Pattern recognition receptor-initiated innate antiviral response in mouse adipose cells

Although wide range of viruses can infect adipose tissues, innate antiviral response of adipose cells has not been investigated. This study focused on innate antiviral system in mouse adipose cells. Major virus sensors including Toll-like receptor 3 (TLR3), melanoma differentiation-associated antigen 5 (MDA5) and retinoic acid-inducible gene I (RIG-I) are constitutively expressed in preadipocytes and adipocytes. Poly(I:C), a common agonist of TLR3, MDA5 and RIG-I, induced the expression of type I interferons (IFN-α/β) in the two types of adipose cells through the activation of IFN-regulatory factor 3 and upregulated pro-inflammatory factors such as TNF-α and IL-6 through the activation nuclear factor kappa B. Moreover, poly(I:C) induced multiple antiviral proteins including IFN-stimulating gene 15, 2'5'-oligoadenylate synthetase and Mx GTPase 1 in preadipocytes and adipocytes. The poly(I:C)-induced innate antiviral response was reduced by TLR3 deficiency and knockdown of MDA5 or RIG-I. Poly(I:C) also inhibited the differentiation of preadipocytes to adipocytes and suppressed the expression of leptin, adiponectin and resistin in mature adipocytes. The results demonstrated that adipose cells are equipped with innate antiviral system, which may modulate the function of adipocytes.