Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA.
Department of Cellular Biology, University of Georgia, Athens, GA.
J Immunol. 2023 Oct 1;211(7):1123-1133. doi: 10.4049/jimmunol.2300373.
Host cell invasion by Trypanosoma cruzi is a markedly silent process, with limited host transcriptional changes indicative of innate immune recognition, except for a modest type I IFN (IFN-I) response. In this study, we show that T. cruzi-induced IFN-β production was nearly abolished in primary murine cGAS-/- or stimulator of IFN genes (STING)-deficient (STINGGt) macrophages and fibroblasts. T. cruzi infection did not impact the ability of IFN-regulatory factor reporter macrophages to respond to classical cGAS-STING agonists, indicating that the limited IFN-β induction is not due to active parasite suppression. cGAS-/-, STINGGt, and IFN-α/β receptor-/- (IFNAR-/-) macrophages infected with T. cruzi yielded significantly higher numbers of amastigotes compared with wild-type macrophages; however, the impact of the STING pathway during infection in vivo is more complex. Despite an initial increase in parasite growth, STINGGt and IFNAR-/- mice ultimately had lower parasite burden in footpads as compared with wild-type mice, demonstrating a role for IFN-I expression in potentiating parasite growth at the infection site. STING pathway activation had little impact on parasite levels in the skeletal muscle; however, in the heart, cGAS-/- and STINGGt mice, but not IFNAR-/- mice, accumulated higher acute parasite loads, suggesting a protective role of STING sensing of T. cruzi in this organ that was independent of IFN-I. Together, these results demonstrate that host cGAS-STING senses T. cruzi infection, enhancing parasite growth at the site of entry, and contributes to acute-phase parasite restriction in the heart, a major site of tissue damage in chronic T. cruzi infection.
宿主细胞被克氏锥虫侵袭是一个显著沉默的过程,除了适度的 I 型干扰素(IFN-I)反应外,宿主转录变化有限,表明先天免疫识别。在这项研究中,我们表明,在原代小鼠 cGAS-/-或干扰素基因刺激因子(STING)缺陷(STINGGt)巨噬细胞和成纤维细胞中,克氏锥虫诱导的 IFN-β产生几乎被完全消除。克氏锥虫感染不会影响 IFN 调节因子报告巨噬细胞对经典 cGAS-STING 激动剂的反应能力,表明有限的 IFN-β诱导不是由于寄生虫的主动抑制。与野生型巨噬细胞相比,感染克氏锥虫的 cGAS-/-、STINGGt 和 IFN-α/β受体-/-(IFNAR-/-)巨噬细胞产生的阿米巴原虫数量明显更高;然而,STING 途径在体内感染过程中的影响更为复杂。尽管寄生虫的生长最初增加,但与野生型小鼠相比,STINGGt 和 IFNAR-/-小鼠最终在足部的寄生虫负荷较低,表明 IFN-I 表达在感染部位增强寄生虫生长的作用。STING 途径的激活对骨骼肌中的寄生虫水平几乎没有影响;然而,在心组织中,cGAS-/-和 STINGGt 小鼠,而不是 IFNAR-/-小鼠,积累了更高的急性寄生虫负荷,这表明 STING 对克氏锥虫的感应在该器官中具有保护作用,这种作用独立于 IFN-I。总之,这些结果表明,宿主 cGAS-STING 感知克氏锥虫感染,增强了入侵部位的寄生虫生长,并有助于心脏中急性阶段的寄生虫限制,心脏是慢性克氏锥虫感染中组织损伤的主要部位。
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