Targeting EndoS to auto-antibodies

识别自身抗原(即自身抗原)的自身抗体既是标志也是诊断 自身免疫性疾病的标志物。尽管自身免疫性疾病的机制复杂，涉及各种 体液和细胞免疫反应，有些完全依赖于自身抗体的存在。 一旦与同源自身抗原结合，自身反应性抗体就会诱导免疫效应机制。 通过补体激活和/或Fc受体结合。由此产生的自身抗体介导的效应器 机制导致慢性炎症和最终的组织损伤症状的自身免疫性疾病。 由免疫球蛋白抗体介导的效应器功能，无论它们识别自身或外来抗原，都是完全 依赖于Ig G Fc区Asn297上N-连接复合型多糖的存在，这使得 结合Fcγ受体的抗体(FcγRs)激活补体，赋予抗体免疫力 信令功能。内切糖苷酶(即从糖蛋白中去除多糖的酶)可以去除糖蛋白中的 糖链分子与Asn297相连，使免疫球蛋白抗体免疫惰性。在所有已知的事物中 内切糖苷酶，即S内切酶(Endoglycosidase，ENDOS)的独特之处在于它只去除与Asn297相连的糖链 免疫球蛋白抗体。由于其免疫球蛋白的特异性，内毒素对病理性自身抗体和/或 在自身免疫的动物模型中注射纯化的内毒素已被证明可以预防或缓解 许多自身免疫性疾病的症状。尽管Endos对免疫球蛋白抗体有精妙的特异性，但它没有 区分具有不同抗原特异性的抗体的能力。取而代之的是内源性脱糖基 所有的免疫球蛋白抗体，包括那些控制癌症的抗体，以及那些针对外来抗原的抗体 提供对感染的防御。工程内分泌，使其仅识别和脱糖基化 相对于所有的免疫球蛋白抗体，自身抗体对于制造真正特异的自身免疫药物是必不可少的。我们 假设我们可以将内皮细胞从一种极具潜力的自身免疫性疾病治疗方法转化为 通过构建与自身抗原(endos-AutoAg)相连的内源性融合蛋白来实现实际的临床应用 驱动病理性自身抗体的靶向去糖基化和灭活，同时将剩余的 免疫系统在功能上完好无损。我们将通过以下方式为这一概念提供原则性证明：(1)优化 Enos-AutoAg融合蛋白的体外特异性和活性特性；以及(2)研究Enos-AutoAg 自身免疫性大疱性大疱性表皮松解症小鼠模型体内融合蛋白的有效性和特异性 (EBA)。

Autoantibodies, which recognize autoantigens (i.e., self-antigens), serve as both hallmarks and diagnostic markers of autoimmune diseases. Although autoimmune disease mechanisms are complex and involve various humoral and cellular immune responses, some are exclusively dependent on the presence of autoantibodies. Upon binding to their cognate autoantigens, self-reactive antibodies induce effector mechanisms of immunity through complement activation and/or Fc receptor binding. The resulting autoantibody-mediated effector mechanisms lead to chronic inflammation and the eventual tissue damage symptomatic of autoimmune disease. The effector functions mediated by IgG antibodies, whether they recognize self or foreign antigens, are entirely dependent on the presence of an N-linked complex type glycan on Asn297 of the IgG Fc region, which enables the antibody to bind Fc γ receptors (FcγRs) and activate complement, endowing the antibody with immune signaling capabilities. Endoglycosidases (i.e., enzymes that remove glycans from glycoproteins) can remove the glycan molecule linked to Asn297 and render IgG antibodies immunologically inert. Of all the known endoglycosidases, Endoglycosidase S (EndoS) is unique in that it removes only the Asn297-linked glycan from IgG antibodies. Due to its IgG-specific properties, EndoS pretreatment of pathological autoantibodies and/or injection of purified EndoS in animal models of autoimmunity has been shown to protect against or alleviate the symptoms of many autoimmune diseases. Although EndoS is exquisitely specific to IgG antibodies, it has no capacity to discriminate between antibodies with different antigen specificities. Instead, EndoS deglycosylates all IgG antibodies, including those that keep cancer in check, as well as those that are specific to foreign antigens that provide defense from infections. Engineering EndoS such that it recognizes and deglycosylates only autoantibodies, as opposed to all IgG antibodies, is essential for making a truly specific autoimmunity drug. We hypothesize that we can translate EndoS from an autoimmune disease therapeutic of great potential to one of actual clinical utility by constructing fusion proteins of EndoS linked to autoantigens (EndoS-autoAg) that will drive the targeted deglycosylation and inactivation of pathological autoantibodies, while leaving the remainder of the immune system functionally intact. We will provide proof-of-principle for this concept by: (1) optimizing EndoS-autoAg fusion protein properties for specificity and activity in vitro; and (2) investigating EndoS-autoAg fusion protein efficacy and specificity in vivo using a mouse model of autoimmune epidermolysis bullosa acquisita (EBA).