Cardiopulmonary Bypass In Rats Research Articles

Inhibition of Caspase-1-dependent pyroptosis alleviates myocardial ischemia/reperfusion injury during cardiopulmonary bypass (CPB) in type 2 diabetic rats

Cardiovascular complications pose a significant burden in type 2 diabetes mellitus (T2DM), driven by the intricate interplay of chronic hyperglycemia, insulin resistance, and lipid metabolism disturbances. Myocardial ischemia/reperfusion (MI/R) injury during cardiopulmonary bypass (CPB) exacerbates cardiac vulnerability. This study aims to probe the role of Caspase-1-dependent pyroptosis in global ischemia/reperfusion injury among T2DM rats undergoing CPB, elucidating the mechanisms underlying heightened myocardial injury in T2DM. This study established a rat model of T2DM and compared Mean arterial pressure (MAP), heart rate (HR), and hematocrit (Hct) between T2DM and normal rats. Myocardial cell morphology, infarction area, mitochondrial ROS and caspase-1 levels, NLRP3, pro-caspase-1, caspase-1 p10, GSDMD expressions, plasma CK-MB, cTnI, IL-1β, and IL-18 levels were assessed after reperfusion in both T2DM and normal rats. The role of Caspase-1-dependent pyroptosis in myocardial ischemia/reperfusion injury during CPB in T2DM rats was examined using the caspase-1 inhibitor VX-765 and the ROS scavenger NAC. T2DM rats demonstrated impaired glucose tolerance but stable hemodynamics during CPB, while showing heightened vulnerability to MI/R injury. This was marked by substantial lipid deposition, disrupted myocardial fibers, and intensified cellular apoptosis. The activation of caspase-1-mediated pyroptosis and increased reactive oxygen species (ROS) production further contributed to tissue damage and the ensuing inflammatory response. Notably, myocardial injury was mitigated by inhibiting caspase-1 through VX-765, which also attenuated the inflammatory cascade. Likewise, NAC treatment reduced oxidative stress and partially suppressed ROS-mediated caspase-1 activation, resulting in diminished myocardial injury. This study proved that Caspase-1-dependent pyroptosis significantly contributes to the inflammation and injury stemming from global MI/R in T2DM rats under CPB, which correlate with the surplus ROS generated by oxidative stress during reperfusion.

Ac2-26 reduced the liver injury after cardiopulmonary bypass in rats via AKT1/GSK3β/eNOS pathway

ObjectiveAbout 10% of patients after cardiopulmonary bypass (CPB) would undergo acute liver injury, which aggravated the mortality of patients. Ac2-26 has been demonstrated to ameliorate organic injury by inhibiting inflammation. The present study aims to evaluate the effect and mechanism of Ac2-26 on acute liver injury after CPB.MethodsA total of 32 SD rats were randomized into sham, CPB, Ac, and Ac/AKT1 groups. The rats only received anesthesia, and rats in other groups received CPB. The rats in Ac/AKT1 were pre-injected with the shRNA to interfere with the expression of AKT1. The rats in CPB were injected with saline, and rats in Ac and Ac/AKT1 groups were injected with Ac2-26. After 12 h of CPB, all the rats were sacrificed and the peripheral blood and liver samples were collected to analyze. The inflammatory factors in serum and liver were detected. The liver function was tested, and the pathological injury of liver tissue was evaluated.ResultsCompared with the sham group, the inflammatory factors, liver function, and pathological injury were worsened after CPB. Compared with the CPB group, the Ac2-26 significantly decreased the pro-inflammatory factors and increased the anti-inflammatory factor, improved liver function, and ameliorated the pathological injury. All the therapeutic effects of Ac2-26 were notably attenuated by the shRNA of AKT1. The Ac2-26 increased the GSK3β and eNOS, and this promotion was inhibited by the shRNA.ConclusionThe Ac2-26 significantly treated the liver injury, inhibited inflammation, and improved liver function. The effect of Ac2-26 on liver injury induced by CPB was partly associated with the promotion of AKT1/GSK3β/eNOS.

Mild and deep hypothermia differentially affect cerebral neuroinflammatory and cold shock response following cardiopulmonary bypass in rat

IntroductionTargeted temperature management (TTM) is considered to be a neuroprotective strategy during cardiopulmonary bypass (CPB) assisted procedures, possibly through the activation of cold shock proteins. We therefore investigated the effects of mild compared with deep hypothermia on the neuroinflammatory response and cold shock protein expression after CPB in rats. MethodsWistar rats were subjected to 1 hr of mild (33 °C) or deep (18 °C) hypothermia during CPB or sham procedure. PET scan analyses using TSPO ligand [11C]PBR28 were performed on day 1 (short-term) or day 3 and 7 post-procedure (long-term) to assess neuroinflammation. Hippocampal and cortical samples were obtained at day 1 in the short-term group and at day 7 in the long-term group. mRNA expression of M1 and M2 microglia associated cytokines was analysed with RT-PCR. Cold shock protein RNA-binding motive 3 (RBM3) and tyrosine receptor kinase B (TrkB) receptor protein expression were determined with Western Blot and quantified. ResultsIn both groups target temperature was reached within an hour. Standard uptake values (SUV) of [11C]PBR28 in CPB rats at 1 day and 3 days were similar to that of sham animals. At 7 days after CPB the SUV was significantly higher in amygdala and hippocampal regions of the CPB 18 °C group as compared to the CPB 33 °C group. No differences were observed in the expression of M1 and M2 microglia-related cytokines between TTM 18 °C and 33 °C. RBM3 protein levels in cortex and hippocampus were significantly higher in CPB 33 °C compared to CPB 18 °C and sham 33 °C, at day 1 and day 7, respectively. ConclusionsTTM at 18 °C increased the neuroinflammatory response in amygdala and hippocampus compared to TTM at 33 °C in rats undergoing a CPB procedure. Additionally, TTM at 33 °C induced increased expression of TrkB and RBM3 in cortex and hippocampus of rats on CPB compared to TTM at 18 °C. Together, these data indicate that neuroinflammation is alleviated by TTM at 33 °C, possibly by recruiting protective mechanisms through cold shock protein induction.

Statement of Retraction: Protective effect of MiR-146 on renal injury following cardiopulmonary bypass in rats through mediating NF-κB signaling pathway

Statement of Retraction: Protective effect of MiR-146 on renal injury following cardiopulmonary bypass in rats through mediating NF-κB signaling pathway

Hydrogen attenuates endothelial glycocalyx damage associated with partial cardiopulmonary bypass in rats.

Cardiopulmonary bypass (CPB) causes systemic inflammation and endothelial glycocalyx damage. Hydrogen has anti-oxidant and anti-inflammatory properties; therefore, we hypothesized that hydrogen would alleviate endothelial glycocalyx damage caused by CPB. Twenty-eight male Sprague-Dawley rats were randomly divided into four groups (n = 7 per group), as follows: sham, control, 2% hydrogen, and 4% hydrogen. The rats were subjected to 90 minutes of partial CPB followed by 120 minutes of observation. In the hydrogen groups, hydrogen was administered via the ventilator and artificial lung during CPB, and via the ventilator for 60 minutes after CPB. After observation, blood collection, lung extraction, and perfusion fixation were performed, and the heart, lung, and brain endothelial glycocalyx thickness was measured by electron microscopy. The serum syndecan-1 concentration, a glycocalyx component, in the 4% hydrogen group (5.7 ± 4.4 pg/mL) was lower than in the control (19.5 ± 6.6 pg/mL) and 2% hydrogen (19.8 ± 5.0 pg/mL) groups (P < 0.001 for each), but it was not significantly different from the sham group (6.2 ± 4.0 pg/mL, P = 0.999). The endothelial glycocalyces of the heart and lung in the 4% hydrogen group were thicker than in the control group. The 4% hydrogen group had lower inflammatory cytokine concentrations (interleukin-1β and tumor necrosis factor-α) in serum and lung tissue, as well as a lower serum malondialdehyde concentration, than the control group. The 2% hydrogen group showed no significant difference in the serum syndecan-1 concentration compared with the control group. However, non-significant decreases in serum and lung tissue inflammatory cytokine concentrations, as well as in serum malondialdehyde concentration, were observed. Administration of 4% hydrogen via artificial and autologous lungs attenuated endothelial glycocalyx damage caused by partial CPB in rats, which might be mediated by the anti-inflammatory and anti-oxidant properties of hydrogen.

Change in Oxidative Stress and Mitochondrial Dynamics in Response to Elevated Cold-Inducible RNA-Binding Protein in Cardiac Surgery-Associated Acute Kidney Injury.

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a common yet serious complication that is closely related to cardiopulmonary bypass (CPB). Extracellular cold-inducible RNA-binding protein (eCIRP) can mediate aseptic inflammation and trigger intracellular oxidative stress. In the present study, expression of serum CIRP was significantly elevated post-CPB (785.0 ± 640.5 pg/mL vs. 149.5 ± 289.1 pg/mL, P < 0.001) and was positively correlated with CPB duration (r = 0.502, P < 0.001). Patients with high expression of CIRP had higher risks of postoperative AKI than patients with low CIRP expression (OR: 1.67, 95% CI 1.04-2.68). In a rat CPB model, the serum CIRP concentration increased significantly after CPB. Similarly, the levels of Scr and BUN significantly increased 4 hours after CPB. KIM-1 and NGAL mRNA levels in the CPB group were 8.2 and 4.3 times higher than the sham group, respectively. In addition, the levels of inflammatory cell infiltration, oxidative stress, and apoptosis in the renal tissue of the CPB group were significantly higher compared to the sham group. The expression levels of serum inflammatory factors at 4 hours post-CPB were also increased. Administration of recombinant human CIRP protein promoted the expression of NADPH oxidase via the TLR-4/MyD88 pathway, aggravated intracellular oxidative stress, mediated mitochondrial dynamics disorder, and eventually increased apoptosis in HK-2 cells. However, the CIRP inhibitor C23 improved the CIRP-mediated oxidative stress and mitochondrial dysfunction in both rat and cell models. In summary, elevated CIRP could mediate oxidative stress and mitochondrial dynamics in the kidney to promote CSA-AKI.

Protective effect of MiR-146 on renal injury following cardiopulmonary bypass in rats through mediating NF-κB signaling pathway

ABSTRACT The mechanism of renal injury after cardiopulmonary bypass is not clear, and the protective effect of microRNA-146 through mediating NF KB signaling pathway needs to be verified. The study intends to establish a rat model of cardiopulmonary bypass (CPB). MiR-146 is silenced or overexpressed by lentivirus transfection. It is divided into miR-146 inhibitors group (inhibitors), miR-146 mimics group (mimics) and sham group. It is found that the contents of Cr, bun and MDA in blood = , serum IL-1, IL-6 and TNF in mimics group are higher than those in the other two groups- α Content, apoptosis rate, ICAM-1, TNF- α, NF- κ B mRNA and NF- κ B protein decreased significantly (P < 0.05), while the content of SOD in kidney increased significantly (P < 0.05). In the inhibitors group, the above indicators showed the opposite results. Double luciferase assay showed that NF-kB was the target gene of miR-146. It can be seen that the expression of miR-146 inhibits inflammatory factors, apoptosis, oxidative stress and NF- κ the activation of B pathway promotes the repair of renal injury in CPB rats.

The role of annexin A1 peptide in regulating PI3K/Akt signaling pathway to reduce lung injury after cardiopulmonary bypass in rats.

Cardiopulmonary bypass (CPB) -induced lung ischemia-reperfusion (I/R) injury remains a large challenge in cardiac surgery; up to date, no effective treatment has been found. Annexin A1 (AnxA1) has an anti-inflammatory effect, and it has been proven to have a protective effect on CPB-induced lung injury. However, the specific mechanism of AnxA1 in CPB-induced lung injury is not well studied. Therefore, we established a CPB-induced lung injury model to explore the relevant mechanism of AnxA1 and try to find an effective treatment for lung protection. Male rats were randomized into five groups (n = 6, each): sham (S group), I/R exposure (I/R group), I/R + dimethyl sulfoxide (D group), I/R + Ac2-26 (AnxA1 peptide) (A group), and I/R + LY294002 (a PI3K specific inhibitor) (AL group). Arterial blood gas analysis and calculation of the oxygenation index, and respiratory index were performed. The morphological changes in lung tissues were observed under light and electron microscopes. TNF-α and IL-6 and total protein in lung bronchoalveolar lavage fluid were detected via enzyme-linked immunosorbent assay. The expressions of PI3K, Akt, and NF-κB (p65) as well as p-PI3K, p-Akt, p-NF-κB (p65), and AnxA1 were detected via western blotting. Compared with the I/R group, the A group showed the following: lower lung pathological damage score; decreased expression of IL-6 and total protein in the bronchoalveolar lavage fluid, and TNF-α in the lung; increased lung oxygenation index; and improved lung function. These imply the protective role of Ac2-26, and show that LY294002 inhibited the ameliorative preconditioning effect of Ac2-26. This finding suggested that the AnxA1 peptide Ac2-26 decreased the inflammation reaction and CPB-induced lung injury in rats, the lung protective effects of AnxA1may be correlated with the activation of PI3K/Akt signaling pathway.

Melatonin ameliorates myocardial injury by reducing apoptosis and autophagy of cardiomyocytes in a rat cardiopulmonary bypass model.

BackgroundMyocardial injury is a frequent complication after cardiac surgery with cardiopulmonary bypass (CPB). This study aimed to test the hypothesis that melatonin could attenuate myocardial injury in a rat CPB model.MethodsEighteen male Sprague-Dawley rats were randomly divided into three groups, n = 6 for each group: the sham operation (SO) group, CPB group and melatonin group. Rats in the SO group underwent cannulation without CPB, rats in CPB group intraperitoneal injected an equal volume of vehicle daily for 7 days before being subjected to CPB and rats in melatonin group intraperitoneal injected 20 mg/kg of melatonin solution daily for 7 days before being subjected to CPB. After 120 min for CPB, the expression levels of plasma interleukin (IL) -6, IL-1β, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), creatine kinase (CK) -MB and cardiac troponin T (cTnT) were measured. Reactive oxygen species (ROS) were detected by dihydroethidium (DHE). Apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining. Mitochondrial damage and autophagosomes were detected by electron microscopy. Apoptosis inducing factor (AIF) was detected by immunofluorescence. The expression of B cell lymphoma/leukemia2 associated X (Bax), B cell lymphoma/leukemia 2 (Bcl-2), cytochrome C (Cyto-C), cleaved caspase-9, AKT, p-AKT, signal transducer and activator of transcription 3 (STAT3), p-STAT3, LC3, P62, mechanistic target of rapamycin kinase (mTOR), p-mTOR and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were determined using western blotting.ResultsMelatonin significantly decreased the levels of IL-1β, IL-6, MDA, CK-MB and cTnT and increased the levels of SOD and GSH-Px, all of which were altered by CPB. Melatonin reduced cardiomyocyte superoxide production, the apoptosis index and autophagy in cardiomyocytes induced by CPB. The AKT, STAT3 and mTOR signaling pathways were activated by melatonin during CPB.ConclusionMelatonin may serve as a cardioprotective factor in CPB by inhibiting oxidative damage, apoptosis and autophagy. The AKT, STAT3 and mTOR signaling pathways were involved in this process.

Diabetic Pathophysiology Enhances Inflammation during Extracorporeal Membrane Oxygenation in a Rat Model.

Systemic inflammatory responses in patients undergoing extracorporeal membrane oxygenation (ECMO) contribute significantly to ECMO-associated morbidity and mortality. In recent years, the number of type 2 diabetes mellitus patients has increased, and the number of these patients undergoing ECMO has also increased. Type 2 diabetes mellitus is a high-risk factor for complications during ECMO. We studied the effects of ECMO on inflammatory response in a diabetic rat ECMO model. Twenty-eight rats were divided into 4 groups: normal SHAM group (normal rats: n = 7), diabetic SHAM group (diabetic rats: n = 7), normal ECMO group (normal rats: n = 7), and diabetic ECMO group (diabetic rats: n = 7). We measured the plasma levels of cytokines, tumor necrosis factor-α, and interleukin-6. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), blood urea nitrogen (BUN), creatinine (Cr), and liver-type fatty acid binding protein (L-FABP) were examined in the rat cardiopulmonary bypass model to ascertain organ damage. In addition, the lung wet-to-dry weight (W/D) ratio was measured as an index of pulmonary tissue edema. A pathologic evaluation of kidneys was conducted by hematoxylin-eosin (HE) and periodic-acid-methenamine-silver (PAM) staining. In the diabetic ECMO group, levels of cytokines, AST, ALT, LDH, and L-FABP increased significantly, reaching a maximum at the end of ECMO in comparison with other groups (p < 0.05). In addition, hematoxylin-eosin and periodic acid-methenamine-silver staining of renal tissues showed marked injury in the ECMO group (normal ECMO and diabetic ECMO groups). Furthermore, when the normal ECMO and diabetic ECMO groups were compared, severe organ injury was seen in the diabetic ECMO group. There was remarkable organ injury in the diabetic ECMO group. These data demonstrate that diabetes enhances proinflammatory cytokine release, renal damage, and pulmonary edema during ECMO in an animal model.

Study on the differential proteomics of rat hippocampal mitochondria during deep hypothermic circulatory arrest.

BackgroundThis study aimed to investigate the effect of deep hypothermic circulatory arrest (DHCA) on rat hippocampal mitochondrial protein expression and its differential proteomics, and explore the potential mechanisms behind the effect.MethodsWe used internal jugular vein reflux and tail artery perfusion methods to establish the rat cardiopulmonary bypass (CPB) model. Rats were dissected to obtain the hippocampus, and the hippocampal mitochondria were purified. The mitochondrial morphology and the mitochondrial marker cytochrome C oxidase (COX) qualitatively examined via transmission electron microscopy and western-blot analysis, respectively. The qualified samples were subjected to isobaric tags for relative and absolute quantification (iTRAQ); we then established the CPB model again to obtain the rat hippocampus for cryoultramicrotomy, and used immunofluorescent double staining technique to qualitatively and semi-quantitatively verify two representative differentially expressed proteins.ResultsBy searching the Mascot 2.2 database, 29 differentially expressed proteins were obtained with statistical significance, including 21 known proteins and 8 unknowns. The expression level of COX and monoacylglycerol lipase did not change significantly (P>0.05) during the hyperacute phase; however, their intracellular localizations were altered.ConclusionsDHCA induced the differential expression of 29 rat hippocampal mitochondrial proteins, some of which had altered intracellular localization. We speculated that the localized alteration of these proteins is one of the neuroprotection mechanisms that occurs during DHCA.

Dexmedetomidine improves postoperative neurocognitive disorder after cardiopulmonary bypass in rats

ABSTRACT Purpose To investigate whether dexmedetomidine can improve postoperative neurocognitive function after cardiopulmonary bypass in rats. Methods A total of 45 male Sprague Dawley (SD) rats were randomly divided into sham group, control group, and dexmedetomidine (Dex) group. The rats in the sham group received skin excision and blood vessel ligation treatment, rats in the control group received cardiopulmonary bypass (CPB), and rats in the Dex group received CPB and Dex treatment. Morris water maze test and open-field tests were used to evaluate the rats’ cognition. The expression of inflammatory mediators in the rats’ central and peripheral regions, Aβ and Tau in the hippocampus and prefrontal cortex, and apoptosis in brain tissue were measured. Results The CPB model rats were found to have significantly decreased cognitive function, increased expression of caspase-3 and Bax in the prefrontal cortex and hippocampus DG, increased apoptosis and activated microglia, and increased plasma levels of TNF-α, IL-6, and TNF-α. Dexmedetomidine reduced apoptosis in the prefrontal cortex and hippocampus DG region of rats, decreased the expression of caspase-3 and bax, inhibited microglia activation in the prefrontal cortex and hippocampus DG region of rats, and decreased the plasma levels of IL-β, IL-6, and TNF-α. Conclusions Dexmedetomidine plays a neuroprotective role by inhibiting inflammation, apoptosis, and microglia activation in the prefrontal cortex and hippocampal DG region, and attenuates the cognitive deficit identified in the control group.

Integrated stress response activation after recovery of cardiopulmonary bypass in rats

The systemic inflammation response syndrome (SIRS) is a consequence of the cardiopulmonary bypass (CPB) in cardiac surgery that can trigger multiple organ dysfunction (MOD). Pulmonary, renal and cerebral dysfunctions are the most common post-operative complications of CPB. The sustained of activation of integrated stress response (ISR) pathway could impact patient outcomes. This project aims to decipher pathophysiological process in SIRS and organ dysfunction after recovery of CPB in a rat model. After isoflurane induction (2%, O 2 : 0.5 L/min) surgical procedure for CPB or Sham was performed under propofol-fentanyl infusion (30–4 μg/kg/h) on mechanically ventilated 15-week old rats. The CPB circuit allows blood to be drawn by the vena cava and reperfused in the aorta after oxygenation. Hemodynamic and biochemical parameters were monitored during the procedure. Mean Arterial Pressure (MAP) was maintained to a minimum of 60 mmHg with a FiO 2 1.0 for 1 h. Five hours post-recovery, behavior, respiratory rate and hemodynamic were measured. Blood and organs were collected to evaluate the integrated stress response pathway. Compared to Sham, CPB leads to a decrease of MAP (88.3 ± 2.6 vs 60.0 ± 9.4 mmHg, P < 0.05, N = 4), an increase of Lactate (1.4 ± 0.4 vs 4.1 ± 0.9 mM, P < 0.05), Creatinine (34.7 ± 1.0 vs 152.7 ± 7.7 μM, P < 0.05), and pro-inflammatory cytokines IL-6 (Sham: 48 ± 24 pg/mL; CPB: 8468 ± 1 pg/mL, P < 0.05). Rat Behavior and reflex, and lung inflammation were significantly altered 5 h after recovery when compared to Sham. ISR pathway activation was shown by western blot on lung, kidney and brain tissues from CPB rats with respectively a 3-, 2- and 3-fold increase in GADD34 protein levels. On our CPB rat model, we highlight organs dysfunctions associated with an activation of the ISR pathway. We will now evaluate the potential impact of ISR activation on MOD.

Endothelial colony-forming cells reduced the lung injury induced by cardiopulmonary bypass in rats

BackgroundCardiopulmonary bypass (CPB) results in severe lung injury via inflammation and endothelial injury. The aim of this study was to evaluate the effect of endothelial colony-forming cells (ECFCs) on lung injury in rats subjected to CPB.MethodsThirty-two rats were randomized into the sham, CPB, CPB/ECFC and CPB/ECFC/L-NIO groups. The rats in the sham group received anaesthesia, and the rats in the other groups received CPB. The rats also received PBS, ECFCs and L-NIO-pre-treated ECFCs. After 24 h of CPB, pulmonary capillary permeability, including the PaO2/FiO2 ratio, protein levels in bronchoalveolar lavage fluid (BALF) and lung tissue wet/dry weight were evaluated. The cell numbers and cytokines in BALF and peripheral blood were tested. Endothelial injury, lung histological injury and apoptosis were assessed. The oxidative stress response and apoptosis-related proteins were analysed.ResultsAfter CPB, all the data deteriorated compared with those obtained in the S group (sham vs CPB vs CPB/ECFC vs CPB/ECFC/L-NIO: histological score 1.62 ± 0.51 vs 5.37 ± 0.91 vs 3.37 ± 0.89 vs 4.37 ± 0.74; PaO2/FiO2 389 ± 12 vs 233 ± 36 vs 338 ± 28 vs 287 ± 30; wet/dry weight 3.11 ± 0.32 vs 6.71 ± 0.73 vs 4.66 ± 0.55 vs 5.52 ± 0.57; protein levels in BALF: 134 ± 22 vs 442 ± 99 vs 225 ± 41 vs 337 ± 53, all P < 0.05). Compared to the CPB treatment, ECFCs significantly improved pulmonary capillary permeability and PaO2/FiO2. Similarly, ECFCs also decreased the inflammatory cell number and pro-inflammatory factors in BALF and peripheral blood, as well as the oxidative stress response in the lung tissue. ECFCs reduced the lung histological injury score and apoptosis and regulated apoptosis-related proteins in the lung tissue. Compared with the CPB/ECFC group, all the indicators were partly reversed by the L-NIO.ConclusionsECFCs significantly reduced lung injury induced by inflammation after CPB.

The N-terminal lectin-like domain of thrombomodulin reduces acute lung injury without anticoagulant effects in a rat cardiopulmonary bypass model.

Systemic inflammation evoked by cardiopulmonary bypass (CPB) leads to acute lung injury (ALI) and respiratory failure. Although recombinant human soluble thrombomodulin (rTM) consists of three domains (D1-3), is reported to attenuate systemic inflammation through the N-terminal lectin-like domain (D1), anticoagulant domain (D2) may exacerbate coagulopathy after CPB. We investigated the potential of selective D1 against CPB-mediated ALI free from anticoagulant effects using a rat CPB model. Rats were divided into three groups: control (CPB alone, n = 5), D1 (CPB + D1, n = 4), and D123 (CPB + D123, n = 6). D1 or D123 was administratedto the rats of each group before CPB establishment. Blood samples are collected before, during and after CPB. Blood coagulability was assessed by a coagulation analyzer. Lung samples are collected at 1h after the termination of CPB for histological analyses. D123 group exhibited significantly prolonged glass beads-activated clotting time with heparinase after CPB compared to that in control group, whereas no significant prolongation in control and D1 group (control vs. D1 vs. D123: 65.4 ± 9.2 vs. 65.3 ± 10.9 vs. 83.5 ± 4.6s, p = 0.036 [control vs. D123], 0.99 [control vs. D1]) indicating the absence of anticoagulant activities of D1. Histological studies revealed less congestion, edema, inflammation, and hemorrhage in both D1 and D123 groups compared to those in control group indicating protective effects of both D1 and D123 against ALI mediated by CPB. N-terminal lectin-like domain of rTM may reduce the risk of ALI without anticoagulant effects.

Protective effects of dexmedetomidine against pulmonary ischemia-reperfusion injury during cardiopulmonary bypass in rats

To investigate the signaling pathways that mediate the protective effects of dexmedetomidine on lung tissue against ischemia-reperfusion (I/R) injury during cardiopulmonary bypass (CPB). Forty adult SD rats were randomized into 5 groups, namely I/R group (group A), dexmedetomidine group (group B), sham-operated group (group C), oxypenicillin group (group D), and oxypenicillin + dexmedetomidine group (group E). The arterial blood gas, lung tissue apoptosis rate, protein kinase (Akt), phosphorylated Akt (p-AKT), caspase-3 and caspase-9 were compared among the 5 groups. In groups A, B, D and E, the heart rate (HR), mean arterial pressure (MAP), and oxygenation index (OI) measured before CPB, at opening of the left hilar and at the end of experiment decreased gradually while the respiratory index (RI) increased at the 3 time points. At the end of experiment, HR, MAP, and OI in group B were significantly higher and RI was significantly lower than those in groups A, D and E (P &lt; 0.05). In groups A-E, the pathological scores of the lung tissue at the end of the experiment were 4.89, 1.89, 0, 6.01 and 5.76, respectively, and the cell apoptosis rates in the lung tissue were 6.25%, 3.69%, 1.06%, 8.06% and 7.79%, respectively (P &lt; 0.001). Western blotting showed that the expressions of Akt and p-AKT were the highest and those of caspase-3 and caspase-9 were the lowest in group B among the 5 groups (P &lt; 0.05). Dexmedetomidine can effectively alleviate lung injury in rats during CPB possibly by targeting caspase-3 and caspase-9 proteins that are related to PI3K/Akt signaling pathway.

To explore the preventive and therapeutic effects of Xuebijing injection on acute lung injury induced by cardiopulmonary bypass in rats by regulating the expression of microRNA-17-5p and its mechanism

To investigate the preventive effect of Xuebijing injection on acute lung injury induced by cardiopulmonary bypass (CPB) and the underlying mechanism. (1) In vivo experiment: 30 Sprague-Dawley (SD) rats were randomly divided into sham group, CPB group, Xuebijing pretreatment group (XBJ+CPB group) with 10 rats in each group. CPB model was reproduced in rats; and CPB was not performed in sham group, but only through arteriovenous puncture. In the XBJ+CPB group, 4 mL/kg Xuebijing injection was injected intraperitoneally 2 hours before CPB, sham group and CPB group were injected with equal volume of normal saline at the same time. The blood from femoral artery was analyzed 4 hours after operation, and the oxygenation index (PaO2/FiO2) was calculated. Then the rats were sacrificed to collect bronchoalveolar lavage fluid (BALF), and the lung permeability index (PPI) was calculated. The lung tissues were harvested, and the wet/dry weight ratio (W/D) of lung tissue was measured. The index of quantitative evaluation of alveolar injury (IQA) was measured. The levels of interleukins (IL-1, IL-6) and tumor necrosis factor-α (TNF-α) in lung tissue and BALF were measured by enzyme-linked immunosorbent assay (ELISA). The content of malondialdehyde (MDA) and the activities of myeloperoxidase (MPO) and superoxide dismutase (SOD) in lung tissue were detected by biochemical method. The microRNA-17-5p (miR-17-5p) expression in lung tissue was determined by quantitative reverse transcription-polymerase chain reaction (RT-qPCR). (2) In vitro experiments: type II alveolar epithelial cells (AEC II) were cultured in vitro, and they were randomly divided into control group (the cells were treated by preoperative serum of CPB in patients with ventricular septal defect), CPB group (the cells were treated by serum after CPB in patients), and XBJ+CPB group (Xuebijing injection 10 g/L+serum after CPB in patients). After 12 hours of culture in each group, the expression of miR-17-5p was detected by RT-qPCR. AEC II cells were transfected with miR-17-5p mimic, inhibitor or corresponding control oligonucleotide (negative control), respectively, to observe the effect of miR-17-5p on Xuebijing regulating CPB-induced apoptosis rate and caspase-3 activity. (1) In vivo experiment: compared with the sham group, the PPI, lung W/D ratio, IQA, and IL-1, IL-6, TNF-α in lung tissue and BALF, as well as MDA content and MPO activity in lung tissue were significantly increased, PaO2/FiO2 and SOD activity in lung tissue were significantly decreased. The parameters of the XBJ+CPB group were significantly improved, suggesting that Xuebijing pretreatment could improve CPB-induced ALI in rats. The expression of miR-17-5p in lung tissue of the CPB group was significantly down-regulated as compared with sham group (2-ΔΔCt: 0.48±0.13 vs. 1.00±0.11, P < 0.05); while the expression of miR-17-5p in the XBJ group was significantly up-regulated as compared with the CPB group (2-ΔΔCt: 1.37±0.09 vs. 0.48±0.13, P < 0.05), indicating that the improvement of Xuebijing injection on lung injury after CPB might be related to miR-17-5p. (2) In vitro experiment: the changes in miR-17-5p expression in each group of AEC II cells confirmed in vivo results. After transfection of miR-17-5p mimic, the apoptotic rate and caspase-3 activity of each group were significantly lower than those transfected with negative control, and the decrease was more significant in the XBJ+CPB group [apoptotic rate: (7.37±0.95)% vs. (12.60±1.90)%, caspase-3 (A value): 0.82±0.09 vs. 1.37±0.08, both P < 0.05]. After transfection of miR-17-5p inhibitor, the apoptotic rate and caspase-3 activity of each group were significantly more than those transfected with negative control [in the XBJ+CPB group: apoptotic rate was (16.30±1.86)% vs. (12.60±1.90)%, caspase-3 (A value) was 1.78±0.13 vs. 1.37±0.08, both P < 0.05]. This indicated that the apoptosis of AEC II cells cultured in serum after CPB was significantly reduced by miR-17-5p, and further reduced by the pretreatment with Xuebijing. Xuebiing injection can reduce the inflammatory reaction and oxidative stress of lung tissue in rats with ALI induced by CPB, and improve oxygenation. The mechanism may be related to up-regulation of miR-17-5p expression in AEC II cells and inhibition of apoptosis of AEC II cells.

Adenosine A2areceptor agonist CGS21680 treatment attenuates cardiopulmonary bypass‑associated inflammatory lung injury in juvenile rats.

The adenosineA2areceptor agonist CGS21680 has been suggested to act as an anti‑inflammatory agent that protects against cardiopulmonary bypass (CPB)‑induced organ injury. However, the therapeutic effects of CGS21680 for CPB‑induced lung injury have not been comprehensively evaluated. Using a juvenile rat model, the present study was designed to evaluated whether CGS21680 attenuates CPB‑induced lung injury. Our juvenile rat CPB model was established by 60min CPB with or without CGS21680 pretreatment (100µg/kg, in the CPB priming solution). Rats in the Sham group only underwent cannulation and heparinization. Serum and pulmonary levels of inflammatory markers and histological features of pulmonary tissues were analyzed. All juvenile rats survived following CPB. Significantly elevated serum levels of tumor necrosis factor‑α (TNF‑α), myeloperoxidase(MPO) and interleukin‑1β(IL‑1β), and decreased glutathione peroxidase (GSH‑PX) levels were observed in the CPB group compared to the Sham group (all P<0.05). TNF‑α, MPO and IL‑1β were significantly decreased, while GSH‑PX was markedly increased in the CGSgroup when compared to the CPBgroup. Consistently, pulmonary tissues from rats in the CPBgroup showed considerable amounts of damaged pneumocytes, severe edema, and increased alveolar macrophages, and significantly higher lung injury scores compared to the controls. Collectively, these changes were all further attenuated by CGS21680. Pretreatment with CGS21680 before CPB attenuated pulmonary injury, which may be related to the anti‑inflammatory effects of CGS21680 downstream of A2areceptor activation.

Chronic hypoxia-induced Cirbp hypermethylation attenuates hypothermic cardioprotection via down-regulation of ubiquinone biosynthesis.

Therapeutic hypothermia is commonly used during cardiopulmonary bypass (CPB) to protect the heart against myocardial injury in cardiac surgery. Patients who suffer from chronic hypoxia (CH), such as those with certain heart or lung conditions, are at high risk of severe myocardial injury after cardiac surgery, but the underlying mechanisms are unknown. This study tested whether CH attenuates hypothermic cardioprotection during CPB. Using a rat model of CPB, we found that hypothermic cardioprotection was impaired in CH rats but was preserved in normoxic rats. Cardiac proteomes showed that cold-inducible RNA binding protein (CIRBP) was significantly (P = 0.03) decreased in CH rats during CPB. Methylation analysis of neonatal rat cardiomyocytes under CH and myocardium specimens from patients with CH showed that CH induced hypermethylation of the Cirbp promoter region, resulting in its depression and failure to respond to cold stress. Cirbp-knockout rats showed attenuated hypothermic cardioprotection, whereas Cirbp-transgenic rats showed an enhanced response. Proteomics analysis revealed that the cardiac ubiquinone biosynthesis pathway was down-regulated during CPB in Cirbp-knockout rats, resulting in a significantly (P = 0.01) decreased concentration of ubiquinone (CoQ10). Consequently, cardiac oxidative stress was aggravated and adenosine 5'-triphosphate production was impaired, leading to increased myocardial injury during CPB. CoQ10-supplemented cardioplegic solution improved cardioprotection in rats exposed to CH, but its effect was limited in normoxic rats. Our study suggests that an individualized cardioprotection strategy should be used to fully compensate for the consequences of epigenetic modification of Cirbp in patients with CH who require therapeutic hypothermia.

Effects of erythropoietin preconditioning on acute renal injury induced by cardiopulmonary bypass in rats

Objective To investigate the renal protective effect of erythropoietin (EPO) preconditioning on acute renal injury induced by cardiopulmonary bypass (CPB) in rats. Methods 40 male Sprague-Dawley rats were randomly divided into four groups: Sham, Control, Low and High EPO.24 h after the CPB, Blood samples were collected for assays of serum creatinine (Cr), meanwhile renal samples were obtained for the determination of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), nuclear factor-κB p65 (NF-κB p65), intercellular adhesion molecule-1 (ICAM-1), and for histologic examination. Results Compared with Control group (141.99±6.96) μmol/L, the levels of Cr decreased in Low EPO (91.52±5.43) μmol/L and High EPO group (67.52±5.63) μmol/L (P<0.01), levels of TNF-α [(9.41±0.72), (7.85±0.67) ng/mg], IL-1β [(12.35±1.43), (10.18±2.01) ng/mg], IL-6 [(8.25±0.65), (6.08±0.72) ng/mg], NF-κB p65 (0.165±0.003, 0.151±0.005), ICAM-1 (6.847±0.310, 5.013±0.462) in renal tissue of the Low and High EPO treated animals were significantly lower than those of the Control group (13.29±1.21) ng/mg, (18.39±1.79) ng/mg, (10.95±1.03) ng/mg, (0.189±0.009), (9.109±0.371) (all P<0.01). Histopathologic finding of the CPB group conflrmed that there was renal impairment by cast formation and tubular necrosis in the tubular epithelium. These changes were markedly reversed in EPO groups, High does EPO had a better renal protective effect (P<0.01). Conclusion EPO was effective on preventing CPB-induced renal injury probably through its downregulation of NF-κB p65. Furthermore, EPO attenuated these above changes dose dependently. Key words: Erythropoietin; Nuclear factor-κB p65; Acute renal injury; Cardiopulmonary bypass