INCREASED LEVELS OF SOLUBLE LDL RECEPTOR-RELATED PROTEIN ARE ASSOCIATED WITH ACUTE CORONARY SYNDROMES
K.A. Quinn*, V. Pye, Y-P Dai, Y. Singh, #C.P. Juergens, #A.H. Hopkins, #N. Dwivedi, H.C. Lowe, ^A. Caruana, C.N. Chesterman, ¶D.A. Owensby.
Centre for Thrombosis and Vascular Research, University of New South Wales, #Cardiology Department, Liverpool Hospital, ^Eastern heart Clinic, Prince of Wales Hospital and ¶Department of Cardiology, Wollongong Hospital, New South Wales.
Background: The low density lipoprotein receptor-related protein (LRP)expressed on macrophages and vascular smooth muscle cells, is over-expressed in the diseased vessel wall and has been implicated in vascular remodelling and the atherogenic process. A metalloproteinase releases a soluble form of LRP (sLRP), which circulates in normal human plasma. Metalloproteinases have been associated with plaque rupture which triggers acute coronary syndromes. This study investigated whether increased plasma sLRP is associated with acute coronary syndromes.
Method: sLRP in plasma was quantitated with an ELISA assay.
Results: Compared to a group of healthy blood donors (mean sLRP: 1.29 mg/ml +/- 0.48 mg/ml, n = 50), sLRP levels were significantly increased in patients with acute myocardial infarction ((1.693 +/- 0.76 mg/ml, n = 25) and unstable angina pectoris (1.73 +/- 0.53 mg/ml, n = 27; p<0.02, ANOVA). In contrast, sLRP levels were not significantly increased in patients with stable angina pectoris (1.475 +/- 0.87 mg/ml n = 28, p>0.05). Preliminary results indicate sLRP was elevated acutely in 6/9 patients following lesion perturbation with PTCA: sLRP before PTCA = 2.5 +/- 0.4 mg/ml, immediately after PTCA = 2.06 +/- 0.24 mg/ml, 16 hours following PTCA = 5.452 +/- 2 mg/ml, (p<0.005, repeated measures ANOVA). These preliminary studies suggest that plasma sLRP levels may be associated with the presence of acute coronary syndromes.
