Bariatric surgery can acutely modulate ER-stress and inflammation on subcutaneous adipose tissue in non-diabetic patients with obesity

Background: Bariatric surgery, especially Roux-en-Y gastric bypass (RYGB), is the most effective and durable treatment option for severe obesity. The mechanisms involving adipose tissue may be important to explain the effects of surgery. Methods: We aimed to identify the genetic signatures of adipose tissue in patients undergoing RYGB. We evaluated 13 obese, non-diabetic patients (mean age 37 years, 100% women, Body mass index (BMI) 42.2 kg/m2) one day before surgery, 3 and 6 months (M) after RYGB. Results: Analysis of gene expression in adipose tissue collected at surgery compared with samples collected at 3M and 6M Post-RYGB showed that interleukins (Interleukin 6, Tumor necrosis factor-α ( TNF -α), and Monocyte chemoattractant protein-1(MCP1)) and endoplasmic reticulum stress (ERS) genes (Eukaryotic translation initiation factor 2 alpha kinase 3 (EIF2AK3) and Calreticulin (CALR)) decreased during the follow-up (P≤0.01 for all). Otherwise, genes involved in energy homeostasis (Adiponectin and AMP-activated protein kinase (AMPK)), cellular response to oxidative stress (Sirtuin 1, Sirtuin 3, and Nuclear factor erythroid 2-related factor 2 (NRF2)), mitochondrial biogenesis (Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α)) and amino acids metabolism (General control nonderepressible 2 (GCN2)) increased from baseline to all other time points evaluated (P≤0.01 for all). Also, expression of Peroxisome proliferator-activated receptor gamma (PPAR ϒ ) (adipogenesis regulation) was significantly decreased after RYGB (P<0.05). Additionally, we observed that PGC1α, SIRT1 and AMPK strongly correlated to BMI at 3M (P≤0.01 for all), as well as ADIPOQ and SIRT1 to BMI at 6M (P≤0.01 for all). Conclusions: Our findings demonstrate that weight loss is associated with amelioration of inflammation and ERS and increased protection against oxidative stress in adipose tissue. These observations are strongly correlated with a decrease in BMI and essential genes that control cellular energy homeostasis, suggesting an adaptive process on a gene expression level during the caloric restriction and weight loss period after RYGB.Trial registration: CAAE: 73585317.0.0000.5440