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  • Title: [The role of p38 mitogen activated protein kinase in the inflammatory response of human monocytes infected with nontypeable Haemophilus influenzae].
    Author: Xu ZH, Xu F, Shen HH, Li LJ.
    Journal: Zhonghua Jie He He Hu Xi Za Zhi; 2008 May; 31(5):348-51. PubMed ID: 18953958.
    Abstract:
    OBJECTIVE: To investigate the role of mitogen activated protein kinase (MAPK) pathway in the inflammatory response induced by nontypeable Haemophilus influenzae (NTHi). METHODS: NTHi was a clinical isolate identified by serum agglutination test and 16S rRNA gene sequencing. The peripheral monocytes isolated from adult healthy donors were divided into medium-treated group, NTHi-stimulated group, SB203580 (p38 MAPK inhibitor) -pretreated group and UO126 (p44/42 MAPK inhibitor) -pretreated group. Monocytes were co-cultured with NTHi and harvested 1 h and 4 h after stimulation. The phosphorylation of p38 and p44/42 MAPKs was detected by Western blot. The expression of toll-like receptor 4 (TLR4) was examined by flow cytometry 16 h after bacterial stimulation. Monocytes were preincubated with SB203580 or UO126 for 1 h and then stimulated with NTHi for 4 h and 16 h, respectively. The level of TNF-alpha in the supernatants was determined by Enzyme-linked immunosorbent assay (ELISA). RESULTS: The phosphorylation of p38 MAPK and p44/42 MAPK was rapidly induced by NTHi and continued for at least 4 h after stimulation. The expression of TLR4 on monocytes after NTHi stimulation was significantly up-regulated compared with the control group (11.8 +/- 1.6 vs 4.8 +/- 0.6, P < 0.05). The leve of TNF-alpha in the supernatants was increased 4 h and 16 h after bacterial stimulation compared with the control group (4 h : 16.4 +/- 5.3 vs 0.6 +/- 0.6, P < 0.01; 24 h : 30.2 +/- 10.7 vs 1.4 +/- 1.1, P < 0.01). SB203580 pretreatment decreased remarkably the TNF-alpha secretion from monocytes (P < 0.05) whereas UO126 had no significant effect on TNF-alpha level (P > 0.05). CONCLUSION: TLR4 is probably involved in the inflammatory response of monocytes induced by NTHi whereas p38 MAPK is the key signal molecule in this inflammatory reaction.
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