Antagonistic regulation of macrophage phenotype by M-CSF and GM-CSF: Implication in atherosclerosis

Abstract Objectives We characterized the transcriptional profiles of GM-CSF- (GM-MO) and M-CSF-induced macrophages (M-MO) and investigated in situ a subset of differentially expressed genes in human and mouse atherosclerotic lesions. Methods and results Using microarrays we identified a number of genes and biological processes differentially regulated in M-MO vs GM-MO. By varying in culture the M-CSF/GM-CSF ratio (0–10), a spectrum of macrophage phenotypes was explored by RT-QPCR. M-CSF (10 ng/ml) stimulated expression of several genes, including selenoprotein-1 ( SEPP1 ), stabilin-1 ( STAB1 ) and CD163 molecule-like-1 ( CD163L1 ) which was inhibited by a low dose of GM-CSF (1 ng/ml); M-CSF inhibited the expression of pro-platelet basic protein ( PPBP ) induced by GM-CSF. Combining Tissue Microarrays/quantitative immunohistochemistry of human aortic lesions with RT-QPCR expression data either from human carotids vs mammary non-atherosclerotic arteries or from the apoE null mice normal and atherosclerotic aortas showed that, STAB1 , SEPP1 and CD163L1 (M-CSF-sensitive genes) and PPBP (GM-CSF-sensitive gene) were expressed in both human arterial and apoE null mice atherosclerotic tissues. Conclusion A balance between M-CSF vs GM-CSF defines macrophage functional polarisation and may contribute to the progression of atherosclerosis.