Different Poly(I∶C) stimulation strategies in inducing innate immune responses in adipocytes

Objective To investigate the innate immune responses in preadipocytes and adipocytes induced by polyinosinic polycytidylic acid [Poly(I∶C)] with different stimulation strategies. Methods Preadipocytes (3T3-L1) and mature adipocytes were treated with Poly(I∶C) through direct exogenous addition and endogenous transfection. Expression of inflammatory factors (TNF-ɑ and IL-6) and typeⅠinterferons (IFN-α and IFN-β) were detected by real-time quantitative PCR at mRNA level and by ELISA at protein level. Results Compared with control group, both Poly(I∶C) stimulation strategies improved the expression of inflammatory factors and typeⅠinterferons at mRNA and protein levels. Transfection of Poly(I∶C) to preadipocytes (3T3-L1) and mature adipocytes significantly enhanced the expression of inflammatory factors and typeⅠinterferons at mRNA and protein levels as compared with the strategy of direct exogenous addition. Exogenous addition of Poly(I∶C) induced the expression of Toll-like receptor 3 (TLR3), while transfection of Poly(I∶C) induced the expression of TLR3, melanoma differentiation related proteins 5 (MDA5) and retinoic acid inducedⅠreceptor (RIG-Ⅰ). Conclusion This study suggests that transfection of Poly(I∶C) into preadipocytes and adipocytes could induce more inflammation reactions than directly addition. Key words: Adipocyte; Poly(I∶C); Pattern recognition receptor; 3T3-L1