Efficacy of metreleptin in obese patients with type 2 diabetes: cellular and molecular pathways underlying leptin tolerance.

OBJECTIVE: Metreleptin has been efficacious in improving metabolic control in patients with lipodystrophy, but its efficacy has not been tested in obese patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: We studied the role of leptin in regulating the endocrine adaptation to long-term caloric deprivation and weight loss in obese diabetic subjects over 16 weeks in the context of a double-blinded, placebo-controlled, randomized trial. We then performed detailed interventional and mechanistic signaling studies in humans in vivo, ex vivo, and in vitro. RESULTS: In obese patients with diabetes, metreleptin administration for 16 weeks did not alter body weight or circulating inflammatory markers but reduced HbA(1c) marginally (8.01 ± 0.93-7.96 ± 1.12, P = 0.03). Total leptin, leptin-binding protein, and antileptin antibody levels increased, limiting free leptin availability and resulting in circulating free leptin levels of ∼50 ng/mL. Consistent with clinical observations, all metreleptin signaling pathways studied in human adipose tissue and peripheral blood mononuclear cells were saturable at ∼50 ng/mL, with no major differences in timing or magnitude of leptin-activated STAT3 phosphorylation in tissues from male versus female or obese versus lean humans in vivo, ex vivo, or in vitro. We also observed for the first time that endoplasmic reticulum (ER) stress in human primary adipocytes inhibits leptin signaling. CONCLUSIONS: In obese patients with diabetes, metreleptin administration did not alter body weight or circulating inflammatory markers but reduced HbA(1c) marginally. ER stress and the saturable nature of leptin signaling pathways play a key role in the development of leptin tolerance in obese patients with diabetes.

Metabolic correction induced by leptin replacement treatment in young children with Berardinelli-Seip congenital lipoatrophy.

OBJECTIVE: Berardinelli-Seip syndrome is a rare congenital lipoatrophy with a severe prognosis and no efficient therapy. Children present with low leptin levels and severe metabolic complications (insulin resistance, elevated triglyceride levels, and hepatic steatosis). The objective of this study was to test safety and efficacy of recombinant-methionyl-human leptin replacement in children with Berardinelli-Seip syndrome before development of severe metabolic disease METHODS: As part of an open trial, recombinant-methionyl-human leptin was given daily for 4 months to children who did not have diabetes and had Berardinelli-Seip congenital lipoatrophy and metabolic complications at a dosage that was meant to achieve physiologic levels. Six boys and 1 girl (age: 2.4-13.6 years), with a mean fasting insulin level of >15 mIU/L and hypertriglyceridemia, were included. RESULTS: At the end of the recombinant-methionyl-human leptin treatment, a 63% reduction of fasting triglycerides level was achieved. A simultaneous 30% increase in insulin sensitivity was seen, and liver volume was reduced by 20.3%. More remarkable, values of insulin sensitivity and triglyceride level were in the reference range in 4 patients. CONCLUSIONS: Leptin replacement is able to reverse metabolic complications in the majority of children with Berardinelli-Seip congenital lipoatrophy and with insulin resistance or dyslipidemia before the development of overt diabetes.