Respiratory and Intestinal Microbiota in Pediatric Lung Diseases-Current Evidence of the Gut-Lung Axis

Taurine supplementation alleviates asthma airway inflammation aggravated by HOCl exposure

Environmental pollutant exposure has been demonstrated to be associated with the onset and progression of asthma. Hypochlorous acid (HOCl), as an environmental exposure-relevant chlorine-based disinfectant, its role in asthmatic airway inflammation remains unclear. Through administering HOCl in drinking water during early life and the perinatal period, we discovered that early-life HOCl drinking water exposure not only aggravated airway inflammation in asthmatic mice but also that perinatal HOCl drinking water exposure could promote airway inflammation in the offspring of asthmatic mice. By gut microbiota sequencing, it was found that HOCl drinking water exposure could reduce the gut microbiota diversity in asthmatic mice, with the abundances of Lactobacillus, Faecalibaculum, Muribaculum, and [Eubacterium]_ventriosum_group being decreased, while increasing the abundances of Dubosiella and Parabacteroides. Further fecal metabolomics analysis revealed that HOCl drinking water exposure significantly enhanced the arachidonic acid metabolism pathway. And there was a certain correlation between the abundances of the significantly altered bacterial genera and the levels of arachidonic acid metabolites. Finally, treatment with taurine, a HOCl neutralizer, showed that taurine could significantly alleviate the asthma airway inflammation aggravated by HOCl exposure. In summary, these results provide evidence for the exacerbation of asthma airway inflammation by HOCl exposure and confirm that taurine supplementation can serve as a potential therapeutic approach.

Intestinal microbiota and respiratory system diseases: Relationships with three common respiratory virus infections

In recent years, the role of the intestinal microbiota in regulating host health and immune balance has attracted widespread attention. This study provides an in-depth analysis of the close relationship between the intestinal microbiota and respiratory system diseases, with a focus on three common respiratory virus infections, including respiratory syncytial virus (RSV), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and influenza virus. The research indicates that during RSV infection, there is a significant decrease in intestinal microbial diversity, suggesting the impact of the virus on the intestinal ecosystem. In SARS-CoV-2 infection, there are evident alterations in the intestinal microbiota, which are positively correlated with the severity of the disease. Similarly, influenza virus infection is associated with dysbiosis of the intestinal microbiota, and studies have shown that the application of specific probiotics exhibits beneficial effects against influenza virus infection. Further research indicates that the intestinal microbiota exerts a wide and profound impact on the occurrence and development of respiratory system diseases through various mechanisms, including modulation of the immune system and production of short-chain fatty acids (SCFAs). This article comprehensively analyzes these research advances, providing new perspectives and potential strategies for the prevention and treatment of future respiratory system diseases. This study not only deepens our understanding of the relationship between the intestinal microbiota and respiratory system diseases but also offers valuable insights for further exploring the role of host-microbiota interactions in the development of diseases.

Respiratory Microbiota and Health Risks in Children with Cerebral Palsy: A Narrative Review

Children diagnosed with cerebral palsy (CP) frequently face a range of intricate health challenges that go beyond their main condition. Respiratory problems represent one of the most crucial factors contributing to morbidity and mortality. This review employed a systematic approach to identify and collate recent findings on the respiratory microbiota in children with CP. The review emphasizes notable microbial alterations in the respiratory systems of children with CP, marked by a decrease in beneficial bacteria (such as Corynebacterium spp. and Dolosigranulum spp.) and an increase in opportunistic pathogens like Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumonia. These changes probably increase the vulnerability of children with CP to frequent respiratory infections, ongoing inflammation, and infections that are resistant to antibiotics. Key factors influencing the composition of microbiota include living in urban areas, socioeconomic factors, seasonal variations, vaccination status, dietary habits, breastfeeding, etc. Although new research has shed significant light on this topic, there are still considerable gaps in our understanding of how these microbial communities develop and interact with the immune responses of the host. Future research should focus on longitudinal studies to track microbiota changes over time and identify interventions that optimize respiratory health in CP.

Role of the Gut-Lung Microbiome Axis in Airway Inflammation in OVA-Challenged Mice and the Effect of Azithromycin

Objective

This study aimed to investigate the role of the gut-lung microbiome axis in airway inflammation in asthma and to evaluate the effect of azithromycin on this axis, with a focus on the potential mechanism by which azithromycin reduces allergic airway inflammation.

Methods

Haematoxylin and eosin (H&E) and periodic acid-Schiff (PAS) staining were used to assess pathological changes in the lung tissues of asthmatic mice. Leukocyte cell types in bronchoalveolar lavage fluid (BALF) samples were quantified following Wright-Giemsa staining. Total IgE, OVA-specific IgE, IL-4, IL-6, and IL-17A levels in BALF and total IgE in serum were measured by ELISA. The respiratory and gut microbiota were analysed using 16S rRNA gene sequencing and subsequent taxonomic analysis.

Results

OVA-challenged asthmatic mice with gut microbiota dysbiosis exhibited alterations in the respiratory microbiota, resulting in further aggravation of airway inflammation. Following faecal microbiota transplantation (FMT) to restore gut microbiota, respiratory microbiota dysbiosis was partially improved, and airway inflammation was significantly alleviated. Furthermore, azithromycin reduced airway inflammation in asthmatic mice, particularly non-eosinophilic inflammation, for which low-dose azithromycin combined with budesonide proved more effective. Azithromycin significantly enhanced the diversity and microbial composition of the gut microbiota and also affected the respiratory microbiota. At the phylum level, azithromycin decreased the abundance of Proteobacteria in the gut microbiota. At the genus level, azithromycin reduced the abundance of Pseudomonas in the respiratory microbiota.

Conclusion

The gut-lung microbiome axis plays a crucial role in airway inflammation in asthma. Azithromycin may reduce airway inflammation in asthma through modulation of the gut-lung microbiome axis.

Therapeutic role of gut microbiota in lung injury-related cognitive impairment

Lung injury can lead to specific neurocognitive dysfunction, and the "triple-hit" phenomenon may be the key theoretical mechanism for the progressive impairment of lung injury-related cognitive impairment. The lung and brain can communicate biologically through immune regulation pathway, hypoxic pathway, neural circuit, mitochondrial dysfunction, and microbial influence, which is called the "lung-brain axis." The gut microbiota is a highly complex community of microorganisms that reside in the gut and communicate with the lung via the "gut-lung axis." The dysregulation of gut microbiota may lead to the migration of pathogenic bacteria to the lung, and directly or indirectly regulate the lung immune response through their metabolites, which may cause or aggravate lung injury. The gut microbiota and the brain interact through the "gut-brain axis." The gut microbiota can influence and regulate cognitive function and behavior of the brain through neural pathway mechanisms, immune regulation pathway and hypothalamic-pituitary-adrenal (HPA) axis regulation. Based on the gut microbiota regulation mechanism of the "gut-lung axis" and "gut-brain axis," combined with the mechanisms of cognitive impairment caused by lung injury, we proposed the "triple-hit" hypothesis. It states that the pathophysiological changes of lung injury trigger a series of events such as immune disorder, inflammatory responses, and microbiota changes, which activate the "lung-gut axis," thus forming a "triple-hit" that leads to the development or deterioration of cognitive impairment. This hypothesis provides a more comprehensive framework for studying and understanding brain dysfunction in the context of lung injury. This review proposes the existence of an interactive tandem network for information exchange among the gut, lung, and brain, referred to as the "gut-lung-brain axis." It further explores the potential mechanism of lung injury-related cognitive impairment caused by multiple interactions of gut microbiota in the "gut-lung-brain axis." We found that there are many numerous pathophysiological factors that influence the interaction within the "gut-lung-brain axis." The impact of gut microbiota on cognitive functions related to lung injury may be mediated through mechanisms such as the "triple-hit" hypothesis, direct translocation of microbes and their metabolites, hypoxic pathway, immune modulation, vagal nerve activity, and the HPA axis regulation, among others. As the research deepens, based on the "triple-hit" hypothesis of lung injury, it is further discovered that gut microbial therapy can significantly change the pathogenesis of the inflammatory process on the "gut-lung-brain axis." It can also relieve lung injury and therapeutically modulate brain function and behavior. This perspective provides a new idea for the follow-up treatment of lung injury-related cognitive impairment caused by dysregulation of gut microbiota.

Lung Microbiota: From Healthy Lungs to Development of Chronic Obstructive Pulmonary Disease

Lung health is dependent on a complex picture of the lung microbiota composed of bacteriobiota, mycobiota, and virome. The studies have demonstrated that the lung microbiota has a crucial role in host protection by regulating innate and adaptive lung immunity. Chronic obstructive pulmonary disease (COPD) is an inflammatory lung disease featuring changed microbiota composition and diversity, known as a dysbiosis. The lung dysbiosis increases with the progress of COPD and during exacerbation. Two models of dysbiosis have been proposed: dysbiosis and inflammation cycles and the disturbance of bacterial interactome. Still, it is unknown if the driving factor of the pathogenesis of COPD belongs to the host or microbiota. Recently, host-microbiota and microbe-microbe interactions have been highlighted in COPD, but the mechanisms behind these interactions need further exploration. The function of the gut-lung axis is crucial for the maintenance of lung health and is affected in COPD. The application of probiotics has resulted in host-beneficial effects, and it is likely that future progress in this field will aid in the therapy of COPD. In this review, the composition of the lung microbiota, molecular mechanisms, and clinical aspects relating to host and microbiota in health and COPD are comprehensively provided.

The neonate respiratory microbiome

Over the past two decades, it has become clear that against earlier assumptions, the respiratory tract is regularly populated by a variety of microbiota even down to the lowest parts of the lungs. New methods and technologies revealed distinct microbiome compositions and developmental trajectories in the differing parts of the respiratory tract of neonates and infants. In this review, we describe the current understanding of respiratory microbiota development in human neonates and highlight multiple factors that have been identified to impact human respiratory microbiome development including gestational age, mode of delivery, diet, antibiotic treatment, and early infections. Moreover, we discuss to date revealed respiratory microbiome-disease associations in infants and children that may indicate a potentially imprinting cross talk between microbial communities and the host immune system in the respiratory tract. It becomes obvious how insufficient our knowledge still is regarding the exact mechanisms underlying such cross talk in humans. Lastly, we highlight strong findings that emphasize the important role of the gut-lung axis in educating and driving pulmonary immunity. Further research is needed to better understand the host - respiratory microbiome interaction in order to enable the translation into microbiome-based strategies to protect and improve human respiratory health from early childhood.

Assessment of upper respiratory and gut bacterial microbiomes during COVID-19 infection in adults: potential aerodigestive transmission

SARS-CoV-2 is the viral pathogen responsible for COVID-19. Although morbidity and mortality frequently occur as a result of lung disease, the gastrointestinal (GI) tract is recognized as a primary location for SARS-CoV-2. Connections and interactions between the microbiome of the gut and respiratory system have been linked with viral infections via what has been referred to as the 'gut-lung axis' with potential aerodigestive communication in health and disease. This research explored the relationship between the microbiomes of the upper respiratory and GI tracts in patients with COVID-19 and examined Extraesophageal reflux (EOR), a mechanism which could contribute to dysregulated communication between the GI and respiratory tract (as identified in COVID-19). 97 patients with a laboratory diagnosis of COVID-19 infection, and 50 age-matched controls were recruited and stool, saliva and sputum were obtained from each participant. ELISA Pepsin tests and Reflux Symptom Index scores (RSI) were conducted for EOR assessment. DNA sequencing of the V4 region of the 16 S rRNA gene was performed for microbiome analysis. No differences were observed between the fecal microbiome's alpha and Shannon diversity indices; however, a distinct microbial composition was observed in COVID-19 patients (when compared to the controls). The respiratory microbiota from individuals with COVID-19 demonstrated a statistically significant reduction in Shannon diversity and bacterial richness alongside an overall reduction in the prevalence of organisms from a typical healthy respiratory microbiome. Furthermore, the bacterial richness of the stool and sputum samples was significantly lower among COVID-19 patients admitted to ICU. A significantly higher RSI score and salivary pepsin level were detected among those with COVID-19. The data indicates that COVID-19 is associated with a dysregulation of both the gut and lung microbiome with a more marked perturbation in the lung, particularly among COVID-19 patients who had been admitted to the ICU. The presence of increased RSI scores, combined with elevated levels of Pepsin, suggests that increased micro-aspiration may occur, which is consistent with of under-recognized interactions between the GI and lung microbiomes in COVID-19 patients and requires additional study. Such studies would benefit from the insights provided by biological samples which reflect the continuum of the aerodigestive tract.

Maternal aspartame exposure alters lung Th1/Th2 cytokine balance in offspring through nuclear factor-κB activation

BACKGROUND

Epidemiological evidence suggests that maternal intake of nonnutritive sweeteners is positively associated with early childhood asthma incidence. We investigated the effects of maternal aspartame exposure during pregnancy and lactation on lung Th1/Th2 cytokine balance and intestinal microbiota in offspring and explored the mechanisms that mediate these effects.

METHOD

Pregnant BALB/c mice were randomly divided on gestational day 7 into two dietary intervention groups: control (drinking water only) and aspartame (drinking water +0.25 g/L aspartame) groups. The dams nursed their offspring for 3 weeks. On postnatal day 21, heart blood samples were collected, and immunoglobulin E levels were measured. Microorganisms from the lower gastrointestinal tract were sampled using a culture-independent approach. Lung tissues were harvested for biochemical analyses.

RESULTS

Maternal aspartame exposure increased the body weight of the dams from gestational day 7 to postnatal day 21 and the body weight of the offspring from birth to postnatal day 21. Maternal aspartame exposure significantly increased the levels of Th2 cytokines (interleukin [IL]-4, IL-5, and IL-13) and IL-17 and immunoglobulin E but reduced that of a Th1 cytokine (interferon-γ) in the offspring's lung tissues. The altered Th1/Th2 balance was accompanied by increased lung nuclear factor-κB activation. The bacterial composition and alpha-diversity of the gut microbiota of the offspring did not differ significantly between the control and aspartame groups.

CONCLUSION

Our findings suggest maternal aspartame exposure influences lung Th1/Th2 cytokine balance in offspring through nuclear factor-κB activation.

Composite dietary antioxidant index, chronic respiratory disease, and all-cause mortality: National Health and Nutrition Examination Survey, 2003-2018

PURPOSE

Diet rich in antioxidant may protect against chronic respiratory disease (CRD), but few studies have evaluated the association between composite dietary antioxidant index (CDAI) and CRD. The study aimed to examine the association of CDAI with the risk of CRD and all-cause mortality in CRD patients from the US.

METHODS

Data were obtained from the National Health and Nutrition Examination Survey, 2003-2018. Logistic and Cox regression analyses were used to estimate association of CDAI with CRD and all-cause mortality. Dose-response relationship was examined by restricted cubic spline analyses.

RESULTS

Total 44,094 participants were eligible for CRD (aged 1-85 years; mean age: 45.71 years old), and 7,685 CRD patients for all-cause mortality (median follow-up: 7.58 years; 1,136 deaths before 12/31/2019). The risk for CRD, asthma, and chronic obstructive pulmonary disease was significantly decreased by 13-32% with the increase intake of CDAI, even after adjusting for confounders (all P < 0.001). The relationship between CDAI and three respiratory endpoints was U-shaped (all P for nonlinearity < 0.001). There was an obvious declining trend in the magnitude of mortality risk with the increase of intake of CDAI, especially in patients with asthma. Fully adjusted hazard ratio was 0.72 (95% confidence interval: 0.54-0.95), 0.55 (0.42-0.72), and 0.48 (0.34-0.66) for the second, third, and fourth quartile of CDAI in patients with asthma relative to the first quartile, respectively. The association with CRD risk was significantly modified by smoking status (P-interaction: 0.006).

CONCLUSION

Our findings indicate that high CDAI is a significant protective factor against CRD and all-cause mortality in the US population.

Large-scale metagenomic assembly provide new insights into the genetic evolution of gut microbiomes in plateau ungulates

Trillions of microbes colonize the ungulate gastrointestinal tract, playing a pivotal role in enhancing host nutrient utilization by breaking down cellulose and hemicellulose present in plants. Here, through large-scale metagenomic assembly, we established a catalog of 131,416 metagenome-assembled genomes (MAGs) and 11,175 high-quality species-level genome bins (SGBs) from 17 species of ungulates in China. Our study revealed the convergent evolution of high relative abundances of carbohydrate-active enzymes (CAZymes) in the gut microbiomes of plateau-dwelling ungulates. Notably, two significant factors contribute to this phenotype: structural variations in their gut microbiome genomes, which contain more CAZymes, and the presence of novel gut microbiota species, particularly those in the genus Cryptobacteroides, which are undergoing independent rapid evolution and speciation and have higher gene densities of CAZymes. Furthermore, these enrichment CAZymes in the gut microbiomes are highly enrichment in known metabolic pathways for short-chain fatty acid (SCFA) production. Our findings not only provide a valuable genomic resource for understanding the gut microbiomes of ungulates but also offer fresh insights into the interaction between gut microbiomes and their hosts, as well as the co-adaptation of hosts and their gut microbiomes to their environments.

Effect of mixed probiotics on pulmonary flora in patients with mechanical ventilation: an exploratory randomized intervention study

OBJECTIVE

The study objective was to investigate the effect of mixed probiotics on the diversity of the pulmonary flora in critically ill patients requiring mechanical ventilation by analysing the changes in lung microbes.

METHODS

24 adult critically ill patients who needed mechanical ventilation in our hospital were randomly divided into a probiotic group and a control group. Then, the probiotic group was given Live Combined Bifidobacterium, Lactobacillus and Enterococcus Capsules, Oral (Bifico) by nasal feeding within 24 h after mechanical ventilation. Bronchoalveolar lavage fluid (BALF) and venous blood were collected within 24 h after mechanical ventilation and on the 5th day after mechanical ventilation, and the treatment status of patients (mechanical ventilation time, 28-day survival), measured cytokine levels (IL-1 β, IL-6, IL-8, IL-17A) and changes in pulmonary microorganisms were observed.

RESULTS

The microbial diversity of BALF samples decreased in the control group, and there was no significant difference in the probiotic group. Species difference analysis showed that among the three probiotics (Bifidobacterium, Lactobacillus, Enterococcus) used for intervention, Lactobacillus caused significant differences in BALF in the control group. Clinical factor association analysis displayed significant associations with IL-17A levels in both blood and BALF.

CONCLUSION

Mechanical ventilation can cause a decline in pulmonary microbial diversity, which can be improved by administering mixed probiotics.

The emerging roles of microbiome and short-chain fatty acids in the pathogenesis of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic lung disease that affects premature infants and leads to long-term pulmonary complications. The pathogenesis of BPD has not been fully elucidated yet. In recent years, the microbiome and its metabolites, especially short-chain fatty acids (SCFAs), in the gut and lungs have been demonstrated to be involved in the development and progression of the disease. This review aims to summarize the current knowledge on the potential involvement of the microbiome and SCFAs, especially the latter, in the development and progression of BPD. First, we introduce the gut-lung axis, the production and functions of SCFAs, and the role of SCFAs in lung health and diseases. We then discuss the evidence supporting the involvement of the microbiome and SCFAs in BPD. Finally, we elaborate on the potential mechanisms of the microbiome and SCFAs in BPD, including immune modulation, epigenetic regulation, enhancement of barrier function, and modulation of surfactant production and the gut microbiome. This review could advance our understanding of the microbiome and SCFAs in the pathogenesis of BPD, which also helps identify new therapeutic targets and facilitate new drug development.

Causal Relationship Between Gut Microbiota and Chronic Obstructive Pulmonary Disease: A Bidirectional Two-Sample Mendelian Randomization Study

Background

The associations between gut microbiota and chronic obstructive pulmonary disease (COPD) have gained increasing attention and research interest among scholars. However, it remains unclear whether gut microbiota serves as a causal factor for COPD or if it is a consequence of the disease. Therefore, we investigated the causal relationship between COPD and gut microbiota, with intention of providing novel insights and references for clinical diagnosis and treatment.

Methods

Based on the genome-wide association study (GWAS) data, we employed MR-Egger regression, random-effects inverse variance-weighted (IVW) method, and weighted median method for bidirectional Mendelian randomization (MR) analysis. We conducted Cochran's Q test for heterogeneity assessment and performed multivariable analysis, sensitivity analysis, and heterogeneity testing to validate the reliability and stability of results.

Results

Utilizing MR analysis, mainly employing the IVW method, we detected a collective of 11 gut microbiota species that exhibited associations with COPD. Among them, Bacteroidia, family XIII, Clostridium innocuum group, Barnesiella, Collinsella, Lachnospiraceae NK4A136 group, Lachnospiraceae UCG004, Lachnospiraceae UCG010, and Bacteroidales were found to be protective factors for COPD. On the other hand, Holdemanella and Marvinbryantia were identified as risk factors for COPD. Individuals with elevated levels of Holdemanella exhibited a 1.141-fold higher risk of developing COPD compared to their healthy counterparts, and those with increased levels of Marvinbryantia had a 1.154-fold higher risk. Reverse MR analysis yielded no evidence indicating a causal relationship between gut microbiota and COPD occurrence.

Conclusion

Our study established a causal link between 11 specific gut microbiota species and COPD, offering novel insights and valuable references for targeted therapies in the clinical management of COPD. However, our results were mainly based on the analysis of database, and further clinical studies are needed to clarify the effects of gut microbiota on COPD and its specific protective mechanism.

Effect and mechanism of quercetin or quercetin-containing formulas against COVID-19: From bench to bedside

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the global coronavirus disease 2019 (COVID-19) pandemic since 2019. Immunopathogenesis and thromboembolic events are central to its pathogenesis. Quercetin exhibits several beneficial activities against COVID-19, including antiviral, anti-inflammatory, immunomodulatory, antioxidative, and antithrombotic effects. Although several reviews have been published, these reviews are incomplete from the viewpoint of translational medicine. The authors comprehensively evaluated the evidence of quercetin against COVID-19, both basically and clinically, to apply quercetin and/or its derivatives in the future. The authors searched the PubMed, Embase, and the Cochrane Library databases without any restrictions. The search terms included COVID-19, SARS-CoV-2, quercetin, antiviral, anti-inflammatory, immunomodulatory, thrombosis, embolism, oxidative, and microbiota. The references of relevant articles were also reviewed. All authors independently screened and reviewed the quality of each included manuscript. The Cochrane Risk of Bias Tool, version 2 (RoB 2) was used to assess the quality of the included randomized controlled trials (RCTs). All selected studies were discussed monthly. The effectiveness of quercetin against COVID-19 is not solid due to methodological flaws in the clinical trials. High-quality studies are also required for quercetin-containing traditional Chinese medicines. The low bioavailability and highly variable pharmacokinetics of quercetin hinder its clinical applications. Its positive impact on immunomodulation through reverting dysbiosis of gut microbiota still lacks robust evidence. Quercetin against COVID-19 does not have tough clinical evidence. Strategies to improve its bioavailability and/or to develop its effective derivatives are needed. Well-designed RCTs are also crucial to confirm their effectiveness in the future.

Xiaoqinglong decoction mitigates nasal inflammation and modulates gut microbiota in allergic rhinitis mice

Introduction

Allergic rhinitis (AR) is a respiratory immune system disorder characterized by dysregulation of immune responses. Within the context of AR, gut microbiota and its metabolites have been identified as contributors to immune modulation. These microorganisms intricately connect the respiratory and gut immune systems, forming what is commonly referred to as the gut-lung axis. Xiaoqinglong Decoction (XQLD), a traditional Chinese herbal remedy, is widely utilized in traditional Chinese medicine for the clinical treatment of AR. In this study, it is hypothesized that the restoration of symbiotic microbiota balance within the gut-lung axis plays a pivotal role in supporting the superior long-term efficacy of XQLD in AR therapy. Therefore, the primary objective of this research is to investigate the impact of XQLD on the composition and functionality of the gut microbiota in a murine model of AR.

Methods

An ovalbumin-sensitized mouse model to simulate AR was utilized, the improvement of AR symptoms after medication was investigated, and high-throughput sequencing was employed to analyze the gut microbiota composition.

Results

XQLD exhibited substantial therapeutic effects in AR mice, notably characterized by a significant reduction in allergic inflammatory responses, considerable alleviation of nasal symptoms, and the restoration of normal nasal function. Additionally, following XQLD treatment, the disrupted gut microbiota in AR mice displayed a tendency toward restoration, showing significant differences compared to the Western medicine (loratadine) group.

Discussion

This results revealed that XQLD may enhance AR allergic inflammatory responses through the regulation of intestinal microbiota dysbiosis in mice, thus influencing the dynamics of the gut-lung axis. The proposal of this mechanism provides a foundation for future research in this area.

Exploring the immune-inflammatory mechanism of Maxing Shigan Decoction in treating influenza virus A-induced pneumonia based on an integrated strategy of single-cell transcriptomics and systems biology

BACKGROUND

Influenza is an acute respiratory infection caused by influenza virus. Maxing Shigan Decoction (MXSGD) is a commonly used traditional Chinese medicine prescription for the prevention and treatment of influenza. However, its mechanism remains unclear.

METHOD

The mice model of influenza A virus pneumonia was established by nasal inoculation. After 3 days of intervention, the lung index was calculated, and the pathological changes of lung tissue were detected by HE staining. Firstly, transcriptomics technology was used to analyze the differential genes and important pathways in mouse lung tissue regulated by MXSGD. Then, real-time fluorescent quantitative PCR (RT-PCR) was used to verify the changes in mRNA expression in lung tissues. Finally, intestinal microbiome and intestinal metabolomics were performed to explore the effect of MXSGD on gut microbiota.

RESULTS

The lung inflammatory cell infiltration in the MXSGD group was significantly reduced (p < 0.05). The results of bioinformatics analysis for transcriptomics results show that these genes are mainly involved in inflammatory factors and inflammation-related signal pathways mediated inflammation biological modules, etc. Intestinal microbiome showed that the intestinal flora Actinobacteriota level and Desulfobacterota level increased in MXSGD group, while Planctomycetota in MXSGD group decreased. Metabolites were mainly involved in primary bile acid biosynthesis, thiamine metabolism, etc. This suggests that MXSGD has a microbial-gut-lung axis regulation effect on mice with influenza A virus pneumonia.

CONCLUSION

MXSGD may play an anti-inflammatory and immunoregulatory role by regulating intestinal microbiome and intestinal metabolic small molecules, and ultimately play a role in the treatment of influenza A virus pneumonia.

Causal effects between gut microbiota and pulmonary arterial hypertension: A bidirectional Mendelian randomization study

BACKGROUND

Multiple studies have highlighted a potential link between gut microbes and the onset of Pulmonary Arterial Hypertension (PAH). Nonetheless, the precise cause-and-effect relationship remains uncertain.

OBJECTIVES

In this investigation, we utilized a two-sample Mendelian randomization (TSMR) approach to probe the presence of a causal connection between gut microbiota and PAH.

METHODS

Genome-wide association (GWAS) data for gut microbiota and PAH were sourced from MiBioGen and FinnGen research, respectively. Inverse variance weighting (IVW) was used as the primary method to explore the causal effect between gut flora and PAH, supplemented by MR-Egger, weighted median (WM). Sensitivity analyses examined the robustness of the MR results. Reverse MR analysis was used to rule out the effect of reverse causality on the results.

RESULTS

The results indicate that Genus Ruminococcaceae UCG004 (OR = 0.407, P = 0.031) and Family Alcaligenaceae (OR = 0.244, P = 0.014) were protective factors for PAH. Meanwhile Genus Lactobacillus (OR = 2.446, P = 0.013), Class Melainabacteria (OR = 2.061, P = 0.034), Phylum Actinobacteria (OR = 3.406, P = 0.010), Genus Victivallis (OR = 1.980, P = 0.010), Genus Dorea (OR = 3.834, P = 0.024) and Genus Slackia (OR = 2.622, P = 0.039) were associated with an increased Prevalence of PAH. Heterogeneity and pleiotropy were not detected by sensitivity analyses, while there was no reverse causality for these nine specific gut microorganisms.

CONCLUSIONS

This study explores the causal effects of eight gut microbial taxa on PAH and provides new ideas for early prevention of PAH.

What Makes the Gut-Lung Axis Working? From the Perspective of Microbiota and Traditional Chinese Medicine

Background

An increasing number of studies have proved that gut microbiota is involved in the occurrence and development of various lung diseases and can interact with the diseased lung. The concept of the gut-lung axis (GLA) provides a new idea for the subsequent clinical treatment of lung diseases through human microbiota. This review aims to summarize the microbiota in the lung and gut and the interaction between them from the perspectives of traditional Chinese medicine and modern medicine.

Method

We conducted a literature search by using the search terms "GLA," "gut microbiota," "spleen," and "Chinese medicine" in the databases PubMed, Web of Science, and CNKI. We then explored the mechanism of action of the gut-lung axis from traditional Chinese medicine and modern medicine.

Results

The lung and gut microbiota enable the GLA to function through immune regulation, while metabolites of the gut microbiota also play an important role. The spleen can improve the gut microbiota to achieve the regulation of the GLA.

Conclusion

Improving the gut microbiota through qi supplementation and spleen fortification provides a new approach to the clinical treatment of lung diseases by regulating the GLA. Currently, our understanding of the GLA is limited, and more research is needed to explain its working principle.

Modulation of chronic obstructive pulmonary disease progression by antioxidant metabolites from Pediococcus pentosaceus: enhancing gut probiotics abundance and the tryptophan-melatonin pathway

Chronic obstructive pulmonary disease (COPD), a condition primarily linked to oxidative stress, poses significant health burdens worldwide. Recent evidence has shed light on the association between the dysbiosis of gut microbiota and COPD, and their metabolites have emerged as potential modulators of disease progression through the intricate gut-lung axis. Here, we demonstrate the efficacy of oral administration of the probiotic Pediococcus pentosaceus SMM914 (SMM914) in delaying the progression of COPD by attenuating pulmonary oxidative stress. Specially, SMM914 induces a notable shift in the gut microbiota toward a community structure characterized by an augmented abundance of probiotics producing short-chain fatty acids and antioxidant metabolisms. Concurrently, SMM914 synthesizes L-tryptophanamide, 5-hydroxy-L-tryptophan, and 3-sulfino-L-alanine, thereby enhancing the tryptophan-melatonin pathway and elevating 6-hydroxymelatonin and hypotaurine in the lung environment. This modulation amplifies the secretion of endogenous anti-inflammatory factors, diminishes macrophage polarization toward the M1 phenotype, and ultimately mitigates the oxidative stress in mice with COPD. The demonstrated efficacy of the probiotic intervention, specifically with SMM914, not only highlights the modulation of intestine microbiota but also emphasizes the consequential impact on the intricate interplay between the gastrointestinal system and respiratory health.

Host Transcriptional Regulatory Genes and Microbiome Networks Crosstalk through Immune Receptors Establishing Normal and Tumor Multiomics Metafirm of the Oral-Gut-Lung Axis

The microbiome has shown a correlation with the diet and lifestyle of each population in health and disease, the ability to communicate at the cellular level with the host through innate and adaptative immune receptors, and therefore an important role in modulating inflammatory process related to the establishment and progression of cancer. The oral cavity is one of the most important interaction windows between the human body and the environment, allowing the entry of an important number of microorganisms and their passage across the gastrointestinal tract and lungs. In this review, the contribution of the microbiome network to the establishment of systemic diseases like cancer is analyzed through their synergistic interactions and bidirectional crosstalk in the oral-gut-lung axis as well as its communication with the host cells. Moreover, the impact of the characteristic microbiota of each population in the formation of the multiomics molecular metafirm of the oral-gut-lung axis is also analyzed through state-of-the-art sequencing techniques, which allow a global study of the molecular processes involved of the flow of the microbiota environmental signals through cancer-related cells and its relationship with the establishment of the transcription factor network responsible for the control of regulatory processes involved with tumorigenesis.

Effects of Maternal Stress on Breast Milk Production and the Microbiota of Very Premature Infants

Perinatal stress experienced by mothers of very premature newborns may influence the mother's milk and the infant's intestinal microbiota. This prospective study of mothers of very preterm infants fed with mother's own milk (MOM) was carried out in a tertiary hospital over a 2-year period. The assessment of maternal stress in 45 mothers of 52 very preterm newborns using the parental stress scale (PSS:NICU) revealed an inverse relationship between stress and MOM production in the first days of life (p = 0.012). The greatest contributor to stress was the one related to the establishment of a mother-child bond. Maternal stress was lower in mothers in whom the kangaroo method was established early (p = 0.011) and in those with a higher educational level (p = 0.032). Levels of fecal calprotectin (FC) decreased with the passage of days and were directly correlated with birthweight (p = 0.044). FC levels 7 days post-delivery were lower in newborns that received postnatal antibiotics (p = 0.027). High levels of maternal stress resulted in progressive decreases and increases in the proportions of Firmicutes and Proteobacteria species, respectively, over 15 days post-delivery, both in MOM and in fecal samples from premature newborns. These findings underscore the importance of recognizing and appropriately managing maternal stress in neonatal units, given its marked influence on both the microbiota of maternal milk and the intestinal microbiota of premature newborns.

The correlation of the intestinal with pharyngeal microbiota in early neonates

Introduction

The gut-lung axis has long been recognized as an important mechanism affecting intestinal and lung immunity. Still, few studies have examined the correlation between the intestinal and pharyngeal microbiota in early neonates, especially when feeding patterns are one of the main drivers of microbiota development.

Methods

To explore the composition and function of intestinal and pharyngeal microbiota and to analyze the effect of limited formula feeding on the initial microbiota colonization in early full-term neonates, we characterized the stool and oropharyngeal microbiota of 20 healthy full-term newborns sampled on days 0 and 5-7 after birth using 16S rRNA gene sequencing. Based on the sequencing results, a comparison was made of the compositions and functions of the intestinal and oropharyngeal microbiota for analysis.

Results and discussion

At the phylum level, Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes were the most abundant in both niches. At the genus level, the species of pioneer bacteria were rich in the intestine and oropharynx but low in abundance on day 0. On days 5-7, Bifidobacterium (25.40%) and Escherichia-Shigella (22.16%) were dominant in the intestine, while Streptococcus (38.40%) and Staphylococcus (23.13%) were dominant in the oropharynx. There were eight core bacteria genera in the intestine and oropharynx on days 5-7, which were Bifidobacterium, Escherichia-Shigella, Staphylococcus, Streptococcus, Bacteroides, Parabacteroides, Rothia, and Acinetobacter. As indicated by PICRUSt analysis, on days 5-7, the intestinal microbiota was more predictive than the oropharyngeal microbiota in transcription, metabolism, cell motility, cellular processes and signaling, and organismal system function in the KEGG pathway. Compared to exclusive breastfeeding, limited formula feeding (40-60%) had no significant effect on the neonatal intestinal and oropharyngeal microbiota composition during the initial colonization period. Our results suggest that the initial colonization of microbiota is closely related to the ecological niche environment in the intestine and oropharynx, with their core microbiota being closely correlated. We found that early limited formula feeding could not significantly affect the initial colonization of microbiota in the intestine and oropharynx.

Disruption of the lung-gut-brain axis is responsible for cortex damage induced by pulmonary exposure to zinc oxide nanoparticles

Increasing evidence shows that gut microbiota is important for host health in response to metal nanomaterials exposure. However, the effect of gut microbiota on the cortex damage caused by pulmonary exposure to zinc oxide nanoparticles (ZnONPs) remains mainly unknown. In this study, a total of 48 adult C57BL/6J mice were intratracheally instilled with 0.6 mg/kg ZnONPs in the presence or absence of antibiotics (ABX) treatment. Besides, 24 mice were treated with or without fecal microbiota transplantation (FMT) after the intraperitoneal administration of ABX. Our results demonstrated for the first time that dysbiosis induced by ABX treatment significantly aggravated cortex damage induced by pulmonary exposure to ZnONPs. Such damage might highly occur through the induction of oxidative stress, manifested by the enhancement of antioxidative enzymes and products of lipid peroxidation. However, ferroptosis was not involved in this process. Interestingly, our data revealed that ABX treatment exacerbated the alterations of gut-brain peptides (including Sst, Sstr2, and Htr4) induced by ZnONPs in both gut and cortex tissues. Moreover, fecal microbiota transplantation (FMT) was able to alleviate cerebral cortex damage, oxidative stress, and alterations of gut-brain peptides induced by pulmonary exposure to ZnONPs. The results together indicate that pulmonary exposure to ZnONPs causes cerebral cortex damage possibly via the disruption of the lung-gut-brain axis. These findings not only propose valuable insights into the mechanism of ZnONPs neurotoxicity but also provide a potential therapeutic method against brain disorders induced by pulmonary exposure to ZnONPs. AVAILABILITY OF DATA AND MATERIALS: The datasets used and/or analyzed during the current study are available from the The corresponding author on reasonable request.

Respiratory Microbiome Profile of Pediatric Pulmonary Hypertension Patients Associated With Congenital Heart Disease

BACKGROUND

Pulmonary hypertension (PH) associated with congenital heart disease (CHD) is the most common type of PH in pediatric patients. The airway microbiome profile in CHD-PH patients remains rarely studied.

METHODS

A total of 158 children were recruited for collection of oropharyngeal swabs to sequence the 16S ribosomal RNA (16S rRNA) V3-V4 region of respiratory microbiome, to establish a correlation between these bacterial groups and echocardiography indicators in CHD-PH patients.

RESULTS

Bacterial α- and β-diversity of the airway microbiome indicated a significantly lower richness in the CHD-PH group and compositional differences associated with the specific taxa and their relative abundances in the upper respiratory tract. Principal coordinate analysis showed that the pharynx microbiota composition in the CHD-PH group varied from that in the CHD or control group. The linear discriminant analysis effect size also highlighted an increased presence of Streptococcus and Rothia in pediatric CHD-PH patients. Comparison of microbial composition between pediatric and adult PH patients showed significant differences and separation of microbiota. The correlation between bacterial abundance and transthoracic echocardiography indexes in CHD-associated PH indicated that different groups of microbiomes may be related to different PH grades.

CONCLUSIONS

In summary, our study reported the systematic definition and divergent profile of the upper respiratory tract microbiota in pediatric PH patients, CHD and reference subjects, as well as between pediatric and adult PH patients.

Lactobacillus mucosae exerted different antiviral effects on respiratory syncytial virus infection in mice

Respiratory syncytial virus (RSV) infection is a constant threat to the health of young children, and this is mainly attributed to the lack of effective prevention strategies. This study aimed to determine whether Lactobacillus (L.) mucosae, a potential probiotic, could protect against respiratory viral infection in a mouse model. Naive 3–4-week-old BALB/c mice were orally administered with three L. mucosae strains (2.5 × 10⁸ CFU/mouse) 7 days before RSV infection (10⁵ TCID₅₀/mouse). Results showed that all three strains inhibited RSV replication and reduced the proportions of inflammatory cells, including granulocytes and monocytes in the blood. The L. mucosae M104R01L3 treatment maintained stable weight in mice and increased interferon (IFN)-β and tumor necrosis factor (TNF)-α levels. The L. mucosae DCC1HL5 treatment increased interleukin (IL)-1β and IL-10 levels. Moreover, the M104R01L3 and DCC1HL5 strains increased the proportions of Akkermansia, Alistipes, and Anaeroplasma which contributed to the advantageous modulation of the gut microbiota. Besides, L. mucosae affected the gut levels of short-chain fatty acids (SCFAs) that are important for the antiviral response. L. mucosae 1,025 increased acetate, propionate, and butyrate levels, whereas L. mucosae M104R01L3 increased the level of acetate in the gut. L. mucosae M104R01L3 may protect against viral infection by upregulating the IFN-β levels in the lungs and its antiviral effect may be related to the increase of acetate levels in the gut. In conclusion, the three L. mucosae strains exerted antiviral effects against RSV infection by differentially regulating immune responses and intestinal micro-ecological balance. This study can provide a reference for studying the mechanisms underlying the antiviral effects of L. mucosae.