Leptin regulates neointima formation after arterial injury through mechanisms independent of blood pressure and the leptin receptor/STAT3 signaling pathways involved in energy balance

Background - Leptin is an adipocyte-derived hormone critical for energy homeostasis and implicated in vascular disease processes. The relevant cellular leptin receptor pools and signaling pathways involved in leptin-related vascular phenotypes in vivo are unclear. Methods and Results - Arterial injury was induced in wild-type (wt), leptin-deficient (lep(ob/ob)), and leptin receptor deficient (lepr(db/db)) mice. Compared with wt mice, lep(ob/ob) and lepr(db/db) mice were protected from the development of neointima. Bone marrow transplantation experiments between wt and lepr(db/db) mice indicated that the vascular protection in lepr(db/db) mice was not attributable to lack of leptin receptor expression on bone marrow - derived elements. To investigate the role of the lepr-mediated signal transducer and activator of transcription 3 (STAT3) signaling pathway in the response to vascular injury, lepr(s/s) mice homozygous for a leptin receptor defective in STAT3 signaling underwent femoral arterial injury. Despite similar obesity and blood pressure levels, the neointimal area in lepr(s/s) mice was significantly increased compared with lepr(db/db) mice. Conclusions - The molecular mechanism by which the leptin receptor mediates neointima formation and vascular smooth muscle cell proliferation is largely independent of the STAT3-dependent signaling pathways involved in energy balance.