Ovalbumin-Induced Epithelial Activation Directs Monocyte-Derived Dendritic Cells to Instruct Type 2 Inflammation in T Cells Which Is Differentially Modulated by 2'-Fucosyllactose and 3-Fucosyllactose

Atopic dermatitis and IgE-mediated food allergy: Common biologic targets for therapy and prevention

OBJECTIVE

To highlight common mechanistic targets for the treatment of atopic dermatitis (AD) and IgE-mediated food allergy (IgE-FA) with potential to be effective for both diseases and prevent atopic progression.

DATA SOURCES

Data sources were PubMed searches or National Clinical Trials (NCT)-registered clinical trials related to AD, IgE-FA, and other atopic conditions, especially focused on the pediatric population.

STUDY SELECTIONS

Human seminal studies and/or articles published in the past decade were emphasized with reference to preclinical models when relevant. NCT-registered clinical trials were filtered by inclusion of pediatric subjects younger than 18 years with special focus on children younger than 12 years as a critical period when AD and IgE-FA diseases may often be concurrent.

RESULTS

AD and IgE-FA share several pathophysiologic features, including epithelial barrier dysfunction, innate and adaptive immune abnormalities, and microbial dysbiosis, which may be critical for the clinical progression between these diseases. Revolutionary advances in targeted biologic therapies have shown the benefit of inhibiting type 2 immune responses, using dupilumab (anti-interleukin-4Rα) or omalizumab (anti-IgE), to potentially reduce symptom burden for both diseases in pediatric populations. Although the potential for biologics to promote disease remission (AD) or sustained unresponsiveness (IgE-FA) remains unclear, the refinement of biomarkers to predict infants at risk for atopic disorders provides promise for prevention through timely intervention.

CONCLUSION

AD and IgE-FA exhibit common features that may be leveraged to develop biologic therapeutic strategies to treat both conditions and even prevent atopic progression. Future studies should be designed with consistent age stratification in the pediatric population and standardized regimens of adjuvant oral immunotherapy or dose escalation (IgE-FA) to improve cross-study interpretation.

Recent advances of 3-fucosyllactose in health effects and production

Human milk oligosaccharides (HMOs) have been recognized as gold standard for infant development. 3-Fucosyllactose (3-FL), being one of the Generally Recognized as Safe HMOs, represents a core trisaccharide within the realm of HMOs; however, it has received comparatively less attention in contrast to extensively studied 2'-fucosyllactose. The objective of this review is to comprehensively summarize the health effects of 3-FL, including its impact on gut microbiota proliferation, antimicrobial effects, immune regulation, antiviral protection, and brain maturation. Additionally, the discussion also covers the commercial application and regulatory approval status of 3-FL. Lastly, an organized presentation of large-scale production methods for 3-FL aims to provide a comprehensive guide that highlights current strategies and challenges in optimization.

Mustard seed major allergen Sin a1 activates intestinal epithelial cells and also dendritic cells that drive type 2 immune responses

Mustard seeds belong to the food category of mandatory labelling due to the severe reactions they can trigger in allergic patients. However, the mechanisms underlying allergic sensitization to mustard seeds are poorly understood. The aim of this work is to study type 2 immune activation induced by the mustard seed major allergen Sin a1 via the intestinal mucosa, employing an in vitro model mimicking allergen exposure via the intestinal epithelial cells (IECs). Sin a1 was isolated from the total protein extract and exposed to IEC, monocyte derived dendritic cells (DCs) or IEC/DC co-cultures. A system of consecutive co-cultures was employed to study the generic capacity of Sin a1 to induce type 2 activation leading to sensitization: IEC/DC, DC/T-cell, T/B-cell and stem cell derived mast cells (MCs) derived from healthy donors. Immune profiles were determined by ELISA and flow cytometry. Sin a1 activated IEC and induced type-2 cytokine secretion in IEC/DC co-culture or DC alone (IL-15, IL-25 and TSLP), and primed DC induced type 2 T-cell skewing. IgG secretion in the T-cell/B-cell phase was enhanced in the presence of Sin a1 in the first stages of the co-culture. Anti-IgE did not induce degranulation but promoted IL-13 and IL-4 release by MC primed with the supernatant from B-cells co-cultured with Sin a1-IEC/DC or -DC primed T-cells. Sin a1 enhanced the release of type-2 inflammatory mediators by epithelial and dendritic cells; the latter instructed generic type-2 responses in T-cells that resulted in B-cell activation, and finally MC activation upon anti-IgE exposure. This indicates that via activation of IEC and/or DC, mustard seed allergen Sin a1 is capable of driving type 2 immunity which may lead to allergic sensitization.

Allergenic Shrimp Tropomyosin Distinguishes from a Non-Allergenic Chicken Homolog by Pronounced Intestinal Barrier Disruption and Downstream Th2 Responses in Epithelial and Dendritic Cell (Co)Culture

BACKGROUND

Tropomyosins (TM) from vertebrates are generally non-allergenic, while invertebrate homologs are potent pan-allergens. This study aims to compare the risk of sensitization between chicken TM and shrimp TM through affecting the intestinal epithelial barrier integrity and type 2 mucosal immune activation.

METHODS

Epithelial activation and/or barrier effects upon exposure to 2-50 μg/mL chicken TM, shrimp TM or ovalbumin (OVA) as a control allergen, were studied using Caco-2, HT-29MTX, or HT-29 intestinal epithelial cells. Monocyte-derived dendritic cells (moDC), cocultured with HT-29 cells or moDC alone, were exposed to 50 μg/mL chicken TM or shrimp TM. Primed moDC were cocultured with naïve Th cells. Intestinal barrier integrity (TEER), gene expression, cytokine secretion and immune cell phenotypes were determined in these human in vitro models.

RESULTS

Shrimp TM, but not chicken TM or OVA exposure, profoundly disrupted intestinal barrier integrity and increased alarmin genes expression in Caco-2 cells. Proinflammatory cytokine secretion in HT-29 cells was only enhanced upon shrimp TM or OVA, but not chicken TM, exposure. Shrimp TM enhanced the maturation of moDC and chemokine secretion in the presence or absence of HT-29 cells, while only in the absence of epithelial cells chicken TM activated moDC. Direct exposure of moDC to shrimp TM increased IL13 and TNFα secretion by Th cells cocultured with these primed moDC, while shrimp TM exposure via HT-29 cells cocultured with moDC sequentially increased IL13 expression and IL4 secretion in Th cells.

CONCLUSIONS

Shrimp TM, but not chicken TM, disrupted the epithelial barrier while triggering type 2 mucosal immune activation, both of which are key events in allergic sensitization.

Unraveling the gut-Lung axis: Exploring complex mechanisms in disease interplay

The link between gut and lung starts as early as during organogenesis. Even though they are anatomically distinct, essential bidirectional crosstalk via complex mechanisms supports GLA. Emerging studies have demonstrated the association of gut and lung diseases via multifaceted mechanisms. Advancements in omics and metagenomics technologies revealed a potential link between gut and lung microbiota, adding further complexity to GLA. Despite substantial studies on GLA in various disease models, mechanisms beyond microbial dysbiosis regulating the interplay between gut and lung tissues during disease conditions are not thoroughly reviewed. This review outlines disease specific GLA mechanisms, emphasizing research gaps with a focus on gut-to-lung direction based on current GLA literature. Moreover, the review discusses potential gut microbiota and their products like metabolites, immune modulators, and non-bacterial contributions as a basis for developing treatment strategies for lung diseases. Advanced experimental methods, modern diagnostic tools, and technological advancements are also highlighted as crucial areas for improvement in developing novel therapeutic approaches for GLA-related diseases. In conclusion, this review underscores the importance of exploring additional mechanisms within the GLA to gain a deeper understanding that could aid in preventing and treating a wide spectrum of lung diseases.

Butyrate interacts with the effects of 2'FL and 3FL to modulate in vitro ovalbumin-induced immune activation, and 2'FL lowers mucosal mast cell activation in a preclinical model for hen's egg allergy

Background

Early life provides a window of opportunity to prevent allergic diseases. With a prevalence of 0.5-2% in infants, hen's egg allergy is one of the most common food allergies. The immunomodulatory effects of human milk oligosaccharides (HMOs), 2'-fucosyllactose (2'FL), and 3-fucosyllactose (3FL) were studied in an in vitro mucosal immune model and an in vivo murine model for hen's egg (ovalbumin) allergy.

Methods

Intestinal epithelial cell (IEC)/dendritic cell (DC) and DC/T cell cocultures were used to expose IECs to ovalbumin (OVA) in an in vitro mucosal immune model. The effects of epithelial pre-incubation with 0.1% 2'FL or 3FL and/or 0.5 mM butyrate were studied. Three- to four-weeks-old female C3H/HeOuJ mice were fed AIN93G diets containing 0.1-0.5% 2'FL or 3FL 2 weeks before and during OVA sensitization and challenge. Allergic symptoms and systemic and local immune parameters were assessed.

Results

Exposing IECs to butyrate in vitro left the IEC/DC/T cell cross-talk unaffected, while 2'FL and 3FL showed differential immunomodulatory effects. In 3FL exposed IEC-DC-T cells, the secretion of IFNγ and IL10 was enhanced. This was observed upon pre-incubation of IECs with 2'FL and butyrate as well, but not 2'FL alone. The presence of butyrate did not affect OVA activation, but when combined with 3FL, an increase in IL6 release from DCs was observed (p < 0.001). OVA allergic mice receiving 0.5% 3FL diet had a lower %Th2 cells in MLNs, but the humoral response was unaltered compared to control mice. OVA-allergic mice receiving 0.1 or 0.5% 2'FL diets had lower serum levels of OVA-IgG2a (p < 0.05) or the mast cell marker mMCP1, in association with increased concentration of cecal short-chain fatty acids (SCFAs) (p < 0.05).

Conclusion

In vitro butyrate exposure promotes the development of a downstream type 1 and regulatory response observed after 2'FL exposure. 2'FL and 3FL differentially modulate ovalbumin-induced mucosal inflammation predominantly independent of butyrate. Mice receiving dietary 3FL during ovalbumin sensitization and challenge had lowered Th2 activation while the frequency of Treg cells was enhanced. By contrast, 2'FL improved the humoral immune response and suppressed mast cell activation in association with increased SCFAs production in the murine model for hen's egg allergy.

Human Milk Oligosaccharides: A Critical Review on Structure, Preparation, Their Potential as a Food Bioactive Component, and Future Perspectives

Human milk is the gold standard for infant feeding. Human milk oligosaccharides (HMOs) are a unique group of oligosaccharides in human milk. Great interest in HMOs has grown in recent years due to their positive effects on various aspects of infant health. HMOs provide various physiologic functions, including establishing a balanced infant's gut microbiota, strengthening the gastrointestinal barrier, preventing infections, and potential support to the immune system. However, the clinical application of HMOs is challenging due to their specificity to human milk and the difficulties and high costs associated with their isolation and synthesis. Here, the differences in oligosaccharides in human and other mammalian milk are compared, and the synthetic strategies to access HMOs are summarized. Additionally, the potential use and molecular mechanisms of HMOs as a new food bioactive component in different diseases, such as infection, necrotizing enterocolitis, diabetes, and allergy, are critically reviewed. Finally, the current challenges and prospects of HMOs in basic research and application are discussed.

An advanced in vitro human mucosal immune model to predict food sensitizing allergenicity risk: A proof of concept using ovalbumin as model allergen

Background

The global demand of sustainable food sources leads to introduction of novel foods on the market, which may pose a risk of inducing allergic sensitization. Currently there are no validated in vitro assays mimicking the human mucosal immune system to study sensitizing allergenicity risk of novel food proteins. The aim of this study was to introduce a series of sequential human epithelial and immune cell cocultures mimicking key immune events after exposure to the common food allergen ovalbumin from intestinal epithelial cell (IEC) activation up to mast cell degranulation.

Methods

This in vitro human mucosal food sensitizing allergenicity model combines crosstalk between IEC and monocyte-derived dendritic cells (moDC), followed by coculture of the primed moDCs with allogenic naïve CD4+ T cells. During subsequent coculture of primed CD4+ T cells with naïve B cells, IgE isotype-switching was monitored and supernatants were added to primary human mast cells to investigate degranulation upon IgE crosslinking. Mediator secretion and surface marker expression of immune cells were determined.

Results

Ovalbumin activates IEC and underlying moDCs, both resulting in downstream IgE isotype-switching. However, only direct exposure of moDCs to ovalbumin drives Th2 polarization and a humoral B cell response allowing for IgE mediated mast cell degranulation, IL13 and IL4 release in this sequential DC-T cell-B cell-mast cell model, indicating also an immunomodulatory role for IEC.

Conclusion

This in vitro coculture model combines multiple key events involved in allergic sensitization from epithelial cell to mast cell, which can be applied to study the allergic mechanism and sensitizing capacity of proteins.