ABSTRACT
Tumor necrosis factor like ligand 1A (TL1A), a member of TNF superfamily, regulates inflammatory response and immune defense. TL1A homologues have recently been discovered in fish, but their functions have not been studied. In this study, a TL1A homologue was identified in grass carp (Ctenopharyngodon idella) and its bioactivities were investigated. The grass carp tl1a (Citl1a) gene was constitutively expressed in tissues, with the highest expression detected in the liver. It was upregulated in response to infection with Aeromonas hydrophila. The recombinant CiTL1A was produced in bacteria and was shown to stimulate the expression of il1ß, tnfα, caspase 8 and ifnγ in the primary head kidney leucocytes. In addition, co-immunoprecipitation assay revealed that CiTL1A interacted with DR3 and induced apoptosis via activation of DR3. The results demonstrate that TL1A regulates inflammation and apoptosis and is involved in the immune defense against bacterial infection in fish.
ABSTRACT
CC chemokine ligand 19 (CCL19) plays a key role in the regulation of immune responses including homeostasis, inflammation, and immune tolerance. In this study, two variants of CCL19 homologues (CCL19a2 and CCL19b) and CCR7 were investigated in grass carp Ctenopharyngodon idella. The three genes were widely expressed in immune tissues and could be modulated by stimulation with LPS, PHA and poly(I:C), and infection with Flavobacterium columnare and grass carp reovirus. In an in vitro chemotaxis assay, the recombinant CCL19a2 and CCL19b were active to promote the migration of HEK293 T cells expressing CCR7 and leucocytes isolated from the gills, head kidney and spleen. Moreover, their chemotactive effects were validated in vivo. We found that the cells recruited by CCL19a2 and CCl19b are mainly monocytes/macrophages expressing high levels of IL-1ß, IFN-γ, colony stimulating factor 1 receptor (CSF1R) and MHC II. Our work suggests that CCL19a2 and CCl19b are involved in recruitment of antigen presenting cells in fish.
