Intestinal ischemia/reperfusion (I/R)-injury often results in sepsis and organ failure and is of major importance in the clinic. A potential strategy to reduce I/R-injury is the application of ischemic preconditioning (IPC) during which repeated, brief episodes of I/R are applied. The aim of this study was to evaluate physiological and cellular effects of intestinal I/R-injury and to compare the influence of in-vivo IPC (iIPC) with ex-vivo IPC (eIPC), in which blood derived factors and nerval regulations are excluded.Using an established perfused rat intestine model, effects of iIPC and eIPC on physiological as well as cellular mechanisms of I/R-injury (60 min hypoxia, 30 min reperfusion) were investigated. iIPC was applied by three reversible occlusions of the mesenteric artery in-vivo for 5 min followed by 5 min of reperfusion before isolating the small intestine, eIPC was induced by stopping the vascular perfusion ex-vivo 3 times for 5 min followed by 5 min of reperfusion after isolation of the intestine. Study groups (each N = 8-9 animals) were: iIPC, eIPC, I/R (iIPC group), I/R (eIPC group), iIPC+I/R, eIPC+I/R, no intervention/control (iIPC group), no intervention/control (eIPC group). Tissue morphology/damage, metabolic functions, fluid shifts and barrier permeability were evaluated. Cellular mechanisms were investigated using signaling arrays.I/R-injury decreased intestinal galactose uptake (iIPC group: p<0.001), increased vascular perfusion pressure (iIPC group: p<0.001; eIPC group: p<0.01) and attenuated venous flow (iIPC group: p<0.05) while lactate-to-pyruvate ratio (iIPC group, eIPC group: p<0.001), luminal flow (iIPC group: p<0.001; eIPC group: p<0.05), goblet cell ratio (iIPC group, eIPC group: p<0.001) and apoptosis (iIPC group, eIPC group: p<0.05) were all increased. Application of iIPC prior to I/R increased vascular galactose uptake (P<0.05) while eIPC had no significant impact on parameters of I/R-injury. On cellular level, I/R-injury resulted in a reduction of the phosphorylation of several MAPK signaling molecules. Application of iIPC prior to I/R increased phosphorylation of JNK2 and p38δ while eIPC enhanced CREB and GSK-3α/β phosphorylation.Intestinal I/R-injury is associated with major physiological and cellular changes. However, the overall influence of the two different IPC strategies on the acute phase of intestinal I/R-injury is rather limited.
Platelet activating factor (PAF) induces vascular barrier breakdown and intestinal failure that contribute to the development of sepsis. The exact cellular mechanisms are not well understood.
Background The application of hydroxyethyl starch (HES) for volume resuscitation is controversially discussed and clinical studies have suggested adverse effects of HES substitution, leading to increased patient mortality. Although, the intestine is of high clinical relevance and plays a crucial role in sepsis and inflammation, information about the effects of HES on intestinal function and barrier integrity is very scarce. We therefore evaluated the effects of clinically relevant concentrations of HES on intestinal function and barrier integrity employing an isolated perfused model of the mouse small intestine. Methods An isolated perfused model of the mouse small intestine was established and intestines were vascularly perfused with a modified Krebs-Henseleit buffer containing 3% Albumin (N=7) or 3% HES (130/0.4; N=7). Intestinal metabolic function (galactose uptake, lactate-to-pyruvate ratio), edema formation (wet-to-dry weight ratio), morphology (histological and electron microscopical analysis), fluid shifts within the vascular, lymphatic and luminal compartments, as well as endothelial and epithelial barrier permeability (FITC-dextran translocation) were evaluated in both groups. Results Compared to the Albumin group, HES perfusion did not significantly change the wet-to-dry weight ratio and lactate-to-pyruvate ratio. However, perfusing the small intestine with 3% HES resulted in a significant loss of vascular fluid (p<0.01), an increased fluid accumulation in the intestinal lumen (p<0.001), an enhanced translocation of FITC-dextran from the vascular to the luminal compartment (p<0.001) and a significantly impaired intestinal galactose uptake (p<0.001). Morphologically, these findings were associated with an aggregation of intracellular vacuoles within the intestinal epithelial cells and enlarged intercellular spaces. Conclusion A vascular perfusion with 3% HES impairs the endothelial and epithelial barrier integrity as well as metabolic function of the small intestine.
IMPORTANCE: Anaphylatoxin C5a, a proinflammatory complement split product, plays a central role in mediating organ dysfunction. OBJECTIVES: This phase II clinical trial was conducted to study safety, tolerability, pharmacokinetics, and pharmacodynamics of vilobelimab, a recombinant monoclonal antibody against C5a, in patients with severe sepsis or septic shock. DESIGN: Multicenter, randomized, and placebo-controlled study. SETTING AND PARTICIPANTS: Eleven multidisciplinary ICUs across Germany. Adult patients with severe sepsis or septic shock and with early onset of infection-associated organ dysfunction. MAIN OUTCOMES AND MEASURES: Patients were randomly assigned in a ratio of 2:1 to three subsequent dosing cohorts for IV vilobelimab or placebo receiving either 2 × 2 mg/kg (0 and 12 hr), 2 × 4 mg/kg (0 and 24 hr), and 3 × 4 mg/kg (0, 24, and 72 hr). Co-primary endpoints were pharmacodynamics (assessed by C5a concentrations), pharmacokinetics (assessed by vilobelimab concentrations), and safety of vilobelimab. Preliminary efficacy was evaluated by secondary objectives. RESULTS: Seventy-two patients were randomized (16 patients for each vilobelimab dosing cohort and eight patients for each placebo dosing cohort). Vilobelimab application was associated with dosing dependent decrease in C5a compared with baseline ( p < 0.001). Duration of C5a decrease increased with more frequent dosing. Membrane attack complex lysis capacity measured by 50% hemolytic complement was not affected. Vilobelimab was well tolerated with similar safety findings in all dose cohorts. No vilobelimab-specific adverse events emerged. For vilobelimab-treated patients, investigators attributed less treatment-emergent adverse events as related compared with placebo. Dosing cohorts 2 and 3 had the highest ICU-free and ventilator-free days. There was no difference in mortality, vasopressor-free days, or renal replacement therapy-free days between the groups. CONCLUSIONS AND RELEVANCE: Administration of vilobelimab in patients with severe sepsis and septic shock selectively neutralizes C5a in a dose-dependent manner without blocking formation of the membrane attack complex and without resulting in detected safety issues. The data warrant further investigation of C5a inhibition in sepsis.
Electrical impedance tomography (EIT) is able to detect rapid lung volume changes during breathing. The aim of our observational study was to characterise the heterogeneity of regional ventilation distribution in lung-healthy adults by EIT and to detect the possible impact of tobacco consumption. A total of 219 nonsmokers, asymptomatic ex-smokers and current smokers were examined during forced full expiration using EIT. Forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC were determined in 836 EIT image pixels for the analysis of spatial and temporal ventilation distribution. Coefficients of variation (CVs) of these pixel values were calculated. Histograms and medians of FEV1/FVCEIT and times required to exhale 50%, 75%, 90% of FVCEIT (t50, t75 and t90) were generated. CV of FEV1/FVCEIT distinguished among all groups (mean±sd: nonsmokers 0.43±0.05, ex-smokers 0.52±0.09, smokers 0.62±0.16). Histograms of FEV1/FVCEIT differentiated between nonsmokers and the other groups (p<0.0001). Medians of t50, t75 and t90 showed the lowest values in nonsmokers. Median t90 separated all groups (median (interquartile range): nonsmokers 0.82 (0.67-1.15), ex-smokers 1.41 (1.03-2.21), smokers 1.91 (1.33-3.53)). EIT detects regional ventilation heterogeneity during forced expiration in healthy nonsmokers and its increase in asymptomatic former and current smokers. Therefore, EIT-derived reference values should only be collected from nonsmoking lung-healthy adults.
