Dysregulated cross-talk between alveolar epithelial cells and stromal cells in idiopathic pulmonary fibrosis reduces epithelial regenerative capacity.

In idiopathic pulmonary fibrosis (IPF) constant epithelial micro-injury and aberrant interactions within the stromal micro-environment lead to abnormal alveolar repair and fibrosis. We hypothesized that alveolar epithelial regenerative responses in IPF are impaired due to disturbed crosstalk between epithelial cells and their stromal niche. We established organoid cultures from unfractionated suspensions and isolated EpCAM+ cells from distal lung tissue of patients with and without IPF. We observed significantly more organoids being formed from unfractionated suspensions compared to isolated EpCAM+ cell cultures, indicating the presence of supportive cells in the unfractionated suspensions. Importantly, lower organoid numbers were observed in unfractionated cultures from IPF lungs compared to non-IPF lungs. This difference was not found when comparing organoid formation from isolated EpCAM+ cells alone between IPF and non-IPF groups, suggesting that crosstalk between the supportive population and epithelial cells is impaired in lungs from IPF patients. Additionally, organoids grown from IPF lung-derived cells were larger in size compared to those from non-IPF lungs in both unfractionated and EpCAM+ cultures, indicating an intrinsic abnormality in epithelial progenitors from IPF lungs. Together, our observations suggest that dysregulated crosstalk between alveolar progenitor cells and the stromal niche affects the regenerative capacity, potentially contributing to alveolar impairment in IPF.

Paracrine Regulation of Alveolar Epithelial Damage and Repair Responses by Human Lung-Resident Mesenchymal Stromal Cells.

COPD is characterized by irreversible lung tissue damage. We hypothesized that lung-derived mesenchymal stromal cells (LMSCs) reduce alveolar epithelial damage via paracrine processes, and may thus be suitable for cell-based strategies in COPD. We aimed to assess whether COPD-derived LMSCs display abnormalities. LMSCs were isolated from lung tissue of severe COPD patients and non-COPD controls. Effects of LMSC conditioned-medium (CM) on H2O2-induced, electric field- and scratch-injury were studied in A549 and NCI-H441 epithelial cells. In organoid models, LMSCs were co-cultured with NCI-H441 or primary lung cells. Organoid number, size and expression of alveolar type II markers were assessed. Pre-treatment with LMSC-CM significantly attenuated oxidative stress-induced necrosis and accelerated wound repair in A549. Co-culture with LMSCs supported organoid formation in NCI-H441 and primary epithelial cells, resulting in significantly larger organoids with lower type II-marker positivity in the presence of COPD-derived versus control LMSCs. Similar abnormalities developed in organoids from COPD compared to control-derived lung cells, with significantly larger organoids. Collectively, this indicates that LMSCs' secretome attenuates alveolar epithelial injury and supports epithelial repair. Additionally, LMSCs promote generation of alveolar organoids, with abnormalities in the supportive effects of COPD-derived LMCS, reflective of impaired regenerative responses of COPD distal lung cells.

A Protective Role of FAM13A in Human Airway Epithelial Cells Upon Exposure to Cigarette Smoke Extract.

BACKGROUND: Chronic Obstructive Pulmonary Disease (COPD) is a progressive lung disease characterized by chronic inflammation upon inhalation of noxious particles, e.g., cigarette smoke. FAM13A is one of the genes often found to be associated with COPD, however its function in the pathophysiology of COPD is incompletely understood. We studied its role in airway epithelial barrier integrity and cigarette smoke-induced epithelial responses. MATERIALS AND METHODS: Protein level and localization of FAM13A was assessed with immunohistochemistry in lung tissue from COPD patients and non-COPD controls. In vitro, FAM13A expression was determined in the absence or presence of cigarette smoke extract (CSE) in primary airway epithelial cells (AECs) from COPD patients and controls by western blotting. FAM13A was overexpressed in cell line 16HBE14o- and its effect on barrier function was monitored real-time by electrical resistance. Expression of junctional protein E-cadherin and ß-catenin was assessed by western blotting. The secretion of neutrophil attractant CXCL8 upon CSE exposure was measured by ELISA. RESULTS: FAM13A was strongly expressed in airway epithelium, but significantly weaker in airways of COPD patients compared to non-COPD controls. In COPD-derived AECs, but not those of controls, FAM13A was significantly downregulated by CSE. 16HBE14o- cells overexpressing FAM13A built up epithelial resistance significantly more rapidly, which was accompanied by higher E-cadherin expression and reduced CSE-induced CXCL8 levels. CONCLUSION: Our data indicate that the expression of FAM13A is lower in airway epithelium of COPD patients compared to non-COPD controls. In addition, cigarette smoking selectively downregulates airway epithelial expression of FAM13A in COPD patients. This may have important consequences for the pathophysiology of COPD, as the more rapid build-up of epithelial resistance upon FAM13A overexpression suggests improved (re)constitution of barrier function. The reduced epithelial secretion of CXCL8 upon CSE-induced damage suggests that lower FAM13A expression upon cigarette smoking may facilitate epithelial-driven neutrophilia.

Retinoic acid signaling balances adult distal lung epithelial progenitor cell growth and differentiation.

BACKGROUND: Despite compelling data describing pro-regenerative effects of all-trans retinoic acid (ATRA) in pre-clinical models of chronic obstructive pulmonary disease (COPD), clinical trials using retinoids for emphysema patients have failed. Crucial information about the specific role of RA signaling in adult rodent and human lung epithelial progenitor cells is largely missing. METHODS: Adult lung organoid cultures were generated from isolated primary mouse and human lung epithelial cells, and incubated with pharmacological pathway modulators and recombinant proteins. Organoid number and size were measured, and differentiation was assessed with quantitative immunofluorescence and gene expression analyses. FINDINGS: We unexpectedly found that ATRA decreased lung organoid size, whereas RA pathway inhibition increased mouse and human lung organoid size. RA pathway inhibition stimulated mouse lung epithelial proliferation via YAP pathway activation and epithelial-mesenchymal FGF signaling, while concomitantly suppressing alveolar and airway differentiation. HDAC inhibition rescued differentiation in growth-augmented lung organoids. INTERPRETATION: In contrast to prevailing notions, our study suggests that regenerative pharmacology using transient RA pathway inhibition followed by HDAC inhibition might hold promise to promote lung epithelial regeneration in diseased adult lung tissue. FUND: This project is funded by the Lung Foundation Netherlands (Longfonds) grant 6.1.14.009 (RG, MK, JS, PSH) and W2/W3 Professorship Award by the Helmholtz Association, Berlin, Germany (MK).

SIRT1/FoxO3 axis alteration leads to aberrant immune responses in bronchial epithelial cells.

Inflammation and ageing are intertwined in chronic obstructive pulmonary disease (COPD). The histone deacetylase SIRT1 and the related activation of FoxO3 protect from ageing and regulate inflammation. The role of SIRT1/FoxO3 in COPD is largely unknown. This study evaluated whether cigarette smoke, by modulating the SIRT1/FoxO3 axis, affects airway epithelial pro-inflammatory responses. Human bronchial epithelial cells (16HBE) and primary bronchial epithelial cells (PBECs) from COPD patients and controls were treated with/without cigarette smoke extract (CSE), Sirtinol or FoxO3 siRNA. SIRT1, FoxO3 and NF-κB nuclear accumulation, SIRT1 deacetylase activity, IL-8 and CCL20 expression/release and the release of 12 cytokines, neutrophil and lymphocyte chemotaxis were assessed. In PBECs, the constitutive FoxO3 expression was lower in patients with COPD than in controls. Furthermore, CSE reduced FoxO3 expression only in PBECs from controls. In 16HBE, CSE decreased SIRT1 activity and nuclear expression, enhanced NF-κB binding to the IL-8 gene promoter thus increasing IL-8 expression, decreased CCL20 expression, increased the neutrophil chemotaxis and decreased lymphocyte chemotaxis. Similarly, SIRT1 inhibition reduced FoxO3 expression and increased nuclear NF-κB. FoxO3 siRNA treatment increased IL-8 and decreased CCL20 expression in 16HBE. In conclusion, CSE impairs the function of SIRT1/FoxO3 axis in bronchial epithelium, dysregulating NF-κB activity and inducing pro-inflammatory responses.

miR-146a-5p plays an essential role in the aberrant epithelial-fibroblast cross-talk in COPD.

We previously reported that epithelial-derived interleukin (IL)-1α drives fibroblast-derived inflammation in the lung epithelial-mesenchymal trophic unit. Since miR-146a-5p has been shown to negatively regulate IL-1 signalling, we investigated the role of miR-146a-5p in the regulation of IL-1α-driven inflammation in chronic obstructive pulmonary disease (COPD).Human bronchial epithelial (16HBE14o-) cells were co-cultured with control and COPD-derived primary human lung fibroblasts (PHLFs), and miR-146a-5p expression was assessed with and without IL-1α neutralising antibody. Genomic DNA was assessed for the presence of the single nucleotide polymorphism (SNP) rs2910164. miR-146a-5p mimics were used for overexpression studies to assess IL-1α-induced signalling and IL-8 production by PHLFs.Co-culture of PHLFs with airway epithelial cells significantly increased the expression of miR-146a-5p and this induction was dependent on epithelial-derived IL-1α. miR-146a-5p overexpression decreased IL-1α-induced IL-8 secretion in PHLFs via downregulation of IL-1 receptor-associated kinase-1. In COPD PHLFs, the induction of miR-146a-5p was significantly less compared with controls and was associated with the SNP rs2910164 (GG allele) in the miR-146a-5p gene.Our results suggest that induction of miR-146a-5p is involved in epithelial-fibroblast communication in the lungs and negatively regulates epithelial-derived IL-1α induction of IL-8 by fibroblasts. The decreased levels of miR-146a-5p in COPD fibroblasts may induce a more pro-inflammatory phenotype, contributing to chronic inflammation in COPD.

Protocadherin-1 Localization and Cell-Adhesion Function in Airway Epithelial Cells in Asthma.

BACKGROUND: The asthma gene PCDH1 encodes Protocadherin-1, a putative adhesion molecule of unknown function expressed in the airway epithelium. Here, we characterize the localization, differential expression, homotypic adhesion specificity and function of PCDH1 in airway epithelial cells in asthma. METHODS: We performed confocal fluorescence microscopy to determine subcellular localization of PCDH1 in 16HBE cells and primary bronchial epithelial cells (PBECs) grown at air-liquid interface. Next, to compare PCDH1 expression and localization in asthma and controls we performed qRT-PCR and fluorescence microscopy in PBECs and immunohistochemistry on airway wall biopsies. We examined homotypic adhesion specificity of HEK293T clones overexpressing fluorescently tagged-PCDH1 isoforms. Finally, to evaluate the role for PCDH1 in epithelial barrier formation and repair, we performed siRNA knockdown-studies and measured epithelial resistance. RESULTS: PCDH1 localized to the cell membrane at cell-cell contact sites, baso-lateral to adherens junctions, with increasing expression during epithelial differentiation. No differences in gene expression or localization of PCDH1 isoforms expressing the extracellular domain were observed in either PBECs or airway wall biopsies between asthma patients and controls. Overexpression of PCDH1 mediated homotypic interaction, whereas downregulation of PCDH1 reduced epithelial barrier formation, and impaired repair after wounding. CONCLUSIONS: In conclusion, PCDH1 is localized to the cell membrane of bronchial epithelial cells baso-lateral to the adherens junction. Expression of PCDH1 is not reduced nor delocalized in asthma even though PCDH1 contributes to homotypic adhesion, epithelial barrier formation and repair.

Interleukin-1α drives the dysfunctional cross-talk of the airway epithelium and lung fibroblasts in COPD.

Chronic obstructive pulmonary disease (COPD) has been associated with aberrant epithelial-mesenchymal interactions resulting in inflammatory and remodelling processes. We developed a co-culture model using COPD and control-derived airway epithelial cells (AECs) and lung fibroblasts to understand the mediators that are involved in remodelling and inflammation in COPD.AECs and fibroblasts obtained from COPD and control lung tissue were grown in co-culture with fetal lung fibroblast or human bronchial epithelial cell lines. mRNA and protein expression of inflammatory mediators, pro-fibrotic molecules and extracellular matrix (ECM) proteins were assessed.Co-culture resulted in the release of pro-inflammatory mediators interleukin (IL)-8/CXCL8 and heat shock protein (Hsp70) from lung fibroblasts, and decreased expression of ECM molecules (e.g. collagen, decorin) that was not different between control and COPD-derived primary cells. This pro-inflammatory effect was mediated by epithelial-derived IL-1α and increased upon epithelial exposure to cigarette smoke extract (CSE). When exposed to CSE, COPD-derived AECs elicited a stronger IL-1α response compared with control-derived airway epithelium and this corresponded with a significantly enhanced IL-8 release from lung fibroblasts.We demonstrate that, through IL-1α production, AECs induce a pro-inflammatory lung fibroblast phenotype that is further enhanced with CSE exposure in COPD, suggesting an aberrant epithelial-fibroblast interaction in COPD.

Cigarette smoke-induced epithelial expression of WNT-5B: implications for COPD.

Wingless/integrase-1 (WNT) signalling is associated with lung inflammation and repair, but its role in chronic obstructive pulmonary disease (COPD) pathogenesis is unclear. We investigated whether cigarette smoke-induced dysregulation of WNT-5B contributes to airway remodelling in COPD.We analysed WNT-5B protein expression in the lung tissue of COPD patients and (non)smoking controls, and investigated the effects of cigarette smoke exposure on WNT-5B expression in COPD and control-derived primary bronchial epithelial cells (PBECs). Additionally, we studied downstream effects of WNT-5B on remodelling related genes fibronectin, matrix metalloproteinase (MMP)-2, MMP-9 and SnaiI in BEAS-2B and air-liquid interface (ALI)-cultured PBECs.We observed that airway epithelial WNT-5B expression is significantly higher in lung tissue from COPD patients than controls. Cigarette smoke extract significantly increased mRNA expression of WNT-5B in COPD, but not control-derived PBECs. Exogenously added WNT-5B augmented the expression of remodelling related genes in BEAS-2B cells, which was mediated by transforming growth factor (TGF)-ß/Smad3 signalling. In addition, WNT-5B upregulated the expression of these genes in ALI-cultured PBECs, particularly PBECs from COPD patients.Together, our results provide evidence that exaggerated WNT-5B expression upon cigarette smoke exposure in the bronchial epithelium of COPD patients leads to TGF-ß/Smad3-dependent expression of genes related to airway remodelling.

Differential effects of fluticasone on extracellular matrix production by airway and parenchymal fibroblasts in severe COPD.

Chronic obstructive pulmonary disease (COPD) is characterized by abnormal repair in the lung resulting in airway obstruction associated with emphysema and peripheral airway fibrosis. Because the presence and degree of airways disease and emphysema varies between COPD patients, this may explain the heterogeneity in the response to treatment. It is currently unknown whether and to what extent inhaled steroids can affect the abnormal repair process in the airways and lung parenchyma in COPD. We investigated the effects of fluticasone on transforming growth factor (TGF)-ß- and cigarette smoke-induced changes in mothers against decapentaplegic homolog (Smad) signaling and extracellular matrix (ECM) production in airway and parenchymal lung fibroblasts from patients with severe COPD. We showed that TGF-ß-induced ECM production by pulmonary fibroblasts, but not activation of the Smad pathway, was sensitive to the effects of fluticasone. Fluticasone induced decorin production by airway fibroblasts and partly reversed the negative effects of TGF-ß treatment. Fluticasone inhibited biglycan production in both airway and parenchymal fibroblasts and procollagen 1 production only in parenchymal fibroblasts, thereby restoring the basal difference in procollagen 1 production between airway and parenchymal fibroblasts. Our findings suggest that the effects of steroids on the airway compartment may be beneficial for patients with severe COPD, i.e., restoration of decorin loss around the airways, whereas the effects of steroids on the parenchyma may be detrimental, since the tissue repair response, i.e., biglycan and procollagen production, is inhibited. More research is needed to further disentangle these differential effects of steroid treatment on the different lung compartments and its impact on tissue repair and remodeling in COPD.

Role of aberrant metalloproteinase activity in the pro-inflammatory phenotype of bronchial epithelium in COPD.

BACKGROUND: Cigarette smoke, the major risk factor for COPD, is known to activate matrix metalloproteinases in airway epithelium. We investigated whether metalloproteinases, particularly A Disintegrin and Metalloproteinase (ADAM)17, contribute to increased pro-inflammatory epithelial responses with respect to the release of IL-8 and TGF-α, cytokines implicated in COPD pathogenesis. METHODS: We studied the effects of cigarette smoke extract (CSE) and metalloproteinase inhibitors on TGF-α and IL-8 release in primary bronchial epithelial cells (PBECs) from COPD patients, healthy smokers and non-smokers. RESULTS: We observed that TGF-α was mainly shed by ADAM17 in PBECs from all groups. Interestingly, IL-8 production occurred independently from ADAM17 and TGF-α shedding, but was significantly inhibited by broad-spectrum metalloproteinase inhibitor TAPI-2. CSE did not induce ADAM17-dependent TGF-α shedding, while it slightly augmented the production of IL-8. This was accompanied by reduced endogenous inhibitor of metalloproteinase (TIMP)-3 levels, suggesting that CSE does not directly but rather indirectly alter activity of ADAM17 through the regulation of its endogenous inhibitor. Furthermore, whereas baseline TGF-α shedding was lower in COPD PBECs, the early release of IL-8 (likely due to its shedding) was higher in PBECs from COPD than healthy smokers. Importantly, this was accompanied by lower TIMP-2 levels in COPD PBECs, while baseline TIMP-3 levels were similar between groups. CONCLUSIONS: Our data indicate that IL-8 secretion is regulated independently from ADAM17 activity and TGF-α shedding and that particularly its early release is differentially regulated in PBECs from COPD and healthy smokers. Since TIMP-2-sensitive metalloproteinases could potentially contribute to IL-8 release, these may be interesting targets to further investigate novel therapeutic strategies in COPD.

House dust mite-promoted epithelial-to-mesenchymal transition in human bronchial epithelium.

The molecular basis of airway remodeling and loss of epithelial integrity in asthma is still undefined. We aimed to establish if exposure of human bronchial epithelium (16HBE cells) to asthma-related stimuli can induce epithelial-to-mesenchymal transition (EMT), a key process in tissue repair and remodeling associated with loss of intercellular contacts. We studied the effects of fibrogenic cytokine TGF-beta and protease-containing aeroallergen house dust mite (HDM) on mesenchymal and epithelial markers, cytoskeleton organization, and activation of beta-catenin-driven reporter TopFLASH. TGF-beta alone up-regulated vimentin and fibronectin, modestly down-regulated E-cadherin, but did not affect cytokeratin. HDM alone did not affect these markers, but promoted stress fibers. Importantly, when added to TGF-beta-primed epithelium, HDM induced E-cadherin internalization, enhanced beta-catenin-dependent transcription, and down-regulated cytokeratin. Regarding the underlying mechanisms, the stimuli together induced sustained myosin light chain phosphorylation, which was crucial for E-cadherin internalization and beta-catenin-dependent transcription. Previously, we showed that HDM signals through the epidermal growth factor receptor (EGFR). Accordingly, inhibition of EGFR prevented TGF-beta/HDM-induced mesenchymalization. TGF-beta facilitated uncoupling of EGFR from E-cadherin, its negative regulator, and prolonged EGFR signaling. Thus, we show that HDM promotes EMT in TGF-beta-primed epithelium. Analysis of primary epithelium appears consistent with this phenotypic change. We propose that TGF-beta secretion and dysregulated EGFR signaling may increase epithelial vulnerability to allergens and trigger the induction of EMT, a hitherto unrecognized contributor to airway remodeling in asthma.

Expression of ADAMs ("a disintegrin and metalloprotease") in the human lung.

In view of the associations of "a disintegrin and metalloprotease" (ADAM) with respiratory diseases, we assessed the expression of various ADAMs in human lung tissue. Lung tissue was obtained from nine individuals who underwent surgery for lung cancer or underwent lung transplantation for emphysema. Also, 16HBE 14o- (human bronchial epithelial) and A549 (alveolar type II epithelium-like) cell lines were used. Immunohistochemistry was performed with antibodies recognizing different ADAM domains. The ADAMs were typically distributed over the bronchial epithelium. ADAM8 and ADAM10 were expressed diffusely in all layers of the epithelium. ADAM9, ADAM17, and ADAM19 were predominantly expressed in the apical part of the epithelium, and ADAM33 was predominantly and strongly expressed in basal epithelial cells. In smooth muscle, ADAM19 and ADAM17 were strongly expressed, as was ADAM33, though this expression was weaker. ADAM33 was strongly expressed in vascular endothelium. All ADAMs were generally expressed in inflammatory cells. The typical distribution of ADAMs in the lung, especially in the epithelium, is interesting and suggests a localized function. As most ADAMs are involved in release of (pro-) inflammatory mediators and growth factors, they may play an important role in the first line of defense and in initiation of repair events in the airways.

Smad gene expression in pulmonary fibroblasts: indications for defective ECM repair in COPD.

BACKGROUND: Chronic Obstructive Pulmonary Disease (COPD) is characterized by defective extracellular matrix (ECM) turnover as a result of prolonged cigarette smoking. Fibroblasts have a central role in ECM turnover. The TGFbeta induced Smad pathway provides intracellular signals to regulate ECM production. We address the following hypothesis: fibroblasts have abnormal expression of genes in the Smad pathway in COPD, resulting in abnormal proteoglycan modulation, the ground substance of ECM. METHODS: We compared gene expression of the Smad pathway at different time points after stimulation with TGFbeta, TNF or cigarette smoke extract (CSE) in pulmonary fibroblasts of GOLD stage II and IV COPD patients, and controls. RESULTS: Without stimulation, all genes were similarly expressed in control and COPD fibroblasts. TGFbeta stimulation: downregulation of Smad3 and upregulation of Smad7 occurred in COPD and control fibroblasts, indicating a negative feedback loop upon TGFbeta stimulation. CSE hardly influenced gene expression of the TGFbeta-Smad pathway in control fibroblasts, whereas it reduced Smad3 and enhanced Smad7 gene expression in COPD fibroblasts. Furthermore, decorin gene expression decreased by all stimulations in COPD but not in control fibroblasts. CONCLUSION: Fibroblasts of COPD patients and controls differ in their regulation of the Smad pathway, the contrast being most pronounced under CSE exposure. This aberrant responsiveness of COPD fibroblasts to CSE might result in an impaired tissue repair capability and is likely important with regard to the question why only a subset of smokers demonstrates an excess ECM destruction under influence of cigarette smoking.

Interaction of airway epithelial cells (A549) with spores and mycelium of Aspergillus fumigatus.

OBJECTIVE: To study the interaction of airway epithelial cell line A549 with fragments of mycelium, spores of Aspergillus fumigatus in vitro and to determine if toll-like receptors (TLRs) are involved in the process. METHODS: A549 cells were exposed to fragments of A. fumigatus mycelium, zymosan and inactivated A. fumigatus spores. Interleukin 6 (IL-6) and IL-8 released by A549 cells to the culture supernatant were measured by ELISA. Presence of TLR2 and TLR4 on A549 cells were studied by immuno-histochemistry. RESULTS: Mycelium fragments of A. fumigatus showed strong binding to epithelial cells but had limited effects on the release of IL-6 and IL-8 by A549 cells. Irradiated A. fumigatus spores were partly internalised by A549 cells and inhibited A549 cells to produce IL-6. TNF-alpha pre-incubated A549 cells produced increased IL-6 after exposure to zymosan and WIAF. Immuno-histochemistry showed a negative staining for TLR2 and TLR4. CONCLUSIONS: The low levels of cytokines produced by A549 cells after the firm binding of either mycelium or spores of A. fumigatus may lead to insufficient recruitment of inflammatory cells to the infected site, which may result in the escape of detection by the immune defence system. TLR2 and TLR4 are probably not or only in part involved in the above process, although very low expression cannot be excluded.

Different modulation of decorin production by lung fibroblasts from patients with mild and severe emphysema.

We have previously reported diminished immunohistochemical staining of decorin in lung tissue from patients with severe emphysema. The aim of this study is to investigate whether this diminished staining is due to a quantitative abnormal production of decorin by pulmonary fibroblasts in vitro. Therefore, we measured decorin (Western blot), collagen type I (ELISA), and fibronectin (ELISA) production by fibroblasts obtained from lung tissue of patients with severe and mild emphysema at basal culture conditions and after modulation with transforming growth factor-beta1, basic fibroblast growth factor, and interferon-gamma. Decorin production at basal culture conditions was significantly higher in fibroblast cultures from patients with severe emphysema compared to fibroblasts from mild emphysema. After stimulation with transforming growth factor-beta1 and basic fibroblast growth factor, decorin production was significantly more reduced in fibroblast cultures from patients with severe emphysema whereas collagen type I and fibronectin production were not affected. We conclude that decorin production by lung fibroblasts of patients with severe emphysema is dysregulated after modulation with cytokines known to be important in smoking associated inflammation. This dysregulation of decorin production may contribute to the impaired lung tissue repair, present in patients with emphysema, since these alterations in the extracellular matrix may cause diminished cytokine binding and neutralization.

Different proliferative capacity of lung fibroblasts obtained from control subjects and patients with emphysema.

To characterize the possible role of a dysregulated proliferative capacity of pulmonary fibroblasts in insufficient tissue repair in lungs from patients with pulmonary emphysema, the authors undertook in vitro proliferative studies with pulmonary fibroblasts obtained from lung tissue of patients with emphysema. A comparison was made with fibroblasts from control subjects. The authors determined the in vitro proliferative capacity of fibroblasts at basal culture conditions and after modulation with interleukin-1beta, interferon-gamma, transforming growth factor-beta(1), and basic fibroblast growth factor. Proliferative capacity was determined by measurement of 5-bromo-2-deoxyuridine (BrdU) incorporation. BrdU incorporation by fibroblast cultures from both groups was very similar. Fibroblast cultures from control subjects, however, incorporated more BrdU after incubation with interleukin-1beta than cultures from patients with emphysema (P<.05). On the other hand, transforming growth factor-beta(1) decreased incorporation of BrdU stronger in fibroblast cultures from control subjects than from patients with emphysema (P<.05). Thus, the proliferative capacity of fibroblast cultures isolated from lung tissue of patients with pulmonary emphysema is different from that of control subjects. Although the difference is small, it may be an essential contribution to the development of pulmonary emphysema that only occurs after repeated smoke-induced injury over many years of an individual's life.