Data Sheet 2_LL37-driven mast cell degranulation and inflammation in rosacea via TLR2/JAK2/STAT3 axis.zip

IntroductionRosacea is a chronic inflammatory facial dermatosis with incompletely elucidated pathogenesis. LL37 is a key molecular mediator in rosacea development, and mast cells represent pivotal immune players in this process. However, the precise mechanism underlying LL37-induced mast cell degranulation remains undefined.
MethodsA LL37-induced rosacea-like dermatitis mouse model was established with or without ruxolitinib treatment. Hematoxylin-eosin and toluidine blue staining were used to evaluate the pathological changes. Mice skin lesions were collected for transcriptome sequencing, Western blot and immunofluorescence. In vitro, the interaction between LL37 and TLR2 on the mast cell membrane surface was detected by co-immunoprecipitation and fluorescence staining. The activation of the TLR2/MyD88/JAK2/STAT3 signaling pathway was investigated using lentivirus-mediated TLR2 knockdown, MyD88 overexpression, combined with JAK2 inhibitor (ruxolitinib). Ten patients underwent VISIA skin analysis system and severity assessment following topical ruxolitinib treatment.
ResultsLL37 induces activation of the TLR2/JAK2 pathway in mast cells of rosacea-like mice. Ruxolitinib ameliorated cutaneous erythema and reduced mast cell infiltration and degranulation. In vitro experiments demonstrated that LL37 directly binds to TLR2, triggering TLR2/MyD88 pathway activation and subsequent mast cell degranulation. Mechanistically, MyD88 directly interacts with JAK2 to modulate the JAK2/STAT3 signaling axis, which governs mast cell degranulation. Topical application of ruxolitinib exhibited clinical efficacy in rosacea patients.
ConclusionThese findings collectively demonstrate that LL37 drives mast cell activation and degranulation in rosacea pathogenesis via TLR2/JAK2/STAT3 pathway activation, while ruxolitinib effectively suppresses this signaling axis. This study provides novel mechanistic insights and therapeutic strategies for rosacea management.

## 引言
玫瑰痤疮（Rosacea）是一种发病机制尚未完全阐明的慢性炎症性面部皮肤病。LL37是玫瑰痤疮发病过程中的关键分子介质，肥大细胞则是该进程中的关键免疫参与者。然而，LL37诱导肥大细胞脱颗粒的确切机制仍未明确。
## 方法
本研究构建了LL37诱导的玫瑰痤疮样皮炎小鼠模型，并设置是否予以芦可替尼（ruxolitinib）干预的分组。采用苏木精-伊红（hematoxylin-eosin）染色与甲苯胺蓝染色（toluidine blue staining）评估皮肤病理变化；收集小鼠皮损组织进行转录组测序（transcriptome sequencing）、蛋白质免疫印迹（Western blot）及免疫荧光（immunofluorescence）检测。体外实验中，通过免疫共沉淀（co-immunoprecipitation）与荧光染色检测LL37与肥大细胞膜表面TLR2的相互作用；借助慢病毒介导的TLR2基因敲低（TLR2 knockdown）、MyD88过表达（MyD88 overexpression）联合JAK2抑制剂（JAK2 inhibitor）芦可替尼，探究TLR2/MyD88/JAK2/STAT3信号通路的激活情况。此外，招募10例玫瑰痤疮患者，予以外用芦可替尼治疗后，采用VISIA皮肤分析系统（VISIA skin analysis system）进行皮肤检测与病情严重程度评估。
## 结果
LL37可激活玫瑰痤疮样模型小鼠肥大细胞中的TLR2/JAK2通路。芦可替尼可改善皮肤红斑症状，减少肥大细胞浸润与脱颗粒现象。体外实验证实，LL37可直接结合TLR2，触发TLR2/MyD88通路激活，进而诱导肥大细胞脱颗粒。机制层面研究发现，MyD88可直接与JAK2相互作用，调控JAK2/STAT3信号轴，该轴可调控肥大细胞脱颗粒过程。临床实验显示，外用芦可替尼对玫瑰痤疮患者具有明确临床疗效。
## 结论
本研究结果表明，LL37通过激活TLR2/JAK2/STAT3通路，介导玫瑰痤疮发病过程中肥大细胞的活化与脱颗粒，而芦可替尼可有效抑制该信号轴的活性。本研究为玫瑰痤疮的临床管理提供了全新的机制见解与治疗策略。