Single Cell Transcriptomics and Immune Profiling Identifies Distinct CD8+ Granzyme K+ T Cell Responses in Cutaneous Lyme Disease 9331

Abstract Description The skin lesion erythema migrans (EM) is the first clinical sign of infection with the tick-transmitted bacterium Borrelia burgdorferi (Bb), the agent of Lyme disease. According to histopathology, T cells are the dominant immune cell type that infiltrates EM lesions. To interrogate the T cell response, we performed single-cell RNA and T cell receptor sequencing using 10x Genomics on PBMCs and whole skin cell digests of biopsies of paired EM lesions and autologous uninvolved skin from 13 subjects with Lyme disease. We found that T cells were significantly more represented in the EM versus the uninvolved skin (29% of the total cells vs. 9% respectively). While CD4+ IFNG+ T cell subsets were abundant in both the EM and the uninvolved skin, we identified a unique subpopulation of CD8+ GZMK+ T cells that differentially expressed IFNG in the EM. These EM-associated CD8+ GZMK+ IFNG+ T cells were clonally expanded and a subset could be traced to the circulation. CD4+ FOXP3+ regulatory T cells were also increased in the EM, although the highest expression of IL-10 was seen in a CD4+ FOXP3- effector T cell subset. T cell recruiting chemokines were mainly expressed by fibroblasts, endothelial cells and pericytes, rather than macrophages, consistent with studies that show perivascular lymphocytic infiltrates in the EM. These findings represent the first comprehensive interrogation of the cutaneous T cell response to Bb infection using single cell transcriptomics. Funding Sources Supported by the National Institute of Allergy and Infectious Diseases of the NIH through the U19-AI089992 and T15LM007056 grants. It was also supported by the Harold W. Jockers Professorship to Linda K. Bockenstedt. Topic Categories Computational and Systems Immunology (COMP)