Hepatic Fibrotic Changes Research Articles

Hepatoprotective effect of dipeptidyl peptidase-4 inhibitor sitagliptin against carbon tetrachloride-induced liver fibrosis in mice

Background and Aim Sitagliptin is a selective dipeptidyl peptidase-4 inhibitor that is used worldwide to ameliorate hyperglycemia and insulin insensitivity-induced dysmetabolism. The current study assessed the effect of sitagliptin as well as silymarin (the standard hepatoprotective drug) against experimentally carbon tetrachloride (CCl4)-induced liver toxicity in male mice. Materials and methods Mice chronic liver fibrosis models were established and divided into olive oil-induced control group, CCl4-induced model group, silymarin-treated group, and sitagliptin-treated group. Hepatic fibrotic changes were evaluated by measuring hepatic enzymes (alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase), histopathological score, activation of hepatic stellate cells (α-smooth muscle actin expression with special stain), and oxidative stress (malondialdehyde, glutathione, total nitrate/nitrite, and manganese superoxide dismutase levels). Results The injection of mice with CCl4 for 7 weeks resulted in a marked elevation of hepatic fibrotic changes and reduction of glutathione level; both silymarin and sitagliptin therapy showed a significant decrease in the fibrotic changes and a significant increase in endogenous antioxidants. Conclusion This study shows that sitagliptin ameliorates hepatic fibrosis in mice and announces a new strategy for treating hepatic fibrosis in humans.

Melatonin mitigates thioacetamide-induced hepatic fibrosis via antioxidant activity and modulation of proinflammatory cytokines and fibrogenic genes

AimsThe potential antifibrotic effects of melatonin against induced hepatic fibrosis were explored. Main methodsRats were allocated into four groups: placebo; thioacetamide (TAA) (200mg/kg bwt, i.p twice weekly for two months); melatonin (5mg/kgbwt, i.p daily for a week before TAA and continued for an additional two months); and melatonin plus TAA. Hepatic fibrotic changes were evaluated biochemically and histopathologically. Hepatic oxidative/antioxidative indices were assessed. The expression of hepatic proinflammatory cytokines (tumor necrosis factor-α, and interleukin-1β), fibrogenic-related genes (transforming growth factor-1β, collagen I, collagen, III, laminin, and autotaxin) and an antioxidant-related gene (thioredoxin-1) were detected by qRT-PCR. Key findingsIn fibrotic rats, melatonin lowered serum aspartate aminotransferase, alanine aminotransferase, and autotaxin activities, bilirubin, hepatic hydroxyproline and plasma ammonia levels. Melatonin displayed hepatoprotective and antifibrotic potential as indicated by mild hydropic degeneration of some hepatocytes and mild fibroplasia. In addition, TAA induced the depletion of glutathione, glutathione s-transferase, glutathione peroxidase, superoxide dismutase, catalase, and paraoxonase-1 (PON-1), while inducing the accumulation of malondialdehyde, protein carbonyl (C=O) and nitric oxide (NO), and DNA fragmentation. These effects were restored by melatonin pretreatment. Furthermore, melatonin markedly attenuated the expression of proinflammatory cytokines and fibrogenic genes via the upregulation of thioredoxin-1 mRNA transcripts. SignificanceMelatonin exhibits potent anti-inflammatory, antioxidant and fibrosuppressive activities against TAA-induced hepatic fibrogenesis via the suppression of oxidative stress, DNA damage, proinflammatory cytokines and fibrogenic gene transcripts. In addition, we demonstrate that the antifibrotic activity of melatonin is mediated by the induction of thioredoxin-1 with attenuation of autotaxin expressions.

Combination of Sitagliptin and Silymarin ameliorates liver fibrosis induced by carbon tetrachloride in rats.

Liver fibrosis is a common pathological condition that occurs in most conditions associated with chronic liver injury. Silymarin is a herbal product widely used for its hepatoprotective effect. Sitagliptin, a dipeptidyl peptidase-4 inhibitor (DPP4-I), is clinically used as an oral antidiabetic agent. This study was designed to investigate the effects of Sitagliptin, Silymarin, and their combination on established liver fibrosis in carbon tetrachloride (CCl4) rat model. Male albino rats received intraperitoneal injections of CCl4 three times a week for 7 weeks, as well as daily oral treatments of Sitagliptin (100mg/kg) or Silymarin (100mg/kg) or their combination during the 7 weeks of intoxication. Hepatic fibrotic changes were evaluated by measuring hepatic enzymes (ALT, AST, ALP, and GGT) and markers of fibrosis (transforming growth factor β1 (TGF-β1), tissue 4-hydroxyproline level, histopathological score), oxidative stress (MDA, GSH, and NOx levels), inflammation (interleukin-6) as well as markers of HSCs activation (α-smooth muscle actin (α-SMA) expression). The injected rats with CCl4 for 7 weeks resulted in a marked elevation of hepatic fibrotic changes and reduction of GSH level, while the combination therapy showed a significant decrease in the former one and a significant increase in the later. In conclusion, this study shows that the combination therapy is more beneficial than monotherapy in ameliorating liver fibrosis in rats. Our findings suggest that Sitagliptin alone or in combination with Silymarin may introduce a new strategy for treating liver fibrosis in humans.

Melatonin ameliorates experimental hepatic fibrosis induced by carbon tetrachloride in rats

To investigate the protective effects of melatonin on carbon tetrachloride (CCl4)-induced hepatic fibrosis in experimental rats. All rats were randomly divided into normal control group, model control group treated with CCl4 for 12 wk, CCl4 + NAC group treated with CCl4 + NAC (100 mg/kg, i.p.) for 12 wk, CCl4 + MEL-1 group treated with CCl4 + melatonin (2.5 mg/kg) for 12 wk, CCl4 + MEL-2 group treated with CCl4 + melatonin (5.0 mg/kg) for 12 wk, and CCl4 + MEL-3 group treated with CCl4 + melatonin (10 mg/kg). Rats in the treatment groups were injected subcutaneously with sterile CCl4 (3 mL/kg, body weight) in a ratio of 2:3 with olive oil twice a week. Rats in normal control group received hypodermic injection of olive oil at the same dose and frequency as those in treatment groups. At the end of experiment, rats in each group were anesthetized and sacrificed. Hematoxylin and eosin (HE) staining and Van Gieson staining were used to examine changes in liver pathology. Serum activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and protein concentration were measured with routine laboratory methods using an autoanalyzer. Hydroxyproline (HYP) content in liver and malondialdehyde (MDA) and glutathione peroxidase (GPx) levels in liver homogenates were assayed by spectrophotometry. Serum hyaluronic acid (HA), laminin (LN), and procollagen III N-terminal peptide (PIIINP) were determined by radioimmunoassay. Pathologic grading showed that the fibrogenesis was much less severe in CCl4 + MEL3 group than in model control group (u = 2.172, P < 0.05), indicating that melatonin (10 mg/kg) can significantly ameliorate CCl4-induced hepatic fibrotic changes. The serum levels of ALT and AST were markedly lower in CCl4 + MEL treatment groups (5, 10 mg/kg) than in model control group (ALT: 286.23 +/- 121.91 U/L vs 201.15 +/- 101.16 U/L and 178.67 +/- 103.14 U/L, P = 0.028, P = 0.007; AST: 431.00 +/- 166.35 U/L vs 321.23 +/- 162.48 U/L and 292.42 +/- 126.23 U/L, P = 0.043, P = 0.013). Similarly, the serum laminin (LN) and hyaluronic acid (HA) levels and hydroxyproline (HYP) contents in liver were significantly lower in CCl4 + MEL-3 group (10 mg/kg) than in model control group (LN: 45.89 +/- 11.71 microg/L vs 55.26 +/- 12.30 microg/L, P = 0.012; HA: 135.71 +/- 76.03 microg/L vs 201.10 +/- 68.46 microg/L, P = 0.020; HYP: 0.42 +/- 0.08 mg/g tissue vs 0.51 +/- 0.07 mg/g tissue, P = 0.012). Moreover, treatment with melatonin (5, 10 mg/kg) significantly reduced the MDA content and increased the GPx activity in liver homogenates compared with model control group (MDA: 7.89 +/- 1.49 noml/mg prot vs 6.29 +/- 1.42 noml/mg prot and 6.25 +/- 2.27 noml/mg prot, respectively, P = 0.015, P = 0.015; GPx: 49.13 +/- 8.72 U/mg prot vs 57.38 +/- 7.65 U/mg prot and 61.39 +/- 13.15 U/mg prot, respectively, P = 0.035, P = 0.003). Melatonin can ameliorate CCl4-induced hepatic fibrosis in rats. The protective effect of melatonin on hepatic fibrosis may be related to its antioxidant activities.

Melatonin ameliorates carbon tetrachloride-induced hepatic fibrogenesis in rats via inhibition of oxidative stress

Melatonin is reported to exhibit a wide variety of biological effects, including antioxidant and anti-inflammatory. Evidence shows the important role of oxidative stress in the etiopathogenesis of hepatic fibrosis. The aim of this study was to investigate the protective effects of administration of melatonin in rats with carbon tetrachloride-induced fibrosis for 6 weeks. Hepatic fibrotic changes were evaluated biochemically by measuring tissue hydroxyproline levels and histopathogical examinations. Malondialdehyde (MDA), an end product of lipid peroxidation, and glutathione peroxidase (GSH-px) and superoxide dismutase (SOD) levels were evaluated in tissue homogenates by spectrophotometry. The nuclear factor-kappaB (NF-κB) in liver tissue was examined by immunohistochemistry. Tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) concentrations in Kupffer cells (KCs) culture supernatants were measured with ELISA. The rats injected subcutaneously with CCl 4 for 6 weeks resulted in hepatic fibrotic changes increased hydroxyproline and MDA levels, and decreased GSH-px and SOD levels, whereas melatonin reversed these effects. Furthermore, melatonin inhibited the expression of NF-κB in liver tissue and decreasing production of proinflammatory cytokines such as TNF-α and IL-1β from KCs in fibrotic rats. These present results suggest that melatonin ameliorates carbon tetrachloride-induced hepatic fibrogenesis in rats via inhibition of oxidative stress and proinflammatory cytokines production.

Melatonin reduces dimethylnitrosamine-induced liver fibrosis in rats.

Increased deposition of the extracellular matrix components, particularly collagen, is a central phenomenon in liver fibrosis. Stellate cells, the central mediators in the pathogenesis of fibrosis are activated by free radicals, and synthesize collagen. Melatonin is a potent physiological scavenger of hydroxyl radicals. Melatonin has also been shown to be involved in the inhibitory regulation of collagen content in tissues. At present, no effective treatment of liver fibrosis is available for clinical use. We aimed to test the effects of melatonin on dimethylnitrosamine (DMN)-induced liver damage in rats. Wistar albino rats were injected with DMN intraperitoneally. Following a single dose of 40 mg/kg DMN, either saline (DMN) or 100 mg/kg daily melatonin was administered for 14 days. In other rats, physiologic saline or melatonin were injected for 14 days, following a single injection of saline as control. Hepatic fibrotic changes were evaluated biochemically by measuring tissue hydroxyproline levels and histopathogical examination. Malondialdehyde (MDA), an end product of lipid peroxidation, and glutathione (GSH) and superoxide dismutase (SOD) levels were evaluated in blood and tissue homogenates. DMN caused hepatic fibrotic changes, whereas melatonin suppressed these changes in five of 14 rats (P < 0.05). DMN administration resulted in increased hydroxyproline and MDA levels, and decreased GSH and SOD levels, whereas melatonin reversed these effects. When melatonin was administered alone, no significant changes in biochemical parameters were noted. In conclusion, the present study suggests that melatonin functions as a potent fibrosuppressant and antioxidant, and may be a therapeutic choice.