Systemic and Local Leptin Resistance in Patients with Cardiovascular Diseases

Background/Objectives: The causes and mechanisms underlying the development of leptin resistance (LR) in patients with cardiovascular disease (CVD) remain unknown. Investigating the characteristics of adipose tissue in patients with CVD is a relevant scientific problem that may help to uncover the missing links in the pathogenesis of LR. This study aimed to evaluate systemic and local markers of LR in patients with different forms of CVD, and to determine the prevalence and tissue-specific expression patterns that contribute to LR. Methods: The study included 108 patients with myocardial infarction (MI), 96 patients with chronic coronary heart disease (CHD), and 96 patients with acquired heart disease (AHD). On day 1 of admission to the hospital, leptin and leptin receptor concentrations and the serum-free leptin index (FLI) were measured. Leptin resistance (LR) was defined as a leptin level of >6.45 ng/mL and FLI of >25. In chronic CHD and AHD patients, LEP, LEPR1, LEPR2, LEPR2/2, LEPR3, LEPR3/2, and LEPR4 expression as well as leptin and soluble leptin receptor secretion were assessed in subcutaneous (SAT), epicardial (EAT), and perivascular (PVAT) adipose tissue. Results: MI and chronic CHD patients are characterized by elevated leptin levels and high FLI values in the blood serum, which indicates a high prevalence of LR, in contrast to AHD patients. In chronic CHD, the LR level was highest in EAT and moderate in SAT. Reduced leptin sensitivity in EAT is underlied by decreased expression of LEPR1, LEPR2, LEPR2/2, LEPR3, LEPR3/2, and LEPR4, and increased leptin production by epicardial adipocytes, which contributes to enhancement of leptin resistance at the systemic level. Conclusions: A high LR rate was detected in patients with MI and chronic CHD. The identified changes in EAT lead to the development of leptin resistance in chronic CHD patients.