Debnath Anjan, Tashker Jessica S, Sajid Mohammed, McKerrow James H
Sandler Center for Basic Research in Parasitic Diseases, University of California, San Francisco, San Francisco, CA 94158, USA.
Int J Parasitol. 2007 Jul;37(8-9):897-906. doi: 10.1016/j.ijpara.2007.01.016. Epub 2007 Feb 12.
Invasive intestinal amebiasis, caused by Entamoeba histolytica, is initiated with attachment of trophozoites to the colonic mucous layer, mucous disruption and/or depletion, and adherence to and cytolysis of host epithelial and inflammatory cells. A current working model of intestinal amebiasis suggests that the microenvironment of the host intestine, particularly intestinal mucins and the bacterial biofilm, may influence the behavior of pathogenic amebae. The invasive phenotype is dependent on expression of a number of virulence factors of which cysteine proteases provide the most convenient experimental probe because their activity is readily monitored. In the present study, we examined the interaction of E. histolytica with GalNAc, mucin, different epithelial cell lines and bacteria both by biochemical assays of protease release and transcriptional profiling using a previously validated genomic microarray. A significant down-regulation of released cysteine protease activity was observed when amebic trophozoites were grown with GalNAc, specific colonic cell lines and bacteria. Transcriptional profiling during GalNAc interaction revealed enhanced expression of the 170-kDa Gal/GalNAc lectin. Decreased protease activity during GalNAc interaction and enhanced expression of the Gal/GalNAc lectin gene are consistent with a program of commensal infection and mucus coat colonization mediated by the lectin. The down-regulation of cysteine protease activity following interaction with a colonic epithelial cell line parallels the presence of secretory mucin having a complex carbohydrate structure rich in Gal and GalNAc. In contrast, interaction of E. histolytica trophozoites with stomach porcine mucin enhanced cysteine protease (EhCP1 and EhCP2) secretion 3-fold. This suggests the specific composition of mucins may affect the Entamoeba phenotype. Transcriptional profiling revealed interaction of Entamoeba with intestinal bacteria induced protein kinase, ABC transporter, Rab family GTPase and hsp 90 gene expression. The enhanced expression of this gene cluster is consistent with enhanced phagocytosis of E. histolytica during interaction with bacteria.
由溶组织内阿米巴引起的侵袭性肠道阿米巴病始于滋养体附着于结肠黏液层、黏液破坏和/或消耗，以及对宿主上皮细胞和炎性细胞的黏附和细胞溶解。目前关于肠道阿米巴病的工作模型表明，宿主肠道的微环境，尤其是肠道黏蛋白和细菌生物膜，可能会影响致病性阿米巴的行为。侵袭表型取决于多种毒力因子的表达，其中半胱氨酸蛋白酶提供了最方便的实验探针，因为其活性易于监测。在本研究中，我们通过蛋白酶释放的生化分析以及使用先前验证的基因组微阵列进行转录谱分析，研究了溶组织内阿米巴与N-乙酰半乳糖胺（GalNAc）、黏蛋白、不同上皮细胞系和细菌之间的相互作用。当阿米巴滋养体与GalNAc、特定结肠细胞系和细菌一起培养时，观察到释放的半胱氨酸蛋白酶活性显著下调。GalNAc相互作用期间的转录谱分析显示，170 kDa Gal/GalNAc凝集素的表达增强。GalNAc相互作用期间蛋白酶活性降低以及Gal/GalNAc凝集素基因表达增强，与由凝集素介导的共生感染和黏液层定植程序一致。与结肠上皮细胞系相互作用后半胱氨酸蛋白酶活性的下调与具有富含Gal和GalNAc的复杂碳水化合物结构的分泌性黏蛋白的存在平行。相比之下，溶组织内阿米巴滋养体与猪胃黏蛋白的相互作用使半胱氨酸蛋白酶（EhCP1和EhCP2）分泌增加了3倍。这表明黏蛋白的特定组成可能会影响溶组织内阿米巴的表型。转录谱分析显示，溶组织内阿米巴与肠道细菌的相互作用诱导了蛋白激酶、ABC转运蛋白、Rab家族GTP酶和热休克蛋白90基因的表达。该基因簇的表达增强与溶组织内阿米巴在与细菌相互作用期间吞噬作用增强一致。
