Entamoeba histolytica:: identification of a distinct β2 integrin-like molecule with a potential role in cellular adherence

Entamoeba histolytica infection causes dysentery, intestinal colitis, and hepatic abscess in an estimated 50 million people worldwide. Attachment of E histolytica trophozoites to intestinal epithelium and vascular endothelium during liver metastasis results in an inflammatory process. We report the identification of a distinct amebic beta(2) integrin (CD18)-like molecule which affords adherence to TNF-alpha-activated endothelial cells. Data from flow cytometry and indirect immuno fluorescence assays suggest the amebic beta2 integrin was localized to focal adhesion plates and was present in both E histolytica and Entamoeba dispar. The amebic beta2 integrin appeared to be distinct from the amebic Gal/GalNAc lectin based on recombinant expression, amebic colocalization, and ELISA studies. Trophozoite adherence to endothelial cells expressing ICAM-1 (CD54) following activation with TNF-alpha or ICAM-1-transfected CHO cells was specifically inhibited with anti-CD18 or anti-CD54 MAbs. In summary, evidence in support of a distinct beta2 integrin-like molecule participating in amebic adherence to TNF-alpha-activated endothelial cells expressing ICAM-1 is presented. The presence of integrin-dependent binding may allow trophozoites to opportunistically adhere to activated intestinal epithelium or vascular endothelium expressing ICAM-1 during amebic colitis or hepatic abscess. (C) 2005 Published by Elsevier Inc.