Division of Molecular Parasitology and Immunology, Council of Scientific and Industrial Research-Central Drug Research Institute, Lucknow 226031, India.
Academy of Scientific and Innovative Research, Ghaziabad, Uttar Pradesh 201002, India; and.
J Immunol. 2020 Feb 1;204(3):596-610. doi: 10.4049/jimmunol.1900412. Epub 2019 Dec 27.
Immune evasion strategies adopted by involve the exploitation of suppressor of cytokine signaling (SOCS) proteins that are well-known negative regulators of the JAK/STAT pathway. However, the cellular mechanism underpinning the induction of SOCS isoforms and their role in breaching the multilevel regulatory circuit connecting the innate and adaptive arms of immunity are still ambiguous during experimental visceral leishmaniasis. Using bone marrow-derived macrophages (BMMфs) and CD4 T cells, we observed that preferentially upregulates SOCS1 and SOCS3 expression in macrophages and T cells, respectively, whereas the SOCS1 level remains consistently high in BMMфs and SOCS3 expression is pronounced and long lasting in T cells. Consequently, this inhibits STAT1-mediated IL-12 induction in macrophages & STAT4-mediated IFN-γ synthesis in T cells. Mechanistically, PI3K/Akt-mediated SRF activation promotes nuclear translocation and binding of Egr2 to SOCS1 promoter for its early induction in infected BMMфs. Additionally, activates IDO/kynurenine/AHR signaling in BMMфs to maintain prolonged SOCS1 expression. Later, PGE2, secreted from infected BMMфs induces cAMP-PKA pathway by binding to the EP2/EP4 receptor of CD4 T cells, leading to SP1, CREB, and GATA1 activation and SOCS3 expression. Small interfering RNA-mediated silencing of SOCS1 and SOCS3 in macrophage and T cells, respectively, restored IL-12 and IFN-γ cytokine levels and BMMф-T cell interaction. Vivo morpholino-mediated silencing of SOCS1 and SOCS3 resulted in protective cytokine responses, thereby reducing organ parasite burden significantly in -infected BALB/c mice. Collectively, our results imply that orchestrates different SOCS isoforms to impair macrophage-T cell cross-talk and preserve its own niche.
寄生虫采用的免疫逃避策略涉及利用细胞因子信号转导抑制因子(SOCS)蛋白,SOCS 蛋白是 JAK/STAT 通路的负调控因子。然而,在实验性内脏利什曼病中,SOCS 同工型诱导的细胞机制及其在破坏连接先天免疫和适应性免疫的多层次调节回路中的作用仍不明确。我们使用骨髓来源的巨噬细胞(BMMф)和 CD4 T 细胞观察到,寄生虫优先上调巨噬细胞和 T 细胞中的 SOCS1 和 SOCS3 表达,而 BMMф 中的 SOCS1 水平保持持续升高,T 细胞中的 SOCS3 表达明显且持久。因此,这抑制了 STAT1 介导的巨噬细胞中 IL-12 的诱导和 STAT4 介导的 T 细胞中 IFN-γ 的合成。从机制上讲,PI3K/Akt 介导的 SRF 激活促进 Egr2 的核易位和结合到 SOCS1 启动子,从而在感染的 BMMф 中早期诱导 SOCS1。此外,寄生虫在 BMMф 中激活 IDO/犬尿氨酸/AHR 信号通路,以维持 SOCS1 的持续表达。随后,从感染的 BMMф 分泌的 PGE2 通过与 CD4 T 细胞上的 EP2/EP4 受体结合,激活 cAMP-PKA 途径,导致 SP1、CREB 和 GATA1 激活和 SOCS3 表达。在巨噬细胞和 T 细胞中分别用小干扰 RNA 沉默 SOCS1 和 SOCS3,恢复了 IL-12 和 IFN-γ 细胞因子水平以及 BMMф-T 细胞相互作用。体内用 morpholino 介导的 SOCS1 和 SOCS3 沉默导致保护性细胞因子反应,从而显著减少 -感染 BALB/c 小鼠中的器官寄生虫负担。总之,我们的研究结果表明寄生虫精心策划了不同的 SOCS 同工型,以损害巨噬细胞-T 细胞串扰并维持自身生态位。