Toll-like receptors （TLRs） 7 and 8 are crucial in host defence against single-stranded RNA （ssRNA） viruses. Such viruses cause severe illnesses, which remain a serious medical burden in both industrialised and dev...Toll-like receptors （TLRs） 7 and 8 are crucial in host defence against single-stranded RNA （ssRNA） viruses. Such viruses cause severe illnesses, which remain a serious medical burden in both industrialised and developing countries. TLR7/8 downstream signaling leads tO a dramatic cellular stress associated with energy consumption. However, the molecular mechanisms of cell survival and adaptation to TLR7/8-induced stress, which give the cells an opportunity to initiate proper inflammatory reactions, are not clear at all. Here we report for the first time that ligand-induced activation of TLR7/8 leads to the accumulation of hypoxia-inducible factor 1 alpha （HIF-1α） protein in THP-1 human myeloid macrophages via redoxand reactive nitrogen species-dependent mechanisms. MAP kinases and phosphoinositol-3K are not involved in TLR7/8-mediated HIF-1α accumulation. Experiments with HIF-1α knockdown THP- 1 cells have clearly demonstrated that HIF-1α is important for the protection of these cells against TLR7/8-induced depletion of ATP. Thus, HIF-1α might support both cell survival and the production of pro-inflammatory cytokines upon TLR7/8 activation.展开更多
文摘Toll-like receptors （TLRs） 7 and 8 are crucial in host defence against single-stranded RNA （ssRNA） viruses. Such viruses cause severe illnesses, which remain a serious medical burden in both industrialised and developing countries. TLR7/8 downstream signaling leads tO a dramatic cellular stress associated with energy consumption. However, the molecular mechanisms of cell survival and adaptation to TLR7/8-induced stress, which give the cells an opportunity to initiate proper inflammatory reactions, are not clear at all. Here we report for the first time that ligand-induced activation of TLR7/8 leads to the accumulation of hypoxia-inducible factor 1 alpha （HIF-1α） protein in THP-1 human myeloid macrophages via redoxand reactive nitrogen species-dependent mechanisms. MAP kinases and phosphoinositol-3K are not involved in TLR7/8-mediated HIF-1α accumulation. Experiments with HIF-1α knockdown THP- 1 cells have clearly demonstrated that HIF-1α is important for the protection of these cells against TLR7/8-induced depletion of ATP. Thus, HIF-1α might support both cell survival and the production of pro-inflammatory cytokines upon TLR7/8 activation.
