Expression profile of pro-inflammatory cytokines in head-kidney leucocytes of rohu following stimulation with poly I:C

Abstract

IL (interleukin)-6, TNF (tumor necrosis factor)-α, IL-1β and IL-8 are pro-inflammatory cytokines which augment host inflammatory reactions in response to multiple stresses or infections. In this study, we analyzed expression profile of these cytokines in head kidney leucocytes (HKL) isolated from healthy rohu (Labeo rohita) juveniles in response to poly I:C (50 µg/ml), a synthetic dsRNA virus analog stimulation. RNA was isolated from stimulated HKLs at 0, 1, 3, 6, 12, 24, and 72 and 96 h post-stimulation (hps) and the expression profile of IL-6, TNF-α, IL-1β and IL-8 was studied using qPCR. IL-6 expression was found to be significantly up-regulated at 72 hps whereas higher level of TNF-α was evident at 96 hps. With regard to IL-8 and IL-1β, a similar kind of expression pattern was observed where levels of both cytokines were higher at 24 hps. As activation of pro-inflammatory cytokine cascade against infection is considered as a marker of early immunity, induction of cytokine levels at or after 24 hps in rohu HKLs following poly I:C stimulation suggested the potential inflammatory role played by these cytokines during viral infection in fish.