Grape seed proanthocyanidin protects liver against ischemia/reperfusion injury by attenuating endoplasmic reticulum stress

Abstract

Aim: To explore the effect of grape seed proanthocyanidin (GSP) in liver ischemia/reperfusion (IR) injury and alleviation of endoplasmic reticulum stress.

Methods: Male Sprague-Dawley rats (220-250 g) were divided into three groups, namely, sham, IR, and GSP groups (n = 8 each). A liver IR (70%) model was established and reperfused for 6 h. Prior to reperfusion, the GSP group was administered with GSP (100 mg/kg) for 15 d, and liver histology was then investigated. Serum aminotransferase and inflammatory mediators coupled with superoxide dismutase and methane dicarboxylic aldehyde were detected. Western blot was conducted to analyze the expression of glucose-regulated protein 78, CCAAT/enhancer-binding protein homologous protein, activating transcription factor-4, inositol-requiring enzyme-1, procaspase-12, and nuclear factor-κb. Apoptotic cells were detected by TUNEL staining.

Results: The serum aminotransferase, apoptotic cells, and Suzuki scores decreased in the GSP group compared with the IR group (Ps < 0.05). The methane dicarboxylic aldehyde level was decreased in the GSP group, but the superoxide dismutase level was reversed (Ps < 0.05). Similarly, GSP downregulated the proinflammatory factors and upregulated the levels of anti-inflammatory factors (Ps < 0.05). Western blot data showed that GSP increased glucose-regulated protein 78 expression and suppressed expression of CCAAT/enhancer-binding protein homologous protein, activating transcription factor-4, inositol-requiring enzyme-1, procaspase-12, and nuclear factor-κb compared with the IR group.

Conclusion: GSP possesses antioxidative, anti-inflammatory, and antiapoptotic effects by relieving endoplasmic reticulum stress through regulation of related signaling pathways to protect the liver against IR injury.

Keywords: Anti-apoptosis; Endoplasmic reticulum stress; Grape seed proanthocyanidin; Inflammation; Ischemia/reperfusion injury.

Figure 1

Effects of grape seed proanthocyanidin on serum aminotransferase levels after reperfusion. The levels of A: Alanine aminotransferase (ALT); and B: Aspartate aminotransferase (AST) after ischemia/reperfusion (IR) and with grape seed proanthocyanidin (GSP) treatment. C: Histopathologic changes were scored (Suzuki score) in tissues collected 6 h after reperfusion; D: The sham group showed normal liver structure; E: IR induced severe lobular distortion, apparent edema, hemorrhage, neutrophil infiltration, and cell apoptosis; F: GSP administration improved the condition (HE, 200 ×); n = 8 each; ^aP < 0.05, ^bP < 0.01 vs IR.

Figure 2

Effects of grape seed proanthocyanidin on inflammatory factors after reperfusion. A-D: ELISA; and E-F: Reverse-transcription PCR were performed to evaluate release and expression of transforming growth factor (TGF)-β1, interleukin (IL)-10, IL-6, and tumor necrosis factor (TNF)-α after ischemia/reperfusion (IR) and with grape seed proanthocyanidin (GSP) treatment; n = 8 each; ^aP < 0.05, ^bP < 0.01 vs IR.

Figure 3

Effects of grape seed proanthocyanidin on superoxide dismutase and methane dicarboxylic aldehyde levels. Levels of A: superoxide dismutase (SOD); and B: Methane dicarboxylic aldehyde (MDA) after ischemia/reperfusion (IR) and with grape seed proanthocyanidin (GSP) treatment; n = 8; ^bP < 0.01 vs IR.

Figure 4

Effects of grape seed proanthocyanidin on hepatocytic apoptosis. TUNEL staining was performed and 100 cells per field were counted in three fields (400 ×). A: Sham; B: Ischemia/reperfusion (IR); and C: IR with grape seed proanthocyanidin (GSP) treatment; D: Quantification of TUNEL staining; n = 8 each; ^bP < 0.01 vs IR.

Figure 5

Effects of grape seed proanthocyanidin on the protein expression of endoplasmic reticulum stress proteins in the liver. The expression of glucose-regulated protein (GRP)78, inositol-requiring enzyme (IRE)-1, nuclear factor (NF)-κb, procaspase-12, activating transcription factor (ATF)-4, and CCAAT/enhancer-binding protein homologous protein (CHOP) was assessed by Western blotting after ischemia/reperfusion (IR) and with grape seed proanthocyanidin (GSP) treatment. GAPDH was used as a loading control.