Cryptococcus neoformans is a major fungal pathogen responsible for life-threatening meningitis, especially in immunocompromised individuals. Although the gut–lung axis is known to regulate immune responses in respiratory infections, its role in cryptococcosis remains unclear. This study aimed to define the dynamic changes in the gut and lung microbiota and their relationship with host immunity during C. neoformans infection. Using a mouse model, we found that pulmonary infection induced significant dysbiosis in both the lung and gut microbiota, marked by decreased beneficial commensals and increased opportunistic pathogens. Integrated analysis showed these microbial shifts were closely associated with distinct immune responses: lung dysbiosis correlated with a strong IL-17-mediated pulmonary inflammatory response, while gut dysbiosis was linked to systemic immune activation in the spleen. Functional metagenomic prediction further revealed widespread disruption in microbial metabolic pathways, including energy metabolism and biosynthesis, in both sites. Importantly, a positive correlation was observed between lung and gut dysbiosis, indicating an interconnected gut–lung axis during cryptococcosis. These findings demonstrate that C. neoformans infection causes coordinated disruptions in microbiota and immunity across the gut–lung axis, underscoring the microbiome as a critical modulator of host response and suggesting potential avenues for microbiome-targeted therapies.

Abstract Purpose of the Review The lung and gut microbiomes have been associated with many important patient-centered outcomes in respiratory diseases, and these have been further associated with pulmonary immunity. Lung transplant patients are necessarily unique with regards to their microbiome characteristics and their immune responses. The goal of this review is to summarize the emerging literature relevant to of bidirectional relationship of the microbiome and pulmonary immunity, with a focus on data relevant to lung transplant recipients. Recent Findings Lung transplant patients tend to have increased lung bacterial burden and shifts in microbial community composition relative to healthy controls. These lung microbiome changes are linked to important post-transplant outcomes, including primary graft dysfunction, acute rejection, and chronic lung allograft dysfunction. Furthermore, these lung microbiome characteristics—especially having an increased lung bacterial burden or communities dominated by “pathogenic” taxa are associated with a pro-inflammatory pulmonary immune signals in lung transplant patients, despite their concurrent use of immunosuppression. The gut microbiome, through systemic pathways such as short-chain fatty acid (SCFA) production, also appears to influence pulmonary immunity in non-transplant patients, although its role in lung transplant recipients remains underexplored. Summary The lung microbiome remains an important factor in pulmonary immunity after lung transplantation, and the gut microbiome has been implicated as further impacting pulmonary and systemic immunity in non-transplant population. Microbiome-targeted interventions show promise—especially in selected populations—but have not yet been linked with improved patient-centered outcomes. Further research which incorporates adequate clinical context is needed to disentangle which microbiome features and immune signals might be harnessed or targeted to optimize post-transplant care and prolong allograft survival.

Lung cancer incidence continues to increase globally, with an estimated mortality rate of 18% worldwide. Current management strategies focus on early screening, early treatment, and palliative care. However, more fundamental approaches are needed to improve treatment outcomes. The gut-lung axis has emerged as an important factor in lung cancer pathophysiology, as it plays a role in pulmonary immune defense and is influenced by changes in gut and lung microbiota. Alterations in microbial composition have been observed in lung cancer patients and may contribute to disease progression. Systemic chemotherapy, while targeting cancer cells, also exerts systemic effects that may disrupt gut and lung microbiota, leading to dysbiosis. These changes may influence treatment response, immune modulation, and clinical outcomes in lung cancer patients. This narrative review explores the role of the gut-lung axis in lung cancer and examines the impact of systemic chemotherapy on gut and lung microbiota. Understanding the interaction between chemotherapy and the gut-lung axis may provide insight into potential adjuvant strategies to improve treatment effectiveness and patient quality of life.

The harsh environments of high-altitude habitats present formidable challenges for animal survival and reproduction. The adaptation of plateau endotherms to hypoxic and cold stresses has been studied for more than a century. However, the responses and contributions of the symbiotic microbiota to host adaptation remain unclear. Here, we conducted an integrated analysis of the gut and respiratory microbiomes of Tibetan chickens native to the high-altitudes of Lhasa and maintained for 20 years (approximately 20 generations) in low-altitude Beijing, as well as other high- and low-altitude breeds, to determine microbiota-host co-evolution in high-altitude adaptation. The results revealed that the respiratory microbial composition differed from that of the gut. The cecal microbiota was enriched in metabolic pathways, whereas the lung microbiota was more enriched in environmental information processing. Higher microbial diversity was observed in the ceca of chickens housed in Lhasa, whereas the lungs presented lower microbial diversity. Notably, consistent with the varying altitudes, the microbial communities in the ceca and lungs could be classified into distinct enterotypes and pulmotypes, respectively. The lung microbiome exhibited a more rapid environmental adaptation response to high-altitude environments, as 88 microbial genera were identified as signatures of high-altitude adaptation compared with only 7 in the ceca. Additionally, cecal Acetobacteroides was jointly regulated by the environmental conditions and host genetics, with higher abundance in the high-altitude chickens. FST analysis and mbQTL mapping identified NAT8L as a key gene under natural selection influencing Acetobacteroides colonization. Moreover, genotype-associated differences in metabolite levels indicate a potential link between NAT8L and Acetobacteroides, possibly through shared involvement in alanine, as-partate, and glutamate metabolism. These findings reveal a host gene-metabolism-microbiota axis that enhances energy efficiency, offering new perspectives for microbiota-host collaboration in high-altitude adaptation.

Nontuberculous mycobacteria (NTM) are ubiquitous bacteria that cause a spectrum of diseases, most notably pulmonary disease (NTMPD). The host factors contributing to the heightened susceptibility and severity of NTMPD in elderly individuals are poorly understood. Prior studies have reported increased incidence of NTMPD in individuals receiving immune modulatory biologics such as anti-TNF and JAK-STAT inhibitors. Moreover, we recently described that age-related changes in the lung microbiome, notably the loss of a main commensalTropherymaspecies, may contribute to increased severity. Therefore, in this study we explore the hypothesis that TNF-inhibition and a disrupted lung microbiome are key factors that contribute to worse disease outcomes in older NTMPD patients. Young (4–6 years old) rhesus macaques were pretreated with nebulized amikacin and vancomycin to deplete the lung microbiome, pretreated with the TNF inhibitor Inflectra or left untreated. Animals were subsequently inoculated withM. aviumsubsp.hominissuis(MAH) in the right lung. Bacterial load, radiographic changes, immune responses, and microbiome composition were monitored longitudinally. Antibiotic-treated animals experienced significant dysbiosis including the depletion ofTropherymafrom the lung microbiome. One antibiotic-treated animal developed and resolved cavitary disease after the lung microbiome returned to homeostasis. Inflectra-treated animals favored an acute-phase response that persisted up to 114 days after inoculation and one Inflectra-treated animal developed chronic granulomatous disease. No control animals showed granulomas. These data suggest that lung microbiome dysbiosis and TNF inhibition can increase susceptibility to NTM granulomatous disease.

CFTR modulators such as lumacaftor/ivacaftor (LUM/IVA) may reshape microbiota-mycobiota composition in the lungs and gut. While the gut-lung axis is established in other settings, little is known about its role following modulator therapy, particularly in the 2-11 age group. In a prospective national multicentre study, 116 children with cystic fibrosis (2-11 years) starting LUM/IVA were followed for 12 months. Stool and sputum were collected at baseline, 3, 6 and 12 months. Bacterial and fungal communities were profiled by 16S rRNA and ITS2 sequencing; diversity, dysbiosis indices, faecal and sputum calprotectin, and gut-lung microbial networks were analysed. LUM/IVA was associated with increased bacterial diversity and compositional shifts in gut and lung microbiota, alongside a significant reduction in faecal calprotectin. Airway mycobiota diversity remained stable. Two lung microbiome response profiles emerged: "responders" (greater bacterial diversity gain) and "non-responders" (minimal change). Baseline gut and lung composition predicted these profiles with 81% accuracy in a random-forest model. Inter-organ microbial interactions peaked at 3 months after initiation and then diverged between profiles, indicating distinct gut-lung axis remodelling. LUM/IVA influences gut-lung microbiota-mycobiota dynamics, with heterogeneous responses between paediatric patients. Identifying factors predictive of response is a key future challenge. In 116 children aged 2-11, lumacaftor/ivacaftor reshaped gut and lung microbiota and reduced fecal calprotectin over 12 months. First pediatric multicenter study integrating bacterial and fungal profiling of stool and sputum with gut-lung network analyses; identifies two distinct lung microbiome response profiles. Baseline gut and lung composition predicted the response profile with approximately 81% accuracy. Highlights a 3-month interaction peak and baseline profiling as practical markers to guide monitoring and microbiome-informed precision care.

The brain-lung axis: bridging neurological and respiratory disorders via neural-immune-microbial dialogue.

Breathing plastics: Influence of airborne microplastics on the respiratory microbiome and health of human lungs (Review)

Lung microbiota has been proven to be closely related to lung cancer, but the precise mechanisms remain unclear. In this study, we found that the quorum-sensing regulator C8-HSL, secreted by Gram-negative bacteria, could promote the proliferation of H460 lung cancer cells invitro and invivo. C8-HSL could also promote the migration and invasion of H460 cells. Moreover, C8-HSL promoted the proliferation, migration, and invasion of H460 cells by activating the PI3K/AKT/ERK pathway. C8-HSL promoted the cell cycle progression of H460 cells by upregulating the expression levels of CDC25A, c-MYC, p-GSK3β, p-Rb, and Cyclin E1, while downregulating the expression levels of p16 and p27. C8-HSL promoted the migration and invasion of H460 cells by upregulating the expression level of MMP9 and downregulating the expression level of E-cadherin. This is the first report of C8-HSL as a promoter of lung cancer cell proliferation, migration, and invasion. Taken together, C8-HSL is a potential risk factor for lung cancer, and strategies targeting C8-HSL-producing bacteria and monitoring C8-HSL concentrations may be beneficial for the prevention and control of lung cancer.

Lung cancer is the leading cause of cancer-related deaths. The human microbiome plays an important role in regulating response to cancer therapeutics, outcomes, and biological processes. However, little is known regarding the interplay between the lung microbiome and other biological processes in cancer. In an exploratory pilot study, we collected bronchoalveolar lavage fluid and brushings from 20 patients with early-stage lung cancer and performed microbial sequencing, untargeted metabolomics, and cytokine analysis. In addition, we employed computational and machine-learning approaches to identify integrated microbial-immunometabolic pathways. Finally, we performed preliminary mechanistic studies to confirm our findings. Previously, we published that upper airway microbiota were selectively enriched in tumor-affected lobes. In the present study we demonstrate that enrichment of pro-tumorigenic cytokines and specific fatty acids are associated with tumor-affected lobes. Finally, we find that long-chain fatty acid stimulation of macrophages leads to neoplastic transformation of lung epithelial cells. Therefore, the findings of this study identify a perturbed fatty acid-macrophage axis that is a potential biomarker of early-stage lung cancer and will lead to development of novel therapeutic agents.

Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) remain among the most frequent complications in critically ill patients. Despite the implementation of modern preventive strategies and the widespread use of broad-spectrum antibiotics, both the incidence and treatment failure rates remain high. However, no adjunctive therapy is currently recommended. Glucocorticoids have recently attracted renewed interest as potential immunomodulatory agents in this setting. By reducing excessive inflammation and promoting the resolution of the immune response, they may help limit lung injury and improve clinical outcomes. This hypothesis is supported by findings from related conditions such as community-acquired pneumonia, acute respiratory distress syndrome, and severe COVID-19, where corticosteroids have demonstrated benefits in selected populations. However, evidence specific to HAP and VAP remains limited. A few randomized trials have evaluated corticosteroids for prevention, particularly in trauma patients, where findings suggest a potential benefit and highlight the relevance of this strategy in select populations. More recently, individualized approaches based on inflammatory biomarkers have shown promise in identifying patients who are more likely to benefit from corticosteroid therapy. Two randomized controlled trials, currently ongoing to evaluate their role as adjunctive treatment in established HAP and VAP, will help define the efficacy and tolerance of steroids. Given the heterogeneity of immune responses in critically ill patients, a "one-size-fits-all" approach is unlikely to be effective. Identifying inflammatory sub-phenotypes using clinical and biological markers (such as C-reactive protein or interleukin-6) may help guide a more personalized use of immunomodulatory therapies. Alterations in the lung microbiome could also influence host response and treatment efficacy. Altogether, corticosteroids represent a promising but still understudied adjunctive strategy for HAP and VAP. Future research should aim to refine patient selection and optimize treatment strategies within a precision medicine framework.

This review aggregates, analyzes, and summarizes the current understanding of the lung microbiome as it relates to pneumonia. We will review the composition and function of a healthy lung microbiome and conceptualize dysbiosis associated with pneumonia. Finally, we discuss how the lung microbiome impacts the diagnosis, prognostication and pathogenesis, and recovery from pneumonia. The most tangible benefit of studying the lung microbiome has been the identification of pathogenic organisms in suspected pneumonia; however, as there is a growing body of evidence that suggest the lung microbiome is critical to pneumonia. Generally, detection of potential pathogens such as Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pneumoniae, and Escherichia coli can be found even when sampling the lung microbiome of healthy individuals, yet it is unclear what determines the transition from potential pathogens present as bystanders to pathogens driving the development of pneumonia. Analysis of the lung microbiome suggests that the loss of "oral commensals" (bacteria found in the oral microbiome) in the lower airways is associated with the development of pneumonia and may provide diagnostic and prognostic insights. The lung microbiome is a rich and dynamic ecosystem comprised of numerous bacterial, fungal, and viral taxa that may contribute to pneumonia pathogenesis. There is increasing evidence that the lung microbiome may provide insight into factors that determine the pathogenicity of respiratory microbes and the susceptibility of individuals to those pathogens.

BackgroundDrug-resistant tuberculosis (DR-TB) undermines global TB control, yet how resistant Mycobacterium tuberculosis strains interact with the lung microbiome, phage communities, and local host immunity remains poorly defined.MethodsIn a prospective cohort of 130 pulmonary TB patients (49 DR-TB, 81 drug-susceptible TB [DS-TB] patients), bronchoalveolar lavage fluid (BALF) was subjected to paired metagenomic and transcriptomic profiling. Microbial and bacteriophage community structures were assessed by diversity metrics and differential abundance testing, whereas host responses were characterized by gene expression, pathway enrichment, and immune cell deconvolution. A Random Forest model was trained to evaluate the diagnostic potential of host transcriptional signatures.ResultsDR-TB airways presented distinct microbial beta diversity, with enrichment of Streptococcus spp. and streptococcal-targeting phages (e.g., Javan variants, phi-Ssu5SJ28rum). Transcriptomic analysis revealed 494 differentially expressed genes, which were associated with increased oxidative phosphorylation, suppressed ion channel and transporter activity, and enrichment of extracellular matrix remodeling pathways. Immune profiling demonstrated a significant reduction in γδ T cells in DR-TB patients (P = 0.0059). An 8-gene host-derived signature (ARHGEF5, PTGES3L, GAL3ST1, RANBP17, ACTA2_AS1, CBY3, MAMSTR, and LOC102031319) discriminated DR-TB from DS-TB with high accuracy (AUC = 0.837).ConclusionThis dual-omics study defines the airway niche of DR-TB as a convergence of microbial dysbiosis, phage imbalance, and host immune–metabolic dysfunction. By uncovering DR-TB–specific microbial and transcriptional signatures, and deriving a predictive host-based classifier, our findings provide mechanistic insights and highlight novel opportunities for microbiome- and host-directed interventions in drug-resistant tuberculosis.

The lung-targeting characteristic of Hantavirus infection and the unclear mechanism underlying its interaction with the lung microbiome hampers the development of effective prevention and control strategies. In this study, lung tissues from Apodemus agrarius and Rattus norvegicus were collected at Hantavirus surveillance sites in Hunan Province. Metagenomic sequencing was subsequently applied to compare microbiome diversity, community structure, and function between infected and uninfected groups. Then the linear discriminant analysis effect size (LEfSe) was employed to identify key biomarkers. The results indicated that after infection with Hantaan virus (HTNV), Apodemus agrarius exhibited significantly increased evenness but markedly decreased richness of lung microbial communities, as reflected by consistent reductions in the number of observed species, Abundance-based Coverage Estimator (ACE) index, and Chao1 index. In contrast, Rattus norvegicus infected with Seoul virus (SEOV) showed no significant difference in microbial richness compared with uninfected controls, and even a slight increase was observed. These findings suggest that host species and virus type may play an important role in shaping microbial community responses. Furthermore, β-diversity analysis showed that the community structure was clearly separated by the host rodent species, as well as by their virus infection status. LEfSe analysis identified taxa with discriminatory power associated with infection status. Streptococcus agalactiae and Streptococcus were associated with SEOV-infected Rattus norvegicus, while Chlamydia and Chlamydia abortus were relatively enriched in uninfected Apodemus agrarius. This exploratory study reveals preliminary association between specific host-Hantavirus pairings (HTNV-Apodemus agrarius and SEOV-Rattus norvegicus) and the rodent lung microbiome, offering potential insights for future research into viral pathogenesis.

COVID-19 weakens the body’s immune system and predisposes to bacterial infections. It has been increasingly evident about changes in the etiological pattern of pneumonia pathogens due to altered lung microbiota after viral pneumonia, the effect of SARS-CoV-2 on the immune system, and antibiotics taking as part of preventing secondary bacterial infection. Our study was aimed to analyze the dynamic change in the pattern of the respiratory tract microbiota in patients with severe pneumonia in the years from 2019 to 2023. There were enrolled 304 patients with pneumonia diagnosed after X-ray examination assessed from January 2019 to December 2023 inclusive. During the pandemic, all the investigated patients had a positive SARS-CoV-2 PCR result, and in the period after the pandemic all the examined patients were negative. Sputum samples delivered to the laboratory, where we performed microbiological culture with identification by MALDI-ToF mass spectrometry. In the pre-COVID-19 pandemic, 62 sputum samples were analyzed, among which Klebsiella pneumoniae and Stenotrophomonas maltophilia were the most common found in 21% and 17.7%, respectively. Both Acinetobacter baumanii and Staphylococcus aureus were isolated in 14.5% cases. Streptococcus pneumoniae was found in 8.1% cases. During the COVID-19 pandemic, 122 samples were evaluated allowing to observe that K. pneumoniae accounted for half of all isolated microorganisms. The second most common was A. baumannii (23.8%). In the post-pandemic period, 120 samples were analyzed, from which K. pneumoniae was mainly identified (31.7%). The next most frequent among pathogens were S. aureus and A. baumannii — 23.3% and 18.3%, respectively. In this way, there was a statistically significant change in the frequency of detection of Gram-positive and Gram-negative microorganisms in ICU patients during the study periods. Before the COVID-19 pandemic, the proportion of Gram-negative microorganisms in the pattern of pathogens was 67.7%, during the pandemic — 91.0%, in the post-pandemic period — approached the values of 2019–2020 and amounted to 70.0% (p 0.001). K. pneumoniae and A. baumannii were the most frequently found, however, the statistical significance of the changes was observed only for K. pneumoniae (p 0.005). An insignificant decline in the detection rate of pneumococcus was established as well. The frequency of staphylococcal discharge after coronavirus infection exceeded the pre-pandemic magnitude (p 0.001).

Chronic obstructive pulmonary disease (COPD) is a progressive and debilitating respiratory condition marked by chronic symptoms and frequent exacerbations, contributing to significant morbidity and mortality. The advent of molecular microbiology and next-generation sequencing (NGS) has expanded our understanding of the lung microbiome, and integration of microbiome datasets with other omics reveals important microbial-metabolic-immuno-inflammatory interactions that influence COPD pathogenesis. Recent studies have highlighted dysbiosis of the airway microbiome, with shifts in bacterial, viral, and fungal communities playing a crucial role in disease progression, exacerbations and clinical outcomes. Moreover, microbiome changes are observed in COPD associated overlap syndromes, complicating diagnosis and treatment. This review synthesizes current microbiome research in COPD, focusing on its clinical relevance, including its potential as a diagnostic and prognostic tool. We additionally discuss the challenges of integrating microbiome data into clinical practice, emphasizing the need for personalized, precision medicine approaches to optimize COPD management and improve patient outcomes.

Air pollution, aggravated by the use of fossil fuels, has intensified respiratory diseases and generated new health risks, especially in vulnerable populations. Climatic phenomena, such as heat waves and forest fires, amplify these impacts, while gases such as PM2.5 and CO₂ are associated with millions of deaths. This study, conducted using the PICo (Population, Phenomenon, and Context) strategy and articles from 2020 to 2024 obtained from PubMed and Google Scholar databases, aims to conduct a narrative review on the consequences of air quality degradation on respiratory diseases. Air pollution is related to increased hospitalizations, with negative effects especially on children and the elderly. Exposure to pollutants aggravates chronic respiratory conditions and affects the lung microbiome, intensifying diseases such as asthma and bronchitis. In addition, local pollution, including burning, has significant impacts on public health. To mitigate these effects, it is crucial to adopt public policies that improve air quality, such as promoting efficient public transportation and the use of cleaner fuels. This study proposes further research on the interaction between pollution, microbiome, and health, with a view to supporting effective public health promotion actions.

Pulmonary mycobacterial diseases (PMDs) remain a leading cause of infectious disease-related mortality worldwide, with the majority of cases attributed to the Mycobacterium tuberculosis complex (MTBC). However, non-tuberculous mycobacteria (NTM) can also cause PMDs, and the incidence of non-tuberculous mycobacterial pulmonary disease (NTM-PD) has been increasing in recent years. This study aimed to explore the lung microbiota and assess the clinical application of bronchoalveolar lavage fluid metagenomic next-generation sequencing (BALF-mNGS) in patients with PMDs caused by MTBC or NTM. This multicenter, retrospective study included patients with suspected PMDs between July 2021 to June 2025. mNGS and conventional diagnostic methods (CDTs), including GeneXpert, BALF culture, acid-fast bacillus (AFB) staining, and T-SPOT, were performed. Based on the microbiological diagnosis, patients were classified into TB and NTM-PD groups. We further analyzed the clinical impact of different MTBC/NTM abundance levels. The relative abundance of MTBC/NTM was represented by reads ten per million (RTPM). Patient clinical characteristics, length of hospital stay (LOHS), laboratory results, and treatment effectiveness were collected from the electronic medical record system. Compared with the TB group, patients with NTM-PD exhibited a higher prevalence of immunosuppression (34.96% vs. 53.85%, P = 0.013), particularly prolonged corticosteroid or immunosuppressant therapy (8.94% vs. 21.54%, P = 0.016). In the TB group, higher MTBC abundance was associated with increased positivity of CDTs and alterations in pulmonary microbiota, including enrichment of Candida albicans and other opportunistic pathogens. In the NTM-PD group, although CDTs positivity did not significantly differ between high- and low-abundance subgroups (21.21% vs. 20.00%, P = 0.906), higher NTM abundance was linked to distinct microbial community patterns and a markedly higher ineffective treatment rate (66.67% vs. 39.39%, P = 0.043). Notably, in both TB and NTM-PD groups, elevated MTBC or NTM abundance was associated with longer hospital stays and lower treatment effectiveness, indicating that pathogen abundance is significantly associated with clinical outcomes in pulmonary mycobacterial diseases. BALF-mNGS not only provides superior pathogen detection in patients with PMDs but also shows that lower MTBC/NTM abundance is associated with better clinical prognosis, including shorter hospital stay and better treatment effectiveness, highlighting its potential role as a prognostic indicator.

Human microbiota is now recognized as a fundamental organ of the body. In its healthy state, it fulfills essential local and systemic functions, whereas dysbiosis disrupts these roles and can contribute to disease. Although numerous studies have examined the relationship between microbiota and cancer, often revealing conflicting mechanisms and outcomes, this work has focused almost exclusively on the gut, leaving the lung microbiota largely unexplored. In this project, a ferrocifen compound was selected as an anticancer agent for lung cancer therapy. We found that lung microbiota actively degraded the ferrocifen. To prevent this degradation, the antibacterial peptide buforin II was synthesized, purified, and characterized. After confirming its antimicrobial activity, it was covalently conjugated to the ferrocifen, yielding an amphiphilic bioconjugate. This prodrug was subsequently formulated into self-assembled structures to enhance ferrocifen solubility and bioavailability. The resulting self-assemblies were evaluated in an orthotopic murine model of lung cancer and administered via nebulization to assess their therapeutic efficacy. A significant reduction in tumor progression and an improved predicted survival in mice were obtained. Together, these findings highlight the capacity of the lung microbiota to interfere with anticancer therapies and underscore the importance of considering this flora when designing treatment strategies for lung cancer.

BackgroundAcute lung injury (ALI) is a severe respiratory disease characterized by diffuse lung injury, vascular barrier dysfunction, and inflammatory responses. Its current treatments such as corticosteroids often involve adverse effects, highlighting the need for alternative therapies. Salvia miltiorrhiza-derived extracellular vesicles (SMEVs) have shown a potential therapeutic value for ALI due to their anti-inflammatory and barrier-protective properties, but the specific mechanisms remain unclear.MethodsSMEVs were extracted and purified through differential centrifugation coupled with sucrose density gradient centrifugation, and were analyzed by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). Biosafety assessment was then conducted in zebrafish embryos, mouse organs, and human umbilical vein endothelial cells (HUVEC). Subsequently, the treatment efficacy of SMEV on LPS-induced HUVEC inflammation was evaluated in vitro. LPS-induced ALI mice were then treated with SMEVs to further evaluate the posttreatment lung histopathology, vascular barrier markers, and microbial composition using metagenomics in vivo.ResultsSMEVs exhibited a typical bilayer structure (average size: 177.7 nm) and excellent biosafety properties. In vitro, SMEVs effectively reduced LPS-induced inflammation (IL-1β, IL-6, TNF-α) and promoted wound healing in HUVEC, while in vivo, SMEVs ameliorated pulmonary edema and inflammation, and restored the VE-cadherin expression. Metagenomic analysis revealed that SMEVs were capable of regulating lung microbiota and reducing the pathogenic bacterial (e.g., g-Listeria, g-Streptococcus) and microbial diversity and richness after LPS stimulation.ConclusionSMEVs can ameliorate ALI by repairing the vascular barrier and modulating lung microbiota, offering a novel therapeutic strategy for this disease. Future research may focus on the SMEV-microbiota-immune interaction targeting ALI treatment.