Chemerin Overexpression in the Liver Protects against Inflammation in Experimental Non-Alcoholic Steatohepatitis.

Non-alcoholic steatohepatitis (NASH) is marked by macrophage infiltration and inflammation. Chemerin is a chemoattractant protein and is abundant in hepatocytes. The aim of this study was to gain insight into the role of hepatocyte-produced prochemerin in NASH. Therefore, mice were infected with adeno-associated virus 8 to direct hepatic overexpression of prochemerin in a methionine-choline deficient dietary model of NASH. At the end of the study, hepatic and serum chemerin were higher in the chemerin-expressing mice. These animals had less hepatic oxidative stress, F4/80 and CC-chemokine ligand 2 (CCL2) protein, and mRNA levels of inflammatory genes than the respective control animals. In order to identify the underlying mechanisms, prochemerin was expressed in hepatocytes and the hepatic stellate cells, LX-2. Here, chemerin had no effect on cell viability, production of inflammatory, or pro-fibrotic factors. Notably, cultivation of human peripheral blood mononuclear cells (PBMCs) in the supernatant of Huh7 cells overexpressing chemerin reduced CCL2, interleukin-6, and osteopontin levels in cell media. CCL2 was also low in RAW264.7 cells exposed to Hepa1-6 cell produced chemerin. In summary, the current study showed that prochemerin overexpression had little effect on hepatocytes and hepatic stellate cells. Of note, hepatocyte-produced chemerin deactivated PBMCs and protected against inflammation in experimental NASH.

Accumulation of cholesterol, triglycerides and ceramides in hepatocellular carcinomas of diethylnitrosamine injected mice.

BACKGROUND: Dysregulated lipid metabolism is critically involved in the development of hepatocellular carcinoma (HCC). The respective metabolic pathways affected in HCC can be identified using suitable experimental models. Mice injected with diethylnitrosamine (DEN) and fed a normal chow develop HCC. For the analysis of the pathophysiology of HCC in this model a comprehensive lipidomic analysis was performed. METHODS: Lipids were measured in tumor and non-tumorous tissues by direct flow injection analysis. Proteins with a role in lipid metabolism were analysed by immunoblot. Mann-Whitney U-test or paired Student´s t-test were used for data analysis. RESULTS: Intra-tumor lipid deposition is a characteristic of HCCs, and di- and triglycerides accumulated in the tumor tissues of the mice. Peroxisome proliferator-activated receptor gamma coactivator 1 alpha, lipoprotein lipase and hepatic lipase protein were low in the tumors whereas proteins involved in de novo lipogenesis were not changed. Higher rates of de novo lipogenesis cause a shift towards saturated acyl chains, which did not occur in the murine HCC model. Besides, LDL-receptor protein and cholesteryl ester levels were higher in the murine HCC tissues. Ceramides are cytotoxic lipids and are low in human HCCs. Notably, ceramide levels increased in the murine tumors, and the simultaneous decline of sphingomyelins suggests that sphingomyelinases were involved herein. DEN is well described to induce the tumor suppressor protein p53 in the liver, and p53 was additionally upregulated in the tumors. CONCLUSIONS: Ceramides mediate the anti-cancer effects of different chemotherapeutic drugs and restoration of ceramide levels was effective against HCC. High ceramide levels in the tumors makes the DEN injected mice an unsuitable model to study therapies targeting ceramide metabolism. This model is useful for investigating how tumors evade the cytotoxic effects of ceramides.

Hepatic lipid profile in mice fed a choline-deficient, low-methionine diet resembles human non-alcoholic fatty liver disease.

BACKGROUND: Emerging data support a role for lipids in non-alcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC) in humans. With experimental models such data can be challenged or validated. Mice fed a low-methionine, choline-deficient (LMCD) diet develop NASH and, when injected with diethylnitrosamine (DEN), HCC. Here, lipidomic analysis was used to elucidate whether the NASH and HCC associated lipid derangements resemble the lipid profile of the human disease. METHODS: Lipids were measured in the liver of mice fed a control or a LMCD diet for 16 weeks. DEN was injected at young age to initiate hepatocarcinogenesis. DEN treatment associated changes of the lipid composition and the tumor lipidome were evaluated. RESULTS: LMCD diet fed mice accumulated ceramides and triacylglycerols in the liver. Phospholipids enriched with monounsaturated fatty acids were also increased, whereas hepatic cholesterol levels remained unchanged in the LMCD model. Phosphatidylcholine and lysophosphatidylcholine concentrations declined in the liver of LMCD diet fed mice. The changes of most lipids associated with LMCD diet feeding were similar between water and DEN injected mice. Several polyunsaturated (PU) diacylglycerol species were already low in the liver of DEN injected mice fed the control diet. Tumors developed in the liver of LMCD diet fed mice injected with DEN. The tumor specific lipid profile, however, did not resemble the decrease of ceramides and PU phospholipids, which was consistently described in human HCC. Triacylglycerols declined in the cancer tissues, which is in accordance with a low expression of lipogenic enzymes in the tumors. CONCLUSIONS: The LMCD model is suitable to study NASH associated lipid reprogramming. Hepatic lipid profile was modestly modified in the DEN injected mice suggesting a function of these derangements in carcinogenesis. Lipid composition of liver tumors did not resemble the human HCC lipidome, and most notably, lipogenesis and triacylglycerol levels were suppressed.

Chemerin Is Induced in Non-Alcoholic Fatty Liver Disease and Hepatitis B-Related Hepatocellular Carcinoma.

Chemerin is protective in experimental models of hepatocellular carcinoma (HCC). Noteworthy, chemerin mRNA and protein were reduced in HCC tissues of Asian patients with mostly hepatitis B disease etiology. The current study nevertheless showed that chemerin protein was induced in tumor tissues of European HCC patients with non-alcoholic fatty liver disease (NAFLD) and patients with unclear disease etiology. A similar regulation was observed in hepatitis B virus (HBV), but not in hepatitis C virus (HCV), related HCC. The apparent discrepancy between the regulation of chemerin in HBV-HCC obtained from our study and recent reports led us to use the chemerin antibodies applied in the previous assays. These antibodies could not equally detect different chemerin isoforms, which were overexpressed in HepG2 cells. Higher chemerin protein in HCC was nevertheless confirmed by the use of all antibodies. Chemerin protein was low in Huh7 and PLC/PRF/5 cells whereas HepG2 and Hep3B cells had chemerin protein similar as primary human hepatocytes. Besides, the anti-tumor effects of retinoids in hepatocyte cell lines did not enclose upregulation of chemerin, which was initially discovered as a tazarotene induced protein in the skin. Finally, protein levels of the chemerin receptor, chemokine-like receptor 1 (CMKLR1), declined in non-viral, and tended to be lower in HBV-HCC tissues suggesting reduced chemerin activity in the tumors. To sum up, our work showed an opposite regulation of chemerin and CMKLR1 in NAFLD and HBV associated HCC. In HCV-HCC neither chemerin nor its receptor were changed in the tumor tissues. Current findings do not support a critical role of total chemerin protein levels in HCC of non-viral and viral etiology. Accordingly, tumor-localized chemerin protein was not associated with tumor-node-metastasis classification.

Alpha-syntrophin deficiency protects against non-alcoholic steatohepatitis associated increase of macrophages, CD8+ T-cells and galectin-3 in the liver.

Non-alcoholic steatohepatitis (NASH) is characterized by immune cell infiltration. Loss of the scaffold protein alpha-syntrophin (SNTA) protected mice from hepatic inflammation in the methionine-choline-deficient (MCD) diet model. Here, we determined increased numbers of macrophages and CD8+ T-cells in MCD diet induced NASH liver of wild type mice. In the mutant animals these NASH associated changes in immune cell composition were less pronounced. Further, there were more γδ T-cells in the NASH liver of the null mice. Galectin-3 protein in the hepatic non-parenchymal cell fraction was strongly induced in MCD diet fed wild type but not mutant mice. Antioxidant enzymes declined in NASH liver with no differences between the genotypes. To identify the target cells responsive to SNTA loss in-vitro experiments were performed. In the human hepatic stellate cell line LX-2, SNTA did not regulate pro-fibrotic or antioxidant proteins like alpha-smooth muscle actin or catalase. Soluble galectin-3 was, however, reduced upon SNTA knock-down and increased upon SNTA overexpression. SNTA deficiency neither affected cell proliferation nor cell death of LX-2 cells. In the macrophage cell line RAW264.7 low SNTA indeed caused higher galectin-3 production whereas release of TNF and cell viability were normal. Moreover, SNTA had no effect on hepatocyte chemerin and CCL2 expression. Overall, SNTA loss improved NASH without causing major effects in macrophage, hepatocyte and hepatic stellate cell lines. SNTA null mice fed the MCD diet had less body weight loss and this seems to contribute to improved liver health of the mutant mice.

Variations in hepatic lipid species of age-matched male mice fed a methionine-choline-deficient diet and housed in different animal facilities.

BACKGROUND: Non-alcoholic steatohepatitis (NASH) is a common disease and feeding mice a methionine-choline-deficient (MCD) diet is a frequently used model to study its pathophysiology. Genetic and environmental factors influence NASH development and liver lipid content, which was studied herein using C57BL/6 J mice bred in two different animal facilities. METHODS: Age-matched male C57BL/6 J mice bred in two different animal facilities (later on referred to as WT1 and WT2) at the University Hospital of Regensburg were fed identical MCD or control chows for 2 weeks. Hepatic gene and protein expression and lipid composition were determined. RESULTS: NASH was associated with increased hepatic triglycerides, which were actually higher in WT1 than WT2 liver in both dietary groups. Cholesterol contributes to hepatic injury but was only elevated in WT2 NASH liver. Ceramides account for insulin resistance and cell death, and ceramide species d18:1/16:0 and d18:1/18:0 were higher in the NASH liver of both groups. Saturated sphingomyelins only declined in WT1 NASH liver. Lysophosphatidylcholine concentrations were quite normal in NASH and only one of the 12 altered phosphatidylcholine species declined in NASH liver of both groups. Very few phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol species were comparably regulated in NASH liver of both animal groups. Seven of these lipid species declined and two increased in NASH. Notably, hepatic mRNA expression of proinflammatory (F4/80, CD68, IL-6, TNF and chemerin) and profibrotic genes (TGF beta and alpha SMA) was comparable in WT1 and WT2 mice. CONCLUSIONS: Mice housed and bred in different animal facilities had comparable disease severity of NASH whereas liver lipids varied among the groups. Thus, there was no specific lipid signature for NASH in the MCD model.

Overexpression of Hepatocyte Chemerin-156 Lowers Tumor Burden in a Murine Model of Diethylnitrosamine-Induced Hepatocellular Carcinoma.

The tumor inhibitory potential of the highly active chemerin-156 isoform was described in orthotopic models of hepatocellular carcinoma (HCC). The majority of HCC arises in the fibrotic liver, which was not reproduced in these studies. Here, a potential therapeutic activity of chemerin-156 was evaluated in diethylnitrosamine (DEN)-induced liver cancer, which mimics fibrosis-associated HCC. Mice were infected with adeno-associated virus (AAV) six months after DEN injection to overexpress chemerin-156 in the liver, and animals injected with non-recombinant-AAV served as controls. Three months later, the animals were killed. Both groups were comparable with regard to liver steatosis and fibrosis. Of note, the number of very small tumors was reduced by chemerin-156. Anyhow, the expression of inflammatory and profibrotic genes was similar in larger tumors of control and chemerin-156-AAV-infected animals. Although genes with a role in lipid metabolism, like 3-hydroxy-3-methylglutaryl-coenzym-A--reductase, were overexpressed in tumors of animals with high chemerin-156, total hepatic cholesterol, diacylglycerol and triglyceride levels, and distribution of individual lipid species were normal. Chemerin-156-AAV-infected mice had elevated hepatic and systemic chemerin. Ex vivo activation of the chemerin receptor chemokine-like receptor 1 increased in parallel with serum chemerin, illustrating the biological activity of the recombinant protein. In the tumors, chemerin-155 was the most abundant variant. Chemerin-156 was not detected in tumors of the controls and was hardly found in chemerin-156-AAV infected animals. In conclusion, the present study showed that chemerin-156 overexpression caused a decline in the number of small lesions but did not prevent the growth of pre-existing neoplasms.

Alpha-syntrophin dependent expression of tubulin alpha 8 protein in hepatocytes.

The scaffold protein alpha-syntrophin (SNTA) is a component of the dystrophin glycoprotein complex and has been comprehensively studied in skeletal muscle and adipocytes. SNTA is further expressed in the liver where its biological role remains unclear. Unpublished data from our group suggested that SNTA deficiency is associated with altered tubulin alpha 8 (TUBA8) levels in fat. TUBA8 is highly expressed in different cell lines including hepatoma cells, and here we analyzed whether SNTA has a role herein. In Hepa1-6 cells, TUBA8 protein levels were increased upon SNTA knock down and were reduced upon overexpression of SNTA. This regulation was not identified when analyzing mRNA expression. In the liver of SNTA-deficient mice, TUBA8 protein was higher compared to the respective wild-type controls while RNA expression was even suppressed. Using the HaloTag platform, TUBA8 was found to form a complex with SNTA in Hepa1-6 cells. In the hepatic stellate cell line LX-2, the lack or overexpression of SNTA did, however, not change TUBA8 protein expression. SNTA and TUBA8 are described to regulate cell proliferation. Yet, knock down of SNTA did neither affect proliferation nor viability of Hepa1-6 cells. The present study shows that SNTA protein levels are inversely related to TUBA8 protein expression in the hepatocyte cell line Hepa1-6.

Chemerin in a Mouse Model of Non-alcoholic Steatohepatitis and Hepatocarcinogenesis.

BACKGROUND/AIM: Non-alcoholic steatohepatitis (NASH) is a risk factor for hepatocellular carcinoma (HCC). The adipokine chemerin protects from HCC and is reduced in human HCC. In this study, chemerin expression was analyzed in a murine model of NASH-HCC. MATERIALS AND METHODS: Serum and hepatic chemerin, and ex vivo chemerin receptor activation were monitored in NASH and NASH-HCC in mice fed a low-methionine diet deficient in choline after initiation of tumors by injection of diethylnitrosamine. RESULTS: In non-tumorous liver tissues, the extent of hepatic steatosis, and the levels of proteins regulating hepatic lipids and liver fibrosis were similar in NASH and NASH-associated HCC. Systemic and hepatic chemerin, and chemerin receptor activation were not changed in HCC. Liver tumors only developed in diethylnitrosamine-injected mice and their number was increased in NASH. Chemerin protein was induced in liver in NASH, but was unchanged in HCC tissues. CONCLUSION: Hepatic and serum chemerin and ex vivo analyzed chemerin receptor activation do not differ in murine NASH-associated HCC when compared to NASH. Hepatic tumors still develop despite high endogenous levels of serum and liver chemerin protein.

The adaptor protein alpha-syntrophin is reduced in human non-alcoholic steatohepatitis but is unchanged in hepatocellular carcinoma.

The adaptor protein alpha-syntrophin (SNTA) is differentially expressed in varying types of cancer and affects triglyceride levels, inflammatory response and cell proliferation. However, little is known about the expression of SNTA in liver diseases. Non-alcoholic steatohepatitis (NASH) is characterized by hepatic steatosis, inflammation and eventually fibrosis, and may progress to hepatocellular carcinoma (HCC). Here, SNTA mRNA was analyzed in liver tissues from 71 non-alcoholic fatty liver disease patients and 32 controls to assess associations with disease characteristics. SNTA mRNA expression was reduced in NASH liver and negatively correlated with steatosis, inflammation, fibrosis and NASH scores. In the NASH patients, those with type 2 diabetes had a higher fibrosis score, reduced inflammation and increased hepatic SNTA mRNA levels demonstrating a strong association of SNTA mRNA levels with inflammation. Recently, we have shown diminished expression of the high-density lipoprotein scavenger receptor BI (SR-BI) in the liver of syntrophin-deficient mice. Indeed, hepatic SNTA and SR-BI mRNA were positively correlated. SNTA protein was further determined in tumor and non-tumorous tissues of 21 HCC patients. Protein expression was unchanged in the tumor and not related to staging and grading. Present study identified associations of hepatic SNTA mRNA levels with SR-BI and features of NASH assuming a function of this protein in chronic liver disease and cholesterol metabolism.

Tubulin alpha 8 is expressed in hepatic stellate cells and is induced in transformed hepatocytes.

Tubulin alpha 8 (TUBA8) is highly abundant in murine liver tumors suggesting a role in hepatocellular carcinoma (HCC). Non-alcoholic steatohepatitis (NASH) is a risk factor for HCC. In mice that are fed with a methionine-choline deficient diet for two weeks to induce advanced murine NASH, we do see increased hepatic levels of TUBA8 protein. In animals given a high-fat diet for 14 weeks or an atherogenic diet for 12 weeks, hepatic TUBA8 is unchanged. TUBA8 is highly expressed in human hepatic stellate cells (HSC) and co-localizes with the HSC marker desmin in the murine liver. Inflammatory (TNF, LPS, IL-6) and profibrotic mediators (TGF-beta) do not regulate TUBA8 in HepG2 cells, primary HSC and the HSC cell line LX-2, when stimulated for 24 h. Agonists of the farnesoid X receptor and peroxisome proliferator activated receptor gamma, which are nuclear receptors involved in NASH and HCC pathophysiology, have no effect on TUBA8 in HepG2 and LX-2 cells. In human HCC tissues of 18 patients TUBA8 is significantly upregulated when compared to the corresponding non-tumorous tissues. Compared to non-transformed hepatocytes, TUBA8 protein is strongly expressed in transformed cells. Thus, TUBA8 is a marker of HSC whose cell number is increased in NASH, while higher levels in HCC may be related to induction of TUBA8 in parenchymal cells.

Hepatic chemerin mRNA expression is reduced in human nonalcoholic steatohepatitis.

BACKGROUND: Chemerin is associated with insulin resistance and is expressed in the liver. Nonalcoholic fatty liver disease (NAFLD) is related to impaired insulin sensitivity, but studies evaluating hepatic and serum chemerin in NAFLD resulted in discordant data. MATERIALS AND METHODS: Chemerin mRNA was determined in the liver tissue obtained from 33 controls and 76 NAFLD patients. Chemerin serum levels were measured in a different cohort of patients with ultrasound-diagnosed NAFLD and the respective controls. Hepatic stellate cells and hepatocytes were exposed to selected metabolites and nuclear receptor agonists to study the regulation of chemerin. Effect of recombinant chemerin on hepatocyte released proteins was analysed. RESULTS: Hepatic chemerin expression was not related to BMI, gender, type 2 diabetes and hypertension. Chemerin mRNA did not correlate with steatosis and was negatively associated with inflammation, fibrosis and nonalcoholic steatohepatitis (NASH) score. Patients with NASH had lower chemerin mRNA compared to those with borderline NASH and controls. Factors with a role in NASH mostly did not regulate chemerin in the liver cells. Of note, liver X receptor agonist reduced chemerin protein. Serum chemerin was not changed in NAFLD. Levels positively correlated with age, waist-to-hip ratio, systolic blood pressure, serum FGF21 and lipocalin 2, and negatively with transferrin saturation. Chemerin induced FGF21 in supernatants of primary human hepatocytes. Hepcidin, a major regulator of iron homoeostasis and lipocalin 2, were not regulated by chemerin. CONCLUSION: Chemerin mRNA is reduced in the liver of NASH patients, and liver X receptor seems to have a role herein.

Ceramide and polyunsaturated phospholipids are strongly reduced in human hepatocellular carcinoma.

Lipid composition affects membrane function, cell proliferation and cell death and is changed in cancer tissues. Hepatocellular carcinoma (HCC) is an aggressive cancer and this study aimed at a comprehensive characterization of hepatic and serum lipids in human HCC. Cholesteryl ester were higher in tumorous tissues (TT) compared to adjacent non-tumorous tissues (NT). Free cholesterol exerting cytotoxic effects was not changed. Phosphatidylethanolamine, -serine (PS) and -inositol but not phosphatidylcholine (PC) and lysophosphatidylcholine (LPC) were reduced in HCC tissues. Saturated species mostly increased and polyunsaturated species were diminished in all of these phospholipids. Ceramide (Cer) was markedly reduced in HCC tissues and higher levels of sphingomyelin suggest impaired sphingomyelinase activity as one of the underlying mechanisms. Importantly, ceramide in NT increased in HCC stage T3. Ceramide released from hepatocytes attracts immune cells and a positive association of the macrophage specific receptor CD163 with NT ceramide was identified. HCC associated lipid changes did not differ in patients suffering from type 2 diabetes. Protein levels of p53 were induced in TT and negatively correlated with Cer d18:1/16:0 and PS 36:1. Of the lipid species changed in HCC tissues only TT Cer d18:1/16:0, Cer d18:1/24:1, PC 38:6 and LPC 22:6 correlated with the respective serum levels. Our study demonstrates a considerably altered hepatic lipidome in HCC tissues. Ceramide was markedly reduced in HCC tissues, and therefore, raising ceramide levels specifically in the tumor represents a reasonable therapeutic approach for the treatment of this malignancy.

Circulating lipocalin 2 is neither related to liver steatosis in patients with non-alcoholic fatty liver disease nor to residual liver function in cirrhosis.

Lipocalin 2 (LCN2) is induced in the injured liver and associated with inflammation. Aim of the present study was to evaluate whether serum LCN2 is a non-invasive marker to assess hepatic steatosis in patients with non-alcoholic fatty liver disease (NAFLD) or residual liver function in patients with liver cirrhosis. Therefore, LCN2 was measured by ELISA in serum of 32 randomly selected patients without fatty liver (controls), 24 patients with ultrasound diagnosed NAFLD and 42 patients with liver cirrhosis mainly due to alcohol. Systemic LCN2 was comparable in patients with liver steatosis, those with liver cirrhosis and controls. LCN2 negatively correlated with bilirubin in both cohorts. In cirrhosis, LCN2 was not associated with more advanced liver injury defined by the CHILD-PUGH score and model for end-stage liver disease score. Resistin but not C-reactive protein or chemerin positively correlated with LCN2. LCN2 levels were not increased in patients with ascites or patients with esophageal varices. Consequently, reduction of portal pressure by transjugular intrahepatic portosystemic shunt did not affect LCN2 levels. Hepatic venous blood (HVS), portal venous blood and systemic venous blood levels of LCN2 were similar. HVS LCN2 was unchanged in patients with end-stage liver cirrhosis compared to those with well-compensated disease arguing against increased hepatic release. Current data exclude that serum LCN2 is of any value as steatosis marker in patients with NAFLD and indicator of liver function in patients with alcoholic liver cirrhosis.

Annexin A6 protein is downregulated in human hepatocellular carcinoma.

Annexin A6 (AnxA6) is a lipid-binding protein highly expressed in the liver, regulating cholesterol homeostasis and signaling pathways with a role in liver physiology. Here, we analyzed whether hepatic AnxA6 levels are affected by pathological conditions that are associated with liver dysfunction and liver injury. AnxA6 levels in the fatty liver of mice fed a high-fat diet, in ob/ob and db/db animals and in human fatty liver are comparable to controls. Similarly, AnxA6 levels appear unaffected in murine nonalcoholic steatohepatitis and human liver fibrosis. Accordingly, adiponectin, lysophosphatidylcholine, palmitate, and TGFbeta, all of which have a role in liver injury, do not affect AnxA6 expression in human hepatocytes. Likewise, adiponectin and IL8 do not alter AnxA6 levels in primary human hepatic stellate cells. However, in hepatic tumors of 18 patients, AnxA6 protein levels are substantially reduced compared to nontumorous tissues. AnxA6 mRNA is even increased in the tumors suggesting that posttranscriptional mechanisms are involved herein. Lipidomic analysis shows trends toward elevated cholesteryl ester and sphingomyelin in the tumor samples, yet the ratio of tumor to nontumorous AnxA6 does not correlate with these lipids. The current study shows that AnxA6 is specifically reduced in human hepatocellular carcinoma suggesting a role of this protein in hepatocarcinogenesis.

Resolvin E1 and chemerin C15 peptide do not improve rodent non-alcoholic steatohepatitis.

Non-alcoholic steatohepatitis (NASH) is a progressive liver disease more commonly diagnosed in obesity. Therapeutic options to treat NASH are limited. Liver inflammation is a hallmark of NASH, and here it was tested whether the lipid mediator resolvin E1 (RvE1) and chemerin derived C15 peptide, which both exert potent anti-inflammatory activities, ameliorate NASH pathology. Male mice fed an atherogenic diet for 12 weeks, well described to induce NASH, received intraperitoneal injections of RvE1, C15 peptide or PBS as control for four days. Both treatments did not affect body weight or serum ALT. Liver triglycerides were neither reduced by the lipid nor the peptide. Hepatic expression of the macrophage marker F4/80 and the inflammatory mediators TNF and CCL2 was not changed. Further, fibrotic genes including TGFbeta, alphaSMA and CTGF were not affected by RvE1 or C15 injections. Serum adiponectin was comparable in the three groups. RvE1 and C15 are ligands of CMKLR1 whose expression was not reduced upon feeding the NASH inducing diet. This excludes low receptor levels as reason for therapeutic failure. In summary, current data demonstrate that RvE1 and chemerin derived C15 peptide do not ameliorate murine NASH.

Lipid abnormalities in alpha/beta2-syntrophin null mice are independent from ABCA1.

The syntrophins alpha (SNTA) and beta 2 (SNTB2) are molecular adaptor proteins shown to stabilize ABCA1, an essential regulator of HDL cholesterol. Furthermore, SNTB2 is involved in glucose stimulated insulin release. Hyperglycemia and dyslipidemia are characteristic features of the metabolic syndrome, a serious public health problem with rising prevalence. Therefore, it is important to understand the role of the syntrophins herein. Mice deficient for both syntrophins (SNTA/B2-/-) have normal insulin and glucose tolerance, hepatic ABCA1 protein and cholesterol. When challenged with a HFD, wild type and SNTA/B2-/- mice have similar weight gain, adiposity, serum and liver triglycerides. Hepatic ABCA1, serum insulin and insulin sensitivity are normal while glucose tolerance is impaired. Liver cholesterol is reduced, and expression of SREBP2 and HMG-CoA-R is increased in the knockout mice. Scavenger receptor-BI (SR-BI) protein is strongly diminished in the liver of SNTA/B2-/- mice while SR-BI binding protein NHERF1 is not changed and PDZK1 is even induced. Knock-down of SNTA, SNTB2 or both has no effect on hepatocyte SR-BI and PDZK1 proteins. Further, SR-BI levels are not reduced in brown adipose tissue of SNTA/B2-/- mice excluding that syntrophins directly stabilize SR-BI. SR-BI stability is regulated by MAPK and phosphorylated ERK2 is induced in the liver of the knock-out mice. Blockage of ERK activity upregulates hepatocyte SR-BI showing that increased MAPK activity contributes to low SR-BI. Sphingomyelin which is well described to regulate cholesterol metabolism is reduced in the liver and serum of the knock-out mice while the size of serum lipoproteins is not affected. Current data exclude a major function of these syntrophins in ABCA1 activity and insulin release but suggest a role in regulating glucose uptake, ERK and SR-BI levels, and sphingomyelin metabolism in obesity.