The long-term objective of this proposal is to determine the mechanism of autoreactive B cells in systemic lupus erythematosus. The present interest in anti-B cell therapy for systemic lupus erythematosus (SLE) and other diseases underscores its importance. The overarching hypothesis is that anti-self B cells of different subsets in SLE are activated by different mechanisms and pre-programmed to have unique roles in pathogenic anti-self responses. We will focus our efforts on the mechanism of activation of B cell specific for the Smith (Sm) antigen, a ribonucleoprotein commonly targeted in SLE. Our previous work indicates that anti-Sm B cells of the follicular (FO) B cell subset are non-functional, but, paradoxically, also indicates that some anti-Sm B cells are selected into the marginal zone (MZ), pre-plasma, and B-1 cell subsets, and are functional. The distinct phenotypes, activation states, and anatomical locations of B cells of each subset are designed to provide a layered and interdependent, protective response to foreign antigens. However, we know little about the interplay between the B cells of these subsets in responses to self-antigen, but preliminary data indicates that they make unique contributions to the anti-Sm response in autoimmunity with implications for pathogenesis. We also find that dendritic cells (DCs) activate anti-Sm MZ B cells, but normally this ability is carefully regulated to prevent concurrent T cell activation. However, in autoimmunity, a deficiency in the activation receptor Fas, allows anti-Sm B cell activation concurrently with T cells, with the potential to generate pathogenic antibodies. We propose three aims to determine the role of B cells of each subset to autoimmunity and the mechanism of anti-Sm B cell activation by DCs. In the first aim, we will determine the contributions and interdependence of B cells of each subset the anti-Sm responses in autoimmune mice. In the second aim, we propose to determine the mechanism of anti-Sm B cell activation by normal and Fas-deficient DCs, and in the final aim, we will determine how Fas regulates the ability of DCs to activate anti-Sm B cells. The proposed experiments will aid in the identification of new therapeutic targets that affect pathogenic mechanisms for B cell activation.

Public Health Relevance

Antibodies specific for self-proteins cause many autoimmune diseases, including systemic lupus erythematosus. How B-lymphocytes that produce these pathogenic anti-self antibodies are activated is largely unknown. In this proposal, we will determine how these B-lymphocytes are activated for the purpose of identifying mechanisms that can be therapeutically targeted in patients with these diseases.

National Institute of Health (NIH)
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Research Project (R01)
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Hypersensitivity, Autoimmune, and Immune-mediated Diseases Study Section (HAI)
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Mancini, Marie
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University of North Carolina Chapel Hill
Schools of Medicine
Chapel Hill
United States
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