STAT4 mediated immunity to Pneumocystis

STAT4介导的肺孢子虫免疫

• 批准号: 8274651
• 负责人: Chad Steele
• 金额: $ 18.31万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-06 至 2014-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8274651
• 关键词: Address; Animals; CCL2 gene; CD3 Antigens; CD4 Positive T Lymphocytes; CXCL1 gene; Cells; Chemokine Receptor Gene; Chronic Obstructive Airway Disease; Chronic lung disease; Coupled; Cytokine Receptors; Data; Development; Epidemic; Experimental Models; HIV; Host Defense; Human; Immune; Immune response; Immunity; Immunosuppression; In Vitro; Individual; Infection; Interferons; Interleukin-1; Interleukin-18; Interleukin-2; Interleukin-4; Investigation; Lung; Mediating; Mediator of activation protein; Mus; Pathway interactions; Patients; Phenotype; Pneumocystis; Pneumocystis Infections; Pneumocystis carinii Pneumonia; Pneumonia; Predisposing Factor; Production; RANTES; Research Project Grants; Role; STAT1 gene; STAT4 protein; STAT6 Transcription Factor; Signal Transduction; Species Specificity; T-bet protein; The Jackson Laboratory; Time; cytokine; immunosuppressed; interleukin-12 subunit p35; pathogen; response; transcription factor

DESCRIPTION (provided by applicant): Pneumocystis has risen to the forefront of lethal, opportunistic lung infections as a result of its close association with the HIV epidemic, yet this atypical fungal pathogen is becoming increasingly associated with pharmacologic-driven immunosuppression as well as patients with chronic lung diseases such as COPD. Loss of CD4+ T cells is a known predisposing factor to Pneumocystis pneumonia, yet how CD4+ T cells specifically control Pneumocystis infection is not known. The lack of the ability to culture Pneumocystis in vitro coupled with high species specificity has limited investigations into human CD4 T cell mediated responses to Pneumocystis. T helper immunity to Pneumocystis is complicated, in that mice deficient in the T helper type 1 (Th1) signature cytokine IFN-? or the Th2 signature cytokine IL-4 are not more susceptible to infection than wild-type animals. Although some data points to Th2 responses being protective, in many experimental models, evidence mostly supports a role for Th1 responses in mediating protective immunity to P. murina. Delayed (higher burden at 2-3 weeks compared to wild-type), but intact (no differences in burden at 4-5 weeks compared to wild-type) clearance of Pneumocystis has been observed in CD4-competent IFN-?R deficient mice, IL-12p35 deficient mice and IL-23p19 deficient mice. One commonality between these cytokines is that IFN-?, IL-12p35 and IL-23p19 each activate the pro-Th1 transcription factor Signal Transducer and Activator of Transcription 4 (STAT4). Therefore, to more formally address the role of T helper development in P. murina host defense, we focused on specific transcription factors that drive Th1 and Th2 responses. In preliminary studies, we show that CD4-competent mice deficient in STAT4, but not the pro-Th2 transcription factor STAT6, are unable to clear P. murina from the lungs 4 weeks post-challenge. At 2 weeks post-challenge, when P. murina burden was similar between all groups, STAT4-/- mice demonstrated reduced lung levels of IL-1?, IL- 1?, CXCL1, CCL2 and CCL5 as well as reductions in total CD3+, CD3+/CD4+ and MHC II+ cells in lung digests. Upon anti-CD3 stimulation, STAT4-/- CD4+ T cells displayed impaired production of IL-2 and IFN-?. As P. murina lung clearance in IFN-?R, IL-12p35 and IL-23p19 deficient mice was impaired early in infection, rather than late (4 weeks) as observed in STAT4-/- mice, these results suggest that an additional mediator may synergize with IFN-?, IL-12p35 or IL-23p19 to maximize STAT4 activation and the subsequent anti- Pneumocystis immune response. To this end, we show that the STAT4 activator IL-18, as well as the Th1 promoting cytokine IL-27, are induced in the lungs during P. murina infection. Surprisingly, we found that mice deficient in the Th1-associated transcription factors T-bet or STAT1 did not display impaired clearance of P. murina 4 weeks post-challenge, indicating a strict requirement for STAT4 in lung clearance of P. murina. Therefore, the focus of this R21 Exploratory/Developmental Research Grant is to define mechanisms of STAT4 induction and mechanisms of STAT4-mediated adaptive immune defense pathways that mediate lung clearance of P. murina. Our central hypothesis is that signaling through STAT4 mediates protective lung immunity against Pneumocystis. To address this hypothesis, we have proposed the following two independent, interrelated Aims: (1) Establish roles for IL-18 and IL-27 in STAT4 signaling and host defense against P. murina lung infection and (2) Elucidate the STAT4-dependent CD4 T cell phenotype during Pneumocystis lung infection.

描述（由申请人提供）：由于肺孢子菌与 HIV 流行密切相关，因此它已成为致命性机会性肺部感染的最前线，但这种非典型真菌病原体与药物驱动的免疫抑制以及慢性肺病（如慢性阻塞性肺病）患者的关系越来越密切。 CD4+ T 细胞的缺失是肺孢子虫肺炎的已知诱发因素，但 CD4+ T 细胞如何特异性控制肺孢子虫感染尚不清楚。由于缺乏体外培养肺孢子虫的能力，加上高度的物种特异性，限制了对人类 CD4 T 细胞介导的肺孢子虫反应的研究。 T 辅助细胞对肺孢子虫的免疫很复杂，因为小鼠缺乏 1 型辅助 T (Th1) 标志性细胞因子 IFN-α。或 Th2 特征细胞因子 IL-4 并不比野生型动物更容易受到感染。尽管一些数据表明 Th2 反应具有保护性，但在许多实验模型中，证据大多支持 Th1 反应在介导鼠鼠保护性免疫中的作用。在 CD4 活性 IFN-γR 缺陷型小鼠、IL-12p35 缺陷型小鼠和 IL-23p19 缺陷型小鼠中观察到肺孢子虫的清除延迟（与野生型相比，2-3 周时负担较高），但完整（与野生型相比，4-5 周时负担没有差异）。这些细胞因子之间的一个共同点是 IFN-α、IL-12p35 和 IL-23p19 各自激活前 Th1 转录因子信号转导子和转录激活子 4 (STAT4)。因此，为了更正式地探讨 T 辅助细胞发育在鼠鼠宿主防御中的作用，我们重点关注驱动 Th1 和 Th2 反应的特定转录因子。在初步研究中，我们表明，缺乏 STAT4（但缺乏前 Th2 转录因子 STAT6）的 CD4 活性小鼠无法在攻击后 4 周从肺部清除鼠鼠。攻击后 2 周，当所有组之间的 P. murina 负荷相似时，STAT4-/- 小鼠表现出肺部 IL-1?、IL-1?、CXCL1、CCL2 和 CCL5 水平降低，以及肺部消化物中总 CD3+、CD3+/CD4+ 和 MHC II+ 细胞减少。在抗 CD3 刺激后，STAT4-/- CD4+ T 细胞表现出 IL-2 和 IFN-γ 的产生受损。由于 IFN-γR、IL-12p35 和 IL-23p19 缺陷小鼠的肺清除率在感染早期受损，而不是像在 STAT4-/- 小鼠中观察到的晚期（4 周），这些结果表明额外的介质可能与 IFN-γ、IL-12p35 或 IL-23p19 协同作用，以最大化 STAT4 激活和随后的抗肺孢子虫免疫 回复。为此，我们发现在 P. murina 感染期间，肺部会诱导 STAT4 激活剂 IL-18 以及 Th1 促进细胞因子 IL-27。令人惊讶的是，我们发现缺乏 Th1 相关转录因子 T-bet 或 STAT1 的小鼠在攻击后 4 周并未表现出鼠鼠的清除受损，这表明鼠鼠肺清除对 STAT4 的严格要求。因此，这项 R21 探索性/发展研究资助的重点是定义 STAT4 诱导机制以及 STAT4 介导的适应性免疫防御途径（介导鼠肺清除）的机制。我们的中心假设是，通过 STAT4 的信号传导介导针对肺孢子虫的保护性肺免疫。为了解决这一假设，我们提出了以下两个独立、相互关联的目标：(1) 确定 IL-18 和 IL-27 在 STAT4 信号传导和宿主防御鼠疟原虫肺部感染中的作用；(2) 阐明肺孢子虫肺部感染期间 STAT4 依赖性 CD4 T 细胞表型。