Oral Methylthioadenosine Administration Attenuates Fibrosis and Chronic Liver Disease Progression in Mdr2−/− Mice

BACKGROUND: Inflammation and fibrogenesis are directly related to chronic liver disease progression, including hepatocellular carcinoma (HCC) development. Currently there are few therapeutic options available to inhibit liver fibrosis. We have evaluated the hepatoprotective and anti-fibrotic potential of orally-administered 5'-methylthioadenosine (MTA) in Mdr2(-/-) mice, a clinically relevant model of sclerosing cholangitis and spontaneous biliary fibrosis, followed at later stages by HCC development. METHODOLOGY: MTA was administered daily by gavage to wild type and Mdr2(-/-) mice for three weeks. MTA anti-inflammatory and anti-fibrotic effects and potential mechanisms of action were examined in the liver of Mdr2(-/-) mice with ongoing fibrogenesis and in cultured liver fibrogenic cells (myofibroblasts). PRINCIPAL FINDINGS: MTA treatment reduced hepatomegaly and liver injury. α-Smooth muscle actin immunoreactivity and collagen deposition were also significantly decreased. Inflammatory infiltrate, the expression of the cytokines IL6 and Mcp-1, pro-fibrogenic factors like TGFβ2 and tenascin-C, as well as pro-fibrogenic intracellular signalling pathways were reduced by MTA in vivo. MTA inhibited the activation and proliferation of isolated myofibroblasts and down-regulated cyclin D1 gene expression at the transcriptional level. The expression of JunD, a key transcription factor in liver fibrogenesis, was also reduced by MTA in activated myofibroblasts. CONCLUSIONS/SIGNIFICANCE: Oral MTA administration was well tolerated and proved its efficacy in reducing liver inflammation and fibrosis. MTA may have multiple molecular and cellular targets. These include the inhibition of inflammatory and pro-fibrogenic cytokines, as well as the attenuation of myofibroblast activation and proliferation. Downregulation of JunD and cyclin D1 expression in myofibroblasts may be important regarding the mechanism of action of MTA. This compound could be a good candidate to be tested for the treatment of (biliary) liver fibrosis

Maresin 1 activates brown adipose tissue and promotes browning of white adipose tissue in mice

Objective Maresin 1 (MaR1) is a docosahexaenoic acid-derived proresolving lipid mediator with insulin-sensitizing and anti-steatosis properties. Here, we aim to unravel MaR1 actions on brown adipose tissue (BAT) activation and white adipose tissue (WAT) browning. Methods MaR1 actions were tested in cultured murine brown adipocytes and in human mesenchymal stem cells (hMSC)-derived adipocytes. In vivo effects of MaR1 were tested in diet-induced obese (DIO) mice and lean WT and Il6 knockout (Il6−/−) mice. Results In cultured differentiated murine brown adipocytes, MaR1 reduces the expression of inflammatory genes, while stimulates glucose uptake, fatty acid utilization and oxygen consumption rate, along with the upregulation of mitochondrial mass and genes involved in mitochondrial biogenesis and function and the thermogenic program. In Leucine Rich Repeat Containing G Protein-Coupled Receptor 6 (LGR6)-depleted brown adipocytes using siRNA, the stimulatory effect of MaR1 on thermogenic genes was abrogated. In DIO mice, MaR1 promotes BAT remodeling, characterized by higher expression of genes encoding for master regulators of mitochondrial biogenesis and function and iBAT thermogenic activation, together with increased M2 macrophage markers. In addition, MaR1-treated DIO mice exhibit a better response to cold-induced BAT activation. Moreover, MaR1 induces a beige adipocyte signature in inguinal WAT of DIO mice and in hMSC-derived adipocytes. MaR1 potentiates Il6 expression in brown adipocytes and BAT of cold exposed lean WT mice. Interestingly, the thermogenic properties of MaR1 were abrogated in Il6−/− mice. Conclusions These data reveal MaR1 as a novel agent that promotes BAT activation and WAT browning by regulating thermogenic program in adipocytes and M2 polarization of macrophages. Moreover, our data suggest that LGR6 receptor is mediating MaR1 actions on brown adipocytes, and that IL-6 is required for the thermogenic effects of MaR1

Zolmitriptan: A Novel Portal Hypotensive Agent Which Synergizes with Propranolol in Lowering Portal Pressure

Objective: Only a limited proportion of patients needing pharmacological control of portal hypertension are hemodynamic responders to propranolol. Here we analyzed the effects of zolmitriptan on portal pressure and its potential interaction with propranolol. Methods: Zolmitriptan, propranolol or both were tested in two rat models of portal hypertension: common bile duct ligation (CBDL) and CCl4-induced cirrhosis. In these animals we measured different hemodynamic parameters including portal venous pressure, arterial renal flow, portal blood flow and cardiac output. We also studied the changes in superior mesenteric artery perfusion pressure and in arterial wall cAMP levels induced by zolmitriptan, propranolol or both. Moreover, we determined the effect of splanchnic sympathectomy on the response of PVP to zolmitriptan. Results: In both models of portal hypertension zolmitriptan induced a dose-dependent transient descent of portal pressure accompanied by reduction of portal flow with only slight decrease in renal flow. In cirrhotic rats, splanchnic sympathectomy intensified and prolonged zolmitriptan-induced portal pressure descent. Also, propranolol caused more intense and durable portal pressure fall when combined with zolmitriptan. Mesenteric artery perfusion pressure peaked for about 1 min upon zolmitriptan administration but showed no change with propranolol. However propranolol enhanced and prolonged the elevation in mesenteric artery perfusion pressure induced by zolmitriptan. In vitro studies showed that propranolol prevented the inhibitory effects of b2-agonists on zolmitriptan-induced vasoconstriction and the combination of propranolol and zolmitriptan significantly reduced the elevation of cAMP caused by b2-agonists. Conclusion: Zolmitriptan reduces portal hypertension and non-selective beta-blockers can improve this effect. Combinati

Systemic and chronic effects of zolmitriptan and terlipressin in CBDL-rats.

<p>Measurement of arterial pressure (MAP) (A), cardiac output (CO) (B) and systemic vascular resistance (SVR) (C) after zolmitriptan, terlipressin or saline administration. (D) Effect of chronic administration of zolmitriptan in portal pressure (PVP). */**p<0.05/0.01 vs saline.</p

Body weight, biochemical data and basal hemodynamic parameters of rats with portal hypertension which received i.v. infusion of zolmitriptan, terlipressin or saline.

<p>Values of body weight and biochemical variables are expressed as median and ranges and hemodynamic data are expressed as mean±SEM. ALP: alkaline phosphatase, ALT: alanine transaminase, AST: aspartate aminotransferase, PVP: portal vein pressure.</p

Effect of intravenous infusion of zolmitriptan and terlipressin in CBDL-rats.

<p>(A,C) Portal pressure (PVP). (B,D) Renal flow (ARF). *p<0.05 vs saline. */**p<0.05/0.01 vs zolmitriptan dose 10 mg/kg.</p

Effect of zolmitriptan in combination NSBB in CCl4-treated rats.

<p>Propranolol or nadolol were administered as an intravenous infusion and 5 minutes later, zolmitriptan or saline infusion were started and portal pressure (PVP) (A,C) and heart rate (HR) (B,D) recorded. Infusion time is indicated with black (beta-blockers) and grey bars (zolmitriptan). */* indicates significance vs rats receiving only NSBB (p<0.05/0.01).</p

Effect of intravenous infusion of zolmitriptan in CCl4-treated rats.

<p>(A) Portal pressure (PVP). (B) Renal flow (ARF). (C) Portal flow (PBF). (D) Portal pressure after SS. */** significance vs saline or sham p<0.05/0.01.</p

Biochemical data and hemodynamic parameters in CBDL rats after chronic treatment with zolmitriptan or vehicle.

<p>Data are expressed as mean±SEM. _a compared to the vehicle group, p<0.05.</p