Type 2 cytokines pleiotropically modulate sensory nerve architecture and neuroimmune interactions to mediate itch [Human DRG]

Background: Anti-type 2 cytokine therapies represent promising interventions for chronic itch; however, their precise mechanisms in restoring nerve architecture and mitigating inflammation and pruritus remain incompletely understood. This study aimed to elucidate the mechanistic roles of IL-4, IL-13, and IL-31 in the pathophysiology of itch associated with type 2 inflammatory skin diseases. Methods: The effect of IL-4, IL-13, and/or IL-31 on neurite outgrowth and/or transcriptomic changes were analyzed in human and mouse dorsal root ganglion (DRG) neuronal cultures. Mouse ear pinnae were processed for histologic, transcriptomic, and proteomic analyses 4 days after intradermal injection of IL-4, IL-13, and/or IL-31. To evaluate functional correlations with neuronal responses, mice were subcutaneously challenged with IL-4, IL-13, and/or IL-31, and scratching behavior was monitored. Association between IL-4/IL-13–IL-4Rα axis and severity of atopic dermatitis (AD) was evaluated through correlative analyses of human DRG transcriptomic changes and AD transcriptomic datasets (GSE130588 and BioMap consortium). Results: IL-4 and IL-13 promote mouse and human DRG sensory neuron growth, with effects similar to or greater than IL-31. In mice, intradermal IL-4, IL-13, and IL-31 increased epidermal nerve growth; however, only IL-4 and IL-13 induced hyperplasia and immune cell recruitment. Multi-omic analyses revealed that IL-4 and IL-13 have a broader impact on neuroimmune interactions than IL-31. In a murine DRG neuron-eosinophil co-culture, IL-4Rα blockade reduced neurite growth. IL-13 and IL-31 elicited acute scratching, demonstrating their roles as direct pruritogens; IL-4 synergistically enhanced IL-13-induced itch, resulting in greater pruritic responses than IL-31. Additionally, a set of itch-associated genes upregulated by IL-4 and IL-13 and downregulated by dupilumab-mediated IL-4Rα blockade in human DRG neuronal cultures showed positive correlation with AD severity. Conclusions: These findings establish the IL-4/IL-13–IL-4Rα axis as a key regulator of inflammatory skin nerve innervation, neuroimmune interactions, barrier integrity, and itch response, highlighting its mechanistic role in modulating sensory neuronal function and shaping the inflammatory microenvironment that drives itch pathophysiology. RNA-seq profiling of Human DRG neuronal culture treated with PBS, IL-4+IL-13+IgG4k-Isotype, or IL-4+IL-13+dupilumab (n=3 per group)

研究背景：抗2型细胞因子疗法是治疗慢性瘙痒的潜在有效手段，但其在修复神经结构、减轻炎症与瘙痒方面的具体机制仍未完全阐明。本研究旨在阐明IL-4、IL-13及IL-31在2型炎症性皮肤病相关瘙痒病理生理学中的机制性作用。
研究方法：在人源与小鼠背根神经节（dorsal root ganglion, DRG）神经元培养中，分析IL-4、IL-13及/或IL-31对神经突生长及/或转录组变化的影响。对皮内注射IL-4、IL-13及/或IL-31 4天后的小鼠耳郭进行组织学、转录组学与蛋白质组学分析。为评估与神经元反应的功能相关性，对小鼠皮下注射IL-4、IL-13及/或IL-31并监测其搔抓行为。通过分析人源DRG转录组变化与特应性皮炎（atopic dermatitis, AD）转录组数据集（GSE130588与BioMap联盟数据集）的相关性，评估IL-4/IL-13–IL-4Rα轴与AD严重程度的关联。
研究结果：IL-4与IL-13可促进小鼠及人源DRG感觉神经元生长，其效果与IL-31相当甚至更强。在小鼠体内，皮内注射IL-4、IL-13及IL-31均可增加表皮神经生长，但仅IL-4与IL-13可诱导表皮增生与免疫细胞募集。多组学分析显示，相较于IL-31，IL-4与IL-13对神经免疫互作的影响更为广泛。在小鼠DRG神经元-嗜酸性粒细胞共培养体系中，阻断IL-4Rα可抑制神经突生长。IL-13与IL-31可诱发急性搔抓行为，证实二者为直接致痒原；IL-4可协同增强IL-13诱导的瘙痒反应，其致痒效果强于IL-31。此外，在人源DRG神经元培养中，IL-4与IL-13上调、度普利尤单抗介导的IL-4Rα阻断下调的一组瘙痒相关基因，与AD严重程度呈正相关。
研究结论：本研究证实IL-4/IL-13–IL-4Rα轴是炎症性皮肤神经支配、神经免疫互作、屏障完整性与瘙痒反应的关键调控因子，阐明了其在调节感觉神经元功能、塑造驱动瘙痒病理生理学的炎症微环境中的机制性作用。对经PBS、IL-4+IL-13+IgG4k同型对照或IL-4+IL-13+度普利尤单抗处理的人源DRG神经元培养物进行RNA测序转录组分析（每组n=3）