Faecal microbial transfer and complex carbohydrates mediate protection against COPD.

OBJECTIVE: Chronic obstructive pulmonary disease (COPD) is a major cause of global illness and death, most commonly caused by cigarette smoke. The mechanisms of pathogenesis remain poorly understood, limiting the development of effective therapies. The gastrointestinal microbiome has been implicated in chronic lung diseases via the gut-lung axis, but its role is unclear. DESIGN: Using an in vivo mouse model of cigarette smoke (CS)-induced COPD and faecal microbial transfer (FMT), we characterised the faecal microbiota using metagenomics, proteomics and metabolomics. Findings were correlated with airway and systemic inflammation, lung and gut histopathology and lung function. Complex carbohydrates were assessed in mice using a high resistant starch diet, and in 16 patients with COPD using a randomised, double-blind, placebo-controlled pilot study of inulin supplementation. RESULTS: FMT alleviated hallmark features of COPD (inflammation, alveolar destruction, impaired lung function), gastrointestinal pathology and systemic immune changes. Protective effects were additive to smoking cessation, and transfer of CS-associated microbiota after antibiotic-induced microbiome depletion was sufficient to increase lung inflammation while suppressing colonic immunity in the absence of CS exposure. Disease features correlated with the relative abundance of Muribaculaceae, Desulfovibrionaceae and Lachnospiraceae family members. Proteomics and metabolomics identified downregulation of glucose and starch metabolism in CS-associated microbiota, and supplementation of mice or human patients with complex carbohydrates improved disease outcomes. CONCLUSION: The gut microbiome contributes to COPD pathogenesis and can be targeted therapeutically.

Probiotic Bifidobacterium longum subsp. longum Protects against Cigarette Smoke-Induced Inflammation in Mice.

Bifidobacterium are prominent gut commensals that produce the short-chain fatty acid (SCFA) acetate, and they are often used as probiotics. Connections between the gut and the lung, termed the gut-lung axis, are regulated by the microbiome. The gut-lung axis is increasingly implicated in cigarette smoke-induced diseases, and cigarette smoke exposure has been associated with depletion of Bifidobacterium species. In this study, we assessed the impact of acetate-producing Bifidobacterium longum subsp. longum (WT) and a mutant strain with an impaired acetate production capacity (MUT) on cigarette smoke-induced inflammation. The mice were treated with WT or MUT B. longum subsp. longum and exposed to cigarette smoke for 8 weeks before assessments of lung inflammation, lung tissue gene expression and cecal SCFAs were performed. Both strains of B. longum subsp. longum reduced lung inflammation, inflammatory cytokine expression and adhesion factor expression and alleviated cigarette smoke-induced depletion in caecum butyrate. Thus, the probiotic administration of B. longum subsp. longum, irrespective of its acetate-producing capacity, alleviated cigarette smoke-induced inflammation and the depletion of cecal butyrate levels.

E-cigarettes induce toxicity comparable to tobacco cigarettes in airway epithelium from patients with COPD.

BACKGROUND: The health effects of e-cigarettes in patients with pre-existing lung disease are unknown. The aim of this study was to investigate whether aerosols from a fourth-generation e-cigarette produces similar in-vitro cytotoxic, DNA damage and inflammatory effects on bronchial epithelial cells (BECs) from patients with COPD, as cigarette smoke. METHODS: BECs from patients with COPD who underwent surgery for lung cancer and comparator (immortalised 16HBE) cells were grown at air liquid interface (ALI). BECs were exposed to aerosols from a JUUL® e-cigarette (Virginia Tobacco and Menthol pods at 5% nicotine strength) or reference 3R4F cigarette for 30 min at ALI. Cell cytotoxicity, DNA damage and inflammation were measured. RESULTS: In response to the Virginia Tobacco and Menthol flavoured e-cigarette aerosols, COPD BECs showed comparable LDH release (cell cytotoxicity, p = 0.59, p = 0.67 respectively), DNA damage (p = 0.41, p = 0.51) and inflammation (IL-8, p = 0.20, p = 0.89 and IL-6, p = 0.24, p = 0.93), to cigarette smoke. 16HBE cells also showed comparable cellular responses to cigarette smoke. CONCLUSION: In airway cells from patients with COPD, aerosols from a fourth-generation e-cigarette were associated with similar toxicity to cigarette smoke. These results have potential implications for the safety of e-cigarette use in patients with lung disease.

Disease-associated gut microbiome and metabolome changes in patients with chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is the third commonest cause of death globally, and manifests as a progressive inflammatory lung disease with no curative treatment. The lung microbiome contributes to COPD progression, but the function of the gut microbiome remains unclear. Here we examine the faecal microbiome and metabolome of COPD patients and healthy controls, finding 146 bacterial species differing between the two groups. Several species, including Streptococcus sp000187445, Streptococcus vestibularis and multiple members of the family Lachnospiraceae, also correlate with reduced lung function. Untargeted metabolomics identifies a COPD signature comprising 46% lipid, 20% xenobiotic and 20% amino acid related metabolites. Furthermore, we describe a disease-associated network connecting Streptococcus parasanguinis_B with COPD-associated metabolites, including N-acetylglutamate and its analogue N-carbamoylglutamate. While correlative, our results suggest that the faecal microbiome and metabolome of COPD patients are distinct from those of healthy individuals, and may thus aid in the search for biomarkers for COPD.

Role of Lung Microbiome in Innate Immune Response Associated With Chronic Lung Diseases.

Respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), lung fibrosis, and lung cancer, pose a huge socio-economic burden on society and are one of the leading causes of death worldwide. In the past, culture-dependent techniques could not detect bacteria in the lungs, therefore the lungs were considered a sterile environment. However, the development of culture-independent techniques, particularly 16S rRNA sequencing, allowed for the detection of commensal microbes in the lung and with further investigation, their roles in disease have since emerged. In healthy individuals, the predominant commensal microbes are of phylum Firmicutes and Bacteroidetes, including those of the genera Veillonella and Prevotella. In contrast, pathogenic microbes (Haemophilus, Streptococcus, Klebsiella, Pseudomonas) are often associated with lung diseases. There is growing evidence that microbial metabolites, structural components, and toxins from pathogenic and opportunistic bacteria have the capacity to stimulate both innate and adaptive immune responses, and therefore can contribute to the pathogenesis of lung diseases. Here we review the multiple mechanisms that are altered by pathogenic microbiomes in asthma, COPD, lung cancer, and lung fibrosis. Furthermore, we focus on the recent exciting advancements in therapies that can be used to restore altered microbiomes in the lungs.

COPD and the gut-lung axis: the therapeutic potential of fibre.

Current management strategies for chronic obstructive pulmonary disease (COPD) incorporate a step-wise, multidisciplinary approach to effectively manage patient symptoms and prevent disease progression. However, there has been limited advancement in therapies to address the underlying cause of COPD pathogenesis. Recent research has established the link between the lungs and the gut-the gut-lung axis -and the gut microbiome is a major component. The gut microbiome is likely perturbed in COPD, contributing to chronic inflammation. Diet is a readily modifiable factor and the diet of COPD patients is often deficient in nutrients such as fibre. The metabolism of dietary fibre by gut microbiomes produces anti-inflammatory short chain fatty acid (SCFAs), which could protect against inflammation in the lungs. By addressing the 'fibre gap' in the diet of COPD patients, this targeted dietary intervention may reduce inflammation, both systemically and in the airways, and value-add to the paradigm shift in respiratory medicine, from reactive to personalised and participatory medicine.

Nutritional support in chronic obstructive pulmonary disease (COPD): an evidence update.

Chronic obstructive pulmonary disease (COPD) primarily affects the lungs but due to the accompanying chronic systematic inflammation and the symptoms associated with the disease there are many extrapulmonary effects which include complex physical and metabolic adaptations. These changes have been associated with reduced exercise capacity, increased nutritional requirements, altered metabolic processes and compromised nutritional intake. As a result, nutritional depletion in COPD is multi-faceted and can involve imbalances of energy (weight loss), protein (sarcopenia), and periods of markedly increased inflammation (pulmonary cachexia) which can increase nutritional losses. As a result, depletion of both fat-mass (FM) and fat-free mass (FFM) can occur. There is good evidence that nutritional support, in the form of oral nutritional supplements (ONS), can overcome energy and protein imbalances resulting in improved nutritional status and functional capacity. However, in order to treat the aetiology of sarcopenia, frailty and cachexia, it is likely that targeted multi-modal interventions are required to address energy and protein imbalance, specific nutrient deficiencies, reduced androgens and targeted exercise training. Furthermore, interventions taking a disease-course approach, are likely to hold the key to effectively managing the common and costly problem of nutritional depletion in COPD.

The cytotoxic, inflammatory and oxidative potential of coconut oil-substituted diesel emissions on bronchial epithelial cells at an air-liquid interface.

Diesel emissions contain high levels of particulate matter (PM) which can have a severe effect on the airways. Diesel PM can be effectively reduced with the substitution of diesel fuel with a biofuel such as vegetable oil. Unfortunately, very little is known about the cellular effects of these alternative diesel emissions on the airways. The aim of this study was to test whether coconut oil substitution in diesel fuel reduces the adverse effect of diesel emission exposure on human bronchial epithelial cells. Human bronchial epithelial cells were cultured at air-liquid interface for 7 days and exposed to diesel engine emissions from conventional diesel fuel or diesel fuel blended with raw coconut oil at low (10%), moderate (15%) and high (20%) proportions. Cell viability, inflammation, antioxidant production and xenobiotic metabolism were measured. Compared to conventional diesel, low fractional coconut oil substitution (10% and 15%) reduced inflammation and increased antioxidant expression, whereas higher fractional coconut oil (20%) reduced cell viability and increased inflammation. Therefore, cellular responses after exposure to alternative diesel emission are dependent on fuel composition.

Primary human bronchial epithelial cell responses to diesel and biodiesel emissions at an air-liquid interface.

INTRODUCTION: Diesel emissions have a high level of particulate matter which can cause inflammation and oxidative stress in the airways. A strategy to reduce diesel particulate matter and the associated adverse effects is the use of biodiesels and fuel additives. However, very little is known about the biological effects of these alternative emissions. The aim of this study is to compare the effect of biodiesel and triacetin/biodiesel emissions on primary human bronchial epithelial cells (pHBECs) compared to diesel emissions. METHODS: pHBECs were exposed to diesel, biodiesel (20%, 50% and 100% biodiesel derived from coconut oil) and triacetin/biodiesel (4% and 10% triacetin) emissions for 30 min at air-liquid interface. Cell viability (cellular metabolism, cell death, CASP3 mRNA expression and BCL2 mRNA expression), inflammation (IL-8 and IL-6 secretion), antioxidant production (HO-1 mRNA expression) and xenobiotic metabolism (CYP1a1 mRNA expression) were measured. RESULTS: Biodiesel emissions (B50) reduced cell viability, and increased oxidative stress. Triacetin/biodiesel emissions (B90) decreased cell viability and increased antioxidant production, inflammation and xenobiotic metabolism. Biodiesel emissions (B100) reduced cell viability, and increased IL-8 secretion and xenobiotic metabolism. CONCLUSIONS: Biodiesel substitution in diesel fuel and triacetin substitution in biodiesel can increase the adverse effects of diesel emissions of pHBECs. Further studies of the effect of these diesel fuel alternatives on pHBECs are required.

The effect of diesel emission exposure on primary human bronchial epithelial cells from a COPD cohort: N-acetylcysteine as a potential protective intervention.

INTRODUCTION: Chronic obstructive pulmonary disease (COPD) will be the third leading cause of death world-wide by 2020. Prolonged exposure to particulate matter is associated with COPD progression and mortality. Diesel emissions are a major contributor to particulate matter pollution. In this study we test a therapeutic antioxidant, N-acetylcysteine (NAC), for its ability to protect bronchial epithelial cells (pHBECs) from patients with COPD from adverse effects of diesel emission exposure. METHODS: pHBECs from patients with or without COPD were cultured at air-liquid interface (ALI). Cells were exposed to diesel emissions for 30 min with or without 3-h post-exposure treatment with 5 mM N-acetylcysteine (NAC). Filtered laboratory air was tested as a negative control. Cell responses (cell viability, inflammation and oxidative stress) and gene expression profiles for intracellular and immune signaling were assessed. RESULTS: Diesel emissions exposure increased IL-8 secretion and production, antioxidant production, and cytochrome P450 1a1 (CYP1a1) mRNA expression and suppressed superoxide dismutase-1 (SOD1) mRNA expression in bronchial epithelial cells from COPD patients. Treatment with N-acetyl cysteine attenuated the suppression of SOD1. Nanostring gene expression profiling of the filtered air controls showed COPD epithelial cells have increased expression of MHC class II and an interferon signaling profile. CONCLUSIONS: This study indicates that bronchial epithelial cells from COPD patients may be vulnerable to diesel emission exposure due to reduced antioxidant capacity, and elevated CYP1a1 mRNA expression. NAC did not appear to offer protection. Future research will be needed to explore other means of recovering oxidant capacity in COPD airways.

Biomarkers of progression of chronic obstructive pulmonary disease (COPD).

Disease progression of chronic obstructive pulmonary disease (COPD) is variable, with some patients having a relatively stable course, while others suffer relentless progression leading to severe breathlessness, frequent acute exacerbations of COPD (AECOPD), respiratory failure and death. Radiological markers such as CT emphysema index, bronchiectasis and coronary artery calcification (CAC) have been linked with increased mortality in COPD patients. Molecular changes in lung tissue reflect alterations in lung pathology that occur with disease progression; however, lung tissue is not routinely accessible. Cell counts (including neutrophils) and mediators in induced sputum have been associated with lung function and risk of exacerbations. Examples of peripheral blood biological markers (biomarkers) include those associated with lung function (reduced CC-16), emphysema severity (increased adiponectin, reduced sRAGE), exacerbations and mortality [increased CRP, fibrinogen, leukocyte count, IL-6, IL-8, and tumor necrosis factor α (TNF-α)] including increased YKL-40 with mortality. Emerging approaches to discovering markers of gene-environment interaction include exhaled breath analysis [volatile organic compounds (VOCs), exhaled breath condensate], cellular and systemic responses to exposure to air pollution, alterations in the lung microbiome, and biomarkers of lung ageing such as telomere length shortening and reduced levels of sirtuins. Overcoming methodological challenges in sampling and quality control will enable more robust yet easily accessible biomarkers to be developed and qualified, in order to optimise personalised medicine in patients with COPD.

Personalizing and targeting therapy for COPD: the role of molecular and clinical biomarkers.

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease characterized by persistent airflow limitation. It is the third leading cause of death worldwide, and there are currently no curative strategies for this disease. Many factors contribute to COPD susceptibility, progression and exacerbations. These include cigarette smoking, environmental and occupational pollutants, respiratory infections and comorbidities. As the clinical phenotypes of COPD are so variable, it has been difficult to devise an individualized treatment plan for patients with this complex chronic disease. This review will highlight how potential clinical, inflammatory, genomic and epigenomic biomarkers for COPD could be used to personalize treatment, leading to improved disease management and prevention for our patients.