Rat Model Of Shock Research Articles

Apoptotic Cell-Based Therapy for the Modification of the Inflammatory Response to Hemorrhagic Shock.

Many trauma patients die from hemorrhagic shock in the military and civilian settings. Although two-thirds of hemorrhagic shock victims die of reasons other than exsanguination, such as the consequent cytokine storm, anti-inflammatory therapies failed to be utilized. Apoptotic cell-based treatments enhance innate ability to exert systemic immunomodulation as demonstrated in several clinical applications and hence might present a novel approach in hemorrhagic shock treatment. Twenty-two rats underwent a pressure-controlled hemorrhagic shock model and followed up for 24 hours. An infusion of apoptotic cells (Allocetra-OTS, Enlivex Therapeutics Ltd, Nes Ziona, Israel) was administered to the treatment group. Hemodynamics, blood counts, biochemistry findings, and cytokine profile were compared to a saline-resuscitated control group. The treatment group's mean arterial pressure decreased from 94.8 mmHg to 28.2 mmHg, resulting in an 8.13 mg/dL increase in lactate and a 1.9 g/L decrease in hemoglobin, similar to the control group. White blood cells and platelets decreased more profoundly in the treatment group. A similar cytokine profile after 24 hours was markedly attenuated in the treatment group 2 hours after bleeding. Levels of pro-inflammatory cytokines such as interleukin (IL)-1a (28.4 pg/mL vs. 179.1 pg/mL), IL-1b (47.4 pg/mL vs. 103.9 pg/mL), IL-6 (526.2 pg/mL vs. 3492 pg/mL), interferon γ (11.4 pg/mL vs. 427.9 pg/mL), and tumor necrosis factor α (19.0 pg/mL vs. 31.7 pg/mL) were profoundly lower in the treatment group. In a pressure-control hemorrhagic shock model in rats, apoptotic cell infusion showed preliminary signs of a uniform attenuated cytokine response. Apoptotic cell-based therapies might serve as a novel immunomodulatory therapy for hemorrhagic shock.

Apelin-13 administration allows for norepinephrine sparing in a rat model of cecal ligation and puncture-induced septic shock

BackgroundInfusion of exogenous catecholamines (i.e., norepinephrine [NE] and dobutamine) is a recommended treatment for septic shock with myocardial dysfunction. However, sustained catecholamine infusion is linked to cardiac toxicity and impaired responsiveness. Several pre-clinical and clinical studies have investigated the use of alternative vasopressors in the treatment of septic shock, with limited benefits and generally no effect on mortality. Apelin-13 (APL-13) is an endogenous positive inotrope and vasoactive peptide and has been demonstrated cardioprotective with vasomodulator and sparing life effects in animal models of septic shock. A primary objective of this study was to evaluate the NE-sparing effect of APL-13 infusion in an experimental sepsis-induced hypotension.MethodsFor this goal, sepsis was induced by cecal ligation and puncture (CLP) in male rats and the arterial blood pressure (BP) monitored continuously via a carotid catheter. Monitoring, fluid resuscitation and experimental treatments were performed on conscious animals. Based on pilot assays, normal saline fluid resuscitation (2.5 mL/Kg/h) was initiated 3 h post-CLP and maintained up to the endpoint. Thus, titrated doses of NE, with or without fixed-doses of APL-13 or the apelin receptor antagonist F13A co-infusion were started when 20% decrease of systolic BP (SBP) from baseline was achieved, to restore SBP values ≥ 115 ± 1.5 mmHg (baseline average ± SEM).ResultsA reduction in mean NE dose was observed with APL-13 but not F13A co-infusion at pre-determined treatment time of 4.5 ± 0.5 h (17.37 ± 1.74 µg/Kg/h [APL-13] vs. 25.64 ± 2.61 µg/Kg/h [Control NE] vs. 28.60 ± 4.79 µg/Kg/min [F13A], P = 0.0491). A 60% decrease in NE infusion rate over time was observed with APL-13 co-infusion, (p = 0.008 vs NE alone), while F13A co-infusion increased the NE infusion rate over time by 218% (p = 0.003 vs NE + APL-13). Associated improvements in cardiac function are likely mediated by (i) enhanced left ventricular end-diastolic volume (0.18 ± 0.02 mL [Control NE] vs. 0.30 ± 0.03 mL [APL-13], P = 0.0051), stroke volume (0.11 ± 0.01 mL [Control NE] vs. 0.21 ± 0.01 mL [APL-13], P < 0.001) and cardiac output (67.57 ± 8.63 mL/min [Control NE] vs. 112.20 ± 8.53 mL/min [APL-13], P = 0.0036), and (ii) a reduced effective arterial elastance (920.6 ± 81.4 mmHg/mL/min [Control NE] vs. 497.633.44 mmHg/mL/min. [APL-13], P = 0.0002). APL-13 administration was also associated with a decrease in lactate levels compared to animals only receiving NE (7.08 ± 0.40 [Control NE] vs. 4.78 ± 0.60 [APL-13], P < 0.01).ConclusionAPL-13 exhibits NE-sparing benefits in the treatment of sepsis-induced shock, potentially reducing deleterious effects of prolonged exogenous catecholamine administration.

A rat model of multicompartmental traumatic injury and hemorrhagic shock induces bone marrow dysfunction and profound anemia.

Severe trauma is associated with systemic inflammation and organ dysfunction. Preclinical rodent trauma models are the mainstay of postinjury research but have been criticized for not fully replicating severe human trauma. The aim of this study was to create a rat model of multicompartmental injury which recreates profound traumatic injury. Male Sprague-Dawley rats were subjected to unilateral lung contusion and hemorrhagic shock (LCHS), multicompartmental polytrauma (PT) (unilateral lung contusion, hemorrhagic shock, cecectomy, bifemoral pseudofracture), or naïve controls. Weight, plasma toll-like receptor 4 (TLR4), hemoglobin, spleen to body weight ratio, bone marrow (BM) erythroid progenitor (CFU-GEMM, BFU-E, and CFU-E) growth, plasma granulocyte colony-stimulating factor (G-CSF) and right lung histologic injury were assessed on day 7, with significance defined as p values <0.05 (*). Polytrauma resulted in markedly more profound inhibition of weight gain compared to LCHS (p = 0.0002) along with elevated plasma TLR4 (p < 0.0001), lower hemoglobin (p < 0.0001), and enlarged spleen to body weight ratios (p = 0.004). Both LCHS and PT demonstrated suppression of CFU-E and BFU-E growth compared to naïve (p < 0.03, p < 0.01). Plasma G-CSF was elevated in PT compared to both naïve and LCHS (p < 0.0001, p = 0.02). LCHS and PT demonstrated significant histologic right lung injury with poor alveolar wall integrity and interstitial edema. Multicompartmental injury as described here establishes a reproducible model of multicompartmental injury with worsened anemia, splenic tissue enlargement, weight loss, and increased inflammatory activity compared to a less severe model. This may serve as a more effective model to recreate profound traumatic injury to replicate the human inflammatory response postinjury.

Abstract 3093: Can Inhibiting Ferroptosis And Subsequent Endothelial Glycocalyx Shedding Reduce The Morbidity And Mortality Of Hemorrhagic Shock?

Background: Trauma patients with hemorrhagic shock accounts for 40% of preventable death. Shock-induced endotheliopathy has garnered interest recently and one aspect of this, endothelial glycocalyx shedding, has shown to promote coagulopathy following hemorrhage. Ferroptosis is an iron dependent, non-apoptotic form of controlled cell death triggered by the oxidation of membrane phospholipids. Liproxstatin-1 (LPX1) is an inhibitor of this process and can protect against oxidative damage to the endothelial cell membrane and subsequent shedding of glycocalyx. We hypothesized that LPX1 would reduce endothelial glycocalyx damage in hemorrhagic shock. Methods: A rat model of hemorrhagic shock and resuscitation was used to assess glycocalyx disruption in the lungs via fluorescent-labeled wheat germ agglutinin staining in frozen tissue and by Syndecan-1 ELISA on plasma samples. A control group (n=5) resuscitated only with Lactated Ringer’s solution, following hemorrhage and resuscitation (H/R) was compared against an experimental group (n=5) that received LPX1 following hemorrhage and before resuscitation. Results: Glycocalyx shedding (assessed by an increase in plasma Syndecan-1 levels) was prevented in the LPX1 treated group compared to control group. Lung tissue staining of the glycocalyx also showed a greater glycocalyx level in the LPX1 group than in the control (40.4 vs 36.3 arbitrary units). Additionally, LPX1 treated animals were able to sustain a higher mean arterial pressure (82 vs 45mmHg), and oxygen saturation throughout the resuscitation period measured at 15 and 30 minutes following LPX1 infusion (98.4% SpO2 vs. 99.0% SpO2 at 30 minutes resuscitation). Conclusions: Ferroptosis inhibitor LPX1 can reduce morbidity acutely during hemorrhagic shock and can protect the endothelial cell glycocalyx from oxidative damage due to its ability to slow the generation of reactive oxygen species and lipid hydroperoxides.

Cholinergic anti-inflammatory pathway confers protective effects in septic shock rats

Background: Septic shock can lead to multiple organ dysfunction. The cholinergic anti-inflammatory pathway is known to prevent organ damage from infection by modulating the inflammatory response. However, the modulatory capacity of cholinergic anti-inflammatory pathways in septic shock remains unclear. Methods: Cecal ligation and puncture (CLP) was used to establish a rat model of septic shock. Bilateral cervical vagal nerve isolation, dual cervical vagotomy, and vagus nerve stimulation (VNS) were used to inhibit or activate cholinergic anti-inflammatory pathways. Tacrine and α-bungarotoxin groups were used to mimic the activation and shutdown of cholinergic anti-inflammatory pathways. The survival status, hemodynamic indicators, inflammatory cytokine content, and inflammatory response of liver and kidney tissues of the rats were detected. Results: Dual cervical vagotomy significantly exacerbated the hepatic (p &lt; 0.05) and renal (p &lt; 0.05) impairment in septic shock rats relative to the sham-operated group. Tacrine, a cholinergic potentiator, significantly alleviated liver (p &lt; 0.05) and kidney (p &lt; 0.05) damage in septic shock rats. Dual cervical vagotomy significantly promoted the expression of pro-inflammatory factors caused by septic shock in rat liver and kidney tissues (p &lt; 0.05), while Tacrine treatment inhibited the increase of inflammatory factors (p &lt; 0.05). Conclusions: Activation of the cholinergic anti-inflammatory pathway exerts protective effects on multiple organ dysfunction caused by septic shock. The cholinergic enhancer, Tacrine, and VNS effectively ameliorated liver and kidney damage, improved hemodynamic indicators, and enhanced survival rates in septic shock rats.

Developing a Clinically Relevant Hemorrhagic Shock Model in Rats.

Over the recent decades, the development of animal models allowed us to better understand various pathologies and identify new treatments. Hemorrhagic shock, i.e., organ failure due to rapid loss of a large volume of blood, is associated with a highly complex pathophysiology involving several pathways. Numerous existing animal models of hemorrhagic shock strive to replicate what happens in humans, but these models have limits in terms of clinical relevance, reproducibility, or standardization. The aim of this study was to refine these models to develop a new model of hemorrhagic shock. Briefly, hemorrhagic shock was induced in male Wistar Han rats (11-13 weeks old) by a controlled exsanguination responsible for a drop in the mean arterial pressure. The next phase of 75 min was to maintain a low mean arterial blood pressure, between 32 mmHg and 38 mmHg, to trigger the pathophysiological pathways of hemorrhagic shock. The final phase of the protocol mimicked patient care with an administration of intravenous fluids, Ringer Lactate solution, to elevate the blood pressure. Lactate and behavioral scores were assessed 16 h after the protocol started, while hemodynamics parameters and plasmatic markers were evaluated 24 h after injury. Twenty-four hours post-hemorrhagic shock induction, the mean arterial and diastolic blood pressure were decreased in the hemorrhagic shock group (p< 0.05). Heart rate and systolic blood pressure remained unchanged. All organ damage markers were increased with the hemorrhagic shock (p < 0.05). The lactatemia and behavioral scores were increased compared to the sham group (p < 0.05). In conclusion, we demonstrated that the protocol described here is a relevant model of hemorrhagic shock that can be used in subsequent studies, particularly to evaluate the therapeutic potential of new molecules.

Magnesium hydride attenuates intestinal barrier injury during hemorrhage shock by regulating neutrophil extracellular trap formation via the ROS/MAPK/PAD4 pathway

Magnesium hydride (MgH2) is a hydrogen storage material that is known for its high capacity and safety and is capable of releasing hydrogen in a controlled manner when administered orally. This release of hydrogen has been associated with a range of biological effects, including anti-inflammatory properties, antioxidant activity, and protection of the intestinal barrier. Previous research has shown that neutrophil extracellular traps (NETs) play a role in the dysfunction of the intestinal barrier in conditions such as sepsis and critical illnesses. However, it remains unclear as to whether MgH2 can protect the intestinal barrier by inhibiting NET formation, and the underlying mechanisms have yet to be elucidated. A rat model of hemorrhagic shock was created, and pretreatment or posttreatment procedures with MgH2 were performed. After 24 h, samples from the small intestine and blood were collected for analysis. In vitro, human neutrophils were incubated with either phorbol-12-myristate-13-acetate (PMA) or MgH2. Reactive oxygen species generation and the expression of key proteins were assessed. The results demonstrated that MgH2 administration led to a decrease in inflammatory cytokines in the serum and mitigated distant organ dysfunction in rats with HS. Furthermore, MgH2 treatment reversed histopathological damage in the intestines, improved intestinal permeability, and enhanced the expression of tight junction proteins (TJPs) during HS. Additionally, MgH2 treatment was found to suppress NET formation in the intestines. In vitro pretreatment with MgH2 alleviated intestinal monolayer barrier disruption that was induced by NETs. Mechanistically, MgH2 pretreatment reduced ROS production and NET formation, inhibited the activation of ERK and p38, and suppressed the expression of the PAD4 protein. These findings indicated that MgH2 may inhibit NET formation in a ROS/MAPK/PAD4-dependent manner, which reduces NET-related intestinal barrier damage, thus offering a novel protective role in preventing intestinal barrier dysfunction during HS.

Venoarterial Extracorporeal Membrane Oxygenation Implementation in Septic Shock Rat Model.

Septic shock, a global health concern, boasts high mortality rates. Research exploring the efficacy of venoarterial extracorporeal membrane oxygenation (VA-ECMO) in septic shock remains limited. Our study aimed to establish a rodent model employing VA-ECMO in septic shock rats, assessing the therapeutic impact of VA-ECMO on septic shock. Nineteen Sprague-Dawley rats were randomly assigned to sham, septic shock, and (septic shock + VA-ECMO; SSE) groups. Septic shock was induced by intravenous lipopolysaccharides, confirmed by a mean arterial pressure drop to 25-30% of baseline. Rats in the SSE group received 2 hours of VA-ECMO support and 60 minutes of post-weaning ventilation. Sham and septic shock groups underwent mechanical ventilation for equivalent durations. Invasive mean arterial pressure monitoring, echocardiographic examinations, and blood gas analysis revealed the efficacy of VA-ECMO in restoring circulation and ensuring adequate tissue oxygenation in septic shock rats. Post-experiment pathology exhibited the potential of VA-ECMO in mitigating major organ injury. In summary, our study successfully established a stable septic shock rat model with the implementation of VA-ECMO, offering a valuable platform to explore molecular mechanisms underlying VA-ECMO's impact on septic shock.

Prolyl hydroxylase domain inhibitor is an effective pre-hospital pharmaceutical intervention for trauma and hemorrhagic shock

Pre-hospital potentially preventable trauma related deaths are mainly due to hypoperfusion-induced tissue hypoxia leading to irreversible organ dysfunction at or near the point of injury or during transportation prior to receiving definitive therapy. The prolyl hydroxylase domain (PHD) is an oxygen sensor that regulates tissue adaptation to hypoxia by stabilizing hypoxia inducible factor (HIF). The benefit of PHD inhibitors (PHDi) in the treatment of anemia and lactatemia arises from HIF stabilization, which stimulates endogenous production of erythropoietin and activates lactate recycling through gluconeogenesis. The results of this study provide insight into the therapeutic roles of MK-8617, a pan-inhibitor of PHD-1, 2, and 3, in the mitigation of lactatemia in anesthetized rats with polytrauma and hemorrhagic shock. Additionally, in an anesthetized rat model of lethal decompensated hemorrhagic shock, acute administration of MK-8617 significantly improves one-hour survival and maintains survival at least until 4 h following limited resuscitation with whole blood (20% EBV) at one hour after hemorrhage. This study suggests that pharmaceutical interventions to inhibit prolyl hydroxylase activity can be used as a potential pre-hospital countermeasure for trauma and hemorrhage at or near the point of injury.

Abstract 376: Comparison of Pre and Post Conditioning With Poloxamer 188 in Rat Model of Severe Hemorrhagic Shock

Background: Hemorrhagic shock remains a leading cause of morbidity and mortality after trauma. Poloxamer (P) 188, an FDA-approved copolymer-based cell membrane stabilizer, is a nonionic triblock copolymer believed to prevent cellular injury after ischemia and reperfusion. While post conditioning may be used in a broad range of scenarios, pre-conditioning may add improved efficacy in scenarios where hemorrhage can be expected, the peri-operative period. We have previously demonstrated prolonged survival with P188 post-conditioning however without complete rescue, here we hypothesize pre-conditioning would further improve survival. Methods: 35 male Sprague Dawley rats (564+/-73 g) were anesthetized, ventilated and instrumented. All rats underwent rapid controlled blood loss of 40% estimated blood volume over 30 min, followed by prolonged permissive hypotension for 60 min before re-transfusion of the lost blood to euvolemia and up to 6 hrs of monitoring under general anesthesia. Rats were then randomized to 3 groups: 10 rats received a 0.8 cc iv bolus of 250mg/kg P188 15min before hemorrhage (pre), 12 rats received the same dose of P188 after hemorrhage (post), and 13 control rats only received 0.8 cc vehicle. Primary endpoint was survival time from the start of hemorrhage. Data are median and IQ range; statistics: Kruskal-Wallis and Chi-Square tests, *p&lt;0.05. Results: P188 administration immediately after hemorrhage significantly improved median survival time compared to both the pre and control groups [post *245 (49, 314) min vs. control group; 53 (32-60), vs pre; 59 (24-70) min, p = 0.0174, 0.00045, respectively]. However, there was no significant differences in survival time between pre and control grouyps and there were no differences in survival rate at 6 hours (pre; 0% vs post; 8% vs control; 7%). Conclusion: A bolus of P188 given immediately after a severe hemorrhagic insult prolonged survival time significantly. However, administration of P188 15 min before hemorrhage did not produce a significant prolongation of survival time.P188 is a highly promising compound whose dose, application timing and application duration in severe hemorrhagic shock require more research.

Evaluation of Mesenteric Microvascular Hyperpermeability Following Hemorrhagic Shock Using Intravital Microscopy.

Intravital microscopy is a powerful tool for evaluating vascular hyperpermeability in various vascular beds. Hemorrhagic shock after traumatic injury is known to induce microvascular hyperpermeability, life-threatening edema, and microcirculatory perfusion disturbances. Here we describe the microsurgical and imaging methods to study mesenteric vascular hyperpermeability using intravital microscopy, in a rat model of hemorrhagic shock. In this protocol, hemorrhagic shock is induced by controlled withdrawal of blood to reduce the mean arterial pressure (MAP) to 40mmHg for 60min, followed by resuscitation for 60min. To study the changes in vascular permeability, the rats are given FITC-albumin, a fluorescent tracer, intravenously. The FITC-albumin flux across the vessel wall is measured in mesenteric postcapillary venules by determining intravascular and extravascular fluorescence intensity under intravital microscopy. Intravital microscopic evaluation of high molecular weight FITC-albumin permeability is a reliable indicator of microvascular hyperpermeability.

Effects of Different Crystalloid Fluids on Renal Tissue in an Experimental Model of Hemorrhagic Shock.

The type of fluid that should be used in uncontrollable hemorrhages remains an area of research. This study was designed to compare the effects of resuscitation with Ringer's lactate (RL) solution versus a normal saline (NS) solution on hemodynamics, renal tissue histopathology, coagulation, and apoptosis in a rat model of hemorrhagic shock. The study employed groups designated as the control, hemorrhage, NS, and RL groups. Heart rate, mean arterial pressure, and respiratory rate were monitored. Annexin A5 values were assayed, rotational thromboelastometry analysis was performed, and excised kidney tissue samples were histopathologically analyzed. Blood pressure levels were found to be significantly higher in the control group than those measured in the other groups. While the clotting time (CT) and clot formation time (CFT) in the hemorrhage group were significantly longer than those in the control and RL groups, the CT and CFT measured in the control group were significantly shorter compared to the RL group. The mean Annexin A5 level was in the hemorrhage group, which was significantly higher compared to the other groups. In the renal histopathological evaluation, the scores of proximal tubular injury, distal renal tubular injury, and interstitial renal tubular injury were found to be significantly lower in the control group compared to the other groups. This study demonstrated that NS or RL can be used safely to improve the hemodynamic symptoms resulting from hemorrhagic shock as a means to reduce apoptosis, and to decrease findings in favor of coagulopathy in bedside coagulation tests during the early stages of hemorrhagic shock until the time of starting a blood transfusion.

Involvement of CD44 and MAPK14-mediated ferroptosis in hemorrhagic shock.

To elucidate the induction of ferroptotic pathways and the transcriptional modulation of pivotal genes in the context of hemorrhagic shock. The R software was used to analyze the GSE64711 dataset, isolating genes relevant to ferroptosis. Enrichment analyses and protein interaction networks were assembled. Using WGCNA hub genes were identified and intersected with ferroptosis-related genes, highlighting hub genes CD44 and MAPK14. In a rat hemorrhagic shock model, cardiac ROS, Fe2+, MDA, and GSH levels were assessed. Key ferroptotic proteins (SLC7A11/GPX4) in myocardial tissues were examined via western blot. Hub genes, CD44 and MAPK14, expressions were confirmed through immunohistochemistry. Analyzing the GSE64711 dataset revealed 337 differentially expressed genes, including 12 linked to ferroptosis. Enrichment analysis highlighted pathways closely related to ferroptosis. Using Genemania, we found these genes mainly affect ROS metabolism and oxidative stress response. WGCNA identified CD44 and MAPK14 as hub genes. Rat myocardial tissue validation showed significant cardiac damage and elevated ROS and MDA levels, and decreased GSH levels in the hemorrhagic shock model. The ferroptotic pathway SLC7A11/GPX4 was activated, and immunohistochemistry showed a significant increase in the expression levels of CD44 and MAPK14 in the hemorrhagic shock rat model. We demonstrated the presence of tissue ferroptosis in hemorrhagic shock by combining bioinformatics analysis with in vivo experimentation. Specifically, we observed the activation of the SLC7A11/GPX4 ferroptotic pathway. Further, CD44 and MAPK14 were identified as hub genes in hemorrhagic shock.

Improvement of hemodynamics in mesenteric microcirculation in septic shock rats by anisodamine and anisodine

Anisodamine and anisodine have been used in treatment of septic shock, but the underlying mechanism are still unclear. In the present study, the effects of anisodamine hydrobromide (Ani HBr) and anisodine hydrobromide (AT3) on the mesenteric hemodynamics in septic shock rats were performed. The rat model of septic shock was established by intravenous tail vein injection of 5 ​mg/kg lipopolysaccharide (LPS), and then treated with Ani HBr, AT3, racemic anisodine (Race Ani) or atropine (ATP). The mesenteric microcirculation was observed using the intravital microscopy. Then, the flow pattern of the microcirculation, leukocytes dynamics and the plasma levels of cytokines tumor necrosis factor (TNF)-α and interleukin-6 (IL-6) were analyzed. Compared with the control rats, reduced mean arterial pressure, increased heart rate, and slow microcirculatory blood flow was found in septic shock rats. The main abnormal flow patterns were intermittent and reciprocating motions. Ani HBr, AT3, Race Ani and ATP elevated the mean arterial pressure and reduced heart rate in septic shock rats. Ani HBr and AT3 not only restored the velocity of microcirculatory blood flow and improved the microcirculatory flow patterns, but also suppressed the LPS-induced leukocyte-endothelium interaction and releases of TNF-α and IL-6. Therefore, Ani HBr and AT3 improves hemodynamics in both macro- and microcirculation, which provide a novel experimental basis for exploring the mechanobiological mechanisms in septic shock.

Effects of Mdivi-1 on Extending the Golden Treatment Time following Hemorrhagic Shock in Hot Environment in Rats.

It is found that a hot environment aggravates hemorrhagic shock-induced internal environment and organ dysfunction. Meanwhile mitochondria show over-fission. Whether inhibition of mitochondrial fission benefits from the early treatment of hemorrhagic shock under a hot environment is unclear. An uncontrolled hemorrhagic shock model in rats is used, and the effects of mitochondrial fission inhibitor mdivi-1 on mitochondrial function, organ function, and survival rate of rats are measured. The results show that 0.1-3 mg/kg mdivi-1 antagonizes hemorrhagic shock-induced mitochondrial fragment. In addition, mdivi-1 improves mitochondrial function, and alleviates hemorrhagic shock-induced oxidative stress and inflammation under a hot environment. Further studies show that 0.1-3 mg/kg Mdivi-1 reduces blood loss, and maintains a mean artery pressure (MAP) of 50-60 mmHg before bleeding-stops after hemorrhagic shock, compared with single Lactate Ringer's (LR) resuscitation. Notably, 1 mg/kg of Mdivi-1 extends the time of hypotensive resuscitation to 2-3 h. During 1 or 2 h of ligation, Mdivi-1 prolongs survival time and protects vital organ function by rescuing mitochondrial morphology and improving mitochondrial function. These results suggest Mdivi-1 is suitable for the early treatment of hemorrhagic shock under a hot environment and can extend the golden treatment time to 2-3 hour for hemorrhagic shock under a hot environment.

Hirudin ameliorates myocardial ischemia-reperfusion injury in a rat model of hemorrhagic shock and resuscitation: roles of NLRP3-signaling pathway.

Severe hemorrhage shock and resuscitation (HSR) has been reported to induce myocardial ischemia-reperfusion injury (MIRI), resulting in a poor prognosis. Hirudin, an effective thrombin inhibitor, can offer protection against MIRI. This study aimed to determine if hirudin administration ameliorates HSR-induced MIRI and the underlying mechanism. A rat model of HSR was established by bleeding rats to a mean arterial blood pressure of 30-35mmHg for 45min and then resuscitating them with all the shed blood through the left femoral vein. After HSR, 1mg/kg of hirudin was administrated immediately. At 24h after HSR, the cardiac injury was assessed using serum CK-MB, cTnT, hematoxylin-eosin (HE) staining, echocardiography, M1-polarized macrophages, and pyroptosis-associated factors, including cleaved caspase-1, Gasdermin D (GSDMD) N-terminal, IL-1β, and IL-18 were measured by immunofluorescence and western blot assays. Nigericin, a unique agonist, was utilized to evaluate the responsibilities of NLRP3 signaling. Under the HSR condition, rats exhibited a significant increase in myocardial injury score, an elevation of serum cTnT, CK-MB levels, an aggrandization of M1-polarized macrophages, an upregulation of pyroptosis-associated factors, including cleaved caspase-1, GSDMD N-terminal, IL-1β, and IL-18, but a significant decrease in left ventricular ejection fraction (EF%) and a reduction of left ventricular fractional shortening (FS%), while hirudin administration partially restored the changes. However, the NLRP3 agonist nigericin reversed the cardioprotective effects of hirudin. We determined the cardioprotective effects of hirudin against HSR-induced MIRI. The mechanism may involve the inhibition of NLRP3-induced pyroptosis.

Retracted: Effects of Different Types of Early Restrictive Fluid Resuscitation on Immune Function and Multiorgan Damage on Hemorrhagic Shock Rat Model in a Hypothermic Environment.

[This retracts the article DOI: 10.1155/2022/4982047.].

Carbon monoxide-releasing molecule 2 inhibits inflammation associated with intestinal ischemia-reperfusion injury in a rat model of hemorrhagic shock.

Intestinal ischemia-reperfusion injury (IRI) occurs in multiple clinical settings and contributes to systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). Due to the innate inflammatory immune nature, T cells play a crucial role in the pathogenesis of IRI, which includes not only CD4+T cells, but also CD8+and γδ T cells. Carbon monoxide (CO) plays an important role in regulating CD4+T cell responses and has been proven to be a novel therapeutic target in a variety of inflammatory disease models. This study aimed to assess whether pretreatment with carbon monoxide-releasing molecule-2 (CORM-2) could ameliorate inflammation by regulating differentiation of CD4+T cells in intestinal mucosa of rats undergoing hemorrhagic shock. A hemorrhagic shock model was established to study intestinal IRI. Morphological changes were investigated using light microscopes. Fluorescein isothiocyanate-dextran (FITC-dextran) was used as an indicator of intestinal paracellular permeability. Transcription factors involved in differentiation of CD4+T cells in intestinal mucosa were detected by immunofluorescence, and the expression levels of related cytokines were determined by Western blotting. The results of hematoxylin-eosin (H-E) staining and FITC-dextran intestinal paracellular permeability assay revealed that CORM-2 maintained the integrity of intestinal mucosal barrier and inhibited the changes of intestinal mucosal permeability. In addition, activation of T helper type 1 (Th1) and T helper type 17 (Th17) cells, and the increased expression levels of proinflammatory cytokines, such as interleukin-17 (IL-17) and interferon-gamma (IFN-γ), were observed in intestinal IRI process. In contrast, pretreatment with CORM-2 weakened changes of the abovementioned observations, in which inhibited activation of Th1 and Th17 cells. However, CORM-2 did not influence differentiation of regulatory T (Treg) cells in intestinal IRI progress. Notably, CORM-2 significantly upregulated the expression level of interleukin-10 (IL-10) protein and downregulated the expression levels of IL-17 and IFN-γ proteins in ileal tissues of rats. CORM-2 possessed anti-inflammatory effects in the progress of intestinal IRI by inhibiting activation of Th1 and Th17 cells in rats undergoing hemorrhagic shock.

Assessing organ-level immunoreactivity in a rat model of sepsis using TSPO PET imaging.

There is current need for new approaches to assess/measure organ-level immunoreactivity and ensuing dysfunction in systemic inflammatory response syndrome (SIRS) and sepsis, in order to protect or recover organ function. Using a rat model of systemic sterile inflammatory shock (intravenous LPS administration), we performed PET imaging with a translocator protein (TSPO) tracer, [18F]DPA-714, as a biomarker for reactive immunoreactive changes in the brain and peripheral organs. In vivo dynamic PET/CT scans showed increased [18F]DPA-714 binding in the brain, lungs, liver and bone marrow, 4 hours after LPS injection. Post-LPS mean standard uptake values (SUVmean) at equilibrium were significantly higher in those organs compared to baseline. Changes in spleen [18F]DPA-714 binding were variable but generally decreased after LPS. SUVmean values in all organs, except the spleen, positively correlated with several serum cytokines/chemokines. In vitro measures of TSPO expression and immunofluorescent staining validated the imaging results. Noninvasive molecular imaging with [18F]DPA-714 PET in a rat model of systemic sterile inflammatory shock, along with in vitro measures of TSPO expression, showed brain, liver and lung inflammation, spleen monocytic efflux/lymphocytic activation and suggested increased bone marrow hematopoiesis. TSPO PET imaging can potentially be used to quantify SIRS and sepsis-associated organ-level immunoreactivity and assess the effectiveness of therapeutic and preventative approaches for associated organ failures, in vivo.

Histamine induced high mobility group box-1 release from vascular endothelial cells through H1 receptor.

BackgroundSystemic allergic reaction is characterized by vasodilation and vascular leakage, which causes a rapid, precipitous and sustained decrease in arterial blood pressure with a concomitant decrease of cardiac output. Histamine is a major mediator released by mast cells in allergic inflammation and response. It causes a cascade of inflammation and strongly increases vascular permeability within minutes through its four G-protein-coupled receptors (GPCRs) on endothelial cells. High mobility group box-1 (HMGB1), a nonhistone chromatin-binding nuclear protein, can be actively secreted into the extracellular space by endothelial cells. HMGB1 has been reported to exert pro-inflammatory effects on endothelial cells and to increase vascular endothelial permeability. However, the relationship between histamine and HMGB1-mediated signaling in vascular endothelial cells and the role of HMGB1 in anaphylactic-induced hypotension have never been studied.Methods and resultsEA.hy 926 cells were treated with different concentrations of histamine for the indicated periods. The results showed that histamine induced HMGB1 translocation and release from the endothelial cells in a concentration- and time-dependent manner. These effects of histamine were concentration-dependently inhibited by d-chlorpheniramine, a specific H1 receptor antagonist, but not by H2 or H3/4 receptor antagonists. Moreover, an H1-specific agonist, 2-pyridylethylamine, mimicked the effects of histamine, whereas an H2-receptor agonist, 4-methylhistamine, did not. Adrenaline and noradrenaline, which are commonly used in the clinical treatment of anaphylactic shock, also inhibited the histamine-induced HMGB1 translocation in endothelial cells. We therefore established a rat model of allergic shock by i.v. injection of compound 48/80, a potent histamine-releasing agent. The plasma HMGB1 levels in compound 48/80-injected rats were higher than those in controls. Moreover, the treatment with anti-HMGB1 antibody successfully facilitated the recovery from compound 48/80-induced hypotension.ConclusionHistamine induces HMGB1 release from vascular endothelial cells solely through H1 receptor stimulation. Anti-HMGB1 therapy may provide a novel treatment for life-threatening systemic anaphylaxis.