Chen Weiguo, Tabata Yasuhiro, Gibson Aaron M, Daines Michael O, Warrier Manoj R, Wills-Karp Marsha, Hershey Gurjit K Khurana
Division of Allergy and Immunology, Institute for Personalized and Predictive Medicine, Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH 45229, USA.
J Allergy Clin Immunol. 2008 Sep;122(3):625-32. doi: 10.1016/j.jaci.2008.06.022. Epub 2008 Aug 9.
IL-13 receptor alpha2 (IL-13R alpha 2) is a high-affinity receptor for IL-13, a central mediator of allergic asthma. It acts predominantly as a decoy receptor but can also contribute to IL-13 responses under certain conditions. IL-13R alpha 2 exists in soluble and membrane forms, which can both bind IL-13 and modulate its activity. Yet the proteolytic processes that contribute to the generation of soluble IL-13R alpha 2 are largely unknown.
We sought to investigate the role of matrix metalloproteinases (MMPs) in the generation of soluble IL-13R alpha 2.
Acellular cleavage assays by MMPs were performed by using glutathione-S-transferase fusion proteins of murine or human IL-13R alpha 2. IL-13R alpha 2 stable-transfected cells were used for analysis of surface expression and release of soluble IL-13R alpha 2. Wild-type and MMP-8-deficient mice were used for analysis of allergen-induced airway hyperresponsiveness and solubilization of IL-13R alpha 2.
Among several MMPs tested, only MMP-8 cleaved IL-13R alpha 2. Treatment of transfected human or murine cells expressing high levels of surface IL-13R alpha 2 with MMP-8 resulted in release of soluble IL-13R alpha 2 into the supernatants, with a concomitant decrease in surface IL-13R alpha 2 levels. The IL-13R alpha 2 solubilized by MMP-8 retained IL-13 binding activity. In an asthma model MMP-8-deficient mice displayed increased airway hyperresponsiveness and decreased soluble IL-13R alpha 2 protein levels in bronchoalveolar lavage fluid compared with those seen in wild-type mice after house dust mite challenge.
MMP-8 cleaves IL-13R alpha 2 in vitro and contributes to the solubilization of IL-13R alpha 2 in vivo.
白细胞介素13受体α2（IL-13Rα2）是白细胞介素13（IL-13）的高亲和力受体，IL-13是过敏性哮喘的关键介质。它主要作为诱饵受体发挥作用，但在某些情况下也可促进IL-13反应。IL-13Rα2以可溶性和膜结合形式存在，二者均可结合IL-13并调节其活性。然而，促成可溶性IL-13Rα2产生的蛋白水解过程在很大程度上尚不清楚。
我们试图研究基质金属蛋白酶（MMPs）在可溶性IL-13Rα2产生中的作用。
通过使用小鼠或人IL-13Rα2的谷胱甘肽-S-转移酶融合蛋白进行MMPs的无细胞切割试验。利用稳定转染IL-13Rα2的细胞分析可溶性IL-13Rα2的表面表达和释放。使用野生型和MMP-8缺陷型小鼠分析变应原诱导的气道高反应性以及IL-13Rα2的溶解情况。
在测试的几种MMPs中，只有MMP-8能切割IL-13Rα2。用MMP-8处理高表达表面IL-13Rα2的转染人或鼠细胞，导致可溶性IL-13Rα2释放到上清液中，同时表面IL-13Rα2水平降低。经MMP-8溶解的IL-13Rα2保留了IL-13结合活性。在哮喘模型中，与屋尘螨激发后的野生型小鼠相比，MMP-8缺陷型小鼠表现出气道高反应性增加，支气管肺泡灌洗液中可溶性IL-13Rα2蛋白水平降低。
MMP-8在体外切割IL-13Rα2，并在体内促成IL-13Rα2的溶解。
