Alterations in the Gut Microbiome of Young Children with Airway Allergic Disease Revealed by Next-Generation Sequencing

Associations and Related Mechanisms of Attention-Deficit Hyperactivity Disorder and Allergic Rhinitis in Children

Attention-deficit hyperactivity disorder (ADHD) is a chronic neurodevelopmental disorder that manifests in early childhood and often affects children's daily life and academic performance, impairing their psychological development and potentially influencing their personality. The concurrent yearly increase in the incidence of allergic diseases and ADHD among children has prompted researchers to explore the association between these 2 health issues. Allergic rhinitis (AR) is one of the most common allergic diseases and is characterized by chronic inflammation of the nasal mucosa. The prevalence of AR increases from infancy through adolescence and then decreases with further aging. The relationship between ADHD and AR has garnered significant attention from researchers recently, although it remains a topic of debate. Numerous studies have suggested a correlation, while some have reported conflicting results. Furthermore, the precise mechanisms underlying their coexistence have not been fully elucidated. This review summarizes the literature on ADHD and AR both domestically and internationally. It highlights their interrelationship and potential comorbid mechanisms, thereby providing new perspectives on the pathogenesis of ADHD and informing long-term treatment and management strategies.

Advances in research on gut microbiota and allergic diseases in children

Epidemiological studies indicate a rising prevalence of allergic diseases, now recognized as a major global public health concern. In children, the progression of these diseases often follows the "atopic march," beginning with eczema, followed by food allergies, allergic rhinitis, and asthma. Recent research has linked gut microbiota dysbiosis to the development of allergic diseases in children. The gut microbiota, a crucial component of human health, plays a vital role in maintaining overall well-being, highlighting its potential in preventing and modifying the course of allergic diseases. This review examines the relationship between childhood allergic diseases and gut microbiota, drawing on the latest evidence. We first elaborated the concepts of allergic diseases and gut microbiota, followed by a discussion of the developmental trajectory of the gut microbiota in healthy children. This review further explored the richness, diversity, and composition of the gut microbiota, as well as specific microbial taxa associated with allergic disease. Lastly, we discussed the current status and future potential of probiotic interventions in managing pediatric allergic diseases.

Multi-biofluid metabolomics analysis of allergic respiratory rhinitis and asthma in early childhood

Background

Childhood rhinitis and asthma are allergic respiratory diseases triggered by common allergens, but they affect different parts of the respiratory system, leading to distinct symptoms. However, a comprehensive multi-biofluid metabolomics-based approach to uncover valuable insights into childhood allergies and allergen sensitization remains unaddressed.

Methods

Seventy-six children, comprising 26 with rhinitis, 26 with asthma, and 24 healthy controls, were enrolled. Fecal, blood, and urine metabolomic analyses using 1H nuclear magnetic resonance (NMR) spectroscopy were conducted. An integrative analysis of their associations with allergen-specific IgE levels in the context of allergic rhinitis and asthma were also assessed.

Results

The analysis of 228 various biofluid samples revealed strong positive correlations between stool and blood metabolites, while blood metabolites exhibited negative correlations with most urine metabolites. Five and 19 metabolites were significantly different in children with rhinitis and asthma, respectively (P < 0.05). Among them, blood isovaleric acid correlated positively with stool IgE levels in rhinitis, while stool butyric acid and acetic acid in asthma exhibited strong negative correlations with total serum and mite allergen-specific IgE levels (P < 0.01). Blood metabolic profiles appeared to have the highest area under the curve (AUC) of 0.732 for rhinitis, whereas stool metabolic profiles had the highest AUC of 0.799 for asthma.

Conclusions

Multiple biofluid metabolomics provides comprehensive insights into childhood allergies, with blood profiles associated with allergic rhinitis and fecal profiles linked to asthma. Their short-chain fatty acid metabolites related to IgE levels emphasize the significant role of the gut microbiota in childhood rhinitis and asthma.

Allergen-specific sublingual immunotherapy altered gut microbiota in patients with allergic rhinitis

Introduction

Allergen-specific immunotherapy (AIT) induces long-term immune tolerance to allergens and is effective for treating allergic rhinitis (AR). However, the impact of sublingual immunotherapy (SLIT) on gut microbiota from AR patients and its correlation with treatment efficacy remains unclear.

Methods

In the present study, we enrolled 24 AR patients sensitized to Dermatophagoides farinae (Der-f) and 6 healthy donors (HD). All AR patients received SLIT treatment using standardized Der-f drops. Stool samples were collected from AR patients before treatment, and 1- and 3-months post-treatment, as well as from HD, for metagenomic sequencing analysis.

Results

AR patients had significantly lower richness and diversity in gut microbiota compared to HD, with notable alterations in composition and function. Besides, three months post-SLIT treatment, significant changes in gut microbiota composition at the genus and species levels were observed in AR patients. Streptococcus parasanguinis_B and Streptococcus parasanguinis, which were significantly lower in AR patients compared to HD, increased notably after three months of treatment. LEfSe analysis identified these species as markers distinguishing HD from AR patients and AR patients pre- from post-SLIT treatment. Furthermore, changes in the relative abundance of S. parasanguinis_B were negatively correlated with changes in VAS scores but positively correlated with changes in RCAT scores, suggesting a positive correlation with effective SLIT treatment.

Discussion

SLIT treatment significantly alters the gut microbiota of AR patients, with S. parasanguinis_B potentially linked to its effectiveness. This study offers insights into SLIT mechanisms and suggests that specific strains may serve as biomarkers for predicting SLIT efficacy and as modulators for improving SLIT efficacy.

Antibiotic administration aggravates asthma by disrupting gut microbiota and the intestinal mucosal barrier in an asthma mouse model

In humans, gut microbiota can determine the health status. The regulatory mechanisms of the gut microbiota in asthma must be elucidated. Although antibiotics (ABXs) can clear infections, they markedly alter the composition and abundance of gut microbiota. The present study used ABX-treated mice to examine the time-dependent effects of ABX administration on the gut microbiota and intestinal mucosal barrier. The mouse asthma model was established using ovalbumin (OVA) and gavaged with an ABX cocktail for different durations (1 or 2 weeks) and stacked sequences. The pathology of the model, model 2, OVA-ABX, OVA-ABX 2, ABX-OVA and ABX-OVA was severe when compared with the control group as evidenced by the following results: i) significantly increased pulmonary and colonic inflammatory cell infiltration; ii) enhanced pause values and iii) OVA-induced immunoglobulin E (IgE) and TGF-β expression levels, and significantly downregulated Tight Junction Protein 1 (TJP1), claudin 1 and Occludin expression levels. Furthermore, the intestinal bacterial load in the OVA-ABX and OVA-ABX 2 groups was significantly lower than that in the ABX-OVA and ABX-OVA 2 groups, respectively. The predominant taxa were as follows: phyla, Firmicutes and Proteobacteria, genera, Escherichia-Shigella, Lactobacillus and Lachnospira. The abundances of Lachnospira and Escherichia-Shigella were correlated with the expression of OVA-induced IgE and TJPs. These findings indicated that ABX administration, which modifies microbiome diversity and bacterial abundance, can disrupt colonic integrity, downregulate TJ proteins, damage the intestinal barrier, enhance enterocyte permeability, and promote the release of inflammatory factors, adversely affecting asthma alleviation and long-term repair.

Immunostimulating Commensal Bacteria and Their Potential Use as Therapeutics

The gut microbiome is intimately intertwined with the host immune system, having effects on the systemic immune system. Dysbiosis of the gut microbiome has been linked not only to gastrointestinal disorders but also conditions of the skin, lungs, and brain. Commensal bacteria can affect the immune status of the host through a stimulation of the innate immune system, training of the adaptive immune system, and competitive exclusion of pathogens. Commensal bacteria improve immune response through the production of immunomodulating compounds such as microbe-associated molecular patterns (MAMPs), short-chain fatty acids (SCFAs), and secondary bile acids. The microbiome, especially when in dysbiosis, is plastic and can be manipulated through the introduction of beneficial bacteria or the adjustment of nutrients to stimulate the expansion of beneficial taxa. The complex nature of the gastrointestinal tract (GIT) ecosystem complicates the use of these methods, as similar treatments have various results in individuals with different residential microbiomes and differential health statuses. A more complete understanding of the interaction between commensal species, host genetics, and the host immune system is needed for effective microbiome interventions to be developed and implemented in a clinical setting.