Inhaled corticosteroid reduced lamina reticularis of the basement membrane by modulation of insulin-like growth factor (IGF)-I expression in bronchial asthma

The New Paradigm: The Role of Proteins and Triggers in the Evolution of Allergic Asthma

Epithelial barrier damage plays a central role in the development and maintenance of allergic inflammation. Rises in the epithelial barrier permeability of airways alter tissue homeostasis and allow the penetration of allergens and other external agents. Different factors contribute to barrier impairment, such as eosinophilic infiltration and allergen protease action-eosinophilic cationic proteins' effects and allergens' proteolytic activity both contribute significantly to epithelial damage. In the airways, allergen proteases degrade the epithelial junctional proteins, allowing allergen penetration and its uptake by dendritic cells. This increase in allergen-immune system interaction induces the release of alarmins and the activation of type 2 inflammatory pathways, causing or worsening the main symptoms at the skin, bowel, and respiratory levels. We aim to highlight the molecular mechanisms underlying allergenic protease-induced epithelial barrier damage and the role of immune response in allergic asthma onset, maintenance, and progression. Moreover, we will explore potential clinical and radiological biomarkers of airway remodeling in allergic asthma patients.

Circulating insulin-like growth factor-1 and risk of lung diseases: A Mendelian randomization analysis

BACKGROUND

Insulin-like growth factor-1 (IGF-1) display a vital role in in the pathogenesis of lung diseases, however, the relationship between circulating IGF-1 and lung disease remains unclear.

METHODS

Single nucleotide polymorphisms (SNPs) associated with the serum levels of IGF-1 and the outcomes data of lung diseases including asthma, chronic obstructive pulmonary disease (COPD), lung cancer and idiopathic pulmonary fibrosis (IPF) were screened from the public genome-wide association studies (GWAS). Two-sample Mendelian randomization (MR) analysis was then performed to assess the independent impact of IGF-1 exposure on these lung diseases.

RESULTS

Totally, 416 SNPs related to circulating IGF-1 levels among 358,072 participants in UK Biobank. According to a primary casual effects model with MR analyses by the inverse variance weighted (IVW) method, the circulating IGF-1 was demonstrated a significantly related with the risk of asthma (OR, 0.992; 95% CI, 0.985-0.999, P=0.0324), while circulating IGF-1 showed no significant correlation with CODP (OR, 1.000; 95% CI, 0.999-1.001, P=0.758), lung cancer (OR, 0.979, 95% CI, 0.849-1.129, P=0.773), as well as IPIGFF (OR, 1.100, 95% CI, 0.794-1.525, P=0.568).

CONCLUSION

The present study demonstrated that circulating IGF-1 may be causally related to lower risk of asthma.

Translational Analysis of Moderate to Severe Asthma GWAS Signals Into Candidate Causal Genes and Their Functional, Tissue-Dependent and Disease-Related Associations

Asthma affects more than 300 million people globally and is both under diagnosed and under treated. The most recent and largest genome-wide association study investigating moderate to severe asthma to date was carried out in 2019 and identified 25 independent signals. However, as new and in-depth downstream databases become available, the translational analysis of these signals into target genes and pathways is timely. In this study, unique (U-BIOPRED) and publicly available datasets (HaploReg, Open Target Genetics and GTEx) were investigated for the 25 GWAS signals to identify 37 candidate causal genes. Additional traits associated with these signals were identified through PheWAS using the UK Biobank resource, with asthma and eosinophilic traits amongst the strongest associated. Gene expression omnibus dataset examination identified 13 candidate genes with altered expression profiles in the airways and blood of asthmatic subjects, including MUC5AC and STAT6. Gene expression analysis through publicly available datasets highlighted lung tissue cell specific expression, with both MUC5AC and SLC22A4 genes showing enriched expression in ciliated cells. Gene enrichment pathway and interaction analysis highlighted the dominance of the HLA-DQA1/A2/B1/B2 gene cluster across many immunological diseases including asthma, type I diabetes, and rheumatoid arthritis. Interaction and prediction analyses found IL33 and IL18R1 to be key co-localization partners for other genes, predicted that CD274 forms co-expression relationships with 13 other genes, including the HLA-DQA1/A2/B1/B2 gene cluster and that MUC5AC and IL37 are co-expressed. Drug interaction analysis revealed that 11 of the candidate genes have an interaction with available therapeutics. This study provides significant insight into these GWAS signals in the context of cell expression, function, and disease relationship with the view of informing future research and drug development efforts for moderate-severe asthma.

Evaluation serum levels of Insulin Growth Factor-1 (IGF-1) and its association with clinical parameters in severe COVID-19

Background

Severe coronavirus disease-2019 (COVID-19) is associated with dysregulated immune response and extreme inflammatory injury. Considering the role of insulin growth factor-1 (IGF-1) in immune-mediated and inflammatory reactions, this study was conducted to investigate the IGF-1 contribution to the pathogenesis of severe form of COVID-19.

Material and methods

Sixty-two patients with severe COVID-19 and 52 healthy subjects were enrolled in this study. The serum levels of IGF-1 were measured using a solid-phase enzyme-linked chemiluminescent immunoassay on an Immulite 2000 system (Siemens Healthcare Diagnostics.

Result

The serum levels of IGF-1 had no significant difference in COVID-19 patients compared to the healthy subjects (p = 0.359). There was a positive correlation between IGF-1 and age in the severe COVID-19 patients, while a negative correlation was observed for the serum levels of IGF-1 and age in the control group (r = 0.364, p = 0.036, r = − 0.536, p = 0.001, respectively). Moreover, IGF-1 was remarkably associated with hypertension, neurogenic disease, shock, and nausea in patients with the severe form of COVID-19 (p = 0.031, p = 0.044, p = 0.01, p = 0.03, respectively).

Conclusion

Our results pointed to the complex role of IGF-1 in the severe form of COVID-19, and its association with clinical parameters, and some risk factors in the severe form of COVID-19.

Circular RNA ERBB2 Contributes to Proliferation and Migration of Airway Smooth Muscle Cells via miR-98-5p/IGF1R Signaling in Asthma

Background

Asthma belongs to chronic inflammatory respiratory diseases characterized by airway inflammation and remodeling. Circular RNAs (circRNAs) are promising therapeutic targets for various diseases, including asthma. In this work, we aim to investigate the role of circular RNA Erb-B2 receptor tyrosine kinase 2 (circERBB2) during progression of asthma.

Methods

Human airway smooth muscle cells (ASMCs) were treated with platelet-derived growth factor BB (PDGF-BB) to mimic cell remodeling. The expression of circERBB2, microRNA-98-5p (miR-98-5p), and insulin-like growth factor 1 receptor (IGF1R) was measured by qRT-PCR. Cell proliferation, migration and apoptosis were determined by cell counting-8 (CCK-8), transwell, and flow cytometry. Protein levels of PCNA, MMP-9, IGF1R were evaluated using Western blotting. The levels of tumor necrosis factor‐α (TNF‐α), interleukin‐1β (IL‐1β), and IL‐6 were detected by enzyme‐linked immunosorbent assay (ELISA). Luciferase reporter gene experiment was adopted to evaluate the targeting relationship between miR-98-5p with circERBB2 and IGF1R. Interaction between RNAs was determined by RNA pulldown and RIP assay.

Results

The depletion of circERBB2 attenuated the proliferation, migration, and levels of inflammatory factors induced by PDGF-BB and cell apoptosis. CircERBB2 was identified to directly interact with miR-98-5p, and overexpression of miR-98-5p abolished the function of circERBB2 on PDGF-BB-stimulated ASMCs. IGF1R was identified as a target of miR-98-5p, and knockdown of IGF1R relieved the PDGF-BB-induced ASMCs proliferation and migration.

Conclusion

Our work disclosed that knockdown of circERBB2 suppressed PDGF-BB-caused proliferation, migration and inflammatory response of ASMCs, through regulating miR-98-5p/IGF1R signaling, presented circERBB2 as a promising therapeutic target for asthma.

A randomized, placebo-controlled trial evaluating effects of lebrikizumab on airway eosinophilic inflammation and remodelling in uncontrolled asthma (CLAVIER)

BACKGROUND

The anti-interleukin 13 (IL-13) monoclonal antibody lebrikizumab improves lung function in patients with moderate-to-severe uncontrolled asthma, but its effects on airway inflammation and remodelling are unknown. CLAVIER was designed to assess lebrikizumab's effect on eosinophilic inflammation and remodelling.

OBJECTIVE

To report safety and efficacy results from enrolled participants with available data from CLAVIER.

METHODS

We performed bronchoscopy on patients with uncontrolled asthma before and after 12 weeks of randomized double-blinded treatment with lebrikizumab (n = 31) or placebo (n = 33). The pre-specified primary end-point was relative change in airway subepithelial eosinophils per mm2 of basement membrane (cells/mm2 ). Pre-specified secondary and exploratory outcomes included change in IL-13-associated biomarkers and measures of airway remodelling.

RESULTS

There was a baseline imbalance in tissue eosinophils and high variability between treatment groups. There was no discernible change in adjusted mean subepithelial eosinophils/mm2 in response to lebrikizumab (95% CI, -82.5%, 97.5%). As previously observed, FEV1 increased after lebrikizumab treatment. Moreover, subepithelial collagen thickness decreased 21.5% after lebrikizumab treatment (95% CI, -32.9%, -10.2%), and fractional exhaled nitric oxide, CCL26 and SERPINB2 mRNA expression in bronchial tissues also reduced. Lebrikizumab was well tolerated, with a safety profile consistent with other lebrikizumab asthma studies.

CONCLUSIONS & CLINICAL RELEVANCE

We did not observe reduced tissue eosinophil numbers in association with lebrikizumab treatment. However, in pre-specified exploratory analyses, lebrikizumab treatment was associated with reduced degree of subepithelial fibrosis, a feature of airway remodelling, as well as improved lung function and reduced key pharmacodynamic biomarkers in bronchial tissues. These results reinforce the importance of IL-13 in airway pathobiology and suggest that neutralization of IL-13 may reduce asthmatic airway remodelling.

CLINICAL TRIAL REGISTRATION

NCT02099656.

Alveolar Epithelial Cells Promote IGF-1 Production by Alveolar Macrophages Through TGF-β to Suppress Endogenous Inflammatory Signals

To maintain alveolar gas exchange, the alveolar surface has to limit unnecessary inflammatory responses. This involves crosstalk between alveolar epithelial cells (AECs) and alveolar macrophages (AMs) in response to damaging factors. We recently showed that insulin-like growth factor (IGF)-1 regulates the phagocytosis of AECs. AMs secrete IGF-1 into the bronchoalveolar lavage fluid (BALF) in response to inflammatory stimuli. However, whether AECs regulate the production of IGF-1 by AMs in response to inflammatory signals remains unclear, as well as the role of IGF-1 in controlling the alveolar balance in the crosstalk between AMs and AECs under inflammatory conditions. In this study, we demonstrated that IGF-1 was upregulated in BALF and lung tissues of acute lung injury (ALI) mice, and that the increased IGF-1 was mainly derived from AMs. In vitro experiments showed that the production and secretion of IGF-1 by AMs as well as the expression of TGF-β were increased in LPS-stimulated AEC-conditioned medium (AEC-CM). Pharmacological blocking of TGF-β in AECs and addition of TGF-β neutralizing antibody to AEC-CM suggested that this AEC-derived cytokine mediates the increased production and secretion of IGF-1 from AMs. Blocking TGF-β synthesis or treatment with TGF-β neutralizing antibody attenuated the increase of IGF-1 in BALF in ALI mice. TGF-β induced the production of IGF-1 by AMs through the PI3K/Akt signaling pathway. IGF-1 prevented LPS-induced p38 MAPK activation and the expression of the inflammatory factors MCP-1, TNF-α, and IL-1β in AECs. However, IGF-1 upregulated PPARγ to increase the phagocytosis of apoptotic cells by AECs. Intratracheal instillation of IGF-1 decreased the number of polymorphonuclear neutrophils in BALF of ALI model mice, reduced alveolar congestion and edema, and suppressed inflammatory cell infiltration in lung tissues. These results elucidated a mechanism by which AECs used TGF-β to regulate IGF-1 production from AMs to attenuate endogenous inflammatory signals during alveolar inflammation.

Leonurus sibiricus root extracts decrease airway remodeling markers expression in fibroblasts

Bronchial asthma is believed to be provoked by the interaction between airway inflammation and remodeling. Airway remodeling is a complex and poorly understood process, and controlling it appears key for halting the progression of asthma and other obstructive lung diseases. Plants synthesize a number of valuable compounds as constitutive products and as secondary metabolites, many of which have curative properties. The aim of this study was to evaluate the anti-remodeling properties of extracts from transformed and transgenic Leonurus sibiricus roots with transformed L. sibiricus roots extract with transcriptional factor AtPAP1 overexpression (AtPAP1). Two fibroblast cell lines, Wistar Institute-38 (WI-38) and human fetal lung fibroblast (HFL1), were incubated with extracts from transformed L. sibiricus roots (TR) and roots with transcriptional factor AtPAP1 over-expression (AtPAP1 TR). Additionally, remodeling conditions were induced in the cultures with rhinovirus 16 (HRV16). The expressions of metalloproteinase 9 (MMP)-9, tissue inhibitor of metalloproteinases 1 (TIMP-1), arginase I and transforming growth factor (TGF)-β were determined by quantitative polymerase chain reaction (qPCR) and immunoblotting methods. AtPAP1 TR decreased arginase I and MMP-9 expression with no effect on TIMP-1 or TGF-β mRNA expression. This extract also inhibited HRV16-induced expression of arginase I, MMP-9 and TGF-β in both cell lines (P < 0·05) Our study shows for the first time to our knowledge, that transformed AtPAP1 TR extract from L. sibiricus root may affect the remodeling process. Its effect can be attributed an increased amount of phenolic acids such as: chlorogenic acid, caffeic acid or ferulic acid and demonstrates the value of biotechnology in medicinal research.

miR-223: A Key Regulator in the Innate Immune Response in Asthma and COPD

Asthma and Chronic Obstructive Pulmonary Disease (COPD) are chronic obstructive respiratory diseases characterized by airway obstruction, inflammation, and remodeling. Recent findings indicate the importance of microRNAs (miRNAs) in the regulation of pathological processes involved in both diseases. MiRNAs have been implicated in a wide array of biological processes, such as inflammation, cell proliferation, differentiation, and death. MiR-223 is one of the miRNAs that is thought to play a role in obstructive lung disease as altered expression levels have been observed in both asthma and COPD. MiR-223 is a hematopoietic cell–derived miRNA that plays a role in regulation of monocyte-macrophage differentiation, neutrophil recruitment, and pro-inflammatory responses and that can be transferred to non-myeloid cells via extracellular vesicles or lipoproteins. In this translational review, we highlight the role of miR-223 in obstructive respiratory diseases, focusing on expression data in clinical samples of asthma and COPD, in vivo experiments in mouse models and in vitro functional studies. Furthermore, we provide an overview of the mechanisms by which miR-223 regulates gene expression. We specifically focus on immune cell development and activation and involvement in immune responses, which are important in asthma and COPD. Collectively, this review demonstrates the importance of miR-223 in obstructive respiratory diseases and explores its therapeutic potential in the pathogenesis of asthma and COPD.

As-needed ICS-LABA in Mild Asthma: What Does the Evidence Say?

For the last three decades, the guidelines for asthma management have supported a stepwise therapeutic approach, based on the administration of controller medications (especially inhaled corticosteroids) complemented by on-demand use of rescue medication. Classically, the rescue medication recommended comprised short-acting β agonists (SABA). Some years ago, the use of Symbicort Maintenance and Reliever Therapy (SMART) demonstrated the benefits of a combination of budesonide-formoterol, an inhaled corticosteroid, and a long-acting β agonist (ICS-LABA) as rescue medication in moderate and severe asthma. The results were enthusiastically received, and this therapeutic option was adopted in the guidelines for moderate to severe asthma patients. Recently, four trials (two randomised placebo control trials under the auspices of the SYGMA project and two real-life studies, Novel START, and the PRACTICAL trial) have explored the potential benefits of substituting SABA with budesonide-formoterol as rescue medication in mild asthma patients. The SYGMA 1 and 2 studies showed that the combination with formoterol-budesonide as rescue medication provides better asthma control than short-acting β-agonists alone in GINA step 2 patients, although the superiority was slight. Compared to budesonide maintenance therapy, the fixed combination of ICS-LABA on demand provides poorer asthma control. Regarding exacerbations, the fixed dose ICS-LABA combination on demand showed the same benefits for the prevention of exacerbations as chronic ICS treatment in mild asthma patients. The Novel START study, which assessed a population with milder symptoms, concluded that the fixed dose ICS-LABA combination used as needed was superior to SABA (albuterol) as needed for the prevention of asthma exacerbations. These results in fact show that, in undertreated GINA step 2 with only SABA as needed, ICS-LABA is more effective than SABA. The authors of PRACTICAL concluded that the study provided modest evidence that the ICS-LABA combination used as-needed for symptom relief reduces the rate of severe exacerbations compared with maintenance low-dose budesonide plus terbutaline as needed, although the study was not limited to mild asthma since according to the treatment consumed, it was evident that they had recruited some moderate asthma patients. Despite this poor evidence, and ignoring the clinical histological benefits of chronic inhaled corticosteroids (especially when administered promptly), GINA 2019 recently recommended daily low dose ICS or ICS-LABA as needed as a first option for step 2 patients. For step 1, symptom-driven or as-needed treatment with ICS-LABA is recommended rather than SABA alone (the preferred option until the last GINA update). Finally, the SIENA study showed that 73% of patients with mild asthma do not have an eosinophilic phenotype and that these patients have a similar clinical response to ICS (mometasone) and antimuscarinic drugs (tiotropium), results that challenge the indication of a drug combination that incorporates ICS as a first option. Overall, we believe there is insufficient evidence for the systematic recommendation of as-needed ICS-LABA instead of SABA on request for GINA step 1 or as a replacement for chronic ICS in GINA step 2.

Insulin-Like Growth Factor 1 Regulates Acute Inflammatory Lung Injury Mediated by Influenza Virus Infection

The acute inflammatory lung injury is an important cause of death due to influenza A virus (IAV) infection. Insulin-like growth factor 1 (IGF1) played an important role in the regulation of inflammation in the immune system. To investigate the role of IGF1 in IAV-mediated acute inflammatory lung injury, the expression of IGF1 and inflammatory cytokines was tested after IAV A/Puerto Rico/8/1934 (H1N1; abbreviated as PR8) infection in A549 cells. Then, a BALB/c mouse model of PR8 infection was established. On days 3, 5, 7, and 9 post-infection, the mice lung tissue was collected to detect the expression changes in IGF1 mRNA and protein. The mice were divided into four groups: (1) PBS (abbreviation of phosphate buffered saline); (2) PR8 + PBS; (3) PR8 + IGF1; and (4) PR8 + PPP (abbreviation of picropodophyllin, the IGF1 receptor inhibitor). The body weight and survival rate of the mice were monitored daily, and the clinical symptoms of the mice were recorded. On day 5 post-infection, the mice were sacrificed to obtain the serum and lung tissues. The expression of inflammatory cytokines in the serum was detected by enzyme linked immunosorbent assay; lung injury was observed by hematoxylin-eosin staining; the viral proliferation in the lung was detected by real-time quantitative PCR; and the protein expression of the main molecules in the phosphatidylinositol-3-kinases/protein kinase B (PI3K/AKT) and mitogen-activated protein kinase (MAPK) signaling pathways was detected by Western blot. It was found that IGF1 expression is upregulated in A549 cells and BALB/c mice infected with PR8, whereas IGF1 regulated the expression of inflammatory cytokines induced by PR8 infection. Overexpression of IGF1 aggravated the IAV-mediated inflammatory response, whereas the inhibition of IGF1 receptor reduced such inflammatory response. The phosphorylation of IGF1 receptor triggered the PI3K/AKT and MAPK signaling pathways to induce an inflammatory response after IAV infection. Therefore, IGF1 plays an important immune function in IAV-mediated acute inflammatory lung injury. IGF1 may provide a therapeutic target for humans in response to an influenza outbreak, and inhibition of IGF1 or IGF1 receptor may represent a novel approach to influenza treatment.

Insulin‑like growth factor 1 inhibits phagocytosis of alveolar epithelial cells in asthmatic mice

The phagocytosis of apoptotic cells by alveolar epithelial cells helps to eliminate airway inflammation. Insulin‑like growth factor 1 (IGF‑1) regulates cell metabolism and proliferation, and promotes cell survival, while it may also promote the proliferation and differentiation of alveolar epithelial cells during the repair of lung injury. The present study investigated the effect of IGF‑1 on the phagocytic activity of alveolar epithelial cells, a nonprofessional phagocyte. IGF‑1 was elevated in lung tissue and bronchoalveolar lavage fluid obtained from mice with ovalbumin‑induced asthma. IGF‑1 was reduced by 50% in the lung tissue and by nearly 100% in the bronchoalveolar lavage fluid in asthmatic mice established by depletion of alveolar macrophages using 2‑chloroadenosine. In addition, interleukin‑33 induced IGF‑1 production in primary alveolar macrophages. It was also observed that IGF‑1 inhibited the phagocytosis of fluorescent microspheres and apoptotic cells by MLE‑12 alveolar epithelial cells. Antibody blocking of IGF‑1 enhanced the phagocytosis of fluorescent microspheres and apoptotic cells, and significantly reduced inflammatory cell infiltration in airway and perivascular tissues. The elevated IGF‑1 level in the lungs of asthma model mice was mainly produced in alveolar macrophages. Taken together, the current study demonstrated that IGF‑1 inhibited phagocytosis by alveolar epithelial cells, and that IGF‑1 blockade enhanced the phagocytic activity and alleviated airway inflammation. These results support the potential use of IGF‑1 as a target in the treatment of asthma.

[New approaches of inhaled steroid asthma management in mild to moderate asthma]

Inhaled corticosteroids (ICS) are the cornerstone of the management of asthma. Daily use allows to reduce mortality, intensity and frequency of exacerbations, to increase the control of symptoms of asthma and the quality of life of asthmatics patients and to reduce the decline of the lung function. A daily use of a weak dose of ICS allows to control the symptoms of asthma of the vast majority of mild to moderate asthmatics patients who account for about 75-80 % of the French asthmatic patients. An add-on strategy with a combination by ICS/LABA allows to decrease by 20 % the risk of an exacerbation compared with a treatment by CSI in monotherapy. "SMART" which consists in using a fixed ICS/LABA combination as a maintenance and reliever therapy had showed better results in the prevention of exacerbations that the use of the same combination associated with a SABA as a reliever therapy. This strategy is recommended by GINA at the same level of proof as the classical treatment. An "on-demand" use of a ICS/LABA combination according to symptoms is clearly less efficacious in terms of control of the symptoms than the classical strategy by ICS/LABA; but both strategies are identical in terms of prevention of exacerbations. The daily dose of ICS is 4 to 5 times less than in the daily ICS group. The clinical effectiveness and cost-effectiveness of a standard asthma self-management plan that advises patients to temporarily quadrupling the dose of ICS in case of asthma worsening can be an alternative and allow to reduce 20 % of clinically important asthma exacerbations.

Insulin-Like Growth Factor-1 Signaling in Lung Development and Inflammatory Lung Diseases

Insulin-like growth factor-1 (IGF-1) was firstly identified as a hormone that mediates the biological effects of growth hormone. Accumulating data have indicated the role of IGF-1 signaling pathway in lung development and diseases such as congenital disorders, cancers, inflammation, and fibrosis. IGF-1 signaling modulates the development and differentiation of many types of lung cells, including airway basal cells, club cells, alveolar epithelial cells, and fibroblasts. IGF-1 signaling deficiency results in alveolar hyperplasia in humans and disrupted lung architecture in animal models. The components of IGF-1 signaling pathways are potentiated as biomarkers as they are dysregulated locally or systemically in lung diseases, whereas data may be inconsistent or even paradoxical among different studies. The usage of IGF-1-based therapeutic agents urges for more researches in developmental disorders and inflammatory lung diseases, as the majority of current data are collected from limited number of animal experiments and are generally less exuberant than those in lung cancer. Elucidation of these questions by further bench-to-bedside researches may provide us with rational clinical diagnostic approaches and agents concerning IGF-1 signaling in lung diseases.

Characterization of the acute inflammatory profile and resolution of airway inflammation after Igf1r-gene targeting in a murine model of HDM-induced asthma

Asthma is a chronic inflammatory disease characterized by bronchial hyperresponsiveness, mucus overproduction and airway remodeling. Notably, we have recently demonstrated that insulin-like growth factor 1 receptor (IGF1R) deficiency in mice attenuates airway hyperresponsiveness and mucus secretion after chronic house dust mite (HDM) exposure. On this basis, inbred C57BL/6 and Igf1r-deficient mice were given HDM extract to study the acute inflammatory profile and implication of Igf1r in acute asthma pathobiology. Additionally, Igf1r-deficiency was therapeutically induced in mice to evaluate the resolution of HDM-induced inflammation. Acute HDM exposure in inbred C57BL/6 mice led to a progressive increase in inflammation, airway remodeling and associated molecular indicators. Preventively-induced Igf1r-deficiency showed reduced neutrophil and eosinophil numbers in BALF and bone marrow, a significant reduction of airway remodeling and decreased levels of related markers. In addition, therapeutic targeting of Igf1r promoted the resolution of HDM-induced-inflammation. Our results demonstrate for the first time that Igf1r is important in acute asthma pathobiology and resolution of HDM-induced inflammation. Thus, IGF1R is suggested to be a promising candidate for future therapeutic approaches for the treatment and prevention of asthma.

Attenuated airway hyperresponsiveness and mucus secretion in HDM-exposed Igf1r-deficient mice

BACKGROUND

Asthma is a common chronic lung disease characterized by airflow obstruction, airway hyperresponsiveness (AHR), and airway inflammation. IGFs have been reported to play a role in asthma, but little is known about how the insulin-like growth factor 1 receptor (IGF1R) affects asthma pathobiology.

METHODS

Female Igf1r-deficient and control mice were intranasally challenged with house dust mite (HDM) extract or PBS five days per week for four weeks. Lung function measurements, and bronchoalveolar lavage fluid (BALF), serum, and lungs were collected on day 28 for further cellular, histological, and molecular analysis.

RESULTS

Following HDM exposure, the control mice responded with a marked AHR and airway inflammation. The Igf1r-deficient mice exhibited an increased expression of the IGF system and surfactant genes, which were decreased in a similar manner for control and Igf1r-deficient mice after HDM exposure. On the other hand, the Igf1r-deficient mice exhibited no AHR, and a selective decrease in blood and BALF eosinophils, lung Il13 levels, collagen, and smooth muscle, as well as a significant depletion of goblet cell metaplasia and mucus secretion markers after HDM exposure. The Igf1r-deficient mice displayed a distinctly thinner epithelial layer than control mice, but this was not altered by HDM.

CONCLUSIONS

Herein, we demonstrate by the first time that the Igf1r plays an important role in murine asthma, mediating both AHR and mucus secretion after HDM exposure. Thus, our study identifies IGF1R as a potential therapeutic target, not only for asthma but also for hypersecretory airway diseases.

Chronic stress impairs the local immune response during cutaneous repair in gilthead sea bream (Sparus aurata, L.)

Scale removal in fish triggers a damage-repair program to re-establish the lost epidermis and scale and an associated local immune response. In mammals, chronic stress is known to delay wound healing and to modulate the cutaneous stress axis, but this is unstudied in teleost fish the most successful extant vertebrates. The present study was designed to test the hypothesis that chronic stress impairs cutaneous repair in teleost fish as a consequence of suppression of the immune response. The hypothesis was tested by removing the scales and damaging the skin on one side of the body of fish previously exposed for 4 weeks to a chronic crowding stress and then evaluating cutaneous repair for 1 week. Scale removal caused the loss of the epidermis although at 3days it was re-established. At this stage the basement membrane was significantly thicker (p=0.038) and the hypodermis was significantly thinner (p=0.016) in the regenerating skin of stressed fish relative to the control fish. At 3days, stressed fish also had a significantly lower plasma osmolality (p=0.015) than control fish indicative of reduced barrier function. Chronic stress caused a significant down-regulation of the glucocorticoid receptor (gr) in skin before damage (time 0, p=0.005) and of star at 3 and 7days (p<0.05) after regeneration relative to control fish. In regenerating skin key transcripts of cutaneous repair, pcna, colivα1 and mmp9, and the inflammatory response, tgfβ1, csf-1r, mpo and crtac2, were down-regulated (p<0.05) by chronic stress. Irrespective of chronic stress and in contrast to intact skin many hyper pigmented masses, putative melanomacrophages, infiltrated the epidermis of regenerating skin. This study reveals that chronic stress suppresses the local immune response to scale removal and impairs the expression of key transcripts of wound healing. Elements of the stress axis were identified and modulated by chronic stress during cutaneous repair in gilthead seabream skin.

The Role of the T lymphocytes and Remodeling in Asthma

In allergic asthma (AA), inflammatory changes in the airway epithelium may contribute to the characteristic pathophysiology and symptoms. The presence of T lymphocytes, eosinophils, mast cells and macrophages, the presence of cytokines, and also structural changes in the airway mucous membrane are characteristic for asthma. Bronchial biopsy specimens were obtained from 33 AA, 25 nonallergic asthma (NAA), and 20 healthy controls (HC). This study used immunohistochemical techniques for identified monoclonal antibodies (CD3, CD4, CD8, CD25, ECP, MBP, tenascin, and laminin) in the bronchi. The highest number of eosinophils and T lymphocyte cells in bronchial biopsies was found in AA, and NAA. The number of T lymphocytes in AA was significantly higher than in NAA and HC. The degree of epithelial damage was higher in the AA group compared to the other groups. The tenascin- and laminin-positive layers in AA were thicker than other groups. In AA, a significant negative correlation was found between epithelial integrity and the count for eosinophils or T lymphocytes. T lymphocytes and eosinophils in AA were found in the area of epithelial and lamina propria damage. This article suggests that T lymphocytes may not only contribute to the chronic airway inflammatory response, airway remodeling, and symptomatology but may also have a central role at the initiation of the allergic immune response. Th-targeted therapy would be of considerable interest in controlling AA. Having more knowledge on the roles of T lymphocytes in the pathogenesis of allergic inflammation highlights the contributions of these cells in regulating and may lead to a new therapeutic target-AA.

Airway remodeling in asthma: what really matters

Airway remodeling is generally quite broadly defined as any change in composition, distribution, thickness, mass or volume and/or number of structural components observed in the airway wall of patients relative to healthy individuals. However, two types of airway remodeling should be distinguished more clearly: (1) physiological airway remodeling, which encompasses structural changes that occur regularly during normal lung development and growth leading to a normal mature airway wall or as an acute and transient response to injury and/or inflammation, which ultimately results in restoration of a normal airway structures; and (2) pathological airway remodeling, which comprises those structural alterations that occur as a result of either disturbed lung development or as a response to chronic injury and/or inflammation leading to persistently altered airway wall structures and function. This review will address a few major aspects: (1) what are reliable quantitative approaches to assess airway remodeling? (2) Are there any indications supporting the notion that airway remodeling can occur as a primary event, i.e., before any inflammatory process was initiated? (3) What is known about airway remodeling being a secondary event to inflammation? And (4), what can we learn from the different animal models ranging from invertebrate to primate models in the study of airway remodeling? Future studies are required addressing particularly pheno-/endotype-specific aspects of airway remodeling using both endotype-specific animal models and “endotyped” human asthmatics. Hopefully, novel in vivo imaging techniques will be further advanced to allow monitoring development, growth and inflammation of the airways already at a very early stage in life.

Airway remodelling in COPD: It's not asthma!

COPD is defined as airflow limitation that is not reversed by treatment. In asthma, airflow limitation is not only reversible, but also inducible. This is called 'airway hyperresponsiveness' (AHR) and is associated with thickening of the airway wall, predominantly the layer of airway smooth muscle, due to more cells, bigger cells and more extracellular matrix (ECM) in proportion to the increase in smooth muscle. AHR is also observed in COPD if the changes in airflow are expressed as a percent of the baseline lung function. However, the absolute change in baseline lung function that can be induced in COPD is actually less than that seen in normal subjects, suggesting that the airways in COPD are resistant not only to opening, but also to closing. This observation agrees with physiological measures showing increased airway wall stiffness in COPD. Like asthma, airway wall thickness is increased in COPD, including the layer of smooth muscle. Unlike asthma, however, fixed airflow obstruction appears to be characterized by a disproportionate increase in the ECM within the smooth muscle layer. In this review, we summarize the studies of airway matrix deposition in COPD and put forward the proposal that the airway remodelling in COPD is different from that in asthma and call for a systematic analysis of airway matrix deposition in COPD.

Therapeutic implication of genetic variants of IL13 and STAT4 in airway remodelling with bronchial asthma

BACKGROUND

Several gene variants identified in bronchial asthmatic patients are associated with a decrease in pulmonary function. The effects of this intervention on pulmonary function have not been fully researched.

OBJECTIVE

We determined the effects of high-dose inhaled corticosteroids (ICSs) on decreased pulmonary function in asthmatic Japanese patients with variants of IL13 and STAT4 during long-term treatments with low to mild doses of ICS.

METHODS

In this study, 411 patients with bronchial asthma who were receiving ICSs and living in Japan were recruited, were genotyped, and underwent pulmonary function tests and fibreoptic examinations. The effects of 2 years of high-dose ICSs administered to asthmatic patients who were homozygous for IL13 AA of rs20541 or STAT4 TT of rs925847 and who progressed to airway remodelling were investigated.

RESULTS

High-dose ICS treatment increased the pulmonary function of patients homozygous for IL13 AA of rs20541 but not of patients homozygous for STAT4 TT of rs925847. The increased concentrations of the mediators IL23, IL11, GMCSF, hyaluronic acid, IL24, and CCL8 in bronchial lavage fluid (BLF) were diminished after high-dose ICS treatment in patients homozygous for IL13 AA of rs20541.

CONCLUSION AND CLINICAL RELEVANCE

IL13 AA of rs20541 and STAT4 TT of rs925847 are potential genomic biomarkers for predicting lower pulmonary function. The administration of high-dose ICSs to asthmatic patients with genetic variants of IL13 AA may inhibit the advancement of airway remodelling. The genetic variants of STAT4 TT did not respond to high-dose ICSs. Therefore, using medications other than ICSs must be considered even during the initial treatment of bronchial asthma. These genetic variants may aid in the realization of personalized and phenotype-specific therapies for bronchial asthma.

Gender differences in the relationship between body mass index (BMI) changes and the prevalence and severity of wheezing and asthma in the first year of life

BACKGROUND

Rapid weight gain has been recently associated with asthma at school age, but its influence in respiratory symptoms during infancy is still unknown.

METHODS

Answers from 6541 parents living in six different cities of Brazil to the International Study of Wheezing in Infants (EISL) questionnaire were analysed. Data from reported weight and height at birth and at one year were used to calculate BMI. Rapid body mass index (BMI) gain was defined by the difference in BMI superior to 1.0z and excessive by the difference superior to 2.0z.

RESULTS

Rapid BMI gain was found in 45.8% infants and excessive in 24.4%. Boys showed a significantly higher BMI gain than girls. Girls with rapid BMI gain showed a significantly higher prevalence of hospitalisation for wheezing (8.8% vs. 6.4%; aOR: 1.4, 95%CI: 1.1-1.8), severe wheezing (18.1% vs. 15.0%; aOR: 1.3, 95%CI: 1.0-1.5) and medical diagnosis of asthma (7.5% vs. 5.7%; aOR: 1.3, 95%CI: 1.0-1.7). Girls with excessive BMI gain also had a significantly higher prevalence of hospitalisation for wheezing (9.8% vs. 6.7%; aOR: 1.5, 95%CI: 1.1-2.0) and severe wheezing (18.9% vs. 15.5%; aOR: 1.3, 95%CI: 1.0-1.6). No significant association was found among boys.

CONCLUSIONS

The majority of the evaluated infants showed BMI gain above expected in the first year of life. Although more commonly found in boys, rapid and excessive BMI gain in the first year of life was significantly related to more severe patterns of wheezing in infancy among girls.

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.

Clinical, physiological, and radiological features of asthma-chronic obstructive pulmonary disease overlap syndrome

Background

Asthma–chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS) is associated with rapid decline in lung function, poorer health-related quality-of-life outcomes, and frequent exacerbations, compared to COPD alone. Although the numbers of patients with ACOS have increased, there is little established evidence regarding diagnostic criteria and treatment options. Thus, the aim of our study was to clarify the clinical, physiological, and radiological features of patients with ACOS.

Methods

We examined a total of 100 patients with COPD and 40 patients with ACOS, who were selected based on clinical criteria. All patients underwent baseline testing, including a COPD assessment test, pulmonary function tests, and multidetector row computed tomography imaging. Percentage of low attenuation volume, percentage of wall area, and percentage of total cross-sectional area of pulmonary vessels less than 5 mm² (%CSA <5) were determined using multidetector row computed tomography. ACOS patients were administered a fixed dose of budesonide/formoterol (160/4.5 μg, two inhalations; twice daily) for 12 weeks, after which the ACOS patients underwent multidetector row computed tomography to measure the same parameters.

Results

At baseline, the ACOS patients and COPD patients had a similar degree of airflow limitation, vital capacity, and residual volume. ACOS patients had higher COPD assessment test scores, percentage of wall area, and %CSA <5 than COPD patients. Compared to baseline, budesonide/formoterol treatment significantly increased the forced expiratory volume in 1 second and decreased the degree of airway wall thickness (percentage of wall area) as well as pulmonary microvascular density (%CSA <5) in ACOS patients.

Conclusion

Our results suggest that ACOS is characterized by an airway lesion–dominant phenotype, in contrast to COPD. Higher %CSA <5 might be a characteristic feature of ACOS.

Characterization of a novel model incorporating airway epithelial damage and related fibrosis to the pathogenesis of asthma

Asthma develops from injury to the airways/lungs, stemming from airway inflammation (AI) and airway remodeling (AWR), both contributing to airway hyperresponsiveness (AHR). Airway epithelial damage has been identified as a new etiology of asthma but is not targeted by current treatments. Furthermore, it is poorly studied in currently used animal models of AI and AWR. Therefore, this study aimed to incorporate epithelial damage/repair with the well-established ovalbumin (OVA)-induced model of chronic allergic airway disease (AAD), which presents with AI, AWR, and AHR, mimicking several features of human asthma. A 3-day naphthalene (NA)-induced model of epithelial damage/repair was superimposed onto the 9-week OVA-induced model of chronic AAD, before 6 weeks of OVA nebulization (NA+OVA group), during the second last OVA nebulization period (OVA/NA group) or 1 day after the 6-week OVA nebulization period (OVA+NA group), using 6-8-week-old female Balb/c mice (n=6-12/group). Mice subjected to the 9-week OVA model, 3-day NA model or respective vehicle treatments (saline and corn oil) were used as appropriate controls. OVA alone significantly increased epithelial thickness and apoptosis, goblet cell metaplasia, TGF-β1, subepithelial collagen (assessed by morphometric analyses of various histological stains), total lung collagen (hydroxyproline analysis), and AHR (invasive plethysmography) compared with that in saline-treated mice (all P<0.05 vs saline treatment). NA alone caused a significant increase in epithelial denudation and apoptosis, TGF-β1, subepithelial, and total lung collagen compared with respective measurements from corn oil-treated controls (all P<0.01 vs corn oil treatment). All three combined models underwent varying degrees of epithelial damage and AWR, with the OVA+NA model demonstrating the greatest increase in subepithelial/total lung collagen and AHR (all P<0.05 vs OVA alone or NA alone). These combined models of airway epithelial damage/AAD demonstrated that epithelial damage is a key contributor to AWR, fibrosis and related AHR, and augments the effects of AI on these parameters.

Potential involvement of IL-17F in asthma

The expression of IL-17F is seen in the airway of asthmatics and its level is correlated with disease severity. Several studies have demonstrated that IL-17F plays a pivotal role in allergic airway inflammation and induces several asthma-related molecules such as CCL20. IL-17F-induced CCL20 may attract Th17 cells into the airway resulting in the recruitment of additional Th17 cells to enhance allergic airway inflammation. We have recently identified, for the first time, that bronchial epithelial cells are its novel cell source in response to IL-33 via ST2-ERK1/2-MSK1 signaling pathway. The receptor for IL-17F is the heterodimeric complex of IL-17RA and IL-17RC, and IL-17F activates many signaling pathways. In a case-control study of 867 unrelated Japanese subjects, a His161 to Arg161 (H161R) substitution in the third exon of the IL-17F gene was associated with asthma. In atopic patients with asthma, prebronchodilator baseline FEV1/FVC values showed a significant association with the H161R variant. Moreover, this variant is a natural antagonist for the wild-type IL-17F. Moreover, IL-17F is involved in airway remodeling and steroid resistance. Hence, IL-17F may play an orchestrating role in the pathogenesis of asthma and may provide a valuable therapeutic target for development of novel strategies.

Targeting insulin-like growth factor-I and insulin-like growth factor-binding protein-3 signaling pathways. A novel therapeutic approach for asthma

Insulin-like growth factor (IGF)-I has been recognized to play critical roles in the pathogenesis of asthma, whereas IGF-binding protein (IGFBP)-3 blocks crucial physiologic manifestations of asthma. IGF-I enhances subepithelial fibrosis, airway inflammation, airway hyperresponsiveness, and airway smooth muscle hyperplasia by interacting with various inflammatory mediators and complex signaling pathways, such as intercellular adhesion molecule-1, and the hypoxia-inducible factor/vascular endothelial growth factor axis. On the other hand, IGFBP-3 decreases airway inflammation and airway hyperresponsiveness through IGFBP-3 receptor-mediated activation of caspases, which subsequently inhibits NF-κB signaling pathway. It also inhibits the IGF-I/hypoxia-inducible factor/vascular endothelial growth factor axis via IGF-I-dependent and/or IGF-I-independent mechanisms. This Translational Review summarizes the role of IGF-I and IGFBP-3 in the context of allergic airway disease, and discusses the therapeutic potential of various strategies targeting the IGF-I and IGFBP-3 signaling pathways for the management of asthma.

Comparison of TNF antagonism by etanercept and dexamethasone on airway epithelium and remodeling in an experimental model of asthma

BACKGROUND

The aim of the study was to compare the influence of TNF antagonism and corticosteroid treatment on epithelial, smooth muscle and basement membrane component of airway remodeling in an experimental murine model of chronic asthma.

METHODS

We used 30 BALB/c mice. Group 1 not exposed to ovalbumin or any medication was designated as control group. Chronic asthma model was achieved in the other three groups with intraperitoneal (IP) and inhaled ovalbumin. Then, Group 2 received IP saline, Group 3 received IP dexamethasone and Group 4 received IP etanercept. Epithelial, subepithelial smooth muscle and basement membrane thickness as well as goblet cells and mast cells were examined on samples isolated from left lung.

RESULTS

Etanercept treatment led to thinner epithelial and basement membrane layer and lower goblet and mast cell number than untreated asthmatic mice (p<0.001, p=0.001, p=0.005 and p=0.03 respectively). Neither epithelial and basement membrane thickness nor mast cell number was different among mice treated with etanercept and dexamethasone (p=0.38, p=0.79 and p=0.51 respectively). However, etanercept group was associated with thicker subepithelial muscle layer but lower goblet cell number (p<0.001 and p=0.04 respectively) than dexamethasone group.

CONCLUSIONS

Corticosteroids are more effective in decreasing smooth muscle mass while TNF antagonists in reducing goblet cell number in animal model of asthma. Therefore, further research is needed to assess the synergistic use of TNF antagonism and dexamethasone for more rational remodeling control.

Antileukotriene reverts the early effects of inflammatory response of distal parenchyma in experimental chronic allergic inflammation

Aims. Compare the effects of montelukast or dexamethasone in distal lung parenchyma and airway walls of guinea pigs (GP) with chronic allergic inflammation. Methods. GP have inhaled ovalbumin (OVA group-2x/week/4weeks). After the 4th inhalation, GP were treated with montelukast or dexamethasone. After 72 hours of the 7th inhalation, GP were anesthetised, and lungs were removed and submitted to histopathological evaluation. Results. Montelukast and dexamethasone treatments reduced the number of eosinophils in airway wall and distal lung parenchyma compared to OVA group (P < 0.05). On distal parenchyma, both treatments were effective in reducing RANTES, NF-κB, and fibronectin positive cells compared to OVA group (P < 0.001). Montelukast was more effective in reducing eotaxin positive cells on distal parenchyma compared to dexamethasone treatment (P < 0.001), while there was a more expressive reduction of IGF-I positive cells in OVA-D group (P < 0.001). On airway walls, montelukast and dexamethasone were effective in reducing IGF-I, RANTES, and fibronectin positive cells compared to OVA group (P < 0.05). Dexamethasone was more effective in reducing the number of eotaxin and NF-κB positive cells than Montelukast (P < 0.05). Conclusions. In this animal model, both treatments were effective in modulating allergic inflammation and remodeling distal lung parenchyma and airway wall, contributing to a better control of the inflammatory response.

The Role of Mitogen-Activated Protein Kinase-Activated Protein Kinases (MAPKAPKs) in Inflammation

Mitogen-activated protein kinase (MAPK) pathways are implicated in several cellular processes including proliferation, differentiation, apoptosis, cell survival, cell motility, metabolism, stress response and inflammation. MAPK pathways transmit and convert a plethora of extracellular signals by three consecutive phosphorylation events involving a MAPK kinase kinase, a MAPK kinase, and a MAPK. In turn MAPKs phosphorylate substrates, including other protein kinases referred to as MAPK-activated protein kinases (MAPKAPKs). Eleven mammalian MAPKAPKs have been identified: ribosomal-S6-kinases (RSK1-4), mitogen- and stress-activated kinases (MSK1-2), MAPK-interacting kinases (MNK1-2), MAPKAPK-2 (MK2), MAPKAPK-3 (MK3), and MAPKAPK-5 (MK5). The role of these MAPKAPKs in inflammation will be reviewed.

Acute inflammation induces insulin-like growth factor-1 to mediate Bcl-2 and Muc5ac expression in airway epithelial cells

Generally, exposure to LPS in human airways occurs in the form of aerosols and causes an acute inflammatory response or exacerbates existing chronic inflammatory conditions by enhancing airway remodeling and associated pathologies. The present study evaluated which inflammatory mediators may be responsible for the expression of Bcl-2 and mucus cell metaplasia when mice are exposed to aerosolized LPS. At 3 days after exposure, aerosolized LPS (for 20-40 min) with the estimated lung deposited dosage of 0, 0.02, 0.2, 1.4, and 20.2 μg showed a characteristic dose-dependent increase in polymorphonuclear neutrophils. Significant increases of proinflammatory mediators, including IL-1β, TNF-α, IL-6, growth-related oncogene or keratinocyte-derived cytokine, IFN-γ-induced protein-10, monocyte chemotactic protein-1, and macrophage inflammatory protein-1α, were detected at the highest doses. In addition to increased numbers of airway epithelial cells, mucus cell numbers and mucus production were increased in a dose-dependent manner. Hyperplastic epithelial cells expressed insulin-like growth factor (IGF)-1 and, similar to previous studies, increased expression of the prosurvival protein Bcl-2 and induced expression of Muc5ac. Suppression of IGF-1 expression using retroviral shRNA blocked Bcl-2 expression in human and murine airway epithelial cells and Muc5ac in primary murine airway epithelial cells. These findings show that acute inflammation induces IGF-1 to mediate Bcl-2 and Muc5ac expression in airway epithelial cells.

Recombinant IGFBP-3 inhibits allergic lung inflammation, VEGF production, and vascular leak in a mouse model of asthma

BACKGROUND

Vascular endothelial growth factor (VEGF) plays a pro-inflammatory mediator as well as a vascular permeability factor in bronchial asthma. Insulin-like growth factor (IGF)-I is also involved in the inflammatory process associated with bronchial asthma and stimulates VEGF expression. The IGF-binding proteins (IGFBPs), especially IGFBP-3, display distinctive properties and can interfere with various biological processes.

METHODS

In this study, an ovalbumin (OVA)-induced murine model of allergic airway disease was used to investigate which mechanism is implicated in the preventive and therapeutic actions of IGFBP-3 administered exogenously on allergen-induced bronchial inflammation and airway hyper-responsiveness, in particular focusing on the regulation of VEGF expression.

RESULTS

Administration of recombinant human IGFBP-3 to OVA-inhaled mice substantially attenuated the increases in hypoxia-inducible factor (HIF)-α activity, IGF-I production, and VEGF protein levels in the lung. In addition, the blockade of IGF-I action decreased the OVA-induced VEGF expression, airway inflammation, and bronchial hyper-responsiveness. The administration of recombinant human IGFBP-3 or CBO-P11 also reduced significantly increases in inflammatory cells, airway hyper-responsiveness, levels of IL-4, IL-5, IL-13, and vascular permeability in the lung of OVA-inhaled mice. Moreover, when recombinant human IGFBP-3 was administered after the completion of OVA inhalation, these therapeutic effects of IGFBP-3 were also observed.

CONCLUSIONS

These results indicate that IGFBP-3 administered exogenously may attenuate antigen-induced airway inflammation and hyper-responsiveness through the modulation of vascular leakage and VEGF expression mediated by HIF-1α/HIF-2α signaling as well as IGF-I action in allergic airway disease of mice.

Is low dose inhaled corticosteroid therapy as effective for inflammation and remodeling in asthma? A randomized, parallel group study

Background

While most of the clinical benefits of inhaled corticosteroid (ICS) therapy may occur at low doses, results of dose-ranging studies are inconsistent. Although symptom/lung function response to low and high dose ICS medication is comparable, it is uncertain whether low dose ICSs are as effective as high dose in the treatment of inflammation and remodeling.

Methods

22 mild or moderate asthmatic adult subjects (corticosteroid free for > 2 months) participated in a randomized, parallel group study to compare effects of fluticasone propionate (FP) 200 mcg/day and 1000 mcg/day. Alveolar macrophage (AM)-derived cytokines and basement membrane thickness (BMT) were measured at baseline and after 7 weeks treatment while symptoms, spirometry, exhaled nitric oxide (eNO) and airway hyperresponsiveness (AHR) to mannitol at baseline and 6 weeks.

Results

FP improved spirometry, eNO, symptoms and AHR with no difference between low and high dose FP. Both high and low dose FP reduced GM-CSF, TNF-alpha and IL-1ra, with no change in BMT and with no differences between low and high dose FP.

Conclusions

200 μg/day of FP was as effective as 1000 μg/day in improving asthma control, airway inflammation, lung function and AHR in adults in the short term. Future studies should examine potential differential effects between low and high dose combination therapy (ICS/long acting beta agonist) on inflammation and airway remodeling over longer treatment periods.

Effect of genetic variation of IL-13 on airway remodeling in bronchial asthma

BACKGROUND

IL-13 is a major stimulator of inflammation and tissue remodeling at sites of Th2 inflammation, and common single-nucleotide polymorphisms in IL13 are associated with allergic phenotypes in several ethnically diverse populations. In particular, IL13Q110 is the non-conservative replacement of a positively charged arginine (R) with a neutral glutamine (Q) at position 110 of IL-13, and as we already know, individuals homozygous for glutamine (Q110/Q110) are strongly associated with asthma and IgE. IL13Q110 has been demonstrated to show that increased allergic inflammation depended on the enhanced IL-13-mediated Th2 effector function. Therefore, we investigated whether Q110/Q110 accelerated the decline in pulmonary function and development of airway remodeling of asthmatic patients in the general population.

METHODS

A total 336 asthmatic subjects living in Japan were recruited, genotyped, and had a pulmonary function test performed on them. To analyze airway inflammation and remodeling, bronchial lavage fluid (BLF) and endobronchial biopsy specimens were examined.

RESULTS

Forced expiratory volume in one second (FEV1), %predicted, forced expiratory volume/forced vital capacity ratio, and forced expiratory flow 25-75%, % predicted were significantly decreased in Q110/Q110 compared to R110/R110, and the decline in FEV1 was increased significantly in Q110/Q110 compared to R110/R110. The concentration of IL-13, IL-23, IL-11, GM-CSF, hyaluronic acid, and CCL8 in BLF were increased in Q110/Q110 compared to R110/R110 and the thickness of the subepithelial layer was thicker.

CONCLUSIONS

Our study demonstrates that Q110/Q110 increases, at least in part, allergic inflammation and the propensity for airway remodeling, thus resulting in low lung function.

What effect does asthma treatment have on airway remodeling? Current perspectives

Airway remodeling, or structural changes of the airway wall arising from injury and repair, plays an important role in the pathophysiology of asthma. Remodeling is characterized as structural changes involving the composition, content, and organization of many of the cellular and molecular constituents of the bronchial wall. These structural changes can include epithelial injury, subepithelial thickening/fibrosis, airway smooth muscle hyperplasia, goblet cell hypertrophy and hyperplasia, and angiogenesis. Historically, these changes are considered a consequence of long-standing airway inflammation. Recent infant and child studies, however, suggest that remodeling occurs in parallel with inflammation in asthmatic subjects. Despite advancements in the recognition of key cellular and molecular mechanisms involved in remodeling, there remains a paucity of information about which treatments or interactions are most likely to regulate these processes. Furthermore, it is unclear as to when is the best time to initiate treatments to modify remodeling, which components to target, and how best to monitor interventions on remodeling. Indeed, inhaled corticosteroids, which are generally considered to have limited influence on remodeling, have been shown to be beneficial in studies in which the dose and duration of treatment were increased and prolonged, respectively. Moreover, several studies have identified the need to identify novel asthma indices and phenotypes that correlate with remodeling and, as a consequence, might specifically respond to new therapies, such as anti-IgE, anti-IL-5, and anti-TNF-α mAbs. Our review will evaluate the development of remodeling in asthmatic subjects and the effects of treatment on these processes.

Insulin-like growth factor-binding protein-3 (IGFBP-3) blocks the effects of asthma by negatively regulating NF-κB signaling through IGFBP-3R-mediated activation of caspases

Insulin-like growth factor-binding protein-3 (IGFBP-3) is a multifunctional protein known for modulating mitogenic and metabolic actions of IGFs as well as exerting a variety of biological actions not involving IGFs. Here, we show that IGFBP-3 blocks specific physiological consequences of asthma in an IGF-independent manner in vitro and in vivo. IGFBP-3 treatment effectively reduced all physiological manifestations of asthma examined in vivo (airway hyper-responsiveness, cellular and pathological changes in bronchoalveolar lavage fluid and lung tissue, and expression of numerous proinflammatory molecules). These unique IGFBP-3 effects were further confirmed in IGFBP-3-transgenic mice, thus strengthening the notion of IGFBP-3 actions within the respiratory system. Using human epithelial cells, we demonstrated the following: 1) IGFBP-3 blocks TNF-α-induced expression of proinflammatory molecules; 2) IGFBP-3 attenuates the TNF-α-induced migratory response of eosinophils; and 3) IGFBP-3 negatively regulates TNF-α-induced expression of the key NF-κB regulatory molecules IκBα and p65-NF-κB at the post-translational level. We identified that IGFBP-3 degrades IκBα and p65-NF-κB proteins through IGFBP-3 receptor (IGFBP-3R)-mediated activation of caspases thereby inhibiting TNF-α-induced activation of NF-κB signaling cascades. This unique IGFBP-3/IGFBP-3R action was further confirmed by demonstrating complete inhibition of IGFBP-3 action in the presence of caspase inhibitors as well as IGFBP-3R siRNAs. Non-IGF-binding IGFBP-3 mutants further proved the IGF-independent action of IGFBP-3. Our findings indicate that IGFBP-3 inhibits airway inflammation and hyper-responsiveness via an IGF-independent mechanism that involves activation of IGFBP-3R signaling and cross-talk with NF-κB signaling. The IGFBP-3/IGFBP-3R system therefore plays a pivotal role in the pathogenesis of asthma and can serve as a newly identified potential therapeutic target for this debilitating disease.

Airway Measurement for Airway Remodeling Defined by Post-Bronchodilator FEV1/FVC in Asthma: Investigation Using Inspiration-Expiration Computed Tomography

PURPOSE

Airway remodeling may be responsible for irreversible airway obstruction in asthma, and a low post-bronchodilator FEV1/FVC ratio can be used as a noninvasive marker of airway remodeling. We investigated correlations between airway wall indices on computed tomography (CT) and various clinical indices, including post-bronchodilator FEV1/FVC ratio, in patients with asthma.

METHODS

Volumetric CT was performed on 22 stable asthma patients who were taking inhaled corticosteroids. Airway dimensions were measured at four segmental bronchi using in-house software based on the full-width/half-maximum method. Parameters included luminal area, wall thickness (WT), wall thickness percentage (WT%), wall area percentage (WA%), bronchial-to-arterial diameter (BA) ratio on inspiration CT, airway collapsibility (AC), and air trapping index (ATI). Correlations were analyzed between CT parameters and clinical indices, including %FEV1, FEV1/FVC, FEF(25-75%), and post-bronchodilator FEV1/FVC ratio.

RESULTS

Post-bronchodilator FEV1/FVC showed significant correlations with WT%, WT, BA ratio, AC, and ATI (r=-0.503, -0.576, 0.454, 0.475, and -0.610, respectively). WT showed negative correlations with FEV1/FVC and FEF(25-75%) (r=-0.431 and -0.581), and WT% was negatively correlated with %FEV1, FEV1/FVC, and FEF(25-75%) (r=-0.434, -0.431, and -0.540, respectively). WA% showed correlations with FEF(25-75%) and body mass index (r=-0.459 and 0.453). The BA ratio was positively correlated with %FEV1 (r=0.459) and FEF(25-75%) (r=0.479). AC showed strong positive correlation with FEV1/FVC (r=0.592), and ATI showed negative correlations with FEV1/FVC (r=-0.534) and FEF(25-75%) (r=-0.591).

CONCLUSIONS

WT%, WT, BA ratio, and AC on inspiration and expiration CT are good indices for measuring airway remodeling defined by post-bronchodilator FEV1/FVC in stable asthma patients treated with inhaled corticosteroids.

Induction of insulin-like growth factor-I by interleukin-17F in bronchial epithelial cells

BACKGROUND

Increased expression of IL-17F has been noted in the airway of asthmatic patients, but its role in asthma has not been fully elucidated. Insulin-like growth FACTOR-I (IGF-I) is known to be involved in airway remodelling and inflammation, while its regulatory mechanisms remain to be defined.

OBJECTIVE

To further clarify the biological function of IL-17F, we investigated whether IL-17F is able to regulate the expression of IGF-I in bronchial epithelial cells.

METHODS

Bronchial epithelial cells were stimulated with IL-17F in the presence or absence of T-helper type 2 cytokines. Various kinase inhibitors were added to the culture to identify the key signalling events leading to the expression of IGF-I, in conjunction with the use of short interfering RNAs (siRNAs) targeting mitogen- and stress-activated protein kinase (MSK) 1, p90 ribosomal S6 kinase (p90RSK), and cyclic AMP response element-binding protein (CREB).

RESULTS

IL-17F significantly induced IGF-I gene and protein expression, and co-stimulation with IL-4 and IL-13 augmented its production. MAP kinase kinase (MEK) inhibitors and the Raf1 kinase inhibitor significantly inhibited IGF-I production, and the combination of PD98059 and Raf1 kinase inhibitor showed further inhibition. Overexpression of Raf1 and Ras dominant-negative mutants inhibited its expression. MSK1 inhibitors significantly blocked IL17F-induced IGF-I expression. Moreover, transfection of the siRNAs targeting MSK1, p90RSK, and CREB blocked its expression.

CONCLUSIONS

In bronchial epithelial cells, IL-17F is able to induce the expression of IGF-I via the Raf1-MEK1/2-ERK1/2-MSK1/p90RSK-CREB pathway in vitro.

Montelukast added to fluticasone propionate does not alter inflammation or outcomes

BACKGROUND

Airway inflammation is a key pathological feature of asthma which underlies its clinical presentation.

OBJECTIVES

To examine whether adding a leukotriene modifier to an inhaled corticosteroid produces further clinical and/or anti-inflammatory benefits in patients symptomatic on short-acting beta(2)-agonists.

METHODS

Patients uncontrolled on short-acting beta(2)-agonists were treated for 12 weeks with either fluticasone propionate (100mcg BD) or fluticasone propionate (100mcg BD) and montelukast (10mg QD) in a randomized, double-blind, parallel group study. Bronchoscopy with endobronchial biopsy and bronchoalveolar lavage (BAL) was performed before and after treatment to compare effects on airway inflammation.

RESULTS

Of 103 subjects enrolled, 89 subjects completed treatment and 82 subjects had matched pair biopsy samples. Submucosal eosinophil counts, the primary endpoint, and asthma control improved to similar extents after both treatments (p<or=0.008). Both treatments significantly reduced submucosal mast cell, CD3+, CD4+, CD8+ and CD25+ cell counts. Submucosal mast cell reduction was greater in the fluticasone propionate plus montelukast group. There were no differences between treatments in BAL markers of inflammation or thickness of sub-epithelial collagen.

CONCLUSIONS

Low-dose fluticasone propionate significantly improves clinical disease control and reduces airway inflammation in asthma patients uncontrolled with short-acting beta(2)-agonists without further improvement when montelukast is added to low-dose fluticasone propionate.

Morphological and molecular characteristics of "difficult" asthma

BACKGROUND

There are several clinical variants of severe difficult-to-treat asthma: asthma with persistent airflow limitation, brittle asthma, and fatal asthma; but the differences between the pathogenetic mechanisms underlying the disease heterogeneity are unknown.

OBJECTIVES

The aim was to evaluate the morphological and molecular characteristics of brittle asthma type I and asthma with persistent airflow limitation compared to mild-to-moderate asthma, by the analysis of the cellular structure and gene expression in the bronchial mucosa.

METHODS

Bronchoscopic evaluation was performed in 42 asthmatic patients: 10 with brittle asthma, 10 with severe asthma with persistent airflow limitation, and 22 with mild-to-moderate asthma. Morphometric and cytological analyses of the bronchial mucosa were performed. The mRNA levels for the ADRB2, HRH1, and CHRM3 genes in the bronchial mucosa were measured by quantitative real-time polymerase chain reaction (PCR).

RESULTS

A predominance of eosinophils (29.48/mm(2), 95% confidence interval [CI] 25.24-33.72) and neutrophils (40.13/mm(2), 95% CI 32.77-47.49) was observed in patients with mild-to-moderate asthma; however, histiocytes-macrophages (65.80/mm(2), 95% CI 56.95-74.65) and lymphocytes (52.94/mm(2), 95% CI 42.83-63.06) were more common in patients with brittle asthma, and neutrophil counts (81.11/mm(2), 95% CI 58.33-103.89) were significantly increased in subjects with persistent airflow limitation. An increase in the expression of the M(3)-cholinoreceptor and the beta(2)-adrenoreceptor genes was demonstrated in severe asthmatics compared to mild-to-moderate asthma patients. Significantly higher levels of CHRM3 (57.17%, 95% CI 55.04-59.29) and HRH1 (38.82%, 95% CI 35.84-41.81) mRNAs were observed in patients with brittle asthma. The level of ADRB2 gene expression (71.41%, 95% CI 63.54-85.09) was maximal in patients with asthma with persistent airflow limitation.

CONCLUSIONS

There is evidence of significantly different morphological characteristics and molecular mechanisms of inflammation and bronchoconstriction underlying the clinical heterogeneity of severe asthma.

Recent findings on the pathogenesis of bronchial asthma. Part II. The role of hormonal predisposition, environmental influences and conditioning leading to bronchial asthma

In this second part of the review on the pathogenesis of asthma the hormonal factors and adverse external events are shortly reviewed which skew the balance of Th1 vs. Th2 CD4+ lymphocytes towards the latter ones and this way increase the probability of atopic diseases. Among other the role of transplacental priming, insulin, insulin-like and other growth factors, lack of the usual microbial infections in the early childhood (the so-called hygiene hypothesis), gender, diminished testosterone production, gastroesophageal reflux, adverse effects during pregnancy are discussed. A separate chapter deals with the role of central nervous system in the etiology and finally the most common allergizing and airway tissue damaging agents are listed in tabulated form.

Role of insulin-like growth factor binding protein-3 in allergic airway remodeling

RATIONALE

The hallmarks of allergic asthma are airway inflammation, obstruction, and remodeling. Airway remodeling may lead to irreversible airflow obstruction with increased morbidity and mortality. Despite advances in the treatment of asthma, the mechanisms underlying airway remodeling are still poorly understood. We reported that insulin-like growth factor (IGF) binding proteins (IGFBPs) contribute to extracellular matrix deposition in idiopathic pulmonary fibrosis; however, their contribution to airway remodeling in asthma has not been established.

OBJECTIVES

We hypothesized that IGFBP-3 is overexpressed in asthma and contributes to airway remodeling.

METHODS

We evaluated levels of IGFBP-3 in tissues and bronchoalveolar lavage fluid from patients with asthma at baseline and 48 hours after allergen challenge, in reparative epithelium in an in vitro wounding assay, and in conditioned media from cytokine- and growth factor-stimulated primary epithelial cells.

MEASUREMENTS AND MAIN RESULTS

IGFBP-3 levels and distribution were evaluated by Western blot, ELISA, and immunofluorescence. IGFBP-3 is increased in vivo in the airway epithelium of patients with asthma compared with normal control subjects. The concentration of IGFBP-3 is increased in the bronchoalveolar lavage fluid of patients with asthma after allergen challenge, its levels are increased in reparative epithelium in an in vitro wounding assay and in the conditioned medium of primary airway epithelial cell cultures stimulated with IGF-I.

CONCLUSIONS

Our results suggest that one mechanism of allergic airway remodeling is through the secretion of the profibrotic IGFBP-3 from IGF-I-stimulated airway epithelial cells during allergic inflammation.

Combined budesonide/formoterol therapy in conjunction with allergen avoidance ameliorates house dust mite-induced airway remodeling and dysfunction

Allergic asthma is characterized by airway inflammation in response to chronic allergen exposure, resulting in remodeling of the airway wall accompanied by dysfunctional airway physiology. However, a link between the immune-inflammatory response to allergen and changes to airway structure and physiology has not yet been fully elucidated. Moreover, the impact of inhaled corticosteroids and beta(2)-agonists, the primary pharmacotherapy for asthma, on this process has not been completely evaluated. In this study, we employed a murine model of chronic exposure to a common environmental aeroallergen, house dust mite, to recapitulate the phenotype of clinical asthma. By examining the therapeutic effects of corticosteroid/beta(2)-agonist combination therapy with budesonide/formoterol (BUD/FORM) in this model of airway disease, we endeavored to determine the impact of BUD/FORM on lung inflammation, structure, and physiology. BUD/FORM was delivered either while allergen exposure was ongoing (concurrent therapy) or following the cessation of allergen exposure (postexposure therapy). Our results show that airway inflammation was substantially reduced in BUD/FORM-treated mice in the concurrent therapy group, whereas in the postexposure therapy group airway inflammation spontaneously resolved. In contrast, BUD/FORM was most effective in resolving several aspects of airway remodeling and bronchial hyperreactivity when delivered in conjunction with allergen withdrawal. This study demonstrates that although both BUD/FORM therapy and allergen avoidance independently reduce airway inflammation, only BUD/FORM therapy in conjunction with allergen avoidance can effectively reverse airway remodeling and bronchial hyperreactivity induced by chronic allergen exposure.

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.

Mucosal remodeling in chronic rhinosinusitis

BACKGROUND

Despite pathophysiologic similarities, mucosal remodeling is well described in asthma but not chronic rhinosinusitis (CRS).

OBJECTIVE

This study attempts to identify mucosal remodeling in CRS and correlate it with clinical information.

METHODS

Charts and histopathology from 53 CRS patients who underwent functional endoscopic sinus surgery were reviewed. Clinical data and basement membrane (BM) thickness were recorded. BM thickness was graded as 0 (no thickening), 1 (mild thickening), 2 (moderate thickening), or 3 (marked thickening). Control mucosae from ten patients without CRS were analyzed for comparison.

RESULTS

Duration of CRS symptoms positively correlated with BM thickness (p = 0.007). Also, patients with a markedly thickened BM (score of 3) had a significantly greater duration of CRS symptoms (120 months) compared to patients with a thinner BM (score < or =2) (33 months) (p = 0.010). Markedly thickened BM was associated with increased coincidence of asthma (p = 0.019) and aspirin sensitivity (p = 0.003). No correlation was found between BM thickness and preoperative Lund-MacKay score. There was no statistically significant difference between markedly thickened BM and thinner BM with respect to coincidence of polyps, course of preoperative systemic steroids, estimated blood loss at surgery, and number of prior surgeries.

CONCLUSION

Increased BM thickness is correlated with prolonged duration of symptoms and the coincidence of asthma. This may indicate paranasal sinus remodeling akin to that which occurs in the bronchioles of persistent asthmatic sufferers.

Airway remodeling in asthma and irreversible airflow limitation-ECM deposition in airway and possible therapy for remodeling-

Airway remodeling in asthma is characterized by goblet cell hyperplasia, subepithelial fibrosis, and hyperplasia and hypertrophy of airway smooth muscle cells. The airway wall thickness increases because of subepithelial fibrosis, and hyperplasia and hypertrophy of the airway smooth muscle cells and submucosal glands. Airway remodeling, therefore, can often cause irreversible airflow limitation and an increase of airway hyperresponsiveness. Recent studies have described the molecular and cellular mechanisms of collagen deposition in the airway wall such as subepithelial fibrosis. Fibroblasts or myofibroblasts play a critical role in the exaggerated deposition of collagen in asthmatic airways. Bone marrow derived fibroblasts may play a role in fibrotic remodeling in asthmatic airways. Airway remodeling is induced by cytokines and mediators produced in chronic allergic airway inflammation. Since, once formed, remodeling is resistant to asthma therapy, early intervention with inhaled corticosteroid should be considered to prevent the progress of airway remodeling.

Insights into early treatment of mild asthma: do inhaled corticosteroids make a difference?

Approaches to the management of moderate-to-severe persistent asthma in both children and adults are widely accepted but the treatment of mild persistent asthma remains controversial because of the lack of agreement on what constitutes mild asthma and whether regular treatment is required at all. Recent evidence indicates that 'mild asthma' may not be as benign a condition as was widely believed and should be treated to improve asthma control and to prevent the significant burden of exacerbation and progression of disease. This is supported by compelling evidence from histologic and clinical studies that have attributed irreversible pathologic and functional airway changes to consequences of persistent airway inflammation and under-treated asthma. This article focuses on the rationale of early treatment of mild persistent asthma, and discusses the various findings from the largest randomized, early-intervention trial with inhaled corticosteroids as regular treatment in patients with asthma of recent onset--the START (inhaled Steroid Treatment As Regular Therapy in early asthma) study. A brief review of the background of the natural history of asthma, the findings from key longitudinal epidemiologic studies on disease progression in children and adults, and the effect of inhaled corticosteroids on this progression are included, to provide further insight into the impact of early treatment on asthma management guidelines.

Insulin increases the expression of contractile phenotypic markers in airway smooth muscle

We have previously demonstrated that long-term exposure of bovine tracheal smooth muscle (BTSM) strips to insulin induces a functional hypercontractile phenotype. To elucidate molecular mechanisms by which insulin might induce maturation of contractile phenotype airway smooth muscle (ASM) cells, we investigated effects of insulin stimulation in serum-free primary BTSM cell cultures on protein accumulation of specific contractile phenotypic markers and on the abundance and stability of mRNA encoding these markers. In addition, we used microscopy to assess insulin effects on ASM cell morphology, phenotype, and induction of phosphatidylinositol (PI) 3-kinase signaling. It was demonstrated that protein and mRNA levels of smooth muscle-specific contractile phenotypic markers, including sm-myosin, are significantly increased after stimulation of cultured BTSM cells with insulin (1 microM) for 8 days compared with cells treated with serum-free media, whereas mRNA stability was unaffected. In addition, insulin treatment promoted the formation of large, elongate ASM cells, characterized by dramatic accumulation of contractile phenotype marker proteins and phosphorylated p70(S6K) (downstream target of PI 3-kinase associated with ASM maturation). Insulin effects on protein accumulation and cell morphology were abrogated by combined pretreatment with the Rho kinase inhibitor Y-27632 (1 microM) or the PI 3-kinase inhibitor LY-294002 (10 microM), indicating that insulin increases the expression of contractile phenotypic markers in BTSM in a Rho kinase- and PI 3-kinase-dependent fashion. In conclusion, insulin increases transcription and protein expression of contractile phenotypic markers in ASM. This could have important implications for the use of recently approved aerosolized insulin formulations in diabetes mellitus.

The effect of inhaled budesonide and formoterol on bronchial remodeling and HRCT features in young asthmatics

Asthma is a chronic disease that may cause remodeling of the airways. We aimed to observe the effects of the combined use of inhaled budesonide and formoterol on both the reversibility of remodeling and structural changes in the airways. Thirty-six male patients (age range, 20-31) with mild-to-moderate persistent asthma were given inhaled formoterol and budesonide treatment for three months. Bronchial diameter (BD) and bronchial wall thickness (BWT), as measured by high-resolution computerized tomography, and reticular basement membrane thickness (RBMT), assessed in bronchoscopic biopsy specimens, were compared with pretreatment findings. Twenty-two age-matched male controls were also enrolled. BDs of the patients were significantly smaller than in the controls, whereas BWT and RBMT were greater. After three months BWT and RBMT of the subsegmental airways significantly decreased and BD increased. There was a prominent eosinophilic and lymphocytic infiltration in the bronchial mucosa of the asthmatics, and the eosinophilic infiltration significantly improved with treatment. Both serum total IgE and eosinophil counts were related to eosinophilic infiltration in the biopsy samples (r = 0.494 and r = 0.463, respectively). FEV(1) was positively correlated with the diameters of the segmental and subsegmental airways (r = 0.491 and r = 0.265, respectively) and negatively correlated with BWT of the subsegmental airways (r = -0.293) and with the RBMT of both the segmental and subsegmental airways (r = -0.597 and r = -0.590, respectively). We suggest that treatment with inhaled formoterol and budesonide may reverse increased RBMT and BWT as part of remodeling in patients with asthma.