Autor:innen:
J. Pelisek (München, DE)
S. Merckelbach (Utrecht, DE)
E. Van der Vorst (München, DE)
M. Kallmayer (München, DE)
L. Mägdefessel (München, DE)
H. Eckstein (München, DE)
Objectives: The CXCL12/CXCR4 axis has already been implicated in intimal hyperplasia as well as various inflammatory diseases. However, the exact role of these chemokines in atherosclerosis has not yet been elucidated. The aim of this study was therefore to analyse the expression and cellular localisation of CXCR4 and CXCL12 in different stages of human carotid atherosclerotic plaques and control vessels.
Methods: Carotid plaques (n = 58) were obtained during carotid endarterectomy. As a control, 10 healthy vessels were included. Specimens were either fixed in formalin and embedded in paraffin (FFPE) (20 stable, 20 unstable plaques) or immediately frozen in liquid nitrogen (fresh frozen, 11 stable, 7 unstable plaques). FFPE samples were used for expression analysis at mRNA-level and for immunohistochemistry. Fresh frozen samples served expression analysis at protein level using Enzyme-linked Immunosorbent Assay (ELISA). For cellular localisation, macrophages, leukocytes, T-cells, B-cells, neovessels, and different phenotype smooth muscle cells (SMCs) were analysed, using correlation approach at mRNA level, consecutive and double staining.
Results: Significant differences in expression of CXCR4 at mRNA level were observed between controls and unstable plaques (P=0.011). Expression of CXCL12 at mRNA level was successively augmented, achieving highest expression in unstable lesions (P<0.001). At protein level, CXCR4 and CXCL12 were significantly increased in atherosclerotic lesions compared to controls (P=0.001, 0.035 and P=0.003, 0.045 for stable und unstable plaques). CXCR4 was localised particularly in macrophages and small neovessels. Weak positive staining was observed in T-cells, SMCs were negative. For CXCL12, no positive cells were detected. However, at mRNA level CXCL12 was significantly associated with inflammatory cells, neovessels and synthetic SMCs.
Conclusion: Expression of CXCR4 and CXCL12 was significantly increased in both stable and unstable carotid atherosclerotic plaques compared to healthy vessels, both at mRNA and protein level. CXCR4 was localised particularly in macrophages, followed by leukocytes. Week expression was observed also in SMCs. In contrast, CXCL12 was associated only with macrophages.