Cyclooxygenase enzymes in allergic inflammation and asthma

A systematic pharmacology-based in vivo study to reveal the effective mechanism of Yupingfeng in asthma treatment

BACKGROUND

The clinical effect of Yupingfeng (YPF) has been confirmed in asthma patients, however, it lacks a study to verify its pharmacological mechanism.

HYPOTHESIS/PURPOSE

To reveal the molecular basis and potential pharmacological mechanism of YPF in the treatment of asthma.

STUDY DESIGN AND METHODS

First, a systems pharmacology-based method integrating pharmacokinetic screening, target prediction, network analyses, GO and KEGG analyses were used for the systematic deciphering of the mechanism of YPF in asthma. Second, differentially expressed genes (DEGs) between asthma patients and healthy controls were identified by GEO2R online tool. Third, based on systems pharmacology and DEGs results, molecular docking was performed utilizing the Discovery Studio 2020 Client version to detect the binding capacity between compounds and targets. Finally, ovalbumin (OVA)-challenged C57BL/6 mice were treated with YPF or its effective compound to assess the predictions.

RESULTS

A total of 35 active compounds were filtered out, with 87 potential targets being identified for further analysis after target fishing and matching. Quercetin, kaempferol, and wogonin were identified as the main ingredients in YPF. The signaling pathways of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT), tumor necrosis factor (TNF) and IL-17 were identified as the top signaling pathways in KEGG enrichment analysis. GEO2R tools of NCBI discovered five DEGs that overlapped with the therapeutic targets of YPF. Wogonin was proven to be the top active compound in YPF through the results of molecular docking. In vivo experiments indicated that YPF and wogonin significantly attenuated airway resistance and lung inflammation by decreasing the levels of inflammatory cytokines and key factors in PI3K/AKT, IL-17, and TNF signaling pathways.

CONCLUSIONS

YPF and its main active compound wogonin may exert some therapeutic effects on asthma inflammation through multiple molecular targets and signaling pathways including PI3K/AKT, IL-17 and TNF-α.

Significance of Pulmonary Endothelial Injury and the Role of Cyclooxygenase-2 and Prostanoid Signaling

The endothelium plays a key role in the dynamic balance of hemodynamic, humoral and inflammatory processes in the human body. Its central importance and the resulting therapeutic concepts are the subject of ongoing research efforts and form the basis for the treatment of numerous diseases. The pulmonary endothelium is an essential component for the gas exchange in humans. Pulmonary endothelial dysfunction has serious consequences for the oxygenation and the gas exchange in humans with the potential of consecutive multiple organ failure. Therefore, in this review, the dysfunction of the pulmonary endothel due to viral, bacterial, and fungal infections, ventilator-related injury, and aspiration is presented in a medical context. Selected aspects of the interaction of endothelial cells with primarily alveolar macrophages are reviewed in more detail. Elucidation of underlying causes and mechanisms of damage and repair may lead to new therapeutic approaches. Specific emphasis is placed on the processes leading to the induction of cyclooxygenase-2 and downstream prostanoid-based signaling pathways associated with this enzyme.

The Anti-Allergic and Anti-Inflammatory Effects of Phlorotannins from the Edible Brown Algae, Ecklonia sp. and Eisenia sp

Because the number of people suffering from allergies has significantly increased, improved ways of treating these conditions by medical, pharmaceutical, and dietary means are required. Large numbers of studies on allergy have been conducted, and many anti-allergic compounds have been found. Phenolic compounds from terrestrial plants, including catechins and flavonoids, possess anti-allergic properties. Although polyphenols are present in some brown algae, their anti-allergic activities were not studied in detail before the 1990s. The focus was on the algal polyphenols, collectively called phlorotannins (eg., eckol, 6,6′-bieckol, 8,8′-bieckol, dieckol, and phlorofucofuroeckol-A), and research was conducted to clarify their anti-allergic activities. This review summarizes the anti-allergic effects of phlorotannins isolated from the brown alga, Eisenia nipponica, and related reports by other research groups.

Natural Products in the Prevention of Metabolic Diseases: Lessons Learned from the 20th KAST Frontier Scientists Workshop

The incidence of metabolic and chronic diseases including cancer, obesity, inflammation-related diseases sharply increased in the 21st century. Major underlying causes for these diseases are inflammation and oxidative stress. Accordingly, natural products and their bioactive components are obvious therapeutic agents for these diseases, given their antioxidant and anti-inflammatory properties. Research in this area has been significantly expanded to include chemical identification of these compounds using advanced analytical techniques, determining their mechanism of action, food fortification and supplement development, and enhancing their bioavailability and bioactivity using nanotechnology. These timely topics were discussed at the 20th Frontier Scientists Workshop sponsored by the Korean Academy of Science and Technology, held at the University of Hawaii at Manoa on 23 November 2019. Scientists from South Korea and the U.S. shared their recent research under the overarching theme of Bioactive Compounds, Nanoparticles, and Disease Prevention. This review summarizes presentations at the workshop to provide current knowledge of the role of natural products in the prevention and treatment of metabolic diseases.

Binding loop of sunflower trypsin inhibitor 1 serves as a design motif for proteolysis-resistant antimicrobial peptides

Although antimicrobial peptides (AMPs) have become powerful drug candidates in the post-antibiotic era, but their low protease stability hinders their clinical application. In the present study, the natural sunflower trypsin inhibitor 1 (SFTI-1) binding loop (CTKSIPPIC) was used to design and synthesize a specific anti-proteolytic sequence template ((RX)_n W (RX)_n CTKSIPPIC (n = 2, 3; X represents A, I, L, V, F, and W)). After several antibacterial, bactericidal, and toxicity tests, RV3 stood out from the variants and had the highest average selectivity index (SI _all = 156.03). It is highly stable in serum, varying pH, temperature, and salt ions as well as under high trypsin, pepsin, or papain concentrations. In a mouse skin inflammation model, established by Pseudomonas aeruginosa infection, RV3 could effectively kill the pathogen, promote wound healing, inhibit inflammatory cell infiltration, and inhibit mRNA and protein expression of TNF-α, IL-6, and IL-1β inflammatory factors. The antibacterial mechanisms of RV3 include combining with lipopolysaccharides and increasing cell membrane permeability, leading to cell membrane rupture and death. These findings indicate that RV3 has great potential for the treatment of bacterial infections.

Effects of COX inhibitors on responsiveness of the tracheal tract to acetylcholine and histamine and their relationship with LTC4 and PGE2 levels of bronchoalveolar lavage fluid in allergic Guinea pigs

Introduction: Nonsteroidal anti-inflammatory drugs (NSAIDs) intervene in the COX (cyclooxygenase) pathways which generate two important inflammation mediators, prostaglandins (PGs) and leukotriene (LTs). Contradictory claims regarding the effect of NSAIDs in asthmatic patients continues to be an issue. The present study investigated the effects of COX inhibitors on the responsiveness of the tracheal tract and on the levels of LTC4 and PGE2 in cells of the bronchoalveolar lavage fluid in an allergic guinea pig model.Materials and Methods: Adult male Dunkin-Hartley guinea pigs (250 - 300 g) were divided into seven groups of six animals each. Four COX inhibitors, aspirin (200 mg/kg and 20 mg/kg), indomethacin (10 mg/kg), ketoprofen (10 mg/kg), and celecoxib (25 mg/kg), were given orally on day 17 to allergy induced guinea pigs at 0, 12, and 24 h before ovalbumin challenge on day 18. PGF2 and LT4 were measured in the bronchoalveolar lavage fluid as well as inflammatory cell count and total protein. Tracheal responsiveness to acetylcholine (Ach) and histamine (His) also was evaluated.Results: An augment in the response of the trachea to Ach and His, as well as overt allergenic signs including short breath, wheezing and sneezing, was observed. The most significant increase in tracheal hyper-responsiveness was observed in the ketoprofen-treated group with similar but less pronounced changes observed in the indomethacin-treated group. Although some variables increased with the aspirin and celecoxib treatments, overall the tracheal sensitivity was reduced. Inflammatory cells including eosinophils and neutrophils corresponded to the changes observed for each treatment group.Conclusion: Ketoprofen and indomethacin increased the tracheal sensibility to Ach and His; therefore, their administration is not recommended in patients susceptible to allergy.

Amphiphilic Triazine Polymer Derivatives as Antibacterial And Anti-atopic Agents in Mice Model

Considering the emergence of bacterial resistance and low proteolytic stability of antimicrobial peptides (AMPs), herein we developed a series of ultra-short triazine based amphipathic polymers (TZP) that are connected with ethylene diamine linkers instead of protease sensitive amide bond. The most potent oligomers, TZP3 and TZP5 not only displayed potent antibacterial action on various drug-resistant pathogens but also exhibited a strong synergic antibacterial activity in combination with chloramphenicol against multidrug-resistant Pseudomonas aeruginosa (MDRPA). Since most of atopic dermatitis (AD) infections are caused by bacterial colonization, we evaluated the potency of TZP3 and TZP5 on AD in vitro and in vivo. In vitro AD analysis of these two polymers showed significant inhibition against the release of β-hexosaminidase and tumor necrosis factor (TNF-α) from RBL-2H3 cells. In AD-like skin lesions in BALB/c mice model, these two polymers displayed significant potency in suppressing dermal and epidermal thickness, mast cell infiltration and pro-inflammatory cytokines expression. Moreover, these polymers exhibited remarkable efficacy over the allergies caused by the imbalance of Th1/Th2 by regulating total IgE and IgG2a. Finally, the impact of treatment effects of these polymers was examined through analyzing the weights and sizes of spleen and lymph node of AD-induced mice.

Ethanol Extract of Sesamum indicum Linn. Inhibits FcεRI-Mediated Allergic Reaction via Regulation of Lyn/Syk and Fyn Signaling Pathways in Rat Basophilic Leukemic RBL-2H3 Mast Cells

This study is aimed at determining whether Sesamum indicum Linn. beneficially influences FcεRI-mediated allergic reactions in RBL-2H3 mast cells; it is also aimed at further investigating Lyn/Fyn and Syk signaling pathways. To examine the antiallergic effect of Sesamum indicum Linn. extract (SIE), we treated antigen/immunoglobulin E- (IgE-) sensitized mast cells with extracts of various concentrations. We examined the degranulation release and concentrations of inflammatory mediators. Additionally, the expressions of genes involved in the FcεRI and arachidonate signaling pathways were examined. SIE inhibited the degranulation and secretion of inflammatory mediators in antigen/IgE-sensitized mast cells. SIE reduced the expressions of FcεRI signaling-related genes, such as Syk, Lyn, and Fyn, and the phosphorylation of extracellular signal-regulated kinase in antigen/IgE-sensitized mast cells. Additionally, in late allergic responses, SIE reduced PGD₂ release and COX-2 and cPLA2 phosphorylation expression in FcεRI-mediated mast cell activation. Lastly, 250–500 mg/kg SIE significantly attenuated the Ag/IgE-induced passive cutaneous anaphylaxis (PCA) reaction in mice. The potent effect of SIE on RBL-2H3 mast cell activation indicates that the extract could potentially be used as a novel inhibitor against allergic reactions.

A novel concept of immunological and allergy interactions in autism spectrum disorders: Molecular, anti-inflammatory effect of osthole

BACKGROUND

Autism spectrum disorder (ASD) is a neurodevelopmental disorder defined by Diagnosis and Statistic Manual 5 (DSM-5) as persistent social interaction and communication deficient across multiple contexts. Various immunological findings have been reported in children with ASD, and co-existing allergic problems have been recorded in children diagnosed with ASD. Osthole, the effective component of Chinese traditional medicine, is reported to have anti-inflammatory effects. This study assessed the anti-inflammatory effect of osthole on the histamine-induced inflammatory responses in PBMC cells.

METHODS

Peripheral blood mononuclear cells (PBMC's) from children with: (1) ASD group with co-existing allergies/asthma (n = 29); (2) ASD group without allergy/asthma (n = 29); (3) Allergy group (n = 30) and from typically developing age-matched control subjects (n = 28) were stimulated with either histamine, FXF, osthole or mixture of this substances. mRNA COX-2 gene expression, COX-2 production and inhibitory effect of tested substances on COX-2 were assessed after stimulation.

RESULTS

Children with ASD may show either an innate proinflammatory response or increased activity of COX-2 which could display more impaired behavioral profile than children with non-inflamed. This study indicated that COX-2 may be involved in pathogenesis of ASD and/or allergy, and osthole could be used to decrease the effects of COX-2 in inflammation and ASD development. High incidence of allergy in ASD patients may indicate immune dysregulation that could be of relevance to the pathophysiology, symptomatology or neuroimmunology of ASD.

CONCLUSIONS

This study shows that fexofenadine (FXF - antihistamine drug) and osthole exhibit selective COX-2 enzyme inhibitory activity. The selective COX-2 activity of osthole may explain further the anti-inflammatory properties of osthole in relieving congestion in allergic rhinitis, and as distinctive effects between FXF and osthole were observed, individual antihistamines may have different modes of action via the COX enzyme system.

Feline calicivirus- and murine norovirus-induced COX-2/PGE2 signaling pathway has proviral effects

Cyclooxygenases (COXs)/prostaglandin E₂ (PGE₂) signaling pathways are known to modulate a variety of homeostatic processes and are involved in various pathophysiological conditions. COXs/PGE₂ signaling pathways have also been demonstrated to have proviral or antiviral effects, which appeared different even in the same virus family. A porcine sapovirus Cowden strain, a member of genus Sapovirus within the Caliciviridae family, induces strong COX-2/PGE₂ but transient COX-1/PGE₂ signaling to enhance virus replication. However, whether infections of other viruses in the different genera activate COXs/PGE₂ signaling, and thus affect the replication of viruses, remains unknown. In the present study, infections of cells with the feline calicivirus (FCV) F9 strain in the genus Vesivirus and murine norovirus (MNV) CW-1 strain in the genus Norovirus only activated the COX-2/PGE₂ signaling in a time-dependent manner. Treatment with pharmacological inhibitors or transfection of small interfering RNAs (siRNAs) against COX-2 enzyme significantly reduced the production of PGE₂ as well as FCV and MNV replications. The inhibitory effects of these pharmacological inhibitors against COX-2 enzyme on the replication of both viruses were restored by the addition of PGE₂. Silencing of COX-1 via siRNAs and inhibition of COX-1 via an inhibitor also decrease the production of PGE₂ and replication of both viruses, which can be attributed to the inhibition COX-1/PGE₂ signaling pathway. These data indicate that the COX-2/PGE₂ signaling pathway has proviral effects for the replication of FCV and MNV, and pharmacological inhibitors against these enzymes serve as potential therapeutic candidates for treating FCV and MNV infections.

Expression and Activity of COX-1 and COX-2 in Acanthamoeba sp.-Infected Lungs According to the Host Immunological Status

Little is known about the pathomechanism of pulmonary infections caused by Acanthamoeba sp. Therefore, the aim of this study was to determine whether Acanthamoeba sp. may affect the expression and activity of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), resulting in the altered levels of their main products, prostaglandins (PGE₂) and thromboxane B₂ (TXB₂), in lungs of immunocompetent or immunosuppressed hosts. Acanthamoeba sp. induced a strong expression of COX-1 and COX-2 proteins in the lungs of immunocompetent mice, which, however, did not result in significant differences in the expression of PGE₂ and TXB₂. Our immunohistochemical analysis showed that immunosuppression induced by glucocorticoids in Acanthamoeba sp.-infected mice caused a decrease in COX-1 and COX-2 (not at the beginning of infection) in lung tissue. These results suggest that similar to COX-2, COX-1 is an important mediator of the pathophysiology in experimental pulmonary acanthamoebiasis. We suggest that the signaling pathways important for Acanthamoeba sp. induction of lung infection might interact with each other and depend on the host immune status.

Inhibitory effect of Zizania latifolia chloroform fraction on allergy-related mediator production in RBL-2H3 cells

Zizania latifolia exhibits anti-inflammatory and anti-allergic effects; however, the mechanisms behind these effects are unknown. Here the ethanol extract of Z. latifolia was partitioned using hexane, chloroform, ethyl acetate, butanol, and water. Subsequently, the anti-allergic effects of these fractions were evaluated in vitro. The results showed that the chloroform fraction of Z. latifolia inhibited the release of β-hexosaminidase and tumor necrosis factor (TNF-α) from RBL-2H3 cells stimulated with dinitrophenyl-bovine serum albumin (DNP-BSA). In addition, this fraction suppressed the expression of cyclooxygenase-2 (COX-2) and inhibited the activation of mitogen-activated protein kinases (MAPKs). The results obtained suggest that the chloroform fraction of Z. latifolia inhibited mast cell-mediated allergic inflammatory responses.

Investigational prostaglandin D2 receptor antagonists for airway inflammation

INTRODUCTION

By activating DP1 and DP2 receptors on immune and non-immune cells, prostaglandin D2 (PGD2), a major metabolic product of cyclo-oxygenase pathway released after IgE-mediated mast cell activation, has pro-inflammatory effects, which are relevant to the pathophysiology of allergic airway disease. At least 15 selective, orally active, DP2 receptor antagonists and one DP1 receptor antagonist (asapiprant) are under development for asthma and/or allergic rhinitis.

AREAS COVERED

In this review, the authors cover the pharmacology of PGD2 and PGD2 receptor antagonists and look at the preclinical, phase I and phase II studies with selective DP1 and DP2 receptor antagonists.

EXPERT OPINION

Future research should aim to develop once daily compounds and increase the drug clinical potency which, apart from OC000459 and ADC-3680, seems to be relatively low. Further research and development of DP2 receptor antagonists is warranted, particularly in patients with severe uncontrolled asthma, whose management is a top priority. Pediatric studies, which are not available, are required for assessing the efficacy and safety of this novel drug class in children with asthma and allergic rhinitis. Studies on the efficacy of DP2 receptor antagonists in various asthma phenotypes including: smokers, obese subjects, early vs late asthma onset, fixed vs reversible airflow limitation, are required for establishing their pharmacotherapeutic role.

NecroX-5 suppresses IgE/Ag-stimulated anaphylaxis and mast cell activation by regulating the SHP-1-Syk signaling module

BACKGROUND

IgE/Ag-stimulated mast cells release various pro-allergic inflammatory mediators, including histamine, eicosanoids, and pro-inflammatory cytokines. NecroX-5, a cell permeable necrosis inhibitor, showed cytoprotective effects in both in vitro and in vivo models. However, the anti-allergic effect of NecroX-5 has not yet been investigated. The aims of this study were to evaluate the anti-allergic activity of NecroX-5 in vivo and to investigate the underlying mechanism in vitro.

METHODS

The anti-allergic activity of NecroX-5 was evaluated in vitro using bone marrow-derived mast cells (BMMCs) and IgE receptor-bearing RBL-2H3 or KU812 cells and in vivo using a mouse model of passive anaphylaxis. The levels of histamine, eicosanoids (PGD2 and LTC4 ), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) were measured using enzyme immunoassay kits. The mechanism underlying the action of NecroX-5 was investigated using immunoblotting, immunoprecipitation, and gene knockdown techniques.

RESULTS

NecroX-5 markedly inhibited mast cell degranulation and the synthesis of eicosanoids, TNF-α, and IL-6 by suppressing the activation of Syk, LAT, phospholipase Cγ1, MAP kinases, the Akt/NF-κB pathway, and intracellular Ca(2+) mobilization via the activation of phosphatase SHP-1. Oral administration of NecroX-5 effectively suppressed mast cell-dependent passive cutaneous and systemic anaphylactic reactions in a dose-dependent manner.

CONCLUSIONS

NecroX-5 might be a potential candidate for the development of a novel anti-allergic agent that suppresses IgE-dependent mast cells signaling.

Effect of gedunin on acute articular inflammation and hypernociception in mice

Gedunin, a natural limonoid from Meliaceae species, has been previously described as an antiinflammatory compound in experimental models of allergic inflammation. Here, we report the antiinflammatory and antinociceptive effects of gedunin in an acute model of articular inflammation induced by zymosan (500 μg/cavity; intra-articular) in C57BL/6 mice. Intraperitoneal (i.p.) pretreatment with gedunin (0.005–5 mg/kg) impaired zymosan-induced edema formation, neutrophil accumulation and hypernociception in mouse knee joints, due to decreased expression of preproET-1 mRNA and production of LTB₄, PGE₂, TNF-α and IL-6. Mouse post-treatment with gedunin (0.05 mg/kg; i.p.) 1 and 6 h after stimulation also impaired articular inflammation, by reverting edema formation, neutrophil accumulation and the production of lipid mediators, cytokines and endothelin. In addition, gedunin directly modulated the functions of neutrophils and macrophages in vitro. The pre-incubation of neutrophil with gedunin (100 µM) impaired shape change, adhesion to endothelial cells, chemotaxis and lipid body formation triggered by different stimuli. Macrophage pretreatment with gedunin impaired intracellular calcium mobilization, nitric oxide production, inducible nitric oxide synthase expression and induced the expression of the antiinflammatory chaperone heat shock protein 70. Our results demonstrate that gedunin presents remarkable antiinflammatory and anti-nociceptive effects on zymosan-induced inflamed knee joints, modulating different cell populations.

Lung inflammation caused by adenosine-5'-triphosphate is mediated via Ca2+/PKCs-dependent COX-2/PGE2 induction

Up-regulation of cyclooxygenase (COX)-2 and prostaglandin E2 (PGE2) are implicated in lung inflammation. Adenosine 5'-triphosphate (ATP) has been shown to act via activation of P2 purinoceptors, leading to COX-2 expression in various inflammatory diseases. The mechanisms of ATP-induced COX-2 expression and PGE2 release remain unclear. We showed that pretreatment with the inhibitors of P2 receptors (PPADS and Suramin), Gq protein (GPA2A), phosphatidylcholine-phospholipase C (PC-PLC; D609), phosphoinositide-phospholipase C (PI-PLC; ET-18-OCH3), Ca(2+)/calmodulin-dependent protein kinase II (CaMKII; KN62), protein kinase C (PKC; Gö6976, Ro-318220, GF109203X, and rottlerin), MEK1/2 (PD98059), p38 MAPK (SB202190), and nuclear factor-kappaB (NF-κB; Bay11-7082) and the intracellular calcium chelator (BAPTA/AM) or transfection with siRNAs of these molecules and cPLA2 reduced ATPγS-induced COX-2 expression or PGE2 production in A549 cells. In addition, ATPγS-induced elevation of intracellular Ca(2+) concentration was attenuated by PPADS, Suramin, D609, or ET-18-OCH3. ATPγS-induced p38 MAPK, p42/p44 MAPK, and NF-κB p65 activation were inhibited by Gö6976, Ro-318220, GF109203X, or rottlerin. ATPγS also induced cPLA2 phosphorylation and activity, which were reduced via inhibition of P2 receptors, PKCs, p38 MAPK, and p42/p44 MAPK. ATPγS-induced cPLA2 expression was inhibited by SB202190, PD98059, or Bay11-7082. In the in vitro study, we established that ATPγS induced PGE2 generation via a cPLA2/COX-2-dependent pathway. In the in vivo study, we found that ATPγS induced COX-2 mRNA expression in the lungs and leukocyte (mainly eosinophils and neutrophils) count in bronchoalveolar lavage (BAL) fluid in mice via a P2 receptors-dependent signaling pathway. We concluded that ATPγS may induce lung inflammation via a cPLA2/COX-2/PGE2-dependent pathway.

Inhibitory effect of echinocystic acid on 12-O-tetradecanoylphorbol-13-acetate-induced dermatitis in mice

The rhizome of Codonopsis lanceolata (family Campanulaceae), which contains lancemaside A as a main constituent, is frequently used in the traditional Chinese medicine for the treatment of inflammatory diseases. Lancemaside A exhibits anti-inflammatory effect in vitro and in vivo. However, orally administered lancemaside A is metabolized to echinocystic acid by the intestinal microflora and the metabolite is absorbed into the blood. Therefore, to understand whether echinocystic acid is effective against skin inflammatory diseases, we assessed its inhibitory effect against 12-O-tetra decanoylphorbol-13-acetate (TPA)-induced ear inflammation in mice. Topically administered echinocystic acid potently suppressed TPA-induced ear swelling. The suppression rates at 0.05 and 0.10 % concentrations were 65 and 73 %, respectively. Echinocystic acid also inhibited TPA-induced myeloperoxidase activity, as well as COX-2, iNOS, TNF-α and IL-1β expressions. Echinocystic acid inhibited NF-κB in TPA-treated mouse ears, as well as in lipopolysaccharide-stimulated peritoneal macrophages. Its potency is comparable with that of dexamethasone. These findings indicate that echinocystic acid may ameliorate inflammatory diseases, such as dermatitis.

Proinflammatory effects of cookstove emissions on human bronchial epithelial cells

Approximately half of the world's population uses biomass fuel for indoor cooking and heating. This form of combustion typically occurs in open fires or primitive stoves. Human exposure to emissions from indoor biomass combustion is a global health concern, causing an estimated 1.5 million premature deaths each year. Many 'improved' stoves have been developed to address this concern; however, studies that examine exposure-response with cleaner-burning, more efficient stoves are few. The objective of this research was to evaluate the effects of traditional and cleaner-burning stove emissions on an established model of the bronchial epithelium. We exposed well-differentiated, normal human bronchial epithelial cells to emissions from a single biomass combustion event using either a traditional three-stone fire or one of two energy-efficient stoves. Air-liquid interface cultures were exposed using a novel, aerosol-to-cell deposition system. Cellular expression of a panel of three pro-inflammatory markers was evaluated at 1 and 24 h following exposure. Cells exposed to emissions from the cleaner-burning stoves generated significantly fewer amounts of pro-inflammatory markers than cells exposed to emissions from a traditional three-stone fire. Particulate matter emissions from each cookstove were substantially different, with the three-stone fire producing the largest concentrations of particles (by both number and mass). This study supports emerging evidence that more efficient cookstoves have the potential to reduce respiratory inflammation in settings where solid fuel combustion is used to meet basic domestic needs.

PRACTICAL IMPLICATIONS

Emissions from more efficient, cleaner-burning cookstoves produced less inflammation in well-differentiated bronchial lung cells. The results support evidence that more efficient cookstoves can reduce the health burden associated with exposure to indoor pollution from the combustion of biomass.

ATP mediates NADPH oxidase/ROS generation and COX-2/PGE2 expression in A549 cells: role of P2 receptor-dependent STAT3 activation

BACKGROUND

Up-regulation of cyclooxygenase (COX)-2 and its metabolite prostaglandin E(2) (PGE(2)) are frequently implicated in lung inflammation. Extracellular nucleotides, such as ATP have been shown to act via activation of P2 purinoceptors, leading to COX-2 expression in various inflammatory diseases, such as lung inflammation. However, the mechanisms underlying ATP-induced COX-2 expression and PGE(2) release remain unclear.

PRINCIPAL FINDINGS

Here, we showed that ATPγS induced COX-2 expression in A549 cells revealed by western blot and real-time PCR. Pretreatment with the inhibitors of P2 receptor (PPADS and suramin), PKC (Gö6983, Gö6976, Ro318220, and Rottlerin), ROS (Edaravone), NADPH oxidase [diphenyleneiodonium chloride (DPI) and apocynin], Jak2 (AG490), and STAT3 [cucurbitacin E (CBE)] and transfection with siRNAs of PKCα, PKCι, PKCμ, p47(phox), Jak2, STAT3, and cPLA(2) markedly reduced ATPγS-induced COX-2 expression and PGE(2) production. In addition, pretreatment with the inhibitors of P2 receptor attenuated PKCs translocation from the cytosol to the membrane in response to ATPγS. Moreover, ATPγS-induced ROS generation and p47(phox) translocation was also reduced by pretreatment with the inhibitors of P2 receptor, PKC, and NADPH oxidase. On the other hand, ATPγS stimulated Jak2 and STAT3 activation which were inhibited by pretreatment with PPADS, suramin, Gö6983, Gö6976, Ro318220, GF109203X, Rottlerin, Edaravone, DPI, and apocynin in A549 cells.

SIGNIFICANCE

Taken together, these results showed that ATPγS induced COX-2 expression and PGE(2) production via a P2 receptor/PKC/NADPH oxidase/ROS/Jak2/STAT3/cPLA(2) signaling pathway in A549 cells. Increased understanding of signal transduction mechanisms underlying COX-2 gene regulation will create opportunities for the development of anti-inflammation therapeutic strategies.

Adenosine A(1) and prostaglandin E receptor 3 receptors mediate global airway contraction after local epithelial injury

Epithelial injury and airway hyperresponsiveness are prominent features of asthma. We have previously demonstrated that laser ablation of single epithelial cells immediately induces global airway constriction through Ca(2+)-dependent smooth muscle shortening. The response is mediated by soluble mediators released from wounded single epithelial cells; however, the soluble mediators and signaling mechanisms have not been identified. In this study, we investigated the nature of the epithelial-derived soluble mediators and the associated signaling pathways that lead to the L-type voltage-dependent Ca(2+) channel (VGCC)-mediated Ca(2+) influx. We found that inhibition of adenosine A1 receptors (or removal of adenosine with adenosine deaminase), cyclooxygenase (COX)-2 or prostaglandin E receptor 3 (EP3) receptors, epidermal growth factor receptor (EGFR), or platelet-derived growth factor receptor (PDGFR) all significantly blocked Ca(2+) oscillations in smooth muscle cells and airway contraction induced by local epithelial injury. Using selective agonists to activate the receptors in the presence and absence of selective receptor antagonists, we found that adenosine activated the signaling pathway A1R→EGFR/PDGFR→COX-2→EP3→VGCCs→calcium-induced calcium release, leading to intracellular Ca(2+) oscillations in airway smooth muscle cells and airway constriction.

Suppression of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced skin inflammation in mice by transduced Tat-Annexin protein

We examined that the protective effects of ANX1 on 12-O-tetradecanoylphorbol- 13-acetate (TPA)-induced skin inflammation in animal models using a Tat-ANX1 protein. Topical application of the Tat-ANX1 protein markedly inhibited TPAinduced ear edema and expression levels of cyclooxygenase-2 (COX-2) as well as pro-inflammatory cytokines such as interleukin- 1 beta (IL-1 β), IL-6, and tumor necrosis factor-alpha (TNF-α). Also, application of Tat-ANX1 protein significantly inhibited nuclear translocation of nuclear factor-kappa B (NF-κ B) and phosphorylation of p38 and extracellular signalregulated kinase (ERK) mitogen-activated protein kinase (MAPK) in TPA-treated mice ears. The results indicate that Tat-ANX1 protein inhibits the inflammatory response by blocking NF-κ B and MAPK activation in TPA-induced mice ears. Therefore, the Tat-ANX1 protein may be useful as a therapeutic agent against inflammatory skin diseases.

COX inhibitors for airway inflammation

INTRODUCTION

The cyclooxygenase (COX) enzyme, which is responsible for the production of prostaglandins (PGs), key mediators of inflammation, may have the potential to become an attractive target for anti-inflammatory therapy. COX catalyzes the conversion of arachidonic acid (AA) into PGs, which play a significant role in disease. PGs are lipid mediators of central importance in the regulation of inflammation and smooth muscle tone. Airway-resident inflammatory cells release PGs: PGD2 and PDF2a amplify smooth muscle contraction and airway inflammation. Following its conversion from membrane phospholipids by phospholipase, AA enters the prostanoid pathway via COX, which catalyzes the conversion of AA to PGH2. PGH2 is then converted to biologically active PGs by cell-specific PG synthases. As COX is the rate limiting step in the PG pathway, the regulation of this enzyme is of critical importance in PG production.

AREAS COVERED

This review addresses the opportunities and challenges of COX inhibitors as therapeutic targets in airway inflammation. The review covers literature from the past 20 years.

EXPERT OPINION

Current literature favors COX inhibitors as potential targets for airway diseases. However, from the information available, it is not clear whether the COX enzyme by itself can serve as a target in drug development for asthma and COPD. Therefore, additional research is required to elucidate the mechanisms of action of COX metabolites before it can be considered as a target.

Noninvasive imaging identifies new roles for cyclooxygenase-2 in choline and lipid metabolism of human breast cancer cells

The expression of cyclooxygenase-2 (COX-2) is observed in approximately 40% of breast cancers. A major product of the COX-2-catalyzed reaction, prostaglandin E(2), is an inflammatory mediator that participates in several biological processes, and influences invasion, vascularization and metastasis. Using noninvasive MRI and MRS, we determined the effect of COX-2 downregulation on the metabolism and invasion of intact poorly differentiated MDA-MB-231 human breast cancer cells stably expressing COX-2 short hairpin RNA. Dynamic tracking of invasion, extracellular matrix degradation and metabolism was performed with an MRI- and MRS-compatible cell perfusion assay under controlled conditions of pH, temperature and oxygenation over the course of 48  h. COX-2-silenced cells exhibited a significant decrease in invasion relative to parental cells that was consistent with the reduced expression of invasion-associated matrix metalloproteinase genes and an increased level of the tissue inhibitor of metalloproteinase-1. We identified, for the first time, a role for COX-2 in mediating changes in choline phospholipid metabolism, and established that choline kinase expression is partly dependent on COX-2 function. COX-2 silencing resulted in a significant decrease in phosphocholine and total choline that was detected by MRS. In addition, a significant increase in lipids, as well as lipid droplet formation, was observed. COX-2 silencing transformed parental cell metabolite patterns to those characteristic of less aggressive cancer cells. These new functional roles of COX-2 may identify new biomarkers and new targets for use in combination with COX-2 targeting to prevent invasion and metastasis.

Iloprost has potent anti-inflammatory properties on human monocyte-derived dendritic cells

BACKGROUND

The stable prostaglandin I2 analogue (iloprost) iloprost has been shown to inhibit allergic airway inflammation in mice by modulating the function of myeloid dendritic cells (DCs).

OBJECTIVE

The aim of the current study was to investigate the biological activity of iloprost on human monocyte-derived DCs.

METHODS

I prostanoid (IP) receptor expression was analysed by RT-PCR. Cytokine secretion by DCs and CD4+ T cells was measured by ELISA. The expression of the transcription factor FoxP3 after co-culture of DCs with CD4+ CD45RA+ T cells was analysed by flow cytometry.

RESULTS

Human monocyte-derived DCs were found to express mRNA specific for the PGI2 receptor IP, and stimulation with iloprost resulted in increased cyclic AMP levels in both immature DCs (iDCs) and mature DCs (mDCs). Moreover, iloprost dose dependently inhibited the secretion of TNF-alpha, IL-6, IL-8 and IL-12p70 in mDCs, while it enhanced IL-10 production. Changes in cytokine secretion were paralleled by an altered T-cell priming capacity of DCs: in co-culture experiments of iloprost-treated mDC and naïve CD45RA+ T cells, an induction of regulatory T cells could be observed, as demonstrated by increased intracellular FoxP3 expression and IL-10 production. Additionally, iloprost inhibited the MIP-3beta-induced migration of mDCs.

CONCLUSION

In summary, our results provide evidence that iloprost profoundly affects the function of human myeloid DCs. Therefore, iloprost might also be a new therapeutical option for the treatment of asthma in humans.

Pharmacologic inhibition of COX-1 and COX-2 in influenza A viral infection in mice

Background

We previously demonstrated that cyclooxygenase (COX)-1 deficiency results in greater morbidity and inflammation, whereas COX-2 deficiency leads to reduced morbidity, inflammation and mortality in influenza infected mice.

Methodology/Principal Findings

We investigated the effects of COX-1 and COX-2 inhibitors in influenza A viral infection. Mice were given a COX-1 inhibitor (SC-560), a COX-2 inhibitor (celecoxib) or no inhibitor beginning 2 weeks prior to influenza A viral infection (200 PFU) and throughout the course of the experiment. Body weight and temperature were measured daily as indicators of morbidity. Animals were sacrificed on days 1 and 4 post-infection and bronchoalveolar lavage (BAL) fluid was collected or daily mortality was recorded up to 2 weeks post-infection. Treatment with SC-560 significantly increased mortality and was associated with profound hypothermia and greater weight loss compared to celecoxib or control groups. On day 4 of infection, BAL fluid cells were modestly elevated in celecoxib treated mice compared to SC-560 or control groups. Viral titres were similar between treatment groups. Levels of TNF-α and G-CSF were significantly attenuated in the SC-560 and celecoxib groups versus control and IL-6 levels were significantly lower in BAL fluid of celecoxib treated mice versus control and versus the SC-560 group. The chemokine KC was significantly lower in SC-560 group versus control.

Conclusions/Significance

Treatment with a COX-1 inhibitor during influenza A viral infection is detrimental to the host whereas inhibition of COX-2 does not significantly modulate disease severity. COX-1 plays a critical role in controlling the thermoregulatory response to influenza A viral infection in mice.

Rap1 mediates protective effects of iloprost against ventilator-induced lung injury

Prostaglandin I(2) (PGI(2)) has been shown to attenuate vascular constriction, hyperpermeability, inflammation, and acute lung injury. However, molecular mechanisms of PGI(2) protective effects on pulmonary endothelial cells (EC) are not well understood. We tested a role of cAMP-activated Epac-Rap1 pathway in the barrier protective effects of PGI(2) analog iloprost in the murine model of ventilator-induced lung injury. Mice were treated with iloprost (2 microg/kg) after onset of high tidal volume ventilation (30 ml/kg, 4 h). Bronchoalveolar lavage, histological analysis, and measurements of Evans blue accumulation were performed. In vitro, microvascular EC barrier function was assessed by morphological analysis of agonist-induced gap formation and monitoring of Rho pathway activation and EC permeability. Iloprost reduced bronchoalveolar lavage protein content, neutrophil accumulation, capillary filtration coefficient, and Evans blue albumin extravasation caused by high tidal volume ventilation. Small-interfering RNA-based Rap1 knockdown inhibited protective effects of iloprost. In vitro, iloprost increased barrier properties of lung microvascular endothelium and alleviated thrombin-induced EC barrier disruption. In line with in vivo results, Rap1 depletion attenuated protective effects of iloprost in the thrombin model of EC permeability. These data describe for the first time protective effects for Rap1-dependent signaling against ventilator-induced lung injury and pulmonary endothelial barrier dysfunction.

Cigarette smoke extract induces COX-2 expression via a PKCalpha/c-Src/EGFR, PDGFR/PI3K/Akt/NF-kappaB pathway and p300 in tracheal smooth muscle cells

Exposure to cigarette smoke extract (CSE) leads to airway or lung inflammation, which may be mediated through cyclooxygenase-2 (COX-2) expression and its product prostaglandin E2 (PGE2) synthesis. The aim of this study was to investigate the molecular mechanisms underlying CSE-induced COX-2 expression in human tracheal smooth muscle cells (HTSMCs). Here, we describe that COX-2 induction is dependent on PKCalpha/c-Src/EGFR, PDGFR/PI3K/Akt/NF-kappaB signaling in HTSMCs. CSE stimulated the phosphorylation of c-Src, EGFR, PDGFR, and Akt, which were inhibited by pretreatment with the inhibitor of PKCalpha (Gö6976 or Gö6983), c-Src (PP1), EGFR (AG1478), PDGFR (AG1296), or PI3K (LY294002). Moreover, CSE induced a significant increase in COX-2 expression, which was reduced by pretreatment with these inhibitors or transfection with siRNA of PKCalpha, Src, or Akt. Furthermore, CSE-stimulated NF-kappaB p65 phosphorylation and translocation were also attenuated by pretreatment with Gö6976, PP1, AG1478, AG1296, or LY294002. CSE-induced COX-2 expression was also mediated through the recruitment of p300 associated with NF-kappaB in HTSMCs, revealed by coimmunoprecipitation and Western blot analysis. In addition, pretreatment with the inhibitors of NF-kappaB (helenalin) and p300 (garcinol) or transfection with p65 siRNA and p300 siRNA markedly inhibited CSE-regulated COX-2 expression. However, CSE-induced PGE2 generation was reduced by pretreatment with the inhibitor of COX-2 (NS-398). These results demonstrated that in HTSMCs, CSE-induced COX-2-dependent PGE2 generation was mediated through PKCalpha/c-Src/EGFR, PDGFR/PI3K/Akt leading to the recruitment of p300 with NF-kappaB complex.

Mechanistic systems biology of inflammatory gene expression in airway smooth muscle as tool for asthma drug development

There is compelling evidence that airway smooth muscle cells may function as inflammatory cells in the airway system by producing multiple inflammatory cytokines in response to a large array of external stimuli such as acetylcholine, bradykinin, inflammatory cytokines, and toll-like receptor activators. However, how multiple extracellular stimuli interact in the regulation of inflammatory gene expression in an airway smooth muscle cell remains poorly understood. This review addresses the mechanistic systems biology of inflammatory gene expression in airway smooth muscle by discussing: a) redundancy underlying multiple stimulus-product relations in receptor-mediated inflammatory gene expression, and their regulation by convergent activation of Erk1/2 mitogen-activated protein kinase (MAPK), b) Erk1/2 MAPK-dependent induction of phosphatase expression as a negative feedback mechanism in the robust maintenance of inflammatory gene expression, and c) cyclooxygenase 2-dependent regulation of the differential temporal dynamics of early and late inflammatory gene expression. It is becoming recognized that a single-target approach is unlikely to be effective for the treatment of inflammatory airway diseases because airway inflammation is a result of complex interactions among multiple inflammatory mediators and cells types in the airway system. Understanding the mechanistic systems biology of inflammatory gene expression in airway smooth muscle and other cell types in the airway system may lead to the development of multi-target drug regimens for the treatment of inflammatory airway diseases such as asthma.

CREB mediates prostaglandin F2alpha-induced MUC5AC overexpression

Mucus secretion is an important protective mechanism for the luminal lining of open tubular organs, but mucin overproduction in the respiratory tract can exacerbate the inflammatory process and cause airway obstruction. Production of MUC5AC, a predominant gel-forming mucin secreted by airway epithelia, can be induced by various inflammatory mediators such as prostaglandins. The two major prostaglandins involved in inflammation are PGE(2) and PGF(2alpha). PGE(2)-induced mucin production has been well studied, but the effect of PGF(2alpha) on mucin production remains poorly understood. To elucidate the effect and underlying mechanism of PGF(2alpha) on MUC5AC production, we investigated the signal transduction of PGF(2alpha) associated with this effect using normal human tracheobronchial epithelial cells. Our results demonstrated that PGF(2alpha) induces MUC5AC overproduction via a signaling cascade involving protein kinase C, ERK, p90 ribosomal S6 protein kinase, and CREB. The regulation of PGF(2alpha)-induced MUC5AC expression by CREB was further confirmed by cAMP response element-dependent MUC5AC promoter activity and by interaction between CREB and MUC5AC promoter. The abrogation of all downstream signaling activities via suppression of each signaling molecule along the pathway indicates that a single pathway from PGF(2alpha) receptor to CREB is responsible for inducing MUC5AC overproduction. As CREB also mediates mucin overproduction induced by PGE(2) and other inflammatory mediators, our findings have important clinical implications for the management of airway mucus hypersecretion.

Inhibition of LPS-induced cyclooxygenase 2 and nitric oxide production by transduced PEP-1-PTEN fusion protein in Raw 264.7 macrophage cells

Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a tumor suppressor. Although it is well known to have various physiological roles in cancer, its inhibitory effect on inflammation remains poorly understood. In the present study, a human PTEN gene was fused with PEP-1 peptide in a bacterial expression vector to produce a genetic in-frame PEP-1-PTEN fusion protein. The expressed and purified PEP-1-PTEN fusion protein were transduced efficiently into macrophage Raw 264.7 cells in a time- and dose- dependent manner when added exogenously in culture media. Once inside the cells, the transduced PEP-1-PTEN protein was stable for 24 h. Transduced PEP-1-PTEN fusion protein inhibited the LPS-induced cyclooxygenase 2 (COX-2) and iNOS expression levels in a dose-dependent manner. Furthermore, transduced PEP-1-PTEN fusion protein inhibited the activation of NF-kappaB induced by LPS. These results suggest that the PEP-1-PTEN fusion protein can be used in protein therapy for inflammatory disorders.

Lipid metabolites as regulators of airway smooth muscle function

Compelling evidence identifies airway smooth muscle (ASM) not only as a target but also a cellular source for a diverse range of mediators underlying the processes of airway narrowing and airway hyperresponsiveness in diseases such as asthma. These include the growing family of plasma membrane phospholipid-derived polyunsaturated fatty acids broadly characterised by the prostaglandins, leukotrienes, lipoxins, isoprostanes and lysophospholipids. In this review, we describe the enzymatic and non-enzymatic biosynthetic pathways of these lipid mediators and how these are influenced by drug treatment, oxidative stress and airways disease. Additionally, we outline their cognate receptors, many of which are expressed by ASM. We describe potential deleterious and protective roles for these lipid mediators in airway inflammatory and remodelling processes by describing their effects on diverse functions of ASM in asthma that have the potential to contribute to asthma pathogenesis and symptoms. These functions include contractile tone development, cytokine and extracellular matrix production, and cellular proliferation and migration.

Oxidative and nitrative stress in bronchial asthma

There has been a marked increase in the global prevalence, morbidity, and mortality of asthma, and its associated economic burden has also grown over the last 40 years. Approximately 300 million people worldwide currently have asthma, and its prevalence increases by 50% every decade. Airway inflammation is the most proximate cause of the recurrent episodes of airflow limitation in asthma. Recent research has revealed that numerous biologically active proinflammatory mediators are responsible for the pathogenesis of asthma. Among these mediators, there is increasing evidence that endogenous or exogenous reactive oxygen species (ROS) and reactive nitrogen species (RNS) are responsible for the airway inflammation of asthma. Many reports have shown that there is an excessive production of ROS and RNS in the airways of asthmatic individuals compared with healthy subjects. Excessively produced ROS and RNS have been reported to lead to airway inflammation, airway hyper-responsiveness, airway microvascular hyperpermeability, tissue injury, and remodeling in animal models and human studies. Although human lungs have a potent antioxidant system, excessive oxidative and nitrative stress leads to an imbalance of oxidants/antioxidants. This review describes the rapidly accruing data linking oxidative and nitrative events to the pathogenesis of bronchial asthma.

Eosinophils and asthma

Recruitment and activation of eosinophils into the airways of asthma patients is suggested to be a contributing causative agent in the histopathologies and lung dysfunction that are characteristic of asthma. Recent studies in mouse models of asthma and in human patients implicate eosinophils in immune regulation and remodeling in the lung in addition to their hypothesized role as destructive agents. Specifically, eosinophils not only participate in release of granule proteins, lipid mediators, reactive oxygen species, cytokines, and growth factors but also function through complex cell-cell interactions to elicit chronic T helper 2 inflammation in the lung. This review highlights the roles of eosinophils in asthma.

Modulation of airway responses by prostaglandins in young and fully grown rabbits

Maturational changes have been noted in neurally mediated contractile and relaxant responses in airways from New Zealand White rabbits. In this study, we focused on prostaglandins with bronchoprotective properties as potential modulators of airway tone in maturing rabbits. Tracheal rings from 1-, 2-, and 13-wk-old rabbits were assessed for neurally mediated contractile and relaxant responses produced by electrical field stimulation (EFS) of nerves in the presence and absence of the prostaglandin inhibitor, indomethacin (Indo). We also measured EFS-induced release of prostaglandin E(2) (PGE(2)) and the stable metabolite of prostacyclin, 6-keto-prostaglandin F(1alpha) (6-keto-PGF(1alpha)). In the presence of Indo, EFS produced significant increases in contractile responses in segments from 1- and 2-wk-old animals but not in segments from 13-wk adult rabbits. Tracheal rings from 1- and 2-wk-old animals precontracted with neurokinin A (NKA) relaxed 100% in response to EFS when Indo was not in the bath. In rings from 13-wk-old animals, relaxation was 40%. With Indo, relaxation was abolished in 1-wk-old animals and reduced to 30% in the 2- and 13-wk-old groups. Buffer from baths collected after EFS had significant increases in PGE(2) and 6-keto-PGF(1alpha) released from tissues from 1- vs. 2- and 13-wk-old animals. Dose response curves to PGE(2) using tissues precontracted to NKA showed significant increases in relaxant responses in 1- and 2- vs. 13-wk-old rabbits. In rabbit airways, this study demonstrates enhanced modulation of airway tone by PGE(2) and greater release of the bronchoprotective prostaglandins PGE(2) and prostacyclin early in life.

Transduced PEP-1-Grb7 fusion protein suppressed LPS-induced COX-2 expression

Although the incidence and severity of atopic dermatitis (AD) is steadily increasing at an alarming rate, its pathogenic mechanisms remain poorly understood yet. Recently, we found that the expression of Grb7 protein was markedly decreased in AD patients using proteomic analysis. In the present study, human Grb7 gene was fused with PEP-1 peptide in a bacterial expression vector to produce a genetic in-frame PEP-1-Grb7 fusion protein. The expressed and purified PEP-1-Grb7 fusion proteins transduced efficiently into skin cells in a time- and dose-dependent manner when added exogenously in culture media. Once inside the cells, the transduced PEP-1-Grb7 protein was stable for 48 h. In addition, transduced PEP-1-Grb7 fusion protein markedly increased cell viability in macrophage RAW 264.7 cells treated with LPS by inhibition of the COX-2 expression level. These results suggest that the PEP-1-Grb7 fusion protein can be used in protein therapy for inflammatory skin disorders, including AD.

Inhaled iloprost suppresses the cardinal features of asthma via inhibition of airway dendritic cell function

Inhalation of iloprost, a stable prostacyclin (PGI(2)) analog, is a well-accepted and safe treatment for pulmonary arterial hypertension. Although iloprost mainly acts as a vasodilator by binding to the I prostanoid (IP) receptor, recent evidence suggests that signaling via this receptor also has antiinflammatory effects through unclear mechanisms. Here we show in a murine model of asthma that iloprost inhalation suppressed the cardinal features of asthma when given during the priming or challenge phase. As a mechanism of action, iloprost interfered with the function of lung myeloid DCs, critical antigen-presenting cells of the airways. Iloprost treatment inhibited the maturation and migration of lung DCs to the mediastinal LNs, thereby abolishing the induction of an allergen-specific Th2 response in these nodes. The effect of iloprost was DC autonomous, as iloprost-treated DCs no longer induced Th2 differentiation from naive T cells or boosted effector cytokine production in primed Th2 cells. These data should pave the way for a clinical effectiveness study using inhaled iloprost for the treatment of asthma.

New Evidence of H1-Receptor Independent COX-2 Inhibition by Fexofenadine HCl in vitro

BACKGROUND/AIMS

Fexofenadine HCl (FEX) has previously been shown to have anti-inflammatory properties in relieving nasal congestion in allergic rhinitis. The objective of this study was to further elucidate the mechanism of action behind the anti-inflammatory properties of FEX in addition to its H(1)-receptor antagonism.

METHODS

The effects of two antihistamines, FEX and loratadine (LOR), were investigated on cyclooxygenase (COX)-1 and -2 enzymes in vitro. FEX (10(-9)-10(-3) mol/l) and LOR (10(-9)-10(-4) mol/l) were incubated with arachidonic acid in a COX screening assay with either ovine COX-1 or COX-2 or human COX-2. COX-2 enzyme inhibitory activity for the antihistamines was compared with the known selective COX-2 inhibitor DuP-679.

RESULTS

High concentrations of FEX (10(-3) mol/l) significantly inhibited arachidonic acid-mediated ovine COX-1 activity, but low concentrations had no effect. Low concentrations of FEX (10(-8) mol/l) inhibited ovine COX-2 activity, and this inhibition decreased with increasing concentrations. The inhibition of COX-2 activity by FEX was similar to that seen with the selective COX-2 inhibitor, DuP-679. Conversely, LOR inhibited COX-1 activity at low concentrations (10(-8) mol/l), but had little inhibitory effect on COX-1 at high concentrations. LOR (10(-5) mol/l) markedly stimulated COX-2 activity.

CONCLUSION

FEX showed selective arachidonic acid-mediated COX-2 inhibitory enzyme activity, which differed markedly from the COX inhibitory enzyme activity of LOR. This selective COX-2 inhibitor activity by FEX may contribute to its anti-inflammatory properties in relieving nasal congestion in allergic rhinitis.

Cyclooxygenase-1 overexpression decreases Basal airway responsiveness but not allergic inflammation

Pharmacological inhibition or genetic disruption of cyclooxygenase (COX)-1 or COX-2 exacerbates the inflammatory and functional responses of the lung to environmentally relevant stimuli. To further examine the contribution of COX-derived eicosanoids to basal lung function and to allergic lung inflammation, transgenic (Tr) mice were generated in which overexpression of human COX-1 was targeted to airway epithelium. Although no differences in basal respiratory or lung mechanical parameters were observed, COX-1 Tr mice had increased bronchoalveolar lavage fluid PGE(2) content compared with wild-type littermates (23.0 +/- 3.6 vs 8.4 +/- 1.4 pg/ml; p < 0.05) and exhibited decreased airway responsiveness to inhaled methacholine. In an OVA-induced allergic airway inflammation model, comparable up-regulation of COX-2 protein was observed in the lungs of allergic wild-type and COX-1 Tr mice. Furthermore, no genotype differences were observed in allergic mice in total cell number, eosinophil content (70 vs 76% of total cells, respectively), and inflammatory cytokine content of bronchoalveolar lavage fluid, or in airway responsiveness to inhaled methacholine (p > 0.05). To eliminate the presumed confounding effects of COX-2 up-regulation, COX-1 Tr mice were bred into a COX-2 null background. In these mice, the presence of the COX-1 transgene did not alter allergen-induced inflammation but significantly attenuated allergen-induced airway hyperresponsiveness, coincident with reduced airway leukotriene levels. Collectively, these data indicate that COX-1 overexpression attenuates airway responsiveness under basal conditions but does not influence allergic airway inflammation.

Involvement of early growth response gene 1 in the modulation of microsomal prostaglandin E synthase 1 by epigallocatechin gallate in A549 human pulmonary epithelial cells

The prostaglandin E(2) (PGE(2)) can play critical roles in the pulmonary inflammation or carcinogenesis. It is the first investigation of the effect of a green tea polyphenol, (-)-epigallocatechin gallate (EGCG), on the PGE(2)-producing microsomal prostaglandin E synthase 1 (mPGES-1) expression in the lung alveolar type II pneumocytes, A549 cells as an epithelial model. EGCG enhanced cyclooxygenase (COX)-2 and mPGES-1 gene expression as well as PGE(2). Among several tea catechins, EGCG was most effective in inducing mPGES-1 expression. Moreover, even in the cytokine-stimulated cells, mPGES-1 protein was super-induced by EGCG treatment. As signaling mediators in mPGES-1 induction by EGCG, active ERK1/2 MAP kinases and early growth response gene 1 (EGR-1) were increased after exposure to EGCG. Moreover, EGCG stimulated the nuclear translocation of the EGR-1 protein in A549 cells through ERK signaling pathway. Recent studies demonstrate that EGR-1 is a key transcription factor in mPGES-1 gene expression. When blocking the gene expression of EGR-1 with EGR-1 siRNA or ERK inhibitor, EGCG-induced mPGES-1 was suppressed in both cases. mPGES-1 promoter with deleted or point-mutated EGR-1 binding sites showed significantly less response to the EGCG stimulation, which also implicated the importance of EGR-1 binding in promoting mPGES-1 gene expression. Taken all, EGCG was strong inducer of EGR-1 expression and mediated EGR-1 nuclear translocation via ERK signaling pathway in A549 pulmonary epithelial cells. Induced EGR-1 then stimulated the induction of mPGES-1 gene expression and this effect mechanistically can be linked to the pharmacological or toxicological actions after human exposure to green tea catechins.