Early Ischemia-reperfusion Injury Research Articles

Reactive Oxygen Species Responsive Multifunctional Fusion Extracellular Nanovesicles: Prospective Treatments for Acute Heart Transplant Rejection.

Heart transplantation offers life-saving treatment for patients with end-stage heart failure; however, ischemia-reperfusion injury (IRI) and subsequent immune responses remain significant challenges. Current therapies primarily target adaptive immunity, with limited options available for addressing IRI and innate immune activation. Although plant-derived vesicle-like nanoparticles show promise in managing diseases, their application in organ transplantation complications is unexplored. Here, this work develops a novel reactive oxygen species (ROS)-responsive multifunctional fusion extracellular nanovesicles carrying rapamycin (FNVs@RAPA) to address early IRI and Ly6C+Ly6G- inflammatory macrophage-mediated rejection in heart transplantation. The FNVs comprise Exocarpium Citri grandis-derived extracellular nanovesicles with anti-inflammatory and antioxidant properties, and mesenchymal stem cell membrane-derived nanovesicles expressing calreticulin with macrophage-targeting ability. A novel ROS-responsive bio-orthogonal chemistry approach facilitates the active targeting delivery of FNVs@RAPA to the heart graft site, effectively alleviating IRI and promoting the polarization of Ly6C+Ly6G- inflammatory macrophages toward an anti-inflammatory phenotype. Hence, FNVs@RAPA represents a promising therapeutic approach for mitigating early transplantation complications and immune rejection. The fusion-targeted delivery strategy offers superior heart graft site enrichment and macrophage-specific targeting, promising improved transplant outcomes.

Genome-wide DNA methylation and transcriptomic analysis of liver tissues subjected to early ischemia/reperfusion injury upon human liver transplantation

Introduction and ObjectivesEpigenetic changes represent a mechanism connecting external stresses with long-term modifications of gene expression programs. In solid organ transplantation, ischemia-reperfusion injury (IRI) appears to induce epigenomic changes in the graft, although the currently available data are extremely limited. The present study aimed to characterize variations in DNA methylation and their effects on the transcriptome in liver transplantation from brain-dead donors. Patients and Methods12 liver grafts were evaluated through serial biopsies at different timings in the procurement-transplantation process: T0 (warm procurement, in donor), T1 (bench surgery), and T2 (after reperfusion, in recipient). DNA methylation (DNAm) and transcriptome profiles of biopsies were analyzed using microarrays and RNAseq. ResultsSignificant variations in DNAm were identified, particularly between T2 and T0. Functional enrichment of the best 1000 ranked differentially methylated promoters demonstrated that 387 hypermethylated and 613 hypomethylated promoters were involved in spliceosomal assembly and response to biotic stimuli, and inflammatory immune responses, respectively. At the transcriptome level, T2 vs. T0 showed an upregulation of 337 and downregulation of 61 genes, collectively involved in TNF-α, NFKB, and interleukin signaling. Cell enrichment analysis individuates macrophages, monocytes, and neutrophils as the most significant tissue-cell type in the response. ConclusionsIn the process of liver graft procurement-transplantation, IRI induces significant epigenetic changes that primarily act on the signaling pathways of inflammatory responses dependent on TNF-α, NFKB, and interleukins. Our DNAm datasets are the early IRI methylome literature and will serve as a launch point for studying the impact of epigenetic modification in IRI.

Can Hypothermic Oxygenated Perfusion Mitigate Ischemia-Reperfusion Injury in Ex-Situ Split Grafts? – A Comparative Study with Living Donation in Pediatric Liver Transplantation

Abstract Background The gold standard in pediatric split liver transplantation (SLT) is living donation (LD) providing high-quality grafts with short static cold storage (SCS). Aims This study investigates the protective effect of hypothermic oxygenated perfusion (HOPE) on ex-situ partial grafts from deceased donors in comparison to standard ex-situ Static-Split and LD SLT. Methods We included all consecutive HOPE-Split, Static-Split and LD SLT performed from 2018-2022 at a single center. The primary endpoint was early ischemia-reperfusion injury (IRI) based on reperfusion biopsy (graded from none/0 to severe/4), the occurrence of post reperfusion syndrome (PRS, drop≥30% of systolic arterial pressure) and post-LT transaminase release. Results A total of 46 SLT (14 HOPE-Split, 17 Static-Split, and 15 LD) were included. With a median perfusion duration of 100min, HOPE-Split had a significant decrease of SCS compared to Static-Split (473 min vs 538 min; p=0.02) with similar total preservation time (p=0.13). This translated into lower rates of mild to severe IRI (grade≥2; p=0.03) and significantly reduced neutrophilic infiltrate than Static-Split (p=0.04; Fig.1). The PRS was also reduced in HOPE-Split (0% vs 35%, p=0.02) with less transaminase release. Despite prolonged SCS (473 vs 117min, p<0.001), HOPE-Split was comparable to LD regarding grade≥2 IRI (64 vs 40%; p=0.17) and PRS (0 vs 6.7% p=0.34), with however higher transaminase release (571 vs 244 UI/L/100g; p=0.004). Overall, 3-months surgical complications, graft and recipient survival did not differ among groups. Conclusions HOPE allowed improved preservation of ex-situ split grafts compared to static cold storage, resulting in similar early IRI profiles then LD grafts. Preservation with HOPE may offer a promising strategy to improve outcomes and expand selection criteria in split LT for pediatric recipients.

Heparin Conjugate Pretreatment of Kidneys From Deceased Donors Before Transplantation: Results From the First-in-human Randomized Phase I Trial.

CHC or placebo was added to the preservation solution during HMP of donated kidneys from deceased donors for at least 3 h before transplantation into adult patients. The primary safety endpoint was the number and severity of adverse events (AEs) and serious AEs (SAEs) during the first 30 d after transplantation. In the first 30 d, 66 AEs were reported in 8 patients who received CHC-pretreated kidneys with 39 AEs in 8 patients who received placebo-pretreated kidneys (P = 0.1 in post hoc analysis). The most common AEs were hypertension (CHC, n = 5; placebo, n = 2) and anemia (CHC, n = 5; placebo, n = 2). Most AEs were assessed as mild (58%) or moderate (39%) and not related to treatment (95%). There were 2 SAEs reported in each group. One SAE, considered possibly related to CHC treatment, was a case of severe postprocedural hemorrhage that required reoperation. No patients needed dialysis. There were no observed rejections and no patient deaths. Pretreatment of kidneys with CHC before transplantation was considered safe and tolerable. Efficacy studies are now planned to investigate if CHC can reduce early ischemia-reperfusion injury in humans.

New insights into ischemia-reperfusion injury signaling pathways in organ transplantation.

Ischemia-reperfusion injury (IRI) leading to allograft rejection in solid organ transplant recipients is a devastating event that compromises graft and patient survival. As our clinical knowledge regarding its definition and presentation has significantly improved over the last years, adequate biomarkers translating to important therapeutic intervention remains a challenge. This review will summarize recent findings in this area. In the past 18 months, our understanding of organ transplantation IRI has improved. IRI involves a positive amplification feedback loop encompassing damaged cells at the graft site, the activity of redox-sensitive damage-associated molecular patterns, and local sequestration of recipient-derived monocytes, lymphocytes and polymorphonuclear leukocytes, like neutrophils, to sustain the immunological cascade and to enhance the destruction of the foreign tissue. Recent studies have identified critical components leading to IRI, including the oxidation state of high mobility group box 1, a classic danger signal, its role in the Toll-like receptor 4-interleukin (IL)-23-IL-17A signaling axis, and the role of neutrophils and CD321, a marker for transmigration of circulating leukocytes into the inflamed tissue. In addition, recent findings imply that the protective functions mediated by autophagy activation counterbalance the detrimental nucleotide-binding domain-like receptor family, pyrin domain containing 3 inflammasome pathway. Finally, clinical studies reveal the posttransplant variables associated with early allograft dysfunction and IRI. The future challenge will be understanding how crosstalk at the molecular and cellular levels integrate prospectively to predict which peri-transplant signals are essential for long-term clinical outcomes.

Lymphocytic Airway Inflammation in Lung Allografts.

Lung transplant remains a key therapeutic option for patients with end stage lung disease but short- and long-term survival lag other solid organ transplants. Early ischemia-reperfusion injury in the form of primary graft dysfunction (PGD) and acute cellular rejection are risk factors for chronic lung allograft dysfunction (CLAD), a syndrome of airway and parenchymal fibrosis that is the major barrier to long term survival. An increasing body of research suggests lymphocytic airway inflammation plays a significant role in these important clinical syndromes. Cytotoxic T cells are observed in airway rejection, and transcriptional analysis of airways reveal common cytotoxic gene patterns across solid organ transplant rejection. Natural killer (NK) cells have also been implicated in the early allograft damage response to PGD, acute rejection, cytomegalovirus, and CLAD. This review will examine the roles of lymphocytic airway inflammation across the lifespan of the allograft, including: 1) The contribution of innate lymphocytes to PGD and the impact of PGD on the adaptive immune response. 2) Acute cellular rejection pathologies and the limitations in identifying airway inflammation by transbronchial biopsy. 3) Potentiators of airway inflammation and heterologous immunity, such as respiratory infections, aspiration, and the airway microbiome. 4) Airway contributions to CLAD pathogenesis, including epithelial to mesenchymal transition (EMT), club cell loss, and the evolution from constrictive bronchiolitis to parenchymal fibrosis. 5) Protective mechanisms of fibrosis involving regulatory T cells. In summary, this review will examine our current understanding of the complex interplay between the transplanted airway epithelium, lymphocytic airway infiltration, and rejection pathologies.

Phosphorylated nuclear factor erythroid 2-related factor 2 promotes the secretion of C-C motif chemokine ligand 2 and the recruitment of M2 macrophages.

BackgroundNuclear factor erythroid 2-related factor 2 (Nrf2) has been shown to ameliorate early ischemia-reperfusion (I/R) injury after activation by tertiary butylhydroquinone (TBHQ). However, despite macrophage-associated inflammation being a distinguishing feature of I/R injury, the precise roles and mechanisms of Nrf2 in macrophage-associated inflammation are still poorly understood.MethodsI/R and hypoxia/reperfusion (H/R) models were constructed in vivo using rats and in vitro using the H9C2 rat cardiomyoblast cell line, respectively. The effects of TBHQ on myocardial damage under oxidative stress were assessed using apoptosis and cell cycle assays, as well as echocardiography. The Jaspar database was used to identify the C-C motif chemokine ligand 2 (Ccl2) gene promoter as a possible binding site for Nrf2. This interaction was validated by chromatin immunoprecipitation (ChIP) assays, enzyme-linked immunosorbent assay (ELISA), immunofluorescence staining, and western blot analysis. Transwell migration assays were used to examine the migration ability of the recruited macrophages.ResultsThe Nrf2 activator, TBHQ, induced phosphorylation of Nrf2 and promoted the secretion of Ccl2 by myocardial microvascular endothelial cells. The secreted Ccl2 induced the chemotaxis of M2 macrophages into the injury site and triggered the secretion of anti-inflammatory factors including interleukin (IL)-10 and tumor growth factor (TGF)-β1 by M2 macrophages, thereby reducing early myocardial ischemia reperfusion injury (MI/R).ConclusionsActivation of Nrf2 alleviated oxidative stress during myocardial ischemia and reperfusion by inducing the secretion of anti-inflammatory factors.

Photoacoustic imaging in evaluating early intestinal ischemia injury and reperfusion injury in rat models.

It remains a challenge to distinguish whether the damaged intestine is viable in treating acute mesenteric ischemia. In this study, photoacoustic imaging (PAI) was used to observe intestinal tissue viability after ischemia and reperfusion injury in rats. An in vivo study was conducted using forty male SD rats, which were randomly divided into a sham-operated (SO) group, a 1 h ischemia group, a 2 h ischemia group, and an ischemia-reperfusion (I/R) group with 10 rats in each group. In the ischemia group, the superior mesenteric artery (SMA) was isolated and clamped for 1 and 2 h, respectively, and in the I/R group, after ischemia for 1 h, the clamp was removed and reperfused for 1 h. The same time interval was used in the SO group. Immediately after establishing the animal model, a PAI examination was performed, and the small intestine was collected for histopathology. The levels of PAI parameters Hb, HbR, MAP 760, and MAP 840 were increased to different degrees in the ischemia groups, especially in the 2 h ischemia group, compared with the SO group (P<0.05), and with prolongation of the ischemia time, the injury was aggravated. All PAI signal levels except HbO in the I/R group were higher than those in the control group, and the increased range differed, especially in Hb and MAP 840. Using western blot, compared with the SO group, the BAX increased significantly in the 2 h ischemia group (P<0.05), and Caspase-3 in the experimental group was significantly higher than in the SO group (P<0.05). The level of HIF-1α increased in the 2 h ischemia group and I/R group (P<0.05), and TUNEL staining showed that the number of positive apoptotic nuclei in the 2 h ischemia group was significantly higher than in the SO group (P<0.05). Hematoxylin-eosin (HE) staining showed that ischemia for 2 hours was the most serious, with obvious mucosal damage, extensive epithelial injury, and bleeding. PAI can be used as an effective tool to detect acute intestinal ischemia injury and quantitatively evaluate tissue viability.

Value of T2 Mapping in the Dynamic Evaluation of Renal Ischemia-Reperfusion Injury

To explore the value of T2 mapping in the dynamic quantitative evaluation of renal ischemia- reperfusion injury (IRI). Forty-eight healthy New Zealand rabbits were randomly divided into IRI group (n = 40) and control group (n = 8). Rabbits in the IRI group underwent left renal artery clamping for 60 minutes. Rabbits underwent MRI examinations (T2WI and T2 mapping) before and 1, 12, 24, and 48 hours after IRI. The inter-observer and intra-observer reproducibility of the T2 values were assessed using the intraclass correlation coefficient (ICC) with 95% confidence interval (CI). Correlations between the T2 value of the renal outer medulla and injury scores were assessed by Spearman correlation analysis. The repeated measures analysis of variance was used to compare the differences in T2 values of the IRI and control group across the different time points. Both of the intra-observer (ICC = 0.97, 95% CI 0.95-0.99) and inter-observer reproducibility (ICC = 0.92, 95% CI 0.86-0.96) were excellent for T2 values. The T2 value of the renal outer medulla was moderately positive correlated with tubular epithelial edema (ρ = 0.686, p < 0.001). In IRI group, T2 values of the renal outer medulla were increase at 1 h after IRI (p = 0.001) and were decrease from 1 h to 12 h (p = 0.002). At 1 h after IRI, the T2 values of the renal outer medulla for the IRI group were higher than those for the control group (p < 0.001). T2 mapping can reflect the dynamic changes of renal parenchyma in an animal model of IRI and be used to assess the early renal IRI.

Effect of volatile anesthetics on early and delayed outcomes in pancreas transplantation.

Ischemia-reperfusion injury (IRI) is a common cause of allograft dysfunction and patient morbidity in solid organ transplantation. This study compares the effect of different inhaled anesthetics on early IRI and clinical outcomes in pancreas allograft recipients. Data were extracted retrospectively for pancreas transplants at a single center over a 15-year period. Early postoperative pancreatic amylase and lipase levels were used as a marker for graft injury. Clinical outcomes measured included length of hospital stay, readmission, and graft survival. There were 625 pancreas transplants included in the analysis with 3 primary inhaled anesthetics: sevoflurane (53%), desflurane (35%), and isoflurane (12%). In the first 30days post-transplant, peak amylase was lowest for sevoflurane (147) followed by desflurane (159) and isoflurane (229) (p=.03). Peak lipase levels followed the same trend (peak values 118, 131, and 135, respectively; p=.02). Early graft loss, length of hospital stay, and readmission within 3months were similar among all three anesthetic groups. There was no difference in 10-year graft survival by Cox regression. Sevoflurane and desflurane are associated with lower peak amylase and lipase levels postoperatively in pancreas transplantation. Short- and long-term clinical outcomes were equivalent for the three agents.

Inhibition of BRD4 Reduces Neutrophil Activation and Adhesion to the Vascular Endothelium Following Ischemia Reperfusion Injury.

Renal ischemia reperfusion injury (IRI) is associated with inflammation, including neutrophil infiltration that exacerbates the initial ischemic insult. The molecular pathways involved are poorly characterized and there is currently no treatment. We performed an in silico analysis demonstrating changes in NFκB-mediated gene expression in early renal IRI. We then evaluated NFκB-blockade with a BRD4 inhibitor on neutrophil adhesion to endothelial cells in vitro, and tested BRD4 inhibition in an in vivo IRI model. BRD4 inhibition attenuated neutrophil adhesion to activated endothelial cells. In vivo, IRI led to increased expression of cytokines and adhesion molecules at 6 h post-IRI with sustained up-regulated expression to 48 h post-IRI. These effects were attenuated, in part, with BRD4 inhibition. Absolute neutrophil counts increased significantly in the bone marrow, blood, and kidney 24 h post-IRI. Activated neutrophils increased in the blood and kidney at 6 h post-IRI and remained elevated in the kidney until 48 h post-IRI. BRD4 inhibition reduced both total and activated neutrophil counts in the kidney. IRI-induced tubular injury correlated with neutrophil accumulation and was reduced by BRD4 inhibition. In summary, BRD4 inhibition has important systemic and renal effects on neutrophils, and these effects are associated with reduced renal injury.

Evaluation of renal ischemia-reperfusion injury by magnetic resonance imaging texture analysis: An experimental study.

To explore the value of MRI texture analysis in evaluating the presence and severity of early renal ischemia-reperfusion injury (IRI). Healthy New Zealand rabbits were used (IRI group, N=54; control group, N=8). Rabbits in the IRI group underwent left renal artery clamping for 60minutes. Magnetic resonance imaging was performed before and at 1, 12, 24, and 48hours after IRI. The relationship between MRI texture features and histopathology parameters was assessed using Pearson's correlation coefficients. The diagnostic performance of texture features in kidney differentiation at different time points was assessed by receiver operating characteristic curve analysis. T2 WI_S(3,-3)Inverse_Difference_Moment had the strongest correlation with brush border destruction, tubular epithelial edema, necrosis, and cast (r=0.56, -0.58, 0.62, and 0.69, respectively; all P<.001). BOLD_S(4,-4)Correlation had the strongest correlation with interstitial inflammatory cell infiltration (r=0.63, P<.001). SWI_S(4,4)Difference_Entropy had the strongest correlation with microvessel density (r=0.61, P<.001). The areas under the curve for T2 WI_S(3,-3)Inverse_Difference_Moment, SWI_S(4,4)Difference_Entropy, and BOLD_S(4,-4)Correlation in kidney differentiation before IRI and that at 1 and 12hours after reperfusion were 0.76, 0.72, and 0.70, respectively; the values before IRI and at 24 and 48hours after reperfusion were 0.84, 0.81, and 0.69, respectively. The area under the curve for T2 WI_S(3,-3)Inverse_Difference_Moment in kidney differentiation at 1 and 12hours after reperfusion and that at 24 and 48hours after reperfusion was 0.66. Magnetic resonance imaging texture analysis can be used for evaluating the presence and severity of early renal IRI.

The Atypical Chemokine Receptor 2 Limits Progressive Fibrosis after Acute Ischemic Kidney Injury

Following renal ischemia-reperfusion injury (IRI), resolution of inflammation allows tubular regeneration, whereas ongoing inflammatory injury mediated by infiltrating leukocytes leads to nephron loss and renal fibrosis, typical hallmarks of chronic kidney disease. Atypical chemokine receptor 2 (ACKR2) is a chemokine decoy receptor that binds and scavenges inflammatory CC chemokines and reduces local leukocyte accumulation. We hypothesized that ACKR2 limits leukocyte infiltration, inflammation, and fibrotic tissue remodeling after renal IRI, thus preventing progression to chronic kidney disease. Compared with wild type, Ackr2 deficiency increases CC chemokine ligand 2 levels in tumor necrosis factor-stimulated tubulointerstitial tissue invitro. In Ackr2-deficient mice with early IRI 1 or 5 days after transient renal pedicle clamping, tubular injury was similar to wild type, although accumulation of mononuclear phagocytes increased in postischemic Ackr2-/- kidneys. Regarding long-term outcomes, Ackr2-/- kidneys displayed more tubular injury 5 weeks after IRI, which was associated with persistently increased renal infiltrates of mononuclear phagocytes, T cells, Ly6Chigh inflammatory macrophages, and inflammation. Moreover, Ackr2 deficiency caused substantially aggravated renal fibrosis in Ackr2-/- kidneys 5 weeks after IRI, shown by increased expression of matrix molecules, renal accumulation of α-smooth muscle actin-positive myofibroblasts, and bone marrow-derived fibrocytes. ACKR2 is important in limiting persistent inflammation, tubular loss, and renal fibrosis after ischemic acute kidney injury and, thus, can prevent progression to chronic renal disease.

Research progress on preventions of ischemia-reperfusion injury during kidney transplant

During kidney transplant, the non-specific inflammatory response induced by ischemia-reperfusion injury (IRI) will lead to decreased survival ability of transplanted kidney. However, the effect of IRI on long-term survival rate of allograft is not sure. Here we illuminated the relationship between early IRI and decreased long-term survival ability of allograft by retrospectively analyzing the clinical evidences and laboratory investigations. Previous studies showed that early IRI resulted in the graft loss through reduction of renal functional mass, vascular injury, chronic hypoxia and subsequent fibrosis. IRI was also one of the main factors to induce dysfunction of transplanted kidney and acute rejection reaction, and to decrease the allograft survival. Therefore, it's better to substitute traditional methods with novel measures during kidney transplant which may relieve the renal IRI much better.

Targeting Innate Immune Cells and Regulated Cell Death in Early Hepatic Ischemia Reperfusion Injury

Targeting Innate Immune Cells and Regulated Cell Death in Early Hepatic Ischemia Reperfusion Injury

Porcine Isolated Liver Perfusion for the Study of Ischemia Reperfusion Injury: A Systematic Review.

Understanding ischemia reperfusion injury (IRI) is essential to further improve outcomes after liver transplantation (LT). Porcine isolated liver perfusion (ILP) is increasingly used to reproduce LT-associated IRI in a strictly controlled environment. However, whether ILP is a reliable substitute of LT was never validated. We systematically reviewed the current experimental setups for ILP and parameters of interest reflecting IRI. Isolated liver perfusion was never compared with transplantation in animals. Considerable variability exists between setups, and comparative data are unavailable. Experience so far suggests that centrifugal pump(s) with continuous flow are preferred to reduce the risk of embolism. Hepatic outflow can be established by cannulation of the inferior vena cava or freely drained in an open bath. Whole blood at approximately 38°C, hematocrit of 20% or greater, and the presence of leukocytes to trigger inflammation is considered the optimal perfusate. A number of parameters related to the 4 liver compartments (hepatocyte, cholangiocyte, endothelium, immune cells) are available; however, their significance and relation to clinical outcomes is not well described. Porcine ILP provides a reproducible model to study early IRI events. As all models, it has its limitations. A standardization of the setup would allow comparison of data and progress in the field.

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

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

GSK-3β as a target for protection against transient cerebral ischemia.

Stroke remains the leading cause of death and disability worldwide. This fact highlights the need to search for potential drug targets that can reduce stroke-related brain damage. We showed recently that a glycogen synthase kinase-3β (GSK-3β) inhibitor attenuates tissue plasminogen activator-induced hemorrhagic transformation after permanent focal cerebral ischemia. Here, we examined whether GSK-3β inhibition mitigates early ischemia-reperfusion stroke injury and investigated its potential mechanism of action. We used the rat middle cerebral artery occlusion (MCAO) model to mimic transient cerebral ischemia. At 3.5 h after MCAO, cerebral blood flow was restored, and rats were administered DMSO (vehicle, 1% in saline) or GSK-3β inhibitor TWS119 (30 mg/kg) by intraperitoneal injection. Animals were sacrificed 24 h after MCAO. TWS119 treatment reduced neurologic deficits, brain edema, infarct volume, and blood-brain barrier permeability compared with those in the vehicle group. TWS119 treatment also increased the protein expression of β-catenin and zonula occludens-1 but decreased β-catenin phosphorylation while suppressing the expression of GSK-3β. These results indicate that GSK-3β inhibition protects the blood-brain barrier and attenuates early ischemia-reperfusion stroke injury. This protection may be related to early activation of the Wnt/β-catenin signaling pathway.

Donor Intervention Research.

Donor Intervention Research.

Recipient Hyperbilirubinemia May Reduce Ischemia-Reperfusion Injury but Fails to Improve Outcome in Clinical Liver Transplantation.

Background. Exogenous bilirubin may reduce experimental ischemia-reperfusion injury (IRI) due to its antioxidant properties. We studied if early graft exposure to high bilirubin levels in the recipient affects the early IRI and outcomes after liver transplantation (LTx). Methods. In 427 LTx patients, the AUROC curve based on bilirubin and AST at day 1 identified a cutoff of 2.04 mg/dL for the recipient pretransplant bilirubin. Recipients were grouped as having low (group L, n = 152) or high (group H, n = 275) bilirubin. Both groups had similar donor-related variables (age, preservation time, donor BMI > 28, and donor risk index (DRI)). Results. Alanine (ALT) and aspartate (AST) aminotransferase levels were higher in group L at day 1; ALT levels remained higher at day 2 in group L. LTx from high risk donors (DRI > 2) revealed a trend towards lower transaminases during the first two days after transplantation in group H. One month and 1-year patient survival were similar in groups L and H. High preoperative bilirubin did not affect the risk for early graft dysfunction (EGD), death, or graft loss during the first year after transplantation nor the incidence of acute rejection. LTx using donors with DRI > 2 resulted in similar rates of EGD in both groups. Conclusion. Increased bilirubin appears to reduce the early IRI after LTx yet this improvement was insufficient to improve the clinical outcome.