Toxins of Vibrio cholerae and Their Role in Inflammation, Pathogenesis, and Immunomodulation

Abstract

Disease manifestations in cholera are primarily attributed to the secretion of cholera toxin (CT). However, the discovery of additional secretory virulence factors in Vibrio cholerae has invoked interest in their potential role related to pathogenesis, inflammation, and immune modulation in its disease attributes. Cholera was earlier thought to be a non-inflammatory diarrhea, but several reports provide evidence for an inflammatory response in cholera disease. These findings have come from studies with Vibrio cholerae strains devoid of CT gene ctx but induced inflammatory response. Studies have shown that while the CT essentially elicits an anti-inflammatory cytokine response, the accessory CTs have been associated with development of a proinflammatory cytokine response in gut. It is postulated that the increase in the inflammatory response to the V. cholerae (ctx) infection could be due to the absence of the immunomodulatory activity of the B subunit of CT that blocks the secretion of proinflammatory cytokines by macrophages, dendritic cells, and epithelial cells. Further studies are needed to understand the potential role of each of these toxins in the inflammation and immunomodulation in cholera disease.