Th2- and to a lesser extent Th1-type cytokines upregulate the production of both CXC (IL-8 and gro-alpha) and CC (RANTES, eotaxin, eotaxin-2, MCP-3 and MCP-4) chemokines in human airway epithelial cells

Effects of autoimmune abnormalities on fertility and placental morphology in mice

Autoimmune diseases (AIDs) alter the placental immune environment leading to fetal loss. This study investigated the effects of AIDs on pregnancy and the placenta in AID-prone MRL/MpJ-Faslpr/lpr mice and wild-type MRL/MpJ, which were mated with male MRL/MpJ and MRL/MpJ-Faslpr/lpr at five months and defined as moLpr and moMpJ, respectively. AID indices (spleen weight and serum autoantibody levels) and fertility status (number and size of fetuses, morphology, and comprehensive gene expression of placentas) were evaluated on gestational day 15.5. Both strains showed equivalent fertility, but moLpr showed lighter placentas and fetuses than moMpJ, and decreased fertility with AID severity. moLpr placentas had a higher number of T cells, higher expression of genes associated with T helper 2 and T follicular helper functions, and altered expression of genes (Krt15, Slc7a3, Sprr2a3) that significantly regulate pregnancy or immunity. The gene expression of T cell migration-associated chemokines (Ccl5, Cxcl9) was significantly increased in moLpr placentas, and CCL5 and CXCL9 were detected in moLpr placentas, particularly in T cells and placenta-component cells, respectively. Thus, AID altered placental morphofunction and fertility in mice; however, fertility was maintained at the examined time points. This study enhances our understanding of placental alterations and gestational risk due to AIDs.

Comparison of smoking traditional, heat not burn and electronic cigarettes on salivary cytokine, chemokine and growth factor profile in healthy young adults-pilot study

Objective: Smoking is the cause of numerous oral pathologies. The aim of the study was to evaluate the effect of smoking traditional cigarettes, e-cigarettes, and heat-not-burn products on the content of salivary cytokines, chemokines, and growth factors in healthy young adults. Design: Three groups of twenty-five smokers each as well as a control group matched in terms of age, gender, and oral status were enrolled in the study. In unstimulated saliva collected from study groups and participants from the control group, the concentrations of cytokines, chemokines, and growth factors were assessed by Bio-Plex® Multiplex System. Results: We demonstrated that smoking traditional cigarettes is responsible for increasing the level of IFN-γ compared to non-smokers and new smoking devices users in unstimulated saliva in the initial period of addiction. Furthermore, e-cigarettes and heat-not-burn products appear to have a similar mechanism of affecting the immune response system of unstimulated saliva, leading to inhibition of the local inflammatory response in the oral cavity. Conclusion: Smoking traditional cigarettes as well as e-cigarettes and heat-not-burn products is responsible for changes of the local immune response in saliva. Further research is necessary to fill the gap in knowledge on the effect of new smoking devices on the oral cavity immune system.

The Role of the Dynamic Lung Extracellular Matrix Environment on Fibroblast Morphology and Inflammation

The extracellular matrix (ECM) supports lung tissue architecture and physiology by providing mechanical stability and elastic recoil. Over the last several decades, it has become increasingly clear that the stiffness of the ECM governs many cellular processes, including cell-phenotype and functions during development, healing, and disease. Of all the lung ECM proteins, collagen-I is the most abundant and provides tensile strength. In many fibrotic lung diseases, the expression of collagen is increased which affects the stiffness of the surrounding environment. The goal of this study was to assess the effect on fibroblast morphology, cell death, and inflammation when exposed to 2D and 3D low (0.4 mg/mL) versus high (2.0 mg/mL) collagen-I-matrix environments that model the mechanics of the breathing lung. This study demonstrates that human fetal lung fibroblasts (HFL1), grown in a 3D collagen type-I environment compared to a 2D one, do not form cells with a myofibroblast morphology, express less F-actin stress fibers, exhibit less cell death, and significantly produce less pro-inflammatory IL-6 and IL-8 cytokines. Exposure to mechanical strain to mimic breathing (0.2 Hz) led to the loss of HFL1 fibroblast dendritic extensions as well as F-actin stress fibers within the cell cytoskeleton, but did not influence cytokine production or cell death. This dynamic assay gives researchers the ability to consider the assessment of the mechanodynamic nature of the lung ECM environment in disease-relevant models and the potential of mechano-pharmacology to identify therapeutic targets for treatment.

Inflammatory phenotype modulation in the respiratory tract and systemic circulation of e-cigarette users: a pilot study

Over 40 million people use e-cigarettes worldwide, but the impact of chronic e-cigarette use on health has not been adequately defined. In particular, effects of e-cigarette aerosol inhalation on inflammation and host defenses across the body are not fully understood. We conducted a longitudinal cohort pilot study to explore changes in the inflammatory state and monocyte function of e-cigarette users (n=20) versus healthy controls (n=13), and to evaluate effects of e-cigarette use reduction on the same. Saliva, sputum, and blood were obtained from e-cigarette users at baseline and after a 2-week intervention of decreased e-cigarette use. Overall, across 38 proteins quantified by multiplex, airway samples from e-cigarette users tended to have decreased levels of immunomodulatory proteins relative to healthy controls, while levels of cytokines, chemokines and growth factors in the circulation tended to be elevated. Specifically, e-cigarette users had lower levels of IL-1 receptor antagonist (IL-1Ra) in saliva (p<0.0001), with higher IL-1Ra and GRO levels in sputum (p<0.01 and p<0.05, respectively), and higher levels of both TNFβ (p<0.0001) and VEGF (p<0.0001) in plasma. Circulating monocytes from e-cigarette users had alterations in their inflammatory phenotype in response to reduced e-cigarette use, with blunted IL-8 and IL-6 release upon challenge with bacterial lipopolysaccharide (p<0.001 and p<0.05, respectively), suggesting a decreased ability to appropriately respond to bacterial infection. Based on these findings, chronic inhalation of e-cigarette aerosols alters the inflammatory state of the airways and systemic circulation, raising concern for the development of both inflammatory and infectious diseases in chronic users of e-cigarettes.

Feasibility, potency, and safety of growing human mesenchymal stem cells in space for clinical application

Growing stem cells on Earth is very challenging and limited to a few population doublings. The standard two-dimensional (2D) culture environment is an unnatural condition for cell growth. Therefore, culturing stem cells aboard the International Space Station (ISS) under a microgravity environment may provide a more natural three-dimensional environment for stem cell expansion and organ development. In this study, human-derived mesenchymal stem cells (MSCs) grown in space were evaluated to determine their potential use for future clinical applications on Earth and during long-term spaceflight. MSCs were flown in Plate Habitats for transportation to the ISS. The MSCs were imaged every 24-48 h and harvested at 7 and 14 days. Conditioned media samples were frozen at -80 °C and cells were either cryopreserved in 5% dimethyl sulfoxide, RNAprotect, or paraformaldehyde. After return to Earth, MSCs were characterized to establish their identity and cell cycle status. In addition, cell proliferation, differentiation, cytokines, and growth factors' secretion were assessed. To evaluate the risk of malignant transformation, the space-grown MSCs were subjected to chromosomal, DNA damage, and tumorigenicity assays. We found that microgravity had significant impact on the MSC capacity to secrete cytokines and growth factors. They appeared to be more potent in terms of immunosuppressive capacity compared to their identical ground control. Chromosomal, DNA damage, and tumorigenicity assays showed no evidence of malignant transformation. Therefore, it is feasible and potentially safe to grow MSCs aboard the ISS for potential future clinical applications.

Human airway trypsin-like protease enhances interleukin-8 synthesis in bronchial epithelial cells by activating protease-activated receptor 2

Human airway trypsin-like protease (HAT) localizes at human bronchial epithelial cells (HBECs). HAT enhanced release of interleukin-8 (IL-8) from HBECs at 10-100 mU/mL and the enhanced release was almost completely abolished by 50 μM leupeptin, a serine protease inhibitor. Previous reports suggested that HAT displays its physiological functions via protease-activated receptor 2 (PAR2). In the present study, we examined the mechanism whereby HAT upregulates IL-8 synthesis in HBECs with a focus on PAR2. Northern blot analysis revealed that HAT enhanced IL-8 mRNA expression at concentrations of 10-100 mU/mL. PAR2 activating peptide (PAR2 AP) also enhanced IL-8 release and IL-8 mRNA expression in HBECs at 50-1,000 μM at similar levels as HAT. Knockdown of PAR2 mRNA by siRNA methods showed that PAR2 mRNA expression was significantly depressed in primary HBECs, and both HAT- and PAR2 AP-induced IL-8 mRNA elevation was significantly depressed in PAR2 siRNA-transfected HBECs. Additionally, HAT cleaved the PAR2 activating site (R³⁶-S³⁷ bond) of synthetic PAR2 N-terminal peptide. These results indicate that HAT stimulates IL-8 synthesis in airway epithelial cells via PAR2 and could help to amplify inflammation in chronic respiratory tract disease.

Increased serum Th2 chemokine levels are associated with bronchopulmonary dysplasia in premature infants

Bronchopulmonary dysplasia (BPD) is one of the most common chronic inflammatory lung disease of premature infants, with serious short- and long-term consequences. Early identification of premature infants at risk of BPD is critical to preventing the pathogenesis of disease. Thus, in the present study, we recruited 126 premature infants, collected peripheral blood samples at different time points during early life, and measured the concentration of Th1 (MCP-1, IP-10, and MIG) and Th2 (eotaxin-1, eotaxin-2, and MCP-4) chemokines in serum. We found serum eotaxin-2 levels were significantly higher in the BPD group than in the non-BPD group on day 1 [1662 pg/ml vs. 1221 pg/ml, P < 0.05], day 7 [1533 pg/ml vs. 1089 pg/ml, P < 0.05], and day 14 [1246 pg/ml vs. 704 pg/ml, P < 0.05] after birth, and serum MCP-4 levels were also significantly higher in the BPD group than in the non-BPD group on day 1 [186 pg/ml vs. 128 pg/ml, P < 0.05], day 7 [199 pg/ml vs. 101 pg/ml, P < 0.05], and day 14 [238 pg/ml vs. 106 pg/ml, P < 0.05] of life.Conclusions: Increased levels of Th2 chemokines, eotaxin-2, and MCP-4, are associated with BPD in premature infants. What is Known: • The pathogenesis of BPD is multifactorial and it is difficult to predict and prevent. • Previous studies have demonstrated that inflammation plays a major role in the pathogenesis of BPD. What is New: • Increased Th2 chemokines, eotaxin-2 and MCP-4, were associated with BPD in premature infants. • Abnormal Th1/Th2 response in early life maybe associated with the subsequent development of BPD, which provide a new insight to understand the pathogenesis of the disease.

Rapamycin attenuates Th2-driven experimental allergic conjunctivitis

Allergic conjunctivitis is mediated by eosinophilic infiltration and Th2 type immune responses. This study aims to elucidate the role of rapamycin, mTOR inhibitor, on OVA-induced experimental allergic conjunctivitis (EAC). Rapamycin administration intraperitoneally markedly reduced clinical signs, total and OVA-specific IgE and IgG1/G2a ratio in serum, and conjunctival eosinophilic infiltration. Infiltrations of CD11c⁺ dendritic cells and CD4⁺ T cells, and the expressions of chemokines and adhesion molecules in the conjunctiva were attenuated in rapamycin-treated mice, as well as decreased Th1 and Th2 cytokines in the cervical lymph nodes compared to non-treated mice. The expression of mTOR signaling proteins was increased in EAC and reduced by rapamycin treatment. Topical application of rapamycin was also proved to show reduced clinical signs, eosinophil infiltration, and Th2 type immune responses comparable to those from intraperitoneal injection of rapamycin. These findings suggest the therapeutic implications of rapamycin in the attenuation of allergic conjunctivitis.

β2-Adrenoceptor signaling in airway epithelial cells promotes eosinophilic inflammation, mucous metaplasia, and airway contractility

The mostly widely used bronchodilators in asthma therapy are β₂-adrenoreceptor (β₂AR) agonists, but their chronic use causes paradoxical adverse effects. We have previously determined that β₂AR activation is required for expression of the asthma phenotype in mice, but the cell types involved are unknown. We now demonstrate that β₂AR signaling in the airway epithelium is sufficient to mediate key features of the asthmatic responses to IL-13 in murine models. Our data show that inhibition of β₂AR signaling with an aerosolized antagonist attenuates airway hyperresponsiveness (AHR), eosinophilic inflammation, and mucus-production responses to IL-13, whereas treatment with an aerosolized agonist worsens these phenotypes, suggesting that β₂AR signaling on resident lung cells modulates the asthma phenotype. Labeling with a fluorescent β₂AR ligand shows the receptors are highly expressed in airway epithelium. In β₂AR^-/- mice, transgenic expression of β₂ARs only in airway epithelium is sufficient to rescue IL-13-induced AHR, inflammation, and mucus production, and transgenic overexpression in WT mice exacerbates these phenotypes. Knockout of β-arrestin-2 (βarr-2^-/-) attenuates the asthma phenotype as in β₂AR^-/- mice. In contrast to eosinophilic inflammation, neutrophilic inflammation was not promoted by β₂AR signaling. Together, these results suggest β₂ARs on airway epithelial cells promote the asthma phenotype and that the proinflammatory pathway downstream of the β₂AR involves βarr-2. These results identify β₂AR signaling in the airway epithelium as capable of controlling integrated responses to IL-13 and affecting the function of other cell types such as airway smooth muscle cells.

Reference Values for a Panel of Cytokinergic and Regulatory Lymphocyte Subpopulations

Lymphocyte subpopulations producing cytokines and exerting regulatory functions represent key immune elements. Given their reciprocal interdependency lymphocyte subpopulations are usually assayed as diagnostic panels, rather than single biomarkers for specialist clinical use. This retrospective analysis on lymphocyte subpopulations, analyzed over the last few years in an outpatient laboratory in Northeast Italy, contributes to the establishment of reference values for several regulatory lymphocytes currently lacking such reference ranges for the general population. Mean values and ranges in a sample of Caucasian patients (mean age 42±8,5 years), were provided for Th1, Th2, Th17, Th-reg, Tc-reg, Tc-CD57⁺ and B1 lymphocytes. The results are consistent with what is found in literature for the single subtypes and are: Th1 157.8±60.3/µl (7.3%±2.9); Th2 118.2±52.2/µl (5.4%±2.5); Th17 221.6±90.2/µl (10.5%±4.4); Th-reg 15.1±10.2/µl (0.7%±0.4); Tc-reg 5.8±4.7/µl (0.3%±0.2); Tc-CD57+ 103.7±114.1/µl (4.6%±4.7); B1 33.7±22.8/µl (1.5%±0.9); (Values are mean±SD). The results show that despite their variability, mean values are rather consistent in all age or sex groups and can be used as laboratory internal reference for this regulatory panel. Adding regulatory cells to lymphocyte subpopulations panels allows a more complete view of the state of the subject's immune network balance, thus improving the personalization and the "actionability" of diagnostic data in a systems medicine perspective.

Characterisation of inflammatory processes in Helicobacter pylori-induced gastric lymphomagenesis in a mouse model

Gastric MALT lymphoma (GML) can be induced by Helicobacter pylori infection in BALB/c mice thymectomised at day 3 post-birth (d3Tx). This represented a unique opportunity to investigate the inflammatory process involved in the recruitment, proliferation and structuration of lymphoid infiltrates in the gastric mucosa of mice developing GML. Complementary molecular and proteomic approaches demonstrated that Th1 and Th2 cytokines were upregulated, along with activators/regulators of the lymphoid response and numerous chemokines. Interleukin-4, interferon γ, lymphotoxin-α and -β were significantly upregulated and correlated with the inflammatory scores for all the d3Tx mice. GML lesions in d3Tx mice infected with H. pylori were associated with the presence of the inflammatory response. The dysregulation of numerous members of the tumour necrosis factor superfamily was also evident and suggests that they could play an important role in GML pathology, especially in light of their ability to promote and control lymphocyte proliferation.

Randomised, double-blind, placebo-controlled trial with azithromycin selects for anti-inflammatory microbial metabolites in the emphysematous lung

Introduction

Azithromycin (AZM) reduces pulmonary inflammation and exacerbations in patients with COPD having emphysema. The antimicrobial effects of AZM on the lower airway microbiome are not known and may contribute to its beneficial effects. Here we tested whether AZM treatment affects the lung microbiome and bacterial metabolites that might contribute to changes in levels of inflammatory cytokines in the airways.

Methods

20 smokers (current or ex-smokers) with emphysema were randomised to receive AZM 250 mg or placebo daily for 8 weeks. Bronchoalveolar lavage (BAL) was performed at baseline and after treatment. Measurements performed in acellular BAL fluid included 16S rRNA gene sequences and quantity; 39 cytokines, chemokines and growth factors and 119 identified metabolites. The response to lipopolysaccharide (LPS) by alveolar macrophages after ex-vivo treatment with AZM or bacterial metabolites was assessed.

Results

Compared with placebo, AZM did not alter bacterial burden but reduced α-diversity, decreasing 11 low abundance taxa, none of which are classical pulmonary pathogens. Compared with placebo, AZM treatment led to reduced in-vivo levels of chemokine (C-X-C) ligand 1 (CXCL1), tumour necrosis factor (TNF)-α, interleukin (IL)-13 and IL-12p40 in BAL, but increased bacterial metabolites including glycolic acid, indol-3-acetate and linoleic acid. Glycolic acid and indol-3-acetate, but not AZM, blunted ex-vivo LPS-induced alveolar macrophage generation of CXCL1, TNF-α, IL-13 and IL-12p40.

Conclusion

AZM treatment altered both lung microbiota and metabolome, affecting anti-inflammatory bacterial metabolites that may contribute to its therapeutic effects.

Trial registration number

NCT02557958.

Investigating NF-κB signaling in lung fibroblasts in 2D and 3D culture systems

BACKGROUND

Inflammatory respiratory diseases are amongst major global health challenges. Lung fibroblasts have been shown to play a key role in lung inflammatory responses. However, their exact role in initiation and maintenance of lung diseases has remained elusive partly due to the limited availability of physiologically relevant in vitro models. Therefore, developing new tools that enable investigating the molecular pathways (e.g. nuclear factor-kappa B (NF-κB) activation) that underpin inflammatory responses in fibroblasts could be a valuable resource for scientists working in this area of research.

RESULTS

In order to investigate NF-κB activation in response to pro-inflammatory stimuli in real-time, we first developed two detection systems based on nuclear localization of NF-κB by immunostaining and luciferase reporter assay system. Furthermore using electrospun porous scaffolds, with similar geometry to human lung extracellular matrix, we developed 3D cultures of lung fibroblasts allowing comparing NF-κB activation in response to pro-inflammatory stimuli (i.e. TNF-α) in 2D and 3D. Our data clearly show that the magnitude of NF-κB activation in 2D cultures is substantially higher than 3D cultures. However, unlike 2D cultures, cells in the 3D model remained responsive to TNF-α at higher concentrations. The more subdued and wider dynamic range of NF-κB responses in 3D culture system was associated with a different expression pattern for TNF receptor I in 3D versus 2D cultures collectively reflecting a more in vivo like TNF receptor I expression and NF-κB activation pattern in the 3D system.

CONCLUSION

Our data suggest that lung fibroblasts are actively involved in the pathogenesis of lung inflammation by activation of NF-κB signaling pathway. The 3D culture detection system provides a sensitive and biologically relevant tool for investigating different pro-inflammatory events involving lung fibroblasts.

Elevated H3K18 acetylation in airway epithelial cells of asthmatic subjects

Background

Epigenetic adjustments of the chromatin architecture through histone modifications are reactive to the environment and can establish chromatin states which are permissive or repressive to gene expression. Epigenetic regulation of gene expression is cell specific and therefore, it is important to understand its contribution to individual cellular responses in tissues like the airway epithelium which forms the mucosal barrier to the inhaled environment within the lung. The airway epithelium of asthmatics is abnormal with dysregulation of genes such as epidermal growth factor receptor (EGFR), the ΔN isoform of the transcription factor p63 (ΔNp63), and signal transducer and activator of transcription 6 (STAT6), integral to differentiation, proliferation, and inflammation. It is important to establish in diseases like asthma how histone modifications affect tissue responses such as proliferation and differentiation.

Objectives

To characterize the global histone acetylation and methylation status in the epithelium of asthmatic compared to healthy subjects and to identify the impact of these variations on genes involved in epithelial functions.

Methods

Whole lungs were obtained from healthy and asthmatic subjects (n = 6) from which airway epithelial cells (AECs) were isolated and airway sections were taken for analysis of histone lysine acetylation and methylation by immunohistochemistry. AECs were subjected to chromatin immunoprecipitation (ChIP) using anti-H3K18ac and anti-H3K4me2 antibodies followed by RT-PCR targeting ΔNp63, EGFR, and STAT6. AECs were also treated with TSA and changes in ΔNp63, EGFR, and STAT6 expression were determined.

Results

We identified an increase in the acetylation of lysine 18 on histone 3 (H3K18ac) and trimethylation of lysine 9 on histone 3 (H3K9me3) in the airway epithelium of asthmatic compared to healthy subjects. We found increased association of H3K18ac around the transcription start site of ΔNp63, EGFR, and STAT6 in AECs of asthmatics. However, we were unable to modify the expression of these genes with the use of the HDAC inhibitor TSA in healthy subjects.

Discussion

The airway epithelium from asthmatic subjects displays increased acetylation of H3K18 and association of this mark around the transcription start site of ΔNp63, EGFR, and STAT6. These findings suggest a complex interaction between histone modifications and gene regulation in asthma.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-015-0254-y) contains supplementary material, which is available to authorized users.

Preliminary expression profile of cytokines in brain tissue of BALB/c mice with Angiostrongylus cantonensis infection

Background

Angiostrongylus cantonensis (A. cantonensis) infection can result in increased risk of eosinophilic meningitis. Accumulation of eosinophils and inflammation can result in the A. cantonensis infection playing an important role in brain tissue injury during this pathological process. However, underlying mechanisms regarding the transcriptomic responses during brain tissue injury caused by A. cantonensis infection are yet to be elucidated. This study is aimed at identifying some genomic and transcriptomic factors influencing the accumulation of eosinophils and inflammation in the mouse brain infected with A. cantonensis.

Methods

An infected mouse model was prepared based on our laboratory experimental process, and then the mouse brain RNA Libraries were constructed for deep Sequencing with Illumina Genome Analyzer. The raw data was processed with a bioinformatics’ pipeline including Refseq genes expression analysis using cufflinks, annotation and classification of RNAs, lncRNA prediction as well as analysis of co-expression network. The analysis of Refseq data provides the measure of the presence and prevalence of transcripts from known and previously unknown genes.

Results

This study showed that Cys-Cys (CC) type chemokines such as CCL2, CCL8, CCL1, CCL24, CCL11, CCL7, CCL12 and CCL5 were elevated significantly at the late phase of infection. The up-regulation of CCL2 indicated that the worm of A. cantonensis had migrated into the mouse brain at an early infection phase. CCL2 could be induced in the brain injury during migration and CCL2 might play a major role in the neuropathic pain caused by A. cantonensis infection. The up-regulated expression of IL-4, IL-5, IL-10, and IL-13 showed Th2 cell predominance in immunopathological reactions at late infection phase in response to infection by A. cantonensis. These different cytokines can modulate and inhibit each other and function as a network with the specific potential to drive brain eosinophilic inflammation. The increase of ATF-3 expression at 21 dpi suggested the injury of neuronal cells at late phase of infection. 1217 new potential lncRNA were candidates of interest for further research.

Conclusions

These cytokine networks play an important role in the development of central nervous system inflammation caused by A. cantonensis infection.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-0939-6) contains supplementary material, which is available to authorized users.

Deep sequencing-based transcriptional analysis of bovine mammary epithelial cells gene expression in response to in vitro infection with Staphylococcus aureus stains

Staphylococcus aureus (S. aureus) is an important etiological organism in chronic and subclinical mastitis in lactating cows. Given the fundamental role the primary bovine mammary epithelial cells (pBMECs) play as a major first line of defense against invading pathogens, their interactions with S. aureus was hypothesized to be crucial to the establishment of the latter’s infection process. This hypothesis was tested by investigating the global transcriptional responses of pBMECs to three S. aureus strains (S56,S178 and S36) with different virulent factors, using a tag-based high-throughput transcriptome sequencing technique. Approximately 4.9 million total sequence tags were obtained from each of the three S. aureus-infected libraries and the control library. Referenced to the control, 1720, 219, and 427 differentially expressed unique genes were identified in the pBMECs infected with S56, S178 and S36 S. aureus strains respectively. Gene ontology (GO) and pathway analysis of the S56-infected pBMECs referenced to those of the control revealed that the differentially expressed genes in S56-infected pBMECs were significantly involved in inflammatory response, cell signalling pathways and apoptosis. In the same vein, the clustered GO terms of the differentially expressed genes of the S178-infected pBMECs were found to comprise immune responses, metabolism transformation, and apoptosis, while those of the S36-infected pBMECs were primarily involved in cell cycle progression and immune responses. Furthermore, fundamental differences were observed in the levels of expression of immune-related genes in response to treatments with the three S. aureus strains. These differences were especially noted for the expression of important pro-inflammatory molecules, including IL-1α, TNF, EFNB1, IL-8, and EGR1. The transcriptional changes associated with cellular signaling and the inflammatory response in this study may reflect different immunomodulatory mechanisms that underlie the interaction between pBMECs and S. aureus strains during infection by the latter.

Muramyl dipeptide mediated activation of human bronchial epithelial cells interacting with basophils: a novel mechanism of airway inflammation

Respiratory tract bacterial infection can amplify and sustain airway inflammation. Intracytosolic nucleotide-binding oligomerization domain-containing protein 2 (NOD2) is one member of the nucleotide binding and oligomerization domain (NOD)-like receptor (NLR) family, which senses the conserved structural peptidoglycan component muramyl dipeptide (MDP) in almost all bacteria. In the present study, activation of the NOD2 ligand MDP on primary human bronchial epithelial cells (HBE) co-cultured with human basophils was investigated. Cytokines, NOD2, adhesion molecules and intracellular signalling molecules were assayed by enzyme-linked immunosorbent assay or flow cytometry. The protein expression of NOD2 was confirmed in basophils/KU812 cells and HBE/human bronchial epithelial cell line (BEAS-2B) cells. MDP was found to up-regulate significantly the cell surface expression of intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 on basophils and HBE in the co-culture system with or without basophil priming by interleukin (IL)-33 (all P < 0·05). MDP could further enhance the release of inflammatory cytokine IL-6 and chemokine CXCL8, and epithelium-derived anti-microbial peptide β-defensin 2 in the co-culture. HBE cells were the major source for the release of IL-6, CXCL8 and β-defensin2 upon stimulation by MDP in the co-culture system. The expression of ICAM-1 and VCAM-1 and release of IL-6 and CXCL8 were suppressed by various signalling molecule inhibitors, implying that the interaction between basophils and primary human bronchial epithelial cells could be regulated differentially by the mitogen-activated protein kinase pathways and nuclear transcription factors. The results therefore provide a new insight into the functional role of basophils in innate immunity, and the link between respiratory bacteria-mediated innate immunity and subsequent amplification of allergic inflammation in the airway.

Effect of TGF-β on ocular surface epithelial cells

A role for transforming growth factor (TGF)-β in the pathogenesis of some ocular surface diseases has been proposed. We determined if secretion of TGF-β and expression of TGF-β receptors RI, RII, and RIII by human ocular surface epithelial cells were modified under inflammatory conditions. We also determined how these cells responded to TGF-β. A human corneal epithelial (HCE) cell line and a conjunctival epithelial cell line (IOBA-NHC) were exposed to TGF-β1 and -β2 and to proinflammatory cytokines. TGF-β receptor mRNAs were analyzed by real time reverse transcription polymerase chain reaction (RT-PCR) in both cell lines, and in conjunctival, limbal, and corneal epithelial cells from post-mortem human specimens. Expression of TGF-β receptors and pSMAD2/SMAD2 were determined by Western blot and immunofluorescence assays. Secretion of TGF-β isoforms, cytokine/chemokine, and metalloproteinases (MMPs) were analyzed in cell supernatants by immunobead-based assays. Secretory leukocyte proteinase inhibitor (SLPI) secretion was analyzed by enzyme-linked immunosorbent assay. TGF-β isoform and receptor gene expression was determined by RT-PCR in conjunctival epithelium of dry eye (DE) patients and healthy subjects. Our results showed that TGF-β RI expression was down-regulated with IL-4 exposure, whereas TGF-β RII and TGF-β2 were upregulated by TNF-α in HCE cells. TGF-β RIII receptor expression was upregulated in IOBA-NHC cells by TNF-α and IFN-γ. SMAD2 phosphorylation occurred in HCE and IOBA-NHC cells after TGF-β treatment. TGF-β significantly up- and down-regulated secretion of several cytokines/chemokines by both cell lines and MMP by HCE cells. TGF-β2 and TGF-β3 were upregulated and TGF-β RIII mRNA was down-regulated in DE conjunctival epithelium. These results show that TGF-β plays an important role in directing local inflammatory responses in ocular surface epithelial cells.

IL-4 attenuates pulmonary epithelial cell-mediated suppression of T cell priming

We have previously shown that Th2-polarized airway inflammation facilitates sensitization towards new, protein antigens. In this context, we could demonstrate that IL-4 needs to act on cells of the hematopoetic and the structural compartment in order to facilitate sensitization towards new antigens. We thus aimed to elucidate possible mechanisms of action of IL-4 on structural cells choosing to analyze pulmonary epithelial cells as an important part of the lung's structural system. We used a co-culture system of DC- or APC-dependent in vitro priming of T cells, co-cultivated on a layer of cells of a murine pulmonary epithelial cell line (LA-4) pretreated with or without IL-4. Effects on T cell priming were analyzed via CFSE-dilution and flow cytometric assessment of activation status. Pulmonary epithelial cells suppressed T cell proliferation in vitro but this effect was attenuated by pre-treatment of the epithelial cells with IL-4. Transwell experiments suggest that epithelial-mediated suppression of T cell activation is mostly cell-contact dependent and leads to attenuation in an early naive T cell phenotype. Secretion of soluble factors like TARC, TSLP, GM-CSF and CCL20 by epithelial cells did not change after IL-4 treatment. However, analysis of co-stimulatory expression on pulmonary epithelial cells revealed that pre-treatment of epithelial cells with IL-4 changed expression GITR-L, suggesting a possible mechanism for the effects observed. Our studies provide new insight into the role of IL-4 during the early phases of pulmonary sensitization: The inhibitory activity of pulmonary epithelial cells in homeostasis is reversed in the presence of IL-4, which is secreted in the context of Th2-dominated allergic airway inflammation. This mechanism might serve to explain facilitated sensitization in the clinical context of polysensitization where due to a pre-existing sensitization increased levels of IL-4 in the airways might facilitate T cell priming towards new antigens.

Anti-malarial drug artesunate attenuates experimental allergic asthma via inhibition of the phosphoinositide 3-kinase/Akt pathway

BACKGROUND

Phosphoinositide 3-kinase (PI3K)/Akt pathway is linked to the development of asthma. Anti-malarial drug artesunate is a semi-synthetic derivative of artemisinin, the principal active component of a medicinal plant Artemisia annua, and has been shown to inhibit PI3K/Akt activity. We hypothesized that artesunate may attenuate allergic asthma via inhibition of the PI3K/Akt signaling pathway.

METHODOLOGY/PRINCIPAL FINDINGS

Female BALB/c mice sensitized and challenged with ovalbumin (OVA) developed airway inflammation. Bronchoalveolar lavage fluid was assessed for total and differential cell counts, and cytokine and chemokine levels. Lung tissues were examined for cell infiltration and mucus hypersecretion, and the expression of inflammatory biomarkers. Airway hyperresponsiveness was monitored by direct airway resistance analysis. Artesunate dose-dependently inhibited OVA-induced increases in total and eosinophil counts, IL-4, IL-5, IL-13 and eotaxin levels in bronchoalveolar lavage fluid. It attenuated OVA-induced lung tissue eosinophilia and airway mucus production, mRNA expression of E-selectin, IL-17, IL-33 and Muc5ac in lung tissues, and airway hyperresponsiveness to methacholine. In normal human bronchial epithelial cells, artesunate blocked epidermal growth factor-induced phosphorylation of Akt and its downstream substrates tuberin, p70S6 kinase and 4E-binding protein 1, and transactivation of NF-κB. Similarly, artesunate blocked the phosphorylation of Akt and its downstream substrates in lung tissues from OVA-challenged mice. Anti-inflammatory effect of artesunate was further confirmed in a house dust mite mouse asthma model.

CONCLUSION/SIGNIFICANCE

Artesunate ameliorates experimental allergic airway inflammation probably via negative regulation of PI3K/Akt pathway and the downstream NF-κB activity. These findings provide a novel therapeutic value for artesunate in the treatment of allergic asthma.

Fibrogenic and redox-related but not proinflammatory genes are upregulated in Lewis rat model of chronic silicosis

Silicosis, a fibrotic granulomatous lung disease, may occur through accidental high-dose or occupational inhalation of silica, leading to acute/accelerated and chronic silicosis, respectively. While chronic silicosis has a long asymptomatic latency, lung inflammation and apoptosis are hallmarks of acute silicosis. In animal models, histiocytic granulomas develop within days after high-dose intratracheal (IT) silica instillation. However, following chronic inhalation of occupationally relevant doses of silica, discrete granulomas resembling human silicosis arise months after the final exposure without significant lung inflammation/apoptosis. To identify molecular events associated with chronic silicosis, lung RNA samples from controls or subchronic silica-exposed rats were analyzed by Affymetrix at 28 wk after silica exposures. Results suggested a significant upregulation of 144 genes and downregulation of 7 genes. The upregulated genes included complement cascade, chemokines/chemokine receptors, G-protein signaling components, metalloproteases, and genes associated with oxidative stress. To examine the kinetics of gene expression relevant to silicosis, quantitative polymerase chain reaction (qPCR), enzyme-linked immunosorbent assay (ELISA), Luminex-bead assays, Western blotting, and/or zymography were performed on lung tissues from 4 d, 28 wk, and intermediate times after subchronic silica exposure and compared with 14-d acute silicosis samples. Results indicated that genes regulating fibrosis (secreted phosphoprotein-1, Ccl2, and Ccl7), redox enzymes (superoxide dismutase-2 and arginase-1), and the enzymatic activities of matrix metalloproteinases 2 and 9 were upregulated in acute and chronic silicosis models. However, proinflammatory cytokines were strongly upregulated only in acute silicosis. Thus, inflammatory cytokines are associated with acute but not chronic silicosis. Data suggest that genes regulating fibrosis, oxidative stress, and metalloproteases may contribute to both acute and chronic silicosis.

Cytokine and chemokine levels in tears from healthy subjects

PURPOSE

There is growing evidence for the existence of an 'immune tone' in normal tears. The aim of this study was to determine the levels of a large panel of cytokines and chemokines in tears obtained from healthy subjects. These levels can then serve as baseline values for comparison with patients suffering from ocular surface diseases.

SUBJECTS AND METHODS

Nine healthy subjects participated in this study, and normal ocular surface health was documented by the results of a dry eye questionnaire, Schirmer strip wetting, and vital staining of the cornea. Four microliters of tears were collected from each eye and analysed separately with multiplex bead-based assays for the concentration of 30 cytokines and chemokines.

RESULTS

Twenty-five cytokines/chemokines were detected. CCL11/Eotaxin1, GM-CSF, G-CSF, IFN-γ, IL-2, IL-3, IL-4, IL-5, IL-10, IL-13, IL-12p70, IL-15, CX3CL1/Fractalkine, TNF-α, epidermal growth factor, and CCL4/MIP-1β were present at 5-100 pg/ml. IL-1β, IL-6, IL-7A, CXCL8/IL-8, and CCL2/MCP-1 were present at 100-400 pg/ml. IL-1Ra, CXCL10/IP-10 and vascular endothelial growth factor were present at more than 1000 pg/ml.

CONCLUSION

Multiplex bead-based assays are convenient for cytokine/chemokine detection in tears. Fracktalkine has been detected in human healthy tears for the first time. The knowledge of cytokine/chemokine concentrations in tears from normal subjects is an important reference for further comparison with patients suffering from ocular surface diseases. Variability in their levels can reflect a phenomenon of potential importance for the understanding of the ocular surface cytokine pattern.

Analysis of eotaxin 1/CCL11, eotaxin 2/CCL24 and eotaxin 3/CCL26 expression in lesional and non-lesional skin of patients with atopic dermatitis

Eotaxins are the chemokines which are highly selective chemotactic agents for eosinophils. The aim of our study was the evaluation of the gene expression level for eotaxin 1/CCL11, eotaxin 2/CCL24, and eotaxin 3/CCL26, both in skin changes and in uninvolved skin of atopic dermatitis (AD) patients. The study comprised 19 patients with AD and 10 healthy controls. The gene expression level for eotaxins in the skin biopsies was evaluated by the real-time quantitative PCR. The change of the gene expression level, calculated as log10 skin lesions/non-lesional skin, was 0.635 for CCL11, 0.172 for CCL24 and 0.291 for CCL26. The change of the gene expression level, calculated as log10 non-lesional skin of AD patients/healthy control, was 0.394 for CCL11, -0.216 for CCL24, and 0.229 for CCL26, while skin lesions of AD patients/healthy control, was: 0.788, -0.046, and 0.483, respectively.

CONCLUSION

The mean gene expression level for CCL11, CCL24, CCL26 was higher in skin changes of AD patients than in uninvolved skin. The higher level of CCL26 in skin changes, indicates its role in their aetiology in AD. The gene expression level for CCL24 in AD patients was lower, both in involved and uninvolved skin vs. the healthy control.

Cytokine responses by conjunctival epithelial cells: an in vitro model of ocular inflammation

OBJECTIVES

We examined the differential secretion of cytokines by a conjunctival epithelial cell line in response to proinflammatory cytokines to identify the potential contributions during ocular surface inflammation.

METHODS

A conjunctival epithelial cell line was exposed to IFN-gamma, TNF-alpha, IL-4, or IL-13, and cytokine production was determined in supernatants at different times after exposure. Cell apoptosis was measured by flow cytometry.

RESULTS

TNF-alpha induced the greatest effect on cytokine secretion, which was time-dependent. TNF-alpha-stimulated secretion of IL-12p40 was significantly increased by 30 min; GM-CSF, MCP-1, IL-6, IL-7, IL-8, and RANTES were significantly increased by 2 h, and IFN-gamma and IL-1alpha by 24 h. After 48 h, TNF-alpha also induced a significant increase in IL-1beta, IL-3, and IP-10 secretion. IFN-gamma significantly enhanced IP-10 and RANTES secretion after 48 h of exposure. Following IL-4 treatment there was a significant increase in eotaxin-1 after 24h, and IL-12p40 and IL-3 after 48 h. IL-13 significantly increased the secretion of eotaxin-1 after 24 h, and IL-8 after 48 h.

CONCLUSION

Our results suggest that conjunctival epithelial cells are an important source of cytokines and chemokines that are regulated by proinflammatory cytokines and may play an important role in ocular surface inflammation.

Interleukin-4, interleukin-13, signal transducer and activator of transcription factor 6, and allergic asthma

Interleukin (IL)-4 and IL-13 share many biological activities. To some extent, this is because they both signal via a shared receptor, IL-4Ralpha. Ligation of IL-4Ralpha results in activation of Signal Transducer and Activator of Transcription factor 6 (STAT6) and Insulin Receptor Substrate (IRS) molecules. In T- and B-cells, IL-4Ralpha signaling contributes to cell-mediated and humoral aspects of allergic inflammation. It has recently become clear that IL-4 and IL-13 produced in inflamed tissues activate signaling in normally resident cells of the airway. The purpose of this review is to critically evaluate the contributions of IL-4- and IL-13-induced tissue responses, especially those mediated by STAT6, to some of the pathologic features of asthma including eosinophilic inflammation, airway hyperresponsiveness, subepithelial fibrosis and excessive mucus production. We also review the functions of some recently identified IL-4- and/or IL-13-induced mediators that provide some detail on molecular mechanisms and suggest an important contribution to host defense.

Pulmonary eosinophilia requires interleukin-5, eotaxin-1, and CD4+ T cells in mice immunized with respiratory syncytial virus G glycoprotein

Severe illness, type 2 cytokine production, and pulmonary eosinophilia are adverse immune responses resulting from respiratory syncytial virus (RSV) challenge of vvGs-immunized mice. We have shown IL-4 and IL-13 activity must be simultaneously inhibited to reduce disease severity. We now address the contributions of IL-5, eotaxin-1, and CD4+ and CD8+ T cells to the induction of disease-enhancing immune responses. Depletion of CD4+ T cells during immunization prevented IL-4, IL-13, and eotaxin-1 production, diminished eosinophilia, and reduced weight loss. Conversely, CD8+ T cell depletion did not decrease eosinophilia, weight loss, or type 2 cytokines but did dramatically reduce mucus production and increase eotaxin production. Anti-IL-5 administration at immunization or challenge significantly decreased pulmonary eosinophilia. Strikingly, there were not concomitant decreases in weight loss. Following RSV challenge eotaxin-1-deficient mice immunized with vvGs exhibited significantly less eosinophilia without decreased weight loss or type 2 cytokine production. We conclude CD4+ T cell production of IL-5 and induction of eotaxin-1 are required for vvGs-induced eosinophilia following RSV challenge, while CD8+ T cells appear to down-regulate eotaxin-1 and mucus production. In summary, we demonstrate that pulmonary eosinophilia 1) is a by-product of memory CD4+ T cell activation, 2) does not necessarily correlate with mucus production, and, most importantly, 3) is not required for the RSV G-induced illness in mice. These findings have important implications for the evaluation of candidate RSV vaccines.

Toll-like receptor 2 down-regulation in established mouse allergic lungs contributes to decreased mycoplasma clearance

RATIONALE

Respiratory Mycoplasma pneumoniae (Mp) infection is involved in asthma pathobiology, but whether the established allergic airway inflammation compromises lung innate immunity and subsequently predisposes patients with asthma to Mp infection remains unknown.

OBJECTIVES

To test whether the established allergic airway inflammation compromises host innate immunity (e.g., Toll-like receptor 2 [TLR2]) to hinder the elimination of Mp from the lungs.

METHODS

We used mouse models of ovalbumin (OVA)-induced allergic airway inflammation with an ensuing Mp infection, and cultures of mouse primary lung dendritic cells (DCs) and bone marrow-derived DCs.

MEASUREMENTS AND MAIN RESULTS

Lung Mp clearance in allergic mice and TLR2 and IL-6 levels in lung cells, including DCs as well as cultured primary lung DCs and bone marrow-derived DCs, were assessed. The established OVA-induced allergic airway inflammation, or the prominent Th2 cytokines IL-4 and IL-13, inhibited TLR2 expression and IL-6 production in lung cells, including lung DCs, and eventually led to impaired host defense against Mp. Studies in IL-6 knockout mice indicated that IL-6 directly promoted Mp clearance from the lungs. IL-4- and IL-13-induced suppression of TLR2 was mediated by inhibiting nuclear factor-kappaB activation through signal transducer and activator of transcription 6 (STAT6) signaling pathway.

CONCLUSIONS

The established OVA-induced allergic airway inflammation impairs TLR2 expression and host defense cytokine (e.g., IL-6) production, and subsequently delays lung bacterial clearance. This could offer novel therapeutic strategies to reinstate TLR2 activation by using TLR2 ligands and/or blocking IL-4 and IL-13 to ameliorate persisting respiratory bacterial infections in allergic lungs.

Interleukin-31 induces cytokine and chemokine production from human bronchial epithelial cells through activation of mitogen-activated protein kinase signalling pathways: implications for the allergic response

Interleukin-31 (IL-31) is a novel T-helper-lymphocyte-derived cytokine that plays an important role in allergic skin inflammation and atopic dermatitis. It has recently been implicated in bronchial inflammation. We investigated the functions and mechanisms of IL-31-induced activation of human bronchial epithelial cells. The gene and protein expressions of candidate cytokines/chemokines from IL-31-stimulated human bronchial epithelial BEAS-2B cells were first quantified by quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. The activity of different mitogen-activated protein kinases (MAPKs) in IL-31-stimulated BEAS-2B cells was assessed by Western blot. The IL-31 could significantly elevate the gene and protein expressions of epidermal growth factor (EGF), vascular endothelial growth factor (VEGF) and monocyte chemoattractant protein-1 (MCP-1/CCL2) of BEAS-2B cells in both time-dependently and dose-dependently. Combination of IL-31 with either IL-4 or IL-13 further enhanced VEGF and CCL2 production while IL-31 could synergistically augment the release of EGF, VEGF, CCL2, IL-6 and IL-8 in cocultures of BEAS-2B cells and eosinophils. In addition, IL-31 could activate p38 MAPK, extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) of BEAS-2B cells. Selective inhibitors of p38 MAPK (SB203580), ERK (PD98059), and JNK (SP600125) could differentially inhibit the production of EGF, VEGF and CCL2, thereby suggesting a role for MAPKs in IL-31 functions. In conclusion, the activation of MAPKs can be crucial for IL-31-mediated activation of bronchial epithelial cells, thereby providing an immunological role for IL-31 in bronchial inflammation, at least partly, via epithelial EGF, VEGF and CCL2 production.

Differential cytokine and chemokine responses of bovine mammary epithelial cells to Staphylococcus aureus and Escherichia coli

We studied the inflammatory and immune responses of bovine mammary epithelial cells (bMEC) infected by mastitis isolates of Staphylococcus aureus. Primary cultures of bMEC were co-incubated separately with three strains of S. aureus and one strain of Escherichia coli. Transcriptional levels and/or protein release of interleukin-8 (IL-8), growth related oncogene alpha (GRO-alpha), growth related oncogene beta (GRO-beta), tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), transforming growth factor beta1 (TGF-beta1) and interleukin-10 (IL-10) were measured at 3, 10 and 24h post-infection (PI). The results indicated that at earlier hours of co-culture, bMEC infected with S. aureus or E. coli expressed more IL-1beta, TNF-alpha, IL-8 and GRO-alpha mRNA than uninfected bMEC. Furthermore, infected bMEC released more TNF-alpha, IL-8, GRO-alpha and GRO-beta proteins than uninfected bMEC. However, differential transcription and release of some cytokines/chemokines from bMEC was observed according to the strain of S. aureus and bacteria Gram type. In conclusion, bMEC did not show an anti-inflammatory potential through IL-10 or TGF-beta1 release. Nevertheless, bMEC were able to release neutrophil-mobilizing chemokines and pro-inflammatory cytokines upon bacterial stimulation, strongly suggesting that bMEC are active contributors to immune and inflammatory responses of mammary gland. In addition, the clinical characteristics and resolution of mastitis may be partly determined by the responses of bMEC according to S. aureus strains and bacteria Gram type.

IL-12 contributes to allergen-induced airway inflammation in experimental asthma

Lack of sufficient IL-12 production has been suggested to be one of the basic underlying mechanisms in atopy, but a potential role of IL-12 in established allergic airway disease remains unclear. We took advantage of a mouse model of experimental asthma to study the role of IL-12 during the development of bronchial inflammation. Administration of anti-IL-12p35 or anti-IL-12p40 mAb to previously OVA-sensitized BALB/c mice concomitantly with exposure to nebulized OVA, abolished both the development of bronchial hyperresponsiveness to metacholine as well as the eosinophilia in bronchoalveolar lavage fluid and peripheral blood. Anti-IL-12 treatment reduced CD4(+) T cell numbers and IL-4, IL-5, and IL-13 levels in the bronchoalveolar lavage fluid and the mRNA expression of IL-10, eotaxin, RANTES, MCP-1, and VCAM-1 in the lung. Anti-IL-12p35 treatment failed to show these effects in IFN-gamma knockout mice pointing to the essential role of IFN-gamma in IL-12-induced effects. Neutralization of IL-12 during the sensitization process aggravated the subsequent development of allergic airway inflammation. These data together with recent information on the role of dendritic cells in both the sensitization and effector phase of allergic respiratory diseases demonstrate a dual role of IL-12. Whereas IL-12 counteracts Th2 sensitization, it contributes to full-blown allergic airway disease upon airway allergen exposure in the postsensitization phase, with enhanced recruitment of CD4(+) T cells and eosinophils and with up-regulation of Th2 cytokines, chemokines, and VCAM-1. IFN-gamma-producing cells or cells dependent on IFN-gamma activity, play a major role in this unexpected proinflammatory effect of IL-12 in allergic airway disease.

Interleukin (IL)-4 and IL-13 up-regulate monocyte chemoattractant protein-1 expression in human bronchial epithelial cells: involvement of p38 mitogen-activated protein kinase, extracellular signal-regulated kinase 1/2 and Janus kinase-2 but not c-Jun NH2-terminal kinase 1/2 signalling pathways

The Th2 cytokines interleukin (IL)-4 and IL-13 and chemokine monocyte chemoattractant protein-1 (MCP-1) are significantly involved in bronchial hyperreactivity (BHR) and remodelling in allergic asthma. Although IL-4 and IL-13 can regulate a number of chemokines from bronchial epithelium, their regulatory effect on the expression of MCP-1 is as yet unproved. We aim to investigate the intracellular signalling mechanisms of IL-4 and IL-13 regulating the expression and secretion of MCP-1 from human bronchial epithelial cells. BEAS-2B cells, derived from a human bronchial epithelial cell line, were activated with or without IL-4 and/or IL-13 for different time intervals. MCP-1 gene expression and protein secretion were measured by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Activation of signalling molecules p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK) and Janus kinase-2 (JAK-2) was accessed by Western blotting. IL-4 and IL-13 were found to up-regulate gene expression and significantly increase the release of MCP-1 from BEAS-2B cells. Both cytokines could activate p38 MAPK, ERK and JAK-2, but not JNK activity. Inhibition of p38 MAPK, ERK and JAK-2 activities by pretreating the cells with their corresponding inhibitors SB203580, PD98059 and AG490, respectively, significantly suppressed IL-4- and IL-13-induced MCP-1 production in BEAS-2B cells. Together, the above results illustrate that the activation of p38 MAPK, ERK and JAK-2 but not JNK is crucial for IL-4- and IL-13-induced MCP-1 release in human bronchial epithelial cells. Our findings may provide insight into the future development of more effective therapeutic agents for treating allergic asthma.

GRO-alpha regulation in airway smooth muscle by IL-1beta and TNF-alpha: role of NF-kappaB and MAP kinases

Airway smooth muscle cells (ASMC) are a source of inflammatory chemokines that may propagate airway inflammatory responses. We investigated the production of the CXC chemokine growth-related oncogene protein-alpha (GRO-alpha) from ASMC induced by cytokines and the role of MAPK and NF-kappaB pathways. ASMC were cultured from human airways, grown to confluence, and exposed to cytokines IL-1beta and TNF-alpha after growth arrest. GRO-alpha release, measured by ELISA, was increased by >50-fold after IL-1beta (0.1 ng/ml) or 5-fold after TNF-alpha (1 ng/ml) in a dose- and time-dependent manner. GRO-alpha release was not affected by the T helper type 2 cytokines IL-4, IL-10, and IL-13. IL-1beta and TNF-alpha also induced GRO-alpha mRNA expression. Supernatants from IL-1beta-stimulated ASMC were chemotactic for neutrophils; this effect was inhibited by anti-GRO-alpha blocking antibody. AS-602868, an inhibitor of IKK-2, and PD-98059, an inhibitor of ERK, inhibited GRO-alpha release and mRNA expression, whereas SP-600125, an inhibitor of JNK, reduced GRO-alpha release without effect on mRNA expression. SB-203580, an inhibitor of p38 MAPK, had no effect. AS-602868 but not PD-98059 or SP-600125 inhibited p65 DNA-binding induced by IL-1beta and TNF-alpha. By chromatin immunoprecipitation assay, IL-1beta and TNF-alpha enhanced p65 binding to the GRO-alpha promoter, which was inhibited by AS-602868. IL-1beta- and TNF-alpha-stimulated expression of GRO-alpha from ASMC is regulated by independent pathways involving NF-kappaB activation and ERK and JNK pathways. GRO-alpha released from ASMC participates in neutrophil chemotaxis.

Defensin and chemokine expression patterns in the palatine tonsil: a model of their local interaction

Defensins and chemokines are an essential part of the immune response mechanisms in the head and neck mucosa. This work investigates their correlation and their expression pattern in tonsillar disease. Forty-four tonsil tissue samples were obtained from patients who underwent tonsillectomy between 1998 and 1999 for chronic tonsillitis with (n =9) and without (n =25) inflammatory infiltrates and hyperplasia of the tonsil (n =10). Defensin (hBD-1, hBD-2, HNP-1 and HNP-4) and chemokine (RANTES, eotaxin, eotaxin-2, MCP-3, MCP-4 and IL-8) mRNA expressions were analyzed by SQRT-PCR. HNP-4 and eotaxin-2 expressions were positively correlated (P <0.05) in the acute tonsillitis group. HBD-2 and MCP-3 expressions were positively correlated in the hyperplastic tonsils group. Within all groups together, HNP-4 and RANTES expressions were highly positively correlated (P <0.01), and HNP-1 and hBD-2 were positively correlated with IL-8 expressions. Immunohistochemistry demonstrated eotaxin-1 as well as IL-8 production to be predominantly located within the lymphoid follicles and submucosa. RANTES production was shown in the epithelial lining and perivascular tissue. The expression of hBD-1 and hBD-2 was limited to the epithelial lining. Our data support an association between the innate and acquired immune systems on the defensin-chemokine level. The finding of positively correlated hBD-2 and IL-8 expression is biologically relevant because of the proximity of hBD-2 (epithelium) and IL-8 (submucosa) release, as well as the synergistic support of the Th1 system. In addition, our data suggest RANTES as a first-line mediator of perivascular leukocyte recruitment.

Matrix metalloproteinase-8 deficiency promotes granulocytic allergen-induced airway inflammation

Matrix metalloproteinases (MMPs) are involved in inflammatory reaction, including asthma-related airway inflammation. MMP-8, mainly produced by neutrophils, has recently been reported to be increased in the bronchoalveolar lavage fluid (BALF) from asthmatic patients. To evaluate the role of MMP-8 in asthma, we measured MMP-8 expression in lung tissue in an OVA-sensitized mouse model of asthma and addressed the effect of MMP-8 deletion on allergen-induced bronchial inflammation. MMP-8 production was increased in lungs from C57BL/6 mice exposed to allergens. After allergen exposure, MMP-8(-/-) mice developed an airway inflammation characterized by an increased neutrophilic inflammation in BALF and an increased neutrophilic and eosinophilic infiltration in the airway walls. MMP-8 deficiency was associated with increased levels of IL-4 and anti-OVA IgE and IgG1 in BALF and serum, respectively. Although allergen exposure induced an enhancement of LPS-induced CXC chemokine, KC, and MIP-2 levels in BALF and lung parenchyma, no difference was observed between the two genotypes. Inflammatory cell apoptosis was reduced in the lungs from MMP-8(-/-) mice. For the first time, our study evidences an important role of MMP-8 in the control of neutrophilic and eosinophilic infiltration during allergen-induced lung inflammation, and demonstrates that the anti-inflammatory effect of MMP-8 is partly due to a regulation of inflammatory cell apoptosis.

The role of the conjunctival epithelium in ocular allergy

PURPOSE OF REVIEW

The epithelium of target organs is playing an increasing role in allergy. Several studies have shown that epithelial cells participate actively in inflammatory processes. This review will focus on recent advances in the role of conjunctival epithelium in allergy as a potential target for therapeutic interventions.

RECENT FINDINGS

Several studies have already shown the involvement of ocular surface epithelial cells in allergic inflammatory diseases, because they are able to produce and secrete cytokines and chemokines upon stimulation. They also express adhesion molecules as well as receptors for several substances implicated in inflammation. Some studies have also shown that conjunctival epithelial cells express co-stimulatory molecules when they interact with activated T cells, adding more evidence to the important role that epithelial cells play in the pathogenesis of ocular inflammatory diseases. Recent reports have also demonstrated that during inflammatory conditions, conjunctival epithelial cells show an altered expression of their neuroreceptors, suggesting that a modulation of neural regulation may be of therapeutic value.

SUMMARY

The ocular surface epithelium is not just a simple physical barrier to the entrance of foreign bodies. It participates in the allergic inflammatory process by being influenced by inflammatory molecules, and by secreting inflammatory cytokines and chemokines. Moreover, the epithelium not only actively participates in the inflammation process but can also initiate it. This relevant spectrum of actions makes epithelium an attractive target for therapeutic interventions.

Eotaxin-3/CCL26 gene expression in intestinal epithelial cells is up-regulated by interleukin-4 and interleukin-13 via the signal transducer and activator of transcription 6

Several inflammatory processes of the bowel are characterized by an accumulation of eosinophils at sites of inflammation. The mechanisms that govern mucosal infiltration with eosinophils are not fully understood. Eotaxin-3/CCL-26 belongs to a family of CC chemokines, which are potent chemoattractants for eosinophils. In this study, we hypothesized that intestinal epithelial cells could release eotaxin-3. We demonstrate that the T helper 2 type cytokines interleukin-4 or interleukin-13 increase eotaxin-3 mRNA levels and eotaxin-3 protein expression in the human intestinal epithelial cell lines HT-29 CL.19A and T84 in a dose-dependent manner. Addition of actinomycin-D prior to interleukin-4/-13 stimulation led to decreases in eotaxin-3 mRNA levels similar to those observed in controls without interleukin-4/-13. Interleukin-4 and interleukin-13 activated signal transducer and activator of transcription 6 which was found to bind the two canonical signal transducer and activator of transcription 6 binding sites located in the eotaxin-3 promoter. Experiments with the eotaxin-3 promoter luciferase constructs revealed that the most proximal signal transducer and activator of transcription 6 binding site located between positions -62 and -71 relative to the transcriptional start was necessary for full eotaxin-3 promoter activity. Importantly, we present evidence that the signal transducer and activator of transcription 6 is necessary and sufficient for interleukin-4 or interleukin-13 mediated eotaxin-3 gene up-regulation using HT-29 CL.19A cells expressing a dominant-negative signal transducer and activator of transcription 6. Overall, these results demonstrate that epithelial eotaxin-3 is up-regulated in the context of a T helper 2 mediated inflammatory bowel disease via the signal transducer and activator of transcription 6, thus suggesting that the intestinal epithelium actively participates in the recruitment of eosinophils at the site of inflammation.

Eotaxin-2 and eotaxin-3 expression is associated with persistent eosinophilic bronchial inflammation in patients with asthma after allergen challenge

BACKGROUND

Eotaxin-1, eotaxin-2, and eotaxin-3 are chemokines involved in the activation and recruitment of eosinophils through activation of their main receptor, CC chemokine receptor 3. The differential roles of these chemokines still remain to be established. It has been suggested that eotaxin-1 is an important mediator in the early phase of allergen-induced recruitment of eosinophils into the airways. Eotaxin-2 and eotaxin-3 might play a role in the subsequent persistence of allergen-induced bronchial eosinophilia.

OBJECTIVE

The aim of this study was to determine the expression of eotaxins and eosinophil counts in the bronchial mucosa of subjects with mild asthma after resolution of the late-phase asthmatic response (LAR).

METHODS

The expression of eotaxins and eosinophil counts were determined in bronchial biopsy specimens obtained from 10 subjects with mild asthma 48 hours after diluent and allergen challenge by using immunohistochemistry. Positively stained cells were counted in a 125-mum-deep zone of the lamina propria.

RESULTS

Eotaxin-2 and eotaxin-3 expression in bronchial mucosa was significantly increased 48 hours after allergen challenge ( P = .001 and P = .013, respectively). At this time point, when marked tissue eosinophilia was still present, these increases were positively correlated with the magnitude of the LAR ( r = 0.72, P = .019 and r = 0.64, P = .046, respectively). Furthermore, eotaxin-2 expression was associated with the number of eosinophils after allergen challenge ( r = 0.72, P = .018).

CONCLUSION

Our findings suggest that eotaxin-2 and eotaxin-3 might account for the persistence of bronchial eosinophilia after resolution of the LAR.

Autoregulation of CCL26 synthesis and secretion in A549 cells: a possible mechanism by which alveolar epithelial cells modulate airway inflammation

Eotaxins (CCL11, CCL24, CCL26) originating from airway epithelial cells and leukocytes have been detected in bronchoalveolar lavage of asthmatics. Although the alveolar epithelium is the destination of uncleared allergens and other inflammatory products, scanty information exists on their contribution to the generation and regulation of the eotaxins. We envisioned a state whereby alveolar type II cells, a known source of other inflammatory proteins, could be involved in both the production and regulation of CCL24 and CCL26. Herein, we demonstrated that all three eotaxins are constitutively expressed in A549 cells. IL-4 and IL-13 stimulated a concentration-dependent secretion of CCL24 and CCL26. The cytokines did not act synergistically. Cycloheximide and actinomycin D abrogated IL-4- and IL-13-dependent CCL26 but not CCL24 secretion. Both IL-13 and IL-4 stimulated CCL26 synthesis that was inhibited in a concentration-dependent manner by CCL26 but not CCL24. Only CCL26 reduced expression of CCR3 receptors by 30-40%. On the other hand, anti-CCR3 pretreatment reduced IL-4+IL-13-dependent CCL26 secretion, implying autoregulation. A CCR3-specific antagonist (SB-328437) significantly decreased IL-4-dependent synthesis and release of CCL26. Eosinophils treated with medium from IL-4-stimulated A549 cells preincubated with anti-CCL26 showed a marked decrease of superoxide anion production compared with anti-CCL24 treated. These results suggest that CCL26 is a major eotaxin synthesized and released by alveolar epithelial cells and is involved in autoregulation of CCR3 receptors and other eotaxins. This CCL26-CCR3 ligand-receptor system may be an attractive target for development of therapeutics that limits progress of inflammation in airway disease.

Oral corticosteroids decrease eosinophil and CC chemokine expression but increase neutrophil, IL-8, and IFN-gamma-inducible protein 10 expression in asthmatic airway mucosa

BACKGROUND

Cytokines and chemokines have been implicated in the pathogenesis of asthma. Inhaled corticosteroids have been shown to decrease the number of eosinophils and to downregulate T H 2 cytokines but to increase neutrophils. The effect of corticosteroids on chemokine expression in asthma has not yet been investigated.

OBJECTIVE

We sought to investigate the effect of a 2-week course of oral corticosteroid (methylprednisolone, 40 mg/d) on the expression of CXC chemokines (IL-8 and IFN-gamma-inducible protein 10 [IP-10]) and CC chemokines (eotaxin and monocyte chemotactic proteins [MCPs] 1-4) in endoscopic biopsy specimens of 13 patients with moderate-to-severe asthma.

METHODS

CD3, major basic protein, and elastase immunoreactivities were monitored before and after treatment by using immunocytochemistry. Eotaxin, IL-8, IP-10, MCP-1, MCP-2, MCP-3, and MCP-4 mRNA expression in epithelium and submucosa were studied by using in situ hybridization.

RESULTS

Corticosteroids reduced the number of CD3-positive T cells and major basic protein-positive eosinophils ( P < .05), whereas the number of neutrophils were increased ( P < .05). Corticosteroids also reduced the number of eotaxin ( P < .05), MCP-3, and MCP-4 mRNA-positive cells ( P < .001) in the epithelium and subepithelium. However, corticosteroids caused a significant increase in the epithelial expression of IL-8 ( P < .001), IP-10 ( P < .05), and MCP-2 mRNAs ( P < .01). Corticosteroids had no effects on MCP-1 mRNA expression.

CONCLUSION

Our results demonstrate the dual nature of corticosteroids. Although corticosteroids can downregulate the expression of some asthma-associated chemokines, such as eotaxin, MCP-3, and MCP-4, they can also upregulate the expression of other chemokines, including IL-8, IP-10, and MCP-2. The failure of oral corticosteroids to inhibit IL-8 mRNA expression might contribute to persistent airway neutrophilia observed in patients with moderate-to-severe asthma, despite treatment with corticosteroids.