Cairns J A, Walls A F
Immunopharmacology Group, Southampton General Hospital, UK.
J Immunol. 1996 Jan 1;156(1):275-83.
Tryptase, a protease unique to the mast cell secretory granule, is released in substantial quantities into the respiratory tract of patients with inflammatory disease of the airways. We have investigated the potential of tryptase to act as a mitogen for bronchial epithelial cells and to stimulate release of IL-8 and expression of ICAM-1. Tryptase was isolated from extracts of human lung tissue using ammonium sulphate precipitation, octyl agarose, and heparin agarose chromatography. Purified tryptase stimulated DNA synthesis in the human epithelial cell line H292, as measured by [3H] thymidine incorporation. Maximal growth was observed after 24 h using 25 mU/ml of tryptase (where 1 micron is defined as that which can hydrolyze 1 mumol of the peptide substrate N-alpha-benzoyl-DL-arginine p-nitroanilide hydrochloride per minute at 25 degrees C), a concentration that is likely to be achieved in vivo. Inhibitors of tryptase activity, including leupeptin and benzamidine hydrochloride, significantly decreased tryptase-induced stimulation of DNA synthesis, indicating the requirement for an active catalytic site. Tryptase stimulated a catalytic site-dependent release of IL-8 from epithelial cells after 24 h, and this was associated with up-regulation of ICAM-1 expression, as revealed by FACS analysis. Tryptase may play a critical role in epithelial repair and in the recruitment of granulocytes following mast cell activation.
类胰蛋白酶是肥大细胞分泌颗粒特有的一种蛋白酶，会大量释放到患有气道炎症性疾病患者的呼吸道中。我们研究了类胰蛋白酶作为支气管上皮细胞促分裂原以及刺激白细胞介素-8释放和细胞间黏附分子-1表达的潜力。使用硫酸铵沉淀、辛基琼脂糖和肝素琼脂糖色谱法从人肺组织提取物中分离类胰蛋白酶。通过[3H]胸苷掺入法测定，纯化的类胰蛋白酶刺激人上皮细胞系H292中的DNA合成。使用25 mU/ml的类胰蛋白酶（其中1个酶单位定义为在25℃下每分钟可水解1 μmol肽底物N-α-苯甲酰-DL-精氨酸对硝基苯胺盐酸盐的量），24小时后观察到最大生长，该浓度在体内可能会达到。类胰蛋白酶活性抑制剂，包括亮抑酶肽和盐酸苯甲脒，显著降低类胰蛋白酶诱导的DNA合成刺激，表明需要一个活性催化位点。24小时后，类胰蛋白酶刺激上皮细胞以催化位点依赖性方式释放白细胞介素-8，并且如流式细胞术分析所示，这与细胞间黏附分子-1表达上调有关。类胰蛋白酶可能在肥大细胞激活后的上皮修复和粒细胞募集中起关键作用。
