Suppression of murine SLE by oral anti-CD3: inducible CD4+CD25-LAP+ regulatory T cells control the expansion of IL-17+ follicular helper T cells

Correlation of the Expression Profile of Peripheral Leukocyte and Liver Tissue Immune Markers With Serum Liver Injury Indices in Children With Biliary Atresia

The aim of the study was to find associations between the levels of liver injury serum markers and the selected liver, peripheral leukocytes, and plasma immune characteristics in biliary atresia (BA) children. Twenty-five newly diagnosed BA children aged 4-30 weeks and 12 age-matched controls were included (for leukocytes characteristics) and 19 BA children and 11 controls (for liver studies). The frequencies of T helper 1 (Th1), Th2, Th17, Th17.1 cells as well as numbers of regulatory T (Treg), B cell subsets, and matrix metalloproteinase -2 and -9 (MMP-2 and MMP-9) expressing leukocytes in the whole blood were evaluated by flow cytometry. Plasma concentrations of tissue inhibitors of metalloproteinase (TIMP)-1, -2, MMP-9, interleukin-17A (IL-17A) and IL-6 were assessed by enzyme-linked immunosorbent assay (ELISA). The leukocyte and liver expression of the retinoic acid receptor-related orphan nuclear receptor gamma (RORγT), fork-head winged helix transcription factor P3 (FoxP3), transforming growth factor beta (TGF-β), interleukin-17A (IL-17A), IL-6, IL-1β, IL-21, interleukin 1 receptor antagonist (IL-1Ra), MMP-2, MMP-9, MMP-12 (liver only), TIMP-1, TIMP-2, T-box transcription factor expressed in T cells, also called TBX21 (T-bet), GATA-binding protein 3 (GATA3), and C-type lectin (CD161) mRNA were determined by real time RT-PCR (reverse-transcription polymerase chain reaction). The BA patients were characterized by increased frequencies of peripheral "suppressor" glycoprotein-A repetitions predominant protein (GARP)+latency-associated peptide (LAP)+Treg and activated Treg cells as well as MMP-2 and MMP-9 bearing lymphocytes, elevated plasma TIMP-1 levels, increased leukocyte expression of MMP-9, TIMP-1, TIMP-2, IL-6, and TGF-β, and decreased leukocyte expression of IL-21 and T-bet, increased liver expression of FoxP3, TIMP-1, and decreased liver expression of IL-1β and MMP-2. The following correlations were found between serum markers of liver injury and leukocyte and liver immune characteristics: (a) hemoglobin (Hb) levels correlated negatively with frequency of peripheral "suppressor" GARP+LAP+ Tregs; (b) aspartate aminotransferase (AST) levels correlated positively with frequency of the peripheral Th17.1 subset and expression of leukocyte FoxP3, (c) gamma glutamyltransferase (GGT) levels correlated positively with the peripheral memory B cells frequencies, the leukocyte IL-6 and TIMP-1 gene expression, (d) alanine aminotransferase (ALT) serum levels correlated positively with the naïve B cell frequency and liver TIMP-2 expression, (e) total bilirubin (Bil) levels correlated positively with the leukocyte MMP-9, the plasma IL-6 levels, and the liver TIMP-2 gene expression, (f) direct Bil levels positively correlated with the liver IL-6 and TIMP-2 expression, (g) international normalized ratio of prothrombin time (PT/INR) concentrations correlated positively with the peripheral Th17.1 subset frequency and the leukocyte MMP-9 but negatively with the liver FoxP3 expression. There were numerous strong positive correlations between the BA liver genes known to be involved in upregulation of IL-17 axis and MMPs/TIMPs expression. No prevailing leukocyte or liver single markers were uniquely associated with serum liver injury indices. BA immune profile is very complex with no single characteristics that would distinguish it from other liver inflammatory diseases.

Distinct functions and transcriptional signatures in orally induced regulatory T cell populations

Oral administration of antigen induces regulatory T cells (Treg) that can not only control local immune responses in the small intestine, but also traffic to the central immune system to deliver systemic suppression. Employing murine models of the inherited bleeding disorder hemophilia, we find that oral antigen administration induces three CD4+ Treg subsets, namely FoxP3+LAP-, FoxP3+LAP+, and FoxP3-LAP+. These T cells act in concert to suppress systemic antibody production induced by therapeutic protein administration. Whilst both FoxP3+LAP+ and FoxP3-LAP+ CD4+ T cells express membrane-bound TGF-β (latency associated peptide, LAP), phenotypic, functional, and single cell transcriptomic analyses reveal distinct characteristics in the two subsets. As judged by an increase in IL-2Rα and TCR signaling, elevated expression of co-inhibitory receptor molecules and upregulation of the TGFβ and IL-10 signaling pathways, FoxP3+LAP+ cells are an activated form of FoxP3+LAP- Treg. Whereas FoxP3-LAP+ cells express low levels of genes involved in TCR signaling or co-stimulation, engagement of the AP-1 complex members Jun/Fos and Atf3 is most prominent, consistent with potent IL-10 production. Single cell transcriptomic analysis further reveals that engagement of the Jun/Fos transcription factors is requisite for mediating TGFβ expression. This can occur via an Il2ra dependent or independent process in FoxP3+LAP+ or FoxP3-LAP+ cells respectively. Surprisingly, both FoxP3+LAP+ and FoxP3-LAP+ cells potently suppress and induce FoxP3 expression in CD4+ conventional T cells. In this process, FoxP3-LAP+ cells may themselves convert to FoxP3+ Treg. We conclude that orally induced suppression is dependent on multiple regulatory cell types with complementary and interconnected roles.

Reduction of Cell Surface T-Cell Receptor by Non-Mitogenic CD3 Antibody to Mitigate Murine Lupus

T-cells are critically involved in the pathogenesis of systemic lupus erythematosus. Although treatment with the anti-CD3 antibody has been reported to be effective in several autoimmune disease animal models including lupus, the immunosuppressive mechanisms remain obscure because of its pleiotropic in vivo kinetics. In this study, a conventional anti-CD3 (2C11C) and a non-mitogenic anti-CD3 with a manipulated Fc region (2C11S) were compared to elucidate the underlying mechanism of action. The efficacy and safety of 2C11S in vivo were demonstrated by sustained TCR reduction for a longer period as compared to 2C11C and no induction of cytokine release or T-cell depletion. Anti-CD3s were administered to NZB/W F1 (BWF1) mice at different time points for individual periods. The short-term treatment with 2C11S in the early phase of lupus suppressed the autoantibody associated with the reduction of germinal center B-cells. Treatment in the late phase attenuated lupus nephritis without affecting autoantibodies or differentiation of effector T-cells. The effect of reduced TCR in the development of autoimmunity was examined by CD3ζ heterozygous-deficient mice, in which T-cells had reduced TCR intensity but showed normal TCR signaling response. Autoantibody and lupus nephritis were attenuated significantly in CD3ζ heterozygous-deficient lupus-prone mice. Collectively, the reduction of surface TCR by non-mitogenic anti-CD3 could sufficiently suppress the development of lupus.

The Emerging Roles of T Helper Cell Subsets and Cytokines in Severe Neutrophilic Asthma

Neutrophilic asthma (NA) is a severe type of steroid resistant asthma, and so far the immune mechanisms underlying NA are not clear. In this article, we performed a comprehensive assessment of Th-cell subsets and cytokines in severe NA patients. A total of 13 healthy individuals and 31 severe asthma patients were enrolled in this study. Refractory asthma patients were defined as those with eosinophilic asthma (EA, accounted for 32% of asthmatic patients) or NA (68%) according to sputum neutrophil/eosinophil counts or blood eosinophils. Th-cell subsets in peripheral blood mononuclear cells (PBMCs) were analyzed by flow cytometry, and cytokines were detected by cytometric bead array (CBA). The results showed significant differences were observed in Th-cell phenotypes, where the number of Th1 cells were reduced and the numbers of Th2 cells were increased in NA and EA groups, respectively, when compared with healthy controls. Th17 cells were not strongly associated with severe neutrophilic asthma. The frequencies of mucosal-associated invariant T (MAIT) cells were strikingly reduced in severe asthma patients, especially in the NA group. This NA group also showed increased levels of IL-17A, IL-17F, TNF-α, and IL-6 in serum and increased levels of IL-17A, IL-17F, IFN-γ, TNF-α, IL-1β, IL-5, IL-6, and IL-8 in sputum. In addition, sputum IL-6 was positively correlated with TNF-α, IFN-γ, IL-17A, and IL-8. Our results uncovered a controversial role for Th17 cells, which were reduced in severe asthma patients. Severe neutrophilic asthma was associated with a striking deficiency of MAIT cells and high pro-inflammatory cytokine levels.

Nasal Administration of Anti-CD3 Monoclonal Antibody (Foralumab) Reduces Lung Inflammation and Blood Inflammatory Biomarkers in Mild to Moderate COVID-19 Patients: A Pilot Study

BACKGROUND

Immune hyperactivity is an important contributing factor to the morbidity and mortality of COVID-19 infection. Nasal administration of anti-CD3 monoclonal antibody downregulates hyperactive immune responses in animal models of autoimmunity through its immunomodulatory properties. We performed a randomized pilot study of fully-human nasal anti-CD3 (Foralumab) in patients with mild to moderate COVID-19 to determine if its immunomodulatory properties had ameliorating effects on disease.

METHODS

Thirty-nine outpatients with mild to moderate COVID-19 were recruited at Santa Casa de Misericordia de Santos in Sao Paulo State, Brazil. Patients were randomized to three cohorts: 1) Control, no Foralumab (n=16); 2) Nasal Foralumab (100ug/day) given for 10 consecutive days with 6 mg dexamethasone given on days 1-3 (n=11); and 3) Nasal Foralumab alone (100ug/day) given for 10 consecutive days (n=12). Patients continued standard of care medication.

RESULTS

We observed reduction of serum IL-6 and C-reactive protein in Foralumab alone vs. untreated or Foralumab/Dexa treated patients. More rapid clearance of lung infiltrates as measured by chest CT was observed in Foralumab and Foralumab/Dexa treated subjects vs. those that did not receive Foralumab. Foralumab treatment was well-tolerated with no severe adverse events.

CONCLUSIONS

This pilot study suggests that nasal Foralumab is well tolerated and may be of benefit in treatment of immune hyperactivity and lung involvement in COVID-19 disease and that further studies are warranted.

γδ T Cell-Secreted XCL1 Mediates Anti-CD3-Induced Oral Tolerance

Oral tolerance is defined as the specific suppression of cellular and/or humoral immune responses to an Ag by prior administration of the Ag through the oral route. Although the investigation of oral tolerance has classically involved Ag feeding, we have found that oral administration of anti-CD3 mAb induced tolerance through regulatory T (Treg) cell generation. However, the mechanisms underlying this effect remain unknown. In this study, we show that conventional but not plasmacytoid dendritic cells (DCs) are required for anti-CD3-induced oral tolerance. Moreover, oral anti-CD3 promotes XCL1 secretion by small intestine lamina propria γδ T cells that, in turn, induces tolerogenic XCR1⁺ DC migration to the mesenteric lymph node, where Treg cells are induced and oral tolerance is established. Consistent with this, TCRδ^-/- mice did not develop oral tolerance upon oral administration of anti-CD3. However, XCL1 was not required for oral tolerance induced by fed Ags, indicating that a different mechanism underlies this effect. Accordingly, oral administration of anti-CD3 enhanced oral tolerance induced by fed MOG_35-55 peptide, resulting in less severe experimental autoimmune encephalomyelitis, which was associated with decreased inflammatory immune cell infiltration in the CNS and increased Treg cells in the spleen. Thus, Treg cell induction by oral anti-CD3 is a consequence of the cross-talk between γδ T cells and tolerogenic DCs in the gut. Furthermore, anti-CD3 may serve as an adjuvant to enhance oral tolerance to fed Ags.

Immunotherapy with oral administration of humanized anti-CD3 monoclonal antibody: a novel gut-immune system-based therapy for metaflammation and NASH

The immune system plays a role in the pathogenesis of non-alcoholic steatohepatitis (NASH) underlying hepatocyte injury and fibrosis progression at all disease stages. Oral administration of anti-CD3 monoclonal antibody (mAb) has been shown in preclinical studies to be an effective method for systemic immune modulation and alleviates immune-mediated disorders without T cell depletion. In the present review, we summarize the concept of the oral administration of humanized anti-CD3 mAb in patients with NASH and discuss the potential of this treatment to address the current requirements of treatments for NASH. Recently published preclinical and clinical data on oral administration of anti CD3 are discussed. Human trials have shown that the oral administration of anti-CD3 in healthy volunteers, patients with chronic hepatitis C virus (HCV) infection and patients with NASH and type 2 diabetes is safe and well tolerated, as well as biologically active. Oral anti-CD3 induces regulatory T cells, suppresses the chronic inflammatory state associated with NASH and exerts a beneficial effect on clinically relevant parameters. Foralumab is a fully human anti-CD3 mAb that has recently been shown to exert a potent anti-inflammatory effect in humanized mice. It is being developed for treatment of NASH and primary biliary cholangitis (PBC). Oral administration of anti CD3 may provide an effective therapy for patients with NASH.

Immunologic Alterations Associated With Oral Delivery of Anti-CD3 (OKT3) Monoclonal Antibodies in Patients With Moderate-to-Severe Ulcerative Colitis

Aim

The aim of this study was to determine the immunologic effects and safety of oral anti-CD3 in patients with ulcerative colitis (UC).

Methods

An open-label pilot study of orally delivered anti-CD3 was performed in patients with moderate-to-severe UC. The primary end points were changes in immunologic parameters and evaluation for safety.

Results

Six subjects received oral OKT3. Biologic effects of oral anti-CD3 included significantly increased proliferation in response to anti-CD3 and anti-inflammatory gene expression profile in peripheral blood mononuclear cells. No serious treatment-related adverse events occurred.

Conclusion

Orally delivered anti-CD3 resulted in immunologic changes in patients with UC.

Immune rebalancing by oral immunotherapy: A novel method for getting the immune system back on track

Immune modulating treatments are often associated with immune suppression or an opposing anti-inflammatory paradigm. As such, there is a risk of exposing patients to infections and malignancies. Contrarily, eliciting only mild immune modulation can be insufficient for alleviating immune-mediated damage. Oral immunotherapy is a novel approach that uses the inherent ability of the gut immune system to generate signals that specifically suppress inflammation at affected sites, without inducing generalized immune suppression. Oral immunotherapy is being developed as a method to rebalance systemic immunity and restore balance, getting it back on track, rather than pushing the immune response too much or too little in opposing directions. Here, I review recent preclinical and clinical data examining the technique and describe its primary advantages.

CD3+CD4+LAP+Foxp3-Regulatory Cells of the Colonic Lamina Propria Limit Disease Extension in Ulcerative Colitis

Background and Aims: In ulcerative colitis (UC), inflammation begins in the rectum and can extend proximally throughout the entire colon. The extension of inflammation is an important determinant of disease course, and may be limited by the action of regulatory T cells (Tregs). In this cross-sectional study, we evaluated the relationship between UC extension and the proportions of CD3+CD4+Foxp3+ and CD3+CD4+LAP+Foxp3-Tregs in the colonic lamina propria (LP) of 79 UC patients and 29 controls. The role of these cells in UC extension was also investigated in the murine oxazolone-induced colitis model.

Methods: Patients: Disease extension was classified according to the Montreal classification. Where possible, endoscopic biopsies of involved and uninvolved tissue were obtained from UC patients. Mouse model: Colitis was induced by intrarectal oxazolone administration. Lamina propria mononuclear cells were isolated from patient biopsies and mouse colon tissue using enzymatic method and the percentage of CD3+CD4+Foxp3+ and CD3+CD4+LAP+Foxp3-cells evaluated by immunofluorescence. Confocal microscopy was applied for the visualization and quantification of CD4+LAP+ cells on tissue histological sections.

Results: In UC patients with distal colitis the proportion of LP CD3+CD4+Foxp3+ Tregs was significantly higher in inflamed tissue than uninvolved tissue. As opposite, the proportion of LP CD3+CD4+LAP+ Tregs was significantly higher in uninvolved tissue than involved tissue. Both LP CD3+CD4+Foxp3+ and LP CD3+CD4+LAP+ Tregs proportion in involved tissue was significantly higher than in controls irrespective of the extension of inflammation. In mice with oxazolone-induced distal colitis, treatment with LAP-depleting antibody was associated with the development of extensive colitis.

Conclusions: Our findings suggest that CD3+CD4+LAP+Foxp3-Tregs limit the extension of inflammatory lesions in UC patients.

Pathways leading to an immunological disease: systemic lupus erythematosus

SLE is a chronic autoimmune disease caused by perturbations of the immune system. The clinical presentation is heterogeneous, largely because of the multiple genetic and environmental factors that contribute to disease initiation and progression. Over the last 60 years, there have been a number of significant leaps in our understanding of the immunological mechanisms driving disease processes. We now know that multiple leucocyte subsets, together with inflammatory cytokines, chemokines and regulatory mediators that are normally involved in host protection from invading pathogens, contribute to the inflammatory events leading to tissue destruction and organ failure. In this broad overview, we discuss the main pathways involved in SLE and highlight new findings. We describe the immunological changes that characterize this form of autoimmunity. The major leucocytes that are essential for disease progression are discussed, together with key mediators that propagate the immune response and drive the inflammatory response in SLE.

Mucosal administration of CD3-specific monoclonal antibody inhibits diabetes in NOD mice and in a preclinical mouse model transgenic for the CD3 epsilon chain

CD3-specific monoclonal antibody (mAb) treats autoimmune disease in animal models and has shown promise in clinical trials of type 1 diabetes. Whereas intravenous administration of CD3-specific mAb acts primarily by transient depletion of activated effector T cells, oral CD3-specific mAb acts primarily by the induction Tregs. We investigated whether oral CD3-specific mAb inhibits disease in non obese diabetic (NOD) mice that spontaneously develop autoimmune diabetes, closely resembling human type 1 diabetes. We found that oral CD3-specific mAb treatment delayed onset and reduced incidence of diabetes in NOD mice, inducing changes in both effector and regulatory T cell compartments. The therapeutic effect was associated with decreased T cell proliferation, decreased IFNγ and IL-17 production, and increased TGF-β and IL-10 production in vitro. In vivo transfer experiments demonstrated that oral CD3-specific mAb decreased diabetogenicity of effector T cells and increased the function of regulatory T cells. Oral OKT3, a monoclonal antibody specific for human CD3 had equivalent effects in transgenic NOD mice expressing the human CD3 epsilon chain which serves as a preclinical model for testing human CD3-specific mAb. These results suggest that oral CD3-specific mAb has the potential for treating autoimmune diabetes in humans.

IL-6 Inhibits Upregulation of Membrane-Bound TGF-β 1 on CD4+ T Cells and Blocking IL-6 Enhances Oral Tolerance

Oral administration of Ag induces regulatory T cells that express latent membrane-bound TGF-β (latency-associated peptide [LAP]) and have been shown to play an important role in the induction of oral tolerance. We developed an in vitro model to study modulation of LAP⁺ on CD4⁺ T cells. The combination of anti-CD3 mAb, anti-CD28 mAb, and recombinant IL-2 induced expression of LAP on naive CD4⁺ T cells, independent of Foxp3 or exogenous TGF-β. In vitro generated CD4⁺LAP⁺Foxp3^- T cells were suppressive in vitro, inhibiting proliferation of naive CD4⁺ T cells and IL-17A secretion by Th17 cells. Assessing the impact of different cytokines and neutralizing Abs against cytokines, we found that LAP induction was decreased in the presence of IL-6 and IL-21, and to a lesser extent by IL-4 and TNF-α. IL-6 abrogated the in vitro induction of CD4⁺LAP⁺ T cells by STAT3-dependent inhibition of Lrrc32 (glycoprotein A repetitions predominant [GARP]), the adapter protein that tethers TGF-β to the membrane. Oral tolerance induction was enhanced in mice lacking expression of IL-6R by CD4⁺ T cells and by treatment of wild-type mice with neutralizing anti-IL-6 mAb. These results suggest that proinflammatory cytokines interfere with oral tolerance induction and that blocking the IL-6 pathway is a potential strategy for enhancing oral tolerance in the setting of autoimmune and inflammatory diseases.

Review article: novel methods for the treatment of non-alcoholic steatohepatitis - targeting the gut immune system to decrease the systemic inflammatory response without immune suppression

BACKGROUND

The systemic immune system plays a role in inflammation and fibrogenesis associated with non-alcoholic steatohepatitis (NASH) and has become a potential target for drug development. In particular, the gut immune system has been suggested as a means for generating signals that can target the systemic immune system.

AIM

To describe seven novel methods being developed for the treatment of NASH that target the gut immune system for alleviation of the systemic inflammatory response, including oral administration of fatty-liver-derived proteins, anti-CD3 antibodies, tumour necrosis factor fusion protein, anti-lipopolysaccharide antibodies, glucosylceramide, delayed-release mercaptopurine, and soy-derived extracts.

METHODS

A search for these methods for oral immunotherapy for NASH was conducted.

RESULTS

Oral administration of these compounds provides an opportunity for immune modulation without immune suppression, with the advantage of being independent of a single molecular/inflammatory pathway. These modes of oral immune therapy demonstrate superior safety profiles, such that the patient is not exposed to general immune suppression. Moreover, these approaches target the whole spectrum of the disease and may serve as adjuvants to other therapies, such that they provide a platform for treatment of concomitant disorders in patients with NASH, including diabetes and hyperlipidaemia. Most of the compounds reviewed are currently in phase II trials, and it is anticipated that the acquisition of more clinical data in the next few years will enable the use of this new class of drugs for the treatment of NASH.

CONCLUSION

Oral immunotherapy may provide a novel platform for the treatment of NASH.

[Changes in proportion and function of peripheral CD4(+)LAP(+) regulatory T cells in children with asthma]

OBJECTIVE

To investigate the changes in the proportion and function of peripheral CD4(+)LAP(+)regulatory T cells (CD4(+)LAP(+)Treg cells) in children with asthma, as well as the role of CD4(+)LAP(+)Treg cells in the pathogenesis of asthma.

METHODS

A total of 75 children who were diagnosed with asthma from March 2014 to September 2015 were enrolled as study subjects, and according to their conditions, they were divided into acute-stage asthma group (40 children) and remission-stage asthma group (35 patients). Another 30 children who underwent physical examination were enrolled as the healthy control group. Flow cytometry was used to determine the percentage of peripheral CD4(+)LAP(+)Treg cells, and [(3)H]-thymidine incorporation assay was performed to analyze the immunosuppression of CD4(+)LAP(+)Treg cells in each group.

RESULTS

The acute-stage asthma group showed significant reductions in the proportion of CD4(+)LAP(+)Treg cells compared with the remission-stage asthma group and the healthy control group (2.0%±1.0% vs 4.1%±2.4%/4.6%±3.0%; P<0.05). The acute-stage asthma group also showed a significant reduction in the immunosuppression rate of CD4(+)LAP(+)Treg cells compared with the remission-stage asthma group and the healthy control group (21%±4% vs 55%±9%/62%±11%; P<0.05).

CONCLUSIONS

In children with asthma, the reduction in the number and inhibitory function of peripheral CD4(+)LAP(+)Treg cells may be involved in the pathogenesis of asthma.

ROCK2 signaling is required to induce a subset of T follicular helper cells through opposing effects on STATs in autoimmune settings

Rho-associated kinase 2 (ROCK2) determines the balance between human T helper 17 (TH17) cells and regulatory T (Treg) cells. We investigated its role in the generation of T follicular helper (TFH) cells, which help to generate antibody-producing B cells under normal and autoimmune conditions. Inhibiting ROCK2 in normal human T cells or peripheral blood mononuclear cells from patients with active systemic lupus erythematosus (SLE) decreased the number and function of TFH cells induced by activation ex vivo. Moreover, inhibition of ROCK2 activity decreased the abundance of the transcriptional regulator Bcl6 (B cell lymphoma 6) and increased that of Blimp1 by reducing the binding of signal transducer and activator of transcription 3 (STAT3) and increasing that of STAT5 to the promoters of the genes Bcl6 and PRDM1, respectively. In the MRL/lpr murine model of SLE, oral administration of the selective ROCK2 inhibitor KD025 resulted in a twofold reduction in the numbers of TFH cells and antibody-producing plasma cells in the spleen, as well as a decrease in the size of splenic germinal centers, which are the sites of interaction between TFH cells and B cells. KD025-treated mice showed a substantial improvement in both histological and clinical scores compared to those of untreated mice and had reduced amounts of Bcl6 and phosphorylated STAT3, as well as increased STAT5 phosphorylation. Together, these data suggest that ROCK2 signaling plays a critical role in controlling the development of TFH cells induced by autoimmune conditions through reciprocal regulation of STAT3 and STAT5 activation.

Therapeutic anti-CD3 monoclonal antibodies: from bench to bedside

The induction of tolerance is a major goal of immunotherapy. Investigations over the last 20 years have shown that anti-CD3 monoclonal antibodies (mAbs) effectively treat autoimmune disease in animal models and have also shown promise in clinical trials. Tolerance induction by anti-CD3 mAbs is related to the induction of Tregs that control pathogenic autoimmune responses. Here, we review preclinical and clinical studies in which intravenous or mucosal administration of anti-CD3 mAbs has been employed and provide an outlook on future developments to enhance the efficacy of this promising therapeutic approach.

IL-10-dependent Tr1 cells attenuate astrocyte activation and ameliorate chronic central nervous system inflammation

See Winger and Zamvil (doi: 10.1093/brain/aww121 ) for a scientific commentary on this article.

The innate immune system plays a central role in the chronic central nervous system inflammation that drives neurological disability in progressive forms of multiple sclerosis, for which there are no effective treatments. The mucosal immune system is a unique tolerogenic organ that provides a physiological approach for the induction of regulatory T cells. Here we report that nasal administration of CD3-specific antibody ameliorates disease in a progressive animal model of multiple sclerosis. This effect is IL-10-dependent and is mediated by the induction of regulatory T cells that share a similar transcriptional profile to Tr1 regulatory cells and that suppress the astrocyte inflammatory transcriptional program. Treatment results in an attenuated inflammatory milieu in the central nervous system, decreased microglia activation, reduced recruitment of peripheral monocytes, stabilization of the blood–brain barrier and less neurodegeneration. These findings suggest a new therapeutic approach for the treatment of progressive forms of multiple sclerosis and potentially other types of chronic central nervous system inflammation.

CD275-Independent IL-17-Producing T Follicular Helper-like Cells in Lymphopenic Autoimmune-Prone Mice

T cells undergo homeostatic expansion and acquire an activated phenotype in lymphopenic microenvironments. Restoration of normal lymphocyte numbers typically re-establishes normal homeostasis, and proinflammatory cytokine production returns to baseline. Mice deficient in guanine nucleotide exchange factor RasGRP1 exhibit dysregulated homeostatic expansion, which manifests as lymphoproliferative disease with autoantibody production. Our previous work revealed that autoreactive B cells lacking RasGRP1 break tolerance early during development, as well as during germinal center responses, suggesting that T cell-independent and T cell-dependent mechanisms are responsible. Examination of whether a particular T cell subset is involved in the breach of B cell tolerance revealed increased Th17 cells in Rasgrp1-deficient mice relative to control mice. Rasgrp1-deficient mice lacking IL-17R had fewer germinal centers, and germinal centers that formed contained fewer autoreactive B cells, suggesting that IL-17 signaling is required for a break in B cell tolerance in germinal centers. Interestingly, a fraction of Th17 cells from Rasgrp1-deficient mice were CXCR5(+) and upregulated levels of CD278 coordinate with their appearance in germinal centers, all attributes of T follicular helper cells (Tfh17). To determine whether CD278-CD275 interactions were required for the development of Tfh17 cells and for autoantibody, Rasgrp1-deficient mice were crossed with CD275-deficient mice. Surprisingly, mice deficient in RasGRP1 and CD275 formed Tfh17 cells and germinal centers and produced similar titers of autoantibodies as mice deficient in only RasGRP1. Therefore, these studies suggest that requirements for Tfh cell development change in lymphopenia-associated autoimmune settings.

Regulatory T cells in atherosclerosis: critical immune regulatory function and therapeutic potential

Atherosclerosis is a chronic inflammatory disease that is mediated by innate and adaptive immune responses. The disease is characterized by sub-endothelial accumulation and modification of lipids in the artery wall triggering an inflammatory reaction which promotes lesion progression and eventual plaque rupture, thrombus formation, and the respective clinical sequelae such as myocardial infarction or stroke. During the past decade, T-cell-mediated immune responses, especially control of pro-inflammatory signals by regulatory T cells (Tregs), have increasingly attracted the interest of experimental and clinical researchers. By suppression of T cell proliferation and secretion of anti-inflammatory cytokines, such as interleukin-10 (IL-10) and transforming growth factor-β, Tregs exert their atheroprotective properties. Atherosclerosis-prone, hyperlipidemic mice harbor systemically less Tregs compared to wild-type mice, suggesting an imbalance of immune cells which affects local and systemic inflammatory and potentially metabolic processes leading to atherogenesis. Restoring or increasing Treg frequency and enhancing their suppressive capacity by various modulations may pose a promising approach for treating inflammatory conditions such as cardiovascular diseases. In this review, we briefly summarize the immunological basics of atherosclerosis and introduce the role and contribution of different subsets of T cells. We then discuss experimental data and current knowledge pertaining to Tregs in atherosclerosis and perspectives on manipulating the adaptive immune system to alleviate atherosclerosis and cardiovascular disease.

Oral immune therapy: targeting the systemic immune system via the gut immune system for the treatment of inflammatory bowel disease

Inflammatory bowel diseases (IBD) are associated with an altered systemic immune response leading to inflammation-mediated damage to the gut and other organs. Oral immune therapy is a method of systemic immune modulation via alteration of the gut immune system. It uses the inherit ability of the innate system of the gut to redirect the systemic innate and adaptive immune responses. Oral immune therapy is an attractive clinical approach to treat autoimmune and inflammatory disorders. It can induce immune modulation without immune suppression, has minimal toxicity and is easily administered. Targeting the systemic immune system via the gut immune system can serve as an attractive novel therapeutic method for IBD. This review summarizes the current data and discusses several examples of oral immune therapeutic methods for using the gut immune system to generate signals to reset systemic immunity as a treatment for IBD.

Inducing and Administering Tregs to Treat Human Disease

Regulatory T cells (Tregs) control unwanted immune responses, including those that mediate tolerance to self as well as to foreign antigens. Their mechanisms of action include direct and indirect effects on effector T cells and important functions in tissue repair and homeostasis. Tregs express a number of cell surface markers and transcriptional factors that have been instrumental in defining their origins and potentially their function. A number of immune therapies, such as rapamycin, IL-2, and anti-T cell antibodies, are able to induce Tregs and are being tested for their efficacy in diverse clinical settings with exciting preliminary results. However, a balance exists with the use of some, such as IL-2, that may have effects on unwanted populations as well as promoting expansion and survival of Tregs requiring careful selection of dose for clinical use. The use of cell surface markers has enabled investigators to isolate and expand ex vivo Tregs more than 500-fold routinely. Clinical trials have begun, administering these expanded Tregs to patients as a means of suppressing autoimmune and alloimmune responses and potentially inducing immune tolerance. Studies in the future are likely to build on these initial technical achievements and use combinations of agents to improve the survival and functional capacity of Tregs.

Intranasal immunization with heat shock protein 60 induces CD4(+) CD25(+) GARP(+) and type 1 regulatory T cells and inhibits early atherosclerosis

Atherosclerosis is an autoimmune inflammatory disease involving both innate and adaptive immune mechanisms. Immune tolerance induction may have therapeutic potential for the suppression of atherosclerosis. Current interest is directed towards mucosal tolerance induction, especially nasal tolerance. Previous studies have shown that heat shock protein 60 (HSP60) is recognized as an important autoantigen in atherosclerosis, and nasal or oral HSP60 can induce tolerance and ameliorate atherosclerosis by inducing several subsets of regulatory T cells (Tregs ) such as latency-associated peptide (LAP)(+) and forkhead box transcription factor 3 (FoxP3)(+) Tregs. However, little is known regarding the detailed mechanisms of nasal tolerance. Here, we again investigated the impact of nasal HSP60 on atherosclerosis and the mechanisms underlying the anti-atherosclerosis responses. We found that nasal HSP60 caused a significant 33·6% reduction in plaque size at the aortic root in the early stages of atherosclerosis (P < 0·001). Notably, a significant increase in activated CD4(+) CD25(+) glycoprotein A repetitions predominant (GARP)(+) Tregs, type 1 Tregs (Tr1 cells), and CD4(+) CD25(+) FoxP3(+) Tregs, as well as a marked decrease in the numbers of type 1 and 17 T helper cells was detected in the spleens and cervical lymph nodes of HSP60-treated mice. Moreover, nasal HSP60 increases the production of transforming growth factor (TGF)-β and interleukin (IL)-10 and decreases the secretion of IFN-γ and IL-17. Interestingly, the atheroprotective role of nasal HSP60 treatment was abrogated partly by the neutralization of IL-10. Our findings show that nasal administration of HSP60 can attenuate atherosclerotic formation by inducing GARP(+) Tregs, Tr1 cells and FoxP3(+) Tregs, and that these Tregs maintain immune homeostasis by secreting IL-10 and TGF-β.

Dysregulated development of IL-17- and IL-21-expressing follicular helper T cells and increased germinal center formation in the absence of RORγt

Interleukin 17-producing helper T (Th17) cells have been widely defined by the lineage transcription factor retinoid-related orphan receptor (ROR)γt. Pathophysiologically, these cells play a crucial role in autoimmune diseases and have been linked to dysregulated germinal center (GC) reactions and autoantibody production. In this study, we used gene expression and flow cytometric analyses for the characterization of Rorγt(-/-) and Rorγt(-/-)Il21(RFP/+) mice to demonstrate a previously unknown transcriptional flexibility in the development of IL-17-producing Th-cell subsets. We found an accumulation of follicular Th (Tfh) cells by 5.2-fold, spontaneous 13-fold higher GC formation, decreased frequency of follicular Foxp3(+) T-regulatory (Treg) cells (50%), and a 3.4-fold increase in the number of proliferating follicular B cells in RORγt-deficient vs. wild-type mice. Dysregulated B-cell responses were associated with enhanced production of IL-17 (6.4-fold), IL-21 (2.2-fold), and B-cell-activating factor (BAFF) (2-fold) and were partially rescued by adoptive transfer of Treg cells. In an unexpected finding, we detected RORγt-independent IL-17 expression in ICOS(+)CXCR5(+)Tfh and in ICOS(+)CXCR5(-)Th cells. Based on the observed high Irf4 and Batf gene expression, we suggest that CD4(+) T-cell transcription factors other than RORγt can cooperatively induce differentiation of IL-17-producing Th cells, including Th17-like Tfh-cell subsets. We conclude that the occurrence of aberrant Tfh and follicular Treg cells support spontaneous GC formation and dysregulated B-cell responses in RORγt-deficient mice.

Oral mixture of autologous colon-extracted proteins for the Crohn’s disease: A double-blind trial

AIM: To evaluate the safety and efficacy of oral administration of Alequel™, an autologous protein-containing colon extract.

METHODS: A total of 43 patients were enrolled in a randomized, placebo-controlled, double-blind trial. Patients were orally administered with autologous protein-containing colon extract three doses of autologous study drug per week for 15 wk, for a total of 45 doses. Patients were followed for safety parameters. Remission was defined as a Crohn’s disease activity index (CDAI) score of less than or equal to 150. All patients were followed for changes in subsets of T cells by fluorescence-activated cell sorting analysis.

RESULTS: Analysis was performed on a total number of evaluable patients of 14 in the study drug group and 15 in the placebo group. Treatment was well tolerated by all patients. No major treatment-related adverse events were reported or observed in any of the treated patients during the feeding or follow-up periods. Between weeks 6 and 9 of the study, six of the 14 (43%) evaluable subjects who received the study drug achieved a CDAI of 150 or lower. In contrast, five of the 15 (33%) evaluable subjects in the placebo group achieved remission. Between weeks 9 and 12, the remission rates were 50% and 33% for the drug group and placebo group, respectively. Among the drug-treated subjects who achieved remission, the effect of the drug was judged as stable in eight of the 14 subjects as measured by at least two CDAI scores indicating remission in the 15-wk treatment period. A decreased percentage of peripheral natural killer T regulatory cells (a decrease of 28% vs an increase of 16%) and an increased ratio of CD4⁺/CD8⁺ T lymphocytes (an increase of 11% vs a decrease of 9%) were noted in subjects with a significant clinical response.

CONCLUSION: Oral administration of the autologous colonic extract could be a safe and effective for the treatment of patients with moderate to severe Crohn’s disease.

Defective circulating CD4+LAP+ regulatory T cells in patients with dilated cardiomyopathy

There has been increasing evidence that chronic immune activation plays critical roles in the pathogenesis of DCM. CD4(+) LAP(+) Tregs are a newly identified T cell subset with suppressive function on the immune response. This study was designed to investigate whether the circulating frequency and function of CD4(+)LAP(+) Tregs would be impaired in patients with DCM. The results demonstrated that DCM patients had a significantly lower frequency of circulating CD4(+)LAP(+) Tregs compared with control donors. CD4(+)LAP(+) Tregs from DCM patients showed compromised function to suppress proliferation of CD4(+) LAP(-)CD25(int/low) T cells and proliferation and IgG production of B cells. Moreover, B cell proliferation and IgG subset production could be directly suppressed by CD4(+) LAP(+) Tregs. TGF-β and contact-dependent mechanisms were involved in CD4(+)LAP(+) Treg-mediated suppression. Correlation analysis suggested that CD4(+)LAP(+) Treg frequency was positively correlated with LVEF and negatively correlated with serum IgG3 and NT-proBNP concentration in patients with DCM. Our results are the first to demonstrate that the frequencies of CD4(+)LAP(+) Tregs in patients with DCM are reduced and that their suppressive function is compromised. Defective CD4(+) LAP(+) Tregs may be an underlying mechanism of immune activation in DCM patients.

A CD3-specific antibody reduces cytokine production and alters phosphoprotein profiles in intestinal tissues from patients with inflammatory bowel disease

BACKGROUND & AIMS

T cells mediate the development of inflammation in inflammatory bowel disease (IBD). We investigated the effects of an antibody against CD3 called otelixizumab, which induces immune tolerance, in intestinal mucosa samples from patients.

METHODS

Intestinal tissues were isolated from patients undergoing routine endoscopy or from patients undergoing intestinal surgery for colon cancer or IBD; healthy surrounding tissues were collected as controls. Isolated lamina propria mononuclear cells (LPMCs) and mucosal tissue explants were incubated with otelixizumab for 24 or 48 hours. Production of inflammatory cytokines was determined by enzyme-linked immunosorbent assay. Levels of 36 cytokines and chemokines and phosphorylation of 39 receptor tyrosine kinases and signaling molecules were measured using protein arrays. Immunoblot analysis was used to analyze T-cell transcription factors.

RESULTS

Incubation of intestinal tissues or LPMCs with otelixizumab reduced production of interferon gamma, interleukin (IL)-17A, and other inflammatory cytokines and chemokines, simultaneously increasing production of IL-10. Mucosal biopsy specimens from patients with IBD retained inflammation-associated tyrosine phosphoprotein profiles ex vivo. Incubation of the inflamed tissue with otelixizumab reduced phosphorylation of these proteins to levels observed in control tissues. Otelixizumab also markedly reduced phosphorylation of proteins associated with T-cell receptor activation. Neutralization of IL-10 blocked the anti-inflammatory effects of otelixizumab.

CONCLUSIONS

We observed anti-inflammatory effects of anti-CD3 in inflamed intestinal tissues from patients with IBD. The antibody appears to down-regulate T-cell activation via IL-10.

Impaired circulating CD4+ LAP+ regulatory T cells in patients with acute coronary syndrome and its mechanistic study

OBJECTIVE

CD4(+) latency-associated peptide (LAP)(+) regulatory T cells (Tregs) are a newly discovered T cell subset in humans and the role of these cells in patients with acute coronary syndrome (ACS) has not been explored. We designed to investigate whether circulating frequency and function of CD4(+)LAP(+) Tregs are defective in ACS.

METHODS

One hundred eleven ACS patients (acute myocardial infarction and unstable angina) and 117 control patients were enrolled in the study. The control patients consisted of chronic stable angina (CSA) and chest pain syndrome (CPS). The frequencies of circulating CD4(+)LAP(+) Tregs and the expression of the transmembrane protein glycoprotein-A repetitions predominant (GARP) on CD4(+) T cells were determined by flow cytometry. The function of CD4(+)LAP(+) Tregs was detected using thymidine uptake. Serum interleukin-10 (IL-10) and transforming growth factor-β protein (TGF-β) levels were detected using ELISA and expression of GARP mRNA in peripheral blood mononuclear cells (PBMCs) was measured by real time-polymerase chain reaction.

RESULTS

We found ACS patients had a significantly lower frequency of circulating CD4(+)LAP(+) Tregs, and the function of these cells was reduced compared to controls. The expression of GARP in CD4(+) T cells and the serum levels of TGF-β in ACS patients were lower than those of control patients. The serum levels of IL-10 were similar between the two cohorts.

CONCLUSIONS

A novel regulatory T cell subset, defined as CD4(+)LAP(+) T cells is defective in ACS patients.

Downregulation of CD4+LAP+ and CD4+CD25+ regulatory T cells in acute coronary syndromes

Background. Regulatory T (Treg) cells play a protective role in atherosclerosis prone models and are related to the onset of acute coronary syndromes (ACS, including non-ST-elevation ACS (NSTEACS) and ST-elevation acute myocardial infarction (STEAMI)). CD4+LAP+ Treg cells are a novel subset of Tregs that have been found to ameliorate atherosclerosis in ApoE^−/− mice, and these cells also exist in humans. The present study was designed to investigate whether CD4+LAP+ Treg cells are involved in the onset of ACS. Methods. The frequencies of CD4+LAP+ and CD4+CD25+ Treg cells were detected using flow cytometric analysis, and the plasma IL-10 and TGF-β1 levels were measured using an ELISA in 29 stable angina (SA) patients, 30 NSTEACS patients, 27 STEAMI patients, and a control group (30 cases). Results. The results revealed a significant decrease in the frequencies of CD4+LAP+ and CD4+CD25+ Treg cells and in the levels of IL-10 and TGF-β1 in patients with ACS compared with those in the SA and control groups. Conclusions. The decrease in the frequencies of CD4+LAP+ and CD4+CD25+ Treg cells may play a role in the onset of ACS.

Combination treatment with anti-CD20 and oral anti-CD3 prevents and reverses autoimmune diabetes

Type 1 diabetes (T1D) is a T cell-mediated autoimmune disease, although B cells also play an important role in T1D development. Both T cell- and B cell-directed immunotherapies have shown efficacy in the prevention and reversal of T1D. However, whether the combined strategy of targeting both T and B cells could further improve therapeutic efficacy remains to be explored. We show that combined treatment with intravenous antihuman CD20 (hCD20) and oral anti-CD3 significantly delays diabetes development in prediabetic hCD20 transgenic NOD mice. More importantly, the combined treatment reverses diabetes in >60% of mice newly diagnosed with diabetes. Further mechanistic studies demonstrated that the addition of oral anti-CD3 to the B-cell depletion therapy synergistically enhances the suppressive function of regulatory T cells. Of note, the oral anti-CD3 treatment induced a fraction of interleukin (IL)-10-producing CD4 T cells in the small intestine through IL-10- and IL-27-producing dendritic cells. Thus, the findings demonstrate that combining anti-CD20 and oral anti-CD3 is superior to anti-CD20 monotherapy for restoring normoglycemia in diabetic NOD mice, providing important preclinical evidence for the optimization of B cell-directed therapy for T1D.

Immune therapy for nonalcoholic steatohepatitis: are we there yet?

Metabolic syndrome, obesity, and nonalcoholic steatohepatitis are associated with a state of chronic inflammation. The immune system and the inflammatory cascade can be involved in the development of any of the above common conditions. This association raises the question of whether immune therapy can be used for the treatment of nonalcoholic steatohepatitis. Although immune therapy is not yet feasible for clinical use, here, we review some of the recent data on the potential role of the various arms of the immune system in the development of nonalcoholic steatohepatitis and several potential therapeutic targets.

An oral CD3-specific antibody suppresses T-cell-induced colitis and alters cytokine responses to T-cell activation in mice

BACKGROUND & AIMS

New therapeutic approaches are needed for inflammatory bowel diseases. A monoclonal antibody against CD3 (anti-CD3) suppresses T-cell-mediated autoimmune diseases such as experimental allergic encephalomyelitis. We explored the effects of anti-CD3 in mice with colitis.

METHODS

Severe combined immunodeficient mice were given injections of CD4(+)CD45RB(high) T cells to induce colitis. Four weeks later, the mice were given 2 or 5 μg/day of anti-CD3 or hamster immunoglobulin (Ig)G (control), via gavage, for 5 or 10 days. The effect of oral anti-CD3 on cytokine responses was studied by activating T cells using intraperitoneal injections of anti-CD3 monoclonal antibody 2 days after oral administration of the antibody. We collected intestine samples for histology analysis and cells were analyzed by flow cytometry. Cytokines in sera were analyzed by cytometric bead array.

RESULTS

Oral administration of anti-CD3 protected the mice from wasting disease and intestinal inflammation. Analyses of spleen and mesenteric lymph node cells showed no differences in total cell counts, or percentages of CD4(+) and forkhead box P3(+) regulatory T cells, between mice given anti-CD3 or the control immunoglobulin. Colitis therefore was not suppressed by induction of forkhead box P3(+) regulatory T cells, or depletion or limited expansion of T cells. Oral administration of anti-CD3 ameliorated the enteropathy induced by intraperitoneal injection of the antibody. In mice with enteropathy, oral anti-CD3 reduced levels of inflammatory cytokines such as interferon-γ, tumor necrosis factor-α, and interleukin (IL)-6; it also increased levels of the anti-inflammatory cytokines IL-10 and transforming growth factor-β. The effects of oral anti-CD3 required IL-10.

CONCLUSIONS

Oral administration of anti-CD3 to mice induces changes in the mucosal immune response that prevent colitis, independent of specific antigen, and reduce T-cell activation in an IL-10-dependent manner. Oral anti-CD3 therefore might be developed for the treatment of patients with inflammatory bowel disease.

CD4+LAP + and CD4 +CD25 +Foxp3 + regulatory T cells induced by nasal oxidized low-density lipoprotein suppress effector T cells response and attenuate atherosclerosis in ApoE-/- mice

Increasing studies have demonstrated that atherosclerosis is a chronic immunoinflammatory disease, and that oxidized low-density lipoprotein (oxLDL)-specific T cells contribute to the autoimmune process in atherosclerosis. Oral administration of oxLDL, which was identified as a candidate autoantigen in atherosclerosis, was shown to induce tolerance and suppress atherogenesis. However, the precise mechanisms of mucosal tolerance induction, in particular nasal tolerance, remain unknown. In this study, we explored the effect of nasal oxLDL on atherosclerosis as well as the cellular and molecular mechanisms leading to atheroprotective responses, and then found that nasal oxLDL drastically ameliorate the initiation (47.6 %, p < 0.001) and progression (21.1 %, p = 0.001) of atherosclerosis. Most importantly, a significant 35.8 % reduction of the progression of atherosclerosis was observed in the enhanced immunization group (p < 0.001). These effects were accompanied by a significant increase in CD4(+) latency-associated peptide (LAP)(+) regulatory T cells (Tregs) and CD4(+)CD25(+)Foxp3(+) Tregs in spleens and cervical lymph nodes, together with increased transforming growth factor (TGF)-β production and suppressed T-helper cells type 1, 2, and 17 immune responses. Surprisingly, neutralization of TGF-β in vivo partially counteracted the protective effect of nasal oxLDL treatment, indicating that the presence of TGF-β was indispensable to CD4(+)LAP(+) Tregs and CD4(+)CD25(+)Foxp3(+) Tregs to acquire regulatory properties. Our studies suggest that CD4(+)LAP(+) Tregs and CD4(+)CD25(+)Foxp3(+) Tregs induced by nasal delivery of oxLDL can inhibit oxLDL-specific T cells response and ameliorate atherosclerosis process.

Regulatory T cells in atherogenesis

Atherosclerosis is believed to be an inflammatory condition of the arterial wall. It has become apparent that various types of cells of innate and adaptive immunity participate in atherogenesis. T cells are of particular interest because they mediate pathogenic immune responses involved in the acceleration of atherosclerosis. Recent studies from several independent groups indicated that subsets of regulatory T cells (Tregs) actively mediate immunologic tolerance and inhibit atherosclerosis development or progression through the down-regulation of effector T-cell responses. It is likely that there is an imbalance between pathogenic effector T cells and Tregs under atherosclerotic conditions. Recent evidence suggests that in addition to the thymus, gut-associated lymphoid tissues are the main sites for the generation of several subsets of peripherally inducible Tregs. This indicates that intervention in the gut environment to promote an endogenous regulatory immune response may serve as a possible therapeutic approach to suppress atherosclerotic diseases. In this review, we discuss not only the possible role of Tregs in the prevention of atherosclerosis, but also promising strategies to prevent or cure atherosclerotic diseases by promoting an endogenous regulatory immune response, particularly by oral immune modulation.

Induction of immunological tolerance by oral anti-CD3

In recent years, our knowledge about immunoregulation and autoimmunity has significantly advanced, but nontoxic and more effective treatments for different inflammatory and autoimmune diseases are still lacking. Oral tolerance is of unique immunologic importance because it is a continuous natural immunologic event driven by exogenous antigen and is an attractive approach for treatment of these conditions. Parenteral administration of anti-CD3 monoclonal antibody is an approved therapy for transplantation in humans and is effective in autoimmune diabetes. Orally administered anti-CD3 monoclonal antibody is biologically active in the gut and suppresses experimental models of autoimmune diseases. Orally delivered antibody does not have side effects including cytokine release syndromes, thus oral anti-CD3 antibody is clinically applicable for chronic therapy. Here we review findings that identify a novel and powerful immunologic approach that is widely applicable for the treatment of human autoimmune conditions.

Tissular T(regs): a unique population of adipose-tissue-resident Foxp3+CD4+ T cells that impacts organismal metabolism

Foxp3+CD4+ regulatory T (T(reg)) cells are a key population in controlling the immune response. Recently, their roles have been expanded to broader, non-immune, contexts, in particular the metabolic consequences downstream of obesity-induced inflammation, e.g. type-2 diabetes and cardiovascular disease. This review highlights the major innate and adaptive immune cell subsets contributing to adipose-tissue inflammation, the key role played by fat-resident T(regs), and the potential of T(reg)-based therapies for treatment of the metabolic syndrome.

Oral administration of different forms of a tolerogenic peptide to define the preparations and doses that delay anti-DNA antibody production and nephritis and prolong survival in SLE-prone mice

Therapeutic agents currently in use to treat systemic lupus erythematosus (SLE) are predominantly immunosuppressive agents with limited specificities. Multiple groups, including ours, have illustrated that inducing tolerance in SLE animal models ameliorates disease symptoms and increases survival. We examined if oral administration of a tolerogenic peptide could affect SLE disease progression. The pConsensus (pCons) peptide, based on protein sequences of anti-double stranded (anti-ds)DNA antibodies, induces tolerance through upregulation of regulatory T cells when administered intravenously. Six different forms of pCons, including multiple antigenic peptides (MAP) and cyclic peptides made up of L- and D-amino acids, at three different concentrations, were fed to BWF1 SLE-susceptible mice for 30 weeks. Mice fed 100 µg of L-MAP or D-MAP had less cumulative proteinuria and serum anti-dsDNA antibody levels than controls. In addition, animals in these groups also survived significantly longer than controls with a corresponding increase in serum transforming growth factor beta (TGFβ, implying a protective role for pCons-induced regulatory T cells. Oral administration of a tolerogenic peptide is a safe, effective method for ameliorating SLE disease manifestations and prolonging survival in SLE-prone mice. Induction of oral tolerance using modified pCons peptides could lead to a novel targeted therapy for human SLE.

Oral tolerance

The gut-associated lymphoid tissue is the largest immune organ in the body and is the primary route by which we are exposed to antigens. Tolerance induction is the default immune pathway in the gut, and the type of tolerance induced relates to the dose of antigen fed: anergy/deletion (high dose) or regulatory T-cell (Treg) induction (low dose). Conditioning of gut dendritic cells (DCs) by gut epithelial cells and the gut flora, which itself has a major influence on gut immunity, induces CD103(+) retinoic acid-dependent DC that induces Tregs. A number of Tregs are induced at mucosal surfaces. Th3 type Tregs are transforming growth factor-β dependent and express latency-associated peptide (LAP) on their surface and were discovered in the context of oral tolerance. Tr1 type Tregs (interleukin-10 dependent) are induced by nasal antigen and forkhead box protein 3(+) iTregs are induced by oral antigen and by oral administration of aryl hydrocarbon receptor ligands. Oral or nasal antigen ameliorates autoimmune and inflammatory diseases in animal models by inducing Tregs. Furthermore, anti-CD3 monoclonal antibody is active at mucosal surfaces and oral or nasal anti-CD3 monoclonal antibody induces LAP(+) Tregs that suppresses animal models (experimental autoimmune encephalitis, type 1 and type 2 diabetes, lupus, arthritis, atherosclerosis) and is being tested in humans. Although there is a large literature on treatment of animal models by mucosal tolerance and some positive results in humans, this approach has yet to be translated to the clinic. The successful translation will require defining responsive patient populations, validating biomarkers to measure immunologic effects, and using combination therapy and immune adjuvants to enhance Treg induction. A major avenue being investigated for the treatment of autoimmunity is the induction of Tregs and mucosal tolerance represents a non-toxic, physiologic approach to reach this goal.

The current concept of T (h) 17 cells and their expanding role in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with a multifaceted range of symptoms affecting almost every organ system. The prototypical pathology of SLE involves the production of antinuclear antibodies and the deposition of immune complexes in basement membranes throughout the body where they induce inflammatory responses. The genetic and environmental etiologies of this process are being intensively sought, and recently, T _H 17 cells have been implicated in the pathogenesis of SLE. T _H 17 cells are CD4+ memory T cells that behave as both helper and effector cell populations functioning through their signature IL-17 cytokines. Their differentiation is distinct to either the T _H 1 or T _H 2 cell lineage, but strongly influences development of adaptive responses, including autoimmunity. This paper details the biological functions and regulation of T _H 17 cells, followed by an update of their expanding role in SLE.

Anti-CD3 antibody ameliorates experimental autoimmune uveitis by inducing both IL-10 and TGF-β dependent regulatory T cells

Chronic/recurrent autoimmune (idiopathic) uveitis is difficult to treat and they account for approximately 10% of legal blindness in the Western world. As it has been reported that anti-CD3 antibody can enhance T cell regulatory function, we investigated its effects in vivo on experimental autoimmune uveitis (EAU), a model for autoimmune uveitis in humans. B10RIII mice immunized with an uveitogenic peptide were treated with the F(ab')(2) fragment of anti-CD3 mAb either before or at clinical disease onset. Evaluation of EAU and cellular responses showed that disease was inhibited and the activation and expansion of pathogenic T cells selectively reduced, whereas functions of Treg in vivo were enhanced. Moreover, mice treated with anti-CD3 mAb were resistant to a second challenge with antigen and thus protected from recurrence of disease. Our results demonstrate that anti-CD3 mAb is a potent inhibitor of autoimmune uveitis.

CD3 mAb treatment ameliorated the severity of the cGVHD-induced lupus nephritis in mice by up-regulation of Foxp3+ regulatory T cells in the target tissue: kidney

Teff/Treg imbalance orchestrated the onset and the progression of the lupus nephritis in a DBA/2→B6D2F1 murine model with cGVHD. In this paper, we first used 145-2C11 Ab to treat these human SLE-like diseased animals. The results showed that short-term low-dose anti-CD3 antibody treatment induced a significant remission of established proteinuria, production of autoantibodies, immune complex deposition and renal parenchyma lesions in lupus nephritic mice. Of note, we found a robust up-regulation of Foxp3 mRNA expression in the target tissue: kidney from mice with anti-CD3 antibody treatment compared to those with control IgG treatment. Likewise, an increased renal mRNA abundance for IL-10 was also observed in anti-CD3 antibody treated mice. In contrast, genes associated with inflammation and fibrosis as well as cytokines related to effector T cell responses were down-regulated by anti-CD3 mAb treatment. These findings suggested that short-term low-dose anti-CD3 antibody treatment might induced an IL-10-secreting Foxp3(+) regulatory T cells in this cGVHD target tissue: kidney, that suppressed the activation of effector T cells (Th1, Th2 and Th17), thus ameliorating the severity of the lupus nephritis in mice.

Mucosal anti-CD3 monoclonal antibody attenuates collagen-induced arthritis that is associated with induction of LAP+ regulatory T cells and is enhanced by administration of an emulsome-based Th2-skewing adjuvant

Mucosal (nasal or oral) administration of anti-CD3 mAb is effective in ameliorating animal models of autoimmunity (experimental autoimmune encephalomyelitis, diabetes, and lupus) by inducing LAP(+) regulatory T cells. We tested this approach in an arthritis model using type II collagen. We found that nasal anti-CD3 was more effective than oral anti-CD3 in attenuating the development of arthritis. Nasal anti-CD3 induced a LAP(+) regulatory T cell that secreted high levels of IL-10 and suppressed collagen-specific T cell proliferation and anti-collagen Ab production. However, neither nasal nor oral anti-CD3 attenuated disease when given to animals with ongoing arthritis, and this was associated with a lack of induction of LAP(+) regulatory T cells. We found, however, that coadministration of a novel emulsome adjuvant, which enhances Th2 responses, resulted in the induction of LAP(+) regulatory T cells and suppression of ongoing arthritis by both nasal and oral anti-CD3. Suppression of arthritis by mucosal anti-CD3 was associated with less joint damage, a decrease of TNF-alpha and IFN-gamma mRNA expression in joints, and a reduction in anti-collagen Abs. These results demonstrate that mucosal anti-CD3 therapy may serve as a therapeutic approach in arthritis and that the biologic effect is enhanced by an emulsome-based adjuvant.

The yin and yang of regulatory T cells and inflammation in RA

Rheumatoid arthritis (RA) is characterized by chronic inflammation leading to joint destruction. Regulatory T (T(REG)) cells are potent suppressors of autoimmunity, but are not capable of controlling every aspect of the inflammatory reaction. We have found that T(REG)-cell function is abnormal in patients with RA, and that a distinct population of T(REG) cells with potent suppressive properties is induced after therapy with inhibitors of tumor necrosis factor. In this Review, we discuss the mutual interactions between the opposing forces of T(REG) cells and inflammation in the context of RA. Therapeutic approaches that enhance T(REG)-cell function whilst controlling inflammation are likely to be the most effective strategies for restoring immune tolerance in patients with this disease.

Induction of regulatory T cells decreases adipose inflammation and alleviates insulin resistance in ob/ob mice

Leptin-deficient ob/ob mice are overweight, develop insulin resistance, and serve as a model for type 2 diabetes (T2D). Studies suggest that inflammatory pathways are linked to the development of insulin resistance and T2D both in animals and humans. We asked whether the induction of regulatory T cells (Tregs) could alleviate the pathological and metabolic abnormalities in ob/ob mice. We induced TGF-beta-dependent CD4(+) latency-associated peptide (LAP)-positive Tregs by oral administration of anti-CD3 antibody plus beta-glucosylceramide. We found a decrease in pancreatic islet cell hyperplasia, fat accumulation in the liver, and inflammation in adipose tissue, accompanied by lower blood glucose and liver enzymes. In addition, treated animals had decreased CD11b(+)F4/80(+) macrophages and TNF-alpha in adipose tissue. Adoptive transfer of orally induced CD4(+)LAP(+) Tregs ameliorated metabolic and cytokine abnormalities. Our results demonstrate the importance of inflammation in T2D and identify a unique immunological approach for treatment of T2D by the induction of Tregs.