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.
View: Text | PDF
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

×

Figure 3

Methyldopa blocks DQ8 antigen presentation in vitro.

Options: View larger image (or click on image) Download as PowerPoint
Methyldopa blocks DQ8 antigen presentation in vitro. (A) Methyldopa chem...
(A) Methyldopa chemical structure. Methyldopa blocked an in vitro DQ8–restricted T cell response by (B) clone 5 to insulin B:13-23 and (C) TCR 489 to deamidated α-gliadin presented by DQ8. The negative controls (no antigen added to culture) resulted in IL-2 levels below 3 pg/ml. (D) Methyldopa specifically inhibited 489, a DQ8-restricted T cell response, while not altering C7CH17, a DR4-restricted T cell response to the HA peptide HA306-318. Cells from an EBV-transformed B cell line homozygous for DQ8 and DR4 were used as APCs in this experiment, such that each APC had DQ8 and DR4 on the cell surface. (E) Methyldopa did not inhibit a DQ8-restricted T cell response to the influenza peptide HA102-118. (B–E) Data represent the mean ± SEM and are representative of 3 independent experiments. (F) Representative isothermal titration calorimetric data for titration of methyldopa into DQ8 protein. Top: Heat released as a function of time from 2-μl injections of 4 mM methyldopa titrated into the sample cell containing 4 μM DQ8 protein at 25oC. Bottom: Fitted binding curve along with the measured thermodynamic parameters and the calculated KD from 3 independent experiments, reported as the mean ± SEM. (G) Molecular docking model of methyldopa in the DQ8 antigen–binding cleft shows potential H bonds between a methyldopa hydroxyl group and DQα62 asparagine (DQα N62) on the DQα-helix and between the methyldopa carboxylic acid and DQβ30 tyrosine (DQβ Y30) on the floor of the cleft.