Bhattacharyya Asima, Pathak Shresh, Datta Simanti, Chattopadhyay Santanu, Basu Joyoti, Kundu Manikuntala
Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India.
Biochem J. 2002 Nov 15;368(Pt 1):121-9. doi: 10.1042/BJ20020555.
Gastric infection, as well as inflammation, caused by Helicobacter pylori, activates the production of cytokines and chemokines by mononuclear cells; interleukin-8 (IL-8) is one of the major inflammatory chemokines. Since H. pylori does not invade mucosal tissue, we observed the effect of the water extract of H. pylori (HPE), containing shed factors, on the production of IL-8 by human peripheral blood monocytes and the human monocyte cell line THP-1. HPE-treatment induced activation of the mitogen-activated protein kinases (MAPKs) ERK (extracellular signal-regulated kinase), p38 and JNK (c-Jun N-terminal kinase), an effect which was not dependent on the presence of the cag pathogenicity island. p38 MAPK activation was sustained. The specific inhibitors, U0126 (for ERK1/2 signalling) and SB203580 (for p38 MAPK signalling), both abrogated IL-8 secretion from HPE-treated THP-1. Dominant-negative mutants of the upstream kinases MEK1 (MAPK/ERK kinase 1), MKK (MAPK kinase) 6 and MKK7 also inhibited IL-8 secretion, pointing to a role of all three MAPKs in HPE-mediated IL-8 release. The inhibitory effects of polymyxin B and anti-CD14 antibody suggested that the effect of HPE on MAPKs was mediated by H. pylori lipopolysaccharide (LPS). By analysis of IL-8-promoter-driven luciferase gene expression, we observed that the effects of HPE-induced nuclear factor-kappaB (NF-kappaB) activation and MAPK signalling were mediated at the level of the IL-8 promoter. While ERK1/2 activation could be linked to enhanced DNA binding of activator protein-1 (AP-1), p38 MAPK signalling did not affect AP-1 DNA binding. Taken together, these results provide the first evidence that LPS from H. pylori stimulates IL-8 release from cells of the monocytic lineage through activation of NF-kappaB and signalling along MAPK cascades. The stimulation of MAPK signalling in macrophages by LPS of H. pylori amplifies the inflammatory response associated with gastric H. pylori infection and needs to be taken into consideration when developing therapeutics based on these signalling pathways.
幽门螺杆菌引起的胃部感染以及炎症会激活单核细胞产生细胞因子和趋化因子；白细胞介素-8（IL-8）是主要的炎性趋化因子之一。由于幽门螺杆菌并不侵袭黏膜组织，我们观察了含有脱落因子的幽门螺杆菌水提取物（HPE）对人外周血单核细胞和人单核细胞系THP-1产生IL-8的影响。HPE处理诱导了丝裂原活化蛋白激酶（MAPK）ERK（细胞外信号调节激酶）、p38和JNK（c-Jun氨基末端激酶）的激活，这一效应并不依赖于cag致病岛的存在。p38 MAPK的激活持续存在。特异性抑制剂U0126（用于ERK1/2信号传导）和SB203580（用于p38 MAPK信号传导）均消除了HPE处理的THP-1分泌IL-8的现象。上游激酶MEK1（MAPK/ERK激酶1）、MKK（MAPK激酶）6和MKK7的显性负性突变体也抑制了IL-8的分泌，表明所有这三种MAPK在HPE介导的IL-8释放中均发挥作用。多粘菌素B和抗CD14抗体的抑制作用表明，HPE对MAPK的作用是由幽门螺杆菌脂多糖（LPS）介导的。通过分析IL-8启动子驱动的荧光素酶基因表达，我们观察到HPE诱导的核因子-κB（NF-κB）激活和MAPK信号传导的效应是在IL-8启动子水平介导的。虽然ERK1/2的激活可能与激活蛋白-1（AP-1）的DNA结合增强有关，但p38 MAPK信号传导并不影响AP-1的DNA结合。综上所述，这些结果首次证明，幽门螺杆菌的LPS通过激活NF-κB和沿MAPK级联信号传导刺激单核细胞系细胞释放IL-8。幽门螺杆菌的LPS对巨噬细胞中MAPK信号传导的刺激放大了与胃部幽门螺杆菌感染相关的炎症反应，在基于这些信号通路开发治疗药物时需要考虑这一点。
