Serum concentrations of levosimendan and its metabolites OR-1855 and OR-1896 in cardiac surgery patients with cardiopulmonary bypass.

Background: The inotropic drug levosimendan is often used as an individualized therapeutic approach perioperatively in cardiac surgery patients with cardiopulmonary bypass (CPB). Data regarding serum concentrations of levosimendan and its metabolites within this context is lacking. Methods: In this retrospective descriptive proof-of-concept study, total serum concentrations (TSC) and unbound fractions (UF) of levosimendan and its metabolites OR-1896 and OR-1855 in cardiac surgery patients with CPB were measured using LC-ESI-MS/MS. Simulation of expected levosimendan TSC was performed using Pharkin 4.0. Serum NT-proBNP was assessed with ELISA. Results: After levosimendan infusion (1.25 mg or 2.5 mg, respectively) after anaesthesia induction, a median TSC of 1.9 ng/ml and 10.4 ng/ml was determined in samples taken directly after surgery (T1). Median TSC of 7.6 ng/ml and 22.0 ng/ml, respectively, were simulated at T1. Whereas 1.1 ng/ml and 1.6 ng/ml TSC of OR-1896, respectively, was quantified the day after surgery (T2), TSC of the intermediate metabolite OR-1855 was mostly below the lower limit of quantification (LLOQ). The UF was 0.5% and 1.1% for levosimendan and 64.1% and 52.1% for OR-1896, respectively, with over half the samples being below LLOQ. NT-proBNP concentrations before surgery and T2 did not differ. Discussion: The low TSC, UF and unchanged NT-proBNP levels in combination with high variation of serum levels between patients suggest a need for optimized dosing regimen of levosimendan combined with therapeutic drug monitoring for such an individualized approach. In addition, the differences between the measured and estimated concentrations may suggest a possible influence of CPB on levosimendan serum concentrations.

An open-label, randomized controlled trial to assess a ketogenic diet in critically ill patients with sepsis.

Patients with sepsis experience metabolic and immunologic dysfunction that may be amplified by standard carbohydrate-based nutrition. A ketogenic diet (KD) may offer an immunologically advantageous alternative, although clinical evidence is limited. We conducted a single-center, open-label, randomized controlled trial to assess whether a KD could induce stable ketosis in critically ill patients with sepsis. Secondary outcomes included assessment of feasibility and safety of KD, as well as explorative analysis of clinical and immunological characteristics. Forty critically ill adults were randomized to either a ketogenic or standard high-carbohydrate diet. Stable ketosis was achieved in all KD patients, with significant increases in ß-hydroxybutyrate levels compared with controls [mean difference 1.4 milimoles per liter; 95% confidence interval (CI): 1.0 to 1.8; P < 0.001). No major adverse events or harmful metabolic side effects (acidosis, dysglycemia, or dyslipidemia) were observed. After day 4, none of the patients in the KD group required insulin treatment, whereas in the control group, insulin dependency ranged between 35% and 60% (P = 0.009). There were no differences in 30-day survival, but ventilation-free [incidence rate ratio (IRR) 1.7; 95% CI: 1.5 to 2.1; P < 0.001], vasopressor-free (IRR 1.7; 95% CI: 1.5 to 2.0; P < 0.001), dialysis-free (IRR 1.5; 95% CI: 1.3 to 1.8; P < 0.001), and intensive care unit-free days (IRR 1.7; 95% CI: 1.4 to 2.1; P < 0.001) were higher in the ketogenic group. Next-generation sequencing of CD4+/CD8+ T cells and protein analyses showed reduced immune dysregulation, with decreased gene expression of T-cell activation and signaling markers and lower pro-inflammatory cytokine secretion. This trial demonstrated the safe induction of a stable ketogenic state in sepsis, warranting larger trials to investigate potential benefits in sepsis-related organ dysfunction.

CD74 is a functional MIF receptor on activated CD4+ T cells.

Next to its classical role in MHC II-mediated antigen presentation, CD74 was identified as a high-affinity receptor for macrophage migration inhibitory factor (MIF), a pleiotropic cytokine and major determinant of various acute and chronic inflammatory conditions, cardiovascular diseases and cancer. Recent evidence suggests that CD74 is expressed in T cells, but the functional relevance of this observation is poorly understood. Here, we characterized the regulation of CD74 expression and that of the MIF chemokine receptors during activation of human CD4+ T cells and studied links to MIF-induced T-cell migration, function, and COVID-19 disease stage. MIF receptor profiling of resting primary human CD4+ T cells via flow cytometry revealed high surface expression of CXCR4, while CD74, CXCR2 and ACKR3/CXCR7 were not measurably expressed. However, CD4+ T cells constitutively expressed CD74 intracellularly, which upon T-cell activation was significantly upregulated, post-translationally modified by chondroitin sulfate and could be detected on the cell surface, as determined by flow cytometry, Western blot, immunohistochemistry, and re-analysis of available RNA-sequencing and proteomic data sets. Applying 3D-matrix-based live cell-imaging and receptor pathway-specific inhibitors, we determined a causal involvement of CD74 and CXCR4 in MIF-induced CD4+ T-cell migration. Mechanistically, proximity ligation assay visualized CD74/CXCR4 heterocomplexes on activated CD4+ T cells, which were significantly diminished after MIF treatment, pointing towards a MIF-mediated internalization process. Lastly, in a cohort of 30 COVID-19 patients, CD74 surface expression was found to be significantly upregulated on CD4+ and CD8+ T cells in patients with severe compared to patients with only mild disease course. Together, our study characterizes the MIF receptor network in the course of T-cell activation and reveals CD74 as a novel functional MIF receptor and MHC II-independent activation marker of primary human CD4+ T cells.

A novel OSA-related model of intermittent hypoxia in endothelial cells under flow reveals pronounced inflammatory pathway activation.

Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder characterized by recurrent episodes of upper airway obstruction and subsequent hypoxia. In patients with OSA, severity and number of these hypoxic events positively correlate with the extent of associated cardiovascular pathology. The molecular mechanisms underlying intermittent hypoxia (IH)-driven cardiovascular disease in OSA, however, remain poorly understood-partly due to the lack of adequate experimental models. Here, we present a novel experimental approach that utilizes primary human endothelial cells cultivated under shear stress. Oxygen partial pressure dynamics were adopted in our in vitro model according to the desaturation-reoxygenation patterns identified in polysomnographic data of severe OSA patients (n = 10, with 892 severe desaturations, SpO2<80%). Using western blot analysis, we detected a robust activation of the two major inflammatory pathways ERK and NF-κB in endothelial cells, whereas no HIF1α and HIF2α protein stabilization was observed. In line with these findings, mRNA and protein expression of the pro-inflammatory adhesion and signaling molecule ICAM-1 and the chemokine CCL2 were significantly increased. Hence, we established a novel in vitro model for deciphering OSA-elicited effects on the vascular endothelium. First data obtained in this model point to the endothelial activation of pro-inflammatory rather than hypoxia-associated pathways in OSA. Future studies in this model might contribute to the development of targeted strategies against OSA-induced, secondary cardiovascular disease.

A Functional Network Driven by MicroRNA-125a Regulates Monocyte Trafficking in Acute Inflammation.

During the onset of acute inflammation, rapid trafficking of leukocytes is essential to mount appropriate immune responses towards an inflammatory insult. Monocytes are especially indispensable for counteracting the inflammatory stimulus, neutralising the noxa and reconstituting tissue homeostasis. Thus, monocyte trafficking to the inflammatory sites needs to be precisely orchestrated. In this study, we identify a regulatory network driven by miR-125a that affects monocyte adhesion and chemotaxis by the direct targeting of two adhesion molecules, i.e., junction adhesion molecule A (JAM-A), junction adhesion molecule-like (JAM-L) and the chemotaxis-mediating chemokine receptor CCR2. By investigating monocytes isolated from patients undergoing cardiac surgery, we found that acute yet sterile inflammation reduces miR-125a levels, concomitantly enhancing the expression of JAM-A, JAM-L and CCR2. In contrast, TLR-4-specific stimulation with the pathogen-associated molecular pattern (PAMP) LPS, usually present within the perivascular inflamed area, resulted in dramatically induced levels of miR-125a with concomitant repression of JAM-A, JAM-L and CCR2 as early as 3.5 h. Our study identifies miR-125a as an important regulator of monocyte trafficking and shows that the phenotype of human monocytes is strongly influenced by this miRNA, depending on the type of inflammatory stimulus.

Simultaneous LC-ESI-MS/MS Quantification of Levosimendan and Its Metabolites for Therapeutic Drug Monitoring of Cardiac Surgery Patients.

Levosimendan is used in severe chronic cardiac insufficiency, also within the peri-operative setting. Real-life pharmacokinetic data in surgical patients is lacking, making therapeutic drug monitoring (TDM) of levosimendan, its pharmacologically active metabolite OR-1896, and its intermediate OR-1855 important. A simultaneous highly sensitive quantification of levosimendan and its metabolites in small-volume samples has not yet been described. Here, levosimendan (LLOQ 0.450 nM), OR-1896, and OR-1855 (LLOQ both 1.0 nM) were successfully quantified by LC-ESI-MS/MS after liquid-liquid extraction in 300 µL of blood. A short C8 column under reversed-phase conditions enabled simultaneous and fast quantification of levosimendan in the negative and the metabolites in the positive ionization mode in a single run within 2 min. Interestingly and unexpectedly, constitutional isomers of levosimendan metabolites with identical mass transitions and similar retention times were observed in surgical patients' samples, which we identified as the metamizole metabolites 4-aminoantipyrine and 4-acetamidoantipyrine. A longer C8 column and a modified mobile phase enabled selective quantification of all analytes in a single run within 7 min. We developed, validated, and applied highly sensitive LC-ESI-MS/MS methods for simultaneous quantification of levosimendan and its metabolites, enabling efficient TDM of cardiac surgery patients even with additional metamizole administration.

Cell-Crossing Functional Network Driven by microRNA-125a Regulates Endothelial Permeability and Monocyte Trafficking in Acute Inflammation.

Opening of the endothelial barrier and targeted infiltration of leukocytes into the affected tissue are hallmarks of the inflammatory response. The molecular mechanisms regulating these processes are still widely elusive. In this study, we elucidate a novel regulatory network, in which miR-125a acts as a central hub that regulates and synchronizes both endothelial barrier permeability and monocyte migration. We found that inflammatory stimulation of endothelial cells induces miR-125a expression, which consecutively inhibits a regulatory network consisting of the two adhesion molecules VE-Cadherin (CDH5) and Claudin-5 (CLDN5), two regulatory tyrosine phosphatases (PTPN1, PPP1CA) and the transcription factor ETS1 eventually leading to the opening of the endothelial barrier. Moreover, under the influence of miR-125a, endothelial expression of the chemokine CCL2, the most predominant ligand for the monocytic chemokine receptor CCR2, was strongly enhanced. In monocytes, on the other hand, we detected markedly repressed expression levels of miR-125a upon inflammatory stimulation. This induced a forced expression of its direct target gene CCR2, entailing a strongly enhanced monocyte chemotaxis. Collectively, cell-type-specific differential expression of miR-125a forms a synergistic functional network controlling monocyte trafficking across the endothelial barrier towards the site of inflammation. In addition to the known mechanism of miRNAs being shuttled between cells via extracellular vesicles, our study uncovers a novel dimension of miRNA function: One miRNA, although disparately regulated in the cells involved, directs a biologic process in a synergistic and mutually reinforcing manner. These findings provide important new insights into the regulation of the inflammatory cascade and may be of great use for future clinical applications.

Very-low-carbohydrate diet enhances human T-cell immunity through immunometabolic reprogramming.

Very-low-carbohydrate diet triggers the endogenous production of ketone bodies as alternative energy substrates. There are as yet unproven assumptions that ketone bodies positively affect human immunity. We have investigated this topic in an in vitro model using primary human T cells and in an immuno-nutritional intervention study enrolling healthy volunteers. We show that ketone bodies profoundly impact human T-cell responses. CD4+ , CD8+ , and regulatory T-cell capacity were markedly enhanced, and T memory cell formation was augmented. RNAseq and functional metabolic analyses revealed a fundamental immunometabolic reprogramming in response to ketones favoring mitochondrial oxidative metabolism. This confers superior respiratory reserve, cellular energy supply, and reactive oxygen species signaling. Our data suggest a very-low-carbohydrate diet as a clinical tool to improve human T-cell immunity. Rethinking the value of nutrition and dietary interventions in modern medicine is required.

T-Cell Response in a Cardiac Xenotransplant Model.

OBJECTIVES: Despite the advances in preclinical cardiac xenotransplantation, the immune reactions caused by species differences are not fully understood. Hyperacute rejection can now be avoided using genetically engineered donor organs, but cellmediated rejection by the adaptive immune response has not been addressed successfully. Here we investigated the initial human pan-T-cell reaction using a pig-human blood working heart model. MATERIALS AND METHODS: Porcine wild-type hearts (n = 7) were perfused with human blood in a biventricular working heart system for 3 hours. As control, blood from the same human donors was circulated without a pig heart. Pan-T cells were selectively extracted from blood taken before and at the end of the perfusion cycle. The relative mRNA expression of selected target genes (real-time quantitative polymerase chain reaction) and the expression of microRNAs were determined. RESULTS: After xenogeneic organ perfusion, there was a moderate upregulation of several CD4+ marker cytokines (interleukin 2, interleukin 4, interferon γ) compared with control. We found a distinct increase in the mRNA expression of granzyme B and perforin, key markers of cytotoxic T cells. No differences in the marker genes of regulatory T cells were evident. Levels of the anti-inflammatory microRNAs miR-16 and miR-93 were significantly higher in the xenoperfused group than in the control group. CONCLUSIONS: This study demonstrated that contact of human blood with pig endothelium activates cytotoxic T cells within the first few hours, indicating acute rejection processes. This is accompanied by upregulation of anti-inflammatory microRNAs, which may represent compensatory anti-inflammatory mechanisms.

Impact of carbohydrate-reduced nutrition in septic patients on ICU: study protocol for a prospective randomised controlled trial.

INTRODUCTION: Sepsis is defined as detrimental immune response to an infection. This overwhelming reaction often abolishes a normal reconstitution of the immune cell homeostasis that in turn increases the risk for further complications. Recent studies revealed a favourable impact of ketone bodies on resolution of inflammation. Thus, a ketogenic diet may provide an easy-to-apply and cost-effective treatment option potentially alleviating sepsis-evoked harm. This study is designed to assess the feasibility, efficiency and safety of a ketogenic diet in septic patients. METHODS AND ANALYSIS: This monocentric study is a randomised, controlled and open-label trial, which is conducted on an intensive care unit of a German university hospital. As intervention enteral nutrition with reduced amount of carbohydrates (ketogenic) or standard enteral nutrition (control) is applied. The primary endpoint is the detection of ketone bodies in patients' blood and urine samples. As secondary endpoints, the impact on important safety-relevant issues (eg, glucose metabolism, lactate serum concentration, incidence of metabolic acidosis, thyroid function and 30-day mortality) and the effect on the immune system are analysed. ETHICS AND DISSEMINATION: The study has received the following approvals: Ethics Committee of the Medical Faculty of Ruhr-University Bochum (No. 18-6557-BR). Results will be made available to critical care survivors, their caregivers, the funders, the critical care societies and other researchers by publication in a peer-reviewed journal. TRIAL REGISTRATION NUMBERS: German Clinical Trial Register (DRKS00017710); Universal Trial Number (U1111-1237-2493).

MicroRNA-93 acts as an "anti-inflammatory tumor suppressor" in glioblastoma.

BACKGROUND: Inflammation is an important driver of malignant glioma disease. Inflammatory mediators are not only produced by immune cells in the tumor microenvironment, but also by glioblastoma (GBM) cells themselves creating a mutually reinforcing loop. We here aimed at identifying an "anti-inflammatory switch" that allows to dampen inflammation in GBM. METHODS: We used human GBM specimens, primary cultures, and cell lines. The response of GBM cells toward inflammatory stimuli was tested by incubation with supernatant of stimulated human immune cells. Expression levels were measured by whole transcriptome microarrays and qRT-PCR, and protein was quantified by LUMINEX and SDS-PAGE. MicroRNA binding to 3'UTRs was analyzed by luciferase assays. Proliferation rates were determined by flow cytometry, and invasion and angiogenesis were studied using migration and endothelial tube formation assays. RESULTS: We demonstrated GBM cells to secrete high amounts of proinflammatory mediators in an inflammatory microenvironment. We found miR-93 as a potential "anti-inflammatory tumor suppressor" dramatically downregulated in GBM. Concordantly, cytokine secretion dropped after miR-93 re-expression. Transfection of miR-93 in GBM cells led to down-regulation of hubs of the inflammatory networks, namely, HIF-1α and MAP3K2 as well as IL-6, G-CSF, IL-8, LIF, IL-1ß, COX2, and CXCL5. We showed only COX2 and CXCL5 to be indirectly regulated by miR-93 while all other genes are true targets. Phenotypically, re-expression of miR-93 in GBM cells substantially suppressed proliferation, migration, and angiogenesis. CONCLUSIONS: Alleviating GBM-derived inflammation by re-expression of miR-93 may be a powerful tool to mitigate these tumors' aggressiveness and holds promise for new clinical approaches.

The IL-1 Antagonist Anakinra Attenuates Glioblastoma Aggressiveness by Dampening Tumor-Associated Inflammation.

BACKGROUND: The recombinant IL-1 receptor antagonist anakinra-currently approved for the treatment of autoinflammatory diseases-blocks IL-1ß-mediated inflammatory signaling. As inflammation is a major driver of cancer, we hypothesized that anakinra might be able to mitigate glioblastoma (GBM) aggressiveness. METHODS: Primary GBM or T98G cells were incubated alone or with peripheral blood mononuclear cells (PBMCs) and were subsequently treated with IL-1ß and/or anakinra. T cells were obtained by magnetic bead isolation. Protein and mRNA expression were quantified by SDS-PAGE, qRT-PCR, and ELISA, respectively. Cell proliferation and apoptosis were analyzed via flow cytometry. Chemotaxis was studied via time-lapse microscopy. RESULTS: Upon IL-1ß stimulation, anakinra attenuated proinflammatory gene expression in both GBM cells and PBMCs, and mitigated tumor migration and proliferation. In a more lifelike model replacing IL-1ß stimulation by GBM-PBMC co-culture, sole presence of PBMCs proved sufficient to induce a proinflammatory phenotype in GBM cells with enhanced proliferation and migration rates and attenuated apoptosis. Anakinra antagonized these pro-tumorigenic effects and, moreover, reduced inflammatory signaling in T cells without compromising anti-tumor effector molecules. CONCLUSION: By dampening the inflammatory crosstalk between GBM and immune cells, anakinra mitigated GBM aggressiveness. Hence, counteracting IL-1ß-mediated inflammation might be a promising strategy to pursue.

Identification of suitable controls for miRNA quantification in T-cells and whole blood cells in sepsis.

Complex immune dysregulation is a hallmark of sepsis. The occurring phases of immunosuppression and hyperinflammation require rapid detection and close monitoring. Reliable tools to monitor patient's immune status are yet missing. Currently, microRNAs are being discussed as promising new biomarkers in sepsis. However, no suitable internal control for normalization of miRNA expression by qPCR has been validated so far, thus hampering their potential benefit. We here present the first evaluation of endogenous controls for miRNA analysis in human sepsis. Novel candidate reference miRNAs were identified via miRNA microArray. TaqMan qPCR assays were performed to evaluate these microRNAs in T-cells and whole blood cells of sepsis patients and healthy controls in two independent cohorts. In T-cells, U48 and miR-320 proved suitable as endogenous controls, while in whole blood cells, U44 and miR-942 provided best stability values for normalization of miRNA quantification. Commonly used snRNA U6 exhibited worst stability in all sample groups. The identified internal controls have been prospectively validated in independent cohorts. The critical importance of housekeeping gene selection is emphasized by exemplary quantification of imuno-miR-150 in sepsis patients. Use of appropriate internal controls could facilitate research on miRNA-based biomarker-use and might even improve treatment strategies in the future.

Effects of balanced hydroxyethyl starch 6% (130/0.4) and albumin 5% on clot formation and glycocalyx shedding: Subgroup analysis of a prospective randomized trial.

BACKGROUND: Intravenous fluids can impair coagulation and affect the endothelial glycocalyx, whereas glycocalyx shedding itself can cause an impairment of clot formation and firmness. We hypothesized that hydroxyethyl starch 6% (130/0.4) has a more distinct effect on coagulation and glycocalyx shedding than albumin 5%. METHODS: Presented data derive from an exploratory subgroup analysis of a prospective randomized, single-blinded trial comparing albumin 5% versus balanced hydroxyethyl starch 6% (130/0.4). Patients between 46 and 85 years undergoing cystectomy were included. Prothrombin time, plasma fibrinogen concentration, partial thromboplastin time, thrombelastometry and platelet function were analyzed before and after surgery. Glycocalyx components were assessed before and after surgery, 2 to 4 h after surgery and at 1st and 3rd postoperative day. Primary outcome parameter was the change of thrombelastometric variables at the end of surgery. Further variables included calculated blood loss, infusion amount and transfusion rate. RESULTS: 55 patients (albumin group n = 28; hydroxyethyl starch group n = 27) were included. Thrombelastometric variables were significantly more compromised in the hydroxyethyl starch than in the albumin group whereas platelet function, glycocalyx shedding, partial thromboplastin time, prothrombin time and fibrinogen were not different between groups. Mean intraoperative calculated blood loss was higher in the hydroxyethyl starch group (1557 ±â€¯825 ml versus 1245 ±â€¯709 ml; p = 0.042). Transfusion requirements did not differ. CONCLUSION: Rotational thrombelastometric variables were significantly more reduced when hydroxyethyl starch was used compared to albumin 5%. This effect was independent from a shedding of the endothelial glycocalyx. However, results presented here are from a subgroup analysis and must be considered with caution. Trial registration EudraCT number 2010-018343-34.

Myeloid-Derived Suppressor Cells Mediate Immunosuppression After Cardiopulmonary Bypass.

OBJECTIVES: Cardiopulmonary bypass is associated with severe immune dysfunctions. Particularly, a cardiopulmonary bypass-related long-lasting immunosuppressive state predisposes patients to a higher risk of postoperative complications, such as persistent bacterial infections. This study was conducted to elucidate mechanisms of post-cardiopulmonary bypass immunosuppression. DESIGN: In vitro studies with human peripheral blood mononuclear cells. SETTING: Cardiosurgical ICU, University Research Laboratory. PATIENTS: Seventy-one patients undergoing cardiac surgery with cardiopulmonary bypass (enrolled May 2017 to August 2018). INTERVENTIONS: Peripheral blood mononuclear cells before and after cardiopulmonary bypass were analyzed for the expression of immunomodulatory cell markers by real-time quantitative reverse transcription polymerase chain reaction. T cell effector functions were determined by enzyme-linked immunosorbent assay, carboxyfluorescein succinimidyl ester staining, and cytotoxicity assays. Expression of cell surface markers was assessed by flow cytometry. CD15 cells were depleted by microbead separation. Serum arginine was measured by mass spectrometry. Patient peripheral blood mononuclear cells were incubated in different arginine concentrations, and T cell functions were tested. MEASUREMENTS AND MAIN RESULTS: After cardiopulmonary bypass, peripheral blood mononuclear cells exhibited significantly reduced levels of costimulatory receptors (inducible T-cell costimulator, interleukin 7 receptor), whereas inhibitory receptors (programmed cell death protein 1 and programmed cell death 1 ligand 1) were induced. T cell effector functions (interferon γ secretion, proliferation, and CD8-specific cell lysis) were markedly repressed. In 66 of 71 patients, a not yet described cell population was found, which could be characterized as myeloid-derived suppressor cells. Myeloid-derived suppressor cells are known to impair immune cell functions by expression of the arginine-degrading enzyme arginase-1. Accordingly, we found dramatically increased arginase-1 levels in post-cardiopulmonary bypass peripheral blood mononuclear cells, whereas serum arginine levels were significantly reduced. Depletion of myeloid-derived suppressor cells from post-cardiopulmonary bypass peripheral blood mononuclear cells remarkably improved T cell effector function in vitro. Additionally, in vitro supplementation of arginine enhanced T cell immunocompetence. CONCLUSIONS: Cardiopulmonary bypass strongly impairs the adaptive immune system by triggering the accumulation of myeloid-derived suppressor cells. These myeloid-derived suppressor cells induce an immunosuppressive T cell phenotype by increasing serum arginine breakdown. Supplementation with L-arginine may be an effective measure to counteract the onset of immunoparalysis in the setting of cardiopulmonary bypass.

Inactivation of the tyrosine phosphatase SHP-2 drives vascular dysfunction in Sepsis.

BACKGROUND: Sepsis, the most severe form of infection, involves endothelial dysfunction which contributes to organ failure. To improve therapeutic prospects, elucidation of molecular mechanisms underlying endothelial vascular failure is of essence. METHODS: Polymicrobial contamination induced sepsis mouse model and primary endothelial cells incubated with sepsis serum were used to study SHP-2 in sepsis-induced endothelial inflammation. SHP-2 activity was assessed by dephosphorylation of pNPP, ROS production was measured by DCF oxidation and protein interactions were assessed by proximity ligation assay. Vascular inflammation was studied in the mouse cremaster model and in an in vitro flow assay. FINDINGS: We identified ROS-dependent inactivation of the tyrosine phosphatase SHP-2 to be decisive for endothelial activation in sepsis. Using in vivo and in vitro sepsis models, we observed a significant reduction of endothelial SHP-2 activity, accompanied by enhanced adhesion molecule expression. The impaired SHP-2 activity was restored by ROS inhibitors and an IL-1 receptor antagonist. SHP-2 activity inversely correlated with the adhesive phenotype of endothelial cells exposed to IL-1ß as well as sepsis serum via p38 MAPK and NF-κB. In vivo, SHP-2 inhibition accelerated IL-1ß-induced leukocyte adhesion, extravasation and vascular permeability. Mechanistically, SHP-2 directly interacts with the IL-1R1 adaptor protein MyD88 via its tyrosine 257, resulting in reduced binding of p85/PI3-K to MyD88. INTERPRETATION: Our data show that SHP-2 inactivation by ROS in sepsis releases a protective break, resulting in endothelial activation. FUND: German Research Foundation, LMU Mentoring excellence and FöFoLe Programme, Verein zur Förderung von Wissenschaft und Forschung, German Ministry of Education and Research.

Changes of hemodynamic and cerebral oxygenation after exercise in normobaric and hypobaric hypoxia: associations with acute mountain sickness.

OBJECTIVE: Normobaric (NH) and hypobaric hypoxia (HH) are associated with acute mountain sickness (AMS) and cognitive dysfunction. Only few variables, like heart-rate-variability, are correlated with AMS. However, prediction of AMS remains difficult. We therefore designed an expedition-study with healthy volunteers in NH/HH to investigate additional non-invasive hemodynamic variables associated with AMS. METHODS: Eleven healthy subjects were examined in NH (FiO2 13.1%; equivalent of 3.883 m a.s.l; duration 4 h) and HH (3.883 m a.s.l.; duration 24 h) before and after an exercise of 120 min. Changes in parameters of electrical cardiometry (cardiac index (CI), left-ventricular ejection time (LVET), stroke volume (SV), index of contractility (ICON)), near-infrared spectroscopy (cerebral oxygenation, rScO2), Lake-Louise-Score (LLS) and cognitive function tests were assessed. One-Way-ANOVA, Wilcoxon matched-pairs test, Spearman's-correlation-analysis and Student's t-test were performed. RESULTS: HH increased heart rate (HR), mean arterial pressure (MAP) and CI and decreased LVET, SV and ICON, whereas NH increased HR and decreased LVET. In both NH and HH cerebral oxygenation decreased and LLS increased significantly. After 24 h in HH, 6 of 11 subjects (54.6%) developed AMS. LLS remained increased until 24 h in HH, whereas cognitive function remained unaltered. In HH, HR and LLS were inversely correlated (r = - 0.692; p < 0.05). More importantly, the rScO2-decrease after exercise in NH significantly correlated with LLS after 24 h in HH (r = - 0.971; p < 0.01) and rScO2 correlated significantly with HR (r = 0.802; p < 0.01), CI (r = 0.682; p < 0.05) and SV (r = 0.709; p < 0.05) after exercise in HH. CONCLUSIONS: Both acute NH and HH altered hemodynamic and cerebral oxygenation and induced AMS. Subjects, who adapted their CI had higher rScO2 and lower LLS. Furthermore, rScO2 after exercise under normobaric conditions was associated with AMS at high altitudes.

Intronic miR-744 Inhibits Glioblastoma Migration by Functionally Antagonizing Its Host Gene MAP2K4.

BACKGROUND: The second intron of Mitogen-Activated Protein Kinase Kinase 4 (MAP2K4), an important hub in the pro-invasive MAPK pathway, harbors miR-744. There is accumulating evidence that intronic micro-RNAs (miRNAs) are capable of either supporting or restraining functional pathways of their host genes, thereby creating intricate regulative networks. We thus hypothesized that miR-744 regulates glioma migration by interacting with its host's pathways. METHODS: Patients' tumor specimens were obtained stereotactically. MiR-744 was overexpressed in U87, T98G, and primary glioblastoma (GBM) cell lines. Cell mobility was studied using migration and Boyden chamber assays. Protein and mRNA expression was quantified by SDS-PAGE and qRT-PCR. Interactions of miR-744 and 3'UTRs were analyzed by luciferase reporter assays, and SMAD2/3, p38, and beta-Catenin activities by TOP/FOPflash reporter gene assays. RESULTS: As compared to a normal brain, miR-744 levels were dramatically decreased in GBM samples and in primary GBM cell lines. Astrocytoma WHO grade II/III exhibited intermediate expression levels. Re-expression of miR-744 in U87, T98G, and primary GBM cell lines induced focal growth and impaired cell mobility. Luciferase activity of 3'UTR reporter constructs revealed the pro-invasive factors TGFB1 and DVL2 as direct targets of miR-744. Re-expression of miR-744 reduced levels of TGFB1, DVL2, and the host MAP2K4, and mitigated activity of TGFB1 and DVL2 downstream targets SMAD2/3 and beta-Catenin. TGFB1 knock-down repressed MAP2K4 expression. CONCLUSION: MiR-744 acts as an intrinsic brake on its host. It impedes MAP2K4 functional pathways through simultaneously targeting SMAD-, beta-Catenin, and MAPK signaling networks, thereby strongly mitigating pro-migratory effects of MAP2K4. MiR-744 is strongly repressed in glioma, and its re-expression might attenuate tumor invasiveness.

Identification and Validation of Potential Differential miRNA Regulation via Alternative Polyadenylation.

MiRNAs control gene expression via recognition of specific sequences in the 3' untranslated region of target genes, leading to mRNA degradation and consequently translational repression. The regulatory impact of miRNAs does not only depend on their expression levels, but also on their targets' mRNA configuration. Via alternative polyadenylation mRNA isoforms are created that may or may not contain the respective miRNA target sequence, turning the regulatory between these two on or off. In the following article, we describe our protocol on how to combine a bioinformatics evaluation of a potential miRNA-target gene interaction using the public web framework miRIAD with 5' rapid amplification of cDNA ends (5'-RACE) in order to explore differential gene regulation by miRNAs through alternative polyadenylation.

MicroRNAs as Clinical Biomarkers and Therapeutic Tools in Perioperative Medicine.

Over the past decade, evolutionarily conserved, noncoding small RNAs-so-called microRNAs (miRNAs)-have emerged as important regulators of virtually all cellular processes. miRNAs influence gene expression by binding to the 3'-untranslated region of protein-coding RNA, leading to its degradation and translational repression. In medicine, miRNAs have been revealed as novel, highly promising biomarkers and as attractive tools and targets for novel therapeutic approaches. miRNAs are currently entering the field of perioperative medicine, and they may open up new perspectives in anesthesia, critical care, and pain medicine. In this review, we provide an overview of the biology of miRNAs and their potential role in human disease. We highlight current paradigms of miRNA-mediated effects in perioperative medicine and provide a survey of miRNA biomarkers in the field known so far. Finally, we provide a perspective on miRNA-based therapeutic opportunities and perspectives.