Activation of Interleukin-1 Receptor-Associated Kinase by Gram-Negative Flagellin

@article{citeulike:1387643, abstract = {Flagellin from various species of gram-negative bacteria activates monocytes to produce proinflammatory cytokines. We have analyzed the pathway by which Salmonella enteritidis flagellin (FliC) activates murine and human monocyte/macrophage-like cell lines. Since lipopolysaccharide (LPS), the principal immune stimulatory component of gram-negative bacteria, is known to signal through Toll-like receptor 4 (TLR4), we tested the possibility that FliC also signals via TLR4. When murine HeNC2 cells were stimulated with LPS in the presence of a neutralizing anti-TLR4 monoclonal antibody, tumor necrosis factor alpha (TNF-[alpha]) and nitric oxide (NO) production were markedly reduced. In contrast, FliC-mediated TNF-[alpha] and NO production were minimally affected by the anti-TLR4 antibody. Furthermore, FliC, unlike LPS, stimulated TNF-[alpha] production in the TLR4 mutant cell line, GG2EE, indicating that TLR4 is not essential for FliC-mediated signaling. To test the possibility that FliC signals via another TLR, we measured FliC-mediated activation of interleukin-1 (IL-1) receptor-associated kinase (IRAK), a central component in IL-1R/TLR signaling. FliC induced IRAK activation in HeNC2 and GG2EE cells as well as in the human promonocytic cell line THP-1. IRAK activation was rapid in HeNC2 cells, with maximal activity observed after 5 min of treatment with FliC. In addition, FliC-mediated IRAK activation exhibited the same concentration dependence as was demonstrated for the induction of TNF-[alpha]. These results represent the first demonstration of IRAK activation by a purified bacterial protein and strongly suggest that a TLR distinct from TLR4 is involved in the macrophage inflammatory response to FliC. 10.1128/IAI.69.7.4424-4429.2001}, author = {Moors, Marlena A. and Li, Liwu and Mizel, Steven B. }, citeulike-article-id = {1387643}, doi = {10.1128/IAI.69.7.4424-4429.2001}, journal = {Infect. Immun.}, keywords = {tlr5-flagellin}, month = {July}, number = {7}, pages = {4424--4429}, posted-at = {2007-06-13 16:27:28}, priority = {2}, title = {Activation of Interleukin-1 Receptor-Associated Kinase by Gram-Negative Flagellin}, url = {http://dx.doi.org/10.1128/IAI.69.7.4424-4429.2001}, volume = {69}, year = {2001} }

TY - JOUR ID - citeulike:1387643 L3 - citeulike-article-id:1387643 TI - Activation of Interleukin-1 Receptor-Associated Kinase by Gram-Negative Flagellin JF - Infect. Immun. VL - 69 IS - 7 SP - 4424 EP - 4429 N2 - Flagellin from various species of gram-negative bacteria activates monocytes to produce proinflammatory cytokines. We have analyzed the pathway by which Salmonella enteritidis flagellin (FliC) activates murine and human monocyte/macrophage-like cell lines. Since lipopolysaccharide (LPS), the principal immune stimulatory component of gram-negative bacteria, is known to signal through Toll-like receptor 4 (TLR4), we tested the possibility that FliC also signals via TLR4. When murine HeNC2 cells were stimulated with LPS in the presence of a neutralizing anti-TLR4 monoclonal antibody, tumor necrosis factor alpha (TNF-[alpha]) and nitric oxide (NO) production were markedly reduced. In contrast, FliC-mediated TNF-[alpha] and NO production were minimally affected by the anti-TLR4 antibody. Furthermore, FliC, unlike LPS, stimulated TNF-[alpha] production in the TLR4 mutant cell line, GG2EE, indicating that TLR4 is not essential for FliC-mediated signaling. To test the possibility that FliC signals via another TLR, we measured FliC-mediated activation of interleukin-1 (IL-1) receptor-associated kinase (IRAK), a central component in IL-1R/TLR signaling. FliC induced IRAK activation in HeNC2 and GG2EE cells as well as in the human promonocytic cell line THP-1. IRAK activation was rapid in HeNC2 cells, with maximal activity observed after 5 min of treatment with FliC. In addition, FliC-mediated IRAK activation exhibited the same concentration dependence as was demonstrated for the induction of TNF-[alpha]. These results represent the first demonstration of IRAK activation by a purified bacterial protein and strongly suggest that a TLR distinct from TLR4 is involved in the macrophage inflammatory response to FliC. 10.1128/IAI.69.7.4424-4429.2001 KW - tlr5-flagellin AU - Moors, Marlena AU - Li, Liwu AU - Mizel, Steven PY - 2001/07/01/ UR - http://dx.doi.org/10.1128/IAI.69.7.4424-4429.2001 ER -