Background: 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.
Objective: 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.
Methods: 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
Results: 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.
Conclusion: 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.