Naturally Occurring IgM Anti-Leucocyte Autoantibodies Protect Against Renal IRI

描述(由申请人提供)：这个多PI方案的总体目标是研究自然产生的IgM抗白细胞自身抗体在抑制缺血再灌注损伤(IRI)后发生的炎症过程中的作用。我们和其他人观察到，在肾或心脏移植后，IgM-ALA水平高的患者中，有一部分(30%)患者的排斥反应很少或没有。我们发现，IgM-ALA以高度特异的方式与白细胞受体结合，在体温下，尽管存在补体，但不会导致白细胞死亡。此外，我们还发现，IgM-ALA(I)可与CD_4和CD_3受体结合(但不能与HLA、IL-2R结合)，可抑制T细胞的活化、增殖和某些致炎细胞因子(TNF-1、IL-2)的产生，但不能抑制其他细胞因子(IL-6和IL-8)的产生；基于这些发现，我们质疑IgM-ALA是否下调了伴随肾IRI的炎症。缺血损伤后释放的糖脂由常驻树突状细胞(DC)在细胞因子存在的情况下处理并递送给NKT细胞，NKT细胞被激活并产生细胞因子(尤其是干扰素？)通过吸引和激活体循环中的白细胞来放大炎症过程。我们推测，IgM-ALA可能通过与参与细胞活化的受体结合，抑制白细胞趋化而下调炎症过程。为了验证我们的假设，我们使用了缺乏IgM的小鼠(IgMko小鼠)，并表明这些小鼠比WT-B6小鼠患上了严重的肾脏IRI。我们提出了三个目标：目标1将检验IgM-ALA在肾脏IRI中具有保护作用的假设。为了验证这一假设，我们计划对IgMko小鼠进行肾脏IRI，并用纯化的B1细胞(WT小鼠的IgM-Ala来源)和从WT小鼠获得的纯化的血浆IgM拯救它们。我们还将通过给WT小鼠注射IgM来测试IgM的治疗价值。目的2将验证一种假设，即在IgM缺陷的小鼠中，导致更严重的肾脏IRI的炎症过程的增强是由于缺乏IgM介导的对树突状细胞(DC)/自然杀伤T(NKT)细胞途径以及下游IL17途径中细胞的抑制，而不是由于IgM缺陷小鼠未被掩盖的其他机制所致。我们将通过阻断抗体和白喉毒素耗尽树突状细胞来阻断IgMko小鼠的这一途径。目的3验证IgM-Ala通过与细胞受体结合，减弱DC和NKT细胞的功能以及白细胞的趋化和功能，从而抑制炎症过程的假说。提出的这些研究的意义在于，正是在人类身上的观察支持了这样的假设，即自然产生的IgM-ALA可能会消除与急性肾损伤(AKI)相关的炎症。我们的初步数据提供了强有力的证据，证明这些自然产生的IgM-ALA确实在AKI中具有保护作用，因此这些研究将确定自然产生的IgM-ALA对组织保护的机制。 公共卫生相关性： 急性肾损伤仍然是一个公共卫生问题。发病率继续上升，发病率和死亡率高得令人无法接受。这些研究代表了治疗AKI的一种新的治疗方法，也是一种可以针对AKI和其他先天免疫障碍的人类临床试验快速推进的方法。

DESCRIPTION (provided by applicant): The overall goal of this multi-PI proposal is to investigate the role of naturally occurring IgM anti-leucocyte autoantibodies in inhibiting inflammatory processes that occur after ischemia-reperfusion injury (IRI). We and others observed that a subset (30%) of patients with high levels of IgM-ALA had minimal or no rejections after a kidney or heart transplant. We showed that IgM-ALA bind to leucocyte receptors in a highly specific manner and at body temperature does not cause leucocyte cell death despite presence of complement. Furthermore, we showed that IgM-ALA (i) bind to CD4 and CD3 receptors (but not HLA, IL-2R) and inhibit T cell activation, proliferation and production of certain proinflammatory cytokines (TNF-1, IL-2) but not others (IL-6 and IL-8), (ii) bind to chemokine receptors and inhibit chemotaxis. Based on these findings we questioned whether IgM- ALA downregulate inflammation that accompanies renal IRI. Glycolipids released after ischemic injury are processed and presented by resident dendritic cells (DC), in presence of cytokines, to NKT cells, which get activated and produce cytokines (in particular IFN?) to amplify the inflammatory process by attracting and activating leucocytes from the systemic circulation. We posit that IgM-ALA could downregulate the inflammatory process by binding to receptors involved in cell activation and inhibiting leucocyte chemotaxis. To test our hypothesis, we used mice deficient in IgM (IgMko mice) and showed that these mice develop severe renal IRI relative to their WT-B6 counterparts. We propose 3 aims: Aim 1 will test the hypothesis IgM-ALA is protective in renal IRI. To test this hypothesis we plan to perform renal IRI in IgMko mice and rescue them with purified B1 cells (source of IgM-ALA in WT mice) and also with purified plasma IgM, obtained from WT mice. We will also test the therapeutic value of IgM by administering IgM to WT mice. Aim 2 will test the hypothesis that the enhanced inflammatory process causing more severe renal IRI in mice deficient in IgM results from lack of IgM mediated inhibition of cells in the dendritic cell (DC)/natural killer T (NKT) cell pathway as well as the downstream IL17 pathway and not from some other mechanism that is unmasked in mice deficient in IgM. We will interrupt this pathway in IgMko mice with blocking antibodies and depleting DCs with diptheria toxin. Aim 3 will test the hypothesis that IgM-ALA inhibits the inflammatory process by binding to cell receptors and attenuating the function of DC and NKT cells and chemotaxis and function of leucocytes. The significance of the studies proposed is that it was observations in humans that undergird the hypothesis that naturally occurring IgM-ALA might abrogate inflammation associated with acute kidney injury (AKI). Our preliminary data provide strong evidence that indeed these naturally occurring IgM-ALA are protective in AKI and thus these studies will define mechanisms of tissue protection by naturally occurring IgM-ALA. PUBLIC HEALTH RELEVANCE: Acute kidney injury continues to remain a public health concern. The incidence continues to rise and the morbidity and mortality is unacceptably high. These studies represent a novel therapeutic approach for the treatment of AKI and an approach that could be targeted for rapid advancement in human clinical trials in AKI and other disorders of innate immunity.