Leptin Inhibition Ameliorates Renal Mitochondrial Dysfunction And Associated Renal Injury In Polycystic Ovary Syndrome

Abstract

Background: Polycystic ovary syndrome (PCOS) is characterized by hyperandrogenism and polycystic ovaries. Renal injury, increased central adiposity and higher circulating levels of the adipokine leptin are common characteristics of PCOS. Leptin has direct renal fibrotic, hypertrophic, and albuminuric effects and can cause renal mitochondrial dysfunction and oxidative stress leading to chronic kidney disease development. Despite increased circulating leptin level in both lean and obese PCOS women, its role in PCOS-mediated renal damage remains unknown. In a well-characterized mouse model of PCOS, we aimed to test the hypothesis that hyperandrogenemia increases central adiposity leading to hyperleptinemia, which via leptin receptors induces intrarenal mitochondrial oxidative stress and dysfunction causing renal injury. Methods: Three-week-old peripubertal female mice were implanted with Silastic tubes filled with the non-aromatizable androgen dihydrotestosterone (DHT, 8 mg) or vehicle for 12 weeks. Eight weeks post-Silastic tubes implantation, the animals were treated with the leptin receptor antagonist (LepR-Ant) pegylated leptin (2 mg/kg, ip, 3x/week) for 4 weeks. Body weight, fat mass (EchoMRI), kidney weight (gravimetry), plasma leptin (ELISA), the glomerular filtration rate (GFR, transcutaneous fluorescence), as well as the renal injury markers urinary albumin to creatinine ratio (UACR, clinical chemistry analyzer), NGAL, and KIM1 (ELISA) were measured. Freshly isolated kidney mitochondria were used to measure mitochondrial reactive oxygen species (mtROS) by Amplex Red assay. Moreover, mitochondrial complex I and complex II-driven respiration and complex IV activity were assessed using Oroboros Fluorespirometer. Results: DHT significantly (p<0.05) increased body weight (31.6 ± 2.3 vs. 23.6 ± 0.5 g), fat mass (3.5 ± 0.6 vs. 1.9 ± 0.4 g), kidney weight (365.6 ± 13.1 vs. 257.1 ± 3.7 mg), leptin (3.7-fold), UACR (1013.3 ± 56.4 vs. 658.9 ± 103.6 μg albumin/g creatinine), NGAL (6-fold), and KIM1 (3.7-fold). Moreover, PCOS mice had significantly (p<0.05) lower GFR (1067.2 ± 59.9 vs. 1335.6 ± 60.3 uL/min/100g body weight), higher mtROS driven by complexes I (3.8 ± 0.8 vs. 2.0 ± 0.3 % electron leak) and III (8.0 ± 1.8 vs. 3.7 ± 0.9 % electron leak), as well as lower complexes I, II, and IV respiration (43-71%). The LepR-Ant had no effect on kidney weight or GFR; however, it abolished DHT-induced increases in body weight and fat mass. Excitingly, the LepR-Ant inhibited mtROS generation and completely restored complex I and II respiration, which was associated with a significant reduction in the urinary renal injury markers UACR, NGAL, and KIM-1 levels (40-60%, p<0.05). Conclusion and significance: Our findings suggest that leptin via its receptor activation plays a significant role in the renal outcomes in PCOS by inducing mitochondrial dysfunction. Leptin receptor blockade could be a novel therapeutic approach to ameliorate renal injury in PCOS. Supported by NIH grants NIGMS P20GM121334 to KSE, LLYC, and DGR, NIGMS P20GM104357, NHLBI P01HL51971, and American Heart Association Predoctoral Fellowship 903804 (A.M.H.). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.