Anti-Tissue Remodeling Effects of Corticosteroids

The profibrotic and senescence phenotype of old lung fibroblasts is reversed or ameliorated by genetic and pharmacological manipulation of Slc7a11 expression

Increased senescence and expression of profibrotic genes in old lung fibroblasts contribute to disrepair responses. We reported that primary lung fibroblasts from old mice have lower expression and activity of the cystine transporter Slc7a11/xCT than cells from young mice, resulting in changes in both the intracellular and extracellular redox environments. This study examines the hypothesis that low Slc7a11 expression in old lung fibroblasts promotes senescence and profibrotic gene expression. The levels of mRNA and protein of Slc7a11, senescence markers, and profibrotic genes were measured in primary fibroblasts from the lungs of old (24 mo) and young (3 mo) mice. In addition, the effects of genetic and pharmacological manipulation of Slc7a11 were investigated. We found that decreased expression of Slc7a11 in old cells was associated with elevated markers of senescence (p21, p16, p53, and β-galactosidase) and increased expression of profibrotic genes (Tgfb1, Smad3, Acta2, Fn1, Col1a1, and Col5a1). Silencing of Slc7a11 in young cells replicated the aging phenotype, whereas overexpression of Slc7a11 in old cells decreased expression of senescence and profibrotic genes. Young cells were induced to express the senescence and profibrotic phenotype by sulfasalazine, a Slc7a11 inhibitor, whereas treatment of old cells with sulforaphane, a Slc7a11 inducer, decreased senescence without affecting profibrotic genes. Like aging cells, idiopathic pulmonary fibrosis fibroblasts show decreased Slc7a11 expression and increased profibrotic markers. In short, old lung fibroblasts manifest a profibrotic and senescence phenotype that is modulated by genetic or pharmacological manipulation of Slc7a11.

Anti-DLL4 ameliorates toluene diisocyanate-induced experimental asthma by inhibiting Th17 response

Toluene diisocyanate (TDI) exhibits an ability to induce steroid insensitive asthma with the involvement of Th17 cells. And emerging evidence has indicated that DLL4 signaling promotes Th17 differentiation through directly upregulating Rorc and IL-17 transcription. Thus, we sought to evaluate the effects of DLL4 blocking antibody on TDI-induced asthma model. Female BALB/c mice were sensitized and challenged with TDI to generate an asthma model. TDI-exposed mice were intraperitoneally injected with anti-DLL4 antibody and then analyzed for various parameters of the airway inflammatory responses. Increased expression of DLL4 in spleen and lung was detected in TDI-exposed mice. Furthermore, anti-DLL4 treatment alleviated TDI-induced airway hyperreactivity (AHR), airway inflammation, airway epithelial injury and airway smooth muscle (ASM) thickening. In the meantime, neutralizing DLL4 also blunted Th17 response via downregulation of ROR-γt expression, while had no effect on Th2 cells and regulatory T (Treg) cells. Overall, anti-DLL4 ameliorated TDI-induced experimental asthma by inhibiting Th17 response, implying the feasibility of targeting DLL4 for therapy of Th17-predominant severe asthma.

Potential biological targets for bioassay development in drug discovery of Sturge-Weber syndrome

Sturge-Weber Syndrome (SWS) is a neurocutaneous disease with clinical manifestations including ocular (glaucoma), cutaneous (port-wine birthmark), neurologic (seizures), and vascular problems. Molecular mechanisms of SWS pathogenesis are initiated by the somatic mutation in GNAQ. Therefore, no definite treatments exist for SWS and treatment options only mitigate the intensity of its clinical manifestations. Biological assay design for drug discovery against this syndrome demands comprehensive knowledge on mechanisms which are involved in its pathogenesis. By analysis of the interrelated molecular targets of SWS, some in vitro bioassay systems can be allotted for drug screening against its progression. Development of such platforms of bioassay can bring along the implementation of high-throughput screening of natural or synthetic compounds in drug discovery programs. Regarding the fact that study of molecular targets and their integration in biological assay design can facilitate the process of effective drug discovery; some potential biological targets and their respective biological assay for SWS drug discovery are propounded in this review. For this purpose, some biological targets for SWS drug discovery such as acetylcholinesterase, alkaline phosphatase, GABAergic receptors, Hypoxia-Inducible Factor (HIF)-1α and 2α are suggested.

The extracellular matrix - the under-recognized element in lung disease?

The lung is composed of airways and lung parenchyma, and the extracellular matrix (ECM) contains the main building blocks of both components. The ECM provides physical support and stability to the lung, and as such it has in the past been regarded as an inert structure. More recent research has provided novel insights revealing that the ECM is also a bioactive environment that orchestrates the cellular responses in its environs. Changes in the ECM in the airway or parenchymal tissues are now recognized in the pathological profiles of many respiratory diseases, including asthma, chronic obstructive pulmonary disease (COPD), and idiopathic pulmonary fibrosis (IPF). Only recently have we begun to investigate whether these ECM changes result from the disease process, or whether they constitute a driving factor that orchestrates the pathological outcomes. This review summarizes our current knowledge of the alterations in the ECM in asthma, COPD, and IPF, and the contributions of these alterations to the pathologies. Emerging data suggest that alterations in the composition, folding or rigidity of ECM proteins may alter the functional responses of cells within their environs, and in so doing change the pathological outcomes. These characteristics highlight potential avenues for targeting lung pathologies in the future. This may ultimately contribute to a better understanding of chronic lung diseases, and novel approaches for finding therapeutic solutions. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Nicotinic acetylcholine receptors are sensors for ethanol in lung fibroblasts

BACKGROUND

Chronic ethanol (EtOH) abuse in humans is known to independently increase the incidence of and mortality due to acute lung injury in at-risk individuals. However, the mechanisms by which EtOH affects lung cells remain incompletely elucidated. In earlier work, we reported that EtOH increased the expression in lung fibroblasts of fibronectin, a matrix glycoprotein implicated in lung injury and repair. This effect was blocked by α-bungarotoxin, a neurotoxin that binds certain nicotinic acetylcholine receptors (nAChRs) thereby implicating nAChRs in this process. Here, we examine the identity of these receptors.

METHODS

Mouse lung fibroblasts were stimulated with EtOH (60 mM) or acetylcholine (100 to 500 μM) and evaluated for the expression of fibronectin and nAChRs. Inhibitors to nAChRs or the antioxidant N-acetyl cysteine (NAC) were used to assess changes in fibronectin expression. Animals exposed to EtOH for up to 6 weeks were used to evaluate the expression of nAChRs in vivo.

RESULTS

First, in EtOH-treated fibroblasts, we observed increased expression of α4 and α9 nAChR subunits. Second, we found that acetylcholine, a natural ligand for nAChRs, mimicked the effects of EtOH. Dihydro-β-erythroidin hydrobromide, a competitive inhibitor of α4 nAChR, blocked the increase in fibronectin expression and cell proliferation. Furthermore, EtOH-induced fibronectin expression was inhibited in cells silenced for α4 nAChR. However, EtOH-treated cells showed increased α-bungarotoxin binding suggesting that α4 nAChR mediates the effects of EtOH via a ligand-independent pathway. Knowing there are several important cysteine residues near the ligand-binding site of α4 nAChRs, we tested the antioxidant NAC and found that it too blocked the induction of fibronectin expression by EtOH. Also, fibroblasts exposed to oxidant stress showed increased fibronectin expression that was blocked with α-bungarotoxin. Finally, we showed increased expression of α4 nAChRs in the lung tissue of mice and rats exposed to EtOH suggesting a role for these receptors in vivo.

CONCLUSIONS

Altogether, our observations suggest that α4 nAChRs serve as sensors for EtOH-induced oxidant stress in lung fibroblasts, thereby revealing a new mechanism by which EtOH may affect lung cells and tissue remodeling and pointing to nAChRs as potential targets for intervention.

In utero nicotine exposure promotes M2 activation in neonatal mouse alveolar macrophages

BACKGROUND

Maternal smoking in utero has been associated with adverse health outcomes including lower respiratory tract infections in infants and children, but the mechanisms underlying these associations continue to be investigated. We hypothesized that nicotine plays a significant role in mediating the effects of maternal tobacco smoke on the function of the neonatal alveolar macrophage (AM), the resident immune cell in the neonatal lung.

METHODS

Primary AMs were isolated at postnatal day 7 from a murine model of in utero nicotine exposure. The murine AM cell line MH-S was used for additional in vitro studies.

RESULTS

In utero nicotine increased interleukin-13 and transforming growth factor-β1 (TGFβ1) in the neonatal lung. Nicotine-exposed AMs demonstrated increased TGFβ1 and increased markers of alternative activation with diminished phagocytic function. However, AMs from mice deficient in the α7 nicotinic acetylcholine receptor (α7 nAChR) had less TGFβ1, reduced alternative activation, and improved phagocytic functioning despite similar in utero nicotine exposure.

CONCLUSION

In utero nicotine exposure, mediated in part via the α7 nAChR, may increase the risk of lower respiratory tract infections in neonates by changing the resting state of AM toward alternative activation. These findings have important implications for immune responses in the nicotine-exposed neonatal lung.

What can in vitro models of COPD tell us?

Chronic obstructive pulmonary disease (COPD) is a progressive lung disease characterised by chronic bronchitis, largely irreversible remodelling of the small airways, and emphysematous destruction of the alveoli. COPD is projected to be the third leading cause of death worldwide by 2020. COPD often results from prolonged exposure to irritants such as cigarette smoke or inhaled particulates. Current pharmacotherapies for COPD are unable to reverse the pathological changes of this disease, and this is partially due to a limited understanding of the intricate mechanisms by which chronic exposure lead to the different pathological components of COPD. This review examines how the mechanisms that underlie various components of COPD can be modelled in vitro, specifically using cigarette smoke extract with cells cultured from primary human lung tissue, and how the effectiveness of current and novel pharmacotherapies on successfully attenuating these pathological changes can also be examined in vitro.

Effect of bone marrow-derived mesenchymal stem cells on endotoxin-induced oxidation of plasma cysteine and glutathione in mice

Bone marrow-derived mesenchymal stem cells (BMDMSC) are emerging as a therapeutic modality in various inflammatory disease states, including acute lung injury (ALI). A hallmark of inflammation, and a consistent observation in patients with ALI, is a perturbation in the systemic redox environment. However, little is known about the effects of BMDMSC on the systemic redox status. The objective of the present study was to determine whether exogenously infused BMDMSC protect against endotoxin-induced oxidation of plasma cysteine (Cys) and glutathione (GSH) redox states. To determine the effect on the redox state if BMDMSC, mice received endotoxin intraperitoneally (1 mg/kg), followed by intravenous infusion of either 5 × 10⁵ BMDMSC or an equal volume of saline solution. Control mice received intraperitoneal endotoxin followed by 5 × 10⁵ lung fibroblasts given intravenously. Cys, cystine (CySS), GSH, and glutathione disulfide (GSSG) concentrations were determined by HPLC. Results showed sequential preservation of plasma Cys and GSH levels in response to BMDMSC infusion. The data show that BMDMSC infusion leads to a more reducing Cys and GSH redox state. The findings are the first to demonstrate that BMDMSC have antioxidant effects in vivo, and add to our understanding of the systemic effects of BMDMSC in lung injury.

Opposite effect of fluticasone and salmeterol on fibronectin and tenascin-C expression in primary human lung fibroblasts

BACKGROUND

Airway remodelling is a key feature of asthma and chronic obstructive pulmonary disease (COPD). The remodelling process involves the deposition of extracellular matrix (ECM) proteins within the airways. Current therapies for asthma and COPD consist of inhaled corticosteroids and long-acting beta(2)-agonists (LABA). However, their effect on airway remodelling is not well understood so far.

OBJECTIVE

In this study we investigated the effect of fluticasone and salmeterol, either alone or in combination, on fibronectin and tenascin-C protein, isoform, and mRNA levels in primary human lung fibroblasts.

METHODS

In our model, fibroblasts cultured in serum-free medium represented a non-inflammatory condition and stimulation with 5% fetal calf serum and/or TGF-beta(1) mimicked a pro-fibrotic environment with activation of tissue repair. Using these two different conditions, the effects of fluticasone and salmeterol on fibronectin and tenascin-C protein and mRNA levels were analysed by immunoblotting and semi-quantitative RT-PCR.

RESULTS

In both conditions, fluticasone increased fibronectin transcript and protein levels, whereas it decreased those of tenascin-C. Salmeterol neither affected fibronectin and tenascin-C synthesis significantly nor did it influence the effect of fluticasone when applied in combination. Furthermore, we found that treatment with fluticasone had an opposite effect on extra domain A and B containing fibronectin isoforms generated by alternative splicing compared with total fibronectin transcript levels, whereas tenascin-C isoforms were not differently modulated by fluticasone.

CONCLUSIONS

Our results indicate that standard therapies for inflammatory lung disorders influence ECM protein composition and relative expression levels. In contrast to corticosteroids, LABA did not significantly alter the expression of tenascin-C and fibronectin in cultures of primary human lung fibroblasts.

The effect of asthma therapeutics on signalling and transcriptional regulation of airway smooth muscle function

SCOPE OF THE REVIEW

Our knowledge of the multifunctional nature of airway smooth muscle (ASM) has expanded rapidly in the last decade, but the underlying molecular mechanisms and how current therapies for obstructive airway diseases, such as asthma and chronic obstructive pulmonary disease (COPD), affect these are still being elucidated. Our current knowledge has built on the pharmacology of human ASM contraction and relaxation established prior to that and which is reviewed in detail elsewhere in this issue. The advent of methods to isolate and culture ASM cells, especially human ASM cells, has made it possible to study how they may contribute to airway remodelling through their synthetic, proliferative, and migratory capacities. Now the underlying molecular mechanisms of ASM growth factor secretion, extracellular matrix (ECM) production, proliferation and migration, as well as contraction and relaxation, are being determined. A complex network of signalling pathways leading to gene transcription in ASM cells permits this functional plasticity in healthy and diseased airways. This review is an overview of the effects of current therapies, and some of those in development, on key signalling pathways and transcription factors involved in these ASM functions.

Oxidation of extracellular cysteine/cystine redox state in bleomycin-induced lung fibrosis

Several lines of evidence indicate that depletion of glutathione (GSH), a critical thiol antioxidant, is associated with the pathogenesis of idiopathic pulmonary fibrosis (IPF). However, GSH synthesis depends on the amino acid cysteine (Cys), and relatively little is known about the regulation of Cys in fibrosis. Cys and its disulfide, cystine (CySS), constitute the most abundant low-molecular weight thiol/disulfide redox couple in the plasma, and the Cys/CySS redox state (E(h) Cys/CySS) is oxidized in association with age and smoking, known risk factors for IPF. Furthermore, oxidized E(h) Cys/CySS in the culture media of lung fibroblasts stimulates proliferation and expression of transitional matrix components. The present study was undertaken to determine whether bleomycin-induced lung fibrosis is associated with a decrease in Cys and/or an oxidation of the Cys/CySS redox state and to determine whether these changes were associated with changes in E(h) GSH/glutathione disulfide (GSSG). We observed distinct effects on plasma GSH and Cys redox systems during the progression of bleomycin-induced lung injury. Plasma E(h) GSH/GSSG was selectively oxidized during the proinflammatory phase, whereas oxidation of E(h) Cys/CySS occurred at the fibrotic phase. In the epithelial lining fluid, oxidation of E(h) Cys/CySS was due to decreased food intake. Thus the data show that decreased precursor availability and enhanced oxidation of Cys each contribute to the oxidation of extracellular Cys/CySS redox state in bleomycin-induced lung fibrosis.

Epithelial-derived fibronectin expression, signaling, and function in intestinal inflammation

Fibronectin (FN) is a multifunctional extracellular matrix protein that plays an important role in cell proliferation, adhesion, and migration. FN expression or its role in colitis is not known. The goal of this study is to characterize FN expression, regulation, and role during intestinal inflammation. Wild-type and transgenic mice expressing luciferase under the control of the human FN promoter, given water or 3% dextran sodium sulfate, were used as animal models of colitis. The Caco2-BBE model intestinal epithelial cell line was used for in vitro studies. FN protein is abundantly expressed by surface epithelial cells in the normal colon. Immunohistochemistry and luciferase assay in mice expressing the FN promoter linked to luciferase demonstrated that FN synthesis was up-regulated during colitis, during both the acute phase and the healing phase. In vitro experiments demonstrated that FN increased the expression of the FN integrin receptor alpha5beta1 in a dose- and time-dependent manner. FN also induced the expression and activation of NF-kappaB. Further, FN potentiated Caco2-BBE cell attachment and wound healing, which was inhibited by RGD peptide as well as NF-kappaB inhibitors MG-132 and 1-pyrrolidinecarbodithioic acid, ammonium salt. In conclusion, FN is abundantly expressed and synthesized by colonic epithelial cells. FN is transcriptionally up-regulated in epithelial cells during both the dextran sodium sulfate-induced colitic and the recovery phase. FN enhances cell attachment and wound healing, which is dependent on binding to the integrin receptor and the NF-kappaB signaling. Together our data show that epithelial-derived FN potentiates cell attachment and wound healing through epithelial-matrix interactions and that FN expression may have important implications for maintaining normal epithelial integrity as well as regulating epithelial response to injury during colitis.

Extracellular cysteine/cystine redox potential controls lung fibroblast proliferation and matrix expression through upregulation of transforming growth factor-beta

Oxidant stress has been implicated in the pathogenesis of chronic lung disorders like idiopathic pulmonary fibrosis. However, mechanisms that link oxidant stress to fibrogenesis remain partially elucidated. Emerging data suggest an important role for the extracellular thiol/disulfide redox environment. The cysteine (Cys)/cystine (CySS) redox couple represents the predominant low-molecular-weight thiol/disulfide pool found in plasma and is sensitive to aging, smoking, and other host factors. We hypothesized that an oxidized extracellular Cys/CySS redox potential (E(h) Cys/CySS) affects lung fibroblasts by inducing intracellular signals that stimulate proliferation and matrix expression. We tested this hypothesis in primary murine lung fibroblasts and found that an oxidized E(h) Cys/CySS (-46 mV) stimulated lung fibroblast proliferation. Furthermore, it stimulated their expression of fibronectin, a matrix glycoprotein highly expressed in fibrotic lung diseases and implicated in lung injury. This stimulatory effect was dependent on protein kinase C activation. Oxidant stress also increased the phosphorylation of cAMP response element binding protein, a transcription factor known for its ability to stimulate fibronectin expression, and increased the expression of mRNAs and proteins coding for the transcription factors nuclear factor (NF)-kappaB and mothers against decapentaplegic homolog 3. Fibroblasts cultured in normal (-80 mV) or reduced (-131 mV) E(h) Cys/CySS showed less induction. Furthermore, fibronectin expression in response to an oxidized E(h) Cys/CySS was associated with expression of transforming growth factor-beta1 (TGF-beta1) and was inhibited by an anti-TGF-beta1 antibody and SB-431542, a TGF-beta1 receptor inhibitor. These studies suggest that extracellular oxidant stress activates redox-sensitive pathways that stimulate lung fibroblast proliferation and matrix expression through upregulation of TGF-beta1.

Variable p-CREB expression depicts different asthma phenotypes

BACKGROUND

Chromatin modification may play a role in inflammatory gene regulation in asthma. Cyclic adenosine mono-phosphate response element-binding protein (CREB), with the specific co-activator, the CREB-binding protein (CBP), contributes to the acetylation of chromatin and to the transcription of pro-inflammatory genes.

OBJECTIVES

To evaluate the expression of CBP and of phospho-CREB (p-CREB) in bronchial biopsies and in peripheral blood mononuclear cells (PBMC) of controls (C), untreated (UA), inhaled steroid treated (ICS) and steroid-dependent asthmatic (SDA) patients.

METHODS

We used immunohistochemistry in bronchial biopsies and western blot analysis and immunocytochemistry in PBMC.

RESULTS

Cyclic adenosine mono-phosphate response element-binding protein expression, in the epithelium was similar in all groups, while p-CREB expression was increased in UA and in SDA in comparison with ICS and C subjects (C vs UA P = 0.002, C vs SDA P = 0.007), (ICS vs SDA P = 0.005), (ICS vs UA P = 0.001). Interestingly, also in the submucosa, p-CREB was increased in UA and SDA in comparison with ICS and C subjects (C vs UA P = 0.0004) (C vs SDA P < 0.0001) (ICS vs UA P = 0.002) (ICS vs SDA P < 0.0001) and positively correlated with leukocyte infiltration within the bronchi (CD45RB+ cells). Similar results were obtained with PBMC isolated from the same patient groups. Incubation of PBMC in vitro, with fluticasone propionate, decreased the p-CREB expression induced by cytokine activation (interferon-gamma, tumor necrosis factor-alpha).

CONCLUSIONS

This study demonstrates that the expression of p-CREB is related, in asthma, to the persistent inflammation according to the disease severity. p-CREB expression can be modulated by glucocorticoids in responsive patients.

Increased fibronectin expression in lung in the setting of chronic alcohol abuse

RATIONALE

The incidence and severity of the acute respiratory distress syndrome (ARDS) is increased in individuals who abuse alcohol. One possible mechanism by which alcohol increases susceptibility to acute lung injury is through alterations in alveolar macrophage function and induction of tissue remodeling activity. Our objective was to determine whether alcohol abuse, independent of other comorbidities, alters fibronectin and metalloproteinase gene expression in alveolar macrophages and in epithelial lining fluid (ELF) of the lung.

METHODS

Otherwise healthy subjects with alcohol abuse (n=21) and smoking-matched controls (n=17) underwent bronchoalveolar lavage. Alveolar macrophage fibronectin and matrix metalloproteinase (MMP) mRNA expression were measured via reverse transcription-polymerase chain reaction. The supernatant from cultured alveolar macrophages and lung ELF were tested for their ability to induce fibronectin and MMP-9 gene transcription in cell-based assays.

RESULTS

Alveolar macrophages from subjects with alcohol abuse demonstrated increased fibronectin mRNA expression (p<0.001), and their ELF also elicited more fibronectin gene transcription in lung fibroblasts compared with controls (p<0.001). In contrast, alveolar macrophages from subjects with alcohol abuse had decreased MMP-9 and MMP-2 mRNA expression (p<0.03 and p<0.005, respectively). Similarly, the supernatant (p<0.001) and ELF (p<0.01) from these subjects induced less MMP-9 gene transcription in THP-1 cells.

DISCUSSION

Alcohol abuse is associated with increased fibronectin mRNA expression in alveolar macrophages and increased fibronectin-inducing activity in the ELF. This appears to be a specific effect as other tissue remodeling genes, such as MMPs, were not equally affected. These findings suggest activation of tissue remodeling that may contribute to the increased susceptibility for the ARDS observed in alcoholism.

Nasal carriage of Staphylococcus aureus in children with allergic rhinitis and the effect of intranasal fluticasone propionate treatment on carriage status

OBJECTIVE

The aim of this study is to determine the rate of nasal carriage of Staphylococcus aureus (NCSA) in children with allergic rhinitis (AR) and to determine the effect of intranasal fluticasone propionate spray on the NCSA.

PATIENTS AND METHODS

Nasal swabs were taken from the children admitted to general pediatrics and pediatric pulmonology clinics. Patients were divided into two groups according to the presence or absence of AR. Diagnosis of AR was based on the patient's symptoms. Nasal swabs were taken from AR patients before and after the treatment with intranasal fluticasone propionate, and from the control group at the beginning and after 2 months.

RESULTS

Whole NCSA rate was 17.9%; it was 21.4% for AR patients and 15.9% for control group, respectively (p>0.05). Treatment with intranasal fluticasone propionate spray did not influence NCSA in AR patients.

CONCLUSION

It seemed that NCSA was not increased in children with AR and treatment with intranasal fluticasone propionate spray did not change NCSA in AR patients. It is obvious that better understanding of the factors affecting the acquisition and loss of NCSA might increase our knowledge about the relationship between NCSA, allergic airway diseases and their treatments.

The effect of triamcinolone acetonide aqueous nasal spray on the nasal carriage of Staphylococcus aureus

BACKGROUND

In this study we aimed to investigate the effect of triamcinolone acetonide aqueous (TAA) intranasal spray that was used for 2 months to treat allergic rhinitis (AR) on the nasal carriage of Staphylococcus aureus (NCSA).

METHODS

A total of 125 adult AR patients (study group) and 133 healthy individuals (control group) were enrolled for the study. The subjects were diagnosed with AR after a detailed history, physical examination, and prick testing. The AR subjects were administered TAA in a daily dosage of a 220-microg intranasal route. Nasal cultures were obtained on the 1st (baseline), 55th, and 60th days, and the subjects in the last two cultures of whom S. aureus was detected were accepted as NCSA.

RESULTS

After all exclusion criteria were used, 110 AR and 114 control group subjects were enrolled in the study. Based on the culture results that were obtained on the 55th and 60th days, 10 (%9.1) patients from the study group and 18 (%15.7) individuals from the control group were defined to be NCSA (p > 0.05).

CONCLUSION

We conclude that the use of TAA treatment for AR does not increase the prevalence of NCSA. However, additional studies with a larger series are required to explain the effects of steroids on nasal colonization of S. aureus.

Adenosine induces fibronectin expression in lung epithelial cells: implications for airway remodeling

Adenosine is an extracellular nucleoside that is elevated in tissues during hypoxia and ischemia reperfusion and has been implicated in asthma and other lung disorders. There, adenosine is considered an important modulator of physiological functions and inflammation, but its effects on matrix expression and turnover during tissue remodeling are unknown. We examined the effects of adenosine on lung epithelial cells with particular attention to the expression of fibronectin, a matrix glycoprotein highly expressed in injured tissues that has been implicated in wound healing. In A549 lung epithelial cells, we found that adenosine induced expression of fibronectin mRNA and protein in a dose- and time-dependent manner and found that the stimulatory effect of adenosine was inhibited by specific adenosine receptor antagonists. Adenosine stimulation was associated with increased levels of intracellular cAMP and with phosphorylation and DNA binding of the cAMP response element binding protein (CREB), known for its ability to stimulate fibronectin gene transcription. To confirm the latter, A549 cells were transfected with a DNA construct containing the human fibronectin promoter connected to a luciferase reporter gene. Adenosine stimulated transcription of the gene, and this effect was blocked by inhibitors of protein kinase activation. Finally, we tested primary lung fibroblasts and primary alveolar epithelial type II cells and found increased fibronectin expression in response to adenosine. Overall, our observations suggest that adenosine might modulate tissue remodeling by stimulating fibronectin expression in lung epithelial cells through induction of purinergic receptor-mediated signals that target CREB phosphorylation and stimulate fibronectin gene transcription.

Ethanol stimulates the expression of fibronectin in lung fibroblasts via kinase-dependent signals that activate CREB

Ethanol renders the lung susceptible to acute lung injury in the setting of insults such as sepsis. The mechanisms mediating this effect are unknown, but activation of tissue remodeling is considered key to this process. We found that chronic ethanol ingestion in rats increased the expression of fibronectin, a matrix glycoprotein implicated in acute lung injury. In cultured NIH/3T3 cells and in primary rat and mouse lung fibroblasts, ethanol induced fibronectin mRNA and protein expression in a dose- and time-dependent fashion. The effect of ethanol was prevented by inhibitors of protein kinase C and mitogen-activated protein kinases and was associated with the phosphorylation and increased DNA binding of the transcription factor cAMP response element binding protein, followed by increased transcription of the fibronectin gene. Fibroblasts were found to express alpha(7) nicotinic acetylcholine receptor (nAChR), and ethanol induction of fibronectin was abolished by alpha-bungarotoxin and methyllcaconitine, inhibitors of alpha(7) nAChRs. However, ethanol was able to induce fibronectin mRNA and protein in primary lung fibroblasts isolated from alpha(7) nAChR knockout mice. The ethanol-induced fibronectin response was dependent on ethanol metabolism since 4-methylpyrazole, an inhibitor of alcohol dehydrogenase, abolished the effect and acetaldehyde induced it. These observations suggest that ethanol or ethanol metabolites stimulate lung fibroblasts to produce fibronectin by inducing specific signals transmitted via nAChRs independent of the alpha(7-)subunit, and this might represent a mechanism by which ethanol renders the lung susceptible to acute lung injury.