Common variable immunodeficiency (CVID) is the most common human primary immunodeficiency. Patients with CVID suffer from recurrent infections and have an increased incidence of autoimmune disorders and lymphoid malignancies. TACI is a receptor for BAFF and APRIL expressed mainly on B cells, and plays an important role in B cell differentiation and antibody production to type II T independent (Tl) antigens. TACI is mutated in a subgroup of patients with CVID. Two missense mutations, C104R in the extracellular domain, which disrupts ligand binding, and A181E in the transmembrane domain, which abolishes signaling, account for the majority of TACI mutations in CVID. Most CVID patients with these two mutations are heterozygous. The central theme of this project is to establish the functional relevance of TACI mutations observed in CVID. Our preliminary data suggests that TACI oligomerizes on the cell surface and that TACI ligation synergizes with CD40 and TLRs to cause B cell differentiation. Preliminary data in TACI+/"""""""" mice that express mutant TACI transgenes support haploinsufficiency as the mechanism of action of the C104R mutation, and suggest that the A181Emutation could exert a dominant negative (DN) effect Our overall hypothesis is that heterozygous TACI mutations found in CVID impair TACI function because of haploinsufficiency or a DN effect and that these mutations contribute together with defects in other pathways of B cell activation to the development of CVID. To test this hypothesis we propose to: 1. Examine whether ligand-independent ligand TACI oligomerization is required for subsequent ligand induced signaling, map the domain(s) that mediates the assembly of hTACI and probe the function of the short and long isoforms of hTACI. 2. Analyze whether the A181E TACI mutant exerts a DN effect in vitro in transfectants and patient B cells, and in vivo in knock-in mice. 3. Determine the effect of TACI mutations on its synergy with CD40 and TLRs in vitro and in vivo in TACI mutant mice, and investigate whether TACI mutations cooperate with mutations in the CD40 and TLR4 pathways to severely impair B cell function as observed in CVID. The studies proposed will help us understand the molecular mechanisms by which TACI mutations may contribute to B cell dysfunction in CVID. They are also critical for understanding the etiology of CVID and its complications (autoimmunity and lymphoma) and for devising novel therapies for affected patients.
(Seeinstructions): Common variable immunodeficiency (CVID) is the most common primary immunodeficiency in humans. Patients with CVID suffer from recurrent infections and have an increased incidence of autoimmune disorders and lymphoid malignancies. The studies proposed are critical for understanding the etiology of CVID and of its complications (autoimmunity and lymphoma) and for devising novel therapies for affected patients.
|Hoyos-Bachiloglu, Rodrigo; Chou, Janet; Sodroski, Catherine N et al. (2017) A digenic human immunodeficiency characterized by IFNAR1 and IFNGR2 mutations. J Clin Invest 127:4415-4420|
|Jabara, Haifa H; Lee, John J; Janssen, Erin et al. (2017) Heterozygosity for transmembrane activator and calcium modulator ligand interactor A144E causes haploinsufficiency and pneumococcal susceptibility in mice. J Allergy Clin Immunol 139:1293-1301.e4|
|Xing, Mengtan; Bjørås, Magnar; Daniel, Jeremy A et al. (2017) Synthetic lethality between murine DNA repair factors XLF and DNA-PKcs is rescued by inactivation of Ku70. DNA Repair (Amst) 57:133-138|
|Yee, Christina S; Massaad, Michel J; Bainter, Wayne et al. (2016) Recurrent viral infections associated with a homozygous CORO1A mutation that disrupts oligomerization and cytoskeletal association. J Allergy Clin Immunol 137:879-88.e2|
|Badran, Yousef R; Massaad, Michel J; Bainter, Wayne et al. (2016) Combined immunodeficiency due to a homozygous mutation in ORAI1 that deletes the C-terminus that interacts with STIM 1. Clin Immunol 166-167:100-2|
|Jabara, Haifa H; Boyden, Steven E; Chou, Janet et al. (2016) A missense mutation in TFRC, encoding transferrin receptor 1, causes combined immunodeficiency. Nat Genet 48:74-8|
|Felgentreff, Kerstin; Lee, Yu Nee; Frugoni, Francesco et al. (2015) Functional analysis of naturally occurring DCLRE1C mutations and correlation with the clinical phenotype of ARTEMIS deficiency. J Allergy Clin Immunol 136:140-150.e7|
|Buchbinder, David; Baker, Rebecca; Lee, Yu Nee et al. (2015) Identification of patients with RAG mutations previously diagnosed with common variable immunodeficiency disorders. J Clin Immunol 35:119-24|
|Chou, Janet; Badran, Yousef R; Yee, Christina S K et al. (2015) A novel mutation in ORAI1 presenting with combined immunodeficiency and residual T-cell function. J Allergy Clin Immunol 136:479-482.e1|
|Boisson, Bertrand; Laplantine, Emmanuel; Dobbs, Kerry et al. (2015) Human HOIP and LUBAC deficiency underlies autoinflammation, immunodeficiency, amylopectinosis, and lymphangiectasia. J Exp Med 212:939-51|
Showing the most recent 10 out of 60 publications