Entamoeba histolytica: identification of a distinct beta2 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 beta2 integrin (CD18)-like molecule which affords adherence to TNF-alpha-activated endothelial cells. Data from flow cytometry and indirect immunofluorescence 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.
Pillai
Dylan R
DR
Division of Infectious Diseases, Department of Medicine, University of California, San Francisco 94143, USA. dpillai@itsa.ucsf.edu
Kain
Kevin C
KC
D000818:Animals; D015153:Blotting, Western; D018821:CD18 Antigens / Q000276:immunology / Q000302:isolation & purification* / Q000502:physiology; D002417:Cattle; D002448:Cell Adhesion / Q000502:physiology; D002460:Cell Line; D042783:Endothelial Cells / Q000469:parasitology; D004730:Endothelium, Vascular / Q000166:cytology / Q000469:parasitology; D004748:Entamoeba histolytica / Q000276:immunology / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology / Q000302:isolation & purification / Q000502:physiology; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000276:immunology / Q000378:metabolism; D037102:Lectins; D037181:Lectins, C-Type / Q000276:immunology; D008565:Membrane Proteins / Q000276:immunology; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D011956:Receptors, Cell Surface; D018411:Spodoptera / Q000166:cytology; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology
D018821:CD18 Antigens; C023339:Clec10a protein, rat; D000939:Epitopes; D037102:Lectins; D037181:Lectins, C-Type; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1