Extracellular Matrix-induced Cyclooxygenase-2 Regulates Macrophage Proteinase Expression

Abstract

Chronic inflammatory diseases are characterized by the persistent presence of macrophages and other mononuclear cells, tissue destruction, cell proliferation, and the deposition of extracellular matrix (ECM). The tissue degradation is mediated, in part, by enhanced proteinase expression by macrophages. It has been demonstrated recently that macrophage proteinase expression can be stimulated or inhibited by purified ECM components. However, in an intact ECM the biologically active domains of matrix components may be masked either by tertiary conformation or by complex association with other matrix molecules. In an effort to determine whether a complex ECM produced by vascular smooth muscle cells (SMC) regulates macrophage degradative phenotype, we prepared insoluble SMC matrices and examined their ability to regulate proteinase expression by RAW264.7 and thioglycollate-elicited peritoneal macrophages. Here we demonstrate that macrophage engagement of SMC-ECM triggers PKC-dependent activation of MAPK erk1/2 leading to increased expression of cyclooxygenase (COX)-2 and prostaglandin (PG) E 2 synthesis. The addition of PGE 2 to macrophage cultures stimulates their expression of both urokinase-type plasminogen activator and MMP-9, and the selective COX-2 inhibitor NS-398 blocks ECMinduced proteinase expression. Moreover, ECM-induced PGE 2 and MMP-9 expression by elicited COX-2 ؊/؊ macrophages is markedly reduced when compared with the response of either COX-2 ؉/؊ or COX-2 ؉/؉ macrophages. These data clearly demonstrate that SMC-ECM exerts a regulatory role on the degradative phenotype of macrophages via enhanced urokinase-type plasminogen activator and MMP-9 expression, and identify COX-2 as a targetable component of the signaling pathway leading to increased proteinase expression.The structural integrity of tissue is compromised in a variety of inflammatory settings by macrophage expression of serine and matrix metalloproteinases (MMPs). 1 Principal among the serine proteinases is urokinase-type plasminogen activator (uPA) (1). Cleavage of plasminogen by uPA generates plasmin, which binds to and degrades fibrin and components of the ECM (2-4). Several studies have demonstrated that uPA-dependent plasminogen activation regulates macrophage migration (5-7), degradation of extracellular matrices (7-9) and fibrin (10, 11), and the release of matrix-bound growth factors (12-14). Moreover, the important role of plasminogen activation in macrophage migration and clearance of fibrin and necrotic tissue following injury has been confirmed by utilizing mice deficient in components of the uPA-plasminogen system (15)(16)(17)(18)(19)(20).In addition to the uPA/plasminogen system, macrophages express MMPs, which are associated with tissue remodeling via their ability to degrade ECM components (21,22). Macrophages, depending on their origin and state of activation, express several members of the MMP family including MMP-9 (23, 24). As observed for the uPA/plasminogen system, several studies have suggested a role for MMP-9 in cell ...

The Prostanoid EP4 Receptor and Its Signaling Pathway

“…MMP-9 expression is low or absent in most normal tissues, but is markedly upregulated during chronic inflammation and cancer (Parks et al, 2004). MMP-9 expression was markedly reduced in macrophages isolated from COX-2-deficient mice and in wild-type macrophages treated with COX-2 inhibitors (Khan et al, 2004). Consistent with these results, pharmacological EP4 activation increased MMP-9 expression and activity in human monocytes and macrophages derived from atherosclerotic plaque (Cipollone et al, 2005).…”

Cyclooxygenase-2 Deficiency Enhances Th2 Immune Responses and Impairs Neutrophil Recruitment in Hepatic Ischemia/Reperfusion Injury

“…We have recently shown that MMP-9 mediates the transmigration of activated neutrophils across fibronectin (29), a key ECM protein expressed very early by endothelial cells in liver I/R injury (31). Others have shown that COX-2 inhibition in vitro is able to block ECM-induced MMP-9 by RAW264.7 macrophage-like cells (55), likely by targeting PGE 2 receptors in these cells (56). In our study, COX-2 Ϫ/Ϫ mice had reduced numbers of MMP-9-positive neutrophils infiltrating the livers after I/R injury; thus, it is reasonable to postulate that COX-2, through selective prostanoid-receptor interactions, may also regulate MMP-9 expression by these cells.…”

Metalloproteinase Expression in Monocytes and Macrophages and its Relationship to Atherosclerotic Plaque Instability

“…28 MMPs-1, -2, -3, -7, -9, -10, -12, -14, and -19 appear to be coordinately upregulated in HPBM or monocyte cell lines after brief culture on or adhesion to preformed ECM 29 or defined ECM components including laminin, collagen, SIKVAV peptide, fibronectin or extracellular MMP inducer (EMMPRIN) 28,30 -37 (supplemental Table I, available online at http://atvb.ahajournals.org). Binding to platelets enhances the effects of binding to ECM proteins, owing to cooperation between signaling from integrins and P-selectin.…”

“…29,33 MMP upregulation can be mimicked by adding PGE2 39,40 or forskolin, 41 a direct activator of adenylate cyclase. Induction of MMPs may be blocked by integrin-blocking antibodies 36 and by COX inhibitors, including selective COX-2 inhibitors, 29,33,40 and antagonists at the EP4 receptor.…”