Mechanisms underlying the induction of regulatory T cells by sublingual immunotherapy

Oral mucosa effectively protects against peanut allergy in mice

BACKGROUND

Oral consumption of peanut products early in life reduces the incidence of peanut allergy in children. However, little is known about whether exposure via the oral mucosa alone is sufficient or whether the gastrointestinal tract must be engaged to protect against peanut allergy.

OBJECTIVE

We used a mouse model and examined the effects of peanut allergen administration to only the oral cavity on allergy development induced by environmental exposure.

METHODS

Naive BALB/c mice were administered peanut flour (PNF) sublingually, followed by epicutaneous exposure to PNF to mimic a human condition. The sublingual volume was adjusted to engage only the oral cavity and prevent it from reaching the esophagus or gastrointestinal tract. The efficacy was evaluated by examining the anaphylactic response, antibody titers, and T follicular helper cells.

RESULTS

The mice exposed epicutaneously to PNF developed peanut allergy, as demonstrated by increased plasma levels of peanut-specific IgE and the manifestation of acute systemic anaphylaxis following intraperitoneal challenge with peanut extract. The development of peanut allergy was suppressed when mice had been given PNF sublingually before epicutaneous exposure. There were fewer T follicular helper cells in the skin-draining lymph nodes of mice that received sublingual PNF than in the mice that received PBS. Suppression of IgE production was observed with sublingual PNF at 1/10 of the intragastric PNF dose.

CONCLUSION

Administration of peanut allergens only to the oral cavity effectively prevents the development of peanut allergy. The capacity of the oral mucosa to promote immunologic tolerance needs to be evaluated further to prevent food allergy.

Soluble TAM Receptor Tyrosine Kinases Correlate with Disease Severity and Predict the Early Responsiveness of Sublingual Immunotherapy in Allergic Rhinitis

Background

Allergic rhinitis (AR) is a common allergic disease, and SLIT has shown effectiveness as a treatment method. This study focuses on the evaluation of serum TAM receptor tyrosine kinases (TYRO3, AXL, and MER) levels as potential indicators of disease severity and predictive markers for sublingual immunotherapy (SLIT) responsiveness in AR patients.

Methods

A total of 160 AR subjects, including 40 mild AR (MAR) and 120 moderate-severe AR (MSAR) patients, and 40 healthy controls (HC) were recruited. Serum concentrations of TYRO3, AXL, and MER were measured and their relationships with disease severity were examined. In the MSAR group, 102 patients underwent SLIT, and the early efficacy was evaluated. The correlations between the baseline serum concentrations of TYRO3, AXL, and MER and the early responsiveness of SLIT were analyzed.

Results

Serum concentrations of TYRO3, AXL, and MER were significantly reduced in AR patients, particularly in those MSAR subjects. Correlation analysis results indicated that serum TYRO3 and MER levels were negatively correlated with the visual analog scale (VAS) and the total nasal symptom score (TNSS). After one year of follow-up, 80 AR patients completed the treatment and were divided into effective and ineffective groups. Serum baseline levels of TYRO3 and MER were found to be lower in the effective group compared to the ineffective group. Additionally, there was a significant increase in serum TYRO3 and MER levels compared to baseline levels. Receiver operating characteristic (ROC) analysis revealed that circulating TYRO3 and MER had potential values for reflecting AR severity and predicting early SLIT responsiveness.

Conclusion

Serum TYRO3 and MER concentrations were decreased in AR patients and negatively associated with disease severity. Circulating TYRO3 and MER seem to be promising indicators for monitoring the efficacy of SLIT in AR patients.

Circulating MMP-12 as Potential Biomarker in Evaluating Disease Severity and Efficacy of Sublingual Immunotherapy in Allergic Rhinitis

Background

Allergic rhinitis (AR) is a highly heterogeneous disease, and allergen-specific immunotherapy (AIT) is an effective treatment. This study aims to evaluate the circulating mas-related G protein-coupled receptor-X2 (MRGPRX2) and matrix metalloproteinase-12 (MMP-12) levels in evaluating disease severity and predicting efficacy of SLIT in AR patients.

Methods

We enrolled 110 moderate-severe persist AR patients (AR group) and 40 healthy controls (HC group). Circulating levels of MRGPRX2 and MMP-12 were measured, and their associations with disease severity were evaluated. All AR patients were assigned to receive sublingual immunotherapy (SLIT), and the efficacy was evaluated, and serum samples were collected at 1 year and 3 years after treatment. The correlations between serum MRGPRX2 and MMP-12 and clinical efficacy were assessed.

Results

The serum concentrations of MRGPRX2 and MMP-12 were significantly higher in the AR group than the HC group, and the elevated MMP-12 levels were correlated with VAS and TNSS, and serum MRGPRX2 levels were correlated with VAS. Finally, 100 and 80 patients completed 1-year and 3-year follow-up and were classified into effective and ineffective groups. Serum MRGPRX2 and MMP-12 levels were lower in the effective group than the ineffective group. Although serum MRGPRX2 and MMP-12 levels did not significantly change after 1 year SLIT, serum MMP-12 levels were decreased 3 years post-SLIT than baseline and 1 year post-SLIT levels. Receiver operating characteristic (ROC) showed that serum MMP-12 was a potential biomarker for predicting the efficacy of SLIT.

Conclusion

Serum MRGPRX2 and MMP-12 appeared to be promising biological indicators in reflecting disease severity in AR patients. Moreover, circulating MMP-12 might serve as a reliable predictor for clinical responsiveness of SLIT.

Differential expression of CD11c defines two types of tissue-resident macrophages with different origins in steady-state salivary glands

Gland macrophages are primed for gland development and functions through interactions within their niche. However, the phenotype, ontogeny, and function of steady-state salivary gland (SG) macrophages remain unclear. We herein identified CD11c⁺ and CD11c^- subsets among CD64⁺ macrophages in steady-state murine SGs. CD11c^- macrophages were predominant in the SGs of embryonic and newborn mice and decreased with advancing age. CD11c⁺ macrophages were rarely detected in the embryonic period, but rapidly expanded after birth. CD11c⁺, but not CD11c^-, macrophage numbers decreased in mice treated with a CCR2 antagonist, suggesting that CD11c⁺ macrophages accumulate from bone marrow-derived progenitors in a CCR2-dependent manner, whereas CD11c^- macrophages were derived from embryonic progenitors in SGs. CD11c⁺ and CD11c^- macrophages strongly expressed colony-stimulating factor (CSF)-1 receptor, the injection of an anti-CSF-1 receptor blocking antibody markedly reduced both subsets, and SGs strongly expressed CSF-1, indicating the dependency of SG resident macrophage development on CSF-1. The phagocytic activity of SG macrophages was extremely weak; however, the gene expression profile of SG macrophages indicated that SG macrophages regulate gland development and functions in SGs. These results suggest that SG CD11c⁺ and CD11c^- macrophages are developed and instructed to perform SG-specific functions in steady-state SGs.

Allergic Rhinitis: What Do We Know About Allergen-Specific Immunotherapy?

Allergic rhinitis (AR) is an IgE-mediated disease that is characterized by Th2 joint inflammation. Allergen-specific immunotherapy (AIT) is indicated for AR when symptoms remain uncontrolled despite medication and allergen avoidance. AIT is considered to have been effective if it alleviated allergic symptoms, decreased medication use, improved the quality of life even after treatment cessation, and prevented the progression of AR to asthma and the onset of new sensitization. AIT can be administered subcutaneously or sublingually, and novel routes are still being developed, such as intra-lymphatically and epicutaneously. AIT aims at inducing allergen tolerance through modification of innate and adaptive immunologic responses. The main mechanism of AIT is control of type 2 inflammatory cells through induction of various functional regulatory cells such as regulatory T cells (Tregs), follicular T cells (Tfr), B cells (Bregs), dendritic cells (DCregs), innate lymphoid cells (IL-10⁺ ILCs), and natural killer cells (NKregs). However, AIT has a number of disadvantages: the long treatment period required to achieve greater efficacy, high cost, systemic allergic reactions, and the absence of a biomarker for predicting treatment responders. Currently, adjunctive therapies, vaccine adjuvants, and novel vaccine technologies are being studied to overcome the problems associated with AIT. This review presents an updated overview of AIT, with a special focus on AR.

Celiac Disease Causes Epithelial Disruption and Regulatory T Cell Recruitment in the Oral Mucosa

Celiac disease (CD) is a chronic autoimmune disease characterized by an immune-triggered enteropathy upon gluten intake. The only current treatment available is lifelong Gluten Free Diet (GFD). Several extraintestinal manifestations have been described in CD, some affecting the oral mucosa. Thus, we hypothesized that oral mucosa could potentially be a target for novel biomarkers and an administration route for CD treatment. Six de novo diagnosed and seven CD patients under GFD for at least 1 year were recruited. Non-celiac subjects (n = 8) were recruited as control group. Two biopsies of the cheek lining were taken from each subject for mRNA analysis and immunohistochemical characterization. We observed a significant decrease in the expression of epithelial junction proteins in all CD patients, indicating that oral mucosa barrier integrity is compromised. FoxP3+ population was greatly increased in CD patients, suggesting that Tregs are recruited to the damaged mucosa, even after avoidance of gluten. Amphiregulin mRNA levels from Peripheral Blood Mononuclear Cells (PBMCs) and epithelial damage in the oral mucosa correlated with Treg infiltration in all the experimental groups, suggesting that recruited Tregs might display a “repair” phenotype. Based on these results, we propose that oral mucosa is altered in CD and, as such, might have diagnostic potential. Furthermore, due to its tolerogenic nature, it could be an important target for oral immunotherapy.

Sublingual Immunotherapy: How Sublingual Allergen Administration Heals Allergic Diseases; Current Perspective about the Mode of Action

Owing to the successful application of sublingual immunotherapy (SLIT), allergen immunotherapy (AIT) has become one of the leading treatments for allergic diseases. Similar to the case with other AITs, such as subcutaneous and oral immunotherapies, not only the alleviation of allergic symptoms, but also the curing of the diseases can be expected in patients undergoing SLIT. However, how and why such strong efficacy is obtained by SLIT, in which allergens are simply administered under the tongue, is not clearly known. Various potential mechanisms, including the induction of blocking antibodies, T cell tolerance, regulatory B and T cells, CD103^-CD11b⁺ classical dendritic cells, and CD206⁺ macrophages, and the reduction of innate lymphoid cells, mast cells, and basophils, have been suggested. Recently, through a comparative analysis between high- and non-responder patients of SLIT, we have successfully proposed several novel mechanisms. Here, we introduce our recent findings and summarize the current understanding of the mechanisms underlying the strong efficacy of SLIT.

Activated leukocyte cell adhesion molecule as a biomarker for disease severity and efficacy of sublingual immunotherapy in allergic rhinitis

BACKGROUND

Activated leukocyte cell adhesion molecule (ALCAM) plays an important role in T cell activation and immune response, but the role of ALCAM in allergic rhinitis (AR) remains unclear. The objective of the current study was to validate serum ALCAM as a biomarker in assessing disease severity and predicting the efficacy of sublingual immunotherapy (SLIT) in AR patients.

METHODS

We recruited 40 healthy controls (HC group), 38 mild AR patients (MAR group) and 80 moderate-severe AR patients (MSAR group) in this study. Serum levels of ALCAM were determined by ELISA, and the association between ALCAM levels and disease severity was evaluated. In the MSAR group, 68 patients underwent and finished 3-years of SLIT, and were divided into effective group and ineffective group, the relationship between ALCAM levels and efficacy of SLIT was exampled.

RESULTS

ALCAM levels were elevated in the serum of AR patients in comparison with HC. Moreover, serum ALCAM concentrations were higher in MSAR group than in MAR group and HC group, and levels of ALCAM significantly correlated with AR total nasal symptom score (TNSS) (r = 0.330, P < 0.001), visual analogue scale (VAS) (r = 0.387, P < 0.001) and serum total IgE levels (r = 0.442, P < 0.001). In the effective group, the ALCAM levels were significantly lower than in the ineffective group. Receiver operating characteristic (ROC) curve exhibited good accuracy for predicting clinical efficacy of SLIT (area under the curve = 0.805, P < 0.001).

CONCLUSIONS

The serum ALCAM maybe a novel biomarker for assessing disease severity and predicting clinical efficacy of SLIT in AR patients.

Stability of regulatory T cells in T helper 2-biased allergic airway diseases

Regulatory T (Treg) cells potentially suppress the deleterious activities of effector T cells and maintain a state of tolerance against antigens in the airway mucosa. A decrease in the number and function of Treg cells is observed in T helper 2 (Th2)-biased allergic airway diseases. However, adoptive transfer of naturally occurring Treg (tTreg) cells or peripherally derived Treg (pTreg) cells in asthmatic mouse models did not yield satisfactory results in any previous studies. Here, we review the recent progress in the identification and plasticity of tTreg and pTreg cells in Th2-biased airway diseases and summarize the factors affecting the stability and function of Treg cells. This review may serve as foundation for understanding the molecular mechanisms underlying the stability of tTreg and pTreg cells and development of effective strategies for treating allergic airway diseases.

Oral biosciences: The annual review 2019

BACKGROUND

Journal of Oral Biosciences is devoted to the advancement and dissemination of fundamental knowledge concerning every aspect of oral biosciences.

HIGHLIGHT

This review features review articles in the fields of "Bone Cell Biology," "Microbiology," "Oral Heath," "Biocompatible Materials," "Mouth Neoplasm," and "Biological Evolution" in addition to the review articles by winners of the Lion Dental Research Award ("Role of nicotinic acetylcholine receptors for modulation of microcircuits in the agranular insular cortex" and "Phospholipase C-related catalytically inactive protein: A novel signaling molecule for modulating fat metabolism and energy expenditure") and the Rising Members Award ("Pain mechanism of oral ulcerative mucositis and the therapeutic traditional herbal medicine hangeshashinto," "Mechanisms underlying the induction of regulatory T cells by sublingual immunotherapy," and "Regulation of osteoclast function via Rho-Pkn3-c-Src pathways"), presented by the Japanese Association for Oral Biology.

CONCLUSION

These reviews in the Journal of Oral Biosciences have inspired the readers of the journal to broaden their knowledge regarding various aspects of oral biosciences. The current editorial review introduces these exciting review articles.

The clinical and immune outcomes after food allergen immunotherapy emphasizing the development of tolerance

PURPOSE OF REVIEW

The present review serves to outline the direction of food allergy immunotherapy research with an emphasis on clinical and immunologic outcomes. It helps to delineate sustained unresponsiveness achieved from food immunotherapy as the clinical outcome most similar to immune tolerance.

RECENT FINDINGS

We will discuss the difference between immune tolerance, desensitization, and sustained unresponsiveness in relation to food immunotherapy by discussing the clinical and immunologic changes which have been recently discovered.

SUMMARY

Research has recently shown that oral immunotherapy is most efficacious clinically at achieving desensitization to a food and sustained unresponsiveness.