Animal models for COPD

LincR-PPP2R5C regulates IL-1β ubiquitination in macrophages and promotes airway inflammation and emphysema in a murine model of COPD

Chronic obstructive pulmonary disease (COPD) is a common disease with high global morbidity and mortality. Macrophages release IL-1β and orchestrate airway inflammation in COPD. Previously, we explored the role of a new lncRNA, LincR-PPP2R5C, in regulating Th2 cells in asthma. Here, we established a murine model of COPD and explored the roles and mechanisms by which LincR-PPP2R5C regulates IL-1β in macrophages. LincR-PPP2R5C was highly expressed in pulmonary macrophages from COPD-like mice. LincR-PPP2R5C deficiency ameliorated emphysema and pulmonary inflammation, as characterized by reduced IL-1β in macrophages. Unexpectedly, in both lung tissues and macrophages, LincR-PPP2R5C deficiency decreased the expression of the IL-1β protein but not the IL-1β mRNA. Furthermore, we found that LincR-PPP2R5C deficiency increased the level of ubiquitinated IL-1β in macrophages, which was mediated by PP2A activity. Targeting PP2A with FTY720 decreased IL-1β and improved COPD. In conclusion, LincR-PPP2R5C regulates IL-1β ubiquitination by affecting PP2A activity in macrophages, contributing to the airway inflammation and emphysema in a murine model of COPD. PP2A and IL-1β ubiquitination in macrophages might be new therapeutic avenues for COPD therapy.

ADAM-10 Regulates MMP-12 during Lipopolysaccharide-Induced Inflammatory Response in Macrophages

A disintegrin and metalloprotease 10 (ADAM-10), a member of the ADAM protease family, has biological activities related to TNF-α activation, cell adhesion, and migration, among other functions. Macrophages are important immune cells that are involved in the inflammatory response of the body. ADAM-10 is involved in inflammatory responses, but the specific regulatory mechanisms are not fully understood. In this study, we investigated the regulatory mechanism of ADAM-10 in the lipopolysaccharide-promoted proliferation (LPS) of the macrophage inflammatory response. Differentially expressed or regulated proteins were identified in interfered ADAM-10 (sh ADAM-10) macrophages using tandem mass tag (TMT) proteomics. The changes and regulatory role of ADAM-10 during LPS-induced inflammatory response in normal, interfering, and overexpressing ADAM-10 (EX ADAM-10) cells were determined. Results indicated that ADAM-10 interference affected inflammation-related pathways and reduced matrix metalloproteinase 12 (MMP-12) protein levels, as identified by TMT proteomics. In normal cells, LPS decreased ADAM-10 gene expression, but promoted ADAM-10 secretion, MMP-12 and TNF-α gene expression, and MMP-12, iNOS, IL-10, and cyclinD1 protein expression. Additionally, ADAM-10 knockdown decreased macrophage viability in sh-ADAM-10 cells. Moreover, an MMP-12 inhibitor had no impact on the viability effect of LPS on cells or the expression of ADAM-10. iNOS expression decreased, whereas IL-10 expression increased after ADAM-10 depletion. ADAM-10 knockdown decreased MMP-12, iNOS, TNF-α, IL-1β, and FKN, while overexpression had an opposite effect. ADAM-10 overexpression further increased MMP-12, iNOS, and TNF-α gene expression in response to LPS. Cell viability was increased in EX ADAM-10 cells, and ADAM-10 secretion was further increased in the EX and LPS groups. Flow cytometry and immunofluorescence staining revealed that EX-ADAM 10 cells had increased iNOS expression, which acted as an IL-6 expression driver. In summary, we found that ADAM-10 is activated by LPS and positively participates in LPS-stimulated macrophage inflammatory responses by positively regulating MMP-12 during the inflammatory process.

Novel pharmacological strategies to treat cognitive dysfunction in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major incurable global health burden and currently the 3rd largest cause of death in the world, with approximately 3.23 million deaths per year. Globally, the financial burden of COPD is approximately €82 billion per year and causes substantial morbidity and mortality. Importantly, much of the disease burden and health care utilisation in COPD is associated with the management of its comorbidities and viral and bacterial-induced acute exacerbations (AECOPD). Recent clinical studies have shown that cognitive dysfunction is present in up to 60% of people with COPD, with impairments in executive function, memory, and attention, impacting on important outcomes such as quality of life, hospitalisation and survival. The high prevalence of cognitive dysfunction in COPD may also help explain the insufficient adherence to therapeutic plans and strategies, thus worsening disease progression in people with COPD. However, the mechanisms underlying the impaired neuropathology and cognition in COPD remain largely unknown. In this review, we propose that the observed pulmonary oxidative burden and inflammatory response of people with COPD 'spills over' into the systemic circulation, resulting in damage to the brain and leading to cognitive dysfunction. As such, drugs targeting the lungs and comorbidities concurrently represent an exciting and unique therapeutic opportunity to treat COPD and cognitive impairments, which may lead to the production of novel targets to prevent and reverse the debilitating and life-threatening effects of cognitive dysfunction in COPD.

RIP3-dependent necroptosis contributes to the pathogenesis of chronic obstructive pulmonary disease

Necroptosis has emerged as a potential mechanism in the pathogenesis of chronic obstructive pulmonary disease (COPD). Here, we found that markers of necroptosis, including high mobility group box 1 release and phosphorylation of mixed lineage kinase domain-like protein (p-MLKL), were markedly induced in the late stage of cigarette smoking-induced (CS-induced) emphysema in mouse lung tissue as well as in lung epithelial cells and organoids with higher dosage of or more prolonged exposure to cigarette smoking extract (CSE). Apoptotic signals were also detected and maximally induced in the early stage of CS-exposed mice and CSE-treated epithelial cells. Inhibition of apoptosis by Z-VAD, a pan-caspase inhibitor, switched the cellular stress to enhanced necroptosis in lung epithelial cells and organoids treated with CSE. Depletion or inhibition of receptor-interacting protein kinase 3 (RIP3) or MLKL attenuated the CSE-induced cell death, suggesting that necroptosis contributes to CSE-induced cell death. Silencing or inhibition of RIP1 had no protective effect, indicating a RIP1-independent RIP3 activation pathway. CSE-induced necroptosis released more damage-associated molecular patterns and evoked greater engulfment but slower clearance by bone marrow-derived macrophages, leading to enhanced expression of proinflammatory cytokines Tnfα and Il6. Finally, our in vivo data verified that inhibition of necroptosis by RIP3 inhibitor GSK'872 protected mice from CS-induced emphysema and suppressed the lung inflammation. In conclusion, we provide evidence that necroptosis contributes to the pathogenesis of COPD. Targeting RIP3 and its downstream pathway may be an effective therapy for COPD.

Nasally Administered Lactococcus lactis Secreting Heme Oxygenase-1 Attenuates Murine Emphysema

Emphysema, a type of lung-destroying condition associated with chronic obstructive pulmonary disease (COPD), is an inflammatory lung disease mainly due to cigarette smoke exposure. As there is no curative therapy, prevention should be considered first by cessation of smoking to avoid exposure to oxidative stresses and inflammatory mediators. In addition, therapies involving antioxidative and/or anti-inflammatory agents such as heme oxygenase (HO)-1 are candidate treatments. We developed a new tool using genetically modified Lactococcus lactis to deliver recombinant HO-1 to the lungs. Using an elastase-induced emphysema model mimicking COPD, we evaluated the effect of nasally administered L. lactis secreting HO-1 (HO-1 lactis) on cellular and molecular responses in the lungs and further disease progression. Nasally administered HO-1 lactis resulted in (1) overexpression of HO-1 in the lungs and serum and (2) attenuation of emphysema progression evaluated both physiologically and morphologically. There was a transient 5-10% weight loss compared to baseline through trafficking to the lungs when administering 1.0 × 10⁹ cells/mouse; however, this did not impact either survival or final body weight. These results suggest that delivering HO-1 using genetically modified L. lactis through the airways could be a safe and potentially effective therapeutic approach for COPD.

Does gallic acid improve cardiac function by attenuation of oxidative stress and inflammation in an elastase-induced lung injury?

Objective(s):

Cardiovascular disease has an important role in mortality caused by lung injury. Emphysema is associated with impaired pulmonary gas exchange efficiency and airflow limitation associated with small airway inflammation. The aim was to evaluate the interactions between lung injury, inflammation, and cardiovascular disease. Since gallic acid has antioxidant and anti-inflammatory effects, we hypothesized that gallic acid protects the lung and the related heart dysfunction in elastase-induced lung injury.

Materials and Methods:

Forty-eight Sprague-Dawley male rats were randomly divided into six groups: Control, Porcine pancreatic elastase (PPE) , PPE+GA, and 3 groups for different doses of gallic acid (GA 7.5, GA 15, GA 30 mg/kg). PPE was injected intra-tracheally on days 1 and 10 of the test. In each group, electrocardiography, hemodynamic parameters, oxidative stress, and bronchoalveolar lavage fluid were examined.

Results:

PPE administration showed a decrease in HR and QRS voltage of electrocardiogram parameters, as well as in hemodynamic parameters (P<0.05, P<0.01, and P<0.001) and superoxide dismutase (SOD) (P<0.05). Tumor Necrosis Factor α (TNF-α) (P<0.001), interleukin 6 (IL-6) (P<0.001), interleukin 6 (MDA) (P<0.001), and the total number of white blood cells (P<0.001) showed an increase in PPE groups. Gallic acid preserved the values of hemodynamic properties, oxidative stress, inflammation, and electrocardiogram parameters in comparison to the PPE group.

Conclusion:

Briefly, this study showed the valuable effect of gallic acid in cardiac dysfunction related to elastase-induced lung injury. These findings suggested that gallic acid, as a natural antioxidant, has a potential therapeutic effect on preventing oxidative stress, inflammation, and subsequent cardiovascular disease.

Cigarette smoke-initiated autoimmunity facilitates sensitisation to elastin-induced COPD-like pathologies in mice

It is currently not understood whether cigarette smoke exposure facilitates sensitisation to self-antigens and whether ensuing auto-reactive T cells drive chronic obstructive pulmonary disease (COPD)-associated pathologies.To address this question, mice were exposed to cigarette smoke for 2 weeks. Following a 2-week period of rest, mice were challenged intratracheally with elastin for 3 days or 1 month. Rag1^-/- , Mmp12^-/- , and Il17a^-/- mice and neutralising antibodies against active elastin fragments were used for mechanistic investigations. Human GVAPGVGVAPGV/HLA-A*02:01 tetramer was synthesised to assess the presence of elastin-specific T cells in patients with COPD.We observed that 2 weeks of cigarette smoke exposure induced an elastin-specific T cell response that led to neutrophilic airway inflammation and mucus hyperproduction following elastin recall challenge. Repeated elastin challenge for 1 month resulted in airway remodelling, lung function decline and airspace enlargement. Elastin-specific T cell recall responses were dose dependent and memory lasted for over 6 months. Adoptive T cell transfer and studies in T cells deficient Rag1^-/- mice conclusively implicated T cells in these processes. Mechanistically, cigarette smoke exposure-induced elastin-specific T cell responses were matrix metalloproteinase (MMP)12-dependent, while the ensuing immune inflammatory processes were interleukin 17A-driven. Anti-elastin antibodies and T cells specific for elastin peptides were increased in patients with COPD.These data demonstrate that MMP12-generated elastin fragments serve as a self-antigen and drive the cigarette smoke-induced autoimmune processes in mice that result in a bronchitis-like phenotype and airspace enlargement. The study provides proof of concept of cigarette smoke-induced autoimmune processes and may serve as a novel mouse model of COPD.

E-cigarette-induced pulmonary inflammation and dysregulated repair are mediated by nAChR α7 receptor: role of nAChR α7 in SARS-CoV-2 Covid-19 ACE2 receptor regulation

Electronic cigarette (e-cig) vaping is increasing rapidly in the United States, as e-cigs are considered less harmful than combustible cigarettes. However, limited research has been conducted to understand the possible mechanisms that mediate toxicity and pulmonary health effects of e-cigs. We hypothesized that sub-chronic e-cig exposure induces inflammatory response and dysregulated repair/extracellular matrix (ECM) remodeling, which occur through the α7 nicotinic acetylcholine receptor (nAChRα7). Adult wild-type (WT), nAChRα7 knockout (KO), and lung epithelial cell-specific KO (nAChRα7 CreCC10) mice were exposed to e-cig aerosol containing propylene glycol (PG) with or without nicotine. Bronchoalveolar lavage fluids (BALF) and lung tissues were collected to determine e-cig induced inflammatory response and ECM remodeling, respectively. Sub-chronic e-cig exposure with nicotine increased inflammatory cellular influx of macrophages and T-lymphocytes including increased pro-inflammatory cytokines in BALF and increased SARS-Cov-2 Covid-19 ACE2 receptor, whereas nAChRα7 KO mice show reduced inflammatory responses associated with decreased ACE2 receptor. Interestingly, matrix metalloproteinases (MMPs), such as MMP2, MMP8 and MMP9, were altered both at the protein and mRNA transcript levels in female and male KO mice, but WT mice exposed to PG alone showed a sex-dependent phenotype. Moreover, MMP12 was increased significantly in male mice exposed to PG with or without nicotine in a nAChRα7-dependent manner. Additionally, sub-chronic e-cig exposure with or without nicotine altered the abundance of ECM proteins, such as collagen and fibronectin, significantly in a sex-dependent manner, but without the direct role of nAChRα7 gene. Overall, sub-chronic e-cig exposure with or without nicotine affected lung inflammation and repair responses/ECM remodeling, which were mediated by nAChRα7 in a sex-dependent manner.

E-cigarette-Induced Pulmonary Inflammation and Dysregulated Repair are Mediated by nAChR α7 Receptor: Role of nAChR α7 in ACE2 Covid-19 receptor regulation

Electronic cigarette (e-cig) vaping is increasing rapidly in the United States, as e-cigs are considered less harmful than combustible cigarettes. However, limited research has been conducted to understand the possible mechanism that mediate, toxicity and pulmonary health effects of e-cigs. We hypothesized that sub-chronic e-cig exposure induces inflammatory response and dysregulated repair/extracellular matrix (ECM) remodeling, which occur through the α7 nicotinic acetylcholine receptor (nAChR α7). Adult wild-type (WT), nAChRα7 knockout (KO), and lung epithelial cell-specific KO (nAChRα7 CreCC10) mice were exposed to e-cig aerosol containing propylene glycol (PG) with or without nicotine. Bronchoalveolar lavage fluids (BALF) and lungs tissues were collected to determine e-cig induced inflammatory response and ECM remodeling, respectively. Sub-chronic e-cig exposure with nicotine increased the inflammatory cellular influx of macrophages and T-lymphocytes including increased pro-inflammatory cytokines in BALF and increased ACE2 Covid-19 receptor, whereas nAChR α7 KO mice show reduced inflammatory responses associated with decreased ACE2 receptor. Interestingly, matrix metalloproteinases (MMPs), such as MMP2, MMP8, and MMP9 were altered both at the protein and mRNA transcript levels in female and male, but WT mice exposed to PG alone showed a sex-dependent phenotype. Moreover, MMP12 was increased significantly in male mice exposed to PG with or without nicotine in a nAChR α7-dependent manner. Additionally, sub-chronic e-cig exposure with or without nicotine altered the abundance of ECM proteins, such as collagen and fibronectin significantly in a sex-dependent manner, but without the direct role of nAChR α7 gene. Overall, sub-chronic e-cig exposure with or without nicotine affected lung inflammation and repair responses/ECM remodeling, which were mediated by nAChR α7 in a sex-dependent manner.

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.

Attached stratified mucus separates bacteria from the epithelial cells in COPD lungs

The respiratory tract is normally kept essentially free of bacteria by cilia-mediated mucus transport, but in chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF), bacteria and mucus accumulates instead. To address the mechanisms behind the mucus accumulation, the proteome of bronchoalveolar lavages from COPD patients and mucus collected in an elastase-induced mouse model of COPD was analyzed, revealing similarities with each other and with the protein content in colonic mucus. Moreover, stratified laminated sheets of mucus were observed in airways from patients with CF and COPD and in elastase-exposed mice. On the other hand, the mucus accumulation in the elastase model was reduced in Muc5b-KO mice. While mucus plugs were removed from airways by washing with hypertonic saline in the elastase model, mucus remained adherent to epithelial cells. Bacteria were trapped on this mucus, whereas, in non-elastase-treated mice, bacteria were found on the epithelial cells. We propose that the adherence of mucus to epithelial cells observed in CF, COPD, and the elastase-induced mouse model of COPD separates bacteria from the surface cells and, thus, protects the respiratory epithelium.

Experimental animal models for COPD: a methodological review

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is a progressive disorder that makes the breathing difficult and is characterized by pathological conditions ranging from chronic inflammation to tissue proteolysis. With regard to ethical issues related to the studies on patients with COPD, the use of animal models of COPD is inevitable. Animal models improve our knowledge about the basic mechanisms underlying COPD physiology, pathophysiology and treatment. Although these models are only able to mimic some of the features of the disease, they are valuable for further investigation of mechanisms involved in human COPD.

METHODS

We searched the literature available in Google Scholar, PubMed and ScienceDirect databases for English articles published until November 2015. For this purpose, we used 5 keywords for COPD, 3 for animal models, 4 for exposure methods, 3 for pathophysiological changes and 3 for biomarkers. One hundred and fifty-one studies were considered eligible for inclusion in this review.

RESULTS

According to the reviewed articles, animal models of COPD are mainly induced in mice, guinea pigs and rats. In most of the studies, this model was induced by exposure to cigarette smoke (CS), intra-tracheal lipopolysaccharide (LPS) and intranasal elastase. There were variations in time course and dose of inducers used in different studies. The main measured parameters were lung pathological data and lung inflammation (both inflammatory cells and inflammatory mediators) in most of the studies and tracheal responsiveness (TR) in only few studies.

CONCLUSION

The present review provides various methods used for induction of animal models of COPD, different animals used (mainly mice, guinea pigs and rats) and measured parameters. The information provided in this review is valuable for choosing appropriate animal, method of induction and selecting parameters to be measured in studies concerning COPD.

Neutrophilic Inflammation in the Immune Responses of Chronic Obstructive Pulmonary Disease: Lessons from Animal Models

Chronic obstructive pulmonary disease (COPD) is a major cause of mortality worldwide, which is characterized by chronic bronchitis, destruction of small airways, and enlargement/disorganization of alveoli. It is generally accepted that the neutrophilic airway inflammation observed in the lungs of COPD patients is intrinsically linked to the tissue destruction and alveolar airspace enlargement, leading to disease progression. Animal models play an important role in studying the underlying mechanisms of COPD as they address questions involving integrated whole body responses. This review aims to summarize the current animal models of COPD, focusing on their advantages and disadvantages on immune responses and neutrophilic inflammation. Also, we propose a potential new animal model of COPD, which may mimic the most characteristics of human COPD pathogenesis, including persistent moderate-to-high levels of neutrophilic inflammation.

Plausible Roles for RAGE in Conditions Exacerbated by Direct and Indirect (Secondhand) Smoke Exposure

Approximately 1 billion people smoke worldwide, and the burden placed on society by primary and secondhand smokers is expected to increase. Smoking is the leading risk factor for myriad health complications stemming from diverse pathogenic programs. First- and second-hand cigarette smoke contains thousands of constituents, including several carcinogens and cytotoxic chemicals that orchestrate chronic inflammatory responses and destructive remodeling events. In the current review, we outline details related to compromised pulmonary and systemic conditions related to smoke exposure. Specifically, data are discussed relative to impaired lung physiology, cancer mechanisms, maternal-fetal complications, cardiometabolic, and joint disorders in the context of smoke exposure exacerbations. As a general unifying mechanism, the receptor for advanced glycation end-products (RAGE) and its signaling axis is increasingly considered central to smoke-related pathogenesis. RAGE is a multi-ligand cell surface receptor whose expression increases following cigarette smoke exposure. RAGE signaling participates in the underpinning of inflammatory mechanisms mediated by requisite cytokines, chemokines, and remodeling enzymes. Understanding the biological contributions of RAGE during cigarette smoke-induced inflammation may provide critically important insight into the pathology of lung disease and systemic complications that combine during the demise of those exposed.

A Plant Proteinase Inhibitor from Enterolobium contortisiliquum Attenuates Pulmonary Mechanics, Inflammation and Remodeling Induced by Elastase in Mice

Proteinase inhibitors have been associated with anti-inflammatory and antioxidant activities and may represent a potential therapeutic treatment for emphysema. Our aim was to evaluate the effects of a plant Kunitz proteinase inhibitor, Enterolobium contortisiliquum trypsin inhibitor (EcTI), on several aspects of experimental elastase-induced pulmonary inflammation in mice. C57/Bl6 mice were intratracheally administered elastase (ELA) or saline (SAL) and were treated intraperitoneally with EcTI (ELA-EcTI, SAL-EcTI) on days 1, 14 and 21. On day 28, pulmonary mechanics, exhaled nitric oxide (ENO) and number leucocytes in the bronchoalveolar lavage fluid (BALF) were evaluated. Subsequently, lung immunohistochemical staining was submitted to morphometry. EcTI treatment reduced responses of the mechanical respiratory system, number of cells in the BALF, and reduced tumor necrosis factor-α (TNF-α), matrix metalloproteinase-9 (MMP-9), matrix metalloproteinase-12 (MMP-12), tissue inhibitor of matrix metalloproteinase (TIMP-1), endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS)-positive cells and volume proportion of isoprostane, collagen and elastic fibers in the airways and alveolar walls compared with the ELA group. EcTI treatment reduced elastase induced pulmonary inflammation, remodeling, oxidative stress and mechanical alterations, suggesting that this inhibitor may be a potential therapeutic tool for chronic obstructive pulmonary disease (COPD) management.

The Plant-Derived Bauhinia bauhinioides Kallikrein Proteinase Inhibitor (rBbKI) Attenuates Elastase-Induced Emphysema in Mice

Background. Elastase mediates important oxidative actions during the development of chronic obstructive pulmonary disease (COPD). However, few resources for the inhibition of elastase have been investigated. Our study evaluated the ability of the recombinant plant derived Bauhinia bauhinioides Kallikrein proteinase Inhibitor (rBbKI) to modulate elastase-induced pulmonary inflammation. Methods. C57Bl/6 mice were given intratracheal elastase (ELA group) or saline (SAL group) and were treated intraperitoneally with rBbKI (ELA-rBbKI and SAL-rBbKI groups). At day 28, the following analyses were performed: (I) lung mechanics, (II) exhaled nitric oxide (ENO), (III) bronchoalveolar lavage fluid (BALF), and (IV) lung immunohistochemical staining. Results. In addition to decreasing mechanical alterations and alveolar septum disruption, rBbKI reduced the number of cells in the BALF and decreased the cellular expression of TNF-α, MMP-9, MMP-12, TIMP-1, eNOS, and iNOS in airways and alveolar walls compared with the ELA group. rBbKI decreased the volume proportion of 8-iso-PGF2α, collagen, and elastic fibers in the airways and alveolar walls compared with the ELA group. A reduction in the number of MUC-5-positive cells in the airway walls was also observed. Conclusion. rBbKI reduced elastase-induced pulmonary inflammation and extracellular matrix remodeling. rBbKI may be a potential pharmacological tool for COPD treatment.

Barriers to inhaled gene therapy of obstructive lung diseases: A review

Knowledge of genetic origins of obstructive lung diseases has made inhaled gene therapy an attractive alternative to the current standards of care that are limited to managing disease symptoms. Initial lung gene therapy clinical trials occurred in the early 1990s following the discovery of the genetic defect responsible for cystic fibrosis (CF), a monogenic disorder. However, despite over two decades of intensive effort, gene therapy has yet to help patients with CF or any other obstructive lung disease. The slow progress is due in part to poor understanding of the biological barriers to inhaled gene therapy. Encouragingly, clinical trials have shown that inhaled gene therapy with various viral vectors and non-viral gene vectors is well tolerated by patients, and continued research has provided valuable lessons and resources that may lead to future success of this therapeutic strategy. In this review, we first introduce representative obstructive lung diseases and examine limitations of currently available therapeutic options. We then review key components for successful execution of inhaled gene therapy, including gene delivery systems, primary physiological barriers and strategies to overcome them, and advances in preclinical disease models with which the most promising systems may be identified for human clinical trials.

Peritendinous elastase treatment induces tendon degeneration in rats: A potential model of tendinopathy in vivo

The purpose of this study was to investigate the role of elastase on tendinopathy, as well as to evaluate the potential for peritendinous injections of elastase into rats to cause tendinopathy. We first investigated the expression of elastase in the tendons of patients with tendinopathy, and then established the effects of elastase injection on the Achilles tendons of rats. Ultrasonographic and incapacitance testing was used to conduct tests for 8 weeks. Tendon tissues were collected for histological observation and protein levels of collagen type I and type III were detected using Western blotting. The percentage of elastase-positive cells increased in human specimens with grades II and III tendinopathy. The rat model demonstrated that the thickness of the tendon increased after elastase injection during Week 2-8. Hypercellularity and focal lesions were detected after Week 2. The expression of elastase was increased and elastin was decreased in Week 8. Collagen type I expression was decreased, but type III was increased in Week 4. These results suggested that elastase may be involved in the development of chronic tendinopathy, and that peritendinous injection of elastase may result in tendinopathy in rats.

Induction and regulation of murine emphysema by elastin peptides

Emphysema is the major component of chronic obstructive pulmonary disease (COPD). During emphysema, elastin breakdown in the lung tissue originates from the release of large amounts of elastase by inflammatory cells. Elevated levels of elastin-derived peptides (EP) reflect massive pulmonary elastin breakdown in COPD patients. Only the EP containing the GXXPG conformational motif with a type VIII β-turn are elastin receptor ligands inducing biological activities. In addition, the COOH-terminal glycine residue of the GXXPG motif seems a prerequisite to the biological activity. In this study, we endotracheally instilled C57BL/6J mice with GXXPG EP and/or COOH-terminal glycine deleted-EP whose sequences were designed by molecular dynamics and docking simulations. We investigated their effect on all criteria associated with the progression of murine emphysema. Bronchoalveolar lavages were recovered to analyze cell profiles by flow cytometry and lungs were prepared to allow morphological and histological analysis by immunostaining and confocal microscopy. We observed that exposure of mice to EP elicited hallmark features of emphysema with inflammatory cell accumulation associated with increased matrix metalloproteinases and desmosine expression and of remodeling of parenchymal tissue. We also identified an inactive COOH-terminal glycine deleted-EP that retains its binding-activity to EBP and that is able to inhibit the in vitro and in vivo activities of emphysema-inducing EP. This study demonstrates that EP are key actors in the development of emphysema and that they represent pharmacological targets for an alternative treatment of emphysema based on the identification of EP analogous antagonists by molecular modeling studies.

Tobacco experimental model to induce urinary bladder neoplasms

OBJECTIVE

to develop an experimental model of exposure to tobacco burning (cigarette) products to assess the effects of its chronic use in relation to cancers of the bladder.

METHODS

the animals were chronically exposed to the burning tobacco products in a semi-open chamber to simulate smoking. Thirty young Wistar rats were divided into two groups: one with 20 animals simulating smoking for six months, and ten not exposed control animals for the same period. After exposure by inhalation of cigarette smoke, animals were euthanized and subjected to histopathological study of the bladder wall.

RESULTS

no tumor was found but mild and non significant alterations. The studies of hemo-oximetry (carboxyhemoglobin and methemoglobin) and the concentration of carbon dioxide (CO2) confirm that the animals were exposed to high concentrations of tobacco smoke and its derivatives.

CONCLUSION

no bladder mucosal neoplasia was found in the pathological study of animals. The developed experimental models were highly efficient, practical and easy to use and can be used in other similar studies to determine the harmful effects caused by smoking.

Alendronate inhalation ameliorates elastase-induced pulmonary emphysema in mice by induction of apoptosis of alveolar macrophages

Alveolar macrophages play a crucial role in the pathogenesis of emphysema, for which there is currently no effective treatment. Bisphosphonates are widely used to treat osteoclast-mediated bone diseases. Here we show that delivery of the nitrogen-containing bisphosphonate alendronate via aerosol inhalation ameliorates elastase-induced emphysema in mice. Inhaled, but not orally ingested, alendronate inhibits airspace enlargement after elastase instillation, and induces apoptosis of macrophages in bronchoalveolar fluid via caspase-3- and mevalonate-dependent pathways. Cytometric analysis indicates that the F4/80(+)CD11b(high)CD11c(mild) population characterizing inflammatory macrophages, and the F4/80(+)CD11b(mild)CD11c(high) population defining resident alveolar macrophages take up substantial amounts of the bisphosphonate imaging agent OsteoSense680 after aerosol inhalation. We further show that alendronate inhibits macrophage migratory and phagocytotic activities and blunts the inflammatory response of alveolar macrophages by inhibiting nuclear factor-κB signalling. Given that the alendronate inhalation effectively induces apoptosis in both recruited and resident alveolar macrophages, we suggest this strategy may have therapeutic potential for the treatment of emphysema.

An increased ratio of serum miR-21 to miR-181a levels is associated with the early pathogenic process of chronic obstructive pulmonary disease in asymptomatic heavy smokers

Heavy smoking is associated with the development of chronic obstructive pulmonary disease (COPD). However, there is no valuable biomarker for evaluating COPD development in heavy smokers because they are usually asymptomatic. This study is aimed at evaluating whether the levels of serum miRNAs can serve as biomarkers for predicting the occurrence of COPD. A rat model of emphysema was induced by enforced smoking, and the dynamic miRNAs expression profile at different stages of emphysema with varying periods of smoking were analyzed by microarray and quantitative real-time polymerase chain reaction (qRT-PCR). The differentially expressing miRNAs were analyzed using Gene Ontology and the KEGG PATHWAY database. The levels of three serum candidate miRNAs were measured by qRT-PCR in 41 healthy controls (HC), 40 asymptomatic heavy smokers, and 49 COPD patients. Following smoking for varying periods, different severities of lung emphysema were observed in different groups of rats, accompanied by altered levels of some serum miRNAs associated with regulating some pathways. Furthermore, the levels of miR-21 were significantly higher in the COPD patients and asymptomatic heavy smokers than in the HC (P < 0.001), while the levels of miR-181a were significantly lower in the COPD patients and asymptomatic heavy smokers than in the HC (P < 0.001). Accordingly, the levels of serum miR-21 and miR-181a as well as their ratios had a high sensitivity (0.854) and specificity (0.850) for evaluating the development of COPD. Our data suggest that the levels of serum miR-21 and miR-181a may be valuable for evaluating the development of COPD in heavy smokers.

Lack of neutrophil elastase reduces inflammation, mucus hypersecretion, and emphysema, but not mucus obstruction, in mice with cystic fibrosis-like lung disease

RATIONALE

Recent evidence from clinical studies suggests that neutrophil elastase (NE) released in neutrophilic airway inflammation is a key risk factor for the onset and progression of lung disease in young children with cystic fibrosis (CF). However, the role of NE in the complex in vivo pathogenesis of CF lung disease remains poorly understood.

OBJECTIVES

To elucidate the role of NE in the development of key features of CF lung disease including airway inflammation, mucus hypersecretion, goblet cell metaplasia, bacterial infection, and structural lung damage in vivo.

METHODS

We used the Scnn1b-Tg mouse as a model of CF lung disease and determined effects of genetic deletion of NE (NE(-/-)) on the pulmonary phenotype. Furthermore, we used novel Foerster resonance energy transfer (FRET)-based NE reporter assays to assess NE activity in bronchoalveolar lavage from Scnn1b-Tg mice and sputum from patients with CF.

MEASUREMENTS AND MAIN RESULTS

Lack of NE significantly reduced airway neutrophilia, elevated mucin expression, goblet cell metaplasia, and distal airspace enlargement, but had no effect on airway mucus plugging, bacterial infection, or pulmonary mortality in Scnn1b-Tg mice. By using FRET reporters, we show that NE activity was elevated on the surface of airway neutrophils from Scnn1b-Tg mice and patients with CF.

CONCLUSIONS

Our results suggest that NE plays an important role in the in vivo pathogenesis and may serve as a therapeutic target for inflammation, mucus hypersecretion, and structural lung damage and indicate that additional rehydration strategies may be required for effective treatment of airway mucus obstruction in CF.

Elastase induces lung epithelial cell autophagy through placental growth factor: a new insight of emphysema pathogenesis

Chronic obstructive pulmonary disease (COPD) is a devastating disease, which is associated with increasing mortality and morbidity. Therefore, there is a need to clearly define the COPD pathogenic mechanism and to explore effective therapies. Previous studies indicated that cigarette smoke (CS) induces autophagy and apoptosis in lung epithelial (LE) cells. Excessive ELANE/HNE (elastase, neutrophil elastase), a factor involved in protease-antiprotease imbalance and the pathogenesis of COPD, causes LE cell apoptosis and upregulates the expression of several stimulus-responsive genes. However, whether or not elastase induces autophagy in LE cell remains unknown. The level of PGF (placental growth factor) is higher in COPD patients than non-COPD controls. We hypothesize that elastase induces PGF expression and causes autophagy in LE cells. In this study, we demonstrated that porcine pancreatic elastase (PPE) induced PGF expression and secretion in LE cells in vitro and in vivo. The activation of MAPK8/JNK1 (mitogen-activated protein kinase 8) and MAPK14/p38alpha MAPK signaling pathways was involved in the PGF mediated regulation of the TSC (tuberous sclerosis complex) pathway and autophagy in LE cells. Notably, PGF-induced MAPK8 and MAPK14 signaling pathways mediated the inactivation of MTOR (mechanistic target of rapamycin), the upregulation of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 β) and the increase of autophagosome formation in mice. Furthermore, the PPE-induced autophagy promotes further apoptosis in vitro and in vivo. In summary, elastase-induced autophagy promotes LE cell apoptosis and pulmonary emphysema through the upregulation of PGF. PGF and its downstream MAPK8 and MAPK14 signaling pathways are potential therapeutic targets for the treatment of emphysema and COPD.

Animal models in chronic obstructive pulmonary disease-an overview

ABSTRACT Chronic obstructive pulmonary disease (COPD) is characterized by progressive airway obstruction resultant from an augmented inflammatory response of the respiratory tract to noxious particles and gases. Previous reports present a number of different hypotheses about the etiology and pathophysiology of COPD. The generating mechanisms of the disease are subject of much speculation, and a series of questions and controversies among experts still remain. In this context, several experimental models have been proposed in order to broaden the knowledge on the pathophysiological characteristics of the disease, as well as the search for new therapeutic approaches for acute or chronically injured lung tissue. This review aims to present the main experimental models of COPD, more specifically emphysema, as well as to describe the main characteristics, advantages, disadvantages, possibilities of application, and potential contribution of each of these models for the knowledge on the pathophysiological aspects and to test new treatment options for obstructive lung diseases.

MR imaging and targeting of a specific alveolar macrophage subpopulation in LPS-induced COPD animal model using antibody-conjugated magnetic nanoparticles

Purpose

Targeting and noninvasive imaging of a specific alveolar macrophage subpopulation in the lung has revealed the importance for early and better diagnosis and therapy of chronic obstructive pulmonary disease (COPD). In this study, the in vivo effect of pulmonary administration of iron oxide nanoparticles on the polarization profile of macrophages was assessed, and a noninvasive free-breathing magnetic resonance imaging (MRI) protocol coupled with the use of biocompatible antibody-conjugated superparamagnetic iron oxide (SPIO) nanoparticles was developed to enable specific targeting and imaging of a particular macrophage subpopulation in lipopolysaccharide-induced COPD mice model.

Materials and methods

Enzyme-linked immunosorbent assay, Real-time polymerase chain reaction, and flow cytometry analysis were performed to assess the biocompatibility of PEGylated dextran-coated SPIO nanoparticles. Specific biomarkers for M1 and M2 macrophages subsets were selected for conjugation with magnetic nanoparticles. MRI protocol using ultra-short echo time sequence was optimized to enable simultaneous detection of inflammation progress in the lung and detection of macrophages subsets. Flow cytometry and immunohistochemistry analysis were finally performed to confirm MRI readouts and to characterize the polarization profile of targeted macrophages.

Results

The tested SPIO nanoparticles, under the current experimental conditions, were found to be biocompatible for lung administration in preclinical settings. Cluster of differentiation (CD)86- and CD206-conjugated magnetic nanoparticles enabled successful noninvasive detection of M1 and M2 macrophage subpopulations, respectively, and were found to co-localize with inflammatory regions induced by lipopolysaccharide challenge. No variation in the polarization profile of targeted macrophages was observed, even though a continuum switch in their polarization might occur. However, further confirmatory studies are required to conclusively establish this observation.

Conclusion

Coupling of magnetic iron oxide nanoparticles with a specific antibody targeted to a particular macrophage subpopulation could offer a promising strategy for an early and better diagnosis of pulmonary inflammatory diseases using noninvasive MRI.

p38 Mitogen-activated protein kinase accelerates emphysema in mouse model of chronic obstructive pulmonary disease

CONTEXT

There are few short-term mouse models of chronic obstructive pulmonary disease (COPD) mimicking the human disease. In addition, p38 is recently recognized as a target for the treatment of COPD. However, the precise mechanism how p38 contributes to the pathogenesis of COPD is still unknown.

OBJECTIVE

We attempted to create a new mouse model for COPD by intra-tracheal administration of a mixture of lipopolysaccharide (LPS) and cigarette smoke solution (CSS), and investigated the importance of the p38 mitogen-activated protein kinase (p38) pathway in the pathogenesis of COPD.

METHODS

Mice were administered LPS + CSS once a day on days 0-4 and 7-11. Thereafter, CSS alone was administered to mice once a day on days 14-18. On day 28, histopathological changes of the lung were evaluated, and bronchoalveolar lavage fluid (BALF) was subjected to western blot array for cytokines. Transgenic (TG) mice expressing a constitutive-active form of MKK6, a p38-specific activator in the lung, were subjected to our experimental protocol of COPD model.

RESULTS

LPS + CSS administration induced enlargement of alveolar air spaces and destruction of lung parenchyma. BALF analyses of the LPS + CSS group revealed an increase in expression levels of several cytokines involved in the pathogenesis of human COPD. These results suggest that our experimental protocol can induce COPD in mice. Likewise, histopathological findings of the lung and induction of cytokines in BALF from MKK6 c.a.-TG mice were more marked than those in WT mice.

CONCLUSION

In a new experimental COPD mouse model, p38 accelerates the development of emphysema.

Recent advances in pre-clinical mouse models of COPD

COPD (chronic obstructive pulmonary disease) is a major incurable global health burden and will become the third largest cause of death in the world by 2020. It is currently believed that an exaggerated inflammatory response to inhaled irritants, in particular cigarette smoke, causes progressive airflow limitation. This inflammation, where macrophages, neutrophils and T-cells are prominent, leads to oxidative stress, emphysema, small airways fibrosis and mucus hypersecretion. The mechanisms and mediators that drive the induction and progression of chronic inflammation, emphysema and altered lung function are poorly understood. Current treatments have limited efficacy in inhibiting chronic inflammation, do not reverse the pathology of disease and fail to modify the factors that initiate and drive the long-term progression of disease. Therefore there is a clear need for new therapies that can prevent the induction and progression of COPD. Animal modelling systems that accurately reflect disease pathophysiology continue to be essential to the development of new therapies. The present review highlights some of the mouse models used to define the cellular, molecular and pathological consequences of cigarette smoke exposure and whether they can be used to predict the efficacy of new therapeutics for COPD.

Hip fracture aggravates systemic inflammation and lung injury in aged chronic cigarette smoke exposed rats

The aim of this investigation was to examine the influence of hip fracture on systemic inflammation and lung injury in aged chronic cigarette smoke exposed rats. Male Sprague Dawley (SD) aged rats (22-25 months old, 460-570 g) were used. Animals were subjected to either chronic cigarette smoke (CS) or air exposure for 12 weeks. These animals then underwent a sham procedure or hip fracture. Endpoint was 24 h. Systemic inflammation was assessed by TNF-α, IL-6, and IL-10 levels. Pulmonary function, inflammatory cell counts and protein concentrations in BAL, pulmonary pathological changes and scores were obtained to assess lung injury. And TLR4 mRNA expression in lung tissue was determined. The indices mentioned above were unchanged in air-exposed rats after hip fracture. However, CS-exposed animals were found to have increased serum levels of TNF-α, IL-6, and IL-10, impaired pulmonary function, increased inflammatory cell counts and protein concentrations in BAL, and intensified pathologic changes and scores. In addition, lung tissue harvested following CS-exposure demonstrated increased TLR4 mRNA expression. Our results indicate that systemic inflammation and lung injury in aged CS-exposed animals were further aggravated by hip fracture. The overexpression of TLR4 mRNA induced by CS exposure may, at least in part, involve in this process.

Chronic Obstructive Pulmonary Disease in Never-Smoking Bricklayers

Background: Chronic obstructive pulmonary disease (COPD) due to occupational exposures remains an important public health problem taking significant toll on the global burden of the disease.Aim: In order to assess chronic prevalence and characteristics of COPD in bricklaying we performed a cross-sectional study including 47 never-smoking male bricklayers (aged 34 to 57 years) and an equal number of never-smoking male office workers studied as a control.Methods: Evaluation of examined subjects consisted of completion of a questionnaire, baseline spirometry, and bronchodilator reversibility testing.Results: We found higher prevalence of respiratory symptoms in bricklayers with significant difference for cough and phlegm. Majority of the chronic respiratory symptoms in bricklayers were work-related. The mean values of all measured spirometric parameters in bricklayers were significantly lower than in office workers. The prevalence of COPD was significantly higher in bricklayers than in office workers (14.9% vs. 4.3%, P = 0.034). COPD in both examined groups was close related to age over 45 years, while in bricklayers significant association was registered for duration of occupational exposure longer than 20 years and work-related respiratory symptoms.Conclusion: Our findings support data about relationship between occupational exposure to inorganic dust and fumes in construction workers and persistent airflow limitation.

Cell therapy with bone marrow mononuclear cells in elastase-induced pulmonary emphysema

Emphysema is characterized by destruction of alveolar walls with loss of gas exchange surface and consequent progressive dyspnea. This study aimed to evaluate the efficiency of cell therapy with bone marrow mononuclear cells (BMMC) in an animal model of elastase-induced pulmonary emphysema. Emphysema was induced in C57Bl/J6 female mice by intranasal instillation of elastase. After 21 days, the mice received bone marrow mononuclear cells from EGFP male mice with C57Bl/J6 background. The groups were assessed by comparison and statistically significant differences (p < 0.05) were observed among the groups treated with BMMC and evaluated after 7, 14 and 21 days. Analysis of the mean linear intercept (Lm) values for the different groups allowed to observe that the group treated with BMMC and evaluated after 21 days showed the most significant result. The group that received no treatment showed a statistically significant difference when compared to other groups, except the group treated and evaluated after 21 days, evidencing the efficacy of cell therapy with BMMC in pulmonary emphysema.

Elastase induced lung epithelial cell apoptosis and emphysema through placenta growth factor

Chronic pulmonary obstructive disease (COPD) is the fourth leading cause of death worldwide, however, the pathogenic factors and mechanisms are not fully understood. Pulmonary emphysema is one of the major components of COPD and is thought to result from oxidative stress, chronic inflammation, protease–antiprotease imbalance and lung epithelial (LE) cell apoptosis. In our previous studies, COPD patients were noted to have higher levels of placenta growth factor (PlGF) in serum and bronchoalveolar lavage fluid than controls. In addition, transgenic mice overexpressing PlGF developed pulmonary emphysema and exposure to PlGF in LE cells induced apoptosis. Furthermore, intratracheal instillation of porcine pancreatic elastase (PPE) on to PlGF wild type mice induced emphysema, but not in PlGF knockout mice. Therefore, we hypothesized that PPE generates pulmonary emphysema through the upregulation of PlGF expression in LE cells. The elevation of PlGF then leads to LE cell apoptosis. In the present study, we investigated whether PPE induces PlGF expression, whether PlGF induces apoptosis and whether the downstream mechanisms of PlGF are related to LE cell apoptosis. We found that PPE increased PlGF secretion and expression both in vivo and in vitro. Moreover, PlGF-induced LE cell apoptosis and PPE-induced emphysema in the mice were mediated by c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38 MAPK) pathways. Given these findings, we suggest that the increase in PlGF and PlGF-induced JNK and p38 MAPK pathways contribute to PPE-induced LE cell apoptosis and emphysema. Regulatory control of PlGF and agents against its downstream signals may be potential therapeutic targets for COPD.

Systems approaches and polypharmacology for drug discovery from herbal medicines: an example using licorice

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice, one of the oldest and most popular herbal medicines in the world, has been widely used in traditional Chinese medicine as a cough reliever, anti-inflammatory, anti-anabrosis, immunomodulatory, anti-platelet, antiviral (hepatitis) and detoxifying agent. Licorice was used as an example to show drug discovery from herbal drugs using systems approaches and polypharmacology.

AIM OF THE STUDY

Herbal medicines are becoming more mainstream in clinical practice and show value in treating and preventing diseases. However, due to its extreme complexity both in chemical components and mechanisms of action, deep understanding of botanical drugs is still difficult. Thus, a comprehensive systems approach which could identify active ingredients and their targets in the crude drugs and more importantly, understand the biological basis for the pharmacological properties of herbal medicines is necessary.

MATERIALS AND METHODS

In this study, a novel systems pharmacology model that integrates oral bioavailability screening, drug-likeness evaluation, blood-brain barrier permeation, target identification and network analysis has been established to investigate the herbal medicines.

RESULTS

The comprehensive systems approach effectively identified 73 bioactive components from licorice and 91 potential targets for this medicinal herb. These 91 targets are closely associated with a series of diseases of respiratory system, cardiovascular system, and gastrointestinal system, etc. These targets are further mapped to drug-target and drug-target-disease networks to elucidate the mechanism of this herbal medicine.

CONCLUSION

This work provides a novel in silico strategy for investigation of the botanical drugs containing a huge number of components, which has been demonstrated by the well-studied licorice case. This attempt should be helpful for understanding definite mechanisms of action for herbal medicines and discovery of new drugs from plants.

Quantification of lung damage in an elastase-induced mouse model of emphysema

Objective. To define the sensitivity of microcomputed tomography- (micro-CT-) derived descriptors for the quantification of lung damage caused by elastase instillation. Materials and Methods. The lungs of 30 elastase treated and 30 control A/J mice were analyzed 1, 6, 12, and 24 hours and 7 and 17 days after elastase instillation using (i) breath-hold-gated micro-CT, (ii) pulmonary function tests (PFTs), (iii) RT-PCR for RNA cytokine expression, and (iv) histomorphometry. For the latter, an automatic, parallel software toolset was implemented that computes the airspace enlargement descriptors: mean linear intercept (L(m)) and weighted means of airspace diameters (D(0), D(1), and D(2)). A Support Vector Classifier was trained and tested based on three nonhistological descriptors using D(2) as ground truth. Results. D(2) detected statistically significant differences (P < 0.01) between the groups at all time points. Furthermore, D(2) at 1 hour (24 hours) was significantly lower (P < 0.01) than D(2) at 24 hours (7 days). The classifier trained on the micro-CT-derived descriptors achieves an area under the curve (AUC) of 0.95 well above the others (PFTS AUC = 0.71; cytokine AUC = 0.88). Conclusion. Micro-CT-derived descriptors are more sensitive than the other methods compared, to detect in vivo early signs of the disease.

Emerging genetics of COPD

Since the discovery of alpha-1 antitrypsin in the early 1960s, several new genes have been suggested to play a role in chronic obstructive pulmonary disease (COPD) pathogenesis. Yet, in spite of those advances, much about the genetic basis of COPD still remains to be discovered. Unbiased approaches, such as genome-wide association (GWA) studies, are critical to identify genes and pathways and to verify suggested genetic variants. Indeed, most of our current understanding about COPD candidate genes originates from GWA studies. Experiments in form of cross-study replications and advanced meta-analyses have propelled the field towards unravelling details about COPD's pathogenesis. Here, we review the discovery of genetic variants in association with COPD phenotypes by discussing the available approaches and current findings. Limitations of current studies are considered and future directions provided.

Annexin V decreases PS-mediated macrophage efferocytosis and deteriorates elastase-induced pulmonary emphysema in mice

Efferocytosis is believed to be a key regulator for lung inflammation in chronic obstructive pulmonary disease. In this study we pharmacologically inhibited efferocytosis with annexin V and attempted to determine its impact on the progression of pulmonary emphysema in mouse. We first demonstrated in vitro and in vivo efferocytosis experiments using annexin V, an inhibitor for phosphatidylserine-mediated efferocytosis. We then inhibited efferocytosis in porcine pancreatic elastase (PPE)-treated mice. PPE-treated mice were instilled annexin V intranasally starting from day 8 until day 20. Mean linear intercept (Lm) was measured, and cell apoptosis was assessed in lung specimen obtained on day 21. Cell profile, apoptosis, and mRNA expression of matrix metalloproteinases (MMPs) and growth factors were evaluated in bronchoalveolar lavage (BAL) cells on day 15. Annexin V attenuated macrophage efferocytosis both in vitro and in vivo. PPE-treated mice had a significant higher Lm, and annexin V further increased that by 32%. More number of macrophages was found in BAL fluid in this group. Interestingly, cell apoptosis was not increased by annexin V treatment both in lung specimens and BAL fluid, but macrophages from mice treated with both PPE and annexin V expressed higher MMP-2 mRNA levels and had a trend for higher MMP-12 mRNA expression. mRNA expression of keratinocyte growth factor tended to be downregulated. We showed that inhibited efferocytosis with annexin V worsened elastase-induced pulmonary emphysema in mice, which was, at least partly, attributed to a lack of phenotypic change in macrophages toward anti-inflammatory one.

A rat model for stable chronic obstructive pulmonary disease induced by cigarette smoke inhalation and repetitive bacterial infection

To develop a stable chronic obstructive pulmonary disease (COPD) model in rats. Sprague-Dawley rats were treated with cigarette-smoke inhalation (CSI) for 12 weeks, repetitive bacterial infection (RBI) for 8 weeks, or the combination of the two (CCR) for 12 weeks and followed up for the additional 20 weeks. Tidal volume (V(T)), peak expiratory flow (PEF) and 50% V(T) expiratory flow (EF(50)), histological changes in the lungs, and levels of the cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-8, and IL-10 in serum and bronchial alveolar lavage fluid (BALF) were examined at intervals during the 32 week study period. The right ventricular hypertrophy index (RVHI) was also determined at the same times. V(T), PEF, and EF(50) were decreased in rats with COPD compared to the control. The expression of TNF-α, IL-8 and IL-10 increased in both serum and BALF with a similar trend. Bronchiole and arteriole wall thickness and the degree of bronchiole stenosis and alveolar size increased in COPD rats. RVHI was reduced gradually following the treatment. All of these changes were more pronounced in the CCR-treatment group than in the other groups. Our results have shown that CSI or RBI alone can induce COPD in rats, but that the combination of CSI with RBI induces a stable COPD that has more similarity to complications seen in patients with COPD. This combination may therefore provide a more appropriate model for study of human COPD.

[Chronic obstructive pulmonary disease: an autoimmune disease?]

Chronic obstructive pulmonary disease (COPD) is an important cause of morbidity and mortality characterized by irreversible airflow limitation involving a reduced caliber of distal airways (less than 2mm) and alveolar destruction. Exposure to tobacco is a major risk factor for COPD, but all smokers do not develop the disease. In addition, there is continued progression of the disease several years after cessation of the exposure. To explain these phenomena, factors involving innate immunity including the release of neutrophil elastase, macrophage metalloproteases, in combination with pro-apoptotic factors, involved in the worsening of the lesions of emphysema and fibrosis of small airways have been described for many years. More recently, it has been proposed at an advanced stage of the disease that an autoimmune reaction directed mainly at elastin could participate to the pathogenesis of the disease. We here review the immunological processes and currently available data on autoimmunity in COPD.

Monitoring in vivo changes in lung microstructure with ³He MRI in Sendai virus-infected mice

Recently, a Sendai virus (SeV) model of chronic obstructive lung disease has demonstrated an innate immune response in mouse airways that exhibits similarities to the chronic airway inflammation in human chronic obstructive pulmonary disease (COPD) and asthma, but the effect on distal lung parenchyma has not been investigated. The aim of our study is to image the time course and regional distribution of mouse lung microstructural changes in vivo after SeV infection. (1)H and (3)He diffusion magnetic resonance imaging (MRI) were successfully performed on five groups of C57BL/6J mice. (1)H MR images provided precise anatomical localization and lung volume measurements. (3)He lung morphometry was implemented to image and quantify mouse lung geometric microstructural parameters at different time points after SeV infection. (1)H MR images detected the SeV-induced pulmonary inflammation in vivo; spatially resolved maps of acinar airway radius R, alveolar depth h, and mean linear intercept Lm were generated from (3)He diffusion images. The morphometric parameters R and Lm in the infected group were indistinguishable from PBS-treated mice at day 21, increased slightly at day 49, and were increased with statistical significance at day 77 (p = 0.02). Increases in R and Lm of infected mice imply that there is a modest increase in alveolar duct radius distal to airway inflammation, particularly in the lung periphery, indicating airspace enlargement after virus infection. Our results indicate that (3)He lung morphometry has good sensitivity in quantifying small microstructural changes in the mouse lung and that the Sendai mouse model has the potential to be a valid murine model of COPD.

Experimental model of smoking and simulation of reflux with acid and pepsin in rats

PURPOSE: To develop experimental models to evaluate the effects of hydrochloric acid associated with the pepsin instilled in the mucosa of the upper esophagus and the esophagogastric junction of young male rats Wistar, simulating injury caused by gastroesophageal reflux on the mucosa of aero-digestive tract in humans as well as the action of the risk exposure of mucosa to cigarette smoke. METHODS: Fifty young male Wistar rats divided in 5 groups with 10 animals each one, respectively simulating pharyngo-laryngeal reflux and gastroesophageal reflux, pharyngo-laryngeal reflux and smoking, smoking only, gastroesophageal reflux and control group. RESULTS: The histopathologic studies no recorded neoplasias, only mild changes and no significant alterations. The hemo-oximetry (carboxyhemoglobin and methemoglobim) and CO2 concentration confirm that the animals were submitted to high intensity of exposure to carcinogens in tobacco and its derivatives. CONCLUSION: The experimental models were highly efficient, practical, easy to use and economical and can be employed in other similar studies to determine the harmful effects by smoking and reflux.

Dynamic ventilation 3He MRI for the quantification of disease in the rat lung

Pulmonary diseases are known to be largely inhomogeneous. To evaluate such inhomogeneities, we are testing an image-based method to measure gas flow in the lung regionally. Dynamic, spin-density-weighted hyperpolarized (3)He MR images performed during slow inhalation of this gas were analyzed to quantify regional inflation rate. This parameter was measured in regions of interest (ROIs) that were defined by a rectangular grid that covered the entire rat lung and grew dynamically with it during its inflation. We used regional inflation rate to quantify elastase-induced emphysema and to differentiate healthy (n = 8) from elastase-treated (n = 9) rat lungs as well as healthy from elastase-treated areas of one rat unilaterally treated with elastase in the left lung. Emphysema was also assessed by gold standard morphological and well-established hyperpolarized (3)He MRI diffusion measurements. Mean values of regional inflation rates were significantly different for healthy and elastase-treated animals and correlated well with the apparent diffusion coefficient of (3)He and morphological measurements. The image-based biomarker inflation rate may be useful for the assessment of regional lung ventilation.

Orexin-A and respiration in a rat model of smoke-induced chronic obstructive pulmonary disease

1. Orexins are neuropeptides synthesized in the hypothalamus that regulate many physiological functions, including energy homeostasis, stress responses, sleep/wake states etc. It is now emerging that orexins may also regulate breathing, but little is known as to how they do this, particularly in chronic obstructive pulmonary disease (COPD). In the present study, we used a rat model of cigarette smoke-induced COPD to investigate orexin-A expression in the hypothalamus and medulla and its effect on respiration. 2. Sprague-Dawley rats were exposed to cigarette smoke (1 h twice daily) for 12 weeks. Lung function and pathological changes associated with inflammation and emphysema were determined to confirm the validity of the COPD model. 3. Hypothalamic and medullary orexin-A levels, as determined by radioimmunoassay, were higher in smoke-exposed than control rats. Furthermore, the expression of prepro-orexin (PPO) mRNA in the hypothalamus and orexin OX(1) receptor mRNA in the medulla, as determined by real-time quantitative polymerase chain reaction, was higher in smoke-exposed than control rats. 4. The number of orexin-A-positive neurons in the hypothalamus and OX(1) and OX(2) receptor-positive neurons in the ventrolateral medulla was higher in smoke-exposed than control rats. 5. Microinjection of orexin-A (1 μmol/L, 0.1 μL) into the pre-Bötzinger complex enhanced phrenic nerve discharge to a greater extent in smoke-exposed compared with control rats (61% vs 36%, respectively). 6. The findings of the present study demonstrate that the increased respiratory activity in smoke-exposed rats is due to an increase in orexin-A as well as upregulation of orexin receptors in the ventrolateral medulla.

Mast cells and COPD

The pathogenesis of chronic obstructive pulmonary disease (COPD) is based on the innate and adaptive inflammatory immune response to the inhalation of toxic particles and gases. Although tobacco smoking is the primary cause of this inhalation injury, many other environmental and occupational exposures contribute to the pathology of COPD. The immune inflammatory changes associated with COPD are linked to a tissue-repair and -remodeling process that increases mucus production and causes emphysematous destruction of the gas-exchanging surface of the lung. The common form of emphysema observed in smokers begins in the respiratory bronchioles near the thickened and narrowed small bronchioles that become the major site of obstruction in COPD. The inflamed airways of COPD patients contain several inflammatory cells including neutrophils, macrophages, T lymphocytes, and dendritic cells. The relative contribution of mast cells to airway injury and remodeling is not well documented. In this review, an overview is given on the possible role of mast cells and their mediators in the pathogenesis of COPD. Activation of mast cells and mast cell signaling in response to exposure to cigarette smoke is further discussed.