Cell cycle arrest & apoptosis of epithelial cell line by cytolethal distending toxin positive Campylobacter jejuni.

ABSTRACT

Background & objectives: Campylobacter jejuni is the leading cause of gastroenteritis worldwide; cytolethal distending toxin (CDT) being an important virulence determinant. As its role in pathogenesis remains unclear, this study aims to investigate cell cycle arrest and apoptosis by CDT (+ve) and CDT (-ve) C. jejuni isolates on HeLa cells. Methods: Culture supernatants and lysates from 10 C. jejuni isolates [CDT (+ve) and CDT (-ve), five each] were incubated with HeLa cells. CDT activity on HeLa cells was confirmed by cell distension, cell cycle arrest by flowcytometry, and apoptosis by DNA fragmentation and flowcytometry. Results: Culture supernatant and lysate of only CDT (+ve) C. jejuni isolates produced cell distension. For CDT (+ve) and CDT (-ve) isolates, the cells at G2/M phase after 24, 48 and 72 h were 25.8 ± 3.79 per cent and 11.2 ± 0.58 per cent, 72.9 ± 2.44 and 14.3 ± 1.88 per cent, 93.5 ± 0.54 per cnet and 18.0 ± 1.80 per cent respectively (P<0.001). All CDT (+ve) isolates induced DNA fragmentation. Apoptosis induced by CDT (+ve) C. jejuni was significantly greater than CDT (-ve) (26.3 ± 3.49 % vs. 10.4 ± 1.01% at 24 h, 43.9 ± 2.40% vs. 17.6 ± 0.88% at 48 h, 68.4 ± 1.61% vs. 28.4 ± 1.62% at 72 h); (P<0.001). Interpretation & conclusion: The present study shows that CDT (+ve) C. jejuni contributes to the pathogenesis through epithelial cell G2/M phase arrest and apoptosis.