Dipankar Nandi
Indian Institute of Science, India
Title: Investigations on sub-populations of thymocytes during atrophy
Biography
Biography: Dipankar Nandi
Abstract
T cells are critical for cell-mediated immunity and these cells are generated in the thymus. The thymus is a primary lymphoid organ in which T cells differentiate and mature. Upon stringent selection, only mature T cells egress into the periphery and are responsible for cellular immunity. There are four major sub-populations of thymocytes based on expression of CD4 and CD8 markers: CD4-CD8- or double negative, CD4+CD8+ or double positive, CD4+ single positive and CD8+ single positive cells. Thymic atrophy, i.e. the loss in the number of thymocytes, occurs during aging, stress and infections. Indeed, thymic atrophy is also observed upon infection with viruses, bacteria, fungi etc.; however, the reasons and consequences of thymic atrophy are not well understood. To better understand the molecular and cellular processes involved during thymic atrophy, we standardized a model of infection-induced thymic atrophy using the intracellular bacterial pathogen, Salmonella typhimurium. During oral infection of C57BL/6 mice by Salmonella typhimurium the number of immature CD4-CD8- and CD4+CD8+ thymocytes, but not single positive and mature CD4+ or CD8+ thymocytes or mesenteric lymph node cells, were greatly reduced. In this presentation, I will outline some of our recent work regarding the subsets that are affected during thymic atrophy during Salmonella typhimurium infection. In addition, we are studying thymic sob-populations in other modes of atrophy, i.e. caused by lipopolysaccharide (LPS), etoposide which is an anti-cancer compound and dexamethasone, a synthetic glucocorticoid. Preliminary data on differences in thymic sub-populations in different modes of thymic atrophy and possible mechanistic insights will be presented. Better understanding of the processes involved in thymic atrophy may lead to the development strategies that may boost the cellular response during stress, infections, treatments with anti-cancer drugs etc.