Allergic TH2 Response Governed by B-Cell Lymphoma 6 Function in Naturally Occurring Memory Phenotype CD4+ T Cells

Allergen-specific B cell responses in oral immunotherapy-induced desensitization, remission, and natural outgrowth in cow's milk allergy

BACKGROUND

Antigen-specific memory B cells play a key role in the induction of desensitization and remission to food allergens in oral immunotherapy and in the development of natural tolerance (NT). Here, we characterized milk allergen Bos d 9-specific B cells in oral allergen-specific immunotherapy (OIT) and in children spontaneously outgrowing cow's milk allergy (CMA) due to NT.

METHODS

Samples from children with CMA who received oral OIT (before, during, and after), children who naturally outgrew CMA (NT), and healthy individuals were received from Stanford biobank. Bos d 9-specific B cells were isolated by flow cytometry and RNA-sequencing was performed. Protein profile of Bos d 9-specific B cells was analyzed by proximity extension assay.

RESULTS

Increased frequencies of circulating milk allergen Bos d 9-specific B cells were observed after OIT and NT. Milk-desensitized subjects showed the partial acquisition of phenotypic features of remission, suggesting that desensitization is an earlier stage of remission. Within these most significantly expressed genes, IL10RA and TGFB3 were highly expressed in desensitized OIT patients. In both the remission and desensitized groups, B cell activation-, Breg cells-, BCR-signaling-, and differentiation-related genes were upregulated. In NT, pathways associated with innate immunity characteristics, development of marginal zone B cells, and a more established suppressor function of B cells prevail that may play a role in long-term tolerance. The analyses of immunoglobulin heavy chain genes in specific B cells demonstrated that IgG2 in desensitization, IgG1, IgA1, IgA2, IgG4, and IgD in remission, and IgD in NT were predominating. Secreted proteins from allergen-specific B cells revealed higher levels of regulatory cytokines, IL-10, and TGF-β after OIT and NT.

CONCLUSION

Allergen-specific B cells are essential elements in regulating food allergy towards remission in OIT-received and naturally resolved individuals.

Changes of allergic inflammation and immunological parameters after Alt a 1 and A. alternata immunotherapy in mice

Background

The efficacy of allergen-specific subcutaneousimmunotherapy (SCIT) with Alt a 1 of the fungus A. alternata is still unknown. Yet, few studies compare the therapeutic effects and immunological mechanisms of Alt a 1 and A. alternata extracts. We aim to explore and compare the changes in allergic inflammation and immunological mechanisms of Alt a 1 and A. alternata in mice.

Methods

Female BALB/c mice administrated recombinant Alt a 1 (rAlt a 1), native Alt a 1 (nAlt a 1), and A. alternata. Lung histology, airway hyper-reactivity (AHR), bronchoalveolar lavage fluid (BALF) cytokine levels, serum immunoglobulin responses, the expression of Bcl-6, the percentages of T follicular helper cells (Tfh), cytokine-related Tfh subtypes, regulatory B cells (Breg), and IL-10+ Breg cells were detected.

Results

High-purity nAlt 1 protein was obtained. SCIT with Alt a 1 and Alternaria decreased airway and lung inflammation, including improvement of lung pathology, lower levels of AHR, reduction of total cell numbers, and IL-4 and IL-13 levels in BALF. Furthermore, Alt a 1-SCIT effectively suppressed the IgE responses, elevated IgG titers, and was superior in decreasing the expression of Bcl-6. Additionally, Alternaria-SCIT significantly decreased the expression of Tfh cells, L-4+ Tfh, and IL-5+ Tfh cells in the spleen, whereas Alt a 1 showed superior therapeutic effects in the lymph node. IL-13+ Tfh cells in these two treatment groups not being significant. IL-17A+ Tfh cells were alleviated most effectively after A. alternata-SCIT in both the spleen and lymph node. Intriguingly, IL-10+ Breg cells decreased remarkably in response to SCIT with rAlt a 1.

Conclusions

Treatments with Alt a 1 and A. alternata extracts had beneficial effects on allergic inflammation. Alt a 1-SCIT resulted in prominent improvement in the immunoglobulin responses, Bcl-6, and IL-10+ Breg cells. Alternaria-SCIT was more likely to suppress the expression of Tfh and cytokine-related Tfh subtypes.

Correlation between B-cell lymphoma 6 with the balance of T helper-1/2 and severity of allergic rhinitis

OBJECTIVE

Allergic rhinitis (AR) is a prevailing immune disorder affecting the nasal mucosa. B-cell lymphoma 6 (BCL6) imposes essential roles in immunity. This study probed into the serum expression of BCL6 and its effect on AR diagnosis and patients' quality of life (QOL).

METHODS

A total of 113 patients with AR including 38 cases with mild AR (MAR) and 75 cases with moderate-severe AR (MSAR) were enrolled, with 101 healthy people enrolled as control. Serum expression of BCL6 was detected by RT-qPCR and the diagnostic efficacy of BCL6 for AR was analyzed using the receiver operating characteristic curve. The proportion of T helper-1/2 (Th1/Th2) cells in CD4+ T cells in peripheral blood mononuclear cells was detected using flow cytometry. The correlation between BCL6 and Th1/Th2 cells and the effects of BCL6 expression on patients' QOL were assessed by Pearson analysis and Mini-RQLQ questionnaire.

RESULTS

BCL6 was downregulated in patients with AR, serum BCL6 level < 0.8450 had certain auxiliary diagnostic values for AR, and serum BCL6 level < 0.5400 could assist the diagnosis of AR severity. Th1 cell proportion in CD4+ T cells was decreased, whereas Th2 cell proportion was increased with AR severity. BCL6 was positively-linked with Th1 cells but inversely-correlated with Th2 cells in patients with AR. Patients with AR with low BCL6 expression had a poorer QOL compared with high BCL6 expression. The domains most affected by BCL6 expression were practical problems, nasal symptoms, and lacrimation.

CONCLUSION

Serum BCL6 is downregulated and low BCL6 expression greatly deteriorates QOL in patients with AR.

Critical Roles of Balanced T Helper 9 Cells and Regulatory T Cells in Allergic Airway Inflammation and Tumor Immunity

CD4⁺T helper (Th) cells are important mediators of immune responses in asthma and cancer. When counteracted by different classes of pathogens, naïve CD4⁺T cells undergo programmed differentiation into distinct types of Th cells. Th cells orchestrate antigen-specific immune responses upon their clonal T-cell receptor (TCR) interaction with the appropriate peptide antigen presented on MHC class II molecules expressed by antigen-presenting cells (APCs). T helper 9 (Th9) cells and regulatory T (Treg) cells and their corresponding cytokines have critical roles in tumor and allergic immunity. In the context of asthma and cancer, the dynamic internal microenvironment, along with chronic inflammatory stimuli, influences development, differentiation, and function of Th9 cells and Treg cells. Furthermore, the dysregulation of the balance between Th9 cells and Treg cells might trigger aberrant immune responses, resulting in development and exacerbation of asthma and cancer. In this review, the development, differentiation, and function of Th9 cells and Treg cells, which are synergistically regulated by various factors including cytokine signals, transcriptional factors (TFs), costimulatory signals, microenvironment cues, metabolic pathways, and different signal pathways, will be discussed. In addition, we focus on the recent progress that has helped to achieve a better understanding of the roles of Th9 cells and Treg cells in allergic airway inflammation and tumor immunity. We also discuss how various factors moderate their responses in asthma and cancer. Finally, we summarize the recent findings regarding potential mechanisms for regulating the balance between Th9 and Treg cells in asthma and cancer. These advances provide opportunities for novel therapeutic strategies that are aimed at reestablishing the balance of these cells in the diseases.