Monocyte matrix metalloproteinase production in Type 2 diabetes and controls - a cross sectional study

Background: Coronary plaque rupture may result from localised over expression of matrix metalloproteinases (MMPs) within the plaque by infiltrating monocyte - macrophages. As MMP expression can be promoted by the modified lipoproteins, oxidative stress and hyperglycaemia that characterises Type 2 diabetes, we hypothesised that peripheral monocytes in these patients, exposed to these factors in vivo, would demonstrate increased MMP production compared to controls. Methods: We examined peripheral venous monocyte expression of MMP and tissue inhibitor of metalloproteinase-1 (TIMP-1) in 18 controls and 22 subjects with Type 2 diabetes and no previous cardiovascular complications. Results: No significant difference in MMP-1, 3 or 9 or TIMP-1 production was observed between control and diabetes groups. Conclusions: Monocyte MMP-1, 3, and 9, and TIMP-1, production are not abnormal in Type 2 diabetes. This data cannot be extrapolated to monocyte - macrophage behaviour in the vessel wall, but it does suggest MMP and TIMP-1 expression prior to monocyte infiltration and transformation are not abnormal in Type 2 diabetes.