Prokaryotic expression of mouse interleukin 17A and its ability of stimulating RAW264.7 cell inflammatory factors expression

Objective To express and purify mouse interleukin 17A(mIL-17A) in E. coli and to analyze its ability of stimulating macrophage inflammatory factors expression. Methods The coding gene of mouse mIL-17A mature protein was amplified from mouse spleen cells by RT-PCR. PCR product was cloned into the prokaryotic expressing vector pET28a, and the resulting recombinant plasmid pET28a/mIL-17a was then transformed into the host E. coli strain BL21(DE3) for expression. The mIL-17A protein was identified by SDS-PAGE and Western blot. The recombinant protein was purified by the Ni-NTA affinity chromatography, and was further tested on the stimulation of cytokine and chemokine of RAW264.7 cells by ELISA and real-time quantity PCR in vitro. Results The mIL-17A with bioactivity was over-expressed and purified successfully, and the results of real-time PCR and ELISA showed that recombinant mIL-17A stimulated macrophage mRNA upregulation of IL-6, defensin β2 and Cxcl3 and secretion of defensin β2, Ccl3, Cxcl3,IFN-γ, IL-6 and IL-4. Interestingly, these effects could be blocked by the addition of anti-IL-17A neutralizing antibody partly. After treatment with mIL-17, 74. 87-fold of defensin β2 mRNA expression was increased comparing with that of untreated cells( P ＜0.01 ), while blocking with anti-IL-17A antibody the increase was only 5.4-fold(P ＜ 0.01 ). Conclusion The recombinant mIL-17A has a strong stimulation on secretion of cytokine and chemokine of macrophage, that maybe result to the enhancement of anti-infection ability of macrophage. Key words: Recombinant interleukin 17A; Macrophage inflammatory protein; Anti-infection immunity; Beta-defensin