CXCR4 and thoracic aortic aneurysm: On the other hand, MIF- (CD74+CXCR4) and MIF- (CD74+CD44) ligand–receptor pairs were significantly enriched in signaling sent from SMC subsets and received by macrophage subsets in the AAA group compared with the normal AA group, while the enrichment of these two ligand–receptor pairs in thoracic aortic aneurysm only presented in hFibromyocte and hTREM2 Mφ (Figure 6C).