Tim-Philipp Simon

Hydroxyethylstarch impairs renal function and induces interstitial proliferation, macrophage infiltration and tubular damage in an isolated renal perfusion model

IntroductionThe aim of the study was to evaluate some of the underlying pathomechanisms of hydroxyethylstarch (HES) induced adverse effects on renal function using 24 porcine kidneys in an isolated perfusion model over six hours.MethodsInfusion of either 10% HES 200/0.5, 6% HES 130/0.42 or Ringers lactate (RL) was performed to achieve an haematocrit of 20% in eight kidneys from four animals per group. Physiological and pathophysiological parameters were determined (including N-acetyl-beta-aminoglucosidase as a marker for lysosomal tubular damage). Histological investigations and immunohistological stainings of the kidneys were performed.ResultsInitially after haemodilution, HES 130/0.42 and HES 200/0.5 reduced urine output compared with RL (P < 0.01). After six hours, N-acetyl-beta-aminoglucosidase was significantly higher in HES 200/0.5 (81 ± 23 U/L) compared with HES 130/0.42 (38 ± 12 U/L) and RL (21 ± 13 U/L; P < 0.001). Osmotic nephrosis-like lesions (OL) of the tubuli were present in all groups showing a significantly lower number of OL in RL (1.1 ± 0.4; P = 0.002) compared with both HES groups (HES 200/0.5 = 2.1 ± 0.6; HES 130/0.42 = 2.0 ± 0.5). Macrophage infiltration was significantly higher in HES 200/0.5 compared with HES 130/0.42 (1.3 ± 1.0 vs. 0.2 ± 0.04; P = 0.044). There was a significant increase in interstitial cell proliferation in the HES 200/0.5 group vs. HES 130/0.42 (18.0 ± 6.9 vs. 6.5 ± 1.6; P = 0.006) with no significant difference in RL (13.5 ± 4.0).ConclusionsWe observed impaired diuresis and sodium excretion by HES and identified renal interstitial proliferation, macrophage infiltration and tubular damage as potential pathological mechanisms of HES-induced adverse effects on renal function using an isolated porcine renal perfusion model. Furthermore, we demonstrated that 10% HES 200/0.5 had more of a pro-inflammatory effect compared with 6% HES 130/0.42 and caused more pronounced tubular damage than 6% HES 130/0.42 and RL. OL were present in all groups, but to a lesser degree after RL administration.

The anti-inflammatory effect of the synthetic antimicrobial peptide 19-2.5 in a murine sepsis model: a prospective randomized study

IntroductionIncreasing rates of multi-resistant bacteria are a major problem in the treatment of critically ill patients. Furthermore, conventional antibiotics lead to the release of bacterial derived membrane parts initiating pro-inflammatory cascades with potential harm to the patient. Antimicrobial peptides (AMP) may kill bacteria without releasing pro-inflammatory factors. Thus, we compared three newly developed synthetic anti-lipopolysaccharide peptides (SALPs) with a broader range of efficacy to suppress cytokine release in plasma and CD14 mRNA expression in organ tissue in a murine, polymicrobial sepsis model.MethodsA randomized, experimental trial was conducted in an animal research facility. Male NMRI mice (n = 90; 8- to 12-weeks old) were randomized to the following six groups: (i) sham operation and parenteral vehicle (NaCl 0.9%) administration (sham); (ii) cecal ligation and puncture (CLP) and vehicle infusion (sepsis-control), (iii) CLP and polymyxin B infusion (polyB), or (iv to vi) CLP and infusion of three different synthetic antimicrobial peptides Peptide 19-2.5 (Pep2.5), Peptide 19-4 (Pep4) or Peptide 19-8 (Pep8). All animals underwent arterial and venous catheterization for hemodynamic monitoring 48 hours prior to CLP or sham-operation. Physical appearance and behavior (activity), plasma cytokine levels, and CD14 mRNA expression in heart, lung, liver, spleen and kidney tissue were determined 24 hours after CLP or sham operation.ResultsOnly Pep2.5 significantly enhanced the activity after CLP, whereas none of the therapeutic regimens elevated the mean arterial pressure or heart rate. The strongly elevated IL-6, IL-10 and monocyte chemoattractant protein serum levels in septic animals were significantly reduced after Pep2.5 administration (P < 0.001, P < 0.001, and P < 0.001, respectively). Similarly, Pep2.5 significantly reduced the sepsis-induced CD14 mRNA expression in heart (P = 0.003), lung (P = 0.008), and spleen tissue (P = 0.009) but not in kidney and liver.ConclusionsStructurally variable SALPs exhibit major differences in their anti-inflammatory effect in vivo. Continuous parenteral administration of Pep2.5 is able to reduce sepsis-induced cytokine release and tissue inflammation.

Characterization of blunt chest trauma in a long-term porcine model of severe multiple trauma

Chest trauma has a significant relevance on outcome after severe trauma. Clinically, impaired lung function typically occurs within 72 hours after trauma. However, the underlying pathophysiological mechanisms are still not fully elucidated. Therefore, we aimed to establish an experimental long-term model to investigate physiological, morphologic and inflammatory changes, after severe trauma. Male pigs (sus scrofa) sustained severe trauma (including unilateral chest trauma, femur fracture, liver laceration and hemorrhagic shock). Additionally, non-injured animals served as sham controls. Chest trauma resulted in severe lung damage on both CT and histological analyses. Furthermore, severe inflammation with a systemic increase of IL-6 (p = 0.0305) and a local increase of IL-8 in BAL (p = 0.0009) was observed. The pO2/FiO2 ratio in trauma animals decreased over the observation period (p < 0.0001) but not in the sham group (p = 0.2967). Electrical Impedance Tomography (EIT) revealed differences between the traumatized and healthy lung (p < 0.0001). In conclusion, a clinically relevant, long-term model of blunt chest trauma with concomitant injuries has been developed. This reproducible model allows to examine local and systemic consequences of trauma and is valid for investigation of potential diagnostic or therapeutic options. In this context, EIT might represent a radiation-free method for bedside diagnostics.

Persistent low serum zinc is associated with recurrent sepsis in critically ill patients - A pilot study

Zinc is an essential trace element for both pathogens and hosts. Hypozincemia is a well known phenomenon in sepsis patients and represents the innate immune systems attempt to deprive pathogens of zinc. However little is known about course, restitution and prognostic value of serum zinc levels in sepsis patients. We performed a prospective observational single-center study set in a tertiary care university hospital intensive care unit. Serum zinc levels were singularly measured of healthy controls and sequentially of surgical sepsis patients and surgical patients over a 8-day period. Throughout the study period, we report significantly decreased serum zinc levels in surgical and surgical sepsis patients compared to healthy controls. Lower serum zinc levels in surgical sepsis patients were associated with a higher susceptibility to a recurrent sepsis episode. Furthermore, surgical sepsis patients with a higher number of organ dysfunctions and increased in-hospital mortality at day 28 and 90 showed lower serum zinc levels at admission. We report serum zinc levels as a promising biomarker in the diagnosis and evaluation of sepsis patients. However, it is still unclear whether these findings are caused by an over-amplified redistribution of zinc during acute-phase response, or whether the critically ill patients were zinc deficient before sepsis.

Plasma adrenomedullin in critically ill patients with sepsis after major surgery: A pilot study

Purpose: Adrenomedullin is released by different tissues in hypoxia, oxidative stress, and inflammation and is found in general and medical patients and, recently, in sepsis patients in emergency departments. The aim of this study was to evaluate biologically active adrenomedullin that mirrors directly the active peptide levels in plasma of surgical intensive care unit (ICU) patients with sepsis. Materials and methods: In this single‐center observational pilot trial, 42 ICU patients with sepsis and 14 patients after major surgery were included after sepsis diagnosis or ICU admission. Results: Patients (66% male) were 70 (median) (interquartile range [IQR], 61‐77]) years old and had a body mass index of 26.2 (24.2‐29.4) kg/m2. The ICU and hospital length of stay was 8 (1‐22) and 17 (8‐21) days, respectively. Eight patients had sepsis, 19 developed severe sepsis, and 15 suffered from septic shock. Adrenomedullin increased with severity (sepsis: 25.8 pg/mL [IQR 20.3‐40.2], severe sepsis: 84.2 pg/mL [IQR 42.7‐118.5], septic shock: 119.7 pg/mL [IQR 83.8‐172.6]; P < .0001). Higher adrenomedullin was associated with poor 90‐day outcomes (P = .019) and more frequent vasopressor use (P = .001). Conclusions: This is the first study investigating adrenomedullin in patients with sepsis following major surgery. Higher adrenomedullin on admission is associated with increased vasopressor need and mortality after 90 days. Thus, adrenomedullin may be a useful additional parameter in surgical patients with sepsis.

Monitoring lung contusion in a porcine polytrauma model using EIT: an application study

Lung contusion is the most common lung injury following blunt chest trauma which, in turn, is associated with high mortality rates (Gavelli et al 2002 Eur. Radiol. 12 1273-94). Lung contusion is characterized by hemorrhage and edema with consecutively reduced compliance. Objective and Approach: In this study, unilateral lung contusion and other traumata were induced in 12 pigs by using a bolt gun machine. To investigate the pathophysiological consequences of lung contusion, information on clinical parameters was collected and monitored regularly while animals were additionally monitored with electrical impedance tomography (EIT) before trauma, and at 4, 24, 48 and 72 h after polytrauma. MAIN RESULTS Statistical analyses showed significant differences between the measurement time points in terms of lung compliance ([Formula: see text]) and in global EIT parameters, such as absolute global impedance (aGlobImp) ([Formula: see text]), tidal impedance variation (TIV) ([Formula: see text]) and the center of ventilation (CoV) ([Formula: see text]). Additionally, distinct analyses for the left (non-injured) and right (injured) lung were also performed. In this context, during the progress of lung contusion, significant changes were found for the injured lung in TIV ([Formula: see text]), global inhomogeneity ([Formula: see text]), regional ventilation delay ([Formula: see text]), CoV ([Formula: see text]) and in regions of non-ventilation (rNoVent) ([Formula: see text]). Furthermore, TIV and rNoVent were capable to differentiate the injured and the contralateral healthy lung at 4 and 24 h after injury (TIV: [Formula: see text] and [Formula: see text]; rNoVent: [Formula: see text] and [Formula: see text]). TIV reached a sensitivity of 82% (specificity of 100%) at 4 h and sensitivity of 82% (specificity of 82%) at 24 h after injury, in detecting lung contusion specific consequences. SIGNIFICANCE The results indicate that EIT might be a valuable tool to detect and to monitor lung injuries including lung contusion. Most probably, EIT-derived indices could also be used to adapt ventilator settings to optimize individual lung protection.

Investigating colloids and crystalloids—everything clear?

Intensive care medicine must take into account disturbed physiological variables. Treatment should be aimed at restoring normal values of these variables, or at least at preventing further deterioration. Shoemaker and colleagues demonstrated that organ failure occurs in high-risk surgical patients when they experience an oxygen deficit, especially intra-operatively and in the early postoperative period. The use of dobutamine to simply increase oxygen delivery (DO2) did not result in increased survival or decreased organ failure. But treatment of postoperative hypovolaemia should aim to compensate the potential shortage in DO2. In this regard, the investigation by Skytte and colleagues provides valuable new evidence on the choice of volume resuscitation in postoperative care in a sophisticated fashion. They found that a bolus administration of crystalloid solution compared with hydroxyethyl starch (HES) after cardiac surgery results in a decrease in renal vein oxygen saturation and an increase in renal oxygen extraction. Skytte and colleagues identified repeated boluses of crystalloid solution as a potential harm for renal oxygenation. This may be of special interest in patients with hypovolaemia when the renal DO2 is impaired. Since DO2 is improved by enhancing blood flow, the investigation by Skytte and colleagues is even more interesting because renal blood flow and cardiac output were increased by both crystalloids and colloids, but the ratio between renal blood flow and cardiac output decreased solely with crystalloids. The major limitation, as already mentioned by Skytte and colleagues, is that they included patientswhowere considered already haemodynamically stable. This is amajor weakness in all trials investigating fluid resuscitation in critically ill patients apart from the CRISTAL trial. In contrast to the investigation by Skytte and colleagues, a former investigation assessing the influence of crystalloid or HES in patients with colorectal surgery could not detect any benefit or harmwith respect to the presence of gastrointestinal (GI)morbidity within the first week after surgery. Other authors could not detect differences in cerebral oxygen extraction when comparing HES with a lactated Ringer’s solution. Yet, a major study leading to the ban of HES in intensive care is in line with the results of Skytte and colleagues. A higher proportion of Risk, Injury, Failure, Loss, and End-stage kidney disease (RIFLE) risk and injury in saline-treated patients compared with HES [3.3% increase (P=0.007) and 3.4% increase (P=0.005), respectively] was detected, but no difference was detectable in the RIFLE failure group. The decision for renal replacement therapy (RRT) was not controlled by the study protocol. Others who compared HES with crystalloids found higher rates of RRT and also exhibited a lack of a protocol for initiation of RRT. To overcome the uncertainty on the appropriate choice and guidance of volume therapy and resuscitation, an evidencedbased guideline on volume therapy in adults was generated by the Association of the Scientific Medical Societies in Germany [Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften e.V. (AWMF)]. AWMF represents Germany in the Council for International Organizations of Medical Sciences (CIOMS). This association affiliates 173 scientific societies from all specialties of medicine in Germany and has generated very high quality and methodological standards, leading to very robust and useful recommendations and guidelines. A guideline on volume therapy was generated on the highest evidence level possible (S3). Following this guideline, estimating the need for volume resuscitation by using central venous pressure (CVP) is not appropriate, as shown in numerous studies in anaesthesia and critical care settings. Thus, this level of evidence led to the recommendation that CVP should not be used for resuscitation guidance; the passive leg raise (PLR) or flow-based parameters should be used instead. The reliability of the PLR to detect changes in cardiac preload was described previously. Furthermore, the National Institute for Health and Care Excellence (NICE) guideline (CG174) on fluid therapy in adults recommends the PLR test for initial assessment of fluid responsiveness. The application of adequate volume resuscitation is more complex than in past decades. An important step is the consideration of fluids as a drug with special indications and contraindications. In this regard, the guidance of fluid therapy during four

Heparan Sulfate Induces Necroptosis in Murine Cardiomyocytes: A Medical-In silico Approach Combining In vitro Experiments and Machine Learning

Life-threatening cardiomyopathy is a severe, but common, complication associated with severe trauma or sepsis. Several signaling pathways involved in apoptosis and necroptosis are linked to trauma- or sepsis-associated cardiomyopathy. However, the underling causative factors are still debatable. Heparan sulfate (HS) fragments belong to the class of danger/damage-associated molecular patterns liberated from endothelial-bound proteoglycans by heparanase during tissue injury associated with trauma or sepsis. We hypothesized that HS induces apoptosis or necroptosis in murine cardiomyocytes. By using a novel Medical-In silico approach that combines conventional cell culture experiments with machine learning algorithms, we aimed to reduce a significant part of the expensive and time-consuming cell culture experiments and data generation by using computational intelligence (refinement and replacement). Cardiomyocytes exposed to HS showed an activation of the intrinsic apoptosis signal pathway via cytochrome C and the activation of caspase 3 (both p < 0.001). Notably, the exposure of HS resulted in the induction of necroptosis by tumor necrosis factor α and receptor interaction protein 3 (p < 0.05; p < 0.01) and, hence, an increased level of necrotic cardiomyocytes. In conclusion, using this novel Medical-In silico approach, our data suggest (i) that HS induces necroptosis in cardiomyocytes by phosphorylation (activation) of receptor-interacting protein 3, (ii) that HS is a therapeutic target in trauma- or sepsis-associated cardiomyopathy, and (iii) indicate that this proof-of-concept is a first step toward simulating the extent of activated components in the pro-apoptotic pathway induced by HS with only a small data set gained from the in vitro experiments by using machine learning algorithms.

Leukotriene B4 indicates lung injury and on-going inflammatory changes after severe trauma in a porcine long-term model

BACKGROUND Recognizing patients at risk for pulmonary complications (PC) is of high clinical relevance. Migration of polymorphonuclear leukocytes (PMN) to inflammatory sites plays an important role in PC, and is tightly regulated by specific chemokines including interleukin (IL)-8 and other mediators such as leukotriene (LT)B4. Previously, we have reported that LTB4 indicated early patients at risk for PC after trauma. Here, the relevance of LTB4 to indicating lung integrity in a newly established long-term porcine severe trauma model (polytrauma, PT) was explored. METHODS Twelve pigs (3 months old, 30 ± 5kg) underwent PT including standardized femur fracture, lung contusion, liver laceration, hemorrhagic shock, subsequent resuscitation and surgical fracture fixation. Six animals served as controls (sham). After 72h lung damage and inflammatory changes were assessed. LTB4 was determined in plasma before the experiment, immediately after trauma, and after 2, 4, 24 or 72h. Bronchoalveolar lavage (BAL)-fluid was collected prior and after the experiment. RESULTS Lung injury, local gene expression of IL-8, IL-1β, IL-10, IL-18 and PMN-infiltration into lungs increased significantly in PT compared with sham. Systemic LTB4 increased markedly in both groups 4h after trauma. Compared with declined plasma LTB4 levels in sham, LTB4 increased further in PT after 72h. Similar increase was observed in BAL-fluid after PT. CONCLUSIONS In a severe trauma model, sustained changes in terms of lung injury and inflammation are determined at day 3 post-trauma. Specifically, increased LTB4 in this porcine long-term model indicated a rapid inflammatory alteration both locally and systemically. The results support the concept of LTB4 as a biomarker for PC after severe trauma and lung contusion.

Organ-specific effects on inflammation and apoptosis of recombinant human activated protein C in a murine model of sepsis

There is legitimate interest in the effects of recombinant human activated protein C (rhAPC) on various organs and individual patients, but the specific effects on organ tissues during early sepsis remain unknown. Differences in the levels of organ damage may influence responses to drug therapy. We aimed to investigate whether rhAPC induces organ-specific effects on inflammation and apoptosis using randomized, experimental trials with male NMRI mice. Animals underwent caecal ligation and puncture, and after 12 h, sepsis inflammation and apoptosis were assessed by plasma cytokines, gene expression ratios and immunohistochemistry (IHC). RhAPC-treated animals exhibited increased physical activity and decreased cytokine release compared to untreated animals (interleukin-6 reduction 58%, P < 0.001). CD14 expression was higher in the heart and liver and decreased upon rhAPC application in the heart (−35%), liver and kidney (both −60%). Macrophage inflammatory protein 2 (MIP2) expression decreased in the heart (−58%) but not in the liver or kidney. IHC revealed decreased cleaved caspase-3 in the heart and kidney due to rhAPC intervention. Preservation of the endothelial PC receptor was significant only in the heart during sepsis (P = 0.007). In early polymicrobial sepsis, inflammation was more pronounced in the heart and liver compared to the kidney. RhAPC exhibited protective effects, especially in the heart tissue, and led to reduced plasma levels of pro-inflammatory cytokines and improved physical activity.