The acquisition of new distinct autoreactivities, epitope spreading, is thought to be driven by chronic immune responses causing inclusion of new autoreactive B cell clones, but the underlying mechanisms involved are ill understood.
The Researcher utilized the 564Igi mouse as a murine model of SLE, which is generated by knock-in of a B cell receptor of an autoreactive B-cell clone. We have previously shown (S.Degn et al. Cell 2017) in a mixed bone marrow chimera model that we can induce and reproduce the spontaneous development of self-reactive B cells from the WT-repertoire (epitope spreading). Once tolerance was broken, WT B-cells acquired new targets of auto-reactivity and became independent of the initial trigger, although still dependent on T cell stimulation.
The Researcher now further progresses on these findings and specifically addresses the requirements needed to start and maintain epitope spreading. In this project, the Researcher was able to show that naïve wild-type (WT) B cells induce epitope spreading by active entry, participation and differentiation in pre-existing autoreactive germinal centers (aGC). Entry of the WT B cell into the aGC is an active process that depends on primary signals via antigen presentation and recognition as well as secondary signals via Toll-like receptor 7 and Interferon alpha, among others. Moreover, entered WT B cells clonally evolved towards dominance of individual clonal lineages, persisted for extended periods and differentiated into autoantibody producing plasma cells. Collectively, the Researcher has setup a new model for epitope spreading that identified a distinct mechanistic insight of the initial phase of epitope spreading and that could have clinical implications for developing targets for early immunotherapeutic strategies.
These results have been presented at (inter)national conferences and is currently submitted for publication.
