Phenotypic and functional alterations of regulatory B cell subsets in adult allergic asthma patients

The Role of Regulatory B Lymphocytes in Allergic Diseases

PURPOSE OF REVIEW

Regulatory B cells (Bregs) are a key component in the regulation of the immune system. Their immunosuppressive function, which includes limiting the inflammatory cascade, occurs through interactions with other immune cells and the secretion of cytokines, primarily IL-10. As knowledge about B cells continues to expand, their diversity is becoming more recognized, with many subpopulations identified in both human and animal models. However, identifying specific transcription factors or markers that could definitively distinguish regulatory B cells remains a challenge. This review summarizes recent findings on the role of B regulatory cells in allergic diseases.

RECENT FINDINGS

In patients with bronchial asthma, atopic dermatitis, and food allergies, the number of regulatory B cells is reduced, and disease severity is inversely proportional to the quantity of these cells. Furthermore, in patients with atopic dermatitis, the ability of regulatory B cells to produce IL-10 in response to IL-6 stimulation is diminished. However, allergen immunotherapy has been shown to induce the formation of regulatory T cells as well as regulatory B cells.

SUMMARY

The success of future therapies based on B cells may depend on deepening our current understanding of their phenotypes, induction, differentiation, and function. Research in these areas is essential for understanding the mechanisms regulating Breg activity and for developing potential targeted therapies in the treatment of allergic diseases.

IL-35 promotes IL-35+IL-10+ Bregs and Conventional LAG3+ Tregs in the lung tissue of OVA-Induced Asthmatic Mice

AIMS

This study aimed to investigate the effect of interleukin-35 (IL-35) on inflamed lung tissue in a murine model of asthma. IL-35 was examined for its potential to induce regulatory lymphocytes during ovalbumin (OVA)-induced acute lung injury.

METHODS

Female BALB/c mice sensitized with OVA and were treated with recombinant IL-35 (rIL-35) via intranasal or intraperitoneal routes and were administered 4 h before OVA challenge. The effects of rIL-35 treatment on the lung and blood levels of regulatory B cells (Bregs) and regulatory T cells (Tregs), as well as their production of immunosuppressive cytokines, were determined using flow cytometry and enzyme-linked immunosorbent assay (ELISA), respectively.

RESULTS

Treatment of OVA-sensitized asthmatic mice with rIL-35, whether administered intranasally or intraperitoneally, resulted in reduced lung inflammation and injury. This reduction was accompanied by an increase in the frequency of IL-35 producing Bregs, IL-35 and IL-10 producing Bregs, and conventional LAG3+ Tregs in the lung tissues and blood. This increase was more pronounced with intranasal rIL-35. Furthermore, there was a positive correlation between the levels of these regulatory cells and lung gene expression of IL-35 and IL-10, and an inverse correlation with both lung gene expression and plasma level of IL-17.

CONCLUSIONS

The results of this study suggest that IL-35, through its ability to increase Bregs and Tregs, is effective in reversing lung inflammation in the context of asthma. Since the increase was more pronounced with intranasal administration, this highlights the therapeutic potential of its local intrapulmonary application in managing asthma-related inflammation.

The current understanding of the phenotypic and functional properties of human regulatory B cells (Bregs)

B cells can have a wide range of pro- and anti- inflammatory functions. A subset of B cells called regulatory B cells (Bregs) can potently suppress immune responses. Bregs have been shown to maintain immune homeostasis and modulate inflammatory responses. Bregs are an exciting cellular target across a range of diseases, including Breg induction in autoimmunity, allergy and transplantation, and Breg suppression in cancers and infection. Bregs exhibit a remarkable phenotypic heterogeneity, rendering their unequivocal identification a challenging task. The lack of a universally accepted and exclusive surface marker set for Bregs across various studies contributes to inconsistencies in their categorization. This review paper presents a comprehensive overview of the current understanding of the phenotypic and functional properties of human Bregs while addressing the persisting ambiguities and discrepancies in their characterization. Finally, the paper examines the promising therapeutic opportunities presented by Bregs as their immunomodulatory capacities have gained attention in the context of autoimmune diseases, allergic conditions, and cancer. We explore the exciting potential in harnessing Bregs as potential therapeutic agents and the avenues that remain open for the development of Breg-based treatment strategies.

Human Ascaris infection is associated with higher frequencies of IL-10 producing B cells

INTRODUCTION

Ascaris lumbricoides has dual effects on the immune system of infected hosts. The IgE response to this parasite has been thoroughly studied, but little is known about cellular responses induced by infection. This study aims to explore the interplay between A. lumbricoides infection and B cell responses, especially B regulatory cells.

METHODS

Participants from Santa Catalina, Bolívar, Colombia, a helminth-endemic town, were screened for soil-transmitted helminthiasis (STH) using stool examinations. Eighteen A. lumbricoides-infected and 11 non-infected subjects were selected. Blood samples were analyzed for Breg cells and related cytokines, and immunoglobulins specific to the A. lumbricoides excretory/secretory product, ABA-1.

RESULTS

Infected subjects exhibited higher frequencies of Breg cells, especially those with a higher A. lumbricoides egg burden. Higher frequencies of different Breg subsets were observed in infected individuals, with CD25+CD71+CD73- B cells being notably increased in strongly infected individuals. Additionally, A. lumbricoides infection was associated with reduced levels of circulating ABA-1-specific IgG1 and IgE. IL-10+ B cell frequencies correlated inversely with ABA-1-specific IgE.

CONCLUSIONS

A. lumbricoides infection has a significant impact on the immune response, particularly on Breg cell populations and antibody responses. Our findings suggest that A. lumbricoides infection mediates a dose-dependent immunosuppressive response characterized by an increase in Breg cells and concomitant suppression of ABA-1-specific humoral responses.

Dietary Polyphenols, Plant Metabolites, and Allergic Disorders: A Comprehensive Review

Given the ongoing rise in the occurrence of allergic disorders, alterations in dietary patterns have been proposed as a possible factor contributing to the emergence and progression of these conditions. Currently, there is a significant focus on the development of dietary therapies that utilize natural compounds possessing anti-allergy properties. Dietary polyphenols and plant metabolites have been intensively researched due to their well-documented anti-inflammatory, antioxidant, and immunomodulatory characteristics, making them one of the most prominent natural bioactive chemicals. This study seeks to discuss the in-depth mechanisms by which these molecules may exert anti-allergic effects, namely through their capacity to diminish the allergenicity of proteins, modulate immune responses, and modify the composition of the gut microbiota. However, further investigation is required to fully understand these effects. This paper examines the existing evidence from experimental and clinical studies that supports the idea that different polyphenols, such as catechins, resveratrol, curcumin, quercetin, and others, can reduce allergic inflammation, relieve symptoms of food allergy, asthma, atopic dermatitis, and allergic rhinitis, and prevent the progression of the allergic immune response. In summary, dietary polyphenols and plant metabolites possess significant anti-allergic properties and can be utilized for developing both preventative and therapeutic strategies for targeting allergic conditions. The paper also discusses the constraints in investigating and broad usage of polyphenols, as well as potential avenues for future research.

Regulatory B Cells-Immunopathological and Prognostic Potential in Humans

The aim of the following review is to shed light on the putative role of regulatory B cells (Bregs) in various human diseases and highlight their potential prognostic and therapeutic relevance in humans. Regulatory B cells are a heterogeneous group of B lymphocytes capable of suppressing inflammatory immune reactions. In this way, Bregs contribute to the maintenance of tolerance and immune homeostasis by limiting ongoing immune reactions temporally and spatially. Bregs play an important role in attenuating pathological inflammatory reactions that can be associated with transplant rejection, graft-versus-host disease, autoimmune diseases and allergies but also with infectious, neoplastic and metabolic diseases. Early studies of Bregs identified IL-10 as an important functional molecule, so the IL-10-secreting murine B10 cell is still considered a prototype Breg, and IL-10 has long been central to the search for human Breg equivalents. However, over the past two decades, other molecules that may contribute to the immunosuppressive function of Bregs have been discovered, some of which are only present in human Bregs. This expanded arsenal includes several anti-inflammatory cytokines, such as IL-35 and TGF-β, but also enzymes such as CD39/CD73, granzyme B and IDO as well as cell surface proteins including PD-L1, CD1d and CD25. In summary, the present review illustrates in a concise and comprehensive manner that although human Bregs share common functional immunosuppressive features leading to a prominent role in various human immunpathologies, they are composed of a pool of different B cell types with rather heterogeneous phenotypic and transcriptional properties.

The role of regulatory B cells in immune regulation and childhood allergic asthma

BACKGROUND

As the most common chronic disease in childhood, asthma displays a major public health problem worldwide with the incidence of those affected rising. As there is currently no cure for allergic asthma, it is mandatory to get a better understanding of the underlying molecular mechanism.

MAIN BODY

By producing IgE antibodies upon allergen contact, B cells play a pivotal role in allergic asthma. Besides that, IL-10-secreting B cell subsets, namely regulatory B cells (Bregs), are reported in mice and humans to play a role in allergic asthma. In humans, several Breg subsets with distinct phenotypic and functional properties are identified among B cells at different maturational and differentiation stages that exert anti-inflammatory functions by expressing several suppressor molecules. Emerging research has focused on the role of Bregs in allergic asthma as well as their role for future diagnostic and preventive strategies.

CONCLUSION

Knowledge about the exact function of human Bregs in allergic asthma is still very limited. This review aims to summarize the current knowledge on Bregs. We discuss different human Breg subsets, several ways of Breg induction as well as the mechanisms through which they exert immunoregulatory functions, and their role in (childhood) allergic asthma.

Parameters of TNF receptor co-expression in allergic and autoimmune processes: Differences and diagnostic significance

The authors used a method quantitative estimation density of TNFR1/TNFR2 on cells by flow cytometry with calibration particles, which allowed them to estimate the absolute number of receptors on cells regardless of the type of flow cytometer. The TNF receptor expression parameters were used to determine their association with the fact of disease and to build diagnostic models. The proposed methodological approach using a combination of flow cytometry and mathematical modeling techniques represents a promising direction for testing the diagnostic and prognostic significance of the studied biomarkers. The multifactorial regression analysis constructed on the basis of this approach made it possible to refine and supplement diagnostic schemes for determining the probability of rheumatoid arthritis and bronchial asthma in patients.

The Role of Diet and Nutrition in Allergic Diseases

Allergic diseases are a set of chronic inflammatory disorders of lung, skin, and nose epithelium characterized by aberrant IgE and Th2 cytokine-mediated immune responses to exposed allergens. The prevalence of allergic diseases, including asthma, allergic rhinitis, and atopic dermatitis, has increased dramatically worldwide in the past several decades. Evidence suggests that diet and nutrition play a key role in the development and severity of allergic diseases. Dietary components can differentially regulate allergic inflammation pathways through host and gut microbiota-derived metabolites, therefore influencing allergy outcomes in positive or negative ways. A broad range of nutrients and dietary components (vitamins A, D, and E, minerals Zn, Iron, and Se, dietary fiber, fatty acids, and phytochemicals) are found to be effective in the prevention or treatment of allergic diseases through the suppression of type 2 inflammation. This paper aims to review recent advances in the role of diet and nutrition in the etiology of allergies, nutritional regulation of allergic inflammation, and clinical findings about nutrient supplementation in treating allergic diseases. The current literature suggests the potential efficacy of plant-based diets in reducing allergic symptoms. Further clinical trials are warranted to examine the potential beneficial effects of plant-based diets and anti-allergic nutrients in the prevention and management of allergic diseases.

IL-10-producing memory B regulatory cells as a novel target for HLA-G to prolong human kidney allograft survival

Despite the growing interest in the role of regulatory B cells (Bregs) in autoimmunity, their distinct role and function in kidney transplant outcomes remain elusive. Here, we retrospectively analyzed the proportion of Bregs, transitional Bregs (tBregs) and memory Bregs (mBregs) and their capacity to produce IL-10 in non-rejected (NR) versus rejected (RJ) kidney transplant recipients. In the NR group, we observed a significant increase in the proportion of mBregs (CD19⁺CD24^hiCD27⁺) but no difference in tBregs (CD19⁺CD24^hiCD38⁺), as compared to the RJ group. We also observed a significant increase in IL-10-producing mBregs (CD19⁺CD24^hiCD27⁺IL-10⁺) in the NR group. As our group and others have previously reported a potential role of the human leukocyte antigen G (HLA-G) in human renal allograft survival, notably through IL-10, we then investigated possible crosstalk between HLA-G and IL-10⁺ mBregs. Our ex vivo data suggest a role of HLA-G in enhancing IL-10⁺ mBreg expansion upon stimulation, which further decreased CD3⁺ T cell proliferation capability. Using RNA-sequencing (RNA-seq), we identified potential key signaling pathways involved in HLA-G-driven IL-10⁺ mBreg expansion, such as the MAPK, TNF and chemokine signaling pathways. Together, our study highlights a novel HLA-G-mediated IL-10-producing mBreg pathway that may serve as a therapeutic target to improve kidney allograft survival.

Exploring proteomic plasma biomarkers in eosinophilic and neutrophilic asthma

BACKGROUND

Few biomarkers identify eosinophilic and neutrophilic asthma beyond cell concentrations in blood or sputum. Finding novel biomarkers for asthma endotypes could give insight about disease mechanisms and guide tailored treatment. Our aim was to investigate clinical characteristics and inflammation-related plasma proteins in relation to blood eosinophil and neutrophil concentrations in subjects with and without asthma.

METHODS

We included 24-26-year-old subjects (n = 2063) from the Swedish population-based cohort BAMSE. Subjects with asthma (n = 239) and without asthma (n = 1824) were subdivided based on blood eosinophil and neutrophil concentrations (cut-offs 0.3 × 10⁹ /L and 5.0 × 10⁹ /L, respectively). We measured the levels of 92 plasma proteins using Olink Proseek Multiplex Inflammation Panel Assay. Group statistics tests were used to analyse the data, as well as adjusted multiple logistic regression models.

RESULTS

Among subjects with asthma, 21.8% had eosinophilic asthma and 20.5% neutrophilic asthma. Eosinophilic asthma, but not neutrophilic asthma, was associated with a distinct clinical phenotype with, for example, higher proportions of eczema and sensitization. Most plasma proteins that associated with high eosinophil and/or neutrophil blood concentrations in subjects with asthma showed similar associations in subjects without asthma. However, out of these proteins, MMP10 levels were associated with eosinophilic asthma and were significantly higher as compared to controls with high eosinophilic concentration, while CCL4 levels associated with high neutrophil concentration only in subjects with asthma.

CONCLUSIONS

Eosinophilic asthma was associated with a clear clinical phenotype. With our definitions, we identified MMP10 as a possible plasma biomarker for eosinophilic asthma and CCL4 was linked to neutrophilic asthma. These proteins should be evaluated further in clinical settings and using sputum granulocytes to define the asthma endotypes.

IgA-producing B cells in lung homeostasis and disease

Immunoglobulin A (IgA) is the most abundant Ig in mucosae where it plays key roles in host defense against pathogens and in mucosal immunoregulation. Whereas intense research has established the different roles of secretory IgA in the gut, its function has been much less studied in the lung. This review will first summarize the state-of-the-art knowledge on the distribution and phenotype of IgA⁺ B cells in the human lung in both homeostasis and disease. Second, it will analyze the studies looking at cellular and molecular mechanisms of homing and priming of IgA⁺ B cells in the lung, notably following immunization. Lastly, published data on observations related to IgA and IgA⁺ B cells in lung and airway disease such as asthma, cystic fibrosis, idiopathic pulmonary fibrosis, or chronic rhinosinusitis, will be discussed. Collectively it provides the state-of-the-art of our current understanding of the biology of IgA-producing cells in the airways and identifies gaps that future research should address in order to improve mucosal protection against lung infections and chronic inflammatory diseases.

Clostridium leptum induces the generation of interleukin-10+ regulatory B cells to alleviate airway inflammation in asthma

BACKGROUND AND OBJECTIVE

Asthma is one of the most common chronic inflammatory diseases of the respiratory tract. Previous studies have shown that the reduction of regulatory B cells (Bregs) can increase inflammation of the body and promote the formation of chronic airway inflammation in asthma, but the detailed mechanisms have not been fully elucidated. The intestinal flora Clostridium leptum (CL) has been reported to modulate immune regulatory cells in the body, but the specific mechanisms are not clear. This study aimed to investigate the effects of CL on the differentiation of interleukin (IL)- 10⁺ Bregs and the regulation of the asthmatic inflammation-associated immune network.

METHODS

The abundances of CL and the frequencies of blood Bregs from asthmatic patients and healthy controls were compared. The house dust mite (HDM)-induced asthma model was established in mice. The effects of CL exposure and B cell infusion on Breg differentiation, T cell cytokine production, and inflammatory cell infiltration in mouse lungs were examined. Bregs were cocultured with regulatory T cells (Tregs) and CD4⁺ non-Tregs to evaluate their roles on Foxp3 expression and T cell differentiation, respectively.

RESULTS

Compared with healthy controls, asthmatic patients had significantly reduced frequencies of blood Bregs and abundances of fecal CL, and these two parameters were positively correlated. In the asthma model, the frequencies of Bregs in lungs were significantly reduced; while the infusion of Bregs isolated from CL- supplemented mice significantly reduced airway inflammation and hyperresponsiveness. In addition, Bregs inhibited the differentiation of cocultured non-Tregs into multiple effector cells and enhanced Foxp3 expression in cocultured Tregs.

CONCLUSION

Bregs contribute to the alleviation of airway inflammation, which provides insight on implementing CL-based microbial induction of Bregs in asthma therapy.

Glutaminolysis is required in maintaining immune regulatory functions in B cells

IL-10-expressing regulatory B cells (B10 cells) are dysfunctional in patients with many immune disorders. The underlying mechanism remains to be further elucidated. Glutamine is an essential nutrient for cell metabolism. This study aims to elucidate the role of glutaminolysis in maintaining the immune regulatory capacity in B10 cells. Peripheral blood samples were collected from 50 patients with allergic rhinitis and 50 healthy control subjects. B cells were isolated from blood samples by cell sorting with flow cytometry. The role of glutaminolysis in regulating B10 cell activities was assessed by immunological and biochemical approaches. The results showed that B cells from patients with allergic rhinitis expressed low levels of the transporter of glutamine and neutral amino acid. Glutaminolysis was required in the IL-10 expression in B cells. The glutamine catabolism was required in B10 cell generation. The mTOR activation mediated the glutaminolysis-associated B10 cell induction, and the suppression of the B cell glycogen synthase kinase-3 (GSK3) activation. GSK3 activation suppressed IL-10 expression in B cells. Inhibition of GSK3 enhanced IL-10 expression in B cells and alleviated experimental allergic rhinitis by generating immune competent type 1 regulatory T cells.

Molecular allergology approach to allergic asthma

Allergic asthma is a frequently encountered and well described asthma phenotype. However, its precise mechanisms are less known. The tools for targeted selection of patients for an optimal response to intervention (prevention or treatment) are also lacking. Here we explore the potential of the molecular allergology approach to achieve a better understanding of allergic asthma mechanisms, a precise diagnosis and an optimal management of these patients.

Regulatory B cells, A to Z

B cells play a central role in the immune system through the production of antibodies. During the past two decades, it has become increasingly clear that B cells also have the capacity to regulate immune responses through mechanisms that extend beyond antibody production. Several types of human and murine regulatory B cells have been reported that suppress inflammatory responses in autoimmune disease, allergy, infection, transplantation, and cancer. Key suppressive molecules associated with regulatory B-cell function include the cytokines IL-10, IL-35, and TGF-β as well as cell membrane-bound molecules such as programmed death-ligand 1, CD39, CD73, and aryl hydrocarbon receptor. Regulatory B cells can be induced by a range of different stimuli, including microbial products such as TLR4 or TLR9 ligands, inflammatory cytokines such as IL-6, IL-1β, and IFN-α, as well as CD40 ligation. This review provides an overview of our current knowledge on regulatory B cells. We discuss different types of regulatory B cells, the mechanisms through which they exert their regulatory functions, factors that lead to induction of regulatory B cells and their role in the alteration of inflammatory responses in different diseases.

Developments allergy in 2019 through the eyes of Clinical and Experimental Allergy, Part II clinical allergy

In the second of two linked articles, we describe the development in clinical as described by Clinical & Experimental Allergy and other journals in 2019. Epidemiology, clinical allergy, asthma and rhinitis are all covered. In this article, we described the development in the field of allergy as described by Clinical and Experimental Allergy in 2019. Epidemiology, clinical allergy, asthma and rhinitis are all covered.

Flow Cytometry: From Experimental Design to Its Application in the Diagnosis and Monitoring of Respiratory Diseases

Recent advances in the field of flow cytometry (FCM) have highlighted the importance of incorporating it as a basic analysis tool in laboratories. FCM not only allows the identification of cell subpopulations by detecting the expression of molecules in the cell membrane or cytoplasm, but it can also quantify and identify soluble molecules. The proper functioning of the FCM requires six fundamental systems, from those related to the transport of events to the systems dedicated to the analysis of information. In this review, we have identified the main considerations that every FCM user must know for an optimal antibody panel design, the quality systems that must govern the FCM protocols to guarantee reproducible results in research or clinical laboratories. Finally, we have introduced the current evidence that highlights the relevance of FCM in the investigation and clinical diagnosis of respiratory diseases, establishing important advances in the basic and clinical study of diseases as old as Tuberculosis along with the recent proposals for the monitoring and classification of patients infected with the new SARS-CoV2 virus.