1,25(OH)2VitD3 supplementation enhances suppression of grass pollen-induced allergic asthma by subcutaneous and sublingual immunotherapy in a mouse model

Vitamin D and allergic diseases

In recent years, the relationship between vitamin D and allergic diseases has received widespread attention. As a fat-soluble vitamin, vitamin D plays a crucial role in regulating the immune system and may influence the onset and progression of diseases such as atopic dermatitis, allergic rhinitis, and asthma. To understand the underlying mechanisms, we have summarized the current research on the association between vitamin D and allergic diseases. We also discuss the impact of vitamin D on the immune system and its role in the course of allergic diseases, particularly focusing on how vitamin D supplementation affects the treatment outcomes of these conditions. We aim to provide a theoretical basis and practical guidance for optimizing the management and treatment of allergic diseases by modulating vitamin D levels.

Randomized, Double-Blind, Placebo-Controlled Trial of Vitamin D Supplementation in the Build-up Phase of House Dust Mite-Specific Immunotherapy

PURPOSE

Vitamin D (VitD) is an immunomodulatory molecule capable of alleviating allergic symptoms. However, the effectiveness of allergen-specific immunotherapy (AIT) is not commonly evidenced in the early build-up phase. The aim of the study was to determine the potential of VitD supplementation in this treatment phase.

METHODS

Thirty-four house dust mite (HDM)-allergic adult patients treated with subcutaneous AIT were randomized to receive VitD2 60,000 IU/week or placebo for 10 weeks and followed up for 10 weeks. The primary endpoints were the symptom-medication score (SMS) and the treatment response rate. The secondary endpoints were eosinophil count and levels of plasma IL-10, Der p 2-specific IgG4, and dysfunctional regulatory T (CRTH2⁺ Treg) cells.

RESULTS

Of 34 patients, 15 in each group completed the study. Patients with VitD deficiency receiving a VitD supplement showed significantly lower mean change SMS than the placebo group in weeks 10 (mean difference -54.54%, P = 0.007) and 20 (mean difference -42.69%, P = 0.04). The percentage of treatment responders reached 78% and 50% in the VitD and placebo groups, respectively, and the effect remained in week 20 (89% and 60%). No significant difference was observed for the tested immunological read-outs, with the exception of the frequency of CRTH2⁺ Treg cells, which was remarkably reduced in the VitD-treated patients. Moreover, improvement in SMS was correlated to the number of CRTH2⁺ Treg cells. Our in vitro experiment indicated that VitD downregulated activation markers, whereas it improved the function of CRTH2⁺ Treg cells.

CONCLUSIONS

VitD supplementation in the build-up phase of AIT could relieve symptoms and decrease Treg cell dysfunction, especially in patients with VitD deficiency.

Immune mechanisms induced by sublingual immunotherapy in allergic respiratory diseases

Allergic respiratory diseases (ARDs) are still a major burden on global public health. Sublingual immunotherapy (SLIT) is a mode of allergen immunotherapy (AIT) which involves administration of the allergen under the tongue, and benefits from tolerogenic properties of the oral mucosa. Studies revealed reduced levels of eosinophilia and eosinophil-dominated inflammation in airways of both animals and humans after SLIT. SLIT was also suggested to lower basophil responsiveness and innate lymphoid cell-2 function in blood samples collected from patients with ARD. Moreover, apart from shifting pathogenic type 2 (TH2) to a type 1 (TH1) and protective regulatory (Treg) polarization of helper T-cell immune response, antibody isotype switch from IgE to IgG1, IgG2, IgG4 and IgA was also reported in patients with ARD receiving SLIT. Today, the literature on SLIT-mediated activities is still scarce and more studies are required to further enlighten the mechanisms utilized by SLIT for the induction of tolerance. The aim of this review is to summarize the current knowledge about the immune-regulatory mechanisms induced by SLIT against ARDs.

Effect of baseline serum vitamin D level on symptom and medication scores of subcutaneous immunotherapy in children with mite allergy

INTRODUCTION

Allergen immunotherapy (AIT) is considered to be the only treatment that may change the natural process of allergic diseases. Subcutaneous immunotherapy (SCIT) is a type of allergen immunotherapy that is commonly used in clinical practice. However, SCIT has inconsistent effects on individuals, and it is yet unclear what factors affect therapeutic efficacy. In recent years, vitamin D levels have been speculated as a potential factor influencing SCIT efficacy.

OBJECTIVE

To investigate the effect of serum vitamin D level on the SCIT efficacy in children with allergic rhinitis and/or asthma caused by dust mite allergy.

METHODS

According to the panel consensus, children with asthma and/or allergic rhinitis who received SCIT were divided into the vitamin D deficiency group (<12 ng/ml), vitamin D insufficiency group (12-20 ng/ml), and vitamin D sufficiency group (>20 ng/ml). Serum 1-25(OH) D3, blood eosinophil, total IgE, dermatophagoides pteronyssinus (Dp), and dermatophagoides farina (Df) specific IgE (sIgE) were detected, and questionnaires of symptom and medication scores were collected before and after one year of treatment.

RESULTS

After one year of SCIT treatment, the symptom and medication score significantly decreased (P < 0.05), but there was no difference between the efficacy in different groups (P > 0.05). Our study found a statistical difference in Dp sIgE level between the vitamin D deficiency and the sufficiency groups (P = 0.024), and vitamin D levels become lower with children's growth (Y = -0.8981*X + 34.26, P = 0.0025).

CONCLUSIONS

No difference was found between the efficacy of one-year SCIT and serum vitamin D levels based on symptom and medication scores. Nevertheless, higher vitamin D levels may be associated with a decreased indicator of Dp allergy.

High dose vitamin D3 empowers effects of subcutaneous immunotherapy in a grass pollen-driven mouse model of asthma

Allergen-specific immunotherapy (AIT) has the potential to provide long-term protection against allergic diseases. However, efficacy of AIT is suboptimal, while application of high doses allergen has safety concerns. The use of adjuvants, like 1,25(OH)2VitD3 (VitD3), can improve efficacy of AIT. We have previously shown that low dose VitD3 can enhance suppression of airway inflammation, but not airway hyperresponsiveness in a grass pollen (GP)-subcutaneous immunotherapy (SCIT) mouse model of allergic asthma. We here aim to determine the optimal dose and formulation of VitD3 for the GP SCIT. GP-sensitized BALBc/ByJ mice received three SCIT injections of VitD3-GP (30, 100, and 300 ng or placebo). Separately, synthetic lipids, SAINT, was added to the VitD3-GP-SCIT formulation (300 nmol) and control groups. Subsequently, mice were challenged with intranasal GP, and airway hyperresponsiveness, GP-specific IgE, -IgG1, and -IgG2a, ear-swelling responses (ESR), eosinophils in broncho-alveolar lavage fluid and lung were measured. VitD3 supplementation of GP-SCIT dose-dependently induced significantly enhanced suppression of spIgE, inflammation and hyperresponsiveness, while neutralizing capacity was improved and ESR were reduced. Addition of VitD3 further decreased Th2 cytokine responses and innate cytokines to allergens in lung tissue by GP-SCIT. However, addition of synthetic lipids to the allergen/VitD3 mixes had no additional effect on VitD3-GP-SCIT. We find a clear, dose dependent effect of VitD3 on GP-SCIT-mediated suppression of allergic inflammation and airway hyperresponsiveness. In contrast, addition of synthetic lipids to the allergen/VitD3 mix had no therapeutic effect. These studies underscore the relevance of VitD3 as an adjuvant to improve clinical efficacy of SCIT treatment regimens.