Potential of immunoglobulin A to prevent allergic asthma

CD11c+ dendritic cells PlexinD1 deficiency exacerbates airway hyperresponsiveness, IgE and mucus production in a mouse model of allergic asthma

Dendritic cells (DCs) are pivotal in regulating allergic asthma. Our research has shown that the absence of Sema3E worsens asthma symptoms in acute and chronic asthma models. However, the specific role of PlexinD1 in these processes, particularly in DCs, remains unclear. This study investigates the role of PlexinD1 in CD11c+ DCs using a house dust mite (HDM) model of asthma. We generated CD11c+ DC-specific PlexinD1 knockout (CD11cPLXND1 KO) mice and subjected them, alongside wild-type controls (PLXND1fl/fl), to an HDM allergen protocol. Airway hyperresponsiveness (AHR) was measured using FlexiVent, and immune cell populations were analyzed via flow cytometry. Cytokine levels and immunoglobulin concentrations were assessed using mesoscale and ELISA, while collagen deposition and mucus production were examined through Sirius-red and periodic acid Schiff (PAS) staining respectively. Our results indicate that CD11cPLXND1 KO mice exhibit significantly exacerbated AHR, characterized by increased airway resistance and tissue elastance. Enhanced mucus production and collagen gene expression were observed in these mice compared to wild-type counterparts. Flow cytometry revealed higher CD11c+ MHCIIhigh CD11b+ cell recruitment into the lungs, and elevated total and HDM-specific serum IgE levels in CD11cPLXND1 KO mice. Mechanistically, co-cultures of B cells with DCs from CD11cPLXND1 KO mice showed significantly increased IgE production compared to wild-type mice.These findings highlight the critical regulatory role of the plexinD1 signaling pathway in CD11c+ DCs in modulating asthma features.

Exploring the Impact of Extra Virgin Olive Oil on Maternal Immune System and Breast Milk Composition in Rats

Maternal breast milk plays a key role in providing newborns with passive immunity and stimulating the maturation of an infant's immune system, protecting them from many diseases. It is known that diet can influence the immune system of lactating mothers and the composition of their breast milk. The aim of this study was to establish if a supplementation during the gestation and lactation of Lewis rats with extra virgin olive oil (EVOO), due to the high proportion of antioxidant components in its composition, has an impact on the mother's immune system and on the breast milk's immune composition. For this, 10 mL/kg of either EVOO, refined oil (control oil) or water (REF group) were orally administered once a day to rats during gestation and lactation periods. Immunoglobulin (Ig) concentrations and gene expressions of immune molecules were quantified in several compartments of the mothers. The EVOO group showed higher IgA levels in both the breast milk and the mammary glands than the REF group. In addition, the gene expression of IgA in mammary glands was also boosted by EVOO consumption. Overall, EVOO supplementation during gestation and lactation is safe and does not negatively affect the mother's immune system while improving breast milk immune composition by increasing the presence of IgA, which could be critical for an offspring's immune health.

Exopolysaccharide from Lacticaseibacillus rhamnosus induces IgA production in airways and alleviates allergic airway inflammation in mouse model

The currently observed high prevalence of allergic diseases has been associated with changes in microbial exposure in industrialized countries. Defined bacterial components represent a new strategy for modulating the allergic immune response. We show that intranasal administration of exopolysaccharide (EPS) isolated from Lacticaseibacillus (L.) rhamnosus LOCK900 induces TGF-β1, IgA, and regulatory FoxP3+ T-cells in the lungs of naïve mice. Using the ovalbumin mouse model, we demonstrate that intranasal administration of EPS downregulates the development of allergic airway inflammation and the Th2 cytokine response in sensitized individuals. At the same time, EPS treatment of sensitized mice, similar to EPS-induced responses in naïve mice, significantly increased the level of total, OVA-specific, and also bacteria-specific IgA in bronchoalveolar lavage and the number of IgA-producing B-cells in the lung tissue of these mice. Thus, EPS derived from L. rhamnosus LOCK900 can be considered a safe candidate for preventing the development of allergic symptoms in the lungs of sensitized individuals upon exposure to an allergen.

Effects on neonatal immunoglobulin concentrations by infant mode of delivery in the upstate KIDS study (2008-2010)

PROBLEM

Previous studies document an association between mode of delivery (MOD) and allergic conditions in children. Immunoglobulin (Ig) concentrations at birth may play a role. The goal of this study is to assess the impact of MOD on Ig concentrations at delivery from newborn dried blood spots (DBS).

METHOD OF STUDY

The Upstate KIDS Study (2008-2010) is a prospective cohort of mother-child pairs recruited from New York State, excluding New York City. Ig subtypes IgA, IgE, IgG1 , IgG2 , IgG3 , IgG4 , and IgM were measured in residual NDBS from the Newborn Screening Program (N = 3274 infants). MOD was categorized as vaginal delivery (VD), emergency cesarean delivery (ECD) or planned cesarean delivery (PCD). Associations between MOD and Ig levels were assessed using ANOVA and multiple regression, with models adjusted for gestational age, birth weight, maternal race, plurality, and smoking status.

RESULTS

IgA, and the IgG subtypes IgG3 and IgG4 were found to be significantly lower in PCD neonates relative to VD neonates in adjusted regression models: 3.57 mg/ml, (95% CI: 3.51, 3.63) compared to 3.64 mg/ml (95% CI: 3.59, 3.69); 8.95 ng/ml (95% CI: 8.88,9.03) compared to 9.03 ng/ml (95% CI: 8.98, 9.08) and 8.05 ng/ml (95% CI: 7.91, 8.20) compared to 8.22 ng/ml (95% CI: 7.91,8.20), respectively.

CONCLUSIONS

MOD may thus be related to neonatal immune profile. Results were found to be robust to sensitivity testing based on maternal complications and indication for CD. Clinical implications are unclear given the small levels of association found in newborns, but the result suggests greater susceptibility to infection, and further study is warranted.

Identification of ANXA2 on epithelial cells as a new receptor for secretory IgA using immunoprecipitation and mass spectrometry

Secretory immunoglobulin A plays an important role in the protection against exogenous pathogens and antigens, but it has also been reported to have pathogenic potential. We previously found that secretory immunoglobulin A accumulated in the peripheral lungs during idiopathic pulmonary fibrosis and that transferrin receptor/CD71 was partially involved in secretory immunoglobulin A-induced inflammatory cytokine production in A549 cells. This study aimed to identify the receptor responsible for the induction of cytokine production by secretory immunoglobulin A-stimulated airway epithelial cells. To this end, immunoprecipitation followed by time-of-flight mass spectrometry and peptide mass fingerprinting were performed and Annexin A2 was detected as a novel receptor for secretory immunoglobulin A. Enzyme-linked immunosorbent assay demonstrated binding of secretory immunoglobulin A to Annexin A2, and flow cytometry showed robust expression of Annexin A2 on the surface of BEAS-2B cells, A549 cells, and normal human bronchial/tracheal epithelial cells. Experiments in A549 cells using Annexin A2 small interfering RNA and neutralizing antibodies suggested that Annexin A2 was partially involved in the production of interleukin-8/CXCL8 and C-C motif chemokine ligand 2/monocyte chemoattractant protein-1 induced by secretory immunoglobulin A. Immunohistochemistry using lung sections revealed clear expression of Annexin A2 on airway epithelial cells, although the staining remained equivalent in idiopathic pulmonary fibrosis, asthma, and healthy control lungs. In conclusion, we identified that Annexin A2 expressed in airway epithelial cells is a novel receptor for secretory immunoglobulin A, which is involved in cytokine synthesis.

Caspase-1 inhibition by YVAD generates tregs pivoting IL-17 to IL-22 response in β-glucan induced airway inflammation

BACKGROUND

During Aspergillus fumigatus mediated lung inflammation, NLRP3 inflammasome is rapidly activated that aggravates IL-1β production contributing to lung inflammation. Previously, we have shown the protective role of SYK-1 inhibition in inhibiting inflammasome activation during lung inflammation. In the current manuscript, we explored the protective role of direct caspase-1 inhibition during β-glucan-induced lung inflammation.

METHODS

We have mimicked the lung inflammation by administering intranasal β-glucan in mice model. YVAD was used for caspase-1 inhibition.

RESULTS

We have shown that caspase-1 inhibition by YVAD did not alter inflammasome independent inflammatory cytokines, while it significantly reduced inflammasome activation and IL-1β secretion. Caspase-1 inhibited bone marrow derived dendritic cells (BMDCs), co-cultured with T cells showed decreased T-cell proliferation and direct them to secrete high TGF-β and IL-10 compared to the T cells co-cultured with β-glucan primed dendritic cells. Caspase-1 inhibition in BMDCs also induced IL-22 secretion from CD4+T cells. Caspase-1 inhibition in intranasal β-glucan administered mice showed decreased tissue damage, immune cell infiltration and IgA secretion compared to control mice. Further, splenocytes challenged with β-glucan show high IL-10 secretion and increased FOXp3 and Ahr indicating an increase in regulatory T cells on caspase-1 inhibition.

CONCLUSION

Caspase-1 inhibition can thus be an attractive target to prevent inflammation mediated tissue damage during Aspergillus fumigatus mouse model and can be explored as an attractive therapeutic strategy.HIGHLIGHTSCaspase-1 inhibition protects lung damage from inflammation during β-glucan exposureCaspase-1 inhibition in dendritic cells decreases IL-1β production resulting in decreased pathogenic Th17Caspase-1 inhibition promotes regulatory T cells thereby inhibiting lung inflammation.

Variable-heavy (VH) families influencing IgA1&2 engagement to the antigen, FcαRI and superantigen proteins G, A, and L

Interest in IgA as an alternative antibody format has increased over the years with much remaining to be investigated in relation to interactions with immune cells. Considering the recent whole antibody investigations showing significant distal effects between the variable (V) and constant (C)- regions that can be mitigated by the hinge regions of both human IgA subtypes A1 and A2, we performed an in-depth mechanistic investigation using a panel of 28 IgA1s and A2s of both Trastuzumab and Pertuzumab models. FcαRI binding were found to be mitigated by the differing glycosylation patterns in IgA1 and 2 with contributions from the CDRs. On their interactions with antigen-Her2 and superantigens PpL, SpG and SpA, PpL was found to sterically hinder Her2 antigen binding with unexpected findings of IgAs binding SpG at the CH2-3 region alongside SpA interacting with IgAs at the CH1. Although the VH3 framework (FWR) is commonly used in CDR grafting, we found the VH1 framework (FWR) to be a possible alternative when grafting IgA1 and 2 owing to its stronger binding to antigen Her2 and weaker interactions to superantigen Protein L and A. These findings lay the foundation to understanding the interactions between IgAs and microbial superantigens, and also guide the engineering of IgAs for future antibody applications and targeting of superantigen-producing microbes.

Influence of Consumption of Two Peruvian Cocoa Populations on Mucosal and Systemic Immune Response in an Allergic Asthma Rat Model

Different cocoa populations have demonstrated a protective role in a rat model of allergic asthma by attenuating the immunoglobulin (Ig) E synthesis and partially protecting against anaphylactic response. The aim of this study was to ascertain the effect of diets containing two native Peruvian cocoa populations (“Amazonas Peru” or APC, and “Criollo de Montaña” or CMC) and an ordinary cocoa (OC) on the bronchial compartment and the systemic and mucosal immune system in the same rat model of allergic asthma. Among other variables, cells and IgA content in the bronchoalveolar lavage fluid (BALF) and serum anti-allergen antibody response were analyzed. The three cocoa populations prevented the increase of the serum specific IgG1 (T helper 2 isotype). The three cocoa diets decreased asthma-induced granulocyte increase in the BALF, which was mainly due to the reduction in the proportion of eosinophils. Moreover, both the OC and CMC diets were able to prevent the leukocyte infiltration caused by asthma induction in both the trachea and nasal cavity and decreased the IgA in both fecal and BALF samples. Overall, these results highlight the potential of different cocoa populations in the prevention of allergic asthma.

Fungal allergic sensitisation in young rural Zimbabwean children: Gut mycobiome and seroreactivity characteristics

Background

The prevalence of allergic diseases has increased over the last few decades, with sensitisation to fungal allergens and gut microbiome dysbiosis implicated in this trend. The fungal community in the gut (mycobiome) has yet to be characterised and related to fungal allergic sensitisation. Thus, we characterised the gut mycobiome and related it to fungal sensitisation and seroreactivity among Zimbabwean children. We further determined the effect of host age, sex, Schistosoma haematobium infection and mycobiome composition on fungal sensitisation and seroreactivity.

Methods

Using shotgun metagenomic sequencing, we characterised the gut microbiome of stool samples of 116 preschool aged children (PSAC) (≤5 years old, 57(49.1%) male and 59 (50.9%) female). Sensitisation to common fungi in Zimbabwe was assessed using skin prick tests (SPTs). Allergen-specific IgM, IgA, IgG, IgE and IgG4 antibodies were quantified by ELISA. We analysed the relationship between fungal genera and SPT reactivity by ANOVA; fungal genera and IgE antibody reactivity by linear regression; variation in mycobiome abundance with host and environmental factors by PERMANOVA; SPT reactivity and host and environmental factors by logistic regression; seroreactivity and host and environmental factors by ANOVA.

Results

The mycobiome formed <1% of the sequenced gut microbiome and 228 fungal genera were identified. The most abundant genera detected were Protomyces, Taphrina, and Aspergillus. S.haematobium infection had a significant effect on fungal genera. Prevalence of SPT sensitisation to ≥1 fungal species was 96%, and individuals were frequently sensitised to Saccharomyces cerevisiae. Antibodies were detected in 100% of the population. There was no relationship between mycobiome abundance and IgE titres or IgE/IgG4 ratios for each fungal species; no significant differences between SPT reactivity and abundance of fungal species except for S. cerevisiae; and fungal seroreactivity did not significantly differ with age. There were some sex (m>f for, Epicoccum nigrum and Penicillium chrysogenum) and SPT reactivity -related differences in seroreactivity.

Conclusion

This is the first comprehensive characterisation of gut mycobiome and fungal allergic sensitisation of rural children in Zimbabwe. Although reported allergic disease is low there is a high percentage of sensitisation. Further studies with larger populations are required to understand the role of the mycobiome in allergic diseases.

Inhalations with thermal waters in respiratory diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Inhalations with thermal waters are an old therapeutic method used in the therapy of respiratory diseases as a treatment of choice showing a long-lasting outcome with no side effects. Paradoxically, there is little well-established research on their mechanisms of action.

AIM OF THE STUDY

The aim of this paper is therefore to summarize the influence of inhalatory treatment with thermal waters on the main symptoms and features of respiratory disorders including allergy-like symptoms, inflammation, oxidant-anti-oxidant balance, cellular influx, disturbed mucus secretions, recurrent infections, pulmonary and nasal function and quality of life. A short history of inhalations is also presented.

MATERIALS AND METHODS

The present paper is a sum-up of research articles on the use of inhalations with thermal waters in respiratory disorders.

RESULTS

According to the herein presented literature, the use of thermal water inhalations is beneficial for almost all manifestations of respiratory diseases. The mode of their action remains still unclear; however, it seems that the most important one relies on the restoration of proper defense mechanisms of the organism.

CONCLUSIONS

Inhalations with thermal waters alleviate symptoms of respiratory diseases. They also improve the quality of life of the patients and seem to be a good add-on therapy in the treatment of disorders of the respiratory system.

Caspase-11 regulates lung inflammation in response to house dust mites

Asthma is an inflammatory lung disorder characterized by mucus hypersecretion, cellular infiltration, and bronchial hyper-responsiveness. House dust mites (HDM) are the most prevalent cause of allergic sensitization. Canonical and noncanonical inflammasomes are multiprotein complexes that assemble in response to pathogen or danger-associated molecular patterns (PAMPs or DAMPs). Murine caspase-11 engages the noncanonical inflammasome. We addressed the role of caspase-11 in mediating host responses to HDM and subsequent allergic inflammation using caspase-11-/- mice, which lack caspase-11 while express caspase-1. We found that HDM induce caspase-11 expression in vitro. The presence of IL-4 and IL-13 promote caspase-11 expression. Additionally, caspase-11-/- macrophages show reduced release of IL-6, IL-12, and KC, and express lower levels of costimulatory molecules (e.g., CD40, CD86 and MHCII) in response to HDM stimulation. Notably, HDM sensitization of caspase-11-/- mice resulted in similar levels of IgE responses and hypothermia in response to nasal HDM challenge compared to WT. However, analysis of cell numbers and cytokines in bronchiolar alveolar lavage fluid (BALF) and histopathology of representative lung segments demonstrate altered inflammatory responses and reduced neutrophilia in the airways of the caspase-11-/- mice. These findings indicate that caspase-11 regulates airway inflammation in response to HDM exposure.

Antibody Class(es) Predictor for Epitopes (AbCPE): A Multi-Label Classification Algorithm

Development of vaccines and therapeutic antibodies to deal with infectious and other diseases are the most perceptible scientific interventions that have had huge impact on public health including that in the current Covid-19 pandemic. From inactivation methodologies to reverse vaccinology, vaccine development strategies of 21st century have undergone several transformations and are moving towards rational design approaches. These developments are driven by data as the combinatorials involved in antigenic diversity of pathogens and immune repertoire of hosts are enormous. The computational prediction of epitopes is central to these developments and numerous B-cell epitope prediction methods developed over the years in the field of immunoinformatics have contributed enormously. Most of these methods predict epitopes that could potentially bind to an antibody regardless of its type and only a few account for antibody class specific epitope prediction. Recent studies have provided evidence of more than one class of antibodies being associated with a particular disease. Therefore, it is desirable to predict and prioritize ‘peptidome’ representing B-cell epitopes that can potentially bind to multiple classes of antibodies, as an open problem in immunoinformatics. To address this, AbCPE, a novel algorithm based on multi-label classification approach has been developed for prediction of antibody class(es) to which an epitope can potentially bind. The epitopes binding to one or more antibody classes (IgG, IgE, IgA and IgM) have been used as a knowledgebase to derive features for prediction. Multi-label algorithms, Binary Relevance and Label Powerset were applied along with Random Forest and AdaBoost. Classifier performance was assessed using evaluation measures like Hamming Loss, Precision, Recall and F1 score. The Binary Relevance model based on dipeptide composition, Random Forest and AdaBoost achieved the best results with Hamming Loss of 0.1121 and 0.1074 on training and test sets respectively. The results obtained by AbCPE are promising. To the best of our knowledge, this is the first multi-label method developed for prediction of antibody class(es) for sequential B-cell epitopes and is expected to bring a paradigm shift in the field of immunoinformatics and immunotherapeutic developments in synthetic biology. The AbCPE web server is available at http://bioinfo.unipune.ac.in/AbCPE/Home.html.

The Epidemiology and Clinical Presentations of Atopic Diseases in Selective IgA Deficiency

Selective IgA deficiency (sIgAD) is the most common primary immunodeficiency disease (PID), with an estimated occurrence from about 1:3000 to even 1:150, depending on population. sIgAD is diagnosed in adults and children after the 4th year of age, with immunoglobulin A level below 0.07 g/L and normal levels of IgM and IgG. Usually, the disease remains undiagnosed throughout the patient's life, due to its frequent asymptomatic course. If symptomatic, sIgAD is connected to more frequent viral and bacterial infections of upper respiratory, urinary, and gastrointestinal tracts, as well as autoimmune and allergic diseases. Interestingly, it may also be associated with other PIDs, such as IgG subclasses deficiency or specific antibodies deficiency. Rarely sIgAD can evolve to common variable immunodeficiency disease (CVID). It should also be remembered that IgA deficiency may occur in the course of other conditions or result from their treatment. It is hypothesized that allergic diseases (e.g., eczema, rhinitis, asthma) are more common in patients diagnosed with this particular PID. Selective IgA deficiency, although usually mildly symptomatic, can be difficult for clinicians. The aim of the study is to summarize the connection between selective IgA deficiency and atopic diseases.

Viability Status-Dependent Effect of Bifidobacterium longum ssp. longum CCM 7952 on Prevention of Allergic Inflammation in Mouse Model

The classical definition of probiotics states that bacteria must be alive to be beneficial for human organism. However, recent reports show that inactivated bacteria or their effector molecules can also possess such properties. In this study, we investigated the physical and immunomodulatory properties of four Bifidobacterium strains in the heat-treated (HT) and untreated (UN) forms. We showed that temperature treatment of bacteria changes their size and charge, which affects their interaction with epithelial and immune cells. Based on the in vitro assays, we observed that all tested strains reduced the level of OVA-induced IL-4, IL-5, and IL-13 in the spleen culture of OVA-sensitized mice. We selected Bifidobacterium longum ssp. longum CCM 7952 (Bl 7952) for further analysis. In vivo experiments confirmed that untreated Bl 7952 exhibited allergy-reducing properties when administered intranasally to OVA-sensitized mice, which manifested in significant suppression of airway inflammation. Untreated Bl 7952 decreased local and systemic levels of Th2 related cytokines, OVA-specific IgE antibodies and simultaneously inhibited airway eosinophilia. In contrast, heat-treated Bl 7952 was only able to reduce IL-4 levels in the lungs and eosinophils in bronchoalveolar lavage, but increased neutrophil and macrophage numbers. We demonstrated that the viability status of Bl 7952 is a prerequisite for the beneficial effects of bacteria, and that heat treatment reduces but does not completely abolish these properties. Further research on bacterial effector molecules to elucidate the beneficial effects of probiotics in the prevention of allergic diseases is warranted.

The Breast Milk Immunoglobulinome

Breast milk components contribute to the infant’s immune development and protection, and among other immune factors, immunoglobulins (Igs) are the most studied. The presence of IgA in milk has been known for a long time; however, less information is available about the presence of other Igs such as IgM, IgG, and their subtypes (IgG1, IgG2, IgG3, and IgG4) or even IgE or IgD. The total Ig concentration and profile will change during the course of lactation; however, there is a great variability among studies due to several variables that limit establishing a clear pattern. In this context, the aim of this review was firstly to shed light on the Ig concentration in breast milk based on scientific evidence and secondly to study the main factors contributing to such variability. A search strategy provided only 75 studies with the prespecified eligibility criteria. The concentrations and proportions found have been established based on the intrinsic factors of the study—such as the sampling time and quantification technique—as well as participant-dependent factors, such as lifestyle and environment. All these factors contribute to the variability of the immunoglobulinome described in the literature and should be carefully addressed for further well-designed studies and data interpretation.

Asthma-Associated Long TSLP Inhibits the Production of IgA

Thymic stromal lymphopoietin (TSLP) contributes to asthmatic disease. The concentrations of protective IgA may be reduced in the respiratory tract of asthma patients. We investigated how homeostatic short TSLP (shTSLP) and asthma-associated long TSLP (loTSLP) regulate IgA production. B cells from healthy donors were stimulated in the presence or absence of shTSLP or loTSLP; the concentrations of IgA, IgM, IgE, and IgG antibodies were determined in cell culture supernatants; and B cells were analyzed by flow cytometry. LoTSLP, but not shTSLP, suppressed the secretion of IgA but not of IgE. The type 2 cytokine IL-4, which in addition to loTSLP contributes to asthmatic disease, did not affect the production of IgA or the frequency of IgA+ B cells. Instead, IL-4 increased IgG production, especially of the subclasses IgG2 and IgG4. LoTSLP inhibited IgA secretion by sorted memory B cells but not by naïve B cells. Although loTSLP inhibited IgA production, the vitamin A metabolite retinoic acid promoted the secretion of IgA, also in the presence of loTSLP, suggesting that vitamin A may promote IgA production in asthma. Our data demonstrate that asthma-associated loTSLP negatively regulates the secretion of IgA, which may negatively impact the surveillance of mucosal surfaces in asthma.

Insights Into Mucosal Innate Immune Responses in House Dust Mite-Mediated Allergic Asthma

The prevalence of asthma has been rising steadily for several decades, and continues to be a major public health and global economic burden due to both direct and indirect costs. Asthma is defined as chronic heterogeneous inflammatory diseases characterized by airway obstruction, mucus production and bronchospasm. Different endotypes of asthma are being recognized based on the distinct pathophysiology, genetic predisposition, age, prognosis, and response to remedies. Mucosal innate response to environmental triggers such as pollen, cigarette smoke, fragrances, viral infection, and house dust mite (HDM) are now recognized to play an important role in allergic asthma. HDM are the most pervasive allergens that co-habitat with us, as they are ubiquitous in-house dusts, mattress and bedsheets, and feed on a diet of exfoliated human skin flakes. Dermatophagoides pteronyssinus, is one among several HDM identified up to date. During the last decade, extensive studies have been fundamental in elucidating the interactions between HDM allergens, the host immune systems and airways. Moreover, the paradigm in the field of HDM-mediated allergy has been shifted away from being solely a Th2-geared to a complex response orchestrated via extensive crosstalk between the epithelium, professional antigen presenting cells (APCs) and components of the adaptive immunity. In fact, HDM have several lessons to teach us about their allergenicity, the complex interactions that stimulate innate immunity in initiating and perpetuating the lung inflammation. Herein, we review main allergens of Dermatophagoides pteronyssinus and their interactions with immunological sentinels that promote allergic sensitization and activation of innate immunity, which is critical for the development of the Th2 biased adaptive immunity to HDM allergens and development of allergic asthma.

Secretory IgA accumulated in the airspaces of idiopathic pulmonary fibrosis and promoted VEGF, TGF-β and IL-8 production by A549 cells

Secretory IgA (SIgA) is a well-known mucosal-surface molecule in first-line defense against extrinsic pathogens and antigens. Its immunomodulatory and pathological roles have also been emphasized, but it is unclear whether it plays a pathological role in lung diseases. In the present study, we aimed to determine the distribution of IgA in idiopathic pulmonary fibrosis (IPF) lungs and whether IgA affects the functions of airway epithelial cells. We performed immunohistochemical analysis of lung sections from patients with IPF and found that mucus accumulated in the airspaces adjacent to the hyperplastic epithelia contained abundant SIgA. This was not true in the lungs of non-IPF subjects. An in-vitro assay revealed that SIgA bound to the surface of A549 cells and significantly promoted production of vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β and interleukin (IL)-8, important cytokines in the pathogenesis of IPF. Among the known receptors for IgA, A549 cells expressed high levels of transferrin receptor (TfR)/CD71. Transfection experiments with siRNA targeted against TfR/CD71 followed by stimulation with SIgA suggested that TfR/CD71 may be at least partially involved in the SIgA-induced cytokine production by A549 cells. These phenomena were specific for SIgA, distinct from IgG. SIgA may modulate the progression of IPF by enhancing synthesis of VEGF, TGF-β and IL-8.

Does a carrot a day keep the allergy away?

Vitamin A is an important micronutrient, from plants diet taken up as carotenoids, from animal food sources as retinol. Its active metabolite retinoic acid (RA) binds to nuclear hormone receptors, thereby regulating gene transcription programs in various cells. Adequate nutritional intake of vitamin A is essential for pre- and postnatal development, eyesight and reproduction, and it contributes to the maintenance and regulation of the immune system. Recent molecular studies indicate that lipocalins play an important role in the bioavailability of RA and its immune modulation against Th2 responses. There is emerging evidence that supply with vitamin A determines the susceptibility to allergic diseases: significantly reduced serum vitamin A levels are commonly observed in allergic patients compared to healthy controls. In line, findings from nutritional and clinical trials suggest that sufficient vitamin A supplementation in pregnancy prevents the development of allergic diseases in the offspring, and helps in controlling symptoms in adult asthmatics. Overall, retinoids have a key role in regulating immune homeostasis on mucosal surfaces because they are able to interfere with inflammatory signalling pathways. In this mini-review we will concentrate on the current knowledge about the influence of dietary and supplementary vitamin A on allergic diseases in humans from infancy to adulthood.

A Review of the Physiological Effects and Mechanisms of Singing

Daily experience suggests that singing can energize us and even provide a physical workout. A growing amount of evidence has been presented to support anecdotal claims of the benefits of singing on health and well-being. Singing has been shown to be related to numerous physiological changes. The cardiorespiratory system is utilized during persistent singing training, resulting in enhanced respiratory muscles and an optimized breathing mode. In addition, singing can also cause changes in neurotransmitters and hormones, including the upregulation of oxytocin, immunoglobulin A, and endorphins, which improves immune function and increases feelings of happiness. This review is organized by respiratory, circulatory, and hormonal changes that are collectively a part of singing in a healthy population. The various studies are discussed with the intention of helping researchers and clinicians realize the potential benefit of singing and provide a clinical option as an adjunct therapy for a given situation. Better understanding of physiological mechanisms will lay a solid theoretical foundation for singing activities and will present important implications for further study. Evaluations of existing research and recommendations for future research are given to promote the scale and duration to better demonstrate the effectiveness of singing before it can be recommended in clinical guidelines and satisfy criteria for funding by commissioners of health and social care.

Immunoglobulin Glycosylation Effects in Allergy and Immunity

PURPOSE OF REVIEW

The aim of this review will be to familiarize the reader with the general area of antibody (Ab) glycosylation and to summarize the known functional roles of glycosylation and how glycan structure can contribute to various disease states with emphasis on allergic disease.

RECENT FINDINGS

Both immunoglobulin (Ig) isotype and conserved Fc glycosylation sites often dictate the downstream activity of an Ab where complexity and degree of glycosylation contribute to its ability to bind Fc receptors (FcRs) and activate complement. Most information on the effects of glycosylation center on IgG in cancer therapy and autoimmunity. In cancer therapy, glycosylation modifications that enhance affinity for activating FcRs are utilized to facilitate immune-mediated tumor cell killing. In autoimmunity, disease severity has been linked to alterations in the presence, location, and composition of Fc glycans. Significantly less is understood about the role of glycosylation in the setting of allergy and asthma. However, recent data demonstrate that glycosylation of IgE at the asparagine-394 site of Cε3 is necessary for IgE interaction with the high affinity IgE receptor but, surprisingly, glycosylation has no effect on IgE interaction with its low-affinity lectin receptor, CD23. Variations in the specific glycoform may modulate the interaction of an Ig with its receptors. Significantly more is known about the functional effects of glycosylation of IgG than for other Ig isotypes. Thus, the role of glycosylation is much better understood in the areas of autoimmunity and cancer therapy, where IgG is the dominant isotype, than in the field of allergy, where IgE predominates. Further work is needed to fully understand the role of glycan variation in IgE and other Ig isotypes with regard to the inhibition or mediation of allergic disease.

Therapeutic intranasal instillation of allergen-loaded microbubbles suppresses experimental allergic asthma in mice

Despite proven efficiency, subcutaneous immunotherapy for aeroallergens is impaired by the duration of the protocol, the repeated injections and potential side-effects associated with the doses of allergen administered. Intranasal delivery of immunotherapeutic agents may overcome several of these drawbacks, provided that an efficient allergen delivery vehicle can be identified. This study evaluates whether intranasally delivered gas-filled microbubble (MB)-associated ovalbumin (OVA), used as a model allergen, can serve as a therapeutic treatment in a mouse model of established allergic asthma. Lung and systemic production of pro-tolerogenic markers, including Foxp3⁺ CD4 T cells, IL-10, and TGF-β, as well as the Th1-type cytokine IFN-γ, was observed after intranasal immunization with OVA-MB. Post-treatment, aerosol-sensitized mice exhibited the same pattern of markers. Moreover, decrease of eosinophils and neutrophils in BALs, lower frequencies of Th2 cytokine- and IL-17-producing CD4 T cells in lungs and reduced specific IgE in BALs and sera after allergen challenge were observed. Concomitantly, lung resistance and mucus production diminished in OVA-MB-treated animals. Thus, therapeutic intranasal administration of OVA-MBs in established experimental allergic asthma allows modulating pathology-associated immune and physiological parameters usually triggered after exposure to the allergen.

The recombinant fusion protein of cholera toxin B and neutrophil-activating protein expressed on Bacillus subtilis spore surface suppresses allergic inflammation in mice

The neutrophil-activating protein of Helicobacter pylori (HP-NAP) has been identified as a modulator with anti-Th2 inflammation activity, and cholera toxin B (CTB) is a mucosal adjuvant that can also induce antigen tolerance. In this study, we constructed a CTB-NAP fusion protein on the surface of Bacillus subtilis spore and evaluate the efficiency of oral administration of the recombinant CTB-NAP spores in preventing asthma in mice. Oral administration of recombinant CTB or CTB-NAP spores significantly decreased serum ovalbumin (OVA)-specific IgE (p < 0.001) and increased fecal IgA (p < 0.01) compared to the treatment with non-recombinant spores. Oral administration of recombinant CTB or CTB-NAP spores induced IL-10 and IFN-γ expression and reduced IL-4 levels in bronchoalveolar lavage fluid (BALF). Moreover, CTB and CTB-NAP spores reduced the eosinophils in BALF and inflammatory cell infiltration in the lungs. Furthermore, CD4⁺CD25⁺Foxp3⁺ Tregs in splenocytes were significantly increased in mice treated with recombinant CTB or CTB-NAP spores. The number of CD4⁺CD25⁺Foxp3⁺ Tregs caused by CTB-NAP was higher than that by CTB alone. Our study indicated that B. subtilis spores with surface expression of subunit CTB or CTB-NAP could inhibit OVA-induced allergic inflammation in mice. The attenuated inflammation was attributed to the induction of CD4⁺CD25⁺Foxp3⁺ Tregs and IgA. Moreover, the fusion protein CTB-NAP demonstrated a better efficiency than CTB alone in inhibiting the inflammation.

Respiratory Syncytial virus infection compromises asthma tolerance by recruiting interleukin-17A-producing cells via CCR6-CCL20 signaling

Asthma tolerance can be induced by breast-feeding or oral feeding with ovalbumin (OVA). Anergy or deletion of specific T cells and generation of T regulatory cells might contribute to this process. However, whether respiratory syncytial virus (RSV) infection would affect asthma tolerance is not very clear. Here, we first established asthma and oral tolerance mouse models and then analyzed airway hypersensitivity and asthma-related genes in the lung, CCR6-expressing IL-17A⁺ cells in the lungs, hilar or mesenteric lymph nodes (HLN or MLN) among control, asthmatic, tolerized, RSV infection, and RSV-infected asthmatic and tolerized groups. We also administrated CCL20 or IL-17A neutralizing antibody to RSV-infected tolerized mice to test whether RSV infection would mobilize CCR6-expressing IL-17A⁺ cells from MLN to the infected lungs. We found that tolerized mice infected with RSV developed asthma-like responses manifested by increasing airway hypersensitivity, exacerbating peribronchial inflammation, elevating lung asthma-related genes (Il17a, Mu5ac, and Gob5), accumulating CCR6-expressing IL-17A⁺ cells in the lungs and HLN with a reduction of this cell population in MLN. CCL20-CCR6 co-expression in RSV-infected tolerized MLN was reduced. Neutralization of CCL20 reduced CD3⁺CD4⁺CCR6⁺ cells in the RSV-infected tolerized HLN. Neutralization of IL-17A mitigated the compromising effects of RSV infection on asthma tolerance. Taken together, RSV infection impairs asthma tolerance by recruiting IL-17A-producing cells via CCR6-CCL20 signaling. The findings provide novel insight into exacerbation and therapeutic strategy of asthma under RSV infection.

Relationship between serum IgA level and allergy/asthma

BACKGROUND/AIMS

Mucosal immunoglobulin A (IgA) may prevent the entrance of allergens. This study examined the relationship between serum IgA levels (within the normal range) and sensitization to house dust mites (HDM) or airway hyper-responsiveness (AHR).

METHODS

The clinical records of 1,136 adult patients with suspected asthma, for whom test data for serum IgA level and methacholine-AHR were available, were reviewed retrospectively. The AHR/allergy indices were compared among patient groups with low (<140 mg/dL, group I), intermediate (140 to 280 mg/dL, group II), or high (≥280 mg/dL, group III) IgA levels in serum.

RESULTS

The HDM skin sensitization rate progressively decreased from 30.0% in group I (n = 139) to 26.8% and 18.5% in groups II (n = 684) and III (n = 313), respectively (p = 0.003). Although both the HDM sensitization degree and the IgA level were significantly related to age, the adjusted odds ratio (OR) of association of a high IgA level (≥ 280 mg/dL) with HDM sensitization was significant (0.617; 95% confidence interval [CI], 0.415 to 0.916; p = 0.017). Among younger subjects (≤ 45 years of age) with AHR, the prevalence of moderate/severe AHR progressively decreased (70.6%, 52.3%, and 47.1% in groups I, II, and III [n = 34, 149, and 51]), respectively (p = 0.045). The IgA < 140 mg/dL was a significant risk factor for moderate/severe AHR (OR, 2.306; 95% CI, 1.049 to 5.071; p = 0.038).

CONCLUSIONS

Sensitization to HDM and methacholine-AHR were significantly associated with serum IgA levels in suspected asthmatics, even when those levels were normal.

House dust mite-driven asthma and allergen-specific T cells depend on B cells when the amount of inhaled allergen is limiting

BACKGROUND

Allergic asthma is a CD4 T_H2-lymphocyte driven disease characterized by airway hyperresponsiveness and eosinophilia. B cells can present antigens to CD4 T cells and produce IgE immunoglobulins that arm effector cells; however, mouse models are inconclusive on whether B cells are necessary for asthma development.

OBJECTIVES

We sought to address the role of B cells in a house dust mite (HDM)-driven T_H2-high asthma mouse model.

METHODS

Wild-type and B cell-deficient muMT mice were sensitized and challenged through the airways with HDM extracts. The antigen-presenting capacities of B cells were studied by using new T-cell receptor transgenic 1-DER mice specific for the Der p 1 allergen.

RESULTS

In vitro-activated B cells from HDM-exposed mice presented antigen to 1-DER T cells and induced a T_H2 phenotype. In vivo B cells were dispensable for activation of naive 1-DER T cells but necessary for full expansion of primed 1-DER T cells. At high HDM challenge doses, B cells were not required for development of pulmonary asthmatic features yet contributed to T_H2 expansion in the mediastinal lymph nodes but not in the lungs. When the amount of challenge allergen was decreased, muMT mice had reduced asthma features. Under these limiting conditions, B cells contributed also to expansion of T_H2 effector cells in the lungs and central memory T cells in the mediastinal lymph nodes.

CONCLUSION

B cells are a major part of the adaptive immune response to inhaled HDM allergen, particularly when the amount of inhaled allergen is low, by expanding allergen-specific T cells.

Humoral immune factors and asthma among American Indian children: a case-control study

Background

Asthma is recognized as intimately related to immunologic factors and inflammation, although there are likely multiple phenotypes and pathophysiologic pathways. Biomarkers of inflammation may shed light on causal factors and have potential clinical utility. Individual and population genetic factors are correlated with risk for asthma and improved understanding of these contributions could improve treatment and prevention of this serious condition.

Methods

A population-based sample of 108 children with clinically defined asthma and 216 control children were recruited from a small community in the northern plains of the United States. A complete blood count, high sensitivity C-reactive protein, total IgE and specific antibodies to 5 common airborne antigens (CAA), in addition to basic demographic and anthropomorphic data were obtained. Logistic regression was primarily used to determine the association between these humoral factors and risk of asthma.

Results

The body mass index (BMI) of those with asthma and their total leukocyte counts, percentage of eosinophils, and levels of total IgE were all greater than corresponding control values in univariate analysis. The presence of detectable, specific IgE antibodies to five common airborne antigens was more likely among cases compared with controls. In multivariate analysis, total IgE was independently associated with asthma; but not after inclusion of a cumulative measure of specific IgE sensitization.

Conclusion

Many previously reported associations between anthropomorphic and immune factors and increased risk of asthma appear to be also present in this American Indian population. In this community, asthma is strongly associated with sensitization to CAA.

Nasal fluid secretory immunoglobulin A levels in children with allergic rhinitis

OBJECTIVES

There is growing knowledge about the immunoregulatory and possibly preventative roles of immunoglobulin A (IgA) in allergic diseases. This study aimed to investigate secretory immunoglobulin A (SIgA) levels in the nasal fluid of children who were either being treated for their allergic rhinitis (AR) with intranasal mometasone furoate or were not receiving treatment.

METHODS

The study population contained 55 children with persistent AR. Group I included 27 newly diagnosed AR patients not taking any medication and group II included 28 patients treated with intranasal steroids for at least 6 months. 27 healthy control subjects were also enrolled in the study. Total symptom scores (TSS) were calculated for each patient. Nasal secretions were obtained using a new modified polyurethane sponge absorption method, and samples were analysed by ELISA.

RESULTS

The median value for nasal fluid SIgA level in each group was 127.2μg/ml (interquartile range; 67.3-149.6) in group I, 133.9μg/ml (102.1-177.8) in group II and 299.8μg/ml (144.5-414.0) in the control group. Groups I and II both had statistically significant reductions in nasal fluid SIgA levels compared to the control group (p<0.001). However, there was no statistically significant difference between groups I and II (p=0.35). A statistically significant and negative correlation also existed between TSS and nasal fluid SIgA levels in both groups I and II (p=0.006, rho=-0.512 and p=0.01, rho=-0.481, respectively).

CONCLUSIONS

SIgA levels in the nasal fluid are significantly reduced in children with AR independent of treatment and are negatively correlated with the TSS.

A preventive immunization approach against insect bite hypersensitivity: Intralymphatic injection with recombinant allergens in Alum or Alum and monophosphoryl lipid A

Insect bite hypersensitivity (IBH) is an IgE-mediated dermatitis of horses caused by bites of Culicoides insects, not indigenous to Iceland. Horses born in Iceland and exported to Culicoides-rich areas are frequently affected with IBH. The aims of the study were to compare immunization with recombinant allergens using the adjuvant aluminum hydroxide (Alum) alone or combined with monophosphoryl lipid A (MPLA) for development of a preventive immunization against IBH. Twelve healthy Icelandic horses were vaccinated intralymphatically three times with 10 μg each of four recombinant Culicoides nubeculosus allergens in Alum or in Alum/MPLA. Injection with allergens in both Alum and Alum/MPLA resulted in significant increase in specific IgG subclasses and IgA against all r-allergens with no significant differences between the adjuvant groups. The induced antibodies from both groups could block binding of allergen specific IgE from IBH affected horses to a similar extent. No IgE-mediated reactions were induced. Allergen-stimulated PBMC from Alum/MPLA horses but not from Alum only horses produced significantly more IFNγ and IL-10 than PBMC from non-vaccinated control horses. In conclusion, intralymphatic administration of small amounts of pure allergens in Alum/MPLA induces high IgG antibody levels and Th1/Treg immune response and is a promising approach for immunoprophylaxis and immunotherapy against IBH.

B-1 cells as a source of IgA

Immunoglobulin A (IgA) is the most abundantly produced immunoglobulin found primarily on mucosal surfaces. The generation of IgA and its involvement in mucosal immune responses have been intensely studied over the past years. IgA can be generated in T cell-dependent and T cell-independent pathways, and it has an important impact on maintaining homeostasis within the mucosal immune system. There is good evidence that B-1 cells contribute substantially to the production of mucosal IgA and thus play an important role in regulating commensal microbiota. However, whether B-1 cells produce antigen-specific or only nonspecific IgA remains to be determined. This review will discuss what is currently known about IgA production by B-1 cells and the functional relevance of B-1 cell-derived IgA both in vitro and in vivo.

IgE and IgA produced by OX40-OX40L or CD40-CD40L interaction in B cells-mast cells re-activate FcεRI or FcαRI on mast cells in mouse allergic asthma

Mast cells are major effector cells of allergic diseases related to IgE. This study was undertaken to determine whether IgE or IgA, produced by CD40-CD40L or OX40-OX40L interactions between B cells and mast cells, re-activate FcεRI or FcαRI on mast cell surface. C57BL mice were sensitized and subjected to OVA challenge to induce asthma. Bone marrow-derived mast cells (BMMCs) and primary B cells were co-cultured. Mast cell recruitment into airways was stained by May-Grünwald Giemsa, the expression of markers or signaling molecules were determined by immunohistochemistry or Western blotting, and co-localization of B cells and mast cells by immunofluorescence. Anti-CD40 plus anti-OX40L Abs synergistically reduced IgE and IgA production, and mediators (histamine, LTs and cytokines) released in mast cells, and additively reduced other responses, such as, numbers of mast cells, the expression of markers (tryptase, mMCP5, B220 and CD19), surface molecules (CD40, CD40L, OX40 and OX40L), FcεRI or FcαRI and the co-localization of BMMCs and B cells, and IgE- or IgA-producing cells, as compared with individual blocking Ab treatment which reducedresponses in BAL cells or lung tissues of OVA-challenged mice or in co-culture of B and mast cells. The data suggest that IgE and IgA, produced by OX40-OX40L or CD40-CD40L interaction between B cells and mast cells, may re-activate receptors of FCεRI and FcαRI on mast cell surfaces, followed by more mediator release, and furthermore, that treatment with anti-CD40 plus anti-OX40L Abs offers a potential treatment for allergic asthma.

Probiotics and pregnancy

Complications of pregnancy are associated with adverse outcomes for mother and baby in the short and long term. The gut microbiome has been identified as a key factor for maintaining health outside of pregnancy and could contribute to pregnancy complications. In addition, the vaginal and the recently revealed placental microbiome are altered in pregnancy and may play a role in pregnancy complications. Probiotic supplementation could help to regulate the unbalanced microflora composition observed in obesity and diabetes. Here, the impact of probiotic supplementation during pregnancy and infancy is reviewed. There are indications for a protective role in preeclampsia, gestational diabetes mellitus, vaginal infections, maternal and infant weight gain and allergic diseases. Large, well-designed randomised controlled clinical trials along with metagenomic analysis are needed to establish the role of probiotics in adverse pregnancy and infancy outcomes.

Regulatory functions of B cells in allergic diseases

B cells are essentially described for their capacity to produce antibodies ensuring anti-infectious immunity or deleterious responses in the case of autoimmunity or allergy. However, abundant data described their ability to restrain inflammation by diverse mechanisms. In allergy, some regulatory B-cell subsets producing IL-10 have been recently described as potent suppressive cells able to restrain inflammatory responses both in vitro and in vivo by regulatory T-cell differentiation or directly inhibiting T-cell-mediated inflammation. A specific deficit in regulatory B cells participates to more severe allergic inflammation. Induction of allergen tolerance through specific immunotherapy induces a specific expansion of these cells supporting their role in establishment of allergen tolerance. However, the regulatory functions carried out by B cells are not exclusively IL-10 dependent. Indeed, other regulatory mechanisms mediated by B cells are (i) the production of TGF-β, (ii) the promotion of T-cell apoptosis by Fas-Fas ligand or granzyme-B pathways, and (iii) their capacity to produce inhibitory IgG4 and sialylated IgG able to mediate anti-inflammatory mechanisms. This points to Bregs as interesting targets for the development of new therapies to induce allergen tolerance. In this review, we highlight advances in the study of regulatory mechanisms mediated by B cells and outline what is known about their phenotype as well as their suppressive role in allergy from studies in both mice and humans.

Immune mechanisms of sublingual immunotherapy

Sublingual immunotherapy (SLIT) is a well-established allergen-specific immunotherapy and a safe and effective strategy to reorient inappropriate immune responses in allergic patients. SLIT takes advantage of the tolerogenic environment of the oral mucosa to promote tolerance to the allergen. Several clinical studies have investigated the complex interplay of innate and adaptive immune responses that SLIT exploits. The oral immune system is composed of tolerogenic dendritic cells that, following uptake of allergen during SLIT, support the differentiation of T helper cell type 1 (Th1) and the induction of IL-10-producing regulatory T cells. Following SLIT, allergic disease-promoting T helper cell type 2 (Th2) responses shift to a Th1 inflammatory response, and IL-10 and transforming growth factor (TGF)-β production by regulatory T cells and tolerogenic dendritic cells suppress allergen-specific T cell responses. These immune changes occur both in the sublingual mucosa and in the periphery of a patient following SLIT. SLIT also promotes the synthesis of allergen-specific IgG and IgA antibodies that block allergen-IgE complex formation and binding to inflammatory cells, thus encouraging an anti-inflammatory environment. Several of these revealing findings have also paved the way for the identification of biomarkers of the clinical efficacy of SLIT. This review presents the emerging elucidation of the immune mechanisms mediated by SLIT.