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Endoplasmic reticulum stress inhibition protects steatotic and non-steatotic livers in partial hepatectomy under ischemia-reperfusion.

ABSTRACT: During partial hepatectomy, ischemia-reperfusion (I/R) is commonly applied in clinical practice to reduce blood flow. Steatotic livers show impaired regenerative response and reduced tolerance to hepatic injury. We examined the effects of tauroursodeoxycholic acid (TUDCA) and 4-phenyl butyric acid (PBA) in steatotic and non-steatotic livers during partial hepatectomy under I/R (PH+I/R). Their effects on the induction of unfolded protein response (UPR) and endoplasmic reticulum (ER) stress were also evaluated. We report that PBA, and especially TUDCA, reduced inflammation, apoptosis and necrosis, and improved liver regeneration in both liver types. Both compounds, especially TUDCA, protected both liver types against ER damage, as they reduced the activation of two of the three pathways of UPR (namely inositol-requiring enzyme and PKR-like ER kinase) and their target molecules caspase 12, c-Jun N-terminal kinase and C/EBP homologous protein-10. Only TUDCA, possibly mediated by extracellular signal-regulated kinase upregulation, inactivated glycogen synthase kinase-3β. This is turn, inactivated mitochondrial voltage-dependent anion channel, reduced cytochrome c release from the mitochondria and caspase 9 activation and protected both liver types against mitochondrial damage. These findings indicate that chemical chaperones, especially TUDCA, could protect steatotic and non-steatotic livers against injury and regeneration failure after PH+I/R.

SUBMITTER: Ben Mosbah I

PROVIDER: S-EPMC3032561 | biostudies-other | 2010 Jul

REPOSITORIES: biostudies-other

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Project description:The aim of the present study was to explore the effect of exogenous hydrogen sulphide (H2S) on endoplasmic reticulum (ER) stress (ERS) in a rat model of hepatic ischemia/reperfusion (I/R) injury. A total of 48 Sprague-Dawley rats were randomly divided into four groups (n=12/group) as follows: Sham, I/R, I/R preceded by NaHS (I/R-NaHS) and I/R preceded by L-C-propargylglycine (PAG), a H2S inhibitor (I/R-PAG). With the exception of the sham group, the rats in the other groups were subjected to 30 min hepatic warm ischemia followed by reperfusion for 6 or 12 h. Hepatic function was evaluated by serum concentrations of alanine aminotransferase (ALT). Apoptosis of hepatic cells was assessed by TUNEL staining and measurement of caspase-12 expression. The expression levels of ERS-associated proteins and mRNAs of pancreatic ER eukaryotic translation initiation factor-2a kinase (PERK), activating transcription factor-6 (ATF6), glucose-regulated protein (GRP) 78, TNF-receptor-associated factor (TRAF)-2, C/EBP homologous protein (CHOP) and caspase-12 were also measured by western blotting and reverse transcription-quantitative PCR. The serum concentrations of ALT in the I/R and I/R-PAG groups were found to be significantly higher compared with those in the sham and I/R-NaHS groups after 6 h of reperfusion; in addition, the ALT level returned to normal in the I/R group, while it increased further in the I/R-PAG group after 12 h of reperfusion. A higher cell apoptosis rate was observed in the I/R and I/R-PAG groups and the highest cell apoptosis rate was observed in the I/R-PAG group; correspondingly, the expression of caspase-12 was increased in the I/R and I/R-PAG groups. H2S appeared to significantly attenuate hepatic I/R-induced ERS response, as indicated by the decreased expression of ATF6, PERK, GRP78, TRAF2 and CHOP. Endogenous H2S may serve a hepatoprotective function after I/R, and inhibition of endogenous H2S results in aggravation of I/R damage. Exogenous H2S was shown to inhibit ERS-related gene expression, leading to suppression of inflammatory reaction and improvement of I/R damage. Therefore, exogenous H2S has therapeutic potential to alleviate hepatic I/R injury.

Project description:IntroductionLongxuetongluo Capsule (LTC) is wildly applied to treat ischemic stroke in clinical practice in China. However, the pharmacological mechanism of LTC on ischemic stroke is still unstated.ObjectiveOur research was designed to study the protective effect of LTC against cerebral ischemia-reperfusion (I/R) injury and reveal the underlying mechanism both in vivo and in vitro.MethodsPC12 cells treated with glucose deprivation/reperfusion (OGD/R) were used to simulate in vitro ischemia/reperfusion (I/R) injury. The cell viability, apoptosis rate, and protein expressions of PC12 cells were evaluated. In vivo validation of the protective effect of LTC was carried out by middle cerebral artery occlusion (MCAO)/reperfusion treatment, and the underlying mechanism of its anti-apoptosis ability was further revealed by immunohistochemistry staining and Western blotting.ResultsIn the current study, we observed that LTC effectively inhibited oxygen-glucose deprivation/reperfusion (OGD/R) induced apoptosis of PC12 cells through suppressing the cleavage of poly ADP-ribose polymerase (PARP), caspase-3, and caspase-9. Further investigation revealed that OGD/R insult remarkably triggered the endoplasmic reticulum stress responses (ER stress) to induce PC12 cell apoptosis. LTC treatment alleviated OGD/R induced ER stress by inhibiting the activation of protein kinase RNA (PKR)-like ER kinase (PERK)/eukaryotic translation initiation factor 2 (eIF2α) and inositol requiring enzyme 1 (IRE1)/tumor necrosis factor receptor-associated factor 2 (TRAF2) pathways. Additionally, LTC also restrained the OGD/R-induced PC12 cell apoptosis by reversing the activated mitogen-activated protein kinase (MAPK) through IRE1/TRAF2 pathway. Animal studies demonstrated LTC significantly restricted the infarct region induced by middle cerebral artery occlusion (MCAO)/reperfusion, the activation of ER stress and apoptosis of neuronal cells had also been suppressed by LTC in the penumbra region.ConclusionLTC protects the cerebral neuronal cell against ischemia/reperfusion injury through ER stress and MAPK-mediated mechanisms.

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Endoplasmic reticulum stress inhibition protects steatotic and non-steatotic livers in partial hepatectomy under ischemia-reperfusion.

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