C-Reactive Protein Stimulates MMP-1 Expression in U937 Histiocytes Through FcγRII and Extracellular Signal-Regulated Kinase Pathway:: An Implication of CRP Involvement in Plaque Destabilization

• Published in: Arteriosclerosis, thrombosis, and vascular biology Vol. 24; no. 1; pp. 61 - 66
• Main Authors: Williams, Takeyla N, Zhang, Cecelia X, Game, Bryan A, He, Lin, Huang, Yan
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Heart Association, Inc 01-01-2004; Hagerstown, MD Lippincott
• Subjects: Atherosclerosis (general aspects, experimental research); Biological and medical sciences; Blood and lymphatic vessels; Cardiology. Vascular system; Diseases of the peripheral vessels. Diseases of the vena cava. Miscellaneous; Medical sciences; C-reactive protein; Extracellular signal-regulated protein kinase; Enzyme; Metalloendopeptidases; Cardiovascular disease; Gene expression; Vascular disease; Peptidases; arteriosclerosis; Atherosclerosis; Hydrolases; matrix metalloproteinase; C reactive protein; Interstitial collagenase
• ISSN: 1079-5642; 1524-4636
• DOI: 10.1161/01.ATV.0000104014.24367.16

OBJECTIVE—It has been shown that plasma level of C-reactive protein (CRP) is an independent predictor for acute coronary syndromes and is associated with plaque weakening. However, the underlying mechanisms are not well understood. In this study, we investigated the effect of CRP on the expression of matrix metalloproteinase-1 (MMP-1) that has been implicated in plaque vulnerability by human U937 histiocytes and monocyte-derived macrophages.
METHODS AND RESULTS—Enzyme-linked immunosorbent assay of MMP-1 in conditioned medium showed that treatment of U937 cells with 100 μg/mL of CRP for 24 hour led to a 3- to 5-fold increase in MMP-1 secretion. CRP also markedly stimulated MMP-1 release from human monocyte-derived macrophages. In contrast, CRP had no effect on tissue inhibitor of metalloproteinase-1 (TIMP-1) secretion. Northern blot showed that CRP upregulated MMP-1 mRNA expression. Collagenase activity assay showed that CRP increased collagen-degrading activity in cell-conditioned medium. Furthermore, results showed that the stimulation of MMP-1 secretion by CRP was inhibited by anti-CD32, but not by anti-CD64 antibody, and by mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK) inhibitor PD98059. Finally, Western blot showed that CRP stimulated phosphorylation of extracellular signal-regulated kinase.
CONCLUSIONS—This study demonstrates that CRP stimulates MMP-1 expression by U937 cells through FcγRII and extracellular signal-regulated kinase pathway. These findings suggest that CRP may promote matrix degradation and thus contribute to plaque vulnerability.