Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, Special Administrative Region, People's Republic of China.
PLoS One. 2012;7(1):e29815. doi: 10.1371/journal.pone.0029815. Epub 2012 Jan 17.
IL-31 is a pruritogenic cytokine, and IL-33 is an alarmin for damaging inflammation. They together relate to the pathogenesis of atopic dermatitis (AD). Eosinophil infiltration into the inner dermal compartment is a predominant pathological feature of AD. We herein investigated the in vitro inflammatory effects of IL-31 and IL-33 on the activation of human eosinophils and dermal fibroblasts.
METHODOLOGY/PRINCIPAL FINDINGS: Receptors, adhesion molecules and signaling molecules were assessed by Western blot or flow cytometry. Chemokines and cytokine were quantitated by multiplex assay. Functional IL-31 receptor component IL-31RA, OSMR-β and IL-33 receptor component ST2 were constitutively expressed on the surface of eosinophils. Co-culture of eosinophils and fibroblasts significantly induced pro-inflammatory cytokine IL-6 and AD-related chemokines CXCL1, CXCL10, CCL2 and CCL5. Such inductions were further enhanced with IL-31 and IL-33 stimulation. IL-31 and IL-33 could significantly provoke the release of CXCL8 from eosinophils and fibroblasts, respectively, which was further enhanced upon co-culture. In co-culture, eosinophils and fibroblasts were the main source for the release of CCL5, and IL-6, CXCL1, CXCL8, CXCL10 and CCL2, respectively. Direct interaction between eosinophils and fibroblasts was required for CXCL1, CXCL10, CXCL8 and CCL5 release. Cell surface expression of intercellular adhesion molecule-1 on eosinophils and fibroblasts was up-regulated in co-culture upon IL-31 and IL-33 stimulation. The interaction between eosinophils and fibroblasts under IL-31 and IL-33 stimulation differentially activated extracellular signal-regulated kinase, c-Jun N-terminal kinase, p38 mitogen-activated protein kinase, nuclear factor-κB and phosphatidylinositol 3-kinase-Akt pathways. Using specific signaling molecule inhibitors, the differential induction of IL-31 and IL-33-mediated release of cytokines and chemokines such as IL-6 and CXCL8 from co-culture should be related to their distinct activation profile of intracellular signaling pathways.
CONCLUSIONS/SIGNIFICANCE: The above findings suggest a crucial immunopathological role of IL-31 and IL-33 in AD through the activation of eosinophils-fibroblasts interaction via differential intracellular signaling mechanisms.
白细胞介素 31（IL-31）是一种致痒细胞因子，白细胞介素 33（IL-33）是一种损伤性炎症的警报素。它们都与特应性皮炎（AD）的发病机制有关。嗜酸性粒细胞浸润真皮内层是 AD 的主要病理特征。本研究旨在探讨 IL-31 和 IL-33 对人嗜酸性粒细胞和真皮成纤维细胞激活的体外炎症作用。
方法/主要发现：通过 Western blot 或流式细胞术评估受体、黏附分子和信号分子；通过多重检测定量细胞因子和趋化因子。嗜酸性粒细胞表面持续表达功能性 IL-31 受体成分 IL-31RA、OSMR-β 和 IL-33 受体成分 ST2。嗜酸性粒细胞和成纤维细胞共培养显著诱导促炎细胞因子 IL-6 和 AD 相关趋化因子 CXCL1、CXCL10、CCL2 和 CCL5。IL-31 和 IL-33 刺激进一步增强了这些诱导作用。IL-31 和 IL-33 可显著刺激嗜酸性粒细胞和成纤维细胞分别释放 CXCL8，共培养后进一步增强。在共培养中，嗜酸性粒细胞和成纤维细胞分别是 CCL5、IL-6、CXCL1、CXCL8、CXCL10 和 CCL2 释放的主要来源。嗜酸性粒细胞和成纤维细胞之间的直接相互作用是 CXCL1、CXCL10、CXCL8 和 CCL5 释放所必需的。IL-31 和 IL-33 刺激下共培养中，嗜酸性粒细胞和成纤维细胞表面细胞间黏附分子-1 的表达上调。IL-31 和 IL-33 刺激下，嗜酸性粒细胞和成纤维细胞之间的相互作用通过不同的细胞外信号调节激酶、c-Jun N 端激酶、p38 丝裂原活化蛋白激酶、核因子-κB 和磷脂酰肌醇 3-激酶-Akt 途径激活。使用特定的信号分子抑制剂，从共培养物中差异诱导的细胞因子和趋化因子（如 IL-6 和 CXCL8）的 IL-31 和 IL-33 介导的释放与它们不同的细胞内信号转导途径的激活谱有关。
结论/意义：上述发现表明，通过嗜酸性粒细胞-成纤维细胞相互作用的差异细胞内信号机制，IL-31 和 IL-33 在 AD 中通过激活发挥关键的免疫病理作用。
