Management of Diabetes Mellitus in Acromegaly and Cushing’s Disease with Focus on Pasireotide Therapy

Abstract: Patients suffering from acromegaly and Cushing’s Disease (CD) face the risk of several clinical complications. The onset of diabetes mellitus (DM) is among the most important: exposure to elevated growth hormone or cortisol levels is associated with insulin resistance (IR). DM contributes to increasing cardiovascular risk for these subjects, which is higher compared to healthy individuals. Hyperglycemia may also be caused by pasireotide, a second-generation somatostatin receptor ligand (SRLs), currently used for the treatment of these diseases. Accordingly, with 2014 medical expert recommendations, the management of hyperglycemia in patients with CD and treated with pasireotide is based on lifestyle changes, metformin, DPP-4 inhibitors (DPP-4i) and, subsequently, GLP-1 Receptor Agonists (GLP-1 RAs). There is no position for SGLT2-inhibitors (SGLT2-i). However, a very recent experts’ consensus regarding the management of pasireotide-induced hyperglycemia in patients with acromegaly suggests the use of GLP-1 RAs as first line treatment (in suitable patients) and the use of SGLT2-i as second line treatment in patients with high cardiovascular risk or renal disease. As a matter of fact, beyond the hypoglycemic effect of GLP1-RAs and SGLT2-i, there is increasing evidence regarding their role in the reduction of cardiovascular risk, commonly very high in acromegaly and CD and often tough to improve despite biochemical remission. So, an increasing use of GLP1-RAs and SGLT2-i to control hyperglycemia is desirable in these diseases. Obviously, all of that must be done with due attention in order to minimize the occurrence of adverse events. For this reason, large studies are needed to analyze the presence of potential limitations.

Keywords: acromegaly, Cushing’s disease, pasireotide, hyperglycemia, diabetes mellitus, cardiovascular risk

Introduction

Acromegaly and Cushing’s Disease (CD) are rare but weakening endocrine diseases.

Acromegaly is usually caused by a growth hormone (GH)-secreting pituitary adenoma, with subsequent excess of insulin-like growth factor (IGF-1).1 CD is characterized by hyperproduction of cortisol due to an adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma.2 Impaired glucose metabolism and the onset of DM are common clinical conditions resulting from these diseases. The worsening of glycemic control might also be caused by treatment with somatostatin receptor analogs, more specifically with pasireotide.

Pasireotide, a second-generation somatostatin receptor ligand (SRLs), is currently used for the treatment of acromegaly and CD.3,4

In the management of acromegaly, long-acting pasireotide is recommended at a starting dose of 40 mg monthly (potentially up-titrated to 60 mg) in patients with poorly controlled or uncontrolled disease after failure with first generation SRLs. Several Randomized Control Trials (RCTs) have shown better outcomes in achieving biochemical control compared to octreotide and lanreotide, both in parallel arms as well as in a cross-over evaluation.5,6 In CD, pasireotide is approved for the treatment of persistent hypercortisolism after a surgical procedure or when surgery is not feasible or refused, at a start dose of 0.6 mg twice daily (potentially up titrated to 0.9 mg twice daily).7,8

Hyperglycemia and Increased Cardiovascular Risk in Acromegaly and CD

Impaired glucose metabolism is one of the comorbidities associated with acromegaly and CD, uniquely linked to the pathophysiology of the diseases. As a matter of fact, in acromegaly, the prevalence of altered basal glucose ranges between 7 and 22%, of altered glucose tolerance between 6 and 45%, and of diabetes between 19 and 56%.9 Additionally, disorders of carbohydrate metabolism occur in 14–74% of the patients among the various forms of hypercortisolism while the prevalence of diabetes varies between 21 and 47%.10

The pathogenesis of insulin resistance (IR) in acromegaly is due to multiple factors: GH exerts its effects both directly by inducing gluconeogenesis, glycogenolysis and lipolysis and promoting IR in the liver and peripheral tissues, as well as indirectly through IGF-1.11 GH stimulates the hydrolysis of triglycerides and the production of free fatty acids from adipose tissue, and this increased synthesis of free fatty acids leads to a decrease in insulin-mediated glucose uptake by inhibiting glucose transporters GLUT-1 and GLUT-4.12,13 Moreover, GH suppresses key insulin signaling pathways involved in stimulating glucose transport in muscle and adipose tissue and inhibiting glucose production in the liver.14

The effects of IR secondary to the excess of GH are initially compensated by the increased secretion of insulin from the pancreatic beta cells, which, however, diminishes over time, favoring the onset of prediabetes and diabetes.15,16 Once the beta cell function is affected, the glucose metabolism disorders persist even after the acromegaly is cured.17 Although physiologically IGF-1 improves glucose homeostasis, the chronic excess of GH in acromegaly that causes IR greatly exceeds the possible beneficial effects of IGF-1 on insulin sensitivity.18

Similar to the excess of GH, hypercortisolism affects carbohydrate metabolism mainly in liver, skeletal muscles, and adipose tissue.19 In the liver, excess glucocorticoids stimulate gluconeogenesis by activating numerous genes involved in the hepatic gluconeogenesis, stimulating lipolysis and proteolysis with increasing substrates for gluconeogenesis, potentiating the action of glucagon and inhibiting glycogenogenesis.20

In the muscle, hypercortisolism induces IR by interfering with different components of the insulin-signaling cascade, as well as by stimulating proteolysis and loss of muscle mass. All this reduces the capacity of the muscle to synthesize glycogen and uptake most of the postprandial glucose from circulation.21

Additionally, hypercortisolism causes an increase in visceral obesity and a relative reduction in peripheral adipose tissue, and this “shift” is closely associated with metabolic syndrome and worsens IR. Moreover, the excess of cortisol influences the synthesis and release of hormones from adipose tissue, mainly adipokines, further contributing to the development of IR.21

Glucocorticoids inhibit the synthesis and secretion of insulin. Also in CD, there is an initial transient phase characterized by the increase in insulin secretion as an adaptive mechanism to IR, but later the chronic exposure to higher levels of cortisol induces pancreatic beta cell apoptosis, loss of beta cell function and the subsequent development of diabetes.20,22

The involvement of the bone system in affecting glucose homeostasis has also been found: in fact, long-term exposure to glucocorticoids causes a reduction in circulating osteocalcin that can increase IR.23

Furthermore, two studies in humans24,25 suggested that secretion of incretins (glucagon-like peptide-1, GLP-1 and glucose dependent insulinotropic peptide, GIP) was unaffected by dexamethasone administration, but their insulinotropic effects of on beta-cells were reduced.

The worsening of glycemic control and the onset of DM are also important limitations in the management of some patients treated with pasireotide.26,27 This topic will be further explored in a subsequent paragraph.

As is well known, hyperglycemia contributes to increasing cardiovascular risk, which is already very high in patients with acromegaly or CD.28,29

Cardiovascular disease is the leading cause of death in 23–50% of patients with acromegaly in different studies.9 Hypertension affects about 33% of the patients, ranging from 11 to 54.7%,30 and it is strongly related with typical cardiac implications of acromegaly as valvulopathy, arrhythmias and cardiomyopathy.

In the large Liege Acromegaly Survey database of 3173 acromegalic patients from 10 European countries,31 left ventricular hypertrophy was present in 15.5% at time of diagnosis. The most common manifestations of cardiopathy are biventricular hypertrophy, diastolic-systolic dysfunction, and valvular regurgitation.32 Certainly, the severity of cardiac disease is correlated with age, duration of acromegaly, GH and IGF-1 levels (both vascular growth factors which stimulate collagen deposition) and long-standing hypertension.33 In the worst cases, hypertrophic cardiopathy can evolve into Left Ventricular Systolic Dysfunction (LVSD), the last stage of cardiac disease, with recurring hospitalizations and very high mortality rates.34 Acromegaly is also associated with sleep apnea (ranging from 45 to 80% of the cases).35

Similarly, in CD cardiovascular disease is the leading cause of death: a retrospective study involving 502 patients (83% in remission) with a median follow-up of 13 years36 demonstrated a standardized mortality ratio (SMR) of 3.3 (95% CI 2.6–4.3) for CV disease, in particular 3.6 (95% CI 2.5–5.1) for ischemic cardiac disease and 3.0 (95% CI 1.4–5.7) for stroke. SMR related cardiovascular disease remained higher also after biochemical remission (2.5, 95% CI 1.8–3.4).36 Cardiovascular remodeling caused by hypercortisolism is frequently irreversible: at 5 years post-remission, coronary artery plaques persisted in 27% of subjects vs 3% of control.37 As a result, the risk for ischemic events remains above that of the general population.38

Hypertension is highly prevalent in patients with hypercortisolism: the majority (80–85%) of patients have hypertension at diagnosis and 9% may have required hospital admission because of the hypertension crisis before the diagnosis of hypercortisolism.39 Also, after remission, hypertension results are highly prevalent, as shown in two different studies (50% and 40%, respectively).40,41 Up to 70% of the patients with active CD present abnormal left ventricular mass parameters, whereas systolic and diastolic function were usually normal. Rarely, patients present dilatative cardiopathy and severe HF.42 Moreover, greater incidence of hypokalemia exposes patients to fatal arrhythmias.

Finally, both obesity and dyslipidemia, frequently occurring in these diseases, do not normalize despite biochemical remission.

Mechanisms of Pasireotide-Induced Hyperglycemia

Pasireotide is a multi-receptor targeted SRL, with action on different somatostatin receptors (SSTR). Pasireotide binds with high affinity to SSTR-1, 3 and 5 and lower to SSTR-2 than first generation SSA. More specifically, the affinity for SSTR-5, several times greater than those of octreotide and lanreotide, explains the efficacy of pasireotide: this binding causes the suppression of ACTH and GH, accompanied by tumor volume reduction.43,44

However, this mechanism causes the alteration of glucose metabolism because the binding is not specific to pituitary cells. Stimulation of pancreatic SSTR-5, expressed more in Langerhans islet beta cells than alfa cells (87% vs 44%), suppresses insulin secretion much more than glucagon secretion.45

Pasireotide appears to inhibit the secretion of incretin hormones GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) in health volunteers after oral glucose tolerance test (OGTT),46 even if a recent study showed no differences in incretin levels and their response to mixed meal tolerance test (MMTT) in CD patients,47 suggesting a main role of direct inhibition of beta-cells activity. However, a reduced intra-islet paracrine effect of GLP-1 cannot be excluded whereas an increased IL-6 mediated GLP-1 secretion in CD may disguise pasireotide inhibitory effect.47,48 Furthermore, pasireotide has no effect on hepatic and peripheral insulin sensitivity.46

Pasireotide-induced hyperglycemia is less pronounced following multiple dosing, and it appears even reversible upon discontinuation of the drug,49 as shown in a pharmacokinetic analysis of single-dose administration, in which mean glucose levels increased to 200 mg/dL (11.1 mmol/L) and returned to euglycemia approximately 23 hours later.50

Not all patients treated with pasireotide develop impaired glucose tolerance or DM: the prevalence of these conditions in CD is respectively 21–64% and 20–47%,51 whereas in acromegaly it is 6–45% and 16–65%.9 This suggests that glycemic control prior to the treatment and a preceding DM, could be predictive of the extent of hyperglycemia.

In the PAOLA study6 a fasting blood glucose (FBG) > 100 mg/dL (5.5 mmol/L) at baseline correlated with higher FBG and higher HbA1c during treatment with pasireotide, while patients with acromegaly < 40 years of age were less likely to experience hyperglycemia than older patients.

Moreover, in acromegalic patients, the up-titration to a dose of 60 mg was associated with a 21–36% increased risk of hyperglycemia.52,53 Other factors that could increase the risk of hyperglycemia were a Body Mass Index > 30 kg/m², hypertension and dyslipidemia at baseline.54

Superimposable results were obtained in another Phase III study,55 always performed in subjects with acromegaly: it was reported that up to 45% of patients with baseline FBG between 100 (5.5 mmol/L) and 126 mg/dL (7.0 mmol/L) had FBG levels ≥126 mg/dL (7.0 mmol/L) after 26 months of pasireotide.55

Also, in CD, preexisting DM or impaired glucose tolerance increased the risk of hyperglycemia-related adverse events (AEs) with pasireotide, although severe AEs were not reported.7

A meta-analysis showed a lower frequency of hyperglycemia-related AEs in acromegalic patients treated with pasireotide monthly (57.3–67.0%) in comparison to those who received it twice daily for CD (68.4–73.0%).27 Also, the rate of discontinuation due to hyperglycemia was higher in CD trials (6.0% and 5.3%) than that in acromegaly trials (3.4% and 4.0%).5–7,56 The reasons for these findings are unknown.

On the other hand, it has been acknowledged that other drugs, commonly used for the treatment of acromegaly or CD, may affect glucose metabolism leading to clinical benefits, even during pasireotide therapy. In fact, in acromegalic subjects, cabergoline can improve glucose tolerance,57 whereas pegvisomant reduces fasting glucose levels and improves insulin sensitivity.58,59 Similar results have been highlighted for ketoconazole,60 metyrapone61 and osilodostrat62 in studies involving patients with CD.

Antidiabetic Drugs with Proven Cardiovascular Benefits

The evidence from Cardio Vascular Outcome Trials with GLP-1 RAs and SGLT2-i have revolutionized the management of Type 2 Diabetes Mellitus (T2DM). As reaffirmed in the recent American Diabetes Association-European Association for the Study of Diabetes (ADA-EASD) Consensus, the treatment approach must be holistic and person-centered, with four main areas of interest: glycemic control, weight loss, CV risk reduction and renal protection.63

In a network meta-analysis of 453 trials assessing glucose-lowering medications from nine drug classes, the greatest reductions in HbA1c were seen with GLP-1 RAs.64 Another meta-analysis comparing the effects of glucose-lowering drugs on body weight and blood pressure indicated the greatest efficacy for reducing body weight with GLP-1 RAs, whereas the greatest reduction in blood pressure is seen with the SGLT2-i.65

Among GLP-1 RAs, liraglutide (at a dose of 1.8 mg daily),66 dulaglutide (at a dose 1.5 mg weekly)67 and injectable semaglutide (at a dose of 0.5 and 1 mg weekly)68 reduced the incidence of three point-MACE (Major Adverse Cardiovascular Events) and the progression of CKD (Chronic Kidney Disease) through the reduction of albuminuria.

With regard to SGLT2-i, empagliflozin and canagliflozin reduced the incidence of three point-MACE.69,70 Empagliflozin, dapagliflozin and canagliflozin demonstrated improvement of CKD in trials with specific renal outcomes, and the first two also demonstrated this benefit in patients without T2DM.71–73 Another significant clinical benefit is the reduction of hospitalization for heart failure (HF), demonstrated also in patients without T2DM for empagliflozin and dapagliflozin, both with reduced ejection fraction (HFrEF)74,75 and preserved ejection fraction (HFpEF).76,77

The Current Management of Pasireotide-Induced Hyperglycemia

Several studies, performed with different designs, evaluated the impact of pasireotide on glucose metabolism. The principal results are summarized in Table 1.5–8,78–85

Table 1 Main Studies Regarding the Use of Pasireotide in Acromegaly and in Cushing’s Disease

It’s undeniable that impairment of glucose metabolism occurred: generally, in all studies the number of subjects with diabetes and prediabetes increased, HbA1c levels were higher and anti-hyperglycemic treatments were required. Metformin, DPP-4i and insulin were commonly used to treat hyperglycemia, whereas GLP-1 RAs and SGLT2-i were given only in a small number of cases.

Nevertheless, a recent randomized multicenter study involving 81 patients with acromegaly or CD receiving pasireotide86 and uncontrolled hyperglycemia with metformin or other oral antidiabetic medications (acarbose or sulfonylureas), evaluated the effects of two different regimens of treatment (incretin-based therapy vs insulin). All 38 patients randomized to an incretin-based therapy (acromegaly, n = 26; CD, n =12) received sitagliptin; 28 of them switched to liraglutide. Twelve patients (31.6% [CD, n = 6; acromegaly, n = 6]) randomized to incretin-based therapy received insulin as rescue therapy. The results have shown a trend for better control of HbA1c with incretin-based therapy. Furthermore, in the same study, 109 patients who received pasireotide did not develop hyperglycemia requiring antidiabetic treatment.86 These findings suggest that impaired glucose metabolism or onset of DM during pasireotide therapy are manageable in most patients, without the need for treatment discontinuation.

Accordingly, given the above-mentioned evidence, glycemia should be monitored in all patients treated with pasireotide in order to intercept an initial alteration of glucose metabolism which could be either prediabetes or DM, according to the indications of ADA.87 In patients treated with pasireotide, FBG and HbA1c levels tend to increase during the first 1–3 months of treatment and stabilize thereafter.88

Regarding CD, in 2014, a medical expert recommendation on pasireotide-induced hyperglycemia was published.89 In this, an HbA1c target value less than 7.0–7.5% (53–58 mmol/L) is established, avoiding as much as possible the risk of hypoglycemia. Patients in euglycemia prior to therapy must be monitored: they should self-check FBG and postprandial glucose (PPG) levels during the day, precisely twice in the first week and once weekly later. Instead, patients with prediabetes and DM must be monitored closely (after 1, 2 and 4 weeks), and they should self-check blood glucose values up to six times per day during the first week, and at least four times per day thereafter.26,89

Medical treatment should always include dietary modification and exercise. Metformin is the first line-therapy, unless contraindicated or not tolerated. If glycemic control is not reached or maintained with monotherapy, combination therapy with drugs targeting the incretinic axis is recommended:89 a Phase I study90 in 19 healthy volunteers randomized to pasireotide 600 μg sc bid alone or co-administered with antidiabetic drugs (metformin 500 mg bid, nateglinide 60 mg tid, vildagliptin 50 mg bid and liraglutide 0.6 daily) demonstrated greater effects of vildagliptin and liraglutide in minimizing hyperglycemia.

Therefore, therapy with a DDP-4i is suggested in a first step combination. Only in the case of failure to reach the HbA1c target, the replace of DDP-4i with a GLP-1 RAs is recommended. If pasireotide-induced hyperglycemia remains uncontrolled with combinations containing metformin and DPP-4i or GLP-1 RAs, experts’ recommendations suggest the beginning of basal insulin therapy. If the individual HbA1c targets are not achieved or the postprandial glucose levels remains elevated, prandial insulin can be added.89

Instead, in acromegaly, a very interesting experts’ consensus statement regarding the management of pasireotide-induced hyperglycemia has been recently published.91 It suggests monitoring blood glucose prior to initiation of pasireotide treatment, through the determination of HbA1c or FBG or the execution of OGTT. Patients are divided into three risk categories related to glycemic status: normal glucose tolerance (NGT) patients at low risk, NGT patients at high risk and prediabetic or diabetic patients. In low-risk patients with no worsening of glycemic control, self-measurement of blood glucose (FBG and PPG) once every week is considered sufficient. In high-risk patients who do not have elevated blood glucose levels, weekly self-monitoring (FBG and PPG) is recommended in the first three months. In patients with pre-existing hyperglycemia, daily self-monitoring in recommended with at least one FBG and one PPG, ideally as multiple-point profiles.91 Further, when possible and economically feasible, high-risk patients should temporarily be equipped with continuous glucose monitors (CGMs) to detect elevated blood glucose levels early and determine deviations from the time in range precisely. During treatment with pasireotide, HbA1c measurements should be routinely performed every three months and at least with each IGF-1measurement.91

For the treatment of hyperglycemia, this recent experts’ consensus statement represents an important leap forward from a conceptual point of view. As a matter of fact, glycemic targets are not strictly fixed but an individualized approach for each patient is suggested. Moreover, CV risk is introduced as a factor influencing the choice of antidiabetic drugs.

Obviously, lifestyle intervention (physical activity, healthy sleep, high-quality nutrition) is always suggested. Metformin is indicated as a first-line medication but, considering the high CV risk of acromegalic subjects, GLP-1 RAs with proven CV benefits could also be considered as a first-line treatment. DPP-4i are considered a viable alternative to GLP-1 RAs in case of gastrointestinal side-effects.91

However, studies demonstrated that 10–30% of acromegalic patients show a paradoxical increase in GH (PI-GH) during 75-g OGTT.3 This is probably due to the action of GIP, which is higher in acromegalic patients, particularly in those with hyperglycemia, and that is likely able to increase the secretion of GH.92,93 As is well known, DPP-4i reduce the incretin-degrading enzyme DPP-4 and thus increase the concentration of active incretins, including GIP. Accordingly, a recent study showed that sitagliptin, administered one hour before 75-g OGTT, increase GH in acromegalic patients, especially in those with PI-GH.94 For this reason, acromegalic patients should be carefully monitored for a potential worsening of the underlying disease during treatment with a DPP- 4i.

The use of SGLT2-i is recommended only as second-line treatment for patients with high CV risk and/or renal disease, despite their high prevalence in acromegaly.91 This is justified by the increased risk of diabetic ketoacidosis (DKA), a severe condition related to treatment with SGLT2-i, in acromegalic subjects.95–97 However, patients safely treated with pasireotide and SGLT2-i are reported.98

The addition of insulin may be considered, but it should ideally be used as an adjunct to metformin and at least one other therapeutic agent.

Obviously, in case of poor glycemic control despite treatment with several anti-hyperglycemic drugs, the dose reduction or even the discontinuation of pasireotide should be considered.

A Potential Change of Perspective and Open Issues

Considering the complex cardiovascular profile of patients with acromegaly and CD, a much greater use of GLP-1 RAs and SGLT2-i might be necessary if DM occurs. There are at least three important aspects that support this consideration: glycemic control, cardiovascular protection, and weight loss.

Accordingly, both in acromegaly and CD, the use of GLP-1 RAs contributes to the achievement of these three main goals, providing an important possibility to enhance the quality of life and to decrease the mortality of patients, with evident advantages compared to DDP-4i and insulin.86,91,99 In this regard, co-agonists of GLP-1 and GIP, such as tirzepatide, with their extraordinary impact in terms of HbA1c reduction and weight loss, represent a theoretically intriguing therapeutic option for the future, despite the current lack of data in acromegaly and CD.

SGLT2-i are not included in the expert recommendations for the patients with CD.89 Currently, there is not enough evidence to support their use, even if their impact on cardiorenal risk might be valuable.

The same reasoning could apply to the acromegalic subjects. In particular, the very favorable benefit of SGLT2-i on HF risk could be extremely crucial.

A proposal for an approach to contrasting hyperglycemia, also taking into account the higher cardio-renal risk, in acromegaly and CD is depicted in Figure 1.

Figure 1 Proposal for a new approach to treat hyperglycemia in patients with acromegaly or Cushing’s Disease, with or without pasireotide treatment. The restoration of euglycemia should be achieved with concomitant reduction in terms of weight and cardiovascular risk, improving quality of life and decreasing mortality.

Notes: The choice of anti-hyperglycemic drugs should be driven by high CV risk and not by the concomitant treatment for acromegaly and CD. In patients with dual therapy at baseline (Metformin + SGLT2-i or GLP-1 RAs) and glycemic control not achieved, follow the same indications reported in the figure. Consider DPP-4i in case of intolerance at SGLT2-i and GLP-1 Ras; Consider BASAL INSULIN as first therapy in case of severe glycometabolic state (HbA1c > 10%, FBG > 300 mg/dL, clinical signs of catabolism). In patients with high risk of ketoacidosis and positive anamnesis for recurrent genitourinary infections, SGLT2-i should be avoided.

Potential limits are higher costs and the risk of AEs. It is well known that the most common AEs of GLP-1 RAs are gastrointestinal (nausea, vomiting, and diarrhea) and tend to occur during initiation and dose escalation, diminishing over time.100 Same AEs are noted with pasireotide, even if described as non-severe.

Another AE common to both treatments (pasireotide and GLP-1 RAs) are cholelithiasis and gallbladder disease. Different meta-analysis of RCTs confirmed that GLP1-RAs are associated with an increased risk of cholelithiasis, in the absence of any relevant increase in the risk of pancreatitis and pancreatic cancer.101,102 It is notable that in the study which compared incretin-based and insulin therapy, patients in the latter group had a higher incidence of gallbladder or biliary-related AEs (23.3% vs 13.2%).86

Instead, as reported in the recent consensus about the management of hyperglycemia in acromegaly, a potential limit for the use of SGLT2-i is the risk of DKA, a condition characterized by hyperglycemia, metabolic acidosis and ketosis (pH ≤ 7.3, bicarbonate ≤ 15 mmol/L, anion gap > 12 mmol/L), fortunately rare in acromegaly, considering it concerns only 1% of all cases and it often occurs only in the initial disease manifestation.103 During treatment with SGLT2-i, DKA occurs in the absence of hyperglycemia, and so it also known as euglycemic diabetic ketoacidosis (EuDKA).104 The suggested mechanism behind the EuDKA is the reduction of insulin requirement in patient treated with SGLT2-i due to massive glycosuria, with concomitant increased gluconeogenesis (driven by an increase of glucagon), release of free fatty acid and subsequent propensity to ketone production.105

It is noteworthy that GH and cortisol themselves increase lipolysis, the lipid oxidation rate and so ketone bodies. Moreover, the shift in the insulin/glucagon ratio as observed in pasireotide treatment is thought to be especially prone to this metabolic complication, warranting greater caution.103

It’s essential to consider the higher risk of DKA or EuDKA during treatment with SGLT2-i, but it’s equally necessary to specify that their incidence appears significantly lower compared to that of a fatal cardiovascular event, both in acromegaly and CD. As a matter of fact, a multicenter retrospective study, during 2015–2020, in 9940 persons with T2DM treated with SGLT2-i has shown that the overall prevalence of DKA is around 0.43% (with 0.25% for EuDKA).106 Furthermore, even some real-life evaluations conducted in subjects with Type 1 Diabetes, a clinical condition with a well-known high risk of DKA and in which the use of SGLT2-i is actually contraindicated, have shown similar data: Stougard et al107 have observed an incidence of DKA equal to 0% in patients treated with SGLT2-i whereas Anson et al108 have observed a lower risk of DKA and associated hospitalization in subjects treated with SGLT-2i compared to those treated with GLP-1 RAs (obviously, as an adjunct to insulin therapy).

Additionally, in acromegalic subjects treated with pegvisomant, in monotherapy or in combination with pasireotide, the incidence of the EuDKA should be reduced. In fact, a reciprocal positive interaction could be achieved because SGLT2-i attenuate the hyperglycemic effect by decreased insulin secretion, meanwhile pasireotide in combination with pegvisomant mitigates the hyperglucagonemia induced by SGLT2-i. Also, pegvisomant decreases lipid oxidation via extrahepatic suppression of Growth Hormone Receptor in different tissues.109

Hence, it seems reasonable to encourage the use of SGLT2-i even in acromegalic patients treated with pasireotide, especially in those with well-controlled disease, modest hyperglycemia and undergoing combined treatment with pegvisomant. It should be helpful to advise them to discontinue therapy with SGLT2-i in case of intercurrent illnesses that may cause a reduction in carbohydrates intake and dehydration (eg, infections and gastroenteritis), and to not skip doses in the case of contextual insulin therapy. SGLT2-i should be avoided in patients with poorly controlled disease.

The same considerations could also be applied to patients with poorly controlled CD.

Another potential limit for the use of SGLT2-i, especially in CD patients for the overall increased risk of infection in this disease, is the higher prevalence of genitourinary infections, reported in both clinical trials and real world evidence. These infectious events are usually mild, and their prevalence is related to sex and a prior positive history of genital infections. In fact, the risk appears higher in females, and among them, in those with previous infections.110 Moreover, it is interesting to underline that in the study of McGovern et al110 the use of corticosteroids, a clinical condition similar to CD, higher values of HbA1c were not associated with significant additional infection risk in subjects treated with SGLT2-i.

Therefore, it is good clinical practice to suggest meticulous intimate hygiene to patients treated with SGLT-2i, avoiding the use of this class of drugs in those with positive anamnesis for genitourinary infections, especially for females.

It is also worth noting that neither GLP-1 RAs nor SGLT2-i cause hypoglycemia, another condition that significantly increases cardiovascular risk and mortality, as demonstrated in the ACCORD trial.111

Finally, a recent case report112 showed the positive effect of a combined therapy of GLP-1 RAs and SGLT2-i on pasireotide-induced hyperglycemia in a patient with CD. After the failure of metformin and DPP-4i, multiple daily insulin injections and, after two days, dulaglutide 0.75 mg were initiated. After improvement of glycemic control, 10 mg of empagliflozin was started and insulin discontinued. After 3 months, hypercortisolemia and glucose impairment were well-regulated, and the patient’s health improved overall.112

Despite several limits (not optimal use of insulin, short follow-up, lack of data regarding other parameters), this is an example of a treatment that is not glycemic-centered but focused to prevent and improve hypercortisolemia-related complications.

Needless to say, further investigations are needed to analyze the above-mentioned considerations and to overcome the limited findings available.

Ethics Statement

This article is based on previously conducted studies and does not contain any new studies with human participants or animals performed by any of the authors.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution and considerations, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Funding

The authors did not receive support from any organization for the submitted work.

Disclosure

The authors declare that they have no competing interests in this work.

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Spontaneous Cushing’s Disease Remission Induced by Pituitary Apoplexy

Abstract

Spontaneous remission of Cushing’s disease (CD) is uncommon and often attributed to pituitary tumor apoplexy. We present a case involving a 14-year-old female who exhibited clinical features of Cushing’s syndrome. Initial diagnostic tests indicated CD: elevated 24h urinary cortisol (235 µg/24h, n < 90 µg/24h), abnormal 1 mg dexamethasone overnight test (cortisol after 1 mg dex 3.4 µg/dL, n < 1.8 µg/dL), and elevated adrenocorticotropic hormone concentrations (83.5 pg/mL, n 10-60 pg/mL). A pituitary adenoma was suspected, so a nuclear MRI was performed, with findings suggestive of a pituitary microadenoma. The patient was referred for a transsphenoidal resection of the microadenoma. While waiting for surgery, the patient presented to the emergency department with a headache and clinical signs of meningism. A computed axial tomography of the central nervous system was performed, and no structural alterations were found. The symptoms subsided with analgesia. One month later, she presented again to the emergency department with clinical findings of acute adrenal insufficiency (cortisol level of 4.06 µg/dL), and she was noted to have spontaneous biochemical remission associated with the resolution of her symptoms of hypercortisolism. For that reason, spontaneous CD remission induced by pituitary apoplexy (PA) was diagnosed. The patient has been managed conservatively since the diagnosis and remains in clinical and biochemical remission until the present time, after 10 months of follow-up. There are three unique aspects of our case: the early age of onset of symptoms, the spontaneous remission of CD due to PA, which has been rarely reported in the medical literature, and the fact that the patient presented a microadenoma because there are fewer than 10 clinical case reports of PA associated with microadenoma.

Introduction

Cushing’s disease (CD) is characterized by excessive production of adrenocorticotropic hormone by a pituitary adenoma and represents the most common cause of endogenous Cushing’s syndrome (CS) [1]. CD was first reported in 1912 by Harvey Williams Cushing, and he described 12 cases at the Peter Bent Brigham Hospital in Baltimore [2]. This disease has a global incidence of approximately 2.2 cases per 1,000,000 people and occurs more frequently in women from 20 to 50 years of age [3]. Pituitary apoplexy (PA) is a rare condition that occurs in 2-12% of cases, and it has a high morbidity and mortality rate [4]. We report an interesting case of a woman diagnosed with CD who achieved spontaneous remission of her disease after a PA.

Case Presentation

A 14-year-old female presented with a two-year history of weight gain (32 kg), depression, elevated blood pressure, type 2 diabetes mellitus, and growth failure (height less than the third percentile). Her height was 140 cm, and her BMI was 28.1 (97th percentile). At presentation, she had not yet reached menarche. Physical examination revealed Tanner 2 breast development, acne, hirsutism, moon facies, dorsocervical fat pad, central obesity, and stretch marks. Initial laboratory tests showed hemoglobin A1C of 13%, low-density lipoprotein of 167 mg/dL, triglycerides of 344 mg/dL, high-density lipoprotein of 26 mg/dL, creatinine of 0.4 mg/dL, and elevated liver enzymes. Abdominal ultrasound indicated moderate hepatic steatosis changes.

Given the high suspicion of CS, a hormonal profile was conducted (Table 1), confirming CS and subsequently diagnosing CD. A nuclear MRI revealed a 2.6 × 1.8 mm pituitary lesion (Figure 1), prompting referral for transsphenoidal resection of the pituitary microadenoma.

Laboratories Reference range Initial One month Three months Six months
TSH (mUI/L) 0.35-4.94 2.17 2.01
AM cortisol (µg/dL) 6.02-18.4 17.3 4.06 <0.5 4.7
1 mg DST (µg/dL) <1.8 3.4
8 mg DST (µg/dL) <50% suppression 1.9 (78% suppression)
Urine-free cortisol (µg/24h) <90 235
ACTH (pg/mL) 10-60 83.5 19.2 9.7
IGF-1 (ng/mL) 36-300 293
Table 1: Pertinent laboratory investigation at baseline and follow-up with our patient

ACTH, adrenocorticotropic hormone; DST, dexamethasone suppression test; IGF-1, insulin growth factor-1; TSH, thyroid-stimulating hormone

Axial-view-of-a-T1-MRI-with-contrast-showing-a-sellar-lesion
Figure 1: Axial view of a T1 MRI with contrast showing a sellar lesion

The red arrow shows a microadenoma in relation to the normal pituitary gland.

Approximately one month after the suppression tests and while awaiting surgery, the patient presented to the emergency department with a sudden, severe, holocranial headache accompanied by projectile vomiting and diplopia, suggestive of meningism. A computed axial tomography of the central nervous system was conducted, revealing no structural abnormalities. Symptoms resolved with intravenous analgesia within approximately four to six hours. Subsequently, the patient experienced a significant decrease in insulin requirements, ultimately leading to the suspension of insulin therapy due to persistent hypoglycemia.

Weeks after the headache episode, the patient was reevaluated in the emergency department with a three-day history of diffuse abdominal pain, vomiting, asthenia, myalgia, hypotension, tachycardia, orthostatism, and recurrent hypoglycemia despite insulin suspension. Acute adrenal insufficiency was suspected and confirmed by a cortisol level of 4.06 µg/dL. Treatment with intravenous hydrocortisone 50 mg every six hours was initiated, leading to complete resolution of symptoms within 72 hours. The patient was discharged on maintenance therapy with oral hydrocortisone (20 mg in the morning and 10 mg at night). Subsequent follow-ups showed undetectable cortisol levels. Currently, the patient has been followed up for 10 months post-event, showing persistent clinical and hormonal remission of her disease.

Discussion

CD represents approximately 80% of cases of endogenous hypercortisolism, and pituitary microadenomas are the most common cause of CD in all age groups [5]. CD prevalence is 0.3-6.2 cases per 100,000 people [3], which represents 4.4% of all pituitary adenomas [6], and it is up to five times more likely to occur in women than men. Spontaneous remission of CD is rare, and it is mainly due to the apoplexy of a pituitary tumor [7].

PA is a potentially fatal condition resulting from hemorrhage or necrosis of a pituitary adenoma that produces compression of the surrounding structures with symptoms that can be critical and even fatal [8]. PA affects between 2% and 12% of patients with pituitary adenomas, mainly in nonfunctional macroadenomas [9]. Although the main mechanism of PA is hemorrhage, it can also be due to a hemorrhagic infarction or an infarction without hemorrhage; this last scenario is clinically less aggressive [10]. Among the most important precipitating factors are craniocerebral trauma, pregnancy, thrombocytopenia, coagulopathies, pituitary stimulation tests, drugs such as anticoagulants and estrogens, surgeries that are complicated by hypotension, and radiotherapy [4,11,12].

There are three unique aspects of our case. First, the age of onset is 14 years old. This characteristic has been reported in less than 6% of cases of CD, with a mean age of onset between 12.3 and 14.1 years and a slightly higher incidence in men (63%) [13]. In this population, CD is the most common cause of hypercortisolism, accounting for 75-80% of all cases [14]. Furthermore, our patient presented a significant weight gain, severe compromise in her height, hypertension, depression, and diabetes mellitus, which is compatible with the classic profile described for CD in pediatric ages. It is important to clarify that although type 2 diabetes mellitus is common in adults, it is unusual in the pediatric population [13].

Second, spontaneous remission in CD due to apoplexy has been rarely reported in the past; hence, our case is an important addition to the scant literature on this unusual phenomenon. Although there are characteristics suggestive of PA, such as hyperdense lesions within the pituitary gland and the reinforcing ring, a CT scan has a low sensitivity for detecting pituitary hemorrhage (21-46%); therefore, a negative CT scan does not rule out PA in cases where there is infarction without hemorrhage, a situation that could correspond to our case [15].

The third unique feature of our case is that the stroke occurred in the context of a microadenoma, a situation reported in less than 10 cases in the literature. Despite being a microadenoma, the symptoms of PA were severe, with symptoms of meningism, an intense headache, vomiting, and the development of adrenal insufficiency. Taylor et al. [16] reported a similar case of a 41-year-old female with microadenoma whose PA was associated with severe headache and vomiting.

The main differential diagnosis in our case is cyclical CS (CCS), a disorder that occurs in 15% of CS cases, especially in CD [17]. The diagnosis of CCS is classically established with three peaks and two valleys in cortisol secretion, spontaneous fluctuations, and clinical features of CS [7]. The possibility of CCS was ruled out due to the typical presentation of the PA event and the persistence of hypocortisolism.

Finally, several cases of recurrence of their disease have been described after remission of CS due to AP. Those recurrences usually develop in follow-ups of up to seven years [18]. At the time of the last evaluation (10 months post-PA), the patient remained in remission, but long-term follow-up is required to detect both reactivation and hypopituitarism [19].

Conclusions

CD is a rare entity in the pediatric population, usually associated with a pituitary microadenoma. Spontaneous remission of this disease is very uncommon, but when it occurs, it is mainly due to PA. We describe a case with three unique aspects: CD with an early age of onset of symptoms, spontaneous remission of CD due to PA, which has been rarely reported in the medical literature, and the fact that there are less than 10 clinical case reports of PA associated with microadenoma. It is imperative for clinicians to be aware of this possible outcome in patients with CD.

References

  1. Fleseriu M, Auchus R, Bancos I, et al.: Consensus on diagnosis and management of Cushing’s disease: a guideline update. Lancet Diabetes Endocrinol. 2021, 9:847-75. 10.1016/S2213-8587(21)00235-7
  2. Bray DP, Rindler RS, Dawoud RA, Boucher AB, Oyesiku NM: Cushing disease: medical and surgical considerations. Otolaryngol Clin North Am. 2022, 55:315-29. 10.1016/j.otc.2021.12.006
  3. Giuffrida G, Crisafulli S, Ferraù F, et al.: Global Cushing’s disease epidemiology: a systematic review and meta-analysis of observational studies. J Endocrinol Invest. 2022, 45:1235-46. 10.1007/s40618-022-01754-1
  4. Briet C, Salenave S, Bonneville JF, Laws ER, Chanson P: Pituitary apoplexy. Endocr Rev. 2015, 36:622-45. 10.1210/er.2015-1042
  5. Newell-Price J, Bertagna X, Grossman A, Nieman L: Cushing’s syndrome. Lancet. 2006, 367:1605-17. 10.1016/S0140-6736(06)68699-6
  6. Daly AF, Beckers A: The epidemiology of pituitary adenomas. Endocrinol Metab Clin North Am. 2020, 49:347-55. 10.1016/j.ecl.2020.04.002
  7. Popa Ilie IR, Herdean AM, Herdean AI, Georgescu CE: Spontaneous remission of Cushing’s disease: a systematic review. Ann Endocrinol (Paris). 2021, 82:613-21. 10.1016/j.ando.2021.10.002
  8. Siwakoti K, Omay SB, Inzucchi SE: Spontaneous resolution of primary hypercortisolism of Cushing disease after pituitary hemorrhage. AACE Clin Case Rep. 2020, 6:e23-9. 10.4158/ACCR-2019-0292
  9. Dubuisson AS, Beckers A, Stevenaert A: Classical pituitary tumour apoplexy: clinical features, management and outcomes in a series of 24 patients. Clin Neurol Neurosurg. 2007, 109:63-70. 10.1016/j.clineuro.2006.01.006
  10. Semple PL, De Villiers JC, Bowen RM, Lopes MB, Laws ER Jr: Pituitary apoplexy: do histological features influence the clinical presentation and outcome?. J Neurosurg. 2006, 104:931-7. 10.3171/jns.2006.104.6.931
  11. Turgut M, Ozsunar Y, Başak S, Güney E, Kir E, Meteoğlu I: Pituitary apoplexy: an overview of 186 cases published during the last century. Acta Neurochir (Wien). 2010, 152:749-61. 10.1007/s00701-009-0595-8
  12. Wildemberg LE, Glezer A, Bronstein MD, Gadelha MR: Apoplexy in nonfunctioning pituitary adenomas. Pituitary. 2018, 21:138-44. 10.1007/s11102-018-0870-x
  13. Concepción-Zavaleta MJ, Armas CD, Quiroz-Aldave JE, et al.: Cushing disease in pediatrics: an update. Ann Pediatr Endocrinol Metab. 2023, 28:87-97. 10.6065/apem.2346074.037
  14. Ferrigno R, Hasenmajer V, Caiulo S, et al.: Paediatric Cushing’s disease: epidemiology, pathogenesis, clinical management and outcome. Rev Endocr Metab Disord. 2021, 22:817-35. 10.1007/s11154-021-09626-4
  15. Banerjee AK: Diagnostic imaging: Brain. 2nd edition. Br J Radiol. 2010, 83:450-1.
  16. Taylor HC, McLean S, Monheim K: Resolution of Cushing’s disease followed by secondary adrenal insufficiency after anticoagulant-associated pituitary hemorrhage: report of a case and review of the literature. Endocr Pract. 2003, 9:147-51. 10.4158/EP.9.2.147
  17. Alexandraki KI, Kaltsas GA, Isidori AM, et al.: The prevalence and characteristic features of cyclicity and variability in Cushing’s disease. Eur J Endocrinol. 2009, 160:1011-8. 10.1530/EJE-09-0046
  18. Kamiya Y, Jin-No Y, Tomita K, et al.: Recurrence of Cushing’s disease after long-term remission due to pituitary apoplexy. Endocr J. 2000, 47:793-7. 10.1507/endocrj.47.793
  19. Machado MC, Gadelha PS, Bronstein MD, Fragoso MC: Spontaneous remission of hypercortisolism presumed due to asymptomatic tumor apoplexy in ACTH-producing pituitary macroadenoma. Arq Bras Endocrinol Metabol. 2013, 57:486-9. 10.1590/s0004-27302013000600012

A Promising In Vitro Model to Study Cushing’s Syndrome

Background: In Cushing’s syndrome (CS), chronic glucocorticoid excess (GC) and disrupted circadian rhythm lead to insulin resistance (IR), diabetes mellitus, dyslipidaemia and cardiovascular comorbidities. As undifferentiated, self-renewing progenitors of adipocytes, mesenchymal stem cells (MSCs) may display the detrimental effects of excess GC, thus revealing a promising model to study the molecular mechanisms underlying the metabolic complications of CS.

Methods: MSCs isolated from the abdominal skin of healthy subjects were treated thrice daily with GCs according to two different regimens: lower, circadian-decreasing (Lower, Decreasing Exposure, LDE) versus persistently higher doses (Higher, Constant Exposure, HCE), aimed at mimicking either the physiological condition or CS, respectively. Subsequently, MSCs were stimulated with insulin and glucose thrice daily, resembling food uptake and both glucose uptake/GLUT-4 translocation and the expression of LIPEATGLIL-6 and TNF-α genes were analyzed at predefined timepoints over three days.

Results: LDE to GCs did not impair glucose uptake by MSCs, whereas HCE significantly decreased glucose uptake by MSCs only when prolonged. Persistent signs of IR occurred after 30 hours of HCE to GCs. Compared to LDE, MSCs experiencing HCE to GCs showed a downregulation of lipolysis-related genes in the acute period, followed by overexpression once IR was established.

Conclusions: Preserving circadian GC rhythmicity is crucial to prevent the occurrence of metabolic alterations. Similar to mature adipocytes, MSCs suffer from IR and impaired lipolysis due to chronic GC excess: MSCs could represent a reliable model to track the mechanisms involved in GC-induced IR throughout cellular differentiation.

Introduction

Glucocorticoids (GCs) regulate a variety of physiological processes, such as metabolism, immune response, cardiovascular activity and brain function (12). Chronic excess and dysregulation of GCs induces Cushing’s syndrome (CS), a complex clinical condition characterized by multisystem morbidities such as central obesity, hypertension, type 2 diabetes mellitus, insulin resistance (IR), dyslipidaemia, fatty liver, hypercoagulability, myopathy and osteoporosis (35). In patients with CS, GC secretion does not follow the circadian rhythm and consistently high serum GC levels are observed throughout the day (67).

IR, defined as the reduced ability of insulin to control the breakdown of glucose in target organs, represents the common thread among obesity, metabolic syndrome and type 2 diabetes mellitus (8). GCs induce IR, but the mechanisms are complex and not completely understood. Under physiological conditions, the binding of insulin to its receptor on the cell surface induces the autophosphorylation of tyrosine in the insulin receptor substrate (IRS)-1 subunit with a consequent complex cascade of intracellular signals that leads to the inhibition of glycogen synthase kinase 3, the inhibition of apoptosis and the translocation of glucose transporter 4 (GLUT4) to the cell membrane with consequent glucose uptake (910). Several studies have shown how chronic exposure to high levels of GCs reduces IRS-1 phosphorylation and protein expression, resulting in a lack of GLUT4 translocation and a reduction in glucose uptake in adipose tissue (11). In addition, the chronic excess of GCs increases lipoprotein activity and expression with subsequent release of circulating fatty acids, which, in turn, induce the phosphorylation of serine in IRS-1, thus compromising the mechanisms that lead to glucose transport into the cell (12).

In recent years, the involvement of mesenchymal stem cells (MSCs) in the onset of different pathologies has been addressed, and for some of them, MSCs have been identified as the real target for lasting therapeutic approaches (1314). MSCs are undifferentiated cells inside many tissues that are able to self-renew and differentiate into adipocytes, osteocytes and chondrocytes (15).

Adipose tissue, muscle tissue and bone are compromised in CS, so the involvement of MSCs in CS complications has been hypothesized; this was confirmed by our previous work reporting that MSCs isolated from the skin of patients affected by CS showed an altered wound healing process that is recognized as a clinical manifestation of CS (16).

In this scenario, it is tempting to speculate that the detrimental effects of excess GC could also affect MSCs, which may represent a promising cellular model to study the mechanisms leading to IR. The choice to use MSCs as a model is particularly interesting, since MSCs are the progenitors of mature adipocytes that may inherit and spread dysregulated mechanisms already present in MSCs.

Here, MSCs isolated from the abdominal skin of healthy subjects were treated in vitro with two different GC regimens, mimicking circadian cortisol rhythm and chronic hypercortisolism. Subsequently, cells were stimulated with insulin and glucose three times/day, resembling the normal uptake of food, and both glucose uptake and the expression of selected genes were analyzed to clarify the mechanisms underlying the development of IR and the occurrence of altered carbohydrate and lipid metabolism under chronic exposure to high levels of GCs.

Materials and Methods

Sample Collection

Seven abdominal skin samples were collected from healthy subjects (four males and three females age matched 42.3 ± 3.4) undergoing abdominoplasty at the Clinic of Plastic and Reconstructive Surgery, Università Politecnica delle Marche. Patients gave their informed consent; the study was approved by the Università Politecnica delle Marche Ethical Committee and conducted in accordance with the Declaration of Helsinki. The main demographical and clinical characteristics of enrolled patients are summarized in Table 1.

TABLE 1

www.frontiersin.orgTable 1 Demographical and functional characteristics of enrolled patients.

Isolation and Characterization of MSCs

Cells were isolated from abdominal skin and then cultured with a Mesenchymal Stem Cell Growth Medium bullet kit (MSCGM, Lonza Group® Ltd) as previously described (16) and characterized according to the criteria by Dominici (15). Plastic adherence, immunophenotype and multipotency were tested as already described (1719). After the Oil Red staining, a semiquantitative analysis was carried out by dissolving the staining with 100% isopropanol and the absorbance was measured at 510nm in a microplate reader (Thermo Scientific Multiskan GO Microplate Spectrophotometer, Milano, Italy). In addition, the expression of PPAR-γ (peroxisome proliferator-activated receptor gamma) and C/EBP-α (CCAAT/enhancer-binding protein alpha) was tested by Real time PCR to confirm the adipocytes differentiation. Undifferentiated MSCs were used as control (C-MSCs). Briefly, after 21 days of culture in adipocytes differentiation medium, 2.5×105 cells from the 7 patients were collected; cDNA synthesis and qRT–PCR were carried out as previously described (20). The primer sequences are summarized in Table 2. mRNA expression was calculated by the 2−ΔΔCt method (21), where ΔCt=Ct (gene of interest)—Ct (control gene) and Δ (ΔCt)=ΔCt (differentiated MSCs)—ΔCt (undifferentiated MSCs). Genes were amplified in triplicate with the housekeeping genes RPLP0 (Ribosomal Protein Lateral Stalk Subunit P0) and GAPDH (Glyceraldehyde-3-Phosphate Dehydrogenase) for data normalization. Of the two, GAPDH was the most stable and was used for subsequent normalization. The values of the relative expression of the genes are mean ± SD of three independent experiments.

TABLE 2

www.frontiersin.orgTable 2 Primer sequences.

Experimental Design: In Vitro Reproduction of Both Circadian Rhythm and Chronic Excess GCs and Food Uptake

Cells were treated with two different GC regimens: some were given lower, circadian-decreasing GC doses (Lower and Decreasing Exposure, LDE), some were exposed to persistently higher GC doses (Higher and Constant Exposure, HCE), to mimic in vitro either the preserved circadian rhythm or its pathologic abolishment in CS, as shown in Figure 1A and described in detail below. LDE cells were first exposed (8:00 a.m.-9:50 a.m.) to 500 nM hydrocortisone (MedChemExpress, MCE, Monmouth Junction, NJ, USA) and then to decreasing concentrations by replacing the medium with a fresh medium containing 250 nM hydrocortisone (9:50 a.m.-01:50 p.m.) and 100 nM (01:50 p.m.-05:50 p.m. and 05:50 p.m.-08:00 a.m.) of hydrocortisone (22). To mimic CS, HCE cells were exposed to 500 nM hydrocortisone for 24/24 hours. The 500 nM hydrocortisone medium was replaced with fresh medium at the same time as the physiological condition medium was changed.

FIGURE 1

www.frontiersin.orgFigure 1 (A) In vitro reproduction of preserved versus abolished GC circadian rhythm. (B). Daily experimental design.

Cells were starved and exposed three times/day to 10 mM glucose with or without prestimulation with 1 μM insulin (Sigma–Aldrich, Milano, Italy) to resemble daily food uptake.

Protocol is resumed in Figure 1B.

Cells derived from each single patient were divided into six experimental groups (Exp):

1) Exp 1, GLU: Cells exposed to glucose;

2) Exp 2, INS+GLU: Cells stimulated with insulin before glucose exposure;

3) Exp 3, LDE+GLU: LDE cells treated with glucose;

4) Exp 4, HCE+GLU: HCE cells treated with glucose;

5) Exp 5, LDE+INS+GLU: LDE cells stimulated with insulin before glucose exposure;

6) Exp 6, HCE+INS+GLU: HCE cells stimulated with insulin before glucose exposure.

In detail, cells were seeded in DMEM/F-12+10% FBS (Corning, NY, USA). After 24 hours, the medium was changed, and the cells were starved overnight with Advanced DMEM/F-12 w/o glucose (Lonza) with 0.5% FBS. At 8:00 a.m., starvation medium was replaced with a new medium containing hydrocortisone 500 nM for 30 minutes in groups exposed to GCs. After washing, the cells were glucose starved with KRPH buffer (20 mM HEPES, 5 mM KH2PO4, 1 mM MgSO4, 1 mM CaCl2, 136 mM NaCl and 4.7 mM KCl, pH 7.4) containing 2% BSA (Sigma–Aldrich) and hydrocortisone for 40 minutes. Cells from Exp 2, 5 and 6 were then stimulated with 1 μM insulin (Sigma–Aldrich) for 20 minutes. Finally, 10 mM glucose was added, and the time sampling was after 20 minutes.

The same protocol starting with starvation for 2 hours in DMEM/F-12 w/o glucose was repeated two times during the day, and the hydrocortisone concentration in the medium of LDE and HCE cells varied accordingly.

To evaluate the long-term impact on metabolism and IR, the experiment was performed for three days with repeated sampling times after glucose administration: T1, T2 and T3 at 9:50 a.m., 1:50 p.m., 5:50 p.m. of the first day; T4, T5 and T6 at 9:50 a.m., 1:50 p.m., 5:50 p.m. of the second day; T7 at 1:50 p.m. of the third day (Figure 1A).

The entire experiment (Exp 1-6, from T1 to T7) was repeated thrice, and data are reported as mean± standard deviation (SD) over the three independent experiments.

XTT Assay

To evaluate whether repeated starvation steps and treatments would affect cell viability and consequently influence the measurement of glucose uptake, an XTT assay (Sigma–Aldrich) was initially performed. A total of 3×103 cells/well belonging to Exp 1, 2, 4 and 6 derived from the 7 patients were plated in a 96-well plate and treated as previously described. Another experimental group was included as a control, consisting of cells continuously cultured in starvation medium (STARVED CTRL). The XTT assay was performed at the end of each day (T3, T6 and T7 sampling times) following the manufacturer’s instructions. The experiment was repeated thrice, and data are reported as mean ± SD over the three independent experiments.

MSCs Responsiveness to Insulin

To evaluate whether MSCs were responsive to insulin, glucose uptake and the cellular localization of GLUT4 were first evaluated in MSCs not treated with GCs (Exp 1 and 2) from T1 to T6.

For the glucose uptake assay, 3×103 cells/well were plated in a 96-well plate and treated according to the above protocol; after insulin stimulation, 10 mM of 2-deoxyglucose (2-DG) was added for 20 minutes, and a colorimetric assay was performed following the manufacturer’s instructions. The readings were at 420 nm in a microplate reader (Thermo Scientific Multiskan GO Microplate Spectrophotometer, Milano, Italy).

For the cellular distribution of GLUT4, 1.5×104 cells (Exp 1 and 2 derived from the 7 patients) were seeded in triplicate on coverslips and treated as indicated before until T5 sampling time. Cells were then washed, fixed with 4% PFA and permeabilized for 30 min. Subsequently, cells were incubated with anti-GLUT4 antibody (Santa Cruz Biotechnology, USA) followed by treatment for 30 min with a goat anti-mouse FITC-conjugated antibody (23). Finally, coverslips were mounted on glass slides in Vectashield (Vectorlabs, CA, USA), and confocal imaging was performed using a Zeiss LSM510/Axiovert 200 M microscope with an objective lens at 20× magnification (24). Line scans were acquired excluding nuclear regions, and GLUT4 immunofluorescence was analyzed as described elsewhere.

Effects of Different GC Regimens on Glucose Uptake and GLUT4 Translocation

After having proven that MSCs could function as a cellular model, since they were responsive to insulin, the potential effects of both GC regimens on glucose uptake were evaluated.

Glucose uptake was measured in the experimental groups treated with GCs (Exp 3, 4, 5 and 6 derived from the 7 patients), and GLUT4 translocation was evaluated in cells from Exp 4 and 6 as described above.

Expression of Genes Involved in the Development of IR

The expression of selected genes, such as LIPEATGLIL-6 and TNF-α (coding for hormone-sensitive Lipase E, Adipose TriGlyceride Lipase, InterLeukin-6 and Tumour Necrosis Factor-α, respectively), was evaluated to clarify the mechanisms involved in the development of IR in MSCs (2528). A total of 2.5×105 cells/well belonging to Exp 5 and 6 from the 7 patients were seeded in triplicates in a 6-well plate and treated following the experimental design. Pellets were collected at T2 and T7, which were chosen as sampling times representing acute and chronic exposure to GCs. RNA extraction, cDNA synthesis and qRT–PCR were carried out as previously described (20). The primer sequences are summarized in Table 2. mRNA expression was calculated by the 2−ΔΔCt method (21), where ΔCt=Ct (gene of interest)—Ct (control gene) and Δ (ΔCt)=ΔCt (HCE+INS+GLU)—ΔCt (LDE+INS+GLU). All selected genes were amplified in triplicate with the housekeeping genes RPLP0 and GAPDH for data normalization. Of the two, GAPDH was the most stable and was used for subsequent normalization. The values of the relative expression of the genes are mean ± SD of three independent experiments.

Statistical Analysis

For statistical analysis, GraphPad Prism 6 Software was used. All data are expressed as the mean ± standard deviation (SD). For parametric analysis all groups were first tested for normal distribution by the Shapiro–Wilk test (29) and comparison between 2 groups were performed by unpaired Student’s t test. For two-sample comparisons, significance was calculated by unpaired t-Student’s test while the ordinary one-way ANOVA test was used for multiple comparison (Tukey’s multiple comparisons test). Significance was set at p value < 0.05.

Results

MSCs Isolation and Characterization From Abdominal Skin

MSCs isolated from abdominal skin appeared homogeneous with a fibroblastoid morphology and showed adherence to plastic. According to Dominici’s criteria (17), cells were positive for CD73, CD90 and CD105, and negative for HLA-DR, CD14, CD19, CD34 and CD45.

Cells were also able to differentiate towards osteogenic, chondrogenic and adipogenic lineages. After 7 days of osteogenic differentiation, cells showed alkaline phosphatase activity (Figure 2A), and after 14 days, cells were strongly positive for alizarin red staining (Figure 2B). Chondrogenic differentiation was achieved after 30 days, as shown by safranin-O staining (Figure 2C). MSCs differentiation into adipocytes occurred after 21 days, as evidenced by the presence of lipid vacuoles after oil red staining (Figure 2D). Its quantification confirmed as the amount of lipid vacuoles was higher in differentiated cells than in control cells (C-MSCs; Figure 2E). The expression of PPAR-γ and C/EBP-α was tested after 21 days of culture in differentiating medium and it was higher in differentiated than in undifferentiated MSCs (Figures 2F, G).

FIGURE 2

www.frontiersin.orgFigure 2 Multilineage differentiation of MSCs from abdominal skin. Representative images of MSCs derived from the seven patients and differentiated towards osteogenic lineage as assessed by ALP reaction (A, Scale bar 100μm) and Alizarin red staining (B, Scale bar 100μm); chondrogenic lineage as indicated by Safranin-O staining (C, Scale bar 100 μm); adipocyte lineage as confirmed by Oil red staining (D, Scale bar 100μm); (E) Oil Red staining quantification. Data are expressed as mean ± SD of the absorbance read for undifferentiated and differentiated cells (C-MSCs and DIFF-MSCs respectively). (F, G) Expression of PPAR-γ and C/EBP-α by RT-PCR in differentiated vs undifferentiated MSCs towards adipogenic lineage. Data are expressed as mean ± SD (over three independent experiments) of the X-fold (2−ΔΔCt method) of differentiated MSCs compared to undifferentiated MSCs, arbitrarily expressed as 1, where ΔCt=Ct (gene of interest)—Ct (control gene) and Δ (ΔCt)=ΔCt (DIFF-MSCs)—ΔCt (C-MSCs). Unpaired t-Student’s test; ***p<0.001, ****p<0.0001.

Cell Viability by XTT Assay

Figure 3 shows that the viability of the STARVED CTRL (cells continuously cultured in starvation medium) was significantly increased compared to that of the HCE cells at T3 but not thereafter. Although repeated interventions caused a proliferation block earlier than starvation alone, the different treatments did not interfere with vitality, and further analyses on glucose uptake were unaffected by different cell mortality during the experiment.

FIGURE 3

www.frontiersin.orgFigure 3 XTT test. The bars indicate cells’ viability at T3, T6 and T7 sampling times. One-way ANOVA; **p < 0.01 vs STARVED CTRL inside each time sampling. STARVED CTRL: cells continuously cultured in starvation medium; GLU: Cells exposed to glucose; INS+GLU: Cells stimulated with insulin before glucose exposure; HCE+GLU: HCE (Higher and Constant Exposure) cells treated with glucose; HCE+INS+GLU: HCE cells stimulated with insulin before glucose exposure. Data are expressed as mean ± SD of the absorbance read for MSCs derived from each single patient over three independent experiments.

MSCs Responsiveness to Insulin

As shown in Figure 4, stimulation with insulin significantly increased glucose uptake at T1, T2, T4 and T5, whereas at T3 and T6, the level of glucose uptake did not differ significantly between insulin-treated (Exp2, INS+GLU) and nontreated (Exp1, GLU) cells.

FIGURE 4

www.frontiersin.orgFigure 4 Responsiveness of MSCs to insulin. The bars show the glucose uptake expressed in pM at T1, T2, T3, T4, T5 and T6 in insulin-stimulated or non-stimulated MSCs. Unpaired t-Student’s test; *p < 0.05, **p < 0.01. GLU: Cells exposed to glucose; INS+GLU: Cells stimulated with insulin before glucose exposure. Data are expressed as mean ± SD of the readings for MSCs derived from each single patient over three independent experiments.

Notably, in the absence of insulin, GLUT4 was more localized in the perinuclear area of the cells (Figures 5A, E). Insulin stimulation enhanced GLUT4 translocation towards the plasma membrane (Figures 5B, F).

FIGURE 5

www.frontiersin.orgFigure 5 GLUT4 translocation. Representative confocal images of GLUT4 in MSCs derived from the seven patients and stimulated (B, D) or not (A, C) with insulin and exposed to 500nM of GCs (C, D). The graphs (E–H) show the fluorescence ratio between the edge and the centre of the cell; yellow arrows indicate the portion of cell subjected to analysis. GLU: Cells exposed to glucose; INS+GLU: Cells stimulated with insulin before glucose exposure; HCE+GLU: HCE (Higher and Constant Exposure) cells treated with glucose; HCE+INS+GLU: HCE cells stimulated with insulin before glucose exposure.

Effects of LDE and HCE on GCs on Glucose Uptake and GLUT4 Translocation

In LDE cells, insulin induced a significant increase in glucose uptake at all sampling times (Figure 6). Conversely, GC administration did not interfere with glucose uptake by HCE cells in the acute period (T1, T2) but led to a significant decrease in glucose uptake when prolonged (T3, T5, T6, T7). Accordingly, GLUT4 translocation was inhibited irrespective of insulin stimulation (Figures 5C, G and D, H) in HCE cells.

FIGURE 6

www.frontiersin.orgFigure 6 Glucose uptake in MSCs undergoing a LDE or a HCE to GCs. The bars represent the glucose uptake expressed in pM at T1 (9:50 a.m. first day, A), T2 (1:50 p.m. first day, B), T3 (5:50 p.m. first day, C), T4 (9:50 a.m. second day, D), T5 (1:50 p.m. second day, E), T6 (5:50 p.m. second day, F) and T7(1:50 p.m. third day, G) in MSCs undergoing a LDE or a HCE to GCs and stimulated or not with insulin. One-way ANOVA; *p < 0.05,**p < 0,01,***p < 0,001. LDE+GLU: LDE (Lower and Decreasing Exposure) cells treated with glucose; HCE+GLU: HCE (higher and Constant Exposure) cells treated with glucose; LDE+INS+GLU: LDE cells stimulated with insulin before glucose exposure; HCE+INS+GLU: HCE cells stimulated with insulin before glucose exposure. Data are expressed as mean ± SD of the readings for MSCs derived from each single patient over three independent experiments.

Effect on Lipolysis and Development of IR: Gene Expression

A downregulation of both genes involved in the breakdown of triglycerides to fatty acids (LIPE and ATGL) was found at T2, whereas at T7, their expression was significantly increased in HCE cells compared to LDE cells. At T7, HCE cells showed a significant increase in the expression of both IL-6 and TNF-α genes, whereas at T2, only the expression of TNF-α was lower than that of LDE cells (Figure 7).

FIGURE 7

www.frontiersin.orgFigure 7 Gene expression in MSCs undergoing a LDE or a HCE to GCs. The bars display the expression of genes referred specifically to the development of IR: (A)LIPE(B)ATGL(C): IL-6 and (D): TNF-α at T2 and T7 sampling times. LDE+GLU+INS: LDE (Lower and Decreasing Exposure) cells stimulated with insulin before glucose exposure; HCE+GLU +INS: HCE (higher and Constant Exposure) cells stimulated with insulin before glucose exposure. Data are expressed as mean ± SD (over three independent experiments) of the X-fold (2−ΔΔCt method) of HCE+INS+GLU compared to LDE+INS+GLU arbitrarily expressed as 1, where ΔCt=Ct (gene of interest)—Ct (control gene) and Δ (ΔCt)=ΔCt (HCE+INS+GLU)—ΔCt (LDE+INS+GLU). Unpaired t-Student’s test; *p < 0.05,**p < 0.01,***p < 0.001;****p < 0.0001.

Discussion

The clinical presentation of CS is well established, but the mechanisms underlying the onset of some of its complications, IR above all, have not yet been fully understood and may involve tissue-specific players. As progenitors of specialized cellular lines that are directly implicated in the progression of chronic GC excess-induced damage (such as adipocytes, skeletal muscle cells and osteocytes), MSCs are of particular interest: in a previous study, we showed that MSCs derived from the skin of patients with CS displayed dysregulated inflammatory markers and altered expression of genes related to wound healing, demonstrating not only how they could be a useful cellular model to study this event but also their potential contribution to the development of CS manifestations (16).

With this premise, we hypothesized that MSCs exposed to excess GC encounter altered glucose uptake mechanisms, which are then inherited and consolidated by their derived, specialized cells.

Our work aimed to explore and compare the effects of two different GC regimens (LDE- Lower and Decreasing Exposure- and HCE- Higher and Constant Exposure) on glucose and lipid metabolism in MSCs.

First, MSCs were isolated from abdominal skin and characterized by confirming their undifferentiated state (15). To faithfully reproduce the circadian variations in GC concentrations and food intake, cells were treated by following an articulated protocol (Figure 1).

It is well established that insulin stimulation promotes glucose uptake via GLUT4 translocation (3032) in adipocytes and skeletal muscle cells, but the same mechanism has not yet been demonstrated for MSCs. Therefore, the responsiveness of MSCs to insulin, as well as the involvement of GLUT4 in glucose uptake, were addressed before evaluating the effects of GCs. We demonstrated that the exposure of MCSs to insulin increased their glucose uptake and insulin-induced GLUT4 translocation with mechanisms that are similar to those described for adipocytes and muscle cells by confocal imaging. In contrast to what was previously reported for adipocytes (3334), GLUT4 expression before insulin stimulation occurred in the cytoplasmic, perinuclear and nuclear compartments in a nonvacuolized pattern. The same localization was observed by Tonack et al. in mouse embryonic stem cells (35). As in adipocytes, the protein translocated on the cell surface, favoring glucose uptake after insulin stimulation.

These results opened the second part of the research aimed at evaluating the IR-inducing effects of GCs on MSCs.

MSCs were exposed to two different GC regimens: in LDE cells, insulin stimulation always caused an increase in glucose uptake, confirming that insulin sensitivity of MSCs is not altered when cortisol circadian rhythm is preserved; conversely, in HCE cells, an impaired response to insulin was observed, as demonstrated by their decreased glucose uptake. These observations were also confirmed by confocal data, showing how excess GC blocked the insulin-induced translocation of GLUT4 from the intracellular compartment to the cell surface. Of note, a reduction in glucose uptake was not detected in earlier sampling times (T1, T2) but later (T3, T5, T6, T7). These results, taken together with the lack of GLUT4 translocation, suggest that IR develops over time. The development of IR following chronic exposure to GCs has been widely demonstrated in differentiated cells such as adipocytes, hepatocytes, muscle and endothelial cells (3638), but to our knowledge, this has never been observed in human stem cells before.

Our results are in line with those by Gathercole et al. (12), who reported increased insulin-stimulated glucose uptake in a human immortalized subcutaneous adipocyte line (Chub-S7) after acute exposure to dexamethasone, as well as to hydrocortisone (up to 48 hours, in a dose- and time-dependent manner for the latter), thus proposing that the development of GC-induced obesity was promoted by enhanced adipocyte differentiation. However, it must be noted that although Chub-S7 are not fully differentiated adipocytes, they cannot be considered MSCs.

In our study, MSCs showed transient signs of IR at T3. In our opinion, this finding represents a physiologic phenomenon and is in line with previous findings in healthy volunteers who were administered hydrocortisone at two different time points and whose endogenous cortisol production was suppressed by metyrapone and nutrient intake was controlled by means of a continuous glucose infusion (39): subjects receiving hydrocortisone in the evening showed a more pronounced delayed hyperglycaemic effect than those taking hydrocortisone in the morning (39). Persistent signs of IR in our MSCs appeared even earlier (from T5, after 30 hours of HCE to GCs) than Gathercole’s Chub-S7 (12): the ability of MSCs to develop early documentable and conceptually plausible alterations, which can be tracked even once differentiated, further confirms that they are a reliable model for physiopathology studies.

The relationship between insulin and lipolysis is bidirectional: inhibition of lipolysis is mainly due to insulin (24), but different mechanisms have been identified where increased lipolysis is involved in the impairment of insulin sensitivity (2540). Boden et al. (41) reported that increasing circulating nonesterified fatty acid (NEFA) levels by lipid infusion induced transient IR. To obtain a clearer picture of the possible mechanisms involved in the development of IR in MSCs, we analyzed the expression of LIPE and ATGL genes at different timepoints. We found that HCE cells showed an initial reduction (T2), followed by a significant increase (T7), in the expression of LIPE and ATGL genes compared to LDE cells. The results from previous works on this topic are partially conflicting: Slavin (42) and Villena (43) found upregulated expression of the LIPE and ATGL genes, respectively, after a short treatment with GCs, but studies examining the effects of prolonged GC administration suggested that the acute induction of systemic lipolysis by GCs was not sustained over time (44). However, in these in vitro studies, cells were never treated with insulin, whose counterregulatory effect on lipolysis could not be highlighted. Notably, diabetic patients with CS show an increased activation of lipolysis due to IR (44). Our results fully reflect this scenario, showing that the lipolytic effects are even more marked once insulin levels fail to compensate for associated IR. LIPE and ATGL gene expression was downregulated at T2, when IR had not yet been reached; at T7, when chronic exposure to high GC levels compromised insulin sensitivity, both lipolysis-related enzymes were overexpressed. Of note, increased expression of LIPE and ATGL genes in the presence of IR was also reported by Sumuano et al. in mature adipocytes (37). Given its ability to decrease the tyrosine kinase activity of the insulin receptor, TNF-α is an important mediator of IR in obesity and type 2 diabetes mellitus (26). IL-6 is notably associated with IR by both sustaining low-grade chronic inflammation (45) and impairing the phosphorylation of insulin receptor and IRS-1 (27). In agreement with these statements, TNF-α and IL-6 expression was lower before IR induction (T2) and higher after prolonged exposure (T7) in HCE cells than in LDE cells, further confirming the importance of preserved circadian GC rhythmicity to prevent the occurrence of metabolic alterations.

Conclusions

MSCs derived from skin could be a good human model for studying the toxic effects of GCs. Like mature adipocytes, they are responsive to insulin stimulation that promotes glucose uptake via GLUT4 translocation, and their chronic exposure to excessive levels of GCs induces the development of IR. For differentiated cells, impaired lipolysis is observed in MSCs once IR has arisen. Furthermore, MSCs could be a promising model to track the mechanisms involved in GC-induced IR throughout cellular differentiation. Functional analyses will be necessary to elucidate the mechanisms behind these first descriptive results and overcame the actual weakness of this research. In addition, co-cultures with MSCs and mature adipocytes will be performed to investigate the crosstalk between these two cell types.

Data Availability Statement

The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.

Ethics Statement

The studies involving human participants were reviewed and approved by Università Politecnica delle Marche Ethical Committee. The patients/participants provided their written informed consent to participate in this study.

Author Contributions

Conceptualization, MO and GA. Methodology, MDV and MM. Formal analysis, MDV, VL, and CL. Data curation, GDB and GG. Writing—original draft preparation, MO and MDV. Writing—review and editing, MO, GA, and MM. Supervision, MO and GA. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by 2017HRTZYA_005 project grant.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s Note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

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Keywords: glucocorticoids, MSCs, lipolysis, glucose uptake, insulin resistance

Citation: Di Vincenzo M, Martino M, Lariccia V, Giancola G, Licini C, Di Benedetto G, Arnaldi G and Orciani M (2022) Mesenchymal Stem Cells Exposed to Persistently High Glucocorticoid Levels Develop Insulin-Resistance and Altered Lipolysis: A Promising In Vitro Model to Study Cushing’s Syndrome. Front. Endocrinol. 13:816229. doi: 10.3389/fendo.2022.816229

Received: 16 November 2021; Accepted: 20 January 2022;
Published: 24 February 2022.

Edited by:

Pierre De Meyts, Université Catholique de Louvain, Belgium

Reviewed by:

Jacqueline Beaudry, University of Toronto, Canada
Małgorzata Małodobra-Mazur, Wroclaw Medical University, Poland

Copyright © 2022 Di Vincenzo, Martino, Lariccia, Giancola, Licini, Di Benedetto, Arnaldi and Orciani. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Giorgio Arnaldi, g.arnaldi@univpm.it

These authors have contributed equally to this work and share first authorship

These authors have contributed equally to this work and share last authorship

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

From https://www.frontiersin.org/articles/10.3389/fendo.2022.816229/full

Cortisol Levels Predict Remission in Cushing’s Patients Undergoing Transsphenoidal Surgery

In patients with Cushing’s disease, removing the pituitary tumor via an endoscopic transsphenoidal surgery (TSS) leads to better remission rates than microscopic TSS, according to new research.

But regardless of surgical approach, plasma cortisol levels one day after surgery are predictive of remission, researchers found.

The study, “Management of Cushing’s disease: Changing trend from microscopic to endoscopic surgery,” was published in the journal World Neurosurgery.

Because it improves visualization and accessibility, endoscopic TSS has been gaining popularity over microscopic TSS to remove pituitary tumors in Cushing’s disease patients. Yet, although this surgery has been associated with high remission rates, whether it outperforms microscopic surgery and determining the factors affecting long-term outcomes may further ease disease recurrence after TSS.

A team with the All India Institute of Medical Sciences addressed this topic in 104 patients who underwent surgery from January 2009 to June 2017. Among these patients, 47 underwent microscopic surgery and 55 endoscopic surgery. At presentation, their ages ranged from 9 to 55 (mean age of 28). Also, patients had been experiencing Cushing’s symptoms over a mean duration of 24 months.

Eighty-seven patients showed weight gain. Hypertension (high blood pressure) and diabetes mellitus were among the most common co-morbidities, found in 76 and 33 patients, respectively. Nineteen patients had osteoporosis and 12 osteopenia, which refers to lower-than-normal bone mineral density.

As assessed with magnetic resonance imaging, 68 patients had a microadenoma (a tumor diameter smaller than one centimeter) and 27 had a macroadenoma (a tumor one centimeter or larger). Only two patients had an invasive pituitary adenoma.

Two patients with larger tumors were operated on transcranially (through the skull). The surgery resulted in total tumor removal in 90 cases (86.5%). A blood loss greater than 100 milliliter was more common with endoscopic than with microscopic TSS.

Ten patients developed transient diabetes inspidus, two experienced seizures after surgery, and six of nine patients with macroadenoma and visual deterioration experienced vision improvements after TSS.

The incidence of intraoperative leak of cerebrospinal fluid — the liquid surrounding the brain and spinal cord — was 23.2%, while that of post-operative leak was 7.7% and was more common in microadenoma than macroadenoma surgery (9.8% vs. 5.0%).

Seventeen patients were lost to follow-up and two died due to metabolic complications and infections. The average follow-up was shorter for endoscopic than with microscopic surgery (18 months vs. 35 months).

Among the remaining 85 cases, 65 (76.5%) experienced remission, as defined by a morning cortisol level under 5.0 μg/dL, restored circadian rhythm (the body’s internal clock, typically impaired in Cushing’s patients), and suppression of serum cortisol to below 2 μg/dl after overnight dexamethasone suppression test.

The remission rate was 54.5% in pediatric patients and was higher with endoscopic than with microscopic TSS (88.2% vs. 56.6%). Also, patients with microadenoma showed a trend toward more frequent remission than those with macroadenoma (73.2% vs. 64.3%).

Ten of the remaining 20 patients experienced disease recurrence up to 28 months after surgery. Sixteen cases revealed signs of hypopituitarism, or pituitary insufficiency, which were managed with replacement therapy.

A subsequent analysis found that morning cortisol level on day one after surgery was the only significant predictor of remission. Specifically, a one-unit increase in cortisol lowered the likelihood of remission by 7%. A cortisol level lower than 10.7 μgm/dl was calculated as predicting remission.

Overall, the study showed that “postoperative plasma cortisol level is a strong independent predictor of remission,” the researchers wrote, and that “remission provided by endoscopy is significantly better than microscopic approach.”

From https://cushingsdiseasenews.com/2019/09/24/cortisol-levels-predict-remission-cushings-patients-undergoing-transsphenoidal-surgery/

No Association Between Long-Term Gh Replacement, Comorbidities In Nonfunctioning Pituitary Adenoma

Hammarstrand C, et al. Eur J Endocrinol. 2018;doi:10.1530/EJE-18-0370.

Patients with growth hormone deficiency due to nonfunctioning pituitary adenoma experienced excessive morbidity due to cerebral infarction and sepsis regardless of whether they received long-term GH therapy, whereas treatment was associated with a normal incidence of type 2 diabetes, despite higher BMI and more severe hypopituitarism in treated patients, according to findings from an observational, registry-based study.

“Although growth hormone replacement therapy is well-established and reverses most of the features associated with GH [deficiency], one of the safety concerns is the reduction in insulin sensitivity and the potential risk of developing type 2 diabetes mellitus,” Daniel S. Olsson, MSc, MD, PhD, professor at the Sahlgrenska Academy Institute of Medicine at the University of Gothenburg, Sweden, and colleagues wrote in the study background.

Studies examining whether there is an association have produced mixed results, the researchers wrote, and it remains unknown to what extent GH deficiency — and GH therapy —contribute to the development of type 2 diabetes and other comorbidities, including cerebral infarction, malignant tumors, myocardial infarction or fractures.

Olsson and colleagues analyzed data from 426 patients treated or followed for nonfunctioning pituitary adenoma between 1997 and 2011, selected from the Swedish National Patient Register. Researchers assessed information on tumor treatment, hormone therapy, antihypertensive medication, BMI and duration of GH therapy. For patients with type 2 diabetes, researchers assessed HbA1c values, insulin treatment, oral antidiabetes therapies and lipid-lowering therapies. Researchers followed the cohort through December 2014 or until death. Patients were stratified by use of GH therapy. Researchers calculated standardized incidence ratios (SIRs) based on the observed number of comorbidities among patients with nonfunctioning pituitary adenoma vs. the expected number of comorbidities in the background population.

Within the cohort, 207 patients received GH therapy (145 men) and 219 did not (129 men). Median duration of GH therapy was 11.7 years; mean age at diagnosis was 56 years for treated patients and 65 years for untreated patients. Median follow-up time for treated and untreated patients was 12.2 years and 8.2 years, respectively.

Incidence of cerebral infarction was increased for the whole cohort regardless of GH therapy status, with an SIR of 1.39 (95% CI, 1.03-1.84), and was most evident among 97 patients who underwent radiotherapy, in which 19 cerebral infarctions occurred vs. the expected number of 9.8 (P = .011).

“The study showed an increased overall incidence of cerebral infarction in patients with [nonfunctioning pituitary adenoma] compared to the general population that was related to previous radiotherapy, but not to GH [replacement therapy],” the researchers wrote.

Incidence of myocardial infarction was similar for treated and untreated patients, with SIRs of 1.18 (95% CI, 0.73-1.8) and 1.23 (95% CI, 0.82-1.78), respectively. Incidence of receiving medical treatment for hypertension was also similar between groups.

In assessing incidence of type 2 diabetes, the researchers found that the SIR was higher among untreated patients (1.65; 95% CI, 1.06-2.46) vs. treated patients, who had an SIR similar to the background population (0.99; 95% CI, 0.55-1.63). Treated patients with type 2 diabetes had higher BMI vs. untreated patients with type 2 diabetes (P = .01), according to researchers, and glycemic status was similar among treated and untreated patients.

The incidence of sepsis requiring hospitalization was also similar between treated and untreated patients, with rates for both groups close to double that of the background population (P < .001). Incidence of malignant tumors was not increased for treated or untreated patients when compared against the background population, according to the researchers. – by Regina Schaffer

DisclosuresThe Gothenburg Growth Hormone Database is supported partly through unrestricted grants from Novo Nordisk, Pfizer and Sandoz. Olsson reports he has served as a consultant for Ipsen, Pfizer and Sandoz. Another author reports he has served as a consultant to AstraZeneca and Viropharma/Shire, and received lecture fees from Novo Nordisk, Otsuka and Pfizer.

From https://www.healio.com/endocrinology/neuroendocrinology/news/in-the-journals/%7B0739a3a3-f592-4352-93f0-2ee5b5a89251%7D/no-association-between-long-term-gh-replacement-comorbidities-in-nonfunctioning-pituitary-adenoma