Prof. Dr. Thomas Winkler
Nikolaus-Fiebiger-Zentrum für Molekulare Medizin
Evolution of Anti-DNA autoantibodies by somatic hypermutation
The formation of antibodies against double-stranded (ds) DNA is considered to be the serologic hallmark of systemic lupus erythematosus (SLE) and anti-dsDNA antibodies play an important role in the pathogenesis of the disease. We and others have shown that autoantibodies against DNA arise de novo by somatic mutation from non-autoreactive precursors. Therefore, self-tolerance checkpoints at the post-mutational stage of B cell differentiation have to exist that normally prevent the induction of pathogenic anti-dsDNA specificities. In the first funding period, we further characterized our newly generated model for postmutational B cell tolerance. By backcrossing the mice to the Rag-/- background and characterisation of the B cell development in the BCR-knockin mice we could further substantiate our finding that anti-DNA autoantibodies are derived from non-autoreactive precursors. In addition, we proposed that defective clearance of apoptotic cells is crucially involved in the development of autoantibodies against DNA. With the generation and analysis of a mouse deficient for Dnase1l3 we could show that a single genetic defect is sufficient to generate high affinity IgG anti-dsDNA autoantibodies in the C57Bl/6 background. Furthermore, we showed that a viral trigger can induce systemic autoimmunity by excessive Type I interferon signalling.
In the new funding period, we intend to extend our analysis of the germinal center tolerance checkpoint towards susceptibility genes for autoantibody generation, in particular to loss of Dnase1l3. By using our transgenic mouse model in the context of excessive Type I interferon signalling triggered by persistent virus infection, we will dissect the mechanisms that operate to break germinal center tolerance.
B-lymphocytes engaged in a germinal center reaction against foreign antigens gain anti-dsDNA reactivity de novo by somatic hypermutation in the dark zone (A). A phagocytosis defect in the tingible body macrophages (TBM) leads to accumulation of apoptotic and secondary necrotic material that is bound to FDCs within immune complexes (B). Anti-DNA B-cells (red) that accidentally gained anti-dsDNA reactivity are positively selected by chromatin and nucleoprotein-complexes presented on the FDC network. Under certain conditions, TFH cells might provide help for the GC B cells (C) and anti-dsDNA plasma cells as well as memory cells are exiting the germinal center (modified from Schroeder et al., Autoimmunity, 2013).
Steinmetz, T.D., Schlötzer-Schrehardt, U., Hearne, A., Schuh, W., Wittner, J., Schulz, S.R., Winkler, T.H., Jäck, H.-M., and Mielenz, D. (2020). TFG is required for autophagy flux and to prevent endoplasmic reticulum stress in CH12 B lymphoma cells. Autophagy. doi: 10.1080/15548627.2020.1821546.
Weisel, F.J., Mullett, S.J., Elsner, R.A., Menk, A.V., Trivedi, N., Luo, W., Wikenheiser, D., Hawse, W.F., Chikina, M., Smita, S., Conter, L.J., Joachim, S.M., Wendell, S.G., Jurczak, M.J., Winkler, T.H., Delgoffe, G.M. and Shlomchik, M.J. (2020). GC B cells selectively oxidize fatty acids for energy while conducting minimal glycolysis. Nat. Immunol. 21, 331–342.
Cossarizza, A., Chang, H., Radbruch, A., Acs, A., Hauser, A.E., .... Radbruch, H., Warnatz, K., .... Winkler, T.H. et al. (2019). Guidelines for the use of flow cytometry and cell sorting in immunological studies (second edition). Eur. J. Immunol. 49: 1457–1973.
Weisenburger, T., von Neubeck, B., Schneider, A., Ebert, N., Schreyer, D., Acs, A. and Winkler, T.H. (2018). Epistatic Interactions Between Mutations of Deoxyribonuclease 1-Like 3 and the Inhibitory Fc Gamma Receptor IIB Result in Very Early and Massive Autoantibodies Against Double-Stranded DNA. Front. Immunol. 9, 1551. doi:10.3389/fimmu.2018.01551
Greiff, V., Menzel, U., Miho, E., Weber, C., Riedel, R., Cook, S., Valai, A., Lopes, T., Radbruch, A., Winkler, T.H., and Reddy, S.T. (2017). Systems Analysis Reveals High Genetic and Antigen-Driven Predetermination of Antibody Repertoires throughout B Cell Development. Cell Reports 19, 1467-1478.
Rakhymzhan, A., Leben, R., Zimmermann, H., Günther, R., Mex, P., Reismann, D., Ulbricht, C., Acs, A., Brandt, A.U., Lindquist, R.L., Winkler, T.H., Hauser, A.E. and Niesner, R.A. (2017). Synergistic Strategy for Multicolor Two-photon Microscopy: Application to the Analysis of Germinal Center Reactions In Vivo. Sci. Rep. 7, 7101.
Stein, M., Dütting, S., Mougiakakos, D., Bösl, M., Fritsch, K., Reimer, D., Urbanczyk, S., Steinmetz, T., Schuh, W., Bozec, A., Winkler, T.H., Jäck, H., Mielenz, D. (2017). A defined metabolic state in pre B cells governs B-cell development and is counterbalanced by Swiprosin-2/EFhd1 Cell Death & Differentiation 24, 1239-1252
Schmitt, H., Sell, S., Koch, J., Seefried, M., Sonnewald, S., Daniel, C., Winkler, T.H.* and Nitschke, L.* (2016). Siglec-H protects from virus-triggered severe systemic autoimmunity. J. Exp. Med. 213, 1627-44.
* equal contribution
Lutz, J., Dittmann, K., Bosl, M.R., Winkler, T.H., Wienands, J., and Engels, N. (2015). Reactivation of IgG-switched memory B cells by BCR-intrinsic signal amplification promotes IgG antibody production. Nat. Commun. 6, 8575.