LAUSR

ABSTRACT High mobility group box protein 1 (HMGB1) acts as a potent proinflammatory cytokine that involves in the pathogenesis of diverse inflammatory and infectious disorders. In previous study, we identified a homolog of HMGB1 in the Lampetra japonica(L‐HMGB1), and further revealed that L‐HMGB1 was able to induce the production of tumor necrosis factor‐&agr; (TNF‐&agr;) in activated human acute monocytic leukemia cells. However, the role of L‐HMGB1 played in lamprey was unknown. Here, we found that L‐HMGB1 was located in the cytoplasm of lamprey leukocytes and supraneural body (SB) cells. Importantly, we demonstrated that L‐HMGB1 participated in activation of various key molecules in inflammation signaling pathway. LPS also promoted the release of L‐HMGB1 from SB cells similar to Hu‐HMGB1, and then extracellular L‐HMGB1 in turn induced the release of cytokines. This study revealed that the synergistic action of LPS and L‐HMGB1 played a crucial role in inflammation in lamprey. Our results suggested that lampreys used L‐HMGB1 to activate their innate immunity for the purpose of pathogen defense. HighlightsL‐HMGB1 directly activated antimicrobial effector in lamprey supraneural body cells similar to LPS‐stimulated.L‐HMGB1 increased L‐TLRs, L‐MyD88 and L‐NF‐kB expression in supraneural body cells.L‐HMGB1 leaded to inflammation activation, antibacterial protection and host defense in lamprey.