Single-cell transcriptomics reveals prominent expression of IL-14, IL-18 and IL-32 in psoriasis

Several different immune-activated cell types with particular cytokine patterns are identified such as keratinocytes, T helper cells, cytotoxic T cells, dendritic cells, macrophages, fibroblasts, and endothelial cells. The expression of well-known pathogenic factors such as TNF-α, IL-8 (CXCL8), L-23 and IL-17 is confirmed in different inflammatory cells. Furthermore, IL-14 (TXLNA; alpha-taxilin), IL-18 and IL-32 are identified as less well-known, and putative new pathogenic factors. Prominent expression of IL-18 is found in keratinocytes, macrophages and Langerhans cells, prominent IL-32 is found in T helper and regulatory T cells, IL-14 is mainly expressed by keratinocytes, fibroblasts and macrophages. Validation of gene expression is performed by ISH of human skin samples. In a murine model of psoriasis, IL-14 and IL-18 are significantly higher expressed in psoriasis-like skin lesions than in normal skin. In an analysis of serum samples from psoriasis patients, IL-18 shows higher expression in psoriasis patients compared to controls, and serum levels in psoriasis responded to treatment with IL-17 inhibitors. Human skin biopsies of lesional skin from patients suffering from plaque-type psoriasis were isolated using the Whole Skin Dissociation Kit (Miltenyi, Gladbach, Germany) and analyzed using 10x Genomics RNAseq.

本研究鉴定出多种具有特定细胞因子表达谱的免疫激活细胞类群，包括角质形成细胞（keratinocytes）、辅助T细胞（T helper cells）、细胞毒性T细胞（cytotoxic T cells）、树突状细胞（dendritic cells）、巨噬细胞（macrophages）、成纤维细胞（fibroblasts）以及内皮细胞（endothelial cells）。研究证实，多种炎症细胞中可检测到经典致病因子的表达，包括肿瘤坏死因子-α（TNF-α）、白细胞介素-8（IL-8, CXCL8）、L-23以及白细胞介素-17（IL-17）。此外，白细胞介素-14（IL-14, TXLNA；α-张力蛋白（alpha-taxilin））、白细胞介素-18（IL-18）与白细胞介素-32（IL-32）被鉴定为尚待深入研究的潜在新型致病因子。其中，IL-18在角质形成细胞、巨噬细胞与朗格汉斯细胞（Langerhans cells）中呈高表达；IL-32在辅助T细胞与调节性T细胞（regulatory T cells）中高表达；IL-14则主要由角质形成细胞、成纤维细胞与巨噬细胞表达。基因表达验证通过对人类皮肤样本实施原位杂交（ISH）完成。在银屑病小鼠模型中，IL-14与IL-18在银屑病样皮肤皮损内的表达水平显著高于正常皮肤。对银屑病患者血清样本的分析显示，银屑病患者体内IL-18的表达水平高于健康对照组，且患者血清IL-18水平可响应白细胞介素-17抑制剂（IL-17 inhibitors）的治疗。本研究使用全皮肤解离试剂盒（Whole Skin Dissociation Kit，美天旎，德国格拉德巴赫）分离斑块状银屑病（plaque-type psoriasis）患者皮损区的皮肤活检样本，并通过10x基因组学RNA测序（10x Genomics RNAseq）完成分析。