Differentially expressed cellular and exosomal miRNAs during inflammation or high fat diet-induced obesity in mouse

The aim of the current study was to characterize the differential cellular and exosomal miRNAs during inflammation or high fat diet-induced obesity in mice. Mesenteric adipose tissue (MAT) and abdominal aorta (AA) from mice fed a normal chow diet (NCD) or a high fat diet (HFD) were harvested for miRNA profiling. MAT-derived adipocytes (MAT-Ad) challenged with either lipopolysaccharide (LPS, 1 µg/ml) or PBS were harvested for miRNA profiling. Meanwhile, miRNAs encapsulated in MAT-Ad-derived exosomes (MAT-Ad-EX) were also analyzed. Hierarchical clustering analysis performed on most significantly regulated miRNAs (HFD vs NCD in tissues; LPS challenge vs PBS in the cells) showed a set of miRNAs that are differentially expressed in obese versus lean MAT or AA tissues, and in LPS-challenged versus PBS-treated MAT-Ads. The dysregulated of miRNAs in MAT-Ad-EX was also generated and hierarchically clustered, induced by prolonged exposure to microbial product. Mouse tissues: C57BL6 mice were fed a normal chow diet (NCD) or a high fat diet (HFD, 60% fat) ad libitum from 4 weeks of age to 20 weeks of age. Mouse mesenteric adipose tissue (MAT, annotated as MAT-NCD or MAT-HFD) and abdominal aorta (AA, annotated as AA-NCD or AA-HFD) were snap-frozen by liquid nitrogen and saved for future RNA assays. Primary cell culture and exosome isolation: Mesenteric pre-adipocytes derived from stromal vascular cells were obtained by collagenase digestion and differentiated to primary adipocytes, designated MAT-Ad. Cells were challenged with PBS or lipopolysaccharide (LPS 1 µg/ml) for 24 h. The culture supernatants were used for exosome isolation and exosomal RNA purification (annotated as MAT-Ad-EX-LPS/PBS), and cells were pelleted for RNA isolation (annotated as MAT-Ad-LPS/PBS).