Mechanistic elucidation of pathogenic CBM complex mutations associated with atopic disease

PROJECT ABSTRACT The study of primary atopic disorders (PADs) has provided important and surprising knowledge about specific genes that control the function of white blood cells involved in driving allergic responses. Over the last several years, our groups have played a leading role in the discovery and characterization of human immune disorders linked to mutations in CARD11, which encodes a critical signaling protein in lymphocytes. CARD11 partners with two other proteins (BCL10 and MALT1) to form the “CBM complex”, which communicates key signals that dictate lymphocyte activation, differentiation and function. Most recently, we described numerous patients with severe eczema, asthma/food allergies, and skin/respiratory infections that carried debilitating CARD11 mutations that disrupt normal CBM function. These variants attenuate CBM signaling in patient lymphocytes and cause them to differentiate abnormally into effector cells associated with allergy/atopy. The long-term objective of this project is to precisely define which cell signaling processes are disrupted by mutations in CBM complex genes, and elucidate how these defects adversely affect B and T cell function to ultimately manifest as in atopy, including assessment of glutamine as a potential treatment strategy. We will also define the broader scope and burden of pathogenic CBM complex mutations that influence atopic predisposition in both rare PADs and common cohorts of allergy disease patients. Built upon an extensive panel of atopy-associated, damaging mutations spanning the CARD11 gene, and extending to other CBM gene mutations identified from allergic patient cohorts, our studies will better define how these mutations disrupt normal CBM-dependent signaling pathways in lymphocytes. Using well- established cell transfection systems AND primary murine and patient cells, we will elucidate the molecular and cellular mechanisms through which impaired CARD11 signaling drives the preferential production of allergy- associated cytokines and IgE. Based on compelling preliminary data, our analyses will pinpoint specific biochemical and metabolic pathways that are disrupted by defective CARD11 signaling directly in primary cells from affected patients, an invaluable resource that we have unique access to. Defining these molecular abnormalities will enhance our understanding of disease pathogenesis and illuminate mechanisms by which simple interventions, such as supplementation with the essential amino acid glutamine, can restore the proper function of T and B cells harboring CBM mutations. Our innovative approach has the potential to significantly revise our understanding of how the CBM complex regulates adaptive immune responses. Insights gleaned from a more thorough investigation of CBM gene mutations, derived from both rare and common allergy patient cohorts, will better define their contribution to atopic susceptibility and inform new targeted therapeutic approaches for treating a broader spectrum of patients suffering from allergic disease.