A functional link between heme oxygenase-1 and tristetraprolin in the anti-inflammatory effects of nicotine.

In this study, we sought to determine whether HO-1 associates with TTP to mediate the anti-inflammatory effects of nicotine. Inhibition of HO-1 activity or HO-1 expression attenuated the effects of nicotine on STAT3 activation, TTP induction, and TNF-α production in LPS-treated macrophages. Induction of HO-1 expression increased the level of TTP in the absence of nicotine. In a LPS-induced endotoxemia model, HO-1 deficiency blocked the effects of nicotine on the STAT3 phosphorylation, TTP induction and LPS-induced TNF-α production in the liver. Downregulation of STAT3 by siRNA attenuated the effect of nicotine on TTP expression and TNF-α production but did not affect the nicotine-mediated induction of HO-1. In TTP knockout mice, nicotine treatment enhanced HO-1 expression and STAT3 activation but failed to inhibit LPS-induced TNF-α production. Our results suggest that HO-1 and TTP are functionally linked in mediating anti-inflammatory effects of nicotine; HO-1 is necessary for the induction of TTP by nicotine. This novel nicotine-HO-1-TTP signaling pathway provides new possibilities for the treatment of inflammatory diseases. PMID: 24095726 [PubMed - as supplied by publisher]
Source: Free Radical Biology and Medicine - Category: Biology Authors: Tags: Free Radic Biol Med Source Type: research