Progesterone attenuates airway remodeling and glucocorticoid resistance in a murine model of exposing to ozone

Deflamin Attenuated Lung Tissue Damage in an Ozone-Induced COPD Murine Model by Regulating MMP-9 Catalytic Activity

Chronic obstructive pulmonary disease (COPD) is comprised of histopathological alterations such as pulmonary emphysema and peribronchial fibrosis. Matrix metalloproteinase 9 (MMP-9) is one of the key enzymes involved in both types of tissue remodeling during the development of lung damage. In recent studies, it was demonstrated that deflamin, a protein component extracted from Lupinus albus, markedly inhibits the catalytic activity of MMP-9 in experimental models of colon adenocarcinoma and ulcerative colitis. Therefore, in the present study, we investigated for the first time the biological effect of deflamin in a murine COPD model induced by chronic exposure to ozone. Ozone exposure was carried out in C57BL/6 mice twice a week for six weeks for 3 h each time, and the treated group was orally administered deflamin (20 mg/kg body weight) after each ozone exposure. The histological results showed that deflamin attenuated pulmonary emphysema and peribronchial fibrosis, as evidenced by H&E and Masson's trichrome staining. Furthermore, deflamin administration significantly decreased MMP-9 activity, as assessed by fluorogenic substrate assay and gelatin zymography. Interestingly, bioinformatic analysis reveals a plausible interaction between deflamin and MMP-9. Collectively, our findings demonstrate the therapeutic potential of deflamin in a COPD murine model, and suggest that the attenuation of the development of lung tissue damage occurs by deflamin-regulated MMP-9 catalytic activity.

Research trends on airway remodeling: A bibliometrics analysis

Background

Airway remodeling is an essential pathological basis of respiratory diseases such as asthma and COPD, which is significantly related to pulmonary function and clinical symptoms. And pulmonary disease can be improved by regulating airway remodeling. This study aimed to establish a knowledge map of airway remodeling to clarify current research hotspots and future research trends.

Methods

A comprehensive search was performed to analyze all relevant articles on airway remodeling using the Web of Science Core Collection Database from January 01, 2004 to June 03, 2023.2 reviewers screened the retrieved literature. Besides, the CiteSpace (6.2. R3) and VOSviewer (1.6.19) were utilized to visualize the research focus and trend regarding the effect of airway remodeling.

Results

A total of 4077 articles about airway remodeling were retrieved. The United States is the country with the most published literature, underscoring the country's role in airway remodeling. In recent years, China has been the country with the fastest growth in the number of published literature, suggesting that China will play a more critical role in airway remodeling in the future. From the perspective of co-operation among countries, European co-operation was closer than Asian co-operation. The co-citation analysis showed that 98,313 citations were recorded in 3594 articles, and 25 clusters could be realized. In recent years, Burst detection shows that oxidative stress and epithelial-mesenchymal transition are hot words.

Conclusions

Based on the bibliometric analysis of airway remodeling studies in the past 20 years, a multi-level knowledge structure map was drawn, it mainly includes countries, institutions, research fields, authors, journals, keywords and so on. The research directions represented by obstructive airway disease, PDGF-BB treatment of airway smooth muscle, allergen-induced airway remodeling, extracellular matrix, and non-coding RNA are the research hotspots in the field of airway remodeling. While the risk factors for airway remodeling, the application of new noninvasively assessing tools, biomarkers as well as The molecular mechanism represented by EMT and autophagy had been frontiers in recent years.

Effective-component compatibility of Bufei Yishen formula alleviates chronic obstructive pulmonary disease inflammation by regulating GSK3β-mediated NLRP3 inflammasome activation

Glycogen synthase kinase 3β (GSK3β) has been associated with sensing many different stimuli to trigger the NLRP3 inflammasome, which plays a crucial role in promoting the inflammatory response in diseases, including chronic obstructive pulmonary disease (COPD). Bufei Yishen formula (BYF), a traditional Chinese herbal medicine, has beneficial effects on COPD. Effective-component compatibility of BYF (ECC-BYF), optimized from BYF, is equally effective as BYF in inhibiting COPD inflammation. However, the exact mechanism by which ECC-BYF regulates the activation of NLRP3 inflammasome to inhibit COPD inflammation remains unclear. Hence, we investigated the mechanisms underlying the alleviation of COPD inflammation by ECC-BYF through the inhibition of GSK3β-mediated NLRP3 inflammasome activation by experimental rat model of COPD and lipopolysaccharide/adenosine triphosphate (LPS/ATP) induced macrophages. The data showed that ECC-BYF significantly improved the lung function, attenuated histopathological damage, and alleviated inflammatory cell infiltration and alveolar destruction. Further, it significantly inhibited inflammatory cytokine production and downregulated the phosphorylation of GSK3β by inhibiting the activation of NLRP3 inflammasome in the rat model of COPD. Moreover, ECC-BYF suppressed the activation of the NLRP3 inflammasome by increasing the phosphorylation at serine 9 and decreasing the phosphorylation at tyrosine 216 of GSK3β, followed by the inhibition of IL-1β secretion in macrophages. Together, ECC-BYF effectively ameliorates COPD by suppressing inflammation, which is dependent on the regulation of GSK3β-mediated NLRP3 inflammasome activation.

Endogenous inhibitory mechanisms in asthma

Endogenous inhibitory mechanisms promote resolution of inflammation, enhance tissue repair and integrity, and promote homeostasis in the lung. These mechanisms include steroid hormones, regulatory T cells, IL-10, prostaglandin E2, prostaglandin I2, lipoxins, resolvins, protectins, maresins, glucagon-like peptide-1 receptor, adrenomedullin, nitric oxide, and carbon monoxide. Here we review the most recent literature regarding these endogenous inhibitory mechanisms in asthma, which remain a promising target for the prevention and treatment of asthma.

K-means cluster analysis of characteristic patterns of allergen in different ages: Real life study

BACKGROUND

Atopy varies in people of different ages owing to different physical conditions and exposure to allergens. We aimed to cluster ages based on atopic severity using K-means cluster analysis and identify atopic incidence, severity, as well as the association among peripheral eosinophils, IgE and sensitisation.

METHODS

Consecutive patients (n = 7654) with allergic symptoms and undergoing allergen-specific IgE tests were included from 2013 to 2017. Age, sex, specific-IgE, peripheral eosinophil counts and total-IgE were collected.

RESULTS

Five age categories were identified: 1-17, 18-36, 37-52, 53-69 and 70-100 years. The incidences of atopy and poly-sensitisation decreased with increasing age. Similar trend was observed for aeroallergens, egg and milk but not for peanuts, soy or seafood. Dust mites remain the crucial factor bothering patients with allergic symptoms, especially for children and adolescents. In patients aged <52 years, sensitisation to aeroallergens was more prevalent than food. In group 37-52 years, incidence of females' atopy was higher than that of males. The overlap of atopy, high eosinophils, and high total-IgE was found in only 19.18% of patients. The trend of allergen-test positivity is not parallel to total IgE and peripheral eosinophil counts.

CONCLUSION

Age-grouping based on cluster analysis helps to find the changes in atopic status and distribution of sensitised allergens with age. Allergen tests are still necessary in the clinical diagnosis and treatment. An innovative exploration of the influence of age and allergens on total-IgE and eosinophil counts is helpful for the development of bio-targeted precision therapy.

CLINICAL TRIAL REGISTRATION

ChiCTR2300067700.

Tiao-Bu-Fei-Shen Formula Improves Glucocorticoid Resistance of Chronic Obstructive Pulmonary Disease via Downregulating the PI3K-Akt Signaling Pathway and Promoting GRα Expression

Objective

To predict and determine the mechanism through which Tiao-Bu-Fei-Shen (TBFS) formula improves glucocorticoid resistance in chronic obstructive pulmonary disease (COPD), using network pharmacology, molecular docking technology, and in vitro studies.

Methods

The main active components and associated targets of TBFS were screened using the systems pharmacology database of traditional Chinese medicine database (TCMSP). The main COPD targets were retrieved from the Human Gene (GeneCards) and DrugBank databases. A protein-protein interaction (PPI) network was constructed using the protein interaction platform STRING and Cytoscape 3.6.1. Gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genome Pathway (KEGG) analyses were performed using the biological information annotation database Metascape. Molecular docking was performed using the AutoDock Vina software. THP-1 monocytes were treated with TBFS-containing serum and cigarette smoke extract (CSE) for 48 h, and cell proliferation in each group was determined using cell counting kit-8 (CCK-8). A COPD cell model was constructed by stimulating THP-1 monocytes with CSE for 12 h. A lentivirus vector for RNA interference of histone deacetylase 2 (HDAC2) gene was constructed and transfected into the THP-1 monocytes, and the transfection efficiency was verified using quantitative polymerase chain reaction (qPCR) and western blotting (WB). The expression of HDAC2 in each group of cells was detected using qPCR, and the expression of HDAC2, phosphoinositide-3 kinase (PI3K) p85α, glucocorticoid receptor α (GRα), and P-AKT1 in each group of cells was detected through WB.

Results

A total of 344 TBFS active components, 249 related drug targets, 1,171 COPD target proteins, and 138 drug and disease intersection targets were obtained. Visual analysis of the PPI network map revealed that the core COPD targets of TBFS were AKT1, IL-6, TNF, TP53, and IL1-β. KEGG pathway enrichment analysis resulted in the identification of 20 signaling pathways as the main pathways involved in the action of TBFS against COPD, including the PI3K-Akt, TNF, and IL-17 signaling pathways. Molecular docking experiments revealed a strong binding capacity of kaempferol, luteolin, and quercetin to the ATK1 protein in TBFS, with quercetin performing the best. PCR results showed that treatment with TBFS significantly increased the expression levels of HDAC2 in the COPD model. WB results showed that TBFS treatment significantly increased the expression levels of GRα and HDAC2 in the COPD model, while reducing the expression levels of P-AKT1.

Conclusion

TBFS treatment improves glucocorticoid resistance observed in COPD through downregulation of the PI3K-Akt signaling pathway and promotion of GRα expression.

Adipose-derived mesenchymal stem cells suppress ozone-mediated airway inflammation in a mouse model of chronic obstructive pulmonary disease

OBJECTIVE AND DESIGN

Ozone exposure is an important risk factor for Chronic Obstructive Pulmonary Disease (COPD) which is a global public health concern. Until now, there is no effective approach to reverse airflow limitation and accelerated loss of lung function completely. Here, we delineate the efficacy of mouse allogeneic adipose-derived mesenchymal stem cells (mASCs) in the treatment of COPD mice by intratracheal and intravenous administration.

METHODS

In this study, we established ozone-exposed COPD model in mice and were administered intratracheally or intravenously with mASCs which were extracted, cultured, and identified in vitro.

RESULTS

We observed that exposure to ozone resulted in a marked lung neutrophilia with high levels of inflammatory cell counts, enhanced expression of cytokines IL-1β and TNF-α, reduced expression of IL-10, lung function and airspace enlargement. mASCs intratracheal administration rescured the lung neutrophilia, lung function and emphysema-like phenotype. Similar results were observed in mice with mASCs intravenous administration. But the altered levels of serum cytokines in mice with mASCs intratracheal administration appears more robust than those in mice with mASCs intravenous administration.

CONCLUSIONS

Collectively, these data indicate that intratracheal administration of mASCs appears more effective in treating ozone-induced COPD compared to intravenous administration of mASCs, although the two approaches can be comparable in safety. mASCs are expected to become a new potential intervention strategy for COPD.

Hormonal Effects on Asthma, Rhinitis, and Eczema

Hormones significantly influence the pathogenesis of asthma, rhinitis, and eczema. This review aims to summarize relevant clinical considerations for practicing allergists and immunologists. The first section reviews the effects of sex hormones: estrogen, progesterone, and testosterone. The second concerns insulin production in the context of type 1 and type 2 diabetes. The third concludes with a discussion of thyroid and adrenal pathology in relationship to asthma, rhinitis, and eczema.

Tracking the response to Pseudomonas aeruginosa infection in ozone-induced chronic obstructive pulmonary disease mouse models

Pseudomonas aeruginosa (P. aeruginosa) is commonly isolated from the sputum of COPD patients. However, the precise role of P. aeruginosa infection in the progression of COPD, especially its role in altering inflammation remains unclear. Here, we designed mice models of COPD infected with P. aeruginosa (PA) and observed dynamic changes of lung structure, lung inflammatory microenvironment, lung function. After infection, the level of mucus secretion peaked on day 3 and remained higher throughout the study period, and the airway remodeling and emphysema was starkly apparent on day 14 and 21. On day 3, interferon-γ and interleukin (IL)- 5 levels increased rapidly, accompanied by elevated T-bet mRNA expression and CD4⁺T-bet⁺ cells; at the late stage of infection (days 14 and 21), consistent with increased GATA3 mRNA expression and CD4⁺GATA3⁺ cells, IL-4 and IL-13 levels significantly increased; IL-17A level, Foxp3 mRNA expression, CD4⁺ROR-γt⁺ cells and CD4⁺FOXP3⁺ cells remained at higher levels throughout the course of the infection. Small-airway function showed a decline from day 3 to day 21; large airway function showed a decline on day 14 and 21. Overall, P. aeruginosa infection contributed to the progression of COPD. During the infection, an early Th1-related inflammation gradually shifted to a later Th2-related inflammation, and small-airway function decline occurred earlier than that of large-airway function. On the basis of infection control, the appropriate use of glucocorticoid might slow disease progression by mitigating the enhanced Th2-related inflammation, and small airways could be also an important treatment target in P. aeruginosa -infected COPD patients.

17α-Hydroxyprogesterone Caproate Inhibits Cytokine Production via Suppression of NF-κB Activation

Cytokine release syndrome (CRS) is one of the leading causes of morbidity and mortality in COVID-19 patients with elevated levels of circulating cytokines contributing to various clinical symptoms. Favorable control of CRS represents a promising and effective strategy to mitigate the clinical outcomes of hospitalized patients with moderate to severe pneumonia. Using in vivo cytokine release assay in human peripheral blood mononuclear cell (PBMC)-engrafted immunodeficient mice, we reported that 17α-hydroxyprogesterone caproate (17-OHPC), a synthetic progestogen, exhibited significant inhibition of OKT-3-stimulated production of numerous cytokines including TNF-α, IFN-γ, IL-2, IL-4, IL-6, IL-10, and GM-CSF. Furthermore, 17-OHPC inhibited in vitro production of IFN-γ, IL-1β, IL-2, IL-6, and IL-10 in human PBMCs stimulated with OKT3, while exhibiting down-regulation of the mRNA levels of TNF-α, IFN-γ, IL-2, IL-6, and IL-10. Using the same human PBMCs, additional stimulators anti-CD28 antibody or PHA treatments led to substantial cytokine production, which was also attenuated by 17-OHPC. OKT3-stimulated phosphorylation of IκBα and nuclear translocation of NF-κB p65 in human PBMCs were also reversed by 17-OHPC, suggesting its inhibition on NF-κB signaling in immune cells. Taken together, this work reported both in vivo and in vitro inhibition of cytokine production by 17-OHPC, presumably by virtue of its suppression of NF-κB signaling. These findings provide pharmacological evidence to support the potential application of 17-OHPC in treating CRS associated with COVID-19.

Lung Function Variation during the Estrus Cycle of Mares Affected by Severe Asthma

Simple Summary

The estrus cycle and sex hormones influence asthma development and severity in humans, but whether the same is occurring in the asthma of horses is unknown. Severe equine asthma (SEA) is characterized by breathing difficulty, even at rest, and although it can be controlled by management and medication, it remains incurable. Stabling and hay feeding are the main contributors to disease exacerbation, but other factors could possibly alter the respiratory compromise. Therefore, the objective of this study was to evaluate the effects of the estrus cycle on airway dysfunction in five mares affected by SEA by assessing the lung function during the follicular and luteal phases of the reproductive cycle. The inspiratory obstruction improved during the luteal phase and the variation in progesterone and the dominant follicle size correlated with lung function parameters, suggesting a role for sex hormones in asthma pathophysiology. This first description of the estrus cycle’s modulation of airway obstruction in horses supports further studies to uncover the effects of sex hormones in asthma in horses and humans.

Abstract

While the prevalence of asthma is higher in boys than in girls during childhood, this tendency reverses at puberty, suggesting an effect of sex hormones on the disease pathophysiology. Fluctuations of asthma severity concurring with the estrus cycle are reported in women, but this phenomenon has never been investigated in mares to date. The objective of this exploratory study was to determine whether the estrus cycle modulates airway obstruction in severe equine asthma (SEA). Five mares with SEA during exacerbation of the disease were studied. The whole breath, expiratory and inspiratory resistance, and reactance were compared during the follicular and luteal phases of the estrus cycle. The reproductive tract was evaluated by rectal palpation, ultrasound, and serum progesterone levels. The inspiratory resistance and reactance improved during the luteal phase of the estrus cycle, and variation in progesterone levels and the dominant follicle size correlated with several lung function parameters. The fluctuation of airway dysfunction during the estrus cycle is noteworthy as deterioration of the disease could perhaps be expected and prevented by horse owners and veterinarians. Further studies are required to determine if the equine species could be a suitable model to evaluate the effects of sex hormones on asthma.

Host Factor Interaction Networks Identified by Integrative Bioinformatics Analysis Reveals Therapeutic Implications in COPD Patients With COVID-19

Background: The COVID-19 pandemic poses an imminent threat to humanity, especially for those who have comorbidities. Evidence of COVID-19 and COPD comorbidities is accumulating. However, data revealing the molecular mechanism of COVID-19 and COPD comorbid diseases is limited. Methods: We got COVID-19/COPD -related genes from different databases by restricted screening conditions (top500), respectively, and then supplemented with COVID-19/COPD-associated genes (FDR<0.05, |LogFC|≥1) from clinical sample data sets. By taking the intersection, 42 co-morbid host factors for COVID-19 and COPD were finally obtained. On the basis of shared host factors, we conducted a series of bioinformatics analysis, including protein-protein interaction analysis, gene ontology and pathway enrichment analysis, transcription factor-gene interaction network analysis, gene-microRNA co-regulatory network analysis, tissue-specific enrichment analysis and candidate drug prediction. Results: We revealed the comorbidity mechanism of COVID-19 and COPD from the perspective of host factor interaction, obtained the top ten gene and 3 modules with different biological functions. Furthermore, we have obtained the signaling pathways and concluded that dexamethasone, estradiol, progesterone, and nitric oxide shows effective interventions. Conclusion: This study revealed host factor interaction networks for COVID-19 and COPD, which could confirm the potential drugs for treating the comorbidity, ultimately, enhancing the management of the respiratory disease.

STAT3 and IL-6 Contribute to Corticosteroid Resistance in an OVA and Ozone-induced Asthma Model with Neutrophil Infiltration

Exposure to high levels of ozone contributes to insensitivity to glucocorticoids in asthma treatment, but the underlying mechanisms are not known. We built two asthma models: a "T2-high" asthma model was established by ovalbumin (OVA) sensitization/challenge and OVA sensitization/challenge combined with ozone exposure (OVA + ozone) was used to induce airway inflammation with increased numbers of neutrophils to simulate "T2-low" asthma. The expression of T-helper (Th)1/2/17-related cytokines was measured by cytokine antibody arrays. Bronchial provocation tests were carried out to evaluate the lung resistance of mice. Hematoxylin and eosin staining, periodic acid-Schiff staining, and immunohistochemical (IHC) analyses of alpha-smooth muscle actin were undertaken to observe morphology changes in lungs. The expression of glucocorticoid receptors (GRs) and phosphorylated-GR (p-GR) was measured by western blotting. Nr3c1 mRNA was quantified by RT-qPCR. Protein expression of proinflammatory cytokines, signal transducer and activator of transcription 3 (STAT3), suppressor of cytokine signaling 3 (SOCS3), and CXCL1 was measured through ELISAs, western blotting, or IHC analyses. Resected lung tissue from seven asthma patients and 10 healthy controls undergoing thoracotomy for pulmonary nodules was evaluated by IHC analyses and ELISAs. In both asthma models, mucus hypersecretion, as well as inflammation, hyperresponsiveness, and remodeling of the airways, was present compared with the control group, whereas the OVA + ozone group showed severe neutrophil infiltration. The expression of Th17-related cytokines (interleukin (IL)-6, IL-17A, IL-21), GR protein, and CXCL1 increased in the OVA + ozone group, whereas the expression of p-GR decreased. Dexamethasone (Dex) could not totally reverse the expression of p-GR and histone deacetylase-2 in the OVA + ozone group. STAT3 expression increased in the OVA + ozone group and could not be completely reversed by Dex, and nor could IL-6 expression. A positive correlation between IL-6 or IL-17A and STAT3 and negative correlation between SOCS3 and STAT3 were shown, suggesting that the IL-6/STAT3 pathway may be involved in OVA + ozone-induced corticosteroid-resistant airway inflammation. In clinical samples, IL-17A expression in lung tissue was positively correlated with percent STAT3-positive area and negatively correlated with SOCS3 expression. The IL-6/STAT3 pathway may contribute to corticosteroid insensitivity in OVA + ozone-induced neutrophilic airway inflammation through regulation of Th17 cells and could provide new targets for individual treatment of corticosteroid resistance in asthma.

Nonrespiratory Comorbidities in Asthma

Asthma is a chronic heterogeneous airway disease. Common comorbid conditions are often disproportionately present in severe asthma. Optimal care of patients with asthma requires the recognition and treatment of these comorbid conditions. This review outlines the pathophysiological mechanisms between nonrespiratory comorbid conditions and asthma and their effect on asthma outcomes. They include: type 2 diabetes mellitus, hypertension, atherosclerotic cardiovascular disease, adrenal and thyroid gland diseases, pregnancy, osteoporosis, adverse effects from medications, and mental health disorders. Studies indicate how poor glycemic control of type 2 diabetes mellitus is associated with not only greater health care utilization but poorer asthma outcomes. Also, a large health care claims database indicates that a substantial proportion of pregnant women have uncontrolled asthma and are prescribed suboptimal controller therapy. Additional data about these nonrespiratory comorbidities and medications known to benefit both nonrespiratory comorbidities and asthma are necessary.

Small-Airway Dysfunction is Involved in the Pathogenesis of Asthma: Evidence from Two Mouse Models

Background

There has been growing evidence of small-airway dysfunction in patients with asthma. Few studies have evaluated the mechanism of small-airway dysfunction in mouse models of asthma.

Purpose

We explored the correlation between small-airway spirometric variables and large-airway function or inflammation in different endotypes of asthma.

Methods

Ovalbumin (OVA) sensitization/challenge was used to produce a type 2 (T2)-high asthma model, and OVA combined with ozone exposure (OVA + ozone) was used for the T2-low asthma model with increased neutrophils. Spirometry, airway responsiveness, cytokine levels in bronchoalveolar lavage fluid (BALF), and pathological analyses of lung slices stained with hematoxylin-eosin, periodic acid–Schiff, and Masson’s trichrome stain were all determined. Muc5ac expression in lung tissue was evaluated by the reverse transcription-polymerase chain reaction (RT-PCR), and alpha-smooth muscle actin was measured by immunohistochemistry.

Results

Inflammatory cells infiltrated the lung tissue and inflammatory cytokines were increased in the BALF of both the OVA and OVA + ozone groups, compared with the control group. Peribronchial hypersecretion and collagen deposition were evident in the models. The OVA + ozone group showed greater neutrophilic infiltration and peribronchial smooth muscle proliferation than the OVA group. Large-airway obstruction, small-airway dysfunction, and airway hyperresponsiveness were confirmed in both models. Small-airway functional variables, such as MMEF (mean midexpiratory flow, average flow from 25 to 75% forced vital capacity [FVC]) and FEF50 (forced expiratory flow at 50% of FVC), were positively correlated with large-airway function and had a stronger negative correlation with airway inflammation, mucus secretion, and responsiveness than large-airway function.

Conclusion

Small-airway dysfunction was evident in the two endotypes of asthma and was correlated with severe airway inflammation, mucus hypersecretion, and airway hyperresponsiveness. The small airways may be an important target in asthma treatment, and further research in the role of small-airway variables in the pathogenesis of asthma is warranted.

Sex, Cells, and Asthma

There are marked sex differences in asthma prevalence and severity. Sex hormones play a central role in these sex biases and directly interact with multiple key cells involved in the pathogenesis of asthma. Here we review the known effects of estrogen, progesterone, and testosterone on airway epithelial cells, airway smooth muscle cells, the mononuclear phagocyte system, innate lymphoid cells, eosinophils, mast cells, T cells, and B cells, all in the context of asthma. Furthermore, we explore unresolved clinical questions, such as the role of sex hormones in the link between asthma and obesity.

Dynamic Changes in the Microbiome and Mucosal Immune Microenvironment of the Lower Respiratory Tract by Influenza Virus Infection

Influenza is a major public health concern, and the high mortality rate is largely attributed to secondary bacterial infections. There are several mechanisms through which the virus increases host susceptibility to bacterial colonization, but the micro-environment in lower respiratory tract (LRT) of host, infected with influenza virus, is unclear. To this end, we analyzed the LRT microbiome, transcriptome of lung and metabolome of bronchoalveolar lavage fluid (BALF) in mice inoculated intra-nasally with H1N1 to simulate human influenza, and we observed significant changes in the composition of microbial community and species diversity in the acute (7 days post inoculation or dpi), convalescent (14 dpi) and the recovery (28 dpi) periods. The dominant bacterial class shifted from Alphaproteobacteria to Gammaproteobacteria and Actinobacteria in the infected mice, with a significant increase in the relative abundance of anaerobes and facultative anaerobes like Streptococcus and Staphylococcus. The dysbiosis in the LRT of infected mice was not normalized even in the recovery phase of the infection. In addition, the infected lung transcriptome showed significant differences in the expression levels of genes associated with bacterial infection and immune responses. Finally, the influenza virus infection also resulted in significant changes in the metabolome of the BALF. These alterations in the microbiome, transcriptome, and metabolome of infected lungs were not only appeared at the acute period, but also observed at the recovery period. Furthermore, the infection of influenza virus induced a long-term effect in LRT micro-environmental homeostasis, which may give a chance for the invasion of potential pathogens.