Role of IL-6 in asthma and other inflammatory pulmonary diseases

Effect of aging on sputum inflammation and asthma control

BACKGROUND

Aged asthmatic patients experience increased morbidity and mortality. Knowledge of the aging effect on airway inflammation and asthma control is limited.

OBJECTIVE

We sought to compare airway inflammation and its relationship to asthma control in aged versus younger patients and determine whether differences are asthma specific or caused by "inflamm-aging."

METHODS

We performed a prospective study of aged (>60 years) and younger (21-40 years) inner-city patients with asthma. After a run-in period to control for inhaled corticosteroid use, induced sputum was collected. Age-matched nonasthmatic control subjects were included to measure age-related inflammatory changes.

RESULTS

Aged (mean age, 67.9 ± 5.1 years; n = 35) compared with younger (mean age, 30.8 ± 5.9 years; n = 37) asthmatic patients had significantly worse asthma control and lower FEV₁. Aged asthmatic patients had higher sputum neutrophil (30.5 × 10⁴/mL and 23.1%) and eosinophil (7.0 × 10⁴/mL and 3.8%) numbers and percentages compared with younger patients (neutrophils, 13.0 × 10⁴/mL [P < .01] and 6.9% [P < .01]; eosinophils, 2.0 × 10⁴/mL [P < .01] and 1.2% [P < .01]). Aged asthmatic patients had higher sputum IL-6 (P < .01) and IL-8 (P = .01) levels. No significant inflammatory differences between aged and younger control subjects were observed. In aged asthmatic patients increased sputum IL-6 and macrophage inflammatory protein 3α/CCL20 levels were significantly associated with decreased asthma control and increased sputum neutrophil numbers and IL-1β, IL-6, and macrophage inflammatory protein 3α/CCL20 levels were associated with hospitalization.

CONCLUSIONS

The inflammatory patterns of aged versus younger asthmatic patients are associated with increased sputum neutrophil and eosinophil values and cytokine levels related to neutrophil recruitment. Differences in airway inflammation can contribute to diminished asthma control in the aged. Further understanding of asthma pathophysiology in aged patients is needed to improve management of this vulnerable population.

Prenatal Stress, Prematurity, and Asthma

Asthma is the most common chronic disease of childhood, affecting millions of children in the United States and worldwide. Prematurity is a risk factor for asthma, and certain ethnic or racial minorities such as Puerto Ricans and non-Hispanic blacks are disproportionately affected by both prematurity and asthma. In this review, we examine current evidence to support maternal psychosocial stress as a putative link between prematurity and asthma, while also focusing on disruption of the hypothalamic-pituitary-adrenal (HPA) axis and immune responses as potential underlying mechanisms for stress-induced "premature asthma." Prenatal stress may cause not only abnormalities in the HPA axis but also epigenetic changes in the fetal glucocorticoid receptor gene (NR3C1), leading to impaired glucocorticoid metabolism. Moreover, maternal stress can alter fetal cytokine balance, favoring TH2 (allergic) immune responses characteristic of atopic asthma: interleukin 6 (IL-6), which has been associated with premature labor, can promote TH2 responses by stimulating production of IL-4 and IL-13. Given a link among stress, prematurity, and asthma, future research should include birth cohorts aimed at confirming and better characterizing "premature asthma." If confirmed, clinical trials of prenatal maternal stress reduction would be warranted to reduce the burden of these common comorbidities. While awaiting the results of such studies, sound policies to prevent domestic and community violence (eg, from firearms) are justified, not only by public safety but also by growing evidence of detrimental effects of violence-induced stress on psychiatric and somatic health.

Inflammatory effects induced by selected limonene oxidation products: 4-OPA, IPOH, 4-AMCH in human bronchial (16HBE14o-) and alveolar (A549) epithelial cell lines

Limonene, a monoterpene abundantly present in most of the consumer products (due to its pleasant citrus smell), easily undergoes ozonolysis leading to several limonene oxidation products (LOPs) such as 4-acetyl-1-methylcyclohexene (4-AMCH), 4-oxopentanal (4-OPA) and 3-isopropenyl-6-oxoheptanal (IPOH). Toxicological studies have indicated that human exposure to limonene and ozone can cause adverse airway effects. However, little attention has been paid to the potential health impact of specific LOPs, in particular of IPOH, 4-OPA and 4-AMCH. This study evaluates the cytotoxic effects of the selected LOPs on human bronchial epithelial (16HBE14o-) and alveolar epithelial (A549) cell lines by generating concentration-response curves using the neutral red uptake assay and analyzing the inflammatory response with a series of cytokines/chemokines. The cellular viability was mostly reduced by 4-OPA [IC₅₀=1.6mM (A549) and 1.45mM (16HBE14o-)] when compared to IPOH [IC₅₀=3.5mM (A549) and 3.4mM (16HBE14o-)] and 4-AMCH [IC₅₀ could not be calculated]. As a result from the inflammatory response, IPOH [50μM] induced an increase of both IL-6 and IL-8 secretion in A549 (1.5-fold change) and in 16HBE14o- (2.8- and 7-fold change respectively). 4-OPA [50μM] treatment of A549 increased IL-6 (1.4-times) and IL-8 (1.3-times) levels, while in 16HBE14o- had an opposite effect. A549 treated with 4-AMCH [50μM] elevate both IL-6 and IL-8 levels by 1.2-times, while in 16HBE14o- had an opposite effect. Based on our results, lung cellular injury characterized by inflammatory cytokine release was observed for both cell lines treated with the selected chemicals at concentrations that did not affect their cellular viability.

MyD88 modulates eosinophil and neutrophil recruitment as well as IL-17A production during allergic inflammation

The contribution of dysregulated innate immune responses to the pathogenesis of allergic disease remains largely unknown. Herein, we addressed the role of Toll-like receptor signaling in airway inflammation by studying mice rendered deficient for the myeloid differentiation factor 88 (MyD88^-/-) which results in concurrent deficiencies in TLR and IL-1R1 signaling pathways. We show that the lack of MyD88 offers a partial protection from allergic disease evidenced by reduced airway eosinophilia and production of the Th17-associated effector cytokine IL-17A. By contrast, airway hyperreactivity and Th2 cytokine production, the cardinal features of allergic disease, remained unchanged. We found that the impaired IL-17A production in MyD88^-/- mice was associated with defective CD4⁺ T cells, which failed to respond to IL-23 stimulation. The total number of Th17-associated effectors in lymph nodes was likewise decreased. Taken together, our results demonstrate that MyD88-dependent mechanisms are critical for orchestrating lung inflammatory responses, in terms of IL-17A production, as well as eosinophil and neutrophil recruitment.

Comorbidities and elevated IL-6 associate with negative outcome in adult-onset asthma

The effect of systemic inflammation and comorbidities on treatment and outcome of adult-onset asthma remains unknown and is the objective of this study.As part of the Seinäjoki Adult Asthma Study (SAAS) with a 12-year follow-up, serum interleukin (IL)-6, high-sensitivity C-reactive protein (hsCRP) and lung function were measured and clinical information on comorbidities and medication collected from 170 patients with adult-onset asthma without chronic obstructive pulmonary disease.At follow-up visit, 54% of the patients had systemic inflammation as indicated by elevated IL-6 or hsCRP, 58% had at least one comorbidity and 30% at least two comorbidities (other than asthma related). Patients with systemic inflammation were treated with higher dose of inhaled corticosteroid (ICS) and they had lower lung function and higher blood neutrophils compared with patients without. Patients having ≥2 comorbidities had lower Asthma Control Test score and this association remained significant in adjusted analysis. Patients with both systemic inflammation and comorbidities showed poorest outcome of asthma. In multivariate regression analysis, high ICS dose was predicted by elevated IL-6, elevated blood neutrophils and eosinophils and poorer lung function at baseline and follow-up.Altogether, in patients with adult-onset asthma, elevated IL-6 was associated with use of high-dose ICS while multi-morbidity was linked to worse symptoms of asthma.

Patient stratification and the unmet need in asthma

Asthma is often described as an inflammatory disease of the lungs and in most patients symptomatic treatment with bronchodilators or inhaled corticosteroids is sufficient to control disease. Unfortunately there are a proportion of patients who fail to achieve control despite treatment with the best current treatment. These severe asthma patients have been considered a homogeneous group of patients that represent the unmet therapeutic need in asthma. Many novel therapies have been tested in unselected asthma patients and the effects have often been disappointing, particularly for the highly specific monoclonal antibody-based drugs such as anti-IL-13 and anti-IL-5. More recently, it has become clear that asthma is a syndrome with many different disease drivers. Clinical trials of anti-IL-13 and anti-IL-5 have focused on biomarker-defined patient groups and these trials have driven the clinical progression of these drugs. Work on asthma phenotyping indicates that there is a group of asthma patients where T helper cell type 2 (Th2) cytokines and inflammation predominate and these type 2 high (T2-high) patients can be defined by biomarkers and response to therapies targeting this type of immunity, including anti-IL-5 and anti-IL-13. However, there is still a subset of T2-low patients that do not respond to these new therapies. This T2-low group will represent the new unmet medical need now that the T2-high-targeting therapies have made it to the market. This review will examine the current thinking on patient stratification in asthma and the identification of the T2-high subset. It will also look at the T2-low patients and examine what may be the drivers of disease in these patients.

The Coagulant Factor Xa Induces Protease-Activated Receptor-1 and Annexin A2-Dependent Airway Smooth Muscle Cytokine Production and Cell Proliferation

During asthma exacerbation, plasma circulating coagulant factor X (FX) enters the inflamed airways and is activated (FXa). FXa may have an important role in asthma, being involved in thrombin activation and an agonist of protease-activated receptor-1 (PAR-1). Extracellular annexin A2 and integrins are also implicated in PAR-1 signaling. In this study, the potential role of PAR-1 in mediating the effects of FXa on human airway smooth muscle (ASM) cell cytokine production and proliferation was investigated. FXa (5-50 nM), but not FX, stimulated increases in ASM IL-6 production and cell number after 24- and 48-hour incubation, respectively (P < 0.05; n = 5). FXa (15 nM) also stimulated increases in the levels of mRNA for cytokines (IL-6), cell cycle-related protein (cyclin D1), and proremodeling proteins (FGF-2, PDGF-B, CTGF, SM22, and PAI-1) after 3-hour incubation (P < 0.05; n = 4). The actions of FXa were insensitive to inhibition by hirudin (1 U/ml), a selective thrombin inhibitor, but were attenuated by SCH79797 (100 nM), a PAR-1 antagonist, or Cpd 22 (1 μM), an inhibitor of integrin-linked kinase. The selective targeting of PAR-1, annexin A2, or β1-integrin by small interfering RNA and/or by functional blocking antibodies also attenuated FXa-evoked responses. In contrast, the targeting of annexin A2 did not inhibit thrombin-stimulated ASM function. In airway biopsies of patients with asthma, FXa and annexin A2 were detected in the ASM bundle by immunohistochemistry. These findings establish FXa as a potentially important asthma mediator, stimulating ASM function through actions requiring PAR-1 and annexin A2 and involving integrin coactivation.

Effects of omega-3 fatty acids on serum levels of T-helper cytokines in children with asthma

BACKGROUND

There has been a considerable interest in the potential therapeutic value of dietary supplementation with ω-3 fatty acids in patients with asthma.

OBJECTIVES

This cross-sectional study was designed to identify the effect of ω-3 fatty acids on symptom score, pulmonary function and serum T-helper cytokine concentrations in children with mild to moderate persistent asthma.

METHODS

A total of 39 patients among 50 volunteers completed this 3-month study. They took a soft gel capsule containing 180mg EPA and 120mg DHA daily. Pulmonary function was evaluated in 28 eligible patients by spirometry, and serum levels of Th1, Th2, Th9, Th17 and Th22 cytokines were measured by multiplex cytometric bead assay before and after treatment.

RESULTS

After treatment with ω-3, symptom score improved in 28 (72%) patients. The results of spirometry showed remarkable improvement in FEV1/FVC (P=0.044) and PEF (P<0.0001) after treatment, but considering a cut-off of 80%, real improvement was observed in 32% of patients with PEF<80% which raised above the cut-off after ω-3 treatment (P=0.004) whereas, FEV1/FVC changes were above the cut-off value in 89% of the patients. After treatment, IL-17A and TNF-α levels decreased significantly (both P=0.049).

CONCLUSION

Oral administration of natural anti-inflammatory products such as ω-3 is a promising complementary approach to managing asthma.

Identifying a biomarker network for corticosteroid resistance in asthma from bronchoalveolar lavage samples

Corticosteroid resistance (CR) is a major barrier to the effective treatment of severe asthma. Hence, a better understanding of the molecular mechanisms involved in this condition is a priority. Network analysis is an emerging strategy to explore this complex heterogeneous disorder at system level to identify a small own network for CR in asthma. Gene expression profile of GSE7368 from bronchoalveolar lavage (BAL) of CR in subjects with asthma was downloaded from the gene expression omnibus (GEO) database and compared to BAL of corticosteroid-sensitive (CS) patients. DEGs were identified by the Limma package in R language. In addition, DEGs were mapped to STRING to acquire protein-protein interaction (PPI) pairs. Topological properties of PPI network were calculated by Centiscape, ClusterOne and BINGO. Subsequently, text-mining tools were applied to design one own cell signalling for CR in asthma. Thirty-five PPI networks were obtained; including a major network consisted of 370 nodes, connected by 777 edges. After topological analysis, a minor PPI network composed by 48 nodes was indentified, which is composed by most relevant nodes of major PPI network. In this subnetwork, several receptors (EGFR, EGR1, ESR2, PGR), transcription factors (MYC, JAK), cytokines (IL8, IL6, IL1B), one chemokine (CXCL1), one kinase (SRC) and one cyclooxygenase (PTGS2) were described to be associated with inflammatory environment and steroid resistance in asthma. We suggest a biomarker network composed by 48 nodes that could be potentially explored with diagnostic or therapeutic use.

Human bronchial and parenchymal fibroblasts display differences in basal inflammatory phenotype and response to IL-17A

BACKGROUND

Chronic inflammation, typified by increased expression of IL-17A, together with airway and parenchymal remodelling are features of chronic lung diseases. Emerging evidence suggests that phenotypic heterogeneity of repair and inflammatory capacities of fibroblasts may contribute to the differential structural changes observed in different regions of the lung.

OBJECTIVE

To investigate phenotypic differences in parenchymal and bronchial fibroblasts, either in terms of inflammation and remodelling or the ability of these fibroblasts to respond to IL-17A.

METHODS

Four groups of primary fibroblasts were used: normal human bronchial fibroblast (NHBF), normal human parenchymal fibroblast (NHPF), COPD human bronchial fibroblast (CHBF) and COPD human parenchymal fibroblast (CHPF). Cytokine and extracellular matrix (ECM) expression were measured at baseline and after stimulation with IL-17A. Actinomycin D was used to measure cytokine mRNA stability.

RESULTS

At baseline, we observed higher protein production of IL-6 in NHPF than NHBF, but higher levels of IL-8 and GRO-α in NHBF. IL-17A induced a higher expression of GRO-α (CXCL1) and IL-6 in NHPF than in NHBF, and a higher level of IL-8 expression in NHBF. IL-17A treatment decreased the mRNA stability of IL-6 in NHBF when compared with NHPF. CHPF expressed higher protein levels of fibronectin, collagen-I and collagen-III than CHBF, NHBF and NHPF. IL-17A increased fibronectin and collagen-III protein only in NHPF and collagen-III protein production in CHBF and CHPF.

CONCLUSIONS AND CLINICAL RELEVANCE

These findings provide insight into the inflammatory and remodelling processes that may be related to the phenotypic heterogeneity of fibroblasts from airway and parenchymal regions and in their response to IL-17A.

Effect of a chemical chaperone, tauroursodeoxycholic acid, on HDM-induced allergic airway disease

Endoplasmic reticulum (ER) stress-induced unfolded protein response plays a critical role in inflammatory diseases, including allergic airway disease. However, the benefits of inhibiting ER stress in the treatment of allergic airway disease are not well known. Herein, we tested the therapeutic potential of a chemical chaperone, tauroursodeoxycholic acid (TUDCA), in combating allergic asthma, using a mouse model of house dust mite (HDM)-induced allergic airway disease. TUDCA was administered during the HDM-challenge phase (preventive regimen), after the HDM-challenge phase (therapeutic regimen), or therapeutically during a subsequent HDM rechallenge (rechallenge regimen). In the preventive regimen, TUDCA significantly decreased HDM-induced inflammation, markers of ER stress, airway hyperresponsiveness (AHR), and fibrosis. Similarly, in the therapeutic regimen, TUDCA administration efficiently decreased HDM-induced airway inflammation, mucus metaplasia, ER stress markers, and AHR, but not airway remodeling. Interestingly, TUDCA administered therapeutically in the HDM rechallenge regimen markedly attenuated HDM-induced airway inflammation, mucus metaplasia, ER stress markers, methacholine-induced AHR, and airway fibrotic remodeling. These results indicate that the inhibition of ER stress in the lungs through the administration of chemical chaperones could be a valuable strategy in the treatment of allergic airway diseases.

Circulating Dendritic Cells, Farm Exposure and Asthma at Early Age

Farm environment has been shown to protect from childhood asthma. Underlying immunological mechanisms are not clear yet, including the role of dendritic cells (DCs). The aim was to explore whether asthma and farm exposures are associated with the proportions and functional properties of DCs from 4.5-year-old children in a subgroup of the Finnish PASTURE birth cohort study. Myeloid DCs (mDCs), plasmacytoid DCs (pDCs) and CD86 expression on mDCs ex vivo (n = 100) identified from peripheral blood mononuclear cells (PBMCs) were analysed using flow cytometry. MDCs and production of interleukin (IL)-6 and tumour necrosis factor alpha (TNF-α) by mDCs were analysed after 5 h in vitro stimulation with lipopolysaccharide (LPS) (n = 88). Prenatal and current farm exposures (farming, stables, hay barn and farm milk) were assessed from questionnaires. Asthma at age 6 years was defined as a doctor's diagnosis and symptoms; atopic sensitization was defined by antigen-specific IgE measurements. Asthma was positively associated with CD86 expression on mDCs ex vivo [adjusted odds ratio (aOR) 4.83, 95% confidence interval (CI) 1.51-15.4] and inversely with IL-6 production in mDCs after in vitro stimulation with LPS (aOR 0.19, 95% CI 0.04-0.82). In vitro stimulation with LPS resulted in lower percentage of mDCs in the farm PBMC cultures as compared to non-farm PBMC cultures. Our results suggest an association between childhood asthma and functional properties of DCs. Farm exposure may have immunomodulatory effects by decreasing mDC proportions.

Blockade of STAT3 in T Cells Inhibits Germinal Center Reactions against Intranasal Allergens

Understanding the developmental mechanisms of humoral immunity against intranasal antigens is essential for the development of therapeutic approaches against air-borne pathogens as well as allergen-induced pulmonary inflammation. Follicular helper T (Tfh) cells expressing CXCR5 are required for humoral immunity by providing IL-21 and ICOS costimulation to activated B cells. However, the regulation of Tfh cell responses against intranasal antigens remains unclear. Here, we found that the generation of Tfh cells and germinal center B cells in the bronchial lymph node against intranasal proteinase antigens was independent of TGF-β. In contrast, administration of STAT3 inhibitor STA-21 suppressed the generation of Tfh cells and germinal center B cells. Compared with wild-type OT-II T cells, STAT3-deficient OT-II T cells transferred into recipients lacking T cells not only showed significantly reduced frequency Tfh cells, but also induced diminished IgG as well as IgE specific for the intranasal antigens. Cotransfer study of wild-type OT-II and STAT3-deficient OT-II T cells revealed that the latter failed to differentiate into Tfh cells. These findings demonstrate that T cell-intrinsic STAT3 is required for the generation of Tfh cells to intranasal antigens and that targeting STAT3 might be an effective approach to ameliorate antibody-mediated pathology in the lung.

Emerging Comorbidities in Adult Asthma: Risks, Clinical Associations, and Mechanisms

Asthma is a heterogeneous disease with many phenotypes, and age at disease onset is an important factor in separating the phenotypes. Most studies with asthma have been performed in patients being otherwise healthy. However, in real life, comorbid diseases are very common in adult patients. We review here the emerging comorbid conditions to asthma such as obesity, metabolic syndrome, diabetes mellitus type 2 (DM2), and cardiac and psychiatric diseases. Their role as risk factors for incident asthma and whether they affect clinical asthma are evaluated. Obesity, independently or as a part of metabolic syndrome, DM2, and depression are risk factors for incident asthma. In contrast, the effects of comorbidities on clinical asthma are less well-known and mostly studies are lacking. Cross-sectional studies in obese asthmatics suggest that they may have less well controlled asthma and worse lung function. However, no long-term clinical follow-up studies with these comorbidities and asthma were identified. These emerging comorbidities often occur in the same multimorbid adult patient and may have in common metabolic pathways and inflammatory or other alterations such as early life exposures, systemic inflammation, inflammasome, adipokines, hyperglycemia, hyperinsulinemia, lung mechanics, mitochondrial dysfunction, disturbed nitric oxide metabolism, and leukotrienes.

Early-onset obesity dysregulates pulmonary adipocytokine/insulin signaling and induces asthma-like disease in mice

Childhood obesity is a risk factor for asthma, but the molecular mechanisms linking both remain elusive. Since obesity leads to chronic low-grade inflammation and affects metabolic signaling we hypothesized that postnatal hyperalimentation (pHA) induced by maternal high-fat-diet during lactation leads to early-onset obesity and dysregulates pulmonary adipocytokine/insulin signaling, resulting in metabolic programming of asthma-like disease in adult mice. Offspring with pHA showed at postnatal day 21 (P21): (1) early-onset obesity, greater fat-mass, increased expression of IL-1β, IL-23, and Tnf-α, greater serum leptin and reduced glucose tolerance than Control (Ctrl); (2) less STAT3/AMPKα-activation, greater SOCS3 expression and reduced AKT/GSK3β-activation in the lung, indicative of leptin resistance and insulin signaling, respectively; (3) increased lung mRNA of IL-6, IL-13, IL-17A and Tnf-α. At P70 body weight, fat-mass, and cytokine mRNA expression were similar in the pHA and Ctrl, but serum leptin and IL-6 were greater, and insulin signaling and glucose tolerance impaired. Peribronchial elastic fiber content, bronchial smooth muscle layer, and deposition of connective tissue were not different after pHA. Despite unaltered bronchial structure mice after pHA exhibited significantly increased airway reactivity. Our study does not only demonstrate that early-onset obesity transiently activates pulmonary adipocytokine/insulin signaling and induces airway hyperreactivity in mice, but also provides new insights into metabolic programming of childhood obesity-related asthma.

D-Dimer Levels before HIV Seroconversion Remain Elevated Even after Viral Suppression and Are Associated with an Increased Risk of Non-AIDS Events

The mechanism underlying the excess risk of non-AIDS diseases among HIV infected people is unclear. HIV associated inflammation/hypercoagulability likely plays a role. While antiretroviral therapy (ART) may return this process to pre-HIV levels, this has not been directly demonstrated. We analyzed data/specimens on 249 HIV+ participants from the US Military HIV Natural History Study, a prospective, multicenter observational cohort of >5600 active duty military personnel and beneficiaries living with HIV. We used stored blood specimens to measure D-dimer and Interleukin-6 (IL-6) at three time points: pre-HIV seroconversion, ≥6 months post-HIV seroconversion but prior to ART initiation, and ≥6 months post-ART with documented HIV viral suppression on two successive evaluations. We evaluated the changes in biomarker levels between time points, and the association between these biomarker changes and future non-AIDS events. During a median follow-up of 3.7 years, there were 28 incident non-AIDS diseases. At ART initiation, the median CD4 count was 361cells/mm³; median duration of documented HIV infection 392 days; median time on ART was 354 days. Adjusted mean percent increase in D-dimer levels from pre-seroconversion to post-ART was 75.1% (95% confidence interval 24.6–148.0, p = 0.002). This increase in D-dimer was associated with a significant 22% increase risk of future non-AIDS events (p = 0.03). Changes in IL-6 levels across time points were small and not associated with future non-AIDS events. In conclusion, ART initiation and HIV viral suppression does not eliminate HIV associated elevation in D-dimer levels. This residual pathology is associated with an increased risk of future non-AIDS diseases.

Interactions of Aspergillus fumigatus Conidia with Airway Epithelial Cells: A Critical Review

Aspergillus fumigatus is an environmental filamentous fungus that also acts as an opportunistic pathogen able to cause a variety of symptoms, from an allergic response to a life-threatening disseminated fungal infection. The infectious agents are inhaled conidia whose first point of contact is most likely to be an airway epithelial cell (AEC). The interaction between epithelial cells and conidia is multifaceted and complex, and has implications for later steps in pathogenesis. Increasing evidence has demonstrated a key role for the airway epithelium in the response to respiratory pathogens, particularly at early stages of infection; therefore, elucidating the early stages of interaction of conidia with AECs is essential to understand the establishment of infection in cohorts of at-risk patients. Here, we present a comprehensive review of the early interactions between A. fumigatus and AECs, including bronchial and alveolar epithelial cells. We describe mechanisms of adhesion, internalization of conidia by AECs, the immune response of AECs, as well as the role of fungal virulence factors, and patterns of fungal gene expression characteristic of early infection. A clear understanding of the mechanisms involved in the early establishment of infection by A. fumigatus could point to novel targets for therapy and prophylaxis.

Erythronium japonicum attenuates histopathological lung abnormalities in a mouse model of ovalbumin-induced asthma

Asthma is a chronic lung condition that can induce mucus hypersecretion and pulmonary obstruction and may even cause death, particularly in children and older individuals. Erythronium japonicum (E. japonicum) is a traditional herb used in Korea and East Asian countries that has been found to exert free radical scavenging activity and anti-proliferative effects in human colorectal carcinoma cells. In the present study, we evaluated the anti-asthmatic effects of an extract of E. japonicum in a mouse model of ovalbumin (OVA)-induced asthma. Female BALB/c mice were sensitized with an intraperitoneal injection of OVA and aluminum hydroxide hydrate on days 1 and 8 and then received the following treatments on days 21 to 25: i) control (no treatment), ii) sterilized tap water (given orally), iii) 1 mg/kg/day dexamethasone (administered orally), iv) 60 mg/kg/day E. japonicum extract, and v) 600 mg/kg/day E. japonicum extract. On the same days, all the mice except those in the control group were challenged 1 h later with nebulized 5% OVA for 30 min. We found that treatment with E. japonicum extract suppressed the OVA-induced increase in the number of white blood cells and decreased the IgE level in the bronchoalveolar lavage fluid samples obtained from the mice. Histopathological analysis of the lung tissues revealed that E. japonicum attenuated the asthma-related morphological changes in the mouse lung tissue, including the increased secretion of mucus in the bronchioles, eosinophil infiltration around the bronchioles and vessels, and goblet cell and epithelial cell hyperplasia. Immunohistochemical analysis revealed that treatment with E. japonicum extract suppressed the OVA-induced proliferation of T helper cells (CD4⁺) and B cells (CD19⁺) in the mouse lung tissue. Furthermore, treatment with E. japonicum extract modulated the expression of both T helper 2 cell-related factors [GATA binding protein 3 (GATA-3), tumor necrosis factor-α (TNF-α), interleukin (IL)-4, IL-5, IL-6 and IL-13], as well as that of T helper 1 cell-related factors [(interferon-γ (IFN-γ), IL-12p35 and IL-12p40]. These findings suggest that E. japonicum may potentially be used as an anti-asthmatic treatment.

The IL6R gene polymorphisms are associated with sIL-6R, IgE and lung function in Chinese patients with asthma

BACKGROUND

sIL-6R is involved in a variety of inflammatory diseases. The present study analyzed the potential associations between two IL6R gene polymorphisms (rs2228145 and rs12083537) and asthma in a Han Chinese population.

METHODS

A cohort of 394 patients and 395 healthy controls were genotyped to detect the two polymorphisms using SNaPshot. In 66 asthma patients and 49 controls, peripheral eosinophil and serum immunoglobulin E (IgE) levels were determined using a routine blood test, and sIL-6R levels were measured by ELISA.

RESULTS

No statistically significant differences were detected between the patients and controls in the distribution of the two independent IL6R polymorphisms (p>0.05). However, rs2228145 C and rs12083537 G were significantly associated with decreased lung function in patients with asthma; the rs2228145 A-C variant was also associated with increased sIL-6R and IgE levels. In addition, sIL-6R levels were positively associated with IgE and inversely associated with lung function in patients with asthma.

CONCLUSIONS

Our results provide evidence that rs2228145 C and rs12083537 G are associated with poor lung function in patients with asthma. Furthermore, the rs2228145 A-C variant is associated with levels of sIL-6R and IgE.

Sex-specific IL-6-associated signaling activation in ozone-induced lung inflammation

Background

Acute ozone (O₃) exposure has known deleterious effects on the respiratory system and has been linked with respiratory disease and infection. Inflammatory lung disease induced by air pollution has demonstrated greater severity and poorer prognosis in women vs. men. Both severe damage to the bronchial-alveolar epithelium and malfunctioning of bronchial-blood barrier have been largely attributed to the pathobiology of O₃-induced inflammatory response, but the associated mechanisms in the male and female lung remain unknown.

Methods

Here, we investigated sex-based differential regulation of lung interleukin-6 (IL-6) and its downstream signaling pathways JAK2/STAT3 and AKT1/NF-κB in response to O₃ exposure in a mouse model. We exposed male and female mice (in different stages of the estrous cycle) to 2 ppm of O₃ or filtered air (FA) for 3 h, and we harvested lung tissue for protein expression analysis by Western blot.

Results

We found significant up-regulation of IL-6 and IL-6R in females and IL-6 in males in response to O₃ vs. FA. Ozone exposure induced a significant increase in STAT3-Y705 phosphorylation in both females and males. Males exposed to O₃ had decreased levels of JAK2, but increased JAK2 (Y1007+Y1008) phosphorylation, while females exposed to O₃ showed significant up-regulation of both proteins. Both NF-κB (p105/p50) and AKT1 protein levels were significantly increased only in females exposed to O₃. In addition, females exposed to O₃ during proestrus displayed increased expression of selected genes when compared to females exposed to O₃ in other estrous cycle stages.

Conclusions

Together, our observations indicate a sex-based and estrous cycle-dependent differential lung inflammatory response to O₃ and involvement of two converging JAK2/STAT3 and AKT1/NF-κB pathways. To our knowledge, this is the first study specifically addressing the impact of the estrous cycle in O₃-associated lung inflammatory pathways.

Electronic supplementary material

The online version of this article (doi:10.1186/s13293-016-0069-7) contains supplementary material, which is available to authorized users.

Interleukin 6 SNP rs1800797 associates with the risk of adult-onset asthma

Interleukin 6 (IL6) is an inflammatory cytokine that has been suggested to have an important role in the pathogenesis of asthma. IL6 single-nucleotide polymorphisms (SNPs) have been associated with levels of IL6, and with childhood and prevalent adult asthma. A recent study also suggested that IL6 SNPs associate especially with atopic asthma. However, association of IL6 SNPs with adult-onset asthma has not been studied. In a population-based study of 467 incident adult-onset asthma cases and 613 disease-free controls from South Finland, we analyzed association of 6 tagging SNPs of the IL6 locus with the risk of adult-onset asthma and with atopy. Asthma was clinically diagnosed, and atopy was defined based on Phadiatop test. IL6 SNP rs1800797 associated with the risk of adult-onset asthma in a log additive model, with adjusted odds ratio (aOR) 1.31 (95% confidence interval 1.09-1.57), and especially with the risk of atopic adult-onset asthma when compared with non-atopic controls, aOR 1.46 (95% CI 1.12-1.90). This is the first study to show an association of IL6 with adult-onset asthma, and especially with atopic adult-onset asthma.

Ten-eleven translocation 1 (TET1) methylation is associated with childhood asthma and traffic-related air pollution

BACKGROUND

Asthma is a complex disorder influenced by genetics and the environment. Recent findings have linked abnormal DNA methylation in T cells with asthma; however, the potential dysregulation of methylation in airway epithelial cells is unknown. Studies of mouse models of asthma have observed greater levels of 5-hydroxymethylcytosine (5-hmC) and ten-eleven translocation 1 (TET1) expression in lungs. TET proteins are known to catalyze methylation through modification of 5-methylcytosine to 5-hmC.

OBJECTIVE

We sought to examine the association of TET1 methylation with asthma and traffic-related air pollution (TRAP).

METHODS

TET1 methylation levels from DNA derived from nasal airway epithelial cells collected from 12 African American children with physician-diagnosed asthma and their nonasthmatic siblings were measured by using Illumina 450K arrays. Regions of interest were verified by means of locus-specific pyrosequencing in 35 sibling pairs and replicated in an independent population (n = 186). Exposure to TRAP in participants' early life and at current home addresses was estimated by using a land-use regression model. Methylation studies in saliva, PBMCs, and human bronchial epithelial cells were done to support our findings.

RESULTS

Loss of methylation at a single CpG site in the TET1 promoter (cg23602092) and increased global 5-hmC levels were significantly associated with asthma. In contrast, TRAP exposure at participants' current homes significantly increased methylation at the same site. Patterns were consistent across tissue sample types. 5-Aza-2'-deoxycytidine and diesel exhaust particle exposure in human bronchial epithelial cells was associated with altered TET1 methylation and expression and global 5-hmC levels.

CONCLUSIONS

Our findings suggest a possible role of TET1 methylation in asthmatic patients and response to TRAP.

CD11b+ and Sca-1+ Cells Exert the Main Beneficial Effects of Systemically Administered Bone Marrow-Derived Mononuclear Cells in a Murine Model of Mixed Th2/Th17 Allergic Airway Inflammation

A murine model of severe clinical asthma was used to study which bone marrow-derived mononuclear cells (BMDMCs) are responsible for ameliorating airway hyperresponsiveness and lung inflammation. BMDMCs depleted of either CD11b-positive cells (monocytes, macrophages, dendritic cells) or Sca-1-positive cells (bone marrow-derived mesenchymal stromal cells) were unable to ameliorate these conditions in this model. Depletion of the other cell types did not diminish the ameliorating effects of BMDMC administration.

Systemic administration of bone marrow-derived mononuclear cells (BMDMCs) or bone marrow-derived mesenchymal stromal cells (MSCs) reduces inflammation and airway hyperresponsiveness (AHR) in a murine model of Th2-mediated eosinophilic allergic airway inflammation. However, since BMDMCs are a heterogeneous population that includes MSCs, it is unclear whether the MSCs alone are responsible for the BMDMC effects. To determine which BMDMC population(s) is responsible for ameliorating AHR and lung inflammation in a model of mixed Th2-eosinophilic and Th17-neutrophilic allergic airway inflammation, reminiscent of severe clinical asthma, BMDMCs obtained from normal C57Bl/6 mice were serially depleted of CD45, CD34, CD11b, CD3, CD19, CD31, or Sca-1 positive cells. The different resulting cell populations were then assessed for ability to reduce lung inflammation and AHR in mixed Th2/Th17 allergic airway inflammation induced by mucosal sensitization to and challenge with Aspergillus hyphal extract (AHE) in syngeneic C56Bl/6 mice. BMDMCs depleted of either CD11b-positive (CD11b+) or Sca-1-positive (Sca-1+) cells were unable to ameliorate AHR or lung inflammation in this model. Depletion of the other cell types did not diminish the ameliorating effects of BMDMC administration. In conclusion, in the current model of allergic inflammation, CD11b+ cells (monocytes, macrophages, dendritic cells) and Sca-1+ cells (MSCs) are responsible for the beneficial effects of BMDMCs.

Significance

This study shows that bone marrow-derived mononuclear cells (BMDMCs) are as effective as bone marrow-derived mesenchymal stromal cells (MSCs) in ameliorating experimental asthma. It also demonstrates that not only MSCs present in the pool of BMDMCs are responsible for BMDMCs’ beneficial effects but also monocytes, which are the most important cell population to trigger these effects. All of this is in the setting of a clinically relevant model of severe allergic airways inflammation and thus provides further support for potential clinical use of cell therapy using MSCs, BMDMCs, and also adult cells such as monocytes in patients with severe asthma.

Alternative Roles of STAT3 and MAPK Signaling Pathways in the MMPs Activation and Progression of Lung Injury Induced by Cigarette Smoke Exposure in ACE2 Knockout Mice

Inflammation-mediated abnormalities in the renin-angiotensin system (RAS) and expression of matrix metalloproteinases (MMPs) are implicated in the pathogenesis of lung injury. Angiotensin converting enzyme II (ACE2), an angiotensin converting enzyme (ACE) homologue that displays antagonist effects on ACE/angiotensin II (Ang II) axis, could also play a protective role against lung diseases. However, the relationship between ACE2 and MMPs activation in lung injury is still largely unclear. The purpose of this study is to investigate whether MMPs activity could be affected by ACE2 and which ACE2 derived signaling pathways could be also involved via using a mouse model with lung injury induced by cigarette smoke (CS) exposure for 1 to 3 weeks. Wild-type (WT; C57BL/6) and ACE2 KO mice (ACE2^-/-) were utilized to study CS-induced lung injury. Increases in the resting respiratory rate (RRR), pulmonary immunokines, leukocyte infiltration and bronchial hyperplasia were observed in the CS-exposed mice. Compared to WT mice, more serious physiopathological changes were found in ACE2^-/- mice in the first week of CS exposure. CS exposure increased pulmonary ACE and ACE2 activities in WT mice, and significantly increased ACE in ACE2^-/- mice. Furthermore, the activity of pulmonary MMPs was decreased in CS-exposed WT mice, whereas this activity was increased in ACE2^-/- mice. CS exposure increased the pulmonary p-p38, p-JNK and p-ERK1/2 level in all mice. In ACE2^-/- mice, a significant increase p-STAT3 signaling was detected; however, no effect was observed on the p-STAT3 level in WT mice. Our results support the hypothesis that ACE2 deficiency influences MMPs activation and STAT3 phosphorylation signaling to promote more pulmonary inflammation in the development of lung injury.

The control of tissue fibrosis by the inflammatory molecule LIGHT (TNF Superfamily member 14)

The TNF Superfamily member LIGHT (TNFSF14) has recently emerged as a potential target for therapeutic interventions aiming to halt tissue fibrosis. In this perspective, we discuss how LIGHT may influence the inflammatory and remodeling steps that characterize fibrosis, relevant for many human diseases presenting with scarring such as asthma, idiopathic pulmonary fibrosis, systemic sclerosis, and atopic dermatitis. LIGHT acts through two receptors in the TNF receptor superfamily, HVEM (TNFRSF14) and LTβR (TNFRSF3), which are broadly expressed on hematopoietic and non-hematopoietic cells. LIGHT can regulate infiltrating T cells, macrophages, and eosinophils, controlling their trafficking or retention in the inflamed tissue, their proliferation, and their ability to produce cytokines that amplify fibrotic processes. More interestingly, LIGHT can act on structural cells, namely epithelial cells, fibroblasts, smooth muscle cells, adipocytes, and endothelial cells. By signaling through either HVEM or LTβR expressed on these cells, LIGHT can contribute to their proliferation and expression of chemokines, growth factors, and metalloproteinases. This will lead to hyperplasia of epithelial cells, fibroblasts, and smooth muscle cells, deposition of extracellular matrix proteins, vascular damage, and further immune alterations that in concert constitute fibrosis. Because of its early expression by T cells, LIGHT may be an initiator of fibrotic diseases, but other sources in the immune system could also signify a role for LIGHT in maintaining or perpetuating fibrotic activity. LIGHT may then be an attractive prognostic marker as well as an appealing target for fibrosis therapies relevant to humans.

Chronic obstructive pulmonary disease induced by exposure to biomass smoke is associated with a Th2 cytokine production profile

Smoking and exposure to biomass smoke induce the release of pro-inflammatory mediators and the activation of T helper cells. The resulting inflammatory response contributes to the development of COPD. Clinical heterogeneity exists among COPD patients, particularly between patients with disease associated with tobacco smoking (TS-COPD) and those exposed to biomass smoke (BE-COPD). The aim of this study was to identify whether exposure to tobacco and biomass smokes promotes different Th responses that contribute to clinical variability. The study only included women. The frequency of Th17 cells in patients with TS-COPD was significantly higher than in patients with BE-COPD and healthy controls (HC). In contrast, patients with BE-COPD had higher levels of Th2 cells than TS-COPD and HC. In accordance, IL-4 serum concentration was higher in BE-COPD than in TS-COPD. Our data indicates that the different responses induced by these two irritants may underlie the clinical heterogeneity between TS- and BE-COPD patients.

Risk of developing Parkinson's disease among patients with asthma: a nationwide longitudinal study

BACKGROUND

A cross-sectional retrospective study suggested a link between allergic diseases and Parkinson's disease. However, the temporal association between asthma and Parkinson's disease remains unknown.

METHODS

From the Taiwan National Health Insurance Research Database, 10 455 patients who were diagnosed with asthma between 1998 and 2008 and aged ≥45 years and 41 820 age- and sex-matched controls were selected for our study and observed until the end of 2011. Those who developed Parkinson's disease during the follow-up period were identified. We also examined the asthma severity, as indicated by the frequency of admission (times per year) for asthma exacerbation, and the risk of subsequent Parkinson's disease.

RESULTS

Patients with asthma had an increased risk of developing Parkinson's disease (hazard ratio [HR]: 3.10, 95% confidence interval [CI]: 2.20-4.36) after we adjusted for demographic data, health system use, medical comorbidities, and medication use. Sensitivity tests yielded consistent findings after we excluded observations on the first year (HR: 2.90, 95% CI: 2.04-4.13) and first 3 years (HR: 2.46, 95% CI: 1.64-3.69). Patients with asthma who had more frequent admissions (times per year) during the follow-up period exhibited a greater risk of subsequent Parkinson's disease (>2: HR: 16.42, 95% CI: 5.88-45.91; 1-2: 12.69, 95% CI: 5.03-31.71; 0-1: HR: 2.92, 95% CI: 1.91-4.49).

CONCLUSION

Patients with asthma had an elevated risk of developing Parkinson's disease later in life, and we observed a dose-dependent relationship between greater asthma severity and a higher risk of subsequent Parkinson's disease.

Systemic expression of inflammatory mediators in patients with chronic rhinosinusitis and nasal polyps with and without Aspirin Exacerbated Respiratory Disease

BACKGROUND

Systemic reactions are related to the pathogenesis of Aspirin Exacerbated Respiratory Disease (AERD). With this work we wanted to study the changes in the systemic levels of inflammatory mediators in both baseline and after oral aspirin challenge in patients with and without AERD.

METHODS

Patients with nasal polyposis and asthma with AERD (n=20) and without (n=18) were orally challenged with aspirin in a single-blind placebo controlled study. Serum samples and urine were collected before and 6h after placebo and aspirin oral challenges. Serum levels of inflammatory mediators were assayed by using the Luminex technology and ELISA. The concentrations of 9-alpha, 11-beta prostaglandin F2, and leukotriene E4 (uLTE4) were measured in urine samples by ELISA. The expression of T-cell surface markers was analyzed in peripheral blood mononuclear cells isolated before and after the challenges.

RESULTS

AERD patients showed significantly higher baseline levels of s-IL-5R-alpha, uLTE4 and percentage of CD4(+)CD25(+)CD127(pos) and CD4(+)CD45RA(-)CD45RO(+) but decreased levels of TGF-β1 and number of CD4(+)CD25(+)CD127(neg) cells. Aspirin challenge induced the release of uLTE4, IL-6 and increased the number of CD4(+)CD45RA(-)CD45RO(+) memory T-cells only in AERD patients but failed to reduce the levels of sCD40L as observed in non-AERD subjects. Further, IL-8 and sIL-5R-alpha levels directly correlated with the PD20ASA and the effects of aspirin on IL-6 and number of memory T-cells was more pronounced in subjects showing more strong reaction (bronchial and nasal).

CONCLUSIONS

AERD patients have a differential baseline inflammatory pattern that supports the role inflammation as underlying mechanism of the disease. Systemic response to oral aspirin challenge was related to an increase in serum IL-6 and the number of circulating memory T-cells in AERD patients.

Hypoxia-Inducible Factor 1α Is a Critical Downstream Mediator for Hypoxia-Induced Mitogenic Factor (FIZZ1/RELMα)-Induced Pulmonary Hypertension

OBJECTIVE

Pulmonary hypertension (PH) is characterized by progressive elevation of pulmonary vascular resistance, right ventricular failure, and ultimately death. We have shown that in rodents, hypoxia-induced mitogenic factor (HIMF; also known as FIZZ1 or resistin-like molecule-β) causes PH by initiating lung vascular inflammation. We hypothesized that hypoxia-inducible factor-1 (HIF-1) is a critical downstream signal mediator of HIMF during PH development.

APPROACH AND RESULTS

In this study, we compared the degree of HIMF-induced pulmonary vascular remodeling and PH development in wild-type (HIF-1α(+/+)) and HIF-1α heterozygous null (HIF-1α(+/-)) mice. HIMF-induced PH was significantly diminished in HIF-1α(+/-) mice and was accompanied by a dysregulated vascular endothelial growth factor-A-vascular endothelial growth factor receptor 2 pathway. HIF-1α was critical for bone marrow-derived cell migration and vascular tube formation in response to HIMF. Furthermore, HIMF and its human homolog, resistin-like molecule-β, significantly increased interleukin (IL)-6 in macrophages and lung resident cells through a mechanism dependent on HIF-1α and, at least to some extent, on nuclear factor κB.

CONCLUSIONS

Our results suggest that HIF-1α is a critical downstream transcription factor for HIMF-induced pulmonary vascular remodeling and PH development. Importantly, both HIMF and human resistin-like molecule-β significantly increased IL-6 in lung resident cells and increased perivascular accumulation of IL-6-expressing macrophages in the lungs of mice. These data suggest that HIMF can induce HIF-1, vascular endothelial growth factor-A, and interleukin-6, which are critical mediators of both hypoxic inflammation and PH pathophysiology.

Lariciresinol-4-O-β-D-glucopyranoside from the root of Isatis indigotica inhibits influenza A virus-induced pro-inflammatory response

ETHNOPHARMACOLOGICAL RELEVANCE

Isatis indigotica is a traditional Chinese medicine. Its dried roots named "ban lan gen" in Chinese, are used for clinical treatment of virus infection, tumor, inflammation with a long history. However, its anti-influenza active ingredient and the underlying mechanism remain unclear. In this study, the anti-influenza and anti-inflammatory effects of a lignan glycoside: lariciresinol-4-O-β-D-glucopyranoside isolated from the root of I. indigotica on human alveolar epithelial cell line A549 infected with influenza A virus were investigated.

MATERIALS AND METHODS

Chemical and spectroscopic methods were employed to identify the structure of the lignan glycoside. Cytotoxicity of the lignan glycoside was analyzed using methylthiazolyltetrazolium (MTT) assay. The inhibitory activity against influenza virus of the lignan was determined by CPE inhibition assay. HEK-293 cells stably co-transfected with NF-κB responsive firefly luciferase and constitutively expressing GFP were employed for monitoring the effect of the lignan on NF-κB signal pathway activation. Nuclear export of viral ribonucleoprotein (RNP) complexes was monitored by indirect immunofluorescence. Quantitative real-time PCR was used to quantify the expression profiling of cytokines and chemokines after infection with influenza virus.

RESULTS

We showed that the lignan glycoside treatment was effective against the influenza A virus-induced cytopathic effect (CPE) in MDCK cells. Further study demonstrated the lignan glycoside attenuated virus-induced NF-κB activation, but did not affect export of viral ribonucleoprotein (RNP) complexes from the nucleus in late stages of infection. We revealed that the lignan glycoside suppressed influenza A virus (H1N1)-induced expression of the pro-inflammatory molecules IL-6, TNF-α, IL-8, MCP-1, IP-10 and IFN-α. Moreover, the cytokines and chemokines profiles induced by H9N2 virus resembled those of influenza virus H1N1, but the lignan glycoside reduced the expression of IP-10 and TNF-α.

CONCLUSIONS

Our results suggest that the lignan glycoside is a bioactive component of I. indigotica which may contribute an adjunct to pharmacotherapy for influenza virus infection.

The microRNA miR-22 inhibits the histone deacetylase HDAC4 to promote T(H)17 cell-dependent emphysema

Smoking-related emphysema is a chronic inflammatory disease driven by the T(H)17 subset of helper T cells through molecular mechanisms that remain obscure. Here we explored the role of the microRNA miR-22 in emphysema. We found that miR-22 was upregulated in lung myeloid dendritic cells (mDCs) of smokers with emphysema and antigen-presenting cells (APCs) of mice exposed to smoke or nanoparticulate carbon black (nCB) through a mechanism that involved the transcription factor NF-κB. Mice deficient in miR-22, but not wild-type mice, showed attenuated T(H)17 responses and failed to develop emphysema after exposure to smoke or nCB. We further found that miR-22 controlled the activation of APCs and T(H)17 responses through the activation of AP-1 transcription factor complexes and the histone deacetylase HDAC4. Thus, miR-22 is a critical regulator of both emphysema and T(H)17 responses.

Pharmacologically-induced mitotic synchrony in airway epithelial cells as a mechanism of action of anti-inflammatory drugs

BACKGROUND

Mitotic synchrony is the synchronous progression of a population of cells through the cell cycle and is characteristic of non-diseased airway epithelial cells. However, we previously showed that asthmatic airway epithelial cells are characterized by mitotic asynchrony and are pro-inflammatory as a result. Glucocorticoids can induce mitotic synchrony that in turn suppresses the pro-inflammatory state of diseased cells, suggesting a novel anti-inflammatory mechanism of action. Herein, we benchmarked traditional glucocorticoids against the ability of a new clinical-stage dissociative steroidal drug, VBP15, for mitotic resynchronization and associated anti-inflammatory activity in asthmatic airway epithelial cells.

METHODS

Primary airway epithelial cells differentiated at air-liquid interface were exposed to VBP15, dexamethasone or vehicle following in vitro mechanical injury. Basolateral cytokine secretions (TGF-β1, IL-6, IL-10, IL-13, and IL-1β) were analyzed at different time points using cytometric bead assays and mitosis was examined by flow cytometry.

RESULTS

VBP15 improved mitotic synchrony of proliferating asthmatic cells in air-liquid interface cultures compared to vehicle-exposed cultures. VBP15 also significantly reduced the basolateral secretion of pro-inflammatory (i.e. IL-1β) and pro-fibrogenic cytokines (i.e. TGF-β1) in air-liquid interface-differentiated asthmatic epithelial cultures following mechanical injury.

CONCLUSION

VBP15 improves mitotic asynchrony and injury-induced pro-inflammatory and fibrogenic responses in asthmatic airway epithelial cultures with efficacy comparable to traditional glucocorticoids. As it is predicted to show superior side effect profiles compared to traditional glucocorticoids, VBP15 holds potential for treatment of asthma and other respiratory conditions.

Effects of Chung-Pae Inhalation Therapy on a Mouse Model of Chronic Obstructive Pulmonary Disease

Chung-pae (CP) inhalation therapy is a method frequently used in Korea to treat lung disease, especially chronic obstructive pulmonary disease (COPD). This study investigated the effects of CP inhalation on a COPD animal model. C57BL/6 mice received porcine pancreatic elastase (PPE) and lipopolysaccharide (LPS) alternately three times for 3 weeks to induce COPD. Then, CP (5 or 20 mg/kg) was administered every 2 h after the final LPS administration. The effect of CP was evaluated by bronchoalveolar lavage (BAL) fluid analysis, histological analysis of lung tissue, and reverse transcription polymerase chain reaction analysis of mRNA of interleukin- (IL-) 1β, tumor necrosis factor- (TNF-) α, IL-6, and tumor growth factor- (TGF-) β. Intratracheal CP administration reduced the number of leukocytes and neutrophils in BAL fluid, inhibited the histological appearance of lung damage, and decreased the mRNA levels of the proinflammatory cytokines IL-1β, TNF-α, IL-6, and TGF-β. Intratracheal CP administration effectively decreased the chronic inflammation and pathological changes in a PPE- and LPS-induced COPD mouse model. Therefore, we suggest that CP is a promising strategy for COPD.

NF-κB-dependent airway inflammation triggers systemic insulin resistance

Inflammatory lung diseases (e.g., pneumonia and acute respiratory distress syndrome) are associated with hyperglycemia, even in patients without a prior diagnosis of Type 2 diabetes. It is unknown whether the lung inflammation itself or the accompanying comorbidities contribute to the increased risk of hyperglycemia and insulin resistance. To investigate whether inflammatory signaling by airway epithelial cells can induce systemic insulin resistance, we used a line of doxycycline-inducible transgenic mice that express a constitutive activator of the NF-κB in airway epithelial cells. Airway inflammation with accompanying neutrophilic infiltration was induced with doxycycline over 5 days. Then, hyperinsulinemic-euglycemic clamps were performed in chronically catheterized, conscious mice to assess insulin action. Lung inflammation decreased the whole body glucose requirements and was associated with secondary activation of inflammation in multiple tissues. Metabolic changes occurred in the absence of hypoxemia. Lung inflammation markedly attenuated insulin-induced suppression of hepatic glucose production and moderately impaired insulin action in peripheral tissues. The hepatic Akt signaling pathway was intact, while hepatic markers of inflammation and plasma lactate were increased. As insulin signaling was intact, the inability of insulin to suppress glucose production in the liver could have been driven by the increase in lactate, which is a substrate for gluconeogenesis, or due to an inflammation-driven signal that is independent of Akt. Thus, localized airway inflammation that is observed during inflammatory lung diseases can contribute to systemic inflammation and insulin resistance.

Dynamics of IL-4 and IL-13 expression in the airways of sheep following allergen challenge

Background

IL-4 and IL-13 play a critical yet poorly understood role in orchestrating the recruitment and activation of effector cells of the asthmatic response and driving the pathophysiology of allergic asthma. The house dust mite (HDM) sheep asthma model displays many features of the human condition and is an ideal model to further elucidate the involvement of these critical Th₂ cytokines. We hypothesized that airway exposure to HDM allergen would induce or elevate the expression profile of IL-4 and IL-13 during the allergic airway response in this large animal model of asthma.

Methods

Bronchoalveolar lavage (BAL) samples were collected from saline- and house dust mite (HDM)- challenged lung lobes of sensitized sheep from 0 to 48 h post-challenge. BAL cytokines (IL-4, IL-13, IL-6, IL-10, TNF-α) were each measured by ELISA. IL-4 and IL-13 expression was assessed in BAL leukocytes by flow cytometry and in airway tissue sections by immunohistology.

Results

IL-4 and IL-13 were increased in BAL samples following airway allergen challenge. HDM challenge resulted in a significant increase in BAL IL-4 levels at 4 h compared to saline-challenged airways, while BAL IL-13 levels were elevated at all time-points after allergen challenge. IL-6 levels were maintained following HDM challenge but declined after saline challenge, while HDM administration resulted in an acute elevation in IL-10 at 4 h but no change in TNF-α levels over time. Lymphocytes were the main early source of IL-4, with IL-4 release by alveolar macrophages (AMs) prominent from 24 h post-allergen challenge. IL-13 producing AMs were increased at 4 and 24 h following HDM compared to saline challenge, and tissue staining provided evidence of IL-13 expression in airway epithelium as well as immune cells in airway tissue.

Conclusion

In a sheep model of allergic asthma, airway inflammation is accompanied by the temporal release of key cytokines following allergen exposure that primarily reflects the Th₂-driven nature of the immune response in asthma. The present study demonstrates for the first time the involvement of IL-4 and IL-13 in a relevant large animal model of allergic airways disease.

Activation of EP4 receptors prevents endotoxin-induced neutrophil infiltration into the airways and enhances microvascular barrier function

BACKGROUND AND PURPOSE

Pulmonary vascular dysfunction is a key event in acute lung injury. We recently demonstrated that PGE₂ , via activation of E-prostanoid (EP)₄ receptors, strongly enhances microvascular barrier function in vitro. The aim of this study was to investigate the beneficial effects of concomitant EP₄ receptor activation in murine models of acute pulmonary inflammation.

EXPERIMENTAL APPROACH

Pulmonary inflammation in male BALB/c mice was induced by LPS (20 μg per mouse intranasally) or oleic acid (0.15 μL·g^-1 , i.v^. ). In-vitro, endothelial barrier function was determined by measuring electrical impedance.

KEY RESULTS

PGE₂ activation of EP₄ receptors reduced neutrophil infiltration, pulmonary vascular leakage and TNF-α concentration in bronchoalveolar lavage fluid from LPS-induced pulmonary inflammation. Similarly, pulmonary vascular hyperpermeability induced by oleic acid was counteracted by EP₄ receptor activation. In lung function assays, the EP₄ agonist ONO AE1-329 restored the increased resistance and reduced compliance upon methacholine challenge in mice treated with LPS or oleic acid. In agreement with these findings, EP₄ receptor activation increased the in vitro vascular barrier function of human and mouse pulmonary microvascular endothelial cells and diminished the barrier disruption induced by LPS. The EP₂ agonist ONO AE1-259 likewise reversed LPS-induced lung dysfunction without enhancing vascular barrier function.

CONCLUSION AND IMPLICATIONS

Our results show that activation of the EP₄ receptor strengthens the microvascular barrier function and thereby ameliorates the pathology of acute lung inflammation, including neutrophil infiltration, vascular oedema formation and airway dysfunction. This suggests a potential benefit for EP₄ agonists in acute pulmonary inflammation.

Expression of adenosine receptors in monocytes from patients with bronchial asthma

Adenosine is generated from adenosine triphosphate, which is released by stressed and damaged cells. Adenosine levels are significantly increased in patients with bronchial asthma (BA) and mediate mast cell degranulation and bronchoconstriction. Over the last decade, increasing evidence has shown that adenosine can modulate the innate immune response during monocytes differentiation towards mature myeloid cells. These adenosine-differentiated myeloid cells, characterized by co-expression of monocytes/macrophages and dendritic cell markers such as CD14 and CD209, produce high levels of pro-inflammatory cytokines, thus contributing to the pathogenesis of BA and chronic obstructive pulmonary disease. We found that expression of ADORA2A and ADORA2B are increased in monocytes obtained from patients with BA, and are associated with the generation of CD14(pos)CD209(pos) pro-inflammatory cells. A positive correlation between expression of ADORA2B and IL-6 was identified in human monocytes and may explain the increased expression of IL-6 mRNA in asthmatics. Taken together, our results suggest that monocyte-specific expression of A2 adenosine receptors plays an important role in pro-inflammatory activation of human monocytes, thus contributing to the progression of asthma.

The TNF Family Molecules LIGHT and Lymphotoxin αβ Induce a Distinct Steroid-Resistant Inflammatory Phenotype in Human Lung Epithelial Cells

Lung epithelial cells are considered important sources of inflammatory molecules and extracellular matrix proteins that contribute to diseases such as asthma. Understanding the factors that stimulate epithelial cells may lead to new insights into controlling lung inflammation. This study sought to investigate the responsiveness of human lung epithelial cells to the TNF family molecules LIGHT and lymphotoxin αβ (LTαβ). Bronchial and alveolar epithelial cell lines, and primary human bronchial epithelial cells, were stimulated with LIGHT and LTαβ, and expression of inflammatory cytokines and chemokines and markers of epithelial-mesenchymal transition and fibrosis/remodeling was measured. LTβ receptor, the receptor shared by LIGHT and LTαβ, was constitutively expressed on all epithelial cells. Correspondingly, LIGHT and LTαβ strongly induced a limited but highly distinct set of inflammatory genes in all epithelial cells tested, namely the adhesion molecules ICAM-1 and VCAM-1; the chemokines CCL5, CCL20, CXCL1, CXCL3, CXCL5, and CXCL11; the cytokines IL-6, activin A and GM-CSF; and metalloproteinases matrix metalloproteinase-9 and a disintegrin and metalloproteinase domain-8. Importantly, induction of the majority of these inflammatory molecules was insensitive to the suppressive effects of the corticosteroid budesonide. LIGHT and LTαβ also moderately downregulated E-cadherin, a protein associated with maintaining epithelial integrity, but did not significantly drive production of extracellular matrix proteins or α-smooth muscle actin. Thus, LIGHT and LTαβ induce a distinct steroid-resistant inflammatory signature in airway epithelial cells via constitutively expressed LTβ receptor. These findings support our prior murine studies that suggested the receptors for LIGHT and LTαβ contribute to development of lung inflammation characteristic of asthma and idiopathic pulmonary fibrosis.

Mechanical Ventilation Induces an Inflammatory Response in Preinjured Lungs in Late Phase of Sepsis

Mechanical ventilation (MV) may amplify the lung-specific inflammatory response in preinjured lungs by elevating cytokine release and augmenting damage to the alveolar integrity. In this study, we test the hypothesis that MV exerts different negative impacts on inflammatory response at different time points of postlung injury. Basic lung injury was induced by cecal ligation and puncture (CLP) surgery in rats. Physiological indexes including blood gases were monitored during MV and samples were assessed following each experiment. Low V_T (tidal volume) MV caused a slight increase in cytokine release and tissue damage at day 1 and day 4 after sepsis induced lung injury, while cytokine release from the lungs in the two moderately ventilated V_T groups was amplified. Interestingly, in the two groups where rats received low V_T MV, we found that infiltration of inflammatory cells was only profound at day 4 after CLP. Marked elevation of protein leakage indicated a compromise in alveolar integrity in rats that received moderate V_T MV at day 4 following CLP, correlating with architectural damage to the alveoli. Our study indicates that preinjured lungs are more sensitive to mechanical MV at later phases of sepsis, and this situation may be a result of differing immune status.

In-vitro suppression of IL-6 and IL-8 release from human pulmonary epithelial cells by non-anticoagulant fraction of enoxaparin

BACKGROUND

Enoxaparin, a mixture of anticoagulant and non-anticoagulant fractions, is widely used as an anticoagulant agent. However, it is also reported to possess anti-inflammatory properties. Our study indicated that enoxaparin inhibits the release of IL-6 and IL-8 from A549 pulmonary epithelial cells. Their release causes extensive lung tissue damage. The use of enoxaparin as an anti-inflammatory agent is hampered due to the risk of bleeding associated with its anticoagulant fractions. Therefore, we aimed to identify the fraction responsible for the observed anti-inflammatory effect of enoxaparin and to determine the relationship between its structure and biological activities.

METHODS

A549 pulmonary epithelial cells were pre-treated in the presence of enoxaparin and its fractions. The levels of IL-6 and IL-8 released from the trypsin-stimulated cells were measured by ELISA. The anticoagulant activity of the fraction responsible for the effect of enoxaparin was determined using an anti-factor-Xa assay. The fraction was structurally characterised using nuclear magnetic resonance. The fraction was 2-O, 6-O or N-desulfated to determine the position of sulfate groups required for the inhibition of interleukins. High-performance size-exclusion chromatography was performed to rule out that the observed effect was due to the interaction between the fraction and trypsin or interleukins.

RESULTS

Enoxaparin (60 μg/mL) inhibited the release of IL-6 and IL-8 by >30%. The fraction responsible for this effect of enoxaparin was found to be a disaccharide composed of α-L-iduronic-acid and α-D-glucosamine-6-sulfate. It (15 μg/mL) inhibited the release of interleukins by >70%. The 6-O sulphate groups were responsible for its anti-inflammatory effect. The fraction did not bind to trypsin or interleukins, suggesting the effect was not due to an artefact of the experimental model.

CONCLUSION

The identified disaccharide has no anticoagulant activity and therefore eliminates the risk of bleeding associated with enoxaparin. Future in-vivo studies should be designed to validate findings of the current study.

Astrocyte response to IFN-γ limits IL-6-mediated microglia activation and progressive autoimmune encephalomyelitis

Background

Therapeutic modalities effective in patients with progressive forms of multiple sclerosis (MS) are limited. In a murine model of progressive MS, the sustained disability during the chronic phase of experimental autoimmune encephalomyelitis (EAE) correlated with elevated expression of interleukin (IL)-6, a cytokine with pleiotropic functions and therapeutic target for non-central nervous system (CNS) autoimmune disease. Sustained IL-6 expression in astrocytes restricted to areas of demyelination suggested that IL-6 plays a major role in disease progression during chronic EAE.

Methods

A progressive form of EAE was induced using transgenic mice expressing a dominant negative interferon-γ (IFN-γ) receptor alpha chain under control of human glial fibrillary acidic protein (GFAP) promoter (GFAPγR1Δ mice). The role of IL-6 in regulating progressive CNS autoimmunity was assessed by treating GFAPγR1Δ mice with anti-IL-6 neutralizing antibody during chronic EAE.

Results

IL-6 neutralization restricted disease progression and decreased disability, myelin loss, and axonal damage without affecting astrogliosis. IL-6 blockade reduced CNS inflammation by limiting inflammatory cell proliferation; however, the relative frequencies of CNS leukocyte infiltrates, including the Th1, Th17, and Treg CD4 T cell subsets, were not altered. IL-6 blockade rather limited the activation and proliferation of microglia, which correlated with higher expression of Galectin-1, a regulator of microglia activation expressed by astrocytes.

Conclusions

These data demonstrate that astrocyte-derived IL-6 is a key mediator of progressive disease and support IL-6 blockade as a viable intervention strategy to combat progressive MS.

Therapeutic potential of anti-IL-6 therapies for granulocytic airway inflammation in asthma

BACKGROUND

Determining the cellular and molecular phenotypes of inflammation in asthma can identify patient populations that may best benefit from targeted therapies. Although elevated IL-6 and polymorphisms in IL-6 signalling are associated with lung dysfunction in asthma, it remains unknown if elevated IL-6 levels are associated with a specific cellular inflammatory phenotype, and how IL-6 blockade might impact such inflammatory responses.

METHODS

Patients undergoing exacerbations of asthma were phenotyped according to their airway inflammatory characteristics (normal cell count, eosinophilic, neutrophilic, mixed granulocytic), sputum cytokine profiles, and lung function. Mice were exposed to the common allergen, house dust-mite (HDM), in the presence or absence of endogenous IL-6. The intensity and nature of lung inflammation, and levels of pro-granulocytic cytokines and chemokines under these conditions were analyzed.

RESULTS

Elevated IL-6 was associated with a lower FEV1 in patients with mixed eosinophilic-neutrophilic bronchitis. In mice, allergen exposure increased lung IL-6 and IL-6 was produced by dendritic cells and alveolar macrophages. Loss-of-function of IL-6 signalling (knockout or antibody-mediated neutralization) abrogated elevations of eosinophil and neutrophil recruiting cytokines/chemokines and allergen-induced airway inflammation in mice.

CONCLUSIONS

We demonstrate the association of pleiotropic cellular airway inflammation with IL-6 using human and animal data. These data suggest that exacerbations of asthma, particularly those with a combined eosinophilic and neutrophilic bronchitis, may respond to therapies targeting the IL-6 pathway and therefore, provide a rational basis for initiation of clinical trials to evaluate this.

Angiotensin-(1-7) attenuates airway remodelling and hyperresponsiveness in a model of chronic allergic lung inflammation

BACKGROUND AND PURPOSE

A long-term imbalance between pro- and anti-inflammatory mediators leads to airway remodelling, which is strongly correlated to most of the symptoms, severity and progression of chronic lung inflammation. The Angiotensin-(1-7) [Ang-(1-7)]/Mas receptor axis of the renin-angiotensin system is associated with attenuation of acute and chronic inflammatory processes. In this study, we investigated the effects of Ang-(1-7) treatment in a model of chronic allergic lung inflammation.

EXPERIMENTAL APPROACH

Mice were sensitized to ovalbumin (OVA; 4 injections over 42 days, 14 days apart) and were challenged three times per week (days 21-46). These mice received Ang-(1-7) (1 μg·h(-1) , s.c.) by osmotic mini-pumps, for the last 28 days. Histology and morphometric analysis were performed in left lung and right ventricle. Airway responsiveness to methacholine, analysis of Ang-(1-7) levels (RIA), collagen I and III (qRT-PCR), ERK1/2 and JNK (Western blotting), IgE (elisa), cytokines and chemokines (elisa multiplex), and immunohistochemistry for Mas receptors were performed.

KEY RESULTS

Infusion of Ang-(1-7) in OVA-sensitized and challenged mice decreased inflammatory cell infiltration and collagen deposition in the airways and lung parenchyma, and prevented bronchial hyperresponsiveness. These effects were accompanied by decreased IgE and ERK1/2 phosphorylation, and decreased pro-inflammatory cytokines. Mas receptors were detected in the epithelium and bronchial smooth muscle, suggesting a site in the lung for the beneficial actions of Ang-(1-7).

CONCLUSIONS AND IMPLICATIONS

Ang-(1-7) exerted beneficial attenuation of three major features of chronic asthma: lung inflammation, airway remodelling and hyperresponsiveness. Our results support an important protective role of Ang-(1-7) in lung inflammation.