Gender dependence of serum soluble Klotho in acromegaly.

OBJECTIVES: In acromegaly, disease activity is biochemically assessed by growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels. However, they are often discrepant, as several factors including gender influence their relationship. We recently found excessively high serum levels of soluble Klotho (sKl) in acromegalic patients, which depended on GH to a comparable extent as IGF-1. To further elucidate the relationship between GH and sKl, we examined the effect of gender on sKl in patients with untreated acromegaly. PATIENTS AND DESIGN: We determined GH, IGF-1 and sKl in sera of 62 consecutive patients with newly diagnosed acromegaly (31 females/31 males, aged 20-85 years). RESULTS: For their given GH excess at presentation with acromegaly, females had lower IGF-1 (490 ± 33 vs 604 ± 33 ng/ml, P = 0·02), but higher sKl [5171 ± 590 vs 3439 ± 431 pg/ml (mean ± SE), P = 0·02] levels than males. In multiple regression analysis, IGF-1 was closely associated with logGH (estimate 139, SE 47, P = 0·005) and BMI (estimate 14·2, SE 4·8, P = 0·005). sKl was closely associated with logGH (estimate 3088, SE 652, P = 0·0001) and gender (estimate 2034, SE 612, P = 0·002), and to a lesser extent with BMI (estimate 174, SE 66, P = 0·01). CONCLUSIONS: For a given GH status, sKl concentrations are higher and IGF-1 concentrations are lower in women than in men. GH is the strongest predictor for both sKl and IGF-1, but gender needs to be considered when using these parameters for monitoring acromegalic patients.

[Panhypopituitarism, Diabetes Insipidus and Bone Pain - Is There a Systemic Disease Behind it?]

INTRODUCTION: A 27-year-old man presented due to unilateral leg pain. He had a history of diabetes insipidus and panhypopituitarism. Laboratory analysis revealed hormonal undersupply. MRI showed a large contrast medium-absorbing mass in the pituitary gland extending into the hypothalamus. FDG-PET/CT examination revealed a hypermetabolic soft tissue lesion around the left femoral shaft. After biopsy of the lesion, a diagnosis of multisystemic Langerhans cell histiocytosis was made.

Postprandial cardiac autonomic function in Prader-Willi syndrome.

CONTEXT: Individuals with Prader-Willi syndrome (PWS) have a high cardiovascular risk, the mechanism of which is unclear. There may be dysfunction in the autonomic nervous system (ANS) in PWS. OBJECTIVE: To measure, as indicators of cardiac autonomic function, postprandial heart rate variability (HRV) and arterial stiffness in adults with PWS. METHODS: Ten adults with PWS were compared with 11 matched healthy obese subjects and 9 healthy lean subjects. Electrocardiographic traces and arterial stiffness were recorded over a period of 10 minutes at -60, 0, 30, 60, 120 and 240 minutes after consumption of a standardized 600-kCal breakfast. Frequency domain analysis was performed using fast Fourier transform to estimate power spectral density in the full spectrum and in low-frequency (LF 0·04-0·15 Hz) and high-frequency (HF 0·15-0·40 Hz) bands. RESULTS: ANCOVA revealed a reduced LF HRV meal response in adults with PWS compared with obese controls, with no differences in HF HRV, LF/HF ratio, heart rate, total power or arterial stiffness meal responses. CONCLUSIONS: This study assessed cardiac autonomic function in adults with PWS compared with matched obese and lean subjects in response to a meal. Results suggest impaired postprandial ANS responsiveness in PWS, which could contribute to both the known increased cardiovascular risk and obesity.

Association of pre- and postoperative αKlotho levels with long-term remission after pituitary surgery for acromegaly.

Soluble αKlotho (sKl) is a disease-specific biomarker that is elevated in patients with acromegaly and declines after surgery for pituitary adenoma. Approximately 25% of patients do not achieve remission after surgery, therefore a risk stratification for patients early in the course of their disease may allow for the identification of patients requiring adjuvant treatment. Growth hormone (GH) and insulin-like growth factor-1 (IGF-1) have been assessed as biomarker for disease activity, however the value of sKl as a predictive biomarker of surgical success has not been evaluated yet. In this study, we measured serum biomarkers before and after transsphenoidal pituitary surgery in 55 treatment-naïve patients. Based on biochemical findings at follow-up (7-16 years), we divided patients into three groups: (A) long-term cure (defined by normal IGF-1 and random low GH (< 1 µg/l) or a suppressed GH nadir (< 0.4/µg/l) on oral glucose testing); (B) initial remission with later disease activity; (C) persistent clinical and/or biochemical disease activity. sKl levels positively related to GH, IGF-1 levels and tumor volume. Interestingly, there was a statistically significant difference in pre- and postoperative levels of sKl between the long-term cure group and the group with persistent disease activity. This study provides first evidence that sKl may serve as an additional marker for surgical success, decreasing substantially in all patients with initial clinical remission while remaining high after surgery in patients with persistent disease activity.

Soluble delta-like 1 homolog decreases in patients with acromegaly following pituitary surgery: A potential mediator of adipogenesis suppression by growth hormone?

OBJECTIVE: GH excess in acromegaly leads to lower fat mass and insulin resistance; both reverse following pituitary surgery. Soluble delta like-1 homolog (sDlk1) inhibits adipocyte differentiation and may mediate the antiadipogenic effects of GH. It is released into the circulation by ectodomain shedding through 'A Disintegrin And Metalloproteinase domain 17' (ADAM17), which also sheds soluble α-Klotho (sKlotho). Klotho is a transmembrane protein, which influences life span. sKlotho inhibits insulin signalling, and is markedly elevated in acromegaly and decreases after surgery. Therefore, we examined if sDlk1 parallels the course of sKlotho, which could explain the well-known changes in fat mass in patients with acromegaly after surgery. DESIGN: We measured serum levels of GH, IGF-1, sDlk1 and sKlotho (both by ELISA) in 42 treatment-naïve acromegaly patients (20 females/22 males) before and 1-3 months after transsphenoidal surgery. Data are presented as median(interquartile range). RESULTS: GH decreased in all patients postoperatively (in 32/42 to <1 ng/ml during oral glucose tolerance testing). Likewise, IGF-1 and sKlotho decreased in all patients, from 587 (432-708) to 195 (133-270) ng/ml, and from 4.0 (2.7-5.9) to 0.7 (0.6-1.2) ng/ml, respectively; sDlk1 fell in 40/42 subjects, from 10.7 (5.8-13.4) to 7.1 (3.7-10.4) ng/ml following pituitary surgery. P < 0.0001 for all parameters. CONCLUSIONS: sDlk1 declined after pituitary surgery in our patients with acromegaly, but to a lesser extent than sKlotho. It remains to be seen whether this may contribute to the well-known postoperative changes in body composition. Our findings may extend beyond the scope of acromegaly, and thus further elucidate mechanisms in the fields of obesity and anti-ageing.

Effect of transsphenoidal surgery on sleep apnoea in acromegaly.

OBJECTIVE: Sleep apnoea syndrome (SAS) is common in acromegaly and both diseases are independently associated with hypertension and insulin resistance contributing to increased morbidity and mortality. Pituitary surgery remains the principal treatment modality in acromegaly. The aim of this study was to assess the prevalence and risk factors of SAS in acromegaly and to analyze the effect of transsphenoidal adenomectomy on SAS and cardiovascular risk factors. SUBJECTS AND METHODS: Thirteen consecutive patients (seven women and six men, aged 25-77 years) with newly diagnosed acromegaly were prospectively studied. Biochemical assessment (IGF-I, GH, acid labile subunit, fasting blood glucose (FBG), insulin), overnight respiratory polygraphy, and an Epworth Sleepiness scale score (ESS) were obtained before and 12 weeks after surgery. SAS was defined by an ESS > or = 10 and > or = 5 apnoeas/hypopnoeas (central or obstructive) per hour. RESULTS: Six of the thirteen (46%) patients had SAS. Risk factors were male gender (83.3 vs 14.3% without SAS) and long disease duration until diagnosis of acromegaly (10.2 +/- 3.2 vs 4.6 +/- 3.6 years, mean +/- S.D.). Ten patients had a homeostasis assessment model score > or = 4 indicating insulin resistance and one had diabetes mellitus requiring insulin. Seven patients had hypertension (> or = 140/90 mmHg). Postoperatively, GH and IGF-I levels decreased, but only five patients were cured. However, SAS resolved in all patients irrespective of whether acromegaly was cured or not. FBG (5.5 +/- 1.2 vs 4.8 +/- 0.4 mmol/l) and systolic blood pressure (150.8 +/- 18.5 vs 130.8 +/- 17.5 mmHg) decreased in all SAS patients. CONCLUSION: We found a high prevalence of SAS in acromegaly patients, in particular, in men and those with long duration of disease. Importantly, a marked reduction of GH excess by transsphenoidal adenomectomy may cure SAS and improve insulin resistance and hypertension.

Liraglutide as add-on therapy to insulin in type 2 diabetes mellitus: a retrospective, observational study from a daily clinical practice setting in Switzerland.

INTRODUCTION: In most patients with type 2 diabetes mellitus (T2DM) and progressive beta-cell insufficiency, insulin therapy is required to achieve sufficient glycemic control. However, insulin therapy may lead to weight gain and increasing risk of hypoglycemia. Glucagon-like peptide-1 receptor agonists are being used as add-on therapy to insulin with favorable metabolic effects. Nonetheless, to date only few studies exist reporting on the combination of liraglutide and insulin with a short follow-up period. The aim of this study was to evaluate the efficacy and safety of liraglutide as add-on to insulin in patients with T2DM over a time period of up to 24-28 months. METHODS: Data of patients with T2DM, treated with insulin and liraglutide at an outpatient clinic in a tertiary referral hospital from October 2009 until December 2011 were retrospectively examined (n = 36). Glycated hemoglobin (HbA1c), weight, total daily insulin dose and side effects were assessed 5-8 months prior to liraglutide, at baseline and at follow-up visits after 3, 6, 12-16 and 24-28 months. RESULTS: Median HbA1c decreased significantly from 7.7% [interquartile range (IQR) 7.0-8.6] at baseline to 6.8% (IQR 6.5-7.7, p = 0.001) at 3 months and 6.9% (IQR 6.3-7.6, p = 0.0001) at 6 months, but re-increased thereafter (at 24-28 months, median 7.5%, IQR 7.1-8.2, p = 1.0). Median weight decreased significantly from 99.8 kg (IQR 81-110) at baseline to 97.7 kg (IQR 81.2-108.2, p = 0.027) at 3 months, but rose again thereafter. Insulin dosage did not change significantly over time. No severe hypoglycemia or major side effects occurred. CONCLUSIONS: In this observational study, adding liraglutide to insulin in daily clinical practice reduced HbA1c significantly within 6 months, but there may be a non-sustainable effect during long-term treatment.

Postprandial metabolism in adults with Prader-Willi syndrome.

OBJECTIVE: Individuals with Prader-Willi syndrome (PWS) are commonly restricted to 60-75% of height-appropriate calorie intake because they rapidly become obese on a normal diet. This study measured changes in energy expenditure, glucose and lipid homeostasis, and metabolic flexibility in response to a meal in PWS adults. METHODS: 11 adults with PWS were compared with 12 adiposity-matched and 10 lean subjects. Indirect calorimetry was conducted at baseline and 210 min after a standardized 600 kCal breakfast to assess energy expenditure and substrate utilization. Circulating glucose, insulin, C-peptide, glucagon, nonesterified fatty acids, and triglycerides were measured up to 240 min. Insulin sensitivity and insulin secretion rate were assessed by HOMA-IR and C-peptide deconvolution, respectively. Body composition was determined by dual-energy X-ray absorptiometry. RESULTS: The PWS group had lower lean mass than the obesity control group. Corrected for lean mass, there were no differences between the PWS and obesity groups in resting metabolic rate or metabolic flexibility. Total and abdominal fat mass, insulin sensitivity, and insulin secretion rate were also similar between these groups. CONCLUSIONS: This study did not detect an intrinsic metabolic defect in individuals with PWS. Rather, lower lean mass, combined with lower physical activity, may contribute to weight gain on an apparent weight-maintenance diet.

Growth hormone and Klotho.

Acromegaly is characterized by excessively high GH and IGF1 levels. Recent data suggest that soluble Klotho (sKlotho) is also elevated in patients with active acromegaly. sKlotho decreases towards normal following removal of the GH-producing pituitary adenoma. The Klotho gene was identified in mice following its accidental disruption by ectopic DNA. It is an ageing suppressor gene of restricted expression (mainly in kidneys, brain, and parathyroid and pituitary glands) encoding a transmembrane protein, mKlotho. mKlotho serves as a co-receptor in fibroblast growth factor 23 (FGF23) signalling. FGF23 promotes urinary phosphate excretion and inhibits the synthesis of calcitriol. The ectodomain of mKlotho is enzymatically released to result in a humoral factor, sKlotho, which exerts systemic effects (on ion channels and signalling pathways), possibly by working as an enzyme that modifies glycans of cell surface glycoproteins. GH enhances renal phosphate reabsorption and calcitriol production, i.e. exerts effects in the proximal tubule opposing those attributed to mKlotho, and attenuates calciuria in the distal tubule similar to sKlotho. sKlotho can be measured in extracellular fluids (serum, urine and cerebrospinal fluid (CSF)) by an ELISA. In line with predominant expression of Klotho in kidneys and choroid plexus, concentrations of sKlotho are particularly high in urine and CSF. Determination of sKlotho in serum and urine (both presumably reflecting GH action on the kidneys) could be used as a supplementary tool in the diagnosis and follow-up of patients with acromegaly. The question arises whether GH exerts selected actions via modifying activities of Klotho.

Impact of Growth Hormone on Cystatin C.

BACKGROUND: Cystatin C (CysC) is an alternative marker to creatinine for estimation of the glomerular filtration rate (GFR). Hormones such as thyroid hormones and glucocorticoids are known to have an impact on CysC. In this study, we examined the effect of growth hormone (GH) on CysC in patients with acromegaly undergoing transsphenoidal surgery. METHODS: Creatinine, CysC, GH and insulin-like growth factor-1 (IGF-1) were determined in 24 patients with acromegaly before and following transsphenoidal surgery. Estimated GFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration formula. RESULTS: In all patients, surgical debulking resulted in decreased clinical disease activity and declining GH/IGF-1 levels. Postoperatively, biochemical cure was documented in 20 out of 24 patients. Creatinine levels (mean ± SEM) increased from 72 ± 3 to 80 ± 3 µmol/l (p = 0.0004) and concurrently, estimated GFR decreased from 99 ± 3 to 91 ± 3 ml/min (p = 0.0008). In contrast to creatinine, CysC levels decreased from 0.72 ± 0.02 to 0.68 ± 0.02 mg/l (p = 0.0008). CONCLUSIONS: Our study provides strong evidence for discordant effects of GH on creatinine and CysC in patients with acromegaly undergoing transsphenoidal surgery, thus identifying another hormone that influences CysC independent of renal function.

Soluble α-klotho: a novel serum biomarker for the activity of GH-producing pituitary adenomas.

OBJECTIVE: Klotho is a lifespan-influencing gene expressed mainly in the kidneys. Soluble α-Klotho (αKL) is released into the circulation. In this study, we present baseline αKL serum levels of patients with acromegaly compared with controls with other pituitary adenomas and assess changes following transsphenoidal surgery. DESIGN: Prospective controlled study. METHODS: We measured soluble αKL (sandwich ELISA) and IGF1 (RIA) in sera of 14 patients (eight females and six males) with active acromegaly and in 22 control patients (13 females and nine males) operated for non-GH-producing pituitary adenomas. Immunohistochemical staining for Klotho was performed in resected adenomas and in normal pituitary tissue samples. RESULTS: Soluble αKL was high in the acromegaly group preoperatively (median 4217 pg/ml, interquartile range (IQR) 1812-6623 pg/ml) and declined after surgery during early follow-up (2-6 days; median 645 pg/ml, IQR 550-1303 pg/ml) (P<0.001) and during late follow-up (2-3 months post-operatively; median 902 pg/ml, IQR 497-1340 pg/ml; P<0.001). In controls, preoperative soluble αKL was significantly lower than in acromegalics, 532 pg/ml (400-677 pg/ml; P<0.001). Following surgery, soluble αKL remained low during early and late follow-up - changes over time within the control group were not statistically significant. These results were independent of age, sex and kidney function. Klotho staining was equal or slightly decreased in GH-positive adenomas compared with controls. CONCLUSION: High soluble αKL serum levels were specific to GH-producing adenomas and decreased rapidly following adenoma removal. Thus, soluble αKL appears to be a new specific and sensitive biomarker reflecting disease activity in acromegaly. Similar Klotho staining patterns in controls and acromegalics suggest that the rise in serum αKL is caused by systemic actions of pituitary GH rather than due to increased expression of Klotho by the pituitary (adenoma).

Moderate amounts of fructose consumption impair insulin sensitivity in healthy young men: a randomized controlled trial.

OBJECTIVE: Adverse effects of hypercaloric, high-fructose diets on insulin sensitivity and lipids in human subjects have been shown repeatedly. The implications of fructose in amounts close to usual daily consumption, however, have not been well studied. This study assessed the effect of moderate amounts of fructose and sucrose compared with glucose on glucose and lipid metabolism. RESEARCH DESIGN AND METHODS: Nine healthy, normal-weight male volunteers (aged 21-25 years) were studied in this double-blind, randomized, cross-over trial. All subjects consumed four different sweetened beverages (600 mL/day) for 3 weeks each: medium fructose (MF) at 40 g/day, and high fructose (HF), high glucose (HG), and high sucrose (HS) each at 80 g/day. Euglycemic-hyperinsulinemic clamps with [6,6]-(2)H(2) glucose labeling were used to measure endogenous glucose production. Lipid profile, glucose, and insulin were measured in fasting samples. RESULTS: Hepatic suppression of glucose production during the clamp was significantly lower after HF (59.4 ± 11.0%) than HG (70.3 ± 10.5%, P < 0.05), whereas fasting glucose, insulin, and C-peptide did not differ between the interventions. Compared with HG, LDL cholesterol and total cholesterol were significantly higher after MF, HF, and HS, and free fatty acids were significantly increased after MF, but not after the two other interventions (P < 0.05). Subjects' energy intake during the interventions did not differ significantly from baseline intake. CONCLUSIONS: This study clearly shows that moderate amounts of fructose and sucrose significantly alter hepatic insulin sensitivity and lipid metabolism compared with similar amounts of glucose.

Effects of a single dose of exenatide on appetite, gut hormones, and glucose homeostasis in adults with Prader-Willi syndrome.

CONTEXT: Prader-Willi syndrome (PWS) is associated with hyperphagia and obesity, without effective pharmacological treatment. Exenatide, recently developed for treatment of type 2 diabetes, induces appetite suppression and weight loss with common side effects. OBJECTIVE: The objective of the study was to investigate the initial safety and effectiveness of exenatide in adult PWS subjects compared with obese controls (OBESE). DESIGN, SETTING, PATIENTS, AND INTERVENTION: Eight PWS and 11 OBESE patients underwent standardized meal studies after a single sc injection of 10 µg exenatide or placebo in a single-blinded, crossover design. MAIN OUTCOME MEASURES: Glucose, insulin, C-peptide, glucagon, peptide YY (PYY; total)/PYY (3-36), glucagon-like peptide-1, and ghrelin (total) were measured fasting and postprandially. Appetite and satiety were assessed by visual analog scales. Energy expenditure (EE) was measured by indirect calorimetry. Side effects were screened during and for 24 h after the meal. RESULTS: PWS and OBESE patients were matched for gender, age, body mass index, and central/total body fat. In both groups, exenatide increased satiety and lowered glucose and insulin levels but increased insulin secretion rate. Side effects were absent in PWS but common in OBESE patients. During the meal, PYY (total) and ghrelin were elevated in PWS patients. Exenatide decreased PYY (total) and glucagon-like peptide-1, whereas ghrelin remained unchanged. Energy expenditure was unchanged by exenatide. CONCLUSIONS: Our pilot study demonstrates that exenatide is well tolerated in PWS patients. It increases satiety independently of measured appetite hormones, exerting glucose lowering, and insulinotropic effects similarly in PWS and OBESE patients. Larger prospective studies should investigate whether chronic exenatide administration will reduce hyperphagia and overweight in PWS patients without side effects.

In adults with Prader-Willi syndrome, elevated ghrelin levels are more consistent with hyperphagia than high PYY and GLP-1 levels.

OBJECTIVE: Prader-Willi syndrome (PWS) is a leading genetic cause of obesity, characterized by hyperphagia, endocrine and developmental disorders. It is suggested that the intense hyperphagia could stem, in part, from impaired gut hormone signaling. Previous studies produced conflicting results, being confounded by differences in body composition between PWS and control subjects. DESIGN: Fasting and postprandial gut hormone responses were investigated in a cross-sectional cohort study including 10 adult PWS, 12 obese subjects matched for percentage body fat and central abdominal fat, and 10 healthy normal weight subjects. METHODS: PYY[total], PYY[3-36], GLP-1[active] and ghrelin[total] were measured by ELISA or radioimmunoassay. Body composition was assessed by dual energy X-ray absorptiometry. Visual analog scales were used to assess hunger and satiety. RESULTS: In contrast to lean subjects (p<0.05), PWS and obese subjects were similarly insulin resistant and had similar insulin levels. Ghrelin[total] levels were significantly higher in PWS compared to obese subjects before and during the meal (p<0.05). PYY[3-36] meal responses were higher in PWS than in lean subjects (p=0.01), but not significantly different to obese (p=0.08), with an additional non-significant trend in PYY[total] levels. There were no significant differences in self-reported satiety between groups, however PWS subjects reported more hunger throughout (p=0.003), and exhibited a markedly reduced meal-induced suppression of hunger (p=0.01) compared to lean or obese subjects. CONCLUSIONS: Compared to adiposity-matched control subjects, hyperphagia in PWS is not related to a lower postprandial GLP-1 or PYY response. Elevated ghrelin levels in PWS are consistent with increased hunger and are unrelated to insulin levels.

Prader-Willi syndrome is associated with activation of the innate immune system independently of central adiposity and insulin resistance.

BACKGROUND: Subjects with Prader-Willi syndrome (PWS) have a reduced life expectancy due to cardiovascular disease. Increased systemic low-grade inflammation is postulated as a contributor, despite reported lower visceral fat mass and increased insulin sensitivity. OBJECTIVES: Our aim was to compare inflammatory markers and arterial stiffness in PWS and adiposity-matched obese control subjects. DESIGN: We conducted a cross-sectional cohort study comparing 12 PWS subjects, 12 obese subjects matched for percentage body fat and central abdominal fat mass, and 10 healthy normal-weight subjects. MAIN OUTCOME MEASURES: Dual-energy x-ray absorptiometry was used to assess body composition, flow cytometry to quantify activation markers on immun e cells, and ELISA for measurement of C-reactive protein, adiponectin, and IL-6. Insulin resistance was estimated by homeostasis model assessment and arterial stiffness by applanation tonometry. RESULTS: PWS and obese subjects had similarly increased homeostasis model assessment and arterial stiffness. Nevertheless, PWS subjects showed significantly higher IL-6 (4.9 + or - 1.0 vs. 2.5 + or - 0.4 pg/ml; P = 0.02) and nonsignificantly higher C-reactive protein (10.5 + or - 3.2 vs. 4.0 + or - 1.0 ng/ml; P = 0.08). Neutrophil activation markers CD66b and CD11b were higher in PWS compared to obese subjects (P < 0.01), reflecting an activated innate immune system. These markers were positively related to central adiposity in lean and obese subjects (r = 0.49; P < 0.05), but not in PWS subjects. CONCLUSIONS: PWS subjects compared to adiposity-matched obese subjects demonstrate similar insulin resistance but increased low-grade inflammation. The dissociation of inflammation and central adiposity suggests that activation of innate immunity may be either a specific genetic feature of PWS or linked to the commonly associated obstructive sleep apnea syndrome, and might offer a treatment target to reduce cardiovascular disease.