Effects of Metreleptin in Patients with Generalized Lipodystrophy Before vs After the Onset of Severe Metabolic Disease.

CONTEXT: Leptin replacement therapy with metreleptin improves metabolic abnormalities in patients with generalized lipodystrophy (GLD). OBJECTIVE: Determine how timing of metreleptin initiation in the clinical course of GLD affects long-term metabolic health. METHODS: Retrospective analysis of patients ≥ 6 months old with congenital (n=47) or acquired (n=16) GLD treated with metreleptin at the National Institutes of Health since 2001. Least squares means (LSM) for HbA1c, insulin area under the curve (AUC) from oral glucose tolerance tests, triglycerides, urine protein excretion, platelets, transaminases, and aspartate aminotransferase (AST) to Platelet Ratio Index (APRI) for early and late treatment groups, defined by baseline metabolic health, were analyzed during median 72 (24, 108) months follow-up. RESULTS: Compared to late groups, early groups based on metabolic status had higher mean±SEM insulin AUC (20831±1 vs 11948±1), lower HbA1c (5.3±0.3 vs 6.8±0.3%), triglycerides (101±1 vs 193±1 mg/dL), urine protein excretion (85±1.5 vs 404±1.4 mg/24 hr), ALT (30±1 vs 53±1 U/L), AST (23±1 vs 40±1 U/L), and APRI (0.22±1.3 vs 0.78±1.3), and higher platelets (257±24 vs 152±28 K/µL) during follow-up (P<0.05). Compared to patients ≥6 years old at baseline, patients <6 years had lower HbA1c (4.5±0.5 vs 6.4±0.2%) and higher AST (40±1vs 23±1 U/L) during follow (P<0.05). CONCLUSION: Patients with GLD who initiated metreleptin before the onset of severe metabolic complications had better long-term control of diabetes, proteinuria, and hypertriglyceridemia. Early treatment may also result is less severe progression of liver fibrosis, but further histological studies are needed to determine the effects of metreleptin therapy on liver disease.

Insulin Signaling Through the Insulin Receptor Increases Linear Growth Through Effects on Bone and the GH-IGF-1 Axis.

CONTEXT: Childhood overnutrition is associated with increased growth and bone mineral density (BMD) vs the opposite for undernutrition. The role of insulin receptor (InsR) signaling in these phenotypes is unclear. Rare disease patients with hyperinsulinemia and impaired InsR function (homozygous [-/-] or heterozygous [+/-] INSR pathogenic variants, type B insulin resistance [TBIR]) model increased InsR signaling, while patients with intact InsR function (congenital generalized lipodystrophy, CGL) model decreased InsR signaling. OBJECTIVE: This work aimed to understand mechanisms whereby InsR signaling influences growth. METHODS: A cross-sectional comparison was conducted of CGL (N = 23), INSR-/- (N = 13), INSR+/- (N = 17), and TBIR (N = 8) at the National Institutes of Health. Main outcome measures included SD scores (SDS) for height, body mass index, insulin-like growth factor (IGF)-1, and BMD, and IGF binding proteins (IGFBP)-1 and -3. RESULTS: INSR-/- vs CGL had higher insulin (median 266 [222-457] vs 33 [15-55] mcU/mL), higher IGFBP-1 (72 350 [55 571-103 107] vs 6453 [1634-26 674] pg/mL), lower BMI SDS (-0.7 ± 1.1 vs 0.5 ± 0.9), lower height SDS (-1.9[-4.3 to -1.3] vs 1.1 [0.5-2.5]), lower BMD SDS (-1.9 ± 1.4 vs 1.9 ± 0.7), and lower IGFBP-3 (0.37 [0.19-1.05] vs 2.00 [1.45-2.67] µg/mL) (P < .05 for all). INSR +/- were variable. Remission of TBIR lowered insulin and IGFBP-1, and increased IGF-1 and IGFBP-3 (P < .05). CONCLUSION: Patients with hyperinsulinemia and impaired InsR function exhibit impaired growth and lower BMD, whereas elevated InsR signaling (CGL) causes accelerated growth and higher BMD. These patients demonstrate that insulin action through the InsR stimulates direct anabolic effects in bone and indirect actions through the growth hormone (GH)-IGF-1 axis. TBIR patients exhibit abnormalities in the GH axis that resolve when InsR signaling is restored, supporting a causal relationship between InsR and GH axis signaling.

Volanesorsen, an antisense oligonucleotide to apolipoprotein C-III, increases lipoprotein lipase activity and lowers triglycerides in partial lipodystrophy.

BACKGROUND: Partial lipodystrophy (PL) syndromes involve deficiency of adipose tissue, causing severe insulin resistance and hypertriglyceridemia. Apolipoprotein C-III (apoC-III) is elevated in PL and is thought to contribute to hypertriglyceridemia by inhibiting lipoprotein lipase (LPL). OBJECTIVE: We hypothesized that volanesorsen, an antisense oligonucleotide to apoC-III, would decrease apoC-III, increase LPL activity, and lower triglycerides in PL. METHODS: Five adults with PL enrolled in a 16-week placebo-controlled, randomized, double blind study of volanesorsen, 300 mg weekly, followed by 1-year open label extension. RESULTS: Within-subject effects of volanesorsen before and after 16 weeks of active drug are reported due to small sample size. From week 0 to 16, apoC-III decreased from median (25th, 75th %ile) 380 (246, 600) to 75 (26, 232) ng/mL, and triglycerides decreased from 503 (330, 1040) to 116 (86, 355) mg/dL while activation of LPL by subjects' serum increased from 21 (20, 25) to 36 (29, 42) nEq/mL*min. Although, A1c did not change, peripheral and hepatic insulin sensitivity (glucose disposal and suppression of glucose production during hyperinsulinemic clamp) increased and palmitate turnover decreased. After 32-52 weeks of volanesorsen, liver fat decreased. Common adverse events included injection site reactions and decreased platelets. CONCLUSIONS: In PL, volanesorsen decreased apoC-III and triglycerides, in part through an LPL dependent mechanism, and may improve insulin resistance and hepatic steatosis.

Long-Term Effects of Metreleptin in Rabson-Mendenhall Syndrome on Glycemia, Growth, and Kidney Function.

CONTEXT: Rabson-Mendenhall syndrome (RMS) is caused by biallelic pathogenic variants in the insulin receptor gene (INSR) leading to insulin-resistant diabetes, microvascular complications, and growth hormone resistance with short stature. Small, uncontrolled studies suggest that 1-year treatment with recombinant leptin (metreleptin) improves glycemia in RMS. OBJECTIVE: This study aimed to determine effects of long-term metreleptin in RMS on glycemia, anthropometrics, the growth hormone axis, and kidney function. METHODS: We compared RMS patients during nonrandomized open-label treatment with metreleptin (≥ 0.15 mg/kg/day) vs no metreleptin over 90 months (5 subjects in both groups at different times, 4 only in metreleptin group, 2 only in control group). Main outcome measures were A1c; glucose; insulin; 24-hour urine glucose; standard deviation scores (SDS) for height, weight, body mass index (BMI), and insulin-like growth factor 1 (IGF-1); growth hormone; and estimated glomerular filtration rate. RESULTS: Over time, metreleptin-treated subjects maintained 1.8 percentage point lower A1c vs controls (P = 0.007), which remained significant after accounting for changes in insulin doses. Metreleptin-treated subjects had a reduction in BMI SDS, which predicted decreased A1c. Growth hormone increased after metreleptin treatment vs control, with no difference in SDS between groups for IGF-1 or height. Reduced BMI predicted higher growth hormone, while reduced A1c predicted higher IGF-1. CONCLUSION: Metreleptin alters the natural history of rising A1c in RMS, leading to lower A1c throughout long-term follow-up. Improved glycemia with metreleptin is likely attributable to appetite suppression and lower BMI SDS. Lower BMI after metreleptin may also worsen growth hormone resistance in RMS, resulting in a null effect on IGF-1 and growth despite improved glycemia.

Homozygous SHBG Variant (rs6258) Linked to Gonadotropin-Independent Precocious Puberty in a Young Girl.

Sex hormone-binding globulin (SHBG) in the blood is a major determinant of bioactivity for key sex steroids such as testosterone and estradiol. Low serum levels of SHBG have been associated with obesity, polycystic ovaries, and metabolic syndrome, and other states associated with hyperandrogenemia. A 9-year, 6-month-old girl presented with a history of peripheral precocious puberty and aggressive behavior. The patient's SHBG level was remarkably low for her age, at less than 5 nmol/L (reference range for a girl with a bone age of 10 years, 73 nmol/L [SEM = 10]) [1]. On genetic and protein analysis, the patient was found to have a homozygous missense potentially pathogenic variant in the SHBG gene (c.554C>T, p.P185L); her parents were asymptomatic heterozygote carriers. Laboratory investigations supported the possible involvement of this genetic alteration in the patient's phenotype. Various analyses of this variant support its pathogenicity, although the exact mechanism remains unclear. In conclusion, we present a genetic SHBG variant in the homozygote state that may have been associated with gonadotropin-independent precocious puberty in a young girl.

Case Studies in Pediatric Lipid Disorders and Their Management.

CONTEXT: Identification of modifiable risk factors, including genetic and acquired disorders of lipid and lipoprotein metabolism, is increasingly recognized as an opportunity to prevent premature cardiovascular disease (CVD) in at-risk youth. Pediatric endocrinologists are at the forefront of this emerging public health concern and can be instrumental in beginning early interventions to prevent premature CVD-related events during adulthood. AIM: In this article, we use informative case presentations to provide practical approaches to the management of pediatric dyslipidemia. CASES: We present 3 scenarios that are commonly encountered in clinical practice: isolated elevation of low-density lipoprotein cholesterol (LDL-C), combined dyslipidemia, and severe hypertriglyceridemia. Treatment with statin is indicated when the LDL-C is ≥190 mg/dL (4.9 mmol/L) in children ≥10 years of age. For LDL-C levels between 130 and 189 mg/dL (3.4-4.89 mmol/L) despite dietary and lifestyle changes, the presence of additional risk factors and comorbid conditions would favor statin therapy. In the case of combined dyslipidemia, the primary treatment target is LDL-C ≤130 mg/dL (3.4 mmol/L) and the secondary target non-high-density lipoprotein cholesterol <145 mg/dL (3.7 mmol/L). If the triglyceride is ≥400 mg/dL (4.5 mmol/L), prescription omega-3 fatty acids and fibrates are considered. In the case of triglyceride >1000 mg/dL (11.3 mmol/L), dietary fat restriction remains the cornerstone of therapy, even though the landscape of medications is changing. CONCLUSION: Gene variants, acquired conditions, or both are responsible for dyslipidemia during childhood. Extreme elevations of triglycerides can lead to pancreatitis. Early identification and management of dyslipidemia and cardiovascular risk factors is extremely important.

Apolipoprotein CIII and Angiopoietin-like Protein 8 are Elevated in Lipodystrophy and Decrease after Metreleptin.

CONTEXT: Lipodystrophy syndromes cause hypertriglyceridemia that improves with leptin treatment using metreleptin. Mechanisms causing hypertriglyceridemia and improvements after metreleptin are incompletely understood. OBJECTIVE: Determine relationship of circulating lipoprotein lipase (LPL) modulators with hypertriglyceridemia in healthy controls and in patients with lipodystrophy before and after metreleptin. METHODS: Cross-sectional comparison of patients with lipodystrophy (generalized lipodystrophy n = 3; partial lipodystrophy n = 11) vs age/sex-matched healthy controls (n = 28), and longitudinal analyses in patients before and after 2 weeks and 6 months of metreleptin. The study was carried out at the National Institutes of Health, Bethesda, Maryland. Outcomes were LPL stimulators apolipoprotein (apo) C-II and apoA-V and inhibitors apoC-III and angiopoietin-like proteins (ANGPTLs) 3, 4, and 8; ex vivo activation of LPL by plasma. RESULTS: Patients with lipodystrophy were hypertriglyceridemic and had higher levels of all LPL stimulators and inhibitors vs controls except for ANGPTL4, with >300-fold higher ANGPTL8, 4-fold higher apoC-III, 3.5-fold higher apoC-II, 1.9-fold higher apoA-V, 1.6-fold higher ANGPTL3 (P < .05 for all). At baseline, all LPL modulators except ANGPLT4 positively correlated with triglycerides. Metreleptin decreased apoC-II and apoC-III after 2 weeks and 6 months, and decreased ANGPTL8 after 6 months (P < 0.05 for all). Plasma from patients with lipodystrophy caused higher ex vivo LPL activation vs hypertriglyceridemic control plasma (P < .0001), which did not change after metreleptin. CONCLUSION: Elevations in LPL inhibitors apoC-III and ANGPTL8 may contribute to hypertriglyceridemia in lipodystrophy, and may mediate reductions in circulating and hepatic triglycerides after metreleptin. These therefore are strong candidates for therapies to lower triglycerides in these patients.

Free fatty acid processing diverges in human pathologic insulin resistance conditions.

BACKGROUNDPostreceptor insulin resistance (IR) is associated with hyperglycemia and hepatic steatosis. However, receptor-level IR (e.g., insulin receptor pathogenic variants, INSR) causes hyperglycemia without steatosis. We examined 4 pathologic conditions of IR in humans to examine pathways controlling lipid metabolism and gluconeogenesis.METHODSCross-sectional study of severe receptor IR (INSR, n = 7) versus postreceptor IR that was severe (lipodystrophy, n = 14), moderate (type 2 diabetes, n = 9), or mild (obesity, n = 8). Lipolysis (glycerol turnover), hepatic glucose production (HGP), gluconeogenesis (deuterium incorporation from body water into glucose), hepatic triglyceride (magnetic resonance spectroscopy), and hepatic fat oxidation (plasma ß-hydroxybutyrate) were measured.RESULTSLipolysis was 2- to 3-fold higher in INSR versus all other groups, and HGP was 2-fold higher in INSR and lipodystrophy versus type 2 diabetes and obesity (P < 0.001), suggesting severe adipose and hepatic IR. INSR subjects had a higher contribution of gluconeogenesis to HGP, approximately 77%, versus 52% to 59% in other groups (P = 0.0001). Despite high lipolysis, INSR subjects had low hepatic triglycerides (0.5% [interquartile range 0.1%-0.5%]), in contrast to lipodystrophy (10.6% [interquartile range 2.8%-17.1%], P < 0.0001). ß-hydroxybutyrate was 2- to 7-fold higher in INSR versus all other groups (P < 0.0001), consistent with higher hepatic fat oxidation.CONCLUSIONThese data support a key pathogenic role of adipose tissue IR to increase glycerol and FFA availability to the liver in both receptor and postreceptor IR. However, the fate of FFA diverges in these populations. In receptor-level IR, FFA oxidation drives gluconeogenesis rather than being reesterified to triglyceride. In contrast, in postreceptor IR, FFA contributes to both gluconeogenesis and hepatic steatosis.TRIAL REGISTRATIONClinicalTrials.gov NCT01778556, NCT00001987, and NCT02457897.FUNDINGNational Institute of Diabetes and Digestive and Kidney Diseases, US Department of Agriculture/Agricultural Research Service 58-3092-5-001.

Thyroid Hormone Effects on Glucose Disposal in Patients With Insulin Receptor Mutations.

CONTEXT: Patients with mutations of the insulin receptor gene (INSR) have extreme insulin resistance and are at risk for early morbidity and mortality from diabetes complications. A case report suggested that thyroid hormone could improve glycemia in INSR mutation in part by increasing brown adipose tissue (BAT) activity and volume. OBJECTIVE: To determine if thyroid hormone increases tissue glucose uptake and improves hyperglycemia in INSR mutation. DESIGN: Single-arm, open-label study of liothyronine. SETTING: National Institutes of Health. PARTICIPANTS: Patients with homozygous (n = 5) or heterozygous (n = 2) INSR mutation. INTERVENTION: Liothyronine every 8 hours for 2 weeks (n = 7); additional 6 months' treatment in those with hemoglobin A1c (HbA1c) > 7% (n = 4). OUTCOMES: Whole-body glucose uptake by isotopic tracers; tissue glucose uptake in muscle, white adipose tissue (WAT) and BAT by dynamic [18F] fluorodeoxyglucose positron emission tomography/computed tomography; HbA1c. RESULTS: There was no change in whole-body, muscle, or WAT glucose uptake from baseline to 2 weeks of liothyronine. After 6 months, there was no change in HbA1c (8.3 ± 1.2 vs 9.1 ± 3.0%, P = 0.27), but there was increased whole-body glucose disposal (22.8 ± 4.9 vs 30.1 ± 10.0 µmol/kg lean body mass/min, P = 0.02), and muscle (0.7 ± 0.1 vs 2.0 ± 0.2 µmol/min/100 mL, P < 0.0001) and WAT glucose uptake (1.2 ± 0.2 vs 2.2 ± 0.3 µmol/min/100 mL, P < 0.0001). BAT glucose uptake could not be quantified because of small volume. There were no signs or symptoms of hyperthyroidism. CONCLUSION: Liothyronine administered at well-tolerated doses did not improve HbA1c. However, the observed increases in muscle and WAT glucose uptake support the proposed mechanism that liothyronine increases tissue glucose uptake. More selective agents may be effective at increasing tissue glucose uptake without thyroid hormone-related systemic toxicity.Clinical Trial Registration Number: NCT02457897; https://clinicaltrials.gov/ct2/show/NCT02457897.

Advanced Lipoprotein Analysis Shows Atherogenic Lipid Profile That Improves After Metreleptin in Patients with Lipodystrophy.

CONTEXT: Patients with lipodystrophy have dyslipidemia and insulin resistance. Leptin treatment with metreleptin in lipodystrophy decreases insulin resistance and lowers triglycerides without changing high-density lipoprotein. Detailed measurement of lipoprotein particles with nuclear magnetic resonance (NMR) spectroscopy can offer insights into cardiovascular disease (CVD) risk and lipid metabolism beyond a standard lipid panel. We hypothesized that patients with lipodystrophy would have a more atherogenic lipid profile than controls at baseline, which would be ameliorated with metreleptin treatment. OBJECTIVE: To characterize the lipoprotein profile in patients with lipodystrophy compared with controls and to evaluate effects of metreleptin treatment. DESIGN SETTING PATIENTS AND INTERVENTION: Patients with lipodystrophy (N = 17) were studied before and after metreleptin for 2 weeks and 6 months and compared with 51 insulin-sensitive sex-matched controls. MAIN OUTCOME MEASURES: Lipoprotein profiles were measured by NMR with the LP4 deconvolution algorithm, which reports triglyceride-rich lipoprotein particles (TRLPs), high-density lipoprotein particles (HDLPs), and low-density lipoprotein particles (LDLPs). RESULTS: Patients with lipodystrophy had elevated large TRLPs and smaller HDLPs and LDLPs compared with controls. Five patients with lipodystrophy had chylomicrons, compared with zero controls. Metreleptin decreased the size and concentration of TRLPs, eliminated chylomicrons in all but one patient, decreased LDLPs, and increased LDLP size. Metreleptin treatment did not have major effects on HDLPs. CONCLUSIONS: Patients with lipodystrophy had an atherogenic lipoprotein profile at baseline consistent with elevated CVD risk, which improved after metreleptin treatment. The presence of fasting chylomicrons in a subset of patients with lipodystrophy suggests saturation of chylomicron clearance by lipoprotein lipase.

Genetic Tumor Syndromes with Endocrine Involvement: A Compendium and an Update.

Many hereditary and sporadic tumor and other syndromes are associated with endocrine functional and or structural abnormalities. The last few decades have yielded advancements in the field with improvements in diagnostic testing, screening guidelines and novel treatment options. In general, endocrine functional abnormalities and neoplasms share an early age of onset. There remains room for improvement as limited literature exists regarding clinical course, prognosis, and screening for earlier cancer detection. This should allow for more timely intervention, and possibly improved outcomes. The aim of this article is to summarize the current knowledge about prevalence, clinical course, and prognosis of functional and structural pituitary, thyroid, adrenal, and gonadal abnormalities in patients with 17 known syndromic, mostly tumor-predisposing, diseases, wherever possible, we review screening recommendations.

Thyroid Abnormalities in Patients With Extreme Insulin Resistance Syndromes.

CONTEXT: Insulin and leptin may increase growth and proliferation of thyroid cells, underlying an association between type 2 diabetes and papillary thyroid cancer (PTC). Patients with extreme insulin resistance due to lipodystrophy or insulin receptor mutations (INSR) are treated with high-dose insulin and recombinant leptin (metreleptin), which may increase the risk of thyroid neoplasia. OBJECTIVE: The aim of this study was to analyze thyroid structural abnormalities in patients with lipodystrophy and INSR mutations and to assess whether insulin, IGF-1, and metreleptin therapy contribute to the thyroid growth and neoplasia in this population. DESIGN: Thyroid ultrasound characteristics were analyzed in 81 patients with lipodystrophy and 11 with INSR (5 homozygous; 6 heterozygous). Sixty patients were taking metreleptin. RESULTS: The prevalence of thyroid nodules in children with extreme insulin resistance (5 of 30, 16.7%) was significantly higher than published prevalence for children (64 of 3202; 2%), with no difference between lipodystrophy and INSR. Body surface area-adjusted thyroid volume was larger in INSR homozygotes vs heterozygotes or lipodystrophy (10.4 ± 5.1, 3.9 ± 1.5, and 6.2 ± 3.4 cm2, respectively. Three patients with lipodystrophy and one INSR heterozygote had PTC. There were no differences in thyroid ultrasound features in patients treated vs not treated with metreleptin. CONCLUSION: Children with extreme insulin resistance had a high prevalence of thyroid nodules, which were not associated with metreleptin treatment. Patients with homozygous INSR mutation had thyromegaly, which may be a novel phenotypic feature of this disease. Further studies are needed to determine the etiology of thyroid abnormalities in patients with extreme insulin resistance.

Combined pituitary hormone deficiency in a girl with 48, XXXX and Rathke's cleft cyst.

BACKGROUND: Tetrasomy X is a rare chromosomal aneuploidy seen in girls, associated with facial dysmorphism, premature ovarian insufficiency and intellectual disability. A Rathke's cleft cyst (RCC) is a remnant of Rathke's pouch which may cause multiple pituitary hormone deficiencies by exerting pressure on the pituitary gland in the sella. METHODS/RESULTS: The patient was diagnosed with tetrasomy X by karyotyping during infancy. Brain MRI and multiple endocrine stimulation tests revealed RCC and combined pituitary hormone deficiency (growth hormone deficiency, secondary adrenal insufficiency and central hypothyroidism) likely due to RCC. CONCLUSION: We report the first case in the literature of a girl with 48, XXXX and combined pituitary hormone deficiency due to Rathke's cyst.

Genetics of Lipodystrophy.

Lipodystrophy disorders are characterized by selective loss of fat tissue with metabolic complications including insulin resistance, hypertriglyceridemia, and nonalcoholic liver disease. These complications can be life-threatening, affect quality of life, and result in increased health care costs. Genetic discoveries have been particularly helpful in understanding the pathophysiology of these diseases, and have shown that mutations affect pathways involved in adipocyte differentiation and survival, lipid droplet formation, and lipid synthesis. In addition, genetic testing can identify patients whose phenotypes are not clearly apparent, but who may still be affected by severe metabolic complications.

Effects of a home-based walking intervention on mobility and quality of life in people with diabetes and peripheral arterial disease: a randomized controlled trial.

OBJECTIVE: Determine the efficacy of a home-based walking intervention to improve walking ability and quality of life in people with diabetes and peripheral arterial disease (PAD). RESEARCH DESIGN AND METHODS: We conducted a randomized, controlled, single-blind trial within university-affiliated clinics in our local community. We randomized 145 participants (45 women) with diabetes and PAD to our intervention--a 6-month behavioral intervention targeting levels of readiness to engage in routine walking for exercise--versus attention control. Our primary outcome was 6-month change in maximal treadmill walking distance. Secondary outcomes included 3-month change in maximal walking distance, lower limb function (i.e., walking impairment scores), quality of life (Medical Outcomes Short Form Survey), exercise behaviors, depressive symptoms, and self-efficacy at 3 and 6 months. RESULTS: The mean age of participants was 66.5 (SD 10.1) years. Intervention and control groups did not differ significantly in 6-month change in maximal treadmill walking distance (average [SE] 24.5 [19.6] meters vs. 39.2 [19.6] meters; P = 0.60). Among secondary outcomes, for the intervention and control groups, respectively, average walking speed scores increased by 5.7 [2.2] units and decreased by 1.9 [2.8] units (P = 0.03); the mental health quality of life subscale score increased by 3.2 [1.5] and decreased by 2.4 [1.5] units (P = 0.01). CONCLUSIONS: A home-based walking intervention did not improve walking distance but did improve walking speed and quality of life in people with diabetes and PAD. Clinicians should consider recommending home-based walking therapy for such patients.