Propofol attenuated acute kidney injury after orthotopic liver transplantation via inhibiting gap junction composed of connexin 32

Connexin32 gap junction channels deliver miR155-3p to mediate pyroptosis in renal ischemia-reperfusion injury

OBJECTIVES

To explore whether the gap junction (GJ) composed by connexin32(Cx32) mediated pyroptosis in renal ischemia-reperfusion(I/R) injury via transmitting miR155-3p, with aim to provide new strategies for the prevention and treatment of acute kidney injury (AKI) after renal I/R.

METHODS

8-10 weeks of male C57BL/ 6 wild-type mice and Cx32 knockdown mice were divided into two groups respectively: control group and renal I/R group. MCC950 (50 mg/kg. ip.) was used to inhibit NLRP3 in vivo. Human kidney tubular epithelial cells (HK - 2) and rat kidney tubular epithelial cells (NRK-52E) were divided into high-density group and low-density group, and treated with hypoxia reoxygenation (H/R) to mimic I/R. The siRNA and plasmid of Cx32, mimic and inhibitor of miR155-3p were transfected into HK - 2 cells respectively. Kidney pathological and functional injuries were measured. Western Blot and immunofluorescent staining were used to observe the expression of NLRP3, GSDMD, GSDMD-N, IL - 18, and mature IL-18. The secretion of IL-18 and IL-1β in serum, kidney tissue and cells supernatant were detected by enzyme-linked immuno sorbent assay (ELISA) kit, and the expression of NLPR3 and miR155-3p were detected by RT-qPCR and fluorescence in situ hybridization (FISH).

RESULTS

Tubular pyroptosis were found to promote AKI after I/R in vivo and Cx32-GJ regulated pyroptosis by affecting the expression of miR155-3p after renal I/R injury. In vitro, H/R could lead to pyroptosis in HK-2 and NRK-52E cells. When the GJ channels were not formed, and Cx32 was inhibited or knockdown, the expression of miR155-3p was significantly reduced and the pyroptosis was obviously inhibited, leading to the reduction of injury and the increase of survival rate. Moreover, regulating the level of miR155-3p could affect survival rate and pyroptosis in vitro after H/R.

CONCLUSIONS

The GJ channels composed of Cx32 regulated tubular pyroptosis in renal I/R injury by transmitting miR155-3p. Inhibition of Cx32 could reduce the level of miR155-3p further to inhibit pyroptosis, leading to alleviation of renal I/R injury which provided a new strategy for preventing the occurrence of AKI. Video Abstract.

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.

Future Directions in Optimizing Anesthesia to Reduce Perioperative Acute Kidney Injury

BACKGROUND

Perioperative acute kidney injury (AKI) is common in surgical patients and is associated with high morbidity and mortality. There are currently few options for AKI prevention and treatment. Due to its complex pathophysiology, there is no efficient medication therapy to stop the onset of the injury or repair the damage already done. Certain anesthetics, however, have been demonstrated to affect the risk of perioperative AKI in some studies. The impact of anesthetics on renal function is particularly important as it is closely related to the prognosis of patients. Some anesthetics can induce anti-inflammatory, anti-necrotic, and anti-apoptotic effects. Propofol, sevoflurane, and dexmedetomidine are a few examples of anesthetics that have protective association with AKI in the perioperative period.

SUMMARY

In this study, we reviewed the clinical characteristics, risk factors, and pathogenesis of AKI. Subsequently, the protective effects of various anesthetic agents against perioperative AKI and the latest research are introduced.

KEY MESSAGE

This work demonstrates that a thorough understanding of the reciprocal effects of anesthetic drugs and AKI is crucial for safe perioperative care and prognosis of patients. However, more complete mechanisms and pathophysiological processes still need to be further studied.

Postoperative acute kidney injury after volatile or intravenous anesthesia: a meta-analysis

Postoperative acute kidney injury (AKI) is a common complication after surgery. The pathophysiology of postoperative AKI is complex. One potentially important factor is anesthetic modality. We, therefore, conducted a meta-analysis of the available literature regarding anesthetic modality and incidence of postoperative AKI. Records were retrieved until January 17, 2023, with the search terms ("propofol" OR "intravenous") AND ("sevoflurane" OR "desflurane" OR "isoflurane" OR "volatile" OR "inhalational") AND ("acute kidney injury" OR "AKI"). A meta-analysis for common effects and random effects was performed after exclusion assessment. Eight records were included in the meta-analysis with a total of 15,140 patients (n = 7,542 propofol and n = 7,598 volatile). The common and random effects model revealed that propofol was associated with a lower incidence of postoperative AKI compared with volatile anesthesia [odds ratio: 0.63 (95% confidence interval: 0.56-0.72) and 0.49 (95% confidence interval: 0.33-0.73), respectively]. In conclusion, the meta-analysis revealed that propofol anesthesia is associated with a lower incidence of postoperative AKI compared with volatile anesthesia. This may motivate choosing propofol-based anesthesia in patients with increased risk of postoperative AKI due to preexisting renal impairment or surgery with a high risk of renal ischemia.NEW & NOTEWORTHY This study analyzed the available literature on anesthetic modality and incidence of postoperative AKI. The meta-analysis revealed that propofol is associated with lower incidence of AKI compared with volatile anesthesia. It might therefore be considerable to use propofol anesthesia in surgeries with increased susceptibility for developing renal injuries such as cardiopulmonary bypass and major abdominal surgery.

A brief history of liver transplantation and transplant anesthesia

In this review, we describe the major milestones in the development of organ transplantation with a specific focus on hepatic transplantation. For many years, the barriers preventing successful organ transplantation in humans seemed insurmountable. Although advances in surgical technique provided the technical ability to perform organ transplantation, limited understanding of immunology prevented successful organ transplantation. The breakthrough to success was the result of several significant discoveries between 1950 and 1980 involving improved surgical techniques, the development of effective preservative solutions, and the suppression of cellular immunity to prevent graft rejection. After that, technical innovations and laboratory and clinical research developed rapidly. However, these advances alone could not have led to improved transplant outcomes without parallel advances in anesthesia and critical care. With increasing organ demand, it proved necessary to expand the donor pool, which has been achieved with the use of living donors, split grafts, extended criteria organs, and organs obtained through donation after cardiac death. Given this increased access to organs and organ resources, the number of transplantations performed every year has increased dramatically. New regulatory organizations and transplant societies provide critical oversight to ensure equitable organ distribution and a high standard of care and also perform outcome analyses. Establishing dedicated transplant anesthesia teams results in improved organ transplantation outcomes and provides a foundation for developing new standards for other subspecialties in anesthesiology, critical care, and medicine overall. Through a century of discovery, the success we enjoy at the present time is the result of the work of well-organized multidisciplinary teams following standardized protocols and thereby saving thousands of lives worldwide each year. With continuing innovation, the future is bright.

Connexins in endothelial cells as a therapeutic target for solid organ transplantation

Connexins are a class of membrane proteins widely distributed throughout the body and have various functions based on their location and levels of expression. More specifically, connexin proteins expressed in endothelial cells (ECs) have unique roles in maintaining EC barrier integrity and function-a highly regulated process that is critical for pro-inflammatory and pro-coagulant reactions. In this minireview, we discuss the regulatory influence connexin proteins have in maintaining EC barrier integrity and their role in ischemia-reperfusion injury as it relates to organ transplantation. It is evident that certain isoforms of the connexin protein family are uniquely positioned to have far-reaching effects on preserving organ function; however, there is still much to be learned of their roles in transplant immunology and the application of this knowledge to the development of targeted therapeutics.

Bibliometric and visual analysis of nephrotoxicity research worldwide

Background: Nephrotoxicity of drugs contributes to acute kidney injury with high mortality and morbidity, which crucially limits the application and development of drugs. Although many publications on nephrotoxicity have been conducted globally, there needs to be a scientometric study to systematically analyze the intellectual landscape and frontiers research trends in the future.

Methods: Publications on nephrotoxicity from 2011 to 2021 were collected to perform bibliometric visualization using VOSviewer, CiteSpace, and Scimago Graphica software based on the Web of Science Core Collection.

Results: A total of 9,342 documents were analyzed, which were primarily published in the United States (1,861), China (1,724), and Egypt (701). For institutions, King Saud University (166) had the most publications; Food and Chemical Toxicology, PLOS One, and Antimicrobial Agents and Chemotherapy were productive journals, primarily concentrating on the mechanisms of nephrotoxicity and renoprotective in cisplatin and antibiotics, especially in oxidative stress. Burst detection suggested that cisplatin, piperacillin-tazobactam, vancomycin-induced nephrotoxicity, antioxidants, and new biomaterials are frontiers of research.

Conclusion: This study first provides an updated perspective on nephrotoxicity and renoprotective strategies and mechanisms. This perspective may benefit researchers in choosing suitable journals and collaborators and assisting them in the deep understanding of the nephrotoxicity and renoprotective hotspots and frontiers.

Quantitative Fluorescence Imaging of the Intracellular Redox State by Real-Time Spatial and Temporal Simultaneous Analysis of O2•- Levels and Keap1 Translocation

Dysregulated redox homeostasis under pathological conditions can eventually culminate in oxidative stress and associated disease damage. Spatial and temporal regulation of intracellular redox states involves two crucial parameters for elucidating oxidative stress-related molecular mechanisms. However, the lack of methods for real-time analysis of redox states is a considerable hurdle for the in-depth interpretation of pathogenic mechanisms. Herein, given the over-produced reactive oxygen species (ROS) and the translocation of redox-sensitive proteins as the potential biomarkers of oxidative stress, we developed a novel ROS-macromolecular protein synergistic imaging strategy that relied on a small-molecule fluorescent CPR-SK probe. The CPR-SK specifically activated the caffeic acid moieties or targeting peptides (EWWW) toward the biomarkers, including superoxide (O₂^•-) fluctuations and Keap1 translocation, achieving simultaneous real-time imaging of dual molecular events during oxidative stress. Importantly, in situ, CPR-SK exhibited both gentle elevation of O₂^•- and subsequent migration of Keap1 from the cytoplasm to the nucleus, which were key indicators for determining slight injuries induced by hepatic ischemia-reperfusion. The results clearly demonstrated that this spatiotemporal imaging method was a reliable tool for analyzing dynamic intracellular changes of the redox state and elucidating the molecular mechanisms of oxidative stress-related diseases.

Ropivacaine with intraspinal administration alleviates preeclampsia-induced kidney injury via glycocalyx /alpha 7 nicotinic acetylcholine receptor pathway

Preeclampsia is characterized by hypertension and proteinuria, which is associated with kidney injury. Glycocalyx (GCX) degradation mediated endothelial injury can result in proteinuria and kidney damage. alpha 7 nicotinic acetylcholine receptor (α7nAChR) connects nervous and immune systems to respond to stress or injury. We aimed to explore the protective effect and mechanism of intraspinal analgesia on maternal kidney injury in preeclampsia. Endotoxin-induced preeclampsia rats treated with ropivacaine via intraspinal administration. Renal histopathological examination was performed, cell apoptosis in the kidney, the levels of Glycocalyx markers of Syndecan-1 and heparin sulfate (HS) in maternal serum, Syndecan-1 along with α7nAChR in the kidney were measured. Our results showed that kidney injury was obviously in preeclampsia rats with proteinuria, endothelial damage, higher apoptosis rate, increasing levels of Syndecan-1 and HS in serum, upregulated Syndecan-1 expression but downregulated α7nAChR expression in kidney. Preeclampsia rats treated with intraspinal injected ropivacaine attenuated preeclampsia-induced kidney injury as Syndecan-1 and HS were decreased in serum, Syndecan-1 expression was suppressed as well as α7nAChR was activated in the kidney. Our results suggested that Ropivacaine administered through the spinal canal may protect preeclampsia-induced renal injury by decreasing GCX and α7nAChR activation.

Anesthesia and the renal sympathetic nervous system in perioperative AKI

Approximately 7% of patients undergoing non-cardiac surgery with general anesthesia develop postoperative acute kidney injury (AKI). It is well-known that general anesthesia may have an impact on renal function and water balance regulation, but the mechanisms and potential differences between anesthetics are not yet completely clear. Recently published large animal studies have demonstrated that volatile (gas) anesthesia stimulates the renal sympathetic nervous system more than intravenous propofol anesthesia, resulting in decreased water and sodium excretion and reduced renal perfusion and oxygenation. Whether this is the case also in humans remains to be clarified. Increased renal sympathetic nerve activity may impair renal excretory function and oxygenation and induce structural injury in ischemic AKI models and could therefore be a contributing factor to AKI in the perioperative setting. This review summarizes anesthetic agents' effects on the renal sympathetic nervous system that may be important in the pathogenesis of perioperative AKI.

Literature review of the mechanisms of acute kidney injury secondary to acute liver injury

People exposed to liver ischaemia reperfusion (IR) injury often develop acute kidney injury and the combination is associated with significant morbidity and mortality. Molecular mediators released by the liver in response to IR injury are the likely cause of acute kidney injury (AKI) in this setting, but the mediators have not yet been identified. Identifying the mechanism of injury will allow the identification of therapeutic targets which may modulate both liver IR injury and AKI following liver IR injury.

Connexin 43 prevents the progression of diabetic renal tubulointerstitial fibrosis by regulating the SIRT1-HIF-1α signaling pathway

Hyperglycemia-induced renal epithelial-to-mesenchymal transition (EMT) is a key pathological factor in diabetic renal tubulointerstitial fibrosis (RIF). Our previous studies have shown that connexin 43 (Cx43) activation attenuated the development of diabetic renal fibrosis. However, whether Cx43 regulates the EMT of renal tubular epithelial cells (TECs) and the pathological process of RIF under the diabetic conditions remains to be elucidated. In the present study, we identified that Cx43 protein expression was down-regulated in the kidney tissues of db/db mice as well as in high glucose (HG)-induced NRK-52E cells. Overexpression of Cx43 improved renal function in db/db spontaneous diabetic model mice, increased SIRT1 levels, decreased hypoxia-inducible factor (HIF)-1α expression, and reduced production of EMT markers and extracellular matrix (ECM) components. Additionally, Cx43 overexpression inhibited the EMT process and reduced the expression of ECM components such as fibronectin (FN), Collagen I, and Collagen IV in HG-induced NRK-52E cells, whereas Cx43 deficiency had the opposite effects. Mechanistically, Cx43 in a carboxyl-terminal signal transduction-dependent manner could up-regulate SIRT1 expression and enhance SIRT1-dependent deacetylation of HIF-1α to reduce HIF-1α activity, which eventually ameliorated renal EMT and diabetic RIF. Our study indicates the essential role of Cx43 in regulating renal EMT and diabetic RIF via regulating the SIRT1-HIF-1α signaling pathway and provides an experimental basis for Cx43 as a potential target for diabetic nephropathy (DN).

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

AIMS

Acute 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.

METHODS

Male 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 FINDINGS

During 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.

CONCLUSION

The 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.

Perioperative Renoprotection: General Mechanisms and Treatment Approaches

In the perioperative setting, acute kidney injury (AKI) is a frequent complication, and AKI itself is associated with adverse outcomes such as higher risk of chronic kidney disease and mortality. Various risk factors are associated with perioperative AKI, and identifying them is crucial to early interventions addressing modifiable risk and increasing monitoring for nonmodifiable risk. Different mechanisms are involved in the development of postoperative AKI, frequently picturing a multifactorial etiology. For these reasons, no single renoprotective strategy will be effective for all surgical patients, and efforts have been attempted to prevent kidney injury in different ways. Some renoprotective strategies and treatments have proven to be useful, some are no longer recommended because they are ineffective or even harmful, and some strategies are still under investigation to identify the best timing, setting, and patients for whom they could be beneficial. With this review, we aim to provide an overview of recent findings from studies examining epidemiology, risk factors, and mechanisms of perioperative AKI, as well as different renoprotective strategies and treatments presented in the literature.

Connexin 32 deficiency protects the liver against ischemia/reperfusion injury

Hepatic ischemia/reperfusion (I/R) injury is a common complication in the clinical setting. Our previous study has shown that connexin 32 (Cx32) plays a major role in renal I/R injury; however, the role of Cx32 in hepatic I/R injury remains unknown. Liver tissue and serum samples from patients undergoing orthotopic liver transplantation (OLT) were used to evaluate the function of Cx32 in OLT post-reperfusion injury. Then, partial hepatic ischemia was established in global Cx32 knockout mice and wild-type mice followed by reperfusion. Hepatic injury markers were examined. Cx32 small interfering RNA and the p53 inhibitor, pifithrin-α, tenovin-1 were used to examine the relationship between Cx32 and the p53/puma pathways in the BRL-3A and murine primary hepatocytes hypoxia/reoxygenation (H/R) model. Corresponding to liver damage, Cx32 was significantly induced both during OLT in human patients and partial hepatic I/R in mice. Cx32 KO mice exhibited less liver injury than controls. Cx32 deficiency significantly suppressed the p53/puma pathways and hepatocyte apoptosis. Similar results were observed in the BRL-3A and murine primary hepatocytes H/R model. Propofol protected against OLT post-reperfusion injury and hepatocyte apoptosis by inhibiting Cx32. In conclusion Cx32 is a novel regulator of hepatic I/R injury through the modulation of hepatocyte apoptosis and damage, largely via the p53/puma signaling pathway.

Dexmedetomidine Attenuates Monocyte-Endothelial Adherence via Inhibiting Connexin43 on Vascular Endothelial Cells

Current studies have identified the multifaceted protective functions of dexmedetomidine on multiple organs. For the first time, we clarify effects of dexmedetomidine on monocyte-endothelial adherence and whether its underlying mechanism is relative to connexin43 (Cx43), a key factor regulating monocyte-endothelial adherence. U937 monocytes and human umbilical vein endothelial cells (HUVECs) were used to explore monocyte-endothelial adherence. Two special siRNAs were designed to knock down Cx43 expression on HUVECs. U937-HUVEC adhesion, adhesion-related molecules, and the activation of the MAPK (p-ERK1/2, p-p38, and p-JNK1/2) signaling pathway were detected. Dexmedetomidine, at its clinically relevant concentrations (0.1 nM and 1 nM), was given as pretreatments to HUVECs. Its effects on Cx43 and U937-HUVEC adhesion were also investigated. The results show that inhibiting Cx43 on HUVECs could attenuate the contents of MCP-1, soluble ICAM-1 (sICAM-1), soluble VCAM-1 (sVCAM-1), and the nonprocessed variants of the adhesion molecules ICAM-1 and VCAM-1 and ultimately result in U937-HUVEC adhesion decrease. Meanwhile, the activation of MAPKs was also inhibited. U0126 (inhibiting p-ERK1/2) and SB202190 (inhibiting p38) decreased the contents of MCP-1, sICAM-1, and sVCAM-1, but SP600125 (inhibiting p-JNK1/2) had none of these effects. ICAM-1 and VCAM-1 could be regulated in a similar way. Dexmedetomidine pretreatment inhibited Cx43 on HUVECs, the activation of MAPKs, and U937-HUVEC adhesion. Therefore, we conclude that dexmedetomidine attenuates U937-HUVEC adhesion via inhibiting Cx43 on HUVECs modulating the activation of MAPK signaling pathways.

A narrative review of the impact of surgery and anaesthesia on acute kidney injury

The epidemiology of peri-operative acute kidney injury varies depending on the definition, type of surgery and acute and chronic comorbidities. Haemodynamic instability, disturbance of the microcirculation, endothelial dysfunction, inflammation and tubular cell injury are the main factors contributing to the pathogenesis. There are no specific therapies. The most effective strategies to protect renal function during the peri-operative period are: the avoidance of nephrotoxic insults; optimisation of haemodynamics; prevention of hypotension; and meticulous fluid management, including avoidance of both hypovolaemia and hypervolaemia. Peri-operative acute kidney injury is associated with an increased risk of short- and long-term postoperative complications, including a longer stay in hospital, development of premature chronic kidney disease and increased mortality. Resource utilisation and healthcare costs are also higher. In future, the development of advanced clinical prediction scores, new imaging and monitoring techniques and the application of new biomarkers for acute kidney injury have the prospect of identifying acute kidney injury earlier and allowing a more personalised management approach with the aim of reducing the global burden of acute kidney injury.

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.

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.

General Anesthetic Agents and Renal Function after Nephrectomy

The association between the choice of general anesthetic agents and the risk of acute kidney injury (AKI) and long-term renal dysfunction after nephrectomy has not yet been evaluated. We reviewed 1087 cases of partial or radical nephrectomy. The incidence of postoperative AKI, new-onset chronic kidney disease (CKD) and CKD upstaging were compared between general anesthetic agent groups (propofol, sevoflurane, and desflurane). Four different propensity score analyses were performed to minimize confounding for each pair of comparison (propofol vs. sevoflurane; propofol vs. desflurane; sevoflurane vs. desflurane; propofol vs. volatile agents). Study outcomes were compared before and after matching. Kaplan-Meier survival curve analysis was performed to compare renal survival determined by the development of new-onset CKD between groups up to 36 months after nephrectomy. Propofol was associated with a lower incidence of AKI (propofol 23.2% vs. sevoflurane 39.5%, p = 0.004; vs. propofol 21.0% vs. desflurane 34.3%, p = 0.031), a lower incidence of CKD upstaging (propofol 27.2% vs. sevoflurane 58.4%, p < 0.001; propofol 32.4% vs. desflurane 48.6%, p = 0.017) and better three-year renal survival after nephrectomy compared to sevoflurane or desflurane group (Log-rank test propofol vs. sevoflurane p < 0.001; vs. desflurane p = 0.015) after matching. Propofol was also associated with a lower incidence of new-onset CKD after nephrectomy compared to sevoflurane after matching (p < 0.001). There were no significant differences between sevoflurane and desflurane. However, subgroup analysis of partial nephrectomy showed a significant difference only in CKD upstaging. In conclusion, propofol, compared to volatile agents, could be a better general anesthetic agent for nephrectomy to attenuate postoperative renal dysfunction. However, limitations of the retrospective study design and inconsistent results of the subgroup analysis preclude firm conclusions.

Propofol attenuates monocyte-endothelial adhesion via modulating connexin43 expression in monocytes

AIMS

Monocyte-endothelial adhesion is considered to be the primary initiator of inflammatory vascular diseases, such as atherosclerosis. Connexin 43 (Cx43) has been reported to play an important part in this process, however, the underlying mechanisms are not fully understood. Intravenous anesthetics, propofol is commonly used in the perioperative period and in the intensive care unit, and considered to have good anti-inflammatory and antioxidant effects. Thus, we speculate that propofol could influence monocyte-endothelial adhesion, and explore whether its possible mechanism is relative with Cx43 expression in U937 monocytes influencing cell adhesion of U937 monocytes to human umbilical vein endothelial cells (HUVEC).

MAIN METHODS

Cx43-siRNAs or pc-DNA-Cx43 were used to alter Cx43 expression in U937 monocytes. Propofol was given as pretreatments to U937 monocytes. Then, cell adhesion, ZO-1, LFA-1, VLA-4, COX and MCP-1 were determined. PI3K/AKT/NF-κB signaling pathway was explored to clarify the possible mechanism.

KEY FINDINGS

Alternation of Cx43 expression affects cell adhesion and adhesion molecules significantly, such as ZO-1, LFA-1, VLA-4, COX-2 and MCP-1, the mechanism of which is relative with Cx43 influencing the activation of PI3K/AKT/NF-κB signaling pathway. Preconditioning with propofol at its clinically relevant anesthesia concentration attenuates cell adhesion. Propofol not only decreases Cx43 expression in U937 monocytes, but also depresses the activation of PI3K/AKT/NF-κB signaling pathway.

SIGNIFICANCE

Modulation Cx43 expression in U937 monocytes could affect cell adhesion via regulating the activation of PI3K/AKT/NF-κB signaling pathway. Propofol attenuates cell adhesion via inhibiting Cx43 and its downstream signaling pathway of PI3K/AKT/NF-κB.

Down-regulation of Cx43 expression on PIH-HUVEC cells attenuates monocyte-endothelial adhesion

INTRODUCTION

Pregnancy-induced hypertension (PIH) is the most common serious complication of pregnancy, resulting in significant maternal and fetal morbidity and mortality. Vasospasm is the main pathogenesis of PIH, which leads to the hemodynamic changes and the injury of vascular endothelial cells. However, the underlying mechanism is still unclear. Monocyte-endothelial adhesion is always considered to be one of the most important indicators of vascular endothelial cell injury. Connexin43 (Cx43) plays an important part in monocyte-endothelial adhesion. Thus, we explored effects of Cx43 on cell adhesion in PIH-induced vascular endothelial cells injury.

METHODS

We obtained human umbilical vein endothelial cells (HUVECs) from patients with or without PIH. Different methods, such as inhibitors: oleamide and Gap26, or specific siRNA were used to alter Cx43 channels function or protein expression in normal or PIH-HUVECs. U937-HUVECs adhesion, adhesion molecules expression, such as VCAM-1 and ICAM-1, and the activity of PI3K/AKT/NF-κB signaling pathway were determined.

RESULTS

Monocyte-endothelial adhesion on PIH-HUVECs was much more obvious than that on normal HUVECs. Inhibition of Cx43 protein expression could attenuate cell adhesion significantly, however, function of Cx43 channels had no effects on it. Alternation of Cx43 protein expression on PIH-HUVECs mediated VCAM-1 and ICAM-1 expression via regulating the activity of PI3K/AKT/NF-κB signaling pathway.

CONCLUSIONS

We firstly reported Cx43 protein expression on PIH-HUVECs was much higher than that on normal HUVECs. Elevation of Cx43 protein expression within the vasculature resulted in PI3K/AKT/NF-κB signaling pathway activation and VCAM-1 and ICAM-1 over-expression, which ultimately lead to monocyte-endothelial adhesion increase.

Crosstalk Between Connexin32 and Mitochondrial Apoptotic Signaling Pathway Plays a Pivotal Role in Renal Ischemia Reperfusion-Induced Acute Kidney Injury

Aims: Perioperative acute kidney injury (AKI) resulting from renal ischemia reperfusion (IR) is not conducive to the postoperative surgical recovery. Our previous study demonstrated that reactive oxygen species (ROS) transmitted by gap junction (GJ) composed of connexin32 (Cx32) contributed to AKI. However, the precise underlying pathophysiologic mechanisms were largely unknown. This study focuses on the underlying mechanisms related to ROS transmitted by Cx32 responsible for AKI aggravation. Results: In a set of in vivo studies, renal IR was found to cause severe impairment in renal tissues with massive ROS generation, which occurred contemporaneously with activation of NF-κB/p53/p53 upregulated modulator of apoptosis (PUMA)-mediated mitochondrial apoptosis pathways. Cx32 deficiency alleviated renal IR-induced AKI, and simultaneously attenuated ROS generation and distribution in renal tissues, which further inhibited NF-κB/p53/PUMA-mediated mitochondrial apoptotic pathways. Correspondingly, in a set of in vitro studies, hypoxia reoxygenation (HR)-induced cellular injury, and cell apoptosis in both human kidney tubular epithelial cells (HK-2s) and rat kidney tubular epithelial cells (NRK52Es) were significantly attenuated by Cx32 inhibitors or Cx32 gene knockdown. More importantly, Cx32 inhibition not only decreased ROS generation and distribution in human or rat kidney tubular epithelial cells but also inhibited its downstream NF-κB/p53/PUMA-mediated mitochondrial apoptotic pathway activation. Innovation and Conclusion: This is the first identification of the underlying mechanisms of IR-induced renal injury integrally which demonstrates the critical role played by Cx32 in IR-induced AKI. Moreover, GJ composed of Cx32 manipulates ROS generation and distribution between neighboring cells, and alters activation of NF-κB/p53/PUMA-mediated mitochondrial apoptotic pathways. Both inhibiting Cx32 function and scavenging ROS effectively reduce mitochondrial apoptosis and subsequently attenuate AKI, providing effective strategies for kidney protection.

Involvement of gap junctions in propylthiouracil-induced cytotoxicity in BRL-3A cells

Gap junctions (GJs), which are important plasma membrane channels for the transfer of signaling molecules between adjacent cells, have been implicated in drug-induced liver injury. However, the influence and the underlying mechanisms of GJs in propylthiouracil (PTU)-induced hepatotoxicity are unclear. In the present study, distinct manipulations were performed to regulate GJ function in the BRL-3A rat liver cell line. The results indicated that the toxic effect of PTU in BRL-3A cells was mediated by GJ intercellular communication, as cell death was significantly attenuated in the absence of functional GJ channels. Furthermore, the specific knockdown of connexin-32 (Cx32; a major GJ component protein in hepatocytes) using small interfering RNA was observed to decrease necrosis, intracellular PTU content and the level of reactive oxygen species (ROS) following PTU exposure. These observations demonstrated that suppressing GJ Cx32 could confer protection against PTU-induced cytotoxicity through decreasing the accumulation of PTU and ROS. To the best of our knowledge, the present study is the first to demonstrate the role and possible underlying mechanisms of GJs in the regulation of PTU-induced toxicity in BRL-3A rat liver cells.

Cx43 Inhibition Attenuates Sepsis-Induced Intestinal Injury via Downregulating ROS Transfer and the Activation of the JNK1/Sirt1/FoxO3a Signaling Pathway

Intestinal injury has long been considered to play a crucial role in the pathophysiology of sepsis and has even been characterized as the “motor” of it. Thus, we explored the effects of connexin43 (Cx43) on sepsis-induced intestinal injury in order to provide potential therapeutic strategies. Rat cecal ligation and puncture (CLP) models in vivo and cell models (IEC-6 cells) pretreated with LPS in vitro were used in the current study. Firstly, different methods, such as Cx43 inhibitors (18-α-GA and oleamide) or siRNA targeting Cx43 and N-acetyl cysteine (NAC) (a kind of ROS scavenger), were used to observe the effects of Cx43 channels mediating ROS transfer on intestinal injury. Secondly, the influence of ROS content on the activity of the JNK1/Sirt1/FoxO3a signaling pathway was explored through the application of NAC, sp600125 (a JNK1 inhibitor), and nicotinamide (a Sirt1 inhibitor). Finally, luciferase assays and ChIP were used to determine the direct regulation of FoxO3a on proapoptotic proteins, Bim and Puma. The results showed that sepsis-induced intestinal injury presented a dynamic change, coincident with the alternation of Cx43 expression. The inhibition of Cx43 attenuated CLP-induced intestinal injury in vivo and LPS-induced IEC-6 injury in vitro. The changes of Cx43 channel function regulated ROS transfer between the neighboring cells, which mediated the activation of the JNK1/Sirt1/FoxO3a signaling pathway. FoxO3a directly affected its downstream target genes, Bim and Puma, which are responsible for cell or tissue apoptosis. In summary, our results suggest that Cx43 inhibition suppresses ROS transfer and inactivates the JNK1/Sirt1/FoxO3a signaling pathway to protect against sepsis-induced intestinal injury.

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 α ₂-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 α _2A-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 α _2A-AR siRNA blocker atipamezole and the specific α _2A-AR siRNA blocker BRL-44408, but not by the specific _2B/C-AR siRNA blocker ARC239. Silencing of α _2A-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 α _2A-AR-dependent suppression of oxidative stress, which might be a novel potential therapeutic target for OALT-induced AGI.

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, p47^phox and gp91^phox 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.

Propofol attenuates sepsis-induced acute kidney injury by regulating miR-290-5p/CCL-2 signaling pathway

Previous studies have indicated that propofol has immunomodulatory and antioxidative properties. However, the renoprotection effect and the precise mechanisms of propofol in sepsis-induced renal injury remain unclear. The purpose of the present study was to investigate the role of miR-290-5p/CCL-2 signaling in septic mice treatment with propofol. Mice were treated with propofol (50 mg/kg) twice within 24 h. Survival outcome was monitored within 48 h. The mRNA and protein levels were assayed by qRT-PCR and western blotting, respectively. Mouse podocytes (MPC5) were treated with lipopolysaccharide (LPS) to establish the cell model in vitro. The proliferation of MPC5 was monitored using the MTS assay. Cell apoptosis was analyzed by flow cytometry. Propofol improved survival outcome and alleviated acute kidney injury in cecal ligation and puncture-operated mice. Propofol increased miR-290-5p expression and decreased CCL-2 and inflammatory cytokines levels in the kidney for septic mice. We found that miR-290-5p was a direct regulator of CCL-2 in MPC5. Propofol could abrogate LPS-induced growth inhibition and apoptosis in MPC5. Meanwhile, propofol inhibited CCL-2 expression in LPS-treated MPC5, however, knockdown of miR-290-5p abrogated the inhibitory effect propofol on the mRNA and protein expressions of CCL-2. Propofol could serve as an effective therapeutic medication to suppress sepsis-induced renal injury in vivo and in vitro by regulating the miR-290-5p/CCL-2 signaling pathway.

Dexmedetomidine restores septic renal function via promoting inflammation resolution in a rat sepsis model

BACKGROUND

Acute kidney injury occurred after sepsis, resulting in high mortality. This research aims to elucidate the mechanistic effect of DEX on the renal inflammation resolution during sepsis in rats.

METHODS

The rats were randomly divided into a sham group and the other three cecal ligation and puncture (CLP) model groups, based on different treatments: placebo, DEX and 2-adrenergic receptor (AR) inhibitor atipamezole (AT) treatment (DEX + AT) groups. The survival of septic rats within 24 h was recorded. Tissue pathology, plasma IL-1β, IL-6, TNF-α, lipoxygenase-5 and lipoxin A4 were evaluated. Western blotting and immunostaining was used to determine expression of TLR4, IκB, IKK, NF-κB p65 and pp65 in kidney tissue. Then qPCR was used to analyze the mRNA expression of renal α_2A-AR, α_2B-AR and α_2C-AR.

RESULTS

Rat mortality and kidney inflammation were significantly increased in septic rats. Specifically, IL-1β, IL-6 and TNF-α plasma levels, NF-κB activity, and TLR4 expression in rat kidney tissues were increased after CLP. In the DEX treatment group, mortality was reduced, histology changes were minor, and lipoxygenase-5, and lipoxin A4 expression were increased. The expression of IL-1β, IL-6 and TNF-α, NF-κB activity and TLR4 expression in rat kidney tissues were also decreased. These results indicated that DEX treatment alleviates acute kidney injury induced by CLP. However, the effects of DEX were apparently suppressed by atipamezole in the DEX + AT group.

CONCLUSION

The current study demonstrated the protective effect of DEX on CLP-induced kidney injury, which may be effective by attenuating NF-κB pathway activation with lipoxin A4.

Connexin32 plays a crucial role in ROS-mediated endoplasmic reticulum stress apoptosis signaling pathway in ischemia reperfusion-induced acute kidney injury

BACKGROUND

Ischemia-reperfusion (I/R)-induced acute kidney injury (AKI) not only prolongs the length of hospital stay, but also seriously affects the patient's survival rate. Although our previous investigation has verified that reactive oxygen species (ROS) transferred through gap junction composed of connexin32 (Cx32) contributed to AKI, its underlying mechanisms were not fully understood and viable preventive or therapeutic regimens were still lacking. Among various mechanisms involved in organs I/R-induced injuries, endoplasmic reticulum stress (ERS)-related apoptosis is currently considered to be an important participant. Thus, in present study, we focused on the underlying mechanisms of I/R-induced AKI, and postulated that Cx32 mediated ROS/ERS/apoptosis signal pathway activation played an important part in I/R-induced AKI.

METHODS

We established renal I/R models with Cx32+/+ and Cx32-/- mice, which underwent double kidneys clamping and recanalization. ROS scavenger (N-acetylcysteine, NAC) and ERS inhibitors (4-phenyl butyric acid, 4-PBA, and tauroursodeoxycholic acid, TUDCA) were used to decrease the content of ROS and attenuate ERS activation, respectively.

RESULTS

Renal damage was progressively exacerbated in a time-dependent manner at the reperfusion stage, that was consistent with the alternation of ERS activation, including glucose regulated protein 78 (BiP/GRP78), X box-binding protein1, and C/EBP homologous protein expression. TUDCA or 4-PBA application attenuated I/R-induced ERS activation and protected against renal tubular epithelial cells apoptosis and renal damage. Cx32 deficiency decreased ROS generation and distribution between the neighboring cells, which attenuated I/R-induced ERS activation, and improved cell apoptosis and renal damage.

CONCLUSION

Cx32 mediated ROS/ERS/apoptosis signal pathway activation played an important part in I/R-induced AKI. Cx32 deficiency, ROS elimination, and ERS inhibition all could protect against I/R-induced AKI.

A Review of Anesthetic Effects on Renal Function: Potential Organ Protection

BACKGROUND

Renal protection is a critical concept for anesthesiologists, nephrologists, and urologists, since anesthesia and renal function are highly interconnected and can potentially interfere with one another. Therefore, a comprehensive understanding of anesthetic drugs and their effects on renal function remains fundamental to the success of renal surgeries, especially transplant procedures. Some experimental studies have shown that some anesthetics provide protection against renal ischemia/reperfusion (IR) injury, but there is limited clinical evidence.

SUMMARY

The effects of anesthetic drugs on renal failure are particularly important in the context of kidney transplantation, since the conditions of preservation following removal profoundly influence the recovery of organ function. Currently, preservation procedures are typically based on the usage of a cold-storage solution. Some anesthetic drugs induce anti-inflammatory, anti-necrotic, and anti-apoptotic effects. A more thorough understanding of anesthetic effects on renal function can present a novel approach for developing organ-protective strategies. The aim of this review is to discuss the effects of different anesthetic drugs on renal function, with particular focus on IR injury. Many studies have demonstrated the organ-protective effects of some anesthetic drugs, specifically propofol, which indicate the potential of some anesthetics to introduce novel organ protective targets. This is not surprising, since lipid emulsions are major components of propofol, which accumulating data show provide organ protective effects against IR injury. Key Messages: Thorough understanding of the interaction between anesthetic drugs and renal function remains fundamental to the delivery of safe perioperative care and to optimizing outcomes after renal surgeries, particularly transplant procedures. Anesthetics can be repurposed for organ protection with more information about their effects, especially during transplant procedures. Here, we review the effects of different anesthetic drugs - specifically those that contain lipids in their structure, with special reference to IR injury.

Acute Kidney Injury as a Risk Factor for Delirium and Coma during Critical Illness

RATIONALE

Acute kidney injury may contribute to distant organ dysfunction. Few studies have examined kidney injury as a risk factor for delirium and coma.

OBJECTIVES

To examine whether acute kidney injury is associated with delirium and coma in critically ill adults.

METHODS

In a prospective cohort study of intensive care unit patients with respiratory failure and/or shock, we examined the association between acute kidney injury and daily mental status using multinomial transition models adjusting for demographics, nonrenal organ failure, sepsis, prior mental status, and sedative exposure. Acute kidney injury was characterized daily using the difference between baseline and peak serum creatinine and staged according to Kidney Disease Improving Global Outcomes criteria. Mental status (normal vs. delirium vs. coma) was assessed daily with the Confusion Assessment Method for the ICU and Richmond Agitation-Sedation Scale.

MEASUREMENTS AND MAIN RESULTS

Among 466 patients, stage 2 acute kidney injury was a risk factor for delirium (odds ratio [OR], 1.55; 95% confidence interval [CI], 1.07-2.26) and coma (OR, 2.04; 95% CI, 1.25-3.34) as was stage 3 injury (OR for delirium, 2.56; 95% CI, 1.57-4.16) (OR for coma, 3.34; 95% CI, 1.85-6.03). Daily peak serum creatinine (adjusted for baseline) values were also associated with delirium (OR, 1.35; 95% CI, 1.18-1.55) and coma (OR, 1.44; 95% CI, 1.20-1.74). Renal replacement therapy modified the association between stage 3 acute kidney injury and daily peak serum creatinine and both delirium and coma.

CONCLUSIONS

Acute kidney injury is a risk factor for delirium and coma during critical illness.

Deficiency of gap junction composed of connexin43 contributes to oxaliplatin resistance in colon cancer cells

Although comprehensive strategies in the treatment of colorectal cancer have been developed for a number of years, the five-year survival rate of metastatic colon cancer remains less than 10%. Oxaliplatin, a commonly used chemotherapeutic agent for metastatic colon cancer, improves the response rate of patients and prolongs patients' progression-free survival. However, the generation of resistance limits the clinical application of oxaliplatin, and the mechanisms of this remain unclear. The present study mainly investigated the effect of the gap junction (GJ) composed of connexin43 (Cx43) on oxaliplatin cytotoxicity in colon cancer cells. Three different methods with distinct mechanisms were used to change the function of Cx43 GJs, including cell culture at different densities, pretreatment with a specific inhibitor or enhancer, and special gene knockdown, to observe the cytotoxicity of oxaliplatin and the level of reactive oxygen species (ROS) mediated by Cx43 GJs. The results revealed that the cytotoxicity of oxaliplatin and the level of ROS were decreased with the downregulation of Cx43 GJ function, but exacerbated with the upregulation of Cx43 GJ function. Moreover, ROS scavenging with N-acetyl-L-cysteine and apocynin decreased the cytotoxicity of oxaliplatin. We concluded that the loss of GJ composed of Cx43 contributed to the resistance of oxaliplatin in colon cancer cells, and the mechanism was associated with intracellular ROS alternation.

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

BACKGROUND

Postoperative 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).

METHODS

Sprague-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.

RESULTS

OALT 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.

CONCLUSIONS

SERPINB1 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.

Prevention of acute kidney injury and protection of renal function in the intensive care unit: update 2017 : Expert opinion of the Working Group on Prevention, AKI section, European Society of Intensive Care Medicine

BACKGROUND

Acute kidney injury (AKI) in the intensive care unit is associated with significant mortality and morbidity.

OBJECTIVES

To determine and update previous recommendations for the prevention of AKI, specifically the role of fluids, diuretics, inotropes, vasopressors/vasodilators, hormonal and nutritional interventions, sedatives, statins, remote ischaemic preconditioning and care bundles.

METHOD

A systematic search of the literature was performed for studies published between 1966 and March 2017 using these potential protective strategies in adult patients at risk of AKI. The following clinical conditions were considered: major surgery, critical illness, sepsis, shock, exposure to potentially nephrotoxic drugs and radiocontrast. Clinical endpoints included incidence or grade of AKI, the need for renal replacement therapy and mortality. Studies were graded according to the international GRADE system.

RESULTS

We formulated 12 recommendations, 13 suggestions and seven best practice statements. The few strong recommendations with high-level evidence are mostly against the intervention in question (starches, low-dose dopamine, statins in cardiac surgery). Strong recommendations with lower-level evidence include controlled fluid resuscitation with crystalloids, avoiding fluid overload, titration of norepinephrine to a target MAP of 65-70 mmHg (unless chronic hypertension) and not using diuretics or levosimendan for kidney protection solely.

CONCLUSION

The results of recent randomised controlled trials have allowed the formulation of new recommendations and/or increase the strength of previous recommendations. On the other hand, in many domains the available evidence remains insufficient, resulting from the limited quality of the clinical trials and the poor reporting of kidney outcomes.

Sufentanil attenuates oxaliplatin cytotoxicity via inhibiting connexin 43‑composed gap junction function

Comprehensive strategies for the treatment of colorectal cancer (CRC) have become increasingly important. One of the most important factors is pain relief. Therefore, patients with CRC are concurrently treated with analgesics and chemotherapeutic agents; however, the effects of analgesics on the therapeutic activity of chemotherapeutic agents remain largely unknown. The present study investigated the effects of three widely used analgesics in clinics: Fentanyl, remifentanil and sufentanil, on the cytotoxicity of oxaliplatin, a commonly used chemotherapeutic agent for CRC. Furthermore, the underlying mechanisms of those effects in association with connexin 43 (Cx43)‑composed gap junction (GJ) function were analyzed. The Lovo, Colo320, HCT116 and HT29 human CRC cell lines, with or without Cx43 expression, were used to examine the effects of the three analgesics on the cytotoxicity of oxaliplatin. The results demonstrated that in the cell lines expressing Cx43 (Lovo and Colo320), the cytotoxicity of oxaliplatin was attenuated and Cx43 GJ function was inhibited. Sufentanil, not fentanyl or remifentanil, inhibited Cx43 GJ function effectively, and reduced the cytotoxicity of oxaliplatin. In contrast, these effects were not observed in the other two colon cancer cell lines not expressing Cx43 (HCT116 and HT29). These results suggested that alternation of Cx43 GJ function may regulate the cytotoxicity of oxaliplatin in regard to CRC. Furthermore, sufentanil, not fentanyl or remifentanil, suppressed the cytotoxicity of oxaliplatin through inhibition of Cx43 GJ function. These results may be beneficial for the treatment of CRC and reduction of treatment resistance.

Gap junction composed of connexin43 modulates 5‑fluorouracil, oxaliplatin and irinotecan resistance on colorectal cancers

Chemotherapy is one of the most commonly used therapeutic strategies for metastatic colon cancer. However, the development of resistance to chemotherapeutic agents limits their application in clinical use. The underlying mechanisms of this resistance development require further elucidation. The current study investigated the effects of connexin43 (Cx43) gap junctions on 5‑fluorouracil (5‑FU), oxaliplatin and irinotecan in colon cancer cells. Three different methods were used to manipulate Cx43 gap junction function: i) Cell culture at different densities; ii) pretreatment with a Cx43 specific inhibitor or enhancer; and iii) Cx43 gene knock‑down. Results indicated that the cell toxicity of 5‑FU, oxaliplatin and irinotecan was cell density‑dependent, which was mediated by gap junctions. Downregulation of Cx43 gap junction functioning attenuated 5‑FU, oxaliplatin and irinotecan toxicity in colon cancer cells, which was increased in cells treated with a Cx43 gap junction function enhancer. Thus, the results of the present study suggest that resistance to 5‑FU, oxaliplatin and irinotecan in colon cancer cells was relative to Cx43 expression loss as cancer developed, which may indicate a novel basis for therapeutic strategy development to combat drug resistance in numerous cell types, in addition to colon cancer cells.

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

BACKGROUND

Postoperative 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.

METHODS

Male 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.

RESULTS

Compared 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.

CONCLUSION

Cx43 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.

Carnosic acid nanoparticles suppress liver ischemia/reperfusion injury by inhibition of ROS, Caspases and NF-κB signaling pathway in mice

Living donor liver transplantation (LDLT) requires ischemia/reperfusion (I/R), which can lead to early graft injury. However, the detailed molecular mechanism of I/R injury remains unclear. Carnosic acid, as a phenolic diterpene with function of anti-inflammation, anti-cancer, anti-bacterial, anti-diabetic, as well as neuroprotective properties, is produced by many species from Lamiaceae family. Nanoparticulate drug delivery systems have been known to better the bioavailability of drugs on intranasal administration compared with only drug solutions. Administration of carnosic acid nanoparticles was thought to be sufficient to lead to considerable inhibition of liver injury progression induced by ischemia/reperfusion. In our study, liver ischemia/reperfusion injury was established successfully with C57BL/6 animal model. 10 and 20mg/kg carnosic acid nanoparticles were injected to mice for five days prior to ischemia. After liver ischemia/reperfusion, the levels of serum AST, ALT and APL were increased, which was attenuated by pre-treatment with carnosic acid nanoparticles. In addition, carnosic acid nanoparticles inhibited ROS production via its related signals regulation. And carnosic acid nanoparticles also suppressed the ischemia/reperfusion-induced up-regulation in the pro-apoptotic protein and mRNA levels of Bax, Cyto-c, Apaf-1 and Caspase-9/3 while increased ischemia/reperfusion-induced decrease of anti-apoptotic factor of Bcl-2. Further, ischemia/reperfusion-induced inflammation was also inhibited for carnosic acid nanoparticles administration via inactivating NF-κB signaling pathway, leading to down-regulation of pro-inflammatory cytokines releasing. In conclusion, our study suggested that carnosic acid nanoparticles protected against liver ischemia/reperfusion injury via its role of anti-oxidative, anti-apoptotic and anti-inflammatory bioactivity.

Induction of heme oxygenase-1 by hemin protects lung against orthotopic autologous liver transplantation-induced acute lung injury in rats

BACKGROUND

Post-liver transplantation acute lung injury (ALI) severely affects patients' survival, whereas the mechanism is unclear and effective therapy is lacking. The authors postulated that reperfusion-induced increased oxidative stress plays a critical role in mediating post-liver transplantation ALI and that induction of heme oxgenase-1 (HO-1), an enzyme with anti-oxidative stress properties, can confer effective protection of lung against ALI.

METHODS

Male Sprague-Dawley rats underwent autologous orthotopic liver transplantation (OALT) in the absence or presence of treatments with the selective HO-1 inducer (Hemin) or HO-1 inhibitor (ZnPP). Lung tissues were collected at 8 h after OALT, pathological scores and lung water content were evaluated; survival rate of rats was analyzed; protein expression of HO-1 was determined by western blotting, and nuclear translocation of Nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor(NF)-κB p65 were detected by Immunofluorescence staining. The inflammatory cytokines and oxidative indexes of lung tissue were determined.

RESULTS

In lungs harvested at the early stage i.e. 8 h after OALT, Hemin treatment significantly increased superoxide dismutase activities, and reduced malondialdehyde, hydrogen peroxide, interleukin-6, myeloperoxidase, and tumor necrosis factor-α production,which were associated with increased HO-1 protein expression and lower pathological scores and increased survival rate of rats. The underline mechanisms might associate with activation of Nrf2 and inhibition of NF-κB p65 nuclear translocation. However, these changes were aggravated by ZnPP.

CONCLUSIONS

Hemin pretreatment, by enhancing HO-1 induction, increased lung antioxidant capacity and reduced inflammatory stress,protected the lung from OALT-induced ALI at early stage of reperfusion.

Intestinal injury following liver transplantation was mediated by TLR4/NF-κB activation-induced cell apoptosis

Intestinal motility and barriers are often impaired due to intestinal congestion during liver transplantation. Intestinal bacteria and enterogenous endotoxins enter into the blood stream or lymphatic system and translocate to other organs, which can result in postoperative multi-organ dysfunction (MODF) and systemic inflammatory reaction syndrome (SIRS) severely affecting patient survival. However, the mechanisms underlying liver transplantation-induced intestinal injury remain unclear and effective therapies are lacking. Thus, the present study investigated whether these effects were associated with endotoxin-mediated apoptosis. Rat autologous orthotopic liver transplantation (AOLT) models were established to observe dynamic intestinal injuries at different time-points following reperfusion. Changes in the levels of endotoxins and the primary receptor, toll-like receptor 4 (TLR4), as well as its downstream signaling molecule, nuclear factor-κB (NF-κB) were all determined. Finally, immunohistochemistry and terminal deoxynucleotidyl transferase dUTP nick end labeling assays were conducted to detect caspase-3 expression and intestinal cell apoptosis, respectively. AOLT resulted in significant pathological intestinal injury, with the most serious intestine damage apparent four or eight hours following reperfusion. Furthermore, the levels of endotoxins and inflammatory cytokines, such as tumor necrosis factor-α and interleukin-6, peaked during this time period and gradually decreased to the normal level. Notably, TLR4 and downstream NF-κB expression, as well as NF-κB-mediated caspase-3 activation and intestinal cell aapoptosis coincided with the intestinal pathological damage. Thus, the possible mechanism of post-liver transplantation intestinal injury was demonstrated to be associated with NF-κB activation-induced cell apoptosis.

Dexmedetomidine Pretreatment Attenuates Kidney Injury and Oxidative Stress during Orthotopic Autologous Liver Transplantation in Rats

This paper aims to explore whether pretreatment with dexmedetomidine (Dex) has antioxidative and renal protective effects during orthotopic autologous liver transplantation (OALT) and its impact on nuclear factor erythroid 2-related factor 2 (Nrf2) activation. Sprague-Dawley rats were randomized into groups that include sham-operated (group S), model (group M), low dose Dex (group D1), high dose Dex (group D2), atipamezole (a nonspecific α₂ receptor blocker) + high dose Dex (group B1), ARC239 (a specific α_2B/c receptor blocker) + high dose Dex (group B2), and BRL-44408 (a specific α_2A receptor blocker) + high dose Dex (group B3). Then histopathologic examination of the kidneys and measurement of renal function, the renal Nrf2 protein expression, and oxidants and antioxidants were performed 8 hours after OALT. We found that pretreatment with Dex activated Nrf2 in glomerular cells and upregulated antioxidants but reduced oxidants (all P < 0.01, group D2 versus group M). Atipamezole and BRL-44408, but not ARC239, reversed these protective effects. In conclusion, pretreatment with Dex activates Nrf2 through α_2A receptor, increases the antioxidant levels, and attenuates renal injury during OALT.

Dexmedetomidine Inhibits TLR4/NF-κB Activation and Reduces Acute Kidney Injury after Orthotopic Autologous Liver Transplantation in Rats

Patients who undergo orthotopic liver transplantation often sustain acute kidney injury(AKI). The toll-like receptor 4(TLR4)/Nuclear factor-кB(NF-кB) pathway plays a role in AKI. Dexmedetomidine(Dex) has been shown to attenuate AKI. The current study aimed to determine whether liver transplantation-induced AKI is associated with inflammatory response, and to assess the effects of dexmedetomidine pretreatment on kidneys in rats following orthotopic autologous liver transplantation(OALT). Seventy-seven adult male rats were randomized into 11 groups. Kidney tissue histopathology and levels of blood urea nitrogen(BUN) and serum creatinine(SCr) were evaluated. Levels of TLR4, NF-κB, tumor necrosis factor-α, and interleukin-1β levels were measured in kidney tissues. OALT resulted in significant kidney functional impairment and tissue injury. Pre-treatment with dexmedetomidine decreased BUN and SCr levels and reduced kidney pathological injury, TLR4 expression, translocation of NF-κB, and cytokine production. The effects of dexmedetomidine were reversed by pre-treatment with atipamezole and BRL44408, but not ARC239. These results were confirmed by using α_2A-adrenergic receptor siRNA which reversed the protective effect of dexmedetomidine on attenuating NRK-52E cells injury induced by hypoxia reoxygenation. In conclusion, Dexmedetomidine-pretreatment attenuates OALT-induced AKI in rats which may be contributable to its inhibition of TLR4/MyD88/NF-κB pathway activation. The renoprotective effects are related to α_2A-adrenergic receptor subtypes.

Connexin 43 expressed in endothelial cells modulates monocyte‑endothelial adhesion by regulating cell adhesion proteins

Adhesion between circulating monocytes and vascular endothelial cells is a key initiator of atherosclerosis. In our previous studies, it was demonstrated that the expression of connexin (Cx)43 in monocytes modulates cell adhesion, however, the effects of the expression of Cx43 in endothelial cells remains to be elucidated. Therefore, the present study investigated the role of the expression of Cx43 in endothelial cells in the process of cell adhesion. A total of four different methods with distinct mechanisms were used to change the function and expression of Cx43 channels in human umbilical vein endothelial cells: Cx43 channel inhibitor (oleamide), enhancer (retinoic acid), overexpression of Cx43 by transfection with pcDNA‑Cx43 and knock‑down of the expression of Cx43 by small interfering RNA against Cx43. The results indicated that the upregulation of the expression of Cx43 enhanced monocyte‑endothelial adhesion and this was markedly decreased by downregulation of Cx43. This mechanism was associated with Cx43‑induced expression of vascular cell adhesion molecule‑1 and intercellular cell adhesion molecule‑1. The effects of Cx43 in endothelial cells was independent of Cx37 or Cx40. These experiments suggested that local regulation of endothelial Cx43 expression within the vasculature regulates monocyte‑endothelial adhesion, a critical event in the development of atherosclerosis and other inflammatory pathologies, with baseline adhesion set by the expression of Cx43. This balance may be crucial in controlling leukocyte involvement in inflammatory cascades.

Downregulation of Lung Toll-Like Receptor 4 Could Effectively Attenuate Liver Transplantation-Induced Pulmonary Damage at the Early Stage of Reperfusion

Acute lung injury (ALI) is a severe complication of orthotopic liver transplantation (OLT) with unclear underline mechanism. Toll-like receptor 4 (TLR4) has been identified as a key receptor mediating inflammation. We hypothesized that TLR4-mediated pulmonary inflammation may contribute to development of ALI during OLT. Patients with or without ALI were observed for serum cytokines and expression of TLR4 on peripheral blood polymorphonuclear leukocytes (PMNs). Next, rats which underwent orthotopic autologous liver transplantation (OALT) were divided into sham and model groups. Pulmonary function and the level of TLR4 expression and cytokines were analyzed. Furthermore, the role of TLR4 in OALT-mediated ALI was assessed in rats treated with TLR4-siRNA before OALT. The PMNs TLR4 expression and the serum TNF-α and IL-β level were higher in patients with ALI than those with non-ALI. Interestingly, lung TLR4 expression was significantly increased after 8 hours of OALT with increased levels of TNF-α and IL-β, which lead to lung pathological damage and an increase of lung myeloperoxidase content. Moreover, knockdown of TLR4 reduced lung cytokines release and reversed the above pathologic changes after OALT and finally improved rats' survival rate. In conclusion, TLR4 overexpression, potentially by stimulating proinflammatory cytokine overproduction, contributes to the development of ALI after OLT.

Renal Outcomes in Critically Ill Patients Receiving Propofol or Midazolam

BACKGROUND AND OBJECTIVES

Propofol has been shown to provide protection against renal ischemia/reperfusion injury experimentally, but clinical evidence is limited to patients undergoing cardiac surgery. There are no data about its association with oliguria and AKI in critically ill patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We obtained data from the Multiparameter Intelligent Monitoring in Intensive Care II database (2001-2008). Patient selection criteria included adult patients in their first intensive care unit (ICU) admission, need for mechanical ventilation, and treatment with propofol or midazolam. Propensity score analysis (1:1) was used and renal-related outcomes (AKI, oliguria, cumulative fluid balance, and need for RRT) were evaluated during the first 7 days of ICU stay.

RESULTS

There were 1396 propofol/midazolam-matched patients. AKI in the first 7-day ICU time period was statistically lower in propofol-treated patients compared with midazolam-treated patients (55.0% versus 67.3%, P<0.001). Propofol was associated with lower AKI incidence using both urine output (45.0% versus 55.7%, P<0.001) and serum creatinine criteria (28.8% versus 37.2%, P=0.001). Patients receiving propofol had oliguria (<400 ml/d) less frequently (12.4% versus 19.6%, P=0.001) and had diuretics prescribed less often (8.5% versus 14.3%, P=0.001). In addition, during the first 7 days of ICU stay, patients receiving propofol less frequently achieved cumulative fluid balance >5% of body weight (50.1% versus 58.3%, P=0.01). The need for RRT in the first 7 days of ICU stay was also less frequent in propofol-treated patients (3.4% versus 5.9%, P=0.03). ICU mortality was lower in propofol-treated patients (14.6% versus 29.7%, P<0.001).

CONCLUSIONS

In this large, propensity-matched ICU population, patients treated with propofol had a lower risk of AKI, fluid-related complications, and need for RRT.

Hemin protects against hippocampal damage following orthotopic autologous liver transplantation in adult rats

AIMS

Induction of heme oxygenase-1 (HO-1) has been widely accepted to be neuro-protective. This study aimed to examine whether hemin (a HO-1 inducer) attenuates neuronal damage in the hippocampus induced by orthotopic autologous liver transplantation (OALT) in adult rats.

MAIN METHODS

Rats were randomly allocated into four groups (n=8 each): (i) Sham control group; (ii) OALT model group; (iii) Hemin+OALT group, with intra-peritoneal (i.p.) injection of hemin (5 mg/kg) 24 hours (h) before the OALT; and (iv) ZnPP (a HO-1 inhibitor)+OALT group, with i.p. injection of ZnPP (32 mg/kg) 24h before the OALT. Twenty four hours after the surgery, the hippocampal tissues were collected for electron microscopic examination and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) analysis. The levels of hippocampal HO-1 protein and serum S-100β, the concentrations of regional tumor necrosis factor-α (TNF-α) and interleukins (IL-6, IL-10), as well as the status of malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT) in the hippocampus were assessed.

KEY FINDINGS

Rats suffered severe neuronal damage in the hippocampus after OALT, mainly in apoptosis. Pre-treatment with hemin obviously alleviated the damage; up-regulated the HO-1 protein level; inhibited the release of TNF-α, IL-6 and MDA; and promoted the activities of SOD, CAT and IL-10; however, pre-treatment with ZnPP did not exhibit the opposite effect, except that a marked increase in serum S-100β level was detected.

SIGNIFICANCE

Hemin up-regulated the expression of HO-1 and attenuated hippocampal neuronal damage induced by OALT.

Elevation of HO-1 Expression Mitigates Intestinal Ischemia-Reperfusion Injury and Restores Tight Junction Function in a Rat Liver Transplantation Model

Aims. This study was aimed at investigating whether elevation of heme oxygenase-1 (HO-1) expression could lead to restoring intestinal tight junction (TJ) function in a rat liver transplantation model. Methods. Intestinal mucosa injury was induced by orthotopic autologous liver transplantation (OALT) on male Sprague-Dawley rats. Hemin (a potent HO-1 activator) and zinc-protoporphyrin (ZnPP, a HO-1 competitive inhibitor), were separately administered in selected groups before OALT. The serum and intestinal mucosa samples were collected at 8 hours after the operation for analysis. Results. Hemin pretreatment significantly reduced the inflammation and oxidative stress in the mucosal tissue after OALT by elevating HO-1 protein expression, while ZnPP pretreatment aggravated the OALT mucosa injury. Meanwhile, the restriction on the expression of tight junction proteins zonula occludens-1 and occludin was removed after hemin pretreatment. These molecular events led to significant improvement on intestinal barrier function, which was proved to be through increasing nuclear translocation of nuclear factor-E2-related factor 2 (Nrf2) and reducing nuclear translocation of nuclear factor kappa-B (NF-κB) in intestinal injured mucosa. Summary. Our study demonstrated that elevation of HO-1 expression reduced the OALT-induced intestinal mucosa injury and TJ dysfunction. The HO-1 protective function was likely mediated through its effects of anti-inflammation and antioxidative stress.