Proper B cell tolerance ensures effective censoring of autoreactive B cells thereby avoiding their participation in effector pathogenic response and preventing autoimmune diseases. The breakdown of B cell tolerance is at the core Systemic Lupus Erythematosus and may in fact, represent the initiating step in the cascade of pathogenic events leading to clinical disease. While B cell tolerance is relatively well understood in transgenic mouse models, human B cell tolerance remains poorly understood due to the lack of informative systems and inherent experimental limitations. To remedy these problems, we have concentrated over the last few years in the study of autoreactive 9G4 B cells, which represent an abundant and homogeneous population of autoreactive B cells that are strictly censored in healthy subjects but not in SLE. Our results demonstrate that normal censoring of 9G4 cells is achieved through a combination of mechanisms including germinal center (GC) exclusion, anergy and positive selection into the marginal zone compartment due at least in part to receptor editing. We have also demonstrated that SLE 9G4 cells are expanded in newly identified effector B cell populations in patients with active disease, presumably reflecting the malfunction of GC and late checkpoints. This application will provide a detailed understanding of human B cell tolerance and its breakdown in SLE by pursuing the following Aims: 1) To elucidate the role of receptor editing and antigen selection in human B cell tolerance;2) To understand antigen-driven selection of effector autoimmune B cells in SLE. The expected information will substantially advance our understanding of the regulation of autoreactive B cells while also identifying B cell markers and autoimmune specificities with great potential as biomarkers, diagnostic and therapeutic targets.

Public Health Relevance

Autoimmune diseases like SLE are triggered by lack of regulation of cells that recognize our own antigens. Understanding the regulation of these cells (called autoreactive B cells) will be of great importance for the diagnosis of treatment of multiple autoimmune diseases also including Rheumatoid Arthritis and Diabetes. We will use a well-recognized subset of human autoreactive B cells (termed 9G4) that are specifically defective in patients with SLE. Using molecular and cellular approaches, we will elucidate the mechanisms, antigens and precise points of deregulation of these cells.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37AI049660-07
Application #
8016628
Study Section
Transplantation, Tolerance, and Tumor Immunology (TTT)
Program Officer
Johnson, David R
Project Start
2001-04-01
Project End
2015-01-31
Budget Start
2011-02-11
Budget End
2012-01-31
Support Year
7
Fiscal Year
2011
Total Cost
$380,840
Indirect Cost
Name
University of Rochester
Department
Internal Medicine/Medicine
Type
Schools of Dentistry
DUNS #
041294109
City
Rochester
State
NY
Country
United States
Zip Code
14627
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