Inhibition of lipopolysaccharide-induced macrophage IL-12 production by Leishmania mexicana amastigotes:: The role of cysteine peptidases and the NF-κB signaling pathway
Inhibition of lipopolysaccharide-induced macrophage IL-12 production by Leishmania mexicana amastigotes:: The role of cysteine peptidases and the NF-κB signaling pathway
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DOI：
10.4049/jimmunol.173.5.3297
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发表时间：
2004-09-01
影响因子：
4.4
通讯作者：
Plevin, R
中科院分区：
文献类型：
--
作者：
Cameron, P;McGachy, A;Plevin, R
感染病损来源的墨西哥利什曼原虫可抑制小鼠骨髓来源的巨噬细胞产生内毒素诱导的IL-12。这种作用与半胱氨酸肽酶B(CPB)的表达有关，因为CPB缺失突变体的无鞭毛体抑制IL-12产生的能力有限，而用CPB抑制剂组织蛋白酶抑制剂IV预先孵育细胞能够抑制野生型无鞭毛体的作用。野生型无鞭毛体感染后，IkappaBalpha和IkappaBβ蛋白及相关蛋白NFkappaB的降解呈时间依赖性。这种影响不发生在CPB缺失突变体的无鞭毛体或野生型前鞭毛体中，因为它们不表达可检测到的CPB。无鞭毛体感染也抑制了NF-kappaB的DNA结合，但仍可观察到p65-kappaB裂解片段的核移位。半胱氨酸肽酶抑制剂可抑制无鞭毛体诱导的IkappaBalpha、IkappaBbeta和核因子-kappaB的降解，而CPB的无鞭毛体特异性同工酶重组CPB2.8在体外可降解GST-IkappaBalpha。LPS介导的IkappaBalpha和IkappaBβ的降解不受这些抑制剂的影响，这证实了无鞭毛体对IkappaBalpha、IkappaBbeta和NF-kappaB的降解不是由受体驱动的、蛋白酶体介导的切割。感染无鞭毛体的骨髓巨噬细胞可以裂解JNK和ERK，但不能裂解p38MAPK，而用半胱氨酸肽酶抑制剂预先孵育可阻止这些蛋白的降解，但不能增强蛋白激酶的活性。总之，我们的结果表明，L墨西哥无鞭毛体特异性半胱氨酸肽酶是该寄生虫通过核因子-kappaB调节信号从而抑制IL-12产生的中心。
Infection with lesion-derived Leishmania mexicana amastigotes inhibited LPS-induced IL-12 production by mouse bone marrow-derived macrophages. This effect was associated with expression of cysteine peptidase B (CPB) because amastigotes of CPB deletion mutants had limited ability to inhibit IL-12 production, whereas preincubation of cells with a CPB inhibitor, cathepsin inhibitor IV, was able to suppress the effect of wild-type amastigotes. Infection with wild-type amastigotes resulted in a time-dependent proteolytic degradation of IkappaBalpha and IkappaBbeta and the related protein NF-kappaB. This effect did not occur with amastigotes of CPB deletion mutants or wild-type promastigotes, which do not express detectable CPB. NF-kappaB DNA binding was also inhibited by amastigote infection, although nuclear translocation of cleaved fragments of p65 NF-kappaB was still observed. Cysteine peptidase inhibitors prevented IkappaBalpha, IkappaBbeta, and NF-kappaB degradation induced by amastigotes, and recombinant CPB2.8, an amastigote-specific isoenzyme of CPB, was shown to degrade GST-IkappaBalpha in vitro. LPS-mediated IkappaBalpha and IkappaBbeta degradation was not affected by these inhibitors, confirming that the site of degradation of IkappaBalpha, IkappaBbeta, and NF-kappaB by the amastigotes was not receptor-driven, proteosomal-mediated cleavage. Infection of bone marrow macrophages with amastigotes resulted in cleavage of JNK and ERK, but not p38 MAPK, whereas preincubation with a cysteine peptidase inhibitor prevented degradation of these proteins, but did not result in enhanced protein kinase activation. Collectively, our results suggest that the amastigote-specific cysteine peptidases of L mexicana are central to the ability of the parasite to modulate signaling via NF-kappaB and consequently inhibit IL-12 production.