Alveolar macrophage-mediated elastolysis: roles of matrix metalloproteinases, cysteine, and serine proteases

New insight into the molecular mechanism of TCM Bufei Huoxue formula for chronic obstructive pulmonary disease based on network pharmacology and experimental verification

OBJECTIVES

To unveil the mechanism of the Bufei Huoxue formula (BHF) for chronic obstructive pulmonary disease (COPD) through integrated network pharmacology (NP) and experimental verification.

METHODS

LC-MS was first applied to the analysis of both in vitro and in vivo samples from BHF for chemical profiling. Then a ligand library was prepared for NP to reveal the mechanism of BHF against COPD. Finally, verification was performed using an animal model related to the results from the NP.

KEY FINDINGS

A ligand library containing 170 compounds from BHF was obtained, while 357 targets related to COPD were filtered to construct a PPI network. GO and KEGG analysis demonstrated that bavachin, paeoniflorin, and demethylation of formononetin were the major compounds for BHF against COPD, which mainly by regulating the PI3K/Akt pathway. The experiments proved that BHF could alleviate lung injury and attenuate the release of TNF-α and IL-6 in the lung and BALF in a dose-dependent manner. Western blot further demonstrated the down-regulated effect of BHF on p-PI3K.

CONCLUSION

BHF provides a potent alternative for the treatment of COPD, and the mechanism is probably associated with regulating the PI3K/AKT pathway to alleviate inflammatory injury by bavachin, paeoniflorin, and demethylation of formononetin.

Inflammation mechanism and research progress of COPD

Chronic obstructive pulmonary disease (COPD) is a common respiratory disease characterized by irreversible progressive airflow limitation, often manifested by persistent cough, sputum production and other respiratory symptoms that pose a serious threat to human health and affect the quality of life of patients. The disease is associated with chronic inflammation, which is associated with the onset and progression of COPD, but anti-inflammatory therapy is not first-line treatment. Inflammation has multiple manifestations and phenotypes, and this heterogeneity reveals different patterns of inflammation, making treatment difficult. This paper aims to explore the direction of more effective anti-inflammatory treatment by analyzing the nature of inflammation and the molecular mechanism of disease occurrence and development in COPD patients, and to provide new ideas for the treatment of COPD patients.

Causal Involvement of Immune Cells in Chronic Obstructive Pulmonary Disease: A Mendelian Randomization Study

Background

The immune cells play a substantial role in the development and progression of chronic obstructive pulmonary disease (COPD). We aim to investigate the causal involvement of immune cells in COPD via a Mendelian randomization (MR) analysis.

Methods

Published genome-wide association studies (GWAS) statistics on immune cells were analyzed, with genetic variants identified as instrumental variables (IVs). Inverse-variance weighting (IVW), weighted median, and MR-Egger regression methods were employed, along with simple mode and weighted mode adopted in the two-sample MR analysis. Sensitivity analysis was conducted to examine the heterogeneity, horizontal pleiotropy, and stability of the causal relationship.

Results

IVW results suggested that CCR2 on CD62L+ plasmacytoid dendritic cells (DC), CCR2 on plasmacytoid DC, CD11b on CD66b++ myeloid cells, CD19 on CD20- CD38- CD24+ memory B cell subset, CD25 on transitional B cells, and CD25++CD8br %CD8br T cells were risk factors for the development of COPD. Besides, CD127 on effector memory-like cytotoxic T lymphocytes lacking expression of co-stimulatory molecule 28 (CD28-EM CTLs) and HLA DR+ NK ACs expressing human leukocyte antigen DR molecules while being natural killer cells (%NK ACs) were protective factors for COPD.

Conclusion

This study unveiled a causal relationship between immune cell phenotype and COPD. These findings offer new insights for the prevention and treatment of COPD using COPD-associated immune cells.

The Role of Macrophages in Lung Fibrosis and the Signaling Pathway

Lung fibrosis is a dysregulated repair process caused by excessive deposition of extracellular matrix that can severely affect respiratory function. Macrophages are a group of immune cells that have multiple functions and can perform a variety of roles. Lung fibrosis develops with the involvement of pro-inflammatory and pro-fibrotic factors secreted by macrophages. The balance between M1 and M2 macrophages has been proposed to play a role in determining the trend and severity of lung fibrosis. New avenues and concepts for preventing and treating lung fibrosis have emerged in recent years through research on mitochondria, Gab proteins, and exosomes. The main topic of this essay is the impact that mitochondria, Gab proteins, and exosomes have on macrophage polarization. In addition, the potential of these factors as targets to enhance lung fibrosis is also explored. We have also collated the functions and mechanisms of signaling pathways associated with the regulation of macrophage polarization such as Notch, TGF-β/Smad, JAK-STAT and cGAS-STING. The goal of this article is to explain the potential benefits of focusing on macrophage polarization as a way to relieve lung fibrosis. We aspire to provide valuable insights that could lead to enhancements in the treatment of this condition.

Persistence of emphysema following cessation of cigarette smoke exposure requires a susceptibility factor

Chronic obstructive pulmonary disease (COPD) is caused by cigarette smoke (CS) exposure but can often be progressive even in former smokers. Exposure of mice to CS for 22 wk causes emphysema, but whether emphysema persists after cessation of CS exposure is not clear. The purpose of this study was to determine whether emphysema persists in mice following a recovery period of 22 wk and whether a susceptibility factor, such as deficiency in the Bcl-2-interacting killer (Bik), is required for this persistence. Therefore, bik+/+ and bik-/- mice at 6-10 wk of age were exposed to 250 mg/m3 total particulate matter of CS or filtered air (FA) for 3 or 22 wk and were kept in FA for an additional 22 wk. Lungs were lavaged to quantify inflammatory cells, and sections were stained with hematoxylin and eosin to assess severity of emphysema. Exposure to CS for 3 wk increased the number of inflammatory cells in bik-/- mice compared with bik+/+ mice but not at 22 wk of exposure. At 22 wk of CS exposure, extent of emphysema was similar in bik+/+ and bik-/- mice. However, when mice were exposed to CS over the first 22 wk and were kept in FA for an additional 22 wk, emphysema remained similar in bik+/+ mice but was enhanced in bik-/- mice. These findings link increased inflammation with persistent emphysematous changes even after smoking cessation and demonstrate that a preexisting susceptibility condition is required to sustain enhanced emphysema that was initiated by long-term CS exposure.NEW & NOTEWORTHY Exposure of mice to cigarette smoke (CS) for 22 wk causes emphysema, but whether emphysema persists after an additional period of 6 mo after cessation of CS exposure has not been reported. In addition, the role of preexisting susceptibility in enhancing the persistence of CS-induced emphysema after exposure to CS has stopped has not been shown. The present study shows that a preexisting susceptibility must be present to enhance CS-induced emphysema after cessation of CS exposure.

Inflammation as the nexus: exploring the link between acute myocardial infarction and chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), particularly following acute exacerbations (AE-COPD), significantly heightens the risks and mortality associated with acute myocardial infarction (AMI). The intersection of COPD and AMI is characterised by a considerable overlap in inflammatory mechanisms, which play a crucial role in the development of both conditions. Although extensive research has been conducted on individual inflammatory pathways in AMI and COPD, the understanding of thrombo-inflammatory crosstalk in comorbid settings remains limited. The effectiveness of various inflammatory components in reducing AMI infarct size or slowing COPD progression has shown promise, yet their efficacy in the context of comorbidity with COPD and AMI is not established. This review focuses on the critical importance of both local and systemic inflammation, highlighting it as a key pathophysiological connection between AMI and COPD/AE-COPD.

The impact of the immune system on lung injury and regeneration in COPD

COPD is a devastating respiratory condition that manifests via persistent inflammation, emphysema development and small airway remodelling. Lung regeneration is defined as the ability of the lung to repair itself after injury by the proliferation and differentiation of progenitor cell populations, and becomes impaired in the COPD lung as a consequence of cell intrinsic epithelial stem cell defects and signals from the micro-environment. Although the loss of structural integrity and lung regenerative capacity are critical for disease progression, our understanding of the cellular players and molecular pathways that hamper regeneration in COPD remains limited. Intriguingly, despite being a key driver of COPD pathogenesis, the role of the immune system in regulating lung regenerative mechanisms is understudied. In this review, we summarise recent evidence on the contribution of immune cells to lung injury and regeneration. We focus on four main axes: 1) the mechanisms via which myeloid cells cause alveolar degradation; 2) the formation of tertiary lymphoid structures and the production of autoreactive antibodies; 3) the consequences of inefficient apoptotic cell removal; and 4) the effects of innate and adaptive immune cell signalling on alveolar epithelial proliferation and differentiation. We finally provide insight on how recent technological advances in omics technologies and human ex vivo lung models can delineate immune cell-epithelium cross-talk and expedite precision pro-regenerative approaches toward reprogramming the alveolar immune niche to treat COPD.

Germline variants of the genes involved in NF-kB activation are associated with the risk of COPD and lung cancer development

Chronic obstructive pulmonary disease (COPD) and lung cancer (LC) are closely related diseases associated with smoking history and dysregulated immune response. However, not all smokers develop the disease, indicating that genetic susceptibility could be important. Therefore, the aim of this study was to search for the potential overlapping genetic biomarkers, with a focus on single nucleotide polymorphisms (SNPs) located in the regulatory regions of immune-related genes. Additionally, the aim was to see if an identified SNP has potentially an effect on proinflamma-tory cytokine concentration in the serum of COPD patients. We extracted summary data of variants in 1511 immune-related genes from COPD and LC genome-wide association studies (GWAS) from the UK Biobank. The LC data had 203 cases, patients diagnosed with LC, and 360 938 controls, while COPD data had 1 897 cases and 359 297 controls. Assuming 1 association/gene, SNPs with a p-value < 3.3 × 10^-5 were considered statistically significantly associated with the disease. We identified seven SNPs located in different genes (BAG6, BTNL2, TNF, HCP5, MICB, NCR3, ABCF1, TCF7L1) to be associated with the COPD risk and two with the LC risk (HLA-C, HLA-B), with statistical significance. We also identified two SNPs located in the IL2RA gene associated with LC (rs2386841; p = 1.86 × 10^-4) and COPD (rs11256442; p = 9.79 × 10^-3) but with lower significance. Functional studies conducted on COPD patients showed that RNA expression of IL2RA, IFNγ and related proinflammatory cytokines in blood serum did not correlate with a specific genotype. Although results presented in this study do not fully support our hypothesis, it is worth to mention that the identified genes/SNPs that were associated with either COPD or LC risk, all were involved in the activation of the NF-κB transcription factor which is closely related to the regulation of the inflammatory response, a condition associated with both pathologies.

Potential Mechanisms Between HF and COPD: New Insights From Bioinformatics

Heart failure (HF) and chronic obstructive pulmonary disease (COPD) are closely related in clinical practice. This study aimed to investigate the co-genetic characteristics and potential molecular mechanisms of HF and COPD. HF and COPD datasets were downloaded from gene expression omnibus database. After identifying common differentially expressed genes (DEGs), the functional analysis highlighted the critical role of extracellular matrix and ribosomal signaling pathways in both diseases. In addition, GeneMANIA's results suggested that the 2 diseases were related to immune infiltration, and CIBERSORT suggested the role of macrophages. We also discovered 4 TFs and 1408 miRNAs linked to both diseases, and salbutamol may positively affect them.

Overview of the Mechanisms of Oxidative Stress: Impact in Inflammation of the Airway Diseases

Inflammation of the human lung is mediated in response to different stimuli (e.g., physical, radioactive, infective, pro-allergenic or toxic) such as cigarette smoke and environmental pollutants. They often promote an increase in inflammatory activities in the airways that manifest themselves as chronic diseases (e.g., allergic airway diseases, asthma, chronic bronchitis/chronic obstructive pulmonary disease (COPD) or even lung cancer). Increased levels of oxidative stress (OS) reduce the antioxidant defenses, affect the autophagy/mitophagy processes, and the regulatory mechanisms of cell survival, promoting inflammation in the lung. In fact, OS potentiate the inflammatory activities in the lung, favoring the progression of chronic airway diseases. OS increases the production of reactive oxygen species (ROS), including superoxide anions (O₂^-), hydroxyl radicals (OH) and hydrogen peroxide (H₂O₂), by the transformation of oxygen through enzymatic and non-enzymatic reactions. In this manner, OS reduces endogenous antioxidant defenses in both nucleated and non-nucleated cells. The production of ROS in the lung can derive from both exogenous insults (cigarette smoke or environmental pollution) and endogenous sources such as cell injury and/or activated inflammatory and structural cells. In this review, we describe the most relevant knowledge concerning the functional interrelation between the mechanisms of OS and inflammation in airway diseases.

Understanding Acquired Brain Injury: A Review

Any type of brain injury that transpires post-birth is referred to as Acquired Brain Injury (ABI). In general, ABI does not result from congenital disorders, degenerative diseases, or by brain trauma at birth. Although the human brain is protected from the external world by layers of tissues and bone, floating in nutrient-rich cerebrospinal fluid (CSF); it remains susceptible to harm and impairment. Brain damage resulting from ABI leads to changes in the normal neuronal tissue activity and/or structure in one or multiple areas of the brain, which can often affect normal brain functions. Impairment sustained from an ABI can last anywhere from days to a lifetime depending on the severity of the injury; however, many patients face trouble integrating themselves back into the community due to possible psychological and physiological outcomes. In this review, we discuss ABI pathologies, their types, and cellular mechanisms and summarize the therapeutic approaches for a better understanding of the subject and to create awareness among the public.

Angiogenesis, Lymphangiogenesis, and Inflammation in Chronic Obstructive Pulmonary Disease (COPD): Few Certainties and Many Outstanding Questions

Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation, predominantly affecting the lung parenchyma and peripheral airways, that results in progressive and irreversible airflow obstruction. COPD development is promoted by persistent pulmonary inflammation in response to several stimuli (e.g., cigarette smoke, bacterial and viral infections, air pollution, etc.). Angiogenesis, the formation of new blood vessels, and lymphangiogenesis, the formation of new lymphatic vessels, are features of airway inflammation in COPD. There is compelling evidence that effector cells of inflammation (lung-resident macrophages and mast cells and infiltrating neutrophils, eosinophils, basophils, lymphocytes, etc.) are major sources of a vast array of angiogenic (e.g., vascular endothelial growth factor-A (VEGF-A), angiopoietins) and/or lymphangiogenic factors (VEGF-C, -D). Further, structural cells, including bronchial and alveolar epithelial cells, endothelial cells, fibroblasts/myofibroblasts, and airway smooth muscle cells, can contribute to inflammation and angiogenesis in COPD. Although there is evidence that alterations of angiogenesis and, to a lesser extent, lymphangiogenesis, are associated with COPD, there are still many unanswered questions.

Emerging role of exosomes in the pathology of chronic obstructive pulmonary diseases; destructive and therapeutic properties

Chronic obstructive pulmonary disease (COPD) is known as the third leading cause of human death globally. Enhanced chronic inflammation and pathological remodeling are the main consequences of COPD, leading to decreased life span. Histological and molecular investigations revealed that prominent immune cell infiltration and release of several cytokines contribute to progressive chronic remodeling. Recent investigations have revealed that exosomes belonging to extracellular vesicles are involved in the pathogenesis of COPD. It has been elucidated that exosomes secreted from immune cells are eligible to carry numerous pro-inflammatory factors exacerbating the pathological conditions. Here, in this review article, we have summarized various and reliable information about the negative role of immune cell-derived exosomes in the remodeling of pulmonary tissue and airways destruction in COPD patients.

Pathogenesis of COPD at the cellular and molecular level

Chronic inflammatory responses in the lung of patients with stable mild-to severe forms of COPD play a central role in the definition, comprehension and monitoring of the disease state. A better understanding of the COPD pathogenesis can't avoid a detailed knowledge of these inflammatory changes altering the functional health of the lung during the disease progression. We here summarize and discuss the role and principal functions of the inflammatory cells populating the large, small airways and lung parenchyma of patients with COPD of increasing severity in comparison with healthy control subjects: T and B lymphocytes, NK and Innate Lymphoid cells, macrophages, and neutrophils. The differential inflammatory distribution in large and small airways of patients is also discussed. Furthermore, relevant cellular mechanisms controlling the homeostasis and the "normal" balance of these inflammatory cells and of structural cells in the lung, such as autophagy, apoptosis, necroptosis and pyroptosis are as well presented and discussed in the context of the COPD severity.

Involvement of the Innate Immune System in the Pathogenesis of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a common, socially significant disease characterized by progressive airflow limitation due to chronic inflammation in the bronchi. Although the causes of COPD are considered to be known, the pathogenesis of the disease continues to be a relevant topic of study. Mechanisms of the innate immune system are involved in various links in the pathogenesis of COPD, leading to persistence of chronic inflammation in the bronchi, their bacterial colonization and disruption of lung structure and function. Bronchial epithelial cells, neutrophils, macrophages and other cells are involved in the development and progression of the disease, demonstrating multiple compromised immune mechanisms.

Mechanisms, Pathophysiology and Currently Proposed Treatments of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is one of the leading global causes of morbidity and mortality. A hallmark of COPD is progressive airflow obstruction primarily caused by cigarette smoke (CS). CS exposure causes an imbalance favoring pro- over antioxidants (oxidative stress), leading to transcription factor activation and increased expression of inflammatory mediators and proteases. Different cell types, including macrophages, epithelial cells, neutrophils, and T lymphocytes, contribute to COPD pathophysiology. Alteration in cell functions results in the generation of an oxidative and inflammatory microenvironment, which contributes to disease progression. Current treatments include inhaled corticosteroids and bronchodilator therapy. However, these therapies do not effectively halt disease progression. Due to the complexity of its pathophysiology, and the risk of exacerbating symptoms with existing therapies, other specific and effective treatment options are required. Therapies directly or indirectly targeting the oxidative imbalance may be promising alternatives. This review briefly discusses COPD pathophysiology, and provides an update on the development and clinical testing of novel COPD treatments.

Leukocyte Function in COPD: Clinical Relevance and Potential for Drug Therapy

Chronic obstructive pulmonary disease (COPD) is a progressive lung condition affecting 10% of the global population over 45 years. Currently, there are no disease-modifying treatments, with current therapies treating only the symptoms of the disease. COPD is an inflammatory disease, with a high infiltration of leukocytes being found within the lung of COPD patients. These leukocytes, if not kept in check, damage the lung, leading to the pathophysiology associated with the disease. In this review, we focus on the main leukocytes found within the COPD lung, describing how the release of chemokines from the damaged epithelial lining recruits these cells into the lung. Once present, these cells become active and may be driven towards a more pro-inflammatory phenotype. These cells release their own subtypes of inflammatory mediators, growth factors and proteases which can all lead to airway remodeling, mucus hypersecretion and emphysema. Finally, we describe some of the current therapies and potential new targets that could be utilized to target aberrant leukocyte function in the COPD lung. Here, we focus on old therapies such as statins and corticosteroids, but also look at the emerging field of biologics describing those which have been tested in COPD already and potential new monoclonal antibodies which are under review.

Epithelial Barrier Dysfunction in Chronic Respiratory Diseases

Mucosal surfaces are lined by epithelial cells, which provide a complex and adaptive module that ensures first-line defense against external toxics, irritants, antigens, and pathogens. The underlying mechanisms of host protection encompass multiple physical, chemical, and immune pathways. In the lung, inhaled agents continually challenge the airway epithelial barrier, which is altered in chronic diseases such as chronic obstructive pulmonary disease, asthma, cystic fibrosis, or pulmonary fibrosis. In this review, we describe the epithelial barrier abnormalities that are observed in such disorders and summarize current knowledge on the mechanisms driving impaired barrier function, which could represent targets of future therapeutic approaches.

Exposure to total particulate matter obtained from combustion of diesel vehicles (EURO 3 and EURO 5): Effects on the respiratory systems of emphysematous mice

Air pollution has association with chronic obstructive pulmonary disease (COPD) and reduced life expectancy. This study investigated the deleterious effects caused by tobacco smoke and diesel exhaust particles (DEP) from vehicles operating under EURO 3 and EURO 5 standards. Experiments were carried out on C57BL/6 mice divided into six groups: control group, group exposed to cigarette smoke (CS), two groups exposed to DEP (AAE3 and AAE5), and two groups exposed to tobacco smoke and vehicle DEP (CSE3 and CSE5). Results showed that, when compared to AA, groups AAE3 and AAE5 showed changes in respiratory mechanics, and that DEP originating from EURO 5 diesel vehicles was less harmful when compared to DEP originating from EURO 3 diesel vehicles. Analyses of groups CSE3 and CSE5 revealed increased inspiratory capacity and decreased tissue elastance, when compared to their respective controls, suggesting an exacerbation of changes in respiratory system mechanics compatible with COPD development.

First evidence of Klebsiella pneumoniae infection in Aceh cattle: Pathomorphology and antigenic distribution in the lungs

BACKGROUND AND AIM

Klebsiella pneumoniae is an emerging zoonotic and foodborne pathogen worldwide. Hypervirulent K. pneumoniae (hvKp) was reported as the causative agent of bovine mastitis. This is the first study in Indonesia that has been conducted to determine the capsular serotype of K. pneumoniae, pulmonary gross pathology and histopathology, and distribution of hvKp in the lungs of Aceh cattle.

MATERIALS AND METHODS

The presence of K. pneumoniae in Aceh cattle was investigated in two slaughterhouses in Banda Aceh and Aceh Besar, Indonesia. Lung tissues with gross pathological lesions were collected from 15 cattle presenting with depression, dehydration, or cachexia. The confirmation and capsular serotyping of K. pneumoniae isolates were performed using polymerase chain reaction. The tissues were stained with hematoxylin-eosin and immunohistochemistry to observe the histopathological lesions and the distribution of the hvKp antigens.

RESULTS

The pneumonic lesions identified in the lungs of Aceh cattle included hyperemia, hemorrhage, consolidation, and atelectasis. K. pneumoniae was isolated in all 15 lung tissues with pathological pneumonic lesions. Two patterns of infection were observed histopathologically. Acute infection was characterized by hyperemia, inflammatory cell infiltration, hemorrhage, bronchiolar epithelium hyperplasia, bronchial and bronchiolar obstruction with purulent exudates, edema, and atelectasis. On the other hand, chronic infection was defined by macrophage infiltration, emphysema, bronchial dilatation, pleural fibrosis, and alveolar wall thickening by interstitial fibrosis. Immunohistochemical staining using monospecific antisera induced by the hvKp isolate confirmed the presence of K. pneumoniae-specific antigens in the acute infection, predominantly in the bronchiolar, vascular, and alveolar areas. In contrast, generally diffuse infiltrates were found in the pleura and interstitial alveolar areas in chronic infection.

CONCLUSION

hvKp can be detected in the lungs of Aceh cattle, representing acute and chronic infections. The distribution of Klebsiella antigens in the lung tissue was consistent with the histopathological findings.

Oxidative Stress-Derived Mitochondrial Dysfunction in Chronic Obstructive Pulmonary Disease: A Concise Review

Chronic obstructive pulmonary disease (COPD) is a progressive and disabling disorder marked by airflow limitation and extensive destruction of lung parenchyma. Cigarette smoke is the major risk factor for COPD development and has been associated with increased oxidant burden on multiple cell types in the lungs. Elevated levels of reactive oxygen species (ROS) may significantly affect expression of biological molecules, signaling pathways, and function of antioxidant defenses. Although inflammatory cells, such as neutrophils and macrophages, contribute to the release of large quantities of ROS, mitochondrial dysfunction plays a critical role in ROS production due to oxidative phosphorylation. Although mitochondria are dynamic organelles, excess oxidative stress is able to alter mitochondrial function, morphology, and RNA and protein content. Indeed, mitochondria may change their shape by undergoing fusion (regulated by mitofusin 1, mitofusin 2, and optic atrophy 1 proteins) and fission (regulated by dynamin-related protein 1), which are essential processes to maintain a healthy and functional mitochondrial network. Cigarette smoke can induce mitochondrial hyperfusion, thus reducing mitochondrial quality control and cellular stress resistance. Furthermore, diminished levels of enzymes involved in the mitophagy process, such as Parkin (a ubiquitin ligase E3) and the PTEN-induced putative kinase 1 (PINK1), are commonly observed in COPD and correlate directly with faulty removal of dysfunctional mitochondria and consequent cell senescence in this disorder. In this review, we highlight the main mechanisms for the regulation of mitochondrial quality and how they are affected by oxidative stress during COPD development and progression.

Proteomics: An advanced tool to unravel the role of alveolar macrophages in respiratory diseases

As we learn more about chronic lung diseases, we are seeing that an unbalanced immune system plays a key role in disease pathogenesis. Innate immune cells, particularly tissue-resident macrophages, are important navigators of immunity, both during infection and in non-communicable lung disease. In the lung, alveolar macrophages are considered some of the most critical and diverse immune cells, yet despite an array of studies over the years, alveolar macrophages remain poorly understood. In this review, we highlight the importance of alveolar macrophages in health and disease, and discuss how proteomics can be used to elucidate mechanistic information and identify potential targets for therapy development.

Doxycycline aggravates granulomatous inflammation and lung microstructural remodeling induced by Schistosoma mansoni infection

Although doxycycline exhibits immunomodulatory properties, its effects on pulmonary infection by Schistosoma mansoni remain overlooked. Thus, we investigated the impact of this drug on lung granulomatous inflammation and microstructural remodeling in a murine model of schistosomiasis. Swiss mice were randomized in four groups: (i) uninfected, (ii) infected with S. mansoni and untreated, (iii) infected treated with praziquantel (Pzq; 200 mg/kg), and (iv) infected treated with Dox (50 mg/kg). Pz was administered in a single dose, and Dox for 60 days. S. mansoni induced marked granulomatous lung inflammation, which was associated to cytokines upregulation (IL-2, IL-4, IL-10, IFN-γ, TNF-α, and TGF-β), neutrophils and macrophages recruitment, alveolar collapse, lung fibrosis, and extensive depletion of elastic fibers. These parameters were attenuated by Pzq and aggravated by Dox. Exudative/productive granulomas were predominant in untreated and Dox-treated animals, while fibrotic granulomas were more frequent in Pzq-treated mice. The number and size of granulomas in Dox-treated animals was higher than untreated and Pzq-treated mice. Dox treatment inhibited the increase in MMP-1 and MMP-2 activity but upregulated myeloperoxidase and N-acetylglucosaminidase activity compared to untreated and Pzq-treated animals. Dox and Pzq exerted no effect on elastin depletion and upregulation of elastase activity. Together, our findings indicated that Dox aggravated granulomatous inflammation, accelerating lung microstructural remodeling by downregulating MMP-1 and MMP-2 activity without impair neutrophils and macrophages recruitment or elastase activity. Thus, Dox potentiates inflammatory damage associated with lung fibrosis, elastin depletion and massive alveolar collapse, profoundly subverting lung structure in S. mansoni-infected mice.

Extracellular Vesicles from Airway Secretions: New Insights in Lung Diseases

Lung diseases (LD) are one of the most common causes of death worldwide. Although it is known that chronic airway inflammation and excessive tissue repair are processes associated with LD such as asthma, chronic obstructive pulmonary disease (COPD) or idiopathic pulmonary fibrosis (IPF), their specific pathways remain unclear. Extracellular vesicles (EVs) are heterogeneous nanoscale membrane vesicles with an important role in cell-to-cell communication. EVs are present in general biofluids as plasma or urine but also in secretions of the airway as bronchoalveolar lavage fluid (BALF), induced sputum (IS), nasal lavage (NL) or pharyngeal lavage. Alterations of airway EV cargo could be crucial for understanding LD. Airway EVs have shown a role in the pathogenesis of some LD such as eosinophil increase in asthma, the promotion of lung cancer in vitro models in COPD and as biomarkers to distinguishing IPF in patients with diffuse lung diseases. In addition, they also have a promising future as therapeutics for LD. In this review, we focus on the importance of airway secretions in LD, the pivotal role of EVs from those secretions on their pathophysiology and their potential for biomarker discovery.

The impact of ageing on monocytes and macrophages

Ageing is a global burden. Increasing age is associated with increased incidence of infections and cancer and decreased vaccine efficacy. This increased morbidity observed with age, is believed to be due in part to a decline in adaptive immunity, termed immunosenescence. However not all aspects of immunity decrease with age as ageing presents with systemic low grade chronic inflammation, characterised by elevated concentrations of mediators such as IL-6, TNFα and C Reactive protein (CRP). Inflammation is a strong predictor of morbidity and mortality, and chronic inflammation is known to be detrimental to a functioning immune system. Although the source of the inflammation is much discussed, the key cells which are believed to facilitate the inflammageing phenomenon are the monocytes and macrophages. In this review we detail how macrophage and monocyte phenotype and function change with age. The impact of ageing on macrophages includes decreased phagocytosis and immune resolution, increased senescent-associated markers, increased inflammatory cytokine production, reduced autophagy, and a decrease in TLR expression. With monocytes there is an increase in circulating CD16⁺ monocytes, decreased type I IFN production, and decreased efferocytosis. In conclusion, we believe that monocytes and macrophages contribute to immunosenescence and inflammageing and as a result have an important role in defective immunity with age.

CircRNA0001859, a new diagnostic and prognostic biomarkers for COPD and AECOPD

Background

Dysregulation of circRNAs has been reported to be functionally associated with chronic obstructive pulmonary disease (COPD). The present investigation elucidated the potential role of CircRNA0001859 in regulating chronic obstructive pulmonary disease acute (COPD) and Acute Exacerbation of COPD (AECOPD).

Methods

Mice model of COPD was established to screen and verify the dysregulated expression of CircRNA0001859. Fluorescence in situ hybridization (FISH) and quantitative real-time PCR (qRT-PCR) were carried out to detect the expression of CircRNA0001859. 38 stable COPD patients, 24 AECOPD patients, 57 COPD with lung cancer patients and 28 healthy person with age and sex matched to total patients were used for the present investigation.

Results

circRNA0001859 was downregulated in the lung tissue of mice after the three kinds of treatments (Cigarette smoke (CS)/NK alone or CS + NNK) for inducing COPD. FISH assay verified the downregulation of circRNA0001859 both in the mice lung and human bronchial epithelial cell of COPD model. Furthermore,, the level of circRNA0001859 was also downregulated in the peripheral blood of COPD and lung cancer patients. CircRNA0001859 might act as a diagnostic and prognostic biomarker for the treatment of in COPD and AECOPD with Are under the receiver operating characteristic curve (ROC curve) (AUC) of 0.7433 and 0.8717, respectively.

Conclusion

We explored a novel circRNA0001859, which might act as a potential therapeutic biomarker for the treatment of COPD and AECOPD.

Sputum and salivary protein biomarkers and point-of-care biosensors for the management of COPD

Chronic obstructive pulmonary disease (COPD) has become one of the most fatal diseases of the century considering mortality and morbidity levels worldwide. This disease is an inflammatory response to environmental stress and tobacco smoking. Although spirometry is the gold-standard diagnostic test administrated in primary and secondary care, it often exhibits low accuracy in cases of predicting disease worsening and possible bias due to the operator, patient, and conditions. Recent developments in proteomics research suggest that the presence of protein biomarkers can aid in the accurate diagnosis and prediction of disease outcomes. This review presents the cutting-edge research progress in the area of protein biomarkers towards the management of COPD. The literature review was confined to protein biomarkers in saliva and sputum because testing these bodily fluids shows great promise for point-of-care (POC) testing due to its practicality, non-invasiveness and inexpensive handling and sampling. Although it is conclusive that more studies on sputum and saliva are needed, this review studies the promising clinical value of interleukin (IL)-6 and IL-8, matrix metalloproteinase (MMP)-8 and MMP-9, C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), and neutrophil elastase (NE). Following the critical analysis of salivary and sputum biomarkers, the recent development of POC biosensors for the multiplexed detection of biomarkers is also reported. Overall, the review aims to explore the possibility for the future development of POC sensors for chronic lung disease management utilizing clinically relevant biomarkers in saliva and sputum.

Impact of emphysema on sputum culture conversion in male patients with pulmonary tuberculosis: a retrospective analysis

Background

Although cigarette smoking may have a negative impact on the clinical outcome of pulmonary tuberculosis (PTB), few studies have investigated the impact of smoking-associated lung diseases. Emphysema is a major pathological finding of smoking-related lung damage. We aimed to clarify the effect of emphysema on sputum culture conversion rate for Mycobacterium tuberculosis (MTB).

Methods

We retrospectively studied 79 male patients with PTB confirmed by acid-fast bacillus smear and culture at Jikei University Daisan Hospital between January 2015 and December 2018. We investigated the sputum culture conversion rates for MTB after starting standard anti-TB treatment in patients with or without emphysema. Emphysema was defined as Goddard score ≥ 1 based on low attenuation area < − 950 Hounsfield Unit (HU) using computed tomography (CT). We also evaluated the effect on PTB-related CT findings prior to anti-TB treatment.

Results

Mycobacterial median time to culture conversion (TCC) in 38 PTB patients with emphysema was 52.0 days [interquartile range (IQR) 29.0–66.0 days], which was significantly delayed compared with that in 41 patients without emphysema (28.0 days, IQR 14.0–42.0 days) (p < 0.001, log-rank test). Multivariate Cox proportional hazards analysis showed that the following were associated with delayed TCC: emphysema [hazard ratio (HR): 2.43; 95% confidence interval (CI): 1.18–4.97; p = 0.015), cavities (HR: 2.15; 95% CI: 1.83–3.89; p = 0.012) and baseline time to TB detection within 2 weeks (HR: 2.95; 95% CI: 1.64–5.31; p < 0.0001). Cavities and consolidation were more often identified by CT in PTB patients with than without emphysema (71.05% vs 43.90%; p = 0.015, and 84.21% vs 60.98%; p = 0.021, respectively).

Conclusions

This study suggests that emphysema poses an increased risk of delayed TCC in PTB. Emphysema detection by CT might be a useful method for prediction of the duration of PTB treatment required for sputum negative conversion.

Alveolar Macrophage Phenotype and Compartmentalization Drive Different Pulmonary Changes in Mouse Strains Exposed to Cigarette Smoke

COPD can manifest itself with different clinical phenotypes characterized by different disease progression and response to therapy. Although a remarkable number of studies have been carried out, little is known about the mechanisms underlying phenotypes that could guide the development of viable future therapies. Several murine strains mirror some human phenotypes after smoke exposure. It was of interest to investigate in these strains whether different pattern of activation of macrophages, and their distribution in lungs, is associated to changes characterizing different phenotypes. We chose C57Bl/6, and Lck deficient mice, which show significant emphysema, DBA/2 mice that develop changes similar to those of "pulmonary fibrosis/emphysema syndrome", p66Shc ko mice that develop bronchiolitis with fibrosis but not emphysema, and finally ICR mice that do not develop changes at 7 months after smoke exposure. Unlike other strains, ICR mice show very few activated macrophages (Mac-3 positive) mostly negative to M1 or M2 markers. On the other hand, a large population of M1 macrophages predominates in the lung periphery of DBA/2, C57Bl/6 and in Lck deficient mice, where emphysema is more evident. M2 macrophages are mainly observed in subpleural and intraparenchymal areas of DBA/2 mice and around bronchioles of p66Shc ko mice where fibrotic changes are present. We observed slight but significant differences in mRNA expression of iNOS, ECF-L, arginase 1, IL-4, IL-13 and TGF-β between air- and smoke-exposed mice. These differences together with the different compartmentalization of macrophages may offer an explanation for the diversity of lesions and their distribution that we observed among the strains.

Human Rhinovirus Impairs the Innate Immune Response to Bacteria in Alveolar Macrophages in Chronic Obstructive Pulmonary Disease

Rationale: Human rhinovirus (HRV) is a common cause of chronic obstructive pulmonary disease (COPD) exacerbations. Secondary bacterial infection is associated with more severe symptoms and delayed recovery. Alveolar macrophages clear bacteria from the lung and maintain lung homeostasis through cytokine secretion. These processes are defective in COPD. The effect of HRV on macrophage function is unknown. Objectives: To investigate the effect of HRV on phagocytosis and cytokine response to bacteria by alveolar macrophages and monocyte-derived macrophages (MDM) in COPD and healthy control subjects. Methods: Alveolar macrophages were obtained by bronchoscopy and MDM by adherence. Macrophages were exposed to HRV16 (multiplicity of infection 5), polyinosinic:polycytidylic acid (poly I:C) 30 μg/ml, IFN-β 10 μg/ml, IFN-γ 10 μg/ml, or medium control for 24 hours. Phagocytosis of fluorescently labeled Haemophilus influenzae or Streptococcus pneumoniae was assessed by fluorimetry. CXCL8 (IL-8), IL-6, TNF-α (tumor necrosis factor-α), and IL-10 release was measured by ELISA. Measurements and Main Results: HRV significantly impaired phagocytosis of H. influenzae by 23% in MDM (n = 37; P = 0.004) and 18% in alveolar macrophages (n = 20; P < 0.0001) in COPD. HRV also significantly reduced phagocytosis of S. pneumoniae by 33% in COPD MDM (n = 20; P = 0.0192). There was no effect in healthy control subjects. Phagocytosis of H. influenzae was also impaired by poly I:C but not IFN-β or IFN-γ in COPD MDM. HRV significantly reduced cytokine responses to H. influenzae. The IL-10 response to H. influenzae was significantly impaired by poly I:C, IFN-β, and IFN-γ in COPD cells. Conclusions: HRV impairs phagocytosis of bacteria in COPD, which may lead to an outgrowth of bacteria. HRV also impairs cytokine responses to bacteria via the TLR3/IFN pathway, which may prevent resolution of inflammation leading to prolonged exacerbations in COPD.

Andrographolide attenuates oxidative stress injury in cigarette smoke extract exposed macrophages through inhibiting SIRT1/ERK signaling

Andrographolide (AG), an ingredient extracted from traditional Chinese herbal medicine Andrographis paniculata, has been demonstrated to have potent anti-inflammatory and anti-oxidative stress properties. The purpose of this study was to investigate whether and how AG attenuated CSE-induced mitochondrial dysfunction, inflammation and oxidative stress in RAW 264.7 cells (a mouse macrophages line). The results showed that AG significantly reduced CSE-induced upregulation of pro-inflammatory cytokines (i.e., TNF-α and IL-1β) in the RAW 264.7 cells. AG inhibited CSE-induced production of reactive oxygen species (ROS) and prevented the reduction of superoxide dismutase (SOD) and glutathione/oxidized glutathione (GSH/GSSG) ratio, indicating the anti-oxidative stress effects of AG in macrophages. AG also improved mitochondrial function and mitochondrial membrane potential. In addition, AG inhibited CSE-induced increase of heme oxygenase (HO)-1, matrix metalloproteinase (MMP)-9 and MMP-12. Moreover, AG increased SIRT1 transcription and expression, suggesting AG inhibits mitochondrial dysfunction, inflammation and oxidative stress via a SIRT1 dependent signaling. We also demonstrated that AG inhibited CSE-induced ERK phosphorylation, and treatment with PD980589, a ERK inhibitor, reversed CSE-induced inflammation and oxidative stress. These results indicated that AG may prevent COPD via the inhibition of SIRT1/ERK signaling pathway, and subsequently inhibition of mitochondrial dysfunction, inflammation, and oxidative stress in macrophages.

Lung Macrophage Functional Properties in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is caused by the chronic exposure of the lungs to toxic particles and gases. These exposures initiate a persistent innate and adaptive immune inflammatory response in the airways and lung tissues. Lung macrophages (LMs) are key innate immune effector cells that identify, engulf, and destroy pathogens and process inhaled particles, including cigarette smoke and particulate matter (PM), the main environmental triggers for COPD. The number of LMs in lung tissues and airspaces is increased in COPD, suggesting a potential key role for LMs in initiating and perpetuating the chronic inflammatory response that underpins the progressive nature of COPD. The purpose of this brief review is to discuss the origins of LMs, their functional properties (chemotaxis, recruitment, mediator production, phagocytosis and apoptosis) and changes in these properties due to exposure to cigarette smoke, ambient particulate and pathogens, as well as their persistent altered functional properties in subjects with established COPD. We also explore the potential to therapeutically modulate and restore LMs functional properties, to improve impaired immune system, prevent the progression of lung tissue destruction, and improve both morbidity and mortality related to COPD.

Animal Models Reflecting Chronic Obstructive Pulmonary Disease and Related Respiratory Disorders: Translating Pre-Clinical Data into Clinical Relevance

Chronic obstructive pulmonary disease (COPD) affects the lives of an ever-growing number of people worldwide. The lack of understanding surrounding the pathophysiology of the disease and its progression has led to COPD becoming the third leading cause of death worldwide. COPD is incurable, with current treatments only addressing associated symptoms and sometimes slowing its progression, thus highlighting the need to develop novel treatments. However, this has been limited by the lack of experimental standardization within the respiratory disease research area. A lack of coherent animal models that accurately represent all aspects of COPD clinical presentation makes the translation of promising in vitrodata to human clinical trials exceptionally challenging. Here, we review current knowledge within the COPD research field, with a focus on current COPD animal models. Moreover, we include a set of advantages and disadvantages for the selection of pre-clinical models for the identification of novel COPD treatments.

Cigarette smoke exposure redirects Staphylococcus aureus to a virulence profile associated with persistent infection

Tobacco smoking represents the leading preventable cause of death worldwide. Smoking is a recognised risk factor for several pathologies and is detrimental to host immune surveillance and defence. However, the impact of smoking on microbial residents of the nasopharyngeal cavity, in contact with cigarette smoke (CS), is lacking. Staphylococcus aureus is a major human pathogen that colonises the human nasopharynx and causes a wide range of infections. We investigated the impact of CS on specific virulence phenotypes important in S aureus pathogenesis. We observed strain-dependent differences following exposure to CS, namely growth inhibition, augmented biofilm formation, increased invasion of, and persistence within, bronchial alveolar epithelial cells. Additionally, we confirm the critical role of a functional accessory gene regulator (Agr) system in mediating increased biofilm development and host cell invasion and persistence following CS exposure. Furthermore, CS exposure resulted in reduced toxin production. Importantly, exposure of S aureus to CS accelerated the frequency of mutations and resulted in a significant increase in gentamicin-resistant small colony variant (SCV) formation. Mutational analysis revealed that CS induced SCVs emerge via the SOS response DNA mutagenic repair system. Taken together, our results suggest that CS redirects certain S aureus strains to a virulence profile associated with persistence.

Immunological and pathological effects of electronic cigarettes

Electronic cigarettes (E-cigarettes) are considered a preferable alternative to conventional cigarettes due to the lack of combustion and the absence of tobacco-specific toxicants. E-cigarettes have rapidly gained in popularity in recent years amongst both existing smokers and previous non-smokers. However, a growing literature demonstrates that E-cigarettes are not as safe as generally believed. Here, we discuss the immunological, and other, deleterious effects of E-cigarettes on a variety of cell types and host defence mechanisms in humans and in murine models. We review not only the effects of complete E-cigarette liquids, but also each of the main components-nicotine, humectants and flavourings. This MiniReview thus highlights the possible role of E-cigarettes in the pathogenesis of disease and raises awareness of the potential harm that E-cigarettes may cause.

A Comparison between Two Pathophysiologically Different yet Microbiologically Similar Lung Diseases: Cystic Fibrosis and Chronic Obstructive Pulmonary Disease

Cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD) are chronic pulmonary diseases that affect ~70,000 and 251 million individuals worldwide, respectively. Although these two diseases have distinctly different pathophysiologies, both cause chronic respiratory insufficiency that erodes quality of life and causes significant morbidity and eventually death. In both CF and COPD, the respiratory microbiome plays a major contributing role in disease progression and morbidity. Pulmonary pathogens can differ dramatically during various stages of each disease and frequently cause acute worsening of lung function due to disease exacerbation. Despite some similarities, outcome and timing/type of exacerbation can also be quite different between CF and COPD. Given these clinical distinctions, both patients and physicians should be aware of emerging therapeutic options currently being offered or in development for the treatment of lung infections in individuals with CF and COPD. Although interventions are available that prolong life and mitigate morbidity, neither disorder is curable. Both acute and chronic pulmonary infections contribute to an inexorable downward course and may trigger exacerbations, culminating in loss of lung function or respiratory failure. Knowledge of the pulmonary pathogens causing these infections, their clinical presentation, consequences, and management are, therefore, critical. In this review, we compare and contrast CF and COPD, including underlying causes, general outcomes, features of the lung microbiome, and potential treatment strategies.

The Interplay Between Immune Response and Bacterial Infection in COPD: Focus Upon Non-typeable Haemophilus influenzae

Chronic obstructive pulmonary disease (COPD) is a debilitating respiratory disease and one of the leading causes of morbidity and mortality worldwide. It is characterized by persistent respiratory symptoms and airflow limitation due to abnormalities in the lower airway following consistent exposure to noxious particles or gases. Acute exacerbations of COPD (AECOPD) are characterized by increased cough, purulent sputum production, and dyspnea. The AECOPD is mostly associated with infection caused by common cold viruses or bacteria, or co-infections. Chronic and persistent infection by non-typeable Haemophilus influenzae (NTHi), a Gram-negative coccobacillus, contributes to almost half of the infective exacerbations caused by bacteria. This is supported by reports that NTHi is commonly isolated in the sputum from COPD patients during exacerbations. Persistent colonization of NTHi in the lower airway requires a plethora of phenotypic adaptation and virulent mechanisms that are developed over time to cope with changing environmental pressures in the airway such as host immuno-inflammatory response. Chronic inhalation of noxious irritants in COPD causes a changed balance in the lung microbiome, abnormal inflammatory response, and an impaired airway immune system. These conditions significantly provide an opportunistic platform for NTHi colonization and infection resulting in a "vicious circle." Episodes of large inflammation as the consequences of multiple interactions between airway immune cells and NTHi, accumulatively contribute to COPD exacerbations and may result in worsening of the clinical status. In this review, we discuss in detail the interplay and crosstalk between airway immune residents and NTHi, and their effect in AECOPD for better understanding of NTHi pathogenesis in COPD patients.

Cigarette smoke extract interferes with placenta macrophage functions: A new mechanism to compromise placenta functions?

The success of pregnancy depends on the maternal immune system's ability to promote tolerance and host defense. This equilibrium is compromised in inflammatory and infectious impairment of placenta. Smoking during pregnancy exposes the fetus to severe complications which might result from an alteration in placenta macrophages (pMφ) functions. In this study, we assessed the effect of cigarette smoke extract (CSE) on the functions of third trimester pMφs.CSE inhibited particles uptake and the formation of multinucleated giant cells, a recently reported property of pMφs based on their ability to fuse in vitro. These alterations were associated with a CSE-induced abnormal activation of pMφs, which was characterized by an increased release of TNF, interleukin (IL)-33, and decreased IL-6 and IL-10 release. Furthermore, CSE enhanced the expression of metalloproteinase genes known to be involved in tissue remodeling. This effect of CSE on pMφs was specific because CSE affected circulating monocytes in a different way. Finally, we showed that nicotine affected in part the functional properties of pMφs. Taken together, these results showed that CSE modulated the functional activity of pMφs, which may compromise pregnancy.

MMP-12 activates protease-activated receptor-1, upregulates placenta growth factor, and leads to pulmonary emphysema

Because of the expansion of aging and smoking populations, chronic obstructive pulmonary disease (COPD) is predicted to be the third leading cause of death worldwide in 2030. Therefore, it is pertinent to develop effective therapy to improve management for COPD. Cigarette smoke-mediated protease-antiprotease imbalance is a major pathogenic mechanism for COPD and results in massive pulmonary infiltration of neutrophils and macrophages, releasing excessive neutrophil elastase (NE) and matrix metalloproteinases (MMPs). Our previous studies indicated that placenta growth factor (PGF) and PGF-triggered downstream signaling molecules mediate NE-induced lung epithelial cell apoptosis, which is a major pathogenic mechanism for pulmonary emphysema. However, the relationship between MMP-directed COPD and PGF remains elusive. We hypothesize that MMPs may upregulate PGF expression and be involved in MMP-mediated pathogenesis of COPD. In this study, we demonstrate that only MMP-12 can increase the expression of PGF by increasing early-growth response protein 1 (Egr-1) level through the activation of protease-activated receptor 1 (PAR-1). The PGF-mediated downstream signaling molecules drive caspase-3 and caspase-9-dependent apoptosis in bronchial epithelial cells. Both the upregulation of PGF by MMP-12 and PGF downstream signaling molecules with pulmonary apoptosis and emphysema were also demonstrated in animals. Given these findings, we suggest that both human COPD-associated elastases, NE, and MMP-12, upregulate PGF expression and promote the progression of emphysema and COPD.

Sodium Tanshinone IIA Sulfonate Decreases Cigarette Smoke-Induced Inflammation and Oxidative Stress via Blocking the Activation of MAPK/HIF-1α Signaling Pathway

Aberrant activation of hypoxia-inducible factor (HIF)-1α is frequently encountered and promotes oxidative stress and inflammation in chronic obstructive pulmonary disease (COPD). The present study investigated whether sodium tanshinone IIA sulfonate (STS), a water-soluble derivative of tanshinone IIA, can mediate its effect through inhibiting HIF-1α–induced oxidative stress and inflammation in cigarette smoke (CS)-induced COPD in mice. Here, we found that STS improved pulmonary function, ameliorated emphysema and decreased the infiltration of inflammatory cells in the lungs of CS-exposed mice. STS reduced CS- and cigarette smoke extract (CSE)-induced upregulation of tumor necrosis factor (TNF)-α and interleukin (IL)-1β in the lungs and macrophages. STS also inhibited CSE-induced reactive oxygen species (ROS) production, as well as the upregulation of heme oxygenase (HO)-1, NOX1 and matrix metalloproteinase (MMP)-9 in macrophages. In addition, STS suppressed HIF-1α expression in vivo and in vitro, and pretreatment with HIF-1α siRNA reduced CSE-induced elevation of TNF-α, IL-1β, and HO-1 content in the macrophages. Moreover, we found that STS inhibited CSE-induced the phosphorylation of ERK, p38 MAPK and JNK in macrophages, and inhibition of these signaling molecules significantly repressed CSE-induced HIF-1α expression. It indicated that STS inhibits CSE-induced HIF-1α expression likely by blocking MAPK signaling. Furthermore, STS also promoted HIF-1α protein degradation in CSE-stimulated macrophages. Taken together, these results suggest that STS prevents COPD development possibly through the inhibition of HIF-1α signaling, and may be a novel strategy for the treatment of COPD.

Matrix metalloproteinases in emphysema

Several studies have implicated a causative role for specific matrix metalloproteinases (MMPs) in the development and progression of cigarette smoke-induced chronic obstructive pulmonary disease (COPD) and its severe sequela, emphysema. However, the precise function of any given MMP in emphysema remains an unanswered question. Emphysema results from the degradation of alveolar elastin - among other possible mechanisms - a process that is often thought to be caused by elastolytic proteinases made by macrophages. In this article, we discuss the data suggesting, supporting, or refuting causative roles of macrophage-derived MMPs, with a focus on MMPs-7, -9, -10, -12, and 28, in both the human disease and mouse models of emphysema. Findings from experimental models suggest that some MMPs, such as MMP-12, may directly breakdown elastin, whereas others, particularly MMP-10 and MMP-28, promote the development of emphysema by influencing the proteolytic and inflammatory activities of macrophages.

Dysregulated Functions of Lung Macrophage Populations in COPD

Chronic obstructive pulmonary disease (COPD) is a diverse respiratory disease characterised by bronchiolitis, small airway obstruction, and emphysema. Innate immune cells play a pivotal role in the disease's progression, and in particular, lung macrophages exploit their prevalence and strategic localisation to orchestrate immune responses. To date, alveolar and interstitial resident macrophages as well as blood monocytes have been described in the lungs of patients with COPD contributing to disease pathology by changes in their functional repertoire. In this review, we summarise recent evidence from human studies and work with animal models of COPD with regard to altered functions of each of these myeloid cell populations. We primarily focus on the dysregulated capacity of alveolar macrophages to secrete proinflammatory mediators and proteases, induce oxidative stress, engulf microbes and apoptotic cells, and express surface and intracellular markers in patients with COPD. In addition, we discuss the differences in the responses between alveolar macrophages and interstitial macrophages/monocytes in the disease and propose how the field should advance to better understand the implications of lung macrophage functions in COPD.

Elastin in lung development and disease pathogenesis

Elastin is expressed in most tissues that require elastic recoil. The protein first appeared coincident with the closed circulatory system, and was critical for the evolutionary success of the vertebrate lineage. Elastin is expressed by multiple cell types in the lung, including mesothelial cells in the pleura, smooth muscle cells in airways and blood vessels, endothelial cells, and interstitial fibroblasts. This highly crosslinked protein associates with fibrillin-containing microfibrils to form the elastic fiber, which is the physiological structure that functions in the extracellular matrix. Elastic fibers can be woven into many different shapes depending on the mechanical needs of the tissue. In large pulmonary vessels, for example, elastin forms continuous sheets, or lamellae, that separate smooth muscle layers. Outside of the vasculature, elastic fibers form an extensive fiber network that originates in the central bronchi and inserts into the distal airspaces and visceral pleura. The fibrous cables form a looping system that encircle the alveolar ducts and terminal air spaces and ensures that applied force is transmitted equally to all parts of the lung. Normal lung function depends on proper secretion and assembly of elastin, and either inhibition of elastin fiber assembly or degradation of existing elastin results in lung dysfunction and disease.

Involvement of Oxidative Stress in COPD

Chronic obstructive pulmonary disease (COPD) is a disease that affects the lungs and is defined by a variety of symptoms that combined with co-morbidities lead to a decline of the patients quality of life. The principal etiology of chronic obstructive pulmonary disease is smoking and air pollution that lead to oxidative and carbonyl stress. This review based on a search of PubMed, OxLIP+/SOLO (Bodleian Libraries) database (from 1991 to 2017) of relevant articles based on assessment of oxidative stress pathways involvement in COPD. Intracellular reactions that take place in organisms and aerobic cells have as by-products reactive oxygen species (ROS) and free radicals. Oxidative stress involved in pathogenesis of COPD is the result of lowered antioxidative potential combined with increased burden of oxidants. Molecular mechanisms underlying COPD pathways are not yet well understood, despite intensive research all over the world. A change in balance between Oxidants and antioxidants in the lungs as well as within the circulatory system, gene polymorphisms, and activation of transcription factors contribute to the molecular pathogenesis of COPD. Future research is needed in order to identify which patients will develop in time a susceptibility to damage caused by ROS and to determine if controlling ROS will have an effect on the progression of COPD.

Cellular and molecular mechanisms of asthma and COPD

Asthma and chronic obstructive pulmonary disease (COPD) both cause airway obstruction and are associated with chronic inflammation of the airways. However, the nature and sites of the inflammation differ between these diseases, resulting in different pathology, clinical manifestations and response to therapy. In this review, the inflammatory and cellular mechanisms of asthma and COPD are compared and the differences in inflammatory cells and profile of inflammatory mediators are highlighted. These differences account for the differences in clinical manifestations of asthma and COPD and their response to therapy. Although asthma and COPD are usually distinct, there are some patients who show an overlap of features, which may be explained by the coincidence of two common diseases or distinct phenotypes of each disease. It is important to better understand the underlying cellular and molecular mechanisms of asthma and COPD in order to develop new treatments in areas of unmet need, such as severe asthma, curative therapy for asthma and effective anti-inflammatory treatments for COPD.

Airway inflammation in chronic obstructive pulmonary disease (COPD): a true paradox

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is primarily an airway condition, which mainly affects cigarette smokers and presents with shortness of breath that is progressive and poorly reversible. In COPD research, there has been a long held belief that airway disease progression is due to inflammation. Although this may be true in the airway lumen with innate immunity activated by the effect of smoke or secondary to infection, the accurate picture of inflammatory cells in the airway wall, where the pathophysiological COPD remodeling occurs, is uncertain and debatable. Areas covered: The current review provides a comprehensive literature survey of the changes in the main inflammatory cells in human COPD patients and focuses on contrarian views that affect the prevailing dogma on inflammation. The review also delves into the role of oxidative stress and inflammasomes in modulating the immune response in COPD. Further, the effects of inflammation in affecting the epithelium, fibroblasts, and airway remodeling are discussed. Expert commentary: Inflammation as a driving force for airway wall damage and remodelling in early COPD is at the very least 'oversimplified' and is likely to be misleading. This has serious implications for rational thinking about the illness, including pathogenesis and designing therapy.

Evaluation of a biomimetic 3D substrate based on the Human Elastin-like Polypeptides (HELPs) model system for elastolytic activity detection

Elastin is a fibrous protein that confers elasticity to tissues such as skin, arteries and lung. It is extensively cross-linked, highly hydrophobic and insoluble. Nevertheless, elastin can be hydrolysed by bacterial proteases in infectious diseases, resulting in more or less severe tissue damage. Thus, development of substrates able to reliably and specifically detect pathogen-secreted elastolytic activity is needed to improve the in vitro evaluation of the injury that bacterial proteases may provoke. In this work, two human biomimetic elastin polypeptides, HELP and HELP1, as well as the matrices derived from HELP, have been probed as substrates for elastolytic activity detection. Thirty strains of Pseudomonas aeruginosa isolated from cystic fibrosis patients were analyzed in parallel with standard substrates, to detect proteolytic and elastolytic activity. Results point to the HELP-based 3D matrix as an interesting biomimetic model of elastin to assess bacterial elastolytic activity in vitro. Moreover, this model substrate enables to further elucidate the mechanism underlying elastin degradation at molecular level, as well as to develop biomimetic material-based devices responsive to external stimuli.

Matrix Metalloproteinase-28 Is a Key Contributor to Emphysema Pathogenesis

Chronic obstructive pulmonary disease (COPD) comprises chronic bronchitis and emphysema, and is a leading cause of morbidity and mortality. Because tissue destruction is the prominent characteristic of emphysema, extracellular proteinases, particularly those with elastolytic ability, are often considered to be key drivers in this disease. Several human and mouse studies have implicated roles for matrix metalloproteinases (MMPs), particularly macrophage-derived proteinases, in COPD pathogenesis. MMP-28 is expressed by the pulmonary epithelium and macrophage, and we have found that it regulates macrophage recruitment and polarization. We hypothesized that MMP-28 has contributory roles in emphysema via alteration of macrophage numbers and activation. Because of the established association of emphysema pathogenesis to macrophage influx, we evaluated the inflammatory changes and lung histology of Mmp28^-/- mice exposed to 3 and 6 months of cigarette smoke. At earlier time points, we found altered macrophage polarization in the smoke-exposed Mmp28^-/- lung consistent with other published findings that MMP-28 regulates macrophage activation. At both 3 and 6 months, Mmp28^-/- mice had blunted inflammatory responses more closely resembling nonsmoked mice, with a reduction in neutrophil recruitment and CXCL1 chemokine expression. By 6 months, Mmp28^-/- mice were protected from emphysema. These results highlight a previously unrecognized role for MMP-28 in promoting chronic lung inflammation and tissue remodeling induced by cigarette smoke and highlight another potential target to modulate COPD.