Charactering the immune signature of antigen presenting cells in the immune response to factor VIII in a murine model of hemophilia A using single-cell RNA sequencing

Abstract Deficiency of the procoagulant protein factor VIII (FVIII) is defining characteristic for individuals with inherited X-linked bleeding disorder hemophilia A. These require intravenous infusions FVIII to treat events, however ~30% develop neutralizing alloantibodies (i.e., inhibitors) against exogenous FVIII. Transcriptome analysis FVIII-stimulated peripheral blood mononuclear cells in patients A and active inhibitors showed increased expression innate immune modulators proinflammatory pathways. Murine models (FVIII KO) similarly anti-FVIII antibodies exposure. Although antibody response CD4-T cell dependent, key antigen presenting (APCs) that mediate inhibitor formation unclear. Bone marrow chimeras transgenic mice depleted dendritic (DC) subsets KO suggest type 2 classical DCs (cDC2), but not cDC1 or plasmacytoid DCs, immunity. We then evaluated evolution splenic APCs their signatures injected 0, 1, 3, 5 doses using flow cytometry single-cell RNA sequencing (scRNAseq). had similar frequencies pDC, cDC1, cDC2 compared normal saline as a control. However, preliminary scRNAseq demonstrated phagocytic interferon-related genes among DC macrophage clusters, particularly CD8a −CD4 +Itgax −DCs. Further analyses APC subclusters differentially expressed will be assessed. Overall, these findings cDCs, specifically cDC2, are critical Supported by NIH K99HL150595 Hemophilia Georgia Clinical Scientist Development Grant.