Plasma Fatty Acid Composition Was Associated with Apelin Gene Expression in Human Adipose Tissues

Abstract

Background. Apelin is an adipokine with an intermediatory role in obesity and insulin resistance, which can be modified by dietary intake. Aims. In this study, we aimed to determine the association of the plasma fatty acid composition with apelin plasma concentration and gene expression in visceral (VAT) and subcutaneous (SAT) adipose tissues. Methods. In this cross-sectional study, we recruited 179 patients aged 19-75 years who were candidates for elective surgery. Through the surgery, SAT and VAT were collected to measure apelin gene expression. Anthropometric measurements, fasting blood samples, and dietary intakes were collected before surgery. Free fatty acids (FFAs) in fasting whole plasma were measured using gas chromatography with flame ionization detection. Linear regression models were used to estimate standardized $\beta$ (STZ $\beta$ ) showing the association of individual and total FFAs with apelin gene expression after adjustment for potential confounding variables. Results. In multivariable analysis, we observed a significant positive association of total plasma free fatty acids (FFAs) (STZ $\beta =0.241$ , $P=0.006$ ), saturated fatty acid (SFA) (STZ $\beta =0.336$ , $P<0.001$ ), and monounsaturated fatty acid (MUFA) (STZ $\beta =0.313$ , $P<0.001$ ) concentrations with apelin gene expression from VAT after controlling for age, sex, body mass index, homeostatic model assessment for insulin resistance (HOMA-IR), physical activity, and energy intake. In the SFA family, there was a direct association with plasma concentration of myristic acid (STZ $\beta =0.372$ , $P<0.001$ ), pentadecanoic acid ( $\text{STZ}\beta =0.252$ , $P=0.002$ ), and heptadecanoic acid (STZ $\beta =0.407$ , $P<0.001$ ) with apelin mRNA expression in VAT. There was no significant association between FFAs and apelin plasma concentration and SAT mRNA levels. Conclusions. In conclusion, circulating plasma FFAs, SFA, and MUFA had a positive association with apelin gene expression in VAT. It seems that plasma fatty acid composition may regulate apelin gene expression in VAT.