Allergen immunotherapy modulates sensitivity of Treg cells to apoptosis in a rat model of allergic asthma

UHPLC/MS-based metabolomics of asthmatic mice reveals metabolic changes in group 2 innate lymphoid cells

Helper Th2-type immune responses are essential in allergic airway diseases, including asthma and allergic rhinitis. Recent studies have indicated that group 2 innate lymphoid cells (ILC2s) play a crucial role in the occurrence and development of asthma. However, the metabolic profile of ILC2s and their regulatory mechanisms in asthma remain unclear. Therefore, we established two asthma mouse models: an ovalbumin (OVA)-induced asthma model and an IL-33-induced asthma model. We then used ultra-high-performance liquid chromatography/mass spectrometry (UHPLC/MS) to conduct high-throughput untargeted metabolic analysis of ILC2s in the lung tissues of the asthma models. The identified metabolites primarily consisted of lipids, lipid-like molecules, benzene, organic acids, derivatives, and organic oxidation compounds. Specifically, 34 differentially accumulated metabolites influenced the metabolic profiles of the control and OVA-induced asthma model groups. Moreover, the accumulation of 39 metabolites significantly differed between the Interleukin 33 (IL-33) and control groups. These differentially accumulated metabolites were mainly involved in pathways such as sphingolipid, oxidative phosphorylation, and fatty acid metabolism. This metabolomic study revealed, for the first time, the key metabolites and metabolic pathways of ILC2s, revealing new aspects of cellular metabolism in the context of airway inflammation. These findings not only contribute to unraveling the pathogenesis of asthma but also provide a crucial theoretical foundation for the future development of therapeutic strategies targeting ILC2s.

Mechanisms of Allergen Immunotherapy in Allergic Rhinitis

PURPOSE OF REVIEW

Allergic rhinitis (AR) is a chronic inflammatory immunoglobulin (Ig) E-mediated disease of the nasal mucosa that can be triggered by the inhalation of seasonal or perennial allergens. Typical symptoms include sneezing, rhinorrhea, nasal itching, nasal congestion and symptoms of allergic conjunctivitis. AR affects a quarter of the population in the United States of America and Europe.

RECENT FINDINGS

AR has been shown to reduce work productivity in 36-59% of the patients with 20% reporting deteriorated job attendance. Moreover, 42% of children with AR report reduced at-school productivity and lower grades. Most importantly, AR impacts the patient's quality of life, due to sleep deprivation. However, a proportion of patients fails to respond to conventional medication and opts for the allergen immunotherapy (AIT), which currently is the only disease-modifying therapeutic option. AIT can be administered by either subcutaneous (SCIT) or sublingual (SLIT) route. Both routes of administration are safe, effective, and can lead to tolerance lasting years after treatment cessation. Both innate and adaptive immune responses that contribute to allergic inflammation are suppressed by AIT. Innate responses are ameliorated by reducing local mast cell, basophil, eosinophil, and circulating group 2 innate lymphoid cell frequencies which is accompanied by decreased basophil sensitivity. Induction of allergen-specific blocking antibodies, immunosuppressive cytokines, and regulatory T and B cell phenotypes are key pro-tolerogenic adaptive immune responses.

CONCLUSION

A comprehensive understanding of these mechanisms is necessary for optimal selection of AIT-responsive patients and monitoring treatment efficacy. Moreover, it could inspire novel and more efficient AIT approaches.

Alzheimer's Disease Affects Severity of Asthma Through Methylation Control of Foxp3 Promoter

Recent studies suggest that severity of asthma can be modulated by neuropsychiatric conditions, while the underlying mechanisms are not clear. Here, we used ovalbumin (OVA) to induce asthma in APP/PS1 mice, a mouse model of Alzheimer's disease (AD), or in their wildtype control C57BL/6J mice. We found that all hallmarks of asthma by OVA were significantly attenuated in APP/PS1 mice, compared to age- and gender-matched C57BL/6J mice. Interestingly, significantly higher number of regulatory T cells (Treg) was detected in the APP/PS1 mouse lung, compared to those in the C57BL/6J mouse lung. Since Foxp3 is crucial for differentiation of naive T cells into Treg and is the most important marker for Treg, we examined the Foxp3 levels in the T cells from the lung of these mice. We found that the Foxp3 levels in the APP/PS1 mouse lung were significantly higher than those in the C57BL/6J mouse lung, likely resulting from reduced Foxp3 promoter methylation. Thus, our study suggests that AD may affect severity of asthma through methylation control of Foxp3 promoter in T cells.

Astragalus Oral Solution Ameliorates Allergic Asthma in Children by Regulating Relative Contents of CD4+CD25highCD127low Treg Cells

Objective: To explore the effects of Astragalus oral solution (AOS) on allergic asthma in children by investigating relative contents of CD4⁺CD25^highCD127^low Treg cells. Methods: The contents of Astragaloside A in AOS were detected by using HPLC. Eighty children with allergic asthma were recruited from February 2016 to June 2017, and randomly assigned into the control group (received placebo, 0.1% quinine chloride in deionized water, daily) and the AOS group (received 10 mL AOS daily). After 6-month treatment, therapeutic results were compared between the two groups. Serum levels of IL-10 and TGF-beta, Th1 cytokines (IL-2 and IFN-γ), and Th2 cytokines (IL-4 and IL-6) were measured by using ELISA kits. Relative contents of CD4⁺CD25^highCD127^low Treg cells were determined by using flow cytometry. Results: Astragaloside A was the main ingredient of AOS with 0.216 ± 0.027 mg/mL from six-batch samples. After 6-month therapy, the AOS group showed improved forced expiratory volume in 1 s (FEV1) and the Pediatric Asthma Quality of Life Questionnaire (PAQLQ) scores compared with the control group (P < 0.05). Serum level of IL-10 was higher and the levels of TGF-beta, Th1 cytokines (IL-2 and IFN-γ), and Th2 cytokines (IL-4 and IL-6) were lower in the AOS group than in the control group (P < 0.05). AOS treatment increased the percentage of gated CD4⁺ T cells, CD4⁺CD25⁺ T cells, CD4⁺CD25^high Treg cells, CD4⁺CD25⁺FoxP3⁺ Treg cells and CD4⁺CD25^highCD127^low Treg cells when compared with the control group (P < 0.05). Conclusions: Astragaloside A was the main component of AOS, and AOS ameliorated allergic asthma in children by regulating relative contents of CD4⁺CD25^highCD127^low Treg cells.