Galactose-specific adhesin and cytotoxicity of Entamoeba histolytica.
We examined the molecular mechanisms of the cytotoxicity of Entamoeba histolytica, using the loss of transepithelial electrical resistance (TER) of monolayers of Madin-Darby canine-kidney (MDCK) cells on their incubation with axenic trophozoites of the HM1-IMSS strain. Such loss of TER occurs very early (in 2-5 min) and is caused by the opening of tight junctions and the detachment of cells. We used specific inhibitors for three of the four molecules currently accepted as being responsible for cytotoxicity: galactose-specific adhesin(s), phospholipase A, and cysteine proteinases. We also used inhibitors of calcium channels. Axenic trophozoites of E. histolytica strain HM1-IMSS were preincubated with the different inhibitors for 1 h prior to their coincubation with MDCK-cell monolayers. The only inhibitor that effectively blocked the loss of TER caused by the parasite was galactose. We suggest that in this experimental model, galactose-specific adhesin(s) are essential for amebic cytotoxicity.
López-Vancell
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R
Departamento de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México y Hospital General de México, DF.
Montfort
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I
Pérez-Tamayo
R
R
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival / Q000502:physiology; D003546:Cysteine Endopeptidases / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004285:Dogs; D017097:Electric Impedance; D004748:Entamoeba histolytica / Q000187:drug effects / Q000472:pathogenicity*; D004847:Epithelial Cells / Q000473:pathology / Q000502:physiology; D005690:Galactose / Q000494:pharmacology; D007668:Kidney / Q000166:cytology / Q000469:parasitology*; D037102:Lectins; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000494:pharmacology; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014774:Virulence / Q000187:drug effects
D002121:Calcium Channel Blockers; D015853:Cysteine Proteinase Inhibitors; D037102:Lectins; D008562:Membrane Glycoproteins; D015800:Protozoan Proteins; C052452:galactose inhibitable adherence protein, Entamoeba histolytica; D010741:Phospholipases A; D003546:Cysteine Endopeptidases; D005690:Galactose