D-dopachrome tautomerase from Japanese sea bass (Lateolabrax japonicus) is a chemokine-like cytokine and functional homolog of macrophage migration inhibitory factor.

摘要: D-dopachrome tautomerase (DDT), a member of the macrophage migration inhibitory factor (MIF) protein superfamily, is newly described cytokine with chemokine-like characteristics. However, research on fish DDT remains limited. In this study, we identified homolog (LjDDT) from Japanese sea bass, Lateolabrax japonicus. Sequence analysis showed that LjDDT had typical sequence features known and MIF homologs was most closely related to rock bream ( Oplegnathus fasciatus). transcripts were detected in all tested tissues healthy highest expression found liver. Upon infection Vibrio harveyi, significantly down-regulated three tissues, including liver, spleen, head kidney. Recombinant (rLjDDT) corresponding antibody (anti-rLjDDT) subsequently prepared. The administration 100 μg/g anti-rLjDDT statistically significant protective effect survival V. harveyi-infected fish. Moreover, rLjDDT able induce monocytes/macrophages (MO/MФ) lymphocytes both vitro vivo, but without influence neutrophils. exhibited chemotactic activity for lipopolysaccharide (LPS) -stimulated M1-type MO/ MΦ vitro, not cAMP-stimulated M2-type MO/MΦ. Furthermore, knockdown LjCD74, LjCXCR4, rLjDDT-enhanced MO/MΦ relieved rLjMIF-inhibited These results indicate LjCD74 may be major receptor LjMIF bass Combined rLjDDT+ rLjMIF treatment no MsiRNA, LjCD74si-, or LjCXCR4sitreated compared control group, suggesting roles antagonistic. conclusion, our study demonstrates first time play role immune responses against bacterial through recruitment via mediation CD74 as an antagonist MIF.