Evidence of Participation of Cytoskeleton of Heart Muscle Cells during the Invasion of Trypanosoma cruzi.

Abstract

ABSTRACT. The participation of heart muscle cells (HMC) cytoskeleton during its interaction withTrypanosoma cruzi was investigated. Pre-treatment of heart muscle cells with cytochalasin B (CB) or D (CD) prior to 1 and 3 h of interaction with T. cruzi inhibited the uptake of parasites by about 65%and 75%. T. cruzi was not able to invade fixed HMC, and fixed parasites were not internalized in either normal and CD-treated HMC. Transmission electron microscopy showed cell membraneprojections of HMCenclosing the parasite during the invasion process after short periods of interaction (5 to 30 min). During the parasite internalization process, sarcolemmaextensions were observed inside the cytoplasmic vacuole, suggesting that the endocytic event may involve internalization of a "self membrane". Images of cytoskeleton elements mobilization during T. cruzi penetration of HMCwere obtained following treatment of cells with Triton X-100. Our results suggest an active involvement of HMCcytoskeleton elements during the interiorization of metacyclic forms of T. cruzi* Wehave employeda system of primary cultures of heart muscle cells to investigate the initial events in T.cruzi-host cell interaction. We have observed HMC membraneexpansions during the adhesion step (16) and the presence of parasite in endocytic vacuoles immediately after invasion (17, 15, 16, 4, 5). Cytochalasins (drugs that block actin polymerization and affect plasma membrane-related functions) have been used to study micro filament-membrane association and also to elucidate the invasion mechanismof obligate intracellular parasites in mammalian cells (1, 3,29). Conflicting evidence has emerged from experiments investigating the effect of these drugs on T. cruzi-host cell interaction. A series of papers have reported that cytochalasin B (CB) and also cytochalasin D (CD) block

Participation of Host Cell Actin Filaments during Interaction of Trypomastigote Forms of Trypanosoma cruzi with Host Cells.

“…Studies carried out by several groups have shown that involvement of host cell actin with cytochalasins interferes with the internalization of trypomastigote forms into vertebrate cells (Barbosa et al, 1995;Burleigh et al, 1995;Burleigh et al, 1998;Caler et al, 2000;Carvalho et al, 1999;Mortara et al, 1999;Nogueira et al, 1976;Procopio et al, 1994;Schenkman et al, 1991). In most of the studies such interference is negative, decreasing the rate of infection and increasing attachment (Barbosa et al, 1995;Meirelles et al, 1982).…”

“…In most of the studies such interference is negative, decreasing the rate of infection and increasing attachment (Barbosa et al, 1995;Meirelles et al, 1982). In other situations, however, it has been shown that cytochalasin treatment even enhances parasite penetration (Caler et al, 2000;Nogueira et al, 1976;Procopio et al, 1994;Schenkman et al, 1991;Sibley et al, 2000).…”

“…However, there is still some discussion regarding the involvement of host cell actin on the process of parasite internalization. Some studies report that treatment of host cells with cytochalasin B or D, drugs which interfere with actin filaments and inhibit the phagocytic process, inhibited the infection of the cells by the parasite (Barbosa et al, 1995;Meirelles et al, 1982). Others, however, show that the same treatment even increased parasite penetration (Procopio et al, 1994;Schenkman et al, 1991;Schenkman et al, 1992;Tardieux et al, 1994).…”

Why studies on invasion of host cell by Trypanosoma cruzi using stablished cell lines or primary cell cultures give conflicting results?

“…Fixed parasites were never seen inside cardiomyocytes, neither live parasites did invade fixed cells. Our data do not preclude the possibility of additional mechanism(s) of penetration that might require more active participation of the parasites for complete invasion to occur, but indicate that endocytosis is the main process involved in the uptake of metacyclic forms of T. cruzi by cardiomyocytes (Barbosa & Meirelles 1995). In a recent paper, De Souza et al (1998) suggested that both active penetration and typical phagocytosis can be used by the parasites to invade macrophages and Vero cells, and that both process can occur in the same cell.…”

Biological Roles of Peptidases in Trypanosomatids~!2009-11-26~!2010-02-15~!2010-03-18~!

“…Cruzipain has an N-terminal catalytic domain linked to an antigenic C-terminal extension, the gp25 [61,62]. Structural characterization of the oligosaccharide chains revealed the presence of sulfated residues that are essential for cruzipain recognition by IgG antibodies from the serum of chagasic patients [63,64]. This peptidase is localized in different cell compartments, depending on the life cycle stage.…”