Suppression of NF-kappaB activation by Entamoeba histolytica in intestinal epithelial cells is mediated by heat shock protein 27.
Suppression of NF-kappaB activation by Entamoeba histolytica in intestinal epithelial cells is mediated by heat shock protein 27.
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发表时间：
2006
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通讯作者：
Srinivas J. Kammanadiminti;K. Chadee
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作者：
Srinivas J. Kammanadiminti;K. Chadee
关于溶组织内阿米巴的发病机制以及上皮细胞对寄生虫的反应知之甚少。在此，我们描述了E.溶组织细胞和结肠上皮细胞以及巨噬细胞在调节上皮细胞应答中的作用。人结肠上皮细胞系Caco-2和T84在transwell板中与分化的人THP-1巨噬细胞单培养或共培养24小时，然后用可溶性阿米巴蛋白（SAP）刺激。在幼稚的上皮细胞，SAP的长期刺激降低了热休克蛋白（HSP）27和72的水平。而SAP对THP-1诱导的肠上皮细胞Hsp 27和Hsp 72表达的增强依赖于ERK MAP激酶的激活。SAP诱导的热休克蛋白合成对氧化和凋亡损伤具有保护作用。SAP处理抑制了IL-1 β诱导的NF-κ B活化，特别是NF-κ B-DNA结合、p65亚基核转位和IkappaB-α磷酸化减少。通过小干扰RNA的基因沉默证实了Hsp 27在IkappaB激酶（IKK）水平上抑制NF-κ B活化的作用。通过免疫共沉淀研究，我们发现Hsp 27与IKK-α和IKK-β相互作用，并且这种关联在SAP处理的条件上皮细胞中增加。野生型Hsp 27的过表达放大了SAP的作用，而Hsp 27的磷酸化缺陷突变体废除了SAP诱导的NF-κ B抑制。在条件上皮细胞，热休克蛋白27磷酸化丝氨酸15后，长期暴露于SAP。这一机制可以解释为什么大多数感染大肠杆菌的个体没有结肠炎症。溶组织剂
Little is known about the pathogenesis of Entamoeba histolytica and how epithelial cells respond to the parasite. Herein, we characterized the interactions between E. histolytica and colonic epithelial cells and the role macrophages play in modulating epithelial cell responses. The human colonic epithelial cell lines Caco-2 and T84 were grown either as monoculture or co-cultured in transwell plates with differentiated human THP-1 macrophages for 24 h before stimulation with soluble amebic proteins (SAP). In naive epithelial cells, prolonged stimulation with SAP reduced the levels of heat shock protein (Hsp) 27 and 72. However in THP-1 conditioned intestinal epithelial cells SAP enhanced Hsp27 and Hsp72, which was dependent on the activation of ERK MAP kinase. Hsp synthesis induced by SAP conferred protection against oxidative and apoptotic injuries. Treatment with SAP inhibited NF-kappaB activation induced by interleukin-1beta; specifically, the NF-kappaB-DNA binding, nuclear translocation of p65 subunit, and phosphorylation of IkappaB-alpha were reduced. Gene silencing by small interfering RNA confirmed the role of Hsp27 in suppressing NF-kappaB activation at IkappaB kinase (IKK) level. By co-immunoprecipitation studies, we found that Hsp27 interacts with IKK-alpha and IKK-beta, and this association was increased in SAP-treated conditioned epithelial cells. Overexpression of wild type Hsp27 amplified the effects of SAP, whereas a phosphorylation-deficient mutant of Hsp27 abrogated SAP-induced NF-kappaB inhibition. In conditioned epithelial cells, Hsp27 was phosphorylated at serine 15 after prolonged exposure to SAP. This mechanism may explain the absence of colonic inflammation seen in the majority of individuals infected with E. histolytica.