W116 - Novel B Cell Subsets as Potential Biomarkers in Idiopathic Inflammatory Myopathies: Insights into Disease Pathogenesis and Disease Activity

Vladimir Mandujano-López – Universidad Nacional Autónoma de México; Beatriz Alcalá-Carmona – Instituto Politécnico Nacional; María Ostos-Prado – Universidad Nacional Autónoma de México; Guadalupe Velásquez-Ortiz – Universidad Nacional Autónoma de México; Yatzil Reyna-Juárez – Universidad Nacional Autónoma de México; Jiram Torres-Ruiz – Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán; Diana Gómez-martin – Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán; José Maravillas-montero – Universidad Nacional Autónoma de México

Abstract Text: Idiopathic inflammatory myopathies are a heterogeneous group of rare autoimmune disorders characterized by progressive muscle weakness and the histopathologic findings of inflammatory infiltrates in muscle tissue. The diagnosis of IIM is based on clinical manifestations and is complicated due to the lack of reliable clinical biomarkers. Although their pathogenesis remains indefinite, the detection of specific autoantibodies and the evidence of the high effectiveness of depleting therapies suggest that B cells could be implicated. However, little is known about changes in peripheral blood B cell subsets in IIM patients and how these changes are related to disease activity. Therefore, we isolated PBMCs from 27 patients and 24 healthy controls and explored the landscape of peripheral B cells in this disease by multiparametric flow cytometry. We found significant numerical decreases in memory and double negative subsets, as well as an expansion of the naïve compartment relative to healthy controls, that contribute to defining disease-associated B cell subset signatures and correlating with different clinical features of patients such as the Visual Analog Scale (VAS) for disease activity and the Manual Muscle Testing (MMT8) muscle strength scale. Additionally, we determined the potential value of these subsets as diagnostic biomarkers, thus positioning B cells as neglected key elements possibly participating in the onset or development of idiopathic inflammatory myopathies.