LYN- and AIRE-mediated tolerance checkpoint defects synergize to trigger organ-specific autoimmunity
Irina Proekt, … , Mark S. Anderson, Anthony L. DeFranco
Irina Proekt, … , Mark S. Anderson, Anthony L. DeFranco
Published August 29, 2016
Citation Information: J Clin Invest. 2016;126(10):3758-3771. https://doi.org/10.1172/JCI84440.
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Research Article Autoimmunity

LYN- and AIRE-mediated tolerance checkpoint defects synergize to trigger organ-specific autoimmunity

Abstract

Studies of the genetic factors associated with human autoimmune disease suggest a multigenic origin of susceptibility; however, how these factors interact and through which tolerance pathways they operate generally remain to be defined. One key checkpoint occurs through the activity of the autoimmune regulator AIRE, which promotes central T cell tolerance. Recent reports have described a variety of dominant-negative AIRE mutations that likely contribute to human autoimmunity to a greater extent than previously thought. In families with these mutations, the penetrance of autoimmunity is incomplete, suggesting that other checkpoints play a role in preventing autoimmunity. Here, we tested whether a defect in LYN, an inhibitory protein tyrosine kinase that is implicated in systemic autoimmunity, could combine with an Aire mutation to provoke organ-specific autoimmunity. Indeed, mice with a dominant-negative allele of Aire and deficiency in LYN spontaneously developed organ-specific autoimmunity in the eye. We further determined that a small pool of retinal protein–specific T cells escaped thymic deletion as a result of the hypomorphic Aire function and that these cells also escaped peripheral tolerance in the presence of LYN-deficient dendritic cells, leading to highly destructive autoimmune attack. These findings demonstrate how 2 distinct tolerance pathways can synergize to unleash autoimmunity and have implications for the genetic susceptibility of autoimmune disease.

Authors

Irina Proekt, Corey N. Miller, Marion Jeanne, Kayla J. Fasano, James J. Moon, Clifford A. Lowell, Douglas B. Gould, Mark S. Anderson, Anthony L. DeFranco

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Figure 3

Activated IRBP-specific T cells infiltrate the retinas of AireGW/+ Lyn–/– mice with uveitis.

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Activated IRBP-specific T cells infiltrate the retinas of AireGW/+ Lyn–/...
(A) Immunostaining of retinas from AireGW/+ Lyn–/– mice showing infiltration of TCRβ+ T cells (red) in mice with uveitis (original magnification, ×40; scale bars: 50 μm). Data are representative of 2 independent experiments. (B–E) Analysis of total and IRBP-specific T cells in mice with uveitis. Plots are representative of 3 independent experiments with n = 3–5 mice per group; numbers shown indicate percentage of cells in gate. Graphs show data pooled from 3 independent experiments; each dot represents an individual mouse; bars represent mean. (B) CD45 and TCRβ expression on total live retinal cells. (C) CD4 and CD8 expression on CD45+TCRβ+ retinal T cells (left), and numbers of these cells in the retinas of mice of indicated ages (right). (D) CD44 expression on CD4+ and CD8+ T cells from indicated tissue. LN, lymph node. (E) Left: Frequency of retinal P2 tetramer–specific CD4+ T cells from mice in C. Right: Numbers of P2-specific cells in indicated tissue. Dashed line represents the limit of detection. (F) Anti-IRBP antibodies in the serum of AireGW/+ Lyn–/– mice with uveitis analyzed longitudinally. Dashed line represents the limit of detection. (G) Mice with active uveitis were analyzed for the presence of CD4+ T cells binding either P2 and IRBP 651–670 (“IRBP 651”; top) or P2 and P7 (bottom) epitopes of IRBP in the indicated tissue. Plots show representative costaining; numbers indicate percentage of cells in gate, quantified on the right. Each dot represents an individual mouse; bars show mean. Dashed line represents the limit of detection for the P2 tetramer; dotted line represents the limit of detection for the IRBP 651 (top) or P7 (bottom) tetramer. Data are pooled from 2 independent experiments. *P < 0.05, **P < 0.01, Mann-Whitney test (C, E, and G).