The Role of the Microbiome in the Pathogenesis and Treatment of Asthma

Effects of azithromycin on alleviating airway inflammation in asthmatic mice by regulating airway microbiota and metabolites

Asthma is a chronic respiratory disease with increasing global prevalence, often linked to disrupted airway microbiota. Azithromycin has shown promise in asthma treatment, but whether its effect is owing to its antimicrobial capacity remains largely unknown. A house dust mite (HDM)-induced asthmatic mouse model was used to evaluate the effects of azithromycin on airway inflammation and microbiota. Mice were divided into control, HDM-induced asthma, HDM + azithromycin, and azithromycin-alone groups. Airway microbiota was analyzed using 16S rRNA sequencing, and metabolomic profiles were assessed via liquid chromatography-tandem mass spectrometry. Azithromycin alleviated type 2 airway inflammation in HDM-induced asthma, restoring microbiota diversity by modulating specific genera, including Streptococcus, Staphylococcus, Ruminococcus, Coprococcus, Bifidobacterium, etc. Combination analysis with metabolomics revealed that azithromycin significantly regulated airway microbiota-associated sphingomyelin metabolism. Azithromycin's therapeutic effects in asthma are associated with its ability to regulate airway microbiota and its associated sphingomyelin metabolism, highlighting the potential for microbiota-targeted therapies in asthma.IMPORTANCEAsthma, a prevalent chronic respiratory condition, poses a significant global health challenge due to its increasing prevalence and associated morbidity. The role of airway microbiota in asthma pathogenesis is gaining attention, with evidence suggesting that disruptions in this microbial community contribute to disease severity. Our study investigates the impact of azithromycin, a macrolide antibiotic, on airway inflammation and microbiota in a mouse model of asthma. The findings reveal that azithromycin not only alleviates airway inflammation but also restores microbiota diversity and modulates microbiota-associated sphingomyelin metabolism. This research underscores the potential of microbiota-targeted therapies in asthma management, offering a novel therapeutic strategy that could improve patient outcomes and reduce the healthcare burden associated with asthma.

Respiratory Flora Intervention: A New Strategy for the Prevention and Treatment of Occupationally Related Respiratory Allergy in Healthcare Workers

Occupational allergic respiratory disease in healthcare workers due to occupational exposure has received widespread attention. At the same time, evidence of altered respiratory flora associated with the development of allergy has been found in relevant epidemiologic studies. It is of concern that the composition of nasopharyngeal flora in healthcare workers differs significantly from that of non-healthcare workers due to occupational factors, with a particularly high prevalence of carriage of pathogenic and drug-resistant bacteria. Recent studies have found that interventions with upper respiratory tract probiotics can significantly reduce the incidence of respiratory allergies and infections. We searched PubMed and other databases to describe the burden of allergic respiratory disease and altered respiratory flora in healthcare workers in this narrative review, and we summarize the mechanisms and current state of clinical research on the use of flora interventions to ameliorate respiratory allergy, with the aim of providing a new direction for protecting the respiratory health of healthcare workers.

Sodium houttuyfonate modulates the lung Th1/Th2 balance and gut microbiota to protect against pathological changes in lung of ovalbumin-induced asthmatic mice

OBJECTIVE

The gut-lung axis involves microbial and product interactions between the lung and intestine. Antibiotics for chronic asthma can cause intestinal dysbiosis, disrupting this axis. Sodium houttuyfonate (SH) has diverse biological activities, including modifying gut microbiota, antibacterial, and anti-inflammatory. This study aims to explore the relationship between SH, CD4+ T cells, and gut microbiota.

METHODS

Allergic asthma was experimentally induced in mice through injection and inhalation of ovalbumin. After the administration of different amounts of SH, ELISA was utilized to ascertain the levels of inflammatory cytokines in the serum, flow cytometry was used to examine the levels of Th1/Th2 cytokines in CD4+ cells from lung tissues. The expression of T-bet and GATA3 in lung tissue was determined by Western blotting and quantitative real-time PCR assay. Gut microbiota was determined by 16S rRNA gene sequencing.

RESULTS

The results showed that SH can alleviate pulmonary injury in asthmatic mice, reducing serum levels of IL-4, IL-5, and IL-13 while simultaneously increasing IFN-γ. Furthermore, SH has been observed to modulate the balance of Th1/Th2 cells by up-regulating the mRNA and protein expression of T-bet but down-regulating GATA3 in the lung tissues of asthmatic mice, thereby promoting the differentiation of Th1 cells. Additionally, SH can regulate the variety and composition of gut microbiota especially genus Akkermansia in asthmatic mice.

CONCLUSION

SH can alleviate asthma through the regulation of Th1/Th2 cells and gut microbiota.

The Microbiota in Children and Adolescents with Asthma

The role of the respiratory microbiome has been deeply explored for at least two decades. Its characterization using modern methods is now well-defined, and the impacts of many microorganisms on health and diseases have been elucidated. Moreover, the acquired knowledge in related fields enables patient stratification based on their risk for disease onset, and the microbiome can play a role in defining possible phenotypes. The interplay between the lung and gut microbiomes is crucial in determining the microbial composition and immuno-inflammatory reaction. Asthma is still not a well-defined condition, where hyperreactivity and the immune system play important roles. In this disease, the microbiome is mostly represented by Proteobacteria, Streptococcus, and Veillonella, while Cytomegalovirus and Epstein-Barr viruses are the most prevalent viruses. A mycobiome may also be present. The passage from infancy to adolescence is examined by evaluating both the clinical picture and its relationship with possible variations of the microbiome and its effects on asthma. Otherwise, asthma is considered a heterogeneous disease that often starts in childhood and follows a particular personalized track, where adolescence plays a pivotal role in future prognosis. Under this point of view, the microbiota, with its possible variations due to many factors, both internal and external, can modify its composition; consequently, its inflammatory action and role in the immunological response has obvious consequences on the clinical conditions.

Safety and efficacy of fecal microbiota transplantation (FMT) as a modern adjuvant therapy in various diseases and disorders: a comprehensive literature review

The human gastrointestinal (GI) tract microbiome is a complex and all-encompassing ecological system of trillions of microorganisms. It plays a vital role in digestion, disease prevention, and overall health. When this delicate balance is disrupted, it can lead to various health issues. Fecal microbiota transplantation (FMT) is an emerging therapeutic intervention used as an adjuvant therapy for many diseases, particularly those with dysbiosis as their underlying cause. Its goal is to restore this balance by transferring fecal material from healthy donors to the recipients. FMT has an impressive reported cure rate between 80% and 90% and has become a favored treatment for many diseases. While FMT may have generally mild to moderate transient adverse effects, rare severe complications underscore the importance of rigorous donor screening and standardized administration. FMT has enormous potential as a practical therapeutic approach; however, additional research is required to further determine its potential for clinical utilization, as well as its safety and efficiency in different patient populations. This comprehensive literature review offers increased confidence in the safety and effectiveness of FMT for several diseases affecting the intestines and other systems, including diabetes, obesity, inflammatory and autoimmune illness, and other conditions.

Causal associations among gut microbiota, 1400 plasma metabolites, and asthma: a two-sample Mendelian randomization study

Background

Emerging evidence indicates a correlation between imbalances in intestinal microbiota and changes in plasma metabolites in the progression of asthma. However, the causal link between these factors remains unclear.

Methods

A two-sample Mendelian randomization (MR) study was employed to evaluate the potential causal connection between gut microbiota, plasma metabolites, and asthma susceptibility. Gut microbiota data from expansive genome-wide genotype studies and 16S fecal microbiome datasets were examined by the MiBioGen Alliance. Asthma data were procured from the FinnGen biobank analysis, while comprehensive Genome-Wide Association Studies (GWAS) summary statistics for plasma metabolites were derived from the NHGRI-EBI GWAS Catalog. Fluctuations in intestinal flora and plasma metabolites in asthma patients were evaluated using the weighted mode method. Additionally, pleiotropic and heterogeneity analyses were performed to ascertain the reliability of the findings.

Results

Upon examining the gut microbiota through MR with the IVW method, alongside tests for heterogeneity and pleiotropy, findings reveal a negative association between the abundance of the Christensenellaceae R.7 group and asthma risk. In contrast, the Bifidobacterium and Prevotella 7 genera exhibit a positive association with asthma risk, indicating they may be potential risk factors (p < 0.05). Furthermore, MR analysis of 1,400 metabolites employing Weighted median, IVW, and Weighted mode methods resulted in p-values below 0.05. Subsequent tests for pleiotropy and heterogeneity showed that the levels of 3,5-dichloro-2,6-dihydroxybenzoic acid have a negative correlation with asthma, whereas the phenylalanine to phosphate ratio has a positive correlation, suggesting their potential as risk factors for asthma (p < 0.05).

Conclusion

The current Mendelian randomization study provides evidence supporting a potential causal link between specific gut microbiota taxa, plasma metabolites, and asthma. These findings offer novel perspectives for future research and the development of treatment and prevention strategies for asthma.

Association between Serum Lipids and Asthma in Adults-A Systematic Review

(1) Background: Asthma is a syndrome found in both adults and children, characterized by airflow obstruction caused by the inflammation of the airways. In recent years, an increasing number of studies have found that lipid metabolism influences both the development and symptomatology of asthma. Lipid metabolism plays an important role both in the occurrence of exacerbations and in the reduction of lung inflammation. Our study aimed to identify any type of association between patients diagnosed with asthma and their serum lipids, including HDL-cholesterol, LDL-cholesterol, total cholesterol, and triglycerides in adults. (2) Methods: To find articles for our review, we searched two platforms: PubMed and Google Scholar. A total of 309 articles from two platforms were analyzed. Finally, 12 papers were selected from the initial pool of identified articles. (3) Results: The positive correlation between triglycerides, total cholesterol, low-density lipoprotein-cholesterol (LDL-cholesterol), and asthma has been demonstrated in several studies. Moreover, it appears that there is an association between biomarkers of type 2 inflammation and HDL and serum triglycerides in people with atopic status. Regarding the nutrition of asthmatic patients, the greatest impact on the development of the disease seems to be the consumption of fruit and vegetables. Several studies show that a predominantly vegan diet is associated with better control of the disease and a decrease in the number of pro-inflammatory cytokines. (4) Conclusions: Studies show a positive correlation between total cholesterol, triglyceride, and LDL-cholesterol levels and asthma and a negative correlation between HDL-cholesterol and asthma. Increased cholesterol values would lead to the stimulation of pro-inflammatory processes and the secretion of cytokines involved in these processes. The most successful diets for asthma patients seem to be those in which the consumption of fruit, vegetables, and high-fiber foods is increased because all of these food groups are rich in vitamins, antioxidants, and minerals.

Saccharomyces boulardii alleviates allergic asthma by restoring gut microbiota and metabolic homeostasis via up-regulation of METTL3 in an m6A-dependent manner

BACKGROUND

Allergic asthma is a heterogeneous disease and new strategies are needed to prevent or treat this disease. Studies have shown that probiotic interventions are effective in preventing asthma. Here, we investigated the impact of Saccharomyces boulardii (S. boulardii) on ovalbumin (OVA)-induced allergic asthma in mice, as well as the underlying mechanisms.

METHODS

First, we constructed a mouse asthma model using OVA and given S. boulardii intervention. Next, we measured N6-methyladenosine (m6A) levels in lung injury tissues. 16 s rRNA was employed to identify different gut microbiota in fecal samples. The analysis of differential metabolites in feces was performed by non-targeted metabolomics. Pearson correlation coefficient was utilized to analyze correlation between gut microbiota, metabolites and methyltransferase-like 3 (METTL3). Finally, we collected mouse feces treated by OVA and S. boulardii intervention for fecal microbiota transplantation (FMT) and interfered with METTL3.

RESULTS

S. boulardii improved inflammation and oxidative stress and alleviated lung damage in asthmatic mice. In addition, S. boulardii regulated m6A modification levels in asthmatic mice. 16 s rRNA sequencing showed that S. boulardii remodeled gut microbiota homeostasis in asthmatic mice. Non-targeted metabolomics analysis showed S. boulardii restored metabolic homeostasis in asthmatic mice. There was a correlation between gut microbiota, differential metabolites, and METTL3 analyzed by Pearson correlation. Additionally, through FMT and interference of METTL3, we found that gut microbiota mediated the up-regulation of METTL3 by S. boulardii improved inflammation and oxidative stress in asthmatic mice, and alleviated lung injury.

CONCLUSIONS

S. boulardii alleviated allergic asthma by restoring gut microbiota and metabolic homeostasis via up-regulation of METTL3 in an m6A-dependent manner.

Unraveling the Complexity of Asthma: Insights from Omics Approaches

Asthma is a heterogeneous respiratory disease that represents a substantial social and economic burden [...].

Can Therapeutic Targeting of the Human Microbiome Influence Asthma Management? A Pro/Con Debate

Asthma is a clinically heterogeneous disease, and despite substantial improvements in therapies, there remains an unmet need for well-tolerated, effective treatments. Observational studies have demonstrated that alterations in the respiratory and gut microbiome are associated with the development of asthma and its severity. These findings are supported by preclinical models demonstrating that respiratory and gut microbes can alter airway inflammation. Therapeutic approaches to target the human microbiome have been increasingly applied to a wide range of acute and chronic diseases, but there are currently no microbiome-based therapeutics approved for the treatment of asthma. This clinical commentary addresses the future role of microbiome-based therapeutics in asthma management from both a pro and con perspective. We examine (1) the prospects for clinical studies demonstrating a causal relationship between the human microbiome and the severity of asthma; (2) the challenges and potential solutions for designing, testing, and implementing a microbiome-based therapeutic; and (3) the possibility of microbiome-based therapeutics for conditions comorbid to asthma. We conclude by identifying research priorities that will help determine the future of microbiome-based therapeutics for the management of asthma.

Immunomodulatory action of synbiotic comprising of newly isolated lactic acid producing bacterial strains against allergic asthma in mice

Given the reported role of gut-microbiota in asthma pathogenesis, the present work was carried to evaluate immunomodulatory action of newly isolated lactic acid producing bacterial strains Bifidobacterium breve Bif11 and Lactiplantibacillus plantarum LAB31 against asthma using ovalbumin (OVA) based mouse model. Our results show that both strains modulate Th2 immune response potentially through production of short chain fatty acids (SCFAs), resulting in suppression of OVA-induced airway inflammation. Furthermore, synbiotic comprising of both strains and prebiotic, Isomaltooligosaccharide exhibited superior potential in amelioration of OVA-induced airway inflammation through improved modulation of Th2 immune response. Further, synbiotic protects against OVA-induced mucus hyper-production and airway-hyperresponsiveness. Such protection was associated with normalization of gut microbiome and enhanced production of SCFAs in cecum which correlates closely with population of T-regulatory cells in spleen. Overall, our novel synbiotic possesses the ability to fine-tune the immune response for providing protection against allergic asthma.