Cigarette smoke attenuation of poly I:C-induced innate antiviral responses in human PBMC is mainly due to inhibition of IFN-β production

The cellular response to dsRNA or its synthetic analog polyinosinic-polycytidylic acid (poly I:C) results in IRF-3-, IRF-7- and NF-kB-mediated activation of type 1 IFNs and pro-inflammatory cytokines critical for innate antiviral immune responses. To investigate whether cigarette smoke compromises type 1 IFN signaling in humans, peripheral blood mononuclear cells (PBMCs) from non-smoking individuals were treated with smoke-conditioned media (SCM) and stimulated with poly I:C. We observed a marked attenuation of IRF-3 and NF-kB activation in PBMCs exposed to SCM compared to control PBMCs. Similarly, PBMCs from smokers or splenocytes from smoke-exposed mice also displayed marked reduction of poly I:C-induced antiviral responses compared with either non-smokers or sham-exposed mice. Cigarette smoke was found to block the production of type I IFNs following poly I:C treatment and inhibit subsequent STAT1 activation. Finally, we confirmed that inhibition of IFN-beta, but not IFN-alpha, predominantly contributes to the cigarette smoke-mediated suppression of innate antiviral responses. These findings provide novel mechanistic insights to the susceptibility of cigarette smokers to viral infections.