Eun-Mi Lee

TGF-β1 is known to inhibit muscle regeneration after muscle injury. However, it is unknown if high systemic levels of TGF-β can affect the muscle regeneration process. In the present study, we demonstrated the effect of a CCl₄ intra-peritoneal injection and losartan (an angiotensin II type 1 receptor antagonist) on skeletal muscle (gastrocnemius muscle) injury and regeneration. Male C57BL/6 mice were grouped randomly as follows: control (n = 7), CCl₄-treatment group (n = 7), and CCl₄ + losartan treatment group (n = 7). After CCl₄ treatment for a 16-week period, the animals were sacrificed and analyzed. The expression of dystrophin significantly decreased in the muscle tissues of the control group, as compared with that of the CCl₄ + losartan group (p < 0.01). p(phospho)-Smad2/3 expression significantly increased in the muscles of the control group compared to that in the CCl₄ + losartan group (p < 0.01). The expressions of Pax7, MyoD, and myogenin increased in skeletal muscles of the CCl₄ + losartan group compared to the corresponding levels in the control group (p < 0.01). We hypothesize that systemically elevated TGF-β1 as a result of CCl₄-induced liver injury causes skeletal muscle injury, while losartan promotes muscle repair from injury via blockade of TGF-β1 signaling.

Proteomic analyses have already been used in a number of hepatological studies and provide important information. However, few reports have focused on changes in the cytoplasmic proteome. The present study therefore aimed to evaluate changes in cytoplasmic proteome of rats in response to alcoholic hepatotoxicity. Rats were fed a Liber-DeCarli liquid diet containing ethanol for four weeks. Cytoplasmic proteins except mitochondrial proteins from the livers of these animals were investigated using two-dimensional gel electrophoresis and mass spectrometry. Alcohol induced a decrease in body weight gain and an increase in alanine transaminase (ALT), cholesterol, and phospholipid levels. Histopathological observations revealed hepatic damage characterized by necrosis and fatty change in alcohol-treated group at week 2, which continues until week 4. Our proteomic analysis revealed that 25 proteins were differentially expressed in the ethanol-fed group. Of these, 12 cytoplasmic proteins are being reported for the first time. Taken together, our results provide further insights into the disease mechanism and therapeutic information of alcoholic liver disease.

Hepatitis C virus (HCV) has become a major public health issue. It is prevalent in most countries. HCV infection frequently begins without clinical symptoms, before progressing to persistent viremia, chronic hepatitis, cirrhosis and hepatocellular carcinoma (HCC) in the majority of patients (70% to 80%). Alcohol is an independent cofactor that accelerates the development of HCC in chronic hepatitis C patients. The purpose of the current study was to evaluate ethanol-induced hepatic changes in HCV core-Tg mice and mutant core Tg mice. Wild type (NTG), core wild-Tg mice (TG-K), mutant core 116-Tg mice (TG-116) and mutant core 99-Tg mice (TG-99) were used in this investigation. All groups were given drinking water with 10% ethanol and 5% sucrose for 13 weeks. To observe liver morphological changes, we performed histopathological and immunohistochemical examinations. Histopathologically, NTG, TG-K and TG-116 mice showed moderate centrilobular necrosis, while severe centrilobular necrosis and hepatocyte dissociation were observed in TG-99 mice with increasing lymphocyte infiltration and piecemeal necrosis. In all groups, a small amount of collagen fiber was found, principally in portal areas. None of the mice were found to have myofibroblasts based on immunohistochemical staining specific for α-SMA. CYP2E1-positive cells were clearly detected in the centrilobular area in all groups. In the TG-99 mice, we also observed cells positive for CK8/18, TGF-β1 and phosphorylated (p)-Smad2/3 and p21 around the necrotic hepatocytes in the centrilobular area (p < 0.01). Based on our data, alcohol intake induced piecemeal necrosis and hepatocyte dissociation in the TG-99 mice. These phenomena involved activation of the TGF-β1/p-Smad2/3/p21 signaling pathway in hepatocytes. Data from this study will be useful for elucidating the association between alcohol intake and HCV infection.

Smad3 is a key mediator of the transforming growth factor (TGF)-β1 signaling pathway that plays central role in inflammation and fibrosis. In present study, we evaluated the effect of Smad3 deficiency in Smad3^−/− mice with carbon tetrachloride (CCl₄)-induced liver fibrosis. The animals were received CCl₄ or olive oil three times a week for 4 weeks. Histopathological analyses were performed to evaluate the fibrosis development in the mice. Alteration of protein expression controlled by Smad3 was examined using a proteomic analysis. CCl₄-induced liver fibrosis was rarely detected in Smad3^−/− mice compared to Smad3^+/+. Proteomic analysis revealed that proteins related to antioxidant activities such as senescence marker protein-30 (SMP30), selenium-binding proteins (SP56) and glutathione S-transferases (GSTs) were up-regulated in Smad3^−/− mice. Western blot analysis confirmed that SMP30 protein expression was increased in Smad3^−/− mice. And SMP30 levels were decreased in CCl₄-treated Smad3^+/+ and Smad3^−/− mice. These results indicate that Smad3 deficiency influences the proteins level related to antioxidant activities during early liver fibrosis. Thus, we suggest that Smad3 deteriorate hepatic injury by inhibitor of antioxidant proteins as well as mediator of TGF-β1 signaling.