Recombinant angiopoietin-like protein 4 attenuates intestinal barrier structure and function injury after ischemia/reperfusion.

BACKGROUND: Intestinal barrier breakdown, a frequent complication of intestinal ischemia-reperfusion (I/R) including dysfunction and the structure changes of the intestine, is characterized by a loss of tight junction and enhanced permeability of the intestinal barrier and increased mortality. To develop effective and novel therapeutics is important for the improvement of outcome of patients with intestinal barrier deterioration. Recombinant human angiopoietin-like protein 4 (rhANGPTL4) is reported to protect the blood-brain barrier when administered exogenously, and endogenous ANGPTL4 deficiency deteriorates radiation-induced intestinal injury. AIM: To identify whether rhANGPTL4 may protect intestinal barrier breakdown induced by I/R. METHODS: Intestinal I/R injury was elicited through clamping the superior mesenteric artery for 60 min followed by 240 min reperfusion. Intestinal epithelial (Caco-2) cells and human umbilical vein endothelial cells were challenged by hypoxia/ reoxygenation to mimic I/R in vitro. RESULTS: Indicators including fluorescein isothiocyanate-conjugated dextran (4 kilodaltons; FD-4) clearance, ratio of phosphorylated myosin light chain/total myosin light chain, myosin light chain kinase and loss of zonula occludens-1, claudin-2 and VE-cadherin were significantly increased after intestinal I/R or cell hypoxia/reoxygenation. rhANGPTL4 treatment significantly reversed these indicators, which were associated with inhibiting the inflammatory and oxidative cascade, excessive activation of cellular autophagy and apoptosis and improvement of survival rate. Similar results were observed in vitro when cells were challenged by hypoxia/reoxygenation, whereas rhANGPTL4 reversed the indicators close to normal level in Caco-2 cells and human umbilical vein endothelial cells significantly. CONCLUSION: rhANGPTL4 can function as a protective agent against intestinal injury induced by intestinal I/R and improve survival via maintenance of intestinal barrier structure and functions.

Fish oil alleviates liver injury induced by intestinal ischemia/reperfusion via AMPK/SIRT-1/autophagy pathway.

AIM: To evaluate whether fish oil (FO) can protect liver injury induced by intestinal ischemia/reperfusion (I/R) via the AMPK/SIRT-1/autophagy pathway. METHODS: Ischemia in Wistar rats was induced by superior mesenteric artery occlusion for 60 min and reperfusion for 240 min. One milliliter per day of FO emulsion or normal saline was administered by intraperitoneal injection for 5 consecutive days to each animal. Animals were sacrificed at the end of reperfusion. Blood and tissue samples were collected for analyses. AMPK, SIRT-1, and Beclin-1 expression was determined in lipopolysaccharide (LPS)-stimulated HepG2 cells with or without FO emulsion treatment. RESULTS: Intestinal I/R induced significant liver morphological changes and increased serum alanine aminotransferase and aspartate aminotransferase levels. Expression of p-AMPK/AMPK, SIRT-1, and autophagy markers was decreased whereas tumor necrosis factor-α (TNF-α) and malonaldehyde (MDA) were increased. FO emulsion blocked the changes of the above indicators effectively. Besides, in LPS-stimulated HepG2 cells, small interfering RNA (siRNA) targeting AMPK impaired the FO induced increase of p-AMPK, SIRT-1, and Beclin-1 and decrease of TNF-α and MDA. SIRT-1 siRNA impaired the increase of SIRT-1 and Beclin-1 and the decrease of TNF-α and MDA. CONCLUSION: Our study indicates that FO may protect the liver against intestinal I/R induced injury through the AMPK/SIRT-1/autophagy pathway.

Protective effects of icariin-mediated SIRT1/FOXO3 signaling pathway on intestinal ischemia/reperfusion-induced acute lung injury.

Acute lung injury (ALI) is a common complication following intestinal ischemia/reperfusion (I/R) and is a major contributing factor to its high mortality rate. Sirtuin 1 (SIRT1), a NAD+-dependent deacetylase, has been reported to have an important role in apoptosis inhibition, oxidative stress resistance and cell lifespan extension through its deacetylation of forkhead box protein O3 (FOXO3). It has been demonstrated that icariin (ICA), a flavonoid extracted from Epimedium, upregulates SIRT1 expression. The aim of the present study was to examine whether ICA-mediated SIRT1/FOXO3 signaling pathway activation had a protective effect on intestinal I/R-induced ALI. The effects of ICA on intestinal I/R-induced ALI and its regulation of the SIRT1/FOXO3 signaling pathway on intestinal I/R-induced ALI were investigated in rats. The results demonstrated that ICA pretreatment markedly reduced intestinal I/R-induced ALI as indicated by histological alterations, including decreased tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), reduced oxidative stress, acetylated FOXO3 and B-cell lymphoma 2 (Bcl-2)-interacting mediator of cell death levels, and increased glutathione (GSH), GSH peroxidase, SIRT1, manganese superoxide dismutase and Bcl-2 levels in rat lung tissues. Furthermore, ICA pretreatment upregulated SIRT1 expression, which then downregulated FOXO3 acetylation. In conclusion, ICA exhibited significant protective effects in intestinal I/R-induced ALI. The protective effect of ICA may be attributed to the upregulation of SIRT1, which contributed to FOXO3 deacetylation and the modulation of downstream antioxidative and anti-apoptotic factors.

Suppression of the p66shc adapter protein by protocatechuic acid prevents the development of lung injury induced by intestinal ischemia reperfusion in mice.

BACKGROUND: Intestinal ischemia/reperfusion (I/R) causes severe histological injury, reactive oxygen species activation, and cell apoptosis in the lung. In this study, we investigated, using a murine intestinal I/R model, the effect of a polyphenolic compound, protocatechuic acid (PCA), in modulation of ShcA and in protection of the lung from I/R-induced injury. METHODS: Fifty ICR mice were randomly divided into five groups, including a control group, intestinal I/R group, control + PCA group, I/R + PCA low-dose group, and I/R + PCA high-dose group. The I/R and I/R + PCA groups were subjected to mesenteric arterial ischemia for 45 minutes and reperfusion for 90 minutes. The control and control + PCA groups underwent a surgical procedure that included isolation of the superior mesenteric artery without occlusion. In all PCA-pretreated groups, the mice received intraperitoneal PCA administration for three consecutive days. Serum specimens were collected for measuring tumor necrosis factor-α and interleukin 6, while lung tissues were harvested for histopathologic assessment including glutathione (GSH) and GSH peroxidase assay. Lung expression of p66shc, phosphorylated p66shc, manganese superoxide dismutase, caspace-3, and Bcl-xL were determined by Western blotting for protein level and semiquantitative reverse transcription-polymerase chain reaction analysis for mRNA level. RESULTS: PCA pretreatment markedly reduced I/R-induced lung injury as indicated by histological alterations; the decreases in tumor necrosis factor-α, interleukin 6, and caspase-3 expression levels; and the increases in GSH, GSH peroxidase, manganese superoxide dismutase, and Bcl-xL levels in the lung. Moreover, PCA treatment down-regulated p66shc expression and phosphorylation. CONCLUSION: PCA has a significant protective effect in lung injury induced by intestinal I/R. The protective effect of PCA may be attributed to the suppression of p66shc and the modulation of downstream antioxidative/antiapoptotic factors.

Inhibition of Rho kinase by fasudil hydrochloride attenuates lung injury induced by intestinal ischemia and reperfusion.

AIM: The aim of this study is to evaluate the role of Rho-kinase in the pathogenesis of lung injury induced by intestinal ischemia/reperfusion (I/R) and the preconditioning effects of fasudil hydrochloride. The novel therapeutic approach of using Rho-kinase inhibitors in the treatment of intestinal I/R is introduced. METHODS: Sprague-Dawley (SD) rats were divided into 4 groups: intestinal I/R group, two fasudil pretreatment groups (7.5 mg/kg and 15 mg/kg), and controls. Intestinal and lung histopathology was evaluated; myeloperoxidase (MPO) and superoxide dismutase (SOD) levels in lung parenchyma were determined. Serum tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were measured. eNOS and P-ERM expression were measured by Western Blot. RESULTS: Lung and intestinal injury were induced by intestinal I/R, characterized by histological damage and a significant increase in BALF protein. Compared to controls, serum TNF-α, IL-6, and lung MPO activity increased significantly in the I/R group, while SOD activity decreased. A strongly positive P-ERM expression was observed, while eNOS expression was weak. After fasudil administration, injury was ameliorated. Serum TNF-α, IL-6, lung MPO and P-ERM expression decreased significantly as compared to the I/R group, while SOD activity and eNOS expression increased significantly. SIGNIFICANCE: Rho-kinase plays a key role in the pathogenesis of lung injury induced by intestinal I/R. The inhibition of the Rho-kinase pathway by fasudil hydrochloride may prevent lung injury.

Sulforaphane protects liver injury induced by intestinal ischemia reperfusion through Nrf2-ARE pathway.

AIM: To investigate the effect of sulforaphane (SFN) on regulation of NF-E2-related factor-2 (Nrf2)-antioxidant response element (ARE) pathway in liver injury induced by intestinal ischemia/reperfusion (I/R). METHODS: Rats were divided randomly into four experimental groups: control, SFN control, intestinal I/R and SFN pretreatment groups (n = 8 in each group). The intestinal I/R model was established by clamping the superior mesenteric artery for 1 h and 2 h reperfusion. In the SFN pretreatment group, surgery was performed as in the intestinal I/R group, with intraperitoneal administration of 3 mg/kg SFN 1 h before the operation. Intestine and liver histology was investigated. Serum levels of aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were measured. Liver tissue superoxide dismutase (SOD), myeloperoxidase (MPO), glutathione (GSH) and glutathione peroxidase (GSH-Px) activity were assayed. The liver transcription factor Nrf2 and heme oxygenase-1 (HO-1) were determined by immunohistochemical analysis and Western blotting analysis. RESULTS: Intestinal I/R induced intestinal and liver injury, characterized by histological changes as well as a significant increase in serum AST and ALT levels (AST: 260.13 +/- 40.17 U/L vs 186.00 +/- 24.21 U/L, P < 0.01; ALT: 139.63 +/- 11.35 U/L vs 48.38 +/- 10.73 U/L, P < 0.01), all of which were reduced by pretreatment with SFN, respectively (AST: 260.13 +/- 40.17 U/L vs 216.63 +/- 22.65 U/L, P < 0.05; ALT: 139.63 +/- 11.35 U/L vs 97.63 +/- 15.56 U/L, P < 0.01). The activity of SOD in the liver tissue decreased after intestinal I/R (P < 0.01), which was enhanced by SFN pretreatment (P < 0.05). In addition, compared with the control group, SFN markedly reduced liver tissue MPO activity (P < 0.05) and elevated liver tissue GSH and GSH-Px activity (P < 0.05, P < 0.05), which was in parallel with the increased level of liver Nrf2 and HO-1 expression. CONCLUSION: SFN pretreatment attenuates liver injury induced by intestinal I/R in rats, attributable to the antioxidant effect through Nrf2-ARE pathway.