Experimental Model Of Septic Shock Research Articles

Angiotensin 1–7 in an experimental septic shock model

BackgroundAlterations in the renin–angiotensin system have been implicated in the pathophysiology of septic shock. In particular, angiotensin 1–7 (Ang-(1–7)), an anti-inflammatory heptapeptide, has been hypothesized to have beneficial effects. The aim of the present study was to test the effects of Ang-(1–7) infusion on the development and severity of septic shock.MethodsThis randomized, open-label, controlled study was performed in 14 anesthetized and mechanically ventilated sheep. Immediately after sepsis induction by bacterial peritonitis, animals received either Ang-(1–7) (n = 7) or placebo (n = 7) intravenously. Fluid resuscitation, antimicrobial therapy, and peritoneal lavage were initiated 4 h after sepsis induction. Norepinephrine administration was titrated to maintain mean arterial pressure (MAP) between 65 and 75 mmHg.ResultsThere were no differences in baseline characteristics between groups. Septic shock was prevented in 6 of the 7 animals in the Ang-(1–7) group at the end of the 24-h period. Fluid balance and MAP were similar in the two groups; however, MAP was achieved with a mean norepinephrine dose of 0.4 μg/kg/min in the Ang-(1–7) group compared to 4.3 μg/kg/min in the control group. Heart rate and cardiac output index were lower in the Ang (1–7) than in the control group, as were plasma interleukin-6 levels, and creatinine levels. Platelet count and PaO2/FiO2 ratio were higher in the Ang-(1–7) group. Mean arterial lactate at the end of the experiment was 1.6 mmol/L in the Ang-(1–7) group compared to 7.4 mmol/L in the control group.ConclusionsIn this experimental septic shock model, early Ang-(1–7) infusion prevented the development of septic shock, reduced norepinephrine requirements, limited interleukine-6 increase and prevented renal dysfunction.

Lack of change in the respiratory quotient during oxygen supply dependence in endotoxemic shock: a subanalysis of an experimental controlled study.

To evaluate if the reductions in systemic and renal oxygen consumption are associated with the development of evidence of anaerobic metabolism. This is a subanalysis of a previously published study. In anesthetized and mechanically ventilated sheep, we measured the respiratory quotient by indirect calorimetry and its systemic, renal, and intestinal surrogates (the ratios of the venous-arterial carbon dioxide pressure and content difference to the arterial-venous oxygen content difference. The Endotoxemic Shock Group (n = 12) was measured at baseline, after 60 minutes of endotoxemic shock, and after 60 and 120 minutes of fluid and norepinephrine resuscitation, and the values were compared with those of a Control Group (n = 12) without interventions. Endotoxemic shock decreased systemic and renal oxygen consumption (6.3 [5.6 - 6.6] versus 7.4 [6.3 - 8.5] mL/minute/kg and 3.7 [3.3 - 4.5] versus 5.4 [4.6 - 9.4] mL/minute/100g; p < 0.05 for both). After 120 minutes of resuscitation, systemic oxygen consumption was normalized, but renal oxygen consumption remained decreased (6.3 [5.9 - 8.2] versus 7.1 [6.1 - 8.6] mL/minute/100g; p = not significance and 3.8 [1.9 - 4.8] versus 5.7 [4.5 - 7.1]; p < 0.05). The respiratory quotient and the systemic, renal and intestinal ratios of the venous-arterial carbon dioxide pressure and content difference to the arterial-venous oxygen content difference did not change throughout the experiments. In this experimental model of septic shock, oxygen supply dependence was not associated with increases in the respiratory quotient or its surrogates. Putative explanations for these findings are the absence of anaerobic metabolism or the poor sensitivity of these variables in detecting this condition.

Hemodynamic resuscitation with fluids bolus and norepinephrine increases severity of lung damage in an experimental model of septic shock

ObjectiveHemodynamic resuscitation is considered a cornerstone of the initial treatment of septic shock. However, there is growing concern about its side effects. Our objective was to assess the relationship between fluid administration and norepinephrine infusion and the development of lung injury. DesignRandomized in vivo study in rabbits. SettingUniversity animal research laboratory. PatientsEighteen New Zealand rabbits. Control group (SHAM, n=6), Sepsis group with or without hemodynamic resuscitation (ETX-R, n=6; ETX-NR, n=6). InterventionsSepsis was induced by intravenous lipopolysaccharide administration and animals were followed-up for 4h. Hemodynamic resuscitation with Ringer lactate (20mL·kg−1) was administered and later norepinephrine was initiated 3h after sepsis induction. At the end, the left lung was excised. Main variables of interestAn indwelling arterial catheter and an esophageal Doppler were placed. Lung mechanics were monitored with side stream spirometry. Lung damage was analyzed by histopathological examination. ResultsThe SHAM group did not show hemodynamic or respiratory changes. Lipopolysaccharide administration aimed an increase in cardiac output and arterial hypotension. In the ETX-NR group, animals remained hypotensive until the end of the experiment. Resuscitation with fluids and norepinephrine reversed arterial hypotension. Compared to the ETX-NR group, the remaining lung of the ETX-R group showed greater accumulation of neutrophils and reactive type-II pneumocytes, thicker alveolar wall, alveolar hemorrhage and non-aerated pulmonary areas. Lung injury score was larger in the ETX-R group. ConclusionsIn our experimental study, following a strategy with bolus fluids and late norepinephrine used in the early phase of endotoxic septic shock has a negative influence on the development of lung injury.

Hemodynamic resuscitation with fluids bolus and norepinephrine increases severity of lung damage in an experimental model of septic shock.

Hemodynamic resuscitation is considered a cornerstone of the initial treatment of septic shock. However, there is growing concern about its side effects. Our objective was to assess the relationship between fluid administration and norepinephrine infusion and the development of lung injury. Randomized in vivo study in rabbits. University animal research laboratory. Eighteen New Zealand rabbits. Control group (SHAM, n=6), Sepsis group with or without hemodynamic resuscitation (ETX-R, n=6; ETX-NR, n=6). Sepsis was induced by intravenous lipopolysaccharide administration and animals were followed-up for 4h. Hemodynamic resuscitation with Ringer lactate (20mL·kg-1) was administered and later norepinephrine was initiated 3h after sepsis induction. At the end, the left lung was excised. An indwelling arterial catheter and an esophageal Doppler were placed. Lung mechanics were monitored with side stream spirometry. Lung damage was analyzed by histopathological examination. The SHAM group did not show hemodynamic or respiratory changes. Lipopolysaccharide administration aimed an increase in cardiac output and arterial hypotension. In the ETX-NR group, animals remained hypotensive until the end of the experiment. Resuscitation with fluids and norepinephrine reversed arterial hypotension. Compared to the ETX-NR group, the remaining lung of the ETX-R group showed greater accumulation of neutrophils and reactive type-II pneumocytes, thicker alveolar wall, alveolar hemorrhage and non-aerated pulmonary areas. Lung injury score was larger in the ETX-R group. In our experimental study, following a strategy with bolus fluids and late norepinephrine used in the early phase of endotoxic septic shock has a negative influence on the development of lung injury.

Recombinant short TNF-BD protein from smallpox virus is pharmacologically active in an experimental septic shock model

Фактор некроза опухолей (TNF) – один из основных цитокинов, медиаторов иммунной системы, обеспечивающих защиту организма человека от вирусных инфекций. В процессе эволюции антропогенный вирус натуральной оспы (Variola virus, VARV) освоил эффективные механизмы преодоления иммунологических барьеров человека, кодируя в своем геноме белки, способные взаимодействовать с рецепторами цитокинов организма-хозяина, блокируя таким образом их активность. В частности, ген G2R этого вируса кодирует белок CrmB, который эффективно связывает TNF человека и мышей. При этом данный белок является двухдоменным и наряду с TNF-связывающим N-концевым доменом содержит С-концевой хемокин-связывающий домен. При использовании методологии молекулярного клонирования нами ранее получен рекомбинантный бакуловирус, продуцирующий в клетках насекомых рекомбинантный белок CrmB вируса натуральной оспы (VARV-CrmB), и показан его TNF-нейтрализующий потенциал в различных тестах in vitro и in vivo. С целью снижения иммуногенности этого вирусного белка при его многократном введении для терапии хронических воспалительных заболеваний получена рекомбинантная плазмида, направляющая в клетках Escherichia coli биосинтез укороченного однодоменного TNF-связывающего (TNF-BD) белка VARV. Методом металл-хелатной аффинной хроматографии из клеток выделен рекомбинантный белок TNF-BD. Терапевтический потенциал белка TNF-BD изучен в экспериментальной модели септического шока, индуцированного в организме мышей введением бактериального липополисахарида (ЛПС). После индукции септического шока животным вводили разные дозы рекомбинантного белка TNF-BD и регистрировали их гибель в течение 7 сут. Все мыши, не получавшие препарат белка TNF-BD после инъекции ЛПС, погибли через 3 сут, а в группах животных, которым вводили TNF-BD, в зависимости от дозы этого белка выжили 30, 40 или 60 % мышей. Результаты исследования демонстрируют наличие специфической фармакологической активности у рекомбинантного белка TNF-BD, синтезированного в бактериальных клетках, в мышиной модели ЛПС-индуцированного септического шока.

Role of baroreflex during endotoxemic shock

Septic shock is a prevalent and life‐threatening condition which is often associated with major hypotension, resulting in multiple organs failure. The infusion of high doses of endotoxin lipopolysaccharide (LPS) is a well‐accepted experimental model of septic shock. Considering that baroreflex is a mandatory mechanism involved in the beat‐to‐beat hemodynamic regulation, we hypothesized herein that baroreflex plays a role buffering endotoxin‐induced hypothension in conscious freely moving rats. Thus, in the present study, we evaluated the cardiovascular outcomes of iv injection of endotoxin (1.5 mg.kg−1 or 2.5 mg.kg−1) or saline in male Wistar rats (280–350g, CEUA #2017.1.585.58.9). The baseline levels of mean arterial pressure and heart rate were not different among all groups. As expected, endotoxin induced hypotension (P&lt;0.001) and tachycardia (P &lt; 0.001). These effects were independent of dose. Interestingly, the drop of mean arterial pressure was significantly higher in rats previously submitted to baroreceptors afferents removal (4 days before recordings) than in (sham) rats with intact baroreceptor afferents (P&lt;0.001). The present data are consistent with the notion that baroreflex is key lessening endotoxin‐induced hypothension. The neural mechanisms involved in this control deserve further investigation aiming new strategic therapeutic tools to revert this critical condition.Support or Funding InformationFinancial support: FAPESP, CAPES and CNPqThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Inhalative and intravenous stimulation of soluble guanylate cyclase reduces pulmonary vascular resistance and increases cardiac output in experimental septic shock.

The effects of inhaled and intravenous application of a guanylate cyclase stimulator (BAY 41-8543) on pulmonary vascular resistance (PVR) and cardiac output (CO) were investigated in an experimental model of septic shock. Following induction of septic shock, anaesthetized pigs (n=31) were randomly place into two groups receiving different interventions. Animals in the first group received intravenous BAY 41-8543 (0.6 mg), inhalative BAY 41-8543 (6 mg) or a placebo. In the second group, the dosage of BAY 41-8543 was increased two-fold or combined with inhalation of nitric oxide (iNO). Intravenous and inhaled administration of BAY 41-8543 resulted in a significantly (P<0.05) reduced PVR and increased CO compared with the placebo. Increasing the dosage of BAY 41-8543 or combining it with iNO did not further decrease PVR. The results of the present study indicate that BAY 41-8543 effectively reduces PVR and increases CO in septic shock, through inhaled or intravenous routes of administration.

Role of protein tyrosine phosphatase 1B in cardiovascular diseases

Protein Tyrosine Phosphatase 1B (PTP1B) is mostly involved in negative regulation of signaling mediated by Tyrosine Kinase Receptors, especially the insulin and leptin receptors. This enzyme thus plays a major role in the development of diseases associated with insulin resistance, such as obesity and diabetes. PTP1B inhibition is currently considered as an attractive treatment of insulin resistance and associated metabolic disorders. In parallel, emerging evidence also suggests that PTP1B is widely expressed in cardiovascular tissues, notably in the heart and the endothelium, and that it could also be a potential treatment of several cardiovascular diseases. PTP1B is especially present in endothelial cells, and appears to contribute to endothelial dysfunction. Indeed, preclinical evidence shows that pharmacological inhibition of gene deletion of PTP1B reduces endothelial dysfunction in various cardiovascular diseases associated or not with insulin resistance. In parallel, because PTP1B also negatively modulates VEGF signaling, inhibition of this enzyme also tends to favor cardiac angiogenesis. Importantly, blocking PTP1B also results in beneficial effects on cardiac dysfunction and remodeling not only in metabolic diseases but also in the context of heart failure, thus this enzyme represents an attractive new target for the treatment of this disease. This beneficial effect in heart failure may to a large extent result from the endothelial protective and/or proangiogenic effects of PTP1B blockade. Finally, PTP1B inhibition also reduces cardiac dysfunction, but also systemic inflammation and mortality in experimental models of septic shock, and thus may also constitute a new treatment of this disease. Altogether, accumulating preclinical evidence suggests that PTP1B represents an interesting molecular target to treat both cardiovascular and metabolic diseases, which often share the same risk factors. This concept now deserves to be tested in clinical studies that should soon be possible with the current development of selective PTP1B inhibitors.

If Channel Inhibition With Ivabradine Does Not Improve Cardiac and Vascular Function in Experimental Septic Shock.

Previous studies have suggested that lowering heart rate (HR) by selective β1-blockers improves sepsis-induced cardiac and vascular dysfunction primarily by decreasing proinflammatory pathways. However, the impact of isolated heart rate reduction (HRR) on hemodynamics and inflammatory pathways remains unknown. The present study was designed to assess the effects of HRR by ivabradine, an If channel inhibitor, on cardiovascular function and inflammatory pathways in peritonitis-induced septic shock in rats. Randomized animal study. University research laboratory. Four hours after cecal ligation and puncture (CLP), Wistar rats were randomly allocated to the following groups: CLP (n = 8) and CLP + ivabradine (n = 8, administered per os 4 h after the surgery). Another eight Wistar male rats underwent sham operation. All rats received a continuous infusion of saline (10 mL kg h), analgesic (nalbuphine: 0.2 mg kg h), and antibiotics (imipenem and cilastatin sodium: 10 mg kg) 4 h after the surgery. Assessment at 18 h included hemodynamics, in vivo cardiac function by echocardiography, and ex vivo vasoreactivity by myography. Circulating cytokine levels (TNF-α, IL-6, and IL-10) were measured by ELISA, whereas cardiac and vascular protein expressions of NF-κB/IκBα/iNOS and Akt/eNOS were assessed by Western blotting. Compared with sham animals, CLP induced tachycardia, hypotension, decreased cardiac output, hyperlactatemia, and vascular hyporesponsiveness to vasopressors. Compared with the CLP group, adjunction of ivabradine decreased the HR without any impact on blood pressure, lactatemia, or vascular responsiveness to vasopressors. Adjunction of ivabradine to CLP rats had no impact on TNF-α, IL-6, and IL-10 cytokines, or on the protein expression levels of phosphorylated forms of NF-κB, Akt, eNOS, and degradation of IκBα in cardiac and vascular tissues. Isolated HRR by ivabradine in an experimental model of septic shock does not appear to be associated with any effect on the tested parameters of cardiac function or on vascular responsiveness to vasopressors. Moreover, in this setting, ivabradine does not alter the circulating levels of selected pro/anti-inflammatory cytokines or cardiac and vascular NF-κB/IκBα protein expression levels.

0117 : If channel inhibition with Ivabradine does not improve cardiac and vascular function in experimental septic shock

Objective Previous studies have suggested that lowering heart rate by selective β1-blockers improves sepsis-induced cardiac and vascular dysfunction primarily by decreasing pro-inflammatory pathways. However, the impact of isolated heart rate reduction on hemodynamics and inflammatory pathways remains unknown. The present study was designed to assess the effects of heart rate reduction by Ivabradine, an If channel inhibitor, on cardiovascular function and inflammatory pathways in peritonitis-induced septic shock in rats. Interventions four hours after cecal ligation and puncture (CLP), Wistar rats were randomly allocated to the following groups: CLP (n=8) and Ivabradine (n=8, administered per os at H4). Another eight Wistar male rats underwent sham operation. All rats received a continuous infusion of saline (10 ml.kg-1.h-1), analgesic (nalbuphin: 0.2 mg.kg-1.h-1) and antibiotics (Imipenem and Cilastatin Sodium: 10 mg/kg) four hours after the surgery. Assessment at 18 hours included hemodynamics, in vivo cardiac function by echocardiography and ex vivo vasoreactivity by myography. Cardiac and vascular expressions of NF-κB and eNOS/Akt/iNOS pathways was assessed by western blot. Results Compared to sham animals, CLP induced tachycardia, hypotension, decreased cardiac output, hyperlactatemia and vascular hyporesponsiveness to vasopressors. Compared to the CLP group, adjunction of Ivabradine decreased the heart rate without any impact on blood pressure, lactatemia or vascular responsiveness to vasopressors. Cardiac output was decreased albeit without reaching statistical significance. Ivabradine had no impact on cardiac and vascular protein expression levels of the phosphorylated forms of NF-κB, Akt, eNOS, iNOS. Conclusion Isolated reduction of heart rate by Ivabradine in an experimental model of septic shock does not result in any effect on cardiovascular function and inflammatory pathways. The author hereby declares no conflict of interest

Effects of ATP-sensitive potassium channel blockers on vascular hyporeactivity, mesenteric blood flow, and survival in lipopolysaccharide-induced septic shock model.

In this study, the possible therapeutic effects of various ATP-sensitive potassium channel (KATP) blockers (glibenclamide, repaglinide, 5-HD, HMR-1098) have been tested in experimental septic shock model. Rats were given lipopolysaccharide (1 mg·kg(-1)) to create experimental shock model and 4 h later, under 400 mg·kg(-1) chloral hydrate anesthesia, parameters such as blood pressure, mesenteric blood flow, the response of mesenteric circulation to phenylephrine (vasoconstrictor stimulation), and organ and oxidative damage were analyzed. Also 75 mg·kg(-1) lethal dose of lipopolysaccharide was given to mice and effects of KATP blockers on survival have been tested. Non-selective blocker glibenclamide with sulphonylurea structure and sarcolemmal KATP channel blocker HMR-1098, which have the similar chemical structure, have improved the pathological parameters such as decrease in mesenteric blood flow, vascular hyporeactivity, but could not prevent the decrease in blood pressure, and oxidative and organ damage that were observed in the shock model. Also, both blockers have decreased the mortality rate from 80% to 40%-50%. Similar (preventive) therapeutic effects were not observed with non-selective blocker repaglinide and mitochondrial KATP channel blocker 5-HD, which were non-sulphonylurea structure. As a result, only KATP channel blockers that have sulphonylurea structure can be a new therapeutic approach in septic shock.

Effects of endothelin and nitric oxide on cardiac muscle functions in experimental septic shock model.

We aimed to investigate the possible roles of nitric oxide (NO) and endothelin on the changes of cardiac muscle function in both hyper- and hypodynamic septic shock periods. Cecal ligation and puncture was performed in 50 Wistar albino rats to induce septic shock. Changes in atrium and right ventricle papillary muscle contractions, atrium beat rate, adrenergic and cholinergic responses in these tissues were evaluated in vitro. Atrium beat rate increased in hypodynamic period (p < 0.001) that was reversed by bosentan (p < 0.001) and N(G)-nitro-L-arginine methylester (L-NAME; p < 0.05). Atrium contractions decreased in both hyper- and hypodynamic periods (p < 0.001) that were partially ameliorated by bosentan in both periods (p < 0.01) and only in hypodynamic period by L-NAME (p < 0.001). L-NAME increased papillary muscle contractions in both periods (p < 0.01), but bosentan increased it only in hyperdynamic period (p < 0.01). Bosentan and L-NAME increased potency of isoproterenol on atrium beat rate in both periods and increased carbachol potency on atrium beat rate and atrium contraction amplitude only in hypodynamic period. Bosentan increased atrium contraction response to isoproterenol in hypodynamic period (p < 0.05). Papillary muscle contraction response to isoproterenol increased in hypodynamic period (p < 0.05). L-NAME increased papillary muscle contraction response to carbachol in both periods (p < 0.01, p < 0.05, respectively). These results show that NO and endothelin may play a role in positive inotropic and negative chronotropic effects for atrium in septic shock. Bosentan and L-NAME may change potency and efficacy of isoproterenol and carbachol via upregulation of adrenergic and cholinergic receptors and/or through post receptor factors.

Renal haemodynamic response to amino acids infusion in an experimental porcine model of septic shock.

Acute kidney injury (AKI) is common in sepsis. Treatments allowing maintenance of renal blood flow (RBF) could help to prevent AKI associated with renal hypoperfusion. Amino acids (AA) have been associated with an increase of RBF and glomerular filtration rate (GFR) in several species. The aim of this study was to evaluate the effects of an AA infusion on RBF and GFR in a porcine model of septic shock. A total of 17 piglets were randomly assigned into three groups: Sham (Sham, n = 5), sepsis without AA (S-NAA, n = 6), sepsis treated with AA (S-AA, n = 6). Piglets preparation included the placement of ultrasonic transit time flow probes around left renal artery for continuous RBF measurement; ureteral catheters for GFR and urine output evaluation; pulmonary artery catheter for cardiac output (CO) and pulmonary arterial pressure measurements. Mean arterial pressure (MAP) and renal vascular resistance (RVR) were also determined. Septic shock was induced with a live Pseudomonas aeruginosa infusion. Crystalloids, colloids and epinephrine infusion were used to maintain and restore MAP > 60 mmHg and CO > 80% from baseline. Renal haemodynamic did not change significantly in the Sham group, whereas RBF increased slightly in the S-NAA group. Conversely, a significant increase in RVR and a decrease in RBF and GFR were observed in the S-AA group. AA infusion was associated with a higher requirement of epinephrine [340.0 (141.2; 542.5) mg vs. 32.5 (3.8; 65.0) mg in the S-NAA group P = 0.044]. An infusion of amino acids impaired renal haemodynamics in this experimental model of septic shock.

Attenuation of Responses to Endotoxin by the Triggering Receptor Expressed on Myeloid Cells-1 Inhibitor LR12 in Nonhuman Primate

The triggering receptor expressed on myeloid cells-1 is an immunoreceptor that amplifies the inflammatory response mediated by toll-like receptors engagement. Triggering receptor expressed on myeloid cells-1 inhibitory peptides such LR12 have been shown to prevent hyperresponsiveness and death in several experimental models of septic shock. Twelve adult male Cynomolgus (Macaca fascicularis) monkeys exposed to an intravenous bolus of endotoxin (10 μg/kg) were randomized to receive LR12 or placebo (n = 6 per group) as an initial intravenous bolus followed by an 8-h continuous intravenous infusion. An additional group of four only received vehicle infusion. Vital signs were monitored for 8 h. Blood was sampled at H0, 1, 2, 4, and 8 for analysis of clinical chemistries, leukocyte count, coagulation parameters, and cytokine plasma concentration. LR12 showed no effect on heart rate and body temperature. By contrast to the placebo group, which experienced a 25 to 40% blood pressure decrease after endotoxin administration, LR12-treated monkeys remained normotensive. Endotoxin induced leukopenia at 2 h (mean leukocyte count, 7.62 g/l vs. 21.1 at H0), which was attenuated by LR12. LR12 also attenuated cytokine production. The triggering receptor expressed on myeloid cells-1 inhibitor LR12 is able to mitigate endotoxin-associated clinical and biological alterations, with no obvious side effects. This study paves the way for future phases Ia and Ib trials in humans.

Effect of Nutrisim© on Endotoxic Shock Induced by Lipopolysaccharide from Escherichia coli: 0111:B4 in Rats: Structural Study of Liver, Kidney and Lung

Bacterial Lipopolysaccharide (LPS) is a glycolipid component of the cell wall of Gram-negative bacteria and is an endotoxin implicated in triggering sepsis and septic shock. Sepsis and its sequelae represent a continuum of clinical syndrome encompassing systemic inflammation, coagulopathy, abnormalities of the renal, hepatic, pulmonary, and hematologic systems followed by multi-organ failure. NutriSim©, a nutritional supplement, has previously been tested in an experimental model of septic shock; for example, a single dose of NutriSim© diminishes significantly the production of serum proin fl ammatory cytokines, attenuates the oxidative stress markers and preserves membrane fl uidity in rat liver mitochondria. Therefore, the aim of the present study was to evaluate the protective effect of NutriSim© on survival and histological alterations in liver, kidney and lung associated with endotoxic shock induced by LPS. The results in this work showed that treatment with a single dose of NutriSim© 15 min prior or after LPS challenge, effectively protects the morphological damage in vital organs such as liver, kidney and lung, and improved the survival rate of LPS-treated rats. In conclusion, a single dose of NutriSim© in a septic shock model induced by LPS appears to effectively protect vital organ damage from morphological injury and reduces mortality.

AT1 receptor-associated protein and septic shock-induced vascular hyporeactivity: another 'magic bullet' in the pipe?

Septic shock remains an important issue for critical care physicians. Despite significant advances in the knowledge of its pathophysiology, new effective therapeutic approaches have yet to emerge. Consequently, research on its pathophysiology must be continued. In a recent study, Katharina Mederle and colleagues explored the impact of angiotensin 1 receptor-associated protein 1 (Arap1) deficiency on vascular hyporesponsiveness in an experimental model of septic shock. The authors demonstrate that experimental septic shock downregulates Arap1 expression, which in turn contributes to vascular hyporesponsiveness to angiotensin II.

The aPC treatment improves microcirculation in severe sepsis/septic shock syndrome

BackgroundThe role of recombinant activated protein C (aPC) during sepsis is still controversial. It showed anti-inflammatory effect and improved the microvascular perfusion in experimental models of septic shock. The present study was aimed at testing the hypothesis that recombinant aPC therapy improves the microcirculation during severe sepsis.MethodsProspective observational study on patients admitted in a 12-beds intensive care unit of a university hospital from July 2010 to December 2011, with severe sepsis and at least two sepsis-induced organ failures occurring within 48 hours from the onset of sepsis, who received an infusion of aPC (24 mcg/kg/h for 96 hours) (aPC group). Patients with contraindications to aPC administration were also monitored (no-aPC group).At baseline (before starting aPC infusion, T0), after 24 hours (T1a), 48 hours (T1b), 72 hours (T1c) and 6 hours after the end of aPC infusion (T2), general clinical and hemodynamic parameters were collected and the sublingual microcirculation was evaluated with sidestream dark-field imaging. Total vessel density (TVD), perfused vessel density (PVD), De Backer score, microvascular flow index (MFIs), the proportion of perfused vessels (PPV) and the flow heterogeneity index (HI) were calculated for small vessels. The perfused boundary region (PBR) was measured as an index of glycocalyx damage. Variables were compared between time points and groups using non parametric or parametric statistical tests, as appropriate.ResultsIn the 13 aPC patients mean arterial pressure (MAP), base excess, lactate, PaO2/FiO2 and the Sequential Organ Failure Assessment (SOFA) score significantly improved over time, while CI and ITBVI did not change. MFIs, TVD, PVD, PPV significantly increased over time and the HI decreased (p < 0.05 in all cases), while the PBR did not change. No-aPC patients (n = 9) did not show any change in the microcirculation over time. A positive correlation was found between MFIs and MAP. TVD, PVD and De Backer score negatively correlated with norepinephrine dose, and the SOFA score negatively correlated with MFIs, TVD and PVD.ConclusionsaPC significantly improves the microcirculation in patients with severe sepsis/septic shock.Trial registrationNCT01806428

Humane End Points in Experimental Models of Septic Shock

Humane End Points in Experimental Models of Septic Shock

Evaluation of left ventricular systolic function revisited in septic shock

The meta-analysis of Huang and coworkers failed to find any evidence for a protective effect of a decreased left ventricular (LV) ejection fraction (EF). These results have to be interpreted with caution since in most studies included in the meta-analysis patients with LV systolic dysfunction received inotropic drugs. We have some arguments suggesting that such a treatment may improve macrocirculation and microcirculation and finally prognosis. This paper allows us to clarify the meaning of LV function in septic shock patients. In all experimental models of septic shock using the load-independent parameter of LV systolic function, LV contractility impairment, called septic cardiomyopathy, has been reported to be constant. However, LVEF reflects the coupling between LV contractility and LV afterload. A normal LVEF may be observed when the arterial tone is severely depressed, as in septic shock, despite seriously impaired intrinsic LV contractility. LV systolic function, evaluated using an echocardiograph or another device, is then more a reflection of arterial tone (and its correction) than of intrinsic LV contractility. As a consequence, the incidence of LV systolic dysfunction greatly depends on the time of the evaluation, reflecting the fact that, during resuscitation and treatment, vasoplegia and then LV afterload are corrected, thus unmasking septic cardiomyopathy. With these points in mind, we can revisit the results of Margaret Parker's original study: it is not that the patients with a low EF survived better, but rather that the other patients had an increased mortality due to persistent profound vasoplegia.

The effects of carnosine in an experimental rat model of septic shock

BackgroundTo examine the effect of carnosine on liver function and histological findings in experimental septic shock model, 24 Sprague-Dawley rats were used.Material/MethodsRats were divided into control, septic shock, and carnosine-treated septic shock groups. Femoral vein and artery catheterization were performed on all rats. Rats in the control group underwent laparotomy and catheterization; in the test groups, cecal ligation-perforation and bladder cannulation were added. Rats in the treatment group received a single intraperitoneal (IP) injection of 250 mg/kg carnosine 60 minutes after cecal ligation-perforation. Rats were monitored for blood pressure, heart rate, and body temperature to assess the postoperative septic response, and body fluids were replaced as necessary. At the end of 24 hours, rats were sacrificed and liver samples were collected.ResultsStatistically significant improvements were observed in liver function, tissue and serum MDA levels, and histological findings in rats treated with carnosine, compared to rats with untreated sepsis. HB and HCT values did not change significantly during the course of the experiment. Rats exposed to septic shock and treated with carnosine exhibited decreased sinusoidal dilatation and cellular inflammation into the portal region, compared to the sepsis group; the livers of rats in this group had near-normal histological structure.ConclusionsWe conclude that carnosine may be an effective treatment for oxidative damage due to liver tissue perfusion defects in cases of septic shock.