title: Trichomonas vaginalis haemolysis: pH regulates a contact-independent mechanism based on pore-forming proteins.
abstract: There is a controversy in literature about involvement of secreted factors in the pathogenetic mechanisms of Trichomonas vaginalis, described mostly as contact-dependent. We found that the protozoan, under triggering conditions, is able to release molecules that lead to lysis without direct contact between parasite and target cells as a prerequisite. In this paper we characterize contact-independent cytotoxicity using the red blood cell as a cellular model. Contact-independent haemolysis is a phenomenon were pH exerts a key role, triggering the secretion of a lytic molecule and regulating its activity. A partial physicochemical characterization of the haemolytic factor suggests that a protein of M(r) > 30 kDa could be the effector responsible for damage. Furthermore, the parasite-induced membrane permeabilization, detected by measuring potassium escape from the target cell, and an effective osmotic protection by carbohydrates allowed us to relate the previously described pore-forming mechanism involved in contact-dependent cytotoxicity with the contact-independent lysis.
authors.affiliation: Institute of Microbiology and Virology, University of Sassari, Italy.
authors.forename: P L
authors.initials: PL
authors.lastname: Fiori
authors.forename: P
authors.initials: P
authors.lastname: Rappelli
authors.forename: M F
authors.initials: MF
authors.lastname: Addis
authors.forename: A
authors.initials: A
authors.lastname: Sechi
authors.forename: P
authors.initials: P
authors.lastname: Cappuccinelli
mesh_terms: D000818:Animals; D002463:Cell Membrane Permeability; D003603:Cytotoxins / Q000378:metabolism; D004912:Erythrocytes / Q000737:chemistry / Q000378:metabolism; D006461:Hemolysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008954:Models, Biological; D009995:Osmosis; D018272:Porins / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D011480:Protease Inhibitors / Q000378:metabolism; D014246:Trichomonas vaginalis / Q000378:metabolism* / Q000472:pathogenicity
chemical_list: D003603:Cytotoxins; D018272:Porins; D011480:Protease Inhibitors; D011188:Potassium