Preventive and therapeutic effects of rapamycin, a mammalian target of rapamycin inhibitor, on food allergy in mice

Probiotics and other adjuvants in allergen-specific immunotherapy for food allergy: a comprehensive review

This review delves into the potential of manipulating the microbiome to enhance oral tolerance in food allergy, focusing on food allergen-specific immunotherapy (FA-AIT) and the use of adjuvants, with a significant emphasis on probiotics. FA-AIT, including oral (OIT), sublingual (SLIT), and epicutaneous (EPIT) immunotherapy, has shown efficacy in desensitizing patients and achieving sustained unresponsiveness (SU). However, the long-term effectiveness and safety of FA-AIT are still under investigation. Probiotics, particularly strains of Lactobacillus, play a crucial role in enhancing immune tolerance by promoting regulatory T cells (Tregs) and modulating cytokine profiles. These probiotics can induce semi-mature dendritic cells, enhance CD40 expression, inhibit IL-4 and IL-5, and promote IL-10 and TGF-β, thus contributing to mucosal defense and immunological tolerance. Clinical trials combining probiotics with FA-AIT have demonstrated improved desensitization rates and immune tolerance in food-allergic patients. For example, the combination of Lactobacillus rhamnosus with peanut OIT resulted in a significantly higher rate of SU compared to the placebo group, along with notable immune changes such as reduced peanut-specific IgE and increased IgG4 levels. The review also explores other adjuvants in FA-AIT, such as biologic drugs, which target specific immune pathways to improve treatment outcomes. Additionally, nanoparticles and herbal therapies like food allergy herbal formula 2 (FAHF-2) are discussed for their potential to enhance allergen delivery and immunogenicity, reduce adverse events, and improve desensitization. In conclusion, integrating probiotics and other adjuvants into FA-AIT protocols could significantly enhance the safety and efficacy of FA-AIT, leading to better patient outcomes and quality of life.

Towards an optimized model of food allergy in zebrafish

BACKGROUND

The prevalence of food allergies is on the rise, posing a significant challenge to public health. Rodents serve as the predominant animal model in food allergy research; yet, the application of rodent models proves to be a laborious and time-consuming endeavor. It is imperative to develop novel in vivo models.

METHODS

Ovalbumin (OVA) was administered as the allergen, following the recommended dosage used in other species. During the sensitization phase, a dosage of 0.25 mg per 10 tails per 1 L was administered twice daily, and during the challenge phase, the dosage was increased to 3 times the initial level. The study explored two dimensions of sensitization: the mode of exposure, which can be either continuous or intermittent, and the duration of exposure, which includes 3 days, 5 days, and 7 days. We examined midgut pathological changes, immunoglobulins contents, and mRNA expressions associated to T helper cells (Th) 2 cytokines following exposure.

RESULTS

A significant 109.3 % increase in the number of eosinophils was observed in the midgut histopathology following intermittent 5-day OVA exposure, which emerged as the most effective model. OVA exposure increased concentrations of immunoglobulin M (IgM) (105.2 %), IgZ (312.1 %), and IgD (304.3 %) in this model. The mRNA expressions of Th2-related interleukin (IL)-4 and IL-13 were also elevated by 132.8 % and 421.0 %, respectively.

CONCLUSION

The intermittent 5-day OVA exposure was suggested to be the best constructed zebrafish food allergy model, which may be a potential tool for research into food allergies.

Role of transient receptor potential vanilloid 4 channels in an ovalbumin-induced murine food allergic model

The prevalence of food allergy (FA) has increased worldwide but an effective therapeutic strategy has not been established. Transient receptor potential vanilloid 4 (TRPV4), a mechanosensitive nonselective cation channel, is mainly expressed in the epithelium of various organs. The present study investigated the role of TRPV4 in the pathogenesis of an ovalbumin (OVA)-induced FA model in mice. Wild-type (WT) and TRPV4-deficient (TRPV4KO) mice were sensitized and challenged by OVA to establish FA model. Intestinal tissue samples were processed for biochemical, molecular, and image analyses. Intestinal permeability and antigen uptake assay were conducted using FITC-dextran and OVA-FITC, respectively. TRPV4 was expressed in the colonic epithelium in normal and OVA-treated WT mice. Repeated oral administration of OVA to mice induced systemic allergic symptoms, diarrhea, upregulation of T helper 2 cytokines, OVA-specific immunoglobulin, and FA-related inflammatory cells. These responses were significantly augmented in TRPV4KO mice compared with WT mice. After the induction of FA, the intestinal permeability was significantly increased in TRPV4KO mice compared with WT mice. The expressions of the tight junction protein occludin and adherence junction protein E-cadherin in the colon were significantly lower in TRPV4KO mice compared with WT mice under normal and FA conditions. In addition, the uptake of OVA by CD11c-positive cells was significantly increased in TRPV4KO mice compared with WT mice under FA conditions. These results suggest that epithelial TRPV4 protects against OVA-induced FA symptoms by suppressing the penetration of allergens by maintaining epithelial barrier functions.

Deficiency of leukotriene B4 receptor type 1 ameliorates ovalbumin-induced allergic enteritis in mice

Leukotriene B4 receptor type 1 (BLT1), a high-affinity receptor for leukotriene B4 (LTB4), plays an important role in inflammatory responses, including allergic airway inflammation. In this study, we examined the effect of genetic BLT1 deletion (BLT1KO) on ovalbumin (OVA)-induced allergic enteritis in mice to determine the pathogenic role of LTB4/BLT1 in allergic enteritis, a gastrointestinal form of food allergy. Repeated oral OVA challenges after sensitization with OVA and aluminium potassium sulphate induced allergic enteritis, characterized by systemic allergic symptoms (scratching, immobility and swelling), diarrhoea, colonic oedema and colonic goblet cell hyperplasia, accompanied by increased colonic peroxidase activity, colonic inflammatory cytokine expression and increased serum OVA-specific IgE levels. The severity of enteritis was significantly attenuated in BLT1KO mice compared with wild-type (WT) mice, without an increase in serum OVA-specific IgE levels. The accumulation of neutrophils, eosinophils, M2-macrophages, dendritic cells, CD4+ T cells and mast cells was observed in the colonic mucosa of allergic enteritis, and such accumulation was significantly lower in BLT1KO mice than in WT mice. BLT1 expression was upregulated and colocalized mostly in neutrophils and partly in eosinophils and dendritic cells in the colonic mucosa of allergic enteritis. These findings indicate that BLT1 deficiency ameliorates OVA-induced allergic enteritis in mice and that LTB4/BLT1 contributes to neutrophil and eosinophil accumulation in the allergic colonic mucosa. Therefore, BLT1 is a promising drug target for treating food allergies.

Sialic acid and food allergies: The link between nutrition and immunology

Food allergies (FA), a major public health problem recognized by the World Health Organization, affect an estimated 3%-10% of adults and 8% of children worldwide. However, effective treatments for FA are still lacking. Recent advances in glycoimmunology have demonstrated the great potential of sialic acids (SAs) in the treatment of FA. SAs are a group of nine-carbon α-ketoacids usually linked to glycoproteins and glycolipids as terminal glycans. They play an essential role in modulating immune responses and may be an effective target for FA intervention. As exogenous food components, sialylated polysaccharides have anti-FA effects. In contrast, as endogenous components, SAs on immunoglobulin E and immune cell surfaces contribute to the pathogenesis of FA. Given the lack of comprehensive information on the effects of SAs on FA, we reviewed the roles of endogenous and exogenous SAs in the pathogenesis and treatment of FA. In addition, we considered the structure-function relationship of SAs to provide a theoretical basis for the development of SA-based FA treatments.

Targeting Mast Cells in Allergic Disease: Current Therapies and Drug Repurposing

The incidence of allergic disease has grown tremendously in the past three generations. While current treatments are effective for some, there is considerable unmet need. Mast cells are critical effectors of allergic inflammation. Their secreted mediators and the receptors for these mediators have long been the target of allergy therapy. Recent drugs have moved a step earlier in mast cell activation, blocking IgE, IL-4, and IL-13 interactions with their receptors. In this review, we summarize the latest therapies targeting mast cells as well as new drugs in clinical trials. In addition, we offer support for repurposing FDA-approved drugs to target mast cells in new ways. With a multitude of highly selective drugs available for cancer, autoimmunity, and metabolic disorders, drug repurposing offers optimism for the future of allergy therapy.

Evaluation of Toxicity and Efficacy of Inotodiol As an Anti-Inflammatory Agent Using Animal Model

Chaga mushroom (Inonotus obliquus) comprises polyphenolic compounds, triterpenoids, polysaccharides, and sterols. Among the triterpenoid components, inotodiol has been broadly examined because of its various biological activities. The purpose of this study is to examine inotodiol from a safety point of view and to present the potential possibilities of inotodiol for medical usage. From chaga mushroom extract, crude inotodiol (INO20) and pure inotodiol (INO95) were produced. Mice were treated with either INO20 or INO95 once daily using oral administration for repeated dose toxicity evaluation. Serum biochemistry parameters were analyzed, and the level of pro-inflammatory cytokines in the serum was quantified. In parallel, the effect of inotodiol on food allergic symptoms was investigated. Repeated administration of inotodiol did not show any mortality or abnormalities in organs. In food allergy studies, the symptoms of diarrhea were ameliorated by administration with INO95 and INO20. Furthermore, the level of MCPT-1 decreased by treatment with inotodiol. In this study, we demonstrated for the first time that inotodiol does not cause any detrimental effect by showing anti-allergic activities in vivo by inhibiting mast cell function. Our data highlight the potential to use inotodiol as an immune modulator for diseases related to inflammation.

Food Allergy-Induced Autism-Like Behavior is Associated with Gut Microbiota and Brain mTOR Signaling

Purpose

Food allergy-induced autism-like behavior has been increasing for decades, but the causal drivers of this association are unclear. We sought to test the association of gut microbiota and mammalian/mechanistic target of rapamycin (mTOR) signaling with cow’s milk allergy (CMA)-induced autism pathogenesis.

Methods

Mice were sensitized intragastrically with whey protein containing cholera toxin before sensitization on intraperitoneal injection with whey-containing alum, followed by intragastric allergen challenge to induce experimental CMA. The food allergic immune responses, ASD-like behavioral tests and changes in the mTOR signaling pathway and gut microbial community structure were performed.

Results

CMA mice showed autism-like behavioral abnormalities and several distinct biomarkers. These include increased levels of 5-hydroxymethylcytosine (5-hmC) in the hypothalamus; c-Fos were predominantly located in the region of the lateral orbital prefrontal cortex (PFC), but not ventral; decreased serotonin 1A in amygdala and PFC. CMA mice exhibited a specific microbiota signature characterized by coordinate changes in the abundance of taxa of several bacterial genera, including the Lactobacillus. Interestingly, the changes were accompanied by promoted mTOR signaling in the brain of CMA mice.

Conclusion

We found that disease-associated microbiota and mTOR activation may thus play a pathogenic role in the intestinal, immunological, and psychiatric Autism Spectrum Disorder (ASD)-like symptoms seen in CAM associated autism. However, this is only a preliminary study, and their mechanisms require further investigation.

Engineered implantable vaccine platform for continuous antigen-specific immunomodulation

Cancer vaccines harness the host immune system to generate antigen-specific antitumor immunity for long-term tumor elimination with durable immunomodulation. Commonly investigated strategies reintroduce ex vivo autologous dendritic cells (DCs) but have limited clinical adoption due to difficulty in manufacturing, delivery and low clinical efficacy. To combat this, we designed the "NanoLymph", an implantable subcutaneous device for antigen-specific antitumor immunomodulation. The NanoLymph consists of a dual-reservoir platform for sustained release of immune stimulants via a nanoporous membrane and hydrogel-encapsulated antigens for local immune cell recruitment and activation, respectively. Here, we present the development and characterization of the NanoLymph as well as efficacy validation for immunomodulation in an immunocompetent murine model. Specifically, we established the NanoLymph biocompatibility and mechanical stability. Further, we demonstrated minimally invasive transcutaneous refilling of the drug reservoir in vivo for prolonging drug release duration. Importantly, our study demonstrated that local elution of two drugs (GMCSF and Resiquimod) generates an immune stimulatory microenvironment capable of local DC recruitment and activation and generation of antigen-specific T lymphocytes within 14 days. In summary, the NanoLymph approach can achieve in situ immunomodulation, presenting a viable strategy for therapeutic cancer vaccines.

IgE-expressing long-lived plasma cells in persistent sensitization

Persistent allergies affect the quality of life of patients and increase economic burdens. Many clinical observations indicate the presence of IgE⁺ long-lived plasma cells (LLPCs), which account for the persistent secretion of specific IgE; however, the characteristics of the IgE⁺ LLPCs have yet to be identified clearly. In this review, we summarized the generation of IgE⁺ PCs, discussed the prosurvival factors in the microenvironment, and reviewed the unique IgE-BCR signaling, which may bring insights into understanding the survival mechanisms of IgE⁺ LLPCs.

Poly-L-arginine promotes asthma angiogenesis through induction of FGFBP1 in airway epithelial cells via activation of the mTORC1-STAT3 pathway

Angiogenesis is a key characteristic of asthma airway remodeling. By releasing cationic granule proteins, such as major basic protein (MBP), activated eosinophils play a prominent role in asthma, but the underlying mechanisms are still not fully understood. In this study, we demonstrated that fibroblast growth factor-binding protein 1 (FGFBP1) was dramatically upregulated in airway epithelial cell lines treated by poly-L-arginine (PLA), a mimic of MBP. Elevated FGFBP1 expression was also detected in asthma clinical samples, as well as in ovalbumin (OVA)-induced chronic asthma mouse models. PLA enhanced FGFBP1 expression through activation of the mechanistic target of rapamycin complex 1-signal transducer and activator of transcription 3 (mTORC1-STAT3) signaling pathway. STAT3 transactivated FGFBP1 by directly binding to the promoter of the FGFBP1 gene. Furthermore, we identified that FGFBP1 secreted by PLA-treated airway epithelial cells served as a proangiogenesis factor. Lastly, we found the mTORC1-STAT3-FGFBP1 signaling pathway was activated in an OVA-induced chronic asthma model with airway remodeling features. Rapamycin treatment alleviated respiratory symptoms and reduced angiogenesis in asthmatic mice. Therefore, activation of the mTORC1-STAT3-FGFBP1 pathway in the airway epithelium contributes to the progress of angiogenesis and should be targeted for the treatment of asthma.

Piper nigrum extract attenuates food allergy by decreasing Th2 cell response and regulating the Th17/Treg balance

Piper nigrum is extensively utilized because of its antioxidation, antiallergic, antitumor, antiinflammatory, antidiarrhea, and gastrointestinal protection. We attempted to indicate whether the Piper nigrum extract (PNE) could alleviate ovalbumin (OVA)-induced food allergy, and to explore its potential mechanism. An OVA-induced food allergy mouse model was established, and different concentrations of PNE were administrated. Symptoms of food allergy, levels of immunoglobulin E (IgE), mucosal mast cell protease-1 (mMCP-1), and intestine pathological changes were assessed. Additionally, the expressions of T helper (Th) 2, Th17 and regulatory T (Treg)-associated cytokines and the proportion of Th17 and Treg cells in CD4⁺ T cells were measured. We found PNE attenuated symptoms of food allergy and decreased the levels of IgE and mMCP-1. In PNE group, the infiltration degree of inflammatory cells was ameliorated and the villi of small intestine were more complete. Moreover, the expressions of Th2 and Th17 cell-associated cytokines were down-regulated by PNE pretreatment, while the levels of Treg cell-associated cytokines were up-regulated. PNE decreased the number of Th17 cells, while increased the Tregs cells. PNE treatment dose-dependently improved the Th17/Treg balance. PNE plays a protective role in OVA-induced food allergy through inhibiting Th2 cell response and regulating the Th17/Treg balance.

Applications of Mouse Models to the Study of Food Allergy

Mouse models of allergic disease offer numerous advantages when compared to the models of other animals. However, selection of appropriate mouse models is critical to advance the field of food allergy by revealing mechanisms of allergy and for testing novel therapeutic approaches. All current mouse models for food allergy have weaknesses that may limit their applicability to human disease. Aspects such as the genetic predisposition to allergy or tolerance from the strain of mouse used, allergen dose, route of exposure (oral, intranasal, intraperitoneal, or epicutaneous), damage of the epithelial barrier, use of adjuvants, food matrix effects, or composition of the microbiota should be considered prior to the selection of a specific murine model and contemplated according to the intended purpose of the study. This chapter reviews our current knowledge on the application of mouse models to food allergy research and the variables that may influence the successful development of each type of model.

Disease Course and Treatment Response of Eosinophilic Gastrointestinal Diseases in Children With Liver Transplantation: Long-Term Follow-Up

INTRODUCTION

To describe the clinical and laboratory profile, natural course, treatment outcome, and risk factors of posttransplant esophageal and nonesophageal eosinophilic gastrointestinal disorders (EGIDs).

METHODS

All children (aged <18 years) who underwent liver transplantation, between 2011 and 2019, in a single transplant center with a follow-up period of 1 year or more posttransplant and with a history of posttransplant endoscopic evaluation were included in this study.

RESULTS

During the study period, 89 children met the inclusion criteria. Patients were followed for a median of 8.0 years. A total of 39 (44%) patients were diagnosed with EGID after transplantation. Of these, 29 (33%) had eosinophilic esophagitis (EoE), and 10 (11%) had eosinophilic gastritis, gastroenteritis or enterocolitis. In comparison with the non-EGID group, patients with EGID were younger at transplant (P ≤ 0.0001), transplanted more frequently due to biliary atresia (P ≤ 0.0001), and had higher rates of pretransplant allergy (P = 0.019). In the posttransplant period, they had higher rates of mammalian Target of Rapamycin inhibitor use (P = 0.006), Epstein-Barr virus viremia (P = 0.03), post-transplant lymphoproliferative disease (P = 0.005), and allergen sensitization (P ≤ 0.0001). In regression analysis, young age at transplant, age at diagnosis, pretransplant atopic dermatitis, and post-transplant lymphoproliferative disease were associated with an increased risk of EGID or EoE. Laboratory abnormalities such as anemia (P = 0.007), thrombocytosis (P = 0.012), and hypoalbuminemia (P = 0.031) were more commonly observed in the eosinophilic gastritis, gastroenteritis or enterocolitis group than in the EoE group. Following treatment, most patients had symptomatic resolution at 3 months and histologic resolution at 6 months postdiagnosis. Among the patients who had 5 years of follow-up, none recurred.

DISCUSSION

EGID is a common posttransplant diagnosis, which seems to affect patients who are transplanted earlier and who have pretransplant atopy. Posttransplant EGID is responsive to treatment, but as histologic remission occurs after symptomatic resolution, the decision to perform control endoscopy should be delayed.

Activation of mTORC1 by LSECtin in macrophages directs intestinal repair in inflammatory bowel disease

Damage to intestinal epithelial cells and the induction of cellular apoptosis are characteristics of inflammatory bowel disease. The C-type lectin receptor family member LSECtin promotes apoptotic cell clearance by macrophages and induces the production of anti-inflammatory/tissue growth factors, which direct intestinal repair in experimental colitis. However, the mechanisms by which the phagocytosis of apoptotic cells triggers the pro-repair function of macrophages remain largely undefined. Here, using immunoprecipitation in combination with mass spectrometry to identify LSECtin-interacting proteins, we found that LSECtin interacted with mTOR, exhibiting a role in activating mTORC1. Mechanistically, apoptotic cells enhance the interaction between LSECtin and mTOR, and increase the activation of mTORC1 induced by LSECtin in macrophages. Elevated mTORC1 signaling triggers macrophages to produce anti-inflammatory/tissue growth factors that contribute to the proliferation of epithelial cells and promote the reestablishment of tissue homeostasis. Collectively, our findings suggest that LSECtin-dependent apoptotic cell clearance by macrophages activates mTORC1, and thus contributes to intestinal regeneration and the remission of colitis.

MTOR suppresses autophagy-mediated production of IL25 in allergic airway inflammation

INTRODUCTION

Airway epithelial cells are recognised as an essential controller for the initiation and perpetuation of asthmatic inflammation, yet the detailed mechanisms remain largely unknown. This study aims to investigate the roles and mechanisms of the mechanistic target of rapamycin (MTOR)-autophagy axis in airway epithelial injury in asthma.

METHODS

We examined the MTOR-autophagy signalling in airway epithelium from asthmatic patients or allergic mice induced by ovalbumin or house dust mites, or in human bronchial epithelial (HBE) cells. Furthermore, mice with specific MTOR knockdown in airway epithelium and autophagy-related lc3b ^-/- mice were used for allergic models.

RESULTS

MTOR activity was decreased, while autophagy was elevated, in airway epithelium from asthmatic patients or allergic mice, or in HBE cells treated with IL33 or IL13. These changes were associated with upstream tuberous sclerosis protein 2 signalling. Specific MTOR knockdown in mouse bronchial epithelium augmented, while LC3B deletion diminished allergen-induced airway inflammation and mucus hyperproduction. The worsened inflammation caused by MTOR deficiency was also ameliorated in lc3b ^-/- mice. Mechanistically, autophagy was induced later than the emergence of allergen-initiated inflammation, particularly IL33 expression. MTOR deficiency increased, while knocking out of LC3B abolished the production of IL25 and the eventual airway inflammation on allergen challenge. Blocking IL25 markedly attenuated the exacerbated airway inflammation in MTOR-deficiency mice.

CONCLUSION

Collectively, these results demonstrate that allergen-initiated inflammation suppresses MTOR and induces autophagy in airway epithelial cells, which results in the production of certain proallergic cytokines such as IL25, further promoting the type 2 response and eventually perpetuating airway inflammation in asthma.

Conversion from tacrolimus to sirolimus as a treatment modality in de novo allergies and immune-mediated disorders in pediatric liver transplant recipients

De novo PTAID may develop in pediatric solid organ transplant recipients, have a diverse spectrum, and are occasionally treatment resistant. Previous reports showed resolution of immune cytopenias in solid organ transplant recipients following replacement of the calcineurin inhibitor tacrolimus with the mTOR inhibitor sirolimus. Herein we describe a retrospective review (2000-2017) of subjects who developed PTAID in whom immunosuppression was changed to sirolimus. Eight recipients (6 males) of either liver (n = 7) or multivisceral transplant (n = 1) suffered from severe, treatment-resistant PTAID and were switched from tacrolimus to sirolimus. The median age at transplant was 1 year (range 0.5-2.4 years). Six (75%) recipients developed de novo allergy and 2 immune-mediated diseases. The median age at presentation of PTAID was 2.7 (1.4-9) years at a median of 1.3 (0.25-8) years after transplantation. The median time from PTAID presentation to conversion to sirolimus was 1.8 (0.45-10) years. Complete resolution of symptoms was seen in 4 (50%) patients after a median of 12 (range 4-24) months including 2 patients with immune-mediated disease, 1 eczema, and 1 with eosinophilic colitis. One patient with multiple food allergies had a partial response and 3 (38%) had no response. None of the 8 recipients developed sirolimus-attributed adverse events or acute rejection during a median follow-up of 5 (0.6-8) years after the conversion. Immunosuppression conversion from tacrolimus to sirolimus can be an effective therapy in patients suffering severe or treatment-resistant PTAID, suggesting a potential role for tacrolimus in the pathogenesis of PTAID.

Anti-allergic effect of inotodiol, a lanostane triterpenoid from Chaga mushroom, via selective inhibition of mast cell function

Inotodiol is a lanostane triterpenoid found only in Chaga mushroom. In the previous study investigating anti-allergic effects of fractionated Chaga mushroom extracts, we have found evidence that purified inotodiol holds an activity to suppress the mast cell function in vivo. To address the therapeutic relevance of the finding, in this study, we investigated whether inotodiol could also alleviate allergy symptoms observed in a chicken ovalbumin (cOVA)-induced mouse model of food allergy. Like the crude 70% ethanol extract of Chaga mushroom (320 mg/kg), oral administration of inotodiol (20 mg/kg), regardless of whether that was for preventive or treatment purpose, resulted in a significant improvement in allergic symptoms and inflammatory lesions in the small intestine appearing after repeated oral challenge with cOVA. Despite the results that inotodiol (20 mg/kg) and the Chaga mushroom extract (320 mg/kg) took effect to a similar extent, immunological mechanisms underlying those effects were found to be distinct from each other. That is, the results obtained from several in vivo assays, including mast cell-mediated passive systemic anaphylaxis, activation/proliferation of adoptively transferred antigen-specific T cells and immunoglobulin (IgG1, IgE, IgA) production by antigen-specific B cells, illustrated that inotodiol selectively inhibited the mast cell function without having any noticeable effect on other immune responses while the crude Chaga mushroom extract indiscriminately suppressed diverse immune responses. The strong anti-allergic activity of inotodiol, along with its remarkable selectivity to mast cell, makes it an excellent therapeutic candidate for food allergy with both high efficacy and outstanding safety.

Co-delivery of allergen epitope fragments and R848 inhibits food allergy by inducing tolerogenic dendritic cells and regulatory T cells

BACKGROUND

Food allergy (FA) is a significant public health problem. The therapeutic efficacy for FA is unsatisfactory currently. The breakdown of intestinal immune tolerance is associated with the pathogenesis of FA. Therefore, it is of great significance to develop novel therapeutic methods to restore immune tolerance in treating FA.

METHODS

We proposed an oral administration strategy to treat FA by co-delivering food allergen epitope fragment (peptide: IK) and adjuvant R848 (TLR7 ligand) in the mPEG-PDLLA nanoparticles (PPLA-IK/R848 NPs). The generation of tolerogenic dendritic cells (DCs) and regulatory T cells (Tregs) induced by PPLA-IK/R848 NPs were evaluated in vitro and in vivo. The therapeutic effects of PPLA-IK/R848 NPs were also assessed in an OVA-induced FA model.

RESULTS

PPLA-IK/R848 NPs could efficiently deliver IK to DCs to drive DCs into the tolerogenic phenotypes and promote the differentiation of Tregs in vitro and in vivo, significantly inhibited FA responses through the recovery of intestinal immune tolerance.

CONCLUSION

Oral administration of PPLA-IK/R848 NPs could efficiently deliver IK and R848 to intestinal DCs and stimulate DCs into allergen tolerogenic phenotype. These tolerogenic DCs could promote the differentiation of Tregs, which significantly protected mice from food allergic responses. This study provided an efficient formulation to alleviate FA through the recovery of immune tolerance.

Traditional Tibetan medicine Anzhijinhua San attenuates ovalbumin-induced diarrhea by regulating the serotonin signaling system in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Tibetan medicine has been practiced for 3800 years. Anzhijinhua San (AZJHS), which is a traditional Tibetan medicine, has been effective in the treatment of indigestion, anorexia and cold diarrhea. However, the effects of AZJHS on allergic diarrhea have not been reported.

AIM OF THE STUDY

The aim of the present study was to elucidate the effect of AZJHS on experimental ovalbumin-induced diarrhea and elucidate its possible mechanism.

MATERIALS AND METHODS

Female BALB/c mice were sensitized by intraperitoneal injection with 50 μg ovalbumin (OVA) and 1 mg alum in saline twice during a 2-week period. From day 28, mice were orally challenged with OVA (50 mg) every other day for a total of ten times. AZJHS (46.8 and 468.0 mg/kg) was orally administered every other day from day 0-46. Food allergy symptoms were evaluated. OVA- specific IgE, 5-HT and its metabolites in serum were determined. Immunohistochemical and histopathology were performed in gastrointestinal tract tissues. 5-HT-related gene expression was assayed in the colon.

RESULTS

Severe symptoms of allergic diarrhea were observed in the model group (diarrhea, anaphylactic response, and rectal temperature). AZJHS (46.8 and 468.0 mg/kg) significantly reduced mouse diarrhea and significantly prevented the increases in OVA-specific IgE levels (P < 0.05), which challenge with OVA. AZJHS (46.8 and 468.0 mg/kg) significantly prevented the increases in 5-HT-positive cells. The nuclei of EC cells in the AZJHS (46.8 and 468.0 mg/kg) group increased in size and the secretory granules were fewer in number compared with those in the model group. AZJHS (46.8 and 468.0 mg/kg) significantly increased the relative fold changes of 5-HTP and 5-HT compared with the model group. The mRNA expression of the serotonin transporter (Sert) and serotonin receptor 3A (Htr3a) was significantly decreased after the 10th challenge with OVA, and AZJHS (46.8 and 468.0 mg/kg) significantly increased these levels.

CONCLUSIONS

We demonstrated that the administration of AZJHS attenuated OVA-induced diarrhea by regulating the serotonin pathway. These results indicated that AZJHS may be a potential candidate as an anti-allergic diarrhea agent.

Epigenome-wide association study reveals methylation pathways associated with childhood allergic sensitization

Epigenetic mechanisms integrate both genetic variability and environmental exposures. However, comprehensive epigenome-wide analysis has not been performed across major childhood allergic phenotypes. We examined the association of epigenome-wide DNA methylation in mid-childhood peripheral blood (Illumina HumanMethyl450K) with mid-childhood atopic sensitization, environmental/inhalant and food allergen sensitization in 739 children in two birth cohorts (Project Viva-Boston, and the Generation R Study-Rotterdam). We performed covariate-adjusted epigenome-wide association meta-analysis and employed pathway and regional analyses of results. Seven-hundred and five methylation sites (505 genes) were significantly cross-sectionally associated with mid-childhood atopic sensitization, 1411 (905 genes) for environmental and 45 (36 genes) for food allergen sensitization (FDR<0.05). We observed differential methylation across multiple genes for all three phenotypes, including genes implicated previously in innate immunity (DICER1), eosinophilic esophagitis and sinusitis (SIGLEC8), the atopic march (AP5B1) and asthma (EPX, IL4, IL5RA, PRG2, SIGLEC8, CLU). In addition, most of the associated methylation marks for all three phenotypes occur in putative transcription factor binding motifs. Pathway analysis identified multiple methylation sites associated with atopic sensitization and environmental allergen sensitization located in/near genes involved in asthma, mTOR signaling, and inositol phosphate metabolism. We identified multiple differentially methylated regions associated with atopic sensitization (8 regions) and environmental allergen sensitization (26 regions). A number of nominally significant methylation sites in the cord blood analysis were epigenome-wide significant in the mid-childhood analysis, and we observed significant methylation - time interactions among a subset of sites examined. Our findings provide insights into epigenetic regulatory pathways as markers of childhood allergic sensitization.

Attenuation of allergic responses following treatment with resveratrol in anaphylactic models and IgE-mediated mast cells

Resveratrol exists widely in plant species and has a variety of anti-oxidant, anti-inflammatory, and immunomodulatory properties. However, there have been few reports regarding its anti-food allergic activity. In this study, we demonstrated that resveratrol (isolated from Abies georgei) could decrease the release of β-hexosaminidase and histamine in rat basophilic leukemia-2H3 cells. Resveratrol was not only found to suppress the development of diarrhea, up-regulate the rectal temperature of ovalbumin-allergic mice, and decrease the serum level of specific immunoglobulin E, mouse mast cell protease-1 and histamine, but also found to decrease the population of dendritic cells, B cells and mast cells of ovalbumin -allergic mice in the spleen or mesenteric lymph node. Furthermore, resveratrol inhibited the release of β-hexosaminidase and histamine in bone marrow-derived cells and alleviated mast cell-mediated passive cutaneous anaphylaxis reactions. These findings indicated that resveratrol isolated from Abies georgei might have the potential to alleviate food hypersensitivity or allergic disease.

Germ-Free Mice Exhibit Mast Cells With Impaired Functionality and Gut Homing and Do Not Develop Food Allergy

Background: Mucosal mast cells (MC) are key players in IgE-mediated food allergy (FA). The evidence on the interaction between gut microbiota, MC and susceptibility to FA is contradictory.

Objective: We tested the hypothesis that commensal bacteria are essential for MC migration to the gut and their maturation impacting the susceptibility to FA.

Methods: The development and severity of FA symptoms was studied in sensitized germ-free (GF), conventional (CV), and mice mono-colonized with L. plantarum WCFS1 or co-housed with CV mice. MC were phenotypically and functionally characterized.

Results: Systemic sensitization and oral challenge of GF mice with ovalbumin led to increased levels of specific IgE in serum compared to CV mice. Remarkably, despite the high levels of sensitization, GF mice did not develop diarrhea or anaphylactic hypothermia, common symptoms of FA. In the gut, GF mice expressed low levels of the MC tissue-homing markers CXCL1 and CXCL2, and harbored fewer MC which exhibited lower levels of MC protease-1 after challenge. Additionally, MC in GF mice were less mature as confirmed by flow-cytometry and their functionality was impaired as shown by reduced edema formation after injection of degranulation-provoking compound 48/80. Co-housing of GF mice with CV mice fully restored their susceptibility to develop FA. However, this did not occur when mice were mono-colonized with L. plantarum.

Conclusion: Our results demonstrate that microbiota-induced maturation and gut-homing of MC is a critical step for the development of symptoms of experimental FA. This new mechanistic insight into microbiota-MC-FA axis can be exploited in the prevention and treatment of FA in humans.

Dihydromyricetin inhibited ovalbumin-induced mice allergic responses by suppressing the activation of mast cells

Dihydromyricetin (DMY) is a natural flavonoid compound derived from Lysionotus pauciflorus Maxim and has been found to possess therapeutic potential for allergic disease induced by food allergens.

Adjuvanted Immunotherapy Approaches for Peanut Allergy

Food allergies are a growing public health concern with an estimated 8% of US children affected. Peanut allergies are also on the rise and often do not spontaneously resolve, leaving individuals at-risk for potentially life-threatening anaphylaxis throughout their lifetime. Currently, two forms of peanut immunotherapy, oral immunotherapy (OIT) and epicutaneous immunotherapy (EPIT), are in Phase III clinical trials and have shown promise to induce desensitization in many subjects. However, there are several limitations with OIT and EPIT, such as allergic side effects, daily dosing requirements, and the infrequent outcome of long-term tolerance. Next-generation therapies for peanut allergy should aim to overcome these limitations, which may be achievable with adjuvanted immunotherapy. An adjuvant can be defined as anything that enhances, accelerates, or modifies an immune response to a particular antigen. Adjuvants may allow for lower doses of antigen to be given leading to decreased side effects; may only need to be administered every few weeks or months rather than daily exposures; and may induce a long-lasting protective effect. In this review article, we highlight examples of adjuvants and formulations that have shown pre-clinical efficacy in treating peanut allergy.

A histomorphometric classification system for normal and inflamed mouse duodenum-Quali-quantitative approach

Gut-associated intestinal lymphoid tissue, the largest secondary lymphoid organ in the human body, constantly samples antigens from the gut lumen, presenting as a default response the activation of TCD4⁺ FOXP3⁺ regulatory T cells that secrete a profile of anti-inflammatory cytokines maintaining gut homeostasis denominated from an immunological perspective as mucosal tolerance. However, when antigens are sampled in an inflammatory setting, the immune response may either be protective, in the case of harmful pathogens, or cause further inflammatory reactions as in food allergy, inflammatory bowel diseases, coeliac disease or food protein-induced enterocolitis syndrome. Therefore, there is a need for accurate and consistent experimental models. However, a drawback in comparing these models is the lack of a classification system similar to that which is already used for humans. Thus, the aim of this work was to propose a classification system of the small intestinal histomorphology in experimental mice. To do this we used a mouse antigen-specific gut inflammation model developed by our research group. Duodenum sections stained with haematoxylin-eosin and Alcian blue were scanned using the APERIO scanning system and analysed with the ImageScope^® software. The evaluated parameters were villus area, villus height and width, enterocyte count, mononuclear intra-epithelial leucocyte and goblet cell counts, and architectural and cellular ratios. Food-sensitized animals challenged with a diet containing the corresponding food allergen presented, as for humans, time-dependent shortened and widened villi accompanied by leucocyte infiltrate and loss of goblet cells. With these data, we were able to establish a classification system for experimental intestinal inflammation in mice thus permitting better comparisons among and between experiments than has been possible previously.

Autophagy mediates epithelial cytoprotection in eosinophilic oesophagitis

OBJECTIVE

The influence of eosinophilic oesophagitis (EoE)-associated inflammation upon oesophageal epithelial biology remains poorly understood. We investigated the functional role of autophagy in oesophageal epithelial cells (keratinocytes) exposed to the inflammatory EoE milieu.

DESIGN

Functional consequences of genetic or pharmacological autophagy inhibition were assessed in endoscopic oesophageal biopsies, human oesophageal keratinocytes, single cell-derived ex vivo murine oesophageal organoids as well as a murine model recapitulating EoE-like inflammation and basal cell hyperplasia. Gene expression, morphological and functional characterisation of autophagy and oxidative stress were performed by transmission electron microscopy, immunostaining, immunoblotting, live cell imaging and flow cytometry.

RESULTS

EoE-relevant inflammatory conditions promoted autophagy and basal cell hyperplasia in three independent murine EoE models and oesophageal organoids. Inhibition of autophagic flux via chloroquine treatment augmented basal cell hyperplasia in these model systems. Oesophageal keratinocytes stimulated with EoE-relevant cytokines, including tumour necrosis factor-α and interleukin-13 exhibited activation of autophagic flux in a reactive oxygen species-dependent manner. Autophagy inhibition via chloroquine treatment or depletion of Beclin-1 or ATG-7, augmented oxidative stress induced by EoE-relevant stimuli in murine EoE, oesophageal organoids and human oesophageal keratinocytes. Oesophageal epithelia of paediatric EoE patients with active inflammation displayed increased autophagic vesicle content compared with normal and EoE remission subjects. Functional flow cytometric analysis revealed autophagic flux in human oesophageal biopsies.

CONCLUSIONS

Our findings reveal for the first time that autophagy may function as a cytoprotective mechanism to maintain epithelial redox balance and homeostasis under EoE inflammation-associated stress, providing mechanistic insights into the role of autophagy in EoE pathogenesis.

Eucheuma cottonii Sulfated Oligosaccharides Decrease Food Allergic Responses in Animal Models by Up-regulating Regulatory T (Treg) Cells

In the present study, the anti-food allergy activity of Eucheuma cottonii sulfated oligosaccharide (ESO) was investigated. ESO was obtained by enzymatic degradation and purified by column chromatography. RBL-2H3 cells and BALB/c mouse model were used to test the anti-food allergy activity of ESO. The effects of ESO on the regulatory T (Treg) cells and bone marrow-derived mast cells (BMMCs) were investigated by flow cytometry. The results of in vivo assay showed that ESO decreased the levels of mast cell protease-1 and histamine and inhibited the levels of specific IgE by 77.7%. In addition, the production of interleukin (IL)-4 and IL-13 was diminished in the ESO groups compared to the non-ESO-treated group. Furthermore, ESO could up-regulate Treg cells by 22.2-97.1%. In conclusion, ESO decreased the allergy response in mice by reducing basophil degranulation, up-regulating Treg cells via Forkhead box protein 3 (Foxp3), and releasing IL-10. ESO may have preventive and therapeutic potential in allergic disease.

Intestinal Microbiota-Derived GABA Mediates Interleukin-17 Expression during Enterotoxigenic Escherichia coli Infection

Intestinal microbiota has critical importance in pathogenesis of intestinal infection; however, the role of intestinal microbiota in intestinal immunity during enterotoxigenic Escherichia coli (ETEC) infection is poorly understood. The present study tested the hypothesis that the intestinal microbiota is associated with intestinal interleukin-17 (IL-17) expression in response to ETEC infection. Here, we found ETEC infection induced expression of intestinal IL-17 and dysbiosis of intestinal microbiota, increasing abundance of γ-aminobutyric acid (GABA)-producing Lactococcus lactis subsp. lactis. Antibiotics treatment in mice lowered the expression of intestinal IL-17 during ETEC infection, while GABA or L. lactis subsp. lactis administration restored the expression of intestinal IL-17. L. lactis subsp. lactis administration also promoted expression of intestinal IL-17 in germ-free mice during ETEC infection. GABA enhanced intestinal IL-17 expression in the context of ETEC infection through activating mechanistic target of rapamycin complex 1 (mTORC1)-ribosomal protein S6 kinase 1 (S6K1) signaling. GABA-mTORC1 signaling also affected intestinal IL-17 expression in response to Citrobacter rodentium infection and in drug-induced model of intestinal inflammation. These findings highlight the importance of intestinal GABA signaling in intestinal IL-17 expression during intestinal infection and indicate the potential of intestinal microbiota-GABA signaling in IL-17-associated intestinal diseases.

Dietary interventions that reduce mTOR activity rescue autistic-like behavioral deficits in mice

Enhanced mammalian target of rapamycin (mTOR) signaling in the brain has been implicated in the pathogenesis of autism spectrum disorder (ASD). Inhibition of the mTOR pathway improves behavior and neuropathology in mouse models of ASD containing mTOR-associated single gene mutations. The current study demonstrated that the amino acids histidine, lysine, threonine inhibited mTOR signaling and IgE-mediated mast cell activation, while the amino acids leucine, isoleucine, valine had no effect on mTOR signaling in BMMCs. Based on these results, we designed an mTOR-targeting amino acid diet (Active 1 diet) and assessed the effects of dietary interventions with the amino acid diet or a multi-nutrient supplementation diet (Active 2 diet) on autistic-like behavior and mTOR signaling in food allergic mice and in inbred BTBR T+Itpr3tf/J mice. Cow's milk allergic (CMA) or BTBR male mice were fed a Control, Active 1, or Active 2 diet for 7 consecutive weeks. CMA mice showed reduced social interaction and increased self-grooming behavior. Both diets reversed behavioral impairments and inhibited the mTOR activity in the prefrontal cortex and amygdala of CMA mice. In BTBR mice, only Active 1 diet reduced repetitive self-grooming behavior and attenuated the mTOR activity in the prefrontal and somatosensory cortices. The current results suggest that activated mTOR signaling pathway in the brain may be a convergent pathway in the pathogenesis of ASD bridging genetic background and environmental triggers (food allergy) and that mTOR over-activation could serve as a potential therapeutic target for the treatment of ASD.

Anti-Food Allergic Activity of Sulfated Polysaccharide from Gracilaria lemaneiformis is Dependent on Immunosuppression and Inhibition of p38 MAPK

Polysaccharides from Gracilaria lemaneiformis in particular possess various bioactive functions, but their antiallergic activity remains incompletely defined. Sulfated polysaccharide from Gracilaria lemaneiformis (GLSP) was obtained by water extraction and ethanol precipitation followed by column chromatography. BALB/c mice, RBL-2H3, and KU812 cells were used for verifying the anti food allergic activity of GLSP. According to the results of mice experiment, GLSP was able to alleviate allergy symptoms, to reduce TM-specific IgE and IgG1, to suppress Th2 cell polarization, and to promote the function of regulatory T (Treg) cells. In addition, GLSP had the ability to inhibit the function of RBL-2H3 cells. Furthermore, GLSP inhibited the activation of KU812 via suppression of p38 mitogen-activated protein kinase (MAPK). In conclusion, immunosuppression as well as the reduction in the level of p38 MAPK may contribute to GLSP's putative activity against food allergy. GLSP may be used as a functional food component for allergic patients.

Intranasal exposure to monoclonal antibody Fab fragments to Japanese cedar pollen Cry j1 suppresses Japanese cedar pollen-induced allergic rhinitis

BACKGROUND AND PURPOSE

Fab fragments (Fabs) of antibodies have the ability to bind to specific allergens but lack the Fc portion that exerts effector functions via binding to receptors including FcεR1 on mast cells. In the present study, we investigated whether intranasal administration of the effector function-lacking Fabs of a monoclonal antibody IgG1 (mAb, P1-8) to the major allergen Cry j1 of Japanese cedar pollen (JCP) suppressed JCP-induced allergic rhinitis in mice.

EXPERIMENTAL APPROACH

Balb/c mice sensitized with JCP on days 0 and 14 were challenged intranasally with the pollen on days 28, 29, 30 and 35. Fabs prepared by the digestion of P1-8 with papain were also administered intranasally 15 min before each JCP challenge.

KEY RESULTS

Intranasal administration of P1-8 Fabs was followed by marked suppression of sneezing and nasal rubbing in mice with JCP-induced allergic rhinitis. The suppression of these allergic symptoms by P1-8 Fabs was associated with decreases in mast cells and eosinophils and decreased hyperplasia of goblet cells in the nasal mucosa.

CONCLUSIONS AND IMPLICATIONS

These results demonstrated that intranasal exposure to P1-8 Fabs was effective in suppressing JCP-induced allergic rhinitis in mice, suggesting that allergen-specific mAb Fabs might be used as a tool to regulate allergic pollinosis.

The rise of food allergy: Environmental factors and emerging treatments

Food allergy has rapidly increased in prevalence, suggesting an important role for environmental factors in disease susceptibility. The immune response of food allergy is characterized by IgE production, and new findings from mouse and human studies indicate an important role of the cytokine IL-9, which is derived from both T cells and mast cells, in disease manifestations. Emerging evidence suggests that route of exposure to food, particularly peanut, is important. Exposure through the skin promotes sensitization while early exposure through the gastrointestinal tract promotes tolerance. Evidence from mouse studies indicate a role of the microbiome in development of food allergy, which is supported by correlative human studies showing a dysbiosis in food allergy. There is no approved treatment for food allergy, but emerging therapies are focused on allergen immunotherapy to provide desensitization, while pre-clinical studies are focused on using adjuvants or novel delivery approaches to improve efficacy and safety of immunotherapy.

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Emerging evidence suggests that route of exposure to food allergens in early life determines sensitization versus tolerance.

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The microbiota and dietary factors appear to play a key role in susceptibility to food allergy.

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Immunotherapy applied via different routes is currently the most promising form of experimental treatment for food allergy.

IgA directly inhibits antigen-dependent B cell activation following distinctive distribution of the antigen in mice

CONTEXT

Serum IgA suppresses immune responses when exposed to antigens recognized by the antibody; however, the underlying mechanism remains unclear.

OBJECTIVE

We herein clarified the relationships between changes in antigen distribution and antigen-dependent B cell activation in the presence or absence of IgA against the antigen in mice.

MATERIALS AND METHODS

DBA/1J and HR-1 mice were intravenously injected with ovalbumin (OVA) and anti-OVA monoclonal IgA OA-4. The distribution of the antigen and B cell responses were measured.

RESULTS

B cell activation by injected OVA, namely, increases in anti-OVA IgG production and the populations of B220(+)GL7(+) and B220(+)CD69(high) splenocytes, was diminished by the co-injection of OA-4. Co-injected OA-4 increased OVA in the serum as well as in the bile and gut. This was coincident with its decrease in the urine due to the inhibition of OVA monomer secretion through the formation of immune complexes. The apparent similarities in the association between fluorescein isothiocyanate (FITC)-OVA and splenic B cells in the presence and absence of OA-4 in vivo appeared to be attributed to compensation between the two effects of OA-4; an increase in serum OVA in vivo and inhibition of the association between OVA and B cells, as suggested by in vitro experiments.

DISCUSSION

Based on these results, the stimulation of B cells by OVA may be directly reduced, at least partly, by the neutralization of OVA by OA-4.

CONCLUSION

IgA may be an effective drug for the treatment of immune disorders due to its ability to blunt antigen-specific B cell activation.

Attenuation of food allergy symptoms following treatment with human milk oligosaccharides in a mouse model

BACKGROUND

The prebiotic nature of human milk oligosaccharides (HMOs) and increasing evidence of direct immunomodulatory effects of these sugars suggest that they may have some therapeutic potential in allergy. Here, we assess the effect of two HMOs, 2'-fucosyllactose and 6'-sialyllactose, on symptomatology and immune responses in an ovalbumin-sensitized mouse model of food allergy.

METHODS

The effects of oral treatment with 2'-fucosyllactose and 6'-sialyllactose on anaphylactic symptoms induced by oral ovalbumin (OVA) challenge in sensitized mice were investigated. Mast cell functions in response to oral HMO treatment were also measured in the passive cutaneous anaphylaxis model, and direct effects on IgE-mediated degranulation of mast cells were assessed.

RESULTS

Daily oral treatment with 2'-fucosyllactose or 6'-sialyllactose attenuated food allergy symptoms including diarrhea and hypothermia. Treatment with HMOs also suppressed antigen-induced increases in mouse mast cell protease-1 in serum and mast cell numbers in the intestine. These effects were associated with increases in the CD4(+) CD25(+) IL-10(+) cell populations in the Peyer's patches and mesenteric lymph nodes, while 6'-sialyllactose also induced increased IL-10 and decreased TNF production in antigen-stimulated splenocytes. Both 2'-fucosyllactose and 6'-sialyllactose reduced the passive cutaneous anaphylaxis response, but only 6'-sialyllactose directly inhibited mast cell degranulation in vitro, at high concentrations.

CONCLUSIONS

Our results suggest that 2'-fucosyllactose and 6'-sialyllactose reduce the symptoms of food allergy through induction of IL-10(+) T regulatory cells and indirect stabilization of mast cells. Thus, human milk oligosaccharides may have therapeutic potential in allergic disease.

Rapamycin inhibition of eosinophil differentiation attenuates allergic airway inflammation in mice

BACKGROUND AND OBJECTIVE

The mammalian target of rapamycin (mTOR) signalling pathway regulates immune responses, and promotes cell growth and differentiation. Inhibition of mTOR with rapamycin modulates allergic asthma, while the underlying molecular mechanisms remain elusive. Here, we demonstrate that rapamycin, effectively inhibits eosinophil differentiation, contributing to its overall protective role in allergic airway inflammation.

METHODS

Rapamycin was administered in a mouse model of ovalbumin-induced allergic airway inflammation, and the eosinophil differentiation was analysed in vivo and in vitro.

RESULTS

Rapamycin significantly attenuated allergic airway inflammation and markedly decreased the amount of eosinophils in local airways, peripheral blood and bone marrow, independently of levels of interleukin-5 (IL-5). In vitro colony forming unit assay and liquid culture demonstrated that rapamycin directly inhibited IL-5-induced eosinophil differentiation. In addition, rapamycin reduced the production of IL-6 and IL-13 by eosinophils. Rapamycin was also capable of reducing the eosinophil levels in IL-5 transgenic NJ.1638 mice, again regardless of the constitutive high levels of IL-5. Interestingly, rapamycin inhibition of eosinophil differentiation in turn resulted in an accumulation of eosinophil lineage-committed progenitors in bone marrow.

CONCLUSIONS

Altogether these results clearly demonstrate a direct inhibitory role of rapamycin in eosinophil differentiation and function, and reemphasize the importance of rapamycin and possibly, mTOR, in allergic airway disease.

IgA attenuates anaphylaxis and subsequent immune responses in mice: possible application of IgA to vaccines

Administration of the influenza vaccination to patients with an egg allergy is major health concern. Contaminating egg antigens occasionally induce severe anaphylactic shock in these patients following administration of the vaccination; therefore, the development of a safer vaccination is needed. In the present study, we investigated whether a mixture of four newly and previously generated anti-ovalbumin (OVA) IgA monoclonal antibodies (mAbs) could inhibit both anaphylactic shock upon a subcutaneous OVA challenge and subsequent further sensitization against OVA in passively anti-OVA IgE-sensitized mice and actively sensitized mice with an injection of OVA. The prevention of anaphylaxis by anti-OVA IgA mAbs was suggested to be mediated through the inhibition of OVA binding to allergenic antibodies such as anti-OVA IgE on mast cells and deceleration of the rate of OVA penetration from the injected site into the systemic circulation. Anti-OVA IgA mAbs inhibited further sensitization against OVA in mice actively sensitized with OVA, but did not affect sensitization against the unrelated antigen, phosphorylcholine-keyhole limpet hemocyanin co-injected with OVA. Our findings indicate that adding the anti-egg antigen IgA to the influenza vaccine should reduce not only the risk of inducing anaphylactic shock, but also undesired further sensitization against egg antigens following the vaccination without affecting the intended beneficial effect of the vaccine, namely the upregulation of immune responses to influenza viruses.

Preventive effects of skullcap (Scutellaria baicalensis) extract in a mouse model of food allergy

ETHNOPHARMACOLOGICAL RELEVANCE

Food allergy, which accompanies acute symptoms such as pruritus, vomiting, diarrhea, and lethal anaphylactic shock is an increasing clinical problem. Skullcap (Scutellaria baicalensis Georgi) has been widely used as a traditional herbal medicine to treat inflammation, cancer, and allergy, but its effects in treating food allergy are not yet known.

MATERIALS AND METHODS

To examine the effect of skullcap on food allergy, female BALB/c mice were sensitized with 20 μg OVA and 2mg alum by intraperitoneal injection on day 0. From day 17, mice were orally challenged with OVA (50 mg) in saline every 3 days, for a total of six times. To investigate the preventive effect, skullcap (25 mg/kg) was orally administered every day from day 17 to 34.

RESULTS

Food allergy symptoms were evaluated by the criteria for diarrhea, anaphylactic response, and rectal temperature. Severe symptoms of food allergy were observed in the sham group (diarrhea, 3 points; anaphylactic response, 2.6 points; rectal temperature, -8.36 °C. In contrast, the skullcap treatment group had a significantly suppressed OVA-induced anaphylactic response (1.3 points) and rectal temperature (-4.76°C). Moreover, both OVA-specific IgE, Th17 cytokine (IL-17), and Th2-related cytokines (IL-4, IL-5, IL-10, and IL-13), which increased with food allergy, were significantly inhibited by skullcap treatment.

CONCLUSION

We demonstrate that the administration of skullcap attenuates OVA-induced food allergy symptoms through regulating systemic immune responses of Th cells. These results indicate that skullcap may be a potential candidate as a preventive agent for food allergy.

Food allergy: Insights into etiology, prevention, and treatment provided by murine models

Food allergy is a rapidly growing public health concern because of its increasing prevalence and life-threatening potential. Animal models of food allergy have emerged as a tool for identifying mechanisms involved in the development of sensitization to normally harmless food allergens, as well as delineating the critical immune components of the effector phase of allergic reactions to food. However, the role animal models might play in understanding human diseases remains contentious. This review summarizes how animal models have provided insights into the etiology of human food allergy, experimental corroboration for epidemiologic findings that might facilitate prevention strategies, and validation for the utility of new therapies for food allergy. Improved understanding of food allergy from the study of animal models together with human studies is likely to contribute to the development of novel strategies to prevent and treat food allergy.

Future Therapies for IgE-Mediated Food Allergy

Food allergy is prevalent, affecting approximately 4-8% of children. There is no currently approved treatment for food allergy, and while strict allergen avoidance is recommended it is difficult to achieve and therefore accidental exposures and reactions are common. There is an urgent need for the development of therapeutic approaches that will improve the health and quality of life of children with food allergy. The majority of current clinical research focus is on specific food allergen immunotherapy through oral, sublingual, or epicutaneous routes. Pre-clinical research has focused on making improvements to the safety and efficacy of allergen immunotherapy through modifications of allergen structure and addition of immuno-modulatory factors. The number of novel therapeutics for food allergy reaching the level of clinical trials remains disappointingly low, and there is a need for an expansion of pre-clinical research to provide safe, practical and novel approaches to the treatment of food allergy.

Remission of food allergy by the Janus kinase inhibitor ruxolitinib in mice

To clarify the role of Janus kinase (JAK) in and the efficacy of JAK inhibitors on food allergy, we investigated the effect of the clinically available JAK inhibitor ruxolitinib on mouse food allergy and the functions of cultured mast cells in vitro. Anaphylactic symptoms including diarrhea and decreases in body temperature pursuant to oral ovalbumin (OVA) challenges in food allergy mice were attenuated by the daily oral administration of ruxolitinib. This drug inhibited increases in mouse mast cell protease-1 concentrations in the serum and mast cell numbers in the intestines of these mice as well as degranulation, IL-13 production, and the spontaneous and IL-9-dependent survival of mouse bone marrow-derived mast cells in spite of the absence of an effect of ruxolitinib on passive systemic anaphylaxis. Anti-OVA IgG2a, IgE, and IgG1 serum levels and the release of IFN-γ, IL-4, IL-9, and IL-10 from the OVA-restimulated splenocytes of food allergy mice were also decreased by the treatment. Moreover, ruxolitinib administration to mice that had already exhibited anaphylactic responses to previous challenges reduced anaphylactic responses to further oral OVA challenges, which suggested that ruxolitinib has a therapeutic potential on food allergy. Our results showed that ruxolitinib remitted food allergy in mice mainly through immunosuppression and the prevention of mast cell hyperplasia, and partially through the inhibition of mast cell activation. We consider JAK inhibition to be a promising strategy for the prevention of food allergy, and ruxolitinib along with its derivatives inhibiting JAK as good candidates for therapeutic drugs to treat food allergy.

Tolerogenic CX3CR1+ B cells suppress food allergy-induced intestinal inflammation in mice

BACKGROUND

B lymphocytes are an important cell population of the immune regulation; their role in the regulation of food allergy has not been fully understood yet.

OBJECTIVE

This study aims to investigate the role of a subpopulation of tolerogenic B cells (TolBC) in the generation of regulatory T cells (Treg) and in the suppression of food allergy-induced intestinal inflammation in mice.

METHODS

The intestinal mucosa-derived CD5+ CD19+ CX3CR1+ TolBCs were characterized by flow cytometry; a mouse model of intestinal T helper (Th)2 inflammation was established to assess the immune regulatory role of this subpopulation of TolBCs.

RESULTS

A subpopulation of CD5+ CD19+ CX3CR1+ B cells was detected in the mouse intestinal mucosa. The cells also expressed transforming growth factor (TGF)-β and carried integrin alpha v beta 6 (αvβ6). Exposure to recombinant αvβ6 and anti-IgM antibody induced naive B cells to differentiate into the TGF-β-producing TolBCs. Coculturing this subpopulation of TolBCs with Th0 cells generated CD4+ CD25+ Foxp3+ Tregs. Adoptive transfer with the TolBCs markedly suppressed the food allergy-induced intestinal Th2 pattern inflammation in mice.

CONCLUSIONS

CD5+ CD19+ CX3CR1+ TolBCs are capable of inducing Tregs in the intestine and suppress food allergy-related Th2 pattern inflammation in mice.

mTOR is a key modulator of ageing and age-related disease

Many experts in the biology of ageing believe that pharmacological interventions to slow ageing are a matter of 'when' rather than 'if'. A leading target for such interventions is the nutrient response pathway defined by the mechanistic target of rapamycin (mTOR). Inhibition of this pathway extends lifespan in model organisms and confers protection against a growing list of age-related pathologies. Characterized inhibitors of this pathway are already clinically approved, and others are under development. Although adverse side effects currently preclude use in otherwise healthy individuals, drugs that target the mTOR pathway could one day become widely used to slow ageing and reduce age-related pathologies in humans.