Cruzipain Activates Latent TGF-β from Host Cells during T. cruzi Invasion

Abstract

Several studies indicate that the activity of cruzipain, the main lysosomal cysteine peptidase of Trypanosoma cruzi, contributes to parasite infectivity. In addition, the parasitic invasion process of mammalian host cells is described to be dependent on the activation of the host TGF-β signaling pathway by T. cruzi. Here, we tested the hypothesis that cruzipain could be an important activator of latent TGF-β and thereby trigger TGF-β-mediated events crucial for the development of Chagas disease. We found that live epimastigotes of T. cruzi, parasite lysates and purified cruzipain were able to activate latent TGF-β in vitro. This activation could be inhibited by the cysteine peptidase inhibitor Z-Phe-Ala-FMK. Moreover, transfected parasites overexpressing chagasin, a potent endogenous cruzipain inhibitor, prevented latent TGF-β activation. We also observed that T. cruzi invasion, as well as parasite intracellular growth, were inhibited by the administration of Z-Phe-Ala-FMK or anti-TGF-β neutralizing antibody to Vero cell cultures. We further demonstrated that addition of purified cruzipain enhanced the invasive activity of trypomastigotes and that this effect could be completely inhibited by addition of a neutralizing anti-TGF-β antibody. Taken together, these results demonstrate that the activities of cruzipain and TGF-β in the process of cell invasion are functionally linked. Our data suggest that cruzipain inhibition is an interesting chemotherapeutic approach for Chagas disease not only because of its trypanocidal activity, but also due to the inhibitory effect on TGF-β activation.

Interactions between Trypanosoma cruzi Secreted Proteins and Host Cell Signaling Pathways

“…Previous studies have demonstrated that forms of T. cruzi are able to activate latent TGF-β ( Waghabi et al, 2005 ). Treatment of macrophages with increasing doses of cruzipain promoted the activation of TGF-β in a dose-dependent manner, confirming that this peptidase is capable of activating latent TGF-β in the absence of any other host or parasite factors ( Ferrão et al, 2015 ). In addition, transgenic EPIs overexpressing chagasin, a natural cruzipain inhibitor, were significantly less able to activate latent TGF-β when compared to wild type parasites ( Santos et al, 2005 ; Ferrão et al, 2015 ).…”

How Does the Main Infective Stage ofT. cruziEnter and Avoid Degradation in Host Cells? A Description of the Pathways and Organelles Involved on These Processes

“…This protein binds to a kininogen molecule that is cleaved into short kinin molecules, which in turn bind to the bradykinin receptor by stimulating the release of calcium from IP3. Cruzipain is also capable to regulate arginase activity increasing T. cruzi survival inside the cell through an increase in the production of IL-10 and TGF-β [92]. The model based on the activation of the glycoprotein gp82 is known to be bidirectional since it has been shown that a peak of calcium is generated not only in the host cell but also in the parasite itself.…”

Expression of cysteine proteinases and cystatins in parasites and use of cysteine proteinase inhibitors in parasitic diseases. Part III: Protozoa (3): Kinetoplastids

“…Also, T. cruzi invasion and intracellular growth were inhibited on addition of CATH CPI or anti-TGF-β antibodies to Vero cell cultures. Therefore, CRZ was suggested as drug target in treatment of Chagas' disease [129] .…”