Characterization and Significance of Monocytes in Acute Stanford Type B Aortic Dissection

Abstract

Acute aortic dissection (AAD) is one of the most common fatal diseases noted in vascular surgery. Human monocytes circulate in dynamic equilibrium and display a considerable heterogeneity. However, the role of monocytes in AAD remains elusive. In our recent study, we firstly obtained blood samples from 22 patients with Stanford type B AAD and 44 age-, sex-, and comorbidity-matched control subjects. And the monocyte proportions were evaluated by flow cytometry. Results showed that the percentage of total CD14+ monocytes in the blood samples of Stanford AAD patients was increased significantly compared with that of normal volunteers (P<0.0005), and the absolute numbers of CD14brightCD16+ and CD14brightCD16- monocytes both increased significantly regardless of the percentage of PBMC or CD14+ cells, while CD14dimCD16+ monocytes displayed the opposite tendency. However, the percentage of CD14+ cells and its three subsets demonstrated no correlation with D-dimer (DD) and C-reactive protein (CRP). Then, blood mononuclear cell (PBMC) samples were collected by Ficoll density gradient centrifugation, followed with CD14+ magnetic bead sorting. After the purity of CD14+ cells was validated over 90%, AAD-related genes were concentrated in CD14+ monocytes. There were no significant differences observed with regard to the mRNA expression levels of MMP1 (P=0.0946), MMP2 (P=0.3941), MMP9 (P=0.2919), IL-6 (P=0.4223), and IL-10 (P=0.3375) of the CD14+ monocytes in Stanford type B AAD patients compared with those of normal volunteers. The expression levels of IL-17 (P<0.05) was higher in Stanford type B AAD patients, while the expression levels of TIMP1(P<0.05), TIMP2(P<0.01), TGF-β1 (P<0.01), SMAD3 (P<0.01), ACTA2 (P<0.001), and ADAMTS-1 (P<0.001) decreased. The data suggested that monocytes might play an important role in the development of Stanford type B AAD. Understanding of the production, differentiation, and function of monocyte subsets might dictate future therapeutic avenues for Stanford type B AAD treatment and can aid the identification of novel biomarkers or potential therapeutic targets for decreasing inflammation in AAD.