Targeting immune inhibitory molecule SUSD2 to reverse immunosuppression

项目摘要/摘要 败血症是许多重症监护病房最常见的死亡原因，对 美国的医疗保健系统。尽管重症监护技术和机械呼吸机支持方面取得了进展， 治疗败血症的药物选择有限，这反映了对宿主依赖性的认识不足。 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，由于严重的细胞死亡，免疫抑制状态持续时间延长 淋巴细胞功能障碍，是脓毒症导致死亡的关键决定因素。因此，恢复 通过阻断免疫抑制分子实现淋巴细胞的存活和功能(S)可能是一个很有前途的研究方向 治疗脓毒症的治疗方案。在这项建议中，我们的目标是研究一个 以前未被识别的免疫抑制分子SUSD2(苏司结构域包含2)在促进 脓毒症引起的免疫抑制。通过无偏见的基因图谱分析，我们之前的研究已经 发现一种细胞表面分子SUSD2，其高表达与一种免疫抑制相关 实验性癌症模型中的表型。在这项研究中，我们观察到T细胞Susd2表达升高。 脓毒症动物和脓毒症患者的淋巴细胞与非败血症对照的比较。遗传 SuSD2(Susd2−/−)基因缺失可显著提高动物存活率，减少T细胞的凋亡 盲肠结扎穿孔(CLP)诱导的多菌败血症模型中的淋巴细胞。从机械上讲，我们的 初步研究发现，SUSD2对白细胞介素2受体(IL-2R)信号转导有抑制作用，是一种很好的抗肿瘤药物。 为T细胞存活和效应器功能所必需的已建立的通路。该提案的目标是审查 SUSD2对微生物脓毒症细胞死亡和T淋巴细胞功能障碍的影响我们 假设1)SUSD2表达增加导致IL-2依赖的细胞存活和效应降低 T淋巴细胞的功能，导致持续的免疫抑制状态和更糟糕的疾病结局 脓毒症；2)STAT5(信号转导和转录激活因子5)和BATF(基础)的增强激活 亮氨酸拉链ATF样转录因子)信号转导维持Sud2−/−T细胞存活和效应功能 3)SUSD2阻断可逆转脓毒症诱导的细胞死亡和T淋巴细胞功能障碍。 将对循环免疫细胞进行单细胞RNA测序分析，以检查抑制作用 SUSD2在单细胞水平上对脓毒症后T细胞应答的影响我们将测试是否用一种 中和抗SUSD2抗体逆转败血症患者分离的功能障碍的T细胞。这些措施的结果 研究将提供实验和临床证据，以支持SUSD2的促进作用 脓毒症引起的免疫抑制，这可能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.