Novel anti-inflammatory effects of the inhaled corticosteroid fluticasone propionate during lung myofibroblastic differentiation

Effect of transduced mesenchymal stem cells with IL-10 gene on control of allergic asthma

Asthma is an important pulmonary disease associated with T helper lymphocyte (Th)2 dominant immune response, which can initiate allergic and inflammatory reactions. Interleukin (IL)-10 is the main immune suppressor cytokine, and mesenchymal stem cells (MSCs) have an immune-modulatory potential that can be transduced with the expression of the IL-10 gene to control pathophysiology of allergic asthma. Bone marrow's MSCs were isolated and transduced with the expression vector that contains the expressible IL-10 gene. Then, allergic asthma mouse model was produced and treated with manipulated MSCs. Methacholine challenge test; measurement of IL-4, IL-5, IL-8, IL-13, IL-25, and IL-33; and total and ovalbumin (OVA)-specific immunoglobulin (Ig)E levels were done. Hyperplasia of the goblet cell, secretion of mucus, and peribronchiolar and perivascular eosinophilic inflammation were evaluated in lung pathological sections. IL-25, IL-33, and total IgE levels; AHR; eosinophilic inflammation; hyperplasia of the goblet cell; and secretion of mucus could be controlled in M, MV, and MV-10 groups, and the control in the MV-10 group was strong compared to M and MV groups. MSCs have immune-modulatory capacity that can control allergic asthma pathophysiology, and this effect can be strengthened and reinforced by the expression of IL-10 gene.

Biologics and airway remodeling in severe asthma

Asthma is a chronic inflammatory airway disease resulting in airflow obstruction, which in part can become irreversible to conventional therapies, defining the concept of airway remodeling. The introduction of biologics in severe asthma has led in some patients to the complete normalization of previously considered irreversible airflow obstruction. This highlights the need to distinguish a "fixed" airflow obstruction due to structural changes unresponsive to current therapies, from a "reversible" one as demonstrated by lung function normalization during biological therapies not previously obtained even with high-dose systemic glucocorticoids. The mechanisms by which exposure to environmental factors initiates the inflammatory responses that trigger airway remodeling are still incompletely understood. Alarmins represent epithelial-derived cytokines that initiate immunologic events leading to inflammatory airway remodeling. Biological therapies can improve airflow obstruction by addressing these airway inflammatory changes. In addition, biologics might prevent and possibly even revert "fixed" remodeling due to structural changes. Hence, it appears clinically important to separate the therapeutic effects (early and late) of biologics as a new paradigm to evaluate the effects of these drugs and future treatments on airway remodeling in severe asthma.

Protective Effect of Mitogen- and Stress-Activated Protein Kinase on the Rats with Focal Ischemia-Reperfusion Injury

Mitogen- and stress-activated protein kinase (MSK) is a recently identified nuclear cAMP-regulated enhancer B (CREB) and histone H3 kinase that responds to both mitogen- and stress-activated protein kinases. This study was designed to investigate the protective effect of MSK on the rats with focal ischemia-reperfusion injury. The rat model was established by inserting thread into the middle cerebral artery. The protein expression was measured by immunoblotting. The localization of MSK was measured by immunofluorescence assay. Highly-differentiated pheochromocytoma 12 (PC12) is used as a sympathetic neuron-like cell line and treated with glutamate to induce neurotoxicity. MSK was knocked down and overexpressed by siRNA and MSK over-expressing vector, respectively. The cell viability was measured by cell counting kit (CCK-8) assay. The coronal sections were isolated and stained with 2, 3, 5-triphenyltetrazolium chloride (TTC) to determine infarct volume. Finally, astrocytes were separated from cerebral cortexes of normal rats to analyze the effects of MSK on inflammatory response. In the rats with focal ischemia-reperfusion injury, the expression of MSK was reduced, reaching the lowest level at 3 d after ischemia-reperfusion, and then recovered gradually. MSK was found mainly localized in neurons and astrocytes. The expression levels of caspase-3, caspase-8, caspase-9, and INOS showed the opposite trend with respect to MSK. Further analysis showed that overexpression of MSK exerted a protective effect on glutamate-induced neurotoxicity through inhibiting apoptosis of PC12 cells, as well as decreased the infarct size in rat with focal ischemia-reperfusion injury. On the contrary, knockdown of MSK showed opposite results. Finally, MSK suppressed LPS-induced inflammatory response by decreasing the expression of inducible nitric oxide synthase (INOS) and increasing the expression of interleukin-10 (IL-10) in astrocytes from cerebral cortexes of normal rats. In conclusion, MSK exerted a protective effect on rat with focal ischemia-reperfusion injury through its anti-apoptotic effect on neurons and anti-inflammatory effect on astrocytes.

Transcriptomic changes during TGF-β-mediated differentiation of airway fibroblasts to myofibroblasts

Asthma is the most common chronic lung disease in children and young adults worldwide. Airway remodelling (including increased fibroblasts and myofibroblasts in airway walls due to chronic inflammation) differentiates asthmatic from non-asthmatic airways. The increase in airway fibroblasts and myofibroblasts occurs via epithelial to mesenchymal transition (EMT) where epithelial cells lose their tight junctions and are transdifferentiated to mesenchymal cells, with further increases in myofibroblasts occurring via fibroblast-myofibroblast transition (FMT). Transforming growth factor (TGF)-β is the central EMT- and FMT-inducing cytokine. In this study, we have used next generation sequencing to delineate the changes in the transcriptome induced by TGF-β treatment of WI-38 airway fibroblasts in both the short term and after differentiation into myofibroblasts, to gain an understanding of the contribution of TGF-β induced transdifferentiation to the asthmatic phenotype. The data obtained from RNAseq analysis was confirmed by quantitative PCR (qPCR) and protein expression investigated by western blotting. As expected, we found that genes coding for intermediates in the TGF-β signalling pathways (SMADs) were differentially expressed after TGF-β treatment, SMAD2 being upregulated and SMAD3 being downregulated as expected. Further, genes involved in cytoskeletal pathways (FN1, LAMA, ITGB1) were upregulated in myofibroblasts compared to fibroblasts. Importantly, genes that were previously shown to be changed in asthmatic lungs (ADAMTS1, DSP, TIMPs, MMPs) were similarly differentially expressed in myofibroblasts, strongly suggesting that TGF-β mediated differentiation of fibroblasts to myofibroblasts may underlie important changes in the asthmatic airway. We also identified new intermediates of signalling pathways (PKB, PTEN) that are changed in myofibroblasts compared to fibroblasts. We have found a significant number of genes that are altered after TGF-β induced transdifferentiation of WI-38 fibroblasts into myofibroblasts, many of which were expected or predicted. We also identified novel genes and pathways that were affected after TGF-β treatment, suggesting additional pathways are activated during the transition between fibroblasts and myofibroblasts and may contribute to the asthma phenotype.

Asthma therapy and its effect on airway remodelling

Asthma remains a major health problem with significant morbidity, mortality and economic costs. In asthma, airway remodelling, which refers to all the microscopic structural changes seen in the airway tissue, has been recognised for many decades and remains one of the defining characteristics of the disease; however, it is still poorly understood. The detrimental pathophysiological consequences of some features of remodelling, like increased airway smooth muscle mass and subepithelial fibrosis, are well documented. However, whether targeting these by therapy would be beneficial is unknown. Although the prevailing thinking is that remodelling is an abnormal response to persistent airway inflammation, recent evidence, especially from studies of remodelling in asthmatic children, suggests that the two processes occur in parallel. The effects of asthma therapy on airway remodelling have not been studied extensively due to the challenges of obtaining airway tissue in the context of clinical trials. Corticosteroids remain the cornerstone of asthma therapy, and their effects on remodelling have been better studied than other drugs. Bronchial thermoplasty is the only asthma therapy to primarily target remodelling, although how it results in the apparent clinical benefits seen is not exactly clear. In this article we discuss the mechanisms of airway remodelling in asthma and review the effects of conventional and novel asthma therapies on the process.

Oncostatin M modulates fibroblast function via signal transducers and activators of transcription proteins-3

Oncostatin M (OSM), an inflammatory cytokine of the interleukin-6 (IL-6) superfamily, plays a key role in various biological processes such as modulation of extracellular matrix (ECM), cell proliferation, cell survival, and induction of inflammation. It has been reported that OSM was increased in asthma and pulmonary fibrosis, and thus OSM may play a role in airway remodeling and the development of lung parenchymal fibrosis. Recruitment of lung fibroblasts to the sites of airway injury and subsequent differentiation into myofibroblasts is believed to contribute to excess ECM deposition. In the current study, we assessed the ability of OSM to modulate fibroblast collagen gel contraction, migration toward fibronectin, and expression of α-smooth muscle actin (α-SMA). We demonstrated that OSM augments gel contraction, chemotaxis, and α-SMA expression. OSM-augmented fibroblast chemotaxis was mediated by the signal transducer and activator of transcription (STAT3) and p38 mitogen-activated protein kinase, while augmentation on gel contraction and α-SMA expression was mediated by STAT3. Neither transforming growth factor-β1 nor PGE2 was involved in mediating OSM effect on the cells. The Th2 cytokines IL-4 and IL-13, which also are believed to play an important role in promoting lung fibrosis and airway remodeling, act through STAT3, and we demonstrated the potential for additive effects of OSM with IL-4 and IL-13. The present study supports the concept that OSM may contribute to tissue remodeling, which may be additive with IL-4 or IL-13. Blockade of OSM or OSM-mediated STAT3 signaling could be a therapeutic target to regulate lung fibrotic mechanisms.

Fluticasone propionate and Salmeterol combination induces SOCS-3 expression in airway epithelial cells

Fluticasone propionate (FP) and Salmeterol (SAL) are commonly used in combination therapy for patients with Chronic obstructive pulmonary disease (COPD). Clinical studies show that FP/SAL used in combination therapy was found to inhibit airway inflammation in COPD patients. However, the mechanisms associated with FP/SAL induced anti-inflammatory effects were not clear. We have evaluated the effect of FP/SAL and tobacco smoke (TS) on SOCS-3 and interleukine-6 expression in bronchial airway epithelial cells (BAEpCs). Human BAEpCs were exposed to TS and subsequently treated with FP or SAL alone or in combinations in the presence and absence of mitogen activated protein kinase (MAPK) inhibitors for either Erk1/Erk2, or p38 or PI3 kinase. In BAEpCs, TS induced IL-6 expression via ERK1/ERK2 MAPK pathway and FP/SAL inhibited TS mediated IL-6 expression. TS down regulated the SOCS-3 expression via activation of Erk1/Erk2, and p38 MAPK signaling. When TS exposed BAEpCs were treated with FP/SAL SOCS-3 expression was restored. FP/SAL combinations induced significantly higher expression of SOCS-3 in BAEpCs when compared to individual drug. Pretreatment with Ly294002 a PI3 MAPK inhibitor significantly attenuated FP/SAL induced SOCS-3 expression in BAEpCs. Furthermore, FP/SAL blunted TS induced phosphorylation of Erk1/Erk2 and p38 MAPK in BAEpCs. Our study suggests that TS inhibits SOCS-3, combination of FP/SAL has a profound synergistic effect on SOCS-3 induction in BAEpCs and it is dependent on PI3 kinase signaling pathway. SOCS-3 may represent a potential biomarker for understanding the efficacy and a novel anti-inflammatory mechanism of FP/SAL combination therapy in the treatment of COPD.

New perspectives in pharmacological treatment of mild persistent asthma

Until the relationship between symptoms, lung function tests, airway inflammation, airway hyper-responsiveness (AHR), exacerbations and remodelling is clarified, regular treatment seems to enable a greater disease control than on-demand therapy in most patients with mild persistent asthma. Current guideline classification based on disease severity remains a cornerstone in asthma management. However, the heterogeneity of asthma, the growing emphasis on subphenotypes, including molecular phenotypes identified by -omics technologies, and their possible implications in terms of different asthma severity, progression and therapeutic response, are changing current asthma treatment mainly based on disease severity classification to a pharmacological strategy more focused on the individual patient.

Pharmacotherapy of patients with mild persistent asthma: strategies and unresolved issues

In studies comparing regular versus on-demand treatment for patients with mild persistent asthma, on-demand treatment seems to have a similar efficacy on clinical and functional outcomes, but it does not suppress chronic airway inflammation or airway hyper-responsiveness (AHR) associated with asthma. Data on the efficacy of a continuous treatment with inhaled corticosteroids (ICS) in preventing the progression of asthma are conflicting. There is the possibility that patients without a regular treatment with ICS may develop a more severe asthma associated with airway structural changes (remodeling) and a progressive loss of lung function. However, the possible clinical and functional consequences of persistent, not controlled, airway inflammation in patients with asthma have to be established. Assessment of asthma control should include inflammatory outcomes, such as fraction of exhaled nitric oxide and sputum eosinophil counts. Until the relationships between symptoms, lung function tests, AHR, airway inflammation, exacerbations, and airway remodeling are clarified, regular treatment seems to be generally more appropriate than on-demand treatment to warrant a greater control of asthma. Select subgroups of patients with mild asthma who are well controlled by regular treatment might adopt the on-demand treatment plan as an intermediate step toward the suspension of controller medication. The increasing evidence for heterogeneity of asthma, the growing emphasis on asthma subphenotypes, including molecular phenotypes identified by omics technologies, and their possible implications for different asthma severity and progression and therapeutic response, are changing the paradigm of treating patients with asthma only based on classification of their disease severity to a pharmacological strategy more focused on the individual asthmatic patient. Pharmacological treatment of asthma is going toward a personalized approach.

Association between genes encoding components of the IL-10/IL-0 receptor pathway and asthma in children

BACKGROUND

Asthma is a chronic inflammation of the airways associated with recurrent symptoms that range from mild to debilitating. Interleukin-10 (IL-10) is a cytokine that displays pleiotropic effects in asthma and allergy.

OBJECTIVE

To determine whether polymorphisms of IL-10/IL-10R pathway contribute to asthma susceptibility in Egyptian children.

METHODS

The IL-10 (-1082G/A), IL-10R1 (G330R), and signal transducer and activator of transcription 3 (STAT3) rs2293452 single-nucleotide polymorphism (SNP) were genotyped in 110 atopic children with asthma, 110 non-atopic children with asthma, and 110 healthy children. Serum IL-10 and immunoglobulin E (IgE) levels were determined by enzyme-linked immunosorbent assay.

RESULTS

A significant association was observed between the IL-10 polymorphism and asthma in both atopic (P = .03) and non-atopic asthma groups (P = .04). The genotype frequencies of IL-10R1 polymorphisms did not differ between all groups. We identified a significant association between STAT3 polymorphism and asthma susceptibility in atopic asthma (P < .001), whereas no such association was observed in the non-atopic asthma group (P = .9). No evidence of gene interactions was found.

CONCLUSION

Polymorphisms of IL-10 and STAT3 may be useful as a new DNA-based diagnostic biomarker for identifying high-risk children susceptible to asthma.

Section 3. A discussion of flexible dosing and patient-centered therapy: highlights of the asthma summit 2009: beyond the guidelines

Despite positive clinical experience and the published clinical benefits of monotherapy with low-or medium-dose inhaled corticosteroids or combination therapy with ICS + long-acting beta-agonist to treat asthma, many patients remain suboptimally controlled. Alternative approaches are needed, and 3 options that have had some success are: 1) using the patient's level of inflammation by established biomarkers to set treatment; 2) self-management incorporating flexible dosing; and 3) using a single inhaler for rescue and maintenance therapy. Which strategy for which patient depends ultimately on the individual patient's disease burden, life-style, comorbidities, preferences, and his or her ability to self-manage the disease, including assessing symptoms and adhering with therapy.

The role of inhaled corticosteroids in the management of cystic fibrosis

The lung disease of cystic fibrosis (CF) is characterized by a vicious cycle of airway obstruction, chronic bacterial infection, and vigorous inflammation, which ultimately results in bronchiectasis. Recognition that excessive and persistent inflammation is a key factor in lung destruction has prompted investigation into anti-inflammatory therapies. Although effective, the use of systemic corticosteroids has been limited by the unacceptable adverse effect profile. Inhaled corticosteroids (ICS) are a widely prescribed anti-inflammatory agent in CF, likely as a result of clinicians' familiarity with these agents and their excellent safety profile at low doses in asthmatic patients. However, while multiple studies are limited by small sample size and short duration, they consistently failed to demonstrate statistically or clinically significant benefits of ICS use in CF. This review provides an overview of the inflammatory response in CF, the mechanisms of action of corticosteroids, the safety of ICS, and the literature relevant to the use of ICS in CF.

Can inhaled corticosteroids influence the natural history of asthma?

PURPOSE OF REVIEW

Asthma is characterised by variable airflow obstruction, airway inflammation and hyper-responsiveness. Persistent inflammation is thought to lead to 'remodelling' of the airway, which in turn leads to the progressive loss of lung function seen in asthmatics. It would appear logical that anti-inflammatory drugs such as inhaled corticosteroids (ICS) would influence the natural history of asthma by reducing inflammation, subsequent remodelling, and thus preventing the decline in lung function. This review will summarise the effects of ICS on the secondary prevention of asthma, lung function and remodelling.

RECENT FINDINGS

Many published studies show a reduction in airway inflammation, improvement in clinical symptoms and prebronchodilator lung function whilst taking ICS. Few studies, however, examine their effect on the natural history of asthma. Several recent studies have targeted very young children with asthma using ICS, and despite their differing target populations and treatment strategies, have failed to show any difference in lung function. Studies in adults with mild persistent asthma show similar findings. ICS appear to reverse some of the processes involved in airway remodelling, but not all.

SUMMARY

Although ICS are effective in controlling symptoms they do not appear to alter the natural history of asthma.

Anti-proliferative and anti-remodelling effect of beclomethasone dipropionate, formoterol and salbutamol alone or in combination in primary human bronchial fibroblasts

BACKGROUND

Bronchial asthma is characterized by lower airway inflammation and remodelling. Anti-inflammatory treatment with inhaled corticosteroids (ICS) provides the mainstay of asthma therapy together with bronchodilation induced by short- and long-acting inhaled beta(2)-agonists. Lower airway fibroblasts may play a critical role in airway inflammation and remodelling, suggesting that they might represent an important target for the major anti-asthmatic drugs. The aim of our study was to investigate the effects of beclomethasone dipropionate (BDP), salbutamol and formoterol either alone or in combination on in vitro cultures of human bronchial fibroblasts.

METHODS

Fibroblasts were cultured in the presence of pro-inflammatory and proliferative stimuli, BDP, salbutamol and formoterol. The effects of drugs on cell proliferation were ascertained by (3)H-thymidine incorporation. CD90 and CD44 expression were detected by flow cytometry and fibronectin secretion using the enzyme-linked immunosorbent assay technique.

RESULTS

This study showed that BDP alone has significant anti-proliferative effects on lung fibroblasts treated with basic fibroblast growth factor and the combination of BDP with formoterol or salbutamol strengthen these effects. Short-acting beta(2)-agonist (SABA) or long-acting beta(2)-agonist (LABA) by themselves did not show any significant effect on the different cultures. CD44 and CD90 expression and fibronectin production were modulated by pro-inflammatory and proliferative stimuli; the addition of the drugs brought them back near to the basal level.

CONCLUSIONS

From this in vitro study, we can conclude that BDP, when combined with salbutamol or formoterol, exhibits enhanced anti-remodelling activity in bronchial fibroblasts, providing new insights on the additive effects of ICS and SABAs and LABAs for asthma therapy.

Asthma therapy and airway remodeling

Asthma is characterized by variable degrees of chronic inflammation and structural alterations in the airways. The most prominent abnormalities include epithelial denudation, goblet cell metaplasia, subepithelial thickening, increased airway smooth muscle mass, bronchial gland enlargement, angiogenesis, and alterations in extracellular matrix components, involving large and small airways. Chronic inflammation is thought to initiate and perpetuate cycles of tissue injury and repair in asthma, although remodeling may also occur in parallel with inflammation. In the absence of definite evidence on how different remodeling features affect lung function in asthma, the working hypothesis should be that structural alterations can lead to the development of persistent airway hyperresponsiveness and fixed airway obstruction. It is still unanswered whether and when to begin treating patients with asthma to prevent or reverse deleterious remodeling, which components of remodeling to target, and how to monitor remodeling. Consequently, efforts are being made to understand better the effects of conventional anti-inflammatory therapies, such as glucocorticosteroids, on airway structural changes. Animal models, in vitro studies, and some clinical studies have advanced present knowledge on the cellular and molecular pathways involved in airway remodeling. This has encouraged the development of biologicals aimed to target various components of airway remodeling. Progress in this area requires the explicit linking of modern structure-function analysis with innovative biopharmaceutical approaches.

Treating asthma as an inflammatory disease

Asthma is a chronic inflammatory disease involving many different cell types and cellular elements. Evidence suggests that, in the long term, this inflammation leads to remodeling of the airways, airflow obstruction, and the bronchial hyperreactivity symptoms of asthma, and is present even in patients with intermittent disease. Patients with allergic asthma and those with seasonal allergic rhinitis are believed to have minimal persistent inflammation, and the two diseases often occur together. Early intervention with inhaled corticosteroids (ICS) is believed to modify the disease process and may limit long-term remodeling. ICS remain the cornerstone and "gold standard" of treatment for asthma.

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

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

Anti-fibrotic effects of theophylline on lung fibroblasts

Theophylline has been used in the management of bronchial asthma and chronic obstructive pulmonary disease for over 50 years. It has not only a bronchodilating effect, but also an anti-inflammatory one conducive to the inhibition of airway remodeling, including subepithelial fibrosis. To date however, whether theophylline has a direct inhibitory effect on airway fibrosis has not been established. To clarify this question, we examined whether theophylline affected the function of lung fibroblasts. Theophylline suppressed TGF-beta-induced type I collagen (COL1) mRNA expression in lung fibroblasts and also inhibited fibroblast proliferation stimulated by FBS and TGF-beta-induced alpha-SMA protein. A cAMP analog also inhibited TGF-beta-induced COL1 mRNA expression in lung fibroblasts. A PKA inhibitor reduced the inhibitory effect of theophylline on TGF-beta-induced COL1 mRNA expression. These results indicate that theophylline exerts anti-fibrotic effects, at least partly, through the cAMP-PKA pathway.

Lung myofibroblasts as targets of salmeterol and fluticasone propionate: inhibition of alpha-SMA and NF-kappaB

Lung myofibroblasts play a major role in the pathophysiology of asthma, contributing not only to tissue remodelling but also to airway inflammation. Nevertheless, only recently, attention has been focused on these cells as potential targets for anti-allergic drugs. Herein, we analysed the pharmacological response of lung myofibroblasts to beta2-agonists associated or not to inhaled corticosteroids, investigating their effects on (i) the constitutive and transforming growth factor-beta (TGF-beta)-induced expression of alpha-smooth muscle actin (alpha-SMA), the main functional marker of myofibroblastic differentiation and contractility; (ii) isometric contraction and (iii) tumour necrosis factor-alpha (TNF-alpha)-induced nuclear translocation of the pro-inflammatory transcription factor nuclear factor-kappaB (NF-kappaB). The beta2-agonist salmeterol (SMl) has on human lung myofibroblasts new direct anti-contractile/anti-inflammatory effects that are amplified by the combined use of low concentrations of the glucocorticoid fluticasone propionate (FP). First, SMl and/or FP (10(-12) M) inhibits the constitutive and TGF-beta-induced expression of alpha-SMA. Second, the two drugs block the TNF-alpha-induced nuclear translocation of the pro-inflammatory transcription factor NF-kappaB. Finally, SMl decreases TNF- alpha-induced production of the inflammatory cytokine IL-6. The complementary anti-inflammatory/ anti-contractile effects displayed by SMl and FP on lung myofibroblasts in vitro may be related to the improvement in lung function and symptom control obtained in vivo by the early use of low doses of glucocorticoids in combination with long-acting beta2-agonists.

Polymorphisms in signal transducer and activator of transcription 3 and lung function in asthma

Background

Identifying genetic determinants for lung function is important in providing insight into the pathophysiology of asthma. Signal transducer and activator of transcription 3 is a transcription factor latent in the cytoplasm; the gene (STAT3) is activated by a wide range of cytokines, and may play a role in lung development and asthma pathogenesis.

Methods

We genotyped six single nucleotide polymorphisms (SNPs) in the STAT3 gene in a cohort of 401 Caucasian adult asthmatics. The associations between each SNP and forced expiratory volume in 1 second (FEV₁), as a percent of predicted, at the baseline exam were tested using multiple linear regression models. Longitudinal analyses involving repeated measures of FEV₁ were conducted with mixed linear models. Haplotype analyses were conducted using imputed haplotypes. We completed a second association study by genotyping the same six polymorphisms in a cohort of 652 Caucasian children with asthma.

Results

We found that three polymorphisms were significantly associated with baseline FEV₁: homozygotes for the minor alleles of each polymorphism had lower FEV₁ than homozygotes for the major alleles. Moreover, these associations persisted when we performed an analysis on repeated measures of FEV₁ over 8 weeks. A haplotypic analysis based on the six polymorphisms indicated that two haplotypes were associated with baseline FEV₁. Among the childhood asthmatics, one polymorphism was associated with both baseline FEV₁ and the repeated measures of FEV₁ over 4 years.

Conclusion

Our results indicate that genetic variants in STAT3, independent of asthma treatment, are determinants of FEV₁ in both adults and children with asthma, and suggest that STAT3 may participate in inflammatory pathways that have an impact on level of lung function.

Reduced eosinophil pro-fibrogenic effect in severe childhood asthma compared to mild disease: an effect of corticosteroids?

Eosinophils play an important role in inflammation and probably in airway remodeling in asthma. We previously demonstrated that eosinophils from atopic subjects display pro-fibrogenic properties towards lung fibroblasts partially by preformed transforming growth factor-beta (TGF-beta). We hypothesized that the pro-fibrogenic potential of eosinophils is increased in children with life-threatening asthma (LTA). Six children with atopic LTA clinically well-controlled by inhaled corticosteroids (ICS) and 5 children with atopic mild asthma (MA) treated only with inhaled beta(2)-agonists were investigated. The effects of their peripheral blood eosinophils on fibroblast proliferation and lattice contraction were investigated. In addition, TGF-beta(1) and IL-6 eosinophil content were also evaluated. Unexpectedly, eosinophils from LTA increased fibroblast proliferation (5.4-fold) and gel contraction (1.1-fold) significantly less than those from MA. TGF-beta(1) but not IL-6 eosinophil content in LTA was significantly lower than that in MA (2.7-fold). In vitro, addition of dexamethasone on eosinophils stimulated by mast cells resulted in a marked decrease in their TGF-beta(1) content by 1.6-fold. In conclusion, eosinophils from children with ICS-treated LTA displayed significantly less pro-fibrogenic properties than those from MA treated only with beta(2)-agonists. Our data suggest that the pro-fibrogenic effect of eosinophils might be influenced by treatment with ICS in childhood asthma.

Role of tissue stroma in cancer cell invasion

Maintenance of epithelial tissues needs the stroma. When the epithelium changes, the stroma inevitably follows. In cancer, changes in the stroma drive invasion and metastasis, the hallmarks of malignancy. Stromal changes at the invasion front include the appearance of myofibroblasts, cells sharing characteristics with fibroblasts and smooth muscle cells. The main precursors of myofibroblasts are fibroblasts. The transdifferentiation of fibroblasts into myofibroblasts is modulated by cancer cell-derived cytokines, such as transforming growth factor-beta (TGF-beta). TGF-beta causes cancer progression through paracrine and autocrine effects. Paracrine effects of TGF-beta implicate stimulation of angiogenesis, escape from immunosurveillance and recruitment of myofibroblasts. Autocrine effects of TGF-beta in cancer cells with a functional TGF-beta receptor complex may be caused by a convergence between TGF-beta signalling and beta-catenin or activating Ras mutations. Experimental and clinical observations indicate that myofibroblasts produce pro-invasive signals. Such signals may also be implicated in cancer pain. N-Cadherin and its soluble form act as invasion-promoters. N-Cadherin is expressed in invasive cancer cells and in host cells such as myofibroblasts, neurons, smooth muscle cells, and endothelial cells. N-Cadherin-dependent heterotypic contacts may promote matrix invasion, perineural invasion, muscular invasion, and transendothelial migration; the extracellular, the juxtamembrane and the beta-catenin binding domain of N-cadherin are implicated in positive invasion signalling pathways. A better understanding of stromal contributions to cancer progression will likely increase our awareness of the importance of the combinatorial signals that support and promote growth, dedifferentiation, invasion, and ectopic survival and eventually result in the identification of new therapeutics targeting the stroma.