Naturally Occurring IgM Anti-Leucocyte Autoantibodies Protect Against Renal IRI

描述（由申请人提供）：这个多pi提案的总体目标是研究天然存在的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，一部分（30%）IgM-ALA水平高的患者在肾或心脏移植后很少或没有排斥反应。我们发现IgM-ALA以高度特异性的方式与白细胞受体结合，并且在体温下，尽管存在补体，但不会导致白细胞死亡。此外，我们发现IgM-ALA (i)结合CD4和CD3受体（但不包括HLA和IL-2R）并抑制T细胞活化、增殖和某些促炎细胞因子（TNF-1、IL-2）的产生，但不包括其他因子（IL-6和IL-8）， （ii）结合趋化因子受体并抑制趋化性。基于这些发现，我们质疑IgM- ALA是否下调伴随肾IRI的炎症。缺血损伤后释放的糖脂被驻留树突状细胞（DC）处理并在细胞因子的存在下呈递给NKT细胞，NKT细胞被激活并产生细胞因子（特别是IFN?），通过吸引和激活来自体循环的白细胞来放大炎症过程。我们假设IgM-ALA可以通过与参与细胞活化和抑制白细胞趋化的受体结合来下调炎症过程。为了验证我们的假设，我们使用了缺乏IgM的小鼠（IgMko小鼠），结果表明这些小鼠相对于WT-B6小鼠发生了严重的肾IRI。我们提出了三个目的：目的1将验证IgM-ALA在肾脏IRI中具有保护作用的假设。为了验证这一假设，我们计划在IgMko小鼠中进行肾脏IRI，并用纯化的B1细胞（WT小鼠中IgM- ala的来源）和从WT小鼠中获得的纯化血浆IgM来拯救它们。我们还将通过给WT小鼠注射IgM来测试IgM的治疗价值。Aim 2将验证以下假设：在缺乏IgM的小鼠中，炎症过程的增强导致更严重的肾IRI是由于缺乏IgM介导的树突状细胞(DC)/自然杀伤T （NKT）细胞通路以及下游il - 17通路中细胞的抑制，而不是由于在缺乏IgM的小鼠中发现的其他机制。我们将用阻断抗体阻断IgMko小鼠的这一途径，并用白喉毒素消耗dc。Aim 3将验证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性和功能来抑制炎症过程的假设。所提出的研究的意义在于，对人类的观察支持了自然发生的IgM-ALA可能消除与急性肾损伤（AKI）相关的炎症的假设。我们的初步数据提供了强有力的证据，证明这些天然存在的IgM-ALA确实对AKI具有保护作用，因此这些研究将确定天然存在的IgM-ALA对组织的保护机制。

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.