Clonal expansion of CD8+ effector T cells in patients with calcific aortic valve disease

Calcific aortic valve disease (CAVD) is a complex cardiovascular pathology, culminating in aortic stenosis and heart failure with no effective treatment strategy, except invasive surgery. While inflammation may contribute to valvular fibro-calcific pathology and T cells have been identified within the leaflets, their contribution to CAVD pathogenesis remains unclear.

Disease-staged whole-tissue proteomics (n=16) confirmed a pro-inflammatory T cell driven signature, with immunohistochemistry (n=10) and immunofluorescence (n=8) conducted on control and CAVD valves to confirm T cell localization to calcified regions. Flow cytometry immunophenotyping (n=20) was was performed using valvular tissue and corresponding peripheral blood from the same individuals. Single cell RNA sequencing and paired single T cell receptor sequencing was conducted on an additional 4 patients on CD45+, CD3+, CD4+ or CD8+ T cells. T cell signaling was identified through unsupervised clustering. Tissue resident memory (TRM) T cells were detected within the valve, exhibiting a highly cytotoxic, activated, and terminally differentiated phenotype. This pan-pro-inflammatory signal was differentially identified in T cells originating from the valve tissue, and not observed in the blood, indicative of an adaptive, local and non-systemic inflammatory signature in CAVD patients. T cell receptor analysis detected hyperexpanded clones within the CD8+ T cell central memory (TCM) population, with TRM cells comprising most of the large and medium clonal expansion within the T cell population. Clonal expansion was more prominent in valve tissue, with expanded clones largely confined to their tissue of origin. Clonal interaction network analysis demonstrated the greatest proportion of clones originating from CD8+ TCM and TRM populations, exhibiting a tissue resident, cytotoxic environment within the valve.

Taken together, the data define distinct T cell subpopulations in CAVD and implicate specific antigenic epitopes driving clonal expansion of valvular T cells, supporting a central role for antigen-driven, autoimmune-like inflammation in disease propagation.