Influence of Overweight and Obesity on Circulating Inflammation-Related microRNA

Increased cardiovascular disease risk and prevalence associated with overweight and obesity is due, in part, to heightened inflammatory burden. The mechanisms underlying adiposity-related amplification of inflammation are not fully understood. Alterations in regulators of inflammatory processes such as microRNAs (miRs), however, are thought to play a pivotal role.

The aim of this study was to determine the influence of overweight and obesity, independent of other cardiovascular risk factors, on circulating expression of miR-34a, miR-126, miR-146a, miR-150 and miR-181b.

Forty-five sedentary, middle-aged (47-64 years) adults were studied: 15 were normal weight (8M/7F; BMI: 23.3 ± 0.3 kg/m2); 15 were overweight (8M/7F; 28.2 ± 0.3 kg/m2); and 15 were obese (7M/8F; 32.3 ± 0.5 kg/m2). All subjects were non-smokers, normotensive and free of overt cardiometabolic disease. Circulating levels of the following inflammation-related miRs: miR-34a, miR-126, miR-146a, miR-150 and miR-181b were determined in plasma using standard RT-PCR techniques. miR expression was normalized to exogenous C. elegans miR-39 and reported as relative expression (AU).

Circulating miR-34a was ~200% higher (P< 0.05) in the obese as compared with normal weight and overweight groups. Whereas, miR-126, miR-146a and miR-150 were significantly lower (~65%) in both the obese and overweight groups than the normal weight group. There were no significant group differences in circulating expression of miR-181b. miR-34a was positively related (r = 0.43; P< 0.05); whereas, miR-126 (r = -0.48), miR-146a (r = -0.33) and miR-150 (r = -0.43) levels were significantly inversely related to BMI.

Overweight and obesity, independent of other cardiometabolic risk factors, negatively influences circulating inflammation-related miRs. Dysregulation of circulating miRs may contribute mechanistically to the heightened inflammatory state associated with overweight and obesity.