Red Cell Tranfusion: Modifier of Lung and Systemic Inflammatory Responses

描述（由申请人提供）：红细胞（RBC）输注仍然是重症监护室中非常常见的治疗方法，但在危重人群中与非预期后果相关。虽然肺是靶器官，但人肺损伤很少由任何单一事件引起，并且单独的RBC输注通常不足以诱导损伤，而是需要具有增加的“易感性”的宿主。我们对红细胞输注的持续关注 及其在调节炎症反应中的潜在作用使我们关注输注的氧化损伤的RBC（oxRBC）和带有表面磷脂酰丝氨酸（PS）的微粒在改变单核吞噬细胞活化状态中的作用以及保护免于持续性肺部炎症和损伤的宿主因子的作用。我们假设存在一种内源性对抗机制，即巨噬细胞（M？）吞噬标准RBC单位内所含的输注oxRBC或PS+微粒，通过释放抗炎信号IL-10抑制巨噬细胞活化。这种由凋亡小体的摄取引起的去激活信号是减少炎症和促进损伤的消退阶段所必需的。不适当的失活，通过有缺陷的IL-10信号转导后摄入凋亡小体可能会增加个体的红细胞输血的风险的易感性。我们已经确定了一种新的“易感”宿主的小鼠模型，并提出缺乏血小板反应蛋白-1（TSP 1）的小鼠，TSP 1是一种多功能粘附糖蛋白，参与吞噬细胞通过M？清除受体CD 36，在LPS诱导的肺部炎症后显示出缺陷的IL-10应答，并且除了缺陷的IL-10应答外，在输注oxRBC后肝脏中的10信号传导。基于我们的研究结果，我们提出了一个总体假设，即TSP 1作为细胞外的桥接分子，介导CD 36依赖性IL-10的产生，有助于M？失活，这是输血后肺部炎症适当解决所必需的。当中断时，宿主容易受到RBC输注的有害影响，并通过受损的M？失活表现出持续的炎症。利用人单核细胞衍生的M <$（HMDM）、鼠M <$、tsp 1-/-和cd 36-/-小鼠，我们将确定（1）在RBC微粒或oxRBC接合后，由M <$产生的TSP 1介导的IL-10是否需要CD 36;（2）输注储存的RBC可通过CD 36依赖性IL-12抑制LPS或细菌病原体诱导的tsp 1-/-小鼠肺部炎症的消退。10生产;（3）IL-10的重建加速tsp 1-/-小鼠肺部炎症的消退，并且可以利用RBC微粒的免疫调节特性来重编程具有完整TSP- 1/CD 36轴的单核吞噬细胞以使其消退。这些研究的完成将确定一个高度新颖的途径，其基础是红细胞输注的免疫调节方面及其对易感宿主肺部炎症和损伤的贡献。

DESCRIPTION (provided by applicant): Red blood cell (RBC) transfusion remains a very common therapeutic in intensive care units, but is associated with unintended consequences in the critically ill population. While the lungs are a target organ, human lung injury is seldom caused by any single event, and RBC transfusion alone is generally not sufficient to induce injury but requires a host with increased "susceptibility". Our ongoing interest in RBC transfusion and its potential role in modifying inflammatory responses have led us to focus upon the role of transfused oxidized, damaged RBC (oxRBC) and micro-particles bearing surface phosphatidylserine (PS) in altering the mononuclear phagocyte activation status and the role of host factors that protect from persistent lung inflammation and injury. We hypothesize that an endogenous countering mechanism exists whereby macrophage (M¿) engulfment of transfused oxRBC or PS+ micro-particles contained within standard RBC units results in suppression of macrophage activation through the release of the anti-inflammatory signal IL-10. This de-activating signal resulting from the ingestion of apoptotic bodies is required to curtail inflammation and promote the resolution phase of injury. Improper deactivation, through defective IL-10 signaling following ingestion of apoptotic bodies may increase the susceptibility of an individual to the risks of RBC transfusion. We have identified a novel murine model of the "susceptible" host and propose that mice deficient in thrombospondin-1 (TSP1), a multi-functional adhesive glycoprotein involved in phagocyte recognition of PS+ apoptotic bodies through the M¿ scavenging receptor CD36, show defective IL-10 responses following LPS- induced lung inflammation and fail to resolve injury in addition to defective IL-10 signaling in th liver following transfusion of oxRBC. Based upon our findings, we propose an overall hypothesis that TSP1 functions as an extracellular, bridging molecule that mediates CD36-dependent IL-10 production, contributing to M¿ deactivation necessary for proper resolution of lung inflammation following transfusion. When disrupted, the host is left vulnerable to the harmful effects of RBC transfusion and shows persistence of inflammation through impaired M¿ deactivation. Utilizing human monocyte derived M¿ (HMDM), murine M¿, tsp1-/-, and cd36-/- mice, we will determine whether (1) TSP1-mediated IL-10 production by M¿ following engagement of RBC micro-particles or oxRBC requires CD36; (2) transfusion of stored RBC impairs resolution of lung inflammation induced by either LPS or bacterial pathogen in tsp1-/- mice through CD36-dependent IL-10 production; and (3) reconstitution of IL-10 hastens resolution of lung inflammation in tsp1-/- mice and that immune-modulatory properties of RBC micro-particles can be harnessed to reprogram mononuclear phagocytes with intact TSP- 1/CD36 axis toward resolution. Completion of these studies will identify a highly novel pathway underlying the immune-modulatory aspect of RBC transfusion and its contribution to lung inflammation and injury in the susceptible host.