The Proteome of Extracellular Vesicles Released from Pulmonary Microvascular Endothelium Reveals Impact of Oxygen Conditions on Biotrauma

The lung can experience different oxygen concentrations, low as in hypoxia, high as under supplemental oxygen therapy, or oscillating during intermittent hypoxia as in obstructive sleep apnea or intermittent hypoxia/hyperoxia due to cyclic atelectasis in the ventilated patient. This study aimed to characterize the oxygen-condition-specific protein composition of extracellular vesicles (EVs) released from human pulmonary microvascular endothelial cells in vitro to decipher their potential role in biotrauma using quantitative proteomics with bioinformatic evaluation, transmission electron microscopy, flow cytometry, and non-activated thromboelastometry (NATEM). The release of vesicles enriched in markers CD9/CD63/CD81 was enhanced under intermittent hypoxia, strong hyperoxia and intermittent hypoxia/hyperoxia. Particles with exposed phosphatidylserine were increased under intermittent hypoxia. A small portion of vesicles were tissue factor-positive, which was enhanced under intermittent hypoxia and intermittent hypoxia/hyperoxia. EVs from treatment with intermittent hypoxia induced a significant reduction of Clotting Time in NATEM analysis compared to EVs isolated after normoxic exposure, while after intermittent hypoxia/hyperoxia, tissue factor in EVs seems to be inactive. Gene set enrichment analysis of differentially expressed genes revealed that EVs from individual oxygen conditions potentially induce different biological processes such as an inflammatory response under strong hyperoxia and intermittent hypoxia/hyperoxia and enhancement of tumor invasiveness under intermittent hypoxia.

Profiling endogenous adrenal function during veno-venous ECMO support in COVID-19 ARDS: a descriptive analysis

Background

Prolonged critical illness is often accompanied by an impairment of adrenal function, which has been frequently related to conditions complicating patient management. The presumed connection between hypoxia and the pathogenesis of this critical- illness- related corticosteroid insufficiency (CIRCI) might play an important role in patients with severe acute respiratory distress syndrome (ARDS). Since extracorporeal membrane oxygenation (ECMO) is frequently used in ARDS, but data on CIRCI during this condition are scarce, this study reports the behaviour of adrenal function parameters during oxygenation support with veno-venous (vv)ECMO in coronavirus disease 2019 (COVID-19) ARDS.

Methods

A total of 11 patients undergoing vvECMO due to COVID-19 ARDS at the Medical University of Vienna, who received no concurrent corticosteroid therapy, were retrospectively included in this study. We analysed the concentrations of cortisol, aldosterone, and angiotensin (Ang) metabolites (Ang I-IV, Ang 1-7, and Ang 1-5) in serum via liquid chromatography/tandem mass spectrometry before, after 1 day, 1 week, and 2 weeks during vvECMO support and conducted correlation analyses between cortisol and parameters of disease severity.

Results

Cortisol concentrations appeared to be lowest after initiation of ECMO and progressively increased throughout the study period. Higher concentrations were related to disease severity and correlated markedly with interleukin-6, procalcitonin, pH, base excess, and albumin during the first day of ECMO. Fair correlations during the first day could be observed with calcium, duration of critical illness, and ECMO gas flow. Angiotensin metabolite concentrations were available in a subset of patients and indicated a more homogenous aldosterone response to plasma renin activity after 1 week of ECMO support.

Conclusion

Oxygenation support through vvECMO may lead to a partial recovery of adrenal function over time. In homogenous patient collectives, this novel approach might help to further determine the importance of adrenal stress response in ECMO and the influence of oxygenation support on CIRCI.

Combined angiotensin-converting enzyme and aminopeptidase inhibition for treatment of experimental ventilator-induced lung injury in mice

Introduction: Ventilator-induced lung injury (VILI) may aggravate critical illness. Although angiotensin-converting enzyme (ACE) inhibition has beneficial effects in ventilator-induced lung injury, its clinical application is impeded by concomitant hypotension. We hypothesized that the aminopeptidase inhibitor ALT-00 may oppose the hypotension induced by an angiotensin-converting enzyme inhibitor, and that this combination would activate the alternative renin-angiotensin system (RAS) axis to counteract ventilator-induced lung injury. Methods: In separate experiments, C57BL/6 mice were mechanically ventilated with low (LVT, 6 mL/kg) and high tidal volumes (HVT, 30 mL/kg) for 4 h or remained unventilated (sham). High tidal volume-ventilated mice were treated with lisinopril (0.15 μg/kg/min) ± ALT-00 at 2.7, 10 or 100 μg/kg/min. Blood pressure was recorded at baseline and after 4 h. Lung histology was evaluated for ventilator-induced lung injury and the angiotensin (Ang) metabolite profile in plasma (equilibrium levels of Ang I, Ang II, Ang III, Ang IV, Ang 1-7, and Ang 1-5) was measured with liquid chromatography tandem mass spectrometry at the end of the experiment. Angiotensin concentration-based markers for renin, angiotensin-converting enzyme and alternative renin-angiotensin system activities were calculated. Results: High tidal volume-ventilated mice treated with lisinopril showed a significant drop in the mean arterial pressure at 4 h compared to baseline, which was prevented by adding ALT-00 at 10 and 100 μg/kg/min. Ang I, Ang II and Ang 1-7 plasma equilibrium levels were elevated in the high tidal volumes group versus the sham group. Lisinopril reduced Ang II and slightly increased Ang I and Ang 1-7 levels versus the untreated high tidal volumes group. Adding ALT-00 at 10 and 100 μg/kg/min increased Ang I and Ang 1-7 levels versus the high tidal volume group, and partly prevented the downregulation of Ang II levels caused by lisinopril. The histological lung injury score was higher in the high tidal volume group versus the sham and low tidal volume groups, and was attenuated by lisinopril ± ALT-00 at all dose levels. Conclusion: Combined angiotensin-converting enzyme plus aminopeptidase inhibition prevented systemic hypotension and maintained the protective effect of lisinopril. In this study, a combination of lisinopril and ALT-00 at 10 μg/kg/min appeared to be the optimal approach, which may represent a promising strategy to counteract ventilator-induced lung injury that merits further exploration.

Usefulness and limitations of the acute respiratory distress syndrome definitions in non-intubated patients. A narrative review

According to the Berlin Definition of acute respiratory distress syndrome (ARDS), a positive end-expiratory pressure (PEEP) of at least 5 cmH₂O is required to diagnose and grade ARDS. While the Berlin consensus statement specifically acknowledges the role of non-invasive ventilation (NIV) in mild ARDS, this stratification has traditionally presumed a mechanically ventilated patient in the context of moderate to severe ARDS. This may not accurately reflect today's reality of clinical respiratory care. NIV and high-flow nasal cannula oxygen therapy (HFNO) have been used for managing of severe forms of acute hypoxemic respiratory failure with growing frequency, including in patients showing pathophysiological signs of ARDS. This became especially relevant during the COVID-19 pandemic. The levels of PEEP achieved with HFNO have been particularly controversial, and the exact FiO₂ it achieves is subject to variability. Pinpointing the presence of ARDS in patients receiving HNFO and the severity in those receiving NIV therefore remains methodically problematic. This narrative review highlights the evolution of the ARDS definition in the context of non-invasive ventilatory support and provides an overview of the parallel development of definitions and ventilatory management of ARDS. It summarizes the methodology applied in clinical trials to classify ARDS in non-intubated patients and the respective consequences on treatment. As ARDS severity has significant therapeutic and prognostic consequences, and earlier treatment in non-intubated patients may be beneficial, closing this knowledge gap may ultimately be a relevant step to improve comparability in clinical trial design and outcomes.

Practice of oxygen use in anesthesiology – a survey of the European Society of Anaesthesiology and Intensive Care

Background

Oxygen is one of the most commonly used drugs by anesthesiologists. The World Health Organization (WHO) gave recommendations regarding perioperative oxygen administration, but the practice of oxygen use in anesthesia, critical emergency, and intensive care medicine remains unclear.

Methods

We conducted an online survey among members of the European Society of Anaesthesiology and Intensive Care (ESAIC). The questionnaire consisted of 46 queries appraising the perioperative period, emergency medicine and in the intensive care, knowledge about current recommendations by the WHO, oxygen toxicity, and devices for supplemental oxygen therapy.

Results

Seven hundred ninety-eight ESAIC members (2.1% of all ESAIC members) completed the survey. Most respondents were board-certified and worked in hospitals with > 500 beds. The majority affirmed that they do not use specific protocols for oxygen administration. WHO recommendations are unknown to 42% of respondents, known but not followed by 14%, and known and followed by 24% of them. Respondents prefer inspiratory oxygen fraction (FiO₂) ≥80% during induction and emergence from anesthesia, but intraoperatively < 60% for maintenance, and higher FiO₂ in patients with diseased than non-diseased lungs. Postoperative oxygen therapy is prescribed more commonly according to peripheral oxygen saturation (SpO₂), but shortage of devices still limits monitoring. When monitoring is used, SpO₂ ≤ 95% is often targeted. In critical emergency medicine, oxygen is used frequently in patients aged ≥80 years, or presenting with respiratory distress, chronic obstructive pulmonary disease, myocardial infarction, and stroke. In the intensive care unit, oxygen is mostly targeted at 96%, especially in patients with pulmonary diseases.

Conclusions

The current practice of perioperative oxygen therapy among respondents does not follow WHO recommendations or current evidence, and access to postoperative monitoring devices impairs the individualization of oxygen therapy. Further research and additional teaching about use of oxygen are necessary.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01884-2.

The Renin-Angiotensin System as a Component of Biotrauma in Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a major concern in critical care medicine with a high mortality of over 30%. Injury to the lungs is caused not only by underlying pathological conditions such as pneumonia, sepsis, or trauma, but also by ventilator-induced lung injury (VILI) resulting from high positive pressure levels and a high inspiratory oxygen fraction. Apart from mechanical factors that stress the lungs with a specific physical power and cause volutrauma and barotrauma, it is increasingly recognized that lung injury is further aggravated by biological mediators. The COVID-19 pandemic has led to increased interest in the role of the renin-angiotensin system (RAS) in the context of ARDS, as the RAS enzyme angiotensin-converting enzyme 2 serves as the primary cell entry receptor for severe acute respiratory syndrome (SARS) coronavirus (CoV)-2. Even before this pandemic, studies have documented the involvement of the RAS in VILI and its dysregulation in clinical ARDS. In recent years, analytical tools for RAS investigation have made major advances based on the optimized precision and detail of mass spectrometry. Given that many clinical trials with pharmacological interventions in ARDS were negative, RAS-modifying drugs may represent an interesting starting point for novel therapeutic approaches. Results from animal models have highlighted the potential of RAS-modifying drugs to prevent VILI or treat ARDS. While these drugs have beneficial pulmonary effects, the best targets and application forms for intervention still have to be determined to avoid negative effects on the circulation in clinical settings.

Understanding Cellular Redox Homeostasis: A Challenge for Precision Medicine

Living organisms use a large repertoire of anabolic and catabolic reactions to maintain their physiological body functions, many of which include oxidation and reduction of substrates. The scientific field of redox biology tries to understand how redox homeostasis is regulated and maintained and which mechanisms are derailed in diverse pathological developments of diseases, where oxidative or reductive stress is an issue. The term “oxidative stress” is defined as an imbalance between the generation of oxidants and the local antioxidative defense. Key mediators of oxidative stress are reactive species derived from oxygen, nitrogen, and sulfur that are signal factors at physiological concentrations but can damage cellular macromolecules when they accumulate. However, therapeutical targeting of oxidative stress in disease has proven more difficult than previously expected. Major reasons for this are the very delicate cellular redox systems that differ in the subcellular compartments with regard to their concentrations and depending on the physiological or pathological status of cells and organelles (i.e., circadian rhythm, cell cycle, metabolic need, disease stadium). As reactive species are used as signaling molecules, non-targeted broad-spectrum antioxidants in many cases will fail their therapeutic aim. Precision medicine is called to remedy the situation.

Safety and preliminary efficacy of sequential multiple ascending doses of solnatide to treat pulmonary permeability edema in patients with moderate-to-severe ARDS-a randomized, placebo-controlled, double-blind trial

Background

Acute respiratory distress syndrome (ARDS) is a complex clinical diagnosis with various possible etiologies. One common feature, however, is pulmonary permeability edema, which leads to an increased alveolar diffusion pathway and, subsequently, impaired oxygenation and decarboxylation. A novel inhaled peptide agent (AP301, solnatide) was shown to markedly reduce pulmonary edema in animal models of ARDS and to be safe to administer to healthy humans in a Phase I clinical trial. Here, we present the protocol for a Phase IIB clinical trial investigating the safety and possible future efficacy endpoints in ARDS patients.

Methods

This is a randomized, placebo-controlled, double-blind intervention study. Patients with moderate to severe ARDS in need of mechanical ventilation will be randomized to parallel groups receiving escalating doses of solnatide or placebo, respectively. Before advancing to a higher dose, a data safety monitoring board will investigate the data from previous patients for any indication of patient safety violations. The intervention (application of the investigational drug) takes places twice daily over the course of 7 days, ensued by a follow-up period of another 21 days.

Discussion

The patients to be included in this trial will be severely sick and in need of mechanical ventilation. The amount of data to be collected upon screening and during the course of the intervention phase is substantial and the potential timeframe for inclusion of any given patient is short. However, when prepared properly, adherence to this protocol will make for the acquisition of reliable data. Particular diligence needs to be exercised with respect to informed consent, because eligible patients will most likely be comatose and/or deeply sedated at the time of inclusion.

Trial registration

This trial was prospectively registered with the EU Clinical trials register (clinicaltrialsregister.eu). EudraCT Number: 2017-003855-47.

Oxygen conditions oscillating between hypoxia and hyperoxia induce different effects in the pulmonary endothelium compared to constant oxygen conditions

The pulmonary endothelium is an immediate recipient of high oxygen concentrations upon oxygen therapy and mediates down-stream responses. Cyclic collapse and reopening of atelectatic lung areas during mechanical ventilation with high fractions of inspired oxygen result in the propagation of oxygen oscillations in the hypoxic/hyperoxic range. We used primary murine lung endothelial cell cultures to investigate cell responses to constant and oscillating oxygen conditions in the hypoxic to hyperoxic range. Severe constant hyperoxia had pro-inflammatory and cytotoxic effects including an increase in expression of ICAM1, E-selectin, and RAGE at 24 hr exposure. The coagulative/fibrinolytic system responded by upregulation of uPA, tPA, and vWF and PAI1 under constant severe hyperoxia. Among antioxidant enzymes, the upregulation of SOD2, TXN1, TXNRD3, GPX1, and Gstp1 at 24 hr, but downregulation of SOD3 at 72 hr constant hyperoxia was evident. Hypoxic/hyperoxic oscillating oxygen conditions induced pro-inflammatory cytokine release to a lesser extent and later than constant hyperoxia. Gene expression analyses showed upregulation of NFKB p65 mRNA at 72 hr. More evident was a biphasic response of NOS3 and ACE1 gene expression (downregulation until 24 hr and upregulation at 72 hr). ACE2 mRNA was upregulated until 72 hr, but shedding of the mature protein from the cell surface favored ACE1. Oscillations resulted in severe production of peroxynitrite, but apart from upregulation of Gstp1 at 24 hr responses of antioxidative proteins were less pronounced than under constant hyperoxia. Oscillating oxygen in the hypoxic/hyperoxic range has a characteristical impact on vasoactive mediators like NOS3 and on the activation of the renin-angiotensin system in the lung endothelium.

Geochemistry and Microtextures of Vein Calcites Pervading the Izu-Bonin Forearc and Rear Arc Crust: New Insights From IODP Expeditions 352 and 351

International Ocean Discovery Program Expeditions 352 and 351 drilled into the Western Pacific Izu-Bonin forearc and rear arc. The drill cores revealed that the forearc is composed of forearc basalts (FAB) and boninites and the rear arc consists of FAB-like rocks. These rocks are pervaded by calcite veins. Blocky vein microtextures enclosing host rock fragments dominate in all locations and suggest hydrofracturing and advective fluid flow. Significant diffusion-fed and crystallization pressure-driven antitaxial veining is restricted to the rear arc. The lack of faults and presence of an Eocene sedimentary cover in the rear arc facilitated antitaxial veining. Rare earth element and isotopic (δ18O, δ13C, 87Sr/86Sr, and Δ47) tracers indicate varying parental fluid compositions ranging from pristine to variably modified seawater. The most pristine seawater signatures are recorded by FAB-hosted low-T (<30 °C) vein calcites. Their 87Sr/86Sr ratios intersect the 87Sr/86Sr seawater curve at ~35-33 and ~22 Ma. These intersections are interpreted as precipitation ages, which concur with Pacific slab rollback. Boninite-hosted low-T (<30 °C) vein calcites precipitated from seawater that was modified by fluid-rock interactions. Mixing calculations yield a mixture of >95% seawater and <5% basaltic 87Sr/86Sr. In the rear arc, low-T rock alteration lowered the circulating seawater in δ18O and 87Sr/86Sr. Thus, vein calcites precipitated from modified seawater with up to 20-30% basaltic 87Sr/86Sr at temperatures up to 74 ± 12 °C. These results show how the local geology and vein growth dynamics affect microtextures and geochemical compositions of vein precipitates.

Geochemistry of Vein Calcites Hosted in the Troodos Pillow Lavas and Their Implications for the Timing and Physicochemical Environment of Fracturing, Fluid Circulation, and Vein Mineral Growth

Calcite veins hosted in pillow lavas of the Late Cretaceous Troodos suprasubduction zone ophiolite provide insights into the timing and physicochemical environment of postmagmatic fracturing and fluid circulation through oceanic crust. This study presents rare earth element and yttrium (REE+Y) concentrations, δ13C, δ18O, 87Sr/86Sr, and clumped isotopic (Δ47) compositions of vein calcites in order to investigate their fluid sources, formation temperatures, and precipitation ages. These geochemical data are combined with microtextural analyses. Intersections of 87Sr/86Sr ratios of vein calcites with the Sr isotope seawater curve suggest two distinct calcite veining phases. Major calcite veining within an interval of ~10 Myr after crust formation is characterized by microtextures that point to extensional fracturing related to crack and sealing, host rock brecciation, and advective fluid flow. These vein calcites show REE+Y characteristics, 87Sr/86Sr ratios, and clumped isotopic compositions indicative of precipitation from seawater at <50 °C. Extended fluid residence times intensified fluid-rock interactions and lowered Y/Ho ratios of some blocky vein calcites, whereas crack and sealing resulted in pristine seawater signatures. Low 87Sr/86Sr ratios of localized high-temperature blocky vein calcites point to the involvement of hydrothermal fluids. These calcites show Mn-controlled oscillatory growth zonations that probably developed in a closed system out of equilibrium. Later calcite veining (<75 Ma) may have coincided with rotation and/or uplift of the Troodos ophiolite. Microtextures of these vein calcites indicate fluid diffusion and fracture-independent crystallization pressure-driven veining. Their variably modified seawater signatures resulted from diffusion-related fluid interaction with hydrothermal sediments.

Postmagmatic Tectonic Evolution of the Outer Izu-Bonin Forearc Revealed by Sediment Basin Structure and Vein Microstructure Analysis: Implications for a 15 Ma Hiatus Between Pacific Plate Subduction Initiation and Forearc Extension

International Ocean Discovery Program Expedition 352 recovered sedimentary-volcaniclastic successions and extensional structures (faults and extensional veins) that allow the reconstruction of the Izu-Bonin forearc tectonic evolution using a combination of shipboard core data, seismic reflection images, and calcite vein microstructure analysis. The oldest recorded biostratigraphic ages within fault-bounded sedimentary basins (Late Eocene to Early Oligocene) imply a ~15 Ma hiatus between the formation of the igneous basement (52 to 50 Ma) and the onset of sedimentation. At the upslope sites (U1439 and U1442) extension led to the formation of asymmetric basins reflecting regional stretch of ~16-19% at strain rates of ~1.58 × 10-16 to 4.62 × 10-16 s-1. Downslope Site U1440 (closer to the trench) is characterized by a symmetric graben bounded by conjugate normal faults reflecting regional stretch of ~55% at strain rates of 4.40 × 10-16 to 1.43 × 10-15 s-1. Mean differential stresses are in the range of ~70-90 MPa. We infer that upper plate extension was triggered by incipient Pacific Plate rollback ~15 Ma after subduction initiation. Extension was accommodated by normal faulting with syntectonic sedimentation during Late Eocene to Early Oligocene times. Backarc extension was assisted by magmatism with related Shikoku and Parece-Vela Basin spreading at ~25 Ma, so that parts of the arc and rear arc, and the West Philippine backarc Basin were dismembered from the forearc. This was followed by slow-rift to postrift sedimentation during the transition from forearc to arc rifting to spreading within the Shikoku-Parece-Vela Basin system.

Prevalence and short-term changes of cognitive dysfunction in young ischaemic stroke patients

BACKGROUND AND PURPOSE

Information on the prevalence and course of post-stroke cognitive impairment in young stroke patients is limited. The aim was to assess a consecutive sample of acute young ischaemic stroke patients (18-55 years) for the presence and development of neuropsychological deficits.

METHODS

Patients prospectively underwent a comprehensive clinical and cognitive assessment, examining general cognitive function, processing speed, attention, flexibility/executive function and word fluency within the first 3 weeks after hospital admission (median assessment at day 6) and at a 3 months' follow-up (FU). Cognitive dysfunction was defined in comparison to age-standardized published norms.

RESULTS

At baseline (N = 114), deficits were highly prevalent in processing speed (56.0%), flexibility/executive function (49.5%), attention (46.4%) and general cognitive function (42.1%). These frequencies were comparable for those with FU assessment (N = 87). In most domains, cognitive performance improved within 3 months, except for word fluency. However, in about one-third of patients, cognitive deficits (as defined by 1.5 standard deviations below the standardized mean) were still present 3 months after stroke. At FU, 44.0% were impaired in the domain flexibility/executive function, 35.0% in processing speed and 30.0% in attention.

CONCLUSIONS

The high prevalence of cognitive deficits in acute young patients with ischaemic stroke highlights the importance of early post-stroke cognitive assessment to capture a patient's dysfunction in a comprehensive manner and to offer adequate rehabilitation. The role of factors which promote neuropsychological deficits needs further exploration.

Treatment of primary graft dysfunction after lung transplantation with orally inhaled AP301: A prospective, randomized pilot study

BACKGROUND

Primary graft dysfunction (PGD) after lung transplantation (LTx) carries significant morbidity and mortality in the early post-operative period and is associated with the development of chronic lung allograft dysfunction. AP301, an activator of epithelial sodium channel-mediated Na+ uptake represents a new concept for prevention and treatment of pulmonary edema and has shown promising results in the pre-clinical setting. This pilot study investigated the clinical effect of inhaled AP301 on patients with development of PGD > 1 according to International Society of Heart and Lung Transplantation criteria after primary LTx in a high-volume center and was conducted as a randomized, placebo-controlled, single-center pilot-study including 20 patients. All consecutive patients fulfilling inclusion criteria were screened for PGD at arrival on the intensive care unit (ICU) after LTx. After randomization, inhaled AP301 or placebo was administered by nebulizer twice daily for 7 days or until extubation. Otherwise, patients were treated according to routine clinical protocol. Partial pressure of arterial oxygen (Pao2)/fraction of inspired oxygen (Fio2) values were obtained until extubation and assessed as a primary outcome parameter. Patients were monitored for 30 days within the study protocol.

RESULTS

From July 2013 to August 2014, 20 patients were randomized 1:1 to AP301 (Group 1) or placebo (Group 2). Both groups were comparable with regard to sex (40% women/60% men vs 50% women/50% men), mean age (55 ± 13 vs 54 ± 6 years), comorbidities, and diagnosis leading to LTx. The Pao2/Fio2 ratio at the time of inclusion was comparable in both groups, with a mean 235.65 ± 90.78 vs 214.2 ± 95.84 (p = 0.405), and there was no significant difference in the extravascular lung water index (13.88 ± 5.28 vs 16 ± 6.29 ml/kg, p = 0.476). The primary end point was mean Pao2/Fio2 ratio values between baseline and Day 3. In the AP301 group, only 1 patient was ventilated at Day 4 and no patients were ventilated after Day 4. In the placebo group, 5 patients were ventilated on Day 4 and 2 patients on Days 5, 6, and 7. The mean increase in the Pao2/Fio2 ratio was significantly higher in Group 1 patients, and the mean between baseline and at 72 hours was 365.6 ± 90.4 in Group 1 vs 335.2 ± 42.3 in Group 2 (p = 0.049). The duration of intubation was shorter in Group 1 than in Group 2 patients (2 ± 0.82 vs 3.7 ± 1.95 days; p = 0.02). ICU stay was 7.5 ± 3.13 days in Group 1 vs 10.8 ± 8.65 days in group 2 (p = 0.57). Survival at 30 days was 100%. No severe adverse events were recorded.

CONCLUSIONS

This study was designed as a proof-of-concept pilot study. Although it was not powered to achieve statistical significances, the study demonstrated relevant clinical effects of inhaled AP301 on patients with PGD after primary LTx. The improved gas exchange led to a significantly shorter duration of mechanical ventilation and a trend towards a shorter ICU stay. Further investigation of AP301 for treatment of PGD in larger studies is warranted.

TRIAL REGISTRATION

The trial is registered at https://www.clinicaltrialsregister.eu/ctr-search/trial/2013-000716-21/AT.

Inhaled AP301 for treatment of pulmonary edema in mechanically ventilated patients with acute respiratory distress syndrome: a phase IIa randomized placebo-controlled trial

Background

High-permeability pulmonary edema is a hallmark of acute respiratory distress syndrome (ARDS) and is frequently accompanied by impaired alveolar fluid clearance (AFC). AP301 enhances AFC by activating epithelial sodium channels (ENaCs) on alveolar epithelial cells, and we investigated its effect on extravascular lung water index (EVLWI) in mechanically ventilated patients with ARDS.

Methods

Forty adult mechanically ventilated patients with ARDS were included in a randomized, double-blind, placebo-controlled trial for proof of concept. Patients were treated with inhaled AP301 (n = 20) or placebo (0.9% NaCl; n = 20) twice daily for 7 days. EVLWI was measured by thermodilution (PiCCO®), and treatment groups were compared using the nonparametric Mann–Whitney U test.

Results

AP301 inhalation was well tolerated. No differences in mean baseline-adjusted change in EVLWI from screening to day 7 were found between the AP301 and placebo group (p = 0.196). There was no difference in the PaO₂/FiO₂ ratio, ventilation pressures, Murray lung injury score, or 28-day mortality between the treatment groups. An exploratory subgroup analysis according to severity of illness showed reductions in EVLWI (p = 0.04) and ventilation pressures (p < 0.05) over 7 days in patients with initial sequential organ failure assessment (SOFA) scores ≥11 inhaling AP301 versus placebo, but not in patients with SOFA scores ≤10.

Conclusions

There was no difference in mean baseline-adjusted EVLWI between the AP301 and placebo group. An exploratory post-hoc subgroup analysis indicated reduced EVLWI in patients with SOFA scores ≥11 receiving AP301. These results suggest further confirmation in future clinical trials of inhaled AP301 for treatment of pulmonary edema in patients with ARDS.

Trial registration

The study was prospectively registered at clinicaltrials.gov, NCT01627613. Registered 20 June 2012.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1795-x) contains supplementary material, which is available to authorized users.

Effects of azithromycin and tanomastat on experimental bronchiolitis obliterans

OBJECTIVE

Azithromycin has become a standard of care in therapy of bronchiolitis obliterans following lung transplantation. Matrix metalloprotease-9 broncho-alveolar lavage levels increase in airway neutrophilia and bronchiolitis obliterans. Interleukin-17 may play a role in lung allograft rejection, and interleukin-12 is downregulated in bronchiolitis obliterans. Whether these mechanisms can be targeted by azithromycin remains unclear.

METHODS

Bronchiolitis obliterans was induced by transplantation of Fischer F344 rat left lungs to Wistar Kyoto rats. Allografts with azithromycin therapy from day 1 to 28 or 56 and mono- or combination therapy with the broad-spectrum matrix metalloprotease inhibitor tanomastat from day 1 to 56 were compared to control allografts and isografts. Graft histology was assessed, and tissue cytokine expression studied using Western blotting and immunofluorescence.

RESULTS

The chronic airway rejection score in the azithromycin group did not change between 4 and 8 weeks after transplantation, whereas it significantly worsened in control allografts (P = .041). Azithromycin+tanomastat prevented complete allograft fibrosis, which occurred in 40% of control allografts. Azithromycin reduced interleukin-17 expression (P = .049) and the number of IL-17(+)/CD8(+) lymphocytes at 4 weeks, and active matrix metalloprotease-9 at 8 weeks (P = .017), and increased interleukin-12 expression (P = .025) at 8 weeks following transplantation versus control allografts.

CONCLUSIONS

The expression of interleukin-17 and matrix metalloprotease-9 in bronchiolitis obliterans may be attenuated by azithromycin, and the decrease in interleukin-12 expression was prevented by azithromycin. Combination of azithromycin with a matrix metalloprotease inhibitor is worth studying further because it prevented complete allograft fibrosis in this study.

Persistent plasminogen activator inhibitor 1 gene expression in cardiac transplant recipients with idiopathic dilated cardiomyopathy

OBJECTIVES

Plasminogen activator inhibitor 1 is the primary regulator of urokinase plasminogen activator and tissue plasminogen activator. Plasminogen activator inhibitor 1 is essential in the control of the thrombotic/fibrinolytic balance and is a marker of endothelial cell injury. Idiopathic dilated cardiomyopathy is reportedly associated with endothelial cell dysfunction. Whether endothelial cell damage plays a role in patients with dilated cardiomyopathy after cardiac transplantation remains unknown.

METHODS

In this study explanted hearts of cardiac transplant recipients with ischemic cardiomyopathy and dilated cardiomyopathy, as well as control myocardial tissue, were investigated for expression of urokinase plasminogen activator, tissue plasminogen activator, urokinase plasminogen activator receptor, and plasminogen activator inhibitor 1 and 2. Furthermore, plasminogen activator inhibitor 1 expression was examined in endomyocardial biopsy specimens and sera of patients with ischemic cardiomyopathy and those with dilated cardiomyopathy during the first posttransplantation year. The effect of the patient's serum on endothelial cells was assessed in vitro to examine the role of circulating endothelial cell damage-related factors.

RESULTS

Plasminogen activator inhibitor 1 expression was upregulated in ischemic cardiomyopathy and dilated cardiomyopathy myocardial tissue versus that seen in control tissue. After transplantation, plasminogen activator inhibitor 1 expression returned to control levels in patients with ischemic cardiomyopathy. In patients with dilated cardiomyopathy, plasminogen activator inhibitor 1 expression increased at 24 weeks after transplantation in both biopsy specimens and sera versus that seen in control tissue. Sera of patients with dilated cardiomyopathy, but not that of patients with ischemic cardiomyopathy, inhibited vascular endothelial growth factor A-induced proliferation of endothelial cells, although downstream target gene activation of early growth response factor 1 and NGFI-A binding protein 2 was not affected.

CONCLUSIONS

These data suggest for the first time that the endothelial cell damage-related process recurs in patients with dilated cardiomyopathy after transplantation, which, independently of vascular endothelial growth factor, is associated with increased plasminogen activator inhibitor 1 expression, and that this pathology might play a role in allograft remodeling in patients with dilated cardiomyopathy.

Serum matrix metalloprotease-1 and vascular endothelial growth factor--a predict cardiac allograft rejection

Cardiac allograft rejection is currently diagnosed from endomyocardial biopsies (EMB) that are invasive and impractical to repeat. A serological marker could facilitate rejection monitoring and minimize EMB-associated risks. We investigated the relation of serum matrix metalloprotease (MMP)-1 and vascular endothelial growth factor (VEGF)-A concentrations to cardiac allograft rejection, using 1176 EMBs and serum samples obtained from 208 recipients. Acute cellular rejection was diagnosed in 186 EMBs. Mean week 1 and week 2 serum MMP-1 concentrations predicted rejection (p = 0.001, AUC = 0.80). At the optimal cut-off level of >or=7.5 ng/mL, MMP-1 predicted rejection with 82% sensitivity and 72% specificity. Initial serum MMP-1 <5.3 ng/mL (lowest quartile) was associated with rejection-free outcome in 80% of patients. Both MMP-1 (p < 0.001, AUC = 0.67-0.75) and VEGF-A (p < 0.01, AUC = 0.62-0.67) predicted rejection on the next EMB, while rejection at EMB was identified only by VEGF-A (p < 0.02, AUC = 0.70-0.77). Patients receiving combined cyclosporine-A and everolimus had the lowest serum MMP-1 concentrations. While serum MMP-1 predicts rejection-free outcome and VEGF-A identifies rejection on EMB, both markers predict rejection in follow-up of cardiac transplant recipients. Combination of serum MMP-1 and VEGF-A concentration may be a noninvasive prognostic marker of cardiac allograft rejection, and could have important implications for choice of surveillance and immunosuppression protocols.

Donor myocardial HIF-1alpha is an independent predictor of cardiac allograft dysfunction: a 7-year prospective, exploratory study

Knowledge on interplay between the cardiac molecular response to transplantation-induced stress and primary graft dysfunction (PGD) is limited. A cDNA array identified HIF-1, EGR-1, NAB-2, VEGF-A and uPA as mediators of cardiac tissue response to transplantation-induced stress. mRNA expression of these molecules was measured in left ventricular biopsies from 200 donors before and after aortic cross-clamping and at 10-, 30- and 60-min reperfusion by real-time RT-PCR. HIF-1alpha expression at two time points was significantly associated with PGD, as shown by univariate analysis, receiver operating characteristic curve and multivariate logistic regression. At a cut-off level of 200 arbitrary units, HIF-1alpha after aortic cross-clamping in donors (78% sensitivity, 83% specificity) and at 10-min reperfusion (85% sensitivity, 83% specificity) identified PGD. HIF-1alpha demonstrates the potential to be a predictive marker for PGD; however, as multiple factors were tested at different time points, prospective evaluation is clearly necessary to confirm this observation.

Matrix metalloproteases and their tissue inhibitor in cardiac transplantation☆☆☆

OBJECTIVE

Multiple studies have shown that matrix metalloproteases (MMPs) are involved in the pathologic reactions occurring as a consequence of cardiac transplantation, including ischemia-reperfusion injury and allograft rejection. This study sought to determine the temporal profile of MMP serum levels following cardiac transplantation.

METHODS

Endomyocardial biopsies and serum samples were obtained from 66 recipients at 1, 2, 3, 4, 7, 12, 24, and 52 weeks post-transplant during the routine follow-up protocol, and MMP-1, MMP-8, MMP-9, and tissue inhibitor of metalloproteases (TIMP)-1 serum concentrations were measured by enzyme-linked immunosorbent assay (ELISA). Immunosuppression comprised cyclosporine A (CyA; n=46) or tacrolimus (TAC; n=20) with mycophenolate mofetil and steroids.

RESULTS

Increased MMP-8, MMP-9, and TIMP-1 serum levels were observed during the first 2 weeks following transplantation compared to the later time points. MMP-1 was increased at 2 and 3 weeks post-transplant compared to all later time points. No correlation of MMP or TIMP serum concentrations with infection episodes was observed.

CONCLUSIONS

Early increase in MMP and TIMP serum levels following cardiac transplantation indicates involvement of these molecules in the reaction of the transplant to ischemia-reperfusion or early immunologic adaptation processes of the host. Further investigation of the relationship between MMP and TIMP serum levels and clinical conditions following transplantation including allograft rejection and hemodynamic graft function is necessary.

Vascular endothelial growth factor increases pulmonary vascular permeability in cystic fibrosis patients undergoing lung transplantation☆☆☆

OBJECTIVE

Vascular endothelial growth factor (VEGF) is the prime regulator of angiogenesis and vascular permeability and its serum levels increase in cystic fibrosis (CF). The mechanisms of VEGF overproduction and its impact on CF lung pathology and pulmonary vascular permeability during lung transplantation are not fully understood.

METHODS

The expression of VEGF, its receptors, hypoxia inducible factor (HIF)-1alpha, beta, angiopoietins, and endothelial cell marker CD31 were studied in lung biopsies of CF and COPD patients and controls, using real time reverse transcription (RT)-PCR and Western blotting. DNA binding activity of HIF-1 to VEGF-A promoter was assessed by electrophoretic mobility shift assay (EMSA) and wet-to-dry lung weight ratios as well as microvascular density (MVD) were determined. Serum VEGF-A concentrations in enzyme-linked immunosorbent assay (ELISA) and wet-to-dry weight ratios of donor lungs were monitored during transplantation in CF and COPD patients. Primary graft dysfunction (PGD) was diagnosed and graded according to the guidelines of the International Society for Heart and Lung Transplantation.

RESULTS

VEGF-A165 and Flt-1 mRNA expression (P<0.05), VEGF-A (P<0.05), and HIF-1alpha (P<0.05) protein levels, DNA binding activity of HIF-1 to VEGF promoter (P<0.001) and extravascular lung water content (P<0.05) were increased in CF lungs versus controls, whereas MVD was unchanged. Before and during lung transplantation, VEGF-A serum concentrations were higher in CF versus COPD patients (P<0.05) and 60 min following reperfusion donor lungs transplanted to CF patients had higher tissue water contents than in COPD patients (P<0.05). PGD grade 3 occurred more frequently in CF (22.7%) versus COPD patients (4%). PGD grade 3 patients had significantly higher VEGF serum concentrations versus PGD grade 0-2 patients (P<0.001).

CONCLUSIONS

These data indicate that upregulated VEGF-A levels are most likely induced by enhanced HIF-1 binding to VEGF-A promoter, possibly contributing to elevated serum VEGF-A levels in CF. Furthermore, CF patients undergoing lung transplantation are possibly more susceptible to PGD because of increased VEGF-A expression that mediates increased lung graft vascular permeability.

Recipient vascular endothelial growth factor serum levels predict primary lung graft dysfunction

Primary graft dysfunction (PGD) is a severe complication in lung transplantation. Therapeutic strategies are limited and there exist no predictive markers for PGD. To investigate whether vascular endothelial growth factor (VEGF) that regulates vascular permeability could predict PGD, pretransplant VEGF serum concentrations were measured in 150 lung transplant patients and 12 controls by ELISA. PGD was scored from 0 to 3 using chest radiographs and PaO(2)/FiO(2) ratios according to the International Society for Heart and Lung Transplantation guidelines. The mean graft ischemia time was 5 h 47 min and the donors' PaO(2)/FiO(2) ratios were >300. PGD grades 0-3 occurred in 23%, 44%, 21%, and 11% of patients, respectively. Pre-operative VEGF serum concentrations were significantly higher in PGD grade 3 (p < 0.0001) versus grade 0-2 and controls. VEGF concentrations significantly predicted PGD grade 3 versus 0-2 in logistic regression analysis (p < 0.0001) and receiver operating analysis (AUC = 0.778). At a cut-off level of > or =650 pg/mL VEGF had 86% sensitivity and 62% specificity to identify PGD grade 3 versus 0-2. Pre-operative VEGF serum concentrations could identify lung transplant recipients with high PGD risk.

Differential role of TGF-beta1/bFGF and ET-1 in graft fibrosis in heart failure patients

Collagen overproduction characteristic for dilated cardiomyopathy (DCM) is coregulated by endothelin (ET)-1, transforming growth factor (TGF)-beta1, basic fibroblast growth factor (bFGF) and matrix metalloproteases (MMPs). Whether these molecules affect grafts transplanted to heart failure patients is unknown. In 67 idiopathic DCM patients, 31 patients with ischemic cardiomyopathy (ICM) and 16 controls, the myocardial bFGF, TGF-beta1, pro-collagen (PrCol) type 1 (PrCol1-alpha1, -alpha2) and MMP expressions were examined using real-time RT-PCR or Western blotting. mRNA expression was measured in grafts for 1 year. TGF-beta1/bFGF stimulation or gene silencing was used to examine their effect on collagen synthesis in cardiac tissue cultures. TGF-beta1 and PrCol1 were upregulated in DCM only, while bFGF was upregulated in both groups versus controls. TGF-beta1 downregulated MMP-1 and upregulated collagen 1, whereas bFGF upregulated MMP-13 in DCM tissue. Post-transplant PrCol1-alpha1, -alpha2 and ET-1 mRNA increased over time in grafts of DCM patients only, while other factors returned to control baseline levels in DCM and ICM. These data indicate that cardiac transplantation corrects the dysregulated TGF/bFGF/MMP-1/MMP-13, but not the excess collagen and ET-1 synthesis in cardiac grafts transplanted to DCM patients. ET-1 might be a major pathologic trigger for graft fibrosis in DCM.

Broncho-alveolar lavage matrix metalloproteases as a sensitive measure of bronchiolitis obliterans

Bronchiolitis obliterans (BO) is a survival-limiting factor in lung transplantation. There are no common BO markers in use. Since BO is associated with extracellular matrix remodeling, we asked whether matrix metalloproteases (MMPs) and their tissue inhibitors (TIMPs) could serve as BO markers. In 72 lung transplant patients (34 BO syndrome (BOS) 0, 15 BOS 0-p, and 23 BOS 1) serum and broncho-alveolar lavage (BAL) MMP and TIMP levels were examined by ELISA. The BAL cell counts were additionally analyzed. The serum MMP-2, MMP-8, MMP-9 and TIMP-2 levels were not different in all groups. In contrast, the BAL MMP-8, -9 and TIMP-1 levels were significantly elevated in BOS 0-p (p = 0.003; p = 0.007; p = 0.0003, respectively) and BOS 1 (p = 0.003; p = 0.001; p = 0.0004, respectively) as compared to BOS 0 patients. The BAL MMP-8, -9 and TIMP-1 levels were significant predictors of BOS 0-p (p = 0.01; p = 0.01; p = 0.01, respectively) and BOS-1 (p = 0.007; p = 0.01; p = 0.006, respectively) in receiver operating characteristic analysis. Except for BAL macrophages that were significantly decreased in BOS 0-p versus BOS 0 patients; other cell counts were not different between the groups. BAL MMP-8, -9 and TIMP-1 might be useful markers to detect BO in lung transplant patients.

Upregulated hypoxia-inducible factor-1 DNA binding activity to the vascular endothelial growth factor-A promoter mediates increased vascular permeability in donor lung grafts

BACKGROUND

Transplantation-induced hypoxia results in enhanced vascular permeability and tissue vascular endothelial growth factor (VEGF) and endothelin-1 (ET-1) overexpression in donor lung grafts. Promoter studies have uncovered a hypoxia-inducible factor (HIF)-1 binding site (HBS) in 5'-flanking region of VEGF gene that regulates the hypoxia-induced expression of VEGF; and ET-1 potently stimulates VEGF-A production. We hypothesized that HIF-1 regulates VEGF-mediated vascular permeability in lung grafts.

METHODS

We studied the mRNA and protein expression of HIF-1 and its protein-binding capacity to the HBS of the VEGF gene in biopsies of preserved donor and control lungs, using real-time reverse transcription-polymerase chain reaction, Western blotting, and electrophoretic mobility shift assay. Wet-to-dry lung weight ratio was measured in donor and control lungs.

RESULTS

While HIF-1 alpha mRNA expression was unchanged, HIF-1 beta was downregulated (p < 0.05) in donor versus control lungs. Protein expression of both, HIF-1 alpha and -beta was significantly upregulated in donor lung grafts. HIF-1 binding to the HBS of the VEGF promoter as well as tissue fluid content were increased in donor lung biopsies versus controls (p < 0.05).

CONCLUSIONS

These data indicate that upregulated HIF-1 DNA binding activity to the HBS of VEGF-A most likely contributes to elevated VEGF levels in preserved lung grafts. Unchanged HIF-1 alpha mRNA expression did not affect HIF-1 alpha protein levels. Endothelin-1 increases HIF-1 alpha accumulation and activates HIF-1 transcription complex in vitro. Therefore, ET-1-mediated increased HIF-1 alpha protein stability most likely leads to transcriptional activation of VEGF during lung graft preservation. Targeting HIF might be of benefit to counteract edema formation in preserved lung grafts.