Phenotype analyses of IL-10-producing Foxp3- CD4+ T cells increased by subcutaneous immunotherapy in allergic airway inflammation

HLA-DR+ regulatory T cells and IL-10 are associated with success or failure of desensitization outcomes

BACKGROUND

Omalizumab (XOLAIR®)-assisted multi-food oral immunotherapy (mOIT) has been shown to safely, effectively, and rapidly desensitize patients with multiple food allergies. In our clinical trial (NCT02626611) on omalizumab-assisted mOIT, different desensitization outcomes (success or failure of desensitization) were observed following a period of either continued or discontinued mOIT. However, the association between the immunological changes induced by omalizumab-assisted mOIT and desensitization outcomes has not yet been fully elucidated. In this study, due to the key roles of regulatory T (Treg) cells and the type 2 helper T cell (Th2) pathway in immune tolerance to food allergens, we aimed to characterize their association with the desensitization outcomes of omalizumab-assisted mOIT.

METHODS

Mass cytometry and multiplex cytokine assays were performed on blood samples obtained from participants with allergies to peanut, cashew, or milk in our phase 2 clinical study (NCT02626611). Comprehensive statistical and bioinformatic analyses were conducted on high-dimensional cytometry-based single-cell data and high-throughput multiplex cytokine data.

RESULTS

Our results demonstrated that the frequency of HLA-DR+ Treg cells, and the production of Th2 cytokines (IL-4, IL-5, IL-13, and IL-9) as well as the immunoregulatory cytokine IL-10 by peripheral blood mononuclear cells (PBMCs) was significantly increased in cultures with allergen compared to cultures with media alone at baseline (Week 0). We also observed increased frequency of allergen responsive HLA-DR+ Treg cells and enhanced production of IL-10 by PBMCs in participants who achieved successful desensitization compared to those with failure of desensitization. However, the production of Th2 cytokines by PBMCs did not show significant differences between participants with different desensitization outcomes (success vs. failure of desensitization), despite omalizumab-assisted mOIT inducing a significant reduction in the production of Th2 cytokines.

CONCLUSIONS

We demonstrated that the frequency of HLA-DR+ Treg cells and IL-10 cytokine production by PBMCs are associated with desensitization outcomes of omalizumab-assisted mOIT. These findings suggest potential immunological parameters that could be targeted to enhance desensitization success rates.

Involvement of Janus kinase-dependent Bcl-xL overexpression in steroid resistance of group 2 innate lymphoid cells in asthma

The mechanisms underlying the development of steroid resistance in asthma remain unclear. To establish whether as well as the mechanisms by which the activation of Janus kinases (JAKs) is involved in the development of steroid resistance in asthma, murine steroid-resistant models of the proliferation of group 2 innate lymphoid cells (ILC2s) in vitro and asthmatic airway inflammation in vivo were analysed. ILC2s in the lungs of BALB/c mice were sorted and then incubated with IL-33, thymic stromal lymphopoietin (TSLP), and/or IL-7 with or without dexamethasone (10 nM), the pan-JAK inhibitor, delgocitinib (1-10 000 nM), and/or the Bcl-xL inhibitor, navitoclax (1-100 nM), followed by the detection of viable and apoptotic cells. The anti-apoptotic factor, Bcl-xL was detected in ILC2s by flow cytometry. As a steroid-resistant asthma model, ovalbumin (OVA)-sensitized BALB/c mice were intratracheally challenged with OVA at a high dose of 500 μg four times. Dexamethasone (1 mg/kg, i.p.), delgocitinib (3-30 mg/kg, p.o.), or navitoclax (30 mg/kg, p.o.) was administered during the challenges. Cellular infiltration into the lungs was analysed by flow cytometry. Airway remodelling was histologically evaluated. The following results were obtained. (1) Cell proliferation concomitant with a decrease in apoptotic cells was induced when ILC2s were cultured with TSLP and/or IL-7, and was potently inhibited by dexamethasone. In contrast, when the culture with TSLP and IL-7 was performed in the presence of IL-33, the proliferative response exhibited steroid resistance. Steroid-resistant ILC2 proliferation was suppressed by delgocitinib in a concentration-dependent manner. (2) The culture with IL-33, TSLP, and IL-7 induced the overexpression of Bcl-xL, which was clearly inhibited by delgocitinib, but not by dexamethasone. When ILC2s were treated with navitoclax, insensitivity to dexamethasone was significantly cancelled. (3) The development of airway remodelling and the infiltration of ILC2s into the lungs in the asthma model were not suppressed by dexamethasone, but were dose-dependently inhibited by delgocitinib. Combination treatment with dexamethasone and either delgocitinib or navitoclax synergistically suppressed these responses. Therefore, JAKs appear to play significant roles in the induction of steroid resistance by up-regulating Bcl-xL in ILC2s. The inhibition of JAKs and Bcl-xL has potential as pharmacotherapy for steroid-resistant asthma, particularly that mediated by ILC2s.

Steroid-Insensitive Gene Expression of Extracellular Matrix Components and Pro-fibrotic Factors in the Lung Associated with Airway Hyperresponsiveness in Murine Asthma

Between 5 and 10% of asthma patients do not respond to glucocorticoid therapy. Experimental animal models are indispensable for investigating the pathogenesis of steroid-resistant asthma; however, the majority of murine asthma models respond well to glucocorticoids. We previously reported that multiple intratracheal administration of ovalbumin (OVA) at a high dose (500 µg/animal) induced steroid-insensitive airway eosinophilia and remodeling with lung fibrosis, whereas a low dose (5 µg/animal) caused steroid-sensitive responses. The aims of the present study were as follows: 1) to clarify whether airway hyperresponsiveness (AHR) in the two models is also insensitive and sensitive to a glucocorticoid, respectively, and 2) to identify steroid-insensitive genes encoding extracellular matrix (ECM) components and pro-fibrotic factors in the lung. In comparisons with non-challenged group, the 5- and 500-µg OVA groups both exhibited AHR to methacholine. Daily intraperitoneal treatment with dexamethasone (1 mg/kg) significantly suppressed the development of AHR in the 5-µg OVA group, but not in the 500-µg OVA group. Among genes encoding ECM components and pro-fibrotic factors, increased gene expressions of fibronectin and collagen types I, III, and IV as ECM components as well as 7 matrix metalloproteinases, tissue inhibitor of metalloproteinase-1, transforming growth factor-β1, and activin A/B as pro-fibrotic factors were insensitive to dexamethasone in the 500-µg OVA group, but were sensitive in the 5-µg OVA group. In conclusion, steroid-insensitive AHR developed in the 500-µg OVA group and steroid-insensitive genes encoding ECM components and pro-fibrotic factors were identified. Drugs targeting these molecules have potential in the treatment of steroid-resistant asthma.

Sustained antigens delivery using composite microneedles for effective epicutaneous immunotherapy

Allergen-specific immunotherapy (SIT) is a desirable way of therapy for various allergic diseases such as food allergy (FA). However, frequent visits for more than 3 years and potential adverse effects often hinder patient compliance. Recently, many researchers started focusing on microneedles (MNs) as a new method for SIT. In this study, we proposed an implantable MNs system produced by a two-step casting process, consisting of OVA (antigen)-loaded silk microneedles and a dissolvable, flexible polyvinyl alcohol (PVA) pedestal. Different from PVA, silk fibroin hydrogel has preferable vaccine release ability in vivo and in vitro. Once MNs are inserted into the skin, the PVA pedestal can dissolve in the interstitial fluid of the excised skin within 5 min and implant the OVA-loaded silk microneedle tips in dermal layer as a sustained antigen depot, thus inducing long-lasting immune response for at least 2 weeks. After receiving 3 doses of MN-based immunotherapy, the immune response in OVA-sensitized mice was successfully suppressed, with no apparent side effects. Compared to conventional subcutaneous immunotherapy (total dose of 150 [Formula: see text]g), MN immunotherapy ameliorated systemic anaphylaxis more effectively even at a lower dose (total dose of 30 [Formula: see text]g), demonstrating the antigen dose-sparing potential of the proposed MNs. Moreover, due to the prolonged release effect of silk-PVA composite MNs, the frequency of immunotherapy can be significantly reduced. To sum up, through prolonged skin exposure to antigen, this implantable designed MN may offer a new therapeutic strategy for FA treatment with significant improvements in efficacy and convenience. Schematic illustration of silk-PVA composite microneedles, consisting of OVA (antigen)-loaded silk microneedles and a dissolvable, flexible PVA pedestal. Once inserted into the skin, the PVA pedestal can dissolve in the interstitial fluid of the excised skin within 5 min. Subsequently, the OVA-loaded silk microneedle tips were implanted in the dermal layer as a sustained antigen depot and induced long-lasting immune response. This MNs-based immunotherapy can significantly modulate the Th1/Th2 imbalance of sensitized mice.

Cationic liposomes bearing Bet v 1 by coiled coil-formation are hypo-allergenic and induce strong immunogenicity in mice

Although aluminum hydroxide (alum) is widely accepted and used as safe vaccine adjuvant, there is some concern about possible toxicity upon long-lasting repeated exposure during subcutaneous allergen immunotherapy (SCIT). Our objective was to evaluate allergen-bearing liposomes as possible alternative for alum-adsorption in SCIT. A self-assembling, coiled-coil forming peptide pair was used to anchor the major birch pollen allergen Bet v 1 to the surface of cationic liposomes. The resulting nanoparticulate liposomes were characterized with respect to their physicochemical, allergenic and immunological properties. Allergenicity was studied by ImmunoCAP inhibition and rat basophil leukemia (RBL) cell assays. Immunogenicity (immunoglobulin responses) and immune skewing (cytokine responses) were evaluated upon immunization of naïve mice, and compared to alum-adsorbed Bet v 1. Bet v 1-bearing cationic liposomes with a diameter of ∼200 nm showed a positive zeta potential. The coiled-coil conjugation of Bet v 1 to the surface of liposomes resulted in about a 15-fold lower allergenicity than soluble Bet v 1 as judged by RBL assays. Moreover, the nanoparticles induced Bet v 1-specific IgG1/IgG2a responses in mice that were several orders of magnitude higher than those induced by alum-adsorbed Bet v 1. This strong humoral response was accompanied by a relatively strong IL-10 induction upon PBMC stimulation with Bet v 1. In conclusion, their hypo-allergenic properties, combined with their capacity to induce a strong humoral immune response and a relatively strong IL-10 production, makes these allergen-covered cationic liposomes a promising alternative for aluminum salt-adsorption of allergen currently used in SCIT.

Extracellular Vesicles Derived from Allergen Immunotherapy-Treated Mice Suppressed IL-5 Production from Group 2 Innate Lymphoid Cells

Allergen immunotherapy (AIT), such as subcutaneous immunotherapy (SCIT), is a treatment targeting the causes of allergic diseases. The roles of extracellular vesicles (EVs), bilayer lipid membrane blebs released from all types of cells, in AIT have not been clarified. To examine the roles of EVs in SCIT, it was analyzed whether (1) EVs are phenotypically changed by treatment with SCIT, and (2) EVs derived from SCIT treatment suppress the function of group 2 innate lymphoid cells (ILC2s), which are major cells contributing to type 2 allergic inflammation. As a result, (1) expression of CD9, a canonical EV marker, was highly up-regulated by SCIT in a murine model of asthma; and (2) IL-5 production from ILC2s in vitro was significantly decreased by the addition of serum EVs derived from SCIT-treated but not non-SCIT-treated mice. In conclusion, it was indicated that EVs were transformed by SCIT, changing to a suppressive phenotype of type 2 allergic inflammation.

Roles of type 1 regulatory T (Tr1) cells in allergen-specific immunotherapy

Allergen-specific immunotherapy (AIT) is the only causative treatment for allergic diseases by modification of the immune response to allergens. A key feature of AIT is to induce immunotolerance to allergens by generating antigen-specific regulatory T (Treg) cells in allergic patients. Type 1 regulatory T (Tr1) cells and forkhead box protein 3 (Foxp3)-expressing Treg cells are well known among Treg cell subsets. Foxp3 was identified as a master transcription factor of Treg cells, and its expression is necessary for their suppressive activity. In contrast to Foxp3⁺ Treg cells, the master transcription factor of Tr1 cells has not been elucidated. Nevertheless, Tr1 cells are generally considered as a distinct subset of Treg cells induced in the periphery during antigen exposure in tolerogenic conditions and can produce large amounts of anti-inflammatory cytokines such as interleukin-10 and transforming growth factor-β, followed by down-regulation of the function of effector immune cells independently of Foxp3 expression. Since the discovery of Tr1 cells more than 20 years ago, research on Tr1 cells has expanded our understanding of the mechanism of AIT. Although the direct precursors and true identity of these cells continues to be disputed, we and others have demonstrated that Tr1 cells are induced in the periphery by AIT, and the induced cells are re-activated by antigens, followed by suppression of allergic symptoms. In this review, we discuss the immune mechanisms for the induction of Tr1 cells by AIT and the immune-suppressive roles of Tr1 cells in AIT.

Local IL-10 replacement therapy was effective for steroid-insensitive asthma in mice

Subgroups of patients with severe asthma showing marked increases in sputum eosinophils and/or neutrophils are insensitive to corticosteroids. Previous reports have shown that exogenous administration of an anti-inflammatory cytokine, interleukin (IL)-10 negatively regulated both eosinophilic and neutrophilic migration into tissues. The objective of this study was to elucidate whether intratracheal IL-10 administration suppresses asthmatic responses in a steroid-insensitive model of mice. Ovalbumin (OVA)-sensitized BALB/c mice were intratracheally challenged with OVA at 500 µg/animal four times. Dexamethasone (1 mg/kg, intraperitoneal) or IL-10 (25 ng/mouse, intratracheal) was administered during the multiple challenges. The number of leukocytes, expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and IL-10 receptor in the lung, and the development of airway remodeling and hyperresponsiveness were evaluated after the fourth challenge. Consistent with our previous study, dexamethasone hardly suppressed the development of airway remodeling and hyperresponsiveness. Although intratracheal IL-10 administration did not affect the development of airway remodeling, the infiltration of eosinophils and neutrophils, and the development of airway hyperresponsiveness were significantly inhibited. Moreover, IL-10 administration significantly decreased the numbers of ICAM-1⁺ and VCAM-1⁺ pulmonary vascular endothelial cells, which express IL-10 receptor 1, even though neither production of eosinophilic nor neutrophilic cytokines in the lung was inhibited. Therefore, IL-10 can suppress eosinophil and neutrophil infiltration by inhibiting the proliferation of ICAM-1⁺ and VCAM-1⁺ pulmonary vascular endothelial cells, resulting in inhibition of airway hyperresponsiveness in steroid-insensitive asthmatic mice. IL-10 replacement therapy may be clinically useful for the treatment of steroid-insensitive asthma.

[Anti-inflammatory Strategies by Focusing on the Particularity of Ocular Immunity]

Particularity of ocular immunity is manifested by "Immune privilege". For example, it has been generally known that corneal transplantation is a typically successful organ transplantation compared with other organs. This immune privilege can be explained by "immune-suppressive ocular microenvironment" and "anterior chamber-associated immune deviation, ACAID". This review focused on molecular mechanisms of the "immune-suppressive ocular microenvironment" and "ACAID", so that possible anti-inflammatory strategies could be raised. Especially, in murine ACAID model, anti-inflammatory actions were induced probably through induction of Treg cells. As an anti-inflammatory strategy, anti-inflammatory Treg cells could be induced in vitro. Treg cells that are specifically responsive for a specific antigen can be induced by culturing spleen cells with the antigen and transforming growth factor-β (TGF-β). The induced Treg cells were activated by stimulation with the specific antigen. When the induced Treg cells were adoptively transferred to recipient mice, antigen-induced inflammation was effectively suppressed. The Treg cells may be able to be efficiently induced by eye-based mechanisms. Further analyses of mechanisms underlying the ocular immune privilege can be useful for development of new anti-inflammatory strategies on the eye basis.

CircRNA expression profiles and circRNA-miRNA-mRNA crosstalk in allergic rhinitis

Background

Circular RNAs (circRNAs) are involved in inflammation; however, their role in allergic rhinitis (AR) remains unclear. In this study, we analyzed circRNA expression and identified a circRNA-miRNA-mRNA network through which circRNAs regulate AR pathogenesis.

Methods

We analyzed circRNA, miRNA, and mRNA expression profiles in the nasal mucosa by high-throughput sequencing (HTS), using a fold-change >1.5 and p-value < 0.05 to pinpoint significantly differentially expressed (DE) circRNAs, miRNAs, and mRNAs in AR. A DEcircRNA-DEmiRNA-DEmRNA crosstalk network was then constructed using bioinformatics and statistical analysis. Gene ontology and Kyoto encyclopedia of genes and genomes pathway analyses were performed to identify the biological terms enriched in the network; whereas RT-PCR and Sanger sequencing were used to confirm the circRNAs.

Results

A total of 264 DEcircRNAs were identified by HTS, including 120 upregulated and 144 downregulated in AR compared to controls. A DEcircRNA-DEmiRNA-DEmRNA crosstalk network was constructed with 17 miRNAs, 11 circRNAs, 29 mRNAs, and 64 interaction pairs. These genes were involved in the Wnt signaling pathway, TNF biosynthesis, inflammatory responses, the PI3K-Akt signaling pathway, and Toll-like receptors. Of the 11 DEcircRNAs, hsa_circ_0008668 and circTRIQK were upregulated, whereas hsa_circ_0029853 and circRNA_01002 were downregulated in AR tissues. Sanger sequencing confirmed the back-splicing junctions of these circRNAs.

Conclusions

We constructed a novel DEcircRNA-DEmiRNA-DEmRNA network for AR that provides a basis for future studies to investigate its underlying molecular mechanisms.

NOX1/NADPH oxidase is involved in the LPS-induced exacerbation of collagen-induced arthritis

We investigate as yet an unidentified role of NOX1, a non-phagocytic isoform of the superoxide-generating NADPH oxidase, in immune responses using Nox1-knockout mice (Nox1-KO). The transcripts of NOX1 was expressed in lymphoid tissues, including the spleen, thymus, bone marrow, and inguinal lymphoid nodes. When antibody production after ovalbumin (OVA) immunization was examined, no significant differences were observed in serum anti-OVA IgG levels between wild-type mice (WT) and Nox1-KO. In the experimental asthma, the infiltration of eosinophils and the Th2 cytokine response after the induction of asthma with OVA were similar between the two genotypes. However, the severity and incidence of experimental collagen-induced arthritis (CIA) following the administration of a low dose of endotoxin (LPS) were significantly lower in Nox1-KO. While neither serum levels of autoantibodies nor in vitro cytokine responses were affected by Nox1 deficiency, NOX1 mRNA levels in the spleen significantly increased after the LPS challenge. Among the spleen cells, remarkable LPS-induced upregulation of NOX1 was demonstrated in both CD11b+ monocytes/macrophages and CD11c+ dendritic cells, suggesting that LPS-inducible NOX1 in monocytes/macrophages/dendritic cells may modulate the development of experimental CIA. Therapeutic targeting of NOX1 may therefore control the onset and/or severity of arthritis which is exacerbated by bacterial infection.

Sublingual immunotherapy for 4 years increased the number of Foxp3+ Treg cells, which correlated with clinical effects

OBJECTIVE

At least 3 years of sublingual immunotherapy (SLIT) is required to achieve long-term clinical tolerance for allergens. However, immunological changes with more than 3 years of SLIT have not yet been elucidated in detail. The present study investigated whether the numbers of regulatory T (Treg) cells and regulatory B (Breg) cells increased with 4 years of SLIT and if these increases correlated with clinical effects for pollinosis.

METHODS

Seven Japanese cedar pollinosis patients received SLIT in 2014 or 2015 and continued treatment until May 2019. In May 2017 and May 2019, peripheral blood mononuclear cells (PBMCs) were collected from the patients, and analyzed by flow cytometer.

RESULTS

(1) The visual analogue scale (VAS) was significantly higher in 2019 than in 2017. (2) The percentages of Foxp3⁺ Treg cells, type 1 regulatory T (Tr1) cells, and Breg cells in PBMCs were significantly higher in 2019 than in 2017. (3) The percentage of Foxp3⁺ Treg cells in PBMCs positively correlated with VAS, whereas those of Tr1 cells and Breg cells did not.

CONCLUSIONS

These results suggest that 4 years of SLIT is needed to achieve sustained increases in Foxp3⁺ Treg cells, which are closely associated with the efficacy of SLIT.

A20-OVA Nanoparticles Inhibit Allergic Asthma in a Murine Model

The skewed T helper (Th) 2 response plays a critical role in the pathogenesis of allergic asthma. Regulatory T (Treg) cells and the regulatory cytokines are required in maintaining the homeostasis in the body. This study aims to determine the effects of a poly(lactic-co-glycolic) acid (PLGA)-ovalbumin (OVA)+A20 (a ubiquitin E3 ligase) nanovaccine on inhibiting allergic asthma in a murine model. In this study, A20 and OVA (a model antigen) were encapsulated into PLGA to be a nanovaccine (PLGA-OVA+A20). An allergic asthma murine model was developed with OVA as the specific antigen to test the role of PLGA-OVA+A20 nanovaccine in maintaining the immune homeostasis in the airway tissues. The results showed that PLGA-OVA+A20 nanovaccine inhibited the asthma responses in mice by suppressing Th2 inflammatory responses, promoting the generation of Treg cells in the airway tissues. We conclude that the PLGA-OVA+A20 nanovaccine has a marked inhibitory effect on the airway allergic response in sensitized mice by significantly promoting the generation of Treg cell and IL-10. The data suggest that PLGA-OVA+A20 has translational potential in the treatment of allergic asthma.

T follicular regulatory cells and IL-10 promote food antigen-specific IgE

Food allergies are a major clinical problem and are driven by IgE antibodies (Abs) specific for food antigens (Ags). T follicular regulatory (Tfr) cells are a specialized subset of FOXP3+ T cells that modulate Ab responses. Here, we analyzed the role of Tfr cells in regulating Ag-specific IgE using a peanut-based food allergy model in mice. Peanut-specific IgE titers and anaphylaxis responses were significantly blunted in Tfr cell-deficient Foxp3-Cre Bcl6fl/fl mice. Loss of Tfr cells led to greatly increased nonspecific IgE levels, showing that Tfr cells have both helper and suppressor functions in IgE production in the germinal center (GC) that work together to facilitate the production of Ag-specific IgE. Foxp3-Cre Ptenfl/fl mice with augmented Tfr cell responses had markedly higher levels of peanut-specific IgE, revealing an active helper function by Tfr cells on Ag-specific IgE. The helper function of Tfr cells for IgE production involves IL-10, and the loss of IL-10 signaling by B cells led to a severely curtailed peanut-specific IgE response, decreased GCB cell survival, and loss of GC dark zone B cells after peanut sensitization. We thus reveal that Tfr cells have an unexpected helper role in promoting food allergy and may represent a target for drug development.

Regulatory T and B cells in peripheral blood of subcutaneous immunotherapy-treated Japanese cedar pollinosis patients

AIM

The aim of this study was to clarify whether there are more regulatory T (Treg) and regulatory B (Breg) cells, and higher levels of IL-10-related transcription factors in subcutaneous immunotherapy (SCIT)-treated pollinosis patients than in non-SCIT-treated patients.

METHODS

Japanese cedar pollinosis patients undergoing SCIT had received treatment for at least 2.8 years. Peripheral blood mononuclear cells were used for flow cytometer analyses and mRNA measurement.

RESULTS

The numbers of type 1 regulatory T (Tr1)-like cells and Breg cells, and expression of E4BP4 mRNA by peripheral blood mononuclear cells in SCIT-treated patients were higher than those in non-SCIT-treated patients.

CONCLUSION

Tr1-like cells, Breg cells and E4BP4 may be involved in the effectiveness of SCIT.

Adoptive transfer of type 1 regulatory T cells suppressed the development of airway hyperresponsiveness in ovalbumin-induced airway inflammation model mice

Type 1 regulatory T (Tr1) cells are CD4⁺ T cells that produce a large amount of IL-10, an anti-inflammatory cytokine. However, it has not been fully elucidated whether Tr1 cells suppress allergic asthma. In this study, the effects of adoptive transfer of in vitro-induced Tr1 cells on allergic asthma were evaluated. Splenocytes from ovalbumin (OVA)-sensitized BALB/c mice were cultured with OVA, IL-21, IL-27, and TGF-β. After culture, IL-10-producing CD4⁺ T cells were isolated by Dynabeads mouse CD4 and IL-10 secretion assay, and analyzed by flow cytometry. Purified Tr1 cells (IL-10⁺ CD4⁺ T cells) were intravenously injected into OVA-sensitized BALB/c mice. The recipient mice were intratracheally challenged with OVA. Airway hyperresponsiveness to methacholine was assessed by the forced oscillation technique, followed by bronchoalveolar lavage (BAL). Almost all of the induced IL-10-producing CD4⁺ T cells were negative for interferon-γ, IL-4, IL-17A, and forkhead box P3, suggesting that the cells were Tr1 cells. The adoptive transfer of Tr1 cells significantly suppressed the development of airway hyperresponsiveness, and increases in IL-5, eosinophils, and neutrophils in BAL fluid. In conclusion, we demonstrated that Tr1 cells suppressed allergic asthma in mice.

[Analyses of Foxp3+ Treg cells and Tr1 cells in subcutaneous immunotherapy-treated allergic individuals in humans and mice]

Subcutaneous immunotherapy (SCIT) is a causative treatment for allergic diseases. More recently, it has become clear that regulatory T (Treg) cells are increased by SCIT. Treg cells are generally divided into two main groups: 1) CD25⁺ Foxp3⁺ CD4⁺ T cells (Foxp3⁺ Treg cells) and 2) IL-10-producing Foxp3^- CD4⁺ T cells (Tr1 cells). We demonstrated that the number of Tr1 cells in peripheral blood mononuclear cells in SCIT-treated pollinosis patients were significantly higher than that in non-SCIT-treated patients, but Foxp3⁺ Treg cells were not. Consistent with the results of human peripheral blood, Tr1 cells were increased in the lungs of asthmatic mice by SCIT, but Foxp3⁺ Treg cells were not. Moreover, in vitro-induced Tr1 cells were responded to the antigen to produce a large amount of IL-10 in in vitro and in vivo. Adoptive transfer of the induced Tr1 cells significantly suppressed the development of asthma. In any species of human and mouse, the increase in Tr1 cells rather than Foxp3⁺ Treg cells could be important for the effects of SCIT. The increased Tr1 cells by SCIT functionally suppressed allergic asthma probably via production of IL-10 in response to the specific antigen. Therefore, analyses of the induction mechanisms of Tr1 cells and search for compounds which induce Tr1 cells are thought to lead to development of more efficient SCIT.