Abstract

Chemokines are a superfamily of chemotactic cytokines that regulate cell activation, inflammation, and immune defense. In this study, chemokine CXCL10 from Nile tilapia ( Oreochromis niloticus ) was identified and characterized. The open reading frame of OnCXCL10 is 408 bp encoding polypeptides of 135 amino acids. The amino acid sequence analysis of CXCL10 confirms homology with other species and contains four conserved cysteine residues. Spatial mRNA expression analysis revealed that OnCXCL10 was highly expressed in spleen, and widely exhibited in other tissues including liver, intestine and head kidney. Following in vivo challenges with lipopolysaccharide (LPS), Streptococcus agalactiae and, Poly I: C separately, the expressions of OnCXCL10 were observed significantly elevated in liver, spleen, and head kidney. The transcriptional up-regulation of OnCXCL10 was also demonstrated in head kidney monocytes/macrophages after in vitro stimulations with LPS, S. agalactiae and Poly I: C. Furthermore, mRNA expression analysis revealed that OnCXCL10 could involved in C1q-mediated intracellular signaling pathways. Taken together, these studies indicated that CXCL10 played an important role in response to pathogen infection and C1q-mediated immune regulation of monocytes/macrophages in Nile tilapia ( Oreochromis niloticus ).