Blastocystis: Investigations on host-pathogen interactions using in vitro model systems

Abstract

Blastocystis is a ubiquitous enteric protozoan found in the intestinal tract of humans and a wide range of animals. Accumulating evidence over the last decade suggests association of Blastocystis with many gastrointestinal symptoms. However, nothing is known about the parasitic virulence factors and early events following host-parasite interactions. In this study, we demonstrate for the first time that Blastocystis possesses proteases that can degrade human secretory immunoglobulin A; and activate IL-8 gene expression in human colonic epithelial cells in NF-N:B dependent manner. Additionally, we show that Blastocystis induces apoptosis in intestinal epithelial cells in a contact-independent manner. We also demonstrate that Blastocystis can disrupt the intestinal barrier function. Moreover, we show for the first time that central vacuole of Blastocystis may function as a reservoir for cysteine proteases. Our findings will certainly help to understand pathobiology of a poorly studied parasite for which public health importance is increasingly recognized.