Institute for Heart and Lung Health, St. Paul's Hospital, Vancouver, British Columbia, Canada.
PLoS One. 2011;6(6):e21484. doi: 10.1371/journal.pone.0021484. Epub 2011 Jun 30.
Granzyme K (GrK) is a trypsin-like serine protease that is elevated in patients with sepsis and acute lung inflammation. While GrK was originally believed to function exclusively as a pro-apoptotic protease, recent studies now suggest that GrK may possess other non-cytotoxic functions. In the context of acute lung inflammation, we hypothesized that GrK induces pro-inflammatory cytokine release through the activation of protease-activated receptors. The direct effect of extracellular GrK on PAR activation, intracellular signaling and cytokine was assessed using cultured human lung fibroblasts. Extracellular GrK induced secretion of IL-6, IL-8 and MCP-1 in a dose- and time-dependent manner in lung fibroblasts. Heat-inactivated GrK did not induce cytokine release indicating that protease activity is required. Furthermore, GrK induced activation of both the ERK1/2 and p38 MAP kinase signaling pathways, and significantly increased fibroblast proliferation. Inhibition of ERK1/2 abrogated the GrK-mediated cytokine release. Through the use of PAR-1 and PAR-2 neutralizing antibodies, it was determined that PAR-1 is essential for GrK-induced IL-6, IL-8 and MCP-1 release. In summary, extracellular GrK is capable of activating PAR-1 and inducing fibroblast cytokine secretion and proliferation.
颗粒酶 K（GrK）是一种胰蛋白酶样丝氨酸蛋白酶，在脓毒症和急性肺炎症患者中升高。虽然 GrK 最初被认为仅作为一种促凋亡蛋白酶发挥作用，但最近的研究表明 GrK 可能具有其他非细胞毒性功能。在急性肺炎症的情况下，我们假设 GrK 通过激活蛋白酶激活受体诱导促炎细胞因子的释放。使用培养的人肺成纤维细胞评估细胞外 GrK 对 PAR 激活、细胞内信号转导和细胞因子的直接影响。细胞外 GrK 以剂量和时间依赖性方式诱导肺成纤维细胞中 IL-6、IL-8 和 MCP-1 的分泌。热失活的 GrK 不会诱导细胞因子释放，表明需要蛋白酶活性。此外，GrK 诱导 ERK1/2 和 p38 MAP 激酶信号通路的激活，并显著增加成纤维细胞增殖。ERK1/2 的抑制消除了 GrK 介导的细胞因子释放。通过使用 PAR-1 和 PAR-2 中和抗体，确定 PAR-1 是 GrK 诱导的 IL-6、IL-8 和 MCP-1 释放所必需的。总之，细胞外 GrK 能够激活 PAR-1 并诱导成纤维细胞细胞因子的分泌和增殖。
