Sixal Inc., Torrance, CA 90502;
Joint School of Nanoscience and Nanoengineering, University of North Carolina at Greensboro, Greensboro, NC 27401.
J Immunol. 2019 Dec 1;203(11):2777-2790. doi: 10.4049/jimmunol.1900112. Epub 2019 Oct 21.
Options for effective prevention and treatment of epidemic allergic diseases remain limited, and particularly so for IgE-mediated food allergies. We previously found that mouse low-affinity anti-human IgE mAbs with K in the 10-10 M range were capable of blocking allergic reactivity without triggering immediate allergic mediator release. In this study, we humanized three parent low affinity allergic response inhibitor (LARI) mouse anti-human IgE mAbs and characterized their biological and immunological features, refined the lead candidate for further clinical development, examined their safety profiles, determined their therapeutic efficiency, and explored the mechanism of action potentially responsible for their therapeutic effects. LARI profoundly blocked cat- and peanut-allergic IgE-mediated basophil activation, inhibited acute release of both prestored and newly synthesized mediator from human mast cells, suppressed peanut-specific IgE-mediated passive cutaneous anaphylaxis, and attenuated dansyl IgE-mediated systemic anaphylaxis in human FcεRIα transgenic mice. Safety testing demonstrated that concentrations of LARI well above therapeutic levels failed to trigger immediate release of prestored and newly synthesized allergic mediators, failed to promote robust cytokine/chemokine production from allergic effector cells, and did not elicit allergic reactivity in an animal model of cutaneous and systemic anaphylaxis. Mechanistic studies revealed that LARI downregulated surface FcεRI receptors and IgE via internalization of the IgE/FcεRI, promoted a partial mediator depletion pathway leading to slow release of small amount of mediators, and functioned as a partial antagonist to inhibit FcεRI signaling phosphorylation of Syk, Akt, Erk, and p38 MAPK. These studies demonstrate that targeting surface-bound IgE with LARI profoundly suppresses human allergic reactivity while displaying an excellent safety profile.
用于有效预防和治疗流行过敏性疾病的方法依然有限，特别是针对 IgE 介导的食物过敏。我们先前发现，亲和力在 10-10 M 范围内的鼠源低亲和力抗人 IgE mAbs 能够阻断过敏反应而不触发即刻过敏介质释放。在本研究中，我们对三种亲本低亲和力过敏反应抑制剂（LARI）鼠源抗人 IgE mAbs 进行了人源化改造，并对其生物学和免疫学特征进行了鉴定，对候选药物进行了优化，以进一步进行临床开发，检测了其安全性，确定了其治疗效果，并探讨了可能与其治疗效果相关的作用机制。LARI 能够显著阻断猫过敏原和花生过敏原介导的嗜碱性粒细胞激活，抑制人肥大细胞中预先储存的和新合成的介质的急性释放，抑制花生特异性 IgE 介导的被动皮肤过敏反应，以及减轻人 FcεRIα 转基因小鼠中dansyl IgE 介导的全身性过敏反应。安全性检测表明，远高于治疗水平的 LARI 浓度未能触发预先储存的和新合成的过敏介质的即刻释放，未能促进过敏效应细胞中大量细胞因子/趋化因子的产生，并且在皮肤和全身性过敏反应的动物模型中也没有引起过敏反应。机制研究表明，LARI 通过内化 IgE/FcεRI 下调表面 FcεRI 受体和 IgE，促进部分介质耗竭途径导致少量介质的缓慢释放，并作为部分拮抗剂抑制 FcεRI 信号传导中 Syk、Akt、Erk 和 p38 MAPK 的磷酸化。这些研究表明，用 LARI 靶向结合表面 IgE 能够显著抑制人类过敏反应，同时表现出极好的安全性。
