Scientific Report 2005

Immunology

Structure-Function Studies of Innate and Adaptive Immunity

L. Teyton, B. Atteberry, K. Bennett, H. Burt, C. Cantu, S. Chabot, S.Y. Chang, W. Cheung, S. Freigang, H. Issafras, C. Li, N. Schrantz, J. Sim, R. Stefanko, C. Wang, K. Yoshida

ACTIVATION OF T-CELL RECEPTORS

Our goal is to understand the molecular switches that lead to activation of T cells. Assembly of functional complexes of T-cell receptors (TCRs) on artificial bilayers with recombinant forms of TCRαβ, CD3δε, CD3γε, and CD8αβ is in progress. We use a combination of single-molecule, multicolor imaging by total internal reflection fluorescence microscopy, in collaboration with K. Fish, Molecular and Integrative Neurosciences Department, and electron microscopy to examine the dynamics and membrane relationships of each subunit within the complex. Similar observations are carried out in the presence of MHC ligands displayed in solution or at the surface of polystyrene beads and liposomes.

Interactions of MHC and TCR molecules with their respective membranes could provide simple switches essential to T-cell activation. This hypothesis is supported by our structure determination, in collaboration A.K. Mitra, University of Auckland, Auckland, New Zealand, of the structure of an MHC molecule attached to a phospholipid bilayer that shows parallel orientation of the long axis of the molecule with the lipid leaflet. In collaboration with I.A. Wilson, Department of Molecular Biology, we are determining 3-dimensional structures of CD3, TCR complexes and CD8αβ.

Autoimmune Diabetes

We are using MHC multimers to detect antigen-specific T-cell populations in nonobese diabetic mice. Pathogenic T cells are characterized by analyzing secretion of cytokines and use of TCRs by single cells. We are also trying to treat insulin-dependent diabetes by depleting antigen-specific T cells in vivo during the preclinical phase of the disease. For this therapy, we are using MHC molecules to deliver doxorubicin liposomes to autoreactive T cells. The specificity of the intervention will limit the side effects and complications of general immunosuppression.

Link between Innate and Adaptive Immunity

We are studying lipid binding to CD1 to determine the factors that govern the presentation of the lipids to T cells. A family of lipid transfer proteins known as saposins, which are involved in the catabolism of lipids, are critical for the loading of natural glycolipids onto CD1 and the selection of natural killer T cells. Other lipid transfer proteins most likely account for the loading of other exogenous ligands. In collaboration with A. Bendelac, University of Chicago, we are using RNA interference, genetic techniques, and recombinant biochemistry to study CD1 within the context of lipid metabolism.

Innate Immune Receptors

Recognition of unique features of the prokaryotic world is embedded in a series of receptors of the innate immune system called pattern recognition molecules. Each of these receptors can sense the presence of a family of unique prokaryotic compounds such as glycolipids, proteoglycans, DNA, or RNA and allow activation of macrophages, dendritic cells, and neutrophils. We are collaborating with R. Ulevitch and P. Tobias, Department of Immunology, to decipher the structural basis of this mode of recognition. We expressed recombinant forms of receptor family members from Drosophila, mice, and humans to compare the biophysical and structural characteristics of the receptors and to delineate new activation pathways.

Publications

Goff, R.D., Gao, Y., Mattner, J., Zhou, D., Yin, N., Cantu, C. III, Teyton, L., Bendelac, A., Savage, P.B. Effects of lipid chain lengths in α-galactosylceramides on cytokine release by natural killer T cells. J. Am. Chem. Soc. 126:13602, 2004.

Kelker, M.S., Foss, T.R., Peti, W., Teyton, L., Kelly, J.W., Wuthrich, K., Wilson, I.A. Crystal structure of human triggering receptor expressed on myeloid cells 1 (TREM-1) at 1.47 Å. J. Mol. Biol. 342:1237, 2004.

Malherbe, L., Hausl, C., Teyton, L., McHeyzer-Williams, M.G. Clonal selection of helper T cells is determined by an affinity threshold with no further skewing of TCR binding properties. Immunity 21:669, 2004.

Mattner, J., Debord, K.L., Ismail, N., Goff, R.D., Cantu, C. III, Zhou, D., Saint-Mezard, P., Wang, V., Gao, Y., Yin, N., Hoebe, K., Schneewind, O., Walker, D., Beutler, B., Teyton, L., Savage, P.B., Bendelac, A. Exogenous and endogenous glycolipid antigens activate NKT cells during microbial infections. Nature 434:525, 2005.

Ranheim, E.A., Tarbell, K.V., Krogsgaard, M., Mallet-Designe, V., Teyton, L., McDevitt, H.O., Weissman, I.L. Selection of aberrant class II restricted CD8⁺ T cells in NOD mice expressing a glutamic acid decarboxylase (GAD)65-specific T cell receptor transgene. Autoimmunity 37:555, 2004.

Reiser, J.B., Teyton, L., Wilson, I.A. Crystal structure of the Drosophila peptidoglycan recognition protein (PGRP)-SA at 1.56 Å resolution. J. Mol. Biol. 340:909, 2004.

Robey, I.F., Peterson, M., Horwitz, M.S., Kono, D.H., Stratmann, T., Theofilopoulos, A.N., Sarvetnick, N., Teyton, L., Feeney, A.J. Terminal deoxynucleotidyltransferase deficiency decreases autoimmune disease in diabetes-prone nonobese diabetic mice and lupus-prone MRL-Fas^lpr mice. J. Immunol. 172:4624, 2004.

Zhou, D., Mattner, J., Cantu, C. III, Schrantz, N., Yin, N., Gao, Y., Sagiv, Y., Hudspeth, K., Wu, Y.P., Yamashita, T., Teneberg, S., Wang, D., Proia, R.L., Levery, S.B., Savage, P.B., Teyton, L., Bendelac, A. Lysosomal glycosphingolipid recognition by NKT cells. Science 306:1786, 2004.