OBJECTIVETo investigate the changes in the expressions of inducible cyclooxygenase type 2 (COX-2) and membrane associated prostaglandin E-1(mPGES-1) in human carotid atherosclerotic plaques and to explore possible mechanisms of inflammatory process involved in plaque stability.

METHODSThe mRNA and protein levels of COX-2 and mPGES-1 were compared between minimally and grossly atherosclerotic arterial tissues. COX-2 and mPGES-1 gene expression were established by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) in 10 mesenchymal artery controls and 24 atherosclerotic specimens. Presence of COX-2 and mPGES-1 protein was assessed by Western blotting.

RESULTSImmunohistochemical staining showed that the COX-2 and mPGES-1 immunoreactive substances were present in the cytoplasm of smooth muscle cell. Compared with the control group, immunostaining positive cells increased in carotid atherosclerotic plaque group. COX-2 and mPGES-1 gene expression was significantly elevated in atherosclerotic plaques (P< 0.05, respectively). The increased mRNA and protein levels of COX-2 and mPGES-1 were correlated in atherosclerotic tissue (P< 0.05). The mRNA and protein levels of COX-2 and mPGES-1 related to degree of pathological damage in atherosclerotic tissue (P< 0.05). COX-2 and mPGES-1 were not found in the control group (mesenteric vascular walls).

CONCLUSIONCOX-2 and mPGES-1 expression in plaques is significantly higher than that in the control group. These findings suggests that COX-2 and mPGES-1 might play a role in pathogenesis of atheroscleros and modulation of inflammatory process involved in plaque stability, and COX-2 may have proinflammatory enzyme properties.