Treatment of diet-induced lipodystrophic C57BL/6J mice with long-acting PASylated leptin normalises insulin sensitivity and hepatic steatosis by promoting lipid utilisation

Abstract

Aims/hypothesis Recombinant leptin offers a viable treatment for lipodystrophy (LD) syndromes. However, due to its short plasma half-life, leptin replacement therapy requires at least daily subcutaneous (s.c.) injections. Here, we optimised this treatment strategy in LD mice by using a novel leptin version with extended plasma half-life using PASylation technology. Methods A long-acting leptin version was prepared by genetic fusion with a 600 residue polypeptide made of Pro, Ala and Ser (PASylation), which enlarges the hydrodynamic volume and, thus, retards renal filtration, allowing less frequent injection. LD was induced in C57BL/6J mice by feeding a diet supplemented with conjugated linoleic acid (CLA). Chronic and acute effects of leptin treatment were assessed by evaluating plasma insulin levels, insulin tolerance, histological liver sections, energy expenditure, energy intake and body composition.Results In a cohort of female mice, 4 nmol PAS-leptin (applied via four s.c. injections every 3 days) successfully alleviated the CLA-induced LD phenotype, which was characterised by hyperinsulinaemia, insulin intolerance and hepatosteatosis. The same injection regimen had no measurable effect when unmodified recombinant leptin was administered at an equivalent dose. In a cohort of LD males, a single s.c. injection of PAS-leptin did not affect energy expenditure but inhibited food intake and promoted a shift in fuel selection towards preferential fat oxidation, which mechanistically substantiates the metabolic improvements. Conclusions/interpretation The excellent pharmacological properties render PASylated leptin an agent of choice for refining both animal studies and therapeutic strategies in the context of LD syndromes and beyond.

Leptin Improves Parameters of Brown Adipose Tissue Thermogenesis in Lipodystrophic Mice

“…Previous studies in LD mice showed no effects of leptin treatment on energy expenditure [ 20 , 21 ], body temperature [ 25 ], or on BAT mUcp1 mRNA expression [ 18 ]. The difference with the present study could be due to a number of methodological factors such as LD mouse model (AGPAT −/− mice in [ 20 ], conjugated linoleic acid-treated mice in [ 21 ], and Tg (A-ZIP/F-1) mice in [ 25 ]), the duration of leptin treatment (3-week infusion in [ 20 ], single injection in [ 21 ], and 1-week infusion in [ 25 ]), and/or the method to determine thermogenesis (48 to 80 h energy expenditure measurements in [ 21 , 25 ] and core body temperature measurements by telemetry following torpor induced by an overnight fast in [ 25 ]). The study of Shimomura et al [ 18 ] is the most similar to the present study since the authors also used Tg (aP2-nSREBP1c) mice.…”

“…Leptin treatment to Tg (aP2-nSREBP1c) mice for 12 days was found to reduce food intake, body weight, plasma insulin, and glucose levels as well as liver fat, but had no effect on BAT mUcp1 mRNA expression as determined by Northern blot analysis [ 18 ]. Similarly, while numerous studies have consistently shown that leptin treatment markedly improves glucose homeostasis and fatty liver in various mouse models of LD [ 10 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ], the effects on energy expenditure have been less positive. Specifically, leptin treatment did not affect energy expenditure in mice with LD from conjugated linoleic acid treatment [ 21 ] or deficiency in 1-acylglycerol-3-phosphate O-acyltransferase 2 (AGPAT2) [ 20 ] as well as body temperature in mice with LD due to overexpression of the transcriptional repressor A-ZIP/F-1 [ 25 ].…”

“…Similarly, while numerous studies have consistently shown that leptin treatment markedly improves glucose homeostasis and fatty liver in various mouse models of LD [ 10 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ], the effects on energy expenditure have been less positive. Specifically, leptin treatment did not affect energy expenditure in mice with LD from conjugated linoleic acid treatment [ 21 ] or deficiency in 1-acylglycerol-3-phosphate O-acyltransferase 2 (AGPAT2) [ 20 ] as well as body temperature in mice with LD due to overexpression of the transcriptional repressor A-ZIP/F-1 [ 25 ]. These studies, however, were either limited by their relatively short duration of leptin treatment and/or the rather superficial analysis or lack of analysis of BAT.…”

Recent trends in protein and peptide-based biomaterials for advanced drug delivery

“…Furthermore, this formulation was stable when stored for 22 months at −20°C, indicating how PASylation can contribute to the maintenance of biological stability [ 430 ]. Similarly, PASylation has contributed to the improved half-life and efficacy of numerous proteins including leptin [ 431 , 432 ], erythropoietin [ 433 ], Conversin [ 434 ] and clotting factor VIII [ 435 ].…”

Intermittent fasting: is there a role in the treatment of diabetes? A review of the literature and guide for primary care physicians

“…There are a number of mechanisms believed to contribute to the development of insulin-resistance in obese patients. These include, but are not limited to, systemic chronic inflammation and ectopic lipid deposition [7,9,30,31]. Visceral adipose tissue is known to function as both a paracrine and endocrine organ through the secretion of adipokines [10].…”