Christian M. Kähler

Peripheral infusion of rat bone marrow derived endothelial progenitor cells leads to homing in acute lung injury

BackgroundBone marrow-derived progenitors for both epithelial and endothelial cells have been observed in the lung. Besides mature endothelial cells (EC) that compose the adult vasculature, endothelial progenitor cells (EPC) are supposed to be released from the bone marrow into the peripheral blood after stimulation by distinct inflammatory injuries. Homing of ex vivo generated bone marrow-derived EPC into the injured lung has not been investigated so far. We therefore tested the hypothesis whether homing of EPC in damaged lung tissue occurs after intravenous administration.MethodsEx vivo generated, characterized and cultivated rat bone marrow-derived EPC were investigated for proliferation and vasculogenic properties in vitro. EPC were tested for their homing in a left-sided rat lung transplant model mimicking a severe acute lung injury. EPC were transplanted into the host animal by peripheral administration into the femoral vein (106 cells). Rats were sacrificed 1, 4 or 9 days after lung transplantation and homing of EPC was evaluated by fluorescence microscopy. EPC were tested further for their involvement in vasculogenesis processes occurring in subcutaneously applied Matrigel in transplanted animals.ResultsWe demonstrate the integration of intravenously injected EPC into the tissue of the transplanted left lung suffering from acute lung injury. EPC were localized in vessel walls as well as in destructed lung tissue. Virtually no cells were found in the right lung or in other organs. However, few EPC were found in subcutaneous Matrigel in transplanted rats.ConclusionTransplanted EPC may play an important role in reestablishing the endothelial integrity in vessels after severe injury or at inflamatory sites and might further contribute to vascular repair or wound healing processes in severely damaged tissue. Therapeutic applications of EPC transplantation may ensue.

Endothelial progenitor cells: current issues on characterization and challenging clinical applications.

Since their discovery about a decade ago, endothelial precursor cells (EPC) have been subjected to intensive investigation. The vision to stimulate respectively suppress a key player of vasculogenesis opened a plethora of clinical applications. However, as research opened deeper insights into EPC biology, the enthusiasm of the pioneer era has been damped in favour of a more critical view. Recent research is focused on three major questions: The fact that the number of EPC in peripheral blood is exceedingly low has consistently raised suspicion whether these cells can plausibly have an impact on physiological or pathophysiological processes. Secondly, whereas the key role of EPC in tumourigenesis has been strongly emphasized by various groups in the past, recent publications are challenging this hypothesis. Thirdly, the lack of consensus on EPC-defining markers and standardized protocols for their detection have repeatedly led to difficulties concerning comparability between papers. In this current review, an overview on recent findings on EPC biology is given, their challenging clinical implications are discussed and the perplexity underlying the current controversial debate is illustrated.

Successful switch from inhalative iloprost to oral bosentan in portopulmonary hypertension associated with liver cirrhosis

SummaryPortopulmonary hypertension (PPHTN) is a rare complication of liver cirrhosis. Prostanoids have been shown to be effective in the treatment of PPHTN and have been used as a bridge to orthotopic liver transplantation. However, inhibition of platelet aggregation might be a limitation of prostacyclin therapy in patients with end-stage liver disease having an increased risk of bleeding from esophageal varices. The effect of oral bosentan, a dual endothelin-receptor antagonist in the reversal of PPHTN, is still unclear. We report a case of PPHTN (mean pulmonary artery pressure [mPAP] of 51xa0mm Hg) that was successfully switched from inhalative iloprost to oral bosentan therapy. Hemodynamic and symptomatic improvements were maintained after a 12-month long-term treatment with inhalative iloprost as well as after single oral bosentan therapy. This is the first reported case of a successful switch from therapy with an inhalative prostacyclin analogue to oral bosentan in a patient suffering from PPHTN. Thus, oral bosentan therapy might be a promising new option for patients suffering from PPHTN.

Effects of the neuropeptide secretoneurin on natural killer cell migration and cytokine release

Secretoneurin has a widespread occurrence in airway mucosal innervation of patients with allergic diseases and may play an important role in the local traffic of immune cells in human airway mucosa. Whether secretoneurin affects natural killer cell migration and cytokine release in vitro was tested. Natural killer cells were obtained from venous blood of healthy donors. Cell migration was studied by micropore filter assays. Signalling mechanisms required for secretoneurin-dependent migration were tested using signalling enzyme blockers. Cytokine release was measured in natural killer cell supernatants by ELISA. Secretoneurin significantly stimulated natural killer cell chemotaxis via activation of phosphatidylinositol 3-kinase and protein kinase C. IL-2 stimulated natural killer cells showed a stronger response toward secretoneurin than unstimulated cells. Moreover, secretoneurin increased the release of interleukin-5 in a dose-dependent manner but did not affect Th1 cytokine release by natural killer cells. Data suggest that secretoneurin stimulates directed migration of natural killer cells and may modulate Th1/Th2-response via affecting chemokine release. Thus, secretoneurin may play an important role in the early stages of allergic inflammation.

Quantification of recent smoking behaviour using proton transfer reaction-mass spectrometry (PTR-MS)

Sirs, responding to the paper of Lirk et al. first of all we want to underline that it would be helpful to have different meaningful criteria – also biomarkers – for diagnosis of smoking behaviour [1]. In fact the biomarker acetonitril may have the advantage that it is relatively long-lived and takes approximately one week to return to the baseline found in non-smokers. Nevertheless there are many questions occurring when reading the study of Lirk et al.:

Subcutaneous implantation of a new intravenous pump system for prostacyclin treatment in patients with pulmonary arterial hypertension

BACKGROUNDnIntravenous prostacyclin treatment is a well recognized option in patients suffering from pulmonary arterial hypertension (PAH), and remains the gold standard of treatment. However, intravenous prostacyclin treatment involves several limitations, because the available battery-driven pump systems carry the risk of line infections, catheter-related embolisms, thrombosis, and delivery system malfunctions.nnnCASE REPORTnWe report for the first time, to the best of our knowledge, on the safe transition procedure from subcutaneous to intravenous treprostinil in a 74-year-old woman suffering from severe PAH (New York Heart Association functional class III), using a new implantable, gas-driven, intravenous pump device (LenusPro, Tricumed/OMT, Frittlingen, Germany).nnnCONCLUSIONSnThis implantable pump system may overcome the well-known limitations and risks of commonly used delivery systems, and thus may provide a new option for continuous intravenous prostacyclin treatment in patients with PAH.

Quantification of recent smoking behaviour using proton transfer reaction-mass spectrometry (PTR-MS)@@@Quantifizierung des rezenten Raucher-Verhaltens durch Protonen Transfer Reaktions-Massenspektrometrie (PTR-MS)

ZusammenfassungHeutzutage gilt Rauchen als der wichtigste medizinische Risikofaktor. Die Überwachung einer Exposition gegenüber Tabakrauch kann im Prinzip mittels Umluftmessungen, oder direkt mit Hilfe von Biomarkern erfolgen. Acetonitrile wurde als ein potentieller Marker für das rezente Raucherverhalten beschrieben. Es war daher das Ziel vorliegender Studie, die in der Ausatemluft festgestellten Acetonitrile-Konzentrationen in einem Kollektiv von 268 Personen (48 Raucher, 220 Nichtraucher) festzustellen.Atemgasproben wurden in inerten Sammelgefäßen gesammelt, und die Konzentration von Acetonitrile in der Umluft während der Abnahmen wurde parallel erhoben. Die Analyse der Umluft- und Atemluftproben erfolgte mittels Protonen Transfer Reaktions-Massenspektrometrie (PTR-MS).Raucher zeigten in der Ausatemluft signifikant erhöhte Acetonitrilekonzentrationen im Vergleich zu Nichtrauchern (p<0,001). Die Erstellung einer receiver-operating-characteristic curve ergab für die Unterscheidung von Rauchern und Nichtrauchern mittels PTR-MS eine Sensitivität von 79% und eine Spezifität von 91% bei einem Schwellenwert von 20.31 parts per billion.Diese erste Feldstudie zum Thema Acetonitrile in einem großen Testkollektiv konnte die Praktikabilität dieses Markers als schnellen und nichtinvasiven Test rezenten Raucherverhaltens nachweisen. Wir schlussfolgern, dass die Analyse der Atemgaskonzentration von Acetonitrile Rückschlüsse auf das aktive Raucherverhalten ziehen lässt.SummarySmoking is the most important single risk factor in current public health. Surveillance of exposure to tobacco smoke may be accomplished using environmental monitoring or in-vivo tests for smoking biomarkers. Acetonitrile exhaled in human breath has been described as a potential marker mirroring recent smoking behavior. The aim of this study was to determine exhaled acetonitrile levels in a sample of 268 volunteers (48 smokers, 220 non-smokers) attending a local health fair.Breath specimens were collected into inert sample bags, with parallel collection of ambient air. Subsequently, all samples were analysed using proton transfer reaction-mass spectrometry (PTR-MS).Smokers had elevated levels of exhaled acetonitrile compared with non-smokers (p<0.001). Analysis using the receiver-operating-characteristic curve demonstrated that smoking can be predicted with a sensitivity of 79% and a specificity of 91%, using a cut-off concentration of 20.31 parts per billion of acetonitrile.This first field survey of exhaled acetonitrile in a large group of test persons demonstrates the feasibility of a rapid and non-invasive test for recent exposure to tobacco. We conclude that analysis of exhaled-breath acetonitrile may serve as a method of determining recent active smoking behaviour.

Sensory neuropeptides are potent chemoattractants for human basophils in vitro

The sensory neuropeptides secretoneurin (SN) and substance P (SP) are involved in neurogenic inflammatory processes as they occur in bronchial asthma or allergic rhinitis. A possible interaction with basophils has not been reported to date. Basophils were isolated from healthy donors by magnetic cell sorting technique and migration was explored using Boyden microchemotaxis chambers. SN [10(-8)M] and SP [10(-6) to 10(-8)M] proved to be chemoattractants equally potent to FMLP [10(-8)M] or LPS [10 pg/ml]. Specific anti-SN antibodies and a trypsinization preparation of SN were used to determine the specificity of the SN effect on basophils. The preincubation of basophils with neurokinin-1 (NK-1) or -2 (NK-2) receptor antagonists revealed the SP effect to act via NK-1 receptors in basophils. In addition, we were able to show phosphodiesterases and phosphoinositide-3 kinases to be engaged in the downstream signalling pathway. Our observations reveal for the first time a link between basophils, which are engaged in allergic processes, and the neuropeptides SN and SP. Furthermore, our data might suggest phosphodiesterases or phosphoinositide-3 kinases to be new therapeutic targets for the treatment of allergic diseases such as asthma or allergic rhinitis.

Diagnostic and therapeutic challenges of a large pleural inflammatory myofibroblastic tumor.

We report a 48-year-old woman with a pleural pseudoneoplasm requiring different diagnostic and therapeutic strategies. After initial presentation with increasing dyspnoea, temperature, dry cough, and interscapular pain diagnostic processing showed a large mediastinal mass with marked pleural effusion and high metabolic activity in the 18F-FDG-PET/CT. Extensive CT-guided biopsy of the tumor reaching from the visceral pleura into the right upper lobe revealed no malignancy, but a marked inflammatory tissue reaction containing foam cells. Initial empiric antibiotic therapy was temporarily successful. However, in the further course the mass relapsed and was resistant to antibiotics and a corticosteroid trial. With the working hypothesis of an inflammatory myofibroblastic tumor the patient underwent surgical tumor resection, finally confirming the suspected diagnosis. Due to residual disease intravenous immunoglobulins were administered leading to sustained response. This case with a pleural localisation of a large inflammatory pseudotumor with responsiveness to immunomodulation after incomplete resection extends the reported spectrum of thoracopulmonary manifestations of this rare entity.

Successful treatment of portopulmonary hypertension with the selective endothelin receptor antagonist Sitaxentan

ZusammenfassungDie portopulmonale Hypertonie ist eine seltene Erkrankung, die durch das Vorhandensein eines erhöhten mittleren pulmonalarteriellen Druckes und dem gleichzeitigen Vorliegen einer portalen Hypertonie gekennzeichnet ist. Eine schwere portopulmonale Hypertonie gilt als Kontraindikation zur Durchführung einer Lebertransplantation. Zahlreiche Medikamente wie Prostazyklindrivate, Phosphodiesteraseinhibitoren wie auch duale Endothelinrezeptorantagonisten wurden in einzelnen Patienten versuchsweise eingesetzt. Die Wirkung eines selektiven Endothelinrezptorantagonisten wie Sitaxentan in diesem Kontext war bisher unbekannt. Wir berichten hier über die erfolgreiche Therapie mit oralem Sitaxentan über einen Zeitraum von drei Monaten, wobei sich sowohl die Leistungsfähigkeit wie auch die pulmonale Hämodynamik verbesserten. Zusätzlich kam es zu einer Verbesserung der portalen Hypertonie durch eine signifikanten Reduktion des Lebervenendruckes von 12 auf 8 mmHg. Der Einsatz selektiver Endothelinrezeptorantagonisten könnte somit eine neue Therapieoption für diese Patienten darstellen.SummaryPortopulmonary hypertension (POPH) is a rare complication of portal hypertension. Prostanoids have been shown to be effective in the treatment of POPH and have been used as a bridge to liver transplantation. More recently, case series revealed beneficial effects of both the dual endothelin receptor antagonist bosentan and the phosphodiesterase-5 inhibitor sildenafil. The efficacy of sitaxentan, a selective endothelin receptor A (ERA) antagonist in the reversal of POPH, is still unclear. We report a case of POPH that was successfully treated with oral sitaxentan. Haemodynamic and symptomatic improvements were maintained after a 12-week long-term treatment period. Additionally, hepatic vein pressure gradient significantly decreased from 12 mmHg to 8 mm after treatment with sitaxentan. This is the first reported case of a successful therapy with a selective ERA antagonist in a patient suffering from POPH. Oral sitaxentan therapy might be a promising new option for patients suffering from POPH.