Investigation of the anti-apoptotic activity of ozone therapy in rainbow trout macrophages infected with Yersinia ruckeri

Yersinia ruckeri is the causal agent of enteric redmouth (ERM) in trout. This study aimed to investigate the effectiveness of nontoxic ozone on Y. ruckeri-infected trout cells in in vitro conditions. Rainbow trout macrophages (RTS-11) were exposed to Y. ruckeri for 24 h after being incubated with the ozonized medium at nontoxic concentration. Effective concentrations of nontoxic ozone (3 gamma) and bacteria (1.5 x 108 cfu/mL) were determined by viability tests. The expression of caspases 1, 3, 8, and 12 was determined by real-time PCR and protein levels investigated by ELISA method. Apoptotic-necrotic cell ratios were determined by acridine orange and ethidium bromide staining. Bacterial stimulations of caspases (1, 3, 8, and 12) were suppressed by ozone mostly at the translational level. While bacterial infection increased the count of apoptotic and necrotic cells at different stages, ozone significantly reduced this condition. Obtained data indicate possible use of nontoxic ozone as a safe and effective treatment alternative for increasing host defenses and eliminating the infection in the case of yersiniosis in fish.