Tobias Welte

Vasorelaxant effect of glucagon-like peptide-(7-36) amide and amylin on the pulmonary circulation of the rat

The gastrointestinal peptides glucagon-like peptide-1(7-36)amide (GLP-1) and amylin are currently being tested in clinical trials for the treatment of diabetes mellitus due to their effects in lowering blood glucose. Receptors for these polypeptides also exist in the lung and since polypeptides are known to modulate airway and pulmonary vascular tone, we investigated whether GLP-1 and amylin act similarly in the lung. We compared their effects with the well-known actions of calcitonin gene-related peptide (CGRP) and vasoactive intestinal peptide (VIP). Both GLP-1 and amylin induced a dose-dependent and time-reversible endothelial-dependent relaxation of preconstricted pulmonary artery rings. Amylin was approximately as strong as VIP and CGRP, GLP-1 however, was 2.3-fold less potent. GLP-1 as well as amylin also reduced the vascular tone in the isolated, perfused and ventilated rat lung. In contrast to their action on the pulmonary vasculature, neither GLP-1 nor amylin showed any effect on the tone of isolated preconstricted trachea rings. In conclusion, GLP-1 and amylin represent two additional peptides which may modulate pulmonary vascular tone.

Pivotal Role of Cathepsin K in Lung Fibrosis

The paramount importance of the homeostasis of the extracellular matrix for pulmonary function is exemplified by two opposing extremes: emphysema and pulmonary fibrosis. This study examined the putative role of cathepsin K (catK) in the pathology of lung fibrosis in mice and its relevance to the human disease activity. We compared the induction of lung fibrosis by administration of bleomycin. CTSK(-/-) mice deposited significantly more extracellular matrix than control mice. Primary lung fibroblasts derived from CTSK(-/-) mice showed a decreased collagenolytic activity indicating the role of catK in collagen degradation. Interestingly, CTSK(+/+) control mice revealed an increased expression of catK in fibrotic lung regions suggesting a protective role of catK to counter the excessive deposition of collagen matrix in the diseased lung. Similarly, in lung specimens obtained from patients with lung fibrosis fibroblasts expressed larger amounts of catK than those obtained from normal lungs. Activation of human pulmonary fibroblasts in primary cell cultures led to an increased activity of catK through enhanced gene transcription and protein expression and to increased intracellular collagenolytic activity. We believe that this is the first study to show that catK plays a pivotal role in lung matrix homeostasis under physiological and pathological conditions.

CATHEPSIN K EXPRESSION IN HUMAN LUNG

Tissue remodeling is crucial in different lung diseases, in the embryonal development as well as in bronchial carcinoma. Cathepsins were proposed to be involved in the degradation of matrix proteins. Cathepsin K is one of the most potent matrix-degrading cysteine proteinases known as yet. The elastinolytic and collagenolytic activity of this papain-like protease is comparable with that of neutrophil elastase. We have investigated the cathepsin K expression in normal adult lung tissues, in embryonal lung tissue and in bronchial carcinoma. With help of specific anti-cathepsin K antibodies it could be shown that cathepsin K was expressed in bronchial epithelial cells. These data could be confirmed at mRNA level using a quantitative RT-PCR as well as by visualisation of the specific enzymatic activity in epithelial cell lines. During the embryonal development cathepsin K was expressed in the epithelial cells of the developing bronchi. The expression seemed to be upregulated in parallel with the development of the bronchial and alveolar lumen. In the later phase of lung development the cathepsin K expression was restricted to bronchial epithelial cells. Furthermore, using quantitative RT-PCR it could be shown that cathepsin K-mRNA was upregulated in lung tumor tissues in comparison to normal tissues from the same patients. These data suggest that cathepsin K may play an important role in matrix remodeling of the lung under physiological and pathological conditions.

Review: Novel Cysteine Proteases of the Papain Family

The papain family of cysteine proteases, by far the largest among cysteine proteases, comprises enzymes from bacteria, plants, invertebrates, and vertebrates It includes the lysosomal cathepsins B, C, H, L, and S, as well as the more recently described cathepsins F, K, O, V, W, and X The term “cathepsin” stands for “lysosomal proteolytic enzyme, regardless of the enzyme class Therefore, in addition to cysteine proteases, this term includes serine proteases (cathepsms A and G), and aspartic proteases (cathepsins D and E) as well Sequence homologies of cathepsins B, C, H, L, and S indicate that these enzymes diverged early during eukaryotic evolution (Berti and Storer 1994) Some of the genes encoding novel enzymes, however, may be the result of relatively recent gene duplication events, as suggested by three gene pairs with common chromosomal localization and high sequence homologies (Fig 1) Mammalian cysteine proteases of the papain family have been implicated in general protein degradation and turnover within the endosomal/lysosomal system (Kirschke and Barrett 1987), as well as in

Evidence of a defective thiol status of alveolar macrophages from COPD patients and smokers

In increasing numbers of pulmonary diseases an association with a loss of intracellular thiols, mainly glutathione, is postulated. Therefore, the quantitative measurement of thiols within different viable cells is a possible metabolic parameter for cellular function and defense capacity of all pulmonary immune cells including alveolar macrophages (AM), that are highly compromised by oxidative stress. In this study the cellular thiol content was determined using fluorochrom conjugated chloromethyl derivatives (5-chloromethylfluorescein diacetate, CMFDA) in flow cytometry. The procedure was evaluated in vitro using biochemical techniques for glutathione quantification. Based on this approach, AM obtained from bronchoalveolar lavage (BAL) of smokers and patients with chronic obstructive pulmonary disease (COPD) showed a significant thiol deficiency compared to a nonsmoker/non-COPD group. The cellular thiol expression of AM from smokers and COPD patients reached only 50 and 53% of the control group. Lowest thiol concentrations (47% of control) were detected within the smoker(+)/COPD(+) group. This intracellular thiol deficiency significantly correlated with reduced lung function (FEV(1), PaO(2)). With regard to the tightly regulated thiol metabolism of immune cells, these results imply the onset of functional disturbances in thiol deficient AM. The determination of the cellular thiol content of AM, obtained from BAL by flow cytometry, presents a simple and reliable tool to monitor the effect of therapeutic measures focusing on the stabilization of the cellular thiol status.

Expression of cathepsins B, H, K, L, and S during human fetal lung development.

Cathepsins are involved in lysosomal protein degradation, proenzyme activation, antigen processing, and hormone maturation. They are secreted by tumor cells and macrophages and catalyze the remodeling of extracellular matrix proteins. To gain insight into the expression pattern of cathepsins during fetal lung development, the expression of cathepsins B, H, K, L, and S at protein and mRNA levels were evaluated by using immunohistochemistry and in situ hybridization. Early expression of cathepsins B, H, and K was found in epithelial cells of the branching presumptive bronchi (<12th week of gestation). The most intense cathepsin K–specific immunoreactivity was found in developing airways with a lumen. Cathepsin K was found in epithelial cells only, whereas in contrast, cathepsins B and H were detected both in epithelial and interstitial cells. During fetal maturation, interstitial cells displayed cathepsin L immunoreactivity and, in the saccular phase (>26th week of gestation), both cathepsin L and S immunoreactivities. A continuous decline in the proportion of cathepsin H‐positive interstitial CD68‐positive cells was observed. These discrete temporal and spatial variations in cathepsin expression during organogenesis of the human lung indicate different physiological roles for the individual enzymes in different cell types and developmental stages.

Expression of Cathepsins B and L in Human Lung Epithelial Cells is Regulated by Cytokines

The cathepsins B, L, and H are expressed ubiquitously and represent the major proportion of lysosomal enzymes. They are involved in bulk proteolysis in the lysosomes, processing of proteins and matrix degradation. Under pathological conditions the participation of cathepsins, especially their secreted forms, was observed in inflammation, tumor progression and metastasis. The enzymatic activity of cathepsins is regulated by posttranslational modification, localization, maturation, changes in pH, and their interaction with inhibitors. Regulation at the level of transcription is not well elucidated. The aim of this study was to investigate the effect of IL-1 beta, IL-6, IL-10, TGF-beta 1, and HGF on mRNA expression and protein level in human lung epithelial cell lines A-549 and BEAS-2B. IL-6 leads to a twofold increase in cathepsin L mRNA expression, whereas TGF-beta 1 decreases the amount of cathepsin L mRNA. At protein level, using enzyme immunoassay, it was shown that IL-6 induced increased amounts of cathepsin L but not cathepsin B. In contrast, after incubation of bronchial epithelial cells with TGF-beta 1 the cathepsin L concentration was decreased. In conclusion, gene expression of cathepsins B and L is variable. The cytokines IL-6 and TGF-beta 1 modulate cathepsin gene expression.

MRP8/MRP14, CD11b and HLA-DR expression of alveolar macrophages in pneumonia

Activation of alveolar macrophages is characterised by specific alterations to the expression pattern of surface markers under certain pathological conditions. MRP8/MRP14 and CD11b are involved in the regulation of macrophage migration and adhesion. HLA-DR regulates the antigen presentation by alveolar macrophages. The aim of this study was to investigate the phenotype of alveolar macrophages in pneumonia particularly in relationship to the changes in concentrations of TGF-beta1 and IL-8. Using cytofluorimetry, we analysed the surface expression of MRP8/MRP14, CD11b, and HLA-DR on alveolar macrophages of 42 pneumonia (PN) patients, 14 patients with interstitial lung diseases (ILD), five patients with chronic obstructive lung disease (COPD), and 58 patients without lung disease. Phenotypic characteristics were correlated to the concentration of TGF-beta1 and IL-8 in the bronchoalveolar lavage fluid (BALF) of the same patients. The direct influence of TGF-beta1 and IL-8 on expression of MRP8/MRP14, CD11b and HLA-DR of cultured monocytes and MonoMac cells was analysed. Significantly more MRP8/MRP14 and CD11b positive macrophages and less HLA-DR-positive macrophages were found in PN but not in ILD or COPD. The percentage of CD11b-positive macrophages correlated with the TGF-beta1 as well as the IL-8 concentrations. The amount of HLA-DR-positive macrophages correlated negatively to the concentration of TGF-beta1 and IL-8. These findings document a significant activation of alveolar macrophages during pneumonia. TGF-beta1 led to a modulation of HLA-DR and MRP8/MRP14-antigen expression in vitro. In conclusion, it was shown that in pneumonia but not in ILD or COPD alveolar macrophages were characterised by an increased MRP8/MRP14 and CD11b expression and a diminished HLA-DR expression. The characterisation of subpopulations within the alveolar macrophages may be a useful tool for the monitoring of disease progression.

Nitric oxide-dependent vasorelaxation and endothelial cell damage caused by mercury chloride

Mercury and its derivatives are known to constrict vascular smooth muscle cells. However, little is known about the role of endothelial cells in mercury-induced vasoreactivity. Using isolated, norepinephrine preconstricted rat aorta and pulmonary artery rings with intact endothelium, we demonstrate that mercury chloride (HgCl2) induces an endothelial-dependent vasorelaxation which was totally blocked by the nitric oxide inhibitor L-NAME. Besides this vasorelaxant effect, treatment with HgCl2 resulted in functional and morphological alterations of the endothelial cells. On aortic rings, endothelial cells were partly lifted from the basal membrane when incubated for 20 min in HgCl2 (10(-7) M)-containing buffer. At a concentration of 10(-6) M, the endothelial cells were completely denuded and acetylcholine vasorelaxation was abolished. Endothelial cell structure and function was preserved by incubating the vessels in HgCl2-containing rat blood instead of buffer. We conclude that HgCl2 induces an endothelial-dependent vasorelaxation and alters structure and function of vascular endothelial cells.

Kostenvergleichsanalyse der stationären und ambulanten Intervalltherapie bei erwachsenen Mukoviszidosepatienten

Zusammenfassung□ HintergrundDie stationäre Intervalltherapie (SIT) bei erwachsenen Mukoviszidosepatienten gilt als teuer. Es wird vermutet, daß eine ambulante Therapie deutlich kostengünstiger wäre. Im Rahmen einer prospektiven kontrollierten Studie zum Vergleich der SIT mit einem neuen häuslichen Therapiekonzept (HIT) hinsichtlich medizinischer, psychosozialer und ökonomischer Erfolgsparameter wurden daher auch die erbrachten Gesundheitsleistungen und Kosten unter deutschen Systembedingungen vergleichend evaluiert.□ Patienten und MethodeWährend des Studienzeitraums April 1995 bis September 1996 wurden 45 Patienten mit insgesamt 56 stationären und 40 ambulanten Therapiekursen aufgenommen. Wesentliches Instrument zur Erhebung des Ressourcenverbrauchs waren Dokumentationsbögen, die vom medizinischen Personal und den Patienten geführt wurden. Darüber hinaus wurden bei HIT Apothekenrechnungen und bei SIT Patientenakten und Daten der Finanzbuchhaltung genutzt.□ ErgebnisseDie durchschnittlichen Kosten je Therapiekurs betrugen bei der SIT 14038, — DM, bei der HIT 18702, — DM. Auffallend waren die hohen Medikationskostenunterschiede (17280, — DM bei HIT gegenüber 4847, — DM bei SIT), die in zwei Unterschieden gründen: dem Einsatz mobiler Pumpinfusionssysteme und deutlich höheren Abgabepreisen für Medikamente bei HIT, wobei Übergewinne der Befüller und/oder Apotheke zu vermuten sind. Die gesellschaftlich relevanten Kosten der HIT (unter Herausrechnung von Übergewinnen) liegen bei geschätzt unter 10500, — DM. Aus gesellschaftlicher Perspektive ist damit die ambulante Therapie kostengünstiger, aus Kassenperspektive die stationäre Therapie.□ Schlußfolgerungen1. Die weithin akzeptierte Annahme, daß die ambulante Versorgung kostengünstiger als die stationäre ist, gilt nicht durchgängig. 2. Es liegt ein Steuerungsdefekt vor, der zu unnötigen und vermeidbaren Krankenhausaufenthalten führen kann, wenn die Kassenperspektive dominiert. 3. Änderungen der Systembedingungen, wie die Zulassung von Versandapotheken, sollten ernsthaft erwogen und evaluiert werden.Abstract□ BackgroundThe regular i.v.-therapy of adults with cystic fibrosis (CF) on an in-patient basis is regarded as expensive. Home treatment is supposed to be cheaper. During a prospective controlled study to compare in-patient treatment (SIT) with home i.v.-treatment (HIT) in regard to clinical, psychosocial and economic parameters, delivered health services and costs in the German setting were evaluated in a comparatable manner.□ Patients and MethodsDuring the study period 4/95 to 9/96 45 patients with altogether 56 hospital and 40 home i.v.-courses of approximately 14 days were included in the study. Principal instruments to record the resource consumption were documentation sheets kept by the medical staff and the patients. In addition, pharmacy accounts in HIT and patient records and hospital controlling data in SIT were used.□ ResultsThe average costs of a course were 14,038 DM for HIT and 18,702 DM for SIT. Striking are the large differences in medication costs. Two main reasons could be identified for the cost difference: 1. the use of a mobile infusion system in HIT and 2. the much higher prices of pharmaceuticals in the ambulatory care sector compared to the hospital sector, where extremely high profits of the home care service firms or the pharmacy can be supposed. The social costs of HIT (when antibiotics are valued to opportunity costs) are estimated at less than 10,500 DM. From a societal perspective HIT is preferable, from the perspective of the statutory health insurance funds hospital therapy is preferable.□ Conclusions1. The widely accepted hypothesis that ambulatory care is cheaper than hospital care is — at least in the German setting — not a-priori true. 2. In the treatment of CF patients incentive failures exist which induce unnecessary and avoidable hospital stays if the perspective of the statutory sickness funds is dominant. 3. Changes in system conditions as e. g. the permission of mail-order pharmacies might help to implement a more rational allocation of resources.BACKGROUNDnThe regular i.v.-therapy of adults with cystic fibrosis (CF) on an in-patient basis is regarded as expensive. Home treatment is supposed to be cheaper. During a prospective controlled study to compare in-patient treatment (SIT) with home i.v.-treatment (HIT) in regard to clinical, psychosocial and economic parameters, delivered health services and costs in the German setting were evaluated in a comparable manner.nnnPATIENTS AND METHODSnDuring the study period 4/95 to 9/96 45 patients with altogether 56 hospital and 40 home i.v.-courses of approximately 14 days were included in the study. Principal instruments to record the resource consumption were documentation sheets kept by the medical staff and the patients. In addition, pharmacy accounts in HIT and patient records and hospital controlling data in SIT were used.nnnRESULTSnThe average costs of a course were 14,038 DM for HIT and 18,702 DM for SIT. Striking are the large differences in medication costs. Two main reasons could be identified for the cost difference: 1, the use of a mobile infusion system in HIT and 2, the much higher prices of pharmaceuticals in the ambulatory care sector compared to the hospital sector, where extremely high profits of the home care service firms or the pharmacy can be supposed. The social costs of HIT (when antibiotics are valued to opportunity costs) are estimated at less than 10,500 DM. From a societal perspective HIT is preferable, from the perspective of the statutory health insurance funds hospital therapy is preferable.nnnCONCLUSIONSn1. The widely accepted hypothesis that ambulatory care is cheaper than hospital care is--at least in the German setting--not a-priori true. 2. In the treatment of CF patients incentive failures exist which induce unnecessary and avoidable hospital stays if the perspective of the statutory sickness funds is dominant. 3. Changes in system conditions as e.g. the permission of mail-order pharmacies might help to implement a more rational allocation of resources.