Microbiota and Fatty Liver Disease-the Known, the Unknown, and the Future

The liver communicates with the intestine via the portal vein, biliary system, and mediators in the circulation. Microbes in the intestine maintain liver homeostasis but can also serve as a source of pathogens and molecules that contribute to fatty liver diseases. We review changes in the gut microbiota that can promote development or progression of alcohol-associated and non-alcoholic fatty liver disease-the most common chronic liver diseases in Western countries. We discuss how microbes and their products contribute to liver disease pathogenesis, putative microbial biomarkers of disease, and potential treatment approaches based on manipulation of the gut microbiota. Increasing our understanding of interactions between the intestinal microbiome and liver might help us identify patients with specific disease subtypes and select specific microbiota-based therapies.

Protective Mechanism of Edible Food Plants against Alcoholic Liver Disease with Special Mention to Polyphenolic Compounds

Alcoholic liver disease (ALD) is one type of liver disease, causing a global healthcare problem and mortality. The liver undergoes tissue damage by chronic alcohol consumption because it is the main site for metabolism of ethanol. Chronic alcohol exposure progresses from alcoholic fatty liver (AFL) to alcoholic steatohepatitis (ASH), which further lead to fibrosis, cirrhosis, and even hepatocellular cancer. Therapeutic interventions to combat ALD are very limited such as use of corticosteroids. However, these therapeutic drugs are not effective for long-term usage. Therefore, additional effective and safe therapies to cope with ALD are urgently needed. Previous studies confirmed that edible food plants and their bioactive compounds exert a protective effect against ALD. In this review article, we summarized the hepatoprotective potential of edible food plants and their bioactive compounds. The underlying mechanism for the prevention of ALD by edible food plants was as follows: anti-oxidation, anti-inflammation, lipid regulation, inhibition of apoptosis, gut microbiota composition modulation, and anti-fibrosis.

Precision medicine in alcoholic and nonalcoholic fatty liver disease via modulating the gut microbiota

Alcoholic liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD) represent a major health burden in industrialized countries. Although alcohol abuse and nutrition play a central role in disease pathogenesis, preclinical models support a contribution of the gut microbiota to ALD and NAFLD. This review describes changes in the intestinal microbiota compositions related to ALD and NAFLD. Findings from in vitro, animal, and human studies are used to explain how intestinal pathology contributes to disease progression. This review summarizes the effects of untargeted microbiome modifications using antibiotics and probiotics on liver disease in animals and humans. While both affect humoral inflammation, regression of advanced liver disease or mortality has not been demonstrated. This review further describes products secreted by Lactobacillus- and microbiota-derived metabolites, such as fatty acids and antioxidants, that could be used for precision medicine in the treatment of liver disease. A better understanding of host-microbial interactions is allowing discovery of novel therapeutic targets in the gut microbiota, enabling new treatment options that restore the intestinal ecosystem precisely and influence liver disease. The modulation options of the gut microbiota and precision medicine employing the gut microbiota presented in this review have excellent prospects to improve treatment of liver disease.

Update on the management of alcoholic steatohepatitis

Among heavy drinkers with liver disease, the development of severe alcoholic hepatitis (AH) is a serious complication. Prognosis is grave and associated with a high mortality due to liver failure, hepatorenal syndrome or intractable sepsis. Clinically, AH presents as a syndrome of progressive inflammatory liver injury in patients with recent or ongoing heavy alcohol consumption. Although approximately 20% of alcoholics undergoing liver biopsy reveal histological features of AH, only a minority progress to severe AH with markedly elevated serum liver enzymes, jaundice and impaired liver function. To establish the diagnosis of AH, histology is recommended but not mandatory. Prognostic scores include the Maddrey's discriminant function, the model of end-stage liver disease, the Glasgow Alcoholic Hepatitis score, and the ABIC score. While the former scores identify patients at risk of death or the need for corticosteroids, the response to corticosteroid therapy can be assessed using the Lille model. Treatments include abstinence and enteral nutrition, while pharmacotherapy using corticosteroids either with or without N-acetylcysteine may be indicated for patients with severe AH. Pentoxifylline was found to reduce the risk of hepatorenal syndrome, but data on mortality are limited. Although considered a contraindication in most transplant centers, recent evidence indicates that carefully selected patients with AH could be good candidates for liver transplantation with a prognosis comparable to other indications.

[Management of acute alcoholic steatohepatitis]

Alcoholic steatohepatitis is an acute inflammatory liver disorder that often complicates the course of underlying cirrhosis. Severe alcoholic steatohepatitis, defined as a Maddrey's discriminant function greater than 32 or association with hepatic encephalopathy, carries a high short-term mortality that is significantly reduced by corticosteroids. A comprehensive work-up is necessary for the presence of concomitant infection or associated viral hepatitis. A liver biopsy must be performed to confirm the diagnosis prior to initiation of steroids. This article summarizes the management of alcoholic steatohepatitis.

Nutrition in alcoholic steatohepatitis: more of the same or something new?

PURPOSE OF REVIEW

To describe the evidences for and against the different nutritional and nonnutritional therapeutic approaches for severe alcoholic steatohepatitis, based on data from randomized controlled trials, in order to answer the question posed in the title: 'more of the same or something new?'.

RECENT FINDINGS

Very few papers assessing old or new therapeutic strategies for severe alcoholic steatohepatitis have been published in the last 18 months. In addition, all of them provide negative results. A meta-analysis of the trials using anabolic steroids in alcoholic steatohepatitis confirmed the lack of benefit associated with this therapy. Also, two randomized controlled trials failed to disclose any positive effect of different antioxidant mixture in these patients.

SUMMARY

The answer to the question posed in the title of this review must unfortunately be 'nothing new, but just the same!'.

[Non-alcoholic fatty liver disease and non-alcoholic steatohepatitis]

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are the hepatic manifestations of the metabolic syndrome. Since the prevalence of obesity and consequently of the metabolic syndrome is steadily increasing, the different types of NAFLD are nowadays the most common cause of liver injury in North America. The development of NASH and fatty liver cirrhosis occurs after a "two-hit-theory", in which hepatic steatosis is followed by lipid peroxidation, the production of cytokines and the induction of Fas ligand. A standardized drug based therapy does not exist so far, but glitazones have emerged as a promising treatment option. However, since the disease is related to Western lifestyle, treatment should be based on prevention and changes in lifestyle.

Sonografische Verlaufsbeurteilung der alkoholischen Fettleber durch untersucherbezogene und digitale Analyse der Echogenität des Binnenreflexmusters

BACKGROUND

The reversibility of alcoholic fatty liver is well-known. The present study aims to investigate whether sonographic controls can document this reversibility under abstinence therapy with respect to inter-observer variability.

METHODS

59 male patients with alcohol dependency were examined by ultrasound at the beginning and the end of a long-term in-patient withdrawal therapy. Fatty liver was graded qualitatively (no, slight, moderate and severe fatty liver). The sonographic liver sections were registered digitally per examination and were subsequently evaluated by means of the PC by two independent experts. Additionally, a digital texture analysis of representative hepatic and renal regions was performed. The pixel intensity ratio of liver and kidney was used as a measure of liver echogenicity.

RESULTS

In the ultrasound examination, the 59 patients had the following severity grade of fatty liver initially: 18 (31 %) severe, 19 (32 %) moderate, 22 (37 %) slight. 37 patients (63 %) showed sonographically an improvement of the initial severity grade within 79 +/- 26 days (p < 0.0001, 95 % confidence interval: 50 - 74 %). The evaluation by the independent experts revealed 47 and 54 % improvement, respectively. The overall degree of agreement between the 3 ratings concerning grading and course was high (intraclass coefficient = 0.896). However, there was a marked deviation between the several grading levels (agreement 15 - 86 %). The categorical differentiation between no/slight versus moderate/severe fatty liver revealed an agreement of between 81 and 91 %. The mean pixel intensity ratio showed an improvement of 17 % (p < 0.0001).

CONCLUSIONS

After 3 months abstinence an improvement of alcoholic fatty liver can be consistently documented in about 50 % of the cases by sonography. The interobserver variability on differentiating no/slight versus moderate/severe fatty liver was low. The digital texture analysis confirmed the range of reversibility and could play a role in quantifying the sonographic degree of fatty infiltration.

Alcoholic and nonalcoholic forms of fatty liver disease

Fatty liver (or steatosis) is an increasingly common finding in histolgical evaluation of liver biopsies. It is frequently associated with obesity, diabetes, metabolic syndromes, and/or alcohol abuse. When the steatosis is accompanied by inflammation and fibrosis, the risk of progression to severe liver disease is high. The aim of this paper is to review the clinical features, pathophysiology, natural history, and options for the treatment of nonalcoholic and alcoholic forms of fatty liver disease.

Alcoholic steatohepatitis: management and prognosis

Alcoholic hepatitis is a disease with a wide range of severity. Patients with severe disease have short-term mortality rates above 35%. In these high-risk patients, pharmacologic therapy is an important adjunct to supportive medical care and has been proved to improve survival. Given the benefit of drug treatment, it is important to identify patients at risk of early mortality from alcoholic hepatitis. A number of validated scoring systems are useful for this purpose, including the Maddrey Discriminant Function, the Model of End-Stage Liver Disease score, and the Glasgow Alcoholic Hepatitis score. Patients judged by one or more of these criteria to have severe alcoholic hepatitis should be treated with corticosteroids or pentoxifylline, provided they have no contraindications for this treatment. Adequate nutrition is also critical and should be provided by tube feeding if necessary. A prompt decline in serum bilirubin indicates a favorable response to therapy. Patients who do not exhibit a reduction in serum bilirubin within 1 week are considered nonresponders and have a 6-month mortality rate of 50% or higher.

Sake yeast suppresses acute alcohol-induced liver injury in mice

Brewer's and baker's yeasts appear to have components that protect from liver injury. Whether sake yeast, Saccharomyces cerevisiae Kyokai no. 9, also has a hepatoprotective effect has not been examined. Here we show that sake yeast suppresses acute alcoholic liver injury in mice. Male C57BL/6 mice that had been fed a diet containing 1% sake yeast for two weeks received three doses of ethanol (5 g/kg BW). In the mice fed sake yeast, ethanol-induced increases in triglyceride (TG) and glutamate pyruvate transaminase (GPT) were significantly attenuated and hepatic steatosis was improved. In addition, sake yeast-fed mice showed a smaller decrease in hepatic S-adenosylmethionine (SAM) level and a smaller increase in plasma homocysteine (Hcy) level after ethanol treatment than the control mice, suggesting that a disorder of methionine metabolism in the liver caused by ethanol was relieved by sake yeast. These results indicate that sake yeast protects against alcoholic liver injury through maintenance of methionine metabolism in the liver.

Therapieoptionen für die nicht-alkoholinduzierte Fettleber und Fettleberhepatitis

Nonalcoholic fatty liver disease (NAFLD) is increasingly recognized as one of the most common causes of chronic liver damage in the western world. It is strongly associated with insulin resistance, obesity and other features of the metabolic syndrome. The entity NAFLD embraces a clinical spectrum from benign steatosis over steatohepatitis to hepatic cirrhosis with its complications liver failure and hepatocellular carcinoma. Treatment is currently based on prescriptive diet and physical exercise. A well-defined pharmacotherapy of NAFLD still remains to be established due to the lack of randomized, controlled trials. Yet, for several drugs such as Metformin and Thiazolidinediones, smaller trials report promising results.

Nonalcoholic fatty liver disease: a review of current understanding and future impact

Nonalcoholic fatty liver disease (NAFLD), already the most common form of liver disease in the United States, can be expected to increase in prevalence and severity in parallel with national epidemics of obesity and type 2 diabetes. NAFLD is frequently associated with insulin resistance. While insulin resistance, and thereby hyperinsulinemia, are, in large part, metabolic consequences of obesity, the basis of diversity in severity and progression of inflammation and fibrosis is not known. Increased susceptibility to oxidative stress is likely to play a role. Several patient characteristics have been associated with more severe histological findings in patients with NAFLD, including type 2 diabetes, hypertension, age over 40 years, and higher transaminases. Liver biopsy is, however, required to accurately grade and stage NAFLD histologically. Although the natural history of NAFLD is relatively poorly defined, NAFLD is increasingly recognized as an important cause of decompensated liver disease. Weight reduction and improved insulin sensitivity are associated with improved biochemical and histological parameters of NAFLD. There are, however, no proven safe and efficacious pharmacological treatments for NAFLD.

[Alcoholic and non-alcoholic steatohepatitis]

Chronic aethylism has always been a major social as well as health problem. It may lead, at least in some patients, to steatohepatitis (ASH) which is known to progress to cirrhosis more rapidly. Because of the fact that the prevalence of obesity in association with the metabolic syndrome (insulin resistance) is strikingly increasing in the Western world, we will more and more often be faced with a second form of steatohepatitis, the so called non-alcoholic steatohepatitis (NASH). Clinical differentiation between these two entities may often be difficult. The use of the CAGE-questions as well as interviewing family members can help to indentify hidden alcohol abuse. Clinically, the presence of both diseases can only be speculated. To get the diagnosis, liver biopsy must be performed to show the typical histologic feature of fatty liver with hepatocyte necrosis as well as infiltration of polymorphcellular leukocytes. Histology cannot differentiate between ASH and NASH. Therefore, similar pathogenetic mechanisms are supposed. However, therapeutic approaches are different. Treatment of choice in ASH is alcohol abstinence, that of NASH the reduction of insulin resistance, primarily by weight loss.

Hepatocyte apoptosis, expression of death receptors, and activation of NF-kappaB in the liver of nonalcoholic and alcoholic steatohepatitis patients

OBJECTIVES

The increasing incidence of nonalcoholic (NASH) and alcoholic steatohepatitis (ASH), associated with lack of effective treatment, has prompted intensive studies on disease pathogenesis. Apoptosis is recognized as common in liver injury and may also contribute to tissue inflammation, fibrogenesis, and development of cirrhosis. In this study, we identified mechanisms of apoptosis induction in human steatohepatitis, and evaluated potential associations between apoptosis, liver pathology, and clinical presentation in NASH and ASH.

METHODS

Hepatocyte apoptosis was evaluated by the TUNEL assay in 20 patients with NASH (all ambulatory), 40 with ASH (20 ambulatory, 20 hospitalized), and 20 controls. Liver biopsies were also graded for inflammation and fibrosis. Immunohistochemistry was performed for death receptors (Fas and TNF-R1), activated caspase-3, NF-kappaB p65, antiapoptotic Bcl-2 protein, and uncoupling protein 2 (UCP-2).

RESULTS

TUNEL-positive hepatocytes were markedly increased in NASH (p < 0.05) and ASH (p < 0.01). Similar results were obtained for activated caspase-3, confirming the occurrence of apoptosis. The Fas receptor was upregulated in ASH, especially in hospitalized patients (p < 0.01), whereas TNF-R1 was expressed both in NASH and ASH (p < 0.01). In addition, patients with ASH showed a remarkable expression of active NF-kappaB, as compared to NASH and controls (p < 0.01). Degrees of inflammation and fibrosis correlated with NF-kappaB p65 expression, which in turn coincided with apoptosis albeit Bcl-2 and UCP-2 expression.

CONCLUSIONS

Liver injury in NASH and ASH is associated with increased hepatocyte apoptosis mediated by death receptors. Further, apoptosis correlates with active NF-kappaB expression, and disease severity. This potential mechanistic link might provide multiple interesting targets for therapeutic intervention.

Emerging indications for MARS dialysis

MARS stands for Molecular Adsorbent Recirculating System and represents an interesting option in treating patients with liver disease. There is still little known about the best time point of initiating this treatment and the exact selection criteria for patients who may benefit from this therapy. The list of potential applications using this procedure is expanding. We report on the experience in seven patients being treated with MARS dialysis for chronic cholestatic liver disease and acute on chronic liver failure. From August 2000 to October 2001 seven patients received 27 MARS treatments in our clinic, ranging from 2 to 12 treatments per subject. Presented cases were diagnosed as steatohepatitis because of alcoholism (n = 3), vanishing bile duct disease (n = 1), metabolic liver disease (n = 1), primary biliary cirrhosis (n = 1) and drug-induced hepatitis (n = 1). Based on this experience, we discuss the ongoing questions of various indications and the decision to initiate MARS dialysis.

Alcoholic steatosis and steatohepatitis

Hepatic steatosis and steatohepatitis are encountered with great frequency in people who consume large amounts of ethanol (more than 6 drinks per day). Ethanol causes steatosis by altering several steps in the hepatic processing of fatty acids, including their uptake from plasma, their use as fuel substrates, and their export as triglyceride. When clinically mild, alcoholic steatosis and steatohepatitis can be difficult to distinguish from nonalcoholic fatty liver disease. This is particularly true among individuals at high risk of accelerated alcoholic liver injury, such as women, the obese, and those with hepatitis C. In the outpatient setting, history and aspartate aminotransferase:alanine aminotransferase ratio offer the best clues to diagnosis. Liver biopsy cannot determine the cause of steatohepatitis, but can show the extent of disease. The etiology of disease is important to prognosis, as alcoholic fatty liver carries a much higher risk of progression and mortality than nonalcoholic fatty liver disease. Patients with moderate to severe alcoholic steatohepatitis are typically hospitalized. Derangements in white blood cell count, prothrombin time, and bilirubin identify those with the highest early mortality. Survival in this severely ill subgroup is improved with the short-term use of corticosteroids; patients who have contraindications to steroids may benefit from other forms of therapy, either pharmacologic, nutritional, or both.

Alcoholic liver injury: pathogenesis and therapy in 2001

Much progress has been made in the understanding of the pathogenesis of alcoholic liver disease, resulting in improvement of prevention and promising prospects for even more effective treatments. It continues to be important to replenish nutritional deficiencies when present but it is crucial to recognize that, because of the alcohol-induced disease process, some of the nutritional requirements change. For instance, methionine, one of the essential amino acids for humans, must be activated to SAMe but, in severe liver disease, the activity of the corresponding enzyme is depressed. Therefore, the resulting deficiencies and associated pathology can be attenuated by the administration of SAMe, but not by methionine. Similarly, phosphatidylethanolamine methyltransferase (PEMT) activity, which is important for hepatic phosphatidylcholine (PC) synthesis, is also depressed in alcoholic liver disease, therefore calling for administration of the products of the reaction. It might also be beneficial to add other compounds to such therapeutic regiment. Since free radical generation by the ethanol-induced CYP2E1 plays a key role in the oxidative stress, inhibitors of this enzyme have great promise. Several have been investigated experimentally and PPC is particularly interesting because of its innocuity. In view of the striking negative interaction between alcoholic liver injury and hepatitis C, an antiviral agent is eagerly awaited that, unlike Interferon, is not contraindicated in the alcoholic. Anti-inflammatory agents are also required. In addition to down-regulators of cytokines and end toxic are being considered. Finally, since excess drinking is the crux of the issue, anticraving agents should be incorporated in any contemplated therapeutic cocktail, in view of the recent promising results obtained with some of these agents such as naltrexone and acamprosate.

[Treatment of alcoholic liver diseases. Abstinence, nutritional support, drug therapy, liver transplantation]

The review summarizes clinically established treatment forms of alcoholic liver disease in four main chapters: abstinence, nutritional supportation, drug therapy and liver transplantation are discussed. Drug therapy is described according to the three types of alcoholic hepatopathies (fatty liver, hepatitis and cirrhosis). Early diagnosis and treatment depending on the severity and stage of alcoholic liver disease are of importance for the attempts to retard progression and improve prognosis.

Fatty liver--current look at the old disease

The report is devoted to the presentation of aetiological factors causing fatty liver, including alcohol, obesity, diabetes mellitus, hyperlipoproteinaemias and drugs. The author discusses morphological changes typical for the fatty liver such as large or small fatty droplets in hepatocytes and rarely coexisting hepatitis (so-called steatohepatitis). The work presents symptoms, changes in biochemical analyses of serum as well as methods of the liver visualisation used in the diagnostics of fatty liver. The treatment in based on the elimination of aetiological factors and properly balanced diet with support of pharmacotherapy in selected cases.

[Steatosis and fibrosis: first stage of liver damage induced by chronic alcoholism. Our experience in 100 cases]

Having briefly analyzed the metabolism of ethanol in man, the author describes hepatocellular damage induced by alcohol abuse and histological, clinical and biohumoral features of steatosis and fibrosis. One hundred clinical cases of hepatic steatosis and fibrosis are also illustrated, studied and observed during five years.

[Is there a therapeutic effect of cures undergone by patients with chronic liver disease? (authors transl)]

"Cures" embrace by definition a broad spectrum starting from taking waters in health resorts to hospital treatment in modern rehabilitation centers. The effectiveness of traditional cure procedures is discussed. Effectiveness of drinking cures, baths and mud packs in liver disease has not yet been proven. Controlled trials are necessary. Clinical treatment is indicated in alcoholic liver damage, viral hepatitis with a protracted course, chronic aggressive hepatitis and compensated cirrhosis of the liver; such treatment, however, is questionable in fatty liver and in chronic persistent hepatitis. Data concerning the effectiveness of treatment of chronic liver diseases are given. The following conclusions are drawn: patients with liver disease ought to be hospitalized when undergoing cures, indications have to be precised, collaboration of patients has to be stimulated, hospital discipline has to be tight, therapy of alcoholism has to include several psychosocial aspects, treatment after leaving hospital has to be improved.