F. Stickel

Integrin αvβ6 is a marker of the progression of biliary and portal liver fibrosis and a novel target for antifibrotic therapies

BACKGROUND/AIMSnThe integrin alphavbeta6 promotes proliferation of specialized epithelia and acts as a receptor for the activation of latent TGFbeta1. We studied alphavbeta6 expression in experimental and human liver fibrosis and the potential of its pharmacological inhibition for treatment of hepatic fibrosis.nnnMETHODSnalphavbeta6 expression was studied by quantitative PCR and immunohistochemistry in rats with cirrhosis due to bile duct ligation (BDL), administration of thioacetamide (TAA), in Mdr2(Abcb4)(-/-) mice with spontaneous biliary fibrosis, and in livers of patients with chronic hepatitis C (n=79) and end-stage liver disease due to various etiologies (n=18). The effect of a selective alphavbeta6 inhibitor was evaluated in Mdr2(Abcb4)(-/-) mice with ongoing fibrogenesis.nnnRESULTSnIntegrin beta6 mRNA increased with fibrosis stage in hepatitis C and was upregulated between 25- and 100-fold in TAA- and BDL-induced cirrhosis, in Mdr2(Abcb4)(-/-) mice and in human end-stage liver disease. alphavbeta6 protein was absent in normal livers and expressed de novo on (activated) bile duct epithelia and transitional hepatocytes. A single dose of the alphavbeta6 inhibitor injected into Mdr2(Abcb4)(-/-) mice significantly induced profibrolytic matrix metalloproteinases (MMP)-8 and -9 after 3 h, with a corresponding increase in extracellular matrix-degrading activities. In parallel profibrogenic transcripts (procollagen alpha1(I), TGFbeta2, and MMP-2) showed a trend of downregulation.nnnCONCLUSIONSn(1) Integrin alphavbeta6 is induced de novo in rodent and human liver fibrosis, where it is expressed on activated bile duct epithelia and (transitional) hepatocytes during fibrosis progression. (2) In vivo a single dose of a small molecule alphavbeta6 inhibitor induced antifibrogenic and profibrolytic genes and activities, suggesting alphavbeta6 is a unique target for treatment of liver fibrosis.

Hepatotoxicity of botanicals.

OBJECTIVEnHepatic impairment resulting from the use of conventional drugs is widely acknowledged, but there is less awareness of the potential hepatotoxicity of herbal preparations and other botanicals, many of which are believed to be harmless and are commonly used for self-medication without supervision. The aim of this paper is to examine the evidence for hepatotoxicity of botanicals and draw conclusions regarding their pathology, safety and applications.nnnDESIGNnCurrent literature on the hepatotoxicity of herbal drugs and other botanicals is reviewed. The aetiology, clinical picture and treatment of mushroom (Amanita) poisoning are described.nnnRESULTSnHepatotoxic effects have been reported for some Chinese herbal medicines (such as Jin Bu Huan, Ma-Huang and Sho-saiko-to), pyrrolizidine alkaloid-containing plants, germander (Teucrium chamaedrys), chaparral (Larrea tridentata), Atractylis gummifera, Callilepsis laureola, and others. The frequency with which botanicals cause hepatic damage is unclear. There is a lack of controlled treatment trials and the few studies published to date do not clarify the incidence of adverse effects. Many plant products do not seem to lead to toxic effects in everyone taking them, and they commonly lack a strict dose-dependency. For some products, such as Sho-saiko-to, the picture is confused further by demonstrations of hepatoprotective properties for some components. Mushroom poisoning is mostly due to the accidental consumption of Amanita species. Treatment with silymarin, thioctic acid, penicillin and liver transplantation have been shown to be effective but require early diagnosis.nnnCONCLUSIONSnSevere liver injury, including acute and chronic abnormalities and even cirrhotic transformation and liver failure, has been described after the ingestion of a wide range of herbal products and other botanical ingredients, such as mushrooms. It is concluded that in certain situations herbal products may be just as harmful as conventional drugs.

Alcohol and cancer: genetic and nutritional aspects

Chronic alcohol consumption is a major risk factor for cancer of upper aero-digestive tract (oro-pharynx, hypopharynx, larynx and oesophagus), the liver, the colo-rectum and the breast. Evidence has accumulated that acetaldehyde is predominantly responsible for alcohol-associated carcinogenesis. Acetaldehyde is carcinogenic and mutagenic, binds to DNA and protein, destroys the folate molecule and results in secondary cellular hyper-regeneration. Acetaldehyde is produced by mucosal and cellular alcohol dehydrogenase, cytochrome P450 2E1 and through bacterial oxidation. Its generation and/or its metabolism is modulated as a result of polymorphisms or mutations of the genes responsible for these enzymes. Acetaldehyde can also be produced by oral bacteria. Smoking, which changes the oral bacterial flora, also increases salivary acetaldehyde. Cigarette smoke and some alcoholic beverages, such as Calvados, contain acetaldehyde. In addition, chronic alcohol consumption induces cytochrome P450 2E1 enxyme activity in mucosal cells, resulting in an increased generation of reactive oxygen species and in an increased activation of various dietary and environmental carcinogens. Deficiencies of riboflavin, Zn, folate and possibly retinoic acid may further enhance alcohol-associated carcinogenesis. Finally, methyl deficiency as a result of multiple alcohol-induced changes leads to DNA hypomethylation. A depletion of lipotropes, including methionine, choline, betaine and S-adenosylmethionine, as well as folate, results in the hypomethylation of oncogenes and may lead to DNA strand breaks, all of which are associated with increased carcinogenesis.

The efficacy and safety of comfrey.

Herbal medication has gathered increasing recognition in recent years with regard to both treatment options and health hazards. Pyrrolizidine alkaloids have been associated with substantial toxicity after their ingestion as tea and in the setting of contaminated cereals have led to endemic outbreaks in Jamaica, India and Afghanistan. In Western Europe, comfrey has been applied for inflammatory disorders such as arthritis, thrombophlebitis and gout and as a treatment for diarrhoea. Only recently was the use of comfrey leaves recognized as a substantial health hazard with hepatic toxicity in humans and carcinogenic potential in rodents. These effects are most likely due to various hepatotoxic pyrrolizidine alkaloids such as lasiocarpine and symphytine, and their related N-oxides. The mechanisms by which toxicity and mutagenicity are conveyed are still not fully understood, but seem to be mediated through a toxic mechanism related to the biotransformation of alkaloids by hepatic microsomal enzymes. This produces highly reactive pyrroles which act as powerful alkylating agents. The main liver injury caused by comfrey (Symphytum officinale) is veno-occlusive disease, a non-thrombotic obliteration of small hepatic veins leading to cirrhosis and eventually liver failure. Patients may present with either acute or chronic clinical signs with portal hypertension, hepatomegaly and abdominal pain as the main features. Therapeutic approaches include avoiding intake and, if hepatic failure is imminent, liver transplantation. In view of the known serious hazards and the ban on distributing comfrey in Germany and Canada, it is difficult to understand why comfrey is still freely available in the United States.

Nutritional therapy in alcoholic liver disease

Chronic alcohol consumption may lead to primary and secondary malnutrition. In particular, protein energy malnutrition not only aggravates alcoholic liver disease but also correlates with impaired liver function and increased mortality. Therefore, in these patients, adequate nutritional support should be implemented in order to improve their prognosis. Clinical trials addressing this issue have shown that nutritional therapy either enterally or parenterally improves various aspects of malnutrition, and there is increasing evidence that it may also improve survival. Therefore, malnourished alcoholics should be administered a diet rich in carbohydrate‐ and protein‐derived calories preferentially via the oral or enteral route. Micronutrient deficiencies typically encountered in alcoholics, such as for thiamine and folate, require specific supplementation. Patients with hepatic encephalopathy may be treated with branched‐chain amino acids in order to achieve a positive nitrogen balance. Fatty liver represents the early stage of alcoholic liver disease, which is usually reversible with abstinence. Metadoxine appears to improve fatty liver but confirmatory studies are necessary. S‐adenosyl‐l‐methionine may be helpful for patients with severe alcoholic liver damage, since various mechanisms of alcohol‐related hepatotoxicity are counteracted with this essential methyl group donor, while a recent large trial showed that the use of polyenylphosphatidylcholine is of limited efficacy.

Acute Hepatitis Induced by Greater Celandine (Chelidonium majus)

We report on two cases of acute liver injury along with the intake of Greater Celandine (Chelidonium majus), a well-known herbal remedy frequently used for irritable bowel syndrome. All other possible causes of acute liver damage were excluded in both patients. In one patient, cholestatic hepatitis recurred rapidly after involuntary re-exposition. Both patients fully recovered after the withdrawal of Greater Celandine. The two cases add to the existing database about the potential hepatotoxicity of drugs containing Greater Celandine and raise the question whether the approval of this drug should be re-evaluated in the light of lacking evidence for a therapeutic benefit.

Pathogenetic mechanisms of upper aerodigestive tract cancer in alcoholics

Chronic excessive alcohol consumption is the strongest risk factor for upper aerodigestive tract (UADT) cancer (oral cavity, pharynx, hypopharynx, larynx, esophagus).1 In addition, alcohol also increases the risk for cancer of the liver, colorectum and breast.1 A great number of epidemiological studies have demonstrated a correlation between alcohol ingestion and the occurrence of cancer in these organs.1–9 These studies clearly show that the ingestion of all types of alcoholic beverages is associated with an increased cancer risk that suggests that ethanol itself is the crucial compound that causes that effect. The exact mechanism(s) of ethanol-associated carcinogenesis has remained obscure because ethanol by itself when given to animals is not carcinogenic.10 Multiple mechanisms are involved in alcohol-associated cancer development of the UADT including the effect of acetaldehyde (AA), the first metabolite of ethanol oxidation, induction of cytochrome P-4502E1 (CYP2E1) leading to the generation of reactive oxygen species (ROS) and enhanced procarcinogen activation, modulation of cellular regeneration and nutritional deficiencies. In our minireview, major emphasis is laid on more recent developments including genetic aspects of ethanol metabolism, bacterial alcohol oxidation and nutritional deficiencies.

Serum collagen type VI and XIV and hyaluronic acid as early indicators for altered connective tissue turnover in alcoholic liver disease.

Hepatic fibrosis in alcoholic liver disease often heralds progression to cirrhosis and, therefore, noninvasive parameters are required for early diagnosis and follow-up. Collagens VI and XIV, procollagen-III-N-propeptide, hyaluronic acid, and active transforming growth factor-β1 (TGF-β1) were measured in healthy volunteers, patients with alcoholic cirrhosis, and heavy drinkers without cirrhosis. Noncirrhotic alcoholics were assigned to two groups with either normal aspartate aminotransferase or levels ≥2 normal. Collagens VI and XIV were elevated in all alcoholic patients compared to controls (P < 0.0001, all instances). Procollagen-III-N-propeptide and hyaluronic acid levels were higher in alcoholic patients with elevated liver enzymes and in cirrhotics as compared to controls. Procollagen-III-N-propeptide revealed a significant correlation with serum levels of TGF-β1(P < 0.0001). Collagens VI, and XIV, procollagen-III-N-propeptide, and hyaluronic acid appear to be sensitive markers indicating fibrotic transformation in alcoholics. The correlation between procollagen-III-N-propeptide and TGF-β1 emphasizes its role in hepatic fibrogenesis.

Non-coding keratin variants associate with liver fibrosis progression in patients with hemochromatosis.

Background Keratins 8 and 18 (K8/K18) are intermediate filament proteins that protect the liver from various forms of injury. Exonic K8/K18 variants associate with adverse outcome in acute liver failure and with liver fibrosis progression in patients with chronic hepatitis C infection or primary biliary cirrhosis. Given the association of K8/K18 variants with end-stage liver disease and progression in several chronic liver disorders, we studied the importance of keratin variants in patients with hemochromatosis. Methods The entire K8/K18 exonic regions were analyzed in 162 hemochromatosis patients carrying homozygous C282Y HFE (hemochromatosis gene) mutations. 234 liver-healthy subjects were used as controls. Exonic regions were PCR-amplified and analyzed using denaturing high-performance liquid chromatography and DNA sequencing. Previously-generated transgenic mice overexpressing K8 G62C were studied for their susceptibility to iron overload. Susceptibility to iron toxicity of primary hepatocytes that express K8 wild-type and G62C was also assessed. Results We identified amino-acid-altering keratin heterozygous variants in 10 of 162 hemochromatosis patients (6.2%) and non-coding heterozygous variants in 6 additional patients (3.7%). Two novel K8 variants (Q169E/R275W) were found. K8 R341H was the most common amino-acid altering variant (4 patients), and exclusively associated with an intronic KRT8 IVS7+10delC deletion. Intronic, but not amino-acid-altering variants associated with the development of liver fibrosis. In mice, or ex vivo, the K8 G62C variant did not affect iron-accumulation in response to iron-rich diet or the extent of iron-induced hepatocellular injury. Conclusion In patients with hemochromatosis, intronic but not exonic K8/K18 variants associate with liver fibrosis development.

413 INCREASED LIVER STIFFNESS IN ALCOHOLIC LIVER DISEASE: DISSECTING FIBROSIS FROM STEATOHEPATITIS

413 INCREASED LIVER STIFFNESS IN ALCOHOLIC LIVER DISEASE: DISSECTING FIBROSIS FROM STEATOHEPATITIS S. Mueller, G. Millonig, S. Friedrich, F. Stickel, T. Longerich, P. Schirmacher, H.-K. Seitz. Center for Alcohol Research and Salem Medical Center, University of Heidelberg, Heidelberg, Germany; Clinical Pharmacology, University of Bern, Bern, Switzerland; Institute of Pathology, University of Heidelberg, Heidelberg, Germany E-mail: sebastian.mueller@urz.uni-heidelberg.de