Role of HSP65 in host protection against intracellular protozoan infection.

我们先前报道，宿主65 kDa热休克蛋白(HSP65)的诱导与弓形虫感染的保护密切相关，而T细胞，尤其是Gammadelta T细胞在保护和表达HSP65方面起着重要作用。弓形虫感染诱导巨噬细胞表达HSP65，而Gammadelta T细胞的耗竭导致其表达显著减弱。RT-PCR法检测该T细胞亚群分泌干扰素-γ和肿瘤坏死因子-α。众所周知，这些细胞因子可以激活巨噬细胞。在感染前用相应的抗体中和这些细胞因子会抑制HSP65的表达，这表明Gammadelta T细胞的HSP65表达依赖于这些细胞因子。我们推测HSP65通过巨噬细胞的保存参与保护，这与其天然的“分子伴侣”作用相吻合。体外感染弓形虫的巨噬细胞和巨噬细胞系J774细胞发生凋亡。在上述细胞因子的诱导下，这些细胞上HSP65的表达可以阻止它们的凋亡。然而，这种作用被该蛋白的反义寡核苷酸所逆转。这些结果表明，HSP65可防止巨噬细胞的凋亡，从而起到保护作用。在感染大利什曼原虫和克氏锥虫的小鼠中，保护性免疫与HSP65的表达也存在类似的关系。

We previously reported that induction of host 65 kDa heat shock protein (HSP65) closely correlates with protection against Toxoplasma gondii (T.gondii) infection, and T cells, especially gammadelta T cells, play an important role in protection and HSP65 expression.T.gondii infection induces HSP65 expression in peritoneal macrophages and depletion of gammadelta T cells resulted in marked attenuation of its espression. This T cell subset secretes IFN-gamma and TNF-alpha as determined by using RT-PCR method. These cytokines are known to activate macrophages. Neutralization of these cytokines with corresponding antibodies prior to infection suppresses HSP65 expression, indicating that HSP65 expression attributed by gammadelta T cells is dependent on these cytokines. We speculate that HSP65 participates in protection by means of preservation of macrophages, in coincident with its native role as "molecular chaperon". Peritoneal macrophages and macrophage cell line, J774 cells infected in vitro with T.gondii undergo apoptosis. Expression of HSP65 on these cells, being induced with above cytokines, prevents them from apoptosis. However, this effect is reversed by the addition of antisense oligonucleotide for this protein. These results indicate that HSP65 prevent apoptosis of macrophages, which contributes to protection.A similar relationship between protective immunity and HSP65 expression was also seen in mice infected with Leishmania major and Trypanosoma cruzi.