日本血吸虫热休克蛋白60 kDa的免疫原性及保护性研究

Studies on immunogenicity and immunoprotection induced by heat shock protein 60 kDa of Schistosoma japonicum in mice

目的研究日本血吸虫热休克蛋白60 kDa(SjHSP60)免疫原性,评价其免疫保护性及可能机制。方法通过在线生物信息学软件预测SjHSP60的B细胞表位,随后用SjHSP60免疫BALB/c小鼠后检测特异性抗体水平和淋巴细胞增殖以评估其免疫原性,进一步通过攻击感染实验观察其免疫保护效果;最后分选免疫小鼠的CD4^+CD25^+调节性T细胞(Treg)与CD4^+CD25^-T细胞共培养,通过细胞增殖实验检测CD4^+CD25^+Treg细胞的抑制功能。结果生物信息学预测结果显示,SjHSP60中存在多个B细胞表位的优势区段。SjHSP60可在小鼠体内诱导特异性抗体(P<0.01),也可诱导小鼠脾细胞发生增殖(P<0.01)和分泌IFN-γ(P<0.01);但攻击感染实验显示,SjHSP60免疫小鼠体内虫荷(P>0.05)、卵荷(P>0.05)均未显著减少。体外共培养实验表明,SjHSP60可显著增强小鼠CD4^+CD25^+Treg细胞的免疫抑制功能(P<0.01)。结论SjHSP60对宿主免疫系统可发挥"双刃剑"作用,即在诱导特异性抗感染免疫应答的同时又可增强免疫抑制功能,从而削弱了其免疫保护作用。

Objective To evaluate the immunogenicity and immunoprotective effect of heat shock protein 60 kDa （SjHSP60） of Schistosoma japonicum in mice after immunization and challenge infection, and explore the mechanism. Methods B cell/antibody-related databases and analysis tools were used to predict B-cell epitopes of SjHSP60. The mice were immunized with the recombinant SjHSP60 and challenged with S. japonicum cercariae. SjHSP60-specific antibodies in serum were detected by ELI- SA. The level of splenocyte proliferation was determined by 3H-TdR incorporation. Ex vivo suppression assay was performed to investigate the effects of CD4＋CD25＋ regulatory T cells （Tregs） induced by SjHSP60. Results SjHSP60 possessed multiple pre dominant regions of B-cell epitopes. SjHSP60 induced a significant increase in both SjHSP60-specific IgG levels （P 〈 0.01） and splenocyte proliferation （P 〈 0.01） with a higher IFN-γ/production （P 〈 0.01）. However, the immunization with SjHSP60 resulted no significant reduction in adult worms （P 〉 0.05） and liver-accumulated eggs （P 〉 0.05） in S. japonicum-infected mice. Ex vivo assay showed that CD4＋CD25＋ Tregs from SjHSP60-immunized mice enhanced immunosuppressive activity. Conclusion SjH- SP60 has a dual role in host immune system, being involved in the induction of dominant humoral and cellular immune responses as well as in the enhancement of immunosuppression.