Surgery-Induced Weight Loss Is Associated With the Downregulation of Genes Targeted by MicroRNAs in Adipose Tissue.

Context: Molecular mechanisms associated with physiological variations in adipose tissue (AT) are not fully recognized. The most recent reports highlight the critical relevance of microRNAs (miRNAs) found in AT.

Objective: To identify changes in messenger RNA (mRNA) and miRNA expressions and their interaction in human AT before and after surgery-induced weight loss. Research Design and Setting: Genome-wide mRNA and miRNA expressions were assessed by microarrays in abdominal subcutaneous AT of 16 morbidly obese women before and 2 years after laparoscopic Roux-en-Y gastric bypass. The association of changes in miRNAs with their respective mRNA targets was studied. The results were replicated in publicly available microarray datasets. Validation was made by real-time polymerase chain reaction in additional fat samples from 26 age-matched lean women and in isolated human adipocytes.

Results: A total of 5018 different mRNA probe sets and 15 miRNAs were differentially expressed after surgery-induced weight loss. The clustering of similar expression patterns for gene products with related functions revealed molecular footprints that elucidate significant changes in cell cycle, development, lipid metabolism, and the inflammatory response. The participation of inflammation was demonstrated by results assessed in isolated adipocytes. Interestingly, when transcriptomes were analyzed taking into account the presence of miRNA target sites, miRNA target mRNAs were upregulated in obese AT (P value = 2 × 10(-181)) and inflamed adipocytes (P value = 4 × 10(-61)), according to the number of target sites harbored by each transcript.

Conclusions: Current findings suggest impaired miRNA target gene expression in obese AT in close association with inflammation, both improving after weight loss.