Prevention of diabetes in nonobese diabetic mice by tumor necrosis factor (TNF): similarities between TNF-alpha and interleukin 1

Development, Pre-Clinical Safety, and Immune Profile of RENOVAC-A Dimer RBD-Based Anti-Coronavirus Subunit Vaccine

Background: The development of effective and safe vaccines and their timely delivery to the public play a crucial role in preventing and managing infectious diseases. Many vaccines have been produced and distributed globally to prevent COVID-19 infection. However, establishing effective vaccine development platforms and evaluating their safety and immunogenicity remains critical to increasing health security, especially in developing countries. Objectives: Therefore, we developed a local subunit vaccine candidate, RENOVAC, and reported its toxicity and immunogenicity profile in animal models. Methods: First, the synthetic gene-coding tandem RBD linked with the GS linker was cloned into the expression vector and expressed in CHO cells. The protein was then purified and filter sterilized, and 10 µg/dose and 25 µg/dose formulations were finally examined for the 14-day repeated dose toxicity followed by the immunogenic profile in preclinical studies. Results: When administered to Sprague Dawley rats by intramuscular route, the vaccine was well tolerated up to and including the dose of 25 µg/animal, and no toxicologically adverse changes were noted. The observed change in weight of the thymus and spleen might be related to the immunological response to the vaccine. The dimer RBD vaccine demonstrated the ability to generate high levels of specific immunoglobulins (IGs) and neutralization antibodies (NAbs). Finally, changes in the amounts of specific T cells and cytokines after vaccination suggested that the vaccine mainly triggers an immune response by activating CD4+ Th2-cells, which then activate B-cells to provide humoral immunity. Conclusions: The study suggests that, based on its reliable immunogenicity and acceptable safety, the vaccine can be further directed for clinical trials.

Significance of Bacillus Calmette-Guerin (BCG) vaccine intervention for patients with Type 1 Diabetes (T1D): A systematic review and meta-analysis

PURPOSE

Immunotherapy is an emerging therapeutic modality for many autoimmune, oncology, and infectious diseases to cure or prevent the underlying causes. Several immunotherapeutic agents are investigated for their beneficial potential in patients with diabetes. However, none have culminated into a successful therapy. The present comprehensive meta-analysis and systematic review covers the last two decades of historical research evaluating the Bacillus Calmette-Guerin (BCG) vaccine as an immunotherapeutic agent in diabetes, along with updated information on similar recent publications.

METHOD

A total of 278 articles were retrieved through literature databases, and after applying inclusion and exclusion criteria as per PRISMA guidelines, seven studies were selected for meta-analysis using Cochrane Q statistics.

RESULTS

Our meta-analysis revealed marginal benefits, lowering glycosylated/glycated haemoglobin (HbA1C) levels and glutamic-acid-decarboxylase (GAD) autoantibodies in BCG treated people with Type 1 Diabetes (T1D) compared to the matched control individuals. The BCG intervention found to be ineffective in regulating C-peptide (connecting peptide) and clinical remission (CR) i.e. improved glycemic regulation, though beneficial tendency was observed.

CONCLUSION

Our systematic review and meta-analysis revealed benefits of BCG vaccine intervention in T1D patients, including improved HbA1C and GAD autoantibody levels. However, the study has several limitations stemming from BCG vaccine-related factors and patient characteristics. Therefore, a large clinical trial with an enhanced study design is needed to validate the immunity-related benefits of the BCG vaccine for glucose metabolism in patients with T1D.

Tyrosol-loaded Nano-niosomes Attenuate Diabetic Injury by TargetingGlucose Metabolism, Inflammation, and Glucose Transfer

INTRODUCTION

The increasing prevalence of type 2 diabetes, has become a global concern, making it imperative to control. Chemical drugs commonly recommended for diabetes treatment cause many complications and drug resistance over time.

METHODS

The polyphenol tyrosol has many health benefits, including anti-diabetes properties. Tyrosol's efficacy can be significantly increased when it is used as a niosome in the treatment of diabetes. In this study, Tyrosol and nano-Tyrosol are examined for their effects on genes implicated in type 2 diabetes in streptozotocin-treated rats. Niosome nanoparticles containing 300 mg surfactant (span60: tween60) and 10 mg cholesterol were hydrated in thin films with equal molar ratios. After 72 hours, nano-niosomal formulas were assessed for their physicochemical properties. MTT assays were conducted on HFF cells to assess the cellular toxicity of the nano niosome contacting optimal Tyrosol. Finally, the expression of PEPCK, GCK, TNF-ɑ, IL6, GLUT2 and GLUT9 was measured by real-time PCR. Physiochemical properties of the SEM images of niosomes loaded with Tyrosol revealed the nanoparticles had a vehicular structure.

RESULTS

In this study, there were two stages of release: initial release (8 hours) and sustainable release (72 hours). Meanwhile, free-form drugs were considerably more toxic than niosomal drugs in terms of their cellular toxicity. An in vivo comparison of oral Tyrosol gavage with nano-Tyrosol showed a significant increase in GCK (P < 0.001), GLUT2 (P < 0.001), and GLUT9 (P < 0.001). Furthermore, nano-Tyrosol decreased the expression of TNF-ɑ (P < 0.05), PEPCK (P < 0.001), and IL-6 (P < 0.05) which had been increased by diabetes mellitus. The results confirmed nano-Tyrosol's anti-diabetes and anti-inflammatory effects.

CONCLUSION

These findings suggest that nano-Tyrosol has potential applications in diabetes treatment and associated inflammation. Further research is needed to better understand the mechanism of action.

A Monocytic Barrier to the Humanization of Immunodeficient Mice

Mice with severe immunodeficiencies have become very important tools for studying foreign cells in an in vivo environment. Xenotransplants can be used to model cells from many species, although most often, mice are humanized through the transplantation of human cells or tissues to meet the needs of medical research. The development of immunodeficient mice is reviewed leading up to the current state-of-the-art strains, such as the NOD-scid-gamma (NSG) mouse. NSG mice are excellent hosts for human hematopoietic stem cell transplants or immune reconstitution through transfusion of human peripheral blood mononuclear cells. However, barriers to full hematopoietic engraftment still remain; notably, the survival of human cells in the circulation is brief, which limits overall hematological and immune reconstitution. Reports have indicated a critical role for monocytic cells - monocytes, macrophages, and dendritic cells - in the clearance of xenogeneic cells from circulation. Various aspects of the NOD genetic background that affect monocytic cell growth, maturation, and function that are favorable to human cell transplantation are discussed. Important receptors, such as SIRPα, that form a part of the innate immune system and enable the recognition and phagocytosis of foreign cells by monocytic cells are reviewed. The development of humanized mouse models has taken decades of work in creating more immunodeficient mice, genetic modification of these mice to express human genes, and refinement of transplant techniques to optimize engraftment. Future advances may focus on the monocytic cells of the host to find ways for further engraftment and survival of xenogeneic cells.

TNFR2 Costimulation Differentially Impacts Regulatory and Conventional CD4+ T-Cell Metabolism

CD4+ conventional T cells (Tconvs) mediate adaptive immune responses, whereas regulatory T cells (Tregs) suppress those responses to safeguard the body from autoimmunity and inflammatory diseases. The opposing activities of Tconvs and Tregs depend on the stage of the immune response and their environment, with an orchestrating role for cytokine- and costimulatory receptors. Nutrient availability also impacts T-cell functionality via metabolic and biosynthetic processes that are largely unexplored. Many data argue that costimulation by Tumor Necrosis Factor Receptor 2 (TNFR2) favors support of Treg over Tconv responses and therefore TNFR2 is a key clinical target. Here, we review the pertinent literature on this topic and highlight the newly identified role of TNFR2 as a metabolic regulator for thymus-derived (t)Tregs. We present novel transcriptomic and metabolomic data that show the differential impact of TNFR2 on Tconv and tTreg gene expression and reveal distinct metabolic impact on both cell types.

CD4+ T-Cell Dysfunction in Severe COVID-19 Disease Is Tumor Necrosis Factor-α/Tumor Necrosis Factor Receptor 1-Dependent

Rationale: Lymphopenia is common in severe coronavirus disease (COVID-19), yet the immune mechanisms are poorly understood. As inflammatory cytokines are increased in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, we hypothesized a role in contributing to reduced T-cell numbers. Objectives: We sought to characterize the functional SARS-CoV-2 T-cell responses in patients with severe versus recovered, mild COVID-19 to determine whether differences were detectable. Methods: Using flow cytometry and single-cell RNA sequence analyses, we assessed SARS-CoV-2-specific responses in our cohort. Measurements and Main Results: In 148 patients with severe COVID-19, we found lymphopenia was associated with worse survival. CD4+ lymphopenia predominated, with lower CD4+/CD8+ ratios in severe COVID-19 compared with patients with mild disease (P < 0.0001). In severe disease, immunodominant CD4+ T-cell responses to Spike-1 (S1) produced increased in vitro TNF-α (tumor necrosis factor-α) but demonstrated impaired S1-specific proliferation and increased susceptibility to activation-induced cell death after antigen exposure. CD4+TNF-α+ T-cell responses inversely correlated with absolute CD4+ counts from patients with severe COVID-19 (n = 76; R = -0.797; P < 0.0001). In vitro TNF-α blockade, including infliximab or anti-TNF receptor 1 antibodies, strikingly rescued S1-specific CD4+ T-cell proliferation and abrogated S1-specific activation-induced cell death in peripheral blood mononuclear cells from patients with severe COVID-19 (P < 0.001). Single-cell RNA sequencing demonstrated marked downregulation of type-1 cytokines and NFκB signaling in S1-stimulated CD4+ cells with infliximab treatment. We also evaluated BAL and lung explant CD4+ T cells recovered from patients with severe COVID-19 and observed that lung T cells produced higher TNF-α compared with peripheral blood mononuclear cells. Conclusions: Together, our findings show CD4+ dysfunction in severe COVID-19 is TNF-α/TNF receptor 1-dependent through immune mechanisms that may contribute to lymphopenia. TNF-α blockade may be beneficial in severe COVID-19.

Gut mucosa alterations and loss of segmented filamentous bacteria in type 1 diabetes are associated with inflammation rather than hyperglycaemia

OBJECTIVE

Type 1 diabetes (T1D) is an autoimmune disease caused by the destruction of pancreatic β-cells producing insulin. Both T1D patients and animal models exhibit gut microbiota and mucosa alterations, although the exact cause for these remains poorly understood. We investigated the production of key cytokines controlling gut integrity, the abundance of segmented filamentous bacteria (SFB) involved in the production of these cytokines, and the respective role of autoimmune inflammation and hyperglycaemia.

DESIGN

We used several mouse models of autoimmune T1D as well as mice rendered hyperglycaemic without inflammation to study gut mucosa and microbiota dysbiosis. We analysed cytokine expression in immune cells, epithelial cell function, SFB abundance and microbiota composition by 16S sequencing. We assessed the role of anti-tumour necrosis factor α on gut mucosa inflammation and T1D onset.

RESULTS

We show in models of autoimmune T1D a conserved loss of interleukin (IL)-17A, IL-22 and IL-23A in gut mucosa. Intestinal epithelial cell function was altered and gut integrity was impaired. These defects were associated with dysbiosis including progressive loss of SFB. Transfer of diabetogenic T-cells recapitulated these gut alterations, whereas induction of hyperglycaemia with no inflammation failed to do so. Moreover, anti-inflammatory treatment restored gut mucosa and immune cell function and dampened diabetes incidence.

CONCLUSION

Our results demonstrate that gut mucosa alterations and dysbiosis in T1D are primarily linked to inflammation rather than hyperglycaemia. Anti-inflammatory treatment preserves gut homeostasis and protective commensal flora reducing T1D incidence.

Interplay of immune and kidney resident cells in the formation of tertiary lymphoid structures in lupus nephritis

Kidney involvement confers significant morbidity and mortality in patients with systemic lupus erythematosus (SLE). The pathogenesis of lupus nephritis (LN) involves diverse mechanisms instigated by elements of the autoimmune response which alter the biology of kidney resident cells. Processes in the glomeruli and in the interstitium may proceed independently albeit crosstalk between the two is inevitable. Podocytes, mesangial cells, tubular epithelial cells, kidney resident macrophages and stromal cells with input from cytokines and autoantibodies present in the circulation alter the expression of enzymes, produce cytokines and chemokines which lead to their injury and damage of the kidney. Several of these molecules can be targeted independently to prevent and reverse kidney failure. Tertiary lymphoid structures with true germinal centers are present in the kidneys of patients with lupus nephritis and have been increasingly recognized to associate with poorer renal outcomes. Stromal cells, tubular epithelial cells, high endothelial vessel and lymphatic venule cells produce chemokines which enable the formation of structures composed of a T-cell-rich zone with mature dendritic cells next to a B-cell follicle with the characteristics of a germinal center surrounded by plasma cells. Following an overview on the interaction of the immune cells with kidney resident cells, we discuss the cellular and molecular events which lead to the formation of tertiary lymphoid structures in the interstitium of the kidneys of mice and patients with lupus nephritis. In parallel, molecules and processes that can be targeted therapeutically are presented.

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).

TNF in the era of immune checkpoint inhibitors: friend or foe?

Immune checkpoint inhibitors (ICIs) are effective in the treatment of patients with advanced cancer and have emerged as a pillar of standard cancer care. However, their use is complicated by adverse effects known as immune-related adverse events (irAEs), including ICI-induced inflammatory arthritis. ICI-induced inflammatory arthritis is distinguished from other irAEs by its persistence and requirement for long-term treatment. TNF inhibitors are commonly used to treat inflammatory diseases such as rheumatoid arthritis, spondyloarthropathies and inflammatory bowel disease, and have also been adopted as second-line agents to treat irAEs refractory to glucocorticoid treatment. Experiencing an irAE is associated with a better antitumour response after ICI treatment. However, whether TNF inhibition can be safely used to treat irAEs without promoting cancer progression, either by compromising ICI therapy efficacy or via another route, remains an open question. In this Review, we discuss clinical and preclinical studies that address the relationship between TNF, TNF inhibition and cancer. The bulk of the evidence suggests that at least short courses of TNF inhibitors are safe for the treatment of irAEs in patients with cancer undergoing ICI therapy. Data from preclinical studies hint that TNF inhibition might augment the antitumour effect of ICI therapy while simultaneously ameliorating irAEs.

Golimumab and Beta-Cell Function in Youth with New-Onset Type 1 Diabetes

BACKGROUND

Type 1 diabetes is an autoimmune disease characterized by progressive loss of pancreatic beta cells. Golimumab is a human monoclonal antibody specific for tumor necrosis factor α that has already been approved for the treatment of several autoimmune conditions in adults and children. Whether golimumab could preserve beta-cell function in youth with newly diagnosed overt (stage 3) type 1 diabetes is unknown.

METHODS

In this phase 2, multicenter, placebo-controlled, double-blind, parallel-group trial, we randomly assigned, in a 2:1 ratio, children and young adults (age range, 6 to 21 years) with newly diagnosed overt type 1 diabetes to receive subcutaneous golimumab or placebo for 52 weeks. The primary end point was endogenous insulin production, as assessed according to the area under the concentration-time curve for C-peptide level in response to a 4-hour mixed-meal tolerance test (4-hour C-peptide AUC) at week 52. Secondary and additional end points included insulin use, the glycated hemoglobin level, the number of hypoglycemic events, the ratio of fasting proinsulin to C-peptide over time, and response profile.

RESULTS

A total of 84 participants underwent randomization - 56 were assigned to the golimumab group and 28 to the placebo group. The mean (±SD) 4-hour C-peptide AUC at week 52 differed significantly between the golimumab group and the placebo group (0.64±0.42 pmol per milliliter vs. 0.43±0.39 pmol per milliliter, P<0.001). A treat-to-target approach led to good glycemic control in both groups, and there was no significant difference between the groups in glycated hemoglobin level. Insulin use was lower with golimumab than with placebo. A partial-remission response (defined as an insulin dose-adjusted glycated hemoglobin level score [calculated as the glycated hemoglobin level plus 4 times the insulin dose] of ≤9) was observed in 43% of participants in the golimumab group and in 7% of those in the placebo group (difference, 36 percentage points; 95% CI, 22 to 55). The mean number of hypoglycemic events did not differ between the trial groups. Hypoglycemic events that were recorded as adverse events at the discretion of investigators were reported in 13 participants (23%) in the golimumab group and in 2 (7%) of those in the placebo group. Antibodies to golimumab were detected in 30 participants who received the drug; 29 had antibody titers lower than 1:1000, of whom 12 had positive results for neutralizing antibodies.

CONCLUSIONS

Among children and young adults with newly diagnosed overt type 1 diabetes, golimumab resulted in better endogenous insulin production and less exogenous insulin use than placebo. (Funded by Janssen Research and Development; T1GER ClinicalTrials.gov number, NCT02846545.).

Lower risk of primary Sjogren's syndrome in patients with dengue virus infection: a nationwide cohort study in Taiwan

The data concerning the association between dengue viruses (DV) infection and autoimmune diseases (ADs) remain unclear and are scarce. This nationwide population-based cohort study assessed the risk of ADs among patients with DV infection. We analyzed Taiwanese medical data from the Registry of the National Notifiable Disease Reporting System of Taiwan’s Centers for Disease Control between 1998 and 2015 and identified patients with DV infection. From the entire general population data in the National Health Insurance Research Database, we randomly selected a comparison cohort that was individual matching by age, sex, residence, and index date. We analyzed the risk of ADs using a Cox proportional hazards regression model stratified by sex, age, and residence. We enrolled 29,365 patients with DV infection (50.68% men; mean age, 44.13 years) and 117,460 age-, sex-, and residence-matched controls in the present study. The incidence rates of organ-specific ADs were nonsignificantly higher in the DV cohort than in the non-DV control cohort. An approximately 70% lower risk of primary Sjogren syndrome (pSS) was evident in the DV cohort than in the non-DV control cohort with an adjusted hazard ratio of 0.30 (95% confidence interval 0.13–0.67) after adjusting for comorbidities in matched design. By contrast, the other systemic ADs were nonsignificantly lower in the DV cohort than in the non-DV control cohort. This nationwide long-term cohort study demonstrated that patients with DV infection had a lower risk of primary Sjogren syndrome than those without DV infection.

Key Points • This retrospective, longitudinal cohort observational study shows that patients with DV infection had a lower risk of pSS than those without DV infection. • The DV cohort had an approximately 70% lower risk of pSS than the control group, with a multivariate-adjusted HR of 0.30. • On the basis of this result, we contended that DV infection has a protective effect that reduces the risk of pSS.

Potential roles of chromium on inflammatory biomarkers in diabetes: A Systematic

Diabetes, as a low-grade chronic inflammatory disease, causes disruption in proper function of immune and metabolic system. Chromium is an important element required for normal lipid and glucose metabolism. Chromium deficiency is correlated with elevation in cardiometabolic risk, which results from increased inflammation. This systematic review was conducted to discover the potential roles of chromium on inflammatory biomarkers. Eligible studies were all in vitro, animal and human studies published in English-language journals from inception until October 2018. PubMed, Scopus, Embase, ProQuest and Google Scholar databases were searched to fined interventional studies from the effects of chromium on inflammatory biomarkers such as tumour necrosis factor a (TNF-a), C-reactive protein (CRP), interleukins, monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1) and adipocytokines in hyperglycaemia and diabetes. Out of 647 articles found in the search, only 14 articles were eligible for analysis, three in vitro studies, eight animal studies and three human studies. Twelve of the 14 studies included in this review, chromium significantly decreased inflammatory factors. The findings of this review indicate, based on in vitro and in vivo studies, that chromium might have potential anti-inflammatory properties, but some of the studies did not show anti-inflammatory effects for chromium (two studies). There are only three studies in humans with controversial results. Therefore, more consistent randomized double-blind controlled trials are needed to reach relevant clinical recommendations, as well as to determine the precise mechanism, of chromium on inflammation in diabetes.

Prevention of clinical and histological signs of MOG-induced experimental allergic encephalomyelitis by prolonged treatment with recombinant human EGF

Epidermal growth factor (EGF) represents the prototype of the group I EGF family. The pleiotropic effects of the EGF have attracted attention to the possibility that it could be implicated in autoimmune diseases, such as Multiple Sclerosis (MS). We show here that treatment with EGF, as a late prophylactic regime, improved the clinical and histological features of EAE, a preclinical model of MS. In silico analysis further corroborated these findings by demonstrating that EGF receptors are less expressed in CNS from patients with MS as compared to controls. Taken together these data provide clear-cut in vivo proof of concept for a beneficial role of exogenously administered EGF in MS, that may, therefore, represent a novel therapeutic approach.

TNF-TNFR2 Signaling Inhibits Th2 and Th17 Polarization and Alleviates Allergic Airway Inflammation

BACKGROUND

TNF-TNFR2 signaling has been indicated to be involved in CD4+ T lymphocyte differentiation. However, its role in allergic airway inflammation is not well understood.

OBJECTIVES

The aim of this study was to investigate the role of TNF-TNFR2 signaling in allergic airway inflammation.

METHODS AND RESULTS

In this study, we used an allergen-induced asthma model to show that TNF-TNFR2 signaling alleviated allergic airway inflammation by reducing the airway infiltration of eosinophils and neutrophils. Activated TNF-TNFR2 signaling decreased the expression of Th2 and Th17 cytokines in serum and bronchoalveolar lavage fluid. Furthermore, TNF-TNFR2 signaling inhibited Th2 and Th17 polarization but promoted Th1 and CD4+CD25+ T cell differentiation in vivo.

CONCLUSIONS

Our study indicates that TNF-TNFR2 signaling alleviates allergic airway inflammation through inhibition of Th2 and Th17 cell differentiation.

Tumor Necrosis Factor α and Regulatory T Cells in Oncoimmunology

Tumor necrosis factor α (TNF) is a potent pro-inflammatory cytokine that has deleterious effect in some autoimmune diseases, which led to the use of anti-TNF drugs in some of these diseases. However, some rare patients treated with these drugs paradoxically develop an aggravation of their disease or new onset autoimmunity, revealing an immunosuppressive facet of TNF. A possible mechanism of this observation is the direct and positive effect of TNF on regulatory T cells (Tregs) through its binding to the TNF receptor type 2 (TNFR2). Indeed, TNF is able to increase expansion, stability, and possibly function of Tregs via TNFR2. In this review, we discuss the role of TNF in graft-versus-host disease as an example of the ambivalence of this cytokine in the pathophysiology of an immunopathology, highlighting the therapeutic potential of triggering TNFR2 to boost Treg expansion. We also describe new targets in immunotherapy of cancer, emphasizing on the putative suppressive effect of TNF in antitumor immunity and of the interest of blocking TNFR2 to regulate the Treg compartment.

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.

Molecular and Cellular Requirements for the Assembly of Tertiary Lymphoid Structures

At sites of chronic inflammation, recruited immune cells form structures that resemble secondary lymphoid organs (SLOs). Those are characterized by segregated areas of prevalent T- or B-cell aggregation, differentiation of high endothelial venules (HEVs) and local activation of resident stromal cells. B-cell proliferation and affinity maturation towards locally displayed autoantigens have been demonstrated at those sites, known as tertiary lymphoid structures (TLSs). TLS formation has been associated with local disease persistence and progression as well as increased systemic manifestations. While bearing a similar histological structure to SLO, the signals that regulate TLS and SLO formation can diverge, and a series of pro-inflammatory cytokines has been ascribed as responsible for TLS formation at different anatomical sites. Here we review the structural elements as well as the signals responsible for TLS aggregation, aiming to provide an overview to this complex immunological phenomenon.

Cellular and Vascular Components of Tertiary Lymphoid Structures

Inflammatory immune cells recruited at the site of chronic inflammation form structures that resemble secondary lymphoid organs (SLO). These are characterized by segregated areas of prevalent T- or B-cell aggregation, differentiation of high endothelial venules, and local activation of resident stromal cells, including lymphatic endothelial cells. B-cell proliferation and affinity maturation toward locally displayed autoantigens have been demonstrated at these sites, known as tertiary lymphoid structures (TLS). TLS formation during chronic inflammation has been associated with local disease persistence and progression, as well as increased systemic manifestations. While bearing a similar histological structure to SLO, the signals that regulate TLS and SLO formation can diverge and a series of pro-inflammatory cytokines have been ascribed as responsible for TLS formation at different anatomical sites. Moreover, for a long time the structural compartment that regulates TLS homeostasis, including survival and recirculation of leucocytes has been neglected. In this chapter, we summarize the novel data available on TLS formation, structural organization, and the functional and anatomical links connecting TLS and SLOs.

Foundations of Immunometabolism and Implications for Metabolic Health and Disease

Highly ordered interactions between immune and metabolic responses are evolutionarily conserved and paramount for tissue and organismal health. Disruption of these interactions underlies the emergence of many pathologies, particularly chronic non-communicable diseases such as obesity and diabetes. Here, we examine decades of research identifying the complex immunometabolic signaling networks and the cellular and molecular events that occur in the setting of altered nutrient and energy exposures and offer a historical perspective. Furthermore, we describe recent advances such as the discovery that a broad complement of immune cells play a role in immunometabolism and the emerging evidence that nutrients and metabolites modulate inflammatory pathways. Lastly, we discuss how this work may eventually lead to tangible therapeutic advancements to promote health.

The dual role of scavenger receptor class A in development of diabetes in autoimmune NOD mice

Human type 1 diabetes is an autoimmune disease that results from the autoreactive destruction of pancreatic β cells by T cells. Antigen presenting cells including dendritic cells and macrophages are required to activate and suppress antigen-specific T cells. It has been suggested that antigen uptake from live cells by dendritic cells via scavenger receptor class A (SR-A) may be important. However, the role of SR-A in autoimmune disease is unknown. In this study, SR-A-/- nonobese diabetic (NOD) mice showed significant attenuation of insulitis, lower levels of insulin autoantibodies, and suppression of diabetes development compared with NOD mice. We also found that diabetes progression in SR-A-/- NOD mice treated with low-dose polyinosinic-polycytidylic acid (poly(I:C)) was significantly accelerated compared with that in disease-resistant NOD mice treated with low-dose poly(I:C). In addition, injection of high-dose poly(I: C) to mimic an acute RNA virus infection significantly accelerated diabetes development in young SR-A-/- NOD mice compared with untreated SR-A-/- NOD mice. Pathogenic cells including CD4+CD25+ activated T cells were increased more in SR-A-/- NOD mice treated with poly(I:C) than in untreated SR-A-/- NOD mice. These results suggested that viral infection might accelerate diabetes development even in diabetes-resistant subjects. In conclusion, our studies demonstrated that diabetes progression was suppressed in SR-A-/- NOD mice and that acceleration of diabetes development could be induced in young mice by poly(I:C) treatment even in SR-A-/- NOD mice. These results suggest that SR-A on antigen presenting cells such as dendritic cells may play an unfavorable role in the steady state and a protective role in a mild infection. Our findings imply that SR-A may be an important target for improving therapeutic strategies for type 1 diabetes.

Transcription of the gene encoding TNF-α is increased by IL-1β in rat and human islets and β-cell lines

Synthesis and secretion of immunomodulatory proteins, such as cytokines and chemokines, controls the inflammatory response within pancreatic islets. When this inflammation does not resolve, destruction of pancreatic islet β-cells leads to diabetes mellitus. Production of the soluble mediators of inflammation, such as TNF-α and IL-1β, from resident and invading immune cells, as well as directly from islet β-cells, is also associated with suboptimal islet transplantation outcomes. In this study, we found that IL-1β induces rapid increases in TNF-α mRNA in rat and human islets and the 832/13 clonal β-cell line. The surge in transcription of the TNF-α gene required the inhibitor of kappa B kinase beta (IκKβ), the p65 subunit of the NF-κB and a signal-specific recruitment of RNA polymerase II to the gene promoter. Of note was the increased intracellular production of TNF-α protein in a manner consistent with mRNA accumulation in response to IL-1β, but no detectable secretion of TNF-α into the media. Additionally, TNF-α specifically induces expression of CD11b, but not CD11c, on neutrophils, which could contribute to the inflammatory milieu and diabetes progression. We conclude that activation of the NF-κB pathway in pancreatic β-cells leads to rapid intracellular production of the pro-inflammatory TNF-α protein through a combination of specific histone covalent modifications and NF-κB signaling pathways.

Managing macrophages in rheumatoid arthritis by reform or removal

Macrophages play a central role in the pathogenesis of rheumatoid arthritis (RA). There is an imbalance of inflammatory and antiinflammatory macrophages in RA synovium. Although the polarization and heterogeneity of macrophages in RA have not been fully uncovered, the identity of macrophages in RA can potentially be defined by their products, including the co-stimulatory molecules, scavenger receptors, different cytokines/chemokines and receptors, and transcription factors. In the last decade, efforts to understand the polarization, apoptosis regulation, and novel signaling pathways in macrophages, as well as how distinct activated macrophages influence disease progression, have led to strategies that target macrophages with varied specificity and selectivity. Major targets that are related to macrophage development and apoptosis include TNF-α, IL-1, IL-6, GM-CSF, M-CSF, death receptor 5 (DR5), Fas, and others, as listed in Table 1. Combined data from clinical, preclinical, and animal studies of inhibitors of these targets have provided valuable insights into their roles in the disease progression and, subsequently, have led to the evolving therapeutic paradigms in RA. In this review, we propose that reestablishment of macrophage equilibrium by inhibiting the development of, and/or eliminating, the proinflammatory macrophages will be an effective therapeutic approach for RA and other autoimmune diseases.

Role of TNFR1 in the innate airway hyperresponsiveness of obese mice

The purpose of this study was to examine the role of tumor necrosis factor receptor 1 (TNFR1) in the airway hyperresponsiveness characteristic of obese mice. Airway responsiveness to intravenous methacholine was measured using the forced oscillation technique in obese Cpe(fat) mice that were either sufficient or genetically deficient in TNFR1 (Cpe(fat) and Cpe(fat)/TNFR1(-/-) mice) and in lean mice that were either sufficient or genetically deficient in TNFR1 [wild-type (WT) and TNFR1(-/-) mice]. Compared with lean WT mice, Cpe(fat) mice exhibited airway hyperresponsiveness. Airway hyperresponsives was also greater in Cpe(fat)/TNFR1(-/-) than in Cpe(fat) mice. Compared with WT mice, Cpe(fat) mice had increases in bronchoalveolar lavage fluid concentrations of several inflammatory moieties including eotaxin, IL-9, IP-10, KC, MIG, and VEGF. These factors were also significantly elevated in Cpe(fat)/TNFR1(-/-) vs. TNFR1(-/-) mice. Additional moieties including IL-13 were also elevated in Cpe(fat)/TNFR1(-/-) vs. TNFR1(-/-) mice but not in Cpe(fat) vs. WT mice. IL-17A mRNA expression was greater in Cpe(fat)/TNFR1(-/-) vs. Cpe(fat) mice and in TNFR1(-/-) vs. WT mice. Analysis of serum indicated that obesity resulted in systemic as well as pulmonary inflammation, but TNFR1 deficiency had little effect on this systemic inflammation. Our results indicate that TNFR1 is protective against the airway hyperresponsiveness associated with obesity and suggest that effects on pulmonary inflammation may be contributing to this protection.

Minimal-change disease secondary to etanercept

Etanercept is a soluble tumor necrosis factor alpha (TNFα) receptor which is widely used in the treatment of rheumatoid arthritis, psoriasis and other autoimmune inflammatory disorders. It is known for its relative lack of nephrotoxicity; however, there are reports on the development of nephrotic syndrome associated with the treatment with TNFα antagonists. Here, we describe a patient with psoriasis who developed biopsy-proven minimal-change disease (MCD) shortly after initiating etanercept. Our case is unique in that the MCD resolved after discontinuation of this medication, notably without the use of corticosteroids, strongly suggesting a drug-related phenomenon.

The role of TNF-α in mice with type 1- and 2- diabetes

Background

Previously, we have demonstrated that short-term treatment of new onset diabetic Non-obese diabetic (NOD) mice, mice that are afflicted with both type 1 (T1D) and type 2 (T2D) diabetes with either Power Mix (PM) regimen or alpha1 antitrypsin (AAT) permanently restores euglycemia, immune tolerance to self-islets and normal insulin signaling.

Methodology and Principal Findings

To search for relevant therapeutic targets, we have applied genome wide transcriptional profiling and systems biology oriented bioinformatics analysis to examine the impact of the PM and AAT regimens upon pancreatic lymph node (PLN) and fat, a crucial tissue for insulin dependent glucose disposal, in new onset diabetic non-obese diabetic (NOD) mice. Systems biology analysis identified tumor necrosis factor alpha (TNF-α) as the top focus gene hub, as determined by the highest degree of connectivity, in both tissues. In PLNs and fat, TNF-α interacted with 53% and 32% of genes, respectively, associated with reversal of diabetes by previous treatments and was thereby selected as a therapeutic target. Short-term anti-TNF-α treatment ablated a T cell-rich islet-invasive and beta cell-destructive process, thereby enhancing beta cell viability. Indeed anti-TNF-α treatment induces immune tolerance selective to syngeneic beta cells. In addition to these curative effects on T1D anti-TNF-α treatment restored in vivo insulin signaling resulting in restoration of insulin sensitivity.

Conclusions

In short, our molecular analysis suggested that PM and AAT both may act in part by quenching a detrimental TNF-α dependent effect in both fat and PLNs. Indeed, short-term anti-TNF-α mAb treatment restored enduring euglycemia, self-tolerance, and normal insulin signaling.

Contrasting effects of TNF and anti-TNF on the activation of effector T cells and regulatory T cells in autoimmunity

Anti-TNF treatment is effective in a majority of rheumatoid arthritis (RA), however, this treatment can unexpectedly trigger the onset or exacerbate multiple sclerosis (MS). Recent progress in cellular immunology research provides a new framework to analyze the possible mechanism underlying these puzzling contradictory effects. The delicate balance of protective CD4(+)FoxP3(+) regulatory T cells (Tregs) and pathogenic CD4(+)FoxP3(-) effector T cells (Teffs) is crucial for the outcome of anti-TNF treatment of autoimmune disease. There is convincing evidence that TNF, in addition to stimulating Teffs, is able to activate and expand Tregs through TNFR2, which is preferentially expressed by Tregs. Therefore, the contrasting effects of TNF on Tregs and Teffs are likely to determine the therapeutic effect of anti-TNF treatment. In this review, we discuss the current understanding of the general effect of TNF on the activation of T cells, and the impact of TNF on the function of Teffs and Tregs. Understanding the differential effects of TNF on Teffs and Tregs is fundamentally required for the design of more effective and safer anti-TNF or anti-TNF receptor(s) therapeutic strategy for autoimmune diseases.

The central role of calcium in the effects of cytokines on beta-cell function: implications for type 1 and type 2 diabetes

The appropriate regulation of intracellular calcium is a requirement for proper cell function and survival. This review focuses on the effects of proinflammatory cytokines on calcium regulation in the insulin-producing pancreatic beta-cell and how normal stimulus-secretion coupling, organelle function, and overall beta-cell viability are impacted. Proinflammatory cytokines are increasingly thought to contribute to beta-cell dysfunction not only in type 1 diabetes (T1D), but also in the progression of type 2 diabetes (T2D). Cytokine-induced disruptions in calcium handling result in reduced insulin release in response to glucose stimulation. Cytokines can alter intracellular calcium levels by depleting calcium from the endoplasmic reticulum (ER) and by increasing calcium influx from the extracellular space. Depleting ER calcium leads to protein misfolding and activation of the ER stress response. Disrupting intracellular calcium may also affect organelles, including the mitochondria and the nucleus. As a chronic condition, cytokine-induced calcium disruptions may lead to beta-cell death in T1D and T2D, although possible protective effects are also discussed. Calcium is thus central to both normal and pathological cell processes. Because the tight regulation of intracellular calcium is crucial to homeostasis, measuring the dynamics of calcium may serve as a good indicator of overall beta-cell function.

Current state of type 1 diabetes immunotherapy: incremental advances, huge leaps, or more of the same?

Thus far, none of the preclinically successful and promising immunomodulatory agents for type 1 diabetes mellitus (T1DM) has conferred stable, long-term insulin independence to diabetic patients. The majority of these immunomodulators are humanised antibodies that target immune cells or cytokines. These as well as fusion proteins and inhibitor proteins all share varying adverse event occurrence and severity. Other approaches have included intact putative autoantigens or autoantigen peptides. Considerable logistical outlays have been deployed to develop and to translate humanised antibodies targeting immune cells, cytokines, and cytokine receptors to the clinic. Very recent phase III trials with the leading agent, a humanised anti-CD3 antibody, call into question whether further development of these biologics represents a step forward or more of the same. Combination therapies of one or more of these humanised antibodies are also being considered, and they face identical, if not more serious, impediments and safety issues. This paper will highlight the preclinical successes and the excitement generated by phase II trials while offering alternative possibilities and new translational avenues that can be explored given the very recent disappointment in leading agents in more advanced clinical trials.

TNF receptor 1 deficiency increases regulatory T cell function in nonobese diabetic mice

TNF has been implicated in the pathogenesis of type 1 diabetes. When administered early in life, TNF accelerates and increases diabetes in NOD mice. However, when administered late, TNF decreases diabetes incidence and delays onset. TNFR1-deficient NOD mice were fully protected from diabetes and only showed mild peri-insulitis. To further dissect how TNFR1 deficiency affects type 1 diabetes, these mice were crossed to β cell-specific, highly diabetogenic TCR transgenic I-A(g7)-restricted NOD4.1 mice and Kd-restricted NOD8.3 mice. TNFR1-deficient NOD4.1 and NOD8.3 mice were protected from diabetes and had significantly less insulitis compared with wild type NOD4.1 and NOD8.3 controls. Diabetic NOD4.1 mice rejected TNFR1-deficient islet grafts as efficiently as control islets, confirming that TNFR1 signaling is not directly required for β cell destruction. Flow cytometric analysis showed a significant increase in the number of CD4(+)CD25(+)Foxp3(+) T regulatory cells in TNFR1-deficient mice. TNFR1-deficient T regulatory cells were functionally better at suppressing effector cells than were wild type T regulatory cells both in vitro and in vivo. This study suggests that blocking TNF signaling may be beneficial in increasing the function of T regulatory cells and suppression of type 1 diabetes.

Type 1 Diabetes: Etiology, Immunology, and Therapeutic Strategies

Type 1 diabetes (T1D) is a chronic autoimmune disease in which destruction or damaging of the beta-cells in the islets of Langerhans results in insulin deficiency and hyperglycemia. We only know for sure that autoimmunity is the predominant effector mechanism of T1D, but may not be its primary cause. T1D precipitates in genetically susceptible individuals, very likely as a result of an environmental trigger. Current genetic data point towards the following genes as susceptibility genes: HLA, insulin, PTPN22, IL2Ra, and CTLA4. Epidemiological and other studies suggest a triggering role for enteroviruses, while other microorganisms might provide protection. Efficacious prevention of T1D will require detection of the earliest events in the process. So far, autoantibodies are most widely used as serum biomarker, but T-cell readouts and metabolome studies might strengthen and bring forward diagnosis. Current preventive clinical trials mostly focus on environmental triggers. Therapeutic trials test the efficacy of antigen-specific and antigen-nonspecific immune interventions, but also include restoration of the affected beta-cell mass by islet transplantation, neogenesis and regeneration, and combinations thereof. In this comprehensive review, we explain the genetic, environmental, and immunological data underlying the prevention and intervention strategies to constrain T1D.

Calcineurin/nuclear factor of activated T cells and MAPK signaling induce TNF-{alpha} gene expression in pancreatic islet endocrine cells

Cytokines contribute to pancreatic islet inflammation, leading to impaired glucose homeostasis and diabetic diseases. A plethora of data shows that proinflammatory cytokines are produced in pancreatic islets by infiltrating mononuclear immune cells. Here, we show that pancreatic islet α cells and β cells express tumor necrosis factor-α (TNF-α) and other cytokines capable of promoting islet inflammation when exposed to interleukin-1β (IL-1β). Cytokine expression by β cells was dependent on calcineurin (CN)/nuclear factor of activated T cells (NFAT) and MAPK signaling. NFAT associated with the TNF-α promoter in response to stimuli and synergistically activated promoter activity with ATF2 and c-Jun. In contrast, the β-cell-specific transcriptional activator MafA could repress NFAT-mediated TNF-α gene expression whenever C/EBP-β was bound to the promoter. NFAT differentially regulated the TNF-α gene depending upon the expression and MAPK-dependent activation of interacting basic leucine zipper partners in β cells. Both p38 and JNK were required for induction of TNF-α mRNA and protein expression. Collectively, the data show that glucose and IL-1β can activate signaling pathways, which control induction and repression of cytokines in pancreatic endocrine cells. Thus, by these mechanisms, pancreatic β cells themselves may contribute to islet inflammation and their own immunological destruction in the pathogenesis of diabetes.

Identification of a serum-induced transcriptional signature associated with type 1 diabetes in the BioBreeding rat

OBJECTIVE

Inflammatory mediators associated with type 1 diabetes are dilute and difficult to measure in the periphery, necessitating development of more sensitive and informative biomarkers for studying diabetogenic mechanisms, assessing preonset risk, and monitoring therapeutic interventions.

RESEARCH DESIGN AND METHODS

We previously utilized a novel bioassay in which human type 1 diabetes sera were used to induce a disease-specific transcriptional signature in unrelated, healthy peripheral blood mononuclear cells (PBMCs). Here, we apply this strategy to investigate the inflammatory state associated with type 1 diabetes in biobreeding (BB) rats.

RESULTS

Consistent with their common susceptibility, sera of both spontaneously diabetic BB DRlyp/lyp and diabetes inducible BB DR+/+ rats induced transcription of cytokines, immune receptors, and signaling molecules in PBMCs of healthy donor rats compared with control sera. Like the human type 1 diabetes signature, the DRlyp/lyp signature, which is associated with progression to diabetes, was differentiated from that of the DR+/+ by induction of many interleukin (IL)-1-regulated genes. Supplementing cultures with an IL-1 receptor antagonist (IL-1Ra) modulated the DRlyp/lyp signature (P < 10(-6)), while administration of IL-1Ra to DRlyp/lyp rats delayed onset (P = 0.007), and sera of treated animals did not induce the characteristic signature. Consistent with the presence of immunoregulatory cells in DR+/+ rats was induction of a signature possessing negative regulators of transcription and inflammation.

CONCLUSIONS

Paralleling our human studies, serum signatures in BB rats reflect processes associated with progression to type 1 diabetes. Furthermore, these studies support the potential utility of this approach to detect changes in the inflammatory state during therapeutic intervention.

Evidence that low-grade systemic inflammation can induce islet dysfunction as measured by impaired calcium handling

In obesity and the early stages of type 2 diabetes (T2D), proinflammatory cytokines are mildly elevated in the systemic circulation. This low-grade systemic inflammation exposes pancreatic islets to these circulating cytokines at much lower levels than seen within the islet during insulitis. These low-dose effects have not been well described. We examined mouse islets treated overnight with a low-dose cytokine combination commonly associated with inflammation (TNF-alpha, IL-1 beta, and IFN-gamma). We then examined islet function primarily using intracellular calcium ([Ca(2+)](i)), a key component of insulin secretion and cytokine signaling. Cytokine-treated islets demonstrated several features that suggested dysfunction including excess [Ca(2+)](i) in low physiological glucose (3mM), reduced responses to glucose stimulation, and disrupted [Ca(2+)](i) oscillations. Interestingly, islets taken from young db/db mice showed similar disruptions in [Ca(2+)](i) dynamics as cytokine-treated islets. Additional studies of control islets showed that the cytokine-induced elevation in basal [Ca(2+)](i) was due to both greater calcium influx through L-type-calcium-channels and reduced endoplasmic reticulum (ER) calcium storage. Many of these cytokine-induced disruptions could be reproduced by SERCA blockade. Our data suggest that chronic low-grade inflammation produces circulating cytokine levels that are sufficient to induce beta-cell dysfunction and may play a contributing role in beta-cell failure in early T2D.

Critical role for TNF in the induction of human antigen-specific regulatory T cells by tolerogenic dendritic cells

TNF is a pleiotropic cytokine with differential effects on immune cells and diseases. Anti-TNF therapy was shown to be effective in rheumatoid arthritis but proved inefficient or even detrimental in other autoimmune diseases. We studied the role of TNF in the induction of Ag-specific regulatory T cells (Tregs) by tolerogenic vitamin D3-modulated human dendritic cells (VD3-DCs), which previously were shown to release high amounts of soluble TNF (sTNF) upon maturation with LPS. First, production of TNF by modulated VD3-DCs was analyzed upon maturation with LPS or CD40L with respect to both secreted (cleaved) TNF (sTNF) and expression of the membrane-bound (uncleaved) form of TNF (mTNF). Next, TNF antagonists were tested for their effect on induction of Ag-specific Tregs by modulated DCs and the subsequent functionality of these Tregs. VD3-DCs expressed greater amounts of mTNF than did control DCs (nontreated DCs), independent of the maturation protocol. Inhibition of TNF with anti-TNF Ab (blocking both sTNF and mTNF) during the priming of Tregs with VD3-DCs prevented generation of Tregs and their suppression of proliferation of CD4(+) T cells. In contrast, sTNF receptor II (sTNFRII), mainly blocking sTNF, did not change the suppressive capacity of Tregs. Blocking of TNFRII by anti-CD120b Ab during Treg induction similarly abrogated their subsequent suppressive function. These data point to a specific role for mTNF on VD3-DCs in the induction of Ag-specific Tregs. Interaction between mTNF and TNFRII instructs the induction of suppressive Tregs by VD3-DCs. Anti-TNF therapy may therefore act adversely in different patients or disease pathways.

Immunotherapy of type 1 diabetes: where are we and where should we be going?

Type 1 diabetes (T1D) is a chronic autoimmune disorder characterized by destruction of insulin-producing pancreatic beta cells. Many broad-based immunosuppressive and antigen-specific immunoregulatory therapies have been and are currently being evaluated for their utility in the prevention and treatment of T1D. Looking forward, this review discusses the potential therapeutic use of antigen-specific tolerance strategies, including tolerance induced by "tolerogenic" antigen-presenting cells pulsed with diabetogenic antigens and transfer of induced or expanded regulatory T cells, which have demonstrated efficacy in nonobese diabetic (NOD) mice. Depending on the time of therapeutic intervention in the T1D disease process, antigen-specific immunoregulatory strategies may be employed as monotherapies, or in combination with short-term tolerance-promoting immunoregulatory drugs and/or drugs promoting differentiation of insulin-producing beta cells from endogenous progenitors.

Induction of Treg by monocyte-derived DC modulated by vitamin D3 or dexamethasone: differential role for PD-L1

Specific therapy with modulated DC may restore immunological tolerance, thereby obviating the need for chronic immunosuppression in transplantation or autoimmunity. In this study we compared the tolerizing capacity of dexamethasone (Dex)- and 1 alpha,25-dihydroxyvitamin D3 (VD3)-modulated DC. Treatment of monocytes with either VD3 or Dex resulted in DC with stable, semi-mature phenotypes compared with standard DC, with intermediate levels of co-stimulatory and MHC class II molecules, which remained unaltered after subsequent pro-inflammatory stimulation. IL-12p70 secretion was lost by VD3- and Dex-DC, whereas IL-10 secretion was unaffected. VD3-DC distinctly produced large amounts of TNF-alpha. Both VD3- and Dex-DC possessed the capacity to convert CD4 T cells into IL-10-secreting Treg potently suppressing the proliferation of responder T cells. However, only Treg induced by VD3-DC exhibited antigen specificity. VD3-, but not Dex-, DC expressed significant high levels of PD-L1 (programmed death-1 ligand), upon activation. Blockade of PD-L1 during priming redirected T cells to produce IFN-gamma instead of IL-10 and abolished acquisition of regulatory capacity. Our findings demonstrate that both VD3- and Dex-DC possess durable but differential tolerogenic features, acting via different mechanisms. Both are potentially useful to specifically down-regulate unwanted immune responses and induce immune tolerance. These modulated DC appear suitable as adjuvant in antigen-specific clinical vaccination intervention strategies.

TNF-alpha: an activator of CD4+FoxP3+TNFR2+ regulatory T cells

TNF-alpha (TNF) is a pleiotropic cytokine which can have proinflammatory or immunosuppressive effects, depending on the context, duration of exposure and disease state. The basis for the opposing actions of TNF remains elusive. The growing appreciation of CD4+FoxP3+ regulatory T cells (Tregs), which comprise approximately 10% of peripheral CD4 cells, as pivotal regulators of immune responses has provided a new framework to define the cellular and molecular basis underlying the contrasting action of TNF. TNF by itself can overcome the profound anergic state of T cell receptor-stimulated Tregs. Furthermore, in concert with IL-2, TNF selectively activates Tregs, resulting in proliferation, upregulation of FoxP3 expression and increases in their suppressive activity. Both human and mouse Tregs predominantly express TNFR2, making it possible for TNF to enhance Treg activity, which helps limit the collateral damage caused by excessive immune responses and eventually terminates immune response. TNFR2-expressing CD4+FoxP3+ Tregs comprise approximately 40% of peripheral Tregs in normal mice and present the maximally suppressive subset of Tregs. In this review, studies describing the action of TNF on Treg function will be discussed. The role of Tregs in the autoimmune disorders and cancer as well as the effect of anti-TNF therapy on Tregs, especially in rheumatoid arthritis, will also be considered.

Tumor necrosis factor-alpha does not mediate diabetes-induced vascular inflammation in mice

OBJECTIVE

Vascular inflammation is a key feature of both micro- and macrovascular complications in diabetes. Several lines of evidence have implicated the cytokine tumor necrosis factor (TNF) alpha as an important mediator of inflammation in diabetes. In the present study we evaluated the role of TNF alpha in streptozotocin (STZ)-induced diabetes on vascular inflammation in C57BL/6 wild-type and apoE-/- mice.

METHODS AND RESULTS

Diabetes increased the expression of vascular cell adhesion molecule (VCAM)-1 in cerebral arteries 150 m in diameter as well as the macrophage accumulation in aortic root atherosclerotic plaques in apoE-/- mice. A more pronounced vascular inflammatory response was observed in diabetic TNF alpha-deficient apoE-/- mice. These mice were also characterized by increased accumulation of IgG and IgM autoantibodies in atherosclerotic lesions. Diabetes also increased VCAM-1 expression and plaque formation in apoE-competent TNF alpha -/- mice, whereas no such effects were observed in C57BL/6 wild-type mice.

CONCLUSIONS

The present findings suggest that TNF alpha does not mediate diabetic-induced vascular inflammation in mice and reveal an unexpected protective role for TNF alpha. These effects are partly attributable to a direct antiinflammatory role of TNF alpha, but may also reflect a defective development of the immune system in these mice.

Is there a feudal hierarchy amongst regulatory immune cells? More than just Tregs

Nature has provided the developing immune system with several checkpoints important for the maintenance of tolerance and the prevention of autoimmunity. The regulatory mechanisms operating in the periphery of the system are mediated by subsets of regulatory cells, now considered principal contributors to peripheral tolerance. Regulatory T cells (Tregs) have received titanic interest in the past decade, placing them at the centre of immuno-suppressive reactions. However, it has become clearer that other immune suppressive cells inhibit auto-reactivity as effectively as Tregs. The function of Tregs and other regulatory cells in rheumatoid arthritis will be discussed in this review.

Mechanisms Of Complete Freund's Adjuvant Protection Against Diabetes in Bb Rats: Induction Of Non-Specific Suppressor Cells

We have previously reported that a single injection of complete Freund's adjuvant (CFA) can prevent diabetes appearance in diabetes-prone (DP) BB rats. In this study, we investigated further the mechanism of CFA-induced protection from diabetes. We found that adoptive transfer of splenic cells from CFA-treated DP rats into young DP rats protected the latter from diabetes development. This suggested that CFA-induced protection from diabetes resulted from activation of regulatory (suppressor) cells. Cell mixing experiments in vitro indicated that CFA activated splenic cells with antigen-nonspecific suppressor activity (suppression of lymphoproliferative responses to lipopolysaccharide and to allogeneic splenic cells). Fractionation of splenic cells on Percoll revealed that the suppressor activity resided in low density cells relatively depleted of T-cells, B-cells, macrophages and NK cells. These results suggest that non-specific (natural) suppressor cells in CFA-treated BB rats may be responsible for suppressing autoimmune responses and preventing insulitis and diabetes development.

Immunoregulatory role of TNFalpha in inflammatory kidney diseases

Tumor necrosis factor alpha (TNFalpha), a pleiotropic cytokine, plays important inflammatory roles in renal diseases such as lupus nephritis, anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis and renal allograft rejection. However, TNFalpha also plays critical immunoregulatory roles that are required to maintain immune homeostasis. These complex biological functions of TNFalpha are orchestrated by its two receptors, TNFR1 and TNFR2. For example, TNFR2 promotes leukocyte infiltration and tissue injury in an animal model of immune complex-mediated glomerulonephritis. On the other hand, TNFR1 plays an immunoregulatory function in a murine lupus model with a deficiency in this receptor that leads to more severe autoimmune symptoms. In humans, proinflammatory and immunoregulatory roles for TNFalpha are strikingly illustrated in patients on anti-TNFalpha medications: These treatments are greatly beneficial in certain inflammatory diseases such as rheumatoid arthritis but, on the other hand, are also associated with the induction of autoimmune lupus-like syndromes and enhanced autoimmunity in multiple sclerosis patients. The indication for anti-TNFalpha treatments in renal inflammatory diseases is still under discussion. Ongoing clinical trials may help to clarify the potential benefit of such treatments in lupus nephritis and ANCA-associated glomerulonephritis. Overall, the complex biology of TNFalpha is not fully understood. A greater understanding of the function of its receptors may provide a framework to understand its contrasting proinflammatory and immunoregulatory functions. This may lead the development of new, more specific anti-inflammatory drugs.

Accelerated pathological and clinical nephritis in systemic lupus erythematosus-prone New Zealand Mixed 2328 mice doubly deficient in TNF receptor 1 and TNF receptor 2 via a Th17-associated pathway

TNF-alpha has both proinflammatory and immunoregulatory functions. Whereas a protective role for TNF administration in systemic lupus erythematosus (SLE)-prone (New Zealand Black x New Zealand White)F(1) mice has been established, it remains uncertain whether this effect segregates at the individual TNFR. We generated SLE-prone New Zealand Mixed 2328 mice genetically deficient in TNFR1, in TNFR2, or in both receptors. Doubly-deficient mice developed accelerated pathological and clinical nephritis with elevated levels of circulating IgG anti-dsDNA autoantibodies and increased numbers of CD4(+) T lymphocytes, especially activated memory (CD44(high)CD62L(low)) CD4(+) T cells. We show that these cells expressed a Th17 gene profile, were positive for IL-17 intracellular staining by FACS, and produced exogenous IL-17 in culture. In contrast, immunological, pathological, and clinical profiles of mice deficient in either TNFR alone did not differ from those in each other or from those in wild-type controls. Thus, total ablation of TNF-alpha-mediated signaling was highly deleterious to the host in the New Zealand Mixed 2328 SLE model. These observations may have profound ramifications for the use of TNF and TNFR antagonists in human SLE and related autoimmune disorders, as well as demonstrate, for the first time, the association of the Th17 pathway with an animal model of SLE.