Interleukin-21 Is Required for the Development of Type 1 Diabetes in NOD Mice

OBJECTIVE: Interleukin (IL)-21 is a type 1 cytokine that has been implicated in the pathogenesis of type 1 diabetes via the unique biology of the nonobese diabetic (NOD) mouse strain. The aim of this study was to investigate a causal role for IL-21 in type 1 diabetes. RESEARCH DESIGN AND METHODS: We generated IL-21R–deficient NOD mice and C57Bl/6 mice expressing IL-21 in pancreatic β-cells, allowing the determination of the role of insufficient and excessive IL-21 signaling in type 1 diabetes. RESULTS: Deficiency in IL-21R expression renders NOD mice resistant to insulitis, production of insulin autoantibodies, and onset of type 1 diabetes. The lymphoid compartment in IL-21R−/− NOD is normal and does not contain an increased regulatory T-cell fraction or diminished effector cytokine responses. However, we observed a clear defect in autoreactive effector T-cells in IL-21R−/− NOD by transfer experiments. Conversely, overexpression of IL-21 in pancreatic β-cells induced inflammatory cytokine and chemokines, including IL-17A, IL17F, IFN-γ, monocyte chemoattractant protein (MCP)-1, MCP-2, and interferon-inducible protein-10 in the pancreas. The ensuing leukocytic infiltration in the islets resulted in destruction of β-cells and spontaneous type 1 diabetes in the normally diabetes-resistant C57Bl/6 and NOD × C57Bl/6 backgrounds. CONCLUSIONS: This work provides demonstration of the essential prodiabetogenic activities of IL-21 on diverse genetic backgrounds (NOD and C57BL/6) and indicates that IL-21 blockade could be a promising strategy for interventions in human type 1 diabetes

Transforming Growth Factor-β Suppresses the Activation of CD8+ T-Cells When Naïve but Promotes Their Survival and Function Once Antigen Experienced : A Two-Faced Impact on Autoimmunity

OBJECTIVE—Transforming growth factor-β (TGF-β) can exhibit strong immune suppression but has also been shown to promote T-cell growth. We investigated the differential effect of this cytokine on CD8+ T-cells in autoimmunity and antiviral immunity

The Role of Innate Immunity in Autoimmunity

During the 2004 International Congress of Immunology in Montreal, a panel of experts gathered for an “Ideashop” discussion on the potential role of innate immunity in autoimmunity and the ways in which this might be targeted in future therapies

Breaking tolerance to the natural human liver autoantigen cytochrome P450 2D6 by virus infection

Autoimmune liver diseases, such as autoimmune hepatitis (AIH) and primary biliary cirrhosis, often have severe consequences for the patient. Because of a lack of appropriate animal models, not much is known about their potential viral etiology. Infection by liver-tropic viruses is one possibility for the breakdown of self-tolerance. Therefore, we infected mice with adenovirus Ad5 expressing human cytochrome P450 2D6 (Ad-2D6). Ad-2D6–infected mice developed persistent autoimmune liver disease, apparent by cellular infiltration, hepatic fibrosis, “fused” liver lobules, and necrosis. Similar to type 2 AIH patients, Ad-2D6–infected mice generated type 1 liver kidney microsomal–like antibodies recognizing the immunodominant epitope WDPAQPPRD of cytochrome P450 2D6 (CYP2D6). Interestingly, Ad-2D6–infected wild-type FVB/N mice displayed exacerbated liver damage when compared with transgenic mice expressing the identical human CYP2D6 protein in the liver, indicating the presence of a stronger immunological tolerance in CYP2D6 mice. We demonstrate for the first time that infection with a virus expressing a natural human autoantigen breaks tolerance, resulting in a chronic form of severe, autoimmune liver damage. Our novel model system should be instrumental for studying mechanisms involved in the initiation, propagation, and precipitation of virus-induced autoimmune liver diseases

Reduced Expression of IFIH1 Is Protective for Type 1 Diabetes

IFIH1 (interferon induced with helicase C domain 1), also known as MDA5 (melanoma differentiation-associated protein 5), is one of a family of intracellular proteins known to recognise viral RNA and mediate the innate immune response. IFIH1 is causal in type 1 diabetes based on the protective associations of four rare variants, where the derived alleles are predicted to reduce gene expression or function. Originally, however, T1D protection was mapped to the common IFIH1 nsSNP, rs1990760 or Thr946Ala. This common amino acid substitution does not cause a loss of function and evidence suggests the protective allele, Ala946, may mark a haplotype with reduced expression of IFIH1 in line with the protection conferred by the four rare loss of function alleles. We have performed allele specific expression analysis that supports this hypothesis: the T1D protective haplotype correlates with reduced IFIH1 transcription in interferon-β stimulated peripheral blood mononuclear cells (overall p = 0.012). In addition, we have used multiflow cytometry analysis and quantitative PCR assays to prove reduced expression of IFIH1 in individuals heterozygous for three of the T1D-associated rare alleles: a premature stop codon, rs35744605 (Glu627X) and predicted splice variants, rs35337543 (IVS8+1) and rs35732034 (IVS14+1). We also show that the nsSNP, Ile923V, does not alter pre-mRNA levels of IFIH1. These results confirm and extend the new autoimmune disease pathway of reduced IFIH1 expression and protein function protecting from T1D

Anti-interleukin-21 antibody and liraglutide for the preservation of β-cell function in adults with recent-onset type 1 diabetes : a randomised, double-blind, placebo-controlled, phase 2 trial

Publisher Copyright: © 2021 Elsevier LtdBackground: Type 1 diabetes is characterised by progressive loss of functional β-cell mass, necessitating insulin treatment. We aimed to investigate the hypothesis that combining anti-interleukin (IL)-21 antibody (for low-grade and transient immunomodulation) with liraglutide (to improve β-cell function) could enable β-cell survival with a reduced risk of complications compared with traditional immunomodulation. Methods: This randomised, parallel-group, placebo-controlled, double-dummy, double-blind, phase 2 trial was done at 94 sites (university hospitals and medical centres) in 17 countries. Eligible participants were adults aged 18–45 years with recently diagnosed type 1 diabetes and residual β-cell function. Individuals with unstable type 1 diabetes (defined by an episode of severe diabetic ketoacidosis within 2 weeks of enrolment) or active or latent chronic infections were excluded. Participants were randomly assigned (1:1:1:1), with stratification by baseline stimulated peak C-peptide concentration (mixed-meal tolerance test [MMTT]), to the combination of anti-IL-21 and liraglutide, anti-IL-21 alone, liraglutide alone, or placebo, all as an adjunct to insulin. Investigators, participants, and funder personnel were masked throughout the treatment period. The primary outcome was the change in MMTT-stimulated C-peptide concentration at week 54 (end of treatment) relative to baseline, measured via the area under the concentration-time curve (AUC) over a 4 h period for the full analysis set (intention-to-treat population consisting of all participants who were randomly assigned). After treatment cessation, participants were followed up for an additional 26-week off-treatment observation period. This trial is registered with ClinicalTrials.gov, NCT02443155. Findings: Between Nov 10, 2015, and Feb 27, 2019, 553 adults were assessed for eligibility, of whom 308 were randomly assigned to receive either anti-IL-21 plus liraglutide, anti-IL-21, liraglutide, or placebo (77 assigned to each group). Compared with placebo (ratio to baseline 0·61, 39% decrease), the decrease in MMTT-stimulated C-peptide concentration from baseline to week 54 was significantly smaller with combination treatment (0·90, 10% decrease; estimated treatment ratio 1·48, 95% CI 1·16–1·89; p=0·0017), but not with anti-IL-21 alone (1·23, 0·97–1·57; p=0·093) or liraglutide alone (1·12, 0·87–1·42; p=0·38). Despite greater insulin use in the placebo group, the decrease in HbA1c (a key secondary outcome) at week 54 was greater with all active treatments (−0·50 percentage points) than with placebo (−0·10 percentage points), although the differences versus placebo were not significant. The effects diminished upon treatment cessation. Changes in immune cell subsets across groups were transient and mild (<10% change over time). The most frequently reported adverse events included gastrointestinal disorders, in keeping with the known side-effect profile of liraglutide. The rate of hypoglycaemic events did not differ significantly between active treatment groups and placebo, with an exception of a lower rate in the liraglutide group than in the placebo group during the treatment period. No events of diabetic ketoacidosis were observed. One participant died while on liraglutide (considered unlikely to be related to trial treatment) in connection with three reported adverse events (hypoglycaemic coma, pneumonia, and brain oedema). Interpretation: The combination of anti-IL-21 and liraglutide could preserve β-cell function in recently diagnosed type 1 diabetes. The efficacy of this combination appears to be similar to that seen in trials of other disease-modifying interventions in type 1 diabetes, but with a seemingly better safety profile. Efficacy and safety should be further evaluated in a phase 3 trial programme. Funding: Novo Nordisk.Peer reviewe

Measles IgG Antibody Index Correlates with T2 Lesion Load on MRI in Patients with Early Multiple Sclerosis

Background: B cells and humoral immune responses play an important role in the pathogenesis and diagnosis of multiple sclerosis (MS). A characteristic finding in patients with MS is a polyspecific intrathecal B cell response against neurotropic viruses, specifically against measles virus, rubella virus, and varicella zoster virus, also known as an MRZ reaction (MRZR). Here, we correlated from the routine clinical diagnostics individual IgG antibody indices (AIs) of MRZR with magnetic resonance imaging (MRI) findings in patients with first MS diagnosis. Methods/Results: MRZR was determined in 68 patients with a clinically isolated syndrome (CIS) or early relapsing-remitting MS (RRMS). Absolute AI values for measles virus, rubella virus, and varicella zoster virus were correlated with T2 lesion load and gadolinium enhancing lesions on cerebral MRI (cMRI) and cMRI combined with spinal MRI (sMRI). Measles virus AI correlated significantly with T2 lesion load on cMRI (p = 0.0312, Mann-Whitney U test) and the sum of lesions on cMRI and sMRI (p = 0.0413). Varicella zoster virus AI also showed a correlation with T2 lesion load on cMRI but did not reach statistical significance (p = 0.2893). Conclusion: The results confirm MRZR as part of the polyspecific immune reaction in MS with possible prognostic impact on MRI and clinical parameters. Furthermore, the data indicate that intrathecal measles virus IgG production correlates wit

Activation of Insulin-Reactive CD8 T-Cells for Development of Autoimmune Diabetes

Objective: We have previously reported a highly diabetogenic CD8 T cell clone, G9C8, in the Non Obese Diabetic (NOD) mouse, specific to low avidity insulin peptide B15-23 and cells responsive to this antigen are among the earliest islet infiltrates. We aimed to study the selection, activation and development of diabetogenic capacity of these insulin-reactive T cells. Research Design and Methods: We generated a TCR transgenic mouse expressing the cloned TCR Vα18/Vβ6 receptor of the G9C8 insulin-reactive CD8 T cell clone. The mice were crossed to TCRCα−/− mice so that the majority of the T cells expressed the clonotypic TCR and the phenotype and function of the cells was investigated. Results: There was good selection of CD8 T cells with a predominance of CD8 single positive thymocytes, in spite of thymic insulin expression. Peripheral lymph node T cells had a naïve phenotype (CD44lo, CD62Lhi) and proliferated to insulin B15-23 peptide and to insulin. These cells produced interferon-γ and TNF-α in response to insulin peptide and were cytotoxic to insulin-peptide coated targets. In vivo, the TCR transgenic mice developed insulitis but not spontaneous diabetes. However, the mice developed diabetes on immunization, and the activated transgenic T cells were able to transfer diabetes to immunodeficient NOD.scid mice. Conclusion: Autoimmune CD8 T cells responding to a low affinity insulin B chain peptide escape from thymic negative selection, and require activation in vivo to cause diabetes