Early-life vancomycin treatment promotes airway inflammation and impairs microbiome homeostasis

Gut-lung axis and asthma: A historical review on mechanism and future perspective

BACKGROUND

Gut microbiota are closely related to the development and regulation of the host immune system by regulating the maturation of immune cells and the resistance to pathogens, which affects the host immunity. Early use of antibiotics disrupts the homeostasis of gut microbiota and increases the risk of asthma. Gut microbiota actively interact with the host immune system via the gut-lung axis, a bidirectional communication pathway between the gut and lung. The manipulation of gut microbiota through probiotics, helminth therapy, and fecal microbiota transplantation (FMT) to combat asthma has become a hot research topic. BODY: This review mainly describes the current immune pathogenesis of asthma, gut microbiota and the role of the gut-lung axis in asthma. Moreover, the potential of manipulating the gut microbiota and its metabolites as a treatment strategy for asthma has been discussed.

CONCLUSION

The gut-lung axis has a bidirectional effect on asthma. Gut microecology imbalance contributes to asthma through bacterial structural components and metabolites. Asthma, in turn, can also cause intestinal damage through inflammation throughout the body. The manipulation of gut microbiota through probiotics, helminth therapy, and FMT can inform the treatment strategies for asthma by regulating the maturation of immune cells and the resistance to pathogens.

The gut metagenome harbors metabolic and antibiotic resistance signatures of moderate-to-severe asthma

Asthma is a common allergic airway disease that has been associated with the development of the human microbiome early in life. Both the composition and function of the infant gut microbiota have been linked to asthma risk, but functional alterations in the gut microbiota of older patients with established asthma remain an important knowledge gap. Here, we performed whole metagenomic shotgun sequencing of 95 stool samples from a cross-sectional cohort of 59 healthy and 36 subjects with moderate-to-severe asthma to characterize the metagenomes of gut microbiota in adults and children 6 years and older. Mapping of functional orthologs revealed that asthma contributes to 2.9% of the variation in metagenomic content even when accounting for other important clinical demographics. Differential abundance analysis showed an enrichment of long-chain fatty acid (LCFA) metabolism pathways, which have been previously implicated in airway smooth muscle and immune responses in asthma. We also observed increased richness of antibiotic resistance genes (ARGs) in people with asthma. Several differentially abundant ARGs in the asthma cohort encode resistance to macrolide antibiotics, which are often prescribed to patients with asthma. Lastly, we found that ARG and virulence factor (VF) richness in the microbiome were correlated in both cohorts. ARG and VF pairs co-occurred in both cohorts suggesting that virulence and antibiotic resistance traits are coselected and maintained in the fecal microbiota of people with asthma. Overall, our results show functional alterations via LCFA biosynthetic genes and increases in antibiotic resistance genes in the gut microbiota of subjects with moderate-to-severe asthma and could have implications for asthma management and treatment.

The lung-gut crosstalk in respiratory and inflammatory bowel disease

Both lung and gut belong to the common mucosal immune system (CMIS), with huge surface areas exposed to the external environment. They are the main defense organs against the invasion of pathogens and play a key role in innate and adaptive immunity. Recently, more and more evidence showed that stimulation of one organ can affect the other, as exemplified by intestinal complications during respiratory disease and vice versa, which is called lung-gut crosstalk. Intestinal microbiota plays an important role in respiratory and intestinal diseases. It is known that intestinal microbial imbalance is related to inflammatory bowel disease (IBD), this imbalance could impact the integrity of the intestinal epithelial barrier and leads to the persistence of inflammation, however, gut microbial disturbances have also been observed in respiratory diseases such as asthma, allergy, chronic obstructive pulmonary disease (COPD), and respiratory infection. It is not fully clarified how these disorders happened. In this review, we summarized the latest examples and possible mechanisms of lung-gut crosstalk in respiratory disease and IBD and discussed the strategy of shaping intestinal flora to treat respiratory diseases.

Effects of the loss of maternal gut microbiota before pregnancy on gut microbiota, food allergy susceptibility, and epigenetic modification on subsequent generations

Maternal environments affect the health of offspring in later life. Changes in epigenetic modifications may partially explain this phenomenon. The gut microbiota is a critical environmental factor that influences epigenetic modifications of host immune cells and the development of food allergies. However, whether changes in the maternal gut microbiota affect the development of food allergies and related epigenetic modifications in subsequent generations remains unclear. Here, we investigated the effects of antibiotic treatment before pregnancy on the development of the gut microbiota, food allergies, and epigenetic modifications in F1 and F2 mice. We found that pre-conception antibiotic treatment affected the gut microbiota composition in F1 but not F2 offspring. F1 mice born to antibiotic-treated mothers had a lower proportion of butyric acid-producing bacteria and, consequently, a lower butyric acid concentration in their cecal contents. The methylation level in the DNA of intestinal lamina propria lymphocytes, food allergy susceptibility, and production of antigen-specific IgE in the F1 and F2 mice were not different between those born to control and antibiotic-treated mothers. In addition, F1 mice born to antibiotic-treated mothers showed increased fecal excretion related to the stress response in a novel environment. These results suggest that the maternal gut microbiota is effectively passed onto F1 offspring but has little effect on food allergy susceptibility or DNA methylation levels in offspring.

Intestinal Microflora Altered by Vancomycin Exposure in Early Life Up-regulates Type 2 Innate Lymphocyte and Aggravates Airway Inflammation in Asthmatic Mice

Allergic asthma is a chronic inflammatory disease primarily mediated by Th2 immune mechanisms. Exposure to antibiotics during early life is associated with an increased risk of allergic asthma, although the exact mechanism is not fully understood. In this study, mice were randomly divided into a normal saline control group (NS group), an OVA-induced asthma group (OVA group), a vancomycin treatment control group (VAN.NS group), and a vancomycin treatment the OVA-induced asthma group (VAN.OVA group). The results showed that vancomycin altered dominant species in experimental mice. The phylum level histogram showed that Bacteroides abundance was increased, and Firmicutes abundance was decreased in the OVA group. Airway inflammation and airway hyperresponsiveness (AHR) were aggravated in the vancomycin-exposed group. Enzyme-linked immunosorbent assay (ELISA) showed that the serum levels of IL-5, IL-13, and IL-33 in the OVA group were higher than those in the NS group, especially in the VAN.OVA group. The expression of GATA binding protein-3(GATA3) and retinoid acid receptor-related orphan receptor alpha (RORa) increased in the OVA group, even more so in the VAN.OVA group. Group 2 innate lymphoid cells (ILC2s) in the lung detected by flow cytometry was increased in OVA mice more than those in control mice, with a more remarkable increase in the VAN.OVA. Our results demonstrated that vancomycin used in early life could alter the intestinal microecology of mice, which, in turn, aggravates airway inflammation and upregulate type 2 innate lymphocytes.

Relationships between antibiotic exposure and asthma in adults in the United States: results of the National Health and Nutrition Examination Survey between 1999 and 2018

Objectives

To investigate the relationship between antibiotic exposure and asthma in adults in the United States.

Methods

Data was obtained from the National Health and Nutrition Examination Survey (NHANES) conducted between 1999 and 2018. A total of 51,124 participants were included, excluding those who were aged < 20 years, female participants who were pregnant, and individuals who did not complete the prescription medications questionnaire and the medical conditions questionnaire regarding asthma status. Antibiotic exposure was defined as the utilization of antibiotics within the past 30 days, categorized based on the Multum Lexicon Plus therapeutic classification system. Asthma was defined as having a history of asthma or having an asthma attack or wheezing symptoms in the past year.

Results

The risk of asthma was found to be 2.557 (95% CI: 1.811, 3.612), 1.547 (95% CI: 1.190, 2.011) and 2.053 (95% CI: 1.344, 3.137) times greater in participants who had used macrolide derivatives, penicillin and quinolones in the past 30 days, respectively, compared with those not using antibiotics. After adjusting for demographic covariates and asthma-related factors, only macrolides derivatives were significantly associated with asthma in the 20-40 and 40-60 age groups. For individuals over 60 years old, quinolones were significantly associated with asthma. The effect of different types of antibiotic with asthma varied in male and female populations. Moreover, higher socioeconomic status, greater BMI, younger age, smoking habits, history of infection, chronic bronchitis, emphysema, and family history of asthma were all identified as risk factors for asthma.

Conclusion

Our study indicated that three types of antibiotics were significantly associated with asthma in different subgroups of the population. Therefore, the use of antibiotics should be more strictly regulated.

Human matters in asthma: Considering the microbiome in pulmonary health

Microbial communities form an important symbiotic ecosystem within humans and have direct effects on health and well-being. Numerous exogenous factors including airborne triggers, diet, and drugs impact these established, but fragile communities across the human lifespan. Crosstalk between the mucosal microbiota and the immune system as well as the gut-lung axis have direct correlations to immune bias that may promote chronic diseases like asthma. Asthma initiation and pathogenesis are multifaceted and complex with input from genetic, epigenetic, and environmental components. In this review, we summarize and discuss the role of the airway microbiome in asthma, and how the environment, diet and therapeutics impact this low biomass community of microorganisms. We also focus this review on the pediatric and Black populations as high-risk groups requiring special attention, emphasizing that the whole patient must be considered during treatment. Although new culture-independent techniques have been developed and are more accessible to researchers, the exact contribution the airway microbiome makes in asthma pathogenesis is not well understood. Understanding how the airway microbiome, as a living entity in the respiratory tract, participates in lung immunity during the development and progression of asthma may lead to critical new treatments for asthma, including population-targeted interventions, or even more effective administration of currently available therapeutics.

Vancomycin-induced gut microbiota dysbiosis aggravates allergic rhinitis in mice by altered short-chain fatty acids

OBJECTIVE

This study aims to explore how gut microbiota dysbiosis affects allergic rhinitis (AR) and whether short-chain fatty acids (SCFAs) play a role in this process.

METHODS

A mouse gut microbiota dysbiosis model was established by adding vancomycin to drinking water for 2 weeks before ovalbumin (OVA) sensitization. Then an OVA-alum AR mouse model was established by intraperitoneal OVA injection followed by nasal excitation. Hematoxylin and eosin (H&E) staining was performed to observe pathological changes in nasal and colon tissues of AR mice. Serum levels of total-IgE, OVA-sIgE, IL-4, IL-5, IL-10, and TGF-β1 were measured. The composition and diversity of the mouse gut microbiota were observed by 16S rDNA sequencing. Levels of SCFAs in feces were determined using SCFA-targeted metabolomics. Sodium butyrate (NaB) was added daily to mice on a low-fiber basal diet 2 weeks before the first sensitization, until the end of the study.

RESULTS

After gut microbiota dysbiosis, serum levels of the total IgE, OVA-sIgE, IL-4, and IL-5 in AR mice were significantly increased, compared with the control group. The composition and diversity of gut microbiota were significantly altered after gut microbiota dysbiosis, with the fecal SCFAs significantly reduced as well. The reduced bacterial genera after gut microbiota dysbiosis, such as Ruminococcus and Lactobacillus, were significantly and positively correlated with SCFAs. In contrast, the increased genera in the Van group, such as Escherichia-Shigella and Klebsiella, were significantly negatively correlated with SCFAs in feces. NaB treatment significantly reduced total-IgE, OVA-sIgE, IL-4, and IL-5 levels in serum, and inflammatory infiltration of the nasal and colon mucosa. In addition, serum levels of IL-10 and TGF-β1 increased significantly after NaB treatment. Foxp3 protein in the colon was upregulated considerably after NaB intervention.

CONCLUSION

Vancomycin-induced gut microbiota dysbiosis increased susceptibility and severity of AR, which is significantly related to reduced SCFA-producing bacteria, fecal SCFAs, and specific bacterial taxa. In addition, it was found that NaB alleviated low dietary fiber base-fed symptoms and immune status in AR mice.

Impact of Therapeutics on Unified Immunity During Allergic Asthma and Respiratory Infections

Asthma is a common chronic respiratory disease that affects millions of people worldwide. Patients with allergic asthma, the most prevalent asthma endotype, are widely considered to possess a defective immune response against some respiratory infectious agents, including viruses, bacteria and fungi. Furthermore, respiratory pathogens are associated with asthma development and exacerbations. However, growing data suggest that the immune milieu in allergic asthma may be beneficial during certain respiratory infections. Immunomodulatory asthma treatments, although beneficial, should then be carefully prescribed to avoid misuse and overuse as they can also alter the host microbiome. In this review, we summarize and discuss recent evidence of the correlations between allergic asthma and the most significant respiratory infectious agents that have a role in asthma pathogenesis. We also discuss the implications of current asthma therapeutics beyond symptom prevention.

Olmesartan Attenuates Single-Lung Ventilation Induced Lung Injury via Regulating Pulmonary Microbiota

Single-lung ventilation (SLV) associated acute lung injury is similar to ischemia reperfusion (IR) injury which is usually occurred during lung surgery. Olmesartan (Olm), a novel angiotensin receptor blocker (ARB), has been reported to ameliorate organ IR injury. Several recent studies have shown that lung microbiota may be involved in pulmonary diseases, but the effect of pulmonary microbiota in SLV-induced lung injury has not been reported. This study aims to determine the mechanism of how Olm attenuates SLV induced lung injury. Our data showed that 7 days Olm treatment before modeling markedly alleviated SLV-induced lung injury by suppressing inflammation and reactive oxygen species. Bronchoalveolar lavage fluid samples from the injured side were collected for 16S rRNA gene-based sequencing analysis and 53 different bacteria at the genus and species levels were identified. Furthermore, the injured lung samples were collected for metabolomics analysis using liquid chromatography-mass spectrometry analyses to explore differential metabolites. The Kyoto Encyclopedia of Genes and Genomes (KEGG) was applied to analyze the correlation between differential metabolites and lung microbiota. A total of 38 pathways were identified according to differential metabolites and 275 relevant pathways were enriched via analyzing the microbial community, 24 pathways were both identified by analyzing either metabolites or microbiota, including pyrimidine metabolism, purine metabolism, aminoacyl-tRNA biosynthesis and ATP-binding cassette transporter. Besides classical blockage of the renin-angiotensin II system, Olm could also alleviate SLV-induced lung injury by rewiring the interaction between pulmonary microbiota and metabolites.

Association of Sarcopenia and Gut Microbiota Composition in Older Patients with Advanced Chronic Kidney Disease, Investigation of the Interactions with Uremic Toxins, Inflammation and Oxidative Stress

Sarcopenia is a prevalent condition in chronic kidney disease (CKD). We determined gut microbiota (gMB) composition in CKD patients with or without sarcopenia. Furthermore, we investigated whether in these patients, there was any association between gMB, uremic toxins, inflammation and oxidative stress. We analyzed gMB composition, uremic toxins (indoxyl sulphate and p-cresyl sulphate), inflammatory cytokines (interleukin 10, tumor necrosis factor α, interleukin 6, interleukin 17, interleukin 12 p70, monocyte chemoattractant protein-1 and fetuin-A) and oxidative stress (malondialdehyde) of 64 elderly CKD patients (10 < eGFR < 45 mL/min/1.73 m², not on dialysis) categorized as sarcopenic and not-sarcopenic. Sarcopenia was defined according to European Working Group on Sarcopenia in Older People 2 criteria. Sarcopenic patients had a greater abundance of the Micrococcaceae and Verrucomicrobiaceae families and of Megasphaera, Rothia, Veillonella, Akkermansia and Coprobacillus genera. They had a lower abundance of the Gemellaceae and Veillonellaceae families and of Acidaminococcus and Gemella genera. GMB was associated with uremic toxins, inflammatory cytokines and MDA. However, uremic toxins, inflammatory cytokines and MDA were not different in sarcopenic compared with not-sarcopenic individuals, except for interleukin 10, which was higher in not-sarcopenic patients. In older CKD patients, gMB was different in sarcopenic than in not-sarcopenic ones. Several bacterial families and genera were associated with uremic toxins and inflammatory cytokines, although none of these latter substantially different in sarcopenic versus not-sarcopenic patients.

Microbiota: A Missing Link in The Pathogenesis of Chronic Lung Inflammatory Diseases

Chronic respiratory diseases account for high morbidity and mortality, with asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis (CF) being the most prevalent globally. Even though the diseases increase in prevalence, the exact underlying mechanisms have still not been fully understood. Despite their differences in nature, pathophysiologies, and clinical phenotypes, a growing body of evidence indicates that the presence of lung microbiota can shape the pathogenic processes underlying chronic inflammation, typically observed in the course of the diseases. Therefore, the characterization of the lung microbiota may shed new light on the pathogenesis of these diseases. Specifically, in chronic respiratory tract diseases, the human microbiota may contribute to the disease’s development and severity. The present review explores the role of the microbiota in the area of chronic pulmonary diseases, especially COPD, asthma, and CF.

Intestinal mucosal bacterial diversity of antibiotic-associated diarrhea (AAD) mice treated with Debaryomyces hansenii and Qiweibaizhu powder

The aim was to investigate the combined effect of Debaryomyces hansenii and Qiweibaizhu powder (QWBZP) on the bacterial diversity of the intestinal mucosa of antibiotic-associated diarrhea (AAD) mice, for the potential treatment of diarrhea, especially which is induced by administration of antibiotics. Eighteen (18) mice were randomly assigned to three equal groups of six mice, namely Normal (mn group), Placebo control (mm group) and D. hansenii and QWBZP (DQ) treatment (mdq group). Mice were gavaged with a solution (23.33 mL·kg^-1·day^-1) consisting of gentamicin and cefradine to establish AAD. The DQ treatment group was gavaged with DQ for 4 days, and sterile water was used as a placebo control. The metagenome DNA of the intestinal mucosal microbiota was extracted, and the 16S rRNA gene was sequenced. Analysis showed that there were 288 OTUs for the normal group, 443 for the placebo control group, and 229 for the DQ treatment group. Phylogenetically, the gut microbiota of the DQ treatment group and the normal group were closer to each other than to the placebo control group. Both the DQ and placebo-treated groups included Stenotrophomonas, Robinsoniella, Bacteroidales S24-7 group norank, Citrobacter, and Glutamicibacter, but their abundances were significantly higher in the DQ treatment group than in the placebo control group. This suggested that the combined use of D. hansenii and QWBZP overcame the influence of dysbacteriosis and could lead to the recovery of intestinal mucosal microbiota homeostasis. This positive effect is likely related to short-chain fatty acid (SCFA)-producing bacteria, such as members of Micrococcaceae, Lachnospiraceae, and Bacteroidales S24-7 group, which could play beneficial roles in protecting the mucosal barrier and stimulating the immune response in mice.

Analysis of the diversity of intestinal microbiome and its potential value as a biomarker in patients with schizophrenia: A cohort study

Exploring the gut microbiota characteristics of patients with acute and remission schizophrenia (SCZ) and evaluating the potential of the gut microbiome as a non-invasive biomarker for SCZ. A total of 87 fecal samples were collected, including a total of 58 samples from 29 SCZ patients over two different periods (remission and onset period) and 29 samples from the control group for 16S rRNA Miseq.The changes of intestinal microbiota in SCZ patients from remission to onset were analyzed, and a random forest model was constructed to recognize biomarkers. The optimal three genus-level diagnosis biomarkers were identified through an AUC validation on a random forest model, furthermore, an AUC of 0.76 (95% CI (0.63, 0.89)) was achieved between 29 aSCZ and 29 HCs. Compared with the control group, the first 11 OUT-level' biomarkers were identified in rSCZ group. As a status marker of the disease, the AUC of 0.7 (95% CI (0.56, 0.84)) was achieved between 29 rSCZ and 29 HCs. There were differences between SCZ patients and HCs, acute and remission patients as well, suggesting that the potential of the gut microbiota as a non-invasive diagnostic tool. Moreover, the features of the gut microbiome of SCZ provide clues for disease prognosis assessment and targeted intervention.

Antibiotic use during pregnancy increases offspring asthma severity in a dose-dependent manner

BACKGROUND

The use of antibiotics during pregnancy is associated with increased allergic asthma risk in the offspring, and given that approximately 25% of pregnant women are prescribed antibiotics, it is important to understand the mechanisms contributing to this phenomenon. Currently, there are no studies that directly test this association experimentally. Our objective was to develop a mouse model in which antibiotic treatment during pregnancy results in increased offspring asthma susceptibility.

METHODS

Pregnant mice were treated daily from gestation day 8-17 with an oral solution of the antibiotic vancomycin, and three concentrations were tested. At weaning, offspring were subjected to an adjuvant-free experimental asthma protocol using ovalbumin as an allergen. The composition of the gut microbiome was determined in mothers and offspring with samples collected from five different time points; short-chain fatty acids were also analyzed in allergic offspring.

RESULTS

We found that maternal antibiotic treatment during pregnancy was associated with increased offspring asthma severity in a dose-dependent manner. Furthermore, maternal vancomycin treatment during pregnancy caused marked changes in the gut microbiome composition in both mothers and pups at several different time points. The increased asthma severity and intestinal microbiome changes in pups were also associated with significantly decreased cecal short-chain fatty acid concentrations.

CONCLUSION

Consistent with the "Developmental Origins Hypothesis," our results confirm that exposure to antibiotics during pregnancy shapes the neonatal intestinal environment and increases offspring allergic lung inflammation.

The Gut Microbiota and Respiratory Diseases: New Evidence

Human body surfaces, such as the skin, intestines, and respiratory and urogenital tracts, are colonized by a large number of microorganisms, including bacteria, fungi, and viruses, with the gut being the most densely and extensively colonized organ. The microbiome plays an essential role in immune system development and tissue homeostasis. Gut microbiota dysbiosis not only modulates the immune responses of the gastrointestinal (GI) tract but also impacts the immunity of distal organs, such as the lung, further affecting lung health and respiratory diseases. Here, we review the recent evidence of the correlations and underlying mechanisms of the relationship between the gut microbiota and common respiratory diseases, including asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), lung cancer, and respiratory infection, and probiotic development as a therapeutic intervention for these diseases.

Dysbiosis of oral microbiota is associated with systemic lupus erythematosus

OBJECTIVE

The important role of intestinal microbiota in systemic lupus erythematosus (SLE) has been recognized. Oral-gut microbiome axis is a crucial link in human health and disease, but few researches indicated the relationship between oral microorganisms and SLE. This study mainly explored the composition and changes of oral microorganisms in SLE patients with different stages, clinical manifestations and biomarkers.

DESIGN

Oral microbiota was detected by 16S ribosomal RNA gene sequencing from 20 SLE patients and 19 healthy controls (HCs). The evenness, diversity and composition of oral microbiota were analyzed. Moreover, receiver-operating characteristic analysis was conducted. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) based on Kyoto Encyclopedia of Genes and Genomes (KEGG) database was used to investigate microbiota functions.

RESULTS

The oral microbiota of SLE patients was imbalanced and the diversity was decreased, but no difference was found between new-onset and treated SLE patients. Families Lactobacillaceae, Veillonellaceae and Moraxellaceae were enriched in SLE patients. Families like Corynebacteriaceae, Micrococcaceae, Defluviitaleaceae, Caulobacteraceae, Phyllobacteriaceae, Methylobacteriaceae, Hyphomicrobiaceae, Sphingomonadaceae, Halomonadaceae, Pseudomonadaceae, Xanthomonadaceae, etc. were decreased in SLE patients. After multiple testing adjustment, families Sphingomonadaceae, Halomonadaceae, and Xanthomonadaceae were significantly decreased in SLE patients. And area under the curve was 0.953 (95% confidence intervals 0.890-1.000) to distinguish SLE patients from HCs. There were differences in metabolic pathways between SLE and HCs (P = 0.025).

CONCLUSIONS

These findings collectively support that oral microbiota dysbiosis and aberrant metabolic pathways were observed in patients with SLE. Our findings may provide suggestive evidences for the diagnosis and treatment of SLE.