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BackgroundWhole body ischemia-reperfusion injury (IRI) after cardiopulmonary resuscitation (CPR) induces a generalized inflammatory response which contributes to the development of post-cardiac arrest syndrome (PCAS). Recently, pattern recognition receptors (PRRs), such as toll-like receptors (TLRs) and inflammasomes, have been shown to mediate the inflammatory response in IRI. In this study we investigated monocyte PRR signaling and function in PCAS.MethodsBlood samples were drawn in the first 12 hours, and at 24 and 48 hours following return of spontaneous circulation in 51 survivors after cardiac arrest. Monocyte mRNA levels of TLR2, TLR4, interleukin-1 receptor-associated kinase (IRAK)3, IRAK4, NLR family pyrin domain containing (NLRP)1, NLRP3, AIM2, PYCARD, CASP1, and IL1B were determined by real-time quantitative PCR. Ex vivo cytokine production in response to stimulation with TLR ligands Pam3CSK4 and lipopolysaccharide (LPS) was assessed in both whole blood and monocyte culture assays. Ex vivo cytokine production of peripheral blood mononuclear cells (PBMCs) from a healthy volunteer in response to stimulation with patients’ sera with or without LPS was assessed. The results were compared to 19 hemodynamically stable patients with coronary artery disease.ResultsMonocyte TLR2, TLR4, IRAK3, IRAK4, NLRP3, PYCARD and IL1B were initially upregulated in patients following cardiac arrest. The NLRP1 and AIM2 inflammasomes were downregulated in resuscitated patients. There was a significant positive correlation between TLR2, TLR4, IRAK3 and IRAK4 expression and the degree of ischemia as assessed by serum lactate levels and the time until return of spontaneous circulation. Nonsurvivors at 30 days had significantly lower mRNA levels of TLR2, IRAK3, IRAK4, NLRP3 and CASP1 in the late phase following cardiac arrest. We observed reduced proinflammatory cytokine release in response to both TLR2 and TLR4 activation in whole blood and monocyte culture assays in patients after CPR. Sera from resuscitated patients attenuated the inflammatory response in cultured PBMCs after co-stimulation with LPS.ConclusionsSuccessful resuscitation from cardiac arrest results in changes in monocyte pattern recognition receptor signaling pathways, which may contribute to the post-cardiac arrest syndrome.Trial registrationThe trial was registered in the German Clinical Trials Register (DRKS00009684) on 27/11/2015.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-016-1340-3) contains supplementary material, which is available to authorized users.

IntroductionIschemia and reperfusion after cardiopulmonary resuscitation (CPR) induce endothelial activation and systemic inflammatory response, resulting in post-resuscitation disease. In this study we analyzed direct markers of endothelial injury, circulating endothelial cells (CECs) and endothelial microparticles (EMPs), and endothelial progenitor cells (EPCs) as a marker of endothelial repair in patients after CPR.MethodsFirst we investigated endothelial injury in 40 patients after CPR, 30 controls with stable coronary artery disease (CAD), and 9 healthy subjects, who were included to measure CECs and EMPs. In a subsequent study, endothelial repair was assessed by EPC measurement in 15 CPR, 9 CAD, and 5 healthy subjects. Blood samples were drawn immediately and 24 hours after ROSC and analyzed by flow cytometry. For all statistical analyses P < 0.05 was considered significant.ResultsThere was a massive rise in CEC count in resuscitated patients compared to CAD (4,494.1 ± 1,246 versus 312.7 ± 41 cells/mL; P < 0.001) and healthy patients (47.5 ± 3.7 cells/mL; P < 0.0005). Patients after prolonged CPR (≥30 min) showed elevated CECs compared to those resuscitated for <30 min (6,216.6 ± 2,057 versus 2,340.9 ± 703.5 cells/mL; P = 0.13/ns). There was a significant positive correlation of CEC count with duration of CPR (R2= 0.84; P < 0.01). EMPs were higher immediately after CPR compared to controls (31.2 ± 5.8 versus 19.7 ± 2.4 events/μL; P = 0.12 (CAD); versus 15.0 ± 5.2 events/μL; P = 0.07 (healthy)) but did not reach significance until 24 hours after CPR (69.1 ± 12.4 versus 22.0 ± 3.0 events/μL; P < 0.005 (CAD); versus 15.4 ± 4.4 events/μL; P < 0.001 (healthy)). EPCs were significantly elevated in patients on the second day after CPR compared to CAD (1.16 ± 0.41 versus 0.02 ± 0.01% of lymphocytes; P < 0.005) and healthy (0.04 ± 0.01; P < 0.005).ConclusionsIn the present study we provide evidence for a severe endothelial damage after successful CPR. Our results point to an ongoing process of endothelial injury, paralleled by a subsequent endothelial regeneration 24 hours after resuscitation.

Background Typical lung ultrasound (LUS) findings in patients with a COVID-19 infection were reported early on. During the global SARS-CoV-2 pandemic, LUS was propagated as a useful instrument in triage and monitoring. We evaluated LUS as a rapid diagnostic triage tool for the management of patients with suspected COVID-19 in the emergency department (ED). Methods The study retrospectively enrolled patients with suspected COVID-19, who were admitted from 1st April to 25th of April 2020 to the ED of a tertiary care center in Germany. During clinical work-up, patients underwent LUS and polymerase chain reaction (PCR) testing for SARS-CoV-2. The recorded ultrasound findings were analyzed and judged regarding typical signs of viral pneumonia, blinded for clinical information of the patients. The results were compared with PCR test and chest computed tomography (CT). Results 2236 patients were treated in the ED during the study period. 203 were tested for SARS-CoV-2 using PCR, 135 (66.5%) underwent LUS and 39 (28.9%) of the patients were examined by chest CT scan. 39 (28.9%) of the 135 patients were tested positive for SARS-CoV-2 with PCR. In 52 (38.5%) COVID-19 was suspected from the finding of the LUS, resulting in a sensitivity of 76.9% and a specificity of 77.1% compared with PCR results. The negative predictive value reached 89.2%. The findings of the LUS had - compared to a positive chest CT scan for COVID-19 - a sensitivity of 70.6% and a specificity of 72.7%. Conclusions LUS is a rapid and useful triage tool in the work-up of patients with suspected COVID-19 infection during a pandemic scenario. Still, the results of the LUS depend on the physician’s experience and skills.

The endothelium serves as a selective barrier and controls the exchange of nutrients, hormones, and leukocytes between blood and tissues. Molecular mechanisms contributing to the pathogenesis of endothelial barrier dysfunction remain incompletely understood. Accumulating evidence implicates bone morphogenetic protein (BMP)-modulator BMPER as a key regulator in endothelial biology. Herein, we analyze the impact of BMPER in the control of endothelial barrier function. To assess the role of BMPER in vascular barrier function in mice, we measured the leakage of Evans blue dye from blood into interstitial lung tissue. BMPER mice exhibited a significantly higher degree of vascular leak compared with wild-type siblings. In accordance with our in vivo observation, siRNA-based BMPER knockdown in human umbilical endothelial cells increased endothelial permeability measured by FITC-dextran passage in transwell assays. Mechanistically, BMPER knockdown reduced the expression of VE-cadherin, a pivotal component of endothelial adherens junctions. Conversely, recombinant human BMPER protein upregulated VE-cadherin protein levels and improved endothelial barrier function in transwell assays. The effects of BMPER knockdown on VE-cadherin expression and endothelial permeability were induced by enhanced BMP activity. Supporting this notion, activation of BMP4-Smad-Id1 signaling reduced VE-cadherin levels and impaired endothelial barrier function in vitro. In vivo, Evans blue dye accumulation was higher in the lungs of BMP4-treated C57BL/6 mice compared to controls indicating that BMP4 increased vascular permeability. High levels of BMPER antagonized BMP4-Smad5-Id1 signaling and prevented BMP4-induced downregulation of VE-cadherin and endothelial leakage, suggesting that BMPER exerts anti-BMP effects and restores endothelial barrier function. Taken together, this data demonstrates that BMPER-modulated BMP pathway activity regulates VE-cadherin expression and vascular barrier function.