The role of TNF-alpha in the pathogenesis of type 1 diabetes in the nonobese diabetic mouse: analysis of dendritic cell maturation

Identification of metabolism-related subtypes and feature genes of pre-eclampsia

The heterogeneity of pre-eclampsia (PE) complicates its pathogenesis, which remains incompletely understood. Emerging evidence indicates a significant role of metabolism in the pathophysiology of PE. We procured the PE dataset from the Gene Expression Omnibus database and sourced a published compilation of metabolism-related genes, then employed consensus clustering to classify PE subtypes. Subsequently, we examined the relationships of these subtypes with metabolic features and immune infiltration. Feature genes were identified using weighted gene co-expression network analysis (WGCNA) and further scrutinized through Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses. To refine the selection of feature genes, we applied two machine learning algorithms. Additionally, we assessed the expression profiles of RAG1, RBBP7, RFTN2, SPATA7, and ZNF16 at the single-cell RNA sequencing (scRNA-seq) level. Finally, we validated the diagnostic value and expression of these genes using PE datasets and quantitative reverse transcription-PCR (qRT-PCR) analysis. We identified three PE subtypes on the basis of the number of distinct metabolic characteristics, namely Metabolism Correlated (MC) A (MCA), MCB, and MCC subclasses. Through WGCNA, we pinpointed 101 metabolic genes that were strongly associated with PE progression. Machine learning algorithms helped to narrow the list to five key signature genes, which were then used to construct a predictive model offering significant clinical benefits for PE patients. qRT-PCR analysis confirmed that these genes are closely linked to PE progression, while scRNA-seq data revealed high expression of RBBP7 in trophoblast cells. In conclusion, the five genes identified here-RAG1, RBBP7, RFTN2, SPATA7, and ZNF16-were found to be strongly associated with PE progression.

Dysfunctional β-cell autophagy induces β-cell stress and enhances islet immunogenicity

Background

Type 1 Diabetes (T1D) is caused by a combination of genetic and environmental factors that trigger autoimmune-mediated destruction of pancreatic β-cells. Defects in β-cell stress response pathways such as autophagy may play an important role in activating and/or exacerbating the immune response in disease development. Previously, we discovered that β-cell autophagy is impaired prior to the onset of T1D, implicating this pathway in T1D pathogenesis.

Aims

To assess the role of autophagy in β-cell health and survival, and whether defects in autophagy render islets more immunogenic.

Methods

We knocked out the critical autophagy enzyme, ATG7, in the β-cells of mice (ATG7Δβ-cell) then monitored blood glucose, performed glucose tolerance tests, and evaluated bulk islet mRNA and protein. We also assessed MHC-I expression and presence of CD45+ immune cells in ATG7Δβ-cell islets and evaluated how impaired autophagy affects EndoC-βH1 HLA-I expression under basal and IFNα stimulated conditions. Lastly, we co-cultured ATG7Δβ-cell islet cells with diabetogenic BDC2.5 helper T cells and evaluated T cell activation.

Results

We found that all ATG7Δβ-cell mice developed diabetes between 11-15 weeks of age. Gene ontology analysis revealed a significant upregulation of pathways involved in inflammatory processes, response to ER stress, and the ER-associated degradation pathway. Interestingly, we also observed upregulation of proteins involved in MHC-I presentation, suggesting that defective β-cell autophagy may alter the immunopeptidome, or antigen repertoire, and enhance β-cell immune visibility. In support of this hypothesis, we observed increased MHC-I expression and CD45+ immune cells in ATG7Δβ-cell islets. We also demonstrate that HLA-I is upregulated in EndoC β-cells when autophagic degradation is inhibited. This effect was observed under both basal and IFNα stimulated conditions. Conversely, a stimulator of lysosome acidification/function, C381, decreased HLA-I expression. Lastly, we showed that in the presence of islet cells with defective autophagy, there is enhanced BDC2.5 T cell activation.

Conclusions

Our findings demonstrate that β-cell autophagy is critical to cell survival/function. Defective β-cell autophagy induces ER stress, alters pathways of antigen production, and enhances MHC-I/HLA-I presentation to surveilling immune cells. Overall, our results suggest that defects in autophagy make β-cells more susceptible to immune attack and destruction.

Evaluation of miRNA-146a, miRNA-34a, and pro-inflammatory cytokines as a potential early indicators for type 1 diabetes mellitus

Background

Type I diabetes mellitus (T1DM) is one of the most common chronic autoimmune diseases worldwide. miRNAs are a class of small non-coding RNA molecules that have been linked to immune system functions, β-cell metabolism, proliferation, and death, all of which contribute to pathogenesis of TIDM. Dysregulated miRNAs have been identified in Egyptian TIDM patients.

Aim

Several miRNAs were profiled in Egyptian TIDM patients to determine whether they can be used as molecular biomarkers for T1DM. The relationship between the investigated miRNAs and pro-inflammatory cytokines (TNF-α and IL-6) has also been evaluated in the development of TIDM, in addition to the creation of a proposed model for TIDM prediction.

Patients & methods

Case-control study included 177 Egyptian patients with confirmed type I diabetes mellitus and 177 healthy individuals. MiRNA-34 and miRNA-146 were detected in serum samples using real-time PCR, whereas TNF-α and IL-6 levels were assessed using ELIZA.

Results

Patients with TIDM showed a significant decrease in the expression of miRNA-146, with a cut-off value ≤ 3.3, 48 % specificity, and 92.1 % sensitivity, whereas miRNA-34 had the highest sensitivity (95.5 %) and specificity (97.2 %) for differentiating diabetic patients from controls. Furthermore, other diagnostic proinflammatory markers showed lower sensitivity and specificity.

Conclusion

Serum levels of miRNA-34a, miRNA-146, IL-6, and TNF-α provide new insights into T1DM pathogenesis and could be used for screening and diagnosis purposes. They can be also a potential therapeutic target, as well as allowing for more strategies to improve T1DM disease outcomes.

Selective Reduction of Ca2+-Independent Phospholipase A2β (iPLA2β)-Derived Lipid Signaling From Macrophages Mitigates Type 1 Diabetes Development

Type 1 diabetes (T1D) is a consequence of autoimmune destruction of β-cells, and macrophages (MΦs) have a central role in initiating processes that lead to β-cell demise. We reported that Ca2+-independent phospholipase A2β (iPLA2β)-derived lipid (iDL) signaling contributes to β-cell death. Because MΦs express iPLA2β, we assessed its role in T1D development. We find that selective reduction of myeloid-iPLA2β in spontaneously diabetes-prone NOD mice 1) decreases proinflammatory eicosanoid production by MΦs, 2) favors the anti-inflammatory (M2-like) MΦ phenotype, and 3) diminishes activated CD4+ and CD8+ T-cells phenotype in the pancreatic infiltrate, prior to T1D onset. These outcomes are associated with a significant reduction in T1D. Further, inhibition of select proinflammatory lipid signaling pathways reduces M1-like MΦ polarization and adoptive transfer of M2-like MΦs reduces NOD T1D incidence, suggesting a mechanism by which iDLs impact T1D development. These findings identify MΦ-iPLA2β as a critical contributor to T1D development and potential target to counter T1D onset.

ARTICLE HIGHLIGHTS

Monocarbonyl analogs of curcumin C66 and B2BrBC modulate oxidative stress, JNK activity, and pancreatic gene expression in rats with streptozotocin-induced diabetes

The pathogenesis of type 1 diabetes mellitus (T1DM) involves oxidative stress and inflammation. Curcumin, a natural polyphenolic compound found in turmeric, known to exhibit antioxidative and anti-inflammatory properties, is characterized by poor chemical stability, low bioavailability, and rapid metabolism. Monocarbonyl analogs of curcumin (MACs) with a structural absence of β-diketone and enhanced stability and bioavailability present a potential solution to the challenges associated with the use of curcumin. This study aimed to evaluate the effect of two MACs, C66 and B2BrBC, on oxidative stress markers, antioxidant enzyme activity, expression of diabetes-associated genes, and signaling pathway proteins in the context of T1DM. Streptozotocin (STZ)-induced male Wistar rats or rat pancreatic RIN-m cells were used for in vivo and in vitro experiments, respectively. C66 or B2BrBC were given either before or after STZ treatment. Oxidative stress markers and antioxidant enzyme activities were determined in various tissues. Expression of diabetes-associated genes was assessed using RT-qPCR, and the activity of signaling pathway proteins in the pancreas was determined through Western blot analysis. Treatment with C66 and B2BrBC significantly reduced oxidative stress markers and positively influenced antioxidant enzyme activities. Moreover, both compounds inhibited JNK activity in the pancreas while enhancing the expression of genes crucial for β-cell survival and glucose and redox homeostasis. The findings highlight the multifaceted potential of C66 and B2BrBC in ameliorating oxidative stress, influencing gene expression patterns linked to diabetes, and modulating key signaling pathways in the pancreas. The findings suggest that these compounds can potentially address diabetes-related pathological processes.

Mucosal Addressin Cell Adhesion Molecule-1 Mediates T Cell Migration into Pancreas-Draining Lymph Nodes for Initiation of the Autoimmune Response in Type 1 Diabetes

Type 1 diabetes (T1D) is an autoimmune disease that is caused by autoreactive T cell-mediated destruction of insulin-producing β cells in the pancreatic islets. Although naive autoreactive T cells are initially primed by islet antigens in pancreas-draining lymph nodes (pan-LNs), the adhesion molecules that recruit T cells into pan-LNs are unknown. We show that high endothelial venules in pan-LNs of young nonobese diabetic mice have a unique adhesion molecule profile that includes strong expression of mucosal addressin cell adhesion molecule-1 (MAdCAM-1). Anti-MAdCAM-1 antibody blocked more than 80% of the migration of naive autoreactive CD4+ T cells from blood vessels into pan-LNs. Transient blockade of MAdCAM-1 in young nonobese diabetic mice led to increased numbers of autoreactive regulatory CD4+ T cells in pan-LNs and pancreas and to long-lasting protection from T1D. These results indicate the importance of MAdCAM-1 in the development of T1D and suggest MAdCAM-1 as a potential therapeutic target for treating T1D.

TNF-α inhibitors for type 1 diabetes: exploring the path to a pivotal clinical trial

Type 1 diabetes (T1D) is an autoimmune disease characterized by the destruction of insulin-producing β-cells in the pancreas. This destruction leads to chronic hyperglycemia, necessitating lifelong insulin therapy to manage blood glucose levels. Typically diagnosed in children and young adults, T1D can, however, occur at any age. Ongoing research aims to uncover the precise mechanisms underlying T1D and to develop potential interventions. These include efforts to modulate the immune system, regenerate β-cells, and create advanced insulin delivery systems. Emerging therapies, such as closed-loop insulin pumps, stem cell-derived β-cell replacement and disease-modifying therapies (DMTs), offer hope for improving the quality of life for individuals with T1D and potentially moving towards a cure. Currently, there are no disease-modifying therapies approved for stage 3 T1D. Preserving β-cell function in stage 3 T1D is associated with better clinical outcomes, including lower HbA1c and decreased risk of hypoglycemia, neuropathy, and retinopathy. Tumor Necrosis Factor alpha (TNF-α) inhibitors have demonstrated efficacy at preserving β-cell function by measurement of C-peptide in two clinical trials in people with stage 3 T1D. However, TNF-α inhibitors have yet to be evaluated in a pivotal trial for T1D. To address the promising clinical findings of TNF-α inhibitors in T1D, Breakthrough T1D convened a panel of key opinion leaders (KOLs) in the field. The workshop aimed to outline an optimal clinical path for moving TNF-α inhibitors to a pivotal clinical trial in T1D. Here, we summarize the evidence for the beneficial use of TNF-α inhibitors in T1D and considerations for strategies collectively identified to advance TNF-α inhibitors beyond phase 2 clinical studies for stage 3 T1D.

Inflammation-oriented montmorillonite adjuvant enhanced oral delivery of anti-TNF-α nanobody against inflammatory bowel disease

Oral delivery of proteins faces challenges due to the harsh conditions of the gastrointestinal (GI) tract, including gastric acid and intestinal enzyme degradation. Permeation enhancers are limited in their ability to deliver proteins with high molecular weight and can potentially cause toxicity by opening tight junctions. To overcome these challenges, we propose the use of montmorillonite (MMT) as an adjuvant that possesses both inflammation-oriented abilities and the ability to regulate gut microbiota. This adjuvant can be used as a universal protein oral delivery technology by fusing with advantageous binding amino acid sequences. We demonstrated that anti-TNF-α nanobody (VII) can be intercalated into the MMT interlayer space. The carboxylate groups (-COOH) of aspartic acid (D) and glutamic acid (E) interact with the MMT surface through electrostatic interactions with sodium ions (Na+). The amino groups (NH2) of asparagine (N) and glutamine (Q) are primarily attracted to the MMT layers through hydrogen bonding with oxygen atoms on the surface. This binding mechanism protects VII from degradation and ensures its release in the intestinal tract, as well as retaining biological activity, leading to significantly enhanced therapeutic effects on colitis. Furthermore, VII@MMT increases the abundance of short-chain fatty acids (SCFAs)-producing strains, including Clostridia, Prevotellaceae, Alloprevotella, Oscillospiraceae, Clostridia_vadinBB60_group, and Ruminococcaceae, therefore enhance the production of SCFAs and butyrate, inducing regulatory T cells (Tregs) production to modulate local and systemic immune homeostasis. Overall, the MMT adjuvant provides a promising universal strategy for protein oral delivery by rational designed protein.

Interferons are key cytokines acting on pancreatic islets in type 1 diabetes

AIMS/HYPOTHESIS

The proinflammatory cytokines IFN-α, IFN-γ, IL-1β and TNF-α may contribute to innate and adaptive immune responses during insulitis in type 1 diabetes and therefore represent attractive therapeutic targets to protect beta cells. However, the specific role of each of these cytokines individually on pancreatic beta cells remains unknown.

METHODS

We used deep RNA-seq analysis, followed by extensive confirmation experiments based on reverse transcription-quantitative PCR (RT-qPCR), western blot, histology and use of siRNAs, to characterise the response of human pancreatic beta cells to each cytokine individually and compared the signatures obtained with those present in islets of individuals affected by type 1 diabetes.

RESULTS

IFN-α and IFN-γ had a greater impact on the beta cell transcriptome when compared with IL-1β and TNF-α. The IFN-induced gene signatures have a strong correlation with those observed in beta cells from individuals with type 1 diabetes, and the level of expression of specific IFN-stimulated genes is positively correlated with proteins present in islets of these individuals, regulating beta cell responses to 'danger signals' such as viral infections. Zinc finger NFX1-type containing 1 (ZNFX1), a double-stranded RNA sensor, was identified as highly induced by IFNs and shown to play a key role in the antiviral response in beta cells.

CONCLUSIONS/INTERPRETATION

These data suggest that IFN-α and IFN-γ are key cytokines at the islet level in human type 1 diabetes, contributing to the triggering and amplification of autoimmunity.

The Relationship between Type 1 Diabetes Mellitus, TNF-α, and IL-10 Gene Expression

Type 1 diabetes mellitus (T1DM) is one of the major chronic diseases in children worldwide. This study aimed to investigate interleukin-10 (IL-10) gene expression and tumor necrosis factor-alpha (TNF-α) in T1DM. A total of 107 patients were included, 15 were T1DM in ketoacidosis, 30 patients had T1DM and HbA1c ≥ 8%; 32 patients had T1DM and presented HbA1c < 8%; and 30 were controls. The expression of peripheral blood mononuclear cells was performed using the reverse transcriptase-polymerase chain reaction in real time. The cytokines gene expression was higher in patients with T1DM. The IL-10 gene expression increased substantially in patients with ketoacidosis, and there was a positive correlation with HbA1c. A negative correlation was found for IL-10 expression and the age of patients with diabetes, and the time of diagnosis of the disease. There was a positive correlation between TNF-α expression with age. The expression of IL-10 and TNF-α genes showed a significant increase in DM1 patients. Once current T1DM treatment is based on exogenous insulin, there is a need for other therapies, and inflammatory biomarkers could bring new possibilities to the therapeutic approach of the patients.

Two-Year Follow-up From the T1GER Study: Continued Off-Therapy Metabolic Improvements in Children and Young Adults With New-Onset T1D Treated With Golimumab and Characterization of Responders

OBJECTIVE

The T1GER (A Study of SIMPONI to Arrest β-Cell Loss in Type 1 Diabetes) study showed many metabolic benefits of the tumor necrosis factor-α blocker golimumab in children and young adults with type 1 diabetes (T1D). Off-therapy effects are reported.

RESEARCH DESIGNS AND METHODS

T1GER was a phase 2, placebo-controlled, randomized trial in which golimumab or placebo was administered for 52 weeks to participants 6-21 years old diagnosed with T1D within 100 days of randomization. Assessments occurred during the 52-week on-therapy and 52-week off-therapy periods.

RESULTS

After treatment was stopped, C-peptide area under the curve (AUC) remained greater in the treatment versus control group. At weeks 78 and 104, the golimumab group had lower reductions in the 4-h C-peptide AUC baseline than the placebo group, where specifically the golimumab group had reductions of 0.31 and 0.41 nmol/L, and the placebo group had reductions of 0.64 and 0.74 nmol/L. There were also trends in less insulin use, higher peak C-peptide levels and those in partial remission, and higher peak C-peptide levels in the golimumab group. Golimumab responders, defined as having an increase or minimal loss of C-peptide AUC and/or being in partial remission at week 52, showed even greater improvements in most metabolic parameters on and off therapy and had less hypoglycemia during the off-therapy period versus placebo. Adverse events, including infections, were similar between the groups during all time periods of the study.

CONCLUSIONS

In children and young adults with new-onset T1D, golimumab preserved endogenous β-cell function and resulted in other favorable metabolic parameters on and off therapy. A subpopulation had disease stabilization while on therapy, with improved metabolic parameters off therapy.

Prenatal arsenic exposure induces immunometabolic alteration and renal injury in rats

Arsenic (As) exposure is progressively associated with chronic kidney disease (CKD), a leading public health concern present worldwide. The adverse effect of As exposure on the kidneys of people living in As endemic areas have not been extensively studied. Furthermore, the impact of only prenatal exposure to As on the progression of CKD also has not been fully characterized. In the present study, we examined the effect of prenatal exposure to low doses of As 0.04 and 0.4 mg/kg body weight (0.04 and 0.4 ppm, respectively) on the progression of CKD in male offspring using a Wistar rat model. Interestingly, only prenatal As exposure was sufficient to elevate the expression of profibrotic (TGF-β1) and proinflammatory (IL-1α, MIP-2α, RANTES, and TNF-α) cytokines at 2-day, 12- and 38-week time points in the exposed progeny. Further, alteration in adipogenic factors (ghrelin, leptin, and glucagon) was also observed in 12- and 38-week old male offspring prenatally exposed to As. An altered level of these factors coincides with impaired glucose metabolism and homeostasis accompanied by progressive kidney damage. We observed a significant increase in the deposition of extracellular matrix components and glomerular and tubular damage in the kidneys of 38-week-old male offspring prenatally exposed to As. Furthermore, the overexpression of TGF-β1 in kidneys corresponds with hypermethylation of the TGF-β1 gene-body, indicating a possible involvement of prenatal As exposure-driven epigenetic modulations of TGF-β1 expression. Our study provides evidence that prenatal As exposure to males can adversely affect the immunometabolism of offspring which can promote kidney damage later in life.

Exocrine pancreas regeneration modifies original pancreas to alleviate diabetes in mouse models

Diabetes is a major public health issue because of its widely epidemic nature and lack of cure. Here, we show that pancreas-derived mesenchymal stem cells (PMSCs) are capable of regenerating exocrine pancreas when implanted into the kidney capsule of mice with streptozotocin (STZ)-induced diabetes. Mechanistically, we found that the regenerated exocrine pancreas elevated interleukin-6 (IL-6) in PMSC implants, which transiently activated tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) to inhibit IL-17, thereby rescuing damaged exocrine pancreas and islet β cells. In addition, we used knockout mouse models to show that global lack of IL-6, TNF-α, or IFN-γ resulted in increased severity of STZ-induced diabetes and resistance to PMSC implantation therapy, confirming the roles of these factors in safeguarding pancreatic β cells. Furthermore, removal of the kidney capsule PMSC implants at 28 days after implantation did not affect the PMSC-initiated therapeutic effect on diabetic mice. This study reveals a previously unknown role of exocrine pancreas regeneration in safeguarding β cells and demonstrates a "soil-rescues-seed" strategy for type 1 diabetes therapy.

Lymphotoxins Serve as a Novel Orchestrator in T1D Pathogenesis

Type 1 diabetes (T1D) stems from pancreatic β cell destruction by islet reactive immune cells. Similar as other autoimmune disorders, there is no curative remedy for T1D thus far. Chronic insulitis is the hallmark of T1D, which creates a local inflammatory microenvironment that impairs β cell function and ultimately leads to β cell death. Immune regulation shows promise in T1D treatment by providing a time window for β cell recovery. However, due to the complex nature of T1D pathogenesis, the therapeutic effect of immune regulation is often short-lasting and unsatisfying in monotherapies. Lymphotoxins (LTs) were first identified in 1960s as the lymphocyte-producing cytokine that can kill other cell types. As a biological cousin of tumor necrosis factor alpha (TNFα), LTs play unique roles in T1D development. Herein in this review, we summarized the advancements of LTs in T1D pathogenesis. We particularly highlighted their effect on the formation of peri-islet tertiary lymphoid organs (TLOs), and discussed their synergistic effect with other cytokines on β cell toxicity and autoimmune progression. Given the complex and dynamic crosstalk between immune cells and β cells in T1D setting, blockade of lymphotoxin signaling applied to the existing therapies could be an efficient approach to delay or even reverse the established T1D.

Prenatal and early life factors and type 1 diabetes

BACKGROUND

The prevalence of type 1 diabetes is increasing worldwide, suggesting that unknown environmental factors are becoming increasingly important in its pathogenesis.

AIM

The aim of the study was to investigate the possible role of a number of prenatal and perinatal factors in the aetiology of type 1 diabetes.

METHODS

Mothers of patients diagnosed with type 1 diabetes (cases) and mothers of children born on the same day and of the same sex as type 1 diabetes patients (controls) were interviewed on a number of prenatal and perinatal factors of interest.

RESULTS

Hand washing prior to eating, frequency of bathing and total stress score were found to be positively associated with the development of type 1 diabetes on univariate analyses. Hand-washing prior to eating and frequency of house cleaning were independently associated with an increased risk of type 1 diabetes, whilst getting dirty was associated with a reduced risk in multivariate analyses. There was no association of type 1 diabetes to removing of outdoor shoes indoors or to the age of first attendance to school or pre-school. There were also no significant associations to parental smoking, parental age, birth order, infant feeding, antibiotic use, mode of delivery or birth weight.

CONCLUSION

Our data suggest that factors that affect the skin or gut microbiome might be more important than infections or factors affecting the microbiome at other sites.

Endosomal Sequestration of TLR4 Antibody Induces Myeloid-Derived Suppressor Cells and Reverses Acute Type 1 Diabetes

We previously showed that treating NOD mice with an agonistic monoclonal anti-TLR4/MD2 antibody (TLR4-Ab) reversed acute type 1 diabetes (T1D). Here, we show that TLR4-Ab reverses T1D by induction of myeloid-derived suppressor cells (MDSCs). Unbiased gene expression analysis after TLR4-Ab treatment demonstrated upregulation of genes associated with CD11b+Ly6G+ myeloid cells and downregulation of T-cell genes. Further RNA sequencing of purified, TLR4-Ab-treated CD11b+ cells showed significant upregulation of genes associated with bone marrow-derived CD11b+ cells and innate immune system genes. TLR4-Ab significantly increased percentages and numbers of CD11b+ cells. TLR4-Ab-induced CD11b+ cells, derived ex vivo from TLR4-Ab-treated mice, suppress T cells, and TLR4-Ab-conditioned bone marrow cells suppress acute T1D when transferred into acutely diabetic mice. Thus, the TLR4-Ab-induced CD11b+ cells, by the currently accepted definition, are MDSCs able to reverse T1D. To understand the TLR4-Ab mechanism, we compared TLR4-Ab with TLR4 agonist lipopolysaccharide (LPS), which cannot reverse T1D. TLR4-Ab remains sequestered at least 48 times longer than LPS within early endosomes, alters TLR4 signaling, and downregulates inflammatory genes and proteins, including nuclear factor-κB. TLR4-Ab in the endosome, therefore, induces a sustained, attenuated inflammatory response, providing an ideal "second signal" for the activation/maturation of MDSCs that can reverse acute T1D.

Plasma Exosome-Enriched Extracellular Vesicles From Lactating Mothers With Type 1 Diabetes Contain Aberrant Levels of miRNAs During the Postpartum Period

Type 1 diabetes is an immune-driven disease, where the insulin-producing beta cells from the pancreatic islets of Langerhans becomes target of immune-mediated destruction. Several studies have highlighted the implication of circulating and exosomal microRNAs (miRNAs) in type 1 diabetes, underlining its biomarker value and novel therapeutic potential. Recently, we discovered that exosome-enriched extracellular vesicles carry altered levels of both known and novel miRNAs in breast milk from lactating mothers with type 1 diabetes. In this study, we aimed to characterize exosomal miRNAs in the circulation of lactating mothers with and without type 1 diabetes, hypothesizing that differences in type 1 diabetes risk in offspring from these groups are reflected in the circulating miRNA profile. We performed small RNA sequencing on exosome-enriched extracellular vesicles extracted from plasma of 52 lactating mothers around 5 weeks postpartum (26 with type 1 diabetes and 26 age-matched controls), and found a total of 2,289 miRNAs in vesicles from type 1 diabetes and control libraries. Of these, 176 were differentially expressed in plasma from mothers with type 1 diabetes (167 upregulated; 9 downregulated, using a cut-off of abs(log2FC) >1 and FDR adjusted p-value <0.05). Extracellular vesicles were verified by nanoparticle tracking analysis, transmission electron microscopy and immunoblotting. Five candidate miRNAs were selected based on their involvement in diabetes and immune modulation/beta-cell functions: hsa-miR-127-3p, hsa-miR-146a-5p, hsa-miR-26a-5p, hsa-miR-24-3p and hsa-miR-30d-5p. Real-time qPCR validation confirmed that hsa-miR-146a-5p, hsa-miR-26a-5p, hsa-miR-24-3p, and hsa-miR-30d-5p were significantly upregulated in lactating mothers with type 1 diabetes as compared to lactating healthy mothers. To determine possible target genes and affected pathways of the 5 miRNA candidates, computational network-based analyses were carried out with TargetScan, mirTarBase, QIAGEN Ingenuity Pathway Analysis and PantherDB database. The candidates showed significant association with inflammatory response and cytokine and chemokine mediated signaling pathways. With this study, we detect aberrant levels of miRNAs within plasma extracellular vesicles from lactating mothers with type 1 diabetes during the postpartum period, including miRNAs with associations to disease pathogenesis and inflammatory responses.

Intestinal Region-Specific and Layer-Dependent Induction of TNFα in Rats with Streptozotocin-Induced Diabetes and after Insulin Replacement

Tumour necrosis factor alpha (TNFα) is essential in neuroinflammatory modulation. Therefore, the goal of this study is to reveal the effects of chronic hyperglycaemia and insulin treatment on TNFα expression in different gut segments and intestinal wall layers. TNFα expression was mapped by fluorescent immunohistochemistry and quantitative immunogold electron microscopy in myenteric ganglia of duodenum, ileum and colon. Tissue TNFα levels were measured by enzyme-linked immunosorbent assays in muscle/myenteric plexus-containing (MUSCLE-MP) and mucosa/submucosa/submucous plexus-containing (MUC-SUBMUC-SP) homogenates. Increasing density of TNFα-labelling gold particles is observed in myenteric ganglia from proximal to distal segments and TNFα tissue levels are much more elevated in MUSCLE-MP homogenates than in MUC-SUBMUC-SP samples in healthy controls. In the diabetics, the number of TNFα gold labels is significantly increased in the duodenum, decreased in the colon and remained unchanged in the ileal ganglia, while insulin does not prevent these diabetes-related TNFα changes. TNFα tissue concentration is also increased in MUSCLE-MP homogenates of diabetic duodenum, while decreased in MUC-SUBMUC-SP samples of diabetic ileum and colon. These findings support that type 1 diabetes has region-specific and intestinal layer-dependent effects on TNFα expression, contributing to the regional damage of myenteric neurons and their intestinal milieu.

Multicomponent Plasmid Protects Mice From Spontaneous Autoimmune Diabetes

Type 1 diabetes is an autoimmune disease in which insulin-secreting β-cells are destroyed, leading to a life-long dependency on exogenous insulin. There are no approved disease-modifying therapies available, and future immunotherapies would need to avoid generalized immune suppression. We developed a novel plasmid expressing preproinsulin2 and a combination of immune-modulatory cytokines (transforming growth factor-beta-1, interleukin [IL] 10 and IL-2) capable of near-complete prevention of autoimmune diabetes in non-obese diabetic mice. Efficacy depended on preproinsulin2, suggesting antigen-specific tolerization, and on the cytokine combination encoded. Diabetes suppression was achieved following either intramuscular or subcutaneous injections. Intramuscular plasmid treatment promoted increased peripheral levels of endogenous IL-10 and modulated myeloid cell types without inducing global immunosuppression. To prepare for first-in-human studies, the plasmid was modified to allow for selection without the use of antibiotic resistance; this modification had no impact on efficacy. This pre-clinical study demonstrates that this multi-component, plasmid-based antigen-specific immunotherapy holds potential for inducing self-tolerance in persons at risk of developing type 1 diabetes. Importantly, the study also informs on relevant cytokine and immune cell biomarkers that may facilitate clinical trials. This therapy is currently being tested for safety and tolerability in a phase 1 trial (ClinicalTrials.gov Identifier: NCT04279613).

Insights into the biology and therapeutic implications of TNF and regulatory T cells

Treatments that block tumour necrosis factor (TNF) have major beneficial effects in several autoimmune and rheumatic diseases, including rheumatoid arthritis. However, some patients do not respond to TNF inhibitor treatment and rare occurrences of paradoxical disease exacerbation have been reported. These limitations on the clinical efficacy of TNF inhibitors can be explained by the differences between TNF receptor 1 (TNFR1) and TNFR2 signalling and by the diverse effects of TNF on multiple immune cells, including FOXP3⁺ regulatory T cells. This basic knowledge sheds light on the consequences of TNF inhibitor therapies on regulatory T cells in treated patients and on the limitations of such treatment in the control of diseases with an autoimmune component. Accordingly, the next generation of drugs targeting TNF is likely to be based on agents that selectively block the binding of TNF to TNFR1 and on TNFR2 agonists. These approaches could improve the treatment of rheumatic diseases in the future.

Tumor Necrosis Factor Alpha Signaling and Organogenesis

Tumor necrosis factor alpha (TNF-α) plays important roles in processes such as immunomodulation, fever, inflammatory response, inhibition of tumor formation, and inhibition of viral replication. TNF-α and its receptors are ubiquitously expressed in developing organs and they regulate the survival, proliferation, and apoptosis of embryonic stem cells (ESCs) and progenitor cells. TNF-α is an important inflammatory factor that also regulates the inflammatory response during organogenesis, and its cytotoxic effects can interfere with normal developmental processes, even leading to the onset of diseases. This review summarizes the various roles of TNF-α in organogenesis in terms of its secreting pattern, concentration-dependent activities, and interactions with other signaling pathways. We also explored new potential functions of TNF-α.

Analysis of immune cell components and immune-related gene expression profiles in peripheral blood of patients with type 1 diabetes mellitus

BACKGROUND

Type 1 diabetes mellitus (T1DM) is a chronic autoimmune disease caused by severe loss of pancreatic β cells. Immune cells are key mediators of β cell destruction. This study attempted to investigate the role of immune cells and immune-related genes in the occurrence and development of T1DM.

METHODS

The raw gene expression profile of the samples from 12 T1DM patients and 10 normal controls was obtained from Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified by Limma package in R. The least absolute shrinkage and selection operator (LASSO)-support vector machines (SVM) were used to screen the hub genes. CIBERSORT algorithm was used to identify the different immune cells in distribution between T1DM and normal samples. Correlation of the hub genes and immune cells was analyzed by Spearman, and gene-GO-BP and gene-pathway interaction networks were constructed by Cytoscape plug-in ClueGO. Receiver operating characteristic (ROC) curves were used to assess diagnostic value of genes in T1DM.

RESULTS

The 50 immune-related DEGs were obtained between the T1DM and normal samples. Then, the 50 immune-related DEGs were further screened to obtain the 5 hub genes. CIBERSORT analysis revealed that the distribution of plasma cells, resting mast cells, resting NK cells and neutrophils had significant difference between T1DM and normal samples. Natural cytotoxicity triggering receptor 3 (NCR3) was significantly related to the activated NK cells, M0 macrophages, monocytes, resting NK cells, and resting memory CD4⁺ T cells. Moreover, tumor necrosis factor (TNF) was significantly associated with naive B cell and naive CD4⁺ T cell. NCR3 [Area under curve (AUC) = 0.918] possessed a higher accuracy than TNF (AUC = 0.763) in diagnosis of T1DM.

CONCLUSIONS

The immune-related genes (NCR3 and TNF) and immune cells (NK cells) may play a vital regulatory role in the occurrence and development of T1DM, which possibly provide new ideas and potential targets for the immunotherapy of diabetes mellitus (DM).

Transcriptional networks in at-risk individuals identify signatures of type 1 diabetes progression

Type 1 diabetes (T1D) is a disease of insulin deficiency that results from autoimmune destruction of pancreatic islet β cells. The exact cause of T1D remains unknown, although asymptomatic islet autoimmunity lasting from weeks to years before diagnosis raises the possibility of intervention before the onset of clinical disease. The number, type, and titer of islet autoantibodies are associated with long-term disease risk but do not cause disease, and robust early predictors of individual progression to T1D onset remain elusive. The Environmental Determinants of Diabetes in the Young (TEDDY) consortium is a prospective cohort study aiming to determine genetic and environmental interactions causing T1D. Here, we analyzed longitudinal blood transcriptomes of 2013 samples from 400 individuals in the TEDDY study before both T1D and islet autoimmunity. We identified and interpreted age-associated gene expression changes in healthy infancy and age-independent changes tracking with progression to both T1D and islet autoimmunity, beginning before other evidence of islet autoimmunity was present. We combined multivariate longitudinal data in a Bayesian joint model to predict individual risk of T1D onset and validated the association of a natural killer cell signature with progression and the model's predictive performance on an additional 356 samples from 56 individuals in the independent Type 1 Diabetes Prediction and Prevention study. Together, our results indicate that T1D is characterized by early and longitudinal changes in gene expression, informing the immunopathology of disease progression and facilitating prediction of its course.

A personalised approach for identifying disease-relevant pathways in heterogeneous diseases

Numerous time-course gene expression datasets have been generated for studying the biological dynamics that drive disease progression; and nearly as many methods have been proposed to analyse them. However, barely any method exists that can appropriately model time-course data while accounting for heterogeneity that entails many complex diseases. Most methods manage to fulfil either one of those qualities, but not both. The lack of appropriate methods hinders our capability of understanding the disease process and pursuing preventive treatments. We present a method that models time-course data in a personalised manner using Gaussian processes in order to identify differentially expressed genes (DEGs); and combines the DEG lists on a pathway-level using a permutation-based empirical hypothesis testing in order to overcome gene-level variability and inconsistencies prevalent to datasets from heterogenous diseases. Our method can be applied to study the time-course dynamics, as well as specific time-windows of heterogeneous diseases. We apply our personalised approach on three longitudinal type 1 diabetes (T1D) datasets, where the first two are used to determine perturbations taking place during early prognosis of the disease, as well as in time-windows before autoantibody positivity and T1D diagnosis; and the third is used to assess the generalisability of our method. By comparing to non-personalised methods, we demonstrate that our approach is biologically motivated and can reveal more insights into progression of heterogeneous diseases. With its robust capabilities of identifying disease-relevant pathways, our approach could be useful for predicting events in the progression of heterogeneous diseases and even for biomarker identification.

Cytokines in type 1 diabetes: mechanisms of action and immunotherapeutic targets

Cytokines play crucial roles in orchestrating complex multicellular interactions between pancreatic β cells and immune cells in the development of type 1 diabetes (T1D) and are thus potential immunotherapeutic targets for this disorder. Cytokines that can induce regulatory functions-for example, IL-10, TGF-β and IL-33-are thought to restore immune tolerance and prevent β-cell damage. By contrast, cytokines such as IL-6, IL-17, IL-21 and TNF, which promote the differentiation and function of diabetogenic immune cells, are thought to lead to T1D onset and progression. However, targeting these dysregulated cytokine networks does not always result in consistent effects because anti-inflammatory or proinflammatory functions of cytokines, responsible for β-cell destruction, are context dependent. In this review, we summarise the current knowledge on the involvement of well-known cytokines in both the initiation and destruction phases of T1D and discuss advances in recently discovered roles of cytokines. Additionally, we emphasise the complexity and implications of cytokine modulation therapy and discuss the ways in which this strategy has been translated into clinical trials.

Fisiopatología de la hepatitis C y diabetes mellitus. Hacia la cura de dos epidemias en el siglo XXI

La infección crónica por virus de la hepatitis C (VHC) y la diabetes mellitus (DM) son dos problemas de salud pública que impactan los sistemas de salud, con una alta carga económica global. La infección por VHC produce manifestaciones hepáticas tales como hepatitis, cirrosis y carcinoma hepatocelular; asimismo, se ha involucrado en la patogénesis de manifestaciones extrahepáticas, entre las cuales se ha asociado con alteraciones metabólicas como la DM. Estudios longitudinales y transversales han reportado mayor incidencia y prevalencia de DM en pacientes con infección crónica por VHC. La DM acelera la progresión histológica y clínica en pacientes con infección crónica por VHC y las complicaciones cardiovasculares. Recientemente se ha avanzado en el tratamiento y la introducción de nuevos medicamentos como los antivirales de acción directa, que mejoran el control glucémico en estos pacientes.

The Association between Depression and Type 1 Diabetes Mellitus: Inflammatory Cytokines as Ferrymen in between?

The depression incidence is much higher in patients with diabetes mellitus (DM), and the majority of these cases remain under-diagnosed. Type 1 diabetes mellitus (T1D) is now widely thought to be an organ-specific autoimmune disease. As a chronic autoimmune condition, T1D is characterized by T cell-mediated selective loss of insulin-producing β-cells. The age of onset of T1D is earlier than T2D, and T1D patients have an increased vulnerability to depression due to its diagnosis and treatment burden occurring in a period when the individuals are young. The literature has suggested that inflammatory cytokines play a wide role in both diseases. In this review, the mechanisms behind the initiation and propagation of the autoimmune response in T1D and depression are analyzed, and the contribution of cytokines to both conditions is discussed. This review outlines the immunological mechanism of T1D and depression, with a particular emphasis on the role of tumor necrosis factor-α (TNF-α), IL-1β, and interferon-γ (IFN-γ) cytokines and their signaling pathways. The purpose of this review is to highlight the possible pathways of the cytokines shared by these two diseases via deciphering their cytokine cascades. They may provide a basic groundwork for future study of the possible mechanism that links these two diseases and to develop new compounds that target the same pathway but can conquer two diseases.

NLRX1 does not play a role in diabetes nor the development of diabetic nephropathy induced by multiple low doses of streptozotocin

Diabetic nephropathy (DN) is a microvascular complication of diabetes mellitus that results in both tubular and glomerular injury. Low-grade inflammation and oxidative stress are two mechanisms known to drive the progression of DN. Nucleotide-binding leucine-rich repeat containing family member X1 (NLRX1) is an innate immune receptor, uniquely located in mitochondria, that has been found to regulate inflammatory responses and to dampen renal oxidative stress by regulating oxidative phosphorylation. For this reason, we investigated the role of NLRX1 in the development of DN in a Type 1 Diabetes mouse model. We analyzed the effect of NLRX1 deficiency on diabetes development and the accompanied renal damage, inflammation, and fibrosis. We found that multiple low doses of streptozotocin induced body weight loss, polydipsia, hyperglycemia, glycosuria, and a mild DN phenotype in wildtype and NLRX1-deficient mice, without significant differences between these mouse strains. Despite increased NLRX1 expression in diabetic wildtype mice, NLRX1 deficiency did not affect the diabetic phenotype induced by streptozotocin treatment, as reflected by similar levels of polyuria, microalbuminuria, and increased renal markers of oxidative stress and inflammation in wildtype and NLRX1-deficient mice. The present findings show that NLRX1 does not mediate the development of streptozotocin-induced diabetes and diabetic-induced nephropathy in mice after multiple low doses of streptozotocin. This data implies that, while NLRX1 can be triggered by cellular stress, its regulatory and functional effects may be dependent on the specific physiological conditions. In the case of DN, NLRX1 may be neither helpful nor harmful, but rather a marker of metabolic stress.

LPS enhances CTB-INSULIN induction of IDO1 and IL-10 synthesis in human dendritic cells

Autoantigen-specific immunotherapy promises effective treatment for devastating tissue specific autoimmune diseases like multiple sclerosis (MS) and type 1 diabetes (T1D). Because activated dendritic cells (DCs) stimulate the differentiation of autoreactive T cells involved in the initiation of autoimmunity, blocking the activation of DCs may be an effective strategy for inhibiting tissue specific autoimmunity. Following this approach, immature DCs were shown to remain inactive after treatment with chimeric fusion proteins composed of the cholera toxin B subunit adjuvant linked to autoantigens like proinsulin (CTB-INS). Mass spectrometer analysis of human DCs treated with CTB-INS suggest that upregulation of the tryptophan catabolic enzyme indoleamine 2, 3-dioxygenase (IDO1) is responsible for inhibiting DC activation thereby resulting in a state of immunological tolerance within the DC. Here we show that the fusion protein CTB-INS inhibits human monocyte derived DC (moDC) activation through stimulation of IDO1 biosynthesis and that the resultant state of DC tolerance can be further enhanced by the presence of residual E. coli lipopolysaccharide (LPS) present in partially purified CTB-INS preparations. Additional experiments showed that LPS enhancement of DC tolerance was dependent upon stimulation of IDO1 biosynthesis. LPS stimulation of increased levels of IDO1 in the DC resulted in increased secretion of kynurenines, tryptophan degradation products known to suppress DC mediated pro-inflammatory T cell differentiation and to stimulate the proliferation of regulatory T cells (Tregs). Further, the presence of LPS in CTB-INS treated DCs stimulated the biosynthesis of costimulatory factors CD80 and CD86 but failed to upregulate maturation factor CD83, suggesting CTB-INS treated DCs may be maintained in a state of semi-activation. While treatment of moDCs with increasing amounts of LPS free CTB-INS was shown to increase DC secretion of the anti-inflammatory cytokine IL-10, the presence of residual LPS in partially purified CTB-INS preparations dramatically increased IL-10 secretion, suggesting that CTB-INS may enhance DC mediated immunological tolerance by stimulating the proliferation of anti-inflammatory T cells. While the extraction of LPS from bacterial generated CTB-INS may remove additional unknown factors that may contribute to the regulation of IDO1 levels, together, our experimental data suggest that LPS stimulates the ability of CTB-INS to induce IDO1 and IL-10 important factors required for establishment of a state of functional immunological tolerance in human DCs. Regulation of the ratio of LPS to CTB-INS may prove to be an effective method for optimization of readily available "off the shelf" CTB-INS mediated immune-therapy for tissue specific autoimmune diseases including type 1 diabetes.

Targeting Type 1 Diabetes: Selective Approaches for New Therapies

The clinical onset of type 1 diabetes is characterized by the destruction of the insulin-producing β cells of the pancreas and is caused by autoantigen-induced inflammation (insulitis) of the islets of Langerhans. The current standard of care for type 1 diabetes mellitus patients allows for management of the disease with exogenous insulin, but patients eventually succumb to many chronic complications such as limb amputation, blindness, and kidney failure. New therapeutic approaches now on the horizon are looking beyond glycemic management and are evaluating new strategies from protecting and regenerating endogenous islets to treating the underlying autoimmunity through selective modulation of key immune cell populations. Currently, there are no effective treatments for the autoimmunity that causes the disease, and strategies that aim to delay or prevent the onset of the disease will play an important role in the future of diabetes research. In this review, we summarize many of the key efforts underway that utilize molecular approaches to selectively modulate this disease and look at new therapeutic paradigms that can transform clinical treatment.

The genetic architecture of type 1 diabetes mellitus

Type 1 diabetes mellitus (T1D) is a complex autoimmune disorder characterised by loss of the insulin-producing pancreatic beta cells in genetically predisposed individuals, ultimately resulting in insulin deficiency and hyperglycaemia. T1D is most common among children and young adults, and the incidence is on the rise across the world. The aetiology of T1D is hypothesized to involve genetic and environmental factors that result in the T-cell mediated destruction of pancreatic beta cells. There is a strong genetic risk to T1D; with genome-wide association studies (GWAS) identifying over 60 susceptibility regions within the human genome which are marked by single nucleotide polymorphisms (SNPs). Here, we review what is currently known about the genetics of T1D. We argue that advancing our understanding of the aetiology and pathogenesis of T1D will require the integration of genome biology (omics-data) with GWAS data, thereby making it possible to elucidate the putative gene regulatory networks modulated by disease-associated SNPs. This approach has a potential to revolutionize clinical management of T1D in an era of precision medicine.

Potency of a Scalable Nanoparticulate Subunit Vaccine

Nanoparticulate vaccines can potentiate immune responses by site-specific drainage to lymph nodes (LNs). This approach may benefit from a nanoparticle engineering method with fine control over size and codelivery of antigen and adjuvant. Here, we applied the flash nanocomplexation (FNC) method to prepare nanovaccines via polyelectrolyte complexation of chitosan and heparin to coencapsulate the VP1 protein antigen from enterovirus 71, which causes hand-foot-mouth disease (HFMD), with tumor necrosis factor α (TNF) or CpG as adjuvants. FNC allows for reduction of the nanovaccine size to range from 90 to 130 nm with relatively narrower size distribution and a high payload capacity. These nanovaccines reached both proximal and distal LNs via subcutaneous injection and subsequently exhibited prolonged retention in the LNs. The codelivery induced strong immune activation toward a Th1 response in addition to a potent Th2 response, and conferred effective protection against lethal virus challenge comparable to that of an approved inactivated viral vaccine in mouse models of both passive and active immunization setting. In addition, these nanovaccines also elicited strong IgA titers, which may offer unique advantages for mucosal protection. This study addresses the issues of size control, antigen bioactivity retention, and biomanufacturing to demonstrate the translational potential of a subunit nanovaccine design.

Neutralization Versus Reinforcement of Proinflammatory Cytokines to Arrest Autoimmunity in Type 1 Diabetes

As physiological pathways of intercellular communication produced by all cells, cytokines are involved in the pathogenesis of inflammatory insulitis as well as pivotal mediators of immune homeostasis. Proinflammatory cytokines including interleukins, interferons, transforming growth factor-β, tumor necrosis factor-α, and nitric oxide promote destructive insulitis in type 1 diabetes through amplification of the autoimmune reaction, direct toxicity to β-cells, and sensitization of islets to apoptosis. The concept that neutralization of cytokines may be of therapeutic benefit has been tested in few clinical studies, which fell short of inducing sustained remission or achieving disease arrest. Therapeutic failure is explained by the redundant activities of individual cytokines and their combinations, which are rather dispensable in the process of destructive insulitis because other cytolytic pathways efficiently compensate their deficiency. Proinflammatory cytokines are less redundant in regulation of the inflammatory reaction, displaying protective effects through restriction of effector cell activity, reinforcement of suppressor cell function, and participation in islet recovery from injury. Our analysis suggests that the role of cytokines in immune homeostasis overrides their contribution to β-cell death and may be used as potent immunomodulatory agents for therapeutic purposes rather than neutralized.

Emetine Di-HCl Attenuates Type 1 Diabetes Mellitus in Mice

Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease characterized by beta cell destruction, insulin deficiency and hyperglycemia. Activated macrophages and autoimmune T cells play a crucial role in the pathogenesis of hyperglycemia in NOD murine diabetes models, but the molecular mechanisms of macrophage activation are unknown. We recently identified pigment epithelium-derived factor (PEDF) as an adipocyte-derived factor that activates macrophages and mediates insulin resistance. Reasoning that PEDF might participate as a proinflammatory mediator in murine diabetes, we measured PEDF levels in NOD mice. PEDF levels are significantly elevated in pancreas, in correlation with pancreatic TNF levels in NOD mice. To identify experimental therapeutics, we screened 2,327 compounds in two chemical libraries (the NIH Clinical Collection and Pharmakon-1600a) for leads that inhibit PEDF mediated TNF release in macrophage cultures. The lead molecule selected, "emetine" is a widely used emetic. It inhibited PEDF-mediated macrophage activation with an EC50 or 146 nM. Administration of emetine to NOD mice and to C57Bl6 mice subjected to streptozotocin significantly attenuated hyperglycemia, reduced TNF levels in pancreas, and attenuated insulitis. Together, these results suggest that targeting PEDF with emetine may attenuate TNF release and hyperglycemia in murine diabetes models. This suggests that further investigation of PEDF and emetine in the pathogenesis of human diabetes is warranted.

Tracking Immunological Responses of Islet Antigen-Specific T Cells in the Nonobese Diabetic (NOD) Mouse Model of Type 1 Diabetes

Tracking autoreactive cells in vivo is important in the study of autoimmune diseases, such as type 1 diabetes. This method provides a model to study the responses of T cells responding to physiologically relevant and organ-specific antigen. Intracellular fluorescent tracers are useful tools to identify adoptively transferred T cells. Firstly, they provide a unique fluorescent signal to distinguish adoptively transferred from endogenous cells. Secondly, cytoplasmic dyes can be used to evaluate proliferation, as the fluorescent intensity is halved with each round of cell division. This provides an important readout to assess cell activation and function.

Elevated IFN-alpha/beta levels in a streptozotocin-induced type I diabetic mouse model promote oxidative stress and mediate depletion of spleen-homing CD8+ T cells by apoptosis through impaired CCL21/CCR7 axis and IL-7/CD127 signaling

Type 1 diabetes mellitus (T1D) is associated with increased type 1 interferon (IFN) levels and subsequent severe defects in lymphocyte function, which increase susceptibility to infections. The blockade of type 1 IFN receptor 1 (IFNAR1) in non-obese diabetic mice has been shown to delay T1D onset and decrease T1D incidence by enhancing spleen CD4+ T cells and restoring B cell function. However, the effect of type 1 IFN blockade during T1D on splenic CD8+ T cells has not previously been studied. Therefore, we investigated, for the first time, the effect of IFNAR1 blockade on the survival and architecture of spleen-homing CD8+ T cells in a streptozotocin-induced T1D mouse model. Three groups of mice were examined: a non-diabetic control group; a diabetic group; and a diabetic group treated with an anti-IFNAR1 blocking antibody. We observed that T1D induction was accompanied by a marked destruction of β cells followed by a marked reduction in insulin levels and increased IFN-α and IFN-β levels in the diabetic group. The diabetic mice also exhibited many abnormal changes including an elevation in blood and spleen free radical (reactive oxygen species and nitric oxide) and pro-inflammatory cytokine (IL-6 and TNF-α) levels, a significant decrease in IL-7 levels, and subsequently, a significant decrease in the numbers of spleen-homing CD8+ T cells. This decrease in spleen-homing CD8+ T cells resulted from a marked reduction in the CCL21-mediated entry of CD8+ T cells into the spleen and from increased apoptosis due to a marked reduction in IL-7-mediated STAT5 and AKT phosphorylation. Interestingly, type 1 IFN signaling blockade in diabetic mice significantly restored the numbers of splenic CD8+ T cells by restoring free radical, pro-inflammatory cytokine and IL-7 levels. These effects subsequently rescued splenic CD8+ T cells from apoptosis through a mechanism that was dependent upon CCL21- and IL-7-mediated signaling. Our data suggest that type 1 IFN is an essential mediator of pathogenesis in T1D and that this role results from the negative effect of IFN signaling on the survival of splenic CD8+ T cells.

The Role of Dendritic Cell Subsets and Innate Immunity in the Pathogenesis of Type 1 Diabetes and Other Autoimmune Diseases

Dendritic cells (DCs) are key antigen-presenting cells that have an important role in autoimmune pathogenesis. DCs control both steady-state T cell tolerance and activation of pathogenic responses. The balance between these two outcomes depends on several factors, including genetic susceptibility, environmental signals that stimulate varied innate responses, and which DC subset is presenting antigen. Although the specific DC phenotype can diverge depending on the tissue location and context, there are four main subsets identified in both mouse and human: conventional cDC1 and cDC2, plasmacytoid DCs, and monocyte-derived DCs. In this review, we will discuss the role of these subsets in autoimmune pathogenesis and regulation, as well as the genetic and environmental signals that influence their function. Specific topics to be addressed include impact of susceptibility loci on DC subsets, alterations in DC subset development, the role of infection- and host-derived innate inflammatory signals, and the role of the intestinal microbiota on DC phenotype. The effects of these various signals on disease progression and the relative effects of DC subset composition and maturation level of DCs will be examined. These areas will be explored using examples from several autoimmune diseases but will focus mainly on type 1 diabetes.

Advances in the cellular immunological pathogenesis of type 1 diabetes

Type 1 diabetes is an autoimmune disease caused by the immune-mediated destruction of insulin-producing pancreatic β cells. In recent years, the incidence of type 1 diabetes continues to increase. It is supposed that genetic, environmental and immune factors participate in the damage of pancreatic β cells. Both the immune regulation and the immune response are involved in the pathogenesis of type 1 diabetes, in which cellular immunity plays a significant role. For the infiltration of CD4(+) and CD8(+) T lymphocyte, B lymphocytes, natural killer cells, dendritic cells and other immune cells take part in the damage of pancreatic β cells, which ultimately lead to type 1 diabetes. This review outlines the cellular immunological mechanism of type 1 diabetes, with a particular emphasis to T lymphocyte and natural killer cells, and provides the effective immune therapy in T1D, which is approached at three stages. However, future studies will be directed at searching for an effective, safe and long-lasting strategy to enhance the regulation of a diabetogenic immune system with limited toxicity and without global immunosuppression.

Islet antigen-specific Th17 cells can induce TNF-α-dependent autoimmune diabetes

Type 1 diabetes (T1D) results from autoimmune destruction of pancreatic β-cells. Although Th1 cells are key orchestrators of T1D, the function(s) of the more recently identified Th17 subset are unclear due to inherent plasticity. In this study, we analyzed Th17 cells for stability and diabetogenicity in NOD mice. We found that like Th1 cells, Th17 are a distinct population throughout the prediabetic phase. At diabetes onset, there were marked increases in IL-17-producing Th17 cells and IFN-γ-producing Th1 cells in the pancreas as well as in the serum levels of these cytokines, indicating that these proinflammatory mediators serve as biomarkers of advanced autoimmunity. Although naturally occurring Th17 cells in diabetic mice did not contribute to diabetes development in transfer models, islet-specific Th17 cells were diabetogenic independently of IL-17 and displayed inflammation-induced Th17-to-Th1 reprogramming that could be elicited by Th1 cells. However, an inability to generate Th1 cells because of Stat4, Ifngr, and Ifng deficiencies did not prevent diabetes. Instead, TNF-α could mediate diabetes in response to either Th17 cells or Th1 cells. The results identify a previously unknown mechanism by which Th17 cells can contribute to T1D. Our studies also suggest that when developing interventions for T1D, it will be potentially advantageous to focus on mechanisms common to effector T cells rather than on the signature cytokines of various subsets.

Dendritic cell subsets in type 1 diabetes: friend or foe?

Type 1 diabetes (T1D) is a T cell mediated autoimmune disease characterized by immune mediated destruction of the insulin-producing β cells in the islets of Langerhans. Dendritic cells (DC) have been implicated in the pathogenesis of T1D and are also used as immunotherapeutic agents. Plasmacytoid (p)DC have been shown to have both protective and pathogenic effects and a newly described merocytic DC population has been shown to break tolerance in the mouse model of T1D, the non-obese diabetic (NOD) mouse. We have used DC populations to prevent the onset of T1D in NOD mice and clinical trials of DC therapy in T1D diabetes have been initiated. In this review we will critically examine the recent published literature on the role of DC subsets in the induction and regulation of the autoimmune response in T1D.

CD8+ dendritic cell-mediated tolerance of autoreactive CD4+ T cells is deficient in NOD mice and can be corrected by blocking CD40L

DCs are important mediators of peripheral tolerance for the prevention of autoimmunity. Chimeric αDEC-205 antibodies with attached antigens allow in vivo antigen-specific stimulation of T cells by CD8(+) DCs, resulting in tolerance in nonautoimmune mice. However, it is not clear whether DC-mediated tolerance induction occurs in the context of ongoing autoimmunity. We assessed the role of CD8(+) DCs in stimulation of autoreactive CD4(+) T cells in the NOD mouse model of type 1 diabetes. Targeting of antigen to CD8(+) DCs via αDEC-205 led to proliferation and expansion of β-cell specific BDC2.5 T cells. These T cells also produced IL-2 and IFN-γ and did not up-regulate FoxP3, consistent with an activated rather than tolerant phenotype. Similarly, endogenous BDC peptide-reactive T cells, identified with I-A(g7) tetramers, did not become tolerant after antigen delivery via αDEC-205: no deletion or Treg induction was observed. We observed that CD8(+) DCs from NOD mice expressed higher surface levels of CD40 than CD8(+) DCs from C57BL/6 mice. Blockade of CD40-CD40L interactions reduced the number of BDC2.5 T cells remaining in mice, 10 days after antigen targeting to CD8 DCs, and blocked IFN-γ production by BDC2.5 T cells. These data indicate that the ability of autoreactive CD4(+) T cells to undergo tolerance mediated by CD8(+) DCs is defective in NOD mice and that blocking CD40-CD40L interactions can restore tolerance induction.

The role of dendritic cells in autoimmunity

Dendritic cells (DCs) initiate and shape both the innate and adaptive immune responses. Accordingly, recent evidence from clinical studies and experimental models implicates DCs in the pathogenesis of most autoimmune diseases. However, fundamental questions remain unanswered concerning the actual roles of DCs in autoimmunity, both in general and, in particular, in specific diseases. In this Review, we discuss the proposed roles of DCs in immunological tolerance, the effect of the gain or loss of DCs on autoimmunity and DC-intrinsic molecular regulators that help to prevent the development of autoimmunity. We also review the emerging roles of DCs in several autoimmune diseases, including autoimmune myocarditis, multiple sclerosis, psoriasis, type 1 diabetes and systemic lupus erythematosus.

Anti-IL-7 receptor-α reverses established type 1 diabetes in nonobese diabetic mice by modulating effector T-cell function

Genetic variation in the IL-7 receptor-α (IL-7R) gene is associated with susceptibility to human type 1 diabetes (T1D). Here we investigate the therapeutic efficacy and mechanism of IL-7Rα antibody in a mouse model of T1D. IL-7Rα antibody induces durable, complete remission in newly onset diabetic mice after only two to three injections. IL-7 increases, whereas IL-7Rα antibody therapy reduces, the IFN-γ-producing CD4(+) (T(H)1) and IFN-γ-producing CD8(+) T cells. Conversely, IL-7 decreases and IL-7Rα antibody enhances the inhibitory receptor Programmed Death 1 (PD-1) expression in the effector T cells. Programmed Death 1 blockade reversed the immune tolerance mediated by the IL-7Rα antibody therapy. Furthermore, IL-7Rα antibody therapy increases the frequency of regulatory T cells without affecting their suppressor activity. The durable efficacy and the multipronged tolerogenic mechanisms of IL-7Rα antibody therapy suggest a unique disease-modifying approach to T1D.

Pancreatic islet expression of chemokine CCL2 suppresses autoimmune diabetes via tolerogenic CD11c+ CD11b+ dendritic cells

Development of type 1 diabetes in the nonobese diabetic (NOD) mouse is preceded by an immune cell infiltrate in the pancreatic islets. The exact role of the attracted cells is still poorly understood. Chemokine CCL2/MCP-1 is known to attract CCR2(+) monocytes and dendritic cells (DCs). We have previously shown that transgenic expression of CCL2 in pancreatic islets via the rat insulin promoter induces nondestructive insulitis on a nonautoimmune background. We report here an unexpected reduction of diabetes development on the NOD background despite an increased islet cell infiltrate with markedly increased numbers of CD11c(+) CD11b(+) DCs. These DCs exhibited a hypoactive phenotype with low CD40, MHC II, CD80/CD86 expression, and reduced TNF-α but elevated IL-10 secretions. They failed to induce proliferation of diabetogenic CD4(+) T cells in vitro. Pancreatic lymph node CD4(+) T cells were down-regulated ex vivo and expressed the anergy marker Grail. By using an in vivo transfer system, we show that CD11c(+) CD11b(+) DCs from rat insulin promoter-CCL2 transgenic NOD mice were the most potent cells suppressing diabetes development. These findings support an unexpected beneficial role for CCL2 in type 1 diabetes with implications for current strategies interfering with the CCL2/CCR2 axis in humans, and for dendritic cell biology in autoimmunity.