Reprogramming of murine macrophages through TLR2 confers viral resistance via TRAF3-mediated, enhanced interferon production

• Published in: PLoS pathogens 2013-07, Vol.9 (7), p.e1003479-e1003479
• Main Authors: Perkins, Darren J, Polumuri, Swamy K, Pennini, Meghan E, Lai, Wendy, Xie, Ping, Vogel, Stefanie N
• Format: Article
• Language: English
• Subjects: Animals; Bacteria; Biology; Cell Line; Cells, Cultured; Cellular Reprogramming; Deoxyribonucleic acid; DNA; E coli; Female; Health aspects; Host-parasite relationships; Humans; Immune response; Immune system; Immunity, Innate; Influenza A virus - immunology; Interferon; Interferon Type I - biosynthesis; Interferon Type I - genetics; Interferon Type I - metabolism; Ligands; Macrophages; Macrophages, Peritoneal - cytology; Macrophages, Peritoneal - immunology; Macrophages, Peritoneal - metabolism; Macrophages, Peritoneal - virology; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Knockout; Physiological aspects; Proteins; Recombinant Proteins - metabolism; Salmonella; Signal Transduction; TNF Receptor-Associated Factor 3 - genetics; TNF Receptor-Associated Factor 3 - metabolism; Toll-Like Receptor 2 - genetics; Toll-Like Receptor 2 - metabolism; Up-Regulation; Vaccinia virus - immunology; Vesicular stomatitis Indiana virus - immunology; Viral infections; Virus diseases; Viruses
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1003479

The cell surface/endosomal Toll-like Receptors (TLRs) are instrumental in initiating immune responses to both bacteria and viruses. With the exception of TLR2, all TLRs and cytosolic RIG-I-like receptors (RLRs) with known virus-derived ligands induce type I interferons (IFNs) in macrophages or dendritic cells. Herein, we report that prior ligation of TLR2, an event previously shown to induce "homo" or "hetero" tolerance, strongly "primes" macrophages for increased Type I IFN production in response to subsequent TLR/RLR signaling. This occurs by increasing activation of the transcription factor, IFN Regulatory Factor-3 (IRF-3) that, in turn, leads to enhanced induction of IFN-β, while expression of other pro-inflammatory genes are suppressed (tolerized). In vitro or in vivo "priming" of murine macrophages with TLR2 ligands increase virus-mediated IFN induction and resistance to infection. This priming effect of TLR2 is mediated by the selective upregulation of the K63 ubiquitin ligase, TRAF3. Thus, we provide a mechanistic explanation for the observed antiviral actions of MyD88-dependent TLR2 and further define the role of TRAF3 in viral innate immunity.