Methyldopa blocks MHC class II binding to disease-specific antigens in autoimmune diabetes
David A. Ostrov, … , Peter A. Gottlieb, Aaron W. Michels
David A. Ostrov, … , Peter A. Gottlieb, Aaron W. Michels
Published February 13, 2018
Citation Information: J Clin Invest. 2018;128(5):1888-1902. https://doi.org/10.1172/JCI97739.
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Research Article Autoimmunity Endocrinology

Methyldopa blocks MHC class II binding to disease-specific antigens in autoimmune diabetes

Abstract

Major histocompatibility (MHC) class II molecules are strongly associated with many autoimmune disorders. In type 1 diabetes (T1D), the DQ8 molecule is common, confers significant disease risk, and is involved in disease pathogenesis. We hypothesized that blocking DQ8 antigen presentation would provide therapeutic benefit by preventing recognition of self-peptides by pathogenic T cells. We used the crystal structure of DQ8 to select drug-like small molecules predicted to bind structural pockets in the MHC antigen–binding cleft. A limited number of the predicted compounds inhibited DQ8 antigen presentation in vitro, with 1 compound preventing insulin autoantibody production and delaying diabetes onset in an animal model of spontaneous autoimmune diabetes. An existing drug with a similar structure, methyldopa, specifically blocked DQ8 in patients with recent-onset T1D and reduced inflammatory T cell responses to insulin, highlighting the relevance of blocking disease-specific MHC class II antigen presentation to treat autoimmunity.

Authors

David A. Ostrov, Aimon Alkanani, Kristen A. McDaniel, Stephanie Case, Erin E. Baschal, Laura Pyle, Sam Ellis, Bernadette Pöllinger, Katherine J. Seidl, Viral N. Shah, Satish K. Garg, Mark A. Atkinson, Peter A. Gottlieb, Aaron W. Michels

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Figure 2

TATD blocks DQ8-restricted T cell responses and prevents diabetes in NOD mice.

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TATD blocks DQ8-restricted T cell responses and prevents diabetes in NOD...
(A) Chemical structure of TATD. (B) TATD blocked an in vitro DQ8–restricted T cell response to insulin B:13-23 (Clone 5) and deamidated α-gliadin228-240 (489 TCR). Data represent the mean ± SEM and are representative of 3 independent experiments. No antigen addition to the culture resulted in IL-2 levels below 3 pg/ml. (C) TATD was cultured with recombinant α-gliadin/DQ8 protein and free peptide in conditions to allow peptide exchange. After washing, the recombinant protein was used to stimulate 489, and IL-2 secretion was measured. Data are from triplicate wells and are representative of 3 independent experiments. 489 in culture without protein resulted in IL-2 levels below 3 pg/ml. (D) Female NOD mice were treated from 4 to 12 weeks of age with 20 mg/kg TATD (n = 10) or PBS (n = 13) by intraperitoneal injection daily for 5 days each week. P = 0.006, by log-rank test. (E) Peak serum insulin autoantibody (IAA) levels were measured using a fluid-phase RIA during the 40-week prevention study. **P = 0.003, by Mann-Whitney U test. The dotted line at 0.01 indicates a positive value. (F) Blood glucose levels during the late prevention study, in which female NOD mice were treated with 30 mg/kg TATD orally each day (n = 9), 50 μg anti-CD3 monoclonal antibody intraperitoneally for 5 consecutive days (n = 10), or PBS (n = 10) beginning at 12 weeks of age and ending at 25 weeks. Data represent the mean ± SEM. *P < 0.05, by ANOVA for comparison of TATD versus PBS. (G) Intraperitoneal GTT following cessation of the study treatments; each dot represents an individual mouse. ***P < 0.01, by 2-tailed, unpaired t test. (H) Representative H&E-stained pancreatic sections from PBS- and TATD-treated mice; insulin staining is shown in brown. Original magnification, ×15. (I) Insulitis scoring from at least 100 separate islets from TATD-treated (n = 3) and PBS-treated (n = 5) mice.