Antioxidant defense of Nrf2 vs pro-inflammatory system of NF-κB during the amoebic liver infection in hamster.

Entamoeba histolytica is the causative agent of amoebic liver abscess (ALA), which course with an uncontrolled inflammation and nitro-oxidative stresses, although it is well known that amoeba has an effective defence mechanisms against this toxic environment, the underlying molecular factors responsible for progression of tissue damage remain largely unknown. The purpose of the present study was to determine during the acute stage of ALA in hamsters, the involvement of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and nuclear factor-kappa B (NF-κB), which are activated in response to oxidative stress. From 12 h post-infection the ALA was visible, haematoxylin-eosin and Masson's trichrome stains were consistent with these observations, and alanine aminotransferase, alkaline phosphatase and γ-glutamyl transpeptidase serum activities were increased too. At 48 h after infection, liver glycogen content was significantly reduced. Western blot analyses showed that 4-Hydroxy-2-nonenal peaked at 12 h, while glycogen synthase kinase-3ß, cleaved caspase-3, pNF-κB, interleukin-1ß and tumour necrosis factor-α were overexpressed from 12 to 48 h post-infection. Otherwise, Nrf2 and superoxide dismutase-1, decreased at 48 h and catalase declined at 36 and 48 h. Furthermore, heme oxygenase-1 was increased at 12 and 24 h and decreased to normal levels at 36 and 48 h. These findings suggest for the first time that the host antioxidant system of Nrf2 is influenced during ALA.

An anti-amoebic vaccine: generation of the recombinant antigen LC3 from Entamoeba histolytica linked to mutated exotoxin A (PEΔIII) via the Pichia pastoris system.

OBJECTIVE: To generate an immunogenic chimeric protein containing the Entamoeba histolytica LC3 fragment fused to the retrograde delivery domains of exotoxin A of Pseudomonas aeruginosa and KDEL3 for use as an effective vaccine. RESULTS: A codon-optimized synthetic gene encoding the PEΔIII-LC3-KDEL3 fusion construct was designed for expression in Pichia pastoris. This transgene was subcloned into the plasmid pPIC9 for methanol-inducible expression. After transformation and selection of positive-transformed clones by PCR, the expression of the recombinant protein PEΔIII-LC3-KDEL3 was elicited. SDS-PAGE, protein glycosylation staining and western blot assays demonstrated a 67 kDa protein in the medium culture supernatant. The recombinant protein was detected with a polyclonal anti-6X His tag antibody and a polyclonal E. histolytica-specific antibody. A specific antibody response was induced in hamsters after immunization with this protein. CONCLUSIONS: We report for the first time the design and expression of the recombinant E. histolytica LC3 protein fused to PEΔIII and KDEL3, with potential application as an immunogen.

Protective effects of allopurinol against acute liver damage and cirrhosis induced by carbon tetrachloride: modulation of NF-κB, cytokine production and oxidative stress.

BACKGROUND: The aim of this work was to evaluate the hepatoprotective ability of allopurinol to prevent the liver injury induced by carbon tetrachloride (CCl(4)). METHODS: Acute liver damage was induced with CCl(4) (4g/kg, by gavage); allopurinol (50mg/kg, by gavage) was given 1h before and 1h after CCl(4) intoxication and two daily doses for the previous three days. Cirrhosis was established by CCl(4) administration (0.4g/kg, i. p. three times a week, eight weeks); allopurinol was administered (100mg/kg, by gavage, daily) during the long-term of CCl(4) treatment. Alanine aminotransferase (ALT), γ-glutamyl transpeptidase (γ-GTP), xanthine oxidase (XO), lipid peroxidation, reduced and oxidized glutathione (GSH, GSSG, respectively), hydroxyproline and histopathologycal analysis were performed. Nuclear factor-κB (NF-κB), pro-inflammatory and anti-inflammatory cytokines, transforming growth factor-ß (TGF-ß) and metalloproteinase-13 (MMP-13) were analyzed by Western blots. RESULTS: Acute injury increased ALT and γ-GTP activities, additionally enhanced NF-κB nuclear translocation and cytokines production such as tumor necrosis factor-α, interleukine-1ß, and interleukine-6. Allopurinol partially prevented these effects, while increased interleukine-10. Acute and chronic CCl(4) treatments altered the levels of XO activity, lipid peroxidation, and GSH/GSSG ratio, while these remained within normal range with allopurinol administration. Necrosis, fibrosis and TGF-ß production induced in chronic injury were partially prevented by allopurinol, interestingly, this drug induced MMP-13 activity. CONCLUSIONS: Allopurinol possesses antioxidant, anti-inflammatory and antifibrotic properties, probably by its capacity to reduce NF-κB nuclear translocation and TGF-ß expression, as well as to induce MMP-13. General significance Allopurinol might be effective treatment of liver diseases.

Allopurinol reverses liver damage induced by chronic carbon tetrachloride treatment by decreasing oxidative stress, TGF-ß production and NF-κB nuclear translocation.

Allopurinol is an inhibitor of xanthine oxidase. The aim of this work was to evaluate the efficacy of allopurinol to reverse the experimental cirrhosis induced by CCl4. Rats received CCl4 for 8 weeks, and immediately after allopurinol was administered for 4 weeks more. Allopurinol reversed all markers of liver damage and oxidative stress to normal values, restoring the metabolic capacity of the liver. Chronic injury by CCl4 induced significant overexpression of profibrogenic cytokine TGF-ß, while allopurinol decreased this production and consequently decreased the collagen content. Moreover, allopurinol is capable of partially inhibiting NF-κB. These findings suggest that allopurinol is capable of reversing the cirrhosis induced by CCl4, modulating oxidative stress, TGF-ß expression and NF-κB nuclear translocation.

Secondary biliary cirrhosis in the rat is prevented by decreasing NF-κB nuclear translocation and TGF-ß expression using allopurinol, an inhibitor of xanthine oxidase.

Allopurinol is an inhibitor of xanthine oxidase (XO), and XO is an enzyme that generates great amounts of reactive oxygen species. The aim of this work was to evaluate the efficacy of allopurinol to prevent experimental cirrhosis. Fibrosis and cirrhosis were induced by common bile duct ligation (BDL) for 4 weeks in rats. Animals were divided into 4 groups: sham-operated rats (SHAM); BDL group; BDL plus allopurinol (100 mg·kg⁻¹, p.o.), and SHAM plus allopurinol treatment. Alanine aminotransferase, γ-glutamyl transpeptidase, and alkaline phosphatase were increased in BDL rats but were preserved normal by allopurinol. XO activity was prevented by allopurinol; however, lipophilic and hydrophilic oxidative stress was not prevented by the drug. Allopurinol partially suppresses nuclear factor-κB (NF-κB) nuclear translocation and transforming growth factor-ß (TGF-ß) expression, and increased the active form of matrix metalloproteinase-13 (MMP-13). Moreover, collagen production induced by BDL was partially but significantly reduced by allopurinol. These findings suggest that allopurinol possesses a hepatoprotective effect probably by modulating proteins such as NF-κB, TGF-ß, and MMP-13, helping to protect against liver damage induced by chronic cholestasis and a mechanism independent of oxidative stress.

Coffee prevents CCl(4)-induced liver cirrhosis in the rat.

PURPOSE: Previous clinical observations suggested that coffee may have beneficial effects on the liver. In fact, an inverse relationship between coffee consumption and liver cirrhosis has been reported in humans. However, the causative role of coffee has not been established; therefore, the aim of this work was to study the effect of coffee in an experimental model of liver damage. METHODS: In this work, cirrhosis was induced by chronic CCl(4) administration and soluble or grain coffee (SC, GC, respectively) were co-administered for 8 weeks. RESULTS: CCl(4) administration elevated serum alkaline phosphatase and alanine aminotranspherase, liver lipid peroxidation, collagen content (fourfold) and TGF-ß mRNA, and protein levels; depleted liver glycogen and reduced glutathione (GSH) content. Coffee prevented most of the changes produced by CCl(4). Histopathological analysis was in agreement with biochemical and molecular data. The best effect was produced by GC. It is worth noting that GC preserved the normal collagen content as well as the normal TGF-ß mRNA and protein levels. CONCLUSIONS: Our results suggest (1) that coffee plays a causative role in preventing cirrhosis (at least experimental cirrhosis); (2) that action mechanisms are probably associated with down regulation of the profibrogenic cytokine TGF-ß and to its antioxidant properties and, (3) that GC is more potent than SC. These findings suggest a beneficial effect of coffee on the liver. However, more clinical and basic studies must be performed before reaching a final recommendation.