“Role of the adipocyte hormone leptin in cardiovascular diseases – a study from Chennai based Population”

BACKGROUND: Obesity is currently regarded as a pro-inflammatory condition during which leptin (Ob gene product) might act as a risk factor for Cardiovascular Diseases (CVD) including Acute Myocardial Infarction (AMI). There is a marked increase in circulating leptin concentrations and inflammatory markers such as Tumor Necrosis Factor-α (TNF-α) in AMI patients but still the association of leptin with inflammation during AMI is not known. The present study suggest that elevated levels of leptin might elicit the risk for CVD by signaling for the secretion of inflammatory cytokines especially, TNF-α. METHODS: Blood samples were collected from 100 CVD subjects diagnosed for AMI immediately after their admission to the hospital and serum leptin, insulin, glucose, lipids and inflammatory marker such as TNF-α were measured. 5 ml random (non-fasting) blood was collected from 100 non-CVD (control) subjects and the results obtained in case of AMI subjects were compared with that of the control subjects. The subjects under study included both men and women belonging to the age group of 35 – 75 and they were classified based on their BMI as normal weight, overweight and obese. RESULTS: Circulating levels of leptin are found to be elevated in obese control subjects and in patients with AMI irrespective of their Body Mass Index (BMI). In addition, leptin is also found to be positively correlated to serum triglycerides, insulin and TNF-α in AMI subjects. MANOVA analysis suggests that leptin might influence the synthesis of insulin and TNF-α. This is the first report relating leptin to TNF-α in Chennai based population, India. CONCLUSIONS: Hyperleptinemia might act as a risk marker for AMI. The present study suggests that at elevated levels, leptin may favor atherosclerosis by promoting the synthesis of TNF-α and insulin. However, our report warrants further investigation both in vitro and in vivo to determine the exact mechanism behind the pro-atherogenic role of leptin. The observed positive correlation between leptin and BMI in both AMI and control subjects suggests that obese subjects manifest leptin resistance and hence, they possess a greater risk for the incidence of CVD.