Swiss Institute of Allergy and Asthma Research (SIAF), University of Zurich, Davos, Switzerland; High-altitude Clinic of Davos, Davos-Wolfgang, Switzerland.
J Allergy Clin Immunol. 2010 Apr;125(4):858-865.e10. doi: 10.1016/j.jaci.2010.01.016. Epub 2010 Mar 15.
Keratinocyte (KC) apoptosis is an important mechanism of eczema and spongiosis in patients with atopic dermatitis (AD) and is mediated by IFN-gamma, which is secreted by T(H)1 cells. IL-32 is a proinflammatory cytokine that is involved in the inflammatory processes of rheumatoid arthritis, chronic obstructive pulmonary disease, and Crohn disease. Recently, it was shown that upregulation of IL-32 induces apoptosis.
The aim of the study was to investigate the expression and function of IL-32 in patients with AD.
The expression of IL-32 in KCs was analyzed by means of RT-PCR, ELISA, and flow cytometry. Transfections of small interfering RNA were performed in primary KCs, and apoptosis was analyzed by means of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling, annexin-V, and 7-amino actinomycin D stainings. Immunofluorescence stainings were used to detect IL-32 in skin biopsy specimens, and serum levels of IL-32 were analyzed by means of ELISA.
We report that IL-32 is expressed in human primary KCs on stimulation with IFN-gamma, TNF-alpha, and T(H)1 cells in contrast to T(H)2, regulatory T (Treg), or T(H)17 cells, which showed no effect. Transfection of primary KCs and artificial skin equivalents with small interfering RNA to IL-32, which resulted in a clear decrease in IL-32 expression, significantly reduced KC apoptosis. Immunofluorescence staining demonstrated that IL-32 was expressed in AD lesional skin, whereas it was present in neither skin biopsy specimens from healthy donors nor in lesional skin from patients with psoriasis. Serum levels of IL-32 from patients with AD correlated with disease severity, but increased serum levels of IL-32 were also detected in asthmatic patients.
The present study demonstrates KCs as a source of IL-32, which modulates KC apoptosis and contributes to the pathophysiology of AD.
角质形成细胞（KC）凋亡是特应性皮炎（AD）患者湿疹和海绵形成的重要机制，由 T(H)1 细胞分泌的 IFN-γ介导。IL-32 是一种促炎细胞因子，参与类风湿关节炎、慢性阻塞性肺疾病和克罗恩病的炎症过程。最近，研究表明 IL-32 的上调诱导细胞凋亡。
本研究旨在探讨 IL-32 在 AD 患者中的表达和功能。
通过 RT-PCR、ELISA 和流式细胞术分析 KC 中 IL-32 的表达。在原代 KC 中进行小干扰 RNA 转染，通过末端脱氧核苷酸转移酶介导的 dUTP 缺口末端标记、膜联蛋白-V 和 7-氨基放线菌素 D 染色分析细胞凋亡。免疫荧光染色用于检测皮肤活检标本中的 IL-32，通过 ELISA 分析血清中 IL-32 的水平。
我们报告说，与 T(H)2、调节性 T (Treg)或 T(H)17 细胞相反，IFN-γ、TNF-α 和 T(H)1 细胞刺激人原代 KC 表达 IL-32。转染原代 KC 和人工皮肤等效物的小干扰 RNA 导致 IL-32 表达明显减少，显著减少 KC 凋亡。免疫荧光染色表明，IL-32 在 AD 病变皮肤中表达，而在健康供体的皮肤活检标本中不存在，也不存在于银屑病病变皮肤中。AD 患者的血清 IL-32 水平与疾病严重程度相关，但也在哮喘患者中检测到血清 IL-32 水平升高。
本研究表明 KC 是 IL-32 的来源，调节 KC 凋亡，有助于 AD 的病理生理学。
