Intestinal microbiota and allergic diseases: A systematic review

The Microbiota in Cancer: A Secondary Player or a Protagonist?

The intestinal microbiota and the human body are in a permanent interaction. There is a symbiotic relationship in which the microbiota plays a vitally important role in the performance of numerous functions, including digestion, metabolism, the development of lymphoid tissue, defensive functions, and other processes. It is a true metabolic organ essential for life and has potential involvement in various pathological states, including cancer and pathologies other than those of a digestive nature. A growing topic of great interest for its implications is the relationship between the microbiota and cancer. Dysbiosis plays a role in oncogenesis, tumor progression, and even the response to cancer treatment. The effect of the microbiota on tumor development goes beyond a local effect having a systemic effect. Another aspect of great interest regarding the intestinal microbiota is its relationship with drugs, modifying their activity. There is increasing evidence that the microbiota influences the therapeutic activity and side effects of antineoplastic drugs and also modulates the response of several tumors to antineoplastic therapy through immunological circuits. These data suggest the manipulation of the microbiota as a possible adjuvant to improve oncological treatment. Is it possible to manipulate the microbiota for therapeutic purposes?

The Role of the Microbiota in the Pathogenesis and Treatment of Atopic Dermatitis-A Literature Review

Atopic dermatitis (AD) is a chronic inflammatory skin condition with a high prevalence worldwide. AD pathogenesis is complex and consists of immune system dysregulation and impaired skin barrier, influenced by genetic and environmental factors. The purpose of the review is to show the complex interplay between atopic dermatitis and the microbiota. Human microbiota plays an important role in AD pathogenesis and the course of the disease. Dysbiosis is an important factor contributing to the development of atopic diseases, including atopic dermatitis. The gut microbiota can influence the composition of the skin microbiota, strengthening the skin barrier and regulating the immune response via the involvement of bacterial metabolites, particularly short-chain fatty acids, in signaling pathways of the gut-skin axis. AD can be modulated by antibiotic intake, dietary adjustments, hygiene, and living conditions. One of the promising strategies for modulating the course of AD is probiotics. This review offers a summary of how the microbiota influences the development and treatment of AD, highlighting aspects that warrant additional investigation.

The Role of Biodiversity in the Development of Asthma and Allergic Sensitization: A State-of-the-Science Review

BACKGROUND

Changes in land use and climate change have been reported to reduce biodiversity of both the environment and human microbiota. These reductions in biodiversity may lead to inadequate and unbalanced stimulation of immunoregulatory circuits and, ultimately, to clinical diseases, such as asthma and allergies.

OBJECTIVE

We summarized available empirical evidence on the role of inner (gut, skin, and airways) and outer (air, soil, natural waters, plants, and animals) layers of biodiversity in the development of asthma, wheezing, and allergic sensitization.

METHODS

We conducted a systematic search in SciVerse Scopus, PubMed MEDLINE, and Web of Science up to 5 March 2024 to identify relevant human studies assessing the relationships between inner and outer layers of biodiversity and the risk of asthma, wheezing, or allergic sensitization. The protocol was registered in PROSPERO (CRD42022381725).

RESULTS

A total of 2,419 studies were screened and, after exclusions and a full-text review of 447 studies, 82 studies were included in the comprehensive, final review. Twenty-nine studies reported a protective effect of outer layer biodiversity in the development of asthma, wheezing, or allergic sensitization. There were also 16 studies suggesting an effect of outer layer biodiversity on increasing asthma, wheezing, or allergic sensitization. However, there was no clear evidence on the role of inner layer biodiversity in the development of asthma, wheezing, and allergic sensitization (13 studies reported a protective effect and 15 reported evidence of an increased risk).

CONCLUSIONS

Based on the reviewed literature, a future systematic review could focus more specifically on outer layer biodiversity and asthma. It is unlikely that association with inner layer biodiversity would have enough evidence for systematic review. Based on this comprehensive review, there is a need for population-based longitudinal studies to identify critical periods of exposure in the life course into adulthood and to better understand mechanisms linking environmental exposures and changes in microbiome composition, diversity, and/or function to development of asthma and allergic sensitization. https://doi.org/10.1289/EHP13948.

Gut microbiome signature and nasal lavage inflammatory markers in young people with asthma

Background

Asthma is a complex disease and a severe global public health problem resulting from interactions between genetic background and environmental exposures. It has been suggested that gut microbiota may be related to asthma development; however, such relationships needs further investigation.

Objective

This study aimed to characterize the gut microbiota as well as the nasal lavage cytokine profile of asthmatic and nonasthmatic individuals.

Methods

Stool and nasal lavage samples were collected from 29 children and adolescents with type 2 asthma and 28 children without asthma in Brazil. Amplicon sequencing of the stool bacterial V4 region of the 16S rRNA gene was performed using Illumina MiSeq. Microbiota analysis was performed by QIIME 2 and PICRUSt2. Type 2 asthma phenotype was characterized by high sputum eosinophil counts and positive skin prick tests for house dust mite, cockroach, and/or cat or dog dander. The nasal immune marker profile was assessed using a customized multiplex panel.

Results

Stool microbiota differed significantly between asthmatic and nonasthmatic participants (P = .001). Bacteroides was more abundant in participants with asthma (P < .05), while Prevotella was more abundant in nonasthmatic individuals (P < .05). In people with asthma, the relative abundance of Bacteroides correlated with IL-4 concentration in nasal lavage samples. Inference of microbiota functional capacity identified differential fatty acid biosynthesis in asthmatic compared to nonasthmatic subjects.

Conclusion

The stool microbiota differed between asthmatic and nonasthmatic young people in Brazil. Asthma was associated with higher Bacteroides levels, which correlated with nasal IL-4 concentration.

Analysis of the saliva microbiome in patients with immunoglobulin G4-related disease

OBJECTIVES

This article aims to investigate the saliva microbiome in patients with immunoglobulin G4-related disease (IgG4RD) compared with primary Sjögren's syndrome (SS).

METHODS

Saliva samples were collected from 11 IgG4RD and 11 SS patients who visited IMSUT Hospital, The Institute of Medical Science, The University of Tokyo. Deoxyribonucleic acid (DNA) was extracted from the samples, and primers were used to amplify the V3-V4 regions of bacterial and archaeal 16S ribosomal RNA (rRNA) genes, which was then analysed by paired-end sequencing. Amplicon reads were processed using QIIME2 to generate representative sequences. The Greengenes database was used to identify the bacterial flora in each sample and compare them between groups.

RESULTS

The IgG4RD and SS groups exhibited differences in bacterial diversity. Cluster analyses of attributed classification groups by species and disease showed that IgG4RD and SS cases formed individual clusters. Significant differences in relative abundance between IgG4RD and SS were observed for the following organisms: Mogibacterium (P = .0051), Solobacterium moorei (P = .0195), Slackia (P = .0356), and Moryella (P = .0455).

CONCLUSIONS

Salivary microbiome analysis of IgG4RD and SS patients revealed significantly higher relative proportions of Mogibacterium, S. moorei, Slackia, and Moryella bacteria in IgG4RD compared with SS.

The effects of polylactic acid bioplastic exposure on midgut microbiota and metabolite profiles in silkworm (Bombyx mori): An integrated multi-omics analysis

Polylactic acid (PLA) is a highly common biodegradable plastic and a potential threat to health and the environment. However, limited data are available on the effects of PLA exposure in the silkworm (Bombyx mori), a model organism used in toxicity studies. In this study, silkworms with or without PLA exposure (P1: 1 mg/L, P5: 5 mg/L, P25: 25 mg/L, and P0: 0 mg/L) for the entire 5th instar period were used to investigate the impact of PLA exposure on midgut morphology, larvae growth, and survival. Mitochondrial damage was observed in the P5 and P25 groups. The weights of the P25 posterior silk gland (5th day in the 5th instar), mature larvae and pupae were all significantly lower than those of the controls (P < 0.05). Dead worm cocoon rates and larva-pupa to 5th instar larvae ratios showed a positive and negative dose-dependent manner with respect to PLA concentrations, respectively. Additionally, reactive oxygen species levels and superoxide dismutase activity of the P25 midgut were significantly higher and lower when compared with controls, respectively (P < 0.05). The molecular mechanisms underlying the effects of PLA and associated physiological responses were also investigated. In the midgut metabolome, 127 significantly different metabolites (variable importance projection >1 and P < 0.05) were identified between the P0 and P25 groups and were mainly enriched for amino acid metabolism and energy supply pathways. The 16 S rDNA data showed that PLA altered microbial richness and structural composition. Microbiota, classified into 34 genera and 63 species, were significantly altered after 25 mg/L PLA exposure (P < 0.05). Spearman's correlation results showed that Bifidobacterium catenulatum and Schaalia odontolytica played potentially vital roles during exposure, as they demonstrated stronger correlations with the significantly different metabolites than other bacterial species. In sum, PLA induced toxic effects on silkworms, especially on energy- and protein-relevant metabolism, but at high concentrations (25 mg/L). This prospective mechanistic investigation on the effects of PLA on larval toxicity provides novel insight regarding the ecological risks of biodegradable plastics in the environment.

Berberine-containing natural-medicine with boiled peanut-OIT induces sustained peanut-tolerance associated with distinct microbiota signature

Background

Gut microbiota influence food allergy. We showed that the natural compound berberine reduces IgE and others reported that BBR alters gut microbiota implying a potential role for microbiota changes in BBR function.

Objective

We sought to evaluate an oral Berberine-containing natural medicine with a boiled peanut oral immunotherapy (BNP) regimen as a treatment for food allergy using a murine model and to explore the correlation of treatment-induced changes in gut microbiota with therapeutic outcomes.

Methods

Peanut-allergic (PA) mice, orally sensitized with roasted peanut and cholera toxin, received oral BNP or control treatments. PA mice received periodic post-therapy roasted peanut exposures. Anaphylaxis was assessed by visualization of symptoms and measurement of body temperature. Histamine and serum peanut-specific IgE levels were measured by ELISA. Splenic IgE+B cells were assessed by flow cytometry. Fecal pellets were used for sequencing of bacterial 16S rDNA by Illumina MiSeq. Sequencing data were analyzed using built-in analysis platforms.

Results

BNP treatment regimen induced long-term tolerance to peanut accompanied by profound and sustained reduction of IgE, symptom scores, plasma histamine, body temperature, and number of IgE+ B cells (p <0.001 vs Sham for all). Significant differences were observed for Firmicutes/Bacteroidetes ratio across treatment groups. Bacterial genera positively correlated with post-challenge histamine and PN-IgE included Lachnospiraceae, Ruminococcaceae, and Hydrogenanaerobacterium (all Firmicutes) while Verrucromicrobiacea. Caproiciproducens, Enterobacteriaceae, and Bacteroidales were negatively correlated.

Conclusions

BNP is a promising regimen for food allergy treatment and its benefits in a murine model are associated with a distinct microbiota signature.

Microbial signature of intestine in children with allergic rhinitis

INTRODUCTION

Previous studies have found that unique patterns of gut microbial colonization in infancy associated with the development of allergic diseases. However, there is no research on the gut microbiota characteristics of AR children in Chinese Mainland.

OBJECTIVE

To investigate the changes of gut microbial of AR children in Chinese Mainland and evaluate the correlation between gut microbial and clinical indexes.

METHODS

In this clinical study, fecal samples from 24 AR children and 25 healthy control children (HCs) were comparative via next generation sequencing of the V3-V4 regions of the 16S rRNA gene. Analyzed the relationship between clinical features and gut microbial using Spearman correlation.

RESULTS

Compared to HCs, AR children showed significant decreases in Shannon index and significant increases in Simpson index at both the family and genera levels (all p < 0.05). In terms of bacterial composition, at the phylum level, AR children had higher abundance of Bacteroidetes than that in the HCs group (p < 0.05) and were significantly positively correlated with TNSS (p < 0.05). At the family level, AR children had higher abundance of Prevotellaceae and Enterobacteriaceae higher than that in the HCs group (all p < 0.05) and had a significantly positive correlation with TNSS, eosinophils (EOS) and total immunoglobulin E (tIgE) (all p < 0.05). At the genus level, reduced abundance of Agathobacter, Parasutterella, Roseburia and Subdoligranulum were also observed in the AR cohorts compared to HCs (all p < 0.05) and significantly negatively associated with TNSS, EOS, tIgE, QOL, and FeNO (all p < 0.05).

CONCLUSION

AR children in Chinese Mainland were characterized by reduced microbial diversity and distinguished microbial characteristics in comparison with HCs. The observations of this study offer proof that distinctive gut microbiota profiles were present in AR children and necessitate further investigation in the form of mechanistic studies.

Relationship between Gut Microbiota and Allergies in Children: A Literature Review

The intestinal microbiota is a diverse and complex microecosystem that lives and thrives within the human body. The microbiota stabilizes by the age of three. This microecosystem plays a crucial role in human health, particularly in the early years of life. Dysbiosis has been linked to the development of various allergic diseases with potential long-term implications. Next-generation sequencing methods have established that allergic diseases are associated with dysbiosis. These methods can help to improve the knowledge of the relationship between dysbiosis and allergic diseases. The aim of this review paper is to synthesize the current understanding on the development of the intestinal microbiota in children, the long-term impact on health, and the relationship between dysbiosis and allergic diseases. Furthermore, we examine the connection between the microbiome and specific allergies such as atopic dermatitis, asthma, and food allergies, and which mechanisms could determine the induction of these diseases. Furthermore, we will review how factors such as mode of delivery, antibiotic use, breastfeeding, and the environment influence the development of the intestinal flora, as well as review various interventions for the prevention and treatment of gut microbiota-related allergies.

Paediatric Asthma and the Microbiome: A Systematic Review

Evidence from the literature suggests an association between the microbiome and asthma development. Here, we aimed to identify the current evidence for the association between asthma and the upper airway, lower airway and/or the gut microbiome. An electronic systemic search of PubMed, EBSCO, Science Direct and Web of Science was conducted until February 2022 to identify the eligible studies. The Newcastle–Ottawa Scale and the Systematic Review Centre for Laboratory Animal Experimentation risk of the bias tools were used to assess quality of included studies. Twenty-five studies met the inclusion criteria. Proteobacteria and Firmicutes were identified as being significantly higher in the asthmatic children compared with the healthy controls. The high relative abundance of Veillonella, Prevotella and Haemophilus in the microbiome of the upper airway in early infancy was associated with a higher risk of asthma development later in life. The gut microbiome analyses indicated that a high relative abundance of Clostridium in early childhood might be associated with asthma development later in life. The findings reported here serve as potential microbiome signatures associated with the increased risk of asthma development. There is a need for large longitudinal studies to further identify high-risk infants, which will help in design strategies and prevention mechanisms to avoid asthma early in life.

International consensus statement on allergy and rhinology: Allergic rhinitis - 2023

BACKGROUND

In the 5 years that have passed since the publication of the 2018 International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis (ICAR-Allergic Rhinitis 2018), the literature has expanded substantially. The ICAR-Allergic Rhinitis 2023 update presents 144 individual topics on allergic rhinitis (AR), expanded by over 40 topics from the 2018 document. Originally presented topics from 2018 have also been reviewed and updated. The executive summary highlights key evidence-based findings and recommendation from the full document.

METHODS

ICAR-Allergic Rhinitis 2023 employed established evidence-based review with recommendation (EBRR) methodology to individually evaluate each topic. Stepwise iterative peer review and consensus was performed for each topic. The final document was then collated and includes the results of this work.

RESULTS

ICAR-Allergic Rhinitis 2023 includes 10 major content areas and 144 individual topics related to AR. For a substantial proportion of topics included, an aggregate grade of evidence is presented, which is determined by collating the levels of evidence for each available study identified in the literature. For topics in which a diagnostic or therapeutic intervention is considered, a recommendation summary is presented, which considers the aggregate grade of evidence, benefit, harm, and cost.

CONCLUSION

The ICAR-Allergic Rhinitis 2023 update provides a comprehensive evaluation of AR and the currently available evidence. It is this evidence that contributes to our current knowledge base and recommendations for patient evaluation and treatment.

Natural Green Spaces, Sensitization to Allergens, and the Role of Gut Microbiota during Infancy

The environment plays an instrumental role in the developmental origins of health and disease. Protective features of the environment in the development of asthma and atopy have been insufficiently studied. We used data from the CHILD (Canadian Healthy Infant Longitudinal Development) Cohort Study to examine relationships between living near natural green spaces in early infancy in Edmonton, AB, Canada and the development of atopic sensitization at 1 year and 3 years of age in a cohort of 699 infants, and whether these associations were mediated by infant gut microbiota (measured using 16s V4 amplicon sequencing) at 4 months. The Urban Planning Land Vegetation Index (uPLVI) map of the City of Edmonton was used to assess infants' exposure to natural spaces based on their home postal codes, and atopic sensitization was assessed using skin prink testing (SPTs) for common food and inhalant allergens. Our findings suggest there is a protective effect of natural green space proximity on the development of multiple inhalant atopic sensitizations at 3 years (odds ratio = 0.28 [95% CI 0.09, 0.90]). This relationship was mediated by changes to Actinobacteria diversity in infant fecal samples taken at 4 months. We also found a positive association between nature proximity and sensitization to at least one food or inhaled allergen; this association was not mediated by gut microbiota. Together, these findings underscore the importance of promoting natural urban greenspace preservation to improve child health by reducing atopic disease susceptibility. IMPORTANCE Our findings highlight the importance of preserving natural green space in urban settings to prevent sensitization to environmental allergens and promote early-life gut microbiota pathways to this health benefit. These findings support a mediating role of gut microbiome compositions in health and disease susceptibility. This study used unique, accurate, and comprehensive methodology to classify natural space exposure via a high-resolution topographical map of foliage subtypes within the City of Edmonton limits. These methods are improvements from other methods previously used to classify natural space exposure, such as the normalized density vegetation index from satellite imagery, which is not able to distinguish anthropogenic from green space. The use of these methods and the associations found between natural green space exposure and atopic sensitization outcomes support their use in future studies. Our findings also provide many avenues for future research including longer term follow up of this cohort and investigation of a causal role of reduced Actinobacteria diversity on atopic sensitization development.

Factors associated with allergy traits around the 2nd year of life: a brazilian cohort study

BACKGROUND

Allergic status has been strongly influenced by early exposures; however, allergic diseases are hard to measure in early life. Thus, this study proposed a latent variable allergy traits around the second year of life and analyzed pre- and perinatal factors associated with this phenomenon.

METHODS

The study used data from the BRISA birth cohort, Ribeirão Preto, Brazil (n = 3644). The theoretical model included: family allergy (history of allergic rhinitis, atopic dermatitis, and asthma); gestational period variables (socioeconomic status, mother's skin color, pregestational body mass index - BMI, smoking, gestational diabetes, and hypertension); birth variables (gestational age, 5-minute Apgar score, birth weight, type of delivery), and early life factor (exclusive breast feeding). The outcome was allergy traits around the 2nd year of life, a latent variable deduced from the shared variance among medical diagnosis of allergic rhinitis, atopic dermatitis, and food allergy. The model was analyzed by structural equation modeling.

RESULTS

Higher socioeconomic status (SC = 0.256; p < 0.001) and higher family allergy values (SC = 1.224; p < 0.001) were associated with higher allergy trait values. Hypertension during pregnancy was associated with higher values (SC = 0.170; p = 0.022) and exclusive breast feeding (SC = -0.192; p < 0.001) with low allergy trait values.

CONCLUSION

Although socioeconomic and environmental factors were associated with allergy traits around the 2nd year of life, the family component of allergy was the exposure that best explained this outcome.

Gut microbiome and attention deficit/hyperactivity disorder: a systematic review

BACKROUND

This systematic review aims to examine the associations between features of gut microbiome and Attention Deficit/Hyperactivity Disorder (ADHD) risk or severity in children, adolescents and young adults.

METHODS

Eligible studies were identified in PubMed and Google Scholar databases until December 31, 2020.

RESULTS

The search identified a total of 1197 items, of which 11 were included in this systematic review. The findings regarding alpha, beta diversity, bacterial phyla, orders and families were inconclusive. At the genus level an increased abundance of Odoribacter (two studies) and Eggerthella (two studies) was found in ADHD; on the contrary, decreased abundance of Faecalibacterium (three studies) was noted, whereas one study suggested its inverse association with ADHD severity and hyperactivity. One study indicated that Bacteroides species also correlated with levels of hyperactivity and impulsivity. At the species level, a lower abundance of Faecalibacterium prausnitzii, but higher of Odoribacter splanchnicus and Bacteroides uniformis was reported.

CONCLUSIONS

This systematic review highlights associations between gut microbiome features and ADHD. Potential mechanisms differ by microorganism and include effects on neurotransmitter production, dopamine metabolism, modulation of inflammation and neurodevelopment through the release of cytokines.

IMPACT

The existence of correlations between features of gut microbiome and ADHD manifestation or its severity in children, adolescents and young adults. Associations between gut microbiome features and ADHD are highlighted. Potential mechanisms seem to differ by microorganism and include effects on neurotransmitter production, dopamine metabolism, modulation of inflammation and neurodevelopment through the release of cytokines. As correlations between gut microbiome features and ADHD seem to exist, additional studies are needed for further investigation.

The Baseline Gut Microbiota Enterotype Directs Lifestyle-Induced Amelioration of Pollen Allergy Severity: A Self Controlled Case-Series Study

Deciphering the key factors underlying individual responses to a habitual diet is important in implementing personalized nutrition strategies to treat allergic diseases. This prospective randomized cohort study aimed to identify key factors determining individual pollen allergy (PA) trajectories in a natural setting. Baseline data on fecal microbiota composition, lifestyle activities, and diet habits of 190 participants with PA and 92 healthy controls were collected, followed by a SOMPO-guided intestinal activity program. Three enterotypes enriched in Bacteroides, Prevotella, and Ruminococcus and four subenterotypes for enterotypes Bacteroides and Prevotella enriched with Faecalibacterium, Megamonas, and Fusobacterium were identified at baseline. PA severity was significantly negatively correlated with the daily intake of fermented plants and no weekly intake of meat, but positively correlated with poor sleep quality. Interactions between enterotype and lifestyle factors affected PA severity, and intestinal activity intervention based on the baseline enterotype reduced the PA severity score. In conclusion, the findings of this study demonstrated that the baseline gut enterotype plays a crucial role in PA. This study suggests combining enterotype data with habitual diet can improve PA severity.

Unlocking the Potential of the Human Microbiome for Identifying Disease Diagnostic Biomarkers

The human microbiome encodes more than three million genes, outnumbering human genes by more than 100 times, while microbial cells in the human microbiota outnumber human cells by 10 times. Thus, the human microbiota and related microbiome constitute a vast source for identifying disease biomarkers and therapeutic drug targets. Herein, we review the evidence backing the exploitation of the human microbiome for identifying diagnostic biomarkers for human disease. We describe the importance of the human microbiome in health and disease and detail the use of the human microbiome and microbiota metabolites as potential diagnostic biomarkers for multiple diseases, including cancer, as well as inflammatory, neurological, and metabolic diseases. Thus, the human microbiota has enormous potential to pave the road for a new era in biomarker research for diagnostic and therapeutic purposes. The scientific community needs to collaborate to overcome current challenges in microbiome research concerning the lack of standardization of research methods and the lack of understanding of causal relationships between microbiota and human disease.

Maternal diets have effects on intestinal mucosal flora and susceptibility to colitis of offspring mice during early life

OBJECTIVES

Intestinal flora is considered closely related to the occurrence of inflammatory bowel disease (IBD). This study aimed to discover whether diverse diet conditions during early life lead to different intestinal flora structure and impact different susceptibility to IBD.

METHODS

We performed a randomized, controlled trial to investigate the relationship between maternal diet, intestinal flora, and susceptibility of IBD in offspring mice. We treated the maternal mice with different dietary conditions (maternal high fat, high protein, or normal diet, and offspring continued maternal diets or changed to normal diet), and then extracted bacterial meta-genomic DNA from the intestinal mucosa of the offspring during the early life and adult stages. We amplified and sequenced the conserved gene v3-v4 of the bacterial 16 S ribosomal RNA. After dextran sulphate sodium intervention, we evaluated the susceptibility to intestinal inflammation with hematoxylin and eosin stains and disease activity index scores.

RESULTS

The number of species and alpha diversity of weaning mice (3 wk old) fed a maternal high-protein diet were significantly lower than those of the control diet group (P < 0.05). Among adult (8 wk old) offspring rats, the alpha diversity of mice that continued on a high-protein diet remained significantly decreased (P < 0.05). In addition, 12 kinds of weak bacteria were found in weaning mice fed a maternal high-protein diet compared with the control group. Offspring that continued in the maternal high-protein group had increased disease activity index and pathologic scores after weaning.

CONCLUSIONS

In general, our study shows that a maternal high-protein diet during early life can negatively regulate the intestinal flora diversity of offspring mice. A high-protein diet during early life led to higher susceptibility of IBD in offspring rats.

[Metagenome-wide association of gut microbiome features in children with moderate-severe house dust mite allergic rhinitis]

Objective:To draw a distinct gut microbiota pattern of children with moderate-severe dust mite-induced allergic rhinitis（DAR） and healthy children. Methods:3-10 years old moderate-severe DAR children（68 cases） and healthy children（38 cases） were involved in this study. General information was collected through questionnaires, and fecal samples were collected for metagenomic sequencing. MetaPhlAn3 was used to generate the microbiota composition abundance in detail, and Alpha and Beta diversity changes were calculated. The difference in species abundance at different taxonomic levels were compared. Differences in functional pathways were compared by LEfSe analysis. Results:The diversity of gut microbiota in children with moderate-severe DAR didn't change significantly compared with healthy children. A total of 37 microbial communities or species with significant abundance difference were found, mainly included Lachnoclostridium, Prevotella, Blautia wexlerae, Prevotella copri, Eubacterium eligens, Eubacterium sp CAG 180, etc. However, the metabolism functions of gut microbiota in children with moderate-severe DAR changed compared with healthy children. Various of fatty acids anabolism enhanced in DAR children. Conclusion:Compared with healthy children, there was no significant difference in gut microbial diversity in moderate-severe DAR children. The abundance of a series of specific microbe species had a marked alteration in DAR, accompanied with changes in certain microbial functional pathways.

Bifidobacterium spp. as functional foods: A review of current status, challenges, and strategies

Members of Bifidobacterium are among the first microbes to colonize the human intestine naturally, their abundance and diversity in the colon are closely related to host health. Recently, the gut microbiota has been gradually proven to be crucial mediators of various metabolic processes between the external environment and the host. Therefore, the health-promoting benefits of Bifidobacterium spp. and their applications in food have gradually been widely concerned. The main purpose of this review is to comprehensively introduce general features, colonization methods, and safety of Bifidobacterium spp. in the human gut, highlighting its health benefits and industrial applications. On this basis, the existing limitations and scope for future research are also discussed. Bifidobacteria have beneficial effects on the host's digestive system, immune system, and nervous system. However, the first prerequisite for functioning is to have enough live bacteria before consumption and successfully colonize the colon after ingestion. At present, strain breeding, optimization (e.g., selecting acid and bile resistant strains, adaptive evolution, high cell density culture), and external protection technology (e.g., microencapsulation and protectants) are the main strategies to address these challenges in food application.

Amoxicillin does not affect the development of cow’s milk allergy in a Brown Norway rat model

The use of antibiotics as well as changes in the gut microbiota have been linked to development of food allergy in childhood. It remains unknown whether administration of a single clinically relevant antibiotic directly promotes food allergy development when administrated during the sensitisation phase in an experimental animal model. We investigated whether the antibiotic amoxicillin affected gut microbiota composition, development of cow's milk allergy (CMA) and frequencies of allergic effector cells and regulatory T cells in the intestine. Brown Norway rats were given daily oral gavages of amoxicillin for six weeks and whey protein concentrate (WPC) with or without cholera toxin three times per week for the last five weeks. Microbiota composition in faeces and small intestine was analysed by 16S rRNA sequencing. The development of CMA was assessed by WPC‐specific IgE in serum, ear swelling response to WPC and body hypothermia following oral gavage of WPC. Allergic effector cells were analysed by histology, and frequencies of regulatory and activated T cells were analysed by flow cytometry. Amoxicillin administration reduced faecal microbiota diversity, reduced the relative abundance of Firmicutes and increased the abundance of Bacteroidetes and Proteobacteria. Despite these effects, amoxicillin did not affect the development of CMA, nor the frequencies of allergic effector cells or regulatory T cells. Thus, amoxicillin does not carry a direct risk for food allergy development when administrated in an experimental model of allergic sensitisation to WPC via the gut. This finding suggests that confounding factors may better explain the epidemiological link between antibiotic use and food allergy.

Role of Bifidobacteria on Infant Health

Bifidobacteria are among the predominant microorganisms during infancy, being a dominant microbial group in the healthy breastfed infant and playing a crucial role in newborns and infant development. Not only the levels of the Bifidobacterium genus but also the profile and quantity of the different bifidobacterial species have been demonstrated to be of relevance to infant health. Although no definitive proof is available on the causal association, reduced levels of bifidobacteria are perhaps the most frequently observed alteration of the intestinal microbiota in infant diseases. Moreover, Bifidobacterium strains have been extensively studied by their probiotic attributes. This review compiles the available information about bifidobacterial composition and function since the beginning of life, describing different perinatal factors affecting them, and their implications on different health alterations in infancy. In addition, this review gathers exhaustive information about pre-clinical and clinical studies with Bifidobacterium strains as probiotics in neonates.

Gut Microbiota Regulation and Their Implication in the Development of Neurodegenerative Disease

In recent years, human gut microbiota have become one of the most promising areas of microorganism research; meanwhile, the inter-relation between the gut microbiota and various human diseases is a primary focus. As is demonstrated by the accumulating evidence, the gastrointestinal tract and central nervous system interact through the gut–brain axis, which includes neuronal, immune-mediated and metabolite-mediated pathways. Additionally, recent progress from both preclinical and clinical studies indicated that gut microbiota play a pivotal role in gut–brain interactions, whereas the imbalance of the gut microbiota composition may be associated with the pathogenesis of neurological diseases (particularly neurodegenerative diseases), the underlying mechanism of which is insufficiently studied. This review aims to highlight the relationship between gut microbiota and neurodegenerative diseases, and to contribute to our understanding of the function of gut microbiota in neurodegeneration, as well as their relevant mechanisms. Furthermore, we also discuss the current application and future prospects of microbiota-associated therapy, including probiotics and fecal microbiota transplantation (FMT), potentially shedding new light on the research of neurodegeneration.

Altered gut microbiome compositions are associated with the severity of asthma

Background

Despite substantial evidence on the contribution of the diversity of the gut microbiome to the pathogenesis of asthma and allergic diseases, little is known about their relationship with asthma severity and/or clinical phenotypes. We analyzed the difference in composition of the gut microbiome between subjects with asthma and healthy subjects and explored its role in the development of asthma.

Methods

Fecal samples from 15 subjects with severe asthma (SA), 14 with non-severe asthma (NSA), and 15 healthy subjects were assessed by 16S ribosomal RNA gene sequencing methods to identify the gut bacterial composition.

Results

Compared with those in the NSA group, patients in the SA group had a higher dose of inhaled corticosteroids, and there were more atopic subjects (60% vs. 35.7%, respectively). No significant differences were found at the phylum level either in operational taxonomic unit numbers or in diversity scores among the SA, NSA, and healthy groups. However, at the family level, the relative abundance of Acidaminococcaceae in the SA group was remarkedly lower than that in the group with healthy subjects (P<0.05). Furthermore, Veillonellaceae and Prevotellaceae were significantly more common in samples from the SA group than in those from the NSA group (P<0.05). In the SA group, positive correlations were observed between the relative abundance of Veillonellaceae and mid-expiratory flow 25% (MEF25%) predicted (r=0.538, P=0.047), as well as between the relative abundance of Acidaminococcaceae and body mass index (r=0642, P=0.010). Principal component analysis suggested that the relative abundances of Acidaminococcaceae and Prevotellaceae were associated with severe asthma. Moreover, we found that class Betaproteobacteria, order Burkholderiales, and family Alcaligenaceae were significantly different among the groups defined by serum immunoglobulin E (IgE) levels.

Conclusions

Our findings suggest that altered gut microbiome compositions are involved in the severity of asthma and that there are specific bacteria related to different asthma phenotypes in terms of serum IgE levels.

Raw Milk-Induced Protection against Food Allergic Symptoms in Mice Is Accompanied by Shifts in Microbial Community Structure

The mechanism underlying the allergy-protective effects of raw cow’s milk is still unknown, but the modulation of the gut microbiome may play a role. The effects of consuming raw cow’s milk or processed milk on fecal microbial communities were therefore characterized in an experimental murine model. C3H/HeOuJ mice were treated with raw milk, pasteurized milk, skimmed raw milk, pasteurized milk supplemented with alkaline phosphatase (ALP), or phosphate-buffered saline (PBS) for eight days prior to sensitization and challenge with ovalbumin (OVA). Fecal samples were collected after milk exposure and after OVA sensitization, and microbiomes were characterized using 16S ribosomal RNA gene amplicon sequencing. Treatment with raw milk prior to OVA sensitization increased the relative abundance of putative butyrate-producing bacteria from the taxa Lachnospiraceae UCG-001, Lachnospiraceae UCG-008, and Ruminiclostridium 5 (Clostridial clusters XIVa and IV), while it decreased the relative abundance of Proteobacterial genera such as Parasutterella, a putative pro-inflammatory bacterial genus. This effect was observed after eight days of raw milk exposure and became more pronounced five weeks later, after allergic sensitization in the absence of milk. Similar trends were observed after treatment with skimmed raw milk. Conversely, the feeding of pasteurized milk led to a loss of allergy protection and a putative dysbiotic microbiome. The addition of ALP to pasteurized milk restored the protective effect observed with raw milk and mitigated some of the microbial community alterations associated with milk pasteurization. Raw milk-induced protection against food allergic symptoms in mice is accompanied by an increased relative abundance of putative butyrate-producing Clostridiales and a decreased relative abundance of putative pro-inflammatory Proteobacteria. Given the safety concerns regarding raw milk consumption, this knowledge is key for the development of new, microbiologically safe, preventive strategies to reduce the incidence of allergic diseases.

Differences in gut microbiota between allergic rhinitis, atopic dermatitis, and skin urticaria: A pilot study

INTRODUCTION

Several forms of allergy have been clinically presented, including, among others, atopic dermatitis (eczema), urticaria (hives), and allergic rhinitis (rhinitis). As their detailed pathogenesis continues to be researched, we aimed in the current study to compare gut microbiota differences between eczema, hives, and rhinitis patients.

METHODS

We enrolled 19 eczemas, nine hives, and 11 allergic rhinitis patients in this study. Fecal samples were examined using 16S ribosomal ribonucleic acid amplicon sequencing, followed by bioinformatics and statistical analyses. We compared microbiota in dermatitis (eczema), chronic urticaria (hives), and allergic rhinitis (rhinitis).

RESULTS

All clinical data were similar between the subgroups. The microbiota results indicated that Bacteroidales species were found in skin allergies, both urticaria and eczema, when compared to rhinitis. The microbiota differs substantially between those patients with atopic dermatitis (eczema), chronic urticaria (hives), and allergic rhinitis (rhinitis), thus indicating that the gut-skin and gut-nose axes exist. Gut flora colonies differ significantly between skin allergy and nose allergy. Bacteroidales species could be a clinical link between gut flora and skin allergy; of those, Bacteroids Plebeius DSM 17135 is significantly associated with the urticaria (hives) subgroup.Conclusion. Our results demonstrated high intra-group homogeneous and high inter-group heterogeneous microbiota. The clinical symptoms of eczema, hives, and rhinitis can all be linked to specific microbiota in the current study. In this pilot study, the Ruminococcaceae and Bacteroidales species are associated with allergic disease, in line with several previous published articles, and the abundance of Firmicutes Phylum is representative of intestinal dysbiosis. In the future, a larger cohort and thorough biochemical studies are needed for confirmation.

A systematic review of the association between fibromyalgia and functional gastrointestinal disorders

BACKGROUND

Fibromyalgia and functional gastrointestinal disorders (FGID) including irritable bowel syndrome (IBS) are common conditions presenting in clinical settings and are more prevalent in women. While the relationship between IBS and fibromyalgia has been demonstrated, a review of the prevalence of the broader group of FGID in adults with fibromyalgia has not been undertaken. The aim of this review was to systematically review the published literature, identifying the comorbidity of FGID in people with fibromyalgia, and to discuss the clinical implications, limitations of current research and areas of interest for future research.

METHODS

Medline, Embase, CINAHL and Web of Science were searched during June 2019. Results were screened for original research articles meeting established criteria for identification of FGID in adults diagnosed with fibromyalgia.

RESULTS

A total of 14 studies involving 1340 adults with fibromyalgia, 363 healthy controls and 441 adults with other pathologies were included in this review. Only 1 of the 14 studies included surveyed the full range of FGID . Functional gut disorders were matched to Rome II criteria for reporting and comparison. In addition to increased abdominal pain and functional bloating or gas, IBS of mixed-pattern and constipation-types appear to be more prevalent than diarrhoea-predominant IBS in adults with fibromyalgia.

CONCLUSION

This review confirms previous reports that IBS is common in people living with fibromyalgia and suggests that IBS-mixed and constipation types predominate. An association with a range of FGID other than IBS is suggested, but data are limited. Research exploring the association between fibromyalgia and functional gastrointestinal dysfunction beyond IBS are warranted.

The Bifidogenic Effect Revisited-Ecology and Health Perspectives of Bifidobacterial Colonization in Early Life

Extensive microbial colonization of the infant gastrointestinal tract starts after parturition. There are several parallel mechanisms by which early life microbiome acquisition may proceed, including early exposure to maternal vaginal and fecal microbiota, transmission of skin associated microbes, and ingestion of microorganisms present in breast milk. The crucial role of vertical transmission from the maternal microbial reservoir during vaginal delivery is supported by the shared microbial strains observed among mothers and their babies and the distinctly different gut microbiome composition of caesarean-section born infants. The healthy infant colon is often dominated by members of the keystone genus Bifidobacterium that have evolved complex genetic pathways to metabolize different glycans present in human milk. In exchange for these host-derived nutrients, bifidobacteria's saccharolytic activity results in an anaerobic and acidic gut environment that is protective against enteropathogenic infection. Interference with early-life microbiota acquisition and development could result in adverse health outcomes. Compromised microbiota development, often characterized by decreased abundance of Bifidobacterium species has been reported in infants delivered prematurely, delivered by caesarean section, early life antibiotic exposure and in the case of early life allergies. Various microbiome modulation strategies such as probiotic, prebiotics, synbiotics and postbiotics have been developed that are able to generate a bifidogenic shift and help to restore the microbiota development. This review explores the evolutionary ecology of early-life type Bifidobacterium strains and their symbiotic relationship with humans and discusses examples of compromised microbiota development in which stimulating the abundance and activity of Bifidobacterium has demonstrated beneficial associations with health.

Lactobacillus rhamnosus 2016SWU.05.0601 regulates immune balance in ovalbumin-sensitized mice by modulating expression of the immune-related transcription factors and gut microbiota

BACKGROUND

Probiotics regulate host immune balance, which may reduce immune-related diseases. The effects and mechanisms of Lactobacillus rhamnosus 2016SWU.05.0601 (Lr-0601) on the immune response in ovalbumin (OVA)-sensitized mice were explored.

RESULTS

Lr-0601 reduced serum immunoglobulin (Ig)E and OVA-IgE and attenuated the alteration in lung pathology in OVA-sensitized mice. Lr-0601 blocked OVA-induced up-regulation in serum T helper (Th) 2 and Th17 cytokines but increased the serum levels of Th1 and regulatory T (Treg) cytokines in OVA-sensitized mice. OVA also markedly reduced the protein levels of spleen T-box transcription factor and forkhead/winged helix transcription factor p3, leading to the reduced mRNA expression of interferon-γ and interleukin (IL)-10. By contrast, OVA markedly increased the protein expression of spleen GATA-binding protein 3 and retinoid-related orphan receptor γt, as well as the mRNA expression of spleen IL-4 and IL-17. These changes induced by OVA were reversed by Lr-0601. Moreover, Lr-0601 helped alleviate OVA-induced intestinal microbiota dysbiosis. A correlation was found between specific genera and immune-associated cytokines.

CONCLUSION

The combined results indicate that Lr-0601 modulated the balance of Th1/Th2 and Treg/Th17 in OVA-sensitized mice, which was associated with the regulation of immune-related transcription factors and gut microbiota. Lr-0601 can potentially be used as a probiotic for preventing immune-related diseases. © 2020 Society of Chemical Industry.

The Gut Microbiome of Adults with Allergic Rhinitis Is Characterised by Reduced Diversity and an Altered Abundance of Key Microbial Taxa Compared to Controls

INTRODUCTION

Unique gut microbial colonisation patterns are associated with the onset of allergic disease in infants; however, there is insufficient evidence to determine if aberrant microbial composition patterns persist in adult allergic rhinitis (AR) sufferers.

OBJECTIVE

To compare the gut microbiome composition between adult AR sufferers and controls.

METHODS

Gut microbial composition in stool samples was compared between 57 adult AR sufferers (39.06 ± 13.29 years) and 23 controls (CG; 36.55 ± 10.51 years) via next-generation sequencing of the V3-V4 hypervariable regions of the 16S rRNA gene. Taxonomic classification and identity assignment was performed using a reference-based approach with the NCBI database of 16S rRNA gene sequences.

RESULTS

Species richness determined via the Shannon index was significantly reduced in the AR cohort compared to the CG (4.35 ± 0.59 in AR vs. 4.65 ± 0.55 in CG, p = 0.037); trends for reductions in operational taxonomic unit (OTU) counts, inverse Simpson, and CHAO1 diversity indices were also noted. Bacteroidetes (p = 0.014) was significantly more abundant in the AR group than in the CG. In contrast, the Firmicutes phylum was significantly less abundant in the AR group than in the CG (p = 0.006). An increased abundance of Parabacteroides (p = 0.008) and a reduced abundance of Oxalobacter (p = 0.001) and Clostridiales (p = 0.005) were also observed in the AR cohort compared to the CG.

CONCLUSION

Adult AR sufferers have a distinct gut microbiome profile, marked by a reduced microbial diversity and altered abundance of certain microbes compared to controls. The results of this study provide evidence that unique gut microbial patterns occur in AR sufferers in adulthood and warrant further examination in the form of mechanistic studies.

Diversity analysis of gut microbiota between healthy controls and those with atopic dermatitis in a Chinese population

An increasing body of evidence suggests that gut microbiota is involved in atopic dermatitis (AD). We aimed to use high-throughput sequencing to characterize the differences in the composition of the gut microbiota between healthy controls and patients with AD. Fecal samples from 93 volunteers were analyzed using 16S rRNA sequencing, including 44 patients with AD and 49 healthy control subjects, aged 6-22 years. Our data show that the operational taxonomic unit composition in patients with AD had greater component similarity than the healthy controls. Patients with AD had a lower alpha diversity than healthy control subjects. The relative abundance of Porphyromonadaceae, Blautia, Parabacteroides, Bacteroides ovatus, Bacteroides uniformis and Prevotella stercorea was significantly higher (P < 0.05) in patients with AD than healthy control subjects. Clostridium and P. stercorea were higher (P < 0.05) in healthy control subjects compared with patients with AD. The results of linear discriminant analysis effect size show that Bacteroidaceae and Porphyromonadaceae can act as possible biomarkers associated with diagnosis of AD. However, this needs further experimental verification. Taken together, these results demonstrate the changes in microbiota composition in AD compared with a healthy control group, opening the way to future diagnosis or intervention studies.

Gut Microbiota and Lung Injury

Gut microbiota are known to impact multiple organs including the lung. The cross talk between gut microbes and lungs, termed as the "gut-lung axis," is vital for immune response and homeostasis in the airways. In this chapter, we summarized the coordinated development of microorganisms in the gut and lung, exogenous and endogenous factors related to the cross talk, the mechanisms of the gut-lung axis and their dysbiosis in lung diseases. Although the current understanding of the gut-lung axis is in its infancy, several gut microbiota-associated strategies have been designed to treat and prevent lung diseases.

The Human Microbiome and Its Impacts on Health

The human microbiome comprises bacteria, archaea, viruses, and eukaryotes which reside within and outside our bodies. These organisms impact human physiology, both in health and in disease, contributing to the enhancement or impairment of metabolic and immune functions. Micro-organisms colonise various sites on and in the human body, where they adapt to specific features of each niche. Facultative anaerobes are more dominant in the gastrointestinal tract, whereas strict aerobes inhabit the respiratory tract, nasal cavity, and skin surface. The indigenous organisms in the human body are well adapted to the immune system, due to the biological interaction of the organisms with the immune system over time. An alteration in the intestinal microbial community plays a major role in human health and disease pathogenesis. These alterations result from lifestyle and the presence of an underlying disease. Dysbiosis increases host susceptibility to infection, and the nature of which depends on the anatomical site involved. The unique diversity of the human microbiota accounts for the specific metabolic activities and functions of these micro-organisms within each body site. It is therefore important to understand the microbial composition and activities of the human microbiome as they contribute to health and disease.

Gut microbiota of children with atopic dermatitis: Controlled study in the metropolitan region of São Paulo, Brazil

BACKGROUND

It is possible that imbalances in the composition of the gut microbiota or the relationship of the microbiota with the host may be implicated in the origin of allergy. Therefore, we studied the intestinal microbiota of children with atopic dermatitis (AD).

METHODS

Cross-sectional study with 81 children aged 5-11; 23 with AD and 58 controls. Surveys were conducted to obtain demographic, socioeconomic and neonatal data. Diagnosis of AD was made based on the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Eubacteria, Bacteroidetes, Firmicutes, B. fragilis, E. coli, Lactobacillus spp., S. aureus, E. faecalis, Salmonella spp., M. smithii, Bifidobacterium spp., C. difficile and C. perfringens were quantified using real-time PCR.

RESULTS

The analysis showed an association between presence of C. difficile (OR: 5.88; 95 % CI: 1.24; 27.98), greater abundance of bifidobacteria (OR: 11.09; 95 % CI: 2.14; 57.39) and a lower abundance of lactobacilli (OR: 0.07; 95 % CI: 0.01; 0.51) in the gut microbiota of children with AD. Counts of Eubacteria (0,05×10³ and 8.49×10³), B. fragilis (0.72×10⁹ and 4.5×10⁹), Lactobacillus spp. (0.02×10⁸ and 0.38×10⁸), E. coli (0.13×10⁹ and 1.52×10⁹) and M. smithii (0.02×10⁸ and 0.31×10⁸) were lower in children with AD (P<0.05).

CONCLUSIONS

This study confirmed that children living in the metropolitan area of São Paulo (Brazil) with AD have a different microbiota pattern with higher prevalence of C. difficile, lower abundance of Lactobacillus and greater abundance of bifidobacteria, regardless of socioeconomic status.

Case-Control Study of the Effects of Gut Microbiota Composition on Neurotransmitter Metabolic Pathways in Children With Attention Deficit Hyperactivity Disorder

Background

Attention-deficit/hyperactivity disorder (ADHD) is a neuropsychiatric condition that may be related to an imbalance of neural transmitters. The gut microbiota is the largest ecosystem in the human body, and the brain-gut axis theory proposes that the gut microbiome can affect brain function in multiple ways. The purpose of this study was to explore the gut microbiota in children with ADHD and assess the possible role of the gut microbiota in disease pathogenesis to open new avenues for ADHD treatment.

Methods

A case-control design was used. We enrolled 17 children aged 6-12 years with ADHD who were treated in the Pediatric Outpatient Department of the First Medical Center of the Chinese PLA General Hospital from January to June, 2019. Seventeen children aged 6-12 years were selected as the healthy control (HC) group. Fecal samples of cases and controls were analyzed by shotgun metagenomics sequencing. Alpha diversity and the differences in the relative abundances of bacteria were compared between the two groups. Functional annotations were performed for the microbiota genes and metabolic pathways were analyzed using the Kyoto Encyclopedia of Genes and Genomes (KEGG).

Results

There was no significant difference in the alpha diversity of gut microbiota between the ADHD and HC groups. Compared with HCs, Faecalibacterium and Veillonellaceae were significantly reduced in children with ADHD (P < 0.05), Odoribacter and Enterococcus were significantly increased [linear discriminant analysis (LDA) > 2]. At the species level, Faecalibacterium prausnitzii, Lachnospiraceae bacterium, and Ruminococcus gnavus were significantly reduced in the ADHD group (P < 0.05), while Bacteroides caccae, Odoribacter splanchnicus, Paraprevotella xylaniphila, and Veillonella parvula were increased (P < 0.05). Metabolic pathway analysis revealed significant between-group differences in the metabolic pathways of neurotransmitters (e.g., serotonin and dopamine) (P < 0.05).

Conclusion

Composition differences of gut microbiota in subjects with ADHD may contribute to brain-gut axis alterations and affect neurotransmitter levels, which could contribute to ADHD symptoms.

The role of gut microbiota in atopic asthma and allergy, implications in the understanding of disease pathogenesis

Asthma is a clinical syndrome characterized by chronic airway inflammation. There is mounting evidence on the role of microbiota in the development of asthma. This review focuses on the role of microbiota in maintaining the integrity of the epithelia and their role in regulating the immune response. The review compiles data from multiple studies on the role of microbiota in the innate immune response and the development and differentiation of CD4⁺ T cells, a major component of the adaptive arm of the immune response. As a result of dysbiosis, invariant natural killer T cells may induce T helper 2 cell differentiation and immunoglobulin E isotype switching through the release of interleukin-4 and interleukin-13. Furthermore, degradation of immunoglobulin A antibodies, increased circulating mast cells and basophils, and inflammation are among other mechanisms by which dysbiosis can induce or exacerbate asthma. After explaining the underlying mechanisms, the review derives conclusions from studies that investigate dysbiosis in infancy and the development of asthma later in life. The review also includes studies that investigate asthmatic mothers and the development of asthma in children and the role of dysbiosis in that regard. Finally, the review explains the statistical relationship between eczema and asthma through multiple studies that investigate the role of dysbiosis in both atopic states. This review provides insight into the role of dysbiosis in asthma, and an understanding that is required to establish clinical trials which aim to modulate the gut microbiota as a means of preventing and treating asthma.

Paediatricians play a key role in preventing early harmful events that could permanently influence the development of the gut microbiota in childhood

AIM

The development of the gut microbiota occurs primarily during infancy, and growing evidence has emphasised its positive role and implications for human health. The aim of this review was to provide essential knowledge about the gut microbiota and to describe and highlight the importance of the factors that influence the gut microbiota in early life and their potential harmful effects later in life.

METHODS

The European Paediatric Association, the Union of the National European Paediatric Societies and Associations, convened a panel of independent European experts to summarise the research on microbiota for general paediatricians. They used PubMed and the Cochrane Library to identify studies published in English up to June 2018.

RESULTS

A number of clinical conditions can disrupt the development of a stable gut microbiota. Changes in the microbiome have been documented in many chronic diseases, mainly immune-mediated gastrointestinal and liver diseases, and distinct patterns have been associated with each specific disease. The gut microbiota can be positively modulated with probiotics, prebiotics, synbiotics, paraprobiotics and postbiotics.

CONCLUSION

Paediatricians can play a key role in preventing harmful events that could permanently influence the composition and/or function of the gut microbiota. Various treatment strategies can be used.

Phthalate exposure alters gut microbiota composition and IgM vaccine response in human newborns

Postnatal exposure to di-(2-ethylhexyl) phthalate (DEHP), a common plasticizer, is associated with allergy development in childhood, suggesting that DEHP exposure may dysregulate immune response in infants. We investigated whether DEHP exposure in newborns through medical treatment affected the gut microbiota pattern and vaccine response, which are both related to immune development. In this prospective cohort study from May 1, 2016 through July 31, 2017, newborns with respiratory distress who were given intravenous infusions (IVs) were enrolled as the DEHP group, and newborns who did not receive IVs were enrolled as the control group. We excluded patients with perinatal maternal probiotics, vaginal delivery, antibiotic treatment, and exclusive human milk or formula feeding. Of 118 infants, urinary phthalate metabolite analysis revealed that the calculated DEHP concentrations of the newborns treated with IVs (n = 15) were higher than those in the control group (n = 10) (p = 0.0001). DEHP exposure altered bacterial communities both in composition and diversity, particularly decreases in Rothia sp. and Bifidobacterium longum in the DEHP group. Furthermore, DEHP exposure significantly enhanced anti-HBsAg-IgM responses in the DEHP group (p = 0.013). Early-life DEHP exposure alter gut microbiota of newborns and may change their immune responses in later life.

Exploring the Science behind Bifidobacterium breve M-16V in Infant Health

Probiotics intervention has been proposed as a feasible preventative approach against adverse health-related complications in infants. Nevertheless, the umbrella concept of probiotics has led to a massive application of probiotics in a range of products for promoting infant health, for which the strain-specificity, safety and efficacy findings associated with a specific probiotics strain are not clearly defined. Bifidobacterium breve M-16V is a commonly used probiotic strain in infants. M-16V has been demonstrated to offer potential in protecting infants from developing the devastating necrotising enterocolitis (NEC) and allergic diseases. This review comprehends the potential beneficial effects of M-16V on infant health particularly in the prevention and treatment of premature birth complications and immune-mediated disorders in infants. Mechanistic studies supporting the use of M-16V implicated that M-16V is capable of promoting early gut microbial colonisation and may be involved in the regulation of immune balance and inflammatory response to protect high-risk infants from NEC and allergies. Summarised information on M-16V has provided conceptual proof of the use of M-16V as a potential probiotics candidate aimed at promoting infant health, particularly in the vulnerable preterm population.

Reduced Akkermansia muciniphila and Faecalibacterium prausnitzii levels in the gut microbiota of children with allergic asthma

INTRODUCTION AND OBJECTIVES

The amounts of Akkermansia muciniphila and Faecalibacterium prausnitzii in gut microbiota are reduced in patients with allergic diseases compared to healthy controls. We aimed to quantify levels of A. muciniphila and F. prausnitzii amounts using real-time quantitative PCR (qPCR) in the gut microbiota of children with allergic asthma and in healthy controls.

MATERIALS AND METHODS

In total, 92 children between the ages of three and eight who were diagnosed with asthma and 88 healthy children were included in the study and bacterial DNA was isolated from the stool samples using the stool DNA isolation Kit. qPCR assays were studied with the microbial DNA qPCR Kit for A. muciniphila and microbial DNA qPCR Kit for F. prausnitzii.

RESULTS

Both bacterial species showed a reduction in the patient group compared to healthy controls. A. muciniphila and F. prausnitzii were found to be 5.45±0.004, 6.74±0.01 and 5.71±0.002, 7.28±0.009 in the stool samples of the asthma and healthy control groups, respectively.

CONCLUSIONS

F. prausnitzii and A. muciniphila may have induced anti-inflammatory cytokine IL-10 and prevented the secretion of pro-inflammatory cytokines like IL-12. These findings suggest that A. muciniphila and F. prausnitzii may suppress inflammation through its secreted metabolites.

Dynamic construction of gut microbiota may influence allergic diseases of infants in Southwest China

BACKGROUND

Gut microbes have been suggested as the possible targets in the management of allergic diseases. However, the way in which these microbes influence allergic diseases remain unclear. Forty-seven full-term newborns were selected from a 1000-infant birth cohort. Among them were 23 allergic infants, whereas 24 infants were healthy without allergic symptoms at 1 year of age. Two hundred and sixty-four fecal samples were collected at 7 time points following their birth. These fecal samples were microbiologically analyzed using 16S rRNA gene sequencing. The dynamic processes involved in gut microbiota diversity and composition in the tested infants were constructed.

RESULTS

Healthy infants demonstrated more statistical differences in longitudinal changes in the alpha diversity of their microbiota at the time points compared with day 0 (meconium) than did allergic infants. Analysis of beta diversity showed that the fecal microbiota of days 0 and 2 comprised different communities in healthy infants, and that there were three separate communities in the fecal microbiota of day 0 of the healthy infants, those of day 2 of the healthy infants, and those of days 0-2 of the allergic infants. The relative abundance of dominant gut microbiota at phylum level varied at different time points in the healthy and diseased groups. Bifidobacterium, Escherichia-Shigella, Streptococcus, Clostridium_sensu_stricto_1, Akkermansia and Erysipelatoclostridium were significantly different between the healthy and diseased groups at a different time points.

CONCLUSION

The dynamic construction processes of gut microbiota during early life might be associated with the occurrence of long-term allergic diseases, with the first month following birth potentially being the most critical.

Chinese herbal medicine bi min fang for allergic rhinitis: protocol for a double-blind, double-dummy, randomized controlled trial

BACKGROUND

People with allergic rhinitis (AR) often seek help from Chinese medicine due to dissatisfaction with conventional treatments. Lung-spleen qi deficiency syndrome (LSQDS) is the most common type of AR, and the Chinese herbal medicine formula bi min fang (BMF) is commonly prescribed for AR patients with LSQDS. However, direct evidence supporting its efficacy and safety is not available, and its potential mechanism of action remains unclear.

METHODS/DESIGN

This paper presents a double-blind, double-dummy, randomized controlled trial. After a 2-week run-in period, 80 AR patients with LSQDS will be recruited and randomly allocated to the BMF group or the control group in a 1:1 ratio. The patients in the BMF group will receive BMF and the placebo for levocetirizine hydrochloride orally, while the control group participants will receive levocetirizine hydrochloride and the placebo for BMF orally. All participants will receive 4 weeks of treatment and 12 weeks of follow-up. The primary outcome is a change in the Total Nasal Symptom Score (TNSS). Secondary outcomes include changes in scores for the standard version of the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ(S)), and visual analog scale (VAS); changes in serum levels of the cytokines interleukin-4, interferon-γ, transforming growth factor β-1, and interleukin-17; and changes in the gut microbiota composition in the stool. The TNSS, RQLQ(S), and VAS will be recorded at the beginning of, middle of and after the treatment period and at the end of each month in the 3-month follow-up period. Blood and stool samples will be collected at baseline and the end of the treatment. The aforementioned four cytokines will be detected in the serum using enzyme-linked immunosorbent assays, and the stool gut microbiota will be detected using 16S ribosomal ribonucleic acid sequencing. Any side effects of the treatment will be recorded.

DISCUSSION

The results of this trial will provide consolidated evidence of the effect of BMF on AR and the potential mechanism by which BMF acts. This study will be the first to explore the mechanism of action of Chinese herbal medicine on the gut microbiota in AR.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR-IPR-17010970 . Registered on 23 March 2017.

Bifidobacterium longum IM55 and Lactobacillus plantarum IM76 alleviate allergic rhinitis in mice by restoring Th2/Treg imbalance and gut microbiota disturbance

This study aimed to examine whether probiotics, which suppressed the differentiation of splenic T cells into type 2 helper T (Th2) cells and induced into regulatory T cells in vitro, alleviate allergic rhinitis (AR) and gut microbiota disturbance. We isolated Bifidobacterium longum IM55 and Lactobacillus plantarum IM76 from human faecal microbiota and kimchi, respectively, and examined their effects on ovalbumin (OVA)-induced AR and gut microbiota disturbance in mice. Treatment with IM55, IM76, or their probiotic mixture (PM) significantly reduced OVA-induced allergic nasal symptoms and blood immunoglobulin E (IgE) levels in mice. These also reduced OVA-induced interleukin (IL)-4 and IL-5 levels in nasal tissues and bronchoalveolar lavage fluid (BALF) but increased OVA-suppressed IL-10 levels. Treatment with IM55, IM76, or PM reduced OVA-induced increase in the populations of mast cells, eosinophils, and Th2 cells and increased OVA-suppressed population of regulatory T cells in the BALF. Treatment with IM55, IM76, or PM also inhibited OVA-induced expression of IL-5 in lung and colon tissues and restored OVA-disturbed composition of gut microbiota Proteobacteria, Bacteroidetes, and Actinobacteria. These results suggest that IM55 and IM67 can alleviate AR by restoring Th2/Treg imbalance and gut microbiota disturbance.

Effect of Dietary Fiber and Metabolites on Mast Cell Activation and Mast Cell-Associated Diseases

Many mast cell-associated diseases, including allergies and asthma, have seen a strong increase in prevalence during the past decades, especially in Western(ized) countries. It has been suggested that a Western diet may contribute to the prevalence and manifestation of allergies and asthma through reduced intake of dietary fiber and the subsequent production of their metabolites. Indeed, dietary fiber and its metabolites have been shown to positively influence the development of immune disorders via changes in microbiota composition and the regulation of B- and T-cell activation. However, the effects of these dietary components on the activation of mast cells, key effector cells of the inflammatory response in allergies and asthma, remain poorly characterized. Due to their location in the gut and vascularized tissues, mast cells are exposed to high concentrations of dietary fiber and/or its metabolites. Here, we provide a focused overview of current findings regarding the direct effects of dietary fiber and its various metabolites on the regulation of mast cell activity and the pathophysiology of mast cell-associated diseases.

The protective effect of Lactobacillus and Bifidobacterium as the gut microbiota members against chronic urticaria

BACKGROUND

Chronic Urticaria is a common disorder which is defined by recurrent occurrence of wheals and sometimes angioedema. It has a notable influence on the patients' quality of life. Regulation of the immune system is one of the important roles of the gut microbiota. The effect of dysbiosis considering some members of gut microbiota in patients with chronic urticaria has been demonstrated in our previous study.

OBJECTIVE

Comparing the frequency and bacterial load of Lactobacillus, Bifidobacterium, and Bacteroides between patients with chronic urticaria and healthy controls.

METHODS

20 patients with chronic urticaria and 20 age and sex matched healthy individuals were included in the present study. Stool samples were analyzed for determining the frequency and bacterial load of Lactobacillus, Bifidobacterium, and Bacteroides genera.

RESULTS

There were no significant differences among the frequencies of detectable Lactobacillus, Bifidobacterium, or Bacteroides in stool samples of patients with chronic urticaria and healthy controls. The relative amounts of Lactobacillus and Bifidobacterium were significantly higher in fecal samples from controls compared to patients with chronic urticaria (P = 0.038 and 0.039, respectively).

CONCLUSION

It is the first study on the implication of Lactobacillus, Bifidobacterium, and Bacteroides genera as gut microbiota members in patients with chronic urticaria.

The developing gut microbiota and its consequences for health

The developmental origin of health and disease highlights the importance of the period of the first 1000 days (from the conception to the 2 years of life). The process of the gut microbiota establishment is included in this time window. Various perinatal determinants, such as cesarean section delivery, type of feeding, antibiotics treatment, gestational age or environment, can affect the pattern of bacterial colonization and result in dysbiosis. The alteration of the early bacterial gut pattern can persist over several months and may have long-lasting functional effects with an impact on disease risk later in life. As for example, early gut dysbiosis has been involved in allergic diseases and obesity occurrence. Besides, while it was thought that the fetus developed under sterile conditions, recent data suggested the presence of a microbiota in utero, particularly in the placenta. Even if the origin of this microbiota and its eventual transfer to the infant are nowadays unknown, this placental microbiota could trigger immune responses in the fetus and would program the infant's immune development during fetal life, earlier than previously considered. Moreover, several studies demonstrated a link between the composition of placental microbiota and some pathological conditions of the pregnancy. All these data show the evidence of relationships between the neonatal gut establishment and future health outcomes. Hence, the use of pre- and/or probiotics to prevent or repair any early dysbiosis is increasingly attractive to avoid long-term health consequences.

International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis

BACKGROUND

Critical examination of the quality and validity of available allergic rhinitis (AR) literature is necessary to improve understanding and to appropriately translate this knowledge to clinical care of the AR patient. To evaluate the existing AR literature, international multidisciplinary experts with an interest in AR have produced the International Consensus statement on Allergy and Rhinology: Allergic Rhinitis (ICAR:AR).

METHODS

Using previously described methodology, specific topics were developed relating to AR. Each topic was assigned a literature review, evidence-based review (EBR), or evidence-based review with recommendations (EBRR) format as dictated by available evidence and purpose within the ICAR:AR document. Following iterative reviews of each topic, the ICAR:AR document was synthesized and reviewed by all authors for consensus.

RESULTS

The ICAR:AR document addresses over 100 individual topics related to AR, including diagnosis, pathophysiology, epidemiology, disease burden, risk factors for the development of AR, allergy testing modalities, treatment, and other conditions/comorbidities associated with AR.

CONCLUSION

This critical review of the AR literature has identified several strengths; providers can be confident that treatment decisions are supported by rigorous studies. However, there are also substantial gaps in the AR literature. These knowledge gaps should be viewed as opportunities for improvement, as often the things that we teach and the medicine that we practice are not based on the best quality evidence. This document aims to highlight the strengths and weaknesses of the AR literature to identify areas for future AR research and improved understanding.

Steroids, stress and the gut microbiome-brain axis

It is becoming well established that the gut microbiome has a profound impact on human health and disease. In this review, we explore how steroids can influence the gut microbiota and, in turn, how the gut microbiota can influence hormone levels. Within the context of the gut microbiome-brain axis, we discuss how perturbations in the gut microbiota can alter the stress axis and behaviour. In addition, human studies on the possible role of gut microbiota in depression and anxiety are examined. Finally, we present some of the challenges and important questions that need to be addressed by future research in this exciting new area at the intersection of steroids, stress, gut-brain axis and human health.