Transfusion-driven hyperhemolysis in sickle cell disease

红细胞(RBC)输注仍然是治疗镰状细胞病的基石治疗方法 (SCD)。然而，患者可能会经历延迟溶血性输血反应(DHTR)，在该患者中 人群有不可预测的进展，从轻微到危及生命的严重反应，在两者输血的地方 患者自身的红细胞在溶血危象时与网织红细胞减少症一起被破坏，加剧 贫血。导致严重DHTR进展的机制还知之甚少，构成了挑战 预防和有效治疗这种输血并发症，这种并发症是不成比例的 在SCD患者中。我们最近发现，急性溶血可诱导先天性I型干扰素(IFN-I)的产生 免疫细胞，导致单核细胞来源的巨噬细胞(MOMΦ)在 SCD，并加剧抗体(Ab)包被的输血红细胞的破坏。我们的初步数据显示 仅AB致敏的RBC破坏也会导致干扰素-I的产生，但如果破坏的话会产生更高的水平 发生在溶血条件下，有趣的是，这也会导致镰刀状红细胞的旁观者溶血， 模拟SCD的溶血亢进反应。我们还发现，溶血诱导的干扰素-I会损害红细胞的生成。 同时抑制EPO/EPOR信号转导。基于这些数据，我们假设Fc受体的交联性 在溶血的背景下，SCD导致干扰素-I水平增加，导致干扰素-I信号增强 吞噬细胞和红系细胞，导致红细胞破坏增加，进一步抑制红细胞 分别生产，导致严重的DHTR。在目标1中，我们将重点识别旁观者的机制 溶血通过检测关键的吞噬激活分子的作用，特别是与SCD相关的Eat Me 包括血栓反应蛋白(TSP-1)及其配体在内的信号在高溶血模型中上调。我们 将比较抗体介导的红细胞吞噬作用和抗体非依赖性红细胞吞噬在触发中的作用 旁观者溶血和询问抑制FCR/SYK磷酸化和血红素的相对贡献 自体镰状红细胞破坏中的激活途径。我们还将研究干扰素-I作为一种 通过检测干扰素-I/STAT1在SCD患者样本中单核细胞的变化来判断DHTR严重程度的生物标志物 比较重度和轻度DHTR患者和恢复到稳定状态后的患者。对于目标2，我们将 利用原代红细胞培养系统确定干扰素-I抑制红细胞生成的机制 靶向缺失人红细胞细胞系和小鼠模型中的关键下游通路。我们还将 检测抑制干扰素-I产生/干扰素-I信号通路或/和增加EPO/EPOR信号通路的疗效 逆转SCD小鼠受损骨髓红细胞生成及体外和培养人红细胞生成的实验研究 用SCD患者血浆治疗。我们相信，我们建议的研究是为了审查进展到 DHTR的严重性可能有助于对风险进行分层，并有助于开发新的靶向疗法来逆转或预防 溶血过多是SCD救命治疗的毁灭性并发症。

Red blood cell (RBC) transfusions remain a cornerstone treatment in the management of sickle cell disease (SCD). However, patients may experience delayed hemolytic transfusion reaction (DHTR) which in this patient population has an unpredictable progression from mild to life-threatening severe reactions where both transfused and patient’s own RBCs are destroyed along with reticulocytopenia at the time of hemolytic crisis, exacerbating the anemia. The mechanisms underlying severe DHTR progression are poorly understood, posing challenges for prevention and effective treatments for this transfusion complication which is disproportionately encountered in patients with SCD. We recently found that acute hemolysis induces type I interferon (IFN-I) production in innate immune cells, leading to increased differentiation and activation of monocyte-derived macrophages (MoMΦ) in SCD, and exacerbating destruction of antibody (Ab)-coated transfused RBCs. Our preliminary data showed that Ab-sensitized RBC destruction alone also led to IFN-I production but with even higher levels if destruction occurred under hemolytic conditions, which interestingly also induced bystander hemolysis of sickle RBCs, mimicking hyperhemolysis reaction in SCD. We also found that hemolysis-induced IFN-I impairs erythropoiesis along with inhibition of EPO/EPOR signaling. Based on these data, we hypothesize that Fc receptor crosslinking in a hemolytic backdrop of SCD leads to increase in IFN-I levels, causing heightened IFN-I signaling in phagocytes and erythroid cells which trigger increased RBC destruction and further suppression of RBC production, respectively, leading to severe DHTR. In aim 1, we will focus on identifying mechanisms of bystander hemolysis by examining the role of key phagocytosis activation molecules, specifically SCD associated eat me signals including thrombospondin (TSP-1) and its ligands which are upregulated in hyperhemolytic models. We will compare the role of Ab-mediated erythrophagocytosis versus Ab-independent RBC engulfment in triggering bystander hemolysis and interrogate the relative contribution of inhibiting FcR/SYK phosphorylation and heme activation pathways in autologous sickle RBC destruction. We will also examine the potential of IFN-I as a biomarker of DHTR severity by examining IFN-I/STAT1 driven changes in monocytes in SCD patient samples, comparing patients experiencing severe and mild DHTR and after recovery to steady state. For aim 2, we will define the mechanisms by which IFN-I suppresses erythropoiesis using primary erythroid cell culture system and targeted deletion of key downstream pathways in human erythroblast cell lines and mouse models. We will also test the therapeutic effects of inhibiting IFN-I production/IFN-I signaling or/and increasing EPO/EPOR signaling on reversing impaired BM erythropoiesis in SCD mice and on human erythropoiesis in vitro and in cultures treated with SCD patient plasma. We believe that our proposed studies to examine the basis for progression to DHTR severity may help stratify risk and aid in development of novel targeted therapies to reverse or prevent hyperhemolysis, a devastating complication of an otherwise life-saving treatment in SCD.