Analysis of T cell receptor repertoire and TCR-HLA interactions in pemphigus vulgaris

Summary: Abstract Body: Pemphigus vulgaris (PV) is a prototypical organ specific human autoimmune disease that presents clinically with flaccid blister formation on the skin and mucous membranes. The disease genetic risk factors are polygenic with both Human Leukocyte Antigen (HLA) and non-HLA susceptibility genes playing important roles in disease progression. Previous studies in ethnically diverse populations show that DRB1*0402, and DQB1*0503 HLA alleles are significantly overrepresented in PV patients. In autoimmune diseases, the T cell receptors (TCRs) recognize self-antigenic proteins presented by HLA. Analyzing the TCR repertoire and TCR-HLA interactions can provide major insights into disease mechanisms driving the initiation and progression of the autoimmune response in PV. This study leverages computational models to analyze TCR repertoire and TCR-HLA interactions and identify common somatic mutations in TCRs associated with recognition of self-antigens in PV. We evaluated 15 subjects, including 4 active PV patients (PV-A), 3 patients in late remission (PV-LTR), 2 patients in partial remission (PV-PR), 3 HLA-matched controls, and 3 HLA-unmatched controls. PCMBs were collected from patients and RNA was isolated for Single Cell RNA Sequencing. The data was analyzed using 10X Genomics tools and R. Out of 85,736 sequenced cells, 50,335 cells (58.71%) produced V-J spanning pairs, yielding 79,219 distinct TCR clonotypes. Overall, we found TCR clonotypes to be very diverse across the different patient and control groups. TCR V(D)J gene usage was analyzed and differentially expressed genes were identified. Analysis of TCR clonotypes of individual patients revealed the presence of somatic mutations in the V(D)J sequences, which are hypothesized to be associated with PV. These mutations were found in both HLA binding regions and other sites. To assess the significance of these mutations, binding scores of these TCRs and the HLA alleles were predicted. The study aims to identify shared mutations that may contribute to the development of PV. Harshitha Basapura Suresha¹, Kristina Seiffert-Sinha¹, Animesh A. Sinha¹ 1. Dermatology, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY, United States. Adaptive and Auto-Immunity