Molecular characterization, expression and functional analysis of goldfish (Carassius aurutus L.) interferon gamma

We report on the characterization and functional analysis of IFNγ of the goldfish. Quantitative analysis indicated the highest expression of goldfish IFNγ in the spleen, with lower expressions in brain, gill, kidney, heart, intestine and muscle. An increase in IFNγ expression was observed in kidney leukocytes following stimulation with PHA, PolyI:C and during mixed leukocyte reaction. IFNγ was expressed in different goldfish immune cell populations and this expression was upregulated in several of these populations following treatment of cells with recombinant goldfish TNFα-2. A recombinant form of goldfish IFNγ (rgIFNγ) was produced and functionally analyzed. The rgIFNγ primed goldfish macrophages and neutrophils for enhanced respiratory burst responses and increased the phagocytic and nitric oxide responses of macrophages. Furthermore, treatment of goldfish macrophages with rgIFNγ induced increased expression of several proinflammatory genes including TNFα-1, TNFα-2, IL-β-1, IL-β-2, IL-12-p35, IL-12-p40, RSAD-2 (=viparin), CXCL-8 (=IL-8), CCL-1, iNOS A and B and IFNγ, and decreased the expression of TLR-3, while the expression of TGFβ remained unchanged. Our results indicate that IFNγ is a central proinflammatory cytokine of teleosts.