Karina Reyes-Gordillo

Curcumin prevents and reverses cirrhosis induced by bile duct obstruction or CCl4 in rats: role of TGF-β modulation and oxidative stress

Curcumin is a phytophenolic compound, which is highly efficacious for treating several inflammatory diseases. The aim of this study was to evaluate the efficacy of curcumin in preventing or reversing liver cirrhosis. A 4‐week bile duct ligation (BDL) rat model was used to test the ability of curcumin (100 mg/kg, p.o., daily) to prevent cirrhosis. To reverse cirrhosis, CCl4 was administered chronically for 3 months, and then it was withdrawn and curcumin administered for 2 months. Alanine aminotransferase, γ‐glutamyl transpeptidase, liver histopathology, bilirubin, glycogen, reduced and oxidized glutathione, and TGF‐β (mRNA and protein) levels were assessed. Curcumin preserved normal values of markers of liver damage in BDL rats. Fibrosis, assessed by measuring hydroxyproline levels and histopathology, increased nearly fivefold after BDL and this effect was partially but significantly prevented by curcumin. BDL increased transforming growth factor‐beta (TGF‐β) levels (mRNA and proteins), while curcumin partially suppressed this mediator of fibrosis. Curcumin also partially reversed the fibrosis induced by CCl4. Curcumin was effective in preventing and reversing cirrhosis, probably by its ability of reducing TGF‐β expression. These data suggest that curcumin might be an effective antifibrotic and fibrolitic drug in the treatment of chronic hepatic diseases.

N-acetylcysteine prevents carbon tetrachloride-induced liver cirrhosis: role of liver transforming growth factor-beta and oxidative stress

Objectives N-acetylcysteine (NAC) is an antioxidant, a precursor of reduced glutathione, and an inhibitor of the profibrotic cytokine liver transforming growth factor-beta (TGF-&bgr;). Carbon tetrachloride (CCl4) cirrhosis is characterized by oxidative stress and fibrosis. Therefore, the aim of this work was to study the effect of NAC on experimental cirrhosis. Methods CCl4 was chronically administered for 8 weeks along with 300 mg/kg of NAC orally once a day. Alkaline phosphatase, alanine aminotransferase, and &ggr;-glutamyltranspeptidase were measured in plasma. Hydroxyproline, glycogen, lipid peroxidation, glutathione were determined in liver samples by colorimetric methods. TGF-&bgr; was evaluated by western blotting, and a histopathological analysis was performed. Results Serum markers of liver damage increased by CCl4 intoxication (P<0.05), whereas cotreatment with NAC prevented these increases (P<0.05); glycogen was depleted in the cirrhotic group (P<0.05), but preserved by NAC (P<0.05). Lipid peroxidation increased and glutathione decreased by the administration of CCl4 (P<0.05), again NAC prevented both effects (P<0.05). Importantly, collagen increased by about seven-fold in the CCl4 group (P<0.05); administration of NAC preserved the normal levels of collagen (P<0.05). Biochemical determinations were corroborated by hematoxylin and eosin, and trichromic stains. Western blots revealed a four-fold increase in TGF-&bgr; in the group receiving CCl4, NAC cotreatment abolished TGF-&bgr; signal (P<0.05). Conclusion Our results strongly suggest that NAC prevents experimental cirrhosis by two mechanisms: by preventing oxidative stress and by downregulating the profibrogenic cytokine TGF-&bgr;. As NAC is currently used in humans intoxicated with paracetamol, it can be tested in fibrotic or cirrhotic patients under controlled trials.

Protective Role of Dietary Curcumin in the Prevention of the Oxidative Stress Induced by Chronic Alcohol with respect to Hepatic Injury and Antiatherogenic Markers

Curcumin, an antioxidant compound found in Asian spices, was evaluated for its protective effects against ethanol-induced hepatosteatosis, liver injury, antiatherogenic markers, and antioxidant status in rats fed with Lieber-deCarli low menhaden (2.7% of total calories from ω-3 polyunsaturated fatty acids (PUFA)) and Lieber-deCarli high menhaden (13.8% of total calories from ω-3 PUFA) alcohol-liquid (5%) diets supplemented with or without curcumin (150 mg/kg/day) for 8 weeks. Treatment with curcumin protected against high ω-3 PUFA and ethanol-induced hepatosteatosis and increase in liver injury markers, alanine aminotransferase, and aspartate aminotransferase. Curcumin upregulated paraoxonase 1 (PON1) mRNA and caused significant increase in serum PON1 and homocysteine thiolactonase activities as compared to high ω-3 PUFA and ethanol group. Moreover, treatment with curcumin protected against ethanol-induced oxidative stress by increasing the antioxidant glutathione and decreasing the lipid peroxidation adduct 4-hydroxynonenal. These results strongly suggest that chronic ethanol in combination with high ω-3 PUFA exacerbated hepatosteatosis and liver injury and adversely decreases antiatherogenic markers due to increased oxidative stress and depletion of glutathione. Curcumin supplementation significantly prevented these deleterious actions of chronic ethanol and high ω-3 PUFA. Therefore, we conclude that curcumin may have therapeutic potential to protect against chronic alcohol-induced liver injury and atherosclerosis.

Methyl palmitate prevents CCl4‐induced liver fibrosis

Liver fibrosis is characterized by an excess of collagen fiber deposition, and it is known that Kupffer cells play an important role by immunomodulation of the toxic response. Methyl palmitate (MP) is an effective Kupffer cell inhibitor. The aim of this work was to evaluate the effect of MP on experimental liver fibrosis. Four groups were formed: the control group, which received the vehicles only; CCl4 group (0.4 g kg−1, i.p., three times a week, for eight weeks); CCl4 plus MP (300 mg kg−1, i.p., daily); and MP alone. Alanine aminotransferase was increased by CCl4, and MP did not prevent this increase. Lipid peroxidation was increased markedly by CCl4; again, MP was not able to prevent this effect. Fibrosis increased nearly 6‐fold (measured as liver hydroxyproline content) in the CCl4 group; MP preserved the normal content of collagen. These results were corroborated by histopathology. To elucidate the antifibrogenic mechanism of MP, we measured the production of TGF‐β; CCl4 increased this cytokine several‐fold, and MP abolished this increase. Collectively the present results indicate that MP possesses a strong antifibrogenic effect at least in the CCl4 model of fibrosis. The antifibrotic effect of MP is probably associated with its ability to reduce TGF‐β content, maybe by immunomodulation of Kupffer cells functioning. Copyright

Trolox Down‐Regulates Transforming Growth Factor‐β and Prevents Experimental Cirrhosis

Cirrhosis is a very common disease and its treatment is limited due to lack of effective drugs. Some studies indicate that this disease is associated with oxidative stress. Therefore, we decided to study the effect of trolox, an effective antioxidant, on experimental cirrhosis. Cirrhosis was induced by CCl4 administration (0.4 g/kg, intraperitoneally, three times per week, for 8 weeks) to Wistar male rats. Trolox was administered daily (50 mg/kg, orally). Fibrosis was assessed histologically and by measuring liver hydroxyproline content. Glutathione, lipid peroxidation and glycogen were measured in liver; serum markers of liver damage were also quantified. Transforming growth factor-beta (TGF-beta) was determined by Western blot and quantified densitometrically. Alkaline phosphatase, gamma-glutamyl transpeptidase and alanine aminotransferase increased in the group receiving CCl4; trolox completely or partially prevented these alterations. Glycogen was almost depleted by CCl4 but was partially preserved by trolox. Lipid peroxidation increased while glutathione decreased by CCl4 administration; trolox corrected both effects. Histology showed thick bands of collagen, necrosis and distortion of the hepatic parenchyma in the CCl4 group, such effects were prevented by trolox. Hydroxyproline content increased 5-fold by CCl4, while the group receiving both CCl4 and trolox showed no significant difference compared to the control group. CCl4 increased 3-fold TGF-beta, while trolox completely prevented this increase. We found that trolox effectively prevented cirrhosis induced with CCl4 in the rat. Our results suggest that the beneficial effects of trolox may be associated to its antioxidant properties and to its ability to reduce the profibrogenic cytokine TGF-beta expression.

Oxidative Stress and Inflammation in Hepatic Diseases: Current and Future Therapy

1Lipid Research Laboratory, VA Medical Center, 50 Irving Street NW, Washington, DC 20422, USA 2Department of Biochemistry and Molecular Medicine, The George Washington University, 2300 I Street NW, Suite 530, Washington, DC 20037, USA 3Laboratory of Experimental Hepatology, Department of Pharmacology, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Apartado Postal 14-740, 07000 México, DF, Mexico

Low-ω3 Fatty Acid and Soy Protein Attenuate Alcohol-Induced Fatty Liver and Injury by Regulating the Opposing Lipid Oxidation and Lipogenic Signaling Pathways.

Chronic ethanol-induced downregulation of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) and upregulation of peroxisome proliferator-activated receptor gamma coactivator 1-beta (PGC1β) affect hepatic lipid oxidation and lipogenesis, respectively, leading to fatty liver injury. Low-ω3 fatty acid (Low-ω3FA) that primarily regulates PGC1α and soy protein (SP) that seems to have its major regulatory effect on PGC1β were evaluated for their protective effects against ethanol-induced hepatosteatosis in rats fed with Lieber-deCarli control or ethanol liquid diets with high or low ω3FA fish oil and soy protein. Low-ω3FA and SP opposed the actions of chronic ethanol by reducing serum and liver lipids with concomitant decreased fatty liver. They also prevented the downregulation of hepatic Sirtuin 1 (SIRT1) and PGC1α and their target fatty acid oxidation pathway genes and attenuated the upregulation of hepatic PGC1β and sterol regulatory element-binding protein 1c (SREBP1c) and their target lipogenic pathway genes via the phosphorylation of 5′ adenosine monophosphate-activated protein kinase (AMPK). Thus, these two novel modulators attenuate ethanol-induced hepatosteatosis and consequent liver injury potentially by regulating the two opposing lipid oxidation and lipogenic pathways.