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Glutathione peroxidase 1 deficiency attenuates concanavalin A-induced hepatic injury by modulation of T-cell activation.

ABSTRACT: Concanavalin A (Con A)-induced hepatitis model is well-established experimental T cell-mediated liver disease. Reactive oxygen species (ROS) is associated with T-cell activation and proliferation, but continued ROS exposure induces T-cell hyporesponsiveness. Because glutathione peroxidase 1 (Gpx1) is an antioxidant enzyme and is involved in T-cell development, we investigated the role of Gpx1 during Con A-induced liver injury in Gpx1 knockout (KO) mice. Male wild-type (WT) mice and Gpx1 KO mice were intravenously injected with Con A (10?mg/kg), and then killed after 8?h after Con A injection. Serum levels of aspartate transaminase and alanine transaminase were measured to assess hepatic injury. To identify that Gpx1 affects T cell-mediated inflammation, we pretreated Gpx1 inhibitor to Human Jurkat T cells then treated Con A. Con A-induced massive liver damage in WT mice but its damage was attenuated in Gpx1 KO mice. Con A-induced Th1 cytokines such as tumor necrosis factor-? (TNF-?), interferon-? (IFN-?) and interleukin (IL)-2 were also decreased in the liver and spleen of Gpx1 KO mice compared with WT mice. In Jurkat T cells, Con A-induced mRNA levels of IL-2, IFN-? and TNF-? were downregulated by pretreatment of Gpx inhibitor, mercaptosuccinic acid. We also observed that Gpx1 KO mice showed increasing oxidative stress in the liver and spleen compared with WT mice. These results suggest that Gpx1 deficiency attenuates Con A-induced liver injury by induction of T-cell hyporesponsiveness through chronic ROS exposure.

SUBMITTER: Lee DH

PROVIDER: S-EPMC4855674 | biostudies-literature | 2016 Apr

REPOSITORIES: biostudies-literature

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Glutathione peroxidase 1 deficiency attenuates concanavalin A-induced hepatic injury by modulation of T-cell activation.

Lee D H DH Son D J DJ Park M H MH Yoon D Y DY Han S B SB Hong J T JT

Cell death & disease 20160428

Concanavalin A (Con A)-induced hepatitis model is well-established experimental T cell-mediated liver disease. Reactive oxygen species (ROS) is associated with T-cell activation and proliferation, but continued ROS exposure induces T-cell hyporesponsiveness. Because glutathione peroxidase 1 (Gpx1) is an antioxidant enzyme and is involved in T-cell development, we investigated the role of Gpx1 during Con A-induced liver injury in Gpx1 knockout (KO) mice. Male wild-type (WT) mice and Gpx1 KO mice ...[more]

PMID: 27124582

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Project description:Background and Aims: Down-regulation of GPx3 accelerated hepatic senescence, which further caused overwhelming inflammation and severe liver graft injury. MSCs derived from human induced pluripotent stem cells (hiPSC-MSCs) have been developed as more efficient delivery vehicle with the property of injury tropism. Here, we aimed to explore the suppressive role of GPx3 in hepatic IR injury using novel delivery system of hiPSC-MSCs. Methods: The mice IR injury model with partial hepatectomy was established. The engineered hiPSC-MSCs delivering GPx3 was constructed. All the mice were segregated into three groups. hiPSC-MSC-GPx3, hiPSC-MSC-pCDH (vector control) or PBS were injected via portal vein after reperfusion. Liver injury was evaluated by histological and serological test. Hepatic apoptosis was detected by Tunel staining and remnant liver regeneration was assessed by Ki67 staining. The role of hepatic senescence in liver graft injury was evaluated in rat orthotopic liver transplantation model. The suppressive effect of GPx3 on hepatic senescence was examined in mice IR injury model and confirmed in vitro. Hepatic senescence was detected by SA-?-Gal and P16/ink4a staining. Results: GPx3 can be successfully delivered by hiPSC-MSCs into liver tissues. Histological examination showed that hiPSC-MSC-GPx3 treatment significantly ameliorated hepatic IR injury post-operation. Significantly lower LDH (891.43±98.45 mU/mL, P<0.05) and AST (305.77±36.22 IU/L, P<0.01) were observed in hiPSC-MSC-GPx3 group compared with control groups. Less apoptotic hepatocytes were observed and the remnant liver regeneration was more active in hiPSC-MSC-GPx3 group. In rat orthotopic liver transplantation model, more senescent hepatocytes were observed in small-for-size liver graft, in which GPx3 expression was significantly compromised. In mice IR injury model, hiPSC-MSC-GPx3 significantly suppressed hepatic senescence. In addition, rGPx3 inhibited cellular senescence of liver cells in a dose dependent manner. Four candidate genes (CD44, Nox4, IFNG, SERPERINB2) were identified to be responsible for suppressive effect of GPx3 on hepatic senescence. Conclusion: Engineered hiPSC-MSCs delivering GPx3 ameliorated hepatic IR injury via inhibition of hepatic senescence.

Project description:Background & aimsHepatic ischemia-reperfusion injury (IRI) is a major complication of hemorrhagic shock, liver resection and transplantation. YAP, a key downstream effector of the Hippo pathway, is essential for determining cell fate and maintaining homeostasis in the liver. We aimed to elucidate its role in IRI.MethodsThe role of YAP/Hippo signaling was systematically studied in biopsy specimens from 60 patients after orthotopic liver transplantation (OLT), and in a mouse model of liver warm IRI. Human biopsy specimens were collected after 2-10 h of cold storage and 3 h post-reperfusion, before being screened by western blot. In the mouse model, the role of YAP was probed by activating or inhibiting YAP prior to ischemia-reperfusion.ResultsIn human biopsies, high post-OLT YAP expression was correlated with well-preserved histology and improved hepatocellular function at postoperative day 1-7. In mice, the ischemia insult (90 min) triggered intrinsic hepatic YAP expression, which peaked at 1-6 h of reperfusion. Activation of YAP protected the liver against IR-stress, by promoting regenerative and anti-oxidative gene induction, while diminishing oxidative stress, necrosis/apoptosis and the innate inflammatory response. Inhibition of YAP aggravated hepatic IRI and suppressed repair/anti-oxidative genes. In mouse hepatocyte cultures, activating YAP prevented hypoxia-reoxygenation induced stress. Interestingly, YAP activation suppressed extracellular matrix synthesis and diminished hepatic stellate cell (HSC) activation, whereas YAP inhibition significantly delayed hepatic repair, potentiated HSC activation, and enhanced liver fibrosis at 7 days post-IRI. Notably, YAP activation failed to protect Nrf2-deficient livers against IR-mediated damage, leading to extensive fibrosis.ConclusionOur novel findings document the crucial role of YAP in IR-mediated hepatocellular damage and liver fibrogenesis, providing evidence of a potential therapeutic target for the management of sterile liver inflammation in transplant recipients.Lay summaryIn the clinical arm, graft YAP expression negatively correlated with liver function and tissue damage after human liver transplantation. YAP activation attenuated hepatocellular oxidative stress and diminished the innate immune response in mouse livers following ischemia-reperfusion injury. In the mouse model, YAP inhibited hepatic stellate cell activation, and abolished injury-mediated fibrogenesis up to 7 days after the ischemic insult.

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Glutathione peroxidase 1 deficiency attenuates concanavalin A-induced hepatic injury by modulation of T-cell activation.

Publications

Glutathione peroxidase 1 deficiency attenuates concanavalin A-induced hepatic injury by modulation of T-cell activation.

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