Gangjian Luo

Propofol activation of the Nrf2 pathway is associated with amelioration of acute lung injury in a rat liver transplantation model

Objective. This study aimed to investigate whether propofol pretreatment can protect against liver transplantation-induced acute lung injury (ALI) and to explore whether Nrf2 pathway is involved in the protections provided by propofol pretreatment. Method. Adult male Sprague-Dawley rats were divided into five groups based on the random number table. Lung pathology was observed by optical microscopy. Lung water content was assessed by wet/dry ratio, and PaO2 was detected by blood gas analysis. The contents of H2O2, MDA, and SOD activity were determined by ELISA method, and the expression of HO-1, NQO1, Keap1, and nuclear Nrf2 was assayed by western blotting. Results. Compared with saline-treated model group, both propofol and N-acetylcysteine pretreatment can reduce the acute lung injury caused by orthotopic autologous liver transplantation (OALT), decrease the lung injury scores, lung water content, and H2O2 and MDA levels, and improve the arterial PaO2 and SOD activity. Furthermore, propofol (but not N-acetylcysteine) pretreatment especially in high dose inhibited the expression of Keap1 and induced translocation of Nrf2 into the nucleus to further upregulate the expression of HO-1 and NQO1 downstream. Conclusion. Pretreatment with propofol is associated with attenuation of OALT-induced ALI, and the Nrf2 pathway is involved in the antioxidative processes.

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

Background:Postliver transplantation acute kidney injury (AKI) severely affects patient survival, whereas the mechanism is unclear and effective therapy is lacking. The authors postulated that reperfusion induced enhancement of connexin32 (Cx32) gap junction plays a critical role in mediating postliver transplantation AKI and that pretreatment/precondition 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 Cx32 inhibitor, 2-aminoethoxydiphenyl borate or propofol (50 mg/kg) (n = 8 per group). Also, kidney tubular epithelial (NRK-52E) cells were subjected to hypoxia–reoxygenation and the function of Cx32 was manipulated by three distinct mechanisms: cell culture in different density; pretreatment with Cx32 inhibitors or enhancer; Cx32 gene knock-down (n = 4 to 5). Results:AOLT resulted in significant increases of renal Cx32 protein expression and gap junction, which were coincident with increases in oxidative stress and impairment in renal function and tissue injury as compared to sham group. Similarly, hypoxia–reoxygenation resulted in significant cellular injury manifested as reduced cell growth and increased lactate dehydrogenase release, which was significantly attenuated by Cx32 gene knock-down but exacerbated by Cx32 enhancement. Propofol inhibited Cx32 function and attenuated post-AOLT AKI. In NRK-52E cells, propofol reduced posthypoxic reactive oxygen species production and attenuated cellular injury, and the cellular protective effects of propofol were reinforced by Cx32 inhibition but cancelled by Cx32 enhancement. Conclusion:Cx32 plays a critical role in AOLT-induced AKI and that inhibition of Cx32 function may represent a new and major mechanism whereby propofol reduces oxidative stress and subsequently attenuates post-AOLT AKI.

Mast cell stabilization alleviates acute lung injury after orthotopic autologous liver transplantation in rats by downregulating inflammation.

Background Acute lung injury (ALI) is one of the most severe complications after orthotopic liver transplantation. Amplified inflammatory response after transplantation contributes to the process of ALI, but the mechanism underlying inflammation activation is not completely understood. We have demonstrated that mast cell stabilization attenuated inflammation and ALI in a rodent intestine ischemia/reperfusion model. We hypothesized that upregulation of inflammation triggered by mast cell activation may be involve in ALI after liver transplantation. Methods Adult male Sprague–Dawley rats received orthotopic autologous liver transplantation (OALT) and were executed 4, 8, 16, and 24 h after OALT. The rats were pretreated with the mast cell stabilizers cromolyn sodium or ketotifen 15 min before OALT and executed 8 h after OALT. Lung tissues and arterial blood were collected to evaluate lung injury. β-hexosaminidase and mast cell tryptase levels were assessed to determine the activation of mast cells. Tumor necrosis factor α (TNF-α), interleukin (IL)-1β and IL-6 in serum and lung tissue were analyzed by enzyme-linked immunosorbent assay. Nuclear factor-kappa B (NF-κB) p65 translocation was assessed by Western blot. Results The rats that underwent OALT exhibited severe pulmonary damage with a high wet-to-dry ratio, low partial pressure of oxygen, and low precursor surfactant protein C levels, which corresponded to the significant elevation of pro-inflammatory cytokines, β-hexosaminidase, and tryptase levels in serum and lung tissues. The severity of ALI progressed and maximized 8 h after OALT. Mast cell stabilization significantly inhibited the activation of mast cells, downregulated pro-inflammatory cytokine levels and translocation of NF-κB, and attenuated OALT-induced ALI. Conclusions Mast cell activation amplified inflammation and played an important role in the process of post-OALT related ALI.

Propofol alleviates liver oxidative stress via activating Nrf2 pathway

BACKGROUND Nuclear factor-E2-related factor 2 (Nrf2)-mediated antioxidant response is the main protective system of graft-liver against ischemia-reperfusion injury after liver transplantation. Propofol is considered to confer protective effects on different organs; thus, we explored the possibility that whether propofol could attenuate graft-liver injury in a rat autologous orthotopic liver transplantation (AOLT) model and mechanisms were associated with activation of Nrf2 pathway. METHODS Sprague-Dawley rats were randomly divided into four groups: sham-operated group, saline-treated AOLT group, low-dose propofol intervention group, and high-dose propofol intervention group. Liver injury was determined, and concentration of hydroxyl free radical (•OH), superoxide anion (O2(•-)), and malondialdehyde in the liver tissue were detected. The expression of Keap1, Nrf2, HO-1, and NQO1 were explored by Western blotting, and also the change of Nrf2 and keap1 was assessed by immunofluorescence. RESULTS Compared with sham group, pathologic damage of graft-livers was in a time-dependent manner, accompanied with the increased level of oxidative stress in the AOLT group, and nuclear Nrf2 expression and its downstream antioxidant enzyme, HO-1 and NQO1, were also increased in this group. However, in propofol pretreatment groups especially in the high-dose group, the pathologic score was significantly decreased, accompanied with a lower level of •OH, O2(•-), and malondialdehyde than that of the AOLT group. The change of oxidative stress might be related to the Nrf2 pathway, evidenced as the elevation of protein expression level of NQO1, HO-1, and nuclear Nrf2. CONCLUSIONS Protective effects of propofol against liver transplantation-induced graft-liver injury may be related with Keap1-Nrf2 signal pathway activation.

Sevoflurane ameliorates intestinal ischemia-reperfusion-induced lung injury by inhibiting the synergistic action between mast cell activation and oxidative stress

Preconditioning with sevoflurane (SEV) can protect against ischemia-reperfusion injury in several organs, however, the benefits of SEV against acute lung injury (ALI), induced by intestinal ischemia-reperfusion (IIR), and the underlying mechanisms remain to be elucidated. The present study was designed to investigate the effects of SEV preconditioning on IIR-mediated ALI and the associated mechanisms in a rat model. Female Sprague-Dawley rats treated with 2.3% SEV or apocynin (AP), an inhibitor of NADPH oxidase, were subjected to 75 min superior mesenteric artery occlusion followed by 2 h reperfusion in the presence or absence of the mast cell degranulator compound 48/80 (CP). SEV and AP were observed to downregulate the protein expression levels of p47phox and gp91phox in the lungs of normal rats. IIR resulted in severe lung injury, characterized by significant increases in pathological injury scores, lung wet/dry weight ratio, protein expression levels of p47phox, gp91phox and ICAM-1, the presence of hydrogen peroxide, malondydehyde and interleukin-6, and the activity of myeloperoxidase. In addition, significant reductions were observed in the expression of prosurfactant protein C, accompanied by an increase in MC degranulation, demonstrated by significant elevations in the number of mast cells, expression levels of tryptase and the concentration of β-hexosaminidase. These changes were further augmented in the presence of CP. In addition, SEV and AP preconditioning significantly alleviated the above alterations induced by IIR alone or in combination with CP. These findings suggested that SEV and AP attenuated IIR-induced ALI by inhibiting NADPH oxidase and the synergistic action between oxidative stress and mast cell activation.

Upregulation of TLR2/4 Expression in Mononuclear Cells in Postoperative Systemic Inflammatory Response Syndrome after Liver Transplantation

Background. To explore the relationship between Toll-like rpheral blood mononuclear cells (PBMC) and systemic inflammatory response syndrome (SIRS) in postoperative patients of liver transplantation (LT). Methods. Blood samples of 27 patients receiving LT were collected at T1 (after induction of anaesthesia), T2 (25 minutes after the beginning of anhepatic phase), T3 (3 hours after graft reperfusion), and T4 (24 hours after graft reperfusion). The expression of TLR2/4 on PBMC and serum concentration of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-8 were measured. The patients were divided into SIRS group (n = 12) and non-SIRS group (n = 15) for analysis. Results. Blood loss and transfusion were higher in the SIRS group than in the non-SIRS group. Both the preanhepatic and anhepatic phase were significantly longer in the SIRS group. The TLR2/4 expression on PBMC as well as serum TNF-α, IL-1β, and IL-8 were significantly higher at T3 and T4 than that at T1 and T2 in the SIRS patients. The expression of TLR4 on PBMC is positively correlated to serum TNF-α, IL-8. Expression of TLR2/4 on PBMC and serum concentrations of TNF-α, IL-1β, did not differ among the 4-time points in non-SIRS patients. Conclusions. Upregulation of TLR2/4 expression on PBMC may contribute to the development of postoperative SIRS during perioperative period of LT.

Intestinal NF-E2-related factor-2 expression and antioxidant activity changes in rats undergoing orthotopic liver autotransplantation.

Liver transplantation is known to trigger intestinal injuries. Oxidative damage that is induced by reactive oxygen species (ROS) plays a crucial role in ischemia-reperfusion injuries. NF-E2-related factor-2 (Nrf2) and its modulated antioxidant enzymes form the critical endogenous antioxidant system to scavenge ROS. The present study investigated the dynamic changes of intestinal ROS levels, Nrf2 expression and antioxidant enzyme activity following orthotopic liver autotransplantation (OLAT). Sprague-Dawley rats were randomly divided into five groups consisting of one sham group and four groups with rats that underwent OLAT and were evaluated following 4, 8, 16 and 24 h, respectively. The intestinal specimens were collected for histopathological examination and the detection of hydrogen peroxide (H2O2), hydroxyl radical (•OH), malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) levels and the expression of Nrf2. The present study demonstrated that OLAT resulted in severe intestinal injury, which manifested as a significant change in the intestine pathological scores as early as 4 h and peaking at 8 h post-treatment. Oxidative stress was also revealed by the increase of the H2O2, •OH and MDA levels. Significant decreases were observed in the activity of SOD and CAT and a dramatic decrease occurred in the levels of GSH at 4 and 8 h post-treatment. All the parameters were restored gradually at 16 and 24 h post-treatment. The expression of Nrf2 in the intestinal tissues increased significantly at 4, 16 and 24 h following OLAT. The present study shows that an imbalance between oxidants and antioxidants contributes to intestinal oxidative injury, and that the upregulation of Nrf2 is not sufficient to withstand intestinal oxidative injury following OLAT.

The Mechanism of Sevoflurane Preconditioning-Induced Protections against Small Intestinal Ischemia Reperfusion Injury Is Independent of Mast Cell in Rats

The study aimed to investigate whether sevoflurane preconditioning can protect against small intestinal ischemia reperfusion (IIR) injury and to explore whether mast cell (MC) is involved in the protections provided by sevoflurane preconditioning. Sprague-Dawley rats exposed to sevoflurane or treated with MC stabilizer cromolyn sodium (CS) were subjected to 75-minute superior mesenteric artery occlusion followed by 2-hour reperfusion in the presence or absence of MC degranulator compound 48/80 (CP). Small intestinal ischemia reperfusion resulted in severe intestinal injury as demonstrated by significant elevations in intestinal injury scores and p47phox and gp91phox, ICAM-1 protein expressions and malondialdehyde and IL-6 contents, and MPO activities as well as significant reductions in SOD activities, accompanied with concomitant increases in mast cell degranulation evidenced by significant increases in MC counts, tryptase expression, and β-hexosaminidase concentrations, and those alterations were further upregulated in the presence of CP. Sevoflurane preconditioning dramatically attenuated the previous IIR-induced alterations except MC counts, tryptase, and β-hexosaminidase which were significantly reduced by CS treatment. Furthermore, CP exacerbated IIR injury was abrogated by CS but not by sevoflurane preconditioning. The data collectively indicate that sevoflurane preconditioning confers protections against IIR injury, and MC is not involved in the protective process.

Using inflammatory and oxidative biomarkers in urine to predict early acute kidney injury in patients undergoing liver transplantation

Abstract Objective: We examined the value of inflammatory and oxidative biomarkers in predicting acute kidney injury (AKI) following orthotopic liver transplantation (OLT). Methods: Urinary excretion of tumour necrosis factor-α (TNF-α), interleukin-8 (IL-8), interleukin-10 (IL-10), superoxide dismutase (SOD), malondialdehyde (MDA), 6-keto prostaglandin F1α (6-keto-PGF1α), hydrogen peroxide (H2O2), and 8-keto prostaglandin F2α (8-iso-PGF2α), serum creatinine (SCr), blood urea nitrogen (BUN), urinary N-acetyl-beta-D-glucosaminidase (NAG), β2-microglobulin (β2-MG) and γ-glutamyl-transferase (γ-GT), were measured before surgery (baseline), at 2 h after graft reperfusion and 24 h after OLT in 28 liver transplantation patients. Results: The levels of TNF-α, IL-8, IL-10, SOD, MDA, 6-keto-PGF1α, H2O2 and 8-iso-PGF2α in urine were all significantly higher in patients who had AKI than in those who did not at 2 h after graft reperfusion and 24 h after OLT (p < 0.01).

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.