Immune cell census in murine atherosclerosis: cytometry by time of flight illuminates vascular myeloid cell diversity

Abstract

AimsAtherosclerosis is characterized by the abundant infiltration of myeloid cells starting at early stages of disease. Myeloid cells are key players in vascular immunity during atherogenesis. However, the subsets of vascular myeloid cells have eluded resolution due to shared marker expression and atypical heterogeneity in vascular tissues. We applied the high-dimensionality of mass cytometry to the study of myeloid cell subsets in atherosclerosis.Methods and resultsApolipoprotein E-deficient (ApoE−/−) mice were fed a chow or a high fat (western) diet for 12 weeks. Single-cell aortic preparations were probed with a panel of 35 metal-conjugated antibodies using cytometry by time of flight (CyTOF). Clustering of marker expression on live CD45+ cells from the aortas of ApoE−/− mice identified 13 broad populations of leucocytes. Monocyte, macrophage, type 1 and type 2 conventional dendritic cell (cDC1 and cDC2), plasmacytoid dendritic cell (pDC), neutrophil, eosinophil, B cell, CD4+ and CD8+ T cell, γδ T cell, natural killer (NK) cell, and innate lymphoid cell (ILC) populations accounted for approximately 95% of the live CD45+ aortic cells. Automated clustering algorithms applied to the Lin-CD11blo-hi cells revealed 20 clusters of myeloid cells. Comparison between chow and high fat fed animals revealed increases in monocytes (both Ly6C+ and Ly6C−), pDC, and a CD11c+ macrophage subset with high fat feeding. Concomitantly, the proportions of CD206+ CD169+ subsets of macrophages were significantly reduced as were cDC2.ConclusionsA CyTOF-based comprehensive mapping of the immune cell subsets within atherosclerotic aortas from ApoE−/− mice offers tools for myeloid cell discrimination within the vascular compartment and it reveals that high fat feeding skews the myeloid cell repertoire toward inflammatory monocyte-macrophage populations rather than resident macrophage phenotypes and cDC2 during atherogenesis.

COVID-19 and the cardiovascular system: implications for risk assessment, diagnosis, and treatment options

“…While little is known regarding the effects of COVID-19 on ACS, several pathways associated with viral diseases may contribute to destabilize plaques in COVID-19 patients. 57 Heart failure patients are at increased risk of acute events or exacerbation; viral illness can potentially destabilize atherosclerotic plaques through systemic inflammatory responses, 58 cytokine storm, as well as specific changes of immune cell polarization towards more unstable phenotypes. All of these have been observed in COVID- 19. In the case of SARS and MERS, acute MI 59,60 has been reported in two out of the five deaths in early reports.…”

Is Toll-like receptor 4 involved in the severity of COVID-19 pathology in patients with cardiometabolic comorbidities?

“…The viral illness, through systemic inflammatory responses and changes of immune cell polarization towards more unstable phenotypes, is responsible for the increased risk of acute cardiovascular events or exacerbations of chronic conditions [ 71 ]. Furthermore, the IL-6, reported as a mortality predictor in severe COVID-19 cases, is an important biomarker of cardiovascular morbidity and mortality linked to atherosclerosis [ 72 ].…”

Type-I interferons in atherosclerosis

“…In vitro data revealed that oxidized LDL (oxLDL) triggers the expression of type-I IFNs in cultured mouse eosinophils via CD36 and suppresses Il4 expression, and subsequently polarizes macrophages to a proinflammatory phenotype (Table 1 and pDCs and mDCs pDCs are known to have the ability to rapidly produce massive amounts of type-I IFNs and are present in both murine and human atherosclerotic lesions as well as intact aorta (Chistiakov et al, 2014;Cole et al, 2018;Döring et al, 2012;Yun et al, 2016). Single-cell data revealed an increased amount of pDCs in aortas from Apoe −/− mice fed a high-fat diet compared with mice fed normal chow (Cole et al, 2018). In human plaques, CD123 + pDCs localize closely to T cells and mDCs in the unstable shoulder region (Chistiakov et al, 2014;Niessner et al, 2006Niessner et al, , 2007 and accumulate during atherogenesis ( Fig.…”