Inflammatory cytokines responses of common carp, Cyprinus carpio, leucocytes in vitro treated by immunostimulants

Cytokines are important regulators of the immune system, and identifying fish cytokines has potential applications for the development of vaccines and/or immunostimulants application in fisheries. In order to understand the immune-related genes triggered by immunostimulants derived from pathogens, we investigated the effects of agonists (lipopolysaccharide (LPS), Poly I:C, and imiquimod) of three Toll-like receptor (TLR)—TLR4, TLR3, and TLR7, respectively—on the expression level of 10 cytokine genes—interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), CXC-chemokine, interleukin-10 (IL-10), type1 interferon (1INF), IFN-γ1, IFN-γ2, Mx protein, and interleukin-12 (IL-12p35 and IL-12 p40)—in the head kidney leukocytes of common carp (Cyprinus carpio L.). All cytokine genes tested, except for type-1 IFN, were significantly up-regulated after LPS treatment. Poly I:C and imiquimod treatment resulted in striking up-regulation of most of the genes examined, particularly for the interferon genes as compared with the control groups. These results clearly demonstrate that TLRs agonists elicit the signaling pathways for cytokines production and initiation of innate immune responses in common carp. The development of strategies to control the pathogen load and of immune-prophylactic measures must be addressed further to realize the economic potential of fish production.