title: Granzyme K activates protease-activated receptor-1.
abstract: 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.
authors.affiliation: Institute for Heart and Lung Health, St. Paul's Hospital, Vancouver, British Columbia, Canada.
authors.forename: Dawn M
authors.initials: DM
authors.lastname: Cooper
authors.forename: Dmitri V
authors.initials: DV
authors.lastname: Pechkovsky
authors.forename: Tillie L
authors.initials: TL
authors.lastname: Hackett
authors.forename: Darryl A
authors.initials: DA
authors.lastname: Knight
authors.forename: David J
authors.initials: DJ
authors.lastname: Granville
mesh_terms: D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D018932:Chemokine CCL2 / Q000096:biosynthesis / Q000378:metabolism; D005110:Extracellular Space / Q000187:drug effects / Q000201:enzymology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D053804:Granzymes / Q000494:pharmacology*; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D015850:Interleukin-6 / Q000096:biosynthesis / Q000378:metabolism; D016209:Interleukin-8 / Q000096:biosynthesis / Q000378:metabolism; D008168:Lung / Q000166:cytology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D044463:Receptor, PAR-1 / Q000378:metabolism*; D013917:Thrombin / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: C111835:CCL2 protein, human; D018932:Chemokine CCL2; D015850:Interleukin-6; D016209:Interleukin-8; D044463:Receptor, PAR-1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D053804:Granzymes; D013917:Thrombin