Immune imbalance of regulatory T/type 2 helper cells in the pathogenesis of allergic rhinitis in children

The Role of Regulatory T Cells in Allergic Diseases: Collegium Internationale Allergologicum (CIA) Update 2024

BACKGROUND

Allergy represents a major health problem of increasing prevalence worldwide with a high socioeconomic impact. Our knowledge on the molecular mechanisms underlying allergic diseases and their treatments has significantly improved over the last years. The generation of allergen-specific regulatory T cells (Tregs) is crucial in the induction of healthy immune responses to allergens, preventing the development and worsening of allergic diseases.

SUMMARY

In the last decades, intensive research has focused on the study of the molecular mechanisms involved in Treg development and Treg-mediated suppression. These mechanisms are essential for the induction of sustained tolerance by allergen-specific immunotherapy (AIT) after treatment discontinuation. Compelling experimental evidence demonstrated altered suppressive capacity of Tregs in patients suffering from allergic rhinitis, allergic asthma, food allergy, or atopic dermatitis, as well as the restoration of their numbers and functionality after successful AIT.

KEY MESSAGE

The better understanding of the molecular mechanisms involved in Treg generation during allergen tolerance induction might well contribute to the development of novel strategies for the prevention and treatment of allergic diseases.

Profiles of immune infiltration in seasonal allergic rhinitis and related genes and pathways

BACKGROUND

Seasonal allergic rhinitis (SAR) is a chronic inflammatory disease for which the molecular mechanism is unclear.

METHODS

Whole blood, CD4⁺ T cells in peripheral blood mononuclear cells (PBMCs), and CD4⁺ T cells in nasal mucosa from SAR-related datasets (GSE43497, GSE50223, and GSE49782) were downloaded from the Gene Expression Omnibus (GEO) database. Differences in SAR-associated immune cell infiltration in the PBMCs were analyzed using the CIBERSORT algorithm. Differential gene expression analysis was conducted between different groups. Gene set enrichment analysis (GSEA) was performed using the clusterProfiler package to explore functional changes in signaling pathways.

RESULTS

There was a significant increase in the proportion of CD8⁺ T cells and a significant decrease in the proportion of neutrophils in the whole blood of SAR patients after allergen challenge compared to SAR patients after diluent challenge. This pattern was also found in SAR patients compared to healthy controls (HCs) by flow cytometry. The NF-κB and Toll-like receptor signaling pathways were enriched in SAR patients following allergen challenge. The expression of CD4⁺ T cell marker genes and associated cytokines significantly differed between allergen-treated SAR patients, diluent-treated SAR patients and HCs. We also observed heightened CD4⁺ T cell related genes, cytokines and pathways activation in the nasal mucosa region of SAR patients after allergen challenge.

CONCLUSION

Our analysis revealed that T cell receptor signaling pathways, T helper 1 (Th1) /T helper 2 (Th2) cell differentiation may contribute to the development of SAR. The present study is the first bioinformatic analysis to quantify immune cell infiltration and identify underlying SAR mechanisms from combined microarray data and provides insight for further research into the molecular mechanisms of SAR.

Silencing of CD86 in dendritic cells by small interfering RNA regulates cytokine production in T cells from patients with allergic rhinitis in vitro

The aim of the present study was to investigate the expression and role of the co‑stimulatory molecule T‑lymphocyte activation antigen CD86 (CD86) in dendritic cells (DCs) from the peripheral blood of patients with allergic rhinitis (AR) compared with those from healthy individuals. It was observed that mature DCs from the peripheral blood of patients with AR expressed high levels of the co‑stimulatory molecule CD86, but not CD80, compared with healthy control subjects. CD86 expression levels in DCs decreased significantly following transfection with siRNA in a lentiviral vector. Furthermore, the level of transforming growth factor‑β1 produced by T cells co‑cultured with DCs was significantly increased in the siRNA group, while interleukin (IL)‑4 and IL‑5 production was significantly decreased. The findings of the present study indicated that CD86 may play a pivotal role in the regulatory T cell/type 2 helper T cell imbalance in allergic inflammation.

Anti-Inflammatory Effects of Cold Thermal Therapy on Allergic Skin Inflammation Induced by Trimellitic Anhydride in BALB/c Mice

Cold and hot thermal therapies are widely used as a traditional therapy in many cultures and are often prescribed in the treatment of various musculoskeletal and neurological conditions which present themselves to primary care physicians. However, there are no reports that investigated either the effects of cold and hot thermal therapies on the skin inflammation of trimellitic anhydride- (TMA-) induced dermatitis-like contact hypersensitivity (CHS) mouse model, or the mechanism of thermal therapy on allergic skin inflammation. Therefore, in this study, to reveal the anti-inflammatory effect of thermal therapy and its mechanism on TMA-induced CHS, we analyzed ear-swelling response (ear edema), vascular permeability, serum IgE levels, histological examination, and histamine and Th2 cytokine levels. Cold thermal therapy reduced the ear-swelling response, the vascular permeability, the serum IgE levels, and the infiltration of eosinophils and mast cells as well as the mast cell degranulation. To determine the mechanism by which cold thermal therapy inhibits allergic skin inflammation, detailed studies were carried out revealing that cold thermal therapy suppressed IL-4 and IL-5 secretion and mast cell activation. These results indicated that cold thermal therapy cures skin inflammation of TMA-induced CHS by decreasing Th2 cytokine release, especially IL-4 and IL-5, and mast cell activation. These data suggest that new insight into the mechanism of robust therapeutic effects of cold thermal therapy against allergic dermatitis, and cold thermal therapy may prove to be a useful therapeutic modality on allergic inflammatory diseases as traditional use as well as Th2- or mast cell-mediated allergic responses.

The role of regulatory T cells in the regulation of upper airway inflammation

Allergic rhinitis (AR) and chronic rhinosinusitis with nasal polyps (CRSwNP) are inflammatory diseases of the upper airway, with a similar immunologic profile, characterized by aberrant and persistent type 2 inflammation. One cell population that has been identified as altered in both disease types is regulatory T cell (Treg). Tregs have the capacity to modulate T-effector function and suppress inflammatory cytokine production in a broad range of cell types. Given the ability of Tregs to control inflammation, the role of Tregs in respiratory diseases has attracted much attention. As discussed in this article, alterations in the Treg numbers and function, or both, have been identified in AR and CRSwNP, although much of the data is conflicting. Here, we explored what is known and, in many cases, unknown about the mechanisms by which Tregs differentiate and function, and how these functions can be controlled in the mucosal microenvironment. By gaining a greater understanding of these processes, it may be possible to harness the natural immunosuppressive activity of Tregs to ameliorate the chronic inflammation associated with AR and CRSwNP.

Variation of Regulatory T Lymphocytes in the Peripheral Blood of Children with Allergic Rhinitis

The studies of T-regulatory (Treg) cells in the pediatric allergic disorders, especially allergic rhinitis (AR), are very few and still far from being elucidated. The aim of this study is to assess the frequencies of CD4⁺CD25⁺Foxp3⁺ (CD4⁺Tregs) and CD8⁺CD25^+highFoxp3⁺ (CD8⁺Tregs) regulatory T lymphocytes in the peripheral blood of children with AR. In fresh whole blood of 60 children with AR and 40 healthy controls, the frequencies of CD4⁺Tregs and CD8⁺Tregs were examined by flow cytometry. The total IgE concentration in the serum was measured. In AR children, the frequencies of CD4⁺Tregs and CD8⁺Tregs were significantly reduced when compared to control group (p = 0.041, p = 0.011, respectively). Moreover, the expressions of Foxp3⁺ in CD4⁺CD25^+high and CD8⁺CD25^+high cells were significantly lower in patient group than controls. We found a significant negative correlation between the frequencies of CD4⁺Tregs and the total IgE concentration (p < 0.01). In conclusion, the present study demonstrated that the percentages of CD8⁺Tregs and CD4⁺Tregs T cells were significantly decreased in children with AR. This suggests that decreased Treg cells might represent a defect in the compartment of T-cell population in children with AR. Further studies are warranted to fully appreciate the clinical relevance of Tregs in children with AR.

Aeroallergens in Canada: Distribution, Public Health Impacts, and Opportunities for Prevention

Aeroallergens occur naturally in the environment and are widely dispersed across Canada, yet their public health implications are not well-understood. This review intends to provide a scientific and public health-oriented perspective on aeroallergens in Canada: their distribution, health impacts, and new developments including the effects of climate change and the potential role of aeroallergens in the development of allergies and asthma. The review also describes anthropogenic effects on plant distribution and diversity, and how aeroallergens interact with other environmental elements, such as air pollution and weather events. Increased understanding of the relationships between aeroallergens and health will enhance our ability to provide accurate information, improve preventive measures and provide timely treatments for affected populations.

Tear osteopontin level and its relationship with local Th1/Th2/Th17/Treg cytokines in children with allergic conjunctivitis

BACKGROUND

Allergic conjunctivitis (AC) is one of the most common allergic ocular diseases worldwide. Osteopontin (OPN), as a recently described Th2 inflammation related protein, may play a role in the pathogenesis of AC. The aim of this study was to identify the expression of OPN in children with AC.

METHODS

Eighty AC children (seasonal and perennial AC) and twenty controls were enrolled in this study. Serum and tears of different time points (during and out of the pollen season) were collected and used for enzyme-linked immunosorbent assay (ELISA) of OPN and T-help cell related cytokines, respectively. The relationship between serum and tears OPN and Th1/2/17Treg related cytokines as well as disease severity were analysed.

RESULTS

Our results showed that expression of tear OPN protein by perennial AC patients increased significantly compared with controls or seasonal AC patients out of the pollen season. Tear OPN expression was positively related to local Th2/17 cytokines and negatively related to IL-10 and TGF-β expression. The tear OPN expression was also significantly related to disease severity.

CONCLUSION

Tear OPN reflects the local clinical status of ocular allergy and might play an important pathophysiological role in local Th2/17/Treg inflammation in children with AC.

Skullcapflavone II attenuates ovalbumin-induced allergic rhinitis through the blocking of Th2 cytokine production and mast cell histamine release

Allergic rhinitis is a common heterogeneous chronic upper airway disorder and is an IgE-mediated inflammation characterized by one or more nasal symptoms such as sneezing, itching, nasal discharge, rhinorrhea, post nasal drainage and nasal blockage. In the present study, the effects of skullcapflavone II (SCFII) on upper airway inflammation, Th2 cytokines, and NF-κB signaling in an ovalbumin (OVA)-induced allergic rhinitis (AR) murine model in vivo were investigated. OVA-induced AR mice increased nasal symptoms, eosinophils and mast cells infiltration into nasal cavity, OVA-specific IgE/IgG1 and histamine in serum, Th2 cytokines including IL-13 and GATA3, and NF-κB signaling in NALF and lung homogenate. Interestingly, treatment of SCFII reduced the levels of OVA-specific IgE/IgG1 and histamine in serum, of Th2 cytokines and of NF-κB signaling in the NALF and the lung homogenate, and histopathological changes in the nasal tissue and the lung. Also, dexamethasone suppressed such increases. The results of this study suggested that SCFII may ameliorate allergic inflammation of upper airway in AR mice model by blocking the Th2 cytokine production, the NF-κB signal pathway and the mast cell histamine release. Taken together, we suggest that SCFII may be used as a therapeutic agent for patients with Th2-mediated or mast cell-mediated allergic diseases.