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Eric Meffre, PhD

Associate Professor Adjunct
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Associate Professor Adjunct

Biography

My work focuses on the etiology of autoimmune diseases affecting millions of individuals in the world by identifying molecules and pathways involved in the establishment of B-cell tolerance through the investigation of rare patients with primary immunodeficiency (PID), enrolled at Yale and through an international network.

Patients with PID provide opportunities to study the impact of specific gene defects on the regulation of B-cell tolerance and the removal of developing autoreactive B cells in humans. Using a RT-PCR based strategy that allows us to assess the frequency of autoreactive B cells, we found that alterations in B-cell receptor (BCR) signaling in patients lacking functional BTK or CD19, or mutations in molecules mediating TLR signaling such as TACI, IRAK4, MyD88 as well as in adenosine deaminase (ADA) and activation-induced cytidine deaminase (AID) all result in a defective central checkpoint and a failure to counterselect developing autoreactive B cells in the bone marrow. Interestingly, successful gene therapy in ADA-deficient patients results in the restoration of early B-cell tolerance checkpoints, revealing that appropriate regiments could correct B-cell selection impairments characteristic of many patients with autoimmune conditions. Our investigations also revealed that central B-cell tolerance defects are primary to many autoimmune diseases including rheumatoid arthritis, type 1 diabetes and systemic lupus erythematosus and can result from genetic polymorphisms such as the R620W PTPN22 risk allele associated with all these diseases and that was reported to alter BCR signaling important for the regulation of this checkpoint.

In contrast, most patients with multiple sclerosis only suffer from specific defects of their peripheral B-cell tolerance checkpoint that likely result from abnormal regulatory T cells, which normally control this second B-cell selection step in the periphery. Regardless of which early B-cell tolerance checkpoint is defective in patients with autoimmune diseases, all these patients are characterized by the accumulation of autoreactive clones in their mature naïve B cell compartment, which may contribute to the development of autoimmunity by increasing the frequency of B cells presenting self-antigens. Understanding the etiology of autoimmunity is the first step toward effective treatment, therapy and ultimately, cure.

Appointments

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Education & Training

PhD
University of Aix-Marseille (1996)
MS
University of Paris (1989)
BS
University of Paris (1988)

Research

Overview

Autoantibody production is a characteristic of most autoimmune diseases including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and type 1 diabetes (T1D). These autoantibodies appear in the serum many years before the onset of clinical disease suggesting an early break in B cell tolerance. We previously established in healthy donors that random V(D)J recombination produce large numbers of autoreactive antibodies. Most developing B cells that express polyreactive antibodies or B cell receptors (BCRs) are silenced in the bone marrow, and additional autoreactive B cells are removed in the periphery. We recently analyzed B cell tolerance in RA patients by testing the specificity of recombinant antibodies cloned from single B cells. RA patients exhibit defective central and peripheral B cell tolerance checkpoints that result in the accumulation of self-reactive mature naïve B cells, likely contributing to the pathogenesis of this disease. Yet the mechanisms that lead to the generation and survival of these autoreactive mature naïve B cells in RA patients are unknown.

Defects in BCR signaling have been reported in B cells from SLE patients who also suffer from defective central and peripheral B cell tolerance checkpoints, suggesting that BCR signaling may play an important role in counterselecting self-reactive B cells. By studying X-linked agammaglobulinemia (XLA) patients who carry mutations in the BTK gene that encodes an essential BCR signaling component, we demonstrated that Btk and therefore BCR signaling is essential in regulating thresholds for human central B cell tolerance. In addition, developing anti-nuclear B cells from IRAK-4- and MyD88-deficient patients failed to be counterselected and demonstrated an essential role for Toll-like receptors in the establishment of human B cell tolerance. Moreover, we recently reported that CD40ligand (CD40L)-and MHC class II-deficient patients who accumulated autoreactive B cells in their mature B cell compartment displayed decreased numbers of regulatory (Treg) and NK T cells in their blood suggesting that these cells may be involved in the establishment of peripheral B cell tolerance in humans.

The long range goal of our research is to further elucidate the mechanisms, molecules and cells that regulate B cell tolerance in healthy humans and that are altered in patients with autoimmune diseases. The working hypothesis is that B cells from RA, SLE and potentially T1D patients suffer from intrinsic signaling defects that result in a central failure to remove autoreactive B cells. In addition, alterations in T cell/dendritic cell functions may affect the counterselection of autoreactive B cells in the periphery. We are currently studying B cell tolerance in patients with CD19, TACI, ICOS, Fas, AID, uracil-DNA glycosylase (UNG) gene defects to identify new pathways and molecules required for the establishment of B cell tolerance. The role of NKT and Treg cells on peripheral B cell tolerance is currently being assessed by analyzing B cell tolerance checkpoints in two primary immunodeficiencies, XLP and IPEX. XLP patients suffer from defective SAP (SLAM associated protein) gene and display normal Treg cells but no NKT cells whereas IPEX patients suffer from Foxp3-deficiency in which no functional Treg cells develop resulting in severe autoimmune manifestations.

Finally, we aim to characterize gene expression profiles using Affimetrix gene chips in unstimulated and BCR-stimulated RA and T1D B cells and compare them to those from healthy donor B cells to potentially identify defective pathways through genes that would fail to be properly regulated.

Medical Subject Headings (MeSH)

Arthritis, Rheumatoid; Autoimmune Diseases; Diabetes Mellitus, Type 1; Immune System; Lupus Erythematosus, Systemic

Publications

2024

2023

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