Inhibition of NF-κB-dependent cytokine and inducible nitric oxide synthesis by the macrocyclic ellagitannin oenothein B in TLR-stimulated RAW 264.7 macrophages

Immunomodulatory effects of oenothein B (1), a macrocyclic ellagitannin from various Onagraceae species, have been described previously. However, the mechanisms underlying the anti-inflammatory activity of 1 have not been fully clarified. The effects of 1 were investigated on inducible nitric oxide synthase, TLR-dependent and TLR-independent signal transduction cascades, and cytokine expression using murine macrophages (RAW 264.7). Compound 1 (10-60 μg/mL) reduced NO production, iNOS mRNA, and iNOS protein levels in a dose-dependent manner, without inhibition of iNOS enzymatic activity. It reduced the binding of the NF-κB p50 subunit to the biotinylated-consensus sequence and decreased nuclear p65 translocation. Gallic acid as a subunit of the macrocyclic ellagitannin 1 showed a far lower inhibitory activity. Nitric oxide production was reduced by 1 after stimulation using TLR2 (Pam2CSK4) and TLR4 (Kdo2) agonists, but this compound did not inhibit inducible nitric oxide synthesis after stimulation using interferon-gamma. IL-1beta, IL-6, and TNF-alpha mRNA synthesis was clearly reduced by the addition of 1. Oenothein B (1) inhibits iNOS after stimulation with LPS, TLR2, and TLR4 agonists via inhibition of TLR/NF-κB-dependent inducible nitric oxide and cytokine synthesis independent from IFN-gamma/JAK/STAT pathways. The full molecular structure of this macrocyclic ellagitannin seems to be required for its immunomodulatory actions.     

Plasma sRAGE is independently associated with increased mortality in ARDS: a meta-analysis of individual patient data

Purpose

The soluble receptor for advanced glycation end-products (sRAGE) is a marker of lung epithelial injury and alveolar fluid clearance (AFC), with promising values for assessing prognosis and lung injury severity in acute respiratory distress syndrome (ARDS). Because AFC is impaired in most patients with ARDS and is associated with higher mortality, we hypothesized that baseline plasma sRAGE would predict mortality, independently of two key mediators of ventilator-induced lung injury.

Methods

We conducted a meta-analysis of individual data from 746 patients enrolled in eight prospective randomized and observational studies in which plasma sRAGE was measured in ARDS articles published through March 2016. The primary outcome was 90-day mortality. Using multivariate and mediation analyses, we tested the association between baseline plasma sRAGE and mortality, independently of driving pressure and tidal volume.

Results

Higher baseline plasma sRAGE [odds ratio (OR) for each one-log increment, 1.18; 95% confidence interval (CI) 1.01–1.38; P?=?0.04], driving pressure (OR for each one-point increment, 1.04; 95% CI 1.02–1.07; P?=?0.002), and tidal volume (OR for each one-log increment, 1.98; 95% CI 1.07–3.64; P?=?0.03) were independently associated with higher 90-day mortality in multivariate analysis. Baseline plasma sRAGE mediated a small fraction of the effect of higher ΔP on mortality but not that of higher V_T.

Conclusions

Higher baseline plasma sRAGE was associated with higher 90-day mortality in patients with ARDS, independently of driving pressure and tidal volume, thus reinforcing the likely contribution of alveolar epithelial injury as an important prognostic factor in ARDS. Registration: PROSPERO (ID: CRD42018100241).

     

Left-Atrial Appendage Thrombosis in Patients With Severe Aortic Stenosis Undergoing Transcatheter Aortic Valve Implantation

BackgroundData about the impact of left-atrial appendage thrombosis (LAAT) on early safety and mortality in patients undergoing transfemoral transcatheter aortic valve implantation (TF-TAVI) are scarce. We aimed to investigate the prevalence and predictors of LAAT and the outcome associated with this condition in patients treated by TF-TAVI.MethodsRetrospective data analysis was derived from a prospective single-centre registry comparing patients with and without LAAT regarding early safety at 30 days, according to Valve Academic Research Consortium-2 (VARC-2) and 2-year mortality.ResultsLAAT was found in 7.6% of the whole cohort (n = 2527) and in 16.6% in those patients with known pre-existing atrial fibrillation (AF cohort, n = 1099). Compared with controls, patients with LAAT were sicker, indicated by a higher Society of Thoracic Surgeons (STS) score and burden of comorbidities. Neither VARC-2–defined early safety at 30 days nor the rate of stroke was different between LAAT and controls in both the whole (early safety: 29.2% vs 24.2%, P = 0.123; stroke: 5.9% vs 4.7%, P = 0.495) and AF cohort (early safety: 29.1% vs 22.9%, P = 0.072; stroke: 5.6% vs 3.3%, P = 0.142). Evaluating the whole cohort in a univariate analysis, the 2-year mortality was significantly higher in LAAT compared with controls (hazard ratio, 1.41; 95% confidence interval, 1.07-1.86; P = 0.014). However, multivariate analysis of the whole cohort and the AF cohort revealed no association between LAAT and 2-year mortality.ConclusionsLAAT was frequent in patients undergoing TF-TAVI— in particular, in patients with histories of AF—but it was not associated with an increase in periprocedural complications and did not predict 2-year mortality.     

Sports-Related Sudden Cardiac Arrest in Germany

BackgroundKnowledge about causes of sports-related sudden cardiac arrest (SrSCA) may influence national strategies to prevent such events. Therefore, we established a prospective registry on SrSCA to estimate the incidence and in particular describe the etiologies of SrSCA in the general population in Germany.MethodsThe registration of SrSCA based upon 4 pillars: a web-based platform to record SrSCA cases in competitive and recreational athletes, media-monitoring, cooperation with the German Resuscitation Registry, and 15 institutes of forensic medicine.ResultsAfter an observation period of 6 years, a total of 349 cases was recorded (mean age 48.0 ± 12.7 years); 109 subjects survived. Most of the cases occurred during nonelite competitive or recreational sports. Bystander cardiopulmonary resuscitation (CPR) was initiated in 262 cases (75%); however, rhythm analysis and defibrillation (if indicated) was mainly performed by medical services. In patients ≤ 35 years of age, premature coronary artery disease (CAD) and sudden arrhythmic death syndrome (SADS) prevailed, followed by myocarditis. In athletes ≥ 35 years of age, CAD predominated.ConclusionsCountry-specific registries are necessary to define the national screening and prevention strategy optimally. In Germany, premature CAD, SADS, and myocarditis are the leading causes of SrSCA in young athletes, reinforcing the great disparity of the prevalence of cardiac diseases among different countries. Extension of on-site SCD-prevention campaigns, with training of CPR and explanation of the efficient use of automated external defibrillators (AEDs), may decrease the burden of SrSCD.     

The effect of hydroxychloroquine on platelet activation in model experiments

Journal of Thrombosis and Thrombolysis - Hydroxychloroquine (HCQ) is an antimalarial agent with pleiotropic effects and now represents a cornerstone in the management of patients with autoimmune...     

Calculation of pulsatile flow and particle paths in an aneurysm-model

Summary The velocity field and the wall shear stress have been calculated numerically by the finite element method to the time-dependent Navier-Stokes equations for pulsatile flow in a model of an aneurysm. The results show a complex flow field with two eddies growing and disappearing during the cardiac cycle. Downstream at the outlet vessel high wall shear stress occurs, which may lead to a downstream-growing of the aneurysm.With the knowledge of a sufficiently accurate flow field, the calculation of several particle paths has been carried out. Starting points and starting time are varied. The paths demonstrate the time-dependent development, shift and disappearance of vortices during the pulsatile cycle and provide hints on zones of stasis. These are significant factors in thrombogenesis.Supported by the Fonds zur Förderung der wissenschaftlichen Forschung, project number P4671     

AMP-activated protein kinase regulates hERG potassium channel

Besides their role in cardiac repolarization, human ether-a-go-go-related gene potassium (hERG) channels are expressed in several tumor cells including rhabdomyosarcoma cells. The channels foster cell proliferation. Ubiquitously expressed AMP-dependent protein kinase (AMPK) is a serine-/threonine kinase, stimulating energy-generating and inhibiting energy-consuming processes thereby helping cells survive periods of energy depletion. AMPK has previously been shown to regulate Na⁺/K⁺ ATPase, Na⁺/Ca²⁺ exchangers, Ca²⁺ channels and K⁺ channels. The present study tested whether AMPK regulates hERG channel activity. Wild type AMPK (α1β1γ1), constitutively active ^γR70QAMPK (α1β1γ1(R70Q)), or catalytically inactive ^αK45RAMPK (α1(K45R)β1γ1) were expressed in Xenopus oocytes with hERG. Tail currents were determined as a measure of hERG channel activity by two-electrode-voltage clamp. hERG membrane abundance was quantified by chemiluminescence and visualized by immunocytochemistry and confocal microscopy. Moreover, hERG currents were measured in RD rhabdomyosarcoma cells after pharmacological modification of AMPK activity using the patch clamp technique. Coexpression of wild-type AMPK and of constitutively active ^γR70QAMPK significantly downregulated the tail currents in hERG-expressing Xenopus oocytes. Pharmacological activation of AMPK with AICAR or with phenformin inhibited hERG currents in Xenopus oocytes, an effect abrogated by AMPK inhibitor compound C. ^γR70QAMPK enhanced the Nedd4-2-dependent downregulation of hERG currents. Coexpression of constitutively active ^γR70QAMPK decreased membrane expression of hERG in Xenopus oocytes. Compound C significantly enhanced whereas AICAR tended to inhibit hERG currents in RD rhabdomyosarcoma cells. AMPK is a powerful regulator of hERG-mediated currents in both, Xenopus oocytes and RD rhabdomyosarcoma cells. AMPK-dependent regulation of hERG may be particularly relevant in cardiac hypertrophy and tumor growth.