Abstract
Many autoimmune diseases are characterized by germinal center (GC) derived affinity-matured, class-switched autoantibodies. Strategies to block GC formation and progression are currently being explored clinically, however, extrafollicular responses may also contribute to early events in autoimmunity. To investigate the relative contribution of these two pathways in autoimmune disease development, we leveraged a transgenic strategy to genetically block the GC pathway. Surprisingly, this accelerated extrafollicular responses and failed to curb autoimmune progression in two lupus models. In vitro, loss of the GC transcription factor Bcl-6 prevented cellular expansion and accelerated plasma cell differentiation, suggesting the in vivo phenotype was caused by rewiring of B cell intrinsic transcriptional programming. In a competitive scenario in vivo, B cells harboring the genetic GC block contributed disproportionately to the plasma cell output. Taken together, this emphasizes the extrafollicular pathway as a key contributor to autoimmune progression, and suggests that strategies aimed at blocking GCs should simultaneously target this pathway to avoid rerouting the pathogenic response.
Highlights
- A genetic GC block fails to prevent autoimmune progression in two lupus models
- An intrinsic GC block drives B cell differentiation into terminally differentiated plasma cells in vitro
- B cells harboring a GC block competitively contribute to the plasma cell compartment in an autoreactive setting in vivo
- Lupus mice with a GC block display immune complex deposition in kidney glomeruli that is indistinguishable from their wild-type counterparts
Summary Affinity-matured autoantibodies generated in germinal centers are a hallmark of autoimmune diseases. Voss et al. block germinal centers in two autoimmune models, but surprisingly find that disease progresses unimpeded. They identify the extrafollicular pathway as a ‘backdoor to autoimmunity’.
Competing Interest Statement
TV-J and KJ-M are inventors on a submitted patent application (PCT/EP2020/082837), owned by Aarhus University, related to human spMBL as a biomarker for SLE. All other authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Footnotes
Additional data in a separate model have been added (New Figures 6, S6 and S7), which support the original findings. Minor corrections have been made in the manuscript. The title and abstract have been revised, and a short layman summary of central finding has been added. One reference has been updated. Supplementary data have been included in-text along with main figures.
