Microneedle-mediated Delivery of Immunomodulators Restores Immune Privilege in Hair Follicles and Reverses Immune-Mediated Alopecia

Disorders in the regulatory arm of the adaptive immune system result in autoimmune-mediated diseases. While systemic immunosuppression is the prevailing approach to manage them, it fails to achieve long-lasting remission due to concomitant suppression of the regulatory arm and carries the risk of heightened susceptibility to infections and malignancies. Alopecia Areata is a condition characterized by localized hair loss due to autoimmunity. The accessibility of the skin provides an opportunity for local rather than systemic intervention to avoid broad immunosuppression. We hypothesized that expansion of endogenous regulatory T cells (Tregs) at the site of antigen encounter can restore the immune balance and generate a long-lasting tolerogenic response. We therefore utilized a hydrogel microneedle (MN) patch for delivery of CCL22, a chemoattractant for Tregs, and IL-2, a Treg survival factor to amplify them. In an immune-mediated murine model of alopecia, we showed local bolstering of Treg numbers leading to sustained hair regrowth and attenuation of inflammatory pathways. In a humanized skin transplant mouse model, we confirmed expansion of Tregs within human skin without engendering peripheral immunosuppression. The MN patch offered high-loading capacity and shelf-life stability for prospective clinical translation. By harmonizing immune responses locally, we aspire to reshape the landscape of autoimmune skin disease management. We performed bulk RNA-sequencing of RNA isolated from AA-like skin lesions from three different experimental groups (untreated, treated with empty MNs, and treated with IL-2+CCL22 loaded MNs).

适应性免疫系统调控通路异常可引发自身免疫介导性疾病。当前临床主流治疗策略为全身性免疫抑制，但该方法会同时抑制免疫调控通路，无法实现持久缓解，且会增加感染与恶性肿瘤的易感风险。斑秃（Alopecia Areata）是一类由自身免疫介导的局限性脱发疾病。皮肤的体表可及性为局部而非全身性干预提供了契机，从而避免广泛的免疫抑制。我们提出假说：在抗原暴露位点扩增内源性调节性T细胞（Tregs），可恢复免疫平衡并诱导持久的免疫耐受应答。为此，我们采用水凝胶微针（MN）贴片递送CCL22——一种Tregs趋化因子——与IL-2——一种Treg存活因子——以扩增Treg群体。在斑秃免疫介导性小鼠模型中，我们证实局部扩增Treg可实现持久的毛发再生，并缓解炎症通路活化。在人源化皮肤移植小鼠模型中，我们验证了该策略可在人皮肤组织内扩增Treg，且不会引发外周免疫抑制。该微针贴片具备高负载能力与货架期稳定性，具备潜在临床转化价值。通过局部协调免疫应答，我们旨在重塑自身免疫性皮肤病的治疗格局。我们对来自3组不同实验组（未处理组、空白微针处理组、IL-2+CCL22负载微针处理组）的斑秃样皮肤病变组织中提取的RNA进行了批量RNA测序（bulk RNA-sequencing）。