Steroid-resistant Inflammation in a Rat Model of Chronic Obstructive Pulmonary Disease Is Associated with a Lack of Nuclear Factor-κB Pathway Activation

Helenine blocks NLRP3 activation by disrupting the NEK7-NLRP3 interaction and ameliorates inflammatory diseases

BACKGROUND

The involvement of NLRP3 inflammasome is associated with the progress of numerous inflammatory conditions. However, there is currently no single compound used in the clinic. Search for the inhibitor of NLRP3 inflammasome from natural products is an attractive direction. The compound Helenin (Hel), which is obtained from Inula helenium L., is reported to have anti-inflammatory activities. However, the underlying molecular mechanisms and specific inflammatory signal pathway remains not well understood.

PURPOSE

This research aims to determine the impacts of Hel on NLRP3 inflammasome and the underlying mechanism involved, meanwhile also assessing its potential as a therapeutic intervention for inflammatory diseases mediated by NLRP3 overactivation.

METHODS

Pretreated with Hel in BMDMs (bone marrow-derived macrophages), then stimulated with NLRP3 triggers and measured the expression of active caspase-1 and interleukin 1β (IL-1β). Determination of intracellular K+ and Ca2+, ASC oligomerization and mitochondrial reactive oxygen species (mtROS) production were employed to explore the preliminary mechanism of Hel on NLRP3 activation. Subsequently, Co-immunoprecipitation was used to investigate protein-protein interaction and reduction of covalent bonds of Hel was to explore the binding mode between drugs and proteins. Finally, in vivo experiments, we utilized mouse lethal sepsis and monosodium urate(MSU)-induced peritonitis models to evaluate the effectiveness of Hel in inhibiting inflammatory diseases.

RESULTS

The findings revealed that Hel exhibited a specific blocking effect on NLRP3, with no impact on the assembly of NLRC4 and AIM2 inflammasome. Through the analysis of mechanisms targeting key upstream factors in NLRP3 activation, Hel inhibited NLRP3-dependent ASC oligomerization but did not regulating inflammasome priming, K+ efflux, Ca2+ influx, or mitochondrial damage and mtROS. Moreover, Hel effectively interrupted the binding of NEK7-NLRP3, which was dependent on the active double C=C of the α,β-unsaturated carbonyl units in Hel. In mouse models, Hel showed promising therapeutic effects in the treatment of NLRP3 overactivation-associated diseases, including the lethal sepsis and acute systemic inflammation induced by lipopolysaccharide (LPS) and peritonitis induced by MSU.

CONCLUSION

Our results indicate that Hel dependent α,β-unsaturated carbonyl units interrupt the formation of the NLRP3-NEK7 interaction, thereby blocks the inflammasome assemblage and activation. These fundings would suggest that Hel is a promising inhibitor for treating diseases driven by NLRP3 overactivation.

Janus kinase/signal transducers and activator of transcription (JAK/STAT) and its role in Lung inflammatory disease

A key signaling channel for the signal transduction of several crucial cytokines implicated in sepsis is the JAK/STAT system. Once cytokines attach to the proper receptors, JAK kinases linked to them are activated and can selectively phosphorylate STATs. Activated STATs subsequently go to the nucleus, where they play a key role in the transcription of the target genes. Various biological activities use the JAK/STAT pathway, including hematopoiesis, immunological modulation, cell differentiation, and apoptosis. Inflammatory lung illnesses affect people worldwide and are a serious public health concern. Numerous common respiratory conditions, such as asthma, bronchiectasis, chronic obstructive pulmonary disease (COPD), and acute respiratory distress syndrome, are strongly influenced by inflammation. Microorganism infections or the destruction or demise of host cells are the causes of inflammation and the factors that perpetuate it. This review discusses the main elements of severe lung inflammation and how the JAK/STAT signaling pathway is essential for lung inflammation.

Nuclear factor-kappa B and its role in inflammatory lung disease

Nuclear factor-kappa B, involved in inflammation, host immune response, cell adhesion, growth signals, cell proliferation, cell differentiation, and apoptosis defense, is a dimeric transcription factor. Inflammation is a key component of many common respiratory disorders, including asthma, chronic obstructive pulmonary disease (COPD), bronchiectasis, and acute respiratory distress syndrome. Many basic transcription factors are found in NF-κB signaling, which is a member of the Rel protein family. Five members of this family c-REL, NF-κB2 (p100/p52), RelA (p65), NF-κB1 (p105/p50), RelB, and RelA (p65) produce 5 transcriptionally active molecules. Proinflammatory cytokines, T lymphocyte, and B lymphocyte cell mitogens, lipopolysaccharides, bacteria, viral proteins, viruses, double-stranded RNA, oxidative stress, physical exertion, various chemotherapeutics are the stimulus responsible for NF-κB activation. NF-κB act as a principal component for several common respiratory illnesses, such as asthma, lung cancer, pulmonary fibrosis, COPD as well as infectious diseases like pneumonia, tuberculosis, COVID-19. Inflammatory lung disease, especially COVID-19, can make NF-κB a key target for drug production.

Animal models of emphysema

OBJECTIVE

Chronic obstructive pulmonary disease (COPD) is a common chronic respiratory disease of human beings characterized by not fully reversible airflow limitation. Emphysema is the main pathological feature of COPD which causes high mortality worldwide every year and consumes a large amount of medical expenses. This paper was to review the establishment and evaluation methods of animal models of emphysema or COPD, and put forward some new ideas on animal selection, method of modeling, and model evaluation.

DATA SOURCES

The author retrieved information from the PubMed database up to July 2019, using various combinations of search terms, including emphysema, model, and animal.

STUDY SELECTION

Original articles, reviews, and other articles were searched and reviewed for animal models of emphysema.

RESULTS

This review summarized animal models of emphysema from the perspectives of animal selection, emphysema mechanism, modeling method and model evaluation, and found that passive smoking is the classic method for developing animal model of emphysema, mice are more suitable for experimental study on emphysema. Compared with pulmonary function indicators, airway inflammation indicators and oxidative stress indicators, pathomorphological indicators of lung tissue are the most important parameters for evaluating the establishment of the animal model of emphysema.

CONCLUSIONS

Mice model induced by passive smoking is the classic animal model of emphysema. Pathomorphological indicators are the most important parameters for evaluating the establishment of the animal model of emphysema.

Establishment of a chronic obstructive pulmonary disease mouse model based on the elapsed time after LPS intranasal instillation

Chronic obstructive pulmonary disease (COPD) was the 3rd leading cause of death in 2012 worldwide. It is particularly severe in the elderly, who are at risk of death by coughing, mucous hypersecretion, and finally breathlessness. Recently, anti-COPD drug development has increased, and many animal screening systems have been studied. Tobacco smoke animal models are the best known animal screening system, but have several preparation requirements, such as a tobacco smoke generator and a separate facility to prevent smoke release. Accordingly, we evaluated the properties of a lipopolysaccharide (LPS) murine model for COPD screening and the effect of the time elapsed from 0 to 72 hr after LPS intranasal instillation on various biomarkers of COPD severity, such as WBC and neutrophils in bronchoalveolar fluid (BALF), IgE in serum, histopathology in the lung, and cytokines (IL-8, TNF-α, IFN-γ, and TGF-β) and chemokines (CCL-2, CXCL1, CXCL9, CXCL10, and CXCL11) in the respiratory system. Although from 48 hr after LPS treatment several factors which could be evaluated as biomarkers for COPD establishment such as WBC and neutrophil in BALF, IgE in serum, cytokines (IL-8, TNF-α, and IFN-γ), and chemokines (CCL-2, CXCL1, CXCL9, CXCL10, and CXCL11) increased at 72 hr the increment of important factors for COPD establishment such as IgE, fibrosis in the lung, and cytokines (IL-8, TNF-α, and IFN-γ) was more clear. Based on our results, we concluded that the optimal time after LPS intranasal instillation is 72 hr.

Tandem mass tags labeled quantitative proteomics to study the effect of tobacco smoke exposure on the rat lung

BACKGROUND

The causal link between tobacco smoke exposure (TSE) and numerous severe respiratory system diseases (RSD), including chronic bronchitis, chronic obstructive pulmonary disease, and lung cancer, is well established. However, the pathogenesis of TSE-induced RSD remains incompletely understood. This research aims to detect the pathogenetic mechanisms and potential therapeutic targets of TSE-induced RSD.

METHODS

This study employed TSE model which rats were exposed to a concentration of 60% tobacco smoke in a toxicant exposure system for four weeks. Tandem mass tags (TMT) labeled quantitative proteomics combined with off-line high pH reversed-phase fractionation, and nano-liquid chromatography-mass spectrometry method (off-line high pH RPF-nano-LC-MS/MS) were adopted to detect differentially expressed proteins (DEPs) in the lung tissues of the TSE model rats and to compare them with those in control. The accuracy of the results was verified by western blot.

RESULTS

Compared with the control group, 33 proteins in the TSE model group's lung tissues showed significant differential expression. Analysis based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways indicated that, several biological pathways, such as the steroid biosynthesis pathway, were involved and played significant roles in the pathogenesis of the experimental group's TSE.

CONCLUSIONS

These findings make a crucial contribution to the search for a comprehensive understanding of TSE-induced RSD's pathogenesis, and furthermore provide guidance for the diagnosis and treatment of TSE-induced RSD.

Paeoniflorin Attenuated Oxidative Stress in Rat COPD Model Induced by Cigarette Smoke

Paeoniflorin (PF), a monoterpene glucoside, might have an effect on the oxidative stress. However, the mechanism is still unknown. In this study, we made the COPD model in Sprague-Dawley (SD) rats by exposing them to the smoke of 20 cigarettes for 1 hour/day and 6 days/week, for 12 weeks, 24 weeks, or 36 weeks. Our findings suggested that smoke inhalation can trigger the oxidative stress from the very beginning. A 24-week treatment of PF especially in the dosage of 40 mg/kg·d can attenuate oxygen stress by partially quenching reactive oxygen species (ROS) and upregulating antioxidant enzymes via an Nrf2-dependent mechanism.

Hyperpolarized 83Kr magnetic resonance imaging of alveolar degradation in a rat model of emphysema

Hyperpolarized ⁸³Kr surface quadrupolar relaxation (SQUARE) generates MRI contrast that was previously shown to correlate with surface-to-volume ratios in porous model surface systems. The underlying physics of SQUARE contrast is conceptually different from any other current MRI methodology as the method uses the nuclear electric properties of the spin I = 9/2 isotope ⁸³Kr. To explore the usage of this non-radioactive isotope for pulmonary pathophysiology, MRI SQUARE contrast was acquired in excised rat lungs obtained from an elastase-induced model of emphysema. A significant ⁸³Kr T₁ relaxation time increase in the SQUARE contrast was found in the elastase-treated lungs compared with the baseline data from control lungs. The SQUARE contrast suggests a reduction in pulmonary surface-to-volume ratio in the emphysema model that was validated by histology. The finding supports usage of ⁸³Kr SQUARE as a new biomarker for surface-to-volume ratio changes in emphysema.

Inhaled corticosteroids increase siglec-5/14 expression in sputum cells of COPD patients

Recent studies show that several Siglec receptors, such as Siglec-8 and Siglec-14, may be important therapeutic targets in asthma and COPD. Siglecs are a family of lectins belonging to the immunoglobulin superfamily and recognize sialic acid residues of glycoproteins. Most of Siglecs have intracellular immunoreceptor tyrosine-based inhibitory motifs (ITIM), implicating them in the suppression of immunoreceptor signaling. Siglec-5/14 may be involved in the negative regulation of innate immune responses. The aim of this study was to analyze Siglec-5/14 expression in induced sputum cells of COPD patients in the following treatment combinations: (1) a long-acting beta2-agonist, formoterol; (2) formoterol combined with a long-acting antimuscarinic agent, tiotropium; and (3) formoterol combined with an inhaled corticosteroid or formoterol combined with tiotropium and with an inhaled corticosteroid. Siglec expression was assessed in sputum cells by flow cytometry using a specific monoclonal antibody. Double staining of cells indicated that Siglec-5/14 is expressed in monocyte/macrophages and neutrophils, but not in lymphocytes. Siglec-5/14 expression was significantly higher in patients receiving combined therapy including inhaled corticosteroids compared with patients taking only formoterol or formoterol + tiotropium. Our results suggest that inhaled corticosteroids may exert beneficial or negative effects, depending on the patients' phenotype, through increased immunosuppressive Siglec-5 or immunoactivatory Siglec-14 receptors, respectively.

High-density lipoproteins potentiate α1-antitrypsin therapy in elastase-induced pulmonary emphysema

Several studies report that high-density lipoproteins (HDLs) can carry α1-antitrypsin (AAT; an elastase inhibitor). We aimed to determine whether injection of exogenous HDL, enriched or not in AAT, may have protective effects against pulmonary emphysema. After tracheal instillation of saline or elastase, mice were randomly treated intravenously with saline, human plasma HDL (75 mg apolipoprotein A1/kg), HDL-AAT (75 mg apolipoprotein A1-3.75 mg AAT/kg), or AAT alone (3.75 mg/kg) at 2, 24, 48, and 72 hours. We have shown that HDL-AAT reached the lung and prevented the development of pulmonary emphysema by 59.3% at 3 weeks (alveoli mean chord length, 22.9 ± 2.8 μm versus 30.7 ± 4.5 μm; P < 0.001), whereas injection of HDL or AAT alone only showed a moderate, nonsignificant protective effect (28.2 ± 4.2 μm versus 30.7 ± 5 μm [P = 0.23] and 27.3 ± 5.66 μm versus 30.71 ± 4.96 μm [P = 0.18], respectively). Indeed, protection by HDL-AAT was significantly higher than that observed with HDL or AAT (P = 0.006 and P = 0.048, respectively). This protective effect was associated (at 6, 24, and 72 h) with: (1) a reduction in neutrophil and macrophage number in the bronchoalveolar lavage fluid; (2) decreased concentrations of IL-6, monocyte chemoattractant protein-1, and TNF-α in both bronchoalveolar lavage fluid and plasma; (3) a reduction in matrix metalloproteinase-2 and matrix metalloproteinase-9 activities; and (4) a reduction in the degradation of fibronectin, a marker of tissue damage. In addition, HDL-AAT reduced acute cigarette smoke-induced inflammatory response. Intravenous HDL-AAT treatment afforded a better protection against elastase-induced pulmonary emphysema than AAT alone, and may represent a significant development for the management of emphysema associated with AAT deficiency.

A role for Rab27 in neutrophil chemotaxis and lung recruitment

Background

Neutrophils are a critical part of the innate immune system. Their ability to migrate into infected or injured tissues precedes their role in microbial killing and clearance. We have previously shown that Rab27a can promote neutrophil migration by facilitating uropod release through protease secretion from primary granule exocytosis at the cell rear. Rab27b has been implicated in primary granule exocytosis but its role in neutrophil migration has not been investigated.

Results

Here we found Rab27b to be expressed in bone marrow derived neutrophils and Rab27b knockout (Rab27b KO) along with Rab27a/b double knockout (Rab27DKO) neutrophils exhibited impaired transwell migration in vitro in response to chemokines MIP-2 and LTB₄. Interestingly, no additional defect in migration was observed in Rab27DKO neutrophils compared with Rab27b KO neutrophils. In vivo, Rab27DKO mice displayed severe impairment in neutrophil recruitment to the lungs in a MIP-2 dependent model but not in an LPS dependent model.

Conclusions

These data taken together implicate Rab27b in the regulation of neutrophil chemotaxis, likely through the regulation of primary granule exocytosis.

Icariin ameliorates cigarette smoke induced inflammatory responses via suppression of NF-κB and modulation of GR in vivo and in vitro

Purpose

To investigate the effects of icariin, a major constituent of flavonoids isolated from the herb Epimedium, on cigarette smoke (CS) induced inflammatory responses in vivo and in vitro.

Methods

In vivo, BALB/c mice were exposed to smoke of 15 cigarettes for 1 h/day, 6 days/week for 3 months and dosed with icariin (25, 50 and 100 mg/kg) or dexamethasone (1 mg/kg). In vitro, A549 cells were incubated with icariin (10, 50 and 100 µM) followed by treatments with CSE (2.5%).

Results

We found that icariin significantly protected pulmonary function and attenuated CS-induced inflammatory response by decreasing inflammatory cells and production of TNF-α, IL-8 and MMP-9 in both the serum and BALF of CS-exposed mice and decreasing production of TNF-α and IL-8 in the supernatant of CSE-exposed A549 cells. Icariin also showed properties in inhibiting the phosphorylation of NF-κB p65 protein and blocking the degradation of IΚB-α protein. Further studies revealed that icariin administration markedly restore CS-reduced GR protein and mRNA expression, which might subsequently contribute to the attenuation of CS-induced respiratory inflammatory response.

Conclusion

Together these results suggest that icariin has anti-inflammatory effects in cigarette smoke induced inflammatory models in vivo and in vitro, possibly achieved by suppressing NF-κB activation and modulating GR protein expression.

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.

Superiority of PC-SOD to other anti-COPD drugs for elastase-induced emphysema and alteration in lung mechanics and respiratory function in mice

Bronchodilators (such as ipratropium bromide), steroids (such as fluticasone propionate), and newly developed anti-inflammatory drugs (such as roflumilast) are used for patients with chronic obstructive pulmonary disease (COPD). We recently reported that lecithinized superoxide dismutase (PC-SOD) confers a protective effect in mouse models of COPD. We here examined the therapeutic effect of the combined administration of PC-SOD with ipratropium bromide on pulmonary emphysema and compared the effect of PC-SOD to other types of drugs. The severity of emphysema in mice was assessed by various criteria. Lung mechanics (elastance) and respiratory function (ratio of forced expiratory volume in the first 0.05 s to forced vital capacity) were assessed. Administration of PC-SOD by inhalation suppressed elastase-induced pulmonary emphysema, alteration of lung mechanics, and respiratory dysfunction. The concomitant intratracheal administration of ipratropium bromide did not alter the ameliorating effects of PC-SOD. Administration of ipratropium bromide, fluticasone propionate, or roflumilast alone did not suppress the elastase-induced increase in the pulmonary level of superoxide anion, pulmonary inflammatory response, pulmonary emphysema, alteration of lung mechanics, or respiratory dysfunction as effectively as did PC-SOD. PC-SOD, but not the other drugs, showed a therapeutic effect even when the drug was administered after the development of emphysema. PC-SOD also suppressed the cigarette smoke-induced pulmonary inflammatory response and increase in airway resistance. Based on these results, we consider that the inhalation of PC-SOD would be therapeutically beneficial for COPD.

Glucocorticoids reduce inflammation in cystic fibrosis bronchial epithelial cells

Reduction of lung inflammation is one of the goals of cystic fibrosis (CF) therapy. Among anti-inflammatory molecules, glucocorticoids (GC) are one of the most prescribed. However, CF patients seem to be resistant to glucocorticoid treatment. Several molecular mechanisms that contribute to decrease anti-inflammatory effects of glucocorticoids have been identified in pulmonary diseases, but the molecular actions of glucocorticoids have never been studied in CF. In the cytoplasm, glucocorticoids bind to glucocorticoid receptor (GR) and then, control NF-κB and MAPK pathways through direct interaction with AP-1 and NF-κB in the nucleus. Conversely, MAPK can regulate glucocorticoid activation by targeting GR phosphorylation. Together these pathways regulate IL-8 release in the lung. Using bronchial epithelial cell lines derived from non CF and CF patients, we analyzed GR-based effects of glucocorticoids on NF-κB and MAPK pathways, after stimulation with TNF-α. We demonstrate that the synthetic glucocorticoid dexamethasone (Dex) significantly decreases IL-8 secretion, AP-1 and NF-κB activity in CF cells in a pro-inflammatory context. Moreover, we show that p38 MAPK controls IL-8 release by determining GR activation through specific phosphorylation on serine 211. Finally, we demonstrate a synergistic effect of dexamethasone treatment and inhibition of p38 MAPK inducing more than 90% inhibition of IL-8 production in CF cells. All together, these results demonstrate the good responsiveness to glucocorticoids of CF bronchial epithelial cells and the reciprocal link between glucocorticoids and p38 MAPK in the control of CF lung inflammation.

Dual bronchodilatory and pulmonary anti-inflammatory activity of RO5024118, a novel agonist at vasoactive intestinal peptide VPAC2 receptors

BACKGROUND AND PURPOSE

Vasoactive intestinal peptide is expressed in the respiratory tract and induces its effects via its receptors, VPAC(1) and VPAC(2). RO5024118 is a selective VPAC(2) receptor agonist derived via chemical modification of an earlier VPAC(2) agonist, RO0251553. In the present studies, we characterized the pharmacological activity of RO5024118.

EXPERIMENTAL APPROACH

Stability of RO5024118 to human neutrophil elastase was assessed. Bronchodilatory activity of RO5024118 was investigated in guinea pig and human isolated airway smooth muscle preparations and in a guinea pig bronchoconstriction model. Pulmonary anti-inflammatory activity of RO5024118 was investigated in a lipopolysaccharide mouse model and in a porcine pancreatic elastase (PPE) rat model.

KEY RESULTS

RO5024118 demonstrated increased stability to neutrophil elastase compared with RO0251553. In human and guinea pig isolated airway preparations, RO5024118 induced bronchodilatory effects comparable with RO0251553 and the long-acting β-agonist salmeterol and was significantly more potent than native vasoactive intestinal peptide and the short-acting β-agonist salbutamol. In 5-HT-induced bronchoconstriction in guinea pigs, RO5024118 exhibited inhibitory activity with similar efficacy as, and longer duration than, RO0251553. In a lipopolysaccharide-mouse model, RO5024118 inhibited neutrophil and CD8(+) cells and myeloperoxidase levels. In rats, intratracheal instillation of PPE induced airway neutrophilia that was resistant to dexamethasone. Pretreatment with RO5024118 significantly inhibited PPE-induced neutrophil accumulation.

CONCLUSIONS AND IMPLICATIONS

These results demonstrate that RO5024118 induces dual bronchodilatory and pulmonary anti-inflammatory activity and may be beneficial in treating airway obstructive and inflammatory diseases.

LINKED ARTICLES

This article is part of a themed section on Analytical Receptor Pharmacology in Drug Discovery. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2010.161.issue-6.

Lung-targeted overexpression of the NF-κB member RelB inhibits cigarette smoke-induced inflammation

Acute lung inflammation can be caused by a variety of respirable agents, including cigarette smoke. Long-term cigarette smoke exposure can cause chronic obstructive pulmonary disease (COPD), a serious illness that affects >10 million Americans. Cigarette smoke is a known inducer of inflammation and is responsible for approximately 90% of all COPD cases. RelB, a member of the NF-κB family, attenuates cigarette smoke-induced inflammatory mediator production in mouse lung fibroblasts in vitro. We hypothesized that overexpression of RelB in the airways of mice would dampen acute smoke-induced pulmonary inflammation. Mice received a recombinant adenovirus encoding RelB by intranasal aspiration to induce transient RelB overexpression in the lungs and were subsequently exposed to mainstream cigarette smoke. Markers of inflammation were analyzed after smoke exposure. Neutrophil infiltration, normally increased by smoke exposure, was significantly and potently decreased after RelB overexpression. Cigarette smoke-induced proinflammatory cytokine and chemokine production, cyclooxygenase-2 expression, and prostaglandin E(2) production were also significantly decreased in the context of RelB overexpression. The expression of intercellular adhesion molecule 1, an NF-κB-dependent protein, was decreased, indicating a potential mechanism through which RelB can regulate inflammatory cell migration. Therefore, increased expression and/or activation of RelB could be a novel therapeutic strategy against acute lung inflammation caused by respirable agents and possibly against chronic injury, such as COPD.

Effects of carbon black nanoparticles on elastase-induced emphysematous lung injury in mice

Although adverse health effects of particulate matter with a diameter of <100 nm (nanoparticles) have been proposed, biological evidence supporting their promotion of the inflammatory lung response in vivo is limited. This study investigated the impact of pulmonary exposure to carbon black nanoparticles (CBNP) on emphysematous lung injury induced by porcine pancreatic elastase (PPE) in mice. Vehicle, two sizes (14 and 56 nm) of CBNP (50 μg/body: 4 mg/kg), PPE (0.03 U/body: 1 U/kg) or PPE + CBNP was administered intratracheally; thereafter, parameters of inflammatory lung changes were evaluated at several time-points. CBNP of 14 nm significantly induced acute lung inflammation in non-elicited subjects and aggravated PPE-elicited airway neutrophilic inflammation at an early stage (day 1), which was concomitant with the enhanced lung expression of pro-inflammatory cytokines such as interleukin-1β and chemokine such as keratinocyte-derived chemoattractant. Further, 14-nm CBNP exaggerated emphysematous lung structural changes at a delayed stage (day 14). On the other hand, 56-nm CBNP induced lung inflammation but did not influence PPE-elicited pathophysiology in the lung. Taken together, CBNP at an optimal size and dose can exacerbate PPE-induced pulmonary inflammation and emphysema. This enhancement may be mediated, at least partly, via the increased local expression of pro-inflammatory molecules.

Moving towards a new generation of animal models for asthma and COPD with improved clinical relevance

Asthma and chronic obstructive pulmonary disease (COPD) are complex inflammatory airway diseases characterised by airflow obstruction that remain leading causes of hospitalization and death worldwide. Animal modelling systems that accurately reflect disease pathophysiology continue to be essential to the development of new therapies for both conditions. In this review, we describe preclinical in vivo models that recapitulate many of the features of asthma and COPD. Specifically, we discuss the pro's and con's of the standard models and highlight recently developed systems designed to more accurately reflect the complexity of both diseases. For instance, clinically relevant allergens (i.e. house dust mite) are now being used to mimic the inflammatory changes and airway remodelling that result after chronic allergen exposures. Additionally, systems are being developed to mimic steroid-resistant and viral exacerbations of allergic inflammation - aspects of asthma where there is an acute need for new therapies. Similarly, COPD models have evolved to align with the improved clinical understanding of the factors contributing to disease progression. This includes using cigarette smoke to model not only airway inflammation and remodelling, but some systemic changes (e.g. hypertension and skeletal muscle alterations) that are thought to influence disease. Further, mouse genetics are being exploited to gain insights into the genetics of COPD susceptibility. The new models of asthma and COPD described herein demonstrate that improved clinical understanding of the diseases and better preclinical models is an iterative process that will hopefully lead to therapies that can effectively manage severe asthma and COPD.

The effects of sleep hypoxia on coagulant factors and hepatic inflammation in emphysematous rats

Objectives

To develop a sleep hypoxia (SH) in emphysema (SHE) rat model and to explore whether SHE results in more severe hepatic inflammation than emphysema alone and whether the inflammation changes levels of coagulant/anticoagulant factors synthesized in the liver.

Methods

Seventy-five rats were put into 5 groups: SH control (SHCtrl), treated with sham smoke exposure (16 weeks) and SH exposure (12.5% O₂, 3 h/d, latter 8 weeks); emphysema control (ECtrl), smoke exposure and sham SH exposure (21% O₂); short SHE (SHEShort), smoke exposure and short SH exposure (1.5 h/d); mild SHE (SHEMild), smoke exposure and mild SH exposure (15% O₂); standard SHE (SHEStand), smoke exposure and SH exposure. Therefore, ECtrl, SHEShort, SHEMild and SHEStand group were among emphysematous groups. Arterial blood gas (ABG) data was obtained during preliminary tests. After exposure, hepatic inflammation (interleukin -6 [IL-6] mRNA and protein, tumor necrosis factor α [TNFα] mRNA and protein) and liver coagulant/anticoagulant factors (antithrombin [AT], fibrinogen [FIB] and Factor VIII [F VIII]) were evaluated. SPSS 11.5 software was used for statistical analysis.

Results

Characteristics of emphysema were obvious in emphysematous groups and ABGs reached SH criteria on hypoxia exposure. Hepatic inflammation parameters and coagulant factors are the lowest in SHCtrl and the highest in SHEStand while AT is the highest in SHCtrl and the lowest in SHEStand. Inflammatory cytokines of liver correlate well with coagulant factors positively and with AT negatively.

Conclusions

When SH is combined with emphysema, hepatic inflammation and coagulability enhance each other synergistically and produce a more significant liver-derivative inflammatory and prothrombotic status.

Preclinical animal models of asthma and chronic obstructive pulmonary disease

Animal models of disease serve a vital function in the search for novel therapeutic approaches. While these systems cannot replicate human disease, they can be used to mimic and investigate mechanisms believed to be central to disease pathogenesis. In this review, we discuss the most relevant and commonly used animal models for asthma and chronic obstructive pulmonary disease (COPD); specifically, models developed for the mouse, rat and guinea pig. Allergens, such as ovalbumin, can be used to induce an IgE-dependent response characterized by early- and late-phase bronchoconstriction, inflammation and airway hyper-responsiveness similar to what occurs in asthmatics. Similarly, elastase and cigarette smoke can be used to replicate steroid-insensitive and progressive inflammation, which leads to lung pathologies that are observed in COPD patients. We also discuss how these models are developing in new ways to more closely reflect the clinical disease. Unfortunately, these models have limitations due to differences in genetics, anatomy and physiology among the species, many of which we have highlighted; however, understanding these differences, careful characterization of these models and parallel in vitro or ex vivo studies using human and relevant animal tissues will overcome some of these issues. In spite of these limitations, as long as studies are designed and interpreted appropriately, in vivo models will continue to be vital for furthering our understanding of disease pathogenesis and for developing new therapies.

Extensive Analysis of Elastase-Induced Pulmonary Emphysema in Rats: ALP in the Lung, a New Biomarker for Disease Progression?

It is accepted that pulmonary exposure of rodents to porcine pancreatic elastase (ELT) induces lesions that morphologically resemble human emphysema. Nonetheless, extensive analysis of this model has rarely been conducted. The present study was designed to extensively examine the effects of ELT on lung inflammation, cell damage, emphysematous change, and cholinergic reactivity in rats. Intratracheal administration of two doses of ELT induced 1) a proinflammatory response in the lung that was characterized by significant infiltration of macrophages and an increased level of interleukin-1beta in lung homogenates, 2) lung cell damage as indicated by higher levels of total protein, lactate dehydrogenase, and alkaline phosphatase (ALP) in lung homogenates, 3) emphysema-related morphological changes including airspace enlargement and progressive destruction of alveolar wall structures, and 4) airway responsiveness to methacholine including an augmented Rn value. In addition, ELT at a high dose was more effective than that at a low dose. This is the novel study to extensively analyze ELT-induced lung emphysema, and the analysis might be applied to future investigations that evaluate new therapeutic agents or risk factors for pulmonary emphysema. In particular, ALP in lung homogenates might be a new biomarker for the disease progression/exacerbation.

Role of matrix metalloproteinases in the inflammatory process of respiratory diseases

Matrix metalloproteinases (MMPs) are a group of proteases known to regulate the turnover of extracellular matrix and thus are suggested to be important in the process of several diseases associated with tissue remodeling. Furthermore, the concept that modulation of airway remodeling including excessive proteolysis damage of the tissue, may be of interest as a basis for future treatment. Degradation of extracellular matrix is currently associated with structural and recruited cell activation and release of inflammatory mediators and MMPs. Indeed, a marked increase in their expression is observed associated with a variety of inflammatory diseases, including respiratory pathologies. In these conditions, we have to consider MMPs as therapeutic targets which can be inhibited by non-selective and/or selective inhibitors as anti-inflammatory compounds. The present review aims to discuss the potential interest of the inhibition of MMP in inflammatory diseases with a focus on respiratory diseases.

MMP/TIMP expression profiles in distinct lung disease models: implications for possible future therapies

BACKGROUND

There is currently a vast amount of evidence in the literature suggesting that matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are involved in the pathogenesis of inflammatory airways diseases, such as asthma and COPD. Despite this, the majority of reports only focus on single MMPs, often only in one model system. This study aimed to investigate the profile of an extensive range of MMP/TIMP levels in three different pre-clinical models of airways disease. These models each have a different and very distinct inflammatory profile, each exhibiting inflammatory characteristics that are similar to that observed in asthma or COPD. Since these models have their own characteristic pathophysiological phenotype, one would speculate that the MMP/TIMP expression profile would also be different.

METHODS

With the use of designed and purchased MMP/TIMP assays, investigation of rat MMP-2, 3, 714 and TIMP-14 mRNA expression was undertaken by Real Time PCR. The three rodent models of airways disease investigated were the endotoxin model, elastase model, and the antigen model.

RESULTS

Intriguingly, we demonstrated that despite the distinct inflammatory profile observed by each model, the MMP/TIMP expression profile is similar between the models, in that the same MMPs/TIMPs were observed to be generally increased or decreased in all three models. It could therefore be speculated that in a particular disease, it may be a complex network of MMPs, rather than an individual MMP, together with inflammatory cytokines and other mediators, that results in the distinct phenotype of inflammatory diseases, such as asthma and COPD.

CONCLUSION

We believe our data may provide key information necessary to understand the role of various MMPs/TIMPs in different inflammatory airway diseases, and aid the development of more selective therapeutics without the side effect profile of current broad-spectrum MMP inhibitors.

Airspace enlargement with airway cell apoptosis in klotho mice: a model of aging lung

Homozygous mutant klotho (KL(-/-)) mice exhibit various characteristics resembling those of human aging, including emphysema. However, age-related changes of lungs have not been fully elucidated. Here, we investigated the structural, functional, biochemical, and cell kinetic alterations of lungs in KL(-/-) mice at 2-12 weeks of age. Homogeneous airspace enlargement and decreased lung elastic recoil were observed in KL(-/-) mice with aging. The apoptotic cells in airway walls in KL(-/-) mice were approximately 6 times greater than those in wild-type (KL(+/+)) mice at 2 weeks of age. However, lipid peroxidation and elastase activity of lungs were not increased in KL(-/-) mice. Western blotting suggested that protein levels of epidermal growth factor (EGF) and phosphorylated extracellular signal-regulated kinase were decreased in KL(-/-) mice. These data suggest that significantly increased apoptosis of airway cells via inhibition of the EGF-dependent pathway may be involved in the development of the aging lungs in KL(-/-) mice.

Liver X receptor agonists increase airway reactivity in a model of asthma via increasing airway smooth muscle growth

The liver X receptors (LXRalpha/beta) are orphan nuclear receptors that are expressed in a large number of cell types and have been shown to have anti-inflammatory properties. Nuclear receptors have previously proved to be amenable targets for small molecular mass pharmacological agents in asthma, and so the effect of an LXR ligand was assessed in models of allergic airway inflammation. LXR agonist, GW 3965, was profiled in rat and mouse models of allergic asthma. In the Brown Norway rats, GW 3965 (3-30 mg/kg) was unable to reduce the bronchoalveolar lavage eosinophilia associated with this model and had no impact on inflammatory biomarkers (eotaxin and IL-1beta). The compound did significantly stimulate ABCA-1 (ATP-binding cassette A1) mRNA expression, indicating that there was adequate exposure/LXR activation. In the mouse model, the LXR ligand surprisingly increased airway reactivity, an effect that was apparent in both the Ag and nonchallenged groups. This increase was not associated with a change in lung tissue inflammation or number of mucus-containing cells. There was, however, a marked increase in airway smooth muscle thickness in both treated groups. We demonstrated an increase in contractile response to exogenous methacholine in isolated airways taken from LXR agonist-treated animals compared with the relevant control tissue. We corroborated these findings in a human system by demonstrating increased proliferation of cultured airway smooth muscle. This phenomenon, if evidenced in man, would indicate that LXR ligands may directly increase airway reactivity, which could be detrimental, especially in patients with existing respiratory disease and with already compromised lung function.

Targeting the NF-kappaB pathway in asthma and chronic obstructive pulmonary disease

Asthma and chronic obstructive pulmonary disease are inflammatory lung disorders responsible for significant morbidity and mortality worldwide. While the importance of allergic responses in asthma is well known, respiratory viral and bacterial infections and pollutants especially cigarette smoke are important factors in the pathogenesis of both diseases. Corticosteroid treatment remains the first preference of treatment in either disease, however these therapies are not always completely effective, and are associated with side effects and steroid resistance. Due to such limitations, development of new treatments represents a major goal for both the pharmaceutical industry and academic researchers. There are now excellent reasons to promote NF-kappaB signalling intermediates and Rel family proteins as potential therapeutic targets for both asthma and chronic obstructive pulmonary disease. This notion is supported by the fact that much of the underlying inflammation of both diseases independent of stimuli, is mediated at least in part, by NF-kappaB mediated signalling events in several cell types. Also, a range of inhibitors of NF-kappaB signalling intermediates are now available, including DNA oligonucleotides and DNA-peptide molecules that act as NF-kappaB decoy sequences, small molecule inhibitors such as IKK-beta inhibitors, and proteasome inhibitors affecting NF-kappaB signalling, that have either shown promise in animal models or have begun clinical trials in other disorders. This review will focus on the role of NF-kappaB in both diseases, will discuss its suitability as a target, and will highlight recent key studies that support the potential of NF-kappaB as a therapeutic target in these two important inflammatory lung diseases.

Pulmonary perfusion imaging in the rodent lung using dynamic contrast-enhanced MRI

With the development of various models of pulmonary disease, there is tremendous interest in quantitative regional assessment of pulmonary function. While ventilation imaging has been addressed to a certain extent, perfusion imaging for small animals has not kept pace. In humans and large animals perfusion can be assessed using dynamic contrast-enhanced (DCE) MRI with a single bolus injection of a gadolinium (Gd)-based contrast agent. But the method developed for the clinic cannot be translated directly to image the rodent due to the combined requirements of higher spatial and temporal resolution. This work describes a novel image acquisition technique staggered over multiple, repeatable bolus injections of contrast agent using an automated microinjector, synchronized with image acquisition to achieve dynamic first-pass contrast enhancement in the rat lung. This allows dynamic first-pass imaging that can be used to quantify pulmonary perfusion. Further improvements are made in the spatial and temporal resolution by combining the multiple injection acquisition method with Interleaved Radial Imaging and "Sliding window-keyhole" reconstruction (IRIS). The results demonstrate a simultaneous increase in spatial resolution (<200 mum) and temporal resolution (<200 ms) over previous methods, with a limited loss in signal-to-noise-ratio.

p38alpha-selective mitogen-activated protein kinase inhibitor SD-282 reduces inflammation in a subchronic model of tobacco smoke-induced airway inflammation

Chronic obstructive pulmonary disease (COPD) is characterized by pulmonary inflammation, which is relatively insensitive to inhaled corticosteroids. The extent of the pulmonary inflammation in COPD correlates with disease severity, and it is thought to play a significant role in disease progression. We have evaluated a selective p38alpha-selective mitogen-activated protein kinase (MAPK) inhibitor, indole-5-carboxamide (ATP-competitive inhibitor of p38 kinase) (SD-282), in an 11-day model of tobacco smoke (TS)-induced pulmonary inflammation in A/J mice, by using dexamethasone as a reference steroid. Two oral treatment paradigms were evaluated in this TS model: prophylactic with daily pretreatment before each daily exposure, and therapeutic with daily treatment for 6 days commencing after 5 days of smoke exposure. Bronchoalveolar lavage and histological evaluation of lung sections taken after exposure to TS revealed an inflammatory response composed of increased numbers of macrophages and neutrophils and enhanced mucin staining. Phospho-p38 staining in macrophages and type II epithelial cells after TS exposure was also observed. Given prophylactically or therapeutically, dexamethasone failed to inhibit any of the TS-induced inflammatory changes. By contrast, SD-282 inhibited TS-induced increases in macrophages and neutrophils. Furthermore, SD 282 reduced TS-induced increases in cyclooxygenase-2 and interleukin-6 levels, and phospho-p38 expression in the lungs. In conclusion, SD-282 markedly reduced TS-induced inflammatory responses when given prophylactically or therapeutically whereas dexamethasone was ineffective. This is the first evidence that a p38alpha-selective MAPK inhibitor can exert pulmonary anti-inflammatory activity in a TS exposure model when given in a therapeutic mode, establishing the potential of p38 MAPK inhibitors as a therapy for COPD.

Comprehensive gene expression profiling of rat lung reveals distinct acute and chronic responses to cigarette smoke inhalation

Chronic obstructive pulmonary disease (COPD) is a smoking-related disease that lacks effective therapies due partly to the poor understanding of disease pathogenesis. The aim of this study was to identify molecular pathways that could be responsible for the damaging consequences of smoking. To do this, we employed Gene Set Enrichment Analysis to analyze differences in global gene expression, which we then related to the pathological changes induced by cigarette smoke (CS). Sprague-Dawley rats were exposed to whole body CS for 1 day and for various periods up to 8 mo. Gene Set Enrichment Analysis of microarray data identified that metabolic processes were most significantly increased early in the response to CS. Gene sets involved in stress response and inflammation were also upregulated. CS exposure increased neutrophil chemokines, cytokines, and proteases (MMP-12) linked to the pathogenesis of COPD. After a transient acute response, the CS-exposed rats developed a distinct molecular signature after 2 wk, which was followed by the chronic phase of the response. During this phase, gene sets related to immunity and defense progressively increased and predominated at the later time points in smoke-exposed rats. Chronic CS inhalation recapitulated many of the phenotypic changes observed in COPD patients including oxidative damage to macrophages, a slowly resolving inflammation, epithelial damage, mucus hypersecretion, airway fibrosis, and emphysema. As such, it appears that metabolic pathways are central to dealing with the stress of CS exposure; however, over time, inflammation and stress response gene sets become the most significantly affected in the chronic response to CS.

Keratinocyte growth factor protects against elastase-induced pulmonary emphysema in mice

Pulmonary emphysema is characterized by persistent inflammation and progressive alveolar destruction. The keratinocyte growth factor (KGF) favorably influences alveolar maintenance and repair and possesses anti-inflammatory properties. We aimed to determine whether exogenous KGF prevented or corrected elastase-induced pulmonary emphysema in vivo. Treatment with 5 mg x kg(-1) x day(-1) KGF before elastase instillation prevented pulmonary emphysema. This effect was associated with 1) a sharp reduction in bronchoalveolar lavage fluid total protein and inflammatory cell recruitment, 2) a reduction in the pulmonary expression of the chemokines CCL2 (or monocyte chemoattractant protein-1) and CXCL2 (or macrophage inflammatory protein-2alpha) and of the adhesion molecules ICAM-1 and VCAM-1, 3) a reduction in matrix metalloproteinase (MMP)-2 and MMP-9 activity at day 3, and 4) a major reduction in DNA damage detected by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) in alveolar cells at day 7. Treatment with KGF after elastase instillation had no effect on elastase-induced emphysema despite the conserved expression of the KGF receptor in the lungs of elastase-instilled animals as determined by immunohistochemistry. In vitro, KGF abolished the elastase-induced increase in CCL2, CXCL2, and ICAM-1 mRNA in the MLE-12 murine alveolar epithelial cell line. We conclude that KGF pretreatment protected against elastase-induced pulmonary inflammation, activation of MMPs, alveolar cell DNA damage, and subsequent emphysema in mice.

The Effect of Smoking on the Transcriptional Regulation of Lung Inflammation in Patients with Chronic Obstructive Pulmonary Disease

RATIONALE

Chronic obstructive pulmonary disease (COPD) is believed to result from an abnormal inflammatory response in the lungs to noxious particles and gases usually found in cigarette smoke.

OBJECTIVES

In this study, the molecular mechanisms for the enhanced proinflammatory cytokine gene transcription in COPD were investigated.

METHODS

Lung tissue was examined from 56 subjects undergoing resection for peripheral lung tumors as follows: current smokers with (n = 14) and without COPD (n = 17), ex-smokers with COPD (n = 13), and nonsmokers (n = 12). The levels of inhibitor kappaB-alpha (IkappaB-alpha), histone deacetylase 2 (HDAC2), acetylated (ac-) histone H3 and H4, the transcription factor nuclear factor-kappaB (NF-kappaB), proinflammatory cytokine messenger RNA, and 8-isoprostane were measured.

MEASUREMENTS AND MAIN RESULTS

IkappaB-alpha levels were significantly decreased in healthy smokers and current and ex-smoking patients with COPD when compared with nonsmokers (p < 0.001), with an associated increase in NF-kappaB DNA binding in current smokers (p < 0.05). An increase in acetylated histone 4 (ac-H4; p < 0.01) was found in current smokers. Conversely, ex-smokers with COPD showed an increase in ac-H3 (p < 0.05). Decreased levels of cytoplasmic, but not nuclear, HDAC2 protein levels were detected. From the cytokine profiles, no significant differences were detected; however, interleukin-12p40 expression correlated with ac-H4 in current smokers with COPD (p < 0.01).

CONCLUSION

These data propose a role for modification of nucleosomal structure in inflammatory cytokine gene transcription in response to smoking. The imbalance between histone deacetylation and acetylation in favor of acetylation may contribute to the enhanced inflammation in smokers susceptible to the development of COPD.

Role of matrix metalloproteinases in the inflammatory response in human airway cell-based assays and in rodent models of airway disease

Since the discovery of the first matrix metalloproteinase (MMP), this ever-growing family of proteinases has been the subject of intense research. Although it was initially believed that MMPs were solely involved in matrix turnover and degradation, there are now data suggesting MMPs are actively involved in the inflammatory process. In previous studies, we have demonstrated an increase in MMP expression in human cell-based assays and in preclinical rat models of airway inflammation. Therefore, the aim of this study was to characterize the role of MMPs in these models by profiling the impact of a broad-spectrum MMP inhibitor. In lipopolysaccharide (LPS)-stimulated THP-1 cells and primary human lung tissue macrophages, the MMP inhibitor had no significant effect on the release of tumor necrosis factor-alpha, interleukin (IL)-8, IL-1 beta, growth-regulated oncogene-alpha, macrophage inflammatory protein-1 alpha, or IL-6 whereas dexamethasone has a significant impact on all cytokines from both cell types. Similarly, in the more biologically complex LPS-driven rat model of airway inflammation, the MMP inhibitor did not have an impact on mediator release and cellular burden. The compound did, however, significantly reduce levels of lung MMP-9. Furthermore, in a "disease" model, the compound did not affect cellular inflammation but did significantly reduce elastase-induced experimental emphysema. In summary, these data demonstrate for the first time that MMPs do not play a role in the increase in inflammatory mediators or cellular burden observed in these preclinical models. However, they do appear to be involved in the elastase-driven breakdown of airway structure, which is not due to a direct effect of the stimulus.

IkappaB kinase-2-independent and -dependent inflammation in airway disease models: relevance of IKK-2 inhibition to the clinic

Nuclear factor kappaB (NF-kappaB) is a transcription factor believed to be central in the expression of numerous inflammatory genes and the pathogenesis of many respiratory diseases. We have previously demonstrated increased NF-kappaB pathway activation in a steroid-sensitive animal model of lipopolysaccharide (LPS)-driven airway inflammation. It is noteworthy that this phenomenon was not observed in a steroid-insensitive model of elastase-induced inflammation in the rat. The aim of this study was to gather further evidence to suggest that these similar profiles of neutrophilic inflammation can be NF-kappaB-dependent or -independent by determining the impact of an IkappaB kinase-2 (IKK-2) inhibitor, 2-[(aminocarbonyl)amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide (TPCA-1). In the LPS model, TPCA-1 blocked the increase in NF-kappaB DNA binding, a marker of NF-kappaB pathway activation. This inhibition was associated with a reduction in inflammatory mediator release [tumor necrosis factor alpha (TNFalpha)/interleukin-1beta (IL-1beta)/matrix metalloproteinase-9 (MMP-9)] and lung inflammatory cell burden (neutrophilia/eosinophilia). These data were paralleled with a steroid and in human cell based assays. In the elastase-driven inflammation model, in which our group has previously failed to measure an increase in NF-kappaB DNA binding, neither TPCA-1 nor the steroid, affected mediator release (IL-1beta/MMP-9) or cellular burden (neutrophilia/lymphomononuclear cells). This is the first study to examine the effect of an IKK-2 inhibitor in well validated models that mimic aspects of the inflammatory lesion evident in diseases such as COPD. In conclusion, we have demonstrated that animal models with similar profiles of airway inflammation can be IKK-2 inhibitor/steroid-sensitive or -insensitive. If both profiles of inflammation exist in the clinic, then this finding is extremely exciting and may lead to greater understanding of disease pathology and the discovery of novel anti-inflammatory targets.