Targeting immune inhibitory molecule SUSD2 to reverse immunosuppression

项目总结/摘要 脓毒症是许多重症监护病房中最常见的死亡原因，并且是患者的主要负担。 美国医疗保健系统。尽管重症监护技术和机械通气支持取得了进展， 脓毒症的药物选择有限，这反映了对宿主依赖性 导致这种病理生理紊乱的机制。大量的证据来自最近的临床和 实验性脓毒症研究表明，由于细胞严重死亡，免疫抑制状态延长 和淋巴细胞功能障碍是脓毒症引起的死亡率的关键决定因素。因此，恢复 通过阻断免疫抑制分子的淋巴细胞存活和功能可能代表一种有希望的 用于治疗脓毒症的治疗方案。在本建议书中，我们旨在研究一个 以前未识别的免疫抑制分子SUSD 2（sushi domain containing 2）， 脓毒症引起的免疫抑制通过无偏倚的基因分析，我们先前的研究 鉴定了一种细胞表面分子SUSD 2，其高表达与免疫抑制相关， 在实验癌症模型中的表型。在这个提议中，我们观察到T细胞中Susd 2表达升高， 与非败血症对照相比，实验性败血症动物和败血症患者的淋巴细胞。遗传 SUSD 2（Susd 2 −/−）的缺失导致动物存活率显著提高，T细胞凋亡减弱。 在盲肠结扎穿孔（CLP）诱导的多微生物脓毒症模型中，机械地，我们 初步研究发现SUSD 2对白细胞介素-2受体（IL-2 R）信号传导具有抑制作用， 建立了T细胞存活和效应子功能所必需的途径。该提案的目的是审查 SUSD 2在微生物脓毒症中对T淋巴细胞死亡和功能障碍的因果作用。我们 假设1）SUSD 2表达升高导致IL-2依赖性细胞存活和效应细胞减少， T淋巴细胞的功能，导致持续的免疫抑制状态和更差的疾病结果， 脓毒症; 2）增强STAT 5（信号转导和转录激活因子5）和BATF（碱性磷酸酶）的活化 亮氨酸拉链ATF样转录因子）信号转导维持细胞存活和效应子在Susd 2 −/− T中的功能 3）SUSD 2阻断逆转脓毒症诱导的细胞死亡和T淋巴细胞功能障碍。 将进行循环免疫细胞的单细胞RNA测序分析，以检查抑制性免疫细胞。 SUSD 2在单细胞水平对脓毒症后T细胞应答的影响。我们将测试是否用 中和抗SUSD 2抗体逆转从脓毒症患者分离的功能失调的T细胞。结果进行 研究将提供实验和临床证据，支持SUSD 2对 脓毒症诱导的免疫抑制，这可能会导致脓毒症的新方法的发展 治疗

Project Summary/Abstract Sepsis is the most common cause of death in many intensive care units and represents a major burden to the US health care system. Despite advances in intensive care technology and mechanical ventilator support, pharmacological options for sepsis are limited, which reflects an insufficient understanding of host-dependent mechanisms that underlie this pathophysiological disorder. A wealth of evidence from recent clinical and experimental sepsis studies indicates that a prolonged immunosuppressive status, due to profound cell death and dysfunction of lymphocytes, is a critical determinant of sepsis-elicited mortality. Therefore, restoration of lymphocyte cell survival and functions by blocking immune inhibitory molecule(s) may represent a promising therapeutic regimen for treating sepsis. In this Proposal, we aim to study the role and mechanism of a previously unrecognized immune inhibitory molecule called SUSD2 (sushi domain containing 2) in promoting sepsis-induced immunosuppression. Through an unbiased gene profiling assay, our previous study has identified a cell surface molecule SUSD2 whose high expression correlated with an immunosuppressive phenotype in an experimental cancer model. In this Proposal, we observed elevated Susd2 expression in T lymphocytes in experimental septic animals and patients with sepsis compared to non-septic controls. Genetic deletion of SUSD2 (Susd2−/−) resulted in a significantly improved animal survival and attenuated apoptosis of T lymphocytes in the cecal ligation and puncture (CLP)-induced polymicrobial sepsis model. Mechanistically, our preliminary studies discovered an inhibitory effect of SUSD2 on interleukin-2 receptor (IL-2R) signaling, a well- established pathway essential for T cell survival and effector functions. The goal of the proposal is to examine the causal effect of SUSD2 on cell death and dysfunction of T lymphocytes in microbial sepsis. We hypothesize that 1) elevated SUSD2 expression leads to diminished IL-2-dependent cell survival and effector functions in T lymphocytes, resulting in a sustained immunosuppressive state and worse disease outcome in sepsis; 2) enhanced activation of STAT5 (signal transducer and activator of transcription 5) and BATF (basic leucine zipper ATF-like transcription factor) signaling maintains cell survival and effector functions in Susd2−/− T cells post sepsis; 3) SUSD2 blockade reverses sepsis-induced cell death and dysfunction of T lymphocytes. Single-cell RNA sequencing analysis of circulatory immune cells will be performed to examine the inhibitory effect of SUSD2 on T cell response post sepsis at the single-cell level. We will test whether treatment with a neutralizing anti-SUSD2 antibody reverses dysfunctional T cells isolated from septic patients. Results of these studies will provide both experimental and clinical evidence to support a promoting function of SUSD2 on sepsis-induced immunosuppression, which can potentially lead to the development of new approach for sepsis treatment.