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Biomedical subjects

Peter J Barnes

Publications and source records attributed to Peter J Barnes.

At least 73 records · Page 4Linked to original sources
PubMed2005

Glycopyrrolate causes prolonged bronchoprotection and bronchodilatation in patients with asthma.

INTRODUCTION: Inhaled anticholinergic drugs are effective bronchodilators in the treatment of COPD, and tiotropium bromide has recently been introduced as a once-daily bronchodilator for use as a maintenance treatment. Racemic glycopyrrolate is an anticholinergic drug that has been used orally to control gastric acidity, parenterally as an antisialogogue and to reverse neuromuscular blockade, and has been studied by inhalation for asthma and COPD. DESIGN AND OBJECTIVE: We investigated the duration of protection against the constrictor effects of inhaled methacholine of a single dose of inhaled nebulized racemic glycopyrrolate (0.5, 1.0, and 2.0 mg) compared with ipratropium bromide (0.5 mg) and placebo in 10 atopic asthmatic volunteers in a double-blind, five-way, crossover study. RESULTS: Protection against methacholine-induced bronchospasm after administering glycopyrrolate was maintained to 30 h, the last time point measured. Both bronchodilatation and bronchoprotection were significantly longer with glycopyrrolate than after ipratropium bromide, and bronchoprotection was significant at all time points from 2 to 30 h compared to placebo. Dryness of the mouth and nose was described in 18% of patients after the highest dose of glycopyrrolate. CONCLUSIONS: The prolonged bronchodilator response and the protection against methacholine-induced bronchospasm demonstrated in asthma suggests that inhaled racemic glycopyrrolate would be superior to ipratropium bromide for treatment of stable COPD.

Asthma↗
PubMed2005

Theophylline in chronic obstructive pulmonary disease: new horizons.

Although theophylline has side effects when used in bronchodilator doses, increasing evidence shows that it has significant antiinflammatory effects in chronic obstructive pulmonary disease at lower plasma concentrations. These antiinflammatory effects are unlikely to be accounted for by phosphodiesterase inhibition or adenosine receptor antagonism, which require higher concentrations. There is now evidence that theophylline at low therapeutic concentrations is an activator of histone deacetylases and that this activation enhances the antiinflammatory effect of corticosteroids. There appears to be a marked reduction in histone deacetylase-2 in macrophages and peripheral lung of patients with chronic obstructive pulmonary disease, which accounts for amplified inflammation and steroid resistance. Theophylline has been shown to restore steroid sensitivity in vitro. The effect of theophylline on histone deacetylase activity appears to be enhanced by oxidative stress. The mechanism whereby theophylline activates histone deacetylase is not yet known, but it does not involve other known actions of theophylline that account for its side effects. Better understanding of the molecular basis for the action of theophylline might lead to the development of novel drugs.

Adrenal Cortex Hormones↗
PubMed2005

Targeting histone deacetylase 2 in chronic obstructive pulmonary disease treatment.

There is increasing evidence that histone acetylation plays a critical role in the regulation of inflammatory genes and in mediating the anti-inflammatory effects of corticosteroids. Inflammatory stimuli through transcription factors, such as NF-kappaB, recruit co-activator molecules with intrinsic histone acetyltransferase activity, leading to hyperacetylation of core histones and gene activation. Histone deacetylases (HDACs) reverse this process and suppress inflammatory genes. Corticosteroids, the most effective anti-inflammatory drugs so far available, recruit HDAC2 to activated inflammatory gene complexes through an interaction with glucocorticoid receptor and thus switch off activated inflammatory genes. In chronic obstructive pulmonary disease and in asthmatic patients who smoke, there is a reduction in HDAC2 activity and expression, resulting in amplification of inflammation and corticosteroid resistance. Therapeutic strategies to increase HDAC activity may, therefore, be expected to reduce inflammation and restore steroid responsiveness. These strategies include low doses of theophylline or antioxidants and nitric oxide synthase inhibitors. HDACs may be inhibited directly by siRNA and in the future by small-molecule activators may be discovered through high output screening. These drugs may represent a novel approach to treating chronic inflammatory diseases.

Adrenal Cortex Hormones↗
PubMed2004

The role of anticholinergics in chronic obstructive pulmonary disease.

Anticholinergics are the bronchodilators of choice in the management of chronic obstructive pulmonary disease (COPD). They work by blocking muscarinic receptors in airway smooth muscle. Cholinergic tone appears to be the only reversible component of COPD. With the discovery of different muscarinic receptor subtypes, the development of more selective anticholinergics is possible. A major advance in this therapeutic area has been the discovery of tiotropium bromide, which has kinetic selectivity for M3 receptors as well as a duration of action of >24 hours. Once-daily administration of tiotropium is well tolerated and has shown significant advantages over ipratropium bromide, given 4 times daily, in the control of COPD.

Bronchodilator Agents↗
PubMed2004

Theobromine inhibits sensory nerve activation and cough.

Cough is a common and protective reflex, but persistent coughing is debilitating and impairs quality of life. Antitussive treatment using opioids is limited by unacceptable side effects, and there is a great need for more effective remedies. The present study demonstrates that theobromine, a methylxanthine derivative present in cocoa, effectively inhibits citric acid-induced cough in guinea-pigs in vivo. Furthermore, in a randomized, double-blind, placebo-controlled study in man, theobromine suppresses capsaicin-induced cough with no adverse effects. We also demonstrate that theobromine directly inhibits capsaicin-induced sensory nerve depolarization of guinea-pig and human vagus nerve suggestive of an inhibitory effect on afferent nerve activation. These data indicate the actions of theobromine appear to be peripherally mediated. We conclude theobromine is a novel and promising treatment, which may form the basis for a new class of antitussive drugs.

Adult↗
PubMed2004

Add-on therapy options in asthma not adequately controlled by inhaled corticosteroids: a comprehensive review.

Many patients with persistent asthma can be controlled with inhaled corticosteroids (ICS). However, a considerable proportion of patients remain symptomatic, despite the use of ICS. We present systematically evidence that supports the different treatment options. A literature search was made of Medline/PubMed to identify randomised and blinded trials. To demonstrate the benefit that can be obtained by increasing the dose of ICS, dose-response studies with at least three different ICS doses were identified. To demonstrate whether more benefit can be obtained by adding long-acting beta2-agonist (LABA), leukotriene antagonist (LTRA) or theophylline than by increasing the dose of ICS, studies comparing these options were identified. Thirdly, studies comparing the different "add-on" options were identified. The addition of a LABA is more effective than increasing the dose of ICS in improving asthma control. By increasing the dose of ICS, clinical improvement is likely to be of small magnitude. Addition of a LTRA or theophylline to the treatment regimen appears to be equivalent to doubling the dose of ICS. Addition of a LABA seems to be superior to an LTRA in improving lung function. However, addition of LABA and LTRA may be equal with respect to asthma exacerbations. However, more and longer studies are needed to better clarify the role of LTRAs and theophylline as add-on therapies.

Administration, Inhalation↗
PubMed2004

Discovery of BRL 50481 [3-(N,N-dimethylsulfonamido)-4-methyl-nitrobenzene], a selective inhibitor of phosphodiesterase 7: in vitro studies in human monocytes, lung macrophages, and CD8+ T-lymphocytes.

The biochemical and pharmacological characteristics in human proinflammatory cells of BRL 50481 [3-(N,N-dimethylsulfonamido)-4-methyl-nitrobenzene], a novel and selective inhibitor of phosphodiesterase (PDE) 7, are described. BRL 50481 inhibited the activity of hrPDE7A1 expressed in baculovirus-infected Spodoptera frugiperda 9 cells in a competitive manner (Ki value of 180 nM) and was 416 and 1884 times less potent against PDE3 and 38 and 238 times less potent against PDE4 at a substrate concentration of 1 microM and 50 nM cAMP, respectively. Western blotting identified HSPDE7A1 but not HSPDE7A2 in three human cell types that are implicated in the pathogenesis of chronic obstructive lung disease, namely, CD8+ T-lymphocytes, monocytes, and lung macrophages. BRL 50481 had no effect on the proliferation of CD8+ T-lymphocytes and only marginally (approximately 2-11%) reduced the generation of tumor necrosis factor (TNF)alpha from blood monocytes and lung macrophages. However, in the presence of BRL 50481 the inhibitory effect of rolipram was enhanced on all three cell types. The expression of HSPDE7A1 was increased in a time-dependent manner in monocytes that were "aged" in culture medium. Under this condition, BRL 50481 now inhibited TNFalpha generation in a concentration-dependent manner. In aged monocytes, rolipram, Org 9935 (a PDE3 inhibitor), and prostaglandin E2 inhibited TNFalpha generation in a concentration-dependent manner and interacted additively with BRL 50481. BRL 50481 is the first fully documented PDE7 inhibitor that has acceptable selectivity for in vitro studies. Furthermore, although BRL 50481 had only a modest inhibitory effect per se on the proinflammatory cells studied, it acted at least additively with other cAMP-elevating drugs, especially when HSPDE7A1 was up-regulated.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2004

Theophylline restores histone deacetylase activity and steroid responses in COPD macrophages.

Chronic obstructive pulmonary disease (COPD) is a common chronic inflammatory disease of the lungs with little or no response to glucocorticoids and a high level of oxidative stress. Histone deacetylase (HDAC) activity is reduced in cells of cigarette smokers, and low concentrations of theophylline can increase HDAC activity. We measured the effect of theophylline on HDAC activity and inflammatory gene expression in alveolar macrophages (AM) from patients with COPD. AM from normal smokers showed a decrease in HDAC activity compared with normal control subjects, and this was further reduced in COPD patients (51% decrease, P < 0.01). COPD AMs also showed increased basal release of IL-8 and TNF-alpha, which was poorly suppressed by dexamethasone. Theophylline induced a sixfold increase in HDAC activity in COPD AM lysates and significantly enhanced dexamethasone suppression of induced IL-8 release, an effect that was blocked by the HDAC inhibitor trichostatin A. Therefore, theophylline might restore steroid responsiveness in COPD patients.

Aged↗
PubMed2004

Anti-inflammatory effects of resveratrol in lung epithelial cells: molecular mechanisms.

Resveratrol (3,4',5-trihydroxystilbene) is a polyphenolic stilbene found in the skins of red fruits, including grapes, that may be responsible for some of the health benefits ascribed to consumption of red wine. Resveratrol has been shown to have antioxidant properties and can act as an estrogen agonist. This study examined the anti-inflammatory effects of resveratrol on human airway epithelial cells. Resveratrol and the related molecule quercetin, but not deoxyrhapontin, inhibited IL-8 and granulocyte-macrophage colony-stimulating factor release from A549 cells. Neither the estrogen receptor antagonist tamoxifen nor the glucocorticoid antagonist mifepristone altered the inhibitory effect of resveratrol. The mechanism of resveratrol action was investigated further using luciferase reporter genes stably transfected into A549 cells. Resveratrol and quercetin inhibited NF-kappaB-, activator protein-1-, and cAMP response element binding protein-dependent transcription to a greater extent than the glucocorticosteroid dexamethasone. These compounds also had no significant effect on acetylation or deacetylation of core histones. Resveratrol, but not estradiol or N-acetyl cysteine, inhibited cytokine-stimulated inducible nitric oxide synthase expression and nitrite production (IC50 = 3.6 +/- 2.9 microM) in human primary airway epithelial cells. Resveratrol also inhibited granulocyte-macrophage colony-stimulating factor release (IC50 = 0.44 +/- 0.17 microM), IL-8 release (IC50 = 4.7 +/- 3.3 microM), and cyclooxygenase-2 expression in these cells. This study demonstrates that resveratrol and quercetin have novel nonsteroidal anti-inflammatory activity that may have applications for the treatment of inflammatory diseases.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2004

Specific CXC but not CC chemokines cause elevated monocyte migration in COPD: a role for CXCR2.

Leukocyte migration is critical to maintaining host defense, but uncontrolled cellular infiltration into tissues can lead to chronic inflammation. In the lung, such diseases include chronic obstructive pulmonary disease (COPD), a debilitating, respiratory condition characterized by progressive and largely irreversible airflow limitation for which cigarette smoking is the major risk factor. COPD is associated with an increased inflammatory cell influx including increased macrophage numbers in the airways and tissue. Alveolar macrophages develop from immigrating blood monocytes and have the capacity to cause the pathological changes associated with COPD. This study addressed the hypothesis that increased macrophage numbers in COPD are a result of increased recruitment of monocytes from the circulation. Chemotaxis assays of peripheral blood mononuclear cells (PBMC)/monocytes from nonsmokers, smokers, and COPD patients demonstrated increased chemotactic responses for cells from COPD patients when compared with controls toward growth-related oncogene (GRO)alpha and neutrophil-activating peptide (NAP)-2 but not toward monocyte chemoattractant protein, interleukin-8, or epithelial-derived NAP(ENA)-78. The enhanced chemotactic response toward GROalpha and NAP-2 was not mediated by differences in expression of their cellular receptors, CXCR1 or CXCR2. Receptor expression studies using flow cytometry indicated that in COPD, monocyte expression of CXCR2 is regulated differently from nonsmokers and smokers, which may account for the enhanced migration toward GROalpha and NAP-2. The results highlight the potential of CXCR2 antagonists as therapy for COPD and demonstrate that an enhanced PBMC/monocyte response to specific CXC chemokines in these patients may contribute to increased recruitment and activation of macrophages in the lungs.

Adult↗
PubMed2004

Histone acetylase and deacetylase activity in alveolar macrophages and blood mononocytes in asthma.

Histone acetylation status is a key factor in the regulation of inflammatory gene transcription. We investigated the activity of histone acetylases (HAT) and deacetylases (HDAC), and the effect of glucocorticoids in alveolar macrophages (AM) and peripheral blood mononuclear cells (PBMC) from subjects with asthma. Bronchoalveolar lavage was performed in 10 patients with intermittent asthma, 8 with persistent asthma, and 10 healthy control subjects. PBMCs and granulocytes were isolated from six patients with mild and severe asthma, before and after a 7-day course of prednisolone (30 mg/day). AMs were isolated for HDAC assay or incubated with dexamethasone (1 microM). HAT activity was increased (1.43 +/- 0.1 vs. 1.01 +/- 0.1 standard units/10 microg, p < 0.05), and HDAC activity was reduced (3031 +/- 243 vs. 5004 +/- 164 arbitrary fluorescence units/10 microg, p < 0.001) in AMs of subjects with asthma compared with control subjects. Dexamethasone suppressed LPS-induced granulocyte macrophage-colony stimulating factor, tumor necrosis factor-alpha, and interleukin-8 release by 83 +/- 1%, 51 +/- 7% and 20 +/- 9% (p < 0.001), respectively. Similar effects were seen on nuclear factor-kappaB inhibition, and interleukin-8 release was further reduced by the HDAC enhancer, theophylline (37 +/- 6%). Prednisolone increased HDAC activity in PBMCs from subjects with mild asthma. The increased inflammatory response in asthma may be due to reduced HDAC and enhanced HAT activity. Glucocorticoids and theophylline may downregulate the inflammatory response by modulating HAT and HDAC activity, and nuclear factor-kappaB activation.

Acetyltransferases↗
PubMed2004

Corticosteroid resistance in chronic obstructive pulmonary disease: inactivation of histone deacetylase.

By contrast with patients with asthma, those with chronic obstructive pulmonary disease (COPD) are poorly responsive to the anti-inflammatory actions of corticosteroids, and these drugs provide little clinical benefit. In both diseases, multiple inflammatory genes are activated, which results from acetylation of core histones around which DNA is wound. This acetylation opens up the chromatin structure allowing gene transcription and synthesis of inflammatory proteins to proceed. Corticosteroids recruit histone deacetylase 2 (HDAC2) to the actively transcribing gene, which reverses this process and switches off inflammatory gene transcription. We propose that in patients with COPD, HDAC2 function is impaired by cigarette smoking and oxidative stress, leading to a pronounced reduction in responsiveness to corticosteroids. Oxidative stress could generate peroxynitrite, which impairs HDAC2 activity through nitration of critical tyrosine residues. This hypothesis raises the possibility that novel therapeutic approaches might unlock this corticosteroid resistance, leading to more effective anti-inflammatory treatments for COPD and other severe inflammatory diseases.

Adrenal Cortex Hormones↗
PubMed2004

Inhibitors of protein kinase C (PKC) prevent activated transcription: role of events downstream of NF-kappaB DNA binding.

In pulmonary A549 cells, the protein kinase C (PKC) inhibitor, Ro 31-8220, and the phosphotidylcholine-specific phospholipase C inhibitor, D609, prevent NF-kappaB-dependent transcription, yet NF-kappaB DNA binding is unaffected (Bergmann, M., Hart, L., Lindsay, M., Barnes, P. J., and Newton, R. (1998) J. Biol. Chem. 273, 6607-6610). We now show that this effect also occurs in BEAS-2B bronchial epithelial cells as well as with other PKC inhibitors (Gö 6976, GF109203X, and calphostin C) in A549 cells. Similarly, phorbol ester, a diacylglycerol mimetic, activates NF-kappaB-dependent transcription and potentiates tumor necrosis factor alpha (TNFalpha)-induced NF-kappaB-dependent transcription, yet unlike TNFalpha, poorly activates IkappaB kinase (IKK) activity, IkappaBalpha degradation, or NF-kappaB DNA binding in both A549 and BEAS-2B cells. As phorbol ester-induced NF-kappaB-dependent transcription was relatively insensitive to the proteasome inhibitor, MG-132, PKC may affect NF-kappaB-dependent transcription via mechanisms other than the core IKK-IkappaB pathway. This is supported by Gal4 one hybrid analysis of p65/RelA transactivation, which was potentiated by TNFalpha and phorbol ester and was inhibited by Ro 31-8220 and D609. Additionally, a number of PKC isoforms, particularly the novel isoform PKCepsilon, induced p65/RelA transactivation. Phosphorylation of p65/RelA and cAMP-responsive element-binding protein (CREB)-binding protein (CBP) was increased by TNFalpha treatment and, in the case of CBP, was prevented by Ro 31-8220 or D609. However, p65/RelA-CBP interactions were unaffected by either compound. As this effect was not limited to NF-kappaB, but was a more general feature of inducible gene transcription, we suggest PKC isoforms may provide a point of intervention in diseases such as inflammation, or cancer, where activated gene expression is prominent.

Bridged-Ring Compounds↗
PubMed2004

Adenovirus-mediated delivery and expression of a cAMP-dependent protein kinase inhibitor gene to BEAS-2B epithelial cells abolishes the anti-inflammatory effects of rolipram, salbutamol, and prostaglandin E2: a comparison with H-89.

cAMP-elevating drugs are thought to mediate their biological effects by activating the cAMP/cAMP-dependent protein kinase (PKA) cascade. However, this hypothesis is difficult to confirm due to a lack of selective inhibitors. Here, we have probed the role of PKA in mediating inhibitory effects of several cAMP-elevating drugs in BEAS-2B epithelial cells using an adenovirus vector encoding a PKA inhibitor protein (PKIalpha) and have compared it to H-89, a commonly used small molecule PKA inhibitor. Initial studies established efficient gene transfer and confirmed functionality of PKIalpha 48 h after virus infection. All cAMP-elevating drugs tested promoted the phosphorylation of cAMP response element-binding protein (CREB), activated a cAMP response element (CRE)-driven luciferase reporter gene, and suppressed both granulocyte/macrophage colony-stimulating factor (GM-CSF) generation and [(3)H]arachidonic acid (AA) release in response to interleukin-1beta and monocyte chemotactic protein (MCP)-1, respectively. These effects were abolished by PKIalpha. In contrast, H-89 behaved unpredictably under the same conditions. Thus, although CREB phosphorylation evoked by a range of cAMP-elevating drugs was abolished by H-89, neither activation of the CRE-dependent luciferase reporter gene construct nor the inhibition of GM-CSF generation was inhibited. Paradoxically, H-89 antagonized MCP-1-induced [(3)H]AA release and enhanced the inhibitory effect of submaximal concentrations of rolipram and 8-bromo-cAMP. We suggest that expression of PKIalpha in susceptible cells provides a simple and unambiguous way to assess the role of PKA in cAMP signaling and to probe the mechanism of action of other drugs and cAMP-dependent responses where the participation of PKA is equivocal. Furthermore, these data suggest that H-89 is not a selective inhibitor of PKA and should be avoided.

Activating Transcription Factor 1↗
PubMed2004

COPD: is there light at the end of the tunnel?

No currently available treatments reduce the progression or suppress the inflammation of chronic obstructive pulmonary disease (COPD). However, with a better understanding of the inflammatory and destructive process, several targets have been identified and new treatments are in clinical development. Several specific therapies are directed against the influx of inflammatory cells into the airways and lung parenchyma that occurs in COPD, including adhesion molecule and chemokine-directed therapy, as well as therapies to inhibit tumour necrosis factor-alpha. Several broad-spectrum anti-inflammatory drugs are also in development, and include inhibitors of phosphodiesterase-4, p38 mitogen-activated protein kinase and nuclear factor-kappaB. There is a need for validated biomarkers and monitoring techniques in early clinical studies with new therapies for COPD.

Antioxidants↗