Acute cigarette smoke-induced connective tissue breakdown requires both neutrophils and macrophage metalloelastase in mice

Cichorium intybus L. significantly alleviates cigarette smoke-induced acute lung injury by lowering NF-κB pathway activation and inflammatory mediators

Background

Cigarette smoke (CS) is one of the primary causes of acute lung injury (ALI) via provoking pulmonary inflammation and oxidative stress. Despite substantial studies, no effective treatment for ALI is presently available.

Purpose

New prospective treatment options for ALI are required. Thus, this project was designed to investigate the in vivo and in vitro protective effects of 70 % methanolic-aqueous crude extract of whole plant of Cichorium intybus (Ci.Mce) against CS-induced ALI.

Study design

/methods: Initially, male Swiss albino mice were subjected to whole-body CS exposure for 10 continuous days to prepare CS-induced ALI models. Normal saline (10 mL/kg), Ci.Mce (100, 200, 300 mg/kg), and Dexamethasone (1 mg/kg) were orally administered to respective animal groups 1 h prior to CS-exposure. 24 hrs after the last CS-exposure, BALF and lungs were harvested to study the key characteristics of ALI. Next, HPLC analysis was done to explore the phytoconstituents.

Results

Ci.Mce exhibited significant reductions in lung macrophage and neutrophil infiltration, lung weight coefficient, and albumin exudation. Additionally, it effectively ameliorated lung histopathological alterations and hypoxemia. Notably, Ci.Mce exerted inhibitory effects on the excessive generation of IL-6, IL-1β, and KC in both CS-induced ALI murine models and CSE-stimulated RAW 264.7 macrophages. Noteworthy benefits included the attenuation of oxidative stress induced by CS, evidenced by decreased levels of MDA, TOS, and MPO, alongside enhanced TAC production. Furthermore, Ci.Mce demonstrated a marked reduction in CS-induced NF-κB expression, both in vivo and in vitro.

Conclusion

Consequently, Cichorium intybus could be a therapeutic option for CS-induced ALI due to its ability to suppress inflammatory reactions, mitigate oxidative stress, and quell NF-κB p65 activation.

Verapamil attenuates oxidative stress and inflammatory responses in cigarette smoke (CS)-induced murine models of acute lung injury and CSE-stimulated RAW 264.7 macrophages via inhibiting the NF-κB pathway

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), severe form of ALI, are characterized by overwhelming of lung inflammation, and no treatment is currently available to treat ALI/ARDS. Cigarette smoke (CS) is one of the prime causes to induce ALI/ARDS via oxidative stress. Despite extensive research, no appropriate therapy is currently available to treat ALI/ARDS. Hence, new potential approaches are needed to treat ALI/ARDS. Consequently, this project was designed to explore the protective effects of verapamil against CS-induced ALI by in vivo and in vitro method. In vivo data obtained from respiratory mechanics, pulmonary morphometric analyses and lung histopathology revealed that verapamil dose-dependently and strikingly decreased the lung weight coefficient, attenuated the albumin exudation into lungs, minimized the infiltration of macrophages and neutrophils into lungs, reduced the pro-inflammatory cytokines (tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and keratinocyte chemoattractant (KC)) production, and improved the hypoxemia and lung histopathological changes. Similarly, verapamil also reduced the production of TNF-α, IL-6 and KC from cigarette smoke extract (CSE)-stimulated RAW 264.7 macrophage. Importantly, verapamil dose-dependently and remarkably suppressed the CS-induced oxidative stress via not only reducing the myeloperoxidase (MPO) activity of lungs, total oxidative stress (TOS) and malondialdehyde (MDA) content in the lungs and supernatant of RAW 264.7 macrophage but also improving total antioxidant capacity (TAC) and superoxide dismutase (SOD) production. Finally, verapamil strikingly decreased the NF-κB expression both in in vivo and in vitro models. Hence, verapamil has positive therapeutic effects against CS-induced ALI via suppressing uncontrolled inflammatory response, oxidative stress and NF-κB p65 signaling.

LSD1-S112A exacerbates the pathogenesis of CSE/LPS-induced chronic obstructive pulmonary disease in mice

Lysine-specific demethylase 1 (LSD1) is an epigenetic regulator that modulates the chromatin status, contributing to gene activation or repression. The post-translational modification of LSD1 is critical for the regulation of many of its biological processes. Phosphorylation of serine 112 of LSD1 by protein kinase C alpha (PKCα) is crucial for regulating inflammation, but its physiological significance is not fully understood. This study aimed to investigate the role of Lsd1-S112A, a phosphorylation defective mutant, in the cigarette smoke extract/LPS-induced chronic obstructive pulmonary disease (COPD) model using Lsd1^SA/SA mice and to explore the potential mechanism underpinning the development of COPD. We found that Lsd1^SA/SA mice exhibited increased susceptibility to CSE/LPS-induced COPD, including high inflammatory cell influx into the bronchoalveolar lavage fluid and airspace enlargement. Additionally, the high gene expression associated with the inflammatory response and oxidative stress was observed in cells and mice containing Lsd1-S112A. Similar results were obtained from the mouse embryonic fibroblasts exposed to a PKCα inhibitor, Go6976. Thus, the lack of LSD1 phosphorylation exacerbates CSE/LPS-induced COPD by elevating inflammation and oxidative stress.

Myeloperoxidase and associated lung disease: Review of the latest developments

Myeloperoxidase (MPO) anti-neutrophil cytoplasmic antibodies (ANCA) are often detected in association with a variety of lung pathologies, the most common being interstitial lung disease (ILD). A growing cohort of patients are being diagnosed with MPO-ANCA in the context of ILD without ANCA-associated vasculitis. Clinically and radiologically, there is little to differentiate this cohort from MPO-ANCA-negative ILD patients; however, the pathophysiology is likely different and different treatments are likely required. We present here a brief summary of the proposed pathophysiology of MPO-ANCA-positive ILD, and a more detailed review of the latest evidence on management, including monitoring for development of ANCA-associated vasculitis, immunosuppression, anti-fibrotics, and novel agents that have yet to be trialled in human experiments.

Cigarette smoke extract combined with LPS down-regulates the expression of MRP2 in chronic pulmonary inflammation may be related to FXR

The transporter multidrug resistance protein 2 (MRP2) plays an important role in chronic pulmonary inflammation by transporting cigarette smoke and other related inflammatory mediators. However, it is not completely clear whether pulmonary inflammation caused by cigarette smoke extract (CSE) and lipopolysaccharide (LPS) is related to MRP2 and its signal factors. In this study, CSE combined with LPS was used to establish an inflammation model in vivo and in vitro. We found that compared with the control group, after CSE combined with LPS treatment, the expression of MRP2 in rat lung tissue in vivo and human alveolar cell line in vitro was down-regulated, while the expression of inflammatory factors was up-regulated. Through silencing and overexpression of FXR, it was found that silent FXR could down-regulate MRP2 and up-regulate the expression of inflammatory factors. On the contrary, overexpression of FXR could up-regulate MRP2 and down-regulate the expression of inflammatory factors. Our results show that CSE combined with LPS can down-regulate the expression of MRP2 under inflammatory conditions, and the down-regulation of MRP2 expression may be achieved partly through the FXR signal pathway.

Neutrophils and IL-1α Regulate Surfactant Homeostasis during Cigarette Smoking

Cigarette smoke exposure induces inflammation marked by rapid and sustained neutrophil infiltration, IL-1α, release and altered surfactant homeostasis. However, the extent to which neutrophils and IL-1α contribute to the maintenance of pulmonary surfactant homeostasis is not well understood. We sought to investigate whether neutrophils play a role in surfactant clearance as well as the effect of neutrophil depletion and IL-1α blockade on the response to cigarette smoke exposure. In vitro and in vivo administration of fluorescently labeled surfactant phosphatidylcholine was used to assess internalization of surfactant by lung neutrophils and macrophages during or following cigarette smoke exposure in mice. We also depleted neutrophils using anti-Ly-6G or anti-Gr-1 Abs, or we neutralized IL-1α using a blocking Ab to determine their respective roles in regulating surfactant homeostasis during cigarette smoke exposure. We observed that neutrophils actively internalize labeled surfactant both in vitro and in vivo and that IL-1α is required for smoke-induced elevation of surfactant protein (SP)-A and SP-D levels. Neutrophil depletion during cigarette smoke exposure led to a further increase in SP-A levels in the bronchoalveolar lavage and increased IL-1α, CCL2, GM-CSF, and G-CSF release. Finally, macrophage expression of Mmp12, a protease linked to emphysema, was increased in neutrophil-depleted groups and decreased following IL-1α blockade. Taken together, our results indicate that neutrophils and IL-1α signaling are actively involved in surfactant homeostasis and that the absence of neutrophils in the lungs during cigarette smoke exposure leads to an IL-1α-dependent exacerbation of the inflammatory response.

Surface-bound matrix metalloproteinase-8 on macrophages: Contributions to macrophage pericellular proteolysis and migration through tissue barriers

Objective

MMP‐8 binds to surface‐bound tissue inhibitor of metalloproteinase‐1 (TIMP‐1) on PMNs to promote pericellular proteolysis during the development of inflammatory diseases associated with tissue destruction. Little is known about the biology of MMP‐8 in macrophages. We tested the hypotheses that: (1) MMP‐8 and TIMP‐1 are also expressed on the surface of activated macrophages, (2) surface‐bound MMP‐8 on macrophages promotes TIMP‐resistant pericellular proteolysis and macrophage migration through tissue barriers, and (3) MMP‐8 binds to surface‐bound TIMP‐1 on macrophages.

Methods

Surface MMP‐8 and TIMP‐1 levels were measured on human monocyte‐derived macrophages (MDM) and/or murine macrophages using immunostaining, biotin‐labeling, and substrate cleavage methods. The susceptibility of membrane‐bound Mmp‐8 on activated macrophages from wild‐type (WT) mice to TIMPs was measured. Migration of WT and Mmp‐8^−/− macrophages through models of tissue barriers in vitro and the accumulation of peritoneal macrophages in WT versus Mmp‐8^−/− mice with sterile peritonitis was compared. Surface levels of Mmp‐8 were compared on activated macrophages from WT and Timp‐1^−/− mice.

Results

Lipopolysaccharides and a cluster of differentiation 40 ligand increased surface MMP‐8 and/or TIMP‐1 staining and surface type I collagenase activity on MDM and/or murine macrophages. Activated Mmp‐8^−/− macrophages degraded less type I collagen than activated WT macrophages. The surface type‐I collagenase activity on WT macrophages was resistant to inhibition by Timp‐1. Peritoneal macrophage accumulation was similar in WT and Mmp‐8^−/− mice with sterile acute peritonitis. However, Mmp‐8^−/− macrophages migrated less efficiently through models of tissue barriers (especially those containing type I collagen) than WT cells. Activated WT and Timp‐1^−/− macrophages had similar surface‐bound Mmp‐8 levels.

Conclusions

MMP‐8 and TIMP‐1 are expressed on the surface of activated human MDM and murine macrophages, but Mmp‐8 is unlikely to bind to surface‐bound Timp‐1 on these cells. Surface‐bound MMP‐8 contributes to TIMP‐resistant monocyte/macrophage pericellular proteolysis and macrophage migration through collagen‐containing tissue barriers.

First-in-Man Safety, Tolerability, and Pharmacokinetics of a Novel and Highly Selective Inhibitor of Matrix Metalloproteinase-12, FP-025: Results from Two Randomized Studies in Healthy Subjects

BACKGROUND AND OBJECTIVES

Matrix metalloproteinases (MMPs) are proteases with different biological and pathological activities, and many have been linked to several diseases. Targeting individual MMPs may offer a safer therapeutic potential for several diseases. We assessed the safety, tolerability, and pharmacokinetics of FP-025, a novel, highly selective oral matrix metalloproteinase-12 inhibitor, in healthy subjects.

METHODS

Two randomized, double-blind, placebo-controlled studies were conducted. Study I was a first-in-man study, evaluating eight single ascending doses (SADs) (50-800 mg) in two formulations: i.e., neat FP-025 in capsule (API-in-Capsule) and in an amorphous solid dispersion (ASD-in-Capsule) formulation. In Study II, three multiple ascending doses (MADs) (100, 200, and 400 mg, twice daily) of FP-025 (ASD-in-Capsule) were administered for 8 days, including a food-effect evaluation.

RESULTS

Ninety-six subjects were dosed. Both formulations were well tolerated with one adverse event (AE) reported in the 800 mg API-in-Capsule SAD group and seven AEs throughout the MAD groups. The exposure to FP-025 was low with the API-in-Capsule formulation; it increased dose-dependently with the ASD-in-Capsule formulation, with which exposure to FP-025 increased in a greater-than-dose-proportional manner at lower doses (≤ 100 mg) but less proportionally at higher doses. The elimination half-life (t_1/2) was between 6 (Study I) and 8 h (Study II). Accumulation of FP-025 was approximately 1.7-fold in the MAD study. Food intake delayed the rate of absorption, but without effect in the extent of absorption or bioavailability.

CONCLUSION

FP-025 was well tolerated and showed a favorable pharmacokinetic profile following ASD-in-Capsule dosing. Efficacy studies in target patient populations, including asthma, chronic obstructive pulmonary disease (COPD), and pulmonary fibrosis, are warranted.

TRIAL REGISTRATION NUMBER

www.clinicaltrials.gov : NCT02238834 (Study I); NCT03304964 (Study II). Trial registration date: Study I was registered on 12 September 2014 while study II was registered on 9 October 2017.

Differential lung inflammation and injury with tobacco smoke exposure in Wistar Kyoto and spontaneously hypertensive rats

OBJECTIVE

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide and has been associated with periods of intense lung inflammation. The objective of this study was to characterize whether similar rat strains, possessing different genetic predispositions, might play a role in exacerbating the pathophysiology of COPD-like cellular and structural changes with progressive 12-week exposure to tobacco smoke (TS). Normotensive Wistar Kyoto (WKY) and spontaneously hypertensive (SH) rats were compared.

MATERIALS AND METHODS

WKY and SH rats were exposed to filtered air or to tobacco smoke at a particulate concentration of 80 mg/m3 for 4, 8, or 12 weeks. Necropsy was performed 24 h after the last exposure to obtain cells by bronchoalveolar lavage for total cell and differential counts. Scoring of lung tissues and immunohistochemical staining for M1 (pro-inflammatory) and M2 (anti-inflammatory) macrophages were performed on paraffin-embedded lung sections.

RESULTS AND DISCUSSION

With progressive exposure, TS-exposed SH rats demonstrated significant airspace enlargement, mucin production, and lung inflammation compared to their FA control and TS-matched WKY rats. Moreover, SH rats also demonstrated increased expression of the M1 marker in alveolar macrophages compared to FA control, as well as the M2 marker compared to controls and TS-exposed WKY rats.

CONCLUSION

The progressive tobacco smoke exposure contributes to persistent lung injury and inflammation that can be significantly enhanced by rat strain susceptibility in the genesis of COPD.

Lung epithelium damage in COPD - An unstoppable pathological event?

Chronic obstructive pulmonary disease (COPD) is a common term for alveolar septal wall destruction resulting in emphysema, and chronic bronchitis accompanied by conductive airway remodelling. In general, this disease is characterized by a disbalance of proteolytic/anti-proteolytic activity, augmented inflammatory response, increased oxidative/nitrosative stress, rise in number of apoptotic cells and decreased proliferation. As the first responder to the various environmental stimuli, epithelium occupies an important position in different lung pathologies, including COPD. Epithelium sequentially transitions from the upper airways in the direction of the gas exchange surface in the alveoli, and every cell type possesses a distinct role in the maintenance of the homeostasis. Basically, a thick ciliated structure of the airway epithelium has a major function in mucus secretion, whereas, alveolar epithelium which forms a thin barrier covered by surfactant has a function in gas exchange. Following this line, we will try to reveal whether or not the chronic bronchitis and emphysema, being two pathological phenotypes in COPD, could originate in two different types of epithelium. In addition, this review focuses on the role of lung epithelium in COPD pathology, and summarises underlying mechanisms and potential therapeutics.

Alpha-1 Antitrypsin Deficiency: Have We Got the Right Proteinase?

Alpha-1 antitrypsin deficiency (AATD) has traditionally been associated with the development of early onset panlobular emphysema thought to reflect the direct interstitial damage caused by neutrophil elastase. Since this enzyme is highly sensitive to irreversible inhibition by alpha-1 antitrypsin (AAT), the logic of intravenous augmentation therapy has remained unquestioned and efficacy is supported by both observational studies and formal clinical trials. However, evidence suggests that although AAT augmentation modulates the progression of emphysema, it only slows it down. This raises the issue of whether our long-held beliefs of the cause of the susceptibility to develop emphysema in deficient individuals are correct. There are several aspects of our understanding of the disease that might benefit from a radical departure from traditional thought. This review addresses these concepts and alternative pathways that may be central to progression of emphysema.

Microscopic Polyangiitis with Pulmonary Fibrosis: An Often-Recognized Manifestation of the Disease

Background

Microscopic polyangiitis (MPA) can manifest with atypical features such as pulmonary fibrosis and chronic obstructive pulmonary disease (COPD), which are atypical and unusual features of small vessel vasculitis.

Case Presentation

This paper presents two patients with microscopic polyangiitis and respiratory symptoms attributable to atypical pulmonary manifestations. Pulmonary fibrosis was present in both cases, with COPD also present in one patient. Management involved methylprednisone, prednisone, and cyclophosphamide. The second patient also received azathioprine. Both patients responded well to immunosuppressive treatment; however, pulmonary fibrosis and COPD were refractory to immunosuppression.

Conclusion

Pulmonary manifestations including pulmonary fibrosis, emphysema, and bronchiectasis are observed in MPA. Evaluation of MPA in unexplained cases should be performed to avoid delays in diagnosis and management. Patients who present with MPA with pulmonary manifestations may respond to treatment, but their pulmonary features demonstrate a refractory nature to such management.

Targeting p16-induced senescence prevents cigarette smoke-induced emphysema by promoting IGF1/Akt1 signaling in mice

Senescence is a mechanism associated with aging that alters tissue regeneration by depleting the stem cell pool. Chronic obstructive pulmonary disease (COPD) displays hallmarks of senescence, including a diminished stem cell population. DNA damage from cigarette smoke (CS) induces senescence via the p16 pathway. This study evaluated the contribution of p16 to CS-associated lung pathologies. p16 expression was prominent in human COPD lungs compared with normal subjects. CS induces impaired pulmonary function, emphysema, and increased alveolar epithelial cell (AECII) senescence in wild-type mice, whereas CS-exposed p16-/- mice exhibit normal pulmonary function, reduced emphysema, diminished AECII senescence, and increased pro-growth IGF1 signaling, suggesting that improved lung function in p16-/- mice was due to increased alveolar progenitor cell proliferation. In conclusion, our study suggests that targeting senescence may facilitate alveolar regeneration in COPD emphysema by promoting IGF1 proliferative signaling.

Impact of aging on inflammatory and immune responses during elastin peptide-induced murine emphysema

Deterioration of lung functions and degradation of elastin fibers with age are accelerated during chronic obstructive pulmonary disease (COPD). Excessive genesis of soluble elastin peptides (EP) is a key factor in the pathophysiology of COPD. We have previously demonstrated that 6-wk-old mice exhibited emphysematous structural changes associated with proinflammatory immune response after EP instillation. In this study, we investigated the consequences of aging on inflammatory, immune, and histological criteria associated with murine emphysema progression after EP exposure. Young (6 wk old) and elderly (15 mo old) C57BL/6J mice were endotracheally instilled with EP, and, at various time points after treatment, the inflammatory cell profiles from bronchoalveolar lavage fluids (BALF) and the T-lymphocyte phenotypes, at local and systemic levels, were analyzed by flow cytometry. Lungs were also prepared to allow morphological and histological analysis by confocal microscopy. Elderly mice exhibited an earlier development of pulmonary emphysema, characterized by an increase of the inflammatory and lymphocytic infiltrates, extracellular matrix breakdown, and airspace enlargement compared with young mice. This age-dependent parenchymal tissue remodeling was associated with an increase of the matrix metalloproteinase expressions and desmosine levels in BALF and/or sera of EP-treated mice. In addition, both the proportion of CD4⁺CD28^- and CD8⁺CD28^- T cells in the tissues of EP-treated mice and the interferon-γ levels in the EP-specific memory T-cell clones were significantly higher in elderly versus younger mice. This study demonstrates that aging accelerates emphysema development and that this effect is linked to increased EP production and their effects on inflammatory and immune response.

CRTH2 antagonist, CT‑133, effectively alleviates cigarette smoke-induced acute lung injury

AIMS

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), characterized by overwhelming lung inflammation, are associated with high mortality. Cigarette smoke (CS) is one of the major causes of ALI/ARDS. Since high expression of prostaglandin (PG) D2 has been observed in CS-induced lung injury. Currently, no effective pharmacological therapies are available to treat ALI, and supportive therapies remain the mainstay of treatment. Therefore, we investigated the protective effect of CT‑133, a newly discovered selective CRTH2 antagonist, on CS-induced ALI in vivo and in vitro.

MAIN METHODS

CT‑133 (10 and 30 mg/kg), dexamethasone (1 mg/kg) and normal saline were intratracheally administrated 1 hr prior to whole-body CS-exposure for seven consecutive days to study the key characteristics of ALI. Subsequently, CSE (4%)- and PGD2-stimulated RAW 264.7 macrophages were used to evaluate the protective effect of CT‑133.

KEY FINDINGS

CT‑133 remarkably attenuated infiltration of inflammatory cells, neutrophils, and macrophages in the BALF, albumin contents, expression of IL‑1β, IL‑6, TNF‑α and KC, lung myeloperoxidase (MPO) activity and lung histopathological alterations caused by CS exposure in mice. Moreover, CT‑133 not only reversed the uncontrolled secretion of IL‑1β, IL-6, TNF‑α and KC from CSE- and PGD2-stimulated RAW 264.7 macrophages but also augmented IL-10 production in both in vivo and in vitro studies. Additionally, CT‑133 alleviated in vitro neutrophil migration chemoattracted by PGD2.

SIGNIFICANCE

Our results provide the first evidence that targeting CRTH2 could be a new potential therapeutic option to treat CS-induced ALI.

Acute Moraxella catarrhalis Airway Infection of Chronically Smoke-Exposed Mice Increases Mechanisms of Emphysema Development: A Pilot Study

In chronic obstructive pulmonary disease (COPD), acute exacerbations and emphysema development are characteristics for disease pathology. COPD is complicated by infectious exacerbations with acute worsening of respiratory symptoms with Moraxella catarrhalis as one of the most frequent pathogens. Although cigarette smoke (CS) is the primary risk factor, additional molecular mechanisms for emphysema development induced by bacterial infections are incompletely understood. We investigated the impact of M. catarrhalis on emphysema development in CS exposed mice and asked whether an additional infection would induce a solubilization of pro-apoptotic and pro-inflammatory endothelial monocyte-activating-protein-2 (EMAPII) to exert its activities in the pulmonary microvas-culature and other parts of the lungs not exposed directly to CS.

Mice were exposed to smoke (6 or 9 months) and/or infected with M. catarrhalis. Lungs, bronchoalveolar lavage fluid (BALF), and plasma were analyzed.

CS exposure reduced ciliated area, caused rarefaction of the lungs, and induced apoptosis. EMAPII was increased independent of prior smoke exposure in BALF of infected mice. Importantly, acute M. catarrhalis infection increased release of matrixmetalloproteases-9 and -12, which are involved in emphysema development and comprise a mechanism of EMAPII release.

Our data suggest that acute M. catarrhalis infection represents an independent risk factor for emphysema development in smoke-exposed mice.

Tobacco Smoke Induces and Alters Immune Responses in the Lung Triggering Inflammation, Allergy, Asthma and Other Lung Diseases: A Mechanistic Review

Many studies have been undertaken to reveal how tobacco smoke skews immune responses contributing to the development of chronic obstructive pulmonary disease (COPD) and other lung diseases. Recently, environmental tobacco smoke (ETS) has been linked with asthma and allergic diseases in children. This review presents the most actual knowledge on exact molecular mechanisms responsible for the skewed inflammatory profile that aggravates inflammation, promotes infections, induces tissue damage, and may promote the development of allergy in individuals exposed to ETS. We demonstrate how the imbalance between oxidants and antioxidants resulting from exposure to tobacco smoke leads to oxidative stress, increased mucosal inflammation, and increased expression of inflammatory cytokines (such as interleukin (IL)-8, IL-6 and tumor necrosis factor α ([TNF]-α). Direct cellular effects of ETS on epithelial cells results in increased permeability, mucus overproduction, impaired mucociliary clearance, increased release of proinflammatory cytokines and chemokines, enhanced recruitment of macrophages and neutrophils and disturbed lymphocyte balance towards Th2. The plethora of presented phenomena fully justifies a restrictive policy aiming at limiting the domestic and public exposure to ETS.

Cigarette smoking and the pathogenesis of systemic lupus erythematosus

INTRODUCTION

Systemic lupus erythematosus (SLE) is a multi-system inflammatory autoimmune disease of incompletely understood etiology. It is thought that environmental exposures 'trigger' or accelerate the disease in genetically-predisposed individuals. Areas covered: Substantial epidemiological evidence exists to support the association between cigarette smoking and the risk of incident SLE. Recent evidence points to current smoking as the specific risk factor, with decreasing risk 5 years after smoking cessation, and the greatest risk for disease characterized by the presence of SLE-specific autoantibodies. Research has begun to search for possible explanations for the temporal nature of the relationship between current smoking and autoantibody positive-SLE. Here we review potential biologic mechanisms linking smoking and SLE risk, including effects upon T and B cells, inflammatory cytokines, oxidative stress, and the formation of short-lived DNA adducts. Expert commentary: The directions for future research in this field include studies of gene-environment interactions, epigenetics, metabolomics and putative biologic mechanisms.

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.

Strain- and sex-dependent pulmonary toxicity of waterpipe smoke in mouse

Waterpipe smoking is emerging as a form of tobacco smoking, but its lung health/risks is not known. It has been shown that different mouse strains show differences in susceptibility to tobacco smoke. However, the effect of waterpipe smoke (WPS) exposure and strain differences in susceptibility to oxidative and inflammatory responses is not known. Here, we showed acute WPS exposure induced oxidative stress and inflammatory response in C57BL/6J and BALB/cJ mouse strains. WPS exposure induced inflammatory cell influx (neutrophils and T-lymphocytes) in bronchoalveolar lavage fluid (BAL fluid), which varied among mouse strains. Proinflammatory cytokines release differed among both the strains, but was significantly increased in C57BL/6J mice. Myeloperoxidase levels in BAL fluid were increased significantly in both the strains. Total reduced glutathione (GSH) level was decreased, whereas the level of oxidized or glutathione disulfide (GSSG) increased in lungs of both the strains. Similarly, the level of lipid peroxidation markers, 15-isoprostane (plasma), malondialdehyde and 4-hydroxy-2-nonenal (lung homogenates) were increased by WPS. Our data suggest that, oxidative stress and inflammatory responses are influenced by strain characteristics during acute WPS exposure. Overall, C57BL/6J mice showed more susceptibility to oxidative stress and inflammatory responses compared to BALB/cJ mice. Acute WPS mediated pulmonary toxicity is differentially regulated in different mouse strains.

Delayed-type hypersensitivity to metals in connective tissue diseases and fibromyalgia

Rheumatic diseases include a group of autoimmune disorders with environmental and genetic etiology that are characterized as a subgroup of connective tissue diseases (CTD). Rheumatoid arthritis (RA) often involves the small joints of the hands in a symmetrical fashion that can lead to loss of joint function, and RA, as well as Sjögren's syndrome (SS) and other rheumatic diseases, are often accompanied by sensitivity to metals. Numerous investigations on metal sensitivity were evaluated in this review. A detailed metal exposure history was collected by different evaluation of studies. In all subjects, the main source of metal exposure was nickel, mercury, gold, palladium, titanium, and chromium. All of SLE (systemic lupus erythematosus), RA and SS patients appeared to have an increased frequency of metal delayed-type hypersensitivity (DTH) (Type IV allergy). As dental restorative materials release minor amounts of their metals (including mercury, gold, and nickel), many adults are commonly exposed to these metal ions by vapor or corrosion into saliva. Metal-related DTH in these patients will induce an inflammatory response. Such inflammations are important factors in CTD progress. It is hypothesized that metal-specific T cell reactivity can act as an etiological agent in the propagation and chronification of rheumatic inflammation. The key responses of metal delayed-type hypersensitivity in autoimmunity are precipitating as an appealing challenge for further investigations.

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.

Time-course effects of aerobic physical training in the prevention of cigarette smoke-induced COPD

A previous study by our group showed that regular exercise training (ET) attenuated pulmonary injury in an experimental model of chronic exposure to cigarette smoke (CS) in mice, but the time-course effects of the mechanisms involved in this protection remain poorly understood. We evaluated the temporal effects of regular ET in an experimental model of chronic CS exposure. Male C57BL/6 mice were divided into four groups: Control (sedentary + air), Exercise (aerobic training + air), Smoke (sedentary + smoke), and Smoke + Exercise (aerobic training + smoke). Mice were exposed to CS and ET for 4, 8, or 12 wk. Exercise protected mice exposed to CS from emphysema and reductions in tissue damping and tissue elastance after 12 wk (P < 0.01). The total number of inflammatory cells in the bronchoalveolar lavage increased in the Smoke group, mainly due to the recruitment of macrophages after 4 wk, neutrophils and lymphocytes after 8 wk, and lymphocytes and macrophages after 12 wk (P < 0.01). Exercise attenuated this increase in mice exposed to CS. The protection conferred by exercise was mainly observed after exercise adaptation. Exercise increased IL-6 and IL-10 in the quadriceps and lungs (P < 0.05) after 12 wk. Total antioxidant capacity and SOD was increased and TNF-α and oxidants decreased in lungs of mice exposed to CS after 12 wk (P < 0.05). The protective effects of exercise against lung injury induced by cigarette smoke exposure suggests that anti-inflammatory mediators and antioxidant enzymes play important roles in chronic obstructive pulmonary disease development mainly after the exercise adaptation.NEW & NOTEWORTHY These experiments investigated for the first time the temporal effects of regular moderate exercise training in cigarette smoke-induced chronic obstructive pulmonary disease. We demonstrate that aerobic conditioning had a protective effect in emphysema development induced by cigarette smoke exposure. This effect was most likely secondary to an effect of exercise on oxidant-antioxidant balance and anti-inflammatory mediators.

Protective effect of Galectin-9 in murine model of lung emphysema: Involvement of neutrophil migration and MMP-9 production

Purpose

Chronic obstructive pulmonary disease (COPD) is characterized by irreversible airflow obstruction and pulmonary emphysema. Persistent inflammation and remodeling of the lungs and airways result in reduced lung function and a lower quality of life. Galectin (Gal)-9 plays a crucial role as an immune modulator in various diseases. However, its role in the pathogenesis of pulmonary emphysema is unknown. This study investigates whether Gal-9 is involved in pulmonary inflammation and changes in emphysema in a porcine pancreatic elastase (PPE)-induced emphysema model.

Materials and methods

Gal-9 was administered to mice subcutaneously once daily from 1 day before PPE instillation to day 5. During the development of emphysema, lung tissue and bronchoalveolar lavage fluid (BALF) were collected. Histological and cytological findings, concentrations of chemokines and matrix metalloproteinases (MMPs) in the BALF, and the influence of Gal-9 treatment on neutrophils were analyzed.

Results

Gal-9 suppressed the pathological changes of PPE-induced emphysema. The mean linear intercept (Lm) of Gal-9-treated emphysema mice was significantly lower than that of PBS-treated emphysema mice (66.1 ± 3.3 μm vs. 118.8 ± 14.8 μm, respectively; p < 0.01). Gal-9 decreased the number of neutrophils and levels of MMP-9, MMP-2 and tissue inhibitor of metalloproteinases (TIMP)-1 in the BALF. The number of neutrophils in the BALF correlated significantly with MMPs levels. Interestingly, Gal-9 pretreatment in vitro inhibited the chemotactic activity of neutrophils and MMP-9 production from neutrophils. Furthermore, in Gal-9-deficient mice, PPE-induced emphysema progressed significantly compared with that in wild–type (WT) mice (108.7 ± 6.58 μm vs. 77.19 ± 6.97 μm, respectively; p < 0.01).

Conclusions

These results suggest that Gal-9 protects PPE-induced inflammation and emphysema by inhibiting the infiltration of neutrophils and decreasing MMPs levels. Exogenous Gal-9 could be a potential therapeutic agent for COPD.

Interstital lung disease in ANCA vasculitis

Anti-neutrophil cytoplasmic antibodies (ANCA) vasculitides are immune-mediated disorders that primarily affect small blood vessels of the airway and kidneys. Lung involvement, one of the hallmarks of microscopic polyangiitis and granulomatosis with polyangiitis, is associated with increased mortality and morbidity. In recent years, several retrospective series and case reports have described the association of interstitial lung disease (ILD) and ANCA vasculitis, particularly those positive for ANCA specific for myeloperoxidase. In the majority of these patients pulmonary fibrosis occurs concurrently or predates the diagnosis of ANCA vasculitis. More importantly, these studies have shown that ILD has an adverse impact on the long-term prognosis of ANCA vasculitis. This review focuses on the main clinical and radiologic features of pulmonary fibrosis associated with anti-neutrophil cytoplasmic antibodies. Major histopathology features, prognosis and therapeutic options are summarized.

Microarray Analysis Reveals Increased Expression of Matrix Metalloproteases and Cytokines of Interleukin-20 Subfamily in the Kidneys of Neonate Rats Underwent Unilateral Ureteral Obstruction: A Potential Role of IL-24 in the Regulation of Inflammation and Tissue Remodeling

BACKGROUND/AIMS

Congenital obstructive nephropathy (CON) is the main cause of pediatric chronic kidney diseases leading to renal fibrosis. High morbidity and limited treatment opportunities of CON urge the better understanding of the underlying molecular mechanisms.

METHODS

To identify the differentially expressed genes, microarray analysis was performed on the kidney samples of neonatal rats underwent unilateral ureteral obstruction (UUO). Microarray results were then validated by real-time RT-PCR and bioinformatics analysis was carried out to identify the relevant genes, functional groups and pathways involved in the pathomechanism of CON. Renal expression of matrix metalloproteinase (MMP)-12 and interleukin (IL)-24 were evaluated by real-time RT-PCR, flow cytometry and immunohistochemical analysis. Effect of the main profibrotic factors on the expression of MMP-12 and IL-24 was investigated on HK-2 and HEK-293 cell lines. Finally, the effect of IL-24 treatment on the expression of pro-inflammatory cytokines and MMPs were tested in vitro.

RESULTS

Microarray analysis revealed 880 transcripts showing >2.0-fold change following UUO, enriched mainly in immune response related processes. The most up-regulated genes were MMPs and members of IL-20 cytokine subfamily, including MMP-3, MMP-7, MMP-12, IL-19 and IL-24. We found that while TGF-β treatment inhibits the expression of MMP-12 and IL-24, H2O2 or PDGF-B treatment induce the epithelial expression of MMP-12. We demonstrated that IL-24 treatment decreases the expression of IL-6 and MMP-3 in the renal epithelial cells.

CONCLUSIONS

This study provides an extensive view of UUO induced changes in the gene expression profile of the developing kidney and describes novel molecules, which may play significant role in the pathomechanism of CON.

Evaluating the utility of serological testing in laryngotracheal stenosis

OBJECTIVES/HYPOTHESIS

Whereas mechanical (traumatic) causes of laryngotracheal stenosis (LTS) are identified based on history, autoimmune laryngotracheal stenosis (aLTS) and idiopathic laryngotracheal stenosis (iLTS) are often more difficult to differentiate. The objective of this study was to evaluate serologic testing in a large cohort of nonmechanical LTS patients to determine which tests, if any, lead clinicians to the etiology of the LTS.

STUDY DESIGN

Retrospective chart review.

METHODS

This study reviewed nonmechanical LTS patients seen at a tertiary medical center from 2007 to 2014. Data were obtained on patient demographics, associated preexisting autoimmune conditions, comorbidities, intubation history, and serologic testing.

RESULTS

Ninety-two records were reviewed. Twenty-three (25%) patients were found to have autoimmune disease; 69 (75%) met criteria for iLTS. A history of cigarette smoking was more significant in the aLTS group than the iLTS group (P < .001). Antineutrophil cytoplasmic antibody (ANCA) was positive only in patients with known granulomatosis with polyangiitis (GPA). All other serological testing was equivocal between the two cohorts.

CONCLUSIONS

Differentiating iLTS from aLTS has proven difficult. The lack of information about the two entities has resulted in variability in the diagnostic workup to distinguish them. This study's finding of a more significant smoking history in the aLTS group correlates with the literature, which suggests an inflammatory effect of smoking cigarettes and an association with autoimmune disease. The only significant cohort of patients in this study found to have positive serological testing correlated with a diagnosable condition responsible for LTS was GPA patients with positive ANCA.

LEVEL OF EVIDENCE

4. Laryngoscope, 127:1408-1412, 2017.

Cigarette smoking and autoimmune disease: what can we learn from epidemiology?

Cigarette smoking has been causally linked to the development of multiple autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, Graves' hyperthyroidism, and primary biliary cirrhosis, among others. We review the known biologic effects of cigarette smoke, in particular its actions on the immune system, and the epidemiologic evidence associating smoking with increased risk of each of these autoimmune diseases. Interactions between cigarette smoking and genetic and immunologic factors, such as the human leukocyte antigen (HLA)shared epitope, rheumatoid factor, anti-cyclic citrullinated peptide antibodies, and anti-double stranded DNA antibodies, may point to mechanisms in disease pathogenesis.

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.

Matrikines are key regulators in modulating the amplitude of lung inflammation in acute pulmonary infection

Bioactive matrix fragments (matrikines) have been identified in a myriad of disorders, but their impact on the evolution of airway inflammation has not been demonstrated. We recently described a pathway where the matrikine and neutrophil chemoattractant proline–glycine–proline (PGP) could be degraded by the enzyme leukotriene A₄ hydrolase (LTA₄H). LTA₄H classically functions in the generation of pro-inflammatory leukotriene B₄, thus LTA₄H exhibits opposing pro- and anti-inflammatory activities. The physiological significance of this secondary anti-inflammatory activity remains unknown. Here we show, using readily resolving pulmonary inflammation models, that loss of this secondary activity leads to more pronounced and sustained inflammation and illness owing to PGP accumulation. PGP elicits an exacerbated neutrophilic inflammation and protease imbalance that further degrades the extracellular matrix, generating fragments that perpetuate inflammation. This highlights a critical role for the secondary anti-inflammatory activity of LTA₄H and thus has consequences for the generation of global LTA₄H inhibitors currently being developed.

Proteases degrade extracellular matrix during inflammation, releasing peptides that can recruit neutrophils. Here the authors show that degradation of such bioactive peptide by the enzyme leukotriene A4 hydrolase is critical to limit pulmonary inflammation during bacterial infection in mice.

Interstitial Lung Disease with ANCA-associated Vasculitis

The association between interstitial lung disease (ILD) and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), particularly microscopic polyangiitis (MPA), has been described in a number of case reports and case series reports in the last 2 decades. In addition, patients with pulmonary fibrosis and ANCA positivity but without other manifestations of systemic vasculitis have also been reported. Pulmonary fibrosis was clinically manifested at the time of diagnosis in the majority of AAV patients that developed this condition. Moreover, ANCA-positive conversion occurs in patients initially diagnosed with idiopathic pulmonary fibrosis, and as a result, other manifestations of systemic vasculitis develop in some of these patients. There is significant predominance of myeloperoxidase (MPO)-ANCA and MPA in patients with AAV and ILD. Radiological and pathological findings generally demonstrate usual interstitial pneumonia (pattern) in the lungs of these patients. In most studies, AAV patients with ILD have a worse prognosis than those without it.

Post-transcriptional inactivation of matrix metalloproteinase-12 after focal cerebral ischemia attenuates brain damage

This study highlights the possible pathological role of MMP-12 in the context of ischemic stroke. Male rats were subjected to a two-hour middle cerebral artery occlusion (MCAO) procedure. MMP-12 shRNA expressing plasmid formulation was administered to these rats twenty-four hours after reperfusion. The results showed a predominant upregulation of MMP-12 (approximately 47, 58, 143, and 265 folds on days 1, 3, 5, 7 post-ischemia, respectively) in MCAO subjected rats. MMP-12 expression was localized to neurons, oligodendrocytes and microglia, but not astrocytes. Transcriptional inactivation of MMP-12 significantly reduced the infarct size. The percent infarct size was reduced from 62.87 ± 4.13 to 34.67 ± 5.39 after MMP-12 knockdown compared to untreated MCAO subjected rats. Expression of myelin basic protein was increased, and activity of MMP-9 was reduced in ischemic rat brains after MMP-12 knockdown. Furthermore, a significant reduction in the extent of apoptosis was noticed after MMP-12 knockdown. TNFα expression in the ipsilateral regions of MCAO-subjected rats was reduced after MMP-12 knockdown in addition to the reduced protein expression of apoptotic molecules that are downstream to TNFα signaling. Specific knockdown of MMP-12 after focal cerebral ischemia offers neuroprotection that could be mediated via reduced MMP-9 activation and myelin degradation as well as inhibition of apoptosis.

Preclinical murine models of Chronic Obstructive Pulmonary Disease

Chronic Obstructive Pulmonary Disease (COPD) is a major incurable global health burden and is the 4th leading cause of death worldwide. It is believed that an exaggerated inflammatory response to cigarette smoke causes progressive airflow limitation. This inflammation, where macrophages, neutrophils and T lymphocytes are prominent, leads to oxidative stress, emphysema, small airway fibrosis and mucus hypersecretion. Much of the disease burden and health care utilisation in COPD is associated with the management of its comorbidities and infectious (viral and bacterial) exacerbations (AECOPD). Comorbidities, defined as other chronic medical conditions, in particular skeletal muscle wasting and cardiovascular disease markedly impact on disease morbidity, progression and mortality. The mechanisms and mediators underlying COPD and its comorbidities are poorly understood and current COPD therapy is relatively ineffective. Thus, there is an obvious need for new therapies that can prevent the induction and progression of COPD and effectively treat AECOPD and comorbidities of COPD. Given that access to COPD patients can be difficult and that clinical samples often represent a "snapshot" at a particular time in the disease process, many researchers have used animal modelling systems to explore the mechanisms underlying COPD, AECOPD and comorbidities of COPD with the goal of identifying novel therapeutic targets. This review highlights the mouse models used to define the cellular, molecular and pathological consequences of cigarette smoke exposure and the recent advances in modelling infectious exacerbations and comorbidities of COPD.

Identification of nuclear phosphoproteins as novel tobacco markers in mouse lung tissue following short-term exposure to tobacco smoke

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We analyzed nuclear phosphoprotein expression activated by tobacco smoke exposure.

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253 phosphoproteins were identified in 1-day and 7-day exposure groups.

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Of these, 33 were significantly differentially expressed in control and exposed groups.

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Identified proteins were related to inflammation, response to stress and nicotine.

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OSF3 and spectrin β chain were identified as candidate tobacco smoke markers.

Smoking is a risk factor for lung diseases, including chronic obstructive pulmonary disease and lung cancer. However, the molecular mechanisms mediating the progression of these diseases remain unclear. Therefore, we sought to identify signaling pathways activated by tobacco-smoke exposure, by analyzing nuclear phosphoprotein expression using phosphoproteomic analysis of lung tissue from mice exposed to tobacco smoke. Sixteen mice were exposed to tobacco smoke for 1 or 7 days, and the expression of phosphorylated peptides was analyzed by mass spectrometry. A total of 253 phosphoproteins were identified, including FACT complex subunit SPT16 in the 1-day exposure group, keratin type 1 cytoskeletal 18 (K18), and adipocyte fatty acid-binding protein, in the 7-day exposure group, and peroxiredoxin-1 (OSF3) and spectrin β chain brain 1 (SPTBN1), in both groups. Semi-quantitative analysis of the identified phosphoproteins revealed that 33 proteins were significantly differentially expressed between the control and exposed groups. The identified phosphoproteins were classified according to their biological functions. We found that the identified proteins were related to inflammation, regeneration, repair, proliferation, differentiation, morphogenesis, and response to stress and nicotine. In conclusion, we identified proteins, including OSF3 and SPTBN1, as candidate tobacco smoke-exposure markers; our results provide insights into the mechanisms of tobacco smoke-induced diseases.

Immune response in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major public health problem because of its high prevalence, rising incidence and associated socio-economic cost. The inhalation of toxic particles and gases, mostly tobacco smoke, is the main risk factor for COPD. Yet, not all smokers are equally susceptible to these toxic effects and only a percentage of them develop the disease (so-called 'susceptible smokers'). This, in combination with the observation that COPD shows familial aggregation, suggests that the genetic background of the smoker is a key element in the pathogenesis of the disease. On the other hand, it is well established that 'susceptible' smokers exhibit an enhanced inflammatory response of the lung parenchyma as compared with 'resistant' smokers (i.e., those who manage to maintain lung function within the normal age range despite their habit). Importantly, in COPD patients this inflammatory response does not resolve after quitting smoking, again at variance with resistant smokers. All in all, these observations suggest that the pathogenesis of COPD may involve, in some patients, an autoimmune component which contributes to the enhanced and persistent inflammatory response that characterizes the disease. Here we: i) review briefly the pathobiology of COPD; ii) present the available scientific evidence supporting a potential role for autoimmunity in COPD; iii) propose a three-step pathogenic hypothesis in the transition from smoking to COPD; and iv) discuss potential implications for the diagnosis and treatment of this frequent, growing, devastating and costly disease.

Pathological changes in the COPD lung mesenchyme--novel lessons learned from in vitro and in vivo studies

Chronic obstructive pulmonary disease (COPD) is currently the fourth leading cause of death worldwide and, in contrast to the trend for cardiovascular diseases, mortality rates still continue to climb. This increase is in part due to an aging population, being expanded by the "Baby boomer" generation who grew up when smoking rates were at their peak and by people in developing countries living longer. Sadly, there has been a disheartening lack of new therapeutic approaches to counteract the progressive decline in lung function associated with the disease that leads to disability and death. COPD is characterized by irreversible chronic airflow limitation that is caused by emphysematous destruction of lung elastic tissue and/or obstruction in the small airways due to occlusion of their lumen by inflammatory mucus exudates, narrowing and obliteration. These lesions are mainly produced by the response of the tissue to the repetitive inhalational injury inflicted by noxious gases, including cigarette smoke, which involves interaction between infiltrating inflammatory immune cells, resident cells (e.g. epithelial cells and fibroblasts) and the extra cellular matrix. This interaction leads to tissue destruction and airway remodeling with changes in elastin and collagen, such that the epithelial-mesenchymal trophic unit is dysregulated in both the disease pathologies. This review focuses on: 1--novel inflammatory and remodeling factors that are altered in COPD; 2--in vitro and in vivo models to understand the mechanism whereby the extra cellular matrix environment in altered in COPD; and 3--COPD in the context of wound-repair tissue responses, with a focus on the regulation of mesenchymal cell fate and phenotype.

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.

Inhibition of human neutrophil elastase by pentacyclic triterpenes

SCOPE

Inhibiting human neutrophil elastase (HNE) is a promising strategy for treating inflammatory lung diseases, such as H1N1 and SARS virus infections. The use of sivelestat, the only clinically registered synthesized HNE inhibitor, is largely limited by its risk of organ toxicity because it irreversibly inhibits HNE. Therefore, potent reversible HNE inhibitors are promising alternatives to sivelestat.

METHODS AND RESULTS

An in vitro HNE inhibition assay was employed to screen a series of triterpenes. Six pentacyclic triterpenes, but not tetracyclic triterpenes, significantly inhibited HNE. Of these pentacyclic triterpenes, ursolic acid exhibited the highest inhibitory potency (IC50 = 5.51 µM). The HNE inhibitory activity of ursolic acid was further verified using a mouse model of acute smoke-induced lung inflammation. The results of nuclear magnetic resonance and HNE inhibition kinetic analysis showed that the pentacyclic triterpenes competitively and reversibly inhibited HNE. Molecular docking experiments indicated that the molecular scaffold, 28-COOH, and a double bond at an appropriate location in the pentacyclic triterpenes are important for their inhibitory activity.

CONCLUSION

Our results provide insights into the effects of pentacyclic triterpenes on lung inflammatory actions through reversible inhibition of HNE activity.

Glutathione peroxidase-1 as a novel therapeutic target for COPD

Oxidative stress plays a role in a variety of diseases but it is even more pertinent in chronic obstructive pulmonary disease (COPD) given the increased oxidant burden in smokers. The increased oxidant burden results from the fact that cigarette smoke contains over 4700 different chemical compounds and more than 10(15) oxidants/free radicals per puff. Other factors, such as air pollutants, infections, and occupational dusts that may exacerbate COPD, also have the potential to produce oxidative stress. These oxidants give rise to Reactive Oxygen Species (ROS) that are generated enzymatically by inflammatory and epithelial cells within the lung as part of an inflammatory immune response towards a pathogen or irritant. Thus, while ROS are necessary for host defence against invading pathogens, increased levels of ROS have been implicated in initiating inflammatory responses in the lungs through the activation of transcriptional factors, signal transduction pathways, chromatin remodelling and gene expression of pro-inflammatory mediators. However, the normal lung has developed defences to ROS-mediated damage, which include antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase. In this review we consider the therapeutic potential of the antioxidant enzyme glutathione peroxidase-1 for the treatment of cigarette smoke-induced lung inflammation and damage.

The role of macrophages in obstructive airways disease: chronic obstructive pulmonary disease and asthma

Macrophages are a major cellular component of the innate immune system, and play an important role in the recognition of microbes, particulates, and immunogens and to the regulation of inflammatory responses. In the lung, macrophages react with soluble proteins that bind microbial products in order to remove pathogens and particles and to maintain the sterility of the airway tract. Chronic obstructive pulmonary disease and asthma are both obstructive airway diseases that involve chronic inflammation of the respiratory tract which contributes to disease progression. In the case of COPD, there is increasing evidence that lung macrophages orchestrate inflammation through the release of chemokines that attract neutrophils, monocytes and T cells and the release of several proteases. On the other hand, in asthma, it seems that alveolar macrophages are inappropriately activated and are implicated in the development and progression of the disease. In this review we summarize the current basic and clinical research studies which highlight the role of macrophages in asthma and COPD.

Role of recently migrated monocytes in cigarette smoke-induced lung inflammation in different strain of mice

This study investigates the role of proinflammatory monocytes recruited from blood circulation and recovered in bronchoalveolar lavage (BAL) fluid in mediating the lung damage in a model of acute cigarette smoke (CS)-induced lung inflammation in two strains of mice with different susceptibility to develop emphysema (susceptible -C57BL/6J and non susceptible -129S2/SvHsd). Exposure to whole-body CS for 3 consecutive research cigarettes in one single day induced acute inflammation in the lung of mice. Analysis of BAL fluid showed more influx of recently migrated monocytes at 72 h after CS-exposition in susceptible compared to non susceptible mice. It correlated with an increase in MMP-12 and TNF-α protein levels in the lung tissue, and with an increment of NF-κB translocation to the nucleus measured by electrophoretic mobility shift assay in C57BL/6J mice. To determine the functional role of these proinflammatory monocytes in mediating CS-induced airway inflammation, alveolar macrophages and blood monocytes were transiently removed by pretreatment with intratracheal and intravenous liposome-encapsulated CL2MDP, given 2 and 4 days prior to CS exposure and their repopulation was studied. Monocytes/macrophages were maximally depleted 48 h after last liposome application and subsequently recently migrated monocytes reappeared in BAL fluid of susceptible mice at 72 h after CS exposure. Recently migrated monocytes influx to the lung correlated with an increase in the MMP-12 protein level in the lung tissue, indicating that the increase in proinflammatory monocytes is associated with a major tissue damaging. Therefore our data confirm that the recruitment of proinflammatory recently migrated monocytes from the blood are responsible for the increase in MMP-12 and has an important role in the pathogenesis of lung disease induced by acute lung inflammation. These results could contribute to understanding the different susceptibility to CS of these strains of mice.

B-lymphocyte lineage cells and the respiratory system

Adaptive humoral immune responses in the airways are mediated by B cells and plasma cells that express highly evolved and specific receptors and produce immunoglobulins of most isotypes. In some cases, such as autoimmune diseases or inflammatory diseases caused by excessive exposure to foreign antigens, these same immune cells can cause disease by virtue of overly vigorous responses. This review discusses the generation, differentiation, signaling, activation, and recruitment pathways of B cells and plasma cells, with special emphasis on unique characteristics of subsets of these cells functioning within the respiratory system. The primary sensitization events that generate B cells responsible for effector responses throughout the airways usually occur in the upper airways, tonsils, and adenoid structures that make up the Waldeyer ring. On secondary exposure to antigen in the airways, antigen-processing dendritic cells migrate into secondary lymphoid organs, such as lymph nodes, that drain the upper and lower airways, and further B-cell expansion takes place at those sites. Antigen exposure in the upper or lower airways can also drive expansion of B-lineage cells in the airway mucosal tissue and lead to the formation of inducible lymphoid follicles or aggregates that can mediate local immunity or disease.