Despite the decades-old knowledge that males and people with diabetes mellitus (DM) are at increased risk for coronary artery disease (CAD), the reasons for this association are only partially understood. Among the immune cells involved, recent evidence supports a critical role of T cells as drivers and modifiers of CAD. CD4+ T cells are commonly found in atherosclerotic plaques. We aimed to understand the relationship of CAD with sex and DM by single-cell RNA (scRNA-Seq) and antibody sequencing (CITE-Seq) of CD4+ T cells. Peripheral blood mononuclear cells (PBMCs) of 61 men and women who underwent cardiac catheterization were interrogated by scRNA-Seq combined with 49 surface markers (CITE-Seq). CAD severity was quantified using Gensini scores, with scores above 30 considered CAD+ and below 6 considered CAD−. Four pairs of groups were matched for clinical and demographic parameters. To test how sex and DM changed cell proportions and gene expression, we compared matched groups of men and women, as well as diabetic and non-diabetic subjects. We analyzed 41,782 single CD4+ T cell transcriptomes for sex differences in 16 women and 45 men with and without coronary artery disease and with and without DM. We identified 16 clusters in CD4+ T cells. The proportion of cells in CD4+ effector memory cluster 8 (CD4T8, CCR2+ Em) was significantly decreased in CAD+, especially among DM+ participants. This same cluster, CD4T8, was significantly decreased in female participants, along with two other CD4+ T cell clusters. In CD4+ T cells, 31 genes showed significant and coordinated upregulation in both CAD and DM. The DM gene signature was partially additive to the CAD gene signature. We conclude that (1) CAD and DM are clearly reflected in PBMC transcriptomes, and (2) significant differences exist between women and men and (3) between subjects with DM and non-DM.

Coronavirus disease 2019 (COVID‐19) caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection can result in severe immune dysfunction, hospitalization, and death. Many patients also develop long‐COVID‐19, experiencing symptoms months after infection. Although significant progress has been made in understanding the immune response to acute SARS‐CoV‐2 infection, gaps remain in our knowledge of how innate immunity influences disease kinetics and severity. We hypothesized that cytometry by time‐of‐flight analysis of PBMCs from healthy and infected subjects would identify novel cell surface markers and innate immune cell subsets associated with COVID‐19 severity. In this pursuit, we identified monocyte and dendritic cell subsets that changed in frequency during acute SARS‐CoV‐2 infection and correlated with clinical parameters of disease severity. Subsets of nonclassical monocytes decreased in frequency in hospitalized subjects, yet increased in the most severe patients and positively correlated with clinical values associated with worse disease severity. CD9, CD163, PDL1, and PDL2 expression significantly increased in hospitalized subjects, and CD9 and 6‐Sulfo LacNac emerged as the markers that best distinguished monocyte subsets amongst all subjects. CD9 + monocytes remained elevated, whereas nonclassical monocytes remained decreased, in the blood of hospitalized subjects at 3–4 months postinfection. Finally, we found that CD9 + monocytes functionally released more IL‐8 and MCP‐1 after LPS stimulation. This study identifies new monocyte subsets present in the blood of COVID‐19 patients that correlate with disease severity, and links CD9 + monocytes to COVID‐19 progression.

BackgroundDespite the decades-old knowledge that diabetes mellitus (DM) is a major risk factor for cardiovascular disease (CVD), the reasons for this association are only partially understood. Among the immune cells involved in CVD development, accumulating evidence supports the critical role of T cells as drivers and modifiers of this condition. CD4+ T cells are commonly found in atherosclerotic plaques. The activity and distribution of CD4+ T cell subsets differs between the sexes.MethodsPeripheral blood mononuclear cells (PBMCs) of 61 men and women who underwent cardiac catheterization were interrogated by single cell RNA sequencing (scRNA-Seq, ∼200,000 cells) combined with 49 protein markers (CITE-Seq). Coronary artery disease (CAD) was quantified using Gensini scores, with scores above 30 considered CAD+ and below 6 considered CAD-. Four pairs of groups were matched for clinical and demographic parameters. To test how DM changed cell proportions and gene expression, we compared matched groups of diabetic and non-diabetic subjects. We analyzed 41,782 single CD4+ T cell transcriptomes for sex differences in 61 mostly statin-treated coronary artery disease patients with and without DM.ResultsWe identified 16 clusters in CD4 T cells. The proportion of cells in CD4 cluster 8 (CD4T8, CCR2+ Em) was significantly decreased in CAD+, especially among DM+ participants. The proportions of cells in CD4T2, CD4T11, CD4T16 were increased and CD4T13 was decreased in CAD+ among DM+Statin+ participants. CD4T12 was increased in DM+ participants. In female participants, CD4T8, 12, and 13 were decreased compared to in male participants. In CD4 T cells, 31 genes showed significant and coordinated upregulation in both CAD and DM. The DM gene signature was partially additive to the CAD gene signature.ConclusionsWe conclude that CAD and DM are clearly reflected in PBMC transcriptomes and that significant differences exist between women and men and between subjects treated with statins or not.