Research on the relationship between levels of soluble cluster of differentiation 40 ligand, matrix metalloproteinase 9 and pregnancy-associated plasma protein A in serum and stability of carotid plaques

Abstract

To study the relationship between serum levels of some inflammatory markers and stability of carotid plaques in the patients with carotid plaques and evaluate the ability of each serum marker in identifying vulnerable carotid plaques. The study included 65 consecutive patients with carotid plaques confirmed by imaging examinations from March 2008 to March 2010. All the patients were classified as stable plaques group (n = 21) and unstable plaques group (n = 44) according to the characteristic findings of the plaques in MRI such as the thickness of fibrous cap, the existence of large lipid core and the intra-plaque hemorrhage. The patients of unstable plaques group were further classified as unruptured plaques group (n = 29) and rupture plaques group (n = 15) according to the integrity of fibrous cap. Serum levels of soluble cluster of differentiation 40 ligand (sCD40L), matrix metalloproteinase 9 (MMP-9) and pregnancy-associated plasma protein A (PAPP-A) were determined by ELISA. Serum levels of sCD40L and MMP-9 in patients of unstable plaques group, unruptured plaques group and rupture plaques group were all significantly enhanced compared to individuals of stable plaques group (SCD40L: χ(2) = 6.45, 12.04 and 16.23, P < 0.01; MMP-9; F = 2.55, 5.10 and 4.69, P < 0.05). Serum levels of PAPP-A in patients of unstable plaques group and rupture plaques group were all significantly enhanced compared to individuals of stable plaques group (χ(2) = 11.71 and 13.55, P < 0.05). Serum levels of PAPP-A in patients of rupture plaques group were significantly enhanced compared to individuals of unruptured plaques group (χ(2) = 13.19, P = 0.000). sCD40L ≥ 673.22 ng/L (OR = 22.47, 95%CI: 2.11 - 239.81, P = 0.010), MMP-9 ≥ 84.09 µg/L (OR = 10.01, 95%CI: 1.74 - 57.78, P = 0.010) and PAPP-A ≥ 0.101 µg/L (OR = 14.29, 95%CI: 2.69 - 75.90, P = 0.002) were all significantly correlated with the vulnerability of carotid plaques. There appear to be a relationship between the serum levels of sCD40L, MMP-9 and PAPP-A and the stability of carotid plaques in patients with carotid plaques. High serum levels of the above-mentioned markers may indicate that the plaques were vulnerable or ruptured.