Dysregulated autophagy in Lymphocytes hints at contribution to immune-mediated thrombotic thrombocytopenic purpura (iTTP)

Abstract Immune-mediated TTP is a life-threatening autoimmune disorder characterized by abundant occlusion of the microcirculation. iTTP is caused by a severe autoantibody-mediated deficiency of the von Willebrand factor cleaving protease, ADAMTS-13. Previously, we demonstrated dendritic cells from iTTP patients to have a distinct expression profile of autophagy (ATG)-related genes in 1 relapsing iTTP patient. Contribution of autophagy to the maintenance of autoimmune lymphocytes is crucial to understand the disease pathogenesis of this rare disease. The autophagy expression profile of purified B- and T-cells isolated from whole blood of iTTP patients or splenocytes using magnetic negative isolation, in the acute or remission phase will be compared to lymphocytes from healthy controls. We choose a panel of nine essential ATG genes (Beclin-1, Atg5, Atg7, Atg14, WIPI1, ULK1, MTOR, NRB1, and WDR45) implicated in other autoimmune diseases to assess a basal level of autophagy by qPCR, autophagic flux (LC3 and p62 expression) will be measured by immunofluorescense. Additionally to discriminate autophagy levels during the acute and relapse phase in relapsing or single episode iTTP patients we will use ImageStream technique. Preliminary immunofluorescence data from healthy donors indicate that B-lymphocytes show elevated autophagy thanT lymphocytes. These findings are in line with a fact that autophagy participates in antigen presentation and hence may be increased in cells which have antigen presenting function. Our study will help to shed light on the development and maintenance of iTTP and paves the road to design new treatment strategies based on aberrantly expressed ATG genes by blocking/activating respective autophagy pathways.