Orthotopic Autologous Liver Transplantation Research Articles

Effect of sulfasalazine on ferroptosis during intestinal injury in rats after liver transplantation

Using a rat autologous orthotopic liver transplantation (AOLT) model and liver cold ischemia–reperfusion (I/R)-induced intestinal injury, we clarified whether ferroptosis occurred in rat AOLT cold I/R-induced intestinal injury. Additionally, the role and possible mechanism of the ferroptosis activator sulfasalazine (SAS) in intestinal injury-induced ferroptosis in rats with AOLT liver cold I/R were investigated. Sixty specific pathogen free (SPF)-grade adult male Sprague‒Dawley (SD) rats were randomly divided into 5 groups using the random number table method (n = 12). Six rats were randomly selected at 6 hour (h) and 24 h after I/R. Inferior vena cava blood specimens were collected from the portal vein (PV) opening at 6 h and 24 h. The concentrations of serum malondialdehyde (MDA), serum interleukin 6 (IL-6) were determined by enzyme-linked immunosorbent assay (ELISA). Ileal tissue was obtained from the PV opening in rats in each group at 6 h and 24 h, and ileal tissue sections were observed under light microscopy. The contents of intestinal MDA, superoxide dismutase (SOD), glutathione(GSH), glutathione peroxidase 4 (GPX4), and tissue iron were determined by ELISA, and the expression of GPX4 and the cysteine glutamate reverse transporter light chain protein (xCT) was determined by Western blot. The experimental results show that ferroptosis is involved in the pathophysiological process of intestinal injury induced by cold hepatic ischemia–reperfusion in AOLT rats. In addition, SAS (500 mg/kg) may inhibit the cystine/glutamate antiporters (System Xc¯)/GSH/GPX4 signal axis in intestinal injury induced by cold I/R in rat AOLT liver, or iron overload after reperfusion, causing a massive accumulation of L-ROS and activating cellular ferroptosis, further aggravate the intestinal injury.

SerpinB1 is required for Rev-erbα-mediated protection against acute lung injury induced by lipopolysaccharide-in mice.

Acute lung injury (ALI) is a serious, life-threatening inflammation of the lungs that still lacks effective treatment. We previously showed that serine protease inhibitor B1 (SerpinB1) protects against ALI induced by orthotopic autologous liver transplantation. However, the role of SerpinB1 in lipopolysaccharide (LPS)-induced ALI and its regulatory mechanisms are not known. Wild-type (WT) and SerpinB1 knockout (KO) mice were treated with intratracheal LPS stimulation to induce ALI. Some of the WT and KO mice were injected i.p. with melatonin, a rhythm-related protein Rev-erbα agonist. The circadian rhythm in WT mice was disrupted by exposing mice to 24 h of continuous dark or light conditions after intratracheal LPS. Neutrophils were isolated from alveolar lavage fluid of WT and KO mice, and from human peripheral blood. Neutrophils were treated with LPS and melatonin. Disruption of circadian rhythm by either 24-h dark or light conditions exacerbated LPS-induced ALI and decreased expression of Rev-erbα and SerpinB1 protein in lung, whereas melatonin treatment increased SerpinB1 expression and attenuated LPS-induced ALI in WT mice, but not in KO mice. In isolated neutrophils, Rev-erbα was co-localized with SerpinB1 and bound to its promoter to trigger SerpinB1 transcription. Furthermore, LPS stimulation increased formation of neutrophil extracellular traps, which was reversed by melatonin treatment in neutrophils from WT mice, but not from KO mice. In mice, SerpinB1 is rhythmically regulated by Rev-erbα, and its down-regulation exacerbates LPS-induced ALI by inducing formation of neutrophil extracellular traps.

Dual-regulation by Cx32 in hepatocyte to trigger and worsen liver graft injury

Liver transplantation is the ultimate treatment option for end-stage liver failure. However, liver graft injury remains a challenge. This study aimed to investigate the role of connexin32 (Cx32) in liver graft injury and elucidate its mechanism of action. Through detecting liver graft samples from 6 patients, we observed that changes in the Cx32 level coincided with liver graft injury. Therefore, we established autologous orthotopic liver transplantation (AOLT) models using Cx32-knockout and wild-type mice and hypoxia/reoxygenation (H/R) and lipopolysaccharide (LPS) pretreatment models using alpha mouse liver 12 (AML12) cells, to explore Cx32 mechanisms in liver graft injury. Following in vivo and in vitro Cx32 knockout, oxidative stress and inflammatory response were inhibited through the regulation of PKC-α/NF-κB/NLRP3 and Nrf2/NOX4/ROS signaling pathways, thereby reducing Bak/Bax-related apoptosis and ameliorating liver graft injury. When the Cx32-based gap junction (GJ) was blocked with 2-aminoethoxydiphenyl borate (2-APB), ROS transfer was attenuated between neighboring cells, exacerbated oxidative stress and inflammatory response were prevented, and aggravation of liver graft injury was mitigated. These results highlight the dual regulation mechanism of Cx32 in liver graft injury. Through interaction with PKC-α, Cx32 regulated the NF-κB/NLRP3 and Nrf2/NOX4/ROS signaling pathways, thus directly triggering oxidative stress and inflammatory response. Simultaneously, mass-produced ROS were transferred to neighboring cells through Cx32 channels, for which oxidative stress and the inflammatory response were aggravated indirectly. Finally, Bak/Bax-related apoptosis was activated, thereby worsening liver graft injury. Our findings propose Cx32 as a dual mechanistic factor for oxidative stress and inflammatory signaling pathways in regulating cell apoptosis on liver graft injury, which suggests a promising therapeutic targets for liver graft injury.

IL-22 Protects against Biliary Ischemia-Reperfusion Injury after Liver Transplantation via Activating STAT3 and Reducing Apoptosis and Oxidative Stress Levels In Vitro and In Vivo.

Biliary complications are currently one of the leading causes of liver failure and patient death after liver transplantation and need to be solved urgently. Biliary ischemia-reperfusion injury (IRI) is one of the important causes of biliary complications. IL-22 has a protective effect on liver injury and hepatitis diseases, and its safety and efficacy in the treatment of hepatitis have also been proved in human clinical experiments. Furthermore, multiple studies have confirmed that IL-22 promotes the proliferation and repair of epithelial cells in various organs. Still, its function in the bile duct after transplantation has not been explored. This study was aimed at investigating the effects of IL-22 on cholangiocyte IRI in vitro and in vivo and exploring its underlying mechanisms. We simulated the hypoxia process of bile duct epithelial cells through in vitro experiments to investigate the protective function and molecular mechanism of IL-22 on bile duct epithelial cells. Subsequently, the function and mechanism of IL-22 in the biliary IRI model of autologous orthotopic liver transplantation in rats were assessed. This study confirmed that IL-22 could promote cholangiocyte proliferation, decrease the apoptosis rate of cholangiocytes and tissues, decrease MDA levels, and increase SOD levels by activating STAT3. In addition, IL-22 can also reduce the level of mitochondrial membrane depolarization, protect mitochondria, reduce ROS production, and play a role in protecting bile ducts. These findings provide evidence for IL-22 as a novel and effective treatment for biliary IRI after liver transplantation.

PI3K/AKT activation attenuates acute kidney injury following liver transplantation by inducing FoxO3a nuclear export and deacetylation

AimsAcute kidney injury (AKI) is a severe complication of autologous orthotopic liver transplantation (AOLT). Apoptosis has been shown to be involved in renal ischemia/reperfusion, and the PI3K/AKT signaling pathway is involved in numerous cell processes, including promoting cell survival and inhibiting apoptosis. We aimed to verify whether the PI3K/AKT signaling pathway participates in the development of post-AOLT AKI. MethodsMale Sprague–Dawley rats underwent AOLT with or without treatment with insulin-like growth factor-1 (IGF-1, a PI3K/AKT activator) and LY294002 (a PI3K/AKT inhibitor; n = 8/group). NRK-52E cells (rat renal tubular epithelial cell line) were subjected to hypoxia–re-oxygenation to mimic renal cell I/R injury in vitro, and confirm whether silencing information regulator 1 (SIRT1) mediated the protective effects of PI3K/AKT by deacetylating forkhead protein O3a (FoxO3a). Key findingsDuring the reperfusion stage, kidney injury peaked at 8 h after reperfusion, then gradually recovered, which was consistent with the dynamic changes in apoptosis and the protein expressions of Bcl-2 interacting mediator of cell death (Bim), Fas ligand (FasL), and nuclear FoxO3a AKT phosphorylation and nuclear SIRT1 protein expression were also upregulated. IGF-1 application decreased Bim, FasL, and nuclear FoxO3a protein expressions, and protected against apoptosis and AKI. In NRK-52E cells, IGF-1 upregulated nuclear SIRT1 expression, reduced FoxO3a acetylation, downregulated Bim and FasL protein expressions, and attenuated apoptosis and AKI; these effects were reversed by SIRT1 blocking. ConclusionThe activation of the PI3K/AKT signaling pathway not only induced FoxO3a nuclear export but also deacetylation through upregulating nuclear SIRT1 expression to attenuate post-AOLT AKI.

Stabilizing mast cells improves acute lung injury after orthotopic liver transplantation via promotion of apoptosis in polymorphonuclear neutrophils.

Postoperative pulmonary complications including acute lung injury (ALI) and acute respiratory distress syndrome have contributed to mortality and morbidity of orthotopic liver transplantation (OLT) with unclear mechanisms. Mast cells (MCs) and polymorphonuclear neutrophils (PMNs) are the main inflammatory cells and participants in the process of ALI. The present study was designed to investigate the role of MCs and PMNs and their potential relation to ALI following OLT. Rat orthotopic autologous liver transplantation (OALT) model was designed to determine lung injury at different time points after liver reperfusion. We also evaluated the function of MCs and the effect of tumor necrosis factor-α (TNF-α) and tryptase on ALI and PMN apoptosis in rats subjected to OALT. Histological scores and inflammatory factor levels as well as PMN apoptosis were measured. Rats suffered from ALI after OALT, which was demonstrated by a collapse of the pulmonary architecture, pulmonary edema, and infiltration of inflammatory cells in alveolar and interstitial spaces, as well as increased levels of proinflammatory cytokines. ALI maximized at 8 h after OALT. However, PMN apoptosis lagged behind the pulmonary injury and maximized at 16 h after OALT, when the acute inflammation resolution initiated. MC stabilization, and tryptase and TNF-α inhibitors could significantly decrease the lung pathophysiologic scores accompanied by an increase in PMN apoptosis. ALI after OALT was associated with MC activation and PMN apoptosis. ALI progression might be affected by delayed PMN apoptosis, which was related to MC activation. Induction of PMN apoptosis might alleviate ALI after OALT.

Metformin Attenuates Ischemia-reperfusion Injury of Fatty Liver in Rats Through Inhibition of the TLR4/NF-κB Axis

Background:Donor organs for liver transplantation may often have fatty liver disease, which confers a higher sensitivity to ischemia/reperfusion injury. At present, there is no effective treatment for the condition. Evidence has suggested that metformin, the first-line medication for diabetes, has protective effects against many disorders. However, the potential role of metformin in ischemia/reperfusion injury in fatty liver disease remains unclear.Aims:To examine the effect of metformin treatment during ischemia/reperfusion injury in fatty liver and determine the possible mechanisms.Study Design:Animal experimentation.Methods:Sprague-Dawley male rats were fed a high-fat diet (520 kcal/100 g) for 14 weeks and then were subjected to the orthotopic autologous liver transplantation model. Sections of liver tissue were stained with hematoxylin and eosin to visualize the damage. Blood and liver samples were used to analyze the related proteins and components involved in the inflammatory signaling pathway.Results:We found that metformin significantly ameliorated the ischemia/reperfusion injury of the fatty liver through a reduction in alanine aminotransferase/aspartate aminotransferase concentrations in the serum and a decrease in dead cells, as shown by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay (p<0.05). In addition, metformin significantly attenuated interleukin (IL)-6, IL-1β, and tumor necrosis factor-α production and increased the expression of active caspase-3 and Bax in the liver (p<0.05). Mechanistically, metformin suppressed the activation of toll-like receptor 4 (TLR4)/NF-κB signaling (p<0.05), resulting in a decreased inflammatory response and apoptosis.Conclusion:Our findings demonstrated that metformin attenuated ischemia/reperfusion injury in fatty liver disease via the TLR4/NF-κB axis, suggesting that metformin could have potential therapeutic applications in ischemia/reperfusion injury associated with liver transplantation.

Neutrophil Elastase Inhibitors Suppress Oxidative Stress in Lung during Liver Transplantation.

Background Neutrophil infiltration plays a critical role in the pathogenesis of acute lung injury following liver transplantation (LT). Neutrophil elastase is released from neutrophils during pulmonary polymorphonuclear neutrophil activation and sequestration. The aim of the study was to investigate whether the inhibition of neutrophil elastase could lead to the restoration of pulmonary function following LT. Methods In in vivo experiments, lung tissue and bronchoalveolar lavage fluid (BALF) were collected at 2, 4, 8, and 24 h after rats were subjected to orthotopic autologous LT (OALT), and neutrophil infiltration was detected. Next, neutrophil elastase inhibitors, sivelestat sodium hydrate (exogenous) and serpin family B member 1 (SERPINB1) (endogenous), were administered to rats before OALT, and neutrophil infiltration, pulmonary oxidative stress, and barrier function were measured at 8 h after OALT. Results Obvious neutrophil infiltration occurred from 2 h and peaked at 8 h in the lungs of rats after they were subjected to OALT, as evidenced by an increase in naphthol-positive cells, BALF neutrophil elastase activity, and lung myeloperoxidase activity. Treatment with neutrophil elastase inhibitors, either sivelestat sodium hydrate or SERPINB1, effectively reduced lung naphthol-positive cells and BALF inflammatory cell content, increased expression of lung HO-1 and tight junction proteins ZO-1 and occludin, and increased the activity of superoxide dismutase. Conclusion Neutrophil elastase inhibitors, sivelestat sodium hydrate and SERPINB1, both reduced lung neutrophil infiltration and pulmonary oxidative stress and finally restored pulmonary barrier function.

Effect of dexmedetomidine on necroptosis during intestinal injury in rats undergoing autologous orthotopic liver transplantation

Objective To evaluate the effect of dexmedetomidine on necroptosis during intestinal injury in rats undergoing autologous orthotopic liver transplantation (AOLT). Methods Twenty-four SPF adult male Sprague-Dawley rats, aged 8-10 weeks, weighing 250-280 g, were divided into 3 groups (n=8 each) using a random number table method: sham operation group (group S), AOLT group (group T) and dexmedetomidine group (group D). Dexmedetomidine 50 μg/kg was intraperitoneally injected at 30 min before surgery in group D. Blood samples were collected from the inferior vena cava at 6 h after opening the hepatic portal vein (at 6 h after the end of surgery in group S) for determination of serum diamine oxidase (DAO), D-lactic acid (D-LA) and tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10) concentrations.The intestine was removed for examination of the pathological changes (with a light microscope) and for determination of the level of malondialdehyde (MDA) content and superoxide dismutase (SOD) activity (using spectrophotometry) and expression of receptor-interacting protein kinase-1 (RIPK1), RIPK3, and mixed lineage kinase domain-like (MLKL) in intestinal tissues (by Western blot). Intestinal damage was assessed and scored according to Chiu. Results Compared with group S, the serum DAO, D-LA, TNF-α and IL-10 concentrations, intestinal MDA content and Chiu′s score were significantly increased, the SOD activity was decreased, and the expression of RIPK1, RIPK3 and MLKL was up-regulated in group T (P<0.05). Compared with group T, the serum DAO, D-LA and TNF-α concentrations, intestinal MDA content and Chiu′s score were significantly decreased, the SOD activity and serum IL-10 concentration were increased, and the expression of RIPK1, RIPK3 and MLKL was down-regulated in group D (P<0.05). Conclusion The mechanism by which dexmedetomidine attenuates intestinal injury is related to inhibiting necroptosis in rats undergoing AOLT. Key words: Dexmedetomidine; Liver transplantation; Intestine; Necrosis

Dexmedetomidine Attenuates Orthotopic Liver Transplantation-Induced Acute Gut Injury via α 2-Adrenergic Receptor-Dependent Suppression of Oxidative Stress.

Patients with orthotopic liver transplantation (OLT) frequently develop acute gut injury (AGI), and dexmedetomidine (Dex) has been reported to exert a protective effect against AGI. We investigated whether Dex protects against AGI through antioxidative stress effects by the Nrf2/HO-1 antioxidative signaling pathway. Rats were randomly allocated into a sham group and six orthotopic autologous liver transplantation (OALT) groups receiving different doses of Dex together with/without α2-adrenergic receptor (AR) blockers. Intestinal tissues were collected to visualize the barrier damage and to measure the indexes of oxidative stress. For in vitro studies, rat intestinal recess epithelial cells (IEC-6) underwent hypoxia/reoxygenation (H/R), and the protective role of Dex was evaluated after α2A-AR siRNA silencing. OALT resulted in increased oxidative stress, significant intestinal injury, and barrier dysfunction. Dex attenuated OALT-induced oxidative stress and intestinal injury, which was abolished by the pretreatment with the nonspecific α2A-AR siRNA blocker atipamezole and the specific α2A-AR siRNA blocker BRL-44408, but not by the specific 2B/C-AR siRNA blocker ARC239. Silencing of α2A-AR siRNA also attenuated the protective role of Dex on alleviating oxidative stress in IEC-6 cells subjected to H/R. Dex exerted its protective effects by activating Nrf2/HO-1 antioxidative signaling. Collectively, Dex attenuates OALT-induced AGI via α2A-AR-dependent suppression of oxidative stress, which might be a novel potential therapeutic target for OALT-induced AGI.

Inhibition of gap junction composed of Cx43 prevents against acute kidney injury following liver transplantation

Postoperative acute kidney injury (AKI) is a severe complication after liver transplantation (LT). Its deterioration and magnification lead to the increase in mortality. Connexin43 (Cx43) mediates direct transmission of intracellular signals between neighboring cells, always considered to be the potent biological basis of organ damage deterioration and magnification. Thus, we explored the effects of Cx43 on AKI following LT and its related possible mechanism. In this study, alternations of Cx43 expression were observed in 82 patients, receiving the first-time orthotopic LT. We built autologous orthotopic liver transplantation (AOLT) models with Sprague–Dawley (SD) rats in vivo, and hypoxia-reoxygenation (H/R) or lipopolysaccharide (LPS) pretreatment models with kidney tubular epithelial cells (NRK-52E) in vitro, both of which were the most important independent risk factors of AKI following LT. Then, different methods were used to alter the function of Cx43 channels to determine its protective effects on AKI. The results indicated that patients with AKI suffering from longer time of tracheal intubation or intensive care unit stay, importantly, had significantly lower survival rate at postoperative 30 days and 3 years. In rat AOLT models, as Cx43 was inhibited with heptanol, postoperative AKI was attenuated significantly. In vitro experiments, downregulation of Cx43 with selective inhibitors, or siRNA protected against post-hypoxic NRK-52E cell injuries caused by H/R and/or LPS, while upregulation of Cx43 exacerbated the above-mentioned cell injuries. Of note, alternation of Cx43 function regulated the content of reactive oxygen species (ROS), which not only mediated oxidative stress and inflammation reactions effectively, but also regulated necroptosis. Therefore, we concluded that Cx43 inhibition protected against AKI following LT through attenuating ROS transmission between the neighboring cells. ROS alternation depressed oxidative stress and inflammation reaction, which ultimately reduced necroptosis. This might offer new insights for targeted intervention for organ protection in LT, or even in other major surgeries.

Role of necroptosis in intestinal injury induced by autologous orthotopic liver transplantation in rats

Objective To evaluate the role of necroptosis in intestinal injury induced by autologous orthotopic liver transplantation (AOLT) in rats. Methods Twenty-four SPF adult male Sprague-Dawley rats, aged 10-12 weeks, weighing 250-280 g, were divided into 3 groups (n=8 each) using a random number table method: sham operation group (group S), AOLT group (group T) and necroptosis inhibitor necrostatin-1 group (group N). Necrostatin-1 1.0 mg/kg and the equal volume of dimethyl sulfoxide (DMSO) were intraperitoneally injected at 30 min before surgery in N and T groups, respectively.Blood samples were collected from the inferior vena cava at 6 h after opening the portal vein (at 6 h after the end of surgery in group S) for determination of serum diamine oxidase (DAO), D-lactic acid (D-LA) and intestinal fatty acid binding protein (I-FABP) concentrations by enzyme-linked immunosorbent assay.Rats were sacrificed after blood sampling, and the intestine was removed for examination of the pathological changes (with a light microscope) and for determination of malondialdehyde (MDA) contents and superoxide dismutase (SOD) activities (using a spectrophotometer), and the expression of receptor-interacting protein kinase-1 (RIPK1), RIPK3 and mixed lineage kinase domain-like protein (MLKL) in intestinal tissues (by Western blot). Intestinal damage was assessed and scored using Chiu′s scoring system. Results Compared with group S, the serum DAO, D-LA and I-FABP concentrations, MDA content and Chiu′s score were significantly increased, SOD activity was decreased, and the expression of RIPK1, RIPK3 and MLKL was up-regulated in group T (P<0.05). Compared with group T, the serum DAO, D-LA and I-FABP concentrations, MDA content and Chiu′s score were significantly decreased, the SOD activity was increased, and the expression of RIPK1, RIPK3 and MLKL was down-regulated in group N (P<0.05). Conclusion Necroptosis is involved in the pathophysiological process of intestinal injury induced by AOLT in rats. Key words: Liver transplantation; Intestine; Necrosis

Role of necroptosis in liver injury in rats undergoing autologous orthotopic liver transplantation

Objective To evaluate the role of necroptosis in liver injury in rats undergoing autologous orthotopic liver transplantation (AOLT). Methods Twenty-four SPF adult male Sprague-Dawley rats, weighing 250-280 g, were divided into 3 groups (n=8 each) using a random number table method: sham operation group (group S), AOLT group (group T) and necroptosis inhibitor necrostatin-1 group (group N). Rats were anesthetized using intraperitoneal 5% chloral hydrate 0.5 ml/100 g. A standard model of OALT was established as previously described by Yao et al.in T and N groups.Necrostatin-1 1.0 mg/kg and the equal volume of dimethyl sulfoxide were intraperitoneally injected at 30 min before surgery in N and T groups, respectively.Blood samples were collected from the inferior vena cava at 6 h after opening the portal vein (at 6 h after operation in group S) for determination of serum aspartate amino-transferase (AST) and alanine amino- transferase (ALT) concentrations.The livers were removed for examination of the pathological changes (with a light microscope) and for determination of the malondialdehyde (MDA) contents and superoxide dismutase (SOD) activity (using a spectrophotometer) and expression of receptor-interacting protein kinase-1 (RIPK1), RIPK3 and mixed lineage kinase domain-like (MLKL) in liver tissues (by Western blot). The damage to livers was evaluated using Suzuki′s scoring system. Results Compared with group S, the serum AST and ALT concentrations, Suzuki′s score of liver tissues and MDA content were significantly increased, the SOD activity was decreased, and the expression of RIPK1, RIPK3 and MLKL was up-regulated in group T (P<0.05). Compared with group T, the serum AST and ALT concentrations, Suzuki′s score of liver tissues and MDA content were significantly decreased, the SOD activity was increased, and the expression of RIPK1, RIPK3 and MLKL was down-regulated in group N (P<0.05). Conclusion Necroptosis is involved in liver injury in rats undergoing AOLT. Key words: Liver transplantation; Reperfusion injury; Necrosis

S-Adenosylmethionine attenuates bile duct early warm ischemia reperfusion injury after rat liver transplantation

Warm ischemia reperfusion injury (IRI) plays a key role in biliary complication, which is a substantial vulnerability of liver transplantation. The early pathophysiological changes of IRI are characterized by an excessive inflammatory response. S-Adenosylmethionine (SAM) is an important metabolic intermediate that modulates inflammatory reactions; however, its role in bile duct warm IRI is not known. In this study, male rats were treated with or without SAM (170 μmol/kg body weight) after orthotopic autologous liver transplantation. The histopathological observations showed that bile duct injury in the IRI group was more serious than in the SAM group. The alanine aminotransferase (ALT), alkaline phosphatase (ALP) and direct bilirubin (DBIL) levels in the serum of the IRI group were significantly increased compared to the SAM group (P < .05). Simultaneously, SAM effectively improved the survival of the transplant recipients. Furthermore, the H2O2 and malondialdehyde (MDA) of the IRI group were much higher compared to the SAM group (P < .05). The GSH/GSSG ratio in the SAM group was significantly increased by SAM treatment compared to the IRI group (P < .05). SAM administration significantly inhibited macrophage infiltration in liver and bile duct tissues, down-regulated TNF-α levels and up-regulated IL-10 expression in bile duct tissues compared to the IRI group (P < .05). The number of apoptotic biliary epithelial cells and caspase-3-positive cells in IRI rat livers were much higher compared to those in SAM-treated rats at 24 h after liver transplantation (P < .05). These data suggested that SAM protected bile ducts against warm IRI by suppressing oxidative stress, inflammatory reactions and apoptosis of biliary epithelial cells after liver transplantation.α

Hypoxia preconditioning protects Ca2+-ATPase activation of intestinal mucosal cells against R/I injury in a rat liver transplantation model.

AIMTo investigate the effect of ischaemia and reperfusion (I/R) injury on the Ca2+-ATPase activation in the intestinal tissue of a rat autologous orthotopic liver transplantation model and to determine if hypoxia preconditioning (HP) therapy induces HIF-1α to protect rat intestinal tissue against I/R injury.METHODSRats received non-lethal hypoxic preconditioning therapy to induce HIF-1α expression. We used an autologous orthotopic liver transplantation model to imitate the I/R injury in intestinal tissue. Then, we detected the microstructure changes in small intestinal tissues, Ca2+-ATPase activity, apoptosis, and inflammation within 48 h postoperatively.RESULTSHIF-1α expression was significantly increased in intestinal tissue at 12 h postoperatively in rats that were exposed to a hypoxic environment for 90 min compared with a non-HP group (HP vs AT, P = 0.0177). Pathological analysis was performed on the intestinal mucosa cells, and the cells in the HP group appeared healthier than the cells in the AT group. The Ca2+-ATPase activity in the small intestinal cells in the AT group was significantly lower after the operation, and the Ca2+-ATPase activity in the HP group recovered faster than that in the AT group at 6 h postoperatively (HP vs AT, P = 0.0106). BCL-2 expression in the HP group was significantly higher than that in the AT group at 12 h postoperatively (HP vs AT P = 0.0010). The expression of the inflammatory factors NO, SOD, IL-6, and TNF-α was significantly lower in the HP group than in the AT group.CONCLUSIONHypoxia-induced HIF-1α could protect intestinal mucosal cells against mitochondrial damage after I/R injury. HP could improve hypoxia tolerance in small intestinal mucosal cells and increase Ca2+-ATPase activity to reduce the apoptosis of and pathological damage to intestinal cells. HP could be a useful way to promote the earlier recovery of intestinal function after graft procedure.

Intravenous Anesthetic Protects Hepatocyte from Reactive Oxygen Species-Induced Cellular Apoptosis during Liver Transplantation In Vivo.

Background Liver transplantation leads to liver ischemia/reperfusion (I/R) injury, resulting in early graft dysfunction and failure. Exacerbations of oxidative stress and inflammatory response are key processes in the development of liver I/R injury. Intravenous anesthetic propofol potent effects on free radical scavenging and protects livers against I/R injury. However, the role and mechanism of propofol-mediated hepatic protection in liver transplantation is poorly understood. The aim of this study was to evaluate the role of propofol postconditioning in the liver I/R injury after liver transplantation. Methods Forty-eight rats were randomly divided into six groups: rats receiving either sham operation or orthotopic autologous liver transplantation (OALT) in the absence or presence of propofol (high dose and low dose) postconditioning or intralipid control or VAS2870 (Nox2 special inhibitor). Eight hours after OALT or sham operation, parameters of organ injury, oxidative stress, inflammation, and NADPH-associated proteins were assessed. Results After OALT, severe liver pathological injury was observed that was associated with increases of serum AST and ALT, which were attenuated by propofol postconditioning. In addition, especially high dose of propofol postconditioning reduced TNF-α, IL-1β, IL-6, TLR4, and NF-κB inflammatory pathway, accompanied with decrease of neutrophil elastase activity, MPO activity, 8-isoprotane, p47phox and gp91phox protein expressions, and increase of SOD activity. Inhibition of Nox2 by VAS2870 conferred similar protective effects in liver transplantation. Conclusion Liver transplantation leads to severe inflammation and oxidative stress with NADPH oxidase activation. Propofol postconditioning reduces liver I/R injury after liver transplantation partly via inhibiting NADPH oxidase Nox2 and the subsequent inflammation and oxidative stress.

SERPINB1 ameliorates acute lung injury in liver transplantation through ERK1/2-mediated STAT3-dependent HO-1 induction

BackgroundPostoperative acute lung injury (ALI) is a severe complication after liver transplantation, which severely affects postoperative patients’ survival. The underlying mechanism is largely unknown and effective treatment limited. We explored the role of serpin protease inhibitor B1 (SERPINB1), a potent inhibitor of neutrophil serine proteases, in ALI in liver transplantation and its interplay with signal transducer and activator of transcription 3 (STAT3) and heme oxygenase-1 (HO-1). MethodsSprague-Dawley rats underwent orthotopic autologous liver transplantation (OALT) were treated with recombinant SB1 (rSB1) in the absence or presence of STAT3 specific inhibitor, WP1066. Then SB1-siRNA was used to knockdown endogenous SERPINB1. Also, alveolar epithelial cells RLE-6TN and BEAS-2B were exposed to TNF-α without or with SERPINB1 and the roles of STAT3 and HO-1 were examined by respective gene knockdown. Finally, rats were treated with ERK1/2 inhibitor U0126, p38 MAPK inhibitor SB20358, or JNK inhibitor SP600125 after rSB1 pretreatment and then subjected to OALT. ResultsOALT resulted in increased pulmonary inflammation and oxidative stress, accompanied by severe lung injury that was coincident with increased pulmonary SERPINB1, HO-1, and STAT3. SERPINB1 gene knockdown increased post-OALT lung injury and pulmonary inflammation. rSB1 administration dose-dependently reduced post-OALT lung injury and decreased pulmonary inflammation and oxidative stress with concomitant enhanced HO-1 and STAT3 protein expression. These protective effects of SERPINB1 were abolished by STAT3 inhibition. Similarly, in RLE-6TN cells and BEAS-2B cells, TNF-α induced cell injury and increased HO-1 and STAT3. SERPINB1 further increased HO-1 and STAT3 protein expression and attenuated TNF-α-induced cellular oxidative stress, apoptotic cells, and mitochondria damage, which were cancelled by STAT3 or HO-1 gene knockdown. Furthermore, these SERPINB1-mediated STAT3/HO-1 activation and pulmonary protective effects were abolished by inhibition of ERK1/2 but not p38 MAPK or JNK. ConclusionsSERPINB1 decreased inflammation, ameliorated oxidative stress in the lung, and attenuated ALI in rats with OALT by activating HO-1 and it does so through STAT3 and it does so by activating ERK1/2.

FK506 reduces liver ischemia-reperfusion injury in a rat model of autologous orthotopic liver transplantation by decreasing HMGB1 release

FK506 reduces liver ischemia-reperfusion injury in a rat model of autologous orthotopic liver transplantation by decreasing HMGB1 release

Propofol attenuated liver transplantation-induced acute lung injury via connexin43 gap junction inhibition.

BackgroundPostoperative acute lung injury (ALI) is a severe complication after liver transplantation, which influences patient survival rate obviously. However, its mechanisms are unclear and effective therapies are still lacking. The current study focused on effects of propofol on liver transplantation-induced ALI and whether its underlying mechanism was relative with connexin43 (Cx43) alternation. The authors postulated that endotoxin induced enhancement of Cx43 gap junction (GJ) plays a critical role in mediating post liver transplantation ALI and that pretreatment with the anesthetic propofol, known to inhibit gap junction, can confer effective protection.MethodsMale Sprague–Dawley rats underwent autologous orthotopic liver transplantation (AOLT) in the absence or presence of treatments with the selective Cx43 inhibitor, enanthol (0.1 mg/kg) and propofol (50 mg/kg), a commonly used anesthetic in clinical anesthesia. In vitro study, BEAS-2B cells, a kind of lung epithelial cell line expressing Cx43, exposed to lipopolysaccharide (LPS), which mainly contributed to ALI. Function of Cx43 GJ was regulated by Cx43 specific inhibitors, gap26 (300 μM) or enhancer, retinoic acid (10 μM) and two specific siRNAs.ResultsCompared with the sham group, AOLT results in ALI obviously with plasma endotoxin increase. Cx43 inhibition decreased ALI through inflammatory reaction reduction. In vitro studies, LPS-induced BEAS-2B cells damage was attenuated by Cx43 function inhibition, but amplified by enhancement. Another important finding was propofol reduced Cx43 function and protected against LPS-mediated BEAS-2B cells damage or AOLT-induced ALI, mechanisms of which were also associated with inflammatory reaction decrease.ConclusionCx43 plays a vital role in liver transplantation-induced ALI. Propofol decreased Cx43 function and protected against ALI in vivo and in vitro. This finding provide a new basis for targeted intervention of organ protection in liver transplantation, even in other kinds of operations.

Dexmedetomidine Protects Rat Liver against Ischemia-Reperfusion Injury Partly by the α2A-Adrenoceptor Subtype and the Mechanism Is Associated with the TLR4/NF-κB Pathway.

Toll-like receptor 4 (TLR4)/nuclear factor kappa B (NF-κB) signaling plays a dominant role in the pathogenesis of liver ischemia-reperfusion (IR) injury. Dexmedetomidine (Dex) protects the liver against IR injury via α2-adrenoceptor activation, but the contribution of TLR4 signaling remains unknown. The authors aimed to examine whether pretreatment with Dex produces hepatic protection and investigate the influence of Dex on TLR4/NF-κB signaling. Dex was given via intraperitoneal injection 30 min prior to orthotopic autologous liver transplantation (OALT) in rats, and three α2-adrenoceptor antagonists including atipamezole (a nonselective α2 receptor blocker), ARC-239 (a specific α2B/C blocker) and BRL-44408 (a specific α2A blocker) were injected intraperitoneally 10 min before Dex administration. Histopathologic evaluation of the liver and the measurement of serum alanine aminotransferase activity, TLR4/NF-κB expression in the liver, and pro-inflammatory factors (serum tumor necrosis factor-α, interleukin-1β and hepatic myeloperoxidase) concentrations were performed 8 h after OALT. Dex ameliorated liver injury after OALT probably by suppressing the TLR4/NF-κB pathway and decreasing inflammatory mediator levels. The protective effects of Dex were reversed by atipamezole and BRL-44408, but not by ARC-239, suggesting that these effects were mediated in part by the α2A subtype. In conclusion, Dex attenuates liver injury partly via the α2A-adrenoceptor subtype, and the mechanism is due to the suppression of the TLR4/NF-κB pathway.