Lauren Fogel

Atherosclerosis destabilizes regulatory T cells (Tregs) resulting in multiple families of exTregs

Distinct Treg subsets in human peripheral blood are defined by unique transcriptomic signatures 2252633

Regulatory CD4+ T cells (Tregs) are critical for maintaining tolerance to self. Chronic inflammation can cause Treg instability which is defined by loss of CD25 and the lineage-defining transcription factor FOXP3, resulting in exTreg cells. To better understand the factors driving Treg to exTreg conversion, we analyzed transcriptomes of Treg subsets expressing varied levels of CD25 and FOXP3 in human peripheral blood CD4+ T cells. We found differential expression of genes related to inflammatory signaling (IFNG, TNF), cytotoxicity (PRF1, GZMB) and cellular stress (HSPA5). This was confirmed at the protein level by flow cytometry. Distinct Treg populations were also defined by unique metabolic profiles suggesting a role of cell-intrinsic metabolic programs in maintaining Treg stability. Our findings start to define novel cellular pathways contributing to Treg homeostasis and instability in human peripheral blood. We acknowledge the support from National Institutes of Health (awards P01 HL136275 and R35 HL145241) to K.L. Lymphocyte Differentiation and Peripheral Maintenance (LYM)

Regulatory T cells turn into multiple pro-inflammatory effector T cells in Mice with Atherosclerosis 2247491

Atherosclerosis is an immune-mediated disease in which regulatory T cells (Tregs) can lose lineage stability and convert into pro-inflammatory effector states (“exTregs”) that may accelerate plaque progression. However, the diversity, lineage relationships, and pathogenic roles of exTreg subsets in cardiovascular disease remain undefined. Using Foxp3 lineage-tracker Apoe-/- mice, we uncovered two distinct Treg subsets (GFP+tdTomatolow and GFP+tdTomatohi), with only the tdTomatohi population differentiating into exTregs (GFP-tdTomatohi). To comprehensively characterize these populations, we performed large-scale single-cell CITE-seq and TCR-seq across spleen, draining (axillar and cervical), and non-draining lymph nodes from Apoe-/- mice on a Western diet. Density-based clustering and trajectory inference revealed at least seven exTreg subsets, including Tfh-like (the largest population), Th1-like, Th17-like, cytotoxic and proliferating exTreg-like populations. Pseudotime analyses supported a branched rather than linear trajectory, with tdTomatohi Tregs giving rise to multiple effector-like programs. TCR analyses showed clonal enrichment predominantly within Tfh- and cytotoxic-like exTregs, suggesting antigen-driven expansion. CITE-seq identified surface markers (e.g., CXCR5/CD185 for Tfh-like and CXCR6/CD186 for cytotoxic Th1-like exTregs). Spatially, exTregs accumulated in draining lymph nodes and spleen, and were detectable in atherosclerotic plaques by intravital microscopy. Collectively, these data define a branched Treg-to-exTreg transition trajectory. Clonally expanded, antigen-experienced exTreg subsets that are expected to influence plaque biology. n/a Immune Response Regulation: Cellular Mechanisms (IRC)