Combined IgE neutralization and Bifidobacterium longum supplementation reduces the allergic response in models of food allergy

Therapeutic Efficacy of YH35324 on FcεRIα-Mediated Mast Cell/Basophil Activation

PURPOSE

Immunoglobulin E (IgE) induces mast cell/basophil activation by binding with FcεRIα and contributes to the development of allergic disease, in which targeting IgE has been considered an effective therapeutic strategy. YH35324 (YH) is a new hybrid protein with an extracellular domain consisting of FcεRIα, and its pharmacodynamic effect and safety were validated. This study aimed to evaluate the therapeutic potential of YH as an anti-IgE immunomodulator compared with omalizumab (Oma).

METHODS

To evaluate the in vitro efficacy of YH in human mast cells, YH was treated with various methods, and the changes were confirmed through flow cytometry, immunoblot analysis, and immunocytochemistry. To evaluate the ex vivo efficacy of YH, the expression of FcεRIα on the surface of blood basophils was measured in 64 subjects with allergic diseases by flow cytometry. Serum soluble FcεRIα, CD23, and Mas-Related G-Protein Coupled Receptor Member X2 levels were measured by enzyme-linked immunosorbent assay.

RESULTS

The YH-administered group exhibited significantly lower expression of FcεRIα on peripheral basophils compared to the Oma-administered group up to 14 days post-administration. YH directly suppressed FcεRIα expression on the surface of LAD2 cells, as it was bound to IgE-unbound FcεRIα and migrated into the cells by actin-dependent endocytosis, then was recycled by FcRn binding in the lysosome in vitro. Serum soluble FcεRIα levels were increased in the YH-administered group compared to the other groups and showed a positive correlation with serum-free IgE.

CONCLUSIONS

YH represents a new therapeutic agent for IgE-mediated allergic disease. Further studies are needed to evaluate its additional effects on the FcεRIα-mediated autoimmune mechanism.

Advances in Biologic Therapies for Allergic Diseases: Current Trends, Emerging Agents, and Future Perspectives

Biologic therapies have revolutionized the treatment of severe allergic diseases, including asthma, atopic dermatitis (AD), chronic spontaneous urticaria (CSU), chronic rhinosinusitis with nasal polyps (CRSwNP), eosinophilic gastrointestinal diseases (EGIDs), and allergic rhinitis (AR). These molecularly targeted agents provide significant benefits for patients unresponsive to conventional treatments by addressing underlying immune mechanisms, particularly type 2 inflammation driven by cytokines such as IL-4, IL-5, and IL-13. Recent advancements include biologics targeting alarmins like thymic stromal lymphopoietin (TSLP) and IL-33, which may address both type 2 and non-type 2 inflammation, broadening their therapeutic scope. Despite their effectiveness, biologics remain expensive, posing socioeconomic challenges, and there are concerns regarding long-term safety and inter-individual variability in responses. Promising innovations such as bispecific antibodies and ultra-long-acting agents are under investigation, alongside digital health tools like remote biomarker monitoring and AI-driven decision support systems, which aim to enhance personalized care. However, disparities in access, particularly for underserved populations, underscore the need for policy reforms and affordable biosimilars. This review synthesizes recent findings and emerging trends, highlighting the evolving role of biologics in transforming allergic disease management and offering insights into future research directions.

Oral and Gut Microbial Hubs Associated With Reaction Threshold Interact With Circulating Immune Factors in Peanut Allergy

BACKGROUND

Among peanut-allergic individuals, there is high variability in the amount of peanut that triggers reactions (i.e., reaction threshold) that is not predictable or well-understood. We conducted this study to characterize relationships between the oral and gut microbiomes and systemic processes associated with reaction threshold in peanut allergy (PA).

METHODS

In a cohort of 120 children with suspected PA who underwent double-blind, placebo-controlled food challenges, we generated and analyzed parallel profiles of the oral microbiome, gut microbiome, peripheral blood transcriptome, peripheral blood cytometry, and serum antibody levels to identify threshold-associated markers and their inter-relationships.

RESULTS

The 120 participants included 23 children with no PA, 74 with high-threshold PA (reacting to ≥ 443 mg cumulative peanut protein), and 23 with low-threshold PA (reacting to < 443 mg cumulative peanut protein). Ten hub microbes were each identified in saliva and stool microbiome networks that were constructed, including the hub microbes Rothia aeria in saliva and Bacteroides sp. in stool that were associated with reaction threshold. These hub microbes were also associated with peripheral blood transcript levels for threshold-associated key drivers of FcγR-mediated phagocytosis and TLR signaling. Correlation network construction with additional data on threshold-associated peripheral blood neutrophil abundance and peanut-specific serum IgE and Ara h 2 antibody levels revealed central roles for saliva Rothia aeria and stool Bacteroides sp. in local-systemic networks for IgE- and IgG-mediated peanut allergy.

CONCLUSIONS

This integrated study of oral and stool microbiomes, blood transcriptome, cellular profiles, and peanut-specific serum antibodies revealed new relationships between local microbiota and systemic measures associated with reaction threshold in peanut allergy.

MiCML: a causal machine learning cloud platform for the analysis of treatment effects using microbiome profiles

BACKGROUND

The treatment effects are heterogenous across patients due to the differences in their microbiomes, which in turn implies that we can enhance the treatment effect by manipulating the patient's microbiome profile. Then, the coadministration of microbiome-based dietary supplements/therapeutics along with the primary treatment has been the subject of intensive investigation. However, for this, we first need to comprehend which microbes help (or prevent) the treatment to cure the patient's disease.

RESULTS

In this paper, we introduce a cloud platform, named microbiome causal machine learning (MiCML), for the analysis of treatment effects using microbiome profiles on user-friendly web environments. MiCML is in particular unique with the up-to-date features of (i) batch effect correction to mitigate systematic variation in collective large-scale microbiome data due to the differences in their underlying batches, and (ii) causal machine learning to estimate treatment effects with consistency and then discern microbial taxa that enhance (or lower) the efficacy of the primary treatment. We also stress that MiCML can handle the data from either randomized controlled trials or observational studies.

CONCLUSION

We describe MiCML as a useful analytic tool for microbiome-based personalized medicine. MiCML is freely available on our web server ( http://micml.micloud.kr ). MiCML can also be implemented locally on the user's computer through our GitHub repository ( https://github.com/hk1785/micml ).

The gut core microbial species Bifidobacterium longum: Colonization, mechanisms, and health benefits

Bifidobacterium longum (B. longum) is a species of the core microbiome in the human gut, whose abundance is closely associated with host age and health status. B. longum has been shown to modulate host gut microecology and have the potential to alleviate various diseases. Comprehensive understanding on the colonization mechanism of B. longum and mechanism of the host-B. longum interactions, can provide us possibility to prevent and treat human diseases through B. longum-directed strategies. In this review, we summarized the gut colonization characteristics of B. longum, discussed the diet factors that have ability/potential to enrich indigenous and/or ingested B. longum strains, and reviewed the intervention mechanisms of B. longum in multiple diseases. The key findings are as follows: First, B. longum has specialized colonization mechanisms, like a wide carbohydrate utilization spectrum that allows it to adapt to the host's diet, species-level conserved genes encoding bile salt hydrolase (BSHs), and appropriate bacterial surface structures. Second, dietary intervention (e.g., anthocyanins) could effectively improve the gut colonization of B. longum, demonstrating the feasibility of diet-tuned strain colonization. Finally, we analyzed the skewed abundance of B. longum in different types of diseases and summarized the main mechanisms by which B. longum alleviates digestive (repairing the intestinal mucosal barrier by stimulating Paneth cell activity), immune (up-regulating the regulatory T cell (Treg) populations and maintaining the balance of Th1/Th2), and neurological diseases (regulating the kynurenine pathway and quinolinic acid levels in the brain through the gut-brain axis).

Therapeutic monoclonal antibodies in allergy: Targeting IgE, cytokine, and alarmin pathways

The etiology of allergy is closely linked to type 2 inflammatory responses ultimately leading to the production of allergen-specific immunoglobulin E (IgE), a key driver of many allergic conditions. At a high level, initial allergen exposure disrupts epithelial integrity, triggering local inflammation via alarmins including IL-25, IL-33, and TSLP, which activate type 2 innate lymphoid cells as well as other immune cells to secrete type 2 cytokines IL-4, IL-5 and IL-13, promoting Th2 cell development and eosinophil recruitment. Th2 cell dependent B cell activation promotes the production of allergen-specific IgE, which stably binds to basophils and mast cells. Rapid degranulation of these cells upon allergen re-exposure leads to allergic symptoms. Recent advances in our understanding of the molecular and cellular mechanisms underlying allergic pathophysiology have significantly shaped the development of therapeutic intervention strategies. In this review, we highlight key therapeutic targets within the allergic cascade with a particular focus on past, current and future treatment approaches using monoclonal antibodies. Specific targeting of alarmins, type 2 cytokines and IgE has shown varying degrees of clinical benefit in different allergic indications including asthma, chronic spontaneous urticaria, atopic dermatitis, chronic rhinosinusitis with nasal polyps, food allergies and eosinophilic esophagitis. While multiple therapeutic antibodies have been approved for clinical use, scientists are still working on ways to improve on current treatment approaches. Here, we provide context to understand therapeutic targeting strategies and their limitations, discussing both knowledge gaps and promising future directions to enhancing clinical efficacy in allergic disease management.

Preventive and Therapeutic Effects of Lactiplantibacillus plantarum HD02 and MD159 through Mast Cell Degranulation Inhibition in Mouse Models of Atopic Dermatitis

As the relationship between the gut microbiome and allergies becomes better understood, targeted strategies to prevent and treat allergies through gut microbiome modulation are being increasingly developed. In the study presented herein, we screened various probiotics for their ability to inhibit mast cell degranulation and identified Lactiplatibacillus plantarum HD02 and MD159 as effective candidates. The two strains significantly attenuated vascular permeability induced by mast cell degranulation in a passive cutaneous anaphylaxis (PCA) model and, in the MC903-induced murine atopic dermatitis (AD) model, demonstrated comparable preventive effects against allergies, reducing blood levels of MCPT-1 (mast cell protease-1) and total IgE. In the house dust mite (HDM)-induced murine AD model, both L. plantarum HD02 and MD159 showed therapeutic effects, with L. plantarum HD02 demonstrating superior efficacy. Nevertheless, L. plantarum MD159 better suppressed transepidermal water loss (TEWL). Furthermore, L. plantarum HD02 and MD159 significantly increased the number of splenic Foxp3+ regulatory T cells, with L. plantarum MD159 having a more pronounced effect. However, only L. plantarum HD02 achieved a reduction in immune cells in the draining lymph nodes. Our findings highlight L. plantarum HD02 and MD159 as promising candidates for the prevention and treatment of allergies, demonstrating significant efficacy in suppressing mast cell degranulation, reducing the number of allergy biomarkers, and modulating immune responses in experimental models of AD. Their distinct mechanisms of action suggest potential complementary roles in addressing allergic diseases, underscoring their therapeutic promise in clinical applications.

Daily Supplementation with Bifidobacterium longum KACC91563 Alleviates Allergic Contact Dermatitis in an Animal Model

Allergic contact dermatitis (ACD) is the most common chronic inflammatory skin disease (or immune-mediated disease), causing disruption to our psychological condition and life quality. In this study, the therapeutic properties of probiotic Bifidobacterium longum (B. longum) was investigated by using an ACD-induced animal model. For ACD induction, BALB/c mice ear and dorsal skin were sensitized with 240 µL of 1% (w/v) 2,4-dinitrochlorobenzene (DNCB) twice (3-day intervals). After a week of the first induction, the mice were re-sensitized by painting on their dorsal skin and ear with 0.4% (w/v) DNCB for a further three times (once per week). Before the ACD induction of 2 weeks and throughout the trial period, the BALB/c mice were supplemented daily with 1 mL of 1.0 × 109 CFU or 5.0 × 109 CFU B. longum using an intragastric gavage method. The ACD-induced mice without B. longum supplementation were used as a control. Results show that B. longum supplementation significantly alleviated ACD symptoms (e.g., ear swelling, epidermal damage) and immune response (e.g., reduced immune cell recruitment, serum IgE level, and cytokine production). The therapeutic efficiency of B. longum increased as the supplementation dose increased. Thus, daily supplementation with 5.0 × 109 CFU probiotic B. longum could be an effective method for the prevention and treatment of ACD.

Safety, Tolerability, Pharmacokinetics, and pharmacodynamics of YH35324, a novel Long-Acting High-Affinity IgETrap-Fc protein in subjects with Atopy: Results from the First-in-Human study

BACKGROUND

YH35324, a long-acting IgETrap-Fc fusion protein, is a novel therapeutic agent for immunoglobulin E (IgE)-mediated allergic diseases. This randomized, double-blind, placebo/active-controlled, single ascending dose Phase 1 study assessed the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of YH35324 in subjects with atopy.

METHODS

Eligible subjects were healthy subjects or atopic adults with mild allergic rhinitis, atopic dermatitis, food allergy, or urticaria, and a serum total IgE level of 30-700 IU/mL (Part A) or > 700 IU/mL (Part B). In Part A, 35 subjects in 5 cohorts received YH35324 (0.3, 1, 3, 6, and 9 mg/kg), 8 received omalizumab (300 mg), and 9 received placebo. In Part B, 8 subjects received YH35324 and 8 received omalizumab.

RESULTS

Twenty subjects (38.5 %) in Part A (YH35324: 37.1 %, omalizumab: 50.0 %, placebo: 33.3 %) and 10 subjects (62.5 %) in Part B (YH35324: 100 %; omalizumab: 25.0 %) experienced treatment-emergent adverse events (TEAEs). TEAEs were mostly grade 1/2; no serious AEs, AE-related treatment discontinuation, or anaphylaxis were reported. YH35324 exhibited dose-proportional increase in Cmax and AUClast over the dose range of 0.3-9 mg/kg. YH35324 rapidly suppressed serum-free IgE levels to a significant extent (< 25 and < 82.8 ng/mL, both P < 0.05) and with longer duration than omalizumab.

CONCLUSION

This study showed that YH35324 has a favorable safety profile and is effective in reducing serum-free IgE levels in subjects with atopic conditions.

Probiotics in Allergy and Immunological Diseases: A Comprehensive Review

Allergy and immunological disorders like autoimmune diseases are vastly prevalent worldwide. These conditions account for a substantial amount of personal and social burden. Such illnesses have lengthy, uncertain, and spotted courses with unpredictable exacerbations. A definite tendency for improving the overall quality of life of individuals suffering from such diseases is crucial to tackling these diseases, especially through diet or lifestyle modification. Further, interventions like microbiome-based therapeutics such as prebiotics or probiotics were explored. Changes in the microbial population were evident during the flare-up of autoimmune and allergic conditions. The realization that the human microbiome is a central player in immunological diseases is a hallmark of its potential usefulness in therapy for such illnesses. This review focuses on the intricate symphony in the orchestra of the human microbiome and the immune system. New therapeutic strategies involving probiotics appear to be the future of personalized medicine. Through this review, we explore the narrative of probiotics and reaffirm their use as therapeutic and preventive agents in immunological disorders.

Bifidobacterium mechanisms of immune modulation and tolerance

Bifidobacterium is a widely distributed commensal bacterial genus that displays beneficial pro-homeostatic and anti-inflammatory immunomodulatory properties. Depletion or absence of Bifidobacterium in humans and model organisms is associated with autoimmune responses and impaired immune homeostasis. At the cellular level, Bifidobacterium upregulates suppressive regulatory T cells, maintains intestinal barrier function, modulates dendritic cell and macrophage activity, and dampens intestinal Th2 and Th17 programs. While there has been a large volume of literature characterizing the probiotic properties of various Bifidobacterial species, the likely multifactorial mechanisms underlying these effects remain elusive, in particular, its immune tolerogenic effect. However, recent work has shed light on Bifidobacterium surface structural polysaccharide and protein elements, as well as its metabolic products, as commensal mediators of immune homeostasis. This review aims to discuss several mechanisms Bifidobacterium utilizes for immune modulation as well as their indirect impact on the regulation of gut microbiome structure and function, from structural molecules to produced metabolites. These mechanisms are pertinent to an increasingly networked understanding of immune tolerance and homeostasis in health and disease.

Degranulation of Mast Cells as a Target for Drug Development

Mast cells act as key effector cells of inflammatory responses through degranulation. Mast cell degranulation is induced by the activation of cell surface receptors, such as FcεRI, MRGPRX2/B2, and P2RX7. Each receptor, except FcεRI, varies in its expression pattern depending on the tissue, which contributes to their differing involvement in inflammatory responses depending on the site of occurrence. Focusing on the mechanism of allergic inflammatory responses by mast cells, this review will describe newly identified mast cell receptors in terms of their involvement in degranulation induction and patterns of tissue-specific expression. In addition, new drugs targeting mast cell degranulation for the treatment of allergy-related diseases will be introduced.

A Review on Maternal and Infant Microbiota and Their Implications for the Prevention and Treatment of Allergic Diseases

Allergic diseases, which are closely related to the composition and metabolism of maternal and infant flora, are prevalent in infants worldwide. The mother's breast milk, intestinal, and vaginal flora directly or indirectly influence the development of the infant's immune system from pregnancy to lactation, and the compositional and functional alterations of maternal flora are associated with allergic diseases in infants. Meanwhile, the infant's own flora, represented by the intestinal flora, indicates and regulates the occurrence of allergic diseases and is altered with the intervention of allergic diseases. By searching and selecting relevant literature in PubMed from 2010 to 2023, the mechanisms of allergy development in infants and the links between maternal and infant flora and infant allergic diseases are reviewed, including the effects of flora composition and its consequences on infant metabolism. The critical role of maternal and infant flora in allergic diseases has provided a window for probiotics as a microbial therapy. Therefore, the uses and mechanisms by which probiotics, such as lactic acid bacteria, can help to improve the homeostasis of both the mother and the infant, and thereby treat allergies, are also described.

Probiotic Bacteria from Human Milk Can Alleviate Oral Bovine Casein Sensitization in Juvenile Wistar Rats

This study aims to see if probiotic bacteria from human milk could ameliorate oral cow's milk sensitization. The probiotic potential of the SL42 strain isolated from the milk of a healthy young mother was first determined. Rats were then randomly gavaged with cow's milk casein without an adjuvant or assigned to the control group. Each group was further subdivided into three groups, with each receiving only Limosilactobacillus reuteri DSM 17938, SL42, or a phosphate-buffered saline solution. Body weight, temperature, eosinophils, serum milk casein-specific IgE (CAS-IgE), histamine, and serum S100A8/A9 and inflammatory cytokine concentrations were measured. The animals were sacrificed after 59 days; histological sections were prepared, and the spleen or thymus weights, as well as the diversity of the gut microbiota, were measured. On days 1 and 59, SL42 abridged systemic allergic responses to casein by dropping histamine levels (25.7%), CAS-specific IgE levels (53.6%), eosinophil numbers (17%), S100A8/9 (18.7%), and cytokine concentrations (25.4-48.5%). Analyses of histological sections of the jejunum confirmed the protective effect of probiotic bacteria in the CAS-challenged groups. Lactic acid bacteria and Clostridia species were also increased in all probiotic-treated groups. These findings suggest that probiotics derived from human milk could be used to alleviate cow's milk casein allergy.