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

Abstract

BackgroundInflammation 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.MethodologyMTA 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 FindingsMTA 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/SignificanceOral 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.

Insulin-like growth factor 1 enhances bile-duct proliferation and fibrosis in Abcb4−/− mice

“…36B4 was used only after having validated it against three reference genes in our previous studies [24]. In BDL model, qPCR was performed as previously described [25]. To assess the significance of the data, ANOVA analysis and Student's t test were employed.…”

Lack of Abcc3 expression impairs bile-acid induced liver growth and delays hepatic regeneration after partial hepatectomy in mice

“…Serum transaminases were measured as described [19]. BA concentrations in bile were measured by the 3a-hydroxysteroid dehydrogenase method.…”

Epidermal Growth Factor Receptor Signaling in Hepatocellular Carcinoma: Inflammatory Activation and a New Intracellular Regulatory Mechanism

“…In the case of PC12 pheochromocytoma cells, manipulation (increase) of the ERK1/2 signal amplitude with MTA (or by PRMT5 knockdown) shifted the biological response to EGF from proliferation to growth arrest and differentiation into neuron-like cells [19]. Interestingly, MTA has been tested in different experimental models of liver inflammatory injury, fibrosis, and carcinogenesis, showing notorious hepatoprotective, antifibrotic, and antitumoral effects [20,21,22,23,24]. One of the most prominent cellular effects of MTA was its ability to limit growth factor-induced cell proliferation; however, the molecular mechanisms responsible for this antiproliferative effect were not completely understood [22,24].…”

“…Interestingly, MTA has been tested in different experimental models of liver inflammatory injury, fibrosis, and carcinogenesis, showing notorious hepatoprotective, antifibrotic, and antitumoral effects [20,21,22,23,24]. One of the most prominent cellular effects of MTA was its ability to limit growth factor-induced cell proliferation; however, the molecular mechanisms responsible for this antiproliferative effect were not completely understood [22,24]. As indicated above, the intensity of the RAF-ERK signal can dictate the ultimate response of the cell to a growth factor, i.e.…”

“…AML12 mouse hepatocytes were incubated for 24 h in serum-free medium (control), with AR (50 ng/ml) or with fetal calf serum (FCS; 10%) in the absence or presence of MTA (500 µ m ). 3 H-thymidine was added for the last 8 h of the incubation and its incorporation into newly synthesized DNA was measured as described [24]. * p < 0.05 vs. control ( a ).…”