Redox regulation of age-associated defects in generation and maintenance of T cell self-tolerance and immunity to foreign antigens.

Thymic atrophy reduces naive T cell production and contributes to increased susceptibility to viral infection with age. Expression of tissue-restricted antigen (TRA) genes also declines with age and has been thought to increase autoimmune disease susceptibility. We find that diminished expression of a model TRA gene in aged thymic stromal cells correlates with impaired clonal deletion of cognate T cells recognizing an autoantigen involved in atherosclerosis. Clonal deletion in the polyclonal thymocyte population is also perturbed. Distinct age-associated defects in the generation of antigen-specific T cells include a conspicuous decline in generation of T cells recognizing an immunodominant influenza epitope. Increased catalase activity delays thymic atrophy, and here, we show that it mitigates declining production of influenza-specific T cells and their frequency in lung after infection, but does not reverse declines in TRA expression or efficient negative selection. These results reveal important considerations for strategies to restore thymic function.

Function and Role of Regulatory T Cells in Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a systemic and heterogeneous autoimmune disease with symmetrical polyarthritis as its critical clinical manifestation. The basic cause of autoimmune diseases is the loss of tolerance to self or harmless antigens. The loss or functional deficiency of key immune cells, regulatory T (Treg) cells, has been confirmed in human autoimmune diseases. The pathogenesis of RA is complex, and the dysfunction of Tregs is one of the proposed mechanisms underlying the breakdown of self-tolerance leading to the progression of RA. Treg cells are a vital component of peripheral immune tolerance, and the transcription factor Foxp3 plays a major immunosuppressive role. Clinical treatment for RA mainly utilizes drugs to alleviate the progression of disease and relieve disease activity, and the ideal treatment strategy should be to re-induce self-tolerance before obvious tissue injury. Treg cells are one of the ideal options. This review will introduce the classification, mechanism of action, and characteristics of Treg cells in RA, which provides insights into clinical RA treatment.

Immune-Related Adverse Events Associated With Immune Checkpoint Inhibitor Therapy.

As part of immune surveillance, killer T lymphocytes search for cancer cells and destroy them. Some cancer cells, however, develop escape mechanisms to evade detection and destruction. One of these mechanisms is the expression of cell surface proteins which allow the cancer cell to bind to proteins on T cells called checkpoints to switch off and effectively evade T-cell-mediated destruction. Immune checkpoint inhibitors (ICIs) are antibodies that block the binding of cancer cell proteins to T-cell checkpoints, preventing the T-cell response from being turned off by cancer cells and enabling killer T cells to attack. In other words, ICIs restore innate antitumor immunity, as opposed to traditional chemotherapies that directly kill cancer cells. Given their relatively excellent risk-benefit ratio when compared to other forms of cancer treatment modalities, ICIs are now becoming ubiquitous and have revolutionized the treatment of many types of cancer. Indeed, the prognosis of some patients is so much improved that the threshold for admission for intensive care should be adjusted accordingly. Nevertheless, by modulating immune checkpoint activity, ICIs can disrupt the intricate homeostasis between inhibition and stimulation of immune response, leading to decreased immune self-tolerance and, ultimately, autoimmune complications. These immune-related adverse events (IRAEs) may virtually affect all body systems. Multiple IRAEs are common and may range from mild to life-threatening. Management requires a multidisciplinary approach and consists mainly of immunosuppression, cessation or postponement of ICI treatment, and supportive therapy, which may require surgical intervention and/or intensive care. We herein review the current literature surrounding IRAEs of interest to anesthesiologists and intensivists. With proper care, fatality (0.3%-1.3%) is rare.

Intestinal Delivery of Proinsulin and IL-10 via Lactococcus lactis Combined With Low-Dose Anti-CD3 Restores Tolerance Outside the Window of Acute Type 1 Diabetes Diagnosis.

A combination treatment (CT) of proinsulin and IL-10 orally delivered via genetically modified Lactococcus lactis bacteria combined with low-dose anti-CD3 (aCD3) therapy successfully restores glucose homeostasis in newly diagnosed non-obese diabetic (NOD) mice. Tolerance is accompanied by the accumulation of Foxp3+ regulatory T cells (Tregs) in the pancreas. To test the potential of this therapy outside the window of acute diabetes diagnosis, we substituted autoimmune diabetic mice, with disease duration varying between 4 and 53 days, with syngeneic islets at the time of therapy initiation. Untreated islet recipients consistently showed disease recurrence after 8.2 ± 0.7 days, while 32% of aCD3-treated and 48% of CT-treated mice remained normoglycemic until 6 weeks after therapy initiation (P < 0.001 vs. untreated controls for both treatments, P < 0.05 CT vs. aCD3 therapy). However, mice that were diabetic for more than 2 weeks before treatment initiation were less efficient at maintaining normoglycemia than those treated within 2 weeks of diabetes diagnosis, particularly in the aCD3-treated group. The complete elimination of endogenous beta cell mass with alloxan at the time of diabetes diagnosis pointed toward the significance of continuous feeding of the islet antigen proinsulin at the time of aCD3 therapy for treatment success. The CT providing proinsulin protected 69% of mice, compared to 33% when an irrelevant antigen (ovalbumin) was combined with aCD3 therapy, or to 27% with aCD3 therapy alone. Sustained tolerance was accompanied with a reduction of IGRP+CD8+ autoreactive T cells and an increase in insulin-reactive (InsB12-20 or InsB13-2) Foxp3+CD4+ Tregs, with a specific accumulation of Foxp3+ Tregs around the insulin-containing islet grafts after CT with proinsulin. The combination of proinsulin and IL-10 via oral Lactococcus lactis with low-dose aCD3 therapy can restore tolerance to beta cells in autoimmune diabetic mice, also when therapy is started outside the window of acute diabetes diagnosis, providing persistence of insulin-containing islets or prolonged beta cell function.

A GM-CSF-neuroantigen tolerogenic vaccine elicits inefficient antigen recognition events below the CD40L triggering threshold to expand CD4+ CD25+ FOXP3+ Tregs that inhibit experimental autoimmune encephalomyelitis (EAE).

BACKGROUND: Tolerogenic vaccines represent antigen-specific interventions designed to re-establish self-tolerance and thereby alleviate autoimmune diseases, which collectively comprise over 100 chronic inflammatory diseases afflicting more than 20 million Americans. Tolerogenic vaccines comprised of single-chain GM-CSF-neuroantigen (GMCSF-NAg) fusion proteins were shown in previous studies to prevent and reverse disease in multiple rodent models of experimental autoimmune encephalomyelitis (EAE) by a mechanism contingent upon the function of CD4+ CD25+ FOXP3+ regulatory T cells (Tregs). GMCSF-NAg vaccines inhibited EAE in both quiescent and inflammatory environments in association with low-efficiency T cell receptor (TCR) signaling events that elicited clonal expansion of immunosuppressive Tregs. METHODS: This study focused on two vaccines, including GMCSF-MOG (myelin oligodendrocyte glycoprotein 35-55/MOG35-55) and GMCSF-NFM (neurofilament medium peptide 13-37/NFM13-37), that engaged the transgenic 2D2 TCR with either low or high efficiencies, respectively. 2D2 mice were crossed with FOXP3 IRES eGFP (FIG) mice to track Tregs and further crossed with Rag-/- mice to reduce pre-existing Treg populations. RESULTS: This study provided evidence that low and high efficiency TCR interactions were integrated via CD40L expression levels to control the Treg/Tcon balance. The high-efficiency GMCSF-NFM vaccine elicited memory Tcon responses in association with activation of the CD40L costimulatory system. Conversely, the low-efficiency GMCSF-MOG vaccine lacked adequate TCR signal strength to elicit CD40L expression and instead elicited Tregs by a mechanism that was impaired by a CD40 agonist. When combined, the low- and high-efficiency GMCSF-NAg vaccines resulted in a balanced outcome and elicited both Tregs and Tcon responses without the predominance of a dominant immunogenic Tcon response. Aside from Treg expansion in 2D2-FIG mice, GMCSF-MOG caused a sustained decrease in TCR-ß, CD3, and CD62L expression and a sustained increase in CD44 expression in Tcon subsets. Subcutaneous administration of GMCSF-MOG without adjuvants inhibited EAE in wildtype mice, which had a replete Treg repertoire, but was pathogenic rather than tolerogenic in 2D2-FIG-Rag1-/- mice, which lacked pre-existing Tregs. CONCLUSIONS: This study provided evidence that the GMCSF-MOG vaccine elicited antigenic responses beneath the CD40L triggering threshold, which defined an antigenic niche that drove dominant expansion of tolerogenic myelin-specific Tregs that inhibited EAE.

Ethanol consumption inhibits TFH cell responses and the development of autoimmune arthritis.

Alcohol consumption is a consistent protective factor for the development of autoimmune diseases such as rheumatoid arthritis (RA). The underlying mechanism for this tolerance-inducing effect of alcohol, however, is unknown. Here we show that alcohol and its metabolite acetate alter the functional state of T follicular helper (TFH) cells in vitro and in vivo, thereby exerting immune regulatory and tolerance-inducing properties. Alcohol-exposed mice have reduced Bcl6 and PD-1 expression as well as IL-21 production by TFH cells, preventing proper spatial organization of TFH cells to form TFH:B cell conjugates in germinal centers. This effect is associated with impaired autoantibody formation, and mitigates experimental autoimmune arthritis. By contrast, T cell independent immune responses and passive models of arthritis are not affected by alcohol exposure. These data clarify the immune regulatory and tolerance-inducing effect of alcohol consumption.

Checkpoint inhibitors (CPI) and autoimmune chronic inflammatory diseases (ACIDs): tolerance and loss of tolerance in the occurrence of immuno-rheumatologic manifestations.

Immune related adverse events (irAEs) have been observed with all checkpoint inhibitors and are very frequent. The evidences coming from experimental models of congenital or acquired deficiency of CTLA-4 or from PD-1 knock-out mice, provided all the informations to interpret the organ or systemic manifestations (endocrine, or systemic autoimmune chronic inflammatory diseases-ACIDs) observed in trials as well as in registries of cohorts treated with anti-CTLA-4 or anti-PD-1/PD-L1 inhibitors, or combination therapies. Finally the concern raised by cancers occurring in patients with autoimmune diseases (Systemic Lupus Erythematosus, Myositis, Rheumatoid Arthritis, Psoriatic Arthritis, Vasculitis, Scleroderma, Polymyalgia Rheumatica and others) and how to deal with immunotherapy was discussed. The biological knowledges acquired with the immunotherapy trials, have paved to way to better treat autoimmune diseases in patients developing cancer during the autoimmune illness. Immunotherapy without Autoimmunity is the unmet need within our reach in the future.

Significant association between tumor mutational burden and immune-related adverse events during immune checkpoint inhibition therapies.

More than 2000 immuno-oncology agents are being tested or are in use as a result of the cancer immunotherapy revolution. Manipulation of co-inhibitory receptors has achieved tumor eradication in a minority of patients, but widespread immune-related adverse events (irAEs) compromised tolerance to healthy self-tissues in the majority. We have proposed that a major mechanism of irAEs is similar to a graft-versus-malignancy effect of graft-versus-host disease. To verify our hypothesis, we retrieved post-marketing data of adverse events from the U.S. Food and Drug Administration Adverse Event Reporting System. A significant positive correlation was revealed in 7677 patients between the reporting odds ratio of irAEs during immune checkpoint inhibitor therapy and the corresponding tumor mutational burden across 19 cancer types. These results can be interpreted to mean that the ICI drugs unleashed T cells against "altered-self," self, and tumors resulting in better overall survival.

Monogenic systemic lupus erythematosus: insights in pathophysiology.

Systemic lupus erythematosus (SLE) is a complex disease with different genetic, immunologic, and environmental factors contributing to the pathogenesis. Monogenic SLE could help us understand the main phases of immune dysregulation in SLE. The aim of this review is to summarize the current knowledge on monogenic SLE with the implications of the respective genes on disease pathogenesis. A comprehensive literature search on monogenic SLE was conducted utilizing the Cochrane Library and MEDLINE/PubMed databases. The main affected pathways in disease pathogenesis are identified as follows: complement system, apoptosis, nucleic acid degradation, nucleic acid sensing, self-tolerance, and type I interferon production. Further studies on monogenic SLE can make precision medicine possible for SLE by increasing our understanding of disease pathogenesis.

Uveitis induced by programmed cell death protein 1 inhibitor therapy with nivolumab in metastatic melanoma patient.

Nivolumab, a new immune checkpoint inhibitor, binds to programmed cell death-protein 1 receptors on T cell, blockades binding of its ligands, and augments the immunologic reaction against tumor cells. Augmented immune response, however, may lead to immune-related adverse events. Herein we describe a rare case of bilateral anterior uveitis induced by nivolumab treatment for metastatic melanoma. A 54-year-old woman presented with mild conjunctival redness and blurred vision two months after initiating nivolumab treatment. Ophthalmological examination revealed bilateral non-granulomatous anterior uveitis. The flare values in the anterior chamber were monitored as an objective inflammatory index during nivolumab therapy and clinical time course was reported in this paper.

Anti-rods/rings autoantibody generation in hepatitis C patients during interferon-α/ribavirin therapy.

Chronic inflammation associated with hepatitis C virus (HCV) infection can lead to disabling liver diseases with progression to liver cirrhosis and hepatocellular carcinoma. Despite the recent availability of more effective and less toxic therapeutic options, in most parts of the world the standard treatment consists of a weekly injection of pegylated interferon α (IFN-α) together with a daily dose of ribavirin. HCV patients frequently present circulating non-organ-specific autoantibodies demonstrating a variety of staining patterns in the indirect immunofluorescence assay for antinuclear antibodies (ANA). Between 20% to 40% of HCV patients treated with IFN-α and ribavirin develop autoantibodies showing a peculiar ANA pattern characterized as rods and rings (RR) structures. The aim of this article is to review the recent reports regarding RR structures and anti-rods/rings (anti-RR) autoantibody production by HCV patients after IFN-α/ribavirin treatment. Anti-RR autoantibodies first appear around the sixth month of treatment and reach a plateau around the twelfth month. After treatment completion, anti-RR titers decrease/disappear in half the patients and remain steady in the other half. Some studies have observed a higher frequency of anti-RR antibodies in relapsers, i.e., patients in which circulating virus reappears after initially successful therapy. The main target of anti-RR autoantibodies in HCV patients is inosine-5'-monophosphate dehydrogenase 2 (IMPDH2), the rate-limiting enzyme involved in the guanosine triphosphate biosynthesis pathway. Ribavirin is a direct IMPDH2 inhibitor and is able to induce the formation of RR structures in vitro and in vivo. In conclusion, these observations led to the hypothesis that anti-RR autoantibody production is a human model of immunologic tolerance breakdown that allows us to explore the humoral autoimmune response from the beginning of the putative triggering event: exposure to ribavirin and interferon.

Dysregulation of anergy-related factors involved in regulatory T cells defects in Systemic Lupus Erythematosus patients: Rapamycin and Vitamin D efficacy in restoring regulatory T cells.

AIM: Systemic Lupus Erythematosus (SLE) patients display dysfunctions in T cell activation and anergy. Therefore the aims of our study were to explore the expression of anergy-related factors in CD4+ T cells in relationship with regulatory T cells (Tregs) frequency in SLE patients and to identify strategies to redress these defects. METHOD: Casitas B-cell lymphoma b (Cbl-b) and 'gene related to anergy in lymphocytes' (GRAIL) proteins were analyzed in peripheral blood mononuclear cells (PBMCs) from SLE patients and healthy donors (HD) by immunoblotting. cbl-b, grail, growth response factors (egr)2 and egr3 messenger RNAs (mRNAs) were evaluated by real-time polymerase chain reaction in SLE and HD PBMCs and CD4+ T cells. Phenotypic and functional characterization of CD4+ T cells was performed by flow cytometry. Tregs expansion protocol consisted in culturing CD4+ T cells for 14 or 21 days of experimental activation with anti-CD3 and anti-CD28 monoclonal antibodies, human recombinant interleukin (hrIL)-2, in the absence or presence of rapamycin (Rapa) or 1,25-(OH)2D3 (vitamin D: VitD). RESULTS: SLE PBMCs expressed low levels of Cbl-b and GRAIL proteins. Both SLE PBMCs and CD4+ T cells expressed low levels of egr2/3 mRNAs. SLE patients had a reduced number of Tregs with impaired suppressive activity. An association between egr2 mRNA level in CD4+ T cells and Tregs percentage was identified. Experimental activation of CD4+ T cells in the presence of hrIL-2 and Rapa or VitD induced the expansion of SLE Tregs. However, on long-term, only Rapa exposure of SLE CD4+ T cells yielded high numbers of Tregs with sustained suppressive activity. CONCLUSION: Our results suggest a new strategy to correct defects in CD4+ T cell tolerance mechanisms that may prove beneficial in SLE.

In vivo maintenance of human regulatory T cells during CD25 blockade.

Regulatory T cells (Tregs) mediate immune tolerance to self and depend on IL-2 for homeostasis. Treg deficiency, dysfunction, and instability are implicated in the pathogenesis of numerous autoimmune diseases. There is considerable interest in therapeutic modulation of the IL-2 pathway to treat autoimmunity, facilitate transplantation tolerance, or potentiate tumor immunotherapy. Daclizumab is a humanized mAb that binds the IL-2 receptor a subunit (IL-2R a or CD25) and prevents IL-2 binding. In this study, we investigated the effect of daclizumab-mediated CD25 blockade on Treg homeostasis in patients with relapsing-remitting multiple sclerosis. We report that daclizumab therapy caused an ~50% decrease in Tregs over a 52-wk period. Remaining FOXP3+ cells retained a demethylated Treg-specific demethylated region in the FOXP3 promoter, maintained active cell cycling, and had minimal production of IL-2, IFN- g, and IL-17. In the presence of daclizumab, IL-2 serum concentrations increased and IL-2R bg signaling induced STAT5 phosphorylation and sustained FOXP3 expression. Treg declines were not associated with daclizumab-related clinical benefit or cutaneous adverse events. These results demonstrate that Treg phenotype and lineage stability can be maintained in the face of CD25 blockade.

Treg cells in rheumatoid arthritis: an update.

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease arising from a breakdown in immunological self-tolerance, which leads to aberrant immune responses to autoantigens. Regulatory CD4(+) T-cells (Tregs) underpin one of the key mechanisms of self-tolerance and are a major focus of study in RA and other autoimmune diseases. In order to design new and improved therapies to reinstate self-tolerance, and perhaps cure disease, we need to understand the complex mechanism of action of Tregs. This review addresses recent findings in the field of Tregs in RA, with particular focus on identification of potential defects in Treg-mediated self-tolerance mechanisms present in RA patients, as well as how Tregs interact with other cells in the inflamed joints. As antigen-specific Tregs are a potential route for the reinstatement of immune tolerance, we also discuss new strategies currently being investigated which expand or induce de novo generation of Tregs.

The use of glucocorticoids in systemic lupus erythematosus. After 60 years still more an art than science.

Systemic Lupus Erythematosus (SLE) is a clinically diverse, chronic autoimmune disease with inflammation in several organ systems. Its pathogenesis is complex, but includes many factors that can be influenced by glucocorticoids (GCs). Indeed, GCs constitute the corner-stone in SLE-treatment. However, guidelines for GC-treatment of the different disease manifestations are lacking and not every patient responds (sufficiently). The focus of this systematic review is to evaluate the differential glucocorticoid treatment of various SLE manifestations. In addition, some relevant mechanisms of glucocorticoid action as well as resistance are discussed.

A CB1/CB2 receptor agonist, WIN 55,212-2, exerts its therapeutic effect in a viral autoimmune model of multiple sclerosis by restoring self-tolerance to myelin.

Infection of mice with Theiler's murine encephalomyelitis virus (TMEV) leads to the development of TMEV-induced demyelinating disease (TMEV-IDD), an autoimmune, demyelinating and neurodegenerative pathology that serves as a model of multiple sclerosis. Activation of endogenous CB1/CB2 cannabinoid receptors inhibits inflammation and improves the clinical status of TMEV-IDD animals. In the present study, mice with established TMEV-IDD were treated with the CB1/CB2 receptor agonist WIN 55,212-2 (WIN), which restored self-tolerance to a myelin self-antigen while ameliorating the disease in a long-term manner. Accordingly, disruption of self-tolerance with cyclophosphamide provoked chronic relapse. Furthermore, transfer of splenocytes from WIN-treated TMEV-IDD mice to TMEV-infected mice at disease onset prevented the autoimmune inflammatory response and motor impairment. The therapeutic effect of WIN correlated with a decrease in the activation of CD4⁺CD25⁺Foxp3⁻ T cells and an increase in regulatory CD4⁺CD25⁺Foxp3⁺ T cells in the CNS, along with alterations in the cytokine and chemokine milieu. These findings demonstrate for the first time that the suppression of autoimmune responses to myelin antigens underlies the therapeutic effect of CB1/CB2 cannabinoid agonists in the treatment of multiple sclerosis.

Aspirin may do wonders by the induction of immunological self-tolerance against autoimmune atherosclerosis.

Induction of immune tolerance is one of the recent novel immunomodulatory strategies to directly intervene the autoimmune-driven atherosclerosis. Aspirin is a prototypic non-steroidal anti-inflammatory drug, which is now being regarded as a life-saver in variety of atherosclerotic cardiovascular complications. Considerable amount of data emerged during last few years clearly suggests that aspirin can cause immunomodulation by several mechanisms, particularly, its ability to induce tolerogenic dendritic cells (DCs) and to upregulate T regulatory (Treg) cells is especially appealing with respect to induction of immunological self-tolerance. Based on this fact, we hypothesize that aspirin, in addition to its anti-inflammatory effect, may also specifically inhibit autoimmune response in atherosclerosis by actively increasing CD4+CD25+FOXP3+Treg cells as well as by inducing tolerogenic DCs which induce hyporesponsiveness in responder naïve T cells. If proved to be correct, this hypothesis will provide an opportunity to medical community with an already available aspirin-based immunotherapeutic approach for inducing immune tolerance against atherosclerosis.

[Regulatory T-cells: modern approaches to optimization of their numbers].

Regulatory T-cells (Tregs) are important components of the complex adaptive system of the body responsive to environmental challenges. Tregs ensure peripheral tolerance and play an important role in control of inflammatory reactions. Several subsets of Tregs have been described. Naturally occurring CD4+CD25+ Tregs are recognized as a major subset of immune cells responsible for peripheral immune self-tolerance. Another subtype of Tregs is inducible. Such Tregs are generated in the periphery and realize their suppressive potential largely in the form of anti-inflammatory activity. The latter plays an important role in cooperation of three principal anti-inflammatory mechanisms that developed in the course of evolution: macrophages possessed of suppressive activity, Tregs, and stress hormones. Normally, all the three mechanisms of inflammation control are in equilibrium. However, the balance may be disturbed with ageing due to repeated episodes of stress and HPA axis activation. As a result, secretion of stress hormones coupled to antigen overload leads to Treg accumulation. In the course of time activation of the HPA axis is replaced by its inhibition manifested both as a decrease of the baseline cortisol level and a reduction of stress-induced cortisol response. Cortisol present in blood at low concentrations is no longer capable of controlling inflammation and Tregs become a principal mechanism of anti-inflammatory machinery. Superfluous Treg accumulation results in the development of functional somatic syndromes, such as chronic fatigue syndrome, and (in some patients) in the growth of tumours resulting from the suppression of anticancer immunity. On the other hand, the lack of adequate antigen loading in the childhood may delay Treg maturation. Allergy and asthma manifestations may be a consequence of such Treg insufficiency. Thus, both excess and deficiency of Tregs may be at the bottom of morbid conditions. The advances in modern pharmacology open up opportunities for developing new methods to control the Treg level.

Repression of the genome organizer SATB1 in regulatory T cells is required for suppressive function and inhibition of effector differentiation.

Regulatory T cells (T(reg) cells) are essential for self-tolerance and immune homeostasis. Lack of effector T cell (T(eff) cell) function and gain of suppressive activity by T(reg) cells are dependent on the transcriptional program induced by Foxp3. Here we report that repression of SATB1, a genome organizer that regulates chromatin structure and gene expression, was crucial for the phenotype and function of T(reg) cells. Foxp3, acting as a transcriptional repressor, directly suppressed the SATB1 locus and indirectly suppressed it through the induction of microRNAs that bound the SATB1 3' untranslated region. Release of SATB1 from the control of Foxp3 in T(reg) cells caused loss of suppressive function, establishment of transcriptional T(eff) cell programs and induction of T(eff) cell cytokines. Our data support the proposal that inhibition of SATB1-mediated modulation of global chromatin remodeling is pivotal for maintaining T(reg) cell functionality.