Hypothermia is better than ischemic preconditioning for preventing early hepatic ischemia/reperfusion in rats.

BACKGROUND: Topical hypothermia (TH) and ischemic preconditioning (IPC) are used to decrease I/R injury. The efficacy of isolated or combined use of TH and IPC in the liver regarding inflammation and cytoprotection in early ischemia/reperfusion (I/R) injury needs to be evaluated. MATERIAL AND METHODS: Wistar rats underwent 70% liver ischemia for 90 min followed by 120 min of reperfusion. Livers of animals allocated in the sham, normothermic ischemia (NI), IPC, TH, and TH+IPC groups were collected for molecular analyses by ELISA and Western blot, aiming to compare proinflammatory, anti-inflammatory, and antioxidant profiles. RESULTS: Compared with NI, TH presented decreased tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-6 and IL-12 concentrations and increased IL-10 levels. TH animals displayed lower inducible nitric oxide synthase (iNOS) and higher endothelial nitric oxide synthase (eNOS) expressions. NAD(P)H-quinone oxidoreductase-1(NQO1) expression was also lower with TH. Isolated IPC and NI were similar regarding all these markers. TH+IPC was associated with decreased IL-12 concentration and reduced iNOS and NQO1 expressions, similarly to isolated TH. Expression of Kelch-like ECH-associated protein (Keap)-1 was increased and expression of nuclear and cytosolic nuclear erythroid 2-related factor 2 (Nrf2) was decreased with TH+IPC vs. NI. CONCLUSION: TH was the most effective method of protection against early I/R injury. Isolated IPC entailed triggering of second-line antioxidant defense enzymes. Combined TH+IPC seemed to confer no additional advantage over isolated TH in relation to the inflammatory process, but had the advantage of completely avoid second-line antioxidant defense enzymes.

IRS1 Expression in Hepatic Tissue and Leukocytes in Chronic Hepatitis C Virus Infected Patients: A Comparative Study.

Aims. To determine lymphocyte IRS (IRS1 cells) in HCV patients, correlating it to liver IRS (IRS 1liver) and HOMA-IR. This study tested the hypothesis that IRS1 cells expression can be used as insulin resistance (IR) marker in HCV-infected patients. IRS1 cells were not studied before in HCV infection. Materials and Methods. HCV chronically infected patients, naïve, nonobese, noncirrhotic, and nondiabetic were prospectively included and compared to controls (blood donors). Blood was taken, and leukocytes were separated. IRS1 was determined by real-time PCR. Liver tissue was obtained from transplant donors as controls. Results. 41 HCV-positive patients were included, 26 males (60.5%); mean age of 45 (±7.9); 33 (80.5%) from genotype 1. 6 out of 12 controls were males (50%); mean age was 26.7 (±3.2). There was expression of IRS1 in leukocytes. The median IRS1 cells (HCV) were 0.061 (0.004 to 0.469); the median IRS 1liver (HCV) was 0.0003 (0.00002 to 0.0186)-lower than in controls (resp., P = 0.005 and P = 0.018). HOMA-IR had an inverse correlation with IRS 1liver (P = 0.04). There was no correlation between IRS1 liver and IRS1 cells (P = 0.930). Conclusions. There was expression of IRS1 in leukocytes. IRS1 cells and IRS1 liver were lower in HCV patients than in controls.

Glutamine prevents fibrosis development in rats with colitis induced by 2,4,6-trinitrobenzene sulfonic acid.

We investigated the effects of glutamine on the development of colonic fibrosis and on the expression of the major fibrogenic factors in a rat model of experimental colitis. Colitis was induced in one-half of the male Wistar rats by intracolonic administration of 30 mg of 2,4,6-trinitrobenzene sulfonic acid (TNBS). L-glutamine (25 mg/kg) was administered rectally to one-half of the controls and one-half of the colitic rats. The control, control+glutamine, TNBS, and TNBS+glutamine groups were studied at d 2 and 7 after colitis induction. Glutamine induced a significant decrease in the area of colon fibrosis and in the staining of alpha-smooth muscle actin positive cells within areas of extracellular matrix deposits in the submucosa. Collagen synthesis was stimulated following TNBS administration, with a significant increase in procollagen IV, collagen III, and collagen Ialpha2 mRNA levels in the colon by d 2 after TNBS instillation. Tissue inhibitor of metalloproteinase, connective tissue growth factor, transforming growth factor-beta, platelet-derived growth factor, and phosphorylated Smad3 were overexpressed in the colon of TNBS-treated rats. These effects were significantly abrogated in the colitic rats treated with glutamine. Our findings suggest that glutamine treatment not only attenuates the outcome of TNBS-induced colitis by reducing the inflammatory response but also by downregulating the increased expression of several gene pathways that contribute to the accumulation of matrix proteins. This molecule may be an interesting candidate for reducing the risk of fibrosis and stricture formation in inflammatory bowel disease.

Effects of glutamine on proinflammatory gene expression and activation of nuclear factor kappa B and signal transducers and activators of transcription in TNBS-induced colitis.

BACKGROUND: We investigated the effects of glutamine on proinflammatory gene expression and activation of nuclear factor kappa B (NF-kappaB) and signal transducers and activators of transcription (STAT) in a rat model of experimental colitis. METHODS: Colitis was induced in male Wistar rats by intracolonic administration of 30 mg of 2,4,6-trinitrobenzene sulfonic acid (TNBS). Glutamine (25 mg/kg) was given by rectal route daily for 7 days. RESULTS: Glutamine significantly reduced gross damage and histopathological scores and prevented the decrease of anal pressure and the elevated myeloperoxidase activity observed in the colon of animals receiving TNBS. TNBS administration induced a marked increase of vascular cell adhesion molecule (VCAM-1), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) protein levels. These inflammatory events were associated with increased protein level of NF-kappaB p50 and p65 subunits in the nucleus and significant phosphorylation/degradation of the inhibitor IkappaBalpha. Protein levels of the phosphorylated forms of STAT1, STAT5, and Akt were elevated in animals with colonic damage. All these effects were inhibited by administration of glutamine. Increases in the cytosolic concentration of TBARS and hydroperoxide-initiated chemiluminescence, markers of oxidative stress, and levels of tumor necrosis factor alpha (TNFalpha) and interferon gamma (IFNgamma) were significantly inhibited at 48 hours of TNBS instillation in glutamine-treated animals. CONCLUSIONS: Inhibition of the expression of proinflammatory mediators that are regulated by the NF-kappaB and STAT signaling pathways contribute to the therapeutical effect of glutamine in the TNBS model of experimental colitis. These effects may be brought about by inhibition of oxidative stress and reduced expression of proinflammatory cytokines.

Glutamine inhibits over-expression of pro-inflammatory genes and down-regulates the nuclear factor kappaB pathway in an experimental model of colitis in the rat.

We investigated the effects of glutamine on markers of oxidative stress, nuclear factor kappaB (NF-kappaB) activation, and pro-inflammatory mediators in a rat model of experimental colitis induced by intracolonic administration of 7% acetic acid. Glutamine (25 mg/kg) was given by rectal route 48 and 24h before acetic acid instillation. Glutamine significantly reduced gross damage and histopathological scores, and partially prevented the decrease of anal pressure observed in the animals receiving acetic acid. Increases in the cytosolic concentration of TBARS and hydroperoxide-initiated chemiluminescence were significantly prevented in glutamine-treated animals. Acetic acid instillation induced a marked increase of the NF-kappaB p65 subunit expression in the nucleus and resulted in significant changes in the cytosolic protein level of IkappaB kinases (IKKalpha and IKKbeta) and the non-phosphorylated form of the inhibitor IkappaBalpha. Protein levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were significantly increased. All these effects were partially prevented by administration of glutamine. It is concluded that the anti-inflammatory activity of glutamine in a rat model of acetic acid-induced colitis may be mediated, at least in part, by inhibition of the expression of certain pro-inflammatory mediators which are regulated by the oxidative stress-sensitive NF-kappaB signalling pathway.

Halothane induces oxidative stress and NF-kappaB activation in rat liver: protective effect of propofol.

We investigated the effects of propofol on markers of oxidative stress, nuclear factor kappa B (NF-kappaB) activation and inducible nitric oxide synthase (iNOS) expression in liver of rats treated with halothane under hypoxic conditions. Male Wistar rats received halothane 1%/oxygen 14%, oxygen 14%/propofol 60 mg kg(-1) i.p., or halothane 1%/oxygen 14%/propofol 60 mg kg(-1) i.p. Morphological examination showed complete loss of architecture with massive necrosis of parenchyma in the halothane group, while only minor histological abnormalities were observed in rats receiving halothane plus propofol. The cytosolic concentration of TBARS and the hydroperoxide-initiated chemiluminescence increased significantly in the liver of animals from the halothane group (+62% and +40% versus controls, respectively), and this increase was abolished by propofol administration. Halothane induced a marked activation of NF-kappaB (+180%), and resulted in a significant decrease of the nonphosphorylated form of the inhibitor IkappaBalpha (-53%), while phosphorylated IkappaBalpha protein level was markedly increased (+146%). Propofol administration lowered these effects to +30% (NF-kappaB), -26% (nonphosphorylated IkappaBalpha), and +56% (phosphorylated IkappaBalpha). The increase of iNOS protein level (+59%) induced by halothane was significantly reduced to +22% by additional administration of propofol. Results obtained show that administration of propofol inhibits oxidative stress, NF-kappaB nuclear traslocation and iNOS overexpression in liver of rats receiving halothane. Propofol treatment, by inhibiting the NF-kappaB signal transduction pathway, might block the production of noxious mediators involved in the development of halothane-induced injury.