Recombinant expression of Epinephelus lanceolatus serum amyloid A (ElSAA) and analysis of its macrophage modulatory activities

Bor Chyuan Su, Wen Chun Lin, Han Ning Huang, Jyh Yih Chen

研究成果: 雜誌貢獻文章同行評審

2 引文 斯高帕斯(Scopus)


Serum amyloid A (SAA) is an acute-phase protein that plays a crucial role in the inflammatory response. In this study, we identified an SAA homolog from Epinephelus lanceolatus (ElSAA). Molecular characterization revealed that ElSAA contains a fibronectin-like motif that is typical of SAAs. Recombinant ElSAA protein (rElSAA) was produced in E. coli BL21 (DE3) cells and purified as a soluble protein. To analyze its biological activity, mouse Raw264.7 macrophage cells were treated with various concentrations of rElSAA. Expression of several inflammation-related cytokines, including tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, IL-6, and IL-10, was induced by rElSAA. This protein also triggered macrophage differentiation, as evidenced by increases in cell size and complexity. To determine whether rElSAA regulates macrophage polarization, we assessed gene expression of M1 and M2 markers. The results demonstrated that rElSAA induced the expression of both M1 and M2 markers, suggesting that it promotes the differentiation of macrophages into a mixed M1/M2 phenotype. To evaluate whether rElSAA enhances phagocytosis via an opsonization-dependent mechanism, GFP-labeled E. coli cells were pretreated with rElSAA, followed by incubation with Raw264.7 cells. Flow cytometry was used to monitor the phagocytic uptake of GFP-labeled E. coli by macrophages. Surprisingly, incubating E. coli with rElSAA did not enhance bacterial uptake by macrophages. However, preincubating Raw264.7 cells with various concentrations of rElSAA, followed by infection with E. coli (multiplicity of infection = 20 or 40), resulted in a clear enhancement of macrophage phagocytic capacity. In conclusion, we have identified SAA from E. lanceolatus and have demonstrated that rElSAA promotes inflammatory cytokine production and macrophage differentiation. In addition, rElSAA enhances phagocytosis of bacteria by macrophages via an opsonization-independent mechanism.
頁(從 - 到)276-286
期刊Fish and Shellfish Immunology
出版狀態已發佈 - 5月 1 2017

ASJC Scopus subject areas

  • 環境化學
  • 海洋科學


深入研究「Recombinant expression of Epinephelus lanceolatus serum amyloid A (ElSAA) and analysis of its macrophage modulatory activities」主題。共同形成了獨特的指紋。