Abstract
Background: Steroid receptor RNA activator gene (SRA1) is involved in physiological and pathological responses of adipose tissue (AT) in the obesity setting. Its role in metabolic inflammation has been studied in in vitro and in vivo animal models. However, AT-SRA1 expression in obesity and its association with metabolic inflammation and insulin resistance is poorly understood. This study aimed to investigate AT-SRA1 expression level and its association with inflammatory and metabolic markers in obese individuals. Methods: 55 non-diabetic individuals were recruited in the study. Demographic information and fasting blood samples were collected for assessing the metabolic and inflammatory markers. Subcutaneous fat tissues were collected for quantifying the level of SRA1 expression using qRT-PCR and immunohistochemistry. Results: AT-SRA1 expression at both mRNA and protein levels was significantly higher in obese compared with lean individuals. SRA1 expression was significantly correlated with demographic parameters including BMI (r = 0.355,p = 0.008), percent of body fat (r = 0.334, p = 0.022),and waist circumference (r = 0.291, p = 0.047), inflammatory cytokines/ chemokines including TNF-a (r = 0.317, p = 0.030), TGF- ß (r = 0.514, p < 0.0001), CCL3 (r = 0.285, p = 0.045), CCL8 (r = 0.344, p = 0.020), CXCL11 (r = 0.400, p = 0.003), IL-13 (r = 0.310, p = 0.028), and IL-18 (r = 0.547, p < 0.0001), immune cell markers including CD16 (r = 0.277, p = 0.047) and CD163 (r = 0.282, p = 0.037). Notably, SRA1 expression is positively correlated with HOMA-IR (r = 0.433, p = 0.005) and fasting plasma insulin level (r = 0.440, p = 0.005). Multiple regression analysis showed TGF- ß and IL-18 are as independent predictors of SRA1. Conclusions: Overall, for the first time our data demonstrate that increased expression of AT-SRA1 may represent as a novel biomarker for metabolic inflammation and insulin-resistance in non-diabetic obese individuals.