Roles of Reactive Oxygen Species in Modulation of Thymocyte Subpopulations during Thymic Atrophy

Abstract

Abstract The thymus is the site of T cell development, selection and maturation. Precursor cells migrate from the bone marrow to the thymus, where they undergo sequential development followed by selection to give rise to mature and functional T cells. The cell surface expressions of various markers define distinct stages of development and maturation of thymocytes. With the help of these markers and multicolour flow cytometry, we have standardized staining procedures to study different thymocyte subsets during atrophy. We have also standardized an acute and lethal model of oral Salmonella Typhimurium infection in BALB/c mice, wherein drastic reduction of thymic cellularity is observed. Using multicolour flow cytometry, we investigated the changes occurring in thymocyte subsets in this model of infection-induced thymic atrophy. In addition, thymic atrophy was also induced by administration of LPS, the chemotherapeutic drug etoposide and the synthetic glucocorticoid, dexamethasone. Extensive thymic atrophy occurred across the different groups and thymocyte subsets were studied in a comprehensive manner. CD4 and CD8 profile on total thymocytes revealed CD4+CD8+ cells to be the most sensitive across all the modes of thymic atrophy studied. Subsequent detailed analysis of the thymic subpopulations revealed distinct changes during thymic atrophy. The roles of reactive oxygen species (ROS) in modulation of thymocyte subsets in the above mentioned conditions were studied using the ROS quencher, N-acetyl cysteine. We further intend to understand the mechanisms involved in changes occurring in the thymocyte subsets that may aid in development of candidate therapeutic molecules with thymopoietic potential.