Phenotypically distinct anti-insulin B cells repopulate pancreatic islets after anti-CD20 treatment in NOD mice

Abstract

Aims/hypothesisAutoreactive B cells escape immune tolerance and contribute to the pathogenesis of type 1 diabetes. While global B cell depletion is a successful therapy for autoimmune disease, the fate of autoreactive cells during this treatment in autoimmune diabetes is unknown. We aimed to identify and track anti-insulin B cells in pancreatic islets and understand their repopulation after anti-CD20 treatment.MethodsWe generated a double transgenic system, the VH125.hCD20/NOD mouse. The VH125 transgenic mouse, expressing an increased frequency of anti-insulin B cells, was crossed with a human CD20 (hCD20) transgenic mouse, to facilitate B cell depletion using anti-CD20. B cells were analysed using multiparameter and ImageStream flow cytometry.ResultsWe demonstrated that anti-insulin B cells were recruited to the pancreas during disease progression in VH125.hCD20/NOD mice. We identified two distinct populations of anti-insulin B cells in pancreatic islets, based on CD19 expression, with both populations enriched in the CD138int fraction. Anti-insulin B cells were not identified in the plasma-cell CD138hi fraction, which also expressed the transcription factor Blimp-1. After anti-CD20 treatment, anti-insulin B cells repopulated the pancreatic islets earlier than non-specific B cells. Importantly, we observed that a CD138intinsulin+CD19− population was particularly enriched after B cell depletion, possibly contributing to the persistence of disease still observed in some mice after anti-CD20 treatment.Conclusions/interpretationOur observations may indicate why the loss of C-peptide is only temporarily delayed following anti-CD20 treatment in human type 1 diabetes.Electronic supplementary materialThe online version of this article (10.1007/s00125-019-04974-y) contains peer-reviewed but unedited supplementary material, which is available to authorised users.

Natural Protection From Type 1 Diabetes in NOD Mice Is Characterized by a Unique Pancreatic Islet Phenotype

“…CD138 + IgDcells identified here are a heterogenous pool of dividing and non-dividing plasmablasts at various intermediate differentiation stages, which consist of CD19 + and CD19cells which lack IgM expression and are more proliferative compared to classical B cells. Crucially, this subset also contains antigen-specific B cells (9). Further work on these defined subsets is required to understand if they are a B1-like-cell that has altered due to the inflamed tissue environment.…”

Insulin-Reactive T Cells Convert Diabetogenic Insulin-Reactive VH125 B Cells Into Tolerogenic Cells by Reducing Germinal Center T:B Cell Interactions in NOD Mice

“…B cells were stained with mAbs to CD19 (6D5), B220 (RA3-6B2), MHCII (10-3.6), CD40 (3/23), CD21 (7E9), CD23 (B3B4), GL7 (GL7), CD80 (16-10A1), CD86 (GL-1), PDL-1 (10F.9G2), and PNA (Sigma). Insulin-FITC (Sigma) was used for the detection of insulin-reactive B cells (at a dilution of 1:2000) as previously described ( 28 ). Cells were then washed (with an additional wash if stained with insulin-FITC), resuspended and examined on a BD LSRII flow cytometer on the same day.…”

B Quiet: Autoantigen-Specific Strategies to Silence Raucous B Lymphocytes and Halt Cross-Talk with T Cells in Type 1 Diabetes

“…Conversely, work by Boldison et al suggests that downregulation of CD20 is not universal for all islet-infiltrating B cells. Instead, autoreactive, AIBCs comprise a heterogeneous population in which CD20 + AIBCs preferentially home to islets in the pancreas where they adopt a distinct CD138 int phenotype [ 27 ]. After global B lymphocyte depletion, these antigen-specific B lymphocytes repopulate the islets sooner than non-antigen-specific B lymphocytes, which supports the notion that antigen-specific, targeted therapy will be required for improved efficacy and safer therapeutic alternatives [ 27 ].…”

“…B lymphocyte repertoires biased toward insulin accelerate disease onset while those biased toward an irrelevant antigen are protected [ 16 ]. Anti-insulin T cells adopt a default regulatory phenotype but become pathogenic in the presence of an expanded pool of insulin specific B cells in mice, and there is a direct correlation between insulin specific effector memory T cells and IAA titers in individuals with new onset T1D [ 27 , 44 ]. It is not surprising, then, that anti-insulin B cell receptor (BCR) heavy chain transgenic mice (VH125 SD /NOD) develop accelerated insulitis and diabetes secondary to an increased frequency of AIBCs, whereas NOD mice lacking AIBCs are protected [ 16 , 45 , 46 ].…”

“…Consequently, BTK targeting in NOD mice is unlikely to impair autoreactive, AIBC function but instead decreases the availability of mature, autoreactive, antigen-specific B cells within an endogenous repertoire. As mentioned above, AIBCs repopulate the pancreas earlier than non-insulin-binding B cells following anti-CD20 B cell depletion [ 27 ]. This suggests that an ideal therapeutic strategy may require a large hit to B cells (e.g., via rituximab) followed by maintenance therapy via BTK inhibition to prevent re-emergence of AIBCs.…”