Human lung myofibroblasts as effectors of the inflammatory process: the common receptor gamma chain is induced by Th2 cytokines, and CD40 ligand is induced by lipopolysaccharide, thrombin and TNF-alpha

The Atlantic salmon interleukin 4/13 receptor family: Structure, tissue distribution and modulation of gene expression

Interleukin (IL)-4 and IL-13 play a central role in T helper 2 immune response in mammals. The cell signalling is mediated by the type I heterodimeric receptor containing the IL-4Rα and γC chains, and the type II receptors formed by IL-4Rα and IL-13Rα1. In salmonid species, three paralogues of the IL-4 and IL-13 cytokines have been reported, il-4/13a, il-4/13b1 and il-4/13b2. In regard to receptors, two paralogues of each IL-4/13 receptor chains have been identified in rainbow trout while five genes named γc1, il-4rα, il-13rα1a, il-13rα1b, and il-13rα2 have identified in Atlantic salmon. Since Atlantic salmon is an important farmed fish species, the aim of this work was to get new insights into distribution, structure and expression regulation of the IL-4/13 receptors in salmon. By using qRT-PCR, it was shown that all γc1, il-4rα, il-13rα1a, il-13rα1b, and il-13rα2 receptor chains were expressed in lymphoid and non-lymphoid tissues of healthy salmon, nonetheless γC expression was higher in lymphoid than non-lymphoid tissues. The in silico structural analysis and homology modelling of the predicted receptor proteins showed that domains and most motifs present in the superior vertebrate chains are conserved in salmon suggesting a conserved role for these receptor chains. Only IL-13Rα1B is a receptor chain with a unique structure that seem not to be present in higher vertebrates but in fish species. In order to determine the regulatory role of IL-4/13 on the expression of receptor chains, Atlantic salmon il-4/13A gene was synthetized and cloned in pET15b. The recombinant IL-4/13A was produced in E. coli and the activity of the purified cytokine was confirmed in vitro. The regulatory role of IL-4/13A on the expression of their potential receptors was tested in salmon receiving the recombinant cytokine and effects were compared with those of the control group. The results showed that IL-4/13A induced the expression of its own gene and GATA-3, in the head kidney of fish but not in the spleen, while IL-10 increased in both lymphoid organs indicating a regulatory role of this cytokine on the induction of Th2 responses in salmon. IFN-γ and MHC class II were also later induced in head kidney. In regard to the expression of the receptor chains, IL-4/13A upregulated the expression of γC, IL-13Rα1A and IL-13Rα2A in the spleen but not in the head kidney of salmon, indicating a role on the modulation of cell signalling for the Th2 response. Furthermore, Piscirickettsia salmonis infection of Atlantic salmon occurred with an increase of γC and IL-13Rα1A suggesting a potential role of the IL-4/13 system in bacterial immunity or pathogenesis. This study contributes to a better understanding of the IL-4/13A system in salmon, which as a key axis for Th2 response may be involved not only in pathogen elimination but also in adaptive immune repair that seems critical tolerance to infectious diseases.

Immunomodulation by mesenchymal stem cells in treating human autoimmune disease-associated lung fibrosis

Background

Interstitial pneumonia in connective tissue diseases (CTD-IP) featuring inflammation and fibrosis is a leading cause of death in CTD-IP patients. The related autoimmune lung injury and disturbed self-healing process make conventional anti-inflammatory drugs ineffective. Equipped with unique immunoregulatory and regenerative properties, mesenchymal stem cells (MSCs) may represent a promising therapeutic agent in CTD-IP. In this study, we aim to define the immunopathology involved in pulmonary exacerbation during autoimmunity and to determine the potential of MSCs in correcting these disorders.

Methods

Lung and blood specimens, bronchoalveolar lavage fluid cells collected from CTD-IP patients, and human primary lung fibroblasts (HLFs) from patients pathologically diagnosed with usual interstitial pneumonia (UIP) and healthy controls were analyzed by histology, flow cytometry and molecular biology. T cell subsets involved in the process of CTD-IP were defined, while the regulatory functions of MSCs isolated from the bone marrow of normal individuals (HBMSCs) on cytotoxic T cells and CTD-UIP HLFs were investigated in vitro.

Results

Higher frequencies of cytotoxic T cells were observed in the lung and peripheral blood of CTD-IP patients, accompanied with a reduced regulatory T cell (Treg) level. CTD-UIP HLFs secreted proinflammatory cytokines in combination with upregulation of α-smooth muscle actin (α-SMA). The addition of HBMSCs in vitro increased Tregs concomitant with reduced cytotoxic T cells in an experimental cell model with dominant cytotoxic T cells, and promoted Tregs expansion in T cell subsets from patients with idiopathic pulmonary fibrosis (IPF). HBMSCs also significantly decreased proinflammatory chemokine/cytokine expression, and blocked α-SMA activation in CTD-UIP HLFs through a TGF-β1-mediated mechanism, which modulates excessive IL-6/STAT3 signaling leading to IP-10 expression. MSCs secreting a higher level of TGF-β1 appear to have an optimal anti-fibrotic efficacy in BLM-induced pulmonary fibrosis in mice.

Conclusions

Impairment of TGF-β signal transduction relevant to a persistent IL-6/STAT3 transcriptional activation contributes to reduction of Treg differentiation in CTD-IP and to myofibroblast differentiation in CTD-UIP HLFs. HBMSCs can sensitize TGF-β1 downstream signal transduction that regulates IL-6/STAT3 activation, thereby stimulating Treg expansion and facilitating anti-fibrotic IP-10 production. This may in turn block progression of lung fibrosis in autoimmunity.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0319-y) contains supplementary material, which is available to authorized users.

Commentary: IL-4 and IL-13 receptors and signaling

Interleukin (IL)-4 and IL-13 were discovered approximately 30years ago and were immediately linked to allergy and atopic diseases. Since then, new roles for IL-4 and IL-13 and their receptors in normal gestation, fetal development and neurological function and in the pathogenesis of cancer and fibrosis have been appreciated. Studying IL-4/-13 and their receptors has revealed important clues about cytokine biology and led to the development of numerous experimental therapeutics. Here we aim to highlight new discoveries and consolidate concepts in the field of IL-4 and IL-13 structure, receptor regulation, signaling and experimental therapeutics.

T cells and costimulation in cancer

Optimal T cell response is dependent not only on T cell receptor activation, but also on additional signaling from coreceptors. The main coreceptors include B7 and tumor necrosis factor family members. They exert costimulatory or coinhibitory effects, and their balance determines the fate of T cell response. In normal conditions, costimulators facilitate the development of protective immune response, whereas coinhibitors dampen inflammation to avoid organ/tissue damage from excessive immune reaction. In the tumor microenvironment, the balance is garbled: inhibitory pathways predominate, and T cell response is impaired. The importance of cosignaling in the tumor immune response has been experimentally and clinically demonstrated. New therapeutic strategies targeting T cell cosignaling, especially coinhibitory molecules, are under active experimental and clinical investigation. This review summarizes the functions of main T cell cosignaling axes and discusses their clinical application.

Cytokines and growth factors promote airway smooth muscle cell proliferation

Chronic airway diseases, such as asthma or chronic obstructive pulmonary disease, are characterized by the presence in the airways of inflammation factors, growth factors and cytokines, which promote airway wall remodelling. The aim of this study was to investigate the effect of cytokines and growth factors on airway smooth muscle cell (ASMC) proliferation, phenotype and responsiveness. Incubation of serum starved human bronchial ASMCs with TNF- α , TGF, bFGF, and PDGF, but not IL-1 β , increased methyl-[(3)H]thymidine incorporation and cell number, mediated by the PI3K and MAPK signalling pathways. Regarding rabbit tracheal ASMC proliferation, TNF- α , IL-1 β , TGF, and PDGF increased methyl-[(3)H]thymidine incorporation in a PI3K- and MAPK-dependent manner. bFGF increased both methyl-[(3)H]thymidine incorporation and cell number. Moreover, incubation with TGF, bFGF and PDGF appears to drive human ASMCs towards a synthetic phenotype, as shown by the reduction of the percentage of cells expressing SM- α actin. In addition, the responsiveness of epithelium-denuded rabbit tracheal strips to carbachol was not significantly altered after 3-day treatment with bFGF. In conclusion, all the tested cytokines and growth factors increased ASMC proliferation to a different degree, depending on the specific cell type, with bronchial ASMCs being more prone to proliferation than tracheal ASMCs.

Cytokine loaded biopolymers as a novel strategy to study stem cells during wound-healing processes

The biopolymer matrigel loaded with cytokine can be used for the recruitment in vivo of specific cell populations and as a vector for the preparation of cell cultures. Data demonstrate that the injection of the matrigel biopolymer supplemented with interleukin-8 (IL-8) in the leech Hirudo medicinalis can be used to purify cell populations showing the same morphofunctional and molecular mechanisms of specific populations of vertebrate hematopoietic precursor cells involved in tissue repair. These cells spontaneously differentiated into myofibroblasts. This approach highlights how the innovative use of a cytokine-loaded biopolymer for an in vivo cell sorting method, applied to a simple invertebrate model, can be a tool for studying myofibroblast cell biology and its regulation, step by step.

Effects of low molecular weight fungal compounds on inflammatory gene transcription and expression in mouse alveolar macrophages

The inflammatory potential and molecular mechanisms underscoring inflammatory responses of lung cells to compounds from fungi that grow on damp building materials is poorly understood in vitro. In this study we evaluated the effect of pure fungal compounds on potentiating acute inflammatory response in primary mouse alveolar macrophages (AMs) and tested the hypothesis that AM responses to low molecular weight fungal compounds exhibit temporal and compound specificity that mimic that observed in the whole lung. Transcriptional responses of 13 inflammation/respiratory burst-associated genes (KC=Cxcl1, Cxcl2, Cxcl5, Cxcl10, Ccl3, Ccl112, Ccl20, IL-1β, Il-6, ifi27 Tnfα, iNOS and Blvrb) were evaluated in mouse AMs exposed to a 1ml (10(-8)mol) dose of either pure atranone C, brevianimide, cladosporin, curdlan, LPS, neoechinulin A & B, sterigmatocystin or TMC-120A for 2h, 4h and 12h PE using customized reverse transcription (RT)-PCR based arrays. Multianalyte ELISA was used to measure expression of 6 pro-inflammatory cytokines common to the transcriptional assays (Cxcl1, Cxcl10, Ccl3, IL1β, Ifn-λ and Tnf-α) to determine whether gene expression corresponded to the transcription data. Compared to controls, all of these compounds induced significant (≥2.5-fold or ≤-2.5-fold change at p≤0.05) time- and compound-specific transcriptional gene alterations in treatment AMs. The highest number of transcribed genes were in LPS treatment AMs at 12h PE (12/13) followed by neoechinulin B at 4h PE (11/13). Highest fold change values (>30) were associated with KC, Cxcl2, Cxcl5 and IL1β genes in cells exposed to LPS. Compound exposures also induced significant (p≤0.05) time- and compound-specific pro-inflammatory responses manifest as differentially elevated Cxcl1, Cxcl10, Ccl3, Ifn-λ and Tnf-α concentrations in culture supernatant of treatment AMs. Dissimilarity in transcriptional responses in AMs and our in vivo model of lung disease is likely attributable to whole lung vs. isolated cell responsive and dose differences between the two studies. The results not only indicate that low molecular weight compounds from fungi that grow in damp built environments are potently pro-inflammatory in vitro, it further highlights the important role AMs play in innate lung defence, and against exposure to low molecular weight fungal compounds. These observations further support our position that exposure to low molecular weight compounds from indoor-associated fungi may provoke some of the inflammatory health effects reported from humans in damp building environments. They also open up a hypothesis building process that could explain the rise of non-atopic asthma associated with fungi.

Inflammation-associated gene transcription and expression in mouse lungs induced by low molecular weight compounds from fungi from the built environment

Few metabolites from fungi found indoors have been tested for inflammatory mediators endpoints in primary cultures of alveolar macrophages or in vivo. In this study, mice were intratracheally instilled with a single dose comprising 4x10(-5)moletoxin/kg lung wt dose of either atranone C, brevianamide, cladosporin, mycophenolic acid, neoechinulin A & B, sterigmatocystin or TMC-120A. These toxins are from fungi common on damp building materials. The dose used was comparable to the estimated doses of possible human exposure. Hematoxylin and eosin (H&E) histology and Alcian Blue/Periodic Acid Schiff (AB/PAS) histochemistry were used to evaluate lungs for time course (4h and 12h post-exposure (PE)) inflammatory and toxic changes. Reverse-transcription (RT)-PCR based arrays were also employed to evaluate time course inflammation-associated gene transcription in lung tissues of the different toxins. Immunohistochemistry (IHC) was used to probe MIP-2 and Tnf-alpha protein expression in treatment lungs to determine whether responses correspond with gene transcription data. Both histology and histochemistry revealed that toxin exposed lungs at 12h PE showed evidence of inflammation. H&E revealed that bronchioli were lined with irregularly thickened and sometimes sloughing epithelium and bronchiolar spaces supported infiltration of leukocytes, cellular and mucus-like debris while alveolar spaces supported swollen macrophages and modest amorphous debris accumulations. All toxin-instilled lungs exhibited copious mucus production and alveolar macrophages with red stained cytoplasm on bronchiolar surfaces, especially at 12h PE. Array analysis of 83 inflammation-associated genes extracted from lung tissue demonstrated a number of patterns, compared to controls. 82 genes assayed at 4h PE and 75 genes at 12h PE were significantly altered (p< or =0.05; >or =1.5-fold or < or =-1.5-fold change) in the different treatment animal groups. Expression of transcriptionally regulated genes was confirmed using immunohistochemistry that demonstrated MIP-2 and Tnf-alpha staining in respiratory bronchiolar epithelia, alveolar macrophages and alveolar type II cells. The transcriptional regulation in these genes in the treatment groups suggests that they may serve central roles in the immunomodulation of toxin-induced pro-inflammatory lung responses. Hierarchical cluster analysis revealed significant patterns of gene transcription linking the response of the toxins at equimolar doses in three groups: (1) brevianamide, mycophenolic acid and neoechinulin B, (2) neoechinulin A and sterigmatocystin, and (3) cladosporin, atranone C and TMC-120. The results further confirm the inflammatory nature of metabolites/toxins from such fungi can contribute to the development of non-allergenic respiratory health effects.

Vitamin D derivatives: calcitriol and tacalcitol inhibits interleukin-6 and interleukin-8 expression in human nasal polyp fibroblast cultures

PURPOSE

Biologically active vitamin D3 (VD) derivatives possess modulatory activities on immunological and inflammatory responses which can be reflected by altered levels of pro-inflammatory chemokines. Nasal polyposis (NP), defined as a chronic inflammatory process of upper respiratory system, could be influenced by VD derivatives. The purpose of this study was to investigate the influence of 1alpha,25-dihydroxyvitamin D3 (calcitriol) and 1alpha,24(R)-dihydroxyvitamin D3 (tacalcitol) on the secretion of IL-6 and IL-8 by fibroblasts derived from NP.

MATERIAL AND METHODS

The study involved 12 fibroblast cultures derived from NP samples obtained from surgically treated patients. Measurements were performed on the polyp cells after the 6-9 passages. Culture stimulation involved treatment with tacalcitol and calcitriol at a defined strength (from 10(-7)M to 10(-4)M). IL-6 and IL-8 concentrations were estimated with ELISA.

RESULTS

Treatment with calcitriol or tacalcitol inhibits the synthesis of both IL-6 and IL-8 compared to the control group. The dose dependence of this effect has been confirmed. VD derivatives influence was marked at higher concentrations. Significant interleukin decrease was observed at 10(-5) and 10(-4) for calcitriol and 10-4 in the case of tacalcitol.

CONCLUSIONS

The present study demonstrates that calcitriol and tacalcitol are capable of affecting pro-inflammatory cytokine (IL-6 and IL-8) levels in NP cultures. Our data imply a potential therapeutical application of topical VD derivates in NP and warrant further investigation.

Interleukin-13 acts as an apoptotic effector on lung epithelial cells and induces pro-fibrotic gene expression in lung fibroblasts

BACKGROUND

IL-13 promotes acute allergic asthma and is discussed to play a role in late asthmatic features such as fibrotic processes and airway remodelling. The contributions of IL-13-mediated mechanisms to subepithelial events related to fibrosis are not yet settled.

OBJECTIVE

We investigated the impact of IL-13 on lung epithelial cells as apoptotic effector and on lung fibroblasts as inducer of pro-fibrotic gene expression.

METHODS

Using the two lung epithelial cell lines A549 and BEAS-2B as well as primary lung epithelial cells, we investigated the capability of IL-13 to induce apoptosis by both flow-cytometry and ELISA. The ability of IL-13 to increase the expression of pro-fibrotic genes and to exert influence on the expression of its own receptor was investigated by real-time quantitative PCR measurement of mRNAs encoding collagen I, collagen III, basic fibroblast growth factor (bFGF), alpha-smooth muscle actin (alpha-SMA) and the IL-13 receptor alpha1 (IL-13Ralpha1) chain in human primary lung fibroblasts. The specificity of IL-13-mediated cellular responses was confirmed by means of an inhibitory monoclonal antibody directed to the IL-13 receptor.

RESULTS

IL-13 induces apoptosis in lung epithelial cell lines as well as in primary lung epithelial cells. Furthermore, IL-13 increases the expression of mRNA for alpha-SMA and collagen III, but not for bFGF in human primary lung fibroblasts. The susceptibility of lung fibroblasts to IL-13-induced up-regulation of pro-fibrotic genes is associated with the regulation of IL-13 receptor expression. IL-13-dependent fibrosis-associated effects could be inhibited by antibody-mediated blockade of the IL-13Ralpha1 subunit.

CONCLUSION

Our findings indicate a function of IL-13 as a mediator in fibrotic processes leading to loss of functional airway tissue in asthma. They also highlight the therapeutic potential of specifically targeting the interaction between IL-13 and its receptor.

Unique functions of the type II interleukin 4 receptor identified in mice lacking the interleukin 13 receptor alpha1 chain

The interleukin 4 receptor (IL-4R) is a central mediator of T helper type 2 (T(H)2)-mediated disease and associates with either the common gamma-chain to form the type I IL-4R or with the IL-13R alpha1 chain (IL-13Ralpha1) to form the type II IL-4R. Here we used Il13ra1-/- mice to characterize the distinct functions of type I and type II IL-4 receptors in vivo. In contrast to Il4ra-/- mice, which have weak T(H)2 responses, Il13ra1-/- mice had exacerbated T(H)2 responses. Il13ra1-/- mice showed much less mortality after infection with Schistosoma mansoni and much more susceptibility to Nippostrongylus brasiliensis. IL-13Ralpha1 was essential for allergen-induced airway hyperreactivity and mucus hypersecretion but not for fibroblast or alternative macrophage activation. Thus, type I and II IL-4 receptors exert distinct effects on immune responses.

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

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

The TRAF6, but not the TRAF2/3, binding domain of CD40 is required for cytokine production in human lung fibroblasts

Fibroblasts are key effector cells in inciting inflammation, wound healing, and scarring. CD40, a member of the TNF receptor superfamily, mediates intercellular communication between fibroblasts and cells that express CD154 (CD40L), including T lymphocytes and platelets. To better understand the mechanisms by which CD40 regulates fibroblast function in inflammation and scarring, we examined the ability of CD40 cytoplasmic tail regions (CD40ct) containing the TRAF6 or the TRAF2/3 binding domains to regulate cytokine and chemokine expression by primary human lung fibroblasts. The full-length human CD40ct, the first 35 amino acids of the CD40ct encompassing the TRAF6 binding site (1-35), and amino acids 35-53 containing the TRAF2/TRAF3 binding domain were expressed in human lung fibroblasts as fusion proteins with the extracellular domain of human CD8alpha by retroviral transduction. The TRAF6, but not the TRAF2/3, binding domain was found to regulate IL-8 and IL-6 production, and induce activation of NF-kappaB and Jun kinase in lung fibroblasts, demonstrating for the first time that CD40ct domains can function independently to regulate pro-inflammatory responses of primary human fibroblasts. Thus, targeting TRAF6 function through pharmacological intervention may represent a viable strategy for modulating localized inflammation.

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

Background

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

Methods

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

Results

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

Conclusion

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

Human pulmonary fibroblasts exhibit altered interleukin-4 and interleukin-13 receptor subunit expression in idiopathic interstitial pneumonia

Abnormal proliferation of pulmonary fibroblasts is a prominent feature of chronic pulmonary fibrotic diseases such as idiopathic interstitial pneumonia (IIP), but it is not presently clear how this proliferative response by lung fibroblasts can be therapeutically modulated. In the present study, we examined whether it was possible to selectively target primary human pulmonary fibroblasts grown out of surgical lung biopsies (SLBs) from IIP patients based on their expression of interleukin-4 receptor (IL-4R) and IL-13R subunits. Pulmonary fibroblast lines cultured from patients with the severest form of IIP, namely usual interstitial pneumonia, exhibited the greatest gene and protein expression of IL-4Ralpha, IL-13Ralpha1, and IL-13Ralpha2 compared with primary pulmonary fibroblast lines grown from other IIP SLBs and normal SLBs. When exposed to increasing concentrations of a chimeric protein comprised of human IL-13 and a truncated version of Pseudomonas exotoxin (IL13-PE), the proliferation of primary usual interstitial pneumonia fibroblasts was inhibited to a much greater extent compared with fibroblast lines from nonspecific interstitial pneumonia and respiratory bronchiolitis/interstitial lung disease patient groups. Fibroblasts from normal patients exhibited minimal susceptibility to the cytotoxic effect of IL13-PE. IL13-PE-mediated targeting of IIP fibroblasts was dependent on their expression of IL-4Ralpha and IL-13Ralpha2. Thus, these data suggest that the abnormal proliferative properties of human lung fibroblasts from certain IIP patient groups can be modulated in a manner that is dependent on the IL-4 and IL-13 receptor subunit expression by these cells.

Up-regulation of interleukin-13 receptor alpha1 on human keratinocytes in the skin of psoriasis and atopic dermatitis

BACKGROUND

Interleukin (IL)-13 is a pleiotropic cytokine, which shares many biological functions with IL-4. The receptor subunits of IL-13 consist of IL-4Ralpha, IL-13Ralpha1 and IL-13Ralpha2. The regulatory mechanisms of the IL-13Ralpha expression in the keratinocytes of certain skin disease have not been known.

OBJECTIVE

To clear the roles of IL-13 and the regulatory mechanisms of its receptor in atopic dermatitis (AD) and psoriasis.

METHOD

The expression of IL-13Ralpha1 in the skin of AD and psoriasis was investigated by immunohistochemistry. The regulation of IL-13Ralpha mRNA in the skin and human primary keratinocyte (HPK) was investigated by quantitative PCR. The secretion of IL-6 and RANTES from HPK was measured by ELISA.

RESULTS

The expression of IL-13Ralpha1 was more prominent on the suprabasal keratinocytes in the skin of AD and striking increase of staining was observed on all layers of keratinocyte in the skin of psoriasis. The mRNA of IL-13Ralpha1, but not of IL-13Ralpha2 was overexpressed in both skin of AD and psoriasis. In vitro experiment using HPK demonstrated that IFN-gamma, IL-13 but not IL-4 could up-regulate the mRNA expression of IL-13Ralpha1. In contrast, IL-13Ralpha2 mRNA expression was up-regulated by IFN-gamma plus IL-4. Furthermore, the stimulation of HPK with IFN-gamma plus IL-13 and/or IL-4 resulted in significant enhancement of IL-6 and RANTES secretion.

CONCLUSION

These findings indicate that IL-4 and IL-13 have different regulatory effects on the expression of IL-13Ralpha1 and alpha2, and the overexpression of IL-13Ralpha1 may play some roles in the pathogenesis of chronic stage of AD or psoriasis.

Tyrosine kinase inhibitors: a new approach for asthma

The pathogenesis of allergic asthma involves the interplay of inflammatory cells and airway-resident cells, and of their secreted mediators including cytokines, chemokines, growth factors and inflammatory mediators. Receptor tyrosine kinases are important for the pathogenesis of airway remodeling. Activation of epidermal growth factor (EGF) receptor kinase and platelet-derived growth factor (PDGF) receptor kinase leads to hyperplasia of airway smooth muscle cells, epithelial cells and goblet cells. Stimulation of non-receptor tyrosine kinases (e.g. Lyn, Lck, Syk, ZAP-70, Fyn, Btk, Itk) is the earliest detectable signaling response upon antigen-induced immunoreceptor activation in inflammatory cells. Cytokine receptor dimerization upon ligand stimulation induces activation of Janus tyrosine kinases (JAKs), leading to recruitment and phosphorylation of signal transducer and activator of transcription (STAT) for selective gene expression regulation. Activation of chemokine receptors can trigger JAK-STAT pathway, Lck, Fyn, Lyn, Fgr, and Syk/Zap-70 to induce chemotaxis of inflammatory cells. Inhibitors of tyrosine kinases have been shown in vitro to block growth factor-induced hyperplasia of airway-resident cells; antigen-induced inflammatory cell activation and cytokine synthesis; cytokine-mediated pro-inflammatory gene expression in inflammatory and airway cells; and chemokine-induced chemotaxis of inflammatory cells. Recently, anti-inflammatory effects of tyrosine kinase inhibitors (e.g. genistein, tyrphostin AG213, piceatannol, tyrphostin AG490, WHI-P97, WHI-P131, Syk antisense) in animal models of allergic asthma have been reported. Therefore, development of inhibitors of tyrosine kinases can be a very attractive strategy for the treatment of asthma.

Mechanisms of inflammation-mediated airway smooth muscle plasticity and airways remodeling in asthma

Recent evidence points to progressive structural change in the airway wall, driven by chronic local inflammation, as a fundamental component for development of irreversible airway hyperresponsiveness. Acute and chronic inflammation is orchestrated by cytokines from recruited inflammatory cells, airway myofibroblasts and myocytes. Airway myocytes exhibit functional plasticity in their capacity for contraction, proliferation, and synthesis of matrix protein and cytokines. This confers a principal role in driving different components of the airway remodeling process, and mediating constrictor hyperresponsiveness. Functional plasticity of airway smooth muscle (ASM) is regulated by an array of environmental cues, including cytokines, which mediate their effects through receptors and a number of intracellular signaling pathways. Despite numerous studies of the cellular effects of cytokines on cultured airway myocytes, few have identified how intracellular signaling pathways modulate or induce these cellular responses. This review summarizes current understanding of these concepts and presents a model for the effects of inflammatory mediators on functional plasticity of ASM in asthma.