Immune profiling of eosinophilic fasciitis by single cell rna sequencing

Summary: <br /> Eosinophilic fasciitis (EF) is a rare inflammatory condition characterized by fibrosis of the fascia and subcutaneous tissue accompanied by variable degrees of eosinophilic infiltration. Although disease etiology remains unclear, T cells have been implicated in pathogenesis in histopathological studies.¹ Using single cell RNA sequencing (scRNAseq), we characterized the immune cell populations from three EF patients as compared to healthy controls. Preliminary data revealed a trend towards increased presence of T cell, B cell, and plasma in EF samples relative to healthy controls. Further characterization of T cells in EF samples revealed a predominance of two CD8 T cell phenotypes. Furthermore, natural killer cells populations also appear increased in EF specimens. TCR repertoire analyses demonstrated clonal expansion in one CD8 T cell population. Overall, these early findings suggest a dominant type 1 cytotoxic response in EF. While the significance of the observed expansion of B cells and plasma cells remains unclear, the clinical improvement of improvement in one patient with the addition of rituximab, a therapy targeting CD20-expressing B cells, warrants further investigation into their role in disease progression. Ian Boothby¹, Maha Kazmi^{1, 2}, Maxime Kinet³, Anna Haemel¹, Michael Rosenblum¹ 1. Dermatology, University of California San Francisco, San Francisco, CA, United States. 2. School of Medicine, University of California Davis, Sacramento, CA, United States. 3. Division of Rheumatology, Department of Medicine, University of California San Francisco, San Francisco, CA, United States. Translational Studies: Cell and Molecular Biology