A Günther

Justus-Liebig-Universität Gießen, Gieben, Hesse, Germany

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Publications (163)836.68 Total impact

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    ABSTRACT: Hemeoxygenase-1 (HO-1), an inducible heat shock protein, is upregulated in response to multiple cellular insults via oxidative stress, lipopolysaccharides (LPS) and hypoxia. In this study, we investigated in vitro the role of toll-like receptor 4 (TLR4), hypoxia-inducible factor-1α (HIF-1α) and iron on HO-1 expression in cystic fibrosis (CF). Immunohistochemical analysis of TLR4, HO-1, ferritin and HIF-1α were performed on lung sections of CFTR-/- and wildtype mice. CFBE41o- and 16HBE14o- cell lines were employed for in vitro analysis via immunoblotting, immunofluorescence, real-time PCR, luciferase reporter gene analysis and iron quantification. We observed a reduced TLR4, HIF-1α, HO-1, and ferritin in CFBE41o- cell line and CF mice. Knockdown studies using TLR4-siRNA in 16HBE14o- revealed significant decrease of HO-1, confirming the role of TLR4 in HO-1 downregulation. Inhibition of HO-1 using tin protoporphyrin in 16HBE14o- cells resulted in increased iron levels suggesting a probable role of HO-1 in iron accumulation. Additionally, sequestration of excess iron using iron chelators resulted in increased HRE response in CFBE41o- and 16HBE14o- implicating a role of iron in HIF-1α stabilization and HO-1. To conclude, our in vitro results demonstrate that multiple regulatory factors such as impaired TLR4 surface expression, increased intracellular iron and decreased HIF-1α downregulates HO-1 expression in CFBE41o- cells.
    American journal of physiology. Lung cellular and molecular physiology. 09/2014;
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    ABSTRACT: Amiodarone (AD) is a highly efficient antiarrhythmic drug with potentially serious side effects. Severe pulmonary toxicity is reported in patients receiving AD even at low doses, and may cause interstitial pneumonia as well as lung fibrosis. Apoptosis of alveolar epithelial type II cells (AECII) has been suggested to play an important role in this disease. In the current study, we aimed to establish a murine model of AD induced lung fibrosis and analyze surfactant homeostasis, lysosomal and endoplasmic reticulum stress in this model. AD/ vehicle was instilled intratracheally into C57BL/6 mice, which were sacrificed on days 7, 14, 21 and 28. Extent of lung fibrosis development was assessed by trichrome staining and hydroxyproline measurement. Cytotoxicity was assessed by lactate dehydrogenase assay. Phospholipids (PL) were analyzed by mass spectrometry. Surfactant proteins (SP) and markers for apoptosis, lysosomal & ER stress were studied by western blotting and immunohistochemistry. AECII morphology was evaluated by electron microscopy. Extensive lung fibrosis and AECII hyperplasia was observed in AD treated mice already at day7. Surfactant PL and SP accumulated in AECII over time. In parallel, induction of apoptosis, lysosomal and ER stress was encountered in AECII of mice lungs and in MLE12 cells treated with AD. In vitro, si RNA mediated knock down of cathepsin D did not alter the AD induced apoptotic response. Our data suggest that mice exposed to intratracheal AD develop severe pulmonary fibrosis, exhibit extensive surfactant alterations and cellular stress, but AD induced AECII apoptosis is not mediated primarily via cathepsin D.
    Toxicological sciences : an official journal of the Society of Toxicology. 08/2014;
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    ABSTRACT: The current study investigated the mechanisms involved in the process of biophysical inhibition of pulmonary surfactant by polymeric nanoparticles0020(NP). The minimal surface tension of diverse synthetic surfactants was monitored in the presence of bare and surface-decorated (i.e. poloxamer 407) sub-100 nm poly(lactide) NP. Moreover, the influence of NP on surfactant composition (i.e. surfactant protein (SP) content) was studied. Dose-elevations of SP advanced the biophysical activity of the tested surfactant preparation. SP-C supplemented phospholipid mixtures (PLM-C) were shown to be more susceptible to biophysical inactivation by bare NP than PLM-B and PLM-B/C. Surfactant function was hindered due to a drastic depletion of the SP content upon contact with bare NP. By contrast, surface-modified NP were capable to circumvent unwanted surfactant inhibition. Surfactant constitution influences the extent of biophysical inhibition by polymeric NP. Steric shielding of the NP surface minimizes unwanted NP-surfactant interactions, which represents an option for the development of surfactant-compatible nanomedicines.
    Acta biomaterialia. 07/2014;
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    ABSTRACT: Rationale: Idiopathic pulmonary fibrosis (IPF) and bleomycin-induced pulmonary fibrosis are associated with surfactant-system dysfunction, alveolar collapse (derecruitment), and collapse induration (irreversible collapse). These events play undefined roles in the loss of lung function. Objective: To quantify how surfactant inactivation, alveolar collapse and collapse induration lead to degradation of lung function. Methods and measurements: Design-based stereology and invasive pulmonary function tests were performed 1, 3, 7, and 14 days (D) following intratracheal bleomycin-instillation in rats. The number and size of open alveoli was correlated to mechanical properties. Main Results: Active surfactant subtypes declined by D1, associated with a progressive alveolar derecruitment and a decrease in compliance. Alveolar epithelial damage was more pronounced in closed alveoli compared to ventilated alveoli. Collapse induration occurred on D7 and D14 as indicated by collapsed alveoli overgrown by a hyperplastic alveolar epithelium. This pathophysiology was also observed for the first time in human IPF lung explants. Prior to the onset of collapse induration, distal airspaces were easily recruited, and lung elastance could be kept low after recruitment by positive end-expiratory pressure (PEEP). At later time points the recruitable fraction of the lung was reduced by collapse induration, causing elastance to be elevated at high levels of PEEP. Conclusion: Surfactant inactivation leading to alveolar collapse and subsequent collapse induration might be the primary pathway for the loss of alveoli in this animal model. Loss of alveoli is highly correlated with the degradation of lung function. Our ultrastructural observations suggest that collapse induration is important in human IPF.
    American Journal of Respiratory Cell and Molecular Biology 07/2014; · 4.15 Impact Factor
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    ABSTRACT: BACKGROUND: Nintedanib (formerly known as BIBF 1120) is an intracellular inhibitor that targets multiple tyrosine kinases. A phase 2 trial suggested that treatment with 150 mg of nintedanib twice daily reduced lung-function decline and acute exacerbations in patients with idiopathic pulmonary fibrosis. METHODS: We conducted two replicate 52-week, randomized, double-blind, phase 3 trials (INPULSIS-1 and INPULSIS-2) to evaluate the efficacy and safety of 150 mg of nintedanib twice daily as compared with placebo in patients with idiopathic pulmonary fibrosis. The primary end point was the annual rate of decline in forced vital capacity (FVC). Key secondary end points were the time to the first acute exacerbation and the change from baseline in the total score on the St. George's Respiratory Questionnaire, both assessed over a 52-week period. RESULTS: A total of 1066 patients were randomly assigned in a 3:2 ratio to receive nintedanib or placebo. The adjusted annual rate of change in FVC was -114.7 ml with nintedanib versus -239.9 ml with placebo (difference, 125.3 ml; 95% confidence interval [CI], 77.7 to 172.8; P<0.001) in INPULSIS-1 and -113.6 ml with nintedanib versus -207.3 ml with placebo (difference, 93.7 ml; 95% CI, 44.8 to 142.7; P<0.001) in INPULSIS-2. In INPULSIS-1, there was no significant difference between the nintedanib and placebo groups in the time to the first acute exacerbation (hazard ratio with nintedanib, 1.15; 95% CI, 0.54 to 2.42; P=0.67); in INPULSIS-2, there was a significant benefit with nintedanib versus placebo (hazard ratio, 0.38; 95% CI, 0.19 to 0.77; P=0.005). The most frequent adverse event in the nintedanib groups was diarrhea, with rates of 61.5% and 18.6% in the nintedanib and placebo groups, respectively, in INPULSIS-1 and 63.2% and 18.3% in the two groups, respectively, in INPULSIS-2. CONCLUSIONS: In patients with idiopathic pulmonary fibrosis, nintedanib reduced the decline in FVC, which is consistent with a slowing of disease progression; nintedanib was frequently associated with diarrhea, which led to discontinuation of the study medication in less than 5% of patients.
    New England Journal of Medicine 05/2014; 370(22):2071-82. · 54.42 Impact Factor
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    ABSTRACT: The regulation of the balance between proliferation and differentiation in the mesenchymal compartment of the lung is largely uncharacterized, unlike its epithelial counterpart. In this study, we determined that miR-142-3p contributes to the proper proliferation of mesenchymal progenitors by controlling the level of WNT signaling. miR-142-3p can physically bind to adenomatous polyposis coli mRNA, functioning to regulate its expression level. In miR-142-3p loss-of-function experiments, proliferation of parabronchial smooth muscle cell progenitors is significantly impaired, leading to premature differentiation. Activation of WNT signaling in the mesenchyme, or Apc loss of function, can both rescue miR-142-3p knockdown. These findings show that in the embryonic lung mesenchyme, the microRNA machinery modulates the level of WNT signaling, adding an extra layer of control in the feedback loop between FGFR2C and β-catenin-mediated WNT signaling.
    Development 02/2014; · 6.60 Impact Factor
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    ABSTRACT: Chronic injury of alveolar lung epithelium leads to epithelial disintegrity in idiopathic pulmonary fibrosis (IPF). We had reported earlier that Grhl2, a transcriptional factor, maintains alveolar epithelial cell integrity by directly regulating components of adherens and tight junctions and thus hypothesized an important role of GRHL2 in pathogenesis of IPF. Comparison of GRHL2 distribution at different stages of human lung development showed its abundance in developing lung epithelium and in adult lung epithelium. However, GRHL2 is detected in normal human lung mesenchyme only at early fetal stage (week 9). Similar mesenchymal reexpression of GRHL2 was also observed in IPF. Immunofluorescence analysis in serial sections from three IPF patients revealed at least two subsets of alveolar epithelial cells (AEC), based on differential GRHL2 expression and the converse fluorescence intensities for epithelial vs. mesenchymal markers. Grhl2 was not detected in mesenchyme in intraperitoneal bleomycin-induced injury as well as in spontaneously occurring fibrosis in double-mutant HPS1 and HPS2 mice, whereas in contrast in a radiation-induced fibrosis model, with forced Forkhead box M1 (Foxm1) expression, an overlap of Grhl2 with a mesenchymal marker was observed in fibrotic regions. Grhl2's role in alveolar epithelial cell plasticity was confirmed by altered Grhl2 gene expression analysis in IPF and further validated by in vitro manipulation of its expression in alveolar epithelial cell lines. Our findings reveal important pathophysiological differences between human IPF and specific mouse models of fibrosis and support a crucial role of GRHL2 in epithelial activation in lung fibrosis and perhaps also in epithelial plasticity.
    AJP Lung Cellular and Molecular Physiology 12/2013; · 3.52 Impact Factor
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    ABSTRACT: TGF-β is a pathogenic factor in patients with acute respiratory distress syndrome (ARDS), a condition characterized by alveolar edema. A unique TGF-β pathway is described, which rapidly promoted internalization of the αβγ epithelial sodium channel (ENaC) complex from the alveolar epithelial cell surface, leading to persistence of pulmonary edema. TGF-β applied to the alveolar airspaces of live rabbits or isolated rabbit lungs blocked sodium transport and caused fluid retention, which-together with patch-clamp and flow cytometry studies-identified ENaC as the target of TGF-β. TGF-β rapidly and sequentially activated phospholipase D1, phosphatidylinositol-4-phosphate 5-kinase 1α, and NADPH oxidase 4 (NOX4) to produce reactive oxygen species, driving internalization of βENaC, the subunit responsible for cell-surface stability of the αβγENaC complex. ENaC internalization was dependent on oxidation of βENaC Cys(43). Treatment of alveolar epithelial cells with bronchoalveolar lavage fluids from ARDS patients drove βENaC internalization, which was inhibited by a TGF-β neutralizing antibody and a Tgfbr1 inhibitor. Pharmacological inhibition of TGF-β signaling in vivo in mice, and genetic ablation of the nox4 gene in mice, protected against perturbed lung fluid balance in a bleomycin model of lung injury, highlighting a role for both proximal and distal components of this unique ENaC regulatory pathway in lung fluid balance. These data describe a unique TGF-β-dependent mechanism that regulates ion and fluid transport in the lung, which is not only relevant to the pathological mechanisms of ARDS, but might also represent a physiological means of acutely regulating ENaC activity in the lung and other organs.
    Proceedings of the National Academy of Sciences 12/2013; · 9.81 Impact Factor
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    ABSTRACT: Reasonable suspicion has accumulated that inhaled nano-scale particulate matter influences the biophysical function of the pulmonary surfactant system. Hence, it is evident to provide novel insights into the extent and mechanisms of nanoparticle-surfactant interactions in order to facilitate the fabrication of safe nanomedicines suitable for pulmonary applications. Negatively- and positively-charged poly(styrene) nanoparticles (diameters of ~100nm) served as model carriers. Nanoparticles were incubated with several synthetic and naturally-derived pulmonary surfactants to characterize the sensitivity of each preparation to biophysical inactivation. Changes in surface properties (i.e. adsorption and dynamic surface tension behavior) were monitored in a pulsating bubble surfactometer. Both nanoparticle formulations revealed a dose-dependent influence on the biophysical behavior of all investigated pulmonary surfactants. However, the surfactant sensitivity towards inhibition depended on both the carrier type, where negatively-charged nanoparticles showed increased inactivation potency compared to their positively-charged counterparts, and surfactant composition. Among the surfactants tested, synthetic mixtures (i.e. phospholipids, phospholipids supplemented with surfactant protein B, and Venticute®) were more susceptible to surface-activity inhibition as the more complex naturally-derived preparations (i.e. Alveofact® and large surfactant aggregates isolated from rabbit bronchoalveolar lavage fluid). Overall, nanoparticle characteristics and surfactant constitution both influence the extent of biophysical inhibition of pulmonary surfactants.
    Biochimica et Biophysica Acta 10/2013; · 4.66 Impact Factor
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    ABSTRACT: Among the idiopathic interstitial pneumonias (IIP), the two entities IPF and NSIP seem to be clinically related, but NSIP has a better outcome. The proteomic signatures which distinguish NSIP from IPF remain still elusive. We therefore performed comparative proteomic analysis of peripheral lung tissue from patients with sporadic IPF (n=14) and fibrotic NSIP (fNSIP, n=8) and organ donors (Controls, n=10), by using the 2-dimensional DIGE technique and MALDI-TOF-MS. The study revealed that the proteomic profiles of IPF and fNSIP were quite similar. Among the upregulated proteins in IPF and fNSIP were stress-induced genes involved in the ER stress-pathway, whereas downregulated proteins in IPF and fNSIP included antiapoptotic factors and antifibrotic molecules. The comparison fNSIP versus IPF indicated upregulation of subunits of the proteasome activator complex and antioxidant enzymes of the peroxiredoxin family. We conclude, that only few protein expression changes exist between IPF and fNSIP, and that epithelial ER- and oxidative stress play a major role in the pathogenesis of both diseases. In contrast to IPF, intracellular clearance of ROS and misfolded protein carbonyls seem to be enhanced in fNSIP due to enhanced expression of antioxidant acting proteins, and may explain the better outcome and survival in patients with fNSIP. BIOLOGICAL SIGNIFICANCE: IPF and fibrotic NSIP (fNSIP) belong to the idiopathic interstitial pneumonias and are usually fatal, but fNSIP has a better outcome. In order to identify molecular mechanisms and differences between IPF and fNSIP, we herein present results of a comparative proteome analysis of IPF, fNSIP and control lung tissue. Our data including validation experiments suggest that ER stress and a general stress-response as well as the decline of antioxidant capacity in alveolar epithelium is key in the pathogenesis of IPF and fNSIP. In addition, we could observe a signature of an increased alveolar epithelial protection against oxidative and ER-stress in fNSIP as compared to IPF, which could help to explain the better outcome of fNSIP patients.
    Journal of proteomics 05/2013; · 5.07 Impact Factor
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    ABSTRACT: Posttranslational modification of the neural cell adhesion molecule (NCAM) by polysialic acid (polySia) is well studied in the nervous system and described as a dynamic modulator of plastic processes like precursor cell migration, axon fasciculation, and synaptic plasticity. Here, we describe a novel function of polysialylated NCAM (polySia-NCAM) in innate immunity of the lung. In mature lung tissue of healthy donors, polySia was exclusively attached to the transmembrane isoform NCAM-140 and located to intracellular compartments of epithelial cells. In patients with chronic obstructive pulmonary disease, however, increased polySia levels and processing of the NCAM carrier were observed. Processing of polysialylated NCAM was reproduced in a mouse model by bleomycin administration leading to an activation of the inflammasome and secretion of interleukin (IL)-1β. As shown in a cell culture model, polySia-NCAM-140 was kept in the late trans-Golgi apparatus of lung epithelial cells and stimulation by IL-1β or lipopolysaccharide induced metalloprotease-mediated ectodomain shedding, resulting in the secretion of soluble polySia-NCAM. Interestingly, polySia chains of secreted NCAM neutralized the cytotoxic activity of extracellular histones as well as DNA/histone-network-containing "neutrophil extracellular traps", which are formed during invasion of microorganisms. Thus, shedding of polySia-NCAM by lung epithelial cells may provide a host-protective mechanism to reduce tissue damage during inflammatory processes.
    Cellular and Molecular Life Sciences CMLS 04/2013; · 5.62 Impact Factor
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    ABSTRACT: Idiopathic pulmonary fibrosis (IPF) is a lethal lung disease of yet unknown etiology. It is characterised by alterations of the alveolar epithelium, myofibroblast activation, and increased extracellular matrix deposition. Recently, reactivation of WNT/β-catenin signaling has been linked with IPF. The cell-specific mechanisms and mediators of WNT/β-catenin signaling in the lung, however, remain elusive. Here, we applied an unbiased gene expression screen to identify epithelial cell-specific mediators of WNT/β-catenin signaling. We found the proinflammatory cytokine interleukin (IL) 1β as one of the most upregulated genes in primary murine alveolar epithelial type (AT) II cells after WNT3a treatment. Increased transcript and protein expression of IL-1β upon WNT3a treatment was further detected in primary ATII cells by qRT-PCR (log-fold change: 2.0 +/- 0.5) and ELISA (1.8 fold increase). We observed significant IL-1β and IL-6 upregulation in bronchoalveolar lavage fluid (BALF) in bleomycin induced lung fibrosis in vivo. Importantly, primary fibrotic ATII cells secreted enhanced IL-1β and IL-6 in vitro. Furthermore, orotracheal application of recombinant WNT protein in TOPGAL reporter animals led to WNT/β-catenin activation in epithelial cells along with a significant increase in IL-1β and IL-6 in vivo (2.7-fold and 6.0-fold, respectively). Finally, we found increased WNT3a protein in fibrotic alveolar epithelium accompanied by enhanced IL-1β and IL-6 level in BALF from IPF patients. Taken together, our findings revealed that the alveolar epithelium is a relevant source of proinflammatory cytokines induced by active WNT/β-catenin. Thus, WNT/interleukin signaling represents a novel link between developmental pathway reactivation and inflammation in the development of pulmonary fibrosis.
    American Journal of Respiratory Cell and Molecular Biology 03/2013; · 4.15 Impact Factor
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    ABSTRACT: Idiopathic pulmonary fibrosis (IPF) is a progressive fibroproliferative disease whose molecular pathogenesis remains unclear. In a recent paper, we demonstrated a key role for the PI3K pathway in both proliferation and differentiation into myofibroblasts of normal human lung fibroblasts treated with TGF-β. In this research, we assessed the expression of class I PI3K p110 isoforms in IPF lung tissue as well as in tissue-derived fibroblast cell lines. Moreover, we investigated the in vitro effects of the selective inhibition of p110 isoforms on IPF fibroblast proliferation and fibrogenic activity. IHC was performed on normal and IPF lung tissue. Expression levels of PI3K p110 isoforms were evaluated by western blot and flow cytometry analysis. Fibroblast cell lines were established from both normal and IPF tissue and the effects of selective pharmacological inhibition as well as specific gene silencing by small interfering RNAs were studied in vitro. No significant differences between normal and IPF tissue/tissue-derived fibroblasts were observed for the expression of PI3K p110 α, β and δ isoforms whereas p110γ was more greatly expressed in both IPF lung homogenates and ex vivo fibroblast cell lines. Myofibroblasts and bronchiolar basal cells in IPF lungs exhibited strong immunoreactivity for p110γ. Positive staining for the markers of proliferation proliferating cell nuclear antigen and cyclin D1 was also shown in cells of fibrolastic foci. Furthermore, both p110γ pharmacological inhibition and gene silencing were able to significantly inhibit proliferation rate as well as α-SMA expression in IPF fibroblasts. Our data suggest that PI3K p110γ isoform may have an important role in the etio-pathology of IPF and can be a specific pharmacological target.Laboratory Investigation advance online publication, 25 February 2013; doi:10.1038/labinvest.2013.6.
    Laboratory Investigation 02/2013; · 3.96 Impact Factor
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    ABSTRACT: Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive and fatal lung disease with no known etiology and treatment options. The hallmarks of the histopathology, which is characteristic of usual interstitial pneumonia (UIP) pattern, include interstitial fibrosis, honeycomb changes and fibroblast foci that develop owing to fibroblast proliferation and excessive matrix deposition. Although the complete pathomechanism is not yet understood, several molecular culprits, including transforming growth factor (TGF)-β, Angiotensin (Ang) II, endothelin (ET)-1, matrix metalloproteinases (MMPs) and cytokines have been identified. IPF is increasingly believed to be an epithelial-driven disease; however, the literature does support an implication of altered immune response and inflammatory processes in the onset or progression of the disease. Mast cells (MCs) are multifunctional tissue resident cells involved in the inflammatory and immune response. An increasing body of evidence suggests a role of MCs and their mediator chymase in the pathology of IPF. With regard to the underlying mechanisms, it is conceivable that MC chymase may function via activation or processing of factors such as proteases, cytokines and growth factors. In this review, we will discuss how MC chymase is linked to and can potentially contribute to the development of IPF. Moreover, the findings from animal model studies will be discussed to highlight the chymase inhibitors as a promising strategy for the treatment of pulmonary fibrosis.
    Histology and histopathology 02/2013; · 2.28 Impact Factor
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    ABSTRACT: Idiopathic pulmonary fibrosis is a fatal lung disease with a variable and unpredictable natural history and limited treatment options. Since publication of the ATS-ERS statement on IPF in the year 2000 diagnostic standards have improved and a considerable number of randomized controlled treatment trials have been published necessitating a revision. In the years 2006 - 2010 an international panel of IPF experts produced an evidence-based guideline on diagnosis and treatment of IPF, which was published in 2011. In order to implement this evidence-based guideline into the German Health System a group of German IPF experts translated and commented the international guideline, also including new publications in the field. A consensus conference was held in Bochum on December 3rd 2011 under the protectorate of the "Deutsche Gesellschaft für Pneumologie und Beatmungsmedizin (DGP)" and supervised by the "Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften" (AWMF). Most recommendations of the international guideline were found to be appropriate for the german situation. Based on recent clinical studies "weak negative" treatment recommendations for pirfenidone and anticoagulation were changed into "weak positive" for pirfenidone and "strong negative" for anticoagulation. Based on negative results from the PANTHER-trial the recommendation for the combination therapy of prednisone plus azathiorpine plus N-acetlycsteine was also changed into strong negative für patients with definite IPF. This document summarizes essential parts of the international IPF guideline and the comments and recommendations of the German IPF consensus conference.
    Pneumologie 01/2013;
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    ABSTRACT: Idiopathic pulmonary fibrosis (IPF) is a fatal disease characterized by excessive deposition of extracellular matrix (ECM). We investigated the regulation of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) in lung fibrosis. MMP and TIMP expression, collagenolytic activity and collagen content was assessed in IPF (n=16) versus donor (n=6) lung homogenates and accomplished by in-situ-zymography for gelatinolytic and collagenolytic activities, combined with MMP antigen detection. Role of MMP13 was assessed employing the bleomycin model of lung fibrosis in MMP-13(-/-) versus wild-type mice. In IPF, MMPs-1, 2, 7, 9 and 13, but not MMP-8, were significantly upregulated, whereas none of the TIMPs (1-4) were significantly altered. Collagen content was slightly increased and collagenolytic activity was most prominent in the airways and co-localized with MMP-13. We observed an exaggerated early inflammatory response and an augmented lung fibrosis in bleomycin-challenged MMP-13(-/-) versus wild-type mice, with elevated lung collagen content 28d after bleomycin challenge in the MMP-13(-/-) mice. Our data suggest that i) collagen deposition in IPF lungs is not primarily due to excessive TIMP production, but rather due to overwhelming ECM production in face of an overall increased, but spatially imbalanced collagenolytic activity, ii) preferential distribution of collagenolytic activity, largely MMP-13, in the airways offers an explanation for the development of honeycomb cysts and iii) despite an overall increase in inflammatory cell content the presence of MMP-13 seems to limit the overall extent of ECM deposition in lung fibrosis.
    PLoS ONE 01/2013; 8(9):e73279. · 3.53 Impact Factor
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    ABSTRACT: Activated Cdc42-associated kinase 1 (ACK1) is a nonreceptor tyrosine kinase linked to cellular transformation. The aberrant regulation of ACK1 promotes tumor progression and metastasis. Therefore, ACK1 is regarded as a valid target in cancer therapy. Seven in absentia homolog (SIAH) ubiquitin ligases facilitate substrate ubiquitinylation that targets proteins to the proteasomal degradation pathway. Here we report that ACK1 and SIAH1 from Homo sapiens interact in a yeast two-hybrid screen. Protein-protein interaction studies and protein degradation analyses using deletion and point mutants of ACK1 verify that SIAH1 and the related SIAH2 interact with ACK1. The association between SIAHs and ACK1 depends on the integrity of a highly conserved SIAH-binding motif located in the far C-terminus of ACK1. Furthermore, we demonstrate that the interaction of ACK1 with SIAH1 and the induction of proteasomal degradation of ACK1 by SIAH1 are independent of ACK1's kinase activity. Chemical inhibitors blocking proteasomal activity corroborate that SIAH1 and SIAH2 destabilize the ACK1 protein by inducing its proteasomal turnover. This mechanism apparently differs from the lysosomal pathway targeting ACK1 after stimulation with the epidermal growth factor. Our data also show that ACK1, but not ACK1 mutants lacking the SIAH binding motif, has a discernable negative effect on SIAH levels. Additionally, knockdown approaches targeting the SIAH2 mRNA uncover specifically that the induction of SIAH2 expression, by hormonally-induced estrogen receptor (ER) activation, decreases the levels of ACK1 in luminal human breast cancer cells. Collectively, our data provide novel insights into the molecular mechanisms modulating ACK1 and they position SIAH ubiquitin ligases as negative regulators of ACK1 in transformed cells.Oncogene advance online publication, 3 December 2012; doi:10.1038/onc.2012.515.
    Oncogene 12/2012; · 8.56 Impact Factor
  • American Journal of Respiratory and Critical Care Medicine 11/2012; 186(10):939-40. · 11.04 Impact Factor
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    ABSTRACT: Pulmonary fibrosis is a devastating and progressive parenchymal lung disease with an extremely poor prognosis. Patients suffering from idiopathic pulmonary fibrosis (IPF) display a compromised lung function, alongside with pathophysiological features such as a highly-increased production of extracellular matrix, alveolar epithelial cell dysfunction and disordered fibroproliferation; features that are due to a dysregulated response to alveolar injury. Under pathophysiological conditions of IPF, abnormally high concentrations of nitric oxide (NO) are found, likely a result of an increased activity of the inducible nitric oxide synthase (NOS2), giving rise to products that contribute to fibrosis development. It is known that pharmacological inhibition or knockdown of NOS2 reduces pulmonary fibrosis, suggesting a role for NOS inhibitors in the treatment of fibrosis. Recent reports identified a critical enzyme, dimethylarginine dimethylaminohydrolase (DDAH), which is exceedingly active in patients suffering from IPF and in mice treated with bleomycin. An upregulation of DDAH was observed in primary alveolar epithelial type II (ATII) cells from mice and patients with pulmonary fibrosis, where it colocalizes with NOS2. DDAH is a key enzyme that breaks down an endogenous inhibitor of NOS, asymmetric dimethylarginine (ADMA), by metabolizing it to L-citrulline and dimethylamine. DDAH was shown to modulate key fibrotic signalling cascades, and inhibition of this enzyme attenuated many features of the disease in in vivo experiments, suggesting a possible new therapeutic strategy for the treatment of patients suffering from IPF. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
    The Journal of Pathology 10/2012; · 7.59 Impact Factor
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    Thorax 10/2012; 67(11):938-40. · 8.38 Impact Factor

Publication Stats

3k Citations
836.68 Total Impact Points


  • 1994–2014
    • Justus-Liebig-Universität Gießen
      • • Department of Internal Medicine
      • • Faculty of Medicine
      Gieben, Hesse, Germany
  • 2010–2012
    • Hannover Medical School
      • Clinic for Pneumology
      Hanover, Lower Saxony, Germany
    • University of California, San Diego
      San Diego, California, United States
  • 2008–2011
    • Universitätsklinikum Gießen und Marburg
      • Klinik für Medizinische Virologie
      Marburg, Hesse, Germany
    • Ruhr-Universität Bochum
      Bochum, North Rhine-Westphalia, Germany
  • 2004
    • Martin Luther University of Halle-Wittenberg
      • Poliklinik für Herz- und Thoraxchirurgie
      Halle, Saxony-Anhalt, Germany