Effect of procyanidins on lipid metabolism and inflammation in rats exposed to alcohol and iron

Abstract

Background: Lifestyle involving uncontrolled alcohol consumption coupled regularly with red meat and other iron sources has detrimental effects on the liver, which in the long term, results in Alcoholic Liver Disease (ALD). Procyanidin has lately garnered increasing attention and has become the focus of research owing to its antioxidant properties. This study explores the anti-inflammatory effects of procyanidins, in preventing ALD, by analyzing the biological activities of the compound on liver injury caused by excessive alcohol and iron.

Method: Male SPF Wistar rats were placed in 4 groups; the control Group A (basic diet); the model Group B (excess alcohol 8-12 mL/kg/d and iron 1000 mg/kg diet); the low dose procyanidin Group C (model group diet plus 60 mg/kg/d of procyanidin); and the high dose procyanidin Group D (model group diet plus 120 mg/kg/d of procyanidin). Serum biochemical markers for liver damage were measured spectrophotometrically. The NFκB and IκB mRNA expression levels were determined using RT-PCR; the NFκB p65 and IκB protein expression levels were assessed via western blotting, while ELISA was used to detect serum inflammatory factors.

Results: The pathological score of the model Group B, low and high dose procyanidin Groups C and D were 6.58 ± 0.90,4.69 ± 0.70 and 2.00 ± 0.73, respectively (P < 0.05). The results showed that high alcohol and iron contents in the model group led to significant damage of liver structure, increased low-density lipoproteins (LDLs), steatosis, and increased levels of inflammatory cytokines. High amounts of procyanidins led to the preservation of the liver structure, production of high-density lipoproteins, and reduction in serum inflammatory cytokines while also significantly decreasing the expression levels of NFκB p65.

Conclusion: The results prove that procyanidins have hepatoprotective potential and could be effective in reversing histopathology, possibly by alleviating inflammation and improving lipid metabolism.

Keywords: ALD; Adaptation; Cell biology; Enzymology; Hepatic injury; Hepatoprotective; Immune response; Immunology; Inflammation; Microorganism; Oxidative stress.

Figure 1

Effect of procyanidins on pathology and ultrastructure of rat liver tissue. (A) Representative histological sections of H&E stained rat liver tissue at 12 weeks in each group. 1: Mallory body; 2: Fat Vacuoles; 3: Inflammatory Infiltration; 4: Hepatocyte Hyaline Degeneration. (B) Ultrastructure of rat liver tissue at 12 weeks in each group. 1: Nucleus; 2: Mitochondria; 3: Rough Endoplasmic Reticulum; 4: Capillary Bile Duct; 5: Lipid Droplets. Scale bar = 50 μm for A, 5 μm for B.

Figure 2

Effect of procyanidins on liver function and lipid metabolism in rats. The serum lipid levels of (A) ALT, (B) AST, (C) GGT showed a significant reduction with the increased dosage of procyanidins as compared to the model Group B. The lipid metabolic indicators (D) TG mmol/L, (E) TC, (F) LDL-C, (G) TG mmol/gprot showed reduction after treatment with procyanidin, with the exception of (H) HDL-C which showed an increase in high dose procyanidin Group D (^∗P < 0.05 vs Control; ^#P < 0.05 vs Model).

Figure 3

Effect of procyanidins on NFκB, IκB protein, and mRNA expression levels in rat liver tissue. (A) The above graphical representations show that NFκB mRNA expression is increased in the model Group B but lowered after procyanidin treatment. (B) The IκB mRNA expression levels are increased in the procyanidin treated groups. (C) NFκB protein levels increased in model Group B as compared to the procyanidin groups (D) IκB levels are increased in procyanidin treatment groups. (E) and (F) Western blot analysis was used to detect the expression levels of NFκB p65 and IκB protein in liver tissue. 1: Control Group A; 2: Model Group B; 3: Low dose procyanidin Group C; 4: High dose procyanidin Group D (^∗P < 0.05 vs Control; ^#P < 0.05 vs Model). The full, uncropped images of the western blots are presented in Supplementary Figure 2.

Figure 4

Effect of procyanidins on serum inflammatory factor levels in rats. (A) TNF-α, (B) IL-6, (C) IL-4, (D) IL-10 levels are reduced with the increasing dose of procyanidins as compared with the model Group B (^∗P < 0.05 vs Control; ^#P < 0.05 vs Model).