B cell depletion reduces T cell activation in pancreatic islets in a murine autoimmune diabetes model

Research progress in the treatment of an immune system disease-type 1 diabetes-by regulating the intestinal flora with Chinese medicine and food homologous drugs

Type 1 diabetes (T1D) is a specific autoimmune disease related to genetic and autoimmune factors. Recent studies have found that the intestinal flora is one of the important environmental factors in the development of T1D. The gut microbiota is the largest microbiota in the human body and has a significant impact on material and energy metabolism. Related studies have found that the intestinal floras of T1D patients are unbalanced. Compared with normal patients, the abundance of beneficial bacteria is reduced, and various pathogenic bacteria are significantly increased, affecting the occurrence and development of diabetes. Medicinal and food homologous traditional Chinese medicine (TCM) has a multicomponent, multitarget, and biphasic regulatory effect. Its chemical composition can increase the abundance of beneficial bacteria, improve the diversity of the intestinal flora, reduce blood sugar, and achieve the purpose of preventing and treating T1D by regulating the intestinal flora and its metabolites. Therefore, based on a review of T1D, intestinal flora, and TCM derived from medicine and food, this review describes the relationship between T1D and the intestinal flora, as well as the research progress of TCM interventions for T1D through regulation of the intestinal flora. Medicine and food homologous TCM has certain advantages in treating diabetes and regulating the intestinal flora. It can be seen that there is still great research space and broad development prospects for the treatment of diabetes by regulating the intestinal flora with drug and food homologous TCM.

Novel engineered B lymphocytes targeting islet-specific T cells inhibit the development of type 1 diabetes in non-obese diabetic Scid mice

Introduction

In this study, we report a novel therapeutic approach using B lymphocytes to attract islet-specific T cells in the non-obese diabetic (NOD) mouse model and prevent the development of autoimmune diabetes. Rather than using the antibody receptor of B cells, this approach utilizes their properties as antigen-presenting cells to T cells.

Methods

Purified splenic B cells were treated with lipopolysaccharide, which increases regulatory B (Breg) cell function, then electroporated with mRNA encoding either chimeric MHC-I or MHC-II molecules covalently linked to antigenic peptides. Immunoregulatory functions of these engineered B cells (e-B cells) were tested by in vitro assays and in vivo co-transfer experiments with beta-cell-antigen-specific CD8+ or CD4+ T cells in NOD.Scid mice, respectively.

Results

The e-B cells expressing chimeric MHC-I-peptide inhibited antigen-specific CD8+ T-cell cytotoxicity in vitro. The e-B cells expressing chimeric MHC-II-peptide induced antigen-specific CD4+ T cells to express the regulatory markers, PD-1, ICOS, CTLA-4, Lag3, and Nrp1. Furthermore, e-B cells encoding the chimeric MHC-I and MHC-II peptide constructs protected NOD.Scid mice from autoimmune diabetes induced by transfer of antigen-specific CD8+ and CD4+ T cells.

Discussion

MHC-peptide chimeric e-B cells interacted with pathogenic T cells, and protected the host from autoimmune diabetes, in a mouse model. Thus, we have successfully expressed MHC-peptide constructs in B cells that selectively targeted antigen-specific cells, raising the possibility that this strategy could be used to endow different protective cell types to specifically regulate/remove pathogenic cells.

Proinflammatory CD20+ T cells contribute to CNS-directed autoimmunity

The origin and function of CD20⁺ T cells are poorly understood. Here, we characterized CD20⁺ T cells in mice and humans and investigated how they are affected by anti-CD20 antibody treatment. We report that murine CD20⁺ T cells are unable to endogenously express the B cell lineage marker CD20; the development of CD20⁺ T cells in rodents requires the presence of CD20-expressing B cells. Our results demonstrated that both murine and human T cells acquire CD20 from B cells via trogocytosis while being activated by an antigen-presenting B cell. In patients with multiple sclerosis (MS) and mice with experimental autoimmune encephalomyelitis (EAE), expression of CD20 on T cells is associated with an up-regulation of activation markers, proinflammatory cytokines, and adhesion molecules, suggesting high pathogenic potential. Supporting this hypothesis, CD20⁺ T cells expand during active EAE in rodents; furthermore, adoptive transfer of CD20⁺ T cells into EAE-diseased mice worsened histological and clinical severity. Of direct therapeutic relevance, we demonstrate that the exclusive therapeutic elimination of CD20⁺ T cells effectively ameliorates EAE, independent of B cells. The results support the hypothesis that CD20⁺ T cells arise upon B cell-T cell interaction and that depletion of CD20⁺ T cells might contribute to the success of anti-CD20 antibody therapies in MS and other inflammatory disorders.

Differences of Circulating CD25hi Bregs and Their Correlations with CD4 Effector and Regulatory T Cells in Autoantibody-Positive T1D Compared with Age-Matched Healthy Individuals

Circulating CD25^hi B cells, a subset of regulatory B cells in humans, are closely related to inflammation and autoimmune diseases. This study is aimed at investigating the alternation of CD25^hi Bregs and their correlation with CD4 effector and regulatory T cells in T1D individuals. We included 68 autoantibody-positive T1D and 68 age-matched healthy individuals with peripheral blood mononuclear cells (PBMCs) and assessed them with CD25^hi Bregs and CD4 effector or regulatory T cells by flow cytometry. Here, we demonstrate that the frequency of CD25^hi Bregs was significantly decreased in T1D subjects (P = 0.0016), but they were not affected by disease status (age at T1D diagnosis or duration) or T1D risk loci (rs2104286 or rs12251307) in IL2RA (all P > 0.05). Moreover, higher IgD (P = 0.043) and lower CD27 (P = 0.0003) expression was observed in CD25^hi Bregs of T1D individuals, but not the expression of IgM, CD24, or CD38 (all P > 0.05). Although there was no correlation between CD25^hi Bregs and CD4 effector T cell subsets in either T1D or healthy individuals (all P > 0.05), we found a positive correlation between CD25^hi Bregs and CD4 Tregs in healthy controls (Sp. r = 0.3544, P = 0.0249), which disappeared in T1D subjects (Sp. r = 0.137, P = 0.401). In conclusion, our results suggest that decreased CD25^hi Bregs and alternation of their phenotypes are features of T1D regardless of disease duration and T1D genetic risk loci, and an impaired balance between CD25^hi Bregs and CD4 Tregs might contribute to the pathogenesis of T1D.

The Influence of Different Types of Diabetes on Vascular Complications

The final outcome of diabetes is chronic complications, of which vascular complications are the most serious, which is the main cause of death for diabetic patients and the direct cause of the increase in the cost of diabetes. Type 1 and type 2 diabetes are the main types of diabetes, and their pathogenesis is completely different. Type 1 diabetes is caused by genetics and immunity to destroy a large number of β cells, and insulin secretion is absolutely insufficient, which is more prone to microvascular complications. Type 2 diabetes is dominated by insulin resistance, leading to atherosclerosis, which is more likely to progress to macrovascular complications. This article explores the pathogenesis of two types of diabetes, analyzes the pathogenesis of different vascular complications, and tries to explain the different trends in the progression of different types of diabetes to vascular complications, in order to better prevent diabetes and its vascular complications.

Regulatory B Cells: Role in Type 1 Diabetes

Regulatory B cells (Bregs) have an anti-inflammatory role and can suppress autoimmunity, by employing both cytokine secretion and cell-contact mediated mechanisms. Numerous Breg subsets have been described and have overlapping phenotypes in terms of their immune expression markers or cytokine production. A hallmark feature of Bregs is the secretion of IL-10, although IL-35 and TGFβ−producing B cells have also been identified. To date, few reports have identified an impaired frequency or function of Bregs in individuals with type 1 diabetes; thus our understanding of the role played by these Breg subsets in the pathogenesis of this condition is limited. In this review we will focus on how regulatory B cells are altered in the development of type 1 diabetes, highlighting both frequency and function and discuss both human and animal studies.

Clonal diversity of the B cell receptor repertoire in patients with coronary in-stent restenosis and type 2 diabetes

Type 2 diabetes mellitus (T2DM) is known as a risk factor for coronary in-stent restenosis (ISR) in patients with coronary artery disease (CAD). Evidence suggests that B cells play a functional role in the progression of atherosclerotic lesions. However, the B cell receptor (BCR) repertoire in patients with ISR remains unclear. This study aims to profile the BCR repertoire in patients with coronary ISR/T2DM. A total of 21 CAD patients with or without ISR/T2DM were enrolled. PBMCs were isolated and examined for BCR repertoire profiles using DNA-seq. Our results showed that the diversity of amino acid sequences in ISR DM patients was higher than that in ISR -DM patients. The frequencies of 21 V/J paired genes differed between ISR DM and -ISR DM patients, while frequencies of 5 V/J paired genes differed between ISR DM and ISR -DM. The -ISR -DM group presented the highest clonotype overlap rate, while ISR DM patients presented the lowest overlap rate. Our study presented the BCR repertoires in patients with ISR/T2DM. The data suggested different BCR signatures between patients with ISR and T2DM. Further analysis of BCR profiles would enhance understanding of ISR.

Dysregulated translational factors and epigenetic regulations orchestrate in B cells contributing to autoimmune diseases

B cells play a crucial role in antigen presentation, antibody production and pro-/anti-inflammatory cytokine secretion in adaptive immunity. Several translational factors including transcription factors and cytokines participate in the regulation of B cell development, with the cooperation of epigenetic regulations. Autoimmune diseases are generally characterized with autoreactive B cells and high-level pathogenic autoantibodies. The success of B cell depletion therapy in mouse model and clinical trials has proven the role of B cells in pathogenesis of autoimmune diseases. The failure of B cell tolerance in immune checkpoints results in accumulated autoreactive naïve B (B_N) cells with aberrant B cell receptor signaling and dysregulated B cell response, contributing to self-antibody-mediated autoimmune reaction. Dysregulation of translational factors and epigenetic alterations in B cells has been demonstrated to correlate with aberrant B cell compartment in autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, primary Sjögren's syndrome, multiple sclerosis, diabetes mellitus and pemphigus. This review is intended to summarize the interaction of translational factors and epigenetic regulations that are involved with development and differentiation of B cells, and the mechanism of dysregulation in the pathogenesis of autoimmune diseases.

The Role of Regulatory B cells in Kidney Diseases

B cells, commonly regarded as proinflammatory antibody-producing cells, are detrimental to individuals with autoimmune diseases. However, in recent years, several studies have shown that regulatory B (Breg) cells, an immunosuppressive subset of B cells, may exert protective effects against autoimmune diseases by secretion of inhibitory cytokines such as IL-10. In practice, Breg cells are identified by their production of immune-regulatory cytokines, such as IL-10, TGF-β, and IL-35, however, no specific marker or Breg cell-specific transcription factor has been identified. Multiple phenotypes of Breg cells have been found, whose functions vary according to their phenotype. This review summarizes the discovery, phenotypes, development, and function of Breg cells and highlights their potential therapeutic value in kidney diseases.

Footprints of Immune Cells in the Pancreas in Type 1 Diabetes; to "B" or Not to "B": Is That Still the Question?

Significant progress has been made in understanding the phenotypes of circulating immune cell sub-populations in human type 1 diabetes but much less is known about the equivalent populations that infiltrate the islets to cause beta-cell loss. In particular, considerable uncertainties remain about the phenotype and role of B-lymphocytes in the pancreas. This gap in understanding reflects both the difficulty in accessing the gland to study islet inflammation during disease progression and the fact that the number and proportion of islet-associated B-lymphocytes varies significantly according to the disease endotype. In very young children (especially those <7 years at onset) pancreatic islets are infiltrated by both CD8+ T- and CD20+ B-lymphocytes in roughly equal proportions but it is widely held that the CD8+ T-lymphocytes are responsible for driving beta-cell toxicity. By contrast, the role played by B-lymphocytes remains enigmatic. This is compounded by the fact that, in older children and teenagers (those ≥13 years at diagnosis) the proportion of B-lymphocytes found in association with inflamed islets is much reduced by comparison with those who are younger at diagnosis (reflecting two endotypes of disease) whereas CD8+ T-lymphocytes form the predominant population in both groups. In the present paper, we review the current state of understanding and develop a proposal to stimulate further discussion of the roles played by islet-associated B-lymphocytes in human type 1 diabetes. We cite evidence indicating that sites of direct contact can be found between CD8+ and CD20+-lymphocytes in and around inflamed islets and propose that such interactions may be important in determining the efficiency of beta cell killing.

100 years post-insulin: immunotherapy as the next frontier in type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease characterised by T cell-mediated destruction of the insulin-producing β cells in the pancreas. Similar to other autoimmune diseases, the incidence of T1D is increasing globally. The discovery of insulin 100 years ago dramatically changed the outlook for people with T1D, preventing this from being a fatal condition. As we celebrate the centenary of this milestone, therapeutic options for T1D are once more at a turning point. Years of effort directed at developing immunotherapies are finally starting to pay off, with signs of progress in new onset and even preventative settings. Here, we review a selection of immunotherapies that have shown promise in preserving β cell function and highlight future considerations for immunotherapy in the T1D setting.

Endotypes in T1D: B lymphocytes and early onset

PURPOSE OF REVIEW

Although type 1 diabetes (T1D) is characterized by destruction of the pancreatic beta cells by self-reactive T cells, it has become increasingly evident that B cells also play a major role in disease development, likely functioning as antigen-presenting cells. Here we review the biology of islet antigen-reactive B cells and their participation in autoimmune diabetes.

RECENT FINDINGS

Relative to late onset, individuals who develop T1D at an early age display increased accumulation of insulin-reactive B cells in islets. This B-cell signature is also associated with rapid progression of disease and responsiveness to B-cell depletion therapy. Also suggestive of B-cell participation in disease is loss of anergy in high-affinity insulin-reactive B cells. Importantly, loss of anergy is seen in patient's healthy first-degree relatives carrying certain T1D risk alleles, suggesting a role early in disease development.

SUMMARY

Recent studies indicate that islet-reactive B cells may play a pathogenic role very early in T1D development in young patients, and suggest utility of therapies that target these cells.

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

AIMS/HYPOTHESIS

Autoreactive 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.

METHODS

We 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.

RESULTS

We 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 CD138^int fraction. Anti-insulin B cells were not identified in the plasma-cell CD138^hi 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 CD138^intinsulin⁺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/INTERPRETATION

Our observations may indicate why the loss of C-peptide is only temporarily delayed following anti-CD20 treatment in human type 1 diabetes.

Follicular regulatory T cells are associated with β-cell autoimmunity and the development of type 1 diabetes

OBJECTIVE

Impaired follicular regulatory T (Tfr) cells enhance T follicular helper (Tfh) cells activity, resulting in the expansion of autoreactive B cells and autoantibody production. However, the role of Tfr cells in the pathogenesis of type 1 diabetes (T1D) is unclear.

METHODS

We evaluated the expression and changes in function of circulating Tfr cells by studying patients with T1D alongside those with type 2 diabetes(T2D), first-degree relatives of T1D patients (T1D-FRs) and healthy controls. We also investigated the effects of Tfr cells on disease development in NOD mice and in an adoptive transfer model.

RESULTS

Tfr cells were significantly decreased in both patient groups. However, they showed different correlations with fasting C-peptide (C-P) and the area under the curve of blood C-peptide (C-PAUC) in patients with T1D and T2D. The frequency of Tfr cells was associated with the number of positive autoantibodies and the titer of GAD autoantibody in T1D patients. Furthermore, Tfr cells decreased significantly after 1 year of follow-up. We also observed Tfr cells in four T1D patients treated with rituximab. After rituximab therapy, the frequency of CXCR5+PD-1+ Tfr cells was decreased and of CXCR5+ICOS+ Tfr cells was increased in three patients. We also found that Tfr cells were associated with the development of diabetes in NOD mice and an adoptive transfer model.

CONCLUSIONS

Tfr cell deficiency could be involved in the pathogenesis of T1D. Therapy with Tfr cells has potential value for T1D. Modulation of these cells may be enhance protective immunity to inhibit autoimmune diabetes.

Anti-drug Antibodies Against a Novel Humanized Anti-CD20 Antibody Impair Its Therapeutic Effect on Primary Biliary Cholangitis in Human CD20- and FcγR-Expressing Mice

There is considerable interest in expanding B cell-targeted therapies in human autoimmune diseases. However, clinical trials in human primary biliary cholangitis (PBC) using a chimeric antibody against human CD20 (hCD20) have showed limited efficacy. Two potential explanations for these disappointing results are the appearance of anti-drug antibodies (ADAs) and the high frequency of patients with moderate PBC or patients who had failed ursodeoxycholic acid treatment. Here, we studied a novel humanized IgG1 antibody against hCD20 and explored its efficacy in early stage PBC using a well-defined murine model. We developed a unique murine model consisting of dnTGF-βRII mice expressing hCD20 and human Fcγ receptors (hFcγRs). Beginning at 4–6 weeks of age, equivalent to stage I/II human PBC, female mice were given weekly injections of an anti-hCD20 antibody (TKM-011) or vehicle control, and monitored for liver histology as well as a broad panel of immunological readouts. After 16 weeks' treatment, we observed a significant reduction in portal inflammation, a decrease in liver-infiltrating mononuclear cells as well as a reduction in liver CD8⁺ T cells. Importantly, direct correlations between numbers of liver non-B cells and B cells (r = 0.7426, p = 0.0006) and between numbers of liver memory CD8⁺ T cells and B cells (r = 0.6423, p = 0.0054) were apparent. Accompanying these changes was a dramatic reduction in anti-mitochondrial antibodies (AMAs), interleukin (IL)-12p40 and IL-5, and elevated levels of the anti-inflammatory chemokine CXCL1/KC. In mice that developed ADAs, clinical improvements were less pronounced. Sustained treatment with B cell-targeted therapies may broadly inhibit effector pathways in PBC, but may need to be administered early in the natural history of PBC.