Quercetin prevents progression of disease in elastase/LPS-exposed mice by negatively regulating MMP expression

Ginkgo Flavonol Glycosides or Ginkgolides Tend to Differentially Protect Myocardial or Cerebral Ischemia-Reperfusion Injury via Regulation of TWEAK-Fn14 Signaling in Heart and Brain

Shuxuening injection (SXNI), one of the pharmaceutical preparations of Ginkgo biloba extract, has significant effects on both ischemic stroke and heart diseases from bench to bedside. Its major active ingredients are ginkgo flavonol glycosides (GFGs) and ginkgolides (GGs). We have previously reported that SXNI as a whole protected ischemic brain and heart, but the active ingredients and their contribution to the therapeutic effects remain unclear. Therefore, we combined experimental and network analysis approach to further explore the specific effects and underlying mechanisms of GFGs and GGs of SXNI on ischemia–reperfusion injury in mouse brain and heart. In the myocardial ischemia–reperfusion injury (MIRI) model, pretreatment with GFGs at 2.5 ml/kg was superior to the same dose of GGs in improving cardiac function and coronary blood flow and reducing the levels of lactate dehydrogenase and aspartate aminotransferase in serum, with an effect similar to that achieved by SXNI. In contrast, pretreatment with GGs at 2.5 ml/kg reduced cerebral infarction area and cerebral edema similarly to that of SXNI but more significantly compared with GFGs in cerebral ischemia–reperfusion injury (CIRI) model. Network pharmacology analysis of GFGs and GGs revealed that tumor necrosis factor-related weak inducer of apoptosis (TWEAK)–fibroblast growth factor-inducible 14 (Fn14) signaling pathway as an important common mechanism but with differential targets in MIRI and CIRI. In addition, immunohistochemistry and enzyme linked immunosorbent assay (ELISA) assays were performed to evaluate the regulatory roles of GFGs and GGs on the common TWEAK–Fn14 signaling pathway to protect the heart and brain. Experimental results confirmed that TWEAK ligand and Fn14 receptor were downregulated by GFGs to mitigate MIRI in the heart while upregulated by GGs to improve CIRI in the brain. In conclusion, our study showed that GFGs and GGs of SXNI tend to differentially protect brain and heart from ischemia–reperfusion injuries at least in part by regulating a common TWEAK–Fn14 signaling pathway.

Cellular senescence in the lung across the age spectrum

Cellular senescence results in cell cycle arrest with secretion of cytokines, chemokines, growth factors, and remodeling proteins (senescence-associated secretory phenotype; SASP) that have autocrine and paracrine effects on the tissue microenvironment. SASP can promote remodeling, inflammation, infectious susceptibility, angiogenesis, and proliferation, while hindering tissue repair and regeneration. While the role of senescence and the contributions of senescent cells are increasingly recognized in the context of aging and a variety of disease states, relatively less is known regarding the portfolio and influences of senescent cells in normal lung growth and aging per se or in the induction or progression of lung diseases across the age spectrum such as bronchopulmonary dysplasia, asthma, chronic obstructive pulmonary disease, or pulmonary fibrosis. In this review, we introduce concepts of cellular senescence, the mechanisms involved in the induction of senescence, and the SASP portfolio that are relevant to lung cells, presenting the potential contribution of senescent cells and SASP to inflammation, hypercontractility, and remodeling/fibrosis: aspects critical to a range of lung diseases. The potential to blunt lung disease by targeting senescent cells using a novel class of drugs (senolytics) is discussed. Potential areas for future research on cellular senescence in the lung are identified.

Rhinovirus-induces progression of lung disease in a mouse model of COPD via IL-33/ST2 signaling axis

Rhinovirus (RV), which is associated with acute exacerbations, also causes persistent lung inflammation in patients with chronic obstructive pulmonary disease (COPD), but the underlying mechanisms are not well-known. Recently, we demonstrated that RV causes persistent lung inflammation with accumulation of a subset of macrophages (CD11b⁺/CD11c⁺), and CD8⁺ T cells, and progression of emphysema. In the present study, we examined the mechanisms underlying the RV-induced persistent inflammation and progression of emphysema in mice with COPD phenotype. Our results demonstrate that at 14 days post-RV infection, in addition to sustained increase in CCL3, CXCL-10 and IFN-γ expression as previously observed, levels of interleukin-33 (IL-33), a ligand for ST2 receptor, and matrix metalloproteinase (MMP)12 are also elevated in mice with COPD phenotype, but not in normal mice. Further, MMP12 was primarily expressed in CD11b⁺/CD11c⁺ macrophages. Neutralization of ST2, reduced the expression of CXCL-10 and IFN-γ and attenuated accumulation of CD11b⁺/CD11c⁺ macrophages, neutrophils and CD8⁺ T cells in COPD mice. Neutralization of IFN-γ, or ST2 attenuated MMP12 expression and prevented progression of emphysema in these mice. Taken together, our results indicate that RV may stimulate expression of CXCL-10 and IFN-γ via activation of ST2/IL-33 signaling axis, which in turn promote accumulation of CD11b+/CD11c+ macrophages and CD8⁺ T cells. Furthermore, RV-induced IFN-γ stimulates MMP12 expression particularly in CD11b⁺/CD11c⁺ macrophages, which may degrade alveolar walls thus leading to progression of emphysema in these mice. In conclusion, our data suggest an important role for ST2/IL-33 signaling axis in RV-induced pathological changes in COPD mice.

Quercetin prevents rhinovirus-induced progression of lung disease in mice with COPD phenotype

Acute exacerbations are the major cause of morbidity and mortality in patients with chronic obstructive pulmonary disease (COPD). Rhinovirus, which causes acute exacerbations may also accelerate progression of lung disease in these patients. Current therapies reduces the respiratory symptoms and does not treat the root cause of exacerbations effectively. We hypothesized that quercetin, a potent antioxidant and anti-inflammatory agent with antiviral properties may be useful in treating rhinovirus-induced changes in COPD. Mice with COPD phenotype maintained on control or quercetin diet and normal mice were infected with sham or rhinovirus, and after 14 days mice were examined for changes in lung mechanics and lung inflammation. Rhinovirus-infected normal mice showed no changes in lung mechanics or histology. In contrast, rhinovirus-infected mice with COPD phenotype showed reduction in elastic recoiling and increase in lung inflammation, goblet cell metaplasia, and airways cholinergic responsiveness compared to sham-infected mice. Interestingly, rhinovirus-infected mice with COPD phenotype also showed accumulation of neutrophils, CD11b⁺/CD11c⁺ macrophages and CD8+ T cells in the lungs. Quercetin supplementation attenuated rhinovirus-induced all the pathologic changes in mice with COPD phenotype. Together these results indicate that quercetin effectively mitigates rhinovirus-induced progression of lung disease in a mouse model of COPD. Therefore, quercetin may be beneficial in the treatment of rhinovirus-associated exacerbations and preventing progression of lung disease in COPD.

Rhinovirus and COPD airway epithelium

Chronic Obstructive Pulmonary Disease (COPD) is characterized by irreversible airflow limitation. It is a global disease and expected to be the third leading cause of death. Respiratory exacerbations are associated with increased mortality and morbidity in this patient population. Respiratory viruses were isolated from at least 30 to 50% of the infectious respiratory COPD exacerbations with rhinovirus being most commonly isolated pathogen. Although rhinovirus does not cause airway epithelial damage like influenza and other respiratory viruses, it may further impair innate immunity of airway epithelium, which is the first line of defense in the lungs. This may increase susceptibility to secondary bacterial infections leading to progression of lung disease. Currently, there arc no therapies available to treat rhinovirus infection in COPD and therefore understanding the mechanisms underlying RV pathogenesis in COPD is essential to identify molecular target to develop new therapeutic strategies. Quercetin, a plant polyphenol, which modulates innate immunity and effectively blocks viral replication may be useful in treating rhinovirus associated COPD exacerbations.

Therapeutic Potential of Medicinal Plants and Their Constituents on Lung Inflammatory Disorders

Acute bronchitis and chronic obstructive pulmonary diseases (COPD) are essentially lung inflammatory disorders. Various plant extracts and their constituents showed therapeutic effects on several animal models of lung inflammation. These include coumarins, flavonoids, phenolics, iridoids, monoterpenes, diterpenes and triterpenoids. Some of them exerted inhibitory action mainly by inhibiting the mitogen-activated protein kinase pathway and nuclear transcription factor-κB activation. Especially, many flavonoid derivatives distinctly showed effectiveness on lung inflammation. In this review, the experimental data for plant extracts and their constituents showing therapeutic effectiveness on animal models of lung inflammation are summarized.

The Effects of Quercetin on Acute Lung Injury and Biomarkers of Inflammation and Oxidative Stress in the Rat Model of Sepsis

Experimental studies indicate that sepsis causes remote organ injury although the molecular mechanism has not been clearly defined. In this report, the role of oxidative damage, and inflammation on lung injury, following sepsis model by cecal ligation and puncture, and the effects of quercetin, antioxidant, and anti-inflammatory flavonoid, in the lung tissue were investigated. In the present study, we found that administration of single-dose quercetin before cecal ligation and puncture procedure, while markedly diminishing the levels of YKL-40 and oxidant molecules (xanthine oxidase (XO), nitric oxide (NO), and malondialdehyde (MDA)), increases the antioxidant enzymes levels. Quercetin is beneficial to acute lung injury by decreasing the levels of oxidative stress markers and increasing the antioxidant enzyme activities. Quercetin also causes a decrease in the serum levels of YKL-40 and periostin in the oxidative lung injury induced by the experimental sepsis model.

TLR2 Activation Limits Rhinovirus-Stimulated CXCL-10 by Attenuating IRAK-1-Dependent IL-33 Receptor Signaling in Human Bronchial Epithelial Cells

Airway epithelial cells are the major target for rhinovirus (RV) infection and express proinflammatory chemokines and antiviral cytokines that play a role in innate immunity. Previously, we demonstrated that RV interaction with TLR2 causes ILR-associated kinase-1 (IRAK-1) depletion in both airway epithelial cells and macrophages. Further, IRAK-1 degradation caused by TLR2 activation was shown to inhibit ssRNA-induced IFN expression in dendritic cells. Therefore, in this study, we examined the role of TLR2 and IRAK-1 in RV-induced IFN-β, IFN-λ1, and CXCL-10, which require signaling by viral RNA. In airway epithelial cells, blocking TLR2 enhanced RV-induced expression of IFNs and CXCL-10. By contrast, IRAK-1 inhibition abrogated RV-induced expression of CXCL-10, but not IFNs in these cells. Neutralization of IL-33 or its receptor, ST2, which requires IRAK-1 for signaling, inhibited RV-stimulated CXCL-10 expression. In addition, RV induced expression of both ST2 and IL-33 in airway epithelial cells. In macrophages, however, RV-stimulated CXCL-10 expression was primarily dependent on TLR2/IL-1R. Interestingly, in a mouse model of RV infection, blocking ST2 not only attenuated RV-induced CXCL-10, but also lung inflammation. Finally, influenza- and respiratory syncytial virus-induced CXCL-10 was also found to be partially dependent on IL-33/ST2/IRAK-1 signaling in airway epithelial cells. Together, our results indicate that RV stimulates CXCL-10 expression via the IL-33/ST2 signaling axis, and that TLR2 signaling limits RV-induced CXCL-10 via IRAK-1 depletion at least in airway epithelial cells. To our knowledge, this is the first report to demonstrate the role of respiratory virus-induced IL-33 in the induction of CXCL-10 in airway epithelial cells.

Choline Triggers Exacerbations of Chronic Obstructive Pulmonary Disease in Patients Infected with Pseudomonas aeruginosa

Background

Although exacerbations of chronic obstructive pulmonary disease produced by Pseudomonas aeruginosa infections are a major cause of death, the molecular mechanism that produces them is not well known. Here we focused on the energetic basis of dyspnoea, hypercapnia and acidosis symptoms.

Methods and Findings

We used an in vivo exacerbation model exposing mice to cigarette smoke and LPS, to mimic emphysema and infections, and choline challenges to trigger exacerbations, that showed 31% increased in the airway resistance for naïve mice and 250% for smoke/LPS treatment. Tissue resistance was increased 32%, in naïve mice, and 169% for smoke/LPS treatment. A decreased tissue elastance, was confirmed by decreased collagen content and increased alveoli chord length. Consequently, the O₂ demanded was 260% greater for smoke/LPS treated mice, to provide the energy required to pump the same volume of air then for naïve mice. The extra CO₂ produced per ml of air pumped caused hypercapnia and acidosis by 4% decrease in pH.In addition, the bacteria grown with choline had a decrease of 67% in phosphate, 23% ATP and 85% phospholipids with an increase of 57% in polyphosphates, 50% carbohydrates, 100% LPS, consuming 45% less energy relative to the bacteria grown with succinate.

Conclusion

choline, released by P. aeruginosa, triggers exacerbation symptoms by increasing lung resistance, O₂ consumption and producing more pCO₂ in blood with dyspnea, hypercapnia and acidosis. The energetic shift of decreased O₂ bacterial demand and increased lung demand benefits the infection, thus restoring the energetic balance on the host will favor P. aeruginosa eradication.

Protective effect of quercetin on pig intestinal integrity after transport stress is associated with regulation oxidative status and inflammation

This experiment was conducted to evaluate the effects of quercetin supplementation on intestinal integrity, intestinal reactive oxygen species (ROS) levels and intestinal inflammation in pigs under transport stress. A total of 170 finishing pigs were randomly assigned into two groups. Animals in the control group consumed a basal diet, while those in the treatment group consumed the same diet supplemented with 25 mg quercetin per kg feed. After a 4-week period, pigs were transported for 5 hr. The quercetin-supplemented pigs showed decreased serum levels of endotoxin (P<0.05), increased height of jejunum villi (P<0.05), and increased occludin and zonula occudens-1 (ZO-1) mRNA expression in the jejunum (P<0.05). These parameters are associated with intestinal health and were markedly improved by quercetin supplementation. Pigs consuming the quercetin-supplemented diet had lower intestinal levels of ROS and malondialdehyde (MDA) compared with the control group (P<0.05). This finding coincided with greater inhibition of the innate immune system (P<0.05), including mitogen-activated protein kinase (MAPK), protein kinase B (Akt) and nuclear factor κB (NF-κB) signaling pathways, as well as decreased expression of inflammatory cytokines in the jejunum. These results indicate that quercetin alleviates intestinal injury in pigs during transport, probably through modulation of intestinal oxidative status and inflammation.

Identification of drug-specific pathways based on gene expression data: application to drug induced lung injury

Identification of signaling pathways that are functional in a specific biological context is a major challenge in systems biology, and could be instrumental to the study of complex diseases and various aspects of drug discovery. Recent approaches have attempted to combine gene expression data with prior knowledge of protein connectivity in the form of a PPI network, and employ computational methods to identify subsets of the protein-protein-interaction (PPI) network that are functional, based on the data at hand. However, the use of undirected networks limits the mechanistic insight that can be drawn, since it does not allow for following mechanistically signal transduction from one node to the next. To address this important issue, we used a directed, signaling network as a scaffold to represent protein connectivity, and implemented an Integer Linear Programming (ILP) formulation to model the rules of signal transduction from one node to the next in the network. We then optimized the structure of the network to best fit the gene expression data at hand. We illustrated the utility of ILP modeling with a case study of drug induced lung injury. We identified the modes of action of 200 lung toxic drugs based on their gene expression profiles and, subsequently, merged the drug specific pathways to construct a signaling network that captured the mechanisms underlying Drug Induced Lung Disease (DILD). We further demonstrated the predictive power and biological relevance of the DILD network by applying it to identify drugs with relevant pharmacological mechanisms for treating lung injury.

Treatment with intranasal iloprost reduces disease manifestations in a murine model of previously established COPD

Pulmonary endothelial prostacyclin appears to be involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). The effect of treatment with a prostacyclin analog in animal models of previously established COPD is unknown. We evaluated the short- and long-term effect of iloprost on inflammation and airway hyperresponsiveness (AHR) in a murine model of COPD. Nineteen mice were exposed to LPS/elastase, followed by either three doses of intranasal iloprost or saline. In the long-term treatment experiment, 18 mice were exposed to LPS/elastase and then received 6 wk of iloprost or were left untreated as controls. In the short-term experiment, iloprost did not change AHR but significantly reduced serum IL-5 and IFN-γ. Long-term treatment with iloprost for both 2 and 6 wk significantly improved AHR. After 6 wk of iloprost, there was a reduction in bronchoalveolar lavage (BALF) neutrophils, serum IL-1β (30.0 ± 9.2 vs. 64.8 ± 7.4 pg/ml, P = 0.045), IL-2 (36.5 ± 10.6 vs. 83.8 ± 0.4 pg/ml, P = 0.01), IL-10 (75.7 ± 9.3 vs. 96.5 ± 3.5 pg/ml, P = 0.02), and nitrite (15.1 ± 5.4 vs. 30.5 ± 10.7 μmol, P = 0.01). Smooth muscle actin (SMA) in the lung homogenate was also significantly reduced after iloprost treatment (P = 0.02), and SMA thickness was reduced in the small and medium blood vessels after iloprost (P < 0.001). In summary, short- and long-term treatment with intranasal iloprost significantly reduced systemic inflammation in an LPS/elastase COPD model. Long-term iloprost treatment also reduced AHR, serum nitrite, SMA, and BALF neutrophilia. These data encourage future investigations of prostanoid therapy as a novel treatment for COPD patients.

A flavanone from Baccharis retusa (Asteraceae) prevents elastase-induced emphysema in mice by regulating NF-κB, oxidative stress and metalloproteinases

Background

Pulmonary emphysema is characterized by irreversible airflow obstruction, inflammation, oxidative stress imbalance and lung remodeling, resulting in reduced lung function and a lower quality of life. Flavonoids are plant compounds with potential anti-inflammatory and antioxidant effects that have been used in folk medicine. Our aim was to determine whether treatment with sakuranetin, a flavonoid extracted from the aerial parts of Baccharis retusa, interferes with the development of lung emphysema.

Methods

Intranasal saline or elastase was administered to mice; the animals were then treated with sakuranetin or vehicle 2 h later and again on days 7, 14 and 28. We evaluated lung function and the inflammatory profile in bronchoalveolar lavage fluid (BALF). The lungs were removed to evaluate alveolar enlargement, extracellular matrix fibers and the expression of MMP-9, MMP-12, TIMP-1, 8-iso-PGF-2α and p65-NF-κB in the fixed tissues as well as to evaluate cytokine levels and p65-NF-κB protein expression.

Results

In the elastase-treated animals, sakuranetin treatment reduced the alveolar enlargement, collagen and elastic fiber deposition and the number of MMP-9- and MMP-12-positive cells but increased TIMP-1 expression. In addition, sakuranetin treatment decreased the inflammation and the levels of TNF-α, IL-1β and M-CSF in the BALF as well as the levels of NF-κB and 8-iso-PGF-2α in the lungs of the elastase-treated animals. However, this treatment did not affect the changes in lung function.

Conclusion

These data emphasize the importance of oxidative stress and metalloproteinase imbalance in the development of emphysema and suggest that sakuranetin is a potent candidate that should be further investigated as an emphysema treatment. This compound may be useful for counteracting lung remodeling and oxidative stress and thus attenuating the development of emphysema.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-015-0233-3) contains supplementary material, which is available to authorized users.

Proinflammatory Pathways: The Modulation by Flavonoids

Inflammation is a natural, carefully orchestrated response of the organism to tissue damage, involving various signaling systems and the recruitment of inflammatory cells. These cells are stimulated to release a myriad of mediators that amplify the inflammatory response and recruit additional cells. These mediators present numerous redundancies of functions, allowing a broad and effective inflammatory response, but simultaneously make the understanding of inflammation pathways much difficult. The extent of the inflammatory response is usually self-limited, although it depends on the balance between the pro- and anti-inflammatory signals. When that equilibrium is dislocated, a more widespread inflammatory response may take place. Flavonoids have been shown to be possible alternatives to the traditionally molecules used as anti-inflammatory agents. In fact, the biological activities of flavonoids include the modulation of the diverse phases of inflammatory processes, from the gene transcription and expression to the inhibition of the enzymatic activities and the scavenging of the reactive species. In the present review, the inflammatory network is widely revised and the flavonoids' broad spectrum of action in many of the analyzed inflammatory pathways is revised. This kind of integrated revision is original in the field, providing the reader the simultaneous comprehension of the inflammatory process and the potential beneficial activities of flavonoids.

Pulmonary inflammation is regulated by the levels of the vesicular acetylcholine transporter

Acetylcholine (ACh) plays a crucial role in physiological responses of both the central and the peripheral nervous system. Moreover, ACh was described as an anti-inflammatory mediator involved in the suppression of exacerbated innate response and cytokine release in various organs. However, the specific contributions of endogenous release ACh for inflammatory responses in the lung are not well understood. To address this question we have used mice with reduced levels of the vesicular acetylcholine transporter (VAChT), a protein required for ACh storage in secretory vesicles. VAChT deficiency induced airway inflammation with enhanced TNF-α and IL-4 content, but not IL-6, IL-13 and IL-10 quantified by ELISA. Mice with decreased levels of VAChT presented increased collagen and elastic fibers deposition in airway walls which was consistent with an increase in inflammatory cells positive to MMP-9 and TIMP-1 in the lung. In vivo lung function evaluation showed airway hyperresponsiveness to methacholine in mutant mice. The expression of nuclear factor-kappa B (p65-NF-kB) in lung of VAChT-deficient mice were higher than in wild-type mice, whereas a decreased expression of janus-kinase 2 (JAK2) was observed in the lung of mutant animals. Our findings show the first evidence that cholinergic deficiency impaired lung function and produce local inflammation. Our data supports the notion that cholinergic system modulates airway inflammation by modulation of JAK2 and NF-kB pathway. We proposed that intact cholinergic pathway is necessary to maintain the lung homeostasis.

Adaptive cellular stress pathways as therapeutic targets of dietary phytochemicals: focus on the nervous system

During the past 5 decades, it has been widely promulgated that the chemicals in plants that are good for health act as direct scavengers of free radicals. Here we review evidence that favors a different hypothesis for the health benefits of plant consumption, namely, that some phytochemicals exert disease-preventive and therapeutic actions by engaging one or more adaptive cellular response pathways in cells. The evolutionary basis for the latter mechanism is grounded in the fact that plants produce natural antifeedant/noxious chemicals that discourage insects and other organisms from eating them. However, in the amounts typically consumed by humans, the phytochemicals activate one or more conserved adaptive cellular stress response pathways and thereby enhance the ability of cells to resist injury and disease. Examplesof such pathways include those involving the transcription factors nuclear factor erythroid 2-related factor 2, nuclear factor-κB, hypoxia-inducible factor 1α, peroxisome proliferator-activated receptor γ, and forkhead box subgroup O, as well as the production and action of trophic factors and hormones. Translational research to develop interventions that target these pathways may lead to new classes of therapeutic agents that act by stimulating adaptive stress response pathways to bolster endogenous defenses against tissue injury and disease. Because neurons are particularly sensitive to potentially noxious phytochemicals, we focus on the nervous system but also include findings from other cell types in which actions of phytochemicals on specific signal transduction pathways have been more thoroughly studied.

Emerging potential of natural products for targeting mucins for therapy against inflammation and cancer

Deregulated mucin expression is a hallmark of several inflammatory and malignant pathologies. Emerging evidence suggests that, apart from biomarkers, these deregulated mucins are functional contributors to the pathogenesis in inflammation and cancer. Both overexpression and downregulation of mucins in various organ systems is associated with pathobiology of inflammation and cancer. Restoration of mucin homeostasis has become an important goal for therapy and management of such disorders has fueled the quest for selective mucomodulators. With improved understanding of mucin regulation and mechanistic insights into their pathobiological roles, there is optimism to find selective non-toxic agents capable of modulating mucin expression and function. Recently, natural compounds derived from dietary sources have drawn attention due to their anti-inflammatory and anti-oxidant properties and low toxicity. Considerable efforts have been directed towards evaluating dietary natural products as chemopreventive and therapeutic agents; identification, characterization and synthesis of their active compounds; and improving their delivery and bioavailability. We describe the current understanding of mucin regulation, rationale for targeting mucins with natural products and discuss some natural products that modulate mucin expression and functions. We further discuss the approaches and parameters that should guide future research to identify and evaluate selective natural mucomodulators for therapy.

Nanoincorporation of curcumin in polymer-glycerosomes and evaluation of their in vitro–in vivo suitability as pulmonary delivery systems

This work was aimed at deliver curcumin to lungs by its incorporation into innovative vesicles glycerosomes and polymer-glycerosomes, the latter obtained combining glycerosomes with two polymers: sodium hyaluronate and trimethyl chitosan.

Storage Effect on Phenols and on the Antioxidant Activity of Extracts fromAnemopsis californicaand Inhibition of Elastase Enzyme

The amount of total phenols and flavonoids and the antioxidant activity of leaf, stem, and rhizome methanolic extracts from a commonly consumedAnemopsis californicaunder different storage conditions were investigated. Storage conditions were at 50, 25, 4, and −20°C, protected or not from light, during 180 days. The inhibition of the elastase enzyme was also evaluated. The results demonstrated that leaf, stem, and rhizome methanolic extracts ofAnemopsis californicamaintain approximately up to 97 and 95% stability in phenolic content and antioxidant activity, respectively, when stored during 60 days at −20°C in the dark. Additionally, these extracts, principally from leaf and rhizome, showed an elastase inhibitory effect by 75 and 71.8%, respectively. Therefore, this study provides the basis for further research on the anti-inflammatory activity. On the other hand,Anemopsis californicacould comprise a good alternative of use as antioxidant in foods.

Epigenetic targets for novel therapies of lung diseases

In spite of substantial advances in defining the immunobiology and function of structural cells in lung diseases there is still insufficient knowledge to develop fundamentally new classes of drugs to treat many lung diseases. For example, there is a compelling need for new therapeutic approaches to address severe persistent asthma that is insensitive to inhaled corticosteroids. Although the prevalence of steroid-resistant asthma is 5-10%, severe asthmatics require a disproportionate level of health care spending and constitute a majority of fatal asthma episodes. None of the established drug therapies including long-acting beta agonists or inhaled corticosteroids reverse established airway remodeling. Obstructive airways remodeling in patients with chronic obstructive pulmonary disease (COPD), restrictive remodeling in idiopathic pulmonary fibrosis (IPF) and occlusive vascular remodeling in pulmonary hypertension are similarly unresponsive to current drug therapy. Therefore, drugs are needed to achieve long-acting suppression and reversal of pathological airway and vascular remodeling. Novel drug classes are emerging from advances in epigenetics. Novel mechanisms are emerging by which cells adapt to environmental cues, which include changes in DNA methylation, histone modifications and regulation of transcription and translation by noncoding RNAs. In this review we will summarize current epigenetic approaches being applied to preclinical drug development addressing important therapeutic challenges in lung diseases. These challenges are being addressed by advances in lung delivery of oligonucleotides and small molecules that modify the histone code, DNA methylation patterns and miRNA function.

Clinical strategies and animal models for developing senolytic agents

Aging is associated with increasing predisposition to multiple chronic diseases. One fundamental aging process that is often operative at sites of the pathology underlying chronic age-related diseases is cellular senescence. Small molecule senolytic agents are being developed. For successful drug development: 1) appropriate animal models of human age-related diseases need to be devised. 2) Models have to be made in which it can be proven that beneficial phenotypic effects are actually caused through clearing senescent cells by putative senolytic agents, as opposed to "off-target" effects of these agents on non-senescent cells. 3) Models are needed to test efficacy of drugs and to uncover potential side effects of senolytic agents. Development of the optimal animal models and clinical trial paradigms for senolytic agents warrants an intensive effort, since senolytic agents, if successful in delaying, preventing, alleviating, or reversing age-related diseases as a group would be transformative.

Oxidative stress and free radicals in COPD--implications and relevance for treatment

Oxidative stress occurs when free radicals and other reactive species overwhelm the availability of antioxidants. Reactive oxygen species (ROS), reactive nitrogen species, and their counterpart antioxidant agents are essential for physiological signaling and host defense, as well as for the evolution and persistence of inflammation. When their normal steady state is disturbed, imbalances between oxidants and antioxidants may provoke pathological reactions causing a range of nonrespiratory and respiratory diseases, particularly chronic obstructive pulmonary disease (COPD). In the respiratory system, ROS may be either exogenous from more or less inhalative gaseous or particulate agents such as air pollutants, cigarette smoke, ambient high-altitude hypoxia, and some occupational dusts, or endogenously generated in the context of defense mechanisms against such infectious pathogens as bacteria, viruses, or fungi. ROS may also damage body tissues depending on the amount and duration of exposure and may further act as triggers for enzymatically generated ROS released from respiratory, immune, and inflammatory cells. This paper focuses on the general relevance of free radicals for the development and progression of both COPD and pulmonary emphysema as well as novel perspectives on therapeutic options. Unfortunately, current treatment options do not suffice to prevent chronic airway inflammation and are not yet able to substantially alter the course of COPD. Effective therapeutic antioxidant measures are urgently needed to control and mitigate local as well as systemic oxygen bursts in COPD and other respiratory diseases. In addition to current therapeutic prospects and aspects of genomic medicine, trending research topics in COPD are presented.

Role of sirtuins in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation that is associated with chronic inflammatory response to noxious particles or gases. The airflow limitation may be explained by hypersecretion of mucus, thickening and fibrosis of small airways and alveolar wall destruction in emphysema. Sirtuins, a group of class III deacetylases, have gained considerable attention for their positive effects on aging-related disease, such as cancer, cardiovascular disease, neurodegenerative diseases, osteoporosis and COPD. Among the seven mammalian sirtuins, SIRT1-SIRT7, SIRT1 and SIRT6 are considered to have protective effects against COPD. In the lungs, SIRT1 inhibits autophagy, cellular senescence, fibrosis, and inflammation by deacetylation of target proteins using NAD(+) as co-substrate and is therefore linked to the redox state. In addition to SIRT1, SIRT6 have also been shown to improve or slow down COPD. SIRT6 is associated with redox state and inhibits cellular senescence and fibrosis. Therefore, activation of SIRT1 and SIRT6 might be an attractive approach for novel therapeutic targets for COPD. The present review describes the protective effects of SIRT1 and SIRT6 against COPD and their target proteins involved in the pathophysiology of COPD.

Relationships of COX2 and MMP12 genetic polymorphisms with chronic obstructive pulmonary disease risk: a meta-analysis

We performed the present meta-analysis in an attempt to confirm the correlation of genetic polymorphisms in the COX2 and MMP12 genes with the susceptibility to chronic obstructive pulmonary disease (COPD). We searched English database such as PubMed, CISCOM, CINAHL, Web of Science, Google Scholar and several Chinese database for meta-analysis. There were no specific language restrictions. Two investigators systematically extracted relevant data within those included studies. Crude ORs with its corresponding 95 % CI were calculated. STATA 12.0 software was adopted for statistical analysis. The impact of COX2 and MMP12 genetic polymorphisms on the pathogenesis of COPD was investigated in the current study with a total of 10 case-control studies, which includes 1,751 COPD patients and 2,472 healthy subjects. Four common polymorphisms, including rs689466 G > A and rs20417 G > C in the COX2 gene, rs652438 A > G and rs2276109 A > G were evaluated in the MMP12 gene. Pooled OR of the present studies and results showed that the frequency of COX2 rs20417 polymorphism was prevalent in COPD patients than those of healthy subjects (C allele vs. G allele OR = 1.33, 95 % CI 1.06-1.67, P = 0.014; GC + CC vs. GG OR = 1.86, 95 % CI 1.07-3.24, P = 0.029; respectively). However, we found no significant correlation between COX2 rs689466 polymorphism and the risk of COPD (all P > 0.05). Furthermore, our meta-analysis illustrated that individuals with MMP12 rs652438 polymorphism had significantly increased risk of developing COPD (G allele vs. A allele OR = 1.62, 95 % CI 1.08-2.42, P = 0.020; AG + GG vs. AA OR = 2.14, 95 % CI 1.12-4.09, P = 0.021; respectively). Nevertheless, no positive relation was detected between MMP12 rs2276109 variant and the risk of COPD. Our meta-analysis indicates that COX2 and MMP12 genetic polymorphisms may be strongly implicated in the development of COPD, especially for the COX2 rs20417 and MMP12 rs652438 polymorphisms. Thus, COX2 and MMP12 genetic polymorphisms could potentially be utilized as helpful biomarkers for early diagnosis of COPD.

Macrophage metalloelastase (MMP12) regulates adipose tissue expansion, insulin sensitivity, and expression of inducible nitric oxide synthase

Macrophage metalloelastase, a matrix metallopeptidase (MMP12) predominantly expressed by mature tissue macrophages, is implicated in pathological processes. However, physiological functions for MMP12 have not been described. Because mRNA levels for the enzyme increase markedly in adipose tissue of obese mice, we investigated the role of MMP12 in adipose tissue expansion and insulin resistance. In humans, MMP12 expression correlated positively and significantly with insulin resistance, TNF-α expression, and the number of CD14(+)CD206(+) macrophages in adipose tissue. MMP12 was the most abundant matrix metallopeptidase detected by proteomic analysis of conditioned medium of M2 macrophages and dendritic cells. In contrast, it was detected only at low levels in bone marrow derived macrophages and M1 macrophages. When mice received a high-fat diet, adipose tissue mass increased and CD11b(+)F4/80(+)CD11c(-) macrophages accumulated to a greater extent in MMP12-deficient (Mmp12(-/-)) mice than in wild-type mice (Mmp12(+/+)). Despite being markedly more obese, fat-fed Mmp12(-/-) mice were more insulin sensitive than fat-fed Mmp12(+/+) mice. Expression of inducible nitric oxide synthase (Nos2) by Mmp12(-/-) macrophages was significantly impaired both in vivo and in vitro, suggesting that MMP12 might mediate nitric oxide production during inflammation. We propose that MMP12 acts as a double-edged sword by promoting insulin resistance while combatting adipose tissue expansion.

Structure-activity association of flavonoids in lung diseases

Flavonoids are polyphenolic compounds classified into flavonols, flavones, flavanones, isoflavones, catechins, anthocyanidins, and chalcones according to their chemical structures. They are abundantly found in Nature and over 8,000 flavonoids have from different sources, mainly plant materials, have been described. Recently reports have shown the valuable effects of flavonoids as antiviral, anti-allergic, antiplatelet, antitumor, antioxidant, and anti-inflammatory agents and interest in these compounds has been increasing since they can be helpful to human health. Several mechanisms of action are involved in the biological properties of flavonoids such as free radical scavenging, transition metal ion chelation, activation of survival genes and signaling pathways, regulation of mitochondrial function and modulation of inflammatory responses. The anti-inflammatory effects of flavonoids have been described in a number of studies in the literature, but not frequently associated to respiratory disease. Thus, this review aims to discuss the effects of different flavonoids in the control of lung inflammation in some disorders such as asthma, lung emphysema and acute respiratory distress syndrome and the possible mechanisms of action, as well as establish some structure-activity relationships between this biological potential and chemical profile of these compounds.

You are what you eat, and so are your children: the impact of micronutrients on the epigenetic programming of offspring

The research field of fetal programming has developed tremendously over the years and increasing knowledge suggests that both maternal and paternal unbalanced diet can have long-lasting effects on the health of offspring. Studies implicate that macronutrients play an important role in fetal programming, although the importance of micronutrients is also becoming increasingly apparent. Folic acid and vitamins B2, B6 and B12 are essential for one-carbon metabolism and are involved in DNA methylation. They can therefore influence the programming of the offspring's epigenome. Also, other micronutrients such as vitamins A and C, iron, chromium, zinc and flavonoids play a role in fetal programming. Since it is estimated that approximately 78 % of pregnant women in the US take vitamin supplements during pregnancy, more attention should be given to the long-term effects of these supplements on offspring. In this review we address several different studies which illustrate that an unbalanced diet prior and during pregnancy, regarding the intake of micronutrients of both mother and father, can have long-lasting effects on the health of adult offspring.

Inhibition of Experimental Systemic Inflammation (Septic Inflammation) and Chronic Bronchitis by New Phytoformula BL Containing Broussonetia papyrifera and Lonicera japonica

Broussonetia papyrifera and Lonicera japonica have long been used in the treatment of inflammatory disorders in Chinese medicine, especially respiratory inflammation. Previously, a new phytoformula (BL) containing B. papyrifera and L. japonica was found to exert strong anti-inflammatory activity against several animal models of inflammation, especially against an animal model of acute bronchitis. In the present investigation, the effects of BL on animal models of septic inflammation and chronic bronchitis are examined. Against lipopolysaccharide (LPS)-induced septic inflammation in mice, BL (200-400 mg/kg) reduced the induction of some important proinflammatory cytokines. At 1 h after LPS treatment, BL was found to considerably inhibit TNF-α production when measured by cytokine array. At 3 h after LPS treatment, BL inhibited the induction of several proinflammatory cytokines, including IFN-γ and IL-1β, although dexamethasone, which was used as a reference, showed a higher inhibitory action on these biomarkers. Against chronic bronchitis induced by LPS/elastase instillation in rats for 4 weeks, BL (200-400 mg/kg/day) significantly inhibited cell recruitment in bronchoalveolar lavage fluid. Furthermore, BL considerably reduced lung injury, as revealed by histological observation. Taken together, these results indicate that BL may have a potential to treat systemic septic inflammation as well as chronic bronchitis.

Simultaneous inactivation of GSK-3β suppresses quercetin-induced apoptosis by inhibiting the JNK pathway

Quercetin, a ubiquitous bioactive plant flavonoid, has shown to exert a broad range of activities, such as apoptotic, antioxidant, and anti-inflammatory effects. Thus, flavonoids can mediate both cell protection and cell injury. Recently, quercetin has been reported to prevent the progression of emphysema in animal models through antioxidant and anti-inflammatory actions. These findings suggest that quercetin could be a potential treatment option for chronic obstructive pulmonary disease. Its clinical application, however, could be limited by the cytotoxicity of quercetin, and understanding of the apoptotic mechanisms of quercetin is a prerequisite to develop a therapeutic strategy with minimal cytotoxicity. We evaluated the apoptotic effect of quercetin and its molecular mechanisms in normal bronchial epithelial cells (BEAS-2B cells). Quercetin decreased the viability of BEAS-2B cells via apoptosis in a dose- and time-dependent manner. Quercetin activated JNK and increased the expression levels of c-Jun and p53-dependent Bax. Blockade of JNK activation by overexpression of dominant negative JNK1 suppressed apoptosis by quercetin via inhibition of caspase-3 activation and reduction of p53 and Bax expression. Simultaneously, quercetin inactivated glycogen synthase kinase (GSK)-3β, which is phosphatidylinositol 3-kinase/Akt dependent. Overexpression of a constitutively active GSK-3β mutant enhanced quercetin-induced JNK activation. In contrast, overexpression of enzymatically inert GSK-3β inhibited JNK activation, resulting in a suppression of apoptosis by quercetin. Taken together, the JNK-p53 pathway is involved in quercetin-induced apoptosis, and simultaneous inactivation of GSK-3β can attenuate apoptosis in normal bronchial epithelial cells.

Quercetin: a flavonoid with the potential to treat asthma

Allergic asthma is a complex inflammatory disorder characterized by airway hyperresponsiveness, eosinophilic inflammation and hypersecretion of mucus. Current therapies include β2-agonists, cysteinyl leukotriene receptor 1 antagonists and corticosteroids. Although these drugs demonstrate beneficial effects, their adverse side effects limit their long-term use. Thus, the development of new compounds with similar therapeutic activities and reduced side effects is both desirable and necessary. Natural compounds are used in some current therapies, as plant-derived metabolites can relieve disease symptoms in the same manner as allopathic medicines. Quercetin is a flavonoid that is naturally found in many fruits and vegetables and has been shown to exert multiple biological effects in experimental models, including the reduction of major symptoms of asthma: bronchial hyperactivity, mucus production and airway inflammation. In this review, we discuss results from the literature that illustrate the potential of quercetin to treat asthma and its exacerbations.

Aberrantly activated EGFR contributes to enhanced IL-8 expression in COPD airways epithelial cells via regulation of nuclear FoxO3A

BACKGROUND

Decreased activity of forkhead transcription factor class O (FoxO)3A, a negative regulator of NF-κB-mediated chemokine expression, is implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). Previously, we showed that quercetin reduces lung inflammation in a murine model of COPD. Here, we examined the mechanisms underlying decreased FoxO3A activation and its modulation by quercetin in COPD human airway epithelial cells and in a COPD mouse model.

METHODS

Primary COPD and normal human airway epithelial cells were treated with quercetin, LY294002 or erlotinib for 2 weeks. IL-8 was measured by ELISA. FoxO3A, Akt, and epidermal growth factor (EGF) receptor (EGFR) phosphorylation and nuclear FoxO3A levels were determined by Western blot analysis. Effects of quercetin on lung chemokine expression, nuclear FoxO3A levels and phosphorylation of EGFR and Akt were determined in COPD mouse model.

RESULTS

Compared with normal, COPD cells showed significantly increased IL-8, which negatively correlated with nuclear FoxO3A levels. COPD bronchial biopsies also showed reduced nuclear FoxO3A. Decreased FoxO3A in COPD cells was associated with increased phosphorylation of EGFR, Akt and FoxO3A and treatment with quercetin, LY294002 or erlotinib increased nuclear FoxO3A and decreased IL-8 and phosphorylation of Akt, EGFR and FoxO3A, Compared with control, elastase/LPS-exposed mice showed decreased nuclear FoxO3A, increased chemokines and phosphorylation of EGFR and Akt. Treatment with quercetin partially reversed these changes.

CONCLUSIONS

In COPD airways, aberrant EGFR activity increases PI 3-kinase/Akt-mediated phosphorylation of FoxO3A, thereby decreasing nuclear FoxO3A and increasing chemokine expression. Quercetin restores nuclear FoxO3A and reduces chemokine expression partly by modulating EGFR/PI 3-kinase/Akt activity.

Rhinovirus attenuates non-typeable Hemophilus influenzae-stimulated IL-8 responses via TLR2-dependent degradation of IRAK-1

Bacterial infections following rhinovirus (RV), a common cold virus, are well documented, but pathogenic mechanisms are poorly understood. We developed animal and cell culture models to examine the effects of RV on subsequent infection with non-typeable Hemophilus influenzae (NTHi). We focused on NTHI-induced neutrophil chemoattractants expression that is essential for bacterial clearance. Mice infected with RV1B were superinfected with NTHi and lung bacterial density, chemokines and neutrophil counts determined. Human bronchial epithelial cells (BEAS-2B) or mouse alveolar macrophages (MH-S) were infected with RV and challenged with NHTi, TLR2 or TLR5 agonists. Chemokine levels were measured by ELISA and expression of IRAK-1, a component of MyD88-dependent TLR signaling, assessed by immunoblotting. While sham-infected mice cleared all NTHi from the lungs, RV-infected mice showed bacteria up to 72 h post-infection. However, animals in RV/NTHi cleared bacteria by day 7. Delayed bacterial clearance in RV/NTHi animals was associated with suppressed chemokine levels and neutrophil recruitment. RV-infected BEAS-2B and MH-S cells showed attenuated chemokine production after challenge with either NTHi or TLR agonists. Attenuated chemokine responses were associated with IRAK-1 protein degradation. Inhibition of RV-induced IRAK-1 degradation restored NTHi-stimulated IL-8 expression. Knockdown of TLR2, but not other MyD88-dependent TLRs, also restored IRAK-1, suggesting that TLR2 is required for RV-induced IRAK-1 degradation.

In conclusion, we demonstrate for the first time that RV infection delays bacterial clearance in vivo and suppresses NTHi-stimulated chemokine responses via degradation of IRAK-1. Based on these observations, we speculate that modulation of TLR-dependent innate immune responses by RV may predispose the host to secondary bacterial infection, particularly in patients with underlying chronic respiratory disorders.

Rhinovirus (RV) is responsible for the majority of common colds. RV infection is also associated with hospitalizations for lower respiratory tract illness, a significant proportion of which are accompanied by bacterial infections including acute otitis media, sinusitis and pneumonia. However, the mechanisms by which RV increases susceptibility to secondary bacterial infections are not understood. In this report, we demonstrate for the first time that RV infection promotes bacterial persistence of non-typeable Hemophilus influenzae (NTHi) in vivo, which was associated with reduced expression of neutrophil-attracting chemokines and neutrophil infiltration into the lungs. Further, RV infection attenuated NTHi or TLR2 or −5 agonist-stimulated chemokine responses in cultured bronchial epithelial cells and alveolar macrophages, suggesting that RV interferes with TLR-related innate immune responses. Next, we found that RV infection caused rapid degradation of IRAK-1, a key adaptor protein in the MyD88-dependent signaling. Inhibition of IRAK-1 degradation restored NTHi-stimulated chemokine responses in RV-infected bronchial epithelial cells. Finally, reductions in IRAK-1 were dependent on TLR2. Together, our results suggest that RV may increase the risk of acquiring secondary bacterial infection by attenuating TLR-dependent innate immune responses.

Cytoprotective and anti-inflammatory effects of melatonin in hydrogen peroxide-stimulated CHON-001 human chondrocyte cell line and rabbit model of osteoarthritis via the SIRT1 pathway

Melatonin has potent antioxidant, analgesic, and antinociceptive properties. However, the effects of melatonin against oxidative stress-induced cytotoxicity and inflammatory mediators in human chondrocytes remain poorly understood. This study examined the effects and underlying mechanism of melatonin in hydrogen peroxide (H(2) O(2) )-stimulated human chondrocytes and rabbit osteoarthritis (OA) model. Melatonin markedly inhibited hydrogen peroxide (H(2) O(2) )-stimulated cytotoxicity, iNOS, and COX-2 protein and mRNA expression, as well as the downstream products, NO and PGE(2) . Incubation of cells with melatonin decreased H(2) O(2) -induced Sirtuin 1 (SIRT1) mRNA and protein expression. SIRT1 inhibition by sirtinol or Sirt1 siRNA reversed the effects of melatonin on H(2) O(2) -mediated induction of pro-inflammatory cytokines (NO, PGE(2) , TNF-α, IL-1β, and IL-8) and the expression of iNOS, COX-2, and cartilage destruction molecules. Melatonin blocked H(2) O(2) -induced phosphorylation of PI3K/Akt, p38, ERK, JNK, and MAPK, as well as activation of NF-κB, which was reversed by sirtinol and SIRT1 siRNA. In rabbit with OA, intra-articular injection of melatonin significantly reduced cartilage degradation, which was reversed by sirtinol. Taken together, this study shows that melatonin exerts cytoprotective and anti-inflammatory effects in an oxidative stress-stimulated chondrocyte model and rabbit OA model, and that the SIRT1 pathway is strongly involved in this effect.

Epigenetics in asthma and COPD

Epigenetic mechanisms are likely to play a role in many complex diseases, the extent of which we only beginning to understand. COPD and asthma are two respiratory diseases subject to strong environmental influences depending on underlying genetic susceptibility. Epigenetic mechanisms such as DNA methylation, histone modification and microRNA may be involved in these processes by modulating environmental effects to influence disease development. Given their demonstrated modifiable nature, epigenetic mechanisms may open new possibilities for therapeutic intervention. Here we give an overview of recent developments in the field of respiratory epigenetics in relation to asthma and COPD in the context of our current understanding of mechanisms leading to such diseases.

Perspectives on translational and therapeutic aspects of SIRT1 in inflammaging and senescence

Sirtuin1 (SIRT1), a type III protein deacetylase, is considered as a novel anti-aging protein involved in regulation of cellular senescence/aging and inflammation. SIRT1 level and activity are decreased during lung inflammaging caused by oxidative stress. The mechanism of SIRT1-mediated protection against inflammaging is associated with the regulation of inflammation, premature senescence, telomere attrition, senescence associated secretory phenotype, and DNA damage response. A variety of dietary polyphenols and pharmacological activators are shown to regulate SIRT1 so as to intervene the progression of type 2 diabetes, cancer, cardiovascular diseases, and chronic obstructive pulmonary disease associated with inflammaging. However, recent studies have shown the non-specific regulation of SIRT1 by the aforementioned pharmacological activators and polyphenols. In this perspective, we have briefly discussed the role of SIRT1 in regulation of cellular senescence and its associated secretory phenotype, DNA damage response, particularly in lung inflammaging and during the development of chronic obstructive pulmonary diseases. We have also discussed the potential directions for future translational therapeutic avenues for SIRT1 in modulating lung inflammaging associated with senescence in chronic lung diseases associated with increased oxidative stress.

Quercetin, a flavonoid with anti-inflammatory activity, suppresses the development of abdominal aortic aneurysms in mice

Inflammation has been implicated as a contributing factor in the development of abdominal aortic aneurysms (AAA). Quercetin, a natural flavonoid with anti-inflammatory properties, is known for its beneficial effects on vascular disease. In this study, we examined the effects of quercetin to inflammatory cell infiltration, subsequent expression of cytokines and activation of proteases on the expansion of experimental AAA. Aneurysms were induced by abluminal application of calcium chloride in C57/BL6 mice. Quercetin (60 mg/kg) was administered once daily by gavage beginning 2 weeks before AAA induction and continuing for 8 weeks. Mice treated with quercetin exhibited a 32.7% reduction in aortic size compared with vehicle-treated controls. Prevention of AAA was associated with preservation of medial structure, as well as a relative reduction in macrophage and CD3(+) T cell infiltration in aortic tissue, inflammatory cytokines release and nuclear factor κB activation. Quercetin also reduced the expression of matrix metalloproteinase (MMP)-2, MMP-9, cathepsin B, and cathepsin K in aortic tissue. In addition, quercetin treatment increased tissue inhibitors of metalloproteinases (TIMP)-1 gene expression. These data indicate that quercetin may be useful for the prevention and treatment of AAA via blocking the inflammatory response and inhibiting the proteases involved in the pathogenesis of this disease.

Quercetin attenuates airway inflammation and mucus production induced by cigarette smoke in rats

Mucus hypersecretion is a feature of many chronic airway diseases induced by cigarette smoke (CS), and evidence suggests that the antioxidant and anti-inflammatory flavonoid quercetin may protect against CS-induced respiratory pathology. In this study, the ability of quercetin to protect against CS-induced mucin expression was examined in vivo and in vitro. Quercetin or 0.2% Tween aqueous solution was administered intraperitoneally to rats,which were then exposed to CS for 28 days. Cell counts and pro-inflammatory cytokine levels were measured in bronchoalveolar lavage fluid (BALF). Lung tissue was examined for total glutathione (GSH) and total antioxidant capacity (T-AOC), histopathological lesions, goblet cell hyperplasia, epidermal growth factor receptor (EGFR) phosphorylation and NF-κB pathway activation. To complement these in vitro studies, human airway epithelial NCI-H292 cells were pretreated with quercetin and then exposed to cigarette smoke extract (CSE). Cell lysates were examined for Muc5ac expression, EGFR phosphorylation and NF-κB pathway activation. In vivo, quercetin pretreatment suppressed CS-induced goblet cell hyperplasia, inflammation, oxidative stress, EGFR phosphorylation and NF-κB pathway activation in rat lung. In vitro, quercetin pretreatment attenuated the CSE-induced Muc5ac expression, NF-κB activation and EGFR phosphorylation. Our results suggest that quercetin attenuates CS-induced mucin protein synthesis in rat lung, possibly by inhibiting oxidative stress and inflammation via a mechanism involving NF-κB pathway activation and EGFR phosphorylation. These findings suggest that quercetin has a potential for treating chronic airway diseases.

Quercetin inhibits rhinovirus replication in vitro and in vivo

Rhinovirus (RV), which is responsible for the majority of common colds, also causes exacerbations in patients with asthma and chronic obstructive pulmonary disease. So far, there are no drugs available for treatment of rhinovirus infection. We examined the effect of quercetin, a plant flavanol on RV infection in vitro and in vivo. Pretreatment of airway epithelial cells with quercetin decreased Akt phosphosphorylation, viral endocytosis and IL-8 responses. Addition of quercetin 6 h after RV infection (after viral endocytosis) reduced viral load, IL-8 and IFN responses in airway epithelial cells. This was associated with decreased levels of negative and positive strand viral RNA, and RV capsid protein, abrogation of RV-induced eIF4GI cleavage and increased phosphorylation of eIF2α. In mice infected with RV, quercetin treatment decreased viral replication as well as expression of chemokines and cytokines. Quercetin treatment also attenuated RV-induced airway cholinergic hyperresponsiveness. Together, our results suggest that quercetin inhibits RV endocytosis and replication in airway epithelial cells at multiple stages of the RV life cycle. Quercetin also decreases expression of pro-inflammatory cytokines and improves lung function in RV-infected mice. Based on these observations, further studies examining the potential benefits of quercetin in the prevention and treatment of RV infection are warranted.

Homocysteine enhances MMP-9 production in murine macrophages via ERK and Akt signaling pathways

Homocysteine (Hcy) at elevated levels is an independent risk factor of cardiovascular diseases, including atherosclerosis. In the present study, we investigated the effect of Hcy on the production of matrix metalloproteinases (MMP) in murine macrophages. Among the MMP known to regulate the activities of collagenase and gelatinase, Hcy exclusively increased the gelatinolytic activity of MMP-9 in J774A.1 cells as well as in mouse peritoneal macrophages. Furthermore, this activity was found to be correlated with Western blot findings in J774A.1 cells, which showed that MMP-9 expression was concentration- and time-dependently increased by Hcy. Inhibition of the ERK and Akt pathways led to a significant decrease in Hcy-induced MMP-9 expression, and combined treatment with inhibitors of the ERK and Akt pathways showed an additive effects. Activity assays for ERK and Akt showed that Hcy increased the phosphorylation of both, but these phosphorylation were not affected by inhibitors of the Akt and ERK pathways. In line with these findings, the molecular inhibition of ERK and Akt using siRNA did not affect the Hcy-induced phosphorylation of Akt and ERK, respectively. Taken together, these findings suggest that Hcy enhances MMP-9 production in murine macrophages by separately activating the ERK and Akt signaling pathways.

Elastase/LPS-exposed mice exhibit impaired innate immune responses to bacterial challenge: role of scavenger receptor A

Nontypeable Haemophilus influenzae (NTHi) is an important bacterial pathogen associated with lower respiratory tract colonization and with acute exacerbations and disease progression in chronic obstructive pulmonary disease (COPD). Why the immune system fails to eliminate NTHi and the exact contribution of the organism to COPD progression are not well understood, in part because we lack an animal model that mimics all aspects of COPD. For this study, we used an established murine model that exhibits typical features of COPD. Elastase/LPS-exposed mice infected with NTHi showed persistence of bacteria up to 5 days after infection, whereas mice exposed to elastase, LPS, or PBS cleared all bacteria by 3 days. Elastase/LPS-exposed mice also showed sustained lung neutrophilic inflammation, goblet cell metaplasia, airway hyperresponsiveness, and progression of emphysema at 15 days after infection. Alveolar macrophages isolated from elastase/LPS-exposed mice showed impaired bacterial phagocytosis, reduced expression of MARCO and of mannose receptor, and absent expression of scavenger receptor-A (SR-A). Neutralization of SR-A significantly decreased phagocytosis of NTHi by normal alveolar macrophages. Our results suggest that elastase/LPS-exposed mice show impaired bacterial clearance and sustained lung inflammation. Lack of SR-A expression may, in part, be responsible for impaired phagocytosis of bacteria by alveolar macrophages of elastase/LPS-exposed mice. These data validate the suitability of elastase/LPS model for investigating NTHi pathogenesis and progression of disease in COPD.

Rhinovirus-induced barrier dysfunction in polarized airway epithelial cells is mediated by NADPH oxidase 1

Previously, we showed that rhinovirus (RV), which is responsible for the majority of common colds, disrupts airway epithelial barrier function, as evidenced by reduced transepithelial resistance (R(T)), dissociation of zona occludins 1 (ZO-1) from the tight junction complex, and bacterial transmigration across polarized cells. We also showed that RV replication is required for barrier function disruption. However, the underlying biochemical mechanisms are not known. In the present study, we found that a double-stranded RNA (dsRNA) mimetic, poly(I:C), induced tight junction breakdown and facilitated bacterial transmigration across polarized airway epithelial cells, similar to the case with RV. We also found that RV and poly(I:C) each stimulated Rac1 activation, reactive oxygen species (ROS) generation, and Rac1-dependent NADPH oxidase 1 (NOX1) activity. Inhibitors of Rac1 (NSC23766), NOX (diphenylene iodonium), and NOX1 (small interfering RNA [siRNA]) each blocked the disruptive effects of RV and poly(I:C) on R(T), as well as the dissociation of ZO-1 and occludin from the tight junction complex. Finally, we found that Toll-like receptor 3 (TLR3) is not required for either poly(I:C)- or RV-induced reductions in R(T). Based on these results, we concluded that Rac1-dependent NOX1 activity is required for RV- or poly(I:C)-induced ROS generation, which in turn disrupts the barrier function of polarized airway epithelia. Furthermore, these data suggest that dsRNA generated during RV replication is sufficient to disrupt barrier function.