慢性光化性皮炎（chronic actinic dermatitis, CAD）是一种好发于中老年男性的免疫介导的光敏性皮肤病。该病病程较长，病情易反复，严重影响患者生活质量。目前，该病的病因及发病机制尚不清楚，包括性别差异、共病患病率在内的临床特征尚未阐明，部分难治性患者对传统治疗药物的反应欠佳，但已有报道可经新型靶向药物（如度普利尤单抗，酪氨酸蛋白激酶即Janus kinase[JAK]抑制剂等）有效治疗，然而其治疗机制尚不明确。

细胞焦亡是一种炎症性程序性细胞死亡方式，其异常激活与多种免疫介导的炎症性疾病相关。了解细胞焦亡对皮肤免疫微环境的影响将有助于破解CAD的机制密码。

本研究首先通过临床回顾性研究澄清了CAD的性别差异、共病患病率等特征；之后通过转录组数据分析探寻细胞焦亡在UVB照射下皮肤免疫微环境中可能发挥的作用，为CAD的发病机制以及新型靶向药物治疗CAD的作用机制提供线索。

第一部分 慢性光化性皮炎109例临床回顾性分析

目的 探索CAD住院患者临床表现的性别差异、共病情况、吸烟情况、用药模式和经济负担。

方法 收集并分析2012年至2023年间本院109例CAD住院患者的临床资料。

结果 共纳入109例CAD住院患者，男女比例14.6:1。不同性别的CAD患者在发病年龄、病程、光试验结果、（光）斑贴实验结果方面无显著差异。近半数患者（46.8%）存在共病，包括高血压（35.8%）、糖尿病（13.8%）和脑血管病（5.5%）。有吸烟史的患者占比较高（48.6%）。49.5%的患者联合应用了至少3种系统性药物。整体患者的中位住院时长11天[四分位距（IQR）8-15天]，中位住院费用为6695.62元（IQR 5089.48-8473.71元）。

结论 CAD住院患者中，共病患病率及有吸烟史的患者比例均较高，建议加强CAD患者中的共病管理及戒烟干预。多药联合的治疗模式在CAD住院患者中常见，未来JAK抑制剂等新型靶向药物可能有助于优化治疗方案。

第二部分 GSDME敲低对中波紫外线照射下HaCaT细胞转录组的影响

目的 探索中波紫外线（UVB）照射下焦亡执行者Gasdermin E（GSDME）蛋白敲低对HaCaT细胞转录组的影响。

方法 使用GSDME敲减（GSDME knockdown, GSDME_kd）及阴性对照（negative control, NC）慢病毒转染HaCaT细胞系，构建稳转株。UVB照射剂量为25 mJ/cm²，照射后12h提取蛋白或RNA，分别用于Western blot（验证HaCaT细胞中GSDME的敲低效率）和转录组测序。设置4个实验组（NC, UVB, GSDME_kd, UVB_GSDME_kd），每组做4个生物学重复用于转录组测序，获得的基因表达矩阵使用R（v 4.3.1）处理。R包DESeq2（v 1.42.0）用于筛选差异表达基因，R包clusterProfiler（v 4.10.0）用于KEGG（Kyoto Encyclopedia of Genes and Genomes）和GO（Gene Ontology）富集分析。

结果 在UVB组与NC组、UVB_GSDME_kd组与UVB组两组比较中，同时上调的基因主要富集于抗病毒反应、抗原加工及递呈、促血管生成等通路；同时下调的基因主要富集于DNA修复、细胞黏附等通路。

结论 UVB照射下，GSDME可能抑制HaCaT细胞中的炎症相关通路。

第三部分 小鼠皮肤光损伤的单细胞转录组数据分析

目的 研究UVB对小鼠皮肤中焦亡相关蛋白表达的影响，寻找关键致病细胞和分子靶点，为探索CAD的发病机制和新型靶向药物对CAD的治疗机制提供线索。

方法 从GEO数据库GSE173385下载对照组和UVB照射组小鼠皮肤样本数据，使用R（v 4.3.1）进行数据分析。

结果 UVB照射组小鼠皮肤样本中的巨噬细胞中焦亡相关基因（Nlrp3、Casp1、Gsdmd、Il1b）的表达水平和比例均升高，M1中焦亡相关基因的表达高于M2，M1/M2型巨噬细胞的比例升高。M1及M2型巨噬细胞的信号通讯强度均显著增高。

结论 UVB引起的小鼠皮肤光损伤中，M1/M2型巨噬细胞比例增加，NLRP3/CASP1/GSDMD介导的细胞焦亡可能在其中发挥作用。尽管UVB照射后，M2型巨噬细胞的比例降低，但其信号强度显著增强。在进一步探究CAD的发病机制及JAK抑制剂对CAD的治疗机制时，M1/M2比例失衡可能是有价值的切入点。

Chronic actinic dermatitis (CAD) is an immunologically mediated photodermatosis that predominantly affects middle-aged and elderly men. The disease course is chronic and relapsing, considerably affecting patients’ quality of life. The etiology, pathogenesis, and several clinical characteristics of CAD, including sex differences and comorbidity rates, are not yet fully understood. Furthermore, some patients with refractory CAD have limited treatment options. Several targeted drugs, such as dupilumab and Janus kinase (JAK) inhibitors, have been reported to be effective for refractory CAD patients recently, but the therapeutic mechanism remains unclear.

Pyroptosis, a form of inflammatory programmed cell death, has been implicated in various immune-mediated inflammatory disorders. Understanding the impact of pyroptosis on the cutaneous immune microenvironment may unravel the pathogenesis of CAD.

In this study, a retrospective analysis was first conducted to elucidate several overlooked clinical characteristics of CAD, such as sex differences and comorbidity rates. Subsequently, we investigated the role that pyroptosis may play in the cutaneous immune microenvironment under UVB irradiation by transcriptomic analysis, with the aim of providing insights into the pathogenesis of CAD and the therapeutic mechanism of targeted drugs.

PartⅠ: Chronic Actinic Dermatitis: A Retrospective Analysis of 109 inpatients

Objective: To explore sex differences, comorbidity rates, smoking status, medication patterns, and economic burdens of CAD inpatients.

Methods: Clinical data of 109 CAD inpatients at our institution between 2012 and 2023 were collected and analyzed.

Results: A total of 109 CAD inpatients were included, with a male-to-female ratio of 14.6:1. No significant sex differences were found in age, disease duration, phototest results, photopatch results and patch results. Nearly half of the patients (46.8%) had comorbidities, including hypertension (35.8%), diabetes mellitus (13.8%), and cerebrovascular diseases (5.5%). The proportion of smoking history was relatively high (48.6%). 49.5% of the patients were treated with three-or-more-drug combination therapies. Among 109 patients analyzed, median [interquartile range (IQR)] hospital length-of-stay was 11 (8-15) days, median (IQR) hospitalization cost was 6695.62 (IQR 5089.48-8473.71) RMB.

Conclusion: Among CAD inpatients, the prevalence of comorbidities and the proportion of patients with a history of smoking are relatively high. It is recommended to enhance the management of comorbidities and implement smoking cessation interventions in these patients. Combination drug therapy is common among CAD inpatients. In the future, targeted drugs, such as JAK inhibitors, may help optimize treatment regimens.

Part II:

The Effect of GSDME Knockdown on the Transcriptome of UVB-Exposed HaCaT Keratinocytes

Objective: To explore the effect of knocking down Gasdermin E (GSDME) under ultraviolet B (UVB) irradiation on the transcriptome of HaCaT cells.

Methods: GSDME knockdown (GSDME_kd) and negative control (NC) lentiviruses were used to transfect the HaCaT cell line to generate stable transfectants. UVB radiation at a dose of 25 mJ/cm² was administered. Proteins and RNA were extracted 12 hours after UVB irradiation for Western blot analysis to verify the knockdown efficiency of GSDME and for transcriptomic sequencing respectively. Four experimental groups (NC, UVB, GSDME_kd, UVB_GSDME_kd) were set up. A total of 16 samples (4 experimental groups obtained from 4 replicate experiments) were processed for transcriptome analysis. The transcriptome profiling data was analyzed using R (v 4.3.1). The DESeq2 package (v 1.42.0) was used for conducting differential gene expression analysis, while the clusterProfiler package (v 4.10.0) was applied for KEGG (Kyoto Encyclopedia of Genes and Genomes) and GO (Gene Ontology) enrichment analysis.

Results: Genes upregulated in two comparisons (UVB v.s. NC and UVB_GSDME_kd v.s. UVB) were mainly enriched in pathways related to antiviral responses, antigen processing and presentation, and angiogenesis. Genes that were downregulated were primarily enriched in DNA repair and cell adhesion pathways.

Conclusion: GSDME may inhibit inflammatory pathways in UVB-exposed HaCaT cells.

Part III: Single-Cell Transcriptomic Analysis of UVB-induced Skin Photodamage in Mice

Objective: To investigate the impact of UVB-induced photodamage on the expression of pyroptosis-related proteins in mouse skin. The research will concentrate on identifying important pathogenic cells and molecular targets to gain a better understanding of the mechanisms behind CAD and the potential therapeutic effects of novel targeted drugs for CAD treatment.

Methods: The expression profile data of GSE173385 dataset were downloaded from the GEO database and then processed using R software (v 4.3.1).

Results: In UVB-irradiated mouse skin sample, there is an increase in the levels and ratios of genes associated with pyroptosis (Nlrp3, Casp1, Gsdmd, Il1b) in macrophages. The proportion of M1/M2 is higher, with M1 showing higher expression of pyroptosis-related genes compared to M2. The signaling strength of both M1 and M2 is notably heightened.

Conclusion: UVB-irradiated skin in mice shows an increase in the M1/M2 macrophage ratio, possibly attributing to pyroptosis via the NLRP3/CASP1/GSDMD pathway. Although the proportion of M2 macrophages decreases after UVB exposure, their signaling strength increases notably. When further investigating the pathogenesis of CAD and the therapeutic mechanisms of JAK inhibitors for CAD, the increased M1/M2 ratio may serve as a valuable point of investigation.