Cellular senescence is similar between regional adipose tissue depots in individuals with obesity and type 2 diabetes
Objective: To determine regional differences in markers of cellular senescence and how these compare in obese individuals with and without T2DM. Methods: Pre-menopausal females undergoing bariatric surgery were categorized as obese-metabolically healthy (OB, n=5) or obese-T2DM (DM, n=5). AT biopsies were acquired by needle aspiration (AB & TH) or excised during surgery (VAT). AT was digested with collagenase and pre-adipocytes were sub-sequentially isolated and cultured. Once confluent, cultured cells were fixed with paraformaldehyde and stained for senescence associated- β-galactosidase (SA-β-gal) activity, or immunofluorescence staining which quantified the protein abundance of H2AX (marker of DNA damage), PML nuclear bodies (marker of cellular stress), and P53&P21 (markers of committed senescent state).
Results: Regional differences in SA-β-gal were observed in OB but not DM where TH had greater (AB: p=0.01, VAT: p=0.05) SA-β-gal emittance than AB and VAT (AB: 1.48±0.21, TH: 3.61±0.47, VAT: 2.16±0.62). Regional differences in the number of H2AX foci were observed in DM and not OB, where VAT has less (AB: p=0.02, TH: p=0.04) H2AX foci than AB and TH (AB: 2.05±0.04, TH: 0.22±0.03, VAT: 0.12±0.02). Comparing OB to DM, OB TH had greater (p<0.01 & p<0.01) p53 and p21 mean fluorescence (0.07±0.001 vs. 0.06±0.001 and 0.07±0.01 vs. 0.05±0.01, respectively). OB AB also had greater (p=0.03) p53 mean fluorescence than DM AB (0.07±0.01 vs. 0.06±0.001).
Conclusion: There were no OB/DM or regional differences in PML. Subcutaneous AT depots are positive for more cellular senescence markers than VAT. Many regional patterns of senescence are similar between OB and DM however, overall OB participants had greater levels of senescence.