Glucose and pyruvate metabolism in severe chronic obstructive pulmonary disease

Imbalanced and Unchecked: The Role of Metal Dyshomeostasis in Driving COPD Progression

Chronic obstructive pulmonary disease (COPD) is a chronic respiratory condition characterized by persistent inflammation and oxidative stress, which ultimately leads to progressive restriction of airflow. Extensive research findings have cogently suggested that the dysregulation of essential transition metal ions, notably iron, copper, and zinc, stands as a critical nexus in the perpetuation of inflammatory processes and oxidative damage within the lungs of COPD patients. Unraveling the intricate interplay between metal homeostasis, oxidative stress, and inflammatory signaling is of paramount importance in unraveling the intricacies of COPD pathogenesis. This comprehensive review aims to examine the current literature on the sources, regulation, and mechanisms by which metal dyshomeostasis contributes to COPD progression. We specifically focus on iron, copper, and zinc, given their well-characterized roles in orchestrating cytokine production, immune cell function, antioxidant depletion, and matrix remodeling. Despite the limited number of clinical trials investigating metal modulation in COPD, the advent of emerging methodologies tailored to monitor metal fluxes and gauge responses to chelation and supplementation hold great promise in unlocking the potential of metal-based interventions. We conclude that targeted restoration of metal homeostasis represents a promising frontier for ameliorating pathological processes driving COPD progression.

Metabolic pathways in immune senescence and inflammaging: Novel therapeutic strategy for chronic inflammatory lung diseases. An EAACI position paper from the Task Force for Immunopharmacology

The accumulation of senescent cells drives inflammaging and increases morbidity of chronic inflammatory lung diseases. Immune responses are built upon dynamic changes in cell metabolism that supply energy and substrates for cell proliferation, differentiation, and activation. Metabolic changes imposed by environmental stress and inflammation on immune cells and tissue microenvironment are thus chiefly involved in the pathophysiology of allergic and other immune-driven diseases. Altered cell metabolism is also a hallmark of cell senescence, a condition characterized by loss of proliferative activity in cells that remain metabolically active. Accelerated senescence can be triggered by acute or chronic stress and inflammatory responses. In contrast, replicative senescence occurs as part of the physiological aging process and has protective roles in cancer surveillance and wound healing. Importantly, cell senescence can also change or hamper response to diverse therapeutic treatments. Understanding the metabolic pathways of senescence in immune and structural cells is therefore critical to detect, prevent, or revert detrimental aspects of senescence-related immunopathology, by developing specific diagnostics and targeted therapies. In this paper, we review the main changes and metabolic alterations occurring in senescent immune cells (macrophages, B cells, T cells). Subsequently, we present the metabolic footprints described in translational studies in patients with chronic asthma and chronic obstructive pulmonary disease (COPD), and review the ongoing preclinical studies and clinical trials of therapeutic approaches aiming at targeting metabolic pathways to antagonize pathological senescence. Because this is a recently emerging field in allergy and clinical immunology, a better understanding of the metabolic profile of the complex landscape of cell senescence is needed. The progress achieved so far is already providing opportunities for new therapies, as well as for strategies aimed at disease prevention and supporting healthy aging.

PathIntegrate: Multivariate modelling approaches for pathway-based multi-omics data integration

As terabytes of multi-omics data are being generated, there is an ever-increasing need for methods facilitating the integration and interpretation of such data. Current multi-omics integration methods typically output lists, clusters, or subnetworks of molecules related to an outcome. Even with expert domain knowledge, discerning the biological processes involved is a time-consuming activity. Here we propose PathIntegrate, a method for integrating multi-omics datasets based on pathways, designed to exploit knowledge of biological systems and thus provide interpretable models for such studies. PathIntegrate employs single-sample pathway analysis to transform multi-omics datasets from the molecular to the pathway-level, and applies a predictive single-view or multi-view model to integrate the data. Model outputs include multi-omics pathways ranked by their contribution to the outcome prediction, the contribution of each omics layer, and the importance of each molecule in a pathway. Using semi-synthetic data we demonstrate the benefit of grouping molecules into pathways to detect signals in low signal-to-noise scenarios, as well as the ability of PathIntegrate to precisely identify important pathways at low effect sizes. Finally, using COPD and COVID-19 data we showcase how PathIntegrate enables convenient integration and interpretation of complex high-dimensional multi-omics datasets. PathIntegrate is available as an open-source Python package.

PathIntegrate: Multivariate modelling approaches for pathway-based multi-omics data integration

As terabytes of multi-omics data are being generated, there is an ever-increasing need for methods facilitating the integration and interpretation of such data. Current multi-omics integration methods typically output lists, clusters, or subnetworks of molecules related to an outcome. Even with expert domain knowledge, discerning the biological processes involved is a time-consuming activity. Here we propose PathIntegrate, a method for integrating multi-omics datasets based on pathways, designed to exploit knowledge of biological systems and thus provide interpretable models for such studies. PathIntegrate employs single-sample pathway analysis to transform multi-omics datasets from the molecular to the pathway-level, and applies a predictive single-view or multi-view model to integrate the data. Model outputs include multi-omics pathways ranked by their contribution to the outcome prediction, the contribution of each omics layer, and the importance of each molecule in a pathway. Using semi-synthetic data we demonstrate the benefit of grouping molecules into pathways to detect signals in low signal-to-noise scenarios, as well as the ability of PathIntegrate to precisely identify important pathways at low effect sizes. Finally, using COPD and COVID-19 data we showcase how PathIntegrate enables convenient integration and interpretation of complex high-dimensional multi-omics datasets. The PathIntegrate Python package is available at https://github.com/cwieder/PathIntegrate.

Mitochondria-Targeted Antioxidants as a Therapeutic Strategy for Chronic Obstructive Pulmonary Disease

Oxidative stress is a major hallmark of COPD, contributing to inflammatory signaling, corticosteroid resistance, DNA damage, and accelerated lung aging and cellular senescence. Evidence suggests that oxidative damage is not solely due to exogenous exposure to inhaled irritants, but also endogenous sources of oxidants in the form of reactive oxygen species (ROS). Mitochondria, the major producers of ROS, exhibit impaired structure and function in COPD, resulting in reduced oxidative capacity and excessive ROS production. Antioxidants have been shown to protect against ROS-induced oxidative damage in COPD, by reducing ROS levels, reducing inflammation, and protecting against the development of emphysema. However, currently available antioxidants are not routinely used in the management of COPD, suggesting the need for more effective antioxidant agents. In recent years, a number of mitochondria-targeted antioxidant (MTA) compounds have been developed that are capable of crossing the mitochondria lipid bilayer, offering a more targeted approach to reducing ROS at its source. In particular, MTAs have been shown to illicit greater protective effects compared to non-targeted, cellular antioxidants by further reducing apoptosis and offering greater protection against mtDNA damage, suggesting they are promising therapeutic agents for the treatment of COPD. Here, we review evidence for the therapeutic potential of MTAs as a treatment for chronic lung disease and discuss current challenges and future directions.

Transcriptome analysis of sputum cells reveals two distinct molecular phenotypes of “asthma and chronic obstructive pulmonary disease overlap” in the elderly

Background

Little is known about the pathogenesis of asthma and chronic obstructive pulmonary disease (COPD) overlap (ACO). This study examined the molecular phenotypes of ACO in the elderly.

Methods

A genome-wide investigation of gene expression in sputum cells from the elderly with asthma, ACO, or COPD was performed using gene set variation analysis (GSVA) with predefined asthma- or COPD-specific gene signatures. We then performed a subsequent cluster analysis using enrichment scores (ESs) to identify molecular clusters in the elderly with ACO. Finally, a second GSVA was conducted with curated gene signatures to gain insight into the pathogenesis of ACO associated with the identified molecular clusters.

Results

Seventy elderly individuals were enrolled (17 with asthma, 41 with ACO, and 12 with COPD). Two distinct molecular clusters of ACO were identified. Clinically, ACO cluster 1 (N = 23) was characterized by male and smoker dominance, more obstructive lung function, and higher proportions of both neutrophil and eosinophil in induced sputum compared to ACO cluster 2 (N = 18). ACO cluster 1 had molecular features similar to both asthma and COPD, with mitochondria and peroxisome dysfunction as important mechanisms in the pathogenesis of these diseases. The molecular features of ACO cluster 2 differed from those of asthma and COPD, with enhanced innate immune reactions to microorganisms identified as being important in the pathogenesis of this form of ACO.

Conclusion

Recognition of the unique biological pathways associated with the two distinct molecular phenotypes of ACO will deepen our understanding of ACO in the elderly.

Acrolein inhalation acutely affects the regulation of mitochondrial metabolism in rat lung

Exposure of the airways to cigarette smoke (CS) is the primary risk factor for developing several lung diseases such as Chronic Obstructive Pulmonary Disease (COPD). CS consists of a complex mixture of over 6000 chemicals including the highly reactive α,β-unsaturated aldehyde acrolein. Acrolein is thought to be responsible for a large proportion of the non-cancer disease risk associated with smoking. Emerging evidence suggest a key role for CS-induced abnormalities in mitochondrial morphology and function in airway epithelial cells in COPD pathogenesis. Although in vitro studies suggest acrolein-induced mitochondrial dysfunction in airway epithelial cells, it is unknown if in vivo inhalation of acrolein affects mitochondrial content or the pathways controlling this. In this study, rats were acutely exposed to acrolein by inhalation (nose-only; 0-4 ppm), 4 h/day for 1 or 2 consecutive days (n = 6/group). Subsequently, the activity and abundance of key constituents of mitochondrial metabolic pathways as well as expression of critical proteins and genes controlling mitochondrial biogenesis and mitophagy were investigated in lung homogenates. A transient decreasing response in protein and transcript abundance of subunits of the electron transport chain complexes was observed following acrolein inhalation. Moreover, acrolein inhalation caused a decreased abundance of key regulators associated with mitochondrial biogenesis, respectively a differential response on day 1 versus day 2. Abundance of components of the mitophagy machinery was in general unaltered in response to acrolein exposure in rat lung. Collectively, this study demonstrates that acrolein inhalation acutely and dose-dependently disrupts the molecular regulation of mitochondrial metabolism in rat lung. Hence, understanding the effect of acrolein on mitochondrial function will provide a scientifically supported reasoning to shortlist aldehydes regulation in tobacco smoke.

Dysregulated mitochondrial metabolism upon cigarette smoke exposure in various human bronchial epithelial cell models

Exposure to cigarette smoke (CS) is the primary risk factor for developing chronic obstructive pulmonary disease. The impact of CS exposure on the molecular mechanisms involved in mitochondrial quality control in airway epithelial cells is incompletely understood. Undifferentiated or differentiated primary bronchial epithelial cells were acutely/chronically exposed to whole CS (WCS) or CS extract (CSE) in submerged or air-liquid interface conditions. Abundance of key regulators controlling mitochondrial biogenesis, mitophagy and mitochondrial dynamics was assessed. Acute exposure to WCS or CSE increased the abundance of components of autophagy and receptor-mediated mitophagy in all models. Although mitochondrial content and dynamics appeared to be unaltered in response to CS, changes in both the molecular control of mitochondrial biogenesis and a shift toward an increased glycolytic metabolism were observed in particular in differentiated cultures. These alterations persisted, at least in part, after chronic exposure to WCS during differentiation and upon subsequent discontinuation of WCS exposure. In conclusion, smoke exposure alters the regulation of mitochondrial metabolism in airway epithelial cells, but observed alterations may differ between various culture models used. This article has an associated First Person interview with the joint first authors of the paper.

Developing a novel strategy for COPD therapy by targeting Nrf2 and metabolism reprogramming simultaneously

Chronic obstructive pulmonary disease (COPD) is estimated to be the sixth major cause of disability, and the third main cause of death in the world by 2020. Although both inflammation and oxidative stress are well known to be the key predisposing factors in the pathogenesis of COPD, other elements, including metabolism, may also contribute to the exacerbation of the disease. However, the therapeutic approach which alters metabolism against COPD has yet been fully developed. Therefore, here we provide a novel therapeutic strategy for COPD patients. We first screened out the known nuclear factor erythroid-2-related factor 2 (Nrf2) activators, CPUY192018, which inhibits glycolysis, boosts antioxidative stress simultaneously and delivers satisfying therapeutic effect in macrophages from COPD patients and cigarette smoke extract induced COPD mice. Furthermore, we clarify that CPUY192018 not only disrupts the interaction between Kelch-like ECH-associated protein 1 (Keap1) and Nrf2, which liberates Nrf2 to activate the antioxidative pathway but also disrupt the interaction between Keap1 and actin which downregulates glycolysis, boosting the phagocytic function of alveolar macrophage in lung tissue. Taken together, CPUY192018 demonstrates notable effects on counteracting oxidative stress and reprogramming metabolism via Nrf2 activation; hence, being a raising potential therapeutic approach against COPD.

Association of resting energy expenditure and nutritional substrate oxidation with COPD stage and prediction indexes

While increase in resting energy expenditure (REE) of COPD patients is generally accepted, there is a lack of information about nutritional substrates oxidation (NSO) in this specific population. The aim of this study was comparison of REE and NSO from indirect calorimetry between COPD patients and control subjects and to evaluate possible associations with the disease stage and prediction indexes. In this observational study, 50 consecutive outpatients with stable COPD (COPD group) were examined and compared with 25 volunteers without respiratory problems (control group). Body composition, REE and NSO were determined in all study participants. All COPD subjects underwent a comprehensive examination to determine COPD severity and prognostic scales. Measured REE values adjusted for body weight, fat-free mass (FFM), and body surface were approximately 10% higher in COPD patients than in the control group. Respiratory quotient (RQ) and non-protein RQ (nRQ) values were respectively 5% and 10% higher in the COPD group. Adjusted carbohydrate oxidation was almost two times higher in comparison with the control group. We found no differences in absolute values of lipid and protein oxidation between the groups. Correlation analysis proved a positive association of relatively expressed REE and oxidation of lipids, and a negative association of RQ, nRQ and oxidation of carbohydrates with the value of prediction indexes. In conclusion, our study demonstrated metabolic changes in COPD patients leading to increased values of REE and changes in NSO which were associated with the disease stage, and which can be applied for nutritional support in clinical practice.

Respiratory metabolites in bronchoalveolar lavage fluid (BALF) and exhaled breath condensate (EBC) can differentiate horses affected by severe equine asthma from healthy horses

BACKGROUND

The use of an untargeted metabolomic approach to investigate biofluids of respiratory origin is of increasing interest in human and veterinary lung research. Considering the high incidence of equine asthma (> 14%) within horse population and the importance of this animal model for human disease, we aimed to investigate the metabolomic profile of bronchoalveolar lavage fluid (BALF) and exhaled breath condensate (EBC) in healthy and asthmatic horses.

RESULTS

On the basis of clinical, endoscopic and BALF cytology findings, 6 horses with severe asthma (Group A) and 6 healthy horses (Group C) were included in the study. 1H-NMR analysis was used to identified metabolites in BALF and EBC samples. Metabolomic analysis allowed to identify and quantify 12 metabolites in BALF and seven metabolites in EBC. Among respiratory metabolites, myo-inositol, formate, glycerol and isopropanol in BALF, and methanol and ethanol in EBC, differed between groups (p < 0.05).

CONCLUSIONS

The application of metabolomic studies to investigate equine asthma using minimally invasive diagnostic methods, such as EBC metabolomics, provided promising results. According to our research, the study of selective profiles of BALF and EBC metabolites might be useful for identifying molecules like myo-inositol and methanol as possible biomarkers for airways diseases in horses.

Metabolomic fingerprinting and systemic inflammatory profiling of asthma COPD overlap (ACO)

Background

Asthma-COPD overlap (ACO) refers to a group of poorly studied and characterised patients reporting with disease presentations of both asthma and COPD, thereby making both diagnosis and treatment challenging for the clinicians. They exhibit a higher burden in terms of both mortality and morbidity in comparison to patients with only asthma or COPD. The pathophysiology of the disease and its existence as a unique disease entity remains unclear. The present study aims to determine whether ACO has a distinct metabolic and immunological mediator profile in comparison to asthma and COPD.

Methods

Global metabolomic profiling using two different groups of patients [discovery (D) and validation (V)] were conducted. Serum samples obtained from moderate and severe asthma [n = 34(D); n = 32(V)], moderate and severe COPD [n = 30(D); 32(V)], ACO patients [n = 35(D); 40(V)] and healthy controls [n = 33(D)] were characterized using gas chromatography mass spectrometry (GC-MS). Multiplexed analysis of 25 immunological markers (IFN-γ (interferon gamma), TNF-α (tumor necrosis factor alpha), IL-12p70 (interleukin 12p70), IL-2, IL-4, IL-5, IL-13, IL-10, IL-1α, IL-1β, TGF-β (transforming growth factor), IL-6, IL-17E, IL-21, IL-23, eotaxin, GM-CSF (granulocyte macrophage-colony stimulating factor), IFN-α (interferon alpha), IL-18, NGAL (neutrophil gelatinase-associated lipocalin), periostin, TSLP (thymic stromal lymphopoietin), MCP-1 (monocyte chemoattractant protein- 1), YKL-40 (chitinase 3 like 1) and IL-8) was also performed in the discovery cohort.

Results

Eleven metabolites [serine, threonine, ethanolamine, glucose, cholesterol, 2-palmitoylglycerol, stearic acid, lactic acid, linoleic acid, D-mannose and succinic acid] were found to be significantly altered in ACO as compared with asthma and COPD. The levels and expression trends were successfully validated in a fresh cohort of subjects. Thirteen immunological mediators including TNFα, IL-1β, IL-17E, GM-CSF, IL-18, NGAL, IL-5, IL-10, MCP-1, YKL-40, IFN-γ, IL-6 and TGF-β showed distinct expression patterns in ACO. These markers and metabolites exhibited significant correlation with each other and also with lung function parameters.

Conclusions

The energy metabolites, cholesterol and fatty acids correlated significantly with the immunological mediators, suggesting existence of a possible link between the inflammatory status of these patients and impaired metabolism. The present findings could be possibly extended to better define the ACO diagnostic criteria, management and tailoring therapies exclusively for the disease.

Chemerin: A Potential Regulator of Inflammation and Metabolism for Chronic Obstructive Pulmonary Disease and Pulmonary Rehabilitation

Chronic obstructive pulmonary disease (COPD) features chronic inflammatory reactions of both intra- and extrapulmonary nature. Moreover, COPD is associated with abnormal glucose and lipid metabolism in patients, which influences the prognosis and chronicity of this disease. Abnormal glucose and lipid metabolism are also closely related to inflammation processes. Further insights into the interactions of inflammation and glucose and lipid metabolism might therefore inspire novel therapeutic interventions to promote lung rehabilitation. Chemerin, as a recently discovered adipokine, has been shown to play a role in inflammatory response and glucose and lipid metabolism in many diseases (including COPD). Chemerin recruits inflammatory cells to sites of inflammation during the early stages of COPD, leading to endothelial barrier dysfunction, early vascular remodeling, and angiogenesis. Moreover, it supports the recruitment of antigen-presenting cells that guide immune cells as part of the body's inflammatory responses. Chemerin also regulates metabolism via activation of its cognate receptors. Glucose homeostasis is affected via effects on insulin secretion and sensitivity, and lipid metabolism is changed by increased transformation of preadipocytes to mature adipocytes through chemerin-binding receptors. Controlling chemerin signaling may be a promising approach to improve various aspects of COPD-related dysfunction. Importantly, several studies indicate that chemerin expression in vivo is influenced by exercise. Although available evidence is still limited, therapeutic alterations of chemerin activity may be a promising target of therapeutic approaches aimed at the rehabilitation of COPD patients based on exercises. In conclusion, chemerin plays an essential role in COPD, especially in the inflammatory responses and metabolism, and has a potential to become a target for, and a biomarker of, curative mechanisms underlying exercise-mediated lung rehabilitation.

Cigarette Smoke Reduces Fatty Acid Catabolism, Leading to Apoptosis in Lung Endothelial Cells: Implication for Pathogenesis of COPD

Endothelial cell (EC) apoptosis contributes to cigarette smoke (CS)-induced pulmonary emphysema. Metabolism of glucose, glutamine, and fatty acid is dysregulated in patients with chronic obstructive pulmonary disease (COPD). Whether CS causes metabolic dysregulation in ECs leading to development of COPD remains elusive. We hypothesized that CS alters metabolism, resulting in apoptosis in lung ECs. To test this hypothesis, we treated primary mouse pulmonary microvascular ECs (PMVECs) with CS extract (CSE) and employed PMVECs from healthy subjects and COPD patients. We found that mitochondrial respiration was reduced in CSE-treated PMVECs and in PMVECs from COPD patients. Specifically, oxidation of fatty acids (FAO) was reduced in these cells, which linked to reduced carnitine palmitoyltransferase 1a (Cpt1a), an essential enzyme for carnitine shuttle. CSE-induced apoptosis was further increased when cells were treated with a specific Cpt1 inhibitor etomoxir or transfected with Cpt1a siRNA. L-Carnitine treatment augmented FAO but attenuated CSE-induced apoptosis by upregulating Cpt1a. CSE treatment increased palmitate-derived ceramide synthesis, which was reduced by L-carnitine. Although CSE treatment increased glycolysis, inhibiting glycolysis with 2-deoxy-d-glucose had no effects on CSE-mediated apoptosis in lung ECs. Conclusively, FAO reduction increases ceramide and apoptosis in lung ECs treated with CSE, which may contribute to the pathogenesis of COPD/emphysema.

Metabolomic signatures of asthma-COPD overlap (ACO) are different from asthma and COPD

INTRODUCTION

Asthma-chronic obstructive pulmonary disease (COPD) overlap, termed as ACO, is a complex heterogeneous disease without any clear diagnostic or therapeutic guidelines. The pathophysiology of the disease, its characteristic features, and existence as a unique disease entity remains unclear. Individuals with ACO have a faster lung function decline, more frequent exacerbations, and worse quality of life than those with COPD or asthma alone.

OBJECTIVES

The present study aims to determine whether ACO has a distinct metabolic profile in comparison to asthma and COPD.

METHODS

Two different groups of patients were recruited as discovery (D) and validation (V) cohorts. Serum samples obtained from moderate and severe asthma patients diagnosed as per GINA guidelines [n = 34(D); n = 32(V)], moderate and severe COPD cases identified by GOLD guidelines [n = 30(D); 32(V)], ACO patients diagnosed by joint GOLD and GINA guidelines [n = 35(D); 40(V)] and healthy controls [n = 33(D)] were characterized using nuclear magnetic resonance (NMR) spectrometry.

RESULTS

Multivariate and univariate analysis indicated that 12 metabolites [lipid, isoleucine, N-acetylglycoproteins (NAG), valine, glutamate, citric acid, glucose, L-leucine, lysine, asparagine, phenylalanine and histidine] were dysregulated in ACO patients when compared with both asthma and COPD. These metabolites were further validated in a fresh cohort of patients, which again exhibited a similar expression pattern.

CONCLUSIONS

Our findings suggest that ACO has an enhanced energy and metabolic burden associated with it as compared to asthma and COPD. It is anticipated that our results will stimulate researchers to further explore ACO and unravel the pathophysiological complexities associated with the disease.

Metabolomics in chronic lung diseases

Chronic lung diseases represent a significant global burden. Their increasing incidence and complexity render a comprehensive, multidisciplinary and personalized approach to each patient, critically important. Most recently, unique biochemical pathways and disease markers have been identified through large-scale metabolomic studies. Metabolomics is the study of metabolic pathways and the measurement of unique biomolecules in a living system. Analysing samples from different compartments such as bronchoalveolar lavage fluid (BALF) and plasma has proven useful for the characterization of a number of pathological conditions and offers promise as a clinical tool. For example, several studies using mass spectrometry (MS) have shown alterations in the sphingolipid metabolism of chronic obstructive pulmonary disease (COPD) sufferers. In this article, we present a practical review of the application of metabolomics to the study of chronic lung diseases (CLD): COPD, idiopathic pulmonary fibrosis (IPF) and asthma. The insights, which the analytical strategies employed in metabolomics, have provided to the dissection of the biochemistry of CLD and future clinical biomarkers are explored.

Quadriceps strength in patients with chronic obstructive pulmonary disease

Background

Skeletal muscle dysfunction is well known in chronic obstructive pulmonary disease (COPD). The muscle strength is altered in various muscles variedly. Lower-limb muscle strength is very important for walking distance. Reduced lower-limb strength can affect the physical quality of life.

Objectives

The aim of the study was to assess and compare the quadriceps strength in COPD patients and age-matched healthy controls and to study the correlation between lung function parameters and the quadriceps strength in patients with COPD.

Methodology

Thirty nonsmoker male patients; thirty nonsmoker female patients with COPD; and sixty age-, BMI-, and gender-matched healthy controls were studied. Quadriceps muscle strength was measured using a quadriceps dynamometer. Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), FEF 25-75, and peak expiratory flow rate were measured using Helios 702 Spirometer. The quadriceps muscle strength between the two groups was compared using the unpaired Student's t-test. Correlations between FVC and FEV₁with muscle strength were analyzed using the Pearson's coefficient.

Results

The mean unilateral and bilateral quadriceps strength in both male and female COPD patients was significantly lesser than the healthy controls (P < 0.05). There was a significant positive correlation between muscle strength and FVC and muscle strength and FEV₁in patients with COPD.

Conclusion

The study shows that there is quadriceps weakness in COPD patients, and pulmonary functions have a direct impact on skeletal muscle strength. Identifying those patients who have reduced strength will allow early interventions targeted at improving the quality of life of the patient.

1H-NMR-based metabolic profiling of healthy individuals and high-resolution CT-classified phenotypes of COPD with treatment of tiotropium bromide

Background

Heterogeneity of COPD results in different therapeutic effects for different patients receiving the same treatment. COPD patients need to be individually treated according to their own characteristics. The purpose of this study was to explore the differences in different CT phenotypic COPD by molecular metabolites through the use of metabolomics.

Methods

According to the characteristics of CT imaging, 42 COPD patients were grouped into phenotype E (n=20) or phenotype M (n=24). Each COPD patient received tiotropium bromide powder for inhalation for a therapeutic period of 3 months. All subjects were assigned into phenotype E in pre-therapy (EB, n=20), phenotype E in post-therapy (EA, n=20), phenotype M in pre-therapy (MB, n=22), phenotype M in post-therapy (MA, n=22), or normal control (N, n=24). The method of metabolomics based on ¹H nuclear magnetic resonance (¹H-NMR) was used to compare the changes in serum metabolites between COPD patients and normal controls and between different phenotypes of COPD patients in pre- and post-therapy.

Results

Patients with COPD phenotype E responded better to tiotropium bromide than patients with COPD phenotype M in terms of pulmonary function and COPD assessment test scores. There were differences in metabolites in COPD patients vs normal control people. Differences were also observed between different COPD phenotypic patients receiving the treatment in comparison with those who did not receive treatment. The changes of metabolites involved lactate, phenylalanine, fructose, glycine, asparagine, citric acid, pyruvic acid, proline, acetone, ornithine, lipid, pyridoxine, maltose, betaine, lipoprotein, and so on. These identified metabolites covered the metabolic pathways of amino acids, carbohydrates, lipids, genetic materials, and vitamin.

Conclusion

The efficacy of tiotropium bromide on COPD phenotype E is better than that of phenotype M. Metabolites detected by ¹H-NMR metabolomics have potentialities of differentiation of COPD and healthy people, discrimination of different COPD phenotypes, and giving insight into the individualized treatment of COPD.

Metabolic reprogramming in the pathogenesis of chronic lung diseases, including BPD, COPD, and pulmonary fibrosis

The metabolism of nutrient substrates, including glucose, glutamine, and fatty acids, provides acetyl-CoA for the tricarboxylic acid cycle to generate energy, as well as metabolites for the biosynthesis of biomolecules, including nucleotides, proteins, and lipids. It has been shown that metabolism of glucose, fatty acid, and glutamine plays important roles in modulating cellular proliferation, differentiation, apoptosis, autophagy, senescence, and inflammatory responses. All of these cellular processes contribute to the pathogenesis of chronic lung diseases, including bronchopulmonary dysplasia, chronic obstructive pulmonary disease, and pulmonary fibrosis. Recent studies demonstrate that metabolic reprogramming occurs in patients with and animal models of chronic lung diseases, suggesting that metabolic dysregulation may participate in the pathogenesis and progression of these diseases. In this review, we briefly discuss the catabolic pathways for glucose, glutamine, and fatty acids, and focus on how metabolic reprogramming of these pathways impacts cellular functions and leads to the development of these chronic lung diseases. We also highlight how targeting metabolic pathways can be utilized in the prevention and treatment of these diseases.

Is mitochondrial dysfunction a driving mechanism linking COPD to nonsmall cell lung carcinoma?

Chronic obstructive pulmonary disease (COPD) patients are at increased risk of developing nonsmall cell lung carcinoma, irrespective of their smoking history. Although the mechanisms behind this observation are not clear, established drivers of carcinogenesis in COPD include oxidative stress and sustained chronic inflammation. Mitochondria are critical in these two processes and recent evidence links increased oxidative stress in COPD patients to mitochondrial damage. We therefore postulate that mitochondrial damage in COPD patients leads to increased oxidative stress and chronic inflammation, thereby increasing the risk of carcinogenesis.

The functional state of the mitochondrion is dependent on the balance between its biogenesis and degradation (mitophagy). Dysfunctional mitochondria are a source of oxidative stress and inflammasome activation. In COPD, there is impaired translocation of the ubiquitin-related degradation molecule Parkin following activation of the Pink1 mitophagy pathway, resulting in excessive dysfunctional mitochondria. We hypothesise that deranged pathways in mitochondrial biogenesis and mitophagy in COPD can account for the increased risk in carcinogenesis. To test this hypothesis, animal models exposed to cigarette smoke and developing emphysema and lung cancer should be developed. In the future, the use of mitochondria-based antioxidants should be studied as an adjunct with the aim of reducing the risk of COPD-associated cancer.

Signaling network of lipids as a comprehensive scaffold for omics data integration in sputum of COPD patients

Chronic obstructive pulmonary disease (COPD) is a heterogeneous and progressive inflammatory condition that has been linked to the dysregulation of many metabolic pathways including lipid biosynthesis. How lipid metabolism could affect disease progression in smokers with COPD remains unclear. We cross-examined the transcriptomics, proteomics, metabolomics, and phenomics data available on the public domain to elucidate the mechanisms by which lipid metabolism is perturbed in COPD. We reconstructed a sputum lipid COPD (SpLiCO) signaling network utilizing active/inactive, and functional/dysfunctional lipid-mediated signaling pathways to explore how lipid-metabolism could promote COPD pathogenesis in smokers. SpLiCO was further utilized to investigate signal amplifiers, distributers, propagators, feed-forward and/or -back loops that link COPD disease severity and hypoxia to disruption in the metabolism of sphingolipids, fatty acids and energy. Also, hypergraph analysis and calculations for dependency of molecules identified several important nodes in the network with modular regulatory and signal distribution activities. Our systems-based analyses indicate that arachidonic acid is a critical and early signal distributer that is upregulated by the sphingolipid signaling pathway in COPD, while hypoxia plays a critical role in the elevated dependency to glucose as a major energy source. Integration of SpLiCo and clinical data shows a strong association between hypoxia and the upregulation of sphingolipids in smokers with emphysema, vascular disease, hypertension and those with increased risk of lung cancer.

MS-based metabolomics facilitates the discovery of in vivo functional small molecules with a diversity of biological contexts

In vivo small molecules as necessary intermediates are involved in numerous critical metabolic pathways and biological processes associated with many essential biological functions and events. There is growing evidence that MS-based metabolomics is emerging as a powerful tool to facilitate the discovery of functional small molecules that can better our understanding of development, infection, nutrition, disease, toxicity, drug therapeutics, gene modifications and host-pathogen interaction from metabolic perspectives. However, further progress must still be made in MS-based metabolomics because of the shortcomings in the current technologies and knowledge. This technique-driven review aims to explore the discovery of in vivo functional small molecules facilitated by MS-based metabolomics and to highlight the analytic capabilities and promising applications of this discovery strategy. Moreover, the biological significance of the discovery of in vivo functional small molecules with different biological contexts is also interrogated at a metabolic perspective.

Large-scale, ion-current-based proteomics investigation of bronchoalveolar lavage fluid in chronic obstructive pulmonary disease patients

Proteomic analysis of bronchoalveolar lavage fluid (BALF) in chronic obstructive pulmonary disease (COPD) patients may provide new biomarkers and deeper understanding of the disease mechanisms but remains challenging. Here we describe an ion-current-based strategy for comparative analysis of BALF proteomes from patients with moderate and stable COPD versus healthy controls. The strategy includes an efficient preparation procedure providing quantitative recovery and a nano-LC/MS analysis with a long, heated column. Under optimized conditions, high efficiency and reproducibility were achieved for each step, enabling a "20-plex" comparison of clinical subjects (n = 10/group). Without depletion/fractionation, a total of 423 unique protein groups were quantified under stringent criteria with at least two quantifiable peptides. Seventy-six proteins were determined as significantly altered in COPD, which represent a diversity of biological processes such as alcohol metabolic process, gluconeogenesis/glycolysis, inflammatory response, proteolysis, and oxidation reduction. Interestingly, altered alcohol metabolism responding to oxidant stress is a novel observation in COPD. The prominently elevated key enzymes involved in alcohol metabolism (e.g., ADH1B, ALDH2, and ALDH3A1) may provide a reasonable explanation for a bewildering observation in COPD patients known for decades: the underestimation of the blood alcohol concentrations through breath tests. These discoveries could provide new insights for identifying novel biomarkers and pathological mediators in clinical studies.

Metabonomic profiling of serum and urine by (1)H NMR-based spectroscopy discriminates patients with chronic obstructive pulmonary disease and healthy individuals

Chronic obstructive pulmonary disease (COPD) has seriously impacted the health of individuals and populations. In this study, proton nuclear magnetic resonance (¹H NMR)-based metabonomics combined with multivariate pattern recognition analysis was applied to investigate the metabolic signatures of patients with COPD. Serum and urine samples were collected from COPD patients (n = 32) and healthy controls (n = 21), respectively. Samples were analyzed by high resolution ¹H NMR (600 MHz), and the obtained spectral profiles were then subjected to multivariate data analysis. Consistent metabolic differences have been found in serum as well as in urine samples from COPD patients and healthy controls. Compared to healthy controls, COPD patients displayed decreased lipoprotein and amino acids, including branched-chain amino acids (BCAAs), and increased glycerolphosphocholine in serum. Moreover, metabolic differences in urine were more significant than in serum. Decreased urinary 1-methylnicotinamide, creatinine and lactate have been discovered in COPD patients in comparison with healthy controls. Conversely, acetate, ketone bodies, carnosine, m-hydroxyphenylacetate, phenylacetyglycine, pyruvate and α-ketoglutarate exhibited enhanced expression levels in COPD patients relative to healthy subjects. Our results illustrate the potential application of NMR-based metabonomics in early diagnosis and understanding the mechanisms of COPD.