Leptin Improves Cardiac Structure and Function in Patients With Generalized Lipodystrophy

Abstract Lipodystrophy (LD) syndromes are rare disorders of deficient adipose tissue and severe metabolic disease, including insulin resistance, diabetes, and hypertriglyceridemia. LD may affect all adipose depots (generalized LD, GLD) or only some depots (partial LD, PLD). Low adipose mass leads to very low leptin in GLD, and variable leptin in PL. Treatment with exogenous leptin (metreleptin) improves metabolic disease in LD, particularly GLD. Left ventricular (LV) hypertrophy is frequent in LD, especially GLD. The mechanism for hypertrophy in LD is not known and may relate to glucose or lipotoxicity. We hypothesized that metreleptin would improve cardiac abnormalities in LD, and that this would be mediated by improvements in glucose and triglycerides (TG). We analyzed echocardiograms (echo), blood pressure (BP), heart rate (HR), and metabolic parameters in 38 subjects with LD (18 GLD, 20 PLD) who were treated with metreleptin in open-label clinical studies at the National Institutes of Health. 27 had repeat echo after 1y of metreleptin (mean 1.0 ± 0.2y), and 23 after 3 to 5y (mean 3.7±0.6y). In GLD, metreleptin significantly improved metabolic disease, including reduced TG (median(IQR) 740(403–1239), 138(88–196), 211(136–558) mg/dL at baseline, 1y, & 3-5y, P<0.0001), hemoglobin A1c (9.5±3.0, 6.5±1.6, 6.5±1.9% at baseline, 1y, & 3-5y, P<0.001), and insulin resistance by HOMA-IR (34.1 (15.2–43.5), 8.7 (2.4–16.0), 8.9 (2.1–16.4), P<0.001). Only HOMA-IR improved in PLD (P<0.01). Systolic BP and HR decreased after metreleptin in GLD (BP 120±11, 117±10, 109±16 mmHg, P=0.046; HR 89±9, 82±12, 80±16 bpm, P=0.018; at baseline, 1y, 3-5y, respectively) but not PLD. Metreleptin improved cardiac parameters in patients with GLD, including reduced posterior wall thickness (9.8±1.7, 9.1±1.3, 8.3±1.7 at baseline, 1y, & 3-5y, P<0.01), LV mass (140.7±45.9, 128.7±37.9, 110.9±29.1 at baseline, 1y, & 3-5y, P<0.01), and LV mass index (88.6±22.0, 81.6±16.9, 81.6±16.9 at baseline, 1y, & 3-5y, P<0.01). Metreleptin also improved septal e’ velocity, a measure of early diastolic cardiac function, in GLD (8.6±1.7, 10.0±2.1, 10.7±2.4 at baseline, 1y, & 3-5y, P<0.01). All changes remained significant after adjustment for BP. In GLD, multivariate variable selection models suggested that changes in posterior wall thickness and LV mass index related to metreleptin-induced reductions in TG, and changes in septal e’ velocity related to metreleptin-induced reductions in hemoglobin A1c. No changes in echo parameters were seen in PLD. These findings suggest that metreleptin improves cardiac hypertrophy and diastolic function in patients with GLD, and these improvements may be mediated by reduced lipotoxicity and glucose toxicity. The applicability of these findings to a broader, leptin-sufficient population with LV hypertrophy and/or diabetic cardiomyopathy remains to be determined.