Roles for thrombin and fibrin(ogen) in cytokine/chemokine production and macrophage adhesion in vivo

Abstract

Extravascular coagulation leading to fibrin deposition accompanies many immune and inflammatory responses. Although recognized by pathologists for decades, and probably pathologic under certain conditions, the physiologic functions of extravascular coagulation remain to be fully defined. This study demonstrates that thrombin can activate macrophage adhesion and prompt interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) production in vivo. Peritoneal macrophages were elicited with thioglycollate (TG) and then activated in situ, either by intraperitoneal injection of lipopolysaccharide (LPS) or by injection of antigen into mice bearing antigen-primed T cells. Others previously established that such treatments stimulate macrophage adhesion to the mesothelial lining of the peritoneal cavity. The present study demonstrates that thrombin functions in this process, as macrophage adhesion was suppressed by Refludan, a highly specific thrombin antagonist, and induced by direct peritoneal administration of purified thrombin. Although recent studies established that protease activated receptor 1 (PAR-1) mediates some of thrombin's proinflammatory activities macrophage adhesion occurred normally in PAR-1-deficient mice. However, adhesion was suppressed in fibrin(ogen)-deficient mice, suggesting that fibrin formation stimulates macrophage adhesion in vivo. This study also suggests that fibrin regulates chemokine/cytokine production in vivo, as direct injection of thrombin stimulated peritoneal accumulation of IL-6 and MCP-1 in a fibrin(ogen)-dependent manner. Given that prior studies have clearly established inflammatory roles for PAR-1, thrombin probably has pleiotropic functions during inflammation, stimulating vasodilation and mast cell degranulation via PAR-1, and activating cytokine/chemokine production and macrophage adhesion via fibrin(ogen). IntroductionVasodilation and increased vascular permeability are among the earliest signs of inflammation. These events stimulate the extravasation of inactive coagulant precursors, which become activated upon exposure to extravascular tissues. The ensuing coagulation cascade culminates with the generation of thrombin, a protease that cleaves extravasated fibrinogen, prompting its polymerization and deposition as fibrin. Accordingly, localized extravascular fibrin deposition accompanies many type 1 T helper cell (Th1)-associated responses, including autoimmune neuropathologies, 1-4 glomerulonephritis, 5,6 rheumatoid arthritis, 7-9 Crohn's disease, 10,11 allograft rejection, 12,13 delayed-type hypersensitivity, 14-19 and viral infections. 20,21 For some time, it has been appreciated that such Th1-associated coagulation has physiologic consequences, as the swelling that accompanies delayed-type hypersensitivity responses is suppressed in anticoagulated or fibrinogen-deficient subjects. [14][15][16][17][18][19] However, the full significance of immune-associated extravascular coagulation remains to be defined.Recent studies suggest that thrombin is a physiologic m...

Excessive Fibrin Deposition in Nasal Polyps Caused by Fibrinolytic Impairment through Reduction of Tissue Plasminogen Activator Expression

“…However, disorder of fibrin turnover facilitates abnormal fibrin deposition and can be deleterious because of its proinflammatory properties (8,23). Fibrin can directly stimulate expression of IL-1b and TNF-a in mononuclear cells and can induce production of the chemokines CXCL8 and CCL2 by endothelial cells and fibroblasts, promoting the migration of leukocytes and macrophages (8,24). Indeed, some evidence suggests that removal of fibrin can diminish disease development and symptoms (8,(25)(26)(27)(28).…”

Metalloproteinase-mediated Shedding of Integrin β2 Promotes Macrophage Efflux from Inflammatory Sites

“…Extravascular fibrin deposition is an early and persistent hallmark of the inflammatory response in the peritonitis model and promotes macrophage cell-cell and cell-fibrin interactions, thus serving as a provisional matrix for recruited macrophages (24,26,27). Deficiency in fibrin(ogen) does not prevent macrophage infiltration in response to thioglycollate, but it does impair macrophage activation (28) and adhesion to the peritoneal cavity mesothelial lining (24).…”

“…To test this hypothesis, we used a model of accelerated macrophage exiting from the peritoneal cavity stimulated by LPS activation of thioglycollate-elicited macrophages (17,24) shown in Fig. 3A.…”

“…3A. In this model, LPS promotes macrophage adhesion and migration across the mesothelium into the lymphatics in a fibrin-dependent manner (24). To block ␤2 integrin cleavage, the metalloprotease inhibitor GM6001 was injected 15 min prior to LPS administration, and cells remaining in the peritoneal cavity 4 h after LPS were collected and analyzed (Fig.…”

Reactive carbonyl compounds (RCCs) cause aggregation and dysfunction of fibrinogen

“…al., 2001), phagocytosis (Rubel et al, 2001(Rubel et al, , 2002, cytokine and chemokine expression (Fan and Edgington, 1993;RL Perez 1995;Smiley et. al., 2001;Szaba and Smiley, 2002), and degranulation (Rubel et. al., 2002;Tuluc et.…”