Palifermin induces alveolar maintenance programs in emphysematous mice

RATIONALE

Emphysema is characterized by destruction of alveoli with ensuing airspace enlargement and loss of alveoli. Induction of alveolar regeneration is still a major challenge in emphysema therapy.

OBJECTIVES

To investigate whether therapeutic application of palifermin (DeltaN23-KGF) is able to induce a regenerative response in distal lung parenchyma after induction of pulmonary emphysema.

METHODS

Mice were therapeutically treated at three occasions by oropharyngeal aspiration of 10 mg DeltaN23-KGF per kg body weight after induction of emphysema by porcine pancreatic elastase.

MEASUREMENTS AND MAIN RESULTS

Airflow limitation associated with emphysema was largely reversed as assessed by noninvasive head-out body plethysmography. Porcine pancreatic elastase-induced airspace enlargement and loss of alveoli were partially reversed as assessed by design-based stereology. DeltaN23-KGF induced proliferation of epithelium, endothelium, and fibroblasts being associated with enhanced differentiation as well as increased expression of vascular endothelial growth factor, vascular endothelial growth factor receptors, transforming growth factor (TGF)-beta1, TGF-beta2, (phospho-) Smad2, plasminogen activator inhibitor-1, and elastin as assessed by quantitative reverse transcriptase-polymerase chain reaction, Western blotting, and immunohistochemistry. DeltaN23-KGF induced the expression of TGF-beta1 in and release of active TGF-beta1 from primary mouse alveolar epithelial type 2 (AE2) cells, murine AE2-like cells LA-4, and cocultures of LA-4 and murine lung fibroblasts (MLF), but not in MLF cultured alone. Recombinant TGF-beta1 but not DeltaN23-KGF induced elastin gene expression in MLF. Blockade of TGF-signaling by neutralizing antibody abolished these effects of DeltaN23-KGF in LA-4/MLF cocultures.

CONCLUSIONS

Our data demonstrate that therapeutic application of DeltaN23-KGF has the potential to induce alveolar maintenance programs in emphysematous lungs and suggest that the regenerative effect on interstitial tissue is linked to AE2 cell-derived TGF-beta1.

Systematic comparison of RNA extraction techniques from frozen and fresh lung tissues: checkpoint towards gene expression studies

Background

The reliability of gene expression profiling-based technologies to detect transcriptional differences representative of the original samples is affected by the quality of the extracted RNA. It strictly depends upon the technique that has been employed. Hence, the present study aimed at systematically comparing silica-gel column (SGC) and guanidine isothiocyanate (GTC) techniques of RNA isolation to answer the question which technique is preferable when frozen, long-term stored or fresh lung tissues have to be evaluated for the downstream molecular analysis.

Methods

Frozen lungs (n = 3) were prepared by long-term storage (2.5 yrs) in -80°C while fresh lungs (n = 3) were harvested and processed immediately. The purity and quantification of RNA was determined with a spectrophotometer whereas the total amounted copy numbers of target sequences were determined with iCycler detection system for assessment of RNA intactness (28S and 18S) and fragment sizes, i.e. short (GAPDH-3' UTR), medium (GAPDH), and long (PBGD) with 200 bp, 700 bp, and 1400 bp distance to the 3'ends of mRNA motif, respectively.

Results

Total yield of RNA was higher with GTC than SGC technique in frozen as well as fresh tissues while the purity of RNA remained comparable. The quantitative reverse transcriptase-polymerase chain reaction data revealed that higher mean copy numbers of 28S and a longer fragment (1400 bp) were obtained from RNA isolated with SGC than GTC technique using fresh as well as frozen tissues. Additionally, a high mean copy number of 18S and medium fragment (700 bp) were obtained in RNA isolated with SGC technique from fresh tissues, only. For the shorter fragment, no significant differences between both techniques were noticed.

Conclusion

Our data demonstrated that although the GTC technique has yielded a higher amount of RNA, the SGC technique was much more superior with respect to the reliable generation of an intact RNA and effectively amplified longer products in fresh as well as in frozen tissues.

Composition of the immunoglobulin classic antigen-binding site regulates allergic airway inflammation in a murine model of experimental asthma

BACKGROUND

When bound to mast cell FcepsilonRI, IgE serves as antigen receptor for allergic reactions, permitting specific identification of the allergen. Although the core of the classic antigen-binding site is heavy chain complementarity determining region 3 (CDR-H3), recent studies suggest that allergens might also bind IgE in a superantigen-like fashion outside the classic antigen-binding site.

OBJECTIVE

We sought to evaluate the contribution of the classic CDR-H3-centric antigen-binding site to the development of an allergic phenotype.

METHODS

Using a murine model of experimental asthma, we characterized a gene-targeted mouse strain expressing an altered range of CDR-H3s (DeltaD-iD mice) in response to the hydrophobic allergen ovalbumin (OVA). Mutant and wild-type (wt) mice were sensitized intraperitoneally with OVA; non-sensitized mice served as controls.

RESULTS

We found the composition of the classic CDR-H3-centric antigen-binding site to be critical for the development of characteristic aspects of allergic asthma. (i) Compared with wt animals, DeltaD-iD mice showed a significantly less pronounced OVA-induced rise in allergen-specific IgE levels and hence in total serum IgE levels. (ii) In addition, DeltaD-iD mice demonstrated a significant reduction in eosinophilic airway inflammation, as well as in interleukin-4 (IL-4), IL-5 and IL-13 levels in BAL fluids.

CONCLUSION

Allergic sensitization and airway inflammation depend on the composition of the predominant CDR-H3 repertoire, suggesting that the classic CDR-H3-centric antigen-binding site plays a crucial role in creating the immunological interface between allergen and IgE. Our results further emphasize a central role of IgE, not only in mediating but also in regulating the allergic immune response.

Decreased pathology and prolonged survival of human DC-SIGN transgenic mice during mycobacterial infection

Dendritic cell (DC)-specific intercellular adhesion molecule-3 grabbing nonintegrin (DC-SIGN: CD209) is a C-type lectin that binds ICAM-2,3 and various pathogens such as HIV, helicobacter, and mycobacteria. It has been suggested that Mycobacterium tuberculosis, the causative agent of pulmonary tuberculosis, interacts with DC-SIGN to evade the immune system. To directly analyze the role of human DC-SIGN during mycobacterial infection, we generated conventional transgenic (tg) mice (termed "hSIGN") using CD209 cDNA under the control of the murine CD11c promoter. Upon mycobacterial infection, DCs from hSIGN mice produced significantly less IL-12p40 and no significant differences were be observed in the secretion levels of IL-10 relative to control DCs. After high dose aerosol infection with the strain M. tuberculosis H37Rv, hSIGN mice showed massive accumulation of DC-SIGN(+) cells in infected lungs, reduced tissue damage and prolonged survival. Based on our in vivo data, we propose that instead of favoring the immune evasion of mycobacteria, human DC-SIGN may have evolved as a pathogen receptor promoting protection by limiting tuberculosis-induced pathology.

Anti-acids lead to immunological and morphological changes in the intestine of BALB/c mice similar to human food allergy

We have shown that anti-acid medication for treating dyspeptic disorders can block protein digestion and induce a higher risk for food sensitization. This mechanism was confirmed in human and animal studies on the humoral as well as the cellular level. Here we aimed to investigate the outcome of the treatment with the anti-acid drug sucralfate on the intestine in our murine model, assuming that morphological and immunological changes will occur. BALB/c mice were fed codfish extract plus sucralfate. Antibodies were examined in ELISA, RBL assay and Western blot. Quantitative morphological analysis of the intestine was performed by design-based stereology, focussing on epithelium, lamina propria, smooth muscle, eosinophils and CD3(+) cells. Histological analyses were performed after H&E-, PAS- and Congo red-staining, while immune histochemistry was done for detection of CD3(+) cells. Codfish-specific IgE and its activity in RBL assay confirmed the Th2-response after treatment with sucralfate. The reactivity pattern of murine IgE in Western blot was similar to allergic patients' IgE. Histological examination showed more slender villi in the duodenum, and increased goblet cell mucus in the cecum after sucralfate treatment. Stereological analyses of the intestine revealed higher eosinophil/CD3(+) ratios, decreased mean thickness of the epithelium of duodenum and cecum, and thinner smooth muscle cell layer in the colon of food allergic mice. Anti-acid treatment with sucralfate induces changes in the structure of epithelium and villi, and an increase in eosinophils and mucus-producing cells in the intestine. Therefore, this medication leads to sensitization against food with changes typical for food allergy also in the intestine.

Keratinocyte growth factor protects against Clara cell injury induced by naphthalene

Airway epithelial cells are exposed to environmental toxicants that result in airway injury. Naphthalene (NA) causes site-selective damage to Clara cells in mouse distal airways. N-terminally truncated recombinant human keratinocyte growth factor (DeltaN23-KGF) protects against acute lung injury. The present study investigated whether or not DeltaN23-KGF protects against NA-induced acute Clara cell damage by measuring airway responses specifically and in order to identify underlying molecular mechanisms. Mice were treated with DeltaN23-KGF or PBS 33 h prior to injection of 200 mg.kg body weight(-1) NA. Lung function was analysed by head-out body plethysmography. Distal airways isolated by microdissection were assessed for cell permeability using ethidium homodimer-1. Immunohistochemistry of Clara cell-specific protein in conjunction with a physical dissector was used to quantify Clara cell numbers. RNA was isolated from frozen airways in order to analyse gene expression using quantitative RT-PCR. DeltaN23-KGF prevented NA-induced airflow limitation and Clara cell permeability, and resulted in twice as many Clara cells compared with PBS pre-treatment. DeltaN23-KGF-pre-treated mice exhibited increased expression of proliferating cell nuclear antigen mRNA. Cytochrome P(450) isoform 2F2, which converts NA into its toxic metabolite, was reduced by approximately 50%. The present results demonstrate that pre-treatment with N-terminally truncated recombinant human keratinocyte growth factor protects against naphthalene-induced injury. This suggests that N-terminally truncated recombinant human keratinocyte growth factor exerts its beneficial effect through a decrease in the expression of cytochrome P(450) isoform 2F2.

Treatment with keratinocyte growth factor does not improve lung allograft survival in the rat

PURPOSE

Lung allografts are threatened by primary graft dysfunction, infections, and rejection. Novel therapies protecting pulmonary allografts are badly needed. Keratinocyte growth factor (KGF) protects the lung against a variety of injurious stimuli and exerts anti-inflammatory effects. The aim of the study was to test the potential of recombinant truncated KGF (DeltaN23-KGF, palifermin) to attenuate pulmonary allograft rejection.

MATERIALS AND METHODS

Intratracheal instillation of 5 mg/kg DeltaN23-KGF was performed twice in donor rats on days 3 and 2 before explantation of the lung. In control animals, an equivalent volume of vehicle was instilled. Left lungs were transplanted in the fully allogeneic Dark Agouti to Lewis rat strain combination and in the less stringent Fischer 344 to Wistar Kyoto combination. Allograft recipients were additionally treated with DeltaN23-KGF post-transplantation. Graft outcome, leukocytic infiltration, and major histocompatibility complex (MHC) class II antigen expression was analyzed.

RESULTS

In both rat strain combinations, DeltaN23-KGF treatment did not improve pulmonary allograft outcome. Graft infiltration by macrophages and T lymphocytes remained unchanged. In addition, we demonstrated that MHC class II antigens were more abundant in KGF-treated allografts compared to control-treated grafts, which probably results in an increased alloreactivity.

CONCLUSION

In conclusion, intratracheal DeltaN23-KGF treatment is not effective to prevent acute pulmonary allograft rejection.

Keratinocyte growth factor prevents intra-alveolar oedema in experimental lung isografts

Primary graft dysfunction, characterised by intra-alveolar oedema, is a major obstacle in pulmonary transplantation. The present study evaluates the potential of keratinocyte growth factor (palmiferin; DeltaN23-KGF) for the prevention of oedema in lung transplants. Intratracheal instillation of 5 mg x kg(-1) DeltaN23-KGF was performed in Lewis rats on days 3 and 2 before explantation. Control animals obtained an equivalent volume of vehicle. Left lungs were isogeneically transplanted and the graft recipients were sacrificed 1 day later for stereological analysis of intra-alveolar oedema and bronchoalveolar lavage. The total protein and phospholipid content, as well as surfactant proteins, were measured. Surfactant activity was analysed with a pulsating bubble surfactometer. In grafts from control treated donors, the fraction of intra-alveolar oedema amounted to 3.4+/-1.1% of the total parenchymal volume. Treatment of donor lungs with DeltaN23-KGF reduced oedema to a fraction of 1.6+/-0.8%. In the lavage fluid of pulmonary grafts from DeltaN23-KGF-treated donors, the total protein content was decreased compared with vehicle-treated lung transplants, whereas phospholipids did not differ. The protein fraction contained increased amounts of surfactant protein-C after DeltaN23-KGF treatment and surfactant function was improved. Treatment of donor lungs with palifermin protects against intra-alveolar oedema formation upon transplantation. This effect appears to be mediated by an improved surfactant homeostasis.

Effects of keratinocyte growth factor on intra-alveolar surfactant fixed in situ: Quantitative ultrastructural and immunoelectron microscopic analysis

Quantitative (immuno) transmission electron microscopy using design-based stereology was performed on specimens collected by means of systematic uniform random sampling of rat lungs, which were fixed by vascular perfusion to stabilize intra-alveolar surfactant in situ. This procedure ensures that the data recorded are representative of the whole organ. Ultrathin sections of specimens embedded at low temperature in Lowicryl HM20 were labeled by indirect immuno-gold staining for surfactant protein A. We observed that, 3 days after treatment of lungs in vivo with truncated keratinocyte growth factor (DeltaN23-KGF), a potent mitogen of alveolar epithelial type II cells, surfactant protein A associated with the tubular myelin fraction of intra-alveolar surfactant was increased by 47% in comparison with buffer-treated control lungs. Despite the marked type II cell hyperplasia, the relative amount of ultrastructural surfactant subtypes was not significantly affected. Because surfactant protein A reduces the sensitivity to inhibition of the biophysical activity of surfactant by exudating plasma proteins, we propose that pretreatment of lungs with DeltaN23-KGF ameliorates adverse effects observed in acute lung injury following, for example, ischemia and reperfusion.

[Pathogenesis of chronic obstructive pulmonary disease]

It is currently believed that the most important factor in the pathogenesis of chronic obstructive pulmonary disease (COPD) is inflammation of the small airways caused by inhaled particles and gases. In this context, a disturbance of the physiological balance between proteases and antiproteases develops that may cause lung emphysema. Moreover, oxidative stress seems to be important, as it may enhance the inflammatory reaction. The development of emphysema may also involve a loss of alveolar cells by apoptosis. Finally, several studies have indicated that a systemic inflammation is induced by COPD that may be of relevance to the development of systemic components that are observed in COPD patients.

Administration of keratinocyte growth factor (KGF) modulates the pulmonary expression of nicotinic acetylcholine receptor subunits alpha7, alpha9 and alpha10

Administration of recombinant human keratinocyte growth factor (rHuKGF, Delta23N-KGF, palifermin) protects the lung against a variety of injurious stimuli. The exact mechanisms leading to lung protection are unknown. Alterations in the non-neuronal cholinergic system of the lung might be involved, as vital pulmonary functions are regulated by acetylcholine. Here, we investigated the effect of KGF on the expression of nicotinic acetylcholine receptor subunits alpha7, alpha9 and alpha10 in rat lungs. Adult rats were treated via intratracheal instillation with rHuKGF or with an equivalent volume of PBS. The expression of nicotinic acetylcholine receptor subunits was analyzed by real-time RT-PCR, immunoblotting and immunohistochemistry. Treatment with rHuKGF led to a decreased expression of nicotinic receptor subunit alpha7 in the total lung. In contrast, the expression of the receptor subunits alpha9 and alpha10 was up-regulated. In conclusion, nicotinic acetylcholine receptors are differentially regulated by KGF treatment in vivo, which might result in changes in the biological effects of acetylcholine.

Nitrogen dioxide induces apoptosis and proliferation but not emphysema in rat lungs

BACKGROUND

Apoptosis of alveolar septal cells has been linked to emphysema formation. Nitrogen dioxide, a component of cigarette smoke, has been shown to induce alveolar epithelial cell apoptosis in vitro. It is hypothesised that exposure of rats to nitrogen dioxide may result in increased alveolar septal cell apoptosis in vivo with ensuing emphysema-that is, airspace enlargement and loss of alveolar walls.

METHODS

Fischer 344 rats were exposed to 10 ppm nitrogen dioxide for 3, 7, 21 days or 21 days followed by 28 days at room air. Age-matched control rats were exposed to room air for 3, 21 or 49 days. Lungs fixed at 20 cm fluid column, embedded in paraffin wax, glycol methacrylate and araldite, were analysed by design-based stereology. Alveolar septal cell apoptosis (transferase dUTP nick end labelling assay, active caspase 3) and proliferation (Ki-67), airspace enlargement, total alveolar surface area, and absolute alveolar septal volume as well as the ultrastructural composition of the alveolar wall were quantified.

RESULTS

Nitrogen dioxide resulted in an eightfold increase in alveolar septal cell apoptosis at day 3 and a 14-fold increase in proliferation compared with age-matched controls. Airspace enlargement, indicated by a 20% increase in mean airspace chord length, was evident by day 7 but was not associated with loss of alveolar walls. By contrast, nitrogen dioxide resulted in an increase in the total surface area and absolute volume of alveolar walls comprising all compartments. The ratio of collagen to elastin, however, was reduced at day 21. Lungs exposed to nitrogen dioxide for 21 days exhibited quantitative structural characteristics as seen in control lungs on day 49.

CONCLUSIONS

Nitrogen dioxide exposure of rats results in increased alveolar septal cell turnover leading to accelerated lung growth, which is associated with an imbalance in the relative composition of the extracellular matrix, but fails to induce emphysema.