Induction Of Treg Cells Research Articles

Helicobacter pylori-derived heat shock protein 60 increases the induction of regulatory T-cells associated with persistent infection

Local Treg responses are involved in Helicobacter pylori-related inflammation and clinical outcomes after infection, and H. pylori-derived HSP60 (HpHSP60) is an important virulence factor associated with gastric carcinogenesis. This study to investigate the role of HpHSP60 in immunosuppression, particularly with regard to whether it could induce the production of Treg cells. For this purpose, human peripheral blood mononuclear cells (PBMCs) were treated with or without HpHSP60 in the presence of an anti-CD3 mAb to determine the effect of HpHSP60 on cell proliferation. In this report, HpHSP60 decreased the expression of CDK4 to significantly arrest the proliferation of mitogen-stimulated T-cells, which correlated with the induction of Treg cells. Moreover, monocytic cells were essential for the induction of HpHSP60-induced Treg cells via the secretion of IL-10 and TGF-β after treatment with HpHSP60. Blockage of HpHSP60 with specific monoclonal antibodies significantly reduced the colonization of H. pylori and the expression of Treg cells in vivo. Overall, our results suggest that HpHSP60 could act on macrophages to trigger the expression of IL-10 and TGF-β, thereby leading to an increase in Treg cells and inhibition of T-cell proliferation.

Comparison of T Helper Cell Patterns in Primary Open-Angle Glaucoma and Normal-Pressure Glaucoma.

BackgroundHSP60-related immunological activities are found in normal-pressure glaucoma (NPG) patients, in whom an elevated intraocular pressure (IOP) found in primary open-angle glaucoma (POAG) is not observed. HSP60 was found in POAG and NPG patients, while anti-HSP60 level was mainly found to be higher in NPG patients. The purpose of this study was to compare the percentages of Th cells and levels of related cytokines, attempting to provide evidence to explain this discrepancy.Material/MethodsBlood samples from POAG, NPG, and normal control (NC) groups were collected and peripheral blood monocytes were isolated and cultured with or without the stimulation of HSP60. Flow cytometry and enzyme-linked immunosorbent assay were used to assess the percentages of Th1, Th2, Th17, and Treg cells, as well as HSP60 antibody levels and related cytokine levels, before and after culture.ResultsSignificantly higher titers of anti-HSP60 were observed only in NPG patients. Comparable Th1 and Th2 cell frequencies, IL-4 level, and IFN-γ level were found in POAG and NPG patients, while higher Treg cell frequency was only found in POAG patients. After culturing with HSP60, increased Th2 frequencies and decreased Th1 frequencies were observed in the POAG, NPG, and NC groups, while increased Treg frequency was only identified in the POAG and NC groups.ConclusionsDifferent Th cell patterns were observed among POAG, NPG, and NC groups. Lack of induction of Treg cells and imbalance of the pro-inflammatory and anti-inflammatory response patterns of Th cells exist in some NPG patients.

FOXP3 O‐GlcNAcylation Controls Regulatory T Cell Homeostasis and Suppressive Function

Regulatory T (Treg) cells are a distinct lineage of T lymphocytes that control immunological self‐tolerance and homeostasis. The use of Treg cells for immunotherapy has been challenging, partially because of the functional heterogeneity and instability of Treg cells. The transcription factor FOXP3 is crucial for Treg lineage specification during development and is continuously required for the suppressive function of mature Treg cells. FOXP3 can be regulated by various post‐translational modifications, which enable transient regulation of FOXP3 functionality in response to environmental cues. Here, we investigate the novel O‐linked N‐Acetylglucosamine (O‐GlcNAc) modification on FOXP3 in Treg cell function and stability.Protein O‐GlcNAcylation is enriched in induced Treg cells, compared to naïve T cells. Chemical augmentation of O‐GlcNAcylation promotes the induction of Treg cell signature genes. O‐GlcNAcylation, controlled by O‐GlcNAc cycling enzymes O‐GlcNAc transferase (OGT) and O‐GlcNAcase (OGA), modifies and stabilizes FOXP3 by counteracting with ubiquitination. Treg cell‐specific OGT deletion in mice does not affect Treg cell lineage specification, but results in fewer suppressive effector Treg cells and the development of an aggressive autoimmune syndrome. O‐GlcNAc‐deficient Treg cells show reduced FOXP3 protein expression and increased effector T‐cell signatures. In summary, we demonstrate that protein O‐GlcNAcylation, by modulating FOXP3, is indispensable for Treg cell suppressive function and lineage stability. Manipulating O‐GlcNAc levels may represent a novel approach to translate Treg cell immunotherapy into clinical practice.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Role of tryptophan catabolism in pediatric allergic diseases

With the change of environment and life-style, the incidence of allergic diseases in children is increasing, but its pathogenesis is not entirely elucidated.It is shown that tryptophan catabolism mediated by indoleamine 2, 3-dioxygenase plays a significant role in the pathophysiology of allergic diseases of children such as asthma and allergic rhinitis.These roles include inducing Treg cell, inhibiting Th2 cell response, mediating immune tolerance and so forth.Therefore, it is a new target for the prevention and treatment of allergic diseases by stimulating the immune cells and changing the diet structure to regulate tryptophan catabolism.This article reviews the role of tryptophan decomposition in children allergic diseases. Key words: Tryptophan metabolism; Allergic diseases

Vaccine-induced antigen-specific regulatory T cells attenuate the antiviral immunity against acute influenza virus infection.

Peptide-based T cell vaccines targeting the conserved epitopes of influenza virus can provide cross-protection against distantly related strains, but they are generally not immunogenic. Foreign antigen-specific regulatory T (Treg) cells are induced under subimmunogenic conditions peripherally, although their development and role in vaccine-mediated antiviral immunity is unclear. Here, we demonstrated primary vaccination with peptides alone significantly induced antigen-specific Foxp3+ Treg cells, which were further expanded by repeated vaccination with unadjuvanted peptides. Certain adjuvants, including CpG, suppressed the induction and expansion of antigen-specific Treg cells by peptide vaccination. Interestingly, secondary influenza virus infection significantly increased the frequency of preexisting antigen-specific Treg cells, although primary infection barely induced them. Importantly, specific depletion of vaccine-induced antigen-specific Treg cells promoted influenza viral clearance, indicating their inhibitory role in vivo. Immunization with CpG-adjuvanted peptides by the subcutaneous prime-intranasal-boost strategy restricted the recruitment and accumulation of antigen-specific Treg cells in lung, and stimulated robust T cell immunity. Finally, subcutaneous prime-intranasal-boost immunization with CpG-adjuvanted peptides or whole-inactivated influenza vaccines protected mice from heterosubtypic influenza virus infection. In conclusion, antigen-specific Treg cells induced by peptide vaccines attenuate the antiviral immunity against influenza virus infection. CpG-adjuvanted peptide vaccines provide heterosubtypic influenza protection probably by inhibiting Treg development and enhancing T cell immunity.

Celastrol mediates Th17 and Treg cell generation via metabolic signaling

A T helper 17 (Th17) cell/regulatory T (Treg) cell imbalance is involved in many immune disorders and diseases. Celastrol, a Chinese herbal compound that has anti-inflammatory and immunosuppressive properties, has been indicated to suppress T cell proliferation and Th17 cell induction, while facilitating Forkhead box P3 (Foxp3) expression and Treg cell generation. In this study, we explored the impact and mechanism of celastrol on Th17 cell/induced Treg (iTreg) cell induction. CD4+CD25− T cells were purified, stimulated with anti-CD3 and anti-CD28 antibodies, and polarized in vitro to generate Th17 or iTreg cells in the presence or absence of celastrol. Initially, we determined that Interleukin (IL)-17 expression by celastrol-treated Th17 was significantly decreased compared with untreated cells; however, the frequency of Foxp3+ cells was increased in celastrol-treated cells. We verified that celastrol inhibited phospho-STAT3 expression in cultured Th17 cells and up-regulated phospho-STAT5 expression in iTreg cells. Furthermore, T cells treated with celastrol were more likely to participate in FAO metabolism instead of glycolysis. Celastrol suppressed the expression of glucose transporter, Glut1, and the rate-limiting enzyme, HK2, in addition to mTOR, HIF-1α, c-Myc and Akt expression in Th17 cells. Conversely, celastrol promoted FAO of lipids by up-regulating CPT1A and AMPKα expression in iTreg cells. Our results suggest that celastrol suppresses Th17 cell induction, while promoting the generation of iTreg cells. We found that celastrol inhibits glycolysis in Th17 cells and promotes FAO by iTreg cells, suggesting that celastrol could mediate the metabolism of Th17 and iTreg cells.

Importance of B cells to development of regulatory T cells and prolongation of tissue allograft survival in recipients receiving autologous bone marrow transplantation.

We previously showed that congenic bone marrow transplantation (BMTx) post myeloablation augmented tissue allograft survival in association with increased regulatory T (Treg) cells of both host and bone marrow donor origin. Regulatory B (Breg) cells can also modulate T-cell immunity and B cells may be implicated in the development of Treg cells. Accordingly, we explored the effect of B-cell depletion invivo on augmented graft survival post BMTx. C57BL/6 mice received BALB/c skin allografts followed 7days later by myeloablation using cyclophosphamide and busulphan. Mice then received T-cell-depleted bone marrow from CD45.1 congenic donors, and ongoing immunosuppression with rapamycin (to day 28 after BMTx). Control mice received cyclophosphamide and busulphan followed by rapamycin, but not congenic bone marrow. At different times post BMTx, mice received B-cell-depleting antibody treatment, and the effect on both skin graft survival, and induction of Treg cells was assessed. BMTx resulted in significantly prolonged skin graft survival versus control mice, in association with attenuated donor-specific alloreactivity relative to controls, increased splenic Treg cells and significantly diminished anti-donor IgG. In mice receiving infusion of B-depleting antibodies for 12days from day 15 post BMTx, both graft survival and Treg cell activity were diminished, particularly for functional Treg cells of donor origin. Adoptive transfer of Breg cells from mice harvested at 15days post BMTx prolonged survival in naive transplanted mice and increased Treg cell levels. Thus, autologous BMTx augmentation of graft survival is dependent in part upon a population of Breg cells that can modulate the function of donor-derived Treg cells.

Norisoboldine, a natural AhR agonist, promotes Treg differentiation and attenuates colitis via targeting glycolysis and subsequent NAD+/SIRT1/SUV39H1/H3K9me3 signaling pathway

Norisoboldine (NOR), a natural aryl hydrocarbon receptor (AhR) agonist, has been demonstrated to attenuate ulcerative colitis (UC) and induce the generation of Treg cells. Under UC condition, hypoxia widely exists in colonic mucosa, and secondary changes of microRNAs (miRs) expressions and glycolysis contribute to Treg differentiation. At present, we worked for exploring the deep mechanisms for NOR-promoted Treg differentiation in hypoxia and its subsequent anti-UC action from the angle of AhR/miR or AhR/glycolysis axis. Results showed that NOR promoted Treg differentiation in hypoxia and the effect was stronger relative to normoxia. It activated AhR in CD4+ T cells under hypoxic microenvironment; CH223191 (a specific AhR antagonist) and siAhR-3 abolished NOR-promoted Treg differentiation. Furthermore, the progress of glycolysis, levels of Glut1 and HK2, and expression of miR-31 rather than miR-219 and miR-490 in CD4+ T cells were downregulated by NOR treatment under hypoxic microenvironment. However, HK2 plasmid but not miR-31 mimic significantly interfered NOR-enhanced Treg polarization. In addition, NOR reduced NAD+ and SIRT1 levels, facilitated the ubiquitin-proteasomal degradation of SUV39H1 protein, and inhibited the enrichment of H3K9me3 at −1, 201 to −1,500 region of Foxp3 promoter in CD4+ T cells under hypoxic microenvironment, which was weakened by HK2 plasmid, CH223191, and siAhR-3. Finally, the correlation between NOR-mediated activation of AhR, repression of glycolysis, regulation of NAD+/SIRT1/SUV39H1/H3K9me3 signals, induction of Treg cells, and remission of colitis was confirmed in mice with DSS-induced colitis by using CH223191 and HK2 plasmid. In conclusion, NOR promoted Treg differentiation and then alleviated the development of colitis by regulating AhR/glycolysis axis and subsequent NAD+/SIRT1/SUV39H1/H3K9me3 signaling pathway.

P21-activated kinase 2 is essential in maintenance of peripheral Foxp3+ regulatory T cells.

SummaryThe p21‐activated kinase 2 (Pak2), an effector molecule of the Rho family GTPases Rac and Cdc42, regulates diverse functions of T cells. Previously, we showed that Pak2 is required for development and maturation of T cells in the thymus, including thymus‐derived regulatory T (Treg) cells. However, whether Pak2 is required for the functions of various subsets of peripheral T cells, such as naive CD4 and helper T‐cell subsets including Foxp3+ Treg cells, is unknown. To determine the role of Pak2 in CD4 T cells in the periphery, we generated inducible Pak2 knockout (KO) mice, in which Pak2 was deleted in CD4 T cells acutely by administration of tamoxifen. Temporal deletion of Pak2 greatly reduced the number of Foxp3+ Treg cells, while minimally affecting the homeostasis of naive CD4 T cells. Pak2 was required for proliferation and Foxp3 expression of Foxp3+ Treg cells upon T‐cell receptor and interleukin‐2 stimulation, differentiation of in vitro induced Treg cells, and activation of naive CD4 T cells. Together, Pak2 is essential in maintaining the peripheral Treg cell pool by providing proliferation and maintenance signals to Foxp3+ Treg cells.

Using marker gene analysis instead of mixed lymphocyte reaction assay for identification of functional CD4+FOXP3+ regulatory T cells.

To establish a quick analytical method using quantitative PCR for marker gene analysis to identify the functions of iTreg cells and subsequently curtail the harvest time for iTreg cells. The data from the marker gene analysis indicated that varying proportions of iTreg cells could reveal the various expression levels of these genes. FoxP3 expression increased to a considerable degree. By using the same iTreg population, the mixed lymphocyte reaction assay was conducted for 5days. The suppression percentage of T-cells was dependent on the proportion of iTreg cells, indicating that gene expression levels can represent the biological functions of iTreg cells. By using human peripheral blood mononuclear cells for Treg cell induction, the marker gene expression analysis showed a difference between iTreg cells and uninduced T cells. Marker gene analysis requires only 1day to identify the functions of human iTreg cells can save time in clinical application and might prevent graft-versus-host disease occurrence effectively.

Circulating exosomes suppress the induction of regulatory T cells via let-7i in multiple sclerosis

Multiple sclerosis (MS) is a T cell-mediated autoimmune disease of the central nervous system. Foxp3+ regulatory T (Treg) cells are reduced in frequency and dysfunctional in patients with MS, but the underlying mechanisms of this deficiency are unclear. Here, we show that induction of human IFN-γ−IL-17A−Foxp3+CD4+ T cells is inhibited in the presence of circulating exosomes from patients with MS. The exosomal miRNA profile of patients with MS differs from that of healthy controls, and let-7i, which is markedly increased in patients with MS, suppresses induction of Treg cells by targeting insulin like growth factor 1 receptor (IGF1R) and transforming growth factor beta receptor 1 (TGFBR1). Consistently, the expression of IGF1R and TGFBR1 on circulating naive CD4+ T cells is reduced in patients with MS. Thus, our study shows that exosomal let-7i regulates MS pathogenesis by blocking the IGF1R/TGFBR1 pathway.

The level of myeloid-derived suppressor cells positively correlates with regulatory T cells in the blood of children with transient hypogammaglobulinaemia of infancy.

IntroductionTransient hypogammaglobulinaemia of infancy (THI) is a primary immunodeficiency characterised by low levels of immunoglobulin G (often with concomitant decrease of IgA and sometimes also of IgM) with still unknown exact reason. A delayed normalisation of the immunoglobulin level in THI may be associated with a transiently elevated number of regulatory T cells (Treg). Although in cancer and chronic inflammation it was shown that the level of Treg cells can be increased by myeloid-derived suppressor cells (MDSCs), until now no studies have been performed in the context of the role of MDSCs in THI and their correlation with Treg cells. Consequently, we aimed to determine the occurrence of MDSCs in the peripheral blood of children with THI and correlate their level with the level of Treg cells.Material and methodsFlow cytometry analyses of Mo-MDSCs and Gr-MDSCs, characterised as HLA-DR–CD11b+CD15–CD14+ and HLA-DR–CD11b+CD15+CD14–, respectively, and Treg (CD4+CD25+Foxp3+) cells were performed.ResultsThe proportion of Mo-MDSCs and Gr-MDSCs was significantly higher in the group of THI patients with elevated level of Treg cells (from the 95% confidence interval level of healthy controls). The cells with Mo-MDSC and Gr-MDSC characteristics positively correlated with the level of Treg cells. Moreover, children with a higher proportion of circulating Treg cells, and thereby higher level of MDSCs, showed delayed normalisation of IgG level and recovery.ConclusionsThese findings show for the first time that MDSCs may be involved in the pathomechanism of THI, probably acting through the induction of Treg cells.

Cellular Components and Mechanisms of Oral Tolerance Induction.

Oral tolerance can be defined as an inhibition of specific immune responsiveness to subsequent parenteral injections of proteins to which an individual or animal has been previously exposed via the oral route. Multiple mechanisms of tolerance are induced by oral-fed antigens, but induction of regulatory CD4 T-cells expressing the transcription factor Foxp3 and the membrane-bound TGF-β stands out as the major players in oral tolerance. Oral antigen administration suppresses several animal models of autoimmune disease, including experimental autoimmune encephalomyelitis, uveitis, thyroiditis, myasthenia, arthritis, and diabetes, but also nonautoimmune inflammatory conditions such as asthma, atherosclerosis, graft rejection, allergy, and stroke. However, human trials have produced mixed results, and a great deal remains to be learned about the mechanisms of oral tolerance before it can be successfully applied to people. In this review, we highlight the cellular components involved in oral tolerance induction. A deep knowledge of these intricate cell interactions will pave the way for a successful application of antigen tolerance to treat autoimmune and nonautoimmune inflammatory diseases.

Therapeutic administration of bone marrow-derived mesenchymal stromal cells reduces airway inflammation without up-regulating Tregs in experimental asthma.

Prophylactic administration of mesenchymal stromal cells (MSCs) derived from adipose (AD-MSC) and bone marrow tissue (BM-MSC) in ovalbumin-induced asthma hinders inflammation in a Treg-dependent manner. It is uncertain whether MSCs act through Tregs when inflammation is already established in asthma induced by a clinically relevant allergen. Evaluate the effect of therapeutic administration of MSCs on inflammation and Treg cells in house dust mite (HDM)-induced asthma. BM-MSCs and AD-MSCs were administered intratracheally to C57BL/6 mice 1 day after the last HDM challenge. Lung function, remodelling and parenchymal inflammation were assayed 3 or 7 days after MSCs treatment, through invasive plethysmography and histology, respectively. Bronchoalveolar lavage fluid (BALF) and mediastinal lymph nodes (mLNs) were assessed regarding the inflammatory profile by flow cytometry, ELISA and qRT-PCR. MSCs were studied regarding their potential to induce Treg cells from primed and unprimed lymphocytes in vitro. BM-MSCs, but not AD-MSCs, reduced lung influx of eosinophils and B cells and increased IL-10 levels in HDM-challenged mice. Neither BM-MSCs nor AD-MSCs reduced lung parenchymal inflammation, airway hyperresponsiveness or mucus hypersecretion. BM-MSCs and AD-MSCs did not up-regulate Treg cell counts within the airways and mLNs, but BM-MSCs decreased the pro-inflammatory profile of alveolar macrophages. Co-culture of BM-MSCs and AD-MSCs with allergen-stimulated lymphocytes reduced Treg cell counts in a cell-to-cell contact-independent manner, although co-culture of both MSCs with unprimed lymphocytes up-regulated Treg cell counts. MSCs therapeutically administered exert anti-inflammatory effects in the airway of HDM-challenged mice, but do not ameliorate lung function or remodelling. Although MSC pre-treatment can increase Treg cell numbers, it is highly unlikely that the MSCs will induce Treg cell expansion when lymphocytes are allergenically primed in an established lung inflammation.

Vitamin C Stabilizes Foxp3 Expression in Induced Treg Cells By Targeted DNA Demethylation and Prevents Murine Model of Acute Graft Versus Host Disease

Antigen-specific regulatory T cells (Tregs) possess the potential to reduce excess of immune responses following allogeneic hematopoietic stem cell transplantation. Although antigen-specific in vitro- expanded Tregs (iTregs) have long been considered as a promising therapeutic agent against allo-immune reactions such as graft versus host disease (GVHD), accumulating evidences have suggested that iTregs easily lose their characteristics with quick cessation of Foxp3 expression , a lineage specifying transcription factor of Tregs, compared with in vivo -generated natural Tregs (nTregs). It has been revealed that insufficient demethylation of the CpG islands in conserved noncoding sequence 2 (CNS2) region of the Foxp3 locus mainly explains such instability of Foxp3 expression in iTregs.In order to overcome this drawback, we investigated the optimum way to generate stable iTregs for the prevention of a murine model of acute GVHD. We created a major-MHC mismatched GVHD model by transferring CD45.1 (H-2Kb) bone marrow (BM) cells together with effector T cells (CD4+25- and CD8 cells) into lethally irradiated (8Gy/body) 8-12-week old BALB/C (H-2Kd) recipients. In this model, recipient mice usually die within 7-10 days after bone marrow transplant (BMT) due to severe acute GVHD. Alloantigen-specific iTregs were generated by co-culturing naive T cells from human CD2 Foxp3 reporter mice (C57BL6/J background, H-2Kb) with BALB/C-derived antigen presenting cells in the presence of TGF-β, IL-2 and retinoic acid. Alloantigen-specific iTregs were then harvested 6-7 days after co-culture, by FACS-sorting the CD4+Foxp3+ population. Subsequently, sorted iTregs (106 cells) were transferred intravenously together with effector T cells (106 cells) and BM cells into recipients. We tested a panel of pharmacological agents and gene transduction during co-culture for their effects on iTreg stability, with FACS-based evaluation on day 7 after BMT. Among a panel of agents and gene modification tested, we found that only vitamin C-treated iTregs effectively improved Foxp3 maintenance compared with untreated iTregs (90%, vitamin C-treated iTregs vs 40%, untreated iTregs) in the GVHD model mice. As reported, vitamin C facilitated DNA demethylation of the Foxp3 CNS2 in iTregs in a Tet DNA demethylase-dependent manner. Bisulfite sequencing revealed a significant acceleration of CpG demethylation at the Foxp3 CNS2 by vitamin C, and the extent of demethylation achieved with vitamin C treatment reached to an equivalent level to those seen in nTregs. Furthermore, vitamin C mediated demethylation was extended to other Treg cell-specific regulatory lesions such as Tnfrsf18, Ikzf4, Ctla4 . On the other hand, untreated iTregs remain methylated at these loci to the same degree as naïve T cells (p<0.05) . At the same time, interestingly, production of inflammatory cytokines such as IFNγ and IL-21 that was observed in untreated iTregs which lost Foxp3 expression (ex- Foxp3 iTreg) was not observed in vitamin C-treated counterparts. Additionally, we further evaluated the benefits of vitamin C treatment, by investigating effects of another well-known demethylating agent, 5-aza-2'-deoxytidine (5-aza-dC). As a result, 5-aza-dC did not only induce DNA demethylation of Foxp3 CNS2, but also of the CNS1 enhancer region of the inflammatory cytokine IFNγ locus, even in iTreg conditioning culture. This nonspecific demethylation was not observed in vitamin C-treated iTregs (p<0.01). Finally , adoptive transfer of vitamin C-treated iTregs ameliorated GVHD in mice. Vitamin C-treated iTreg prolonged survival at BMT day 45 compared with untreated iTreg (100%, N=8, vitamin C treated iTreg group, vs 44.4%, untreated iTreg group, N=9, p<0.01). Amelioration of acute GVHD by vitamin C-treated iTreg was also confirmed by colon length on day 7 after BMT (p<0.05) and pathological findings of colon and small intestine.In summary, vitamin C stabilized Foxp3 expression with specific demethylation of Foxp3 CNS2 as well as Treg-associated genes in antigen-specific iTregs, preventing them from conversion into inflammatory ex- Foxp3 iTregs, thus ameliorating the pathogenesis of a murine model of GVHD. Our findings strongly suggest the potential of clinical application of Treg therapy combined with vitamin C treatment, for GVHD and autoimmune diseases. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

The role of regulatory B cells in allergen immunotherapy.

Allergen immunotherapy (AIT) is currently the only curative treatment available for allergic diseases, and has been used in clinical practice for over a century. Induction and maintenance of immune tolerance to nonhazardous environmental and self-antigens is essential to maintain homeostasis and prevent chronic inflammation. Regulatory B (BREG) cells are immunoregulatory cells that protect against chronic inflammatory responses primarily through production of anti-inflammatory cytokines such as IL-10, transforming growth factor-β, and IL-35. The importance of BREG cells has been extensively demonstrated in the context of autoimmune diseases. Data showing their role in the regulation of allergic responses are slowly accumulating. This review summarizes recent findings relevant to the topic of BREG cells and their potential role in AIT. BREG cells support AIT in models of allergic airway inflammation and intestinal inflammation through induction of regulatory T (TREG) cells. In humans BREG frequency increases during venom immunotherapy while the phenotype of allergen-specific B cells changes. Mechanisms of BREG-mediated tolerance to allergens include IL-10-mediated suppression of effector T cell, including TH2 responses, induction of TREG cells, IL-10-mediated inhibition of Dendritic cell maturation, modulation of T follicular helper responses, and production of anti-inflammatory IgG4 antibodies. Current evidence supports a potential role for BREG cells in induction and maintenance of allergen tolerance during AIT. A better understanding of the role of B cells and BREG cells in AIT could open potential new windows for developing targeted therapies specifically focused on promoting BREG responses during AIT.

The regulation of regulation: interleukin-10 increases CD4+ CD25+ regulatory T cells but impairs their immunosuppressive activity in murine models with schistosomiasis japonica or asthma.

CD4+ CD25+ Foxp3+ regulatory T (Treg) cells play an important role in maintaining immune homeostasis. Interleukin-10 (IL-10), a cytokine with anti-inflammatory capacities, also has a critical role in controlling immune responses. In addition, it is well known that production of IL-10 is one of the suppression mechanisms of Treg cells. However, the action of IL-10 on Treg cells themselves remains insufficiently understood. In this study, by using a Schistosoma japonicum-infected murine model, we show that the elevated IL-10 contributed to Treg cell induction but impaired their immunosuppressive function. Our investigations further suggest that this may relate to the up-regulation of serum transforming growth factor (TGF-β) level but the decrease in membrane-bound TGF-β of Treg cells by IL-10 during S. japonicum infection. In addition, similar IL-10-mediated regulation on Treg cells was also confirmed in the murine model of asthma. In general, our findings identify a previously unrecognized opposing regulation of IL-10 on Treg cells and provide a deep insight into the precise regulation in immune responses.

Dermatophagoides pteronyssinus immunotherapy changes the T-regulatory cell activity

Subcutaneous specific immunotherapy (SCIT) has been shown to modify the Dermatophagoides pteronissinus (DP) allergic response, characterized by generation of Treg cells. However, studies have reported no changes in the proportion of Treg cells after immunotherapy, indicating that the effects may be due to modifications in their regulatory activities. We aimed to determine whether Tregs generated by DP-SCIT can switch the allergic response to tolerant and study the involvement of suppressive cytokines on it. Twenty-four DP-allergic rhinitis patients were recruited, 16 treated with DP-SCIT and 8 untreated. Treg and T effector cells were isolated before and after DP-SCIT, and cocultured in different combinations with α-IL-10, α-TGF-β blocking antibodies and nDer p 1. Treg cells after DP-SCIT increased Th1 and decreased Th2 and Th9 proliferation. Similarly, they increased IL-10 and decreased IL-4 and IL-9-producing cells. α-IL-10 affected the activity of Treg cells obtained after DP-SCIT only. Finally, DP-specific IgG4 levels, Treg percentage and IL-10 production were correlated after DP-SCIT. These results demonstrate that DP-SCIT induces Treg cells with different suppressive activities. These changes could be mediated by IL-10 production and appear to play an important role in the induction of the tolerance response leading to a clinical improvement of symptoms.

Casein kinase 2 is a critical determinant of the balance of Th17 and Treg cell differentiation

Th17 cells promote inflammatory reactions, whereas regulatory T (Treg) cells inhibit them. Thus, the Th17/Treg cell balance is critically important in inflammatory diseases. However, the molecular mechanisms underlying this balance are unclear. Here, we demonstrate that casein kinase 2 (CK2) is a critical determinant of the Th17/Treg cell balance. Both the inhibition of CK2 with a specific pharmacological inhibitor, CX-4945, and its small hairpin RNA (shRNA)-mediated knockdown suppressed Th17 cell differentiation but reciprocally induced Treg cell differentiation in vitro. Moreover, CX-4945 ameliorated the symptoms of experimental autoimmune encephalomyelitis and reduced Th17 cell infiltration into the central nervous system. Mechanistically, CX-4945 inhibited the IL-6/STAT3 and Akt/mTOR signaling pathways. Thus, CK2 has a crucial role in regulating the Th17/Treg balance.

Hydrolysed ovalbumin offers more effective preventive and therapeutic protection against egg allergy than the intact protein.

The application of specific immunotherapy to stimulate oral tolerance towards food allergens is hampered by the high frequency of adverse side-effects and the excessive duration of the treatments. In this work, a hydrolysate of ovalbumin with pepsin (OP), selected for its low IgE reactivity and Th2-stimulating capacity, was assayed for its ability to prevent and treat allergy to egg white (EW). As a first step, the safety of OP, in terms of the absence of sensitizing and eliciting potential, was evaluated in BALB/c mice. Then, its suitability for prophylactic and therapeutic applications was compared with that of the intact allergen, paying attention to the molecular and cellular mechanisms involved in the control of the allergic process. To this aim, IgE, IgG1, IgG2a and IgA levels, allergic reactions, expression of genes related to Th1, Th2, Th17 and Treg responses, dendritic and T cell populations were assessed in intestinal tissues and spleens of EW-allergic mice, either untreated or treated with intact ovalbumin (OVA) or OP. The hydrolysate of OVA with pepsin was hypoallergenic, lacked sensitizing potential and offered preventive and therapeutic protection against allergy to EW through the induction of Treg cells and the up-regulation of TGF-β, IL-10, IL-17, Foxp3 and RORγt in intestinal tissues. This restrained the expression of GATA3 and the differentiation of Th2 cells, leading to low cytokine responses following exvivo spleen cell stimulation. As compared with intact OVA, OP was more effective against sensitization. In addition, in the therapeutic setting, OP provided quicker desensitization that lasted for at least 3weeks after discontinuation of the therapy. This study provides evidence for the superior role of hydrolysed, as compared to intact allergens, in the prevention of allergy development and in the promotion of long-term desensitization, as well as of intermolecular tolerance.