Gut flora enhance bacterial clearance in lung through toll-like receptors 4

Alveolar macrophage modulation via the gut-lung axis in lung diseases

Several studies have demonstrated great potential implications for the gut-lung axis in lung disease etiology and treatment. The gut environment can be influenced by diet, metabolites, microbiotal composition, primary diseases, and medical interventions. These changes modulate the functions of alveolar macrophages (AMs) to shape the pulmonary immune response, which greatly impacts lung health. The immune modulation of AMs is implicated in the pathogenesis of various lung diseases. However, the mechanism of the gut-lung axis in lung diseases has not yet been determined. This mini-review aimed to shed light on the critical nature of communication between the gut and AMs during the development of pulmonary infection, injury, allergy, and malignancy. A better understanding of their crosstalk may provide new insights into future therapeutic strategies targeting the gut-AM interaction.

The respiratory microbiota and its impact on health and disease in dogs and cats: A One Health perspective

Healthy lungs were long thought of as sterile, with presence of bacteria identified by culture representing contamination. Recent advances in metagenomics have refuted this belief by detecting rich, diverse, and complex microbial communities in the healthy lower airways of many species, albeit at low concentrations. Although research has only begun to investigate causality and potential mechanisms, alterations in these microbial communities (known as dysbiosis) have been described in association with inflammatory, infectious, and neoplastic respiratory diseases in humans. Similar studies in dogs and cats are scarce. The microbial communities in the respiratory tract are linked to distant microbial communities such as in the gut (ie, the gut-lung axis), allowing interplay of microbes and microbial products in health and disease. This review summarizes considerations for studying local microbial communities, key features of the respiratory microbiota and its role in the gut-lung axis, current understanding of the healthy respiratory microbiota, and examples of dysbiosis in selected respiratory diseases of dogs and cats.

Intestinal Escherichia coli and related dysfunction as potential targets of Traditional Chinese Medicine for respiratory infectious diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM) has saved countless lives and maintained human health over its long history, especially in respiratory infectious diseases. The relationship between the intestinal flora and the respiratory system has been a popular research topic in recent years. According to the theory of the "gut-lung axis" in modern medicine and the idea that "the lung stands in an interior-exterior relationship with the large intestine" in TCM, gut microbiota dysbiosis is a contributing factor to respiratory infectious diseases, and there is potential means for manipulation of the gut microbiota in the treatment of lung diseases. Emerging studies have indicated intestinal Escherichia coli (E. coli) overgrowth in multiple respiratory infectious diseases, which could exacerbate respiratory infectious diseases by disrupting immune homeostasis, the gut barrier and metabolic balance. TCM is an effective microecological regulator, that can regulate the intestinal flora including E. coli, and restore the balance of the immune system, gut barrier, and metabolism.

AIM OF THE REVIEW

This review discusses the changes and effects of intestinal E. coli in respiratory infection, as well as the role of TCM in the intestinal flora, E. coli and related immunity, the gut barrier and the metabolism, thereby suggesting the possibility of TCM therapy regulating intestinal E. coli and related immunity, the gut barrier and the metabolism to alleviate respiratory infectious diseases. We aimed to make a modest contribution to the research and development of new therapies for intestinal flora in respiratory infectious diseases and the full utilization of TCM resources. Relevant information about the therapeutic potential of TCM to regulate intestinal E. coli against diseases was collected from PubMed, China National Knowledge Infrastructure (CNKI), and so on. The Plants of the World Online (https://wcsp.science.kew.org) and the Plant List (www.theplantlist.org) databases were used to provide the scientific names and species of plants.

RESULTS

Intestinal E. coli is a very important bacterium in respiratory infectious diseases that affects the respiratory system through immunity, the gut barrier and the metabolism. Many TCMs can inhibit the abundance of E. coli and regulate related immunity, the gut barrier and the metabolism to promote lung health.

CONCLUSION

TCM targeting intestinal E. coli and related immune, gut barrier, and metabolic dysfunction could be a potential therapy to promote the treatment and prognosis of respiratory infectious diseases.

The Function and Molecular Mechanism of Commensal Microbiome in Promoting Malignant Progression of Lung Cancer

The human commensal microbiome existing in an internal environment is relatively consistent with that of the host. The presence of bacterial dysbiosis, on the other hand, promptly results in the termination of this symbiotic association. The altered microbial structure in the lung may be responsible for the development of lung cancer by controlling the host's inflammatory response and influencing a variety of immunological pathways. More and more studies have pointed to the fact that the commensal microbiota plays a vital role in both the development of tumors and the body's response to lung cancer treatment. Microbiome dysbiosis, genotoxicity, virulence effect, and epigenetic dysregulations are some of the potential mechanisms that may lie behind the process of tumorigenesis that is mediated by microbiome. Other potential mechanisms include regulating host immune activity through a variety of pathogenic factors, dysregulating host metabolism as a result of microbiome alterations, and microbiome dysbiosis. In this historical overview, we go through some of the more recent mechanistic discoveries into the biological processes that are involved in lung cancer that are caused by bacteria. Without a question, obtaining a greater knowledge of the dynamic link between the lung microbiome and lung cancer has the potential to inspire the development of innovative early detection and customized treatment methods for lung cancer.

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.

Prediction of exacerbation frequency of AECOPD based on next-generation sequencing and its relationship with imbalance of lung and gut microbiota: a protocol of a prospective cohort study

INTRODUCTION

Patients with frequent acute exacerbation phenotype chronic obstructive pulmonary disease (AECOPD) have a higher hospitalisation rate than infrequent exacerbation, the disease progresses quickly and treatment is more difficult. At present, it is impossible to predict patients with COPD with frequent acute exacerbation phenotypes. The composition of the lower respiratory tract flora and the intestinal flora is closely related to AECOPD, but the specific association mechanism between them is not very clear. This study used metagenomic next-generation sequencing (mNGS) technology to explore the microbial characteristics of the intestinal tract and airways of patients with COPD, and analyse the correlation between the sequencing results and inflammatory factors, immune factors and nutritional factors.

METHODS AND ANALYSIS

This will be a prospective cohort study. We intend to recruit 152 patients with stable COPD. In the baseline, we will detect the participants' induced sputum and faecal flora through mNGS, and changes in blood immune levels, and the patient's condition is evaluated. Every 2 months, we will check the number of acute exacerbation through the phone range. After 12 months, we will check again the changes in the blood immune level, evaluate the patient's condition and count the number of episodes.

ETHICS AND DISSEMINATION

This study has been approved by the ethics committee of Guangdong Provincial Hospital of Traditional Chinese Medicine (approval number ZF2019-219-03). The results of the study will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (ChiCTR2000032870).

The Interaction Between Viruses and Intestinal Microbiota: A Review

As the main pathogen threatening human and animal health, viruses can affect the immunity and metabolism of bodies. There are innate microbial barriers in the digestive tract of the body to preserve the homeostasis of the animal body, which directly or indirectly influences the host defence against viral infection. Understanding the interaction between viruses and intestinal microbiota or probiotics is helpful to study the pathogenesis of diseases. Here, we review recent studies on the interaction mechanism between intestinal microbiota and viruses. The interaction can be divided into two aspects: inhibition of viral infection by microbiota and promotion of viral infection by microbiota. The treatment of viral infection by probiotics is summarized.

Role of lung and gut microbiota on lung cancer pathogenesis

BACKGROUND

Lung cancer is the leading cause of cancer-related deaths worldwide (Ferlay et al., Int J Cancer 136:E359-386, 2015). In addition, lung cancer is associated with the highest mortality among all cancer types (Wu et al., Exp Ther Med 16:3004-3010, 2018). Previous studies report that microbiota play an important role in lung cancer. Notably, changes in lung and gut microbiota, are associated with progression of lung cancer. Several studies report that lung and gut microbiome promote lung cancer initiation and development by modulating metabolic pathways, inhibiting the function of immune cells, and producing pro-inflammatory factors. In addition, some factors such as microbiota dysbiosis, affect production of bacteriotoxins, genotoxicity and virulence effect, therefore, they play a key role in cancer progression. These findings imply that lung and gut microbiome are potential markers and targets for lung cancer. However, the role of microbiota in development and progression of lung cancer has not been fully explored.

PURPOSE

The aim of this study was to systemically review recent research findings on relationship of lung and gut microbiota with lung cancer. In addition, we explored gut-lung axis and potential mechanisms of lung and gut microbiota in modulating lung cancer progression.

CONCLUSION

Pulmonary and intestinal flora influence the occurrence, development, treatment and prognosis of lung cancer, and will provide novel strategies for prevention, diagnosis, and treatment of lung cancer.

Gut Microbiota, in the Halfway between Nutrition and Lung Function

The gut microbiota is often mentioned as a “forgotten organ” or “metabolic organ”, given its profound impact on host physiology, metabolism, immune function and nutrition. A healthy diet is undoubtedly a major contributor for promoting a “good” microbial community that turns out to be crucial for a fine-tuned symbiotic relationship with the host. Both microbial-derived components and produced metabolites elicit the activation of downstream cascades capable to modulate both local and systemic immune responses. A balance between host and gut microbiota is crucial to keep a healthy intestinal barrier and an optimal immune homeostasis, thus contributing to prevent disease occurrence. How dietary habits can impact gut microbiota and, ultimately, host immunity in health and disease has been the subject of intense study, especially with regard to metabolic diseases. Only recently, these links have started to be explored in relation to lung diseases. The objective of this review is to address the current knowledge on how diet affects gut microbiota and how it acts on lung function. As the immune system seems to be the key player in the cross-talk between diet, gut microbiota and the lungs, involved immune interactions are discussed. There are key nutrients that, when present in our diet, help in gut homeostasis and lead to a healthier lifestyle, even ameliorating chronic diseases. Thus, with this review we hope to incite the scientific community interest to use diet as a valuable non-pharmacological addition to lung diseases management. First, we talk about the intestinal microbiota and interactions through the intestinal barrier for a better understanding of the following sections, which are the main focus of this article: the way diet impacts the intestinal microbiota and the immune interactions of the gut–lung axis that can explain the impact of diet, a key modifiable factor influencing the gut microbiota in several lung diseases.

The Potential Role of Probiotics in Protection against Influenza a Virus Infection in Mice

Influenza A virus induces severe respiratory tract infection and results in a serious global health problem. Influenza infection disturbs the cross-talk connection between lung and gut. Probiotic treatment can inhibit influenza virus infection; however, the mechanism remains to be explored. The mice received Lactobacillus mucosae 1025, Bifidobacterium breve CCFM1026, and their mixture MIX for 19 days. Effects of probiotics on clinical symptoms, immune responses, and gut microbial alteration were evaluated. L. mucosae 1025 and MIX significantly reduced the loss of body weight, pathological symptoms, and viral loading. B. breve CCFM1026 significantly reduced the proportion of neutrophils and increased lymphocytes, the expressions of TLR7, MyD88, TRAF6, and TNF-α to restore the immune disorders. MIX increased the antiviral protein MxA expression, the relative abundances of Lactobacillus, Mucispirillum, Adlercreutzia, Bifidobacterium, and further regulated SCFA metabolism resulting in an enhancement of butyrate. The correlation analysis revealed that the butyrate was positively related to MxA expression (p < 0.001) but was negatively related to viral loading (p < 0.05). The results implied the possible antiviral mechanisms that MIX decreased viral loading and increased the antiviral protein MxA expression, which was closely associated with the increased butyrate production resulting from gut microbial alteration.

Gut Microbiota: the Emerging Link to Lung Homeostasis and Disease

The gut microbiota plays a crucial role in the development of the immune system and confers benefits or disease susceptibility to the host. Emerging studies have indicated the gut microbiota could affect pulmonary health and disease through cross talk between the gut microbiota and the lungs. Gut microbiota dysbiosis could lead to acute or chronic lung disease, such as asthma, tuberculosis, and lung cancer. In addition, the composition of the gut microbiota may be associated with different lung diseases, the prevalence of which also varies by age. Modulation of the gut microbiota through short-chain fatty acids, probiotics, and micronutrients may present potential therapeutic strategies to protect against lung diseases. In this review, we will provide an overview of the cross-talk between the gut microbiota and the lungs, as well as elucidate the underlying pathogenesis and/or potential therapeutic strategies of some lung diseases from the point of view of the gut microbiota.

The Intestinal Microbiota Plays as a Protective Regulator Against Radiation Pneumonitis

Radiation pneumonitis is a common complication of thoracic irradiation for lung cancer patients. The healthy gut microbiota plays an important role in the local mucosal defense process as well as pulmonary immunomodulation of the host. However, the effect of the intestinal microbiota on radiation pneumonitis is not well understood. Here we studied how the intestinal microbiota affected the host response to radiation pneumonitis. C57BL/6 mice were administered antibiotics to induce disequilibrium in the gut microbiota, and subsequently irradiated. We found that the intestinal microbiota served as a protective mediator against radiation pneumonitis, as indicated by decreased body weight and increased mortality in antibiotic-treated mice. In mice with gut microbiota disequilibrium, more serious pathological lung damage was observed at two and four weeks postirradiation. Fecal microbiota transplantation into irradiated mice led to improvement from radiation-induced inflammation two weeks postirradiation. High-throughput sequencing of murine feces displayed conversion of flora diversity, bacterial composition and community structure in the absence of normal intestinal flora. We filtered the potentially important species among the gut microbiota and considered that the tissue-type plasminogen activator might be involved in the inflammatory process. This study reveals that the gut microbiota functions as a protective regulator against radiation pneumonitis. Additionally, fecal microbiota transplantation was shown to alleviate lung injury in the irradiated model. The protective role of the healthy gut microbiota and the utilization of the gut-lung axis show potential for innovative therapeutic strategies in radiation-induced lung injury.

Microbiome dysbiosis in lung cancer: from composition to therapy

The correlations between microbiota dysbiosis and cancer have gained extensive attention and been widely explored. As a leading cancer diagnosis worldwide, lung cancer poses a great threat to human health. The healthy human lungs are consistently exposed to external environment and harbor a specific pattern of microbiota, sharing many key pathological and physiological characteristics with the intestinal tract. Although previous findings uncovered the critical roles of microbiota in tumorigenesis and response to anticancer therapy, most of them were focused on the intestinal microbiota rather than lung microbiota. Notably, the considerable functions of microbiota in maintaining lung homeostasis should not be neglected as the microbiome dysbiosis may promote tumor development and progression through production of cytokines and toxins and multiple other pathways. Despite the fact that increasing studies have revealed the effect of microbiome on the induction of lung cancer and different disease status, the underlying mechanisms and potential therapeutic strategies remained unclear. Herein, we summarized the recent progresses about microbiome in lung cancer and further discussed the role of microbial communities in promoting lung cancer progression and the current status of therapeutic approaches targeting microbiome to alleviate and even cure lung cancer.

The Gut Microbiota and Respiratory Diseases: New Evidence

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

Intestinal microbiota disruption limits the isoniazid mediated clearance of Mycobacterium tuberculosis in mice

Tuberculosis (TB) continues to remain a global threat due to the emergence of drug-resistant Mycobacterium tuberculosis (Mtb) strains and toxicity associated with TB drugs. Intestinal microbiota has been reported to affect the host response to immunotherapy and drugs. However, how it affects the potency of first-line TB drug isoniazid (INH) is largely unknown. Here, we examined the impact of gut microbial dysbiosis on INH efficiency to kill Mtb. In this study, we employed in vivo mouse model, pretreated with broad-spectrum antibiotics (Abx) cocktail to disrupt their intestinal microbial population prior to Mtb infection and subsequent INH therapy. We demonstrated that microbiota disruption results in the impairment of INH-mediated Mtb clearance, and aggravated TB-associated tissue pathology. Further, it suppressed the innate immunity and reduced CD4 T-cell response against Mtb. Interestingly, a distinct shift of gut microbial profile was noted with abundance of Enterococcus and reduction of Lactobacillus and Bifidobacterium population. Our results show that the intestinal microbiota is crucial determinant in efficacy of INH to kill Mtb and impacts the host immune response against infection. This work provides an intriguing insight into the potential links between host gut microbiota and potency of INH.

TLR4 deficiency reduces pulmonary resistance to Streptococcus pneumoniae in gut microbiota-disrupted mice

Streptococcus pneumoniae is a clinically important pathogen responsible for significant morbidity and mortality worldwide. Disruption of the host gut microbiota by antibiotics reduces the pulmonary resistance to S. pneumoniae. The aim of our study was to determine the potential role of TLR4 in the reduced pulmonary resistance to S. pneumoniae following gut microbiota disruption. Wild-type and TLR4-deficient mice were given broad-spectrum antibiotics for 3 weeks by oral gavage to disrupt the gut microbiota, and subsequently inoculated intra-nasally with S. pneumoniae. The extent of the decline in pulmonary resistance in both animal groups was evaluated in terms of the overall survival and pulmonary bacterial clearance. Both survival and pulmonary clearance of S. pneumoniae were lower in the TLR4-deficient mice with disrupted gut microbiota, compared to their intestinally healthy counterparts after pneumococcal infection. However, the degree of decline was much lower in the TLR4-deficient mice compared to the wild-type mice. Our findings indicate that impaired TLR4 function might be the basis of the reduced pulmonary resistance to S. pneumoniae caused by gut microbiota disruption.

Characterisation of gut, lung, and upper airways microbiota in patients with non-small cell lung carcinoma: Study protocol for case-control observational trial

BACKGROUND

Several studies have confirmed the important role of the gut microbiota in the regulation of immune functions and its correlation with different diseases, including cancer. While brain-gut and liver-gut axes have already been demonstrated, the existence of a lung-gut axis has been suggested more recently, with the idea that changes in the gut microbiota could affect the lung microbiota, and vice versa. Likewise, the close connection between gut microbiota and cancer of proximal sites (intestines, kidneys, liver, etc.) is already well established. However, little is known whether there is a similar relation when looking at world's number one cause of death from cancer-lung cancer.

OBJECTIVE

Firstly, this study aims to characterise the gut, lung, and upper airways (UAs) microbiota in patients with non-small cell lung cancer (NSCLC) treated with surgery or neoadjuvant chemotherapy plus surgery. Secondly, it aims to evaluate a chemotherapy effect on site-specific microbiota and its influence on immune profile. To our knowledge, this is the 1st study that will analyse multi-site microbiota in NSCLC patients along with site-specific immune response.

METHODS

The study is a case-controlled observational trial. Forty NSCLC patients will be divided into 2 groups depending on their anamnesis: Pchir, patients eligible for surgery, or Pct-chir, patients eligible for neoadjuvant chemotherapy plus surgery. Composition of the UAs (saliva), gut (faeces), and lung microbiota (from broncho-alveolar lavage fluid (BALF) and 3 lung pieces: "healthy" tissue distal to tumour, peritumoural tissue and tumour itself) will be analysed in both groups. Immune properties will be evaluated on the local (evaluation of the tumour immune cell infiltrate, tumour classification and properties, immune cell phenotyping in BALF; human neutrophil protein (HNP) 1-3, β-defensin 2, and calprotectin in faeces) and systemic level (blood cytokine and immune cell profile). Short-chain fatty acids (SCFAs) (major products of bacterial fermentation with an effect on immune system) will be dosed in faecal samples. Other factors such as nutrition and smoking status will be recorded for each patient. We hypothesise that smoking status and tumour type/grade will be major factors influencing both microbiota and immune/inflammatory profile of all sampling sites. Furthermore, due to non-selectivity, the same effect is expected from chemotherapy.

Epithelial MHC Class II Expression and Its Role in Antigen Presentation in the Gastrointestinal and Respiratory Tracts

As the primary barrier between an organism and its environment, epithelial cells are well-positioned to regulate tolerance while preserving immunity against pathogens. Class II major histocompatibility complex molecules (MHC class II) are highly expressed on the surface of epithelial cells (ECs) in both the lung and intestine, although the functional consequences of this expression are not fully understood. Here, we summarize current information regarding the interactions that regulate the expression of EC MHC class II in health and disease. We then evaluate the potential role of EC as non-professional antigen presenting cells. Finally, we explore future areas of study and the potential contribution of epithelial surfaces to gut-lung crosstalk.

The Role of Pulmonary and Systemic Immunosenescence in Acute Lung Injury

Acute lung injury (ALI) is associated with increased morbidity and mortality in the elderly (> 65 years), but the knowledge about origin and effects of immunosenescence in ALI is limited. Here, we investigated the immune response at pulmonary, systemic and cellular level in young (2-3 months) and old (18-19 months) C57BL/6J mice to localize and characterize effects of immunosenescence in ALI. ALI was induced by intranasal lipopolysaccharide (LPS) application and the animals were sacrificed 24 or 72 h later. Pulmonary inflammation was investigated by analyzing histopathology, bronchoalveolar lavage fluid (BALF) cytometry and cytokine expression. Systemic serum cytokine expression, spleen lymphocyte populations and the gut microbiome were analyzed, as well as activation of alveolar and bone marrow derived macrophages (BMDM) in vitro. Pulmonary pathology of ALI was more severe in old compared with young mice. Old mice showed significantly more inflammatory cells and pro-inflammatory cyto- or chemokines (TNFα, IL-6, MCP-1, CXCL1, MIP-1α) in the BALF, but a delayed expression of cytokines associated with activation of adaptive immunity and microbial elimination (IL-12 and IFNγ). Alveolar macrophages, but not BMDM, of old mice showed greater activation after in vivo and in vitro stimulation with LPS. No systemic enhanced pro-inflammatory cytokine response was detected in old animals after LPS exposure, but a delayed expression of IL-12 and IFNγ. Furthermore, old mice had less CD8⁺ T-cells and NK cells and more regulatory T-cells in the spleen compared with young mice and a distinct gut microbiome structure. The results of our study show an increased alveolar macrophage activation and pro-inflammatory signaling in the lungs, but not systemically, suggesting a key role of senescent alveolar macrophages in ALI. A decrease in stimulators of adaptive immunity with advancing age might further promote the susceptibility to a worse prognosis in ALI in elderly.

Houttuynia cordata polysaccharides ameliorate pneumonia severity and intestinal injury in mice with influenza virus infection

ETHNOPHARMACOLOGICAL RELEVANCE

Hottuynia cordata is an important traditional Chinese medicine for the treatment of respiratory diseases including bacterial and viral infections. Polysaccharides isolated from Houttuynia cordata (HCP), as its main ingredients, have been demonstrated to ameliorate the LPS-induced acute lung injury in mice. The study aimed to determine the protective effects of HCP on multiple organ injury in influenza A virus (IAV) H1N1 infected mice and its primary mechanisms in anti-inflammation and immune regulation.

MATERIALS AND METHODS

Mice were inoculated with IAV H1N1 and then treated with 20 or 40 mg/kg/d of HCP for survival test and acute lung-gut injury test.

RESULTS

The treatment with HCP resulted in an increase in the survival rate of H1N1 infected mice and the protection from lung and intestine injury, accompanied with the reduced virus replication. HCP markedly decreased the concentration of pulmonary proinflammatory cytokines/chemokines and the number of intestinal goblet cells, and strengthened the intestinal physical and immune barrier, according to the increase of sIgA and tight junction protein (ZO-1) in intestine. At the same time, the inhibition of inflammation in lung and gut was related to the suppressing of the expression of TLR4 and p-NFκB p65 in lung.

CONCLUSIONS

These results indicated that HCP ameliorated lung and intestine injury induced by IAV attack. The mechanisms were associated with inhibition of inflammation, protection of intestinal barrier and regulation of mucosal immunity, which may be related to the regulation of gut-lung axis. As an alternative medicine, HCP may have clinical potential to treat IAV infection in human beings.

Desired Turbulence? Gut-Lung Axis, Immunity, and Lung Cancer

The microbiota includes different microorganisms consisting of bacteria, fungi, viruses, and protozoa distributed over many human body surfaces including the skin, vagina, gut, and airways, with the highest density found in the intestine. The gut microbiota strongly influences our metabolic, endocrine, and immune systems, as well as both the peripheral and central nervous systems. Recently, a dialogue between the gut and lung microbiota has been discovered, suggesting that changes in one compartment could impact the other compartment, whether in relation to microbial composition or function. Further, this bidirectional axis is evidenced in an, either beneficial or malignant, altered immune response in one compartment following changes in the other compartment. Stimulation of the immune system arises from the microbial cells themselves, but also from their metabolites. It can be either direct or mediated by stimulated immune cells in one site impacting the other site. Additionally, this interaction may lead to immunological boost, assisting the innate immune system in its antitumour response. Thus, this review offers an insight into the composition of these sites, the gut and the lung, their role in shaping the immune system, and, finally, their role in the response to lung cancer.

Does probiotic supplementation affect pulmonary exacerbation and intestinal inflammation in cystic fibrosis: a systematic review of randomized clinical trials

BACKGROUND

Patients with cystic fibrosis (CF) usually have abnormal intestinal microbiota due to massive exposure to antibiotics. Probiotics could modify the gut microbiota and hence may affect CF management. So the aim of present systematic review was evaluation of the efficacy and safety of probiotic supplementation for the management of cystic fibrosis.

DATA SOURCES

We searched PubMed, Science Direct, Google Scholar, Springer Cochrane Library Databases until January 2016 for randomized controlled trials (RCTs) performed in pediatric or adult populations related to the study aim. Key words were selected based on Mesh terms. Based on the Critical Appraisal Skills Programme checklist, eligibility of included articles was evaluated.

RESULTS

Five studies included in this review represent 188 participants with a follow up period ranging from 1 month to 6 months. The results of the included studies supporting the use of probiotics in management of pulmonary exacerbation and intestinal calprotectin in patients with cystic fibrosis. However the level of evidence was limited.

CONCLUSIONS

The lack of high quality RCTs makes it impossible to support a general recommendation about the use of probiotics in the treatment of CF pulmonary exacerbation and intestinal inflammation.

Airway Microbiota and the Implications of Dysbiosis in Asthma

The mucosal surfaces of the human body are typically colonized by polymicrobial communities seeded in infancy and are continuously shaped by environmental exposures. These communities interact with the mucosal immune system to maintain homeostasis in health, but perturbations in their composition and function are associated with lower airway diseases, including asthma, a developmental and heterogeneous chronic disease with various degrees and types of airway inflammation. This review will summarize recent studies examining airway microbiota dysbioses associated with asthma and their relationship with the pathophysiology of this disease.

Lung-gut cross-talk: evidence, mechanisms and implications for the mucosal inflammatory diseases

The mucosal immune system (including airway, intestinal, oral and cervical epithelium) is an integrated network of tissues, cells and effector molecules that protect the host from environmental insults and infections at mucous membrane surfaces. Dysregulation of immunity at mucosal surfaces is thought to be responsible for the alarming global increase in mucosal inflammatory diseases such as those affecting the gastrointestinal (Crohn's disease, ulcerative colitis and irritable bowel syndrome) and respiratory (asthma, allergy and chronic obstructive pulmonary disorder) system. Although immune regulation has been well-studied in isolated mucosal sites, the extent of the immune interaction between anatomically distant mucosal sites has been mostly circumstantial and the focus of much debate. With novel technology and more precise tools to examine histological and functional changes in tissues, today there is increased appreciation of the 'common mucosal immunological system' originally proposed by Bienenstock nearly 40 years ago. Evidence is amounting which shows that stimulation of one mucosal compartment can directly and significantly impact distant mucosal site, however the mechanisms are unknown. Today, we are only beginning to understand the complexity of relationships and communications that exist between different mucosal compartments. A holistic approach to studying the mucosal immune system as an integrated global organ is imperative for future advances in understanding mucosal immunology and for future treatment of chronic diseases. In this review, we particularly focus on the latest evidence and the mechanisms operational in driving the lung-gut cross-talk.

Gut-lung axis: The microbial contributions and clinical implications

Gut microbiota interacts with host immune system in ways that influence the development of disease. Advances in respiratory immune system also broaden our knowledge of the interaction between host and microbiome in the lung. Increasing evidence indicated the intimate relationship between the gastrointestinal tract and respiratory tract. Exacerbations of chronic gut and lung disease have been shown to share key conceptual features with the disorder and dysregulation of the microbial ecosystem. In this review, we discuss the impact of gut and lung microbiota on disease exacerbation and progression, and the recent understanding of the immunological link between the gut and the lung, the gut-lung axis.

The Gut-Lung Axis in Respiratory Disease

Host-microorganism interactions shape local cell functionality, immune responses, and can influence disease development. Evidence indicates that the impact of host-microbe interactions reaches far beyond the local environment, thus influencing responses in peripheral tissues. There is a vital cross-talk between the mucosal tissues of our body, as exemplified by intestinal complications during respiratory disease and vice versa. Although, mechanistically, this phenomenon remains poorly defined, the existence of the gut-lung axis and its implications in both health and disease could be profoundly important for both disease etiology and treatment. In this review, we highlight how changes in the intestinal microenvironment, with a particular focus on the intestinal microbiota, impact upon respiratory disease.

Microbiome Changes during Tuberculosis and Antituberculous Therapy

The critical role of commensal microbiota in the human body has been increasingly recognized, and our understanding of its implications in human health and disease has expanded rapidly. The lower respiratory tract contains diverse communities of microbes known as lung microbiota, which are present in healthy individuals and in individuals with respiratory diseases. The dysbiosis of the airway microbiota in pulmonary tuberculosis (TB) may play a role in the pathophysiological processes associated with TB disease. Recent studies of the lung microbiome have pointed out changes in lung microbial communities associated with TB and other lung diseases and have also begun to elucidate the profound effects that antituberculous drug therapy can have on the human lung microbiome composition. In this review, the potential role of the human microbiome in TB pathogenesis and the changes in the human microbiome with Mycobacterium tuberculosis infection and TB therapy are presented and discussed.

Lung Ischemia-Reperfusion is a Sterile Inflammatory Process Influenced by Commensal Microbiota in Mice

Lung ischemia-reperfusion (IR) complicates numerous clinical processes, such as cardiac arrest, transplantation, and major trauma. These conditions generate sterile inflammation, which can cause or worsen acute lung injury. We previously reported that lung and systemic inflammation in a mouse model of ventilated lung IR depends on Toll-like receptor 4 (TLR-4) signaling and the presence of alveolar macrophages. Here, we tested the hypothesis that the intestinal microbiome has a role in influencing the inflammatory response to lung IR. Lung IR was created in intubated mechanically ventilated mice via reversible left pulmonary artery occlusion followed by reperfusion. Inflammatory markers and histology were tracked during varying periods of reperfusion (from 1 to 24 h). Separate groups of mice were given intestinally localized antibiotics for 8 to 10 weeks and then were subjected to left lung IR and analysis of lungs and plasma for markers of inflammation. Alveolar macrophages from antibiotic-treated or control mice were tested ex vivo for inflammatory responses to bacterial TLR agonists, namely, lipopolysaccharide and Pam3Cys. We found that inflammation generated by left lung IR was rapid in onset and dissipated within 12 to 24 h. Treatment of mice with intestinally localized antibiotics was associated with a marked attenuation of circulating and lung inflammatory markers as well as reduced histologic evidence of infiltrating cells and edema in the lung after IR. Alveolar macrophages from antibiotic-treated mice produced less cytokines ex vivo when stimulated with TLR agonists as compared with those from control mice. Our data indicate that the inflammatory response induced by nonhypoxic lung IR is transient and is strongly influenced by intestinal microbiota. Furthermore, these data suggest that the intestinal microbiome could potentially be manipulated to attenuate the post-IR pulmonary inflammatory response.

Alterations of the Murine Gut Microbiome with Age and Allergic Airway Disease

The gut microbiota plays an important role in the development of asthma. With advanced age the microbiome and the immune system are changing and, currently, little is known about how these two factors contribute to the development of allergic asthma in the elderly. In this study we investigated the associations between the intestinal microbiome and allergic airway disease in young and old mice that were sensitized and challenged with house dust mite (HDM). After challenge, the animals were sacrificed, blood serum was collected for cytokine analysis, and the lungs were processed for histopathology. Fecal pellets were excised from the colon and subjected to 16S rRNA analysis. The microbial community structure changed with age and allergy development, where alterations in fecal communities from young to old mice resembled those after HDM challenge. Allergic mice had induced serum levels of IL-17A and old mice developed a greater allergic airway response compared to young mice. This study demonstrates that the intestinal bacterial community structure differs with age, possibly contributing to the exaggerated pulmonary inflammatory response in old mice. Furthermore, our results show that the composition of the gut microbiota changes with pulmonary allergy, indicating bidirectional gut-lung communications.

Activation of Toll-like receptors by intestinal microflora reduces radiation-induced DNA damage in mice

Activation of Toll-like receptors (TLRs) signaling by intestinal microflora-derived bacterial products plays a key role in injury defence for the host. We investigated the role of TLRs activated by intestinal microflora in radiation-induced DNA damage in mice. We analyzed DNA damage induced by 2Gy γ-ray radiation in an intestinal commensal bacteria-depleted mouse model (CD group), in which TLRs (TLR2/6, TLR4 and TLR5) ligand levels in serum were reduced. Chromosomal aberrations were measured in bone marrow cells and peripheral blood leukocyte comet assays were performed. DNA damage was increased in the CD group compared with the control group. Treatment of mice with TLR agonists (CBLB502, LPS and lipopeptide) 1h before radiation resulted in a significant decrease in DNA damage. Genes induced by TLR5 activation were analyzed; activation of TLRs regulated the expression of Gadd45b, Sod2, and Rad21, which are involved in DNA damage repair. In summary, our data indicate that TLRs activation by intestinal microflora reduces DNA damage induced by radiation and regulates expression of several DNA repair genes.

The clinical significance of the gut microbiota in cystic fibrosis and the potential for dietary therapies

Cystic fibrosis (CF) is characterised by many comorbidities related to aberrant mucosa and chronic inflammation in the respiratory and digestive systems. The intestinal mucosa serves as the primary interface between the gut microbiota and endocrine, neural and immune systems. There is emerging evidence that aberrant intestinal mucosa in CF may associate with an altered gut microbiota. Compared to healthy subjects, the overall bacterial abundance and species richness seems to be reduced in CF, accompanied by a trend in suppression of Firmicutes and Bacteroidetes spp. and an augmentation of potentially pathogenic species. There is also some concordance of gut and respiratory microbiotas in CF infants over time. The clinical significance of these observations awaits investigation. The gut microbiota have some potential in CF management by affecting inflammatory and immune responses, and influencing aberrant mucosa. As an important modifiable factor, diet therapies such as probiotics and prebiotics have shown initial promise in improving CF related conditions associated with chronic inflammation. More studies are needed to confirm this, as well as the efficacy of other dietary strategies such as modulating dietary fat and indigestible carbohydrate. Similarly, dietary modification of gut microbiota to optimise nutritional status in CF may be feasible, although more CF-specific studies are warranted.