Altered Peripheral B-Lymphocyte Subsets in Type 1 Diabetes and Latent Autoimmune Diabetes in Adults

Hsa_circRNA_405498 and hsa_circRNA_100033 Serve as Potential Biomarkers for Differential Diagnosis of Type 1 Diabetes

CONTEXT

The role of circular RNAs (circRNAs) in type 1 diabetes (T1D) is largely unknown.

OBJECTIVE

We aimed to identify some circRNAs as differential diagnostic biomarkers for T1D to distinguish between patients with latent autoimmune diabetes in adults (LADA) and type 2 diabetes (T2D).

METHODS

The circRNA expression profiles were determined by Arraystar human circRNA microarray in T1D compared to controls (n = 6 each). The differentially expressed circRNAs were validated by real-time quantitative polymerase chain reaction using a validation cohort with 20 T1D and 20 controls. The diagnostic performances of the candidate circRNAs and the clinical parameters were assessed using the logistic least absolute shrinkage and selection operator (LASSO) regression model in a larger cohort with 457 individuals, including patients with T1D, T2D, and LADA, and controls.

RESULTS

We identified 110 differentially expressed circular transcripts (53 upregulated and 57 downregulated) in T1D patients compared with controls. Further analysis showed that the levels of hsa_circRNA_405498 and hsa_circRNA_100033 were significantly downregulated in T1D compared to controls (both P < .05). Moreover, the expression levels of these 2 circRNAs showed sequential downregulation from controls, patients with T2D, LADA, to T1D (P < .05). The area under the curve (AUC) of receiver operating characteristic plots in logistic LASSO regression model showed high diagnostic accuracy for combination model with the 2 circRNAs and some clinical parameters in distinguishing T1D from LADA (AUC = 0.915), T2D (AUC = 0.993), and controls (AUC = 0.992).

CONCLUSION

Our study demonstrated that hsa_circRNA_405498 and hsa_circRNA_100033 are promising novel differential diagnostic biomarkers for T1D.

Simplified integration of optimal self-management behaviors is associated with improved HbA1c in patients with type 1 diabetes

PURPOSE

Living with type 1 diabetes requires burdensome and complex daily diabetes self-management behaviors. This study aimed to determine the association between integrated behavior performance and HbA1c, while identifying the behavior with the most significant impact on HbA1c.

METHODS

A simple and feasible questionnaire was used to collect diabetes self-management behavior in patients with type 1 diabetes (n = 904). We assessed six dimensions of behavior performance: continuous glucose monitor (CGM) usage, frequent glucose testing, insulin pump usage, carbohydrate counting application, adjustment of insulin doses, and usage of apps for diabetes management. We evaluated the association between these behaviors and HbA1c.

RESULTS

In total, 21.3% of patients performed none of the allotted behavior, while 28.5% of patients had a total behavior score of 3 or more. 63.6% of patients with a behavior score ≥ 3 achieved HbA1c goal, contrasting with only 30.4% of patients with a behavior score of 0-1. There was a mean 0.54% ± 0.05% decrease in HbA1c for each 1-unit increase in total behavior score after adjustment for age, family education and diabetes duration. Each behavior was independently correlated with a lower HbA1c level, with CGM having the most significant effect on HbA1c levels.

CONCLUSIONS

Six optimal self-management behaviors, especially CGM usage, were associated with improved glycemic control, emphasizing the feasibility of implementing a simplified version of DSMES in the routine clinical care.

REGISTRATION NUMBER

ClinicalTrials.gov Identifier: NCT03610984.

Factors Governing B Cell Recognition of Autoantigen and Function in Type 1 Diabetes

Islet autoantibodies predict type 1 diabetes (T1D) but can be transient in murine and human T1D and are not thought to be directly pathogenic. Rather, these autoantibodies signal B cell activity as antigen-presenting cells (APCs) that present islet autoantigen to diabetogenic T cells to promote T1D pathogenesis. Disrupting B cell APC function prevents T1D in mouse models and has shown promise in clinical trials. Autoantigen-specific B cells thus hold potential as sophisticated T1D biomarkers and therapeutic targets. B cell receptor (BCR) somatic hypermutation is a mechanism by which B cells increase affinity for islet autoantigen. High-affinity B and T cell responses are selected in protective immune responses, but immune tolerance mechanisms are known to censor highly autoreactive clones in autoimmunity, including T1D. Thus, different selection rules often apply to autoimmune disease settings (as opposed to protective host immunity), where different autoantigen affinity ceilings are tolerated based on variations in host genetics and environment. This review will explore what is currently known regarding B cell signaling, selection, and interaction with T cells to promote T1D pathogenesis.

Changes of B cell subsets in different types of diabetes and its effect on the progression of latent autoimmune diabetes in adults

PURPOSE

Developmental abnormalities in B cells is one of the key players in autoimmune diabetes, but little is known about its role in latent autoimmune diabetes in adults (LADA). This study aimed to investigate the distribution of B cell subsets in different types of diabetes and to analyze their correlations with other biochemical parameters.

METHODS

A total of 140 participants were prospectively enrolled from January 2021 to December 2022. Diabetes-related autoantibodies and laboratory indicators were tested. Flow cytometry was used to analyze the percentage of circulating B cell subsets and T follicular cells. The correlation of B cell subsets with different indicators was assessed by Spearman's correlation method.

RESULTS

We observed that the Naïve phenotype cells tended to be less frequent in patients with diabetes than in healthy controls. The frequency of plasmablasts (PB) and Breg cell-related phenotype (B10) were significantly higher in LADA. Notably, the percentage of PB was positively associated with levels of islet cell antibody (ICA) and insulin autoantibody (IAA), but inversely associated with fasting C-peptide (FCP), further indicating that PB may promote the destruction of β-cell in patients with diabetes.

CONCLUSIONS

This study showed that patients with LADA had significantly altered frequencies of B cell subsets, particularly in the naïve to memory B cell ratio. Our study provided valuable information on the distribution characteristics of B cell subsets in LADA and suggested the feasibility of B-cell targeted therapy in LADA patients.

The MHC Class II Antigen-Processing and Presentation Pathway Is Dysregulated in Type 1 Diabetes

Peptide loading of MHC class II (MHCII) molecules is facilitated by HLA-DM (DM), which catalyzes CLIP release, stabilizes empty MHCII, and edits the MHCII-bound peptide repertoire. HLA-DO (DO) binds to DM and modulates its activity, resulting in an altered set of peptides presented at the cell surface. MHCII-peptide presentation in individuals with type 1 diabetes (T1D) is abnormal, leading to a breakdown in tolerance; however, no direct measurement of the MHCII pathway activity in T1D patients has been performed. In this study, we measured MHCII Ag-processing pathway activity in humans by determining MHCII, MHCII-CLIP, DM, and DO levels by flow cytometry for peripheral blood B cells, dendritic cells, and monocytes from 99 T1D patients and 97 controls. Results showed that MHCII levels were similar for all three APC subsets. In contrast, MHCII-CLIP levels, independent of sex, age at blood draw, disease duration, and diagnosis age, were significantly increased for all three APCs, with B cells showing the largest increase (3.4-fold). DM and DO levels, which usually directly correlate with MHCII-CLIP levels, were unexpectedly identical in T1D patients and controls. Gene expression profiling on PBMC RNA showed that DMB mRNA was significantly elevated in T1D patients with residual C-peptide. This resulted in higher levels of DM protein in B cells and dendritic cells. DO levels were also increased, suggesting that the MHCII pathway maybe differentially regulated in individuals with residual C-peptide. Collectively, these studies show a dysregulation of the MHCII Ag-processing pathway in patients with T1D.

Elevated glucose metabolism driving pro-inflammatory response in B cells contributes to the progression of type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease characterized by the immune system's failure to maintain self-tolerance, resulting in the autoimmune destruction of pancreatic beta cells. Although T1D has conventionally been viewed as a T-cell-dominant disease, recent research has emphasized the contribution of B cells in the onset of the disease. However, the mechanism underlying aberrant B cell responses remains unknown. B cell metabolism is a crucial prerequisite for B cell function and the development of adaptive immune responses. Here, we investigated the metabolic features of B cells, first in a cross-sectional cohort and subsequently in non-obese diabetic (NOD) mice, and revealed that there is an increased frequency of high-glucose-avidity (2-NBDGhigh) B cell population that may contribute to T1D progression. Further characterization of the metabolic, transcriptional and functional phenotype of B cells in NOD mice found that elevated glucose avidity is associated with a greater capacity for co-stimulation, proliferation and inflammatory cytokine production. Mechanistically, elevated Myc signaling orchestrated the glucose metabolism and the pro-inflammatory response of B cells in T1D. In vitro experiments demonstrated that pharmacological inhibition of glucose metabolism using metformin and 2-DG reduced pro-inflammatory cytokine production and B cell proliferation. Moreover, the combination of these inhibitors successfully delayed insulitis development, onset of diabetes, and improved high blood glucose levels in streptozotocin (STZ)-induced diabetic mice model. Taken together, our work has uncovered these high-glucose-avidity B cells as novel adjuvant diagnostic and therapeutic targets for T1D.

B cell metabolism in autoimmune diseases: signaling pathways and interventions

Autoimmune diseases are heterogeneous disorders believed to stem from the immune system's inability to distinguish between auto- and foreign- antigens. B lymphocytes serve a crucial role in humoral immunity as they generate antibodies and present antigens. Dysregulation of B cell function induce the onset of autoimmune disorders by generating autoantibodies and pro-inflammatory cytokines, resulting in an imbalance in immune regulation. New research in immunometabolism shows that cellular metabolism plays an essential role in controlling B lymphocytes immune reactions by providing the energy and substrates for B lymphocytes activation, differentiation, and function. However, dysregulated immunometabolism lead to autoimmune diseases by disrupting self-tolerance mechanisms. This review summarizes the latest research on metabolic reprogramming of B lymphocytes in autoimmune diseases, identifying crucial pathways and regulatory factors. Moreover, we consider the potential of metabolic interventions as a promising therapeutic strategy. Understanding the metabolic mechanisms of B cells brings us closer to developing novel therapies for autoimmune disorders.

Identification of an anergic BND cell-derived activated B cell population (BND2) in young-onset type 1 diabetes patients

Recent evidence suggests a role for B cells in the pathogenesis of young-onset type 1 diabetes (T1D), wherein rapid progression occurs. However, little is known regarding the specificity, phenotype, and function of B cells in young-onset T1D. We performed a cross-sectional analysis comparing insulin-reactive to tetanus-reactive B cells in the blood of T1D and controls using mass cytometry. Unsupervised clustering revealed the existence of a highly activated B cell subset we term BND2 that falls within the previously defined anergic BND subset. We found a specific increase in the frequency of insulin-reactive BND2 cells in the blood of young-onset T1D donors, which was further enriched in the pancreatic lymph nodes of T1D donors. The frequency of insulin-binding BND2 cells correlated with anti-insulin autoantibody levels. We demonstrate BND2 cells are pre-plasma cells and can likely act as APCs to T cells. These findings identify an antigen-specific B cell subset that may play a role in the rapid progression of young-onset T1D.

Association of immune cell composition with the risk factors and incidence of acute coronary syndrome

BACKGROUND

Although immune cells are involved in acute coronary syndrome (ACS), few studies have explored the association of incident ACS with the relative immune cell proportions. We aimed to investigate the association of immune cell proportions with the incidence and risk factors of ACS in the Dongfeng-Tongji cohort.

METHODS

We conducted the analyses with 38,295 subjects from the first follow-up of the Dongfeng-Tongji cohort, including DNA methylation profiles for 1570 individuals. The proportions of immune cell types were observed from routine blood tests or estimated from DNA methylation profiles. For both observed and estimated immune cell proportions, we tested their associations with risk factors of ACS by multivariable linear regression models. In addition, the association of each immune cell proportion with incident ACS was assessed by the Cox regression model and conditional logistic regression model, respectively, adjusting for the risk factors of ACS.

FINDINGS

The proportions of lymphocytes, monocytes, and neutrophils showed strong associations with sex, followed by diabetes. Moreover, sex and current smoking were the two factors with strongest association with the proportions of lymphocyte subtypes. The hazard ratio (HR) and 95% confidence interval (CI) of incident ACS per standard deviation (SD) increase in proportions of lymphocytes and neutrophils were 0.91 (0.85-0.96) and 1.10 (1.03-1.16), respectively. Furthermore, the OR (95% CI) of incident ACS per SD increase in proportions of NK cells, CD4⁺ T cells, and B cells were 0.88 (0.78-0.99), 1.15 (1.03-1.30), and 1.13 (1.00-1.26), respectively.

INTERPRETATION

The proportions of immune cells were associated with several risk factors of ACS, including sex, diabetes, and current smoking. In addition, proportion of neutrophils had a risk effect, while proportion of lymphocytes had a protective effect on the incidence of ACS. The protective effect of lymphocytes was probably driven by NK cells.

Type 1 diabetes and inborn errors of immunity: Complete strangers or 2 sides of the same coin?

Type 1 diabetes (T1D) is a polygenic disease and does not follow a mendelian pattern. Inborn errors of immunity (IEIs), on the other hand, are caused by damaging germline variants, suggesting that T1D and IEIs have nothing in common. Some IEIs, resulting from mutations in genes regulating regulatory T-cell homeostasis, are associated with elevated incidence of T1D. The genetic spectrum of IEIs is gradually being unraveled; consequently, molecular pathways underlying human monogenic autoimmunity are being identified. There is an appreciable overlap between some of these pathways and the genetic variants that determine T1D susceptibility, suggesting that after all, IEI and T1D are 2 sides of the same coin. The study of monogenic IEIs with a variable incidence of T1D has the potential to provide crucial insights into the mechanisms leading to T1D. These insights contribute to the definition of T1D endotypes and explain disease heterogeneity. In this review, we discuss the interconnected pathogenic pathways of autoimmunity, β-cell function, and primary immunodeficiency. We also examine the role of environmental factors in disease penetrance as well as the circumstantial evidence of IEI drugs in preventing and curing T1D in individuals with IEIs, suggesting the repositioning of these drugs also for T1D therapy.

Immunomodulatory Effect of Isocaloric Diets with Different Protein Contents on Young Adult Sprague Dawley Rats

To understand the potential mechanisms of dietary protein on intestinal and host health, we studied the immunomodulatory effects of isocaloric diets with high or low crude protein (CP) contents on young adult Sprague Dawley (SD) rats. A total of 180 healthy male rats were randomly assigned to six groups (six replicate pens per treatment with five rats per pen) and fed diets with 10% CP, 14% CP, 20% CP (control), 28% CP, 38% CP, and 50% CP. Compared with the control diet, the rats fed the 14% CP diet significantly elevated lymphocyte cell counts in the peripheral blood and ileum, whereas the 38% CP diet significantly activated the expression of the TLR4/NF-κB signaling pathway in the colonic mucosa (p < 0.05). Moreover, the 50% CP diet reduced growth performance and fat deposition and increased the percentages of CD4⁺ T, B, and NK cells in the peripheral blood and the colonic mucosal expression of IL-8, TNF-α, and TGF-β. Overall, rats fed the 14% CP diet enhanced host immunity by increasing the numbers of immune cells, and the immunological state and growth of SD rats were negatively impacted by the diet containing 50% CP.

The crucial role and mechanism of insulin resistance in metabolic disease

Insulin resistance (IR) plays a crucial role in the development and progression of metabolism-related diseases such as diabetes, hypertension, tumors, and nonalcoholic fatty liver disease, and provides the basis for a common understanding of these chronic diseases. In this study, we provide a systematic review of the causes, mechanisms, and treatments of IR. The pathogenesis of IR depends on genetics, obesity, age, disease, and drug effects. Mechanistically, any factor leading to abnormalities in the insulin signaling pathway leads to the development of IR in the host, including insulin receptor abnormalities, disturbances in the internal environment (regarding inflammation, hypoxia, lipotoxicity, and immunity), metabolic function of the liver and organelles, and other abnormalities. The available therapeutic strategies for IR are mainly exercise and dietary habit improvement, and chemotherapy based on biguanides and glucagon-like peptide-1, and traditional Chinese medicine treatments (e.g., herbs and acupuncture) can also be helpful. Based on the current understanding of IR mechanisms, there are still some vacancies to follow up and consider, and there is also a need to define more precise biomarkers for different chronic diseases and lifestyle interventions, and to explore natural or synthetic drugs targeting IR treatment. This could enable the treatment of patients with multiple combined metabolic diseases, with the aim of treating the disease holistically to reduce healthcare expenditures and to improve the quality of life of patients to some extent.

Aberrant alteration of peripheral B lymphocyte subsets in hepatocellular carcinoma patients

Although B lymphocytes are widely known to participate in the immune response, the conclusive roles of B lymphocyte subsets in the antitumor immune response have not yet been determined. Single-cell data from GEO datasets were first analyzed, and then a B cell flow cytometry panel was used to analyze the peripheral blood of 89 HCC patients and 33 healthy controls recruited to participate in our research. Patients with HCC had a higher frequency of B10 cells and a lower percentage of MZB cells than healthy controls. And the changes in B cell subsets might occur at an early stage. Moreover, the frequency of B10 cells decreased after surgery. Positively correlated with B10 cells, the elevated IL-10 level in HCC serum may be a new biomarker in HCC identification. For the first time, our results suggest that altered B cell subsets are associated with the development and prognosis of HCC. Increased B10 cell percentage and IL-10 in HCC patients suggest they might augment the development of liver tumors. Hence, B cell subsets and related cytokines may have predictive value in HCC patients and could be potential targets for immunotherapy in HCC.

Latent autoimmune diabetes in adults in China

Latent autoimmune diabetes in adults (LADA) is a type of diabetes caused by slow progression of autoimmune damage to pancreatic beta cells. According to the etiological classification, LADA should belong to the autoimmune subtype of type 1 diabetes (T1D). Previous studies have found general immune genetic effects associated with LADA, but there are also some racial differences. Multicenter studies have been conducted in different countries worldwide, but it is still unclear how the Chinese and Caucasian populations differ. The epidemiology and phenotypic characteristics of LADA may vary between Caucasian and Chinese diabetic patients as lifestyle, food habits, and body mass index differ between these two populations. The prevalence of LADA in China has reached a high level compared to other countries. The prevalence of LADA in China has reached a high level compared to other countries, and the number of patients with LADA ranks first in the world. Previous studies have found general immune genetic effects associated with LADA, but some racial differences also exist. The prevalence of LADA among newly diagnosed type 2 diabetes patients over the age of 30 years in China is 5.9%, and LADA patients account for 65% of the newly diagnosed T1D patients in the country. As a country with a large population, China has many people with LADA. A summary and analysis of these studies will enhance further understanding of LADA in China. In addition, comparing the similarities and differences between the Chinese and the Caucasian population from the perspectives of epidemiology, clinical, immunology and genetics will help to improve the understanding of LADA, and then promote LADA studies in individual populations.

Altered Tim-1 and IL-10 Expression in Regulatory B Cell Subsets in Type 1 Diabetes

Background

Type 1 diabetes (T1D) is an autoimmune disease with a complex aetiology. B cells play an important role in the pathogenesis of T1D. Regulatory B cells (Bregs) are a subset of B cells that produce and secrete the inhibitory factor interleukin-10 (IL-10), thereby exerting an anti-inflammatory effect. It was recently discovered that T-cell immunoglobulin mucin domain 1 (Tim-1) is essential for maintaining Bregs function related to immune tolerance. However, the detailed understanding of Tim-1⁺ Bregs and IL-10⁺ Bregs in T1D patients is lacking. This study aimed to characterize the profile of B cell subsets in T1D patients compared with that in controls and determine whether Tim-1⁺ Bregs and IL-10⁺ Bregs play roles in T1D.

Materials and Methods

A total of 47 patients with T1D, 30 patients with type 2 diabetes (T2D) and 24 healthy controls were recruited in this study. Flow cytometry was used to measure the levels of different B cell subsets (including B cells, plasmablasts, and Bregs) in the peripheral blood. Radiobinding assays were performed to detect the antibody titres of T1D patients. In addition, the correlations between different B cell subsets and patient parameters were investigated.

Results

Compared with healthy controls, differences in frequency of Tim-1⁺ Bregs were significantly decreased in patients with T1D (36.53 ± 6.51 vs. 42.25 ± 6.83, P=0.02^*), and frequency of IL-10⁺ Bregs were lower than healthy controls (17.64 ± 7.21vs. 24.52 ± 11.69, P=0.009^**), the frequency of total Bregs in PBMC was also decreased in patients with T1D (1.42 ± 0.53vs. 1.99 ± 0.93, P=0.002.^**). We analyzed whether these alterations in B cells subsets were associated with clinical features. The frequencies of Tim-1⁺ Bregs and IL-10⁺ Bregs were negatively related to fasting blood glucose (FBG) (r=-0.25 and -0.22; P=0.01^* and 0.03^*, respectively). The frequencies of Tim-1⁺ Bregs and IL-10⁺ Bregs are positively correlated with fast C-peptide (FCP) (r=0.23 and 0.37; P=0.02^* and 0.0001^***, respectively). In addition, the frequency of IL-10⁺ Breg was also negatively related to glycosylated haemoglobin (HbA1c) (r=-0.20, P=0.04^*). The frequencies of Tim-1⁺ Bregs, IL-10⁺ Bregs and Bregs in T2D patients were reduced, but no statistically significant difference was found between other groups. Interestingly, there was positive correlation between the frequencies of Tim-1⁺ Bregs and IL-10⁺ Bregs in T1D (r=0.37, P=0.01^*). Of note, it is worth noting that our study did not observe any correlations between B cell subsets and autoantibody titres.

Conclusions

Our study showed altered Tim-1 and IL-10 expression in regulatory B cell in T1D patients. Tim-1, as suggested by the present study, is associated with islet function and blood glucose levels. These findings indicate that Tim-1⁺ Bregs and IL-10⁺ Bregs were involved in the pathogenesis of T1D.

Increased plasmablasts enhance T cell-mediated beta cell destruction and promote the development of type 1 diabetes

BACKGROUND

Although type 1 diabetes (T1D) is typically described as a T cell-mediated autoimmune disease, increasing evidence for a role of B cells has emerged. However, the pivotal disease-relevant B cell subset and its contribution to islet autoimmunity remain elusive.

METHODS

The frequencies and phenotypic characteristics of circulating B cell subsets were analyzed using flow cytometry in individuals with new-onset T1D, long-term T1D, type 2 diabetes, and nondiabetic controls, and also in a prospective cohort of patients receiving mesenchymal stromal cell (MSC) transplantation. NOD mice and adoptive transfer assay were used to dissect the role of the certain B cell subset in disease progression. An in-vitro coculture system of islets with immune cells was established to examine the response against islets and the underlying mechanisms.

RESULTS

We identified that plasmablasts, a B cell subset at the antibody-secreting stage, were significantly increased and correlated with the deterioration of beta cell function in patients with new-onset T1D. Further, a fall of plasmablast number was associated with the preservation of beta cell function in patients who received MSC transplantation after 3 months of follow-up. Meanwhile, a gradual increase of plasmablasts in pancreatic lymph nodes during the natural progression of insulitis was observed in non-obese diabetic (NOD) mice; adoptive transfer of plasmablasts together with T cells from NOD mice accelerated diabetes onset in NOD/SCID recipients.

CONCLUSIONS

Our study revealed that plasmablasts may function as antigen-presenting cells and promote the activation and proinflammatory response of CD4+ T cells, further contributing to the T cell-mediated beta cell destruction. Our results provide insights into the pathogenic role of plasmablasts in islet autoimmunity and may offer new translational strategies for inhibiting T1D development.

Latent Autoimmune Diabetes in Adults (LADA): From Immunopathogenesis to Immunotherapy

Latent autoimmune diabetes in adults (LADA) is a type of diabetes characterized by slow autoimmune damage of pancreatic β cells without insulin treatment in the early clinical stage. There are differences between LADA and classical type 1 diabetes (T1D) and type 2 diabetes (T2D) in genetic background, autoimmune response, rate of islet function decline, clinical metabolic characteristics, and so on. The disease progression and drug response of patients with LADA are closely related to the level of islet autoimmunity, thus exploring the pathogenesis of LADA is of great significance for its prevention and treatment. Previous studies reported that adaptive immunity and innate immunity play a critical role in the etiology of LADA. Recent studies have shown that the intestinal microbiota which impacts host immunity hugely, participates in the pathogenesis of LADA. In addition, the progression of autoimmune pancreatic β cell destruction in LADA is slower than in classical T1D, providing a wider window of opportunities for intervention. Therefore, therapies including antidiabetic drugs with immune-regulation effects and immunomodulators could contribute to promising interventions for LADA. We also shed light on potential interventions targeting the gut microbiota and gut-associated immunity, which may be envisaged to halt or delay the process of autoimmunity in LADA.

Single-cell RNA sequencing analysis reveals the relationship of bone marrow and osteopenia in STZ-induced type 1 diabetic mice

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scRNA-seq analysis reveals the profiles of bone marrow cells in STZ-induced T1D mice.

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scRNA-seq analysis reveals the heterogeneity of bone marrow immune cells in STZ-induced T1D mice.

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The ratio of BM-neutrophils to B lymphocytes is increased in the bone marrow of STZ-induced T1D mice.

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Osteopenia is occurred in STZ-induced T1D mice.

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This increased ratio is negatively correlated with osteopenia in STZ-induced T1D mice.

Introduction

Type 1 diabetes (T1D) is a multifactorial autoimmune disease. Broad knowledge about the genetics, epidemiology and clinical management of T1D has been achieved, but understandings about the cell varieties in the bone marrow during T1D remain limited.

Objectives

We aimed to present a profile of the bone marrow cells and reveal the relationship of bone marrow and osteopenia in streptozotocin (STZ)-induced T1D mice.

Methods

The whole bone marrow cells from the femurs and tibias of healthy (group C) and STZ-induced T1D mice (group D) were collected for single-cell RNA sequencing analysis. Single-cell flow cytometry and immunohistochemistry were performed to confirm the proportional changes among bone marrow neutrophils (BM-neutrophils) (Cxcr2⁺, Ly6g⁺) and B lymphocytes (Cd19⁺). X-ray and micro-CT were performed to detect bone mineral density. The correlation between the ratio of BM-neutrophils/B lymphocytes and osteopenia in STZ-induced T1D mice was analyzed by nonparametric Spearman correlation analysis.

Results

The bone marrow cells in groups C and D were divided into 12 clusters, and 249 differentially expressed genes were found. The diversity of CD45⁺ immune cells between groups C and D were greatly affected: the proportion of BM-neutrophils showed a significant increase while the proportion of B lymphocytes in group D showed a significant decrease. X-ray and micro-CT analyses confirmed that osteopenia occurred in group D mice. In addition, the results of single-cell flow cytometry and correlation analysis showed that the ratio of BM-neutrophils/B lymphocytes negatively correlated with osteopenia in STZ-induced T1D mice.

Conclusion

A single-cell RNA sequencing analysis revealed the profile and heterogeneity of bone marrow immune cells in STZ-induced T1D mice for the first time. The ratio of BM-neutrophils/B lymphocytes negatively correlated with osteopenia in STZ-induced T1D mice, which may enhance understanding for treating T1D and preventing T1D-induced osteopenia.

Latent autoimmune diabetes in adults: a focus on β-cell protection and therapy

Latent autoimmune diabetes in adults (LADA) is a heterogeneous disease sharing some phenotypic, genetic, and immunological features with both type 1 and 2 diabetes. Patients with LADA have a relatively slow autoimmune process and more residual islet β-cell function at onset, allowing a time window to protect residual islet β cells and delay or inhibit disease progression. It is crucial to discover various heterogeneous factors affecting islet β-cell function for precise LADA therapy. In this review, we first describe the natural history of LADA. Thereafter, we summarize β-cell function-related heterogeneous factors in LADA, including the age of onset, body mass index, genetic background, and immune, lifestyle, and environmental factors. In parallel, we evaluate the impact of current hypoglycemic agents and immune intervention therapies for islet β-cell protection. Finally, we discuss the opportunities and challenges of LADA treatment from the perspective of islet β-cell function protection.

Innate immunity in latent autoimmune diabetes in adults

Latent autoimmune diabetes in adults (LADA) is an autoimmune disease that shares some genetic, immunological and clinical features with both type 1 diabetes and type 2 diabetes. Immune cells including CD4⁺ T cells, CD8⁺ T cells, B cells, macrophages and dendritic cells (DCs) have been detected in the pancreas of patients with LADA and a rat model of LADA. Therefore, similar to type 1 diabetes, the pathogenesis of LADA may be caused by interactions between islet β-cells and innate and adaptive immune cells. However, the role of the immunity in the initiation and progression of LADA remains largely unknown. In this review, we have summarized the potential roles of innate immunity and immune-modulators in LADA development. Furthermore, we have examined the evidence and discussed potential innate immunological reasons for the slower development of LADA compared with type 1 diabetes. More in-depth mechanistic studies are needed to fully elucidate the roles of innate immune-associated genes, molecules and cells in their contributions to LADA pathogenesis. Undertaking these studies will greatly enhance the development of new strategies and optimization of current strategies for the diagnosis and treatment of the disease.

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.

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.

Regulatory B Cells in Autoimmune Diabetes

Since they were discovered almost three decades ago, a subset of B cells denoted as regulatory B cells (Bregs) have elicited interest throughout the immunology community. Many investigators have sought to characterize their phenotype and to understand their function and immunosuppressive mechanisms. Indeed, studies in murine models have demonstrated that Bregs possess varied phenotypic markers and could be classified into different subsets whose action and pivotal role depend on the pathological condition or stimuli. Similar conclusions were drawn in clinical settings delineating an analogous Breg population phenotypically resembling the murine Bregs that ultimately may be associated with a state of tolerance. Recent studies suggested that Bregs may play a role in the onset of autoimmune diabetes. This review will focus on deciphering the different subclasses of Bregs, their emerging role in autoimmune diabetes, and their potential use as a cell-based therapeutic.

The critical roles of histone deacetylase 3 in the pathogenesis of solid organ injury

Histone deacetylase 3 (HDAC3) plays a crucial role in chromatin remodeling, which, in turn, regulates gene transcription. Hence, HDAC3 has been implicated in various diseases, including ischemic injury, fibrosis, neurodegeneration, infections, and inflammatory conditions. In addition, HDAC3 plays vital roles under physiological conditions by regulating circadian rhythms, metabolism, and development. In this review, we summarize the current knowledge of the physiological functions of HDAC3 and its role in organ injury. We also discuss the therapeutic value of HDAC3 in various diseases.

CD5-expressing CD8+ T-cell subsets differ between children with type 1 diabetes and controls

Different lymphocyte subsets are involved in autoimmune pathogenesis of type 1 diabetes (T1D). Previous studies suggested a role of CD5-expressing T and B cells including rare unconventional lymphocytes with combined T- and B-cell features [dual expressing (DE) cells]. We performed algorithm-supported multiparameter flow cytometry and quantitative PCR to investigate immune cell subsets and DE cells in children with T1D (n = 20) and matched controls (n = 20). Comparisons of conventional immune cells detected increased proportions of CD3⁺ T cells in T1D patients, whereas CD19⁺ B-cell proportions were comparable to controls. Self-organizing maps for flow cytometry analyses (FlowSOM) showed highly similar CD5-expressing B-cell subsets and no differences for DE cells were detected between the study groups by flow cytometry or specific quantitative PCR. Notably, differences in CD8⁺ T cells were indicated by FlowSOM and similarity-based t-distributed stochastic neighbor embedding (tSNE) analyses. Study group comparisons confirmed significantly reduced CD8⁺ T-cell proportions with moderate or low CD5 expression in T1D patients. Finally, in vitro experiments showed stable CD5 expression differences of CD8⁺ T cells after T-cell activation, cytokine stimulation and culture. We observed differences of T-cell coreceptor CD5 expression in T1D patients with potential relevance for immune regulation of CD8⁺ T-cell activation.

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.

Phenotypes, roles, and modulation of regulatory lymphocytes in periodontitis and its associated systemic diseases

Periodontitis is a common chronic inflammatory disease that can result in tooth loss and poses a risk to systemic health. Lymphocytes play important roles in periodontitis through multiple mechanisms. Regulatory lymphocytes including regulatory B cells (Bregs) and T cells (Tregs) are the main immunosuppressive cells that maintain immune homeostasis, and are critical to our understanding of the pathogenesis of periodontitis and the development of effective treatments. In this review, we discuss the phenotypes, roles, and modulating strategies of regulatory lymphocytes including Bregs and Tregs in periodontitis and frequently cooccurring inflammatory diseases such as rheumatoid arthritis, Alzheimer disease, diabetes mellitus, and stroke. The current evidence suggests that restoring immune balance through therapeutic targeting of regulatory lymphocytes is a promising strategy for the treatment of periodontitis and other systemic inflammatory diseases.

B regulatory cells associated with changes in biochemical and inflammatory parameters in normal-glycemic individuals, pre-diabetes and T2DM patients

AIM

To determine the percentages of (CD19 + CD24 + CD38+, CD19 + CD24 + CD27+, CD19 + IL-10+)-Breg cells, IL-17 single and IL-17+/IFN-γ double producers T cells and IFN-γ+ T cells, in normal-glycemic individuals, prediabetes and T2DM patients, and to analyze the association of Breg cells with metabolic parameters of T2DM.

METHODS

percentages of Breg cells, IL-17+ and IL-17 + IFN-γ+ T cells, IFN-γ+ T cells and IL-10 were determined by flow cytometry. IL-6 levels were evaluated by ELISA assay.

RESULTS

increased IL-6 levels, IL-17+ and IL-17 + IFN-γ+ T cells and a diminution of IL-10 levels and CD19 + IL-10+ cells in T2DM patients were observed. We found that CD19 + CD24 + CD27+ cells and CD19 + CD24 + CD38+ cells were increased in T2DM patients. The percentages of CD19 + CD24 + CD38+ cells were associated with HOMA-B, TyG index, HDL and cholesterol values. In normal-glycemic individuals, CD19 + CD24 + CD27+ cells were inversely associated to triglycerides and TyG index. In prediabetes patients, CD19 + CD24 + CD38+ cells were inversely related with cholesterol and LDL. Finally, CD19 + CD24 + CD38+ cells were inversely related with HDL values in T2DM patients.

CONCLUSION

Our results suggest that increased percentages of IL-17 single and IL-17/IFN-γ double producers T cells in T2DM patients may be a consequence of the initial CD19 + IL-10+ cells reduction. Furthermore, dyslipidemia could play an important role in percentages and activity of B regulatory cells.

Why Is COVID-19 More Severe in Patients With Diabetes? The Role of Angiotensin-Converting Enzyme 2, Endothelial Dysfunction and the Immunoinflammatory System

Meta-analyses have indicated that individuals with type 1 or type 2 diabetes are at increased risk of suffering a severe form of COVID-19 and have a higher mortality rate than the non-diabetic population. Patients with diabetes have chronic, low-level systemic inflammation, which results in global cellular dysfunction underlying the wide variety of symptoms associated with the disease, including an increased risk of respiratory infection. While the increased severity of COVID-19 amongst patients with diabetes is not yet fully understood, the common features associated with both diseases are dysregulated immune and inflammatory responses. An additional key player in COVID-19 is the enzyme, angiotensin-converting enzyme 2 (ACE2), which is essential for adhesion and uptake of virus into cells prior to replication. Changes to the expression of ACE2 in diabetes have been documented, but they vary across different organs and the importance of such changes on COVID-19 severity are still under investigation. This review will examine and summarise existing data on how immune and inflammatory processes interplay with the pathogenesis of COVID-19, with a particular focus on the impacts that diabetes, endothelial dysfunction and the expression dynamics of ACE2 have on the disease severity.

Toll-like receptor 7 deficiency suppresses type 1 diabetes development by modulating B-cell differentiation and function

Innate immunity mediated by Toll-like receptors (TLRs), which can recognize pathogen molecular patterns, plays a critical role in type 1 diabetes development. TLR7 is a pattern recognition receptor that senses single-stranded RNAs from viruses and host tissue cells; however, its role in type 1 diabetes development remains unclear. In our study, we discovered that Tlr7-deficient (Tlr7-/-) nonobese diabetic (NOD) mice, a model of human type 1 diabetes, exhibited a significantly delayed onset and reduced incidence of type 1 diabetes compared with Tlr7-sufficient (Tlr7+/+) NOD mice. Mechanistic investigations showed that Tlr7 deficiency significantly altered B-cell differentiation and immunoglobulin production. Moreover, Tlr7-/- NOD B cells were found to suppress diabetogenic CD4+ T-cell responses and protect immunodeficient NOD mice from developing diabetes induced by diabetogenic T cells. In addition, we found that Tlr7 deficiency suppressed the antigen-presenting functions of B cells and inhibited cytotoxic CD8+ T-cell activation by downregulating the expression of both nonclassical and classical MHC class I (MHC-I) molecules on B cells. Our data suggest that TLR7 contributes to type 1 diabetes development by regulating B-cell functions and subsequent interactions with T cells. Therefore, therapeutically targeting TLR7 may prove beneficial for disease protection.

The Multiple Roles of B Lymphocytes in the Onset and Treatment of Type 1 Diabetes: Interactions between B Lymphocytes and T Cells

Although type 1 diabetes is thought to be an organ-specific autoimmune disease, mediated by effective CD4⁺ and CD8⁺ T cells, it has recently become clear that B cells participate in the initiation and progress of this disease. Indeed, B cell deletion can prevent or reverse autoimmune diabetes in nonobese diabetic mice and even result in partially remaining β cell function in patients with new-onset type 1 diabetes. This review summarizes the dual role of B cells in this process not only of pathogenic effect but also of immunoregulatory function in type 1 diabetes. We focus on the impact that B cells have on regulating the activation, proliferation, and cytokine production of self-reactive T cells along with regulatory T cells, with the aim of providing a better understanding of the interactions between T and B cells in immunopathogenesis and improving the efficacy of interventions for clinical practice.

Comprehensive Analyses of Type 1 Diabetes Ketosis- or Ketoacidosis-Related Genes in Activated CD56+CD16+ NK Cells

OBJECTIVES

Alterations in natural killer (NK) cells activity cause damage to pancreatic islets in type 1 diabetes mellitus (T1DM). The aim of this study is to identify T1DM ketosis- or ketoacidosis-related genes in activated CD56⁺CD16⁺ NK cells.

METHODS

Microarray datasets were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were analyzed using the GEO2R tool. Enrichment analyses were performed using Metascape online database and GSEA software. Cell-specific gene co-expression network was built using NetworkAnalyst tools. Cytoscape software was used to identify hub genes and construct co-expressed networks. Target miRNAs were predicted based on the DIANA-micro T, miRDB, and miRWalk online databases.

RESULTS

A total of 70 DEGs were identified between T1DM patients recovered from ketosis or ketoacidosis and healthy control blood samples in GSE44314. Among the DEGs, 10 hub genes were screened out. The mature NK cell-specific gene co-expression network for DEGs in T1DM was built using NetworkAnalyst tools. DEGs between activated CD56⁺CD16⁺ NK cells and CD56^brightCD16^- NK cells were identified from GSE1511. After intersection, 13 overlapping genes between GSE44314 and GSE1511 microarray datasets were screened out, in which 7 hub genes were identified. Additionally, 59 target miRNAs were predicted according to the 7 hub genes. After validating with the exosome miRNA expression profile dataset of GSE97123, seven differentially expressed miRNAs (DEmiRNAs) in plasma-derived exosome were selected. Finally, a mRNA-miRNA network was constructed, which was involved in the T1DM ketosis or ketoacidosis process.

CONCLUSION

This work identified seven hub genes in activated CD56⁺CD16⁺ NK cells and seven miRNAs in plasma-derived exosome as potential predictors of T1DM ketoacidosis, which provided a novel insight for the pathogenesis at the transcriptome level.

Altered Systemic and Intestinal IgA Immune Responses in Individuals With Type 1 Diabetes

OBJECTIVE

Increasing evidence supports the observation that immunoglobulin A (IgA) exerts a critical effect on the susceptibility to autoimmunity by modulating gut homeostasis and subsequent host immunity. We hypothesized that the IgA immunity is altered in individuals with type 1 diabetes. To test our hypothesis, we investigated intestinal, oral, and peripheral IgA immune responses in individuals with type 1 diabetes.

METHODS

We collected stool, oral cavity, and blood samples from participants diagnosed with type 1 diabetes (within 1 year and more than 1 year) and healthy control individuals. Serum islet autoantibody titers were detected by radioligand assays. IgA-bound bacteria and IgA-expressing B cells were studied by flow cytometry. Oral free IgA level was measured by enzyme-linked immunosorbent assay. Serum and stool free IgA concentrations were determined by immune-turbidimetry method.

RESULTS

Individuals diagnosed with type 1 diabetes within 1 year had an increased proportion of stool IgA-bound bacteria compared with healthy control individuals. The proportion of stool IgA-bound bacteria was positively associated with glutamic acid decarboxylase autoantibody titer. Moreover, individuals with a longer disease duration displayed a higher level of IgA-bound bacteria than those diagnosed within 1 year. In contrast to healthy control individuals, type 1 diabetes patients had increased serum IgA concentrations.

CONCLUSIONS

Individuals with type 1 diabetes display altered IgA immunity, especially increased stool IgA-bound bacteria, which is likely to contribute to β-cell autoimmunity and the disease development, and thus, might be considered as a novel therapeutic target for the treatment of type 1 diabetes.

Histone Deacetylase 3 Aggravates Type 1 Diabetes Mellitus by Inhibiting Lymphocyte Apoptosis Through the microRNA-296-5p/Bcl-xl Axis

Type 1 diabetes mellitus (T1DM) is a chronic autoimmune disease characterized by immune-mediated destruction of pancreatic beta-cells. Multiple microRNAs (miRNAs) have been implicated in T1DM pathogenesis. Although histone deacetylase 3 (HDAC3) has been reported to be involved in T1DM, the underlying mechanisms remain to be further elucidated. This study was designed to investigate the potential regulatory role of Hdac3 on T1DM progression. The expression of miR-296-5p and B-cell leukemia-XL (BCL-XL) was determined using RT-qPCR and Western blot assay in peripheral blood mononuclear cells (PBMCs) of patients with T1DM, tumor necrosis factor-α (TNF-α)- and cycloheximide (CHX)-induced cell model, and streptozotocin (STZ)-induced rat model. The binding affinity between miR-296-5p and Bcl-xl was verified by using dual-luciferase reporter gene assay, and the binding between Hdac3 and the promoter region of miR-296-5p was validated using chromatin immunoprecipitation assay. Western blot analysis and flow cytometry were conducted to assess the apoptotic events of lymphocytes. miR-296-5p expression was downregulated while BCL-XL expression was upregulated in PBMCs of patients with T1DM. An adverse correlation was identified between miR-296-5p and Bcl-xl in mouse TE15 B lymphocytes. Bcl-xl was further validated to be targeted and negatively regulated by miR-296-5p in 293 T cells. Hdac3 inhibited miR-296-5p expression by binding to its promoter region. The effects of overexpressed Hdac3 on lymphocyte apoptosis was counterweighed via downregulation of Bcl-xl or upregulation of miR-296-5p, the mechanism of which was further validated in a rat model of DM. Taken together, the Hdac3-mediated upregulation of Bcl-xl via inhibiting miR-296-5p promoter activity enhanced the anti-apoptotic capacity of lymphocytes to accelerate the occurrence of T1DM.

Altered Regulatory B Cell Subsets in Children with Type 1 Diabetes Mellitus

B regulatory cells (Breg) refer to characteristic subsets of B cells that generally exert anti-inflammatory functions and maintain peripheral tolerance mainly through their ability to secrete interleukin-10 (IL10). Dysregulation in the function of Breg cells was reported in several autoimmune diseases. However, the relation between Breg and children with type 1 diabetes (T1D) is poorly understood. Thus, this study is aimed at determining whether Breg cells play a role in T1D in children or not, so we hypothesized that an altered phenotype of B cell subsets is associated with T1D in children. Children with T1D (n = 29) and control children with normal blood glucose levels (n = 14) were recruited. The percentages of different circulating IL10-producing Breg subsets, including B10, immature transitional, and plasmablasts were determined using flow cytometry analysis. Furthermore, the association between different IL10-producing B cells and patient parameters was investigated. The percentage of circulating IL10⁺CD24^hiCD27⁺ (B10) and IL10⁺CD24^hiCD38^hi (immature transitional) subsets of Breg cells was significantly lower in T1D patients than in healthy controls. Moreover, these cells were also negatively correlated with fasting blood glucose and HbA1c levels. Breg cells did not correlate with autoantibody levels in the serum. These findings suggest that certain Breg subsets are numerically deficient in children with T1D. This alteration in frequency is associated with deficient islet function and glycemia. These findings suggest that Breg cells may be involved in the loss of auto-tolerance and consequent destruction of pancreatic cells and could, therefore, be a potential target for immunotherapy.

Slow progressors to type 1 diabetes lose islet autoantibodies over time, have few islet antigen-specific CD8+ T cells and exhibit a distinct CD95hi B cell phenotype

AIMS/HYPOTHESIS

The aim of this study was to characterise islet autoantibody profiles and immune cell phenotypes in slow progressors to type 1 diabetes.

METHODS

Immunological variables were compared across peripheral blood samples obtained from slow progressors to type 1 diabetes, individuals with newly diagnosed or long-standing type 1 diabetes, and healthy individuals. Polychromatic flow cytometry was used to characterise the phenotypic attributes of B and T cells. Islet autoantigen-specific B cells were quantified using an enzyme-linked immunospot (ELISpot) assay and islet autoantigen-specific CD8⁺ T cells were quantified using peptide-HLA class I tetramers. Radioimmunoassays were used to detect islet autoantibodies. Sera were assayed for various chemokines, cytokines and soluble receptors via ELISAs.

RESULTS

Islet autoantibodies were lost over time in slow progressors. Various B cell subsets expressed higher levels of CD95 in slow progressors, especially after polyclonal stimulation, compared with the corresponding B cell subsets in healthy donors (p < 0.05). The phenotypic characteristics of CD4⁺ and CD8⁺ T cells were similar in slow progressors and healthy donors. Lower frequencies of CD4⁺ T cells with a central memory phenotype (CD27^int, CD127⁺, CD95^int) were observed in slow progressors compared with healthy donors (mean percentage of total CD4⁺ T cells was 3.00% in slow progressors vs 4.67% in healthy donors, p < 0.05). Autoreactive B cell responses to proinsulin were detected at higher frequencies in slow progressors compared with healthy donors (median no. of spots was 0 in healthy donors vs 24.34 in slow progressors, p < 0.05) in an ELISpot assay. Islet autoantigen-specific CD8⁺ T cell responses were largely absent in slow progressors and healthy donors. Serum levels of DcR3, the decoy receptor for CD95L, were elevated in slow progressors compared with healthy donors (median was 1087 pg/ml in slow progressors vs 651 pg/ml in healthy donors, p = 0.06).

CONCLUSIONS/INTERPRETATION

In this study, we found that slow progression to type 1 diabetes was associated with a loss of islet autoantibodies and a distinct B cell phenotype, consistent with enhanced apoptotic regulation of peripheral autoreactivity via CD95. These phenotypic changes warrant further studies in larger cohorts to determine their functional implications.

Crosstalk Between Immunity System Cells and Pancreas. Transformation of Stem Cells Used in the 3D Bioprinting Process as a Personalized Treatment Method for Type 1 Diabetes

Interactions between the immune system and the pancreas are pivotal in understanding how and why β cells' damage causes problems with pancreas functioning. Pancreatic islets are crucial in maintaining glucose homeostasis in organs, tissue and cells. Autoimmune aggression towards pancreatic islets, mainly β cells, leads to type 1 diabetes-one of the most prevalent autoimmune disease in the world, being a worldwide risk to health of many people. In this review, we highlight the role of immune cells and its influence in the development of autoimmunity in Langerhans islets. Moreover, we discuss the impact of the immunological factors on future understanding possible recurrence of autoimmunity on 3D-bioprinted bionic pancreas.

Changes in innate and adaptive immunity over the first year after the onset of type 1 diabetes

AIMS

The development of the immune phenotype in patients with type 1 diabetes (T1D) during the first year following disease onset remains poorly described, and studies analysing the longitudinal development of a complex set of immunological and metabolic parameters are missing. Thus, we aim to provide such complex view in a cohort of 38 children with new onset T1D who were prospectively followed for 1 year.

METHODS

All subjects were tested for a set of immunological parameters (complete blood count; serum immunoglobulins; and T, B and dendritic cells), HbA1c and daily insulin dose at baseline and at 6 and 12 months after T1D diagnosis. A mixed meal tolerance test was administered to each of the subjects 12 months after diagnosis, and the C-peptide area under the curve (AUC) was noted and was then tested for association with all immunological parameters.

RESULTS

A gradual decrease in leukocytes (adjusted p = 0.0012) was reflected in a significant decrease in neutrophils (adjusted p = 0.0061) over the post-onset period, whereas Tregs (adjusted p = 0.0205) and originally low pDCs (adjusted p < 0.0001) increased. The expression of the receptor for BAFF (BAFFR) on B lymphocytes (adjusted p = 0.0127) markedly increased after onset. No immunological parameters were associated with C-peptide AUC; however, we observed a linear increase in C-peptide AUC with the age of the patients (p < 0.0001).

CONCLUSIONS

Our study documents substantial changes in the innate and adaptive immune system over the first year after disease diagnosis but shows no association between immunological parameters and residual beta-cell activity. The age of patients remains the best predictor of C-peptide AUC, whereas the role of the immune system remains unresolved.

Regulation of B cell homeostasis by Ptpn22 contributes to type 1 diabetes in NOD mice

PURPOSE

A coding variant in PTPN22 (C1858T) is one of the most important genetic risk factors in type 1 diabetes (T1D). The role of the PTPN22 risk allele in B cells is still incompletely understood and has not been investigated directly in T1D. This study aimed to explore the role of PTPN22 in the homeostasis of B cells and its influence in T1D.

METHODS

Wild-type (WT) and Ptpn22 inducible knockdown (KD) NOD mice were treated with 200 μg/ml doxycycline at the age of 10 weeks for 1-2 months. B cell compositions in the bone marrow, peritoneal cavity and spleen were examined. The pathogenicity of Ptpn22 KD B cells was explored by adoptive cell transfer.

RESULTS

Ptpn22 silencing increased the frequency of recirculating mature B cells in the bone marrow, decreased the frequency of B-1a cells in the peritoneal cavity and suppressed the formation of marginal zone B cells and plasma cells in the spleen. Changes in the composition of the peripheral B cell compartment caused by altered cell proliferation while rates of apoptosis were not affected. Significantly, co-transfer of Ptpn22 KD B cells with NY8.3 diabetogenic T cells diminished the frequency of diabetes in recipient NOD.scid mice compared with co-transfer of WT B cells.

CONCLUSIONS

Our study constitutes the first functional study of Ptpn22 in B cells in NOD mice. Our findings suggest that Ptpn22 variation contributes to T1D by modifying the B cell compartment and support a gain-of-function for the PTPN22 disease variant.

Distinct two different ages associated with clinical profiles of acute onset type 1 diabetes in Chinese patients

BACKGROUND

There are abundant variations in the phenotypes and genetics of type 1 diabetes (T1D) patients across different races. This study aimed to assess differences between juvenile acute onset (JAO) and adult acute onset in Chinese T1D patients.

METHODS

Seven hundred and fifty-one acute onset T1D patients were divided into two groups by the patient onset age as follows: the juvenile acute onset group (≤20 years, JAO group) and the adult acute onset group (>20 years, AAO group). Clinical characteristics, islet autoantibodies, and HLA class II haplotypes and genotypes were compared between these two groups.

RESULTS

In comparison with AAO patients, JAO patients had significantly lower relative weights and lower triglyceride levels (P < .001, P < .01, respectively) but higher frequency of ketoacidosis (P < .001), higher daily insulin dosage (P_c  < .001), higher HbA1_c (P_c  < .05), and higher HDL-cholesterol levels (P_c  < .01). The JAO group showed a higher prevalence of IA-2A, ZnT8A, and multiple autoantibodies than that in the AAO group (P < .001, P < .01, P < .001, respectively). Haplotypes for DRB1*0301-DQA1*03-DQB1*0201, DR3, DR4, DR9, and DR3/DR9 genotypes are highly associated with JAO susceptibility, whereas only DR3 and DR9 genotypes confer risk for AAO. In the JAO group but not the AAO group, DR3 is related to ZnT8A, and DR3/DR9 is related to IA-2A and multiple autoantibodies.

CONCLUSIONS

These observations suggest that JAO patients markedly differ from AAO patients in their clinical manifestations and genetics in the Chinese T1D population. Notably, the DR3/DR9 genotype can facilitate the appearance of IA-2A or multiple autoantibodies in JAO patients.

Blood Co-Circulating Extracellular microRNAs and Immune Cell Subsets Associate with Type 1 Diabetes Severity

Immune cell subsets and microRNAs have been independently proposed as type 1 diabetes (T1D) diagnostic and/or prognostic biomarkers. Here, we aimed to analyze the relationships between peripheral blood circulating immune cell subsets, plasmatic microRNAs, and T1D. Blood samples were obtained from both children with T1D at diagnosis and age-sex matched healthy controls. Then, immunophenotype assessed by flow cytometry was coupled with the quantification of 60 plasmatic microRNAs by quantitative RT-PCR. The associations between immune cell frequency, plasmatic microRNAs, and the parameters of pancreatic loss, glycemic control, and diabetic ketoacidosis were assessed by logistic regression models and correlation analyses. We found that the increase in specific plasmatic microRNAs was associated with T1D disease onset (let-7c-5p, let-7d-5p, let-7f-5p, let-7i-5p, miR-146a-5p, miR-423-3p, and miR-423-5p), serum C-peptide concentration (miR-142-5p and miR-29c-3p), glycated hemoglobin (miR-26a-5p and miR-223-3p) and the presence of ketoacidosis (miR-29c-3p) more strongly than the evaluated immune cell subset frequency. Some of these plasmatic microRNAs were shown to positively correlate with numbers of blood circulating B lymphocytes (miR-142-5p) and CD4⁺CD45RO⁺ (miR-146a-5p and miR-223-3p) and CD4⁺CD25⁺ cells (miR-423-3p and miR-223-3p) in children with T1D but not in healthy controls, suggesting a disease-specific microRNA association with immune dysregulation in T1D. In conclusion, our results suggest that, while blood co-circulating extracellular microRNAs and immune cell subsets may be biologically linked, microRNAs may better provide powerful information about T1D onset and severity.

Decrease in the proportion of CD24hi CD38hi B cells and impairment of their regulatory capacity in type 1 diabetes patients

B10 cells restore immune balance by producing interleukin (IL)-10. Impaired B10 cell responses are related to numerous autoimmune diseases. However, the function of B10 cells in type 1 diabetes (T1D) patients is controversial. We hypothesized that there are numerical and functional defects of B10 cells in T1D. Sixty-two patients with T1D and 74 healthy volunteers were included in our study. We showed that B10 cells in human peripheral blood belong to a CD24^hi CD38^hi B cell subpopulation. CD24^hi CD38^hi B cells from healthy individuals possessed regulatory capacity, suppressed interferon (IFN)-γ, tumor necrosis factor (TNF)-α and IL-17A production and promoted IL-4 production and forkhead box protein 3 (FoxP3) expression in CD4⁺ T cells through an IL-10-dependent mechanism. Compared to healthy controls, B10 cell percentages in T1D were significantly lower (5·6 ± 3·5 versus 6·9 ± 3·3%; P < 0·05), produced less IL-10 (15·4 ± 4·3 versus 29·0 ± 4·5%; P < 0·001) and lacked regulatory capacity. In addition, Pearson's correlation analysis showed that the frequency of circulating B10 cells was negatively correlated with the frequency of CD4⁺ IFN-γ⁺ and CD4⁺ TNF-α⁺ T cells (r = -0·248 and r = -0·283, P = 0·008 and P = 0·017, respectively), positively correlating with the frequency of CD4⁺ CD25⁺ FoxP3⁺ T cells (r = 0·247, P = 0·001). These data offer direct proof that there is a deficiency of circulating CD24^hi CD38^hi B cells in peripheral blood of patients with T1D, which participate in the T1D immune imbalance involved in the development of T1D.

Two to Tango: Dialogue between Adaptive and Innate Immunity in Type 1 Diabetes

Type 1 diabetes mellitus (T1DM) is a long-term and chronic autoimmune disorder, in which the immune system attacks the pancreatic β-cells. Both adaptive and innate immune systems are involved in T1DM development. Both B-cells and T-cells, including CD4 ⁺ and CD8 ⁺ T-cells, as well as other T-cell subsets, could affect onset of autoimmunity. Furthermore, cells involved in innate immunity, including the macrophages, dendritic cells, and natural killer (NK) cells, could also accelerate or decelerate T1DM development. In this review, the crosstalk and function of immune cells in the pathogenesis of T1DM, as well as the corresponding therapeutic interventions, are discussed.

Gene Expression Analysis of the Pre-Diabetic Pancreas to Identify Pathogenic Mechanisms and Biomarkers of Type 1 Diabetes

Type 1 Diabetes (T1D) occurs as a result of the autoimmune destruction of pancreatic β-cells by self-reactive T cells. The etiology of this disease is complex and difficult to study due to a lack of disease-relevant tissues from pre-diabetic individuals. In this study, we performed gene expression analysis on human pancreas tissues obtained from the Network of Pancreatic Organ Donors with Diabetes (nPOD), and showed that 155 genes were differentially expressed by ≥2-fold in the pancreata of autoantibody-positive (AA+) at-risk individuals compared to healthy controls. Only 48 of these genes remained changed by ≥2-fold in the pancreata of established T1D patients. Pathway analysis of these genes showed a significant association with various immune pathways. We were able to validate the differential expression of eight disease-relevant genes by QPCR analysis: A significant upregulation of CADM2, and downregulation of TRPM5, CRH, PDK4, ANGPL4, CLEC4D, RSG16, and FCGR2B was confirmed in the pancreata of AA+ individuals versus controls. Studies have already implicated FCGR2B in the pathogenesis of disease in non-obese diabetic (NOD) mice. Here we showed that CADM2, TRPM5, PDK4, and ANGPL4 were similarly changed in the pancreata of pre-diabetic 12-week-old NOD mice compared to NOD.B10 controls, suggesting a possible role for these genes in the pathogenesis of both T1D and NOD disease. The loss of the leukocyte-specific gene, FCGR2B, in the pancreata of AA+ individuals, is particularly interesting, as it may serve as a potential whole blood biomarker of disease progression. To test this, we quantified FCGR2B expression in peripheral blood samples of T1D patients, and AA+ and AA- first-degree relatives of T1D patients enrolled in the TrialNet Pathway to Prevention study. We showed that FCGR2B was significantly reduced in the peripheral blood of AA+ individuals compared to AA- controls. Together, these findings demonstrate that gene expression analysis of pancreatic tissue and peripheral blood samples can be used to identify disease-relevant genes and pathways and potential biomarkers of disease progression in T1D.

Past, present and future of latent autoimmune diabetes in adults

Latent autoimmune diabetes in adults (LADA) is the most common form of autoimmune diabetes diagnosed in adults. Similar to type 1 diabetes, the prevalence of LADA is impacted by ethnicity and geography. LADA is characterized by β cell loss due to autoimmunity and insulin resistance and has highly heterogeneous clinical features, autoimmunity, and genetics in a glutamic acid decarboxylase antibody (GADA) titre-dependent manner, suggesting LADA is part of a continuum spectrum between type 1 and type 2 diabetes. Although LADA is the most frequent form of autoimmune diabetes diagnosed in adults, clinical trials involving LADA are scarce. Here we review the recent advancements in LADA epidemiology, clinical features, pathogenesis, and interventions. We also highlight the environmental factors that are thought to play an important role in addition to genetics in the pathogenesis of LADA. In the future, high-throughput molecular profiles might shed light on the nature of LADA among the wide spectrum of diabetes and offer new opportunities to identify novel LADA-specific biomarkers.

IL-10-producing regulatory B cells exhibit functional defects and play a protective role in severe endotoxic shock

Dysregulated host immune homeostasis in sepsis is life-threatening even after a successfully treated bacterial infection. Lipopolysaccharide (LPS) is an endotoxin that is a major contributor to the aberrant immune responses and endotoxic shock in gram-negative bacterial sepsis. However, the current knowledge of the role of B cells in endotoxic shock is limited. Here, we report that CD1d expression in B cells and the percentage of CD5⁺CD1d^hi regulatory B (Breg) cells decreased in a mouse model of endotoxic shock. Interestingly, IL-10 but not FasL expression in CD5⁺CD1d^hi Breg cells in response to endotoxin was dramatically reduced in severe septic shock mice, and the regulatory function of CD5⁺CD1d^hi Breg cells in vitro to control the Th1 response was also diminished. Adoptive transfer of CD5⁺CD1d^hi Breg cells from healthy WT mice but not IL-10 deficient mice downregulated the IFN-γ secretion in CD4⁺ T cells and conferred protection against severe endotoxic shock in vivo. Our findings demonstrate the change and notable therapeutic potential of IL-10-producing Breg cells in endotoxic shock.

Phenotypic identification of CD19+CD5+CD1d+ regulatory B cells that produce interleukin 10 and transforming growth factor β1 in human peripheral blood

INTRODUCTION

Regulatory B cells (Bregs), a novel subpopulation of B cells, are a significant area of research due to their immune regulatory function in the immunological response. Bregs have been reported to regulate acute inflammation and immunity through the production of anti-inflammatory cytokines.

MATERIAL AND METHODS

A B cell subpopulation was identified using flow cytometric analysis in two different processes: 1) after preparation and storage of peripheral blood mononuclear cells (PBMCs) using Ficoll density gradient centrifugation from a human blood sample, 2) followed by isolation and storage of B cells through magnetic separation using a B cell isolation kit and MS column. ELISA assays were performed to observe the cytokine production of interkleukin 10 (IL-10) and transforming growth factor β₁ (TGF-β₁) by this novel B cell subpopulation.

RESULTS

Double positive staining of CD5+CD1d+ Bregs represents (19.27 ±1.52) from PBMCs, (33.32 ±2.95) from B cells accordingly (n = 40). Through ELISA assays, it has been found that B cell subpopulation produces IL-10 (0.56 ±0.08) and TGF-β₁ (0.90 ±0.12) (n = 40).

CONCLUSIONS

These methods should be able to facilitate progress in research on Bregs through the following steps: 1) the regulatory role may be observed in comparison with particular autoimmune diseases, inflammation, cancer, and immunologic responses to find out whether Breg alteration and/or cytokine production is altered as well in these disorders or conditions. 2) If the alteration of Bregs and cytokine production is significant along with the clinical correlation, a further in vitro study can be initiated with exposure of certain drugs to overcome the alteration of the cytokine production; then, an in vivo study can be initiated.

[Features of the development of latent autoimmune diabetes in adults (LADA)]

The study of the sociomedical problems of diabetes mellitus led to the discovery of latent autoimmune diabetes in adults (LADA), a special form of the disease. The slow onset of the disease, the clinical signs of type 2 diabetes mellitus concurrent with the autoantibody pancreatic β-cell destruction mechanism that is characteristic of type 1 diabetes. Genetic factors play an important role in the genesis of the disease. Insulitis concurrent with intact or hypertrophic islets of the gland originally develops morphologically. Subsequently, the phenomena of islet atrophy and sclerosis are progressive. The disease is typical for young people (generally those aged 25-35 years) with normal body mass index, low blood C-peptide levels, with antibodies against β-cells, primarily to glutamate decarboxylase, being detected. Insulin preparations should be used to treat these patients.