The wide spectrum of steatohepatitis: a report of four cases and a review of the literature

Pathogenesis and significance of hepatitis C virus steatosis: an update on survival strategy of a successful pathogen

Hepatitis C virus (HCV) is a successful pathogen on the grounds that it exploits its host's metabolism to build up viral particles; moreover it favours its own survival by inducing chronic disease and the development of specific anatomic changes in the infected organ. Steatosis, therefore, is associated with HCV infection by necessity rather than by chance alone. Approximately 6% of HCV patients have steatohepatitis. Interestingly, HCV steatosis occurs in the setting of multiple metabolic abnormalities (hyperuricemia, reversible hypocholesterolemia, insulin resistance, arterial hypertension and expansion of visceral adipose tissue) collectively referred to as "hepatitis C-associated dysmetabolic syndrome" (HCADS). General, nonalcoholic fatty liver disease (NAFLD)-like, mechanisms of steatogenesis (including increased availability of lipogenic substrates and de novo lipogenesis; decreased oxidation of fatty substrates and export of fatty substrates) are shared by all HCV genotypes. However, genotype 3 seemingly amplifies such steatogenic molecular mechanisms reported to occur in NAFLD via more profound changes in microsomal triglyceride transfer protein; peroxisome proliferator-activated receptor alpha; sterol regulatory element-binding proteins and phosphatase and tensin homologue. HCV steatosis has a remarkable clinical impact in as much as it is an acknowledged risk factor for accelerated fibrogenesis; for impaired treatment response to interferon and ribavirin; and development of hepatocellular carcinoma. Recent data, moreover, suggest that HCV-steatosis contributes to premature atherogenesis via both direct and indirect mechanisms. In conclusion, HCV steatosis fulfills all expected requirements necessary to perpetuate the HCV life cycle. A better understanding of the physiology of HCADS will likely result in a more successful handling of disease with improved antiviral success rates.

From NAFLD in clinical practice to answers from guidelines

This review of the literature consists of three sections. First, papers concerning non-alcoholic fatty liver disease (NAFLD) awareness among the general population, general practitioners, and liver and non-liver specialists were retrieved and analyzed to highlight the perception of disease, verify knowledge of current recommendations, and identify the main difficulties experienced in clinical practice. Next, position papers and clinical practice guidelines issued by International and National Hepatological Scientific Societies were identified and critically assessed in order to pinpoint the areas of convergence/difference. Finally, practical suggestions on NAFLD diagnosis and management in daily practice are provided and the open questions highlighted.

Review article: is non-alcoholic fatty liver disease a spectrum, or are steatosis and non-alcoholic steatohepatitis distinct conditions?

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is currently conceptualised as a clinical spectrum that results from a ‘multiple-hit’ process which begins with simple steatosis and subsequently renders the hepatocytes susceptible to a variety of insults. Ultimately, more serious liver injuries like non-alcoholic steatohepatitis (NASH) and cirrhosis may develop. Although the metabolic syndrome is considered the crucial player in the pathogenesis of NAFLD, recent studies have highlighted novel pathophysiological mechanisms in this clinical entity.

AIM

To discuss the pathophysiology of NAFLD based on the hypothesis that simple steatosis and NASH are discrete entities rather than two points on a spectrum.

METHODS

A literature search was conducted in August 2012 on PubMed, Ovid Embase, Ovid Medline and Scopus using the following search terms: steatosis, non-alcoholic steatohepatitis, pathophysiology, fatty liver, natural history and genetics.

RESULTS

Simple steatosis and NASH appear as two distinct pathophysiological entities and progression from pure fatty liver to NASH appears to be so rare as to warrant publication. The possible pathogenetic pathways specifically related to NASH are highlighted.

CONCLUSIONS

Although simple steatosis and non-alcoholic steatohepatitis are currently viewed as two histological subtypes of the unique spectrum of non-alcoholic fatty liver disease, the two conditions are likely distinct not only from a histological but also from a pathophysiological standpoint. Efforts to distinguish simple steatosis from non-alcoholic steatohepatitis using non-invasive modalities should be informed by the current pathophysiology of these two clinical entities.

Epidemiology of primary and secondary liver cancers

Primary liver cancer is the sixth most common cancer worldwide with a wide geographic distribution. The incidence of primary liver cancer is increasing and there is still a higher prevalence in developing countries. Early recognition remains an obstacle and lack of it results in poor outcomes for hepatocellular carcinoma (HCC), the most prevalent primary liver cancer, and cholangiocarcinoma. The most common risk factors associated with HCC are hepatitis B and chronic hepatitis C infections, alcohol use, smoking, and aflatoxin exposure. Emerging risk factors such as obesity might play an important role in the future because of the increasing prevalence of this condition.

Diagnostic challenges of nonalcoholic fatty liver disease (NAFLD) in children of normal weight

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is generally regarded as affecting the overweight or obese. Though previously reported, the notion that NAFLD occurs in the presence of normal body weight (adult BMI<25) is unfamiliar in adults and problematic in children. Normal-body-weight NAFLD accounts for approximately 15% of all NAFLD and may be more prevalent with certain ethnicities.

CASE

We describe a case of a child who appeared to have normal-body-weight NAFLD, on the basis of typical age of presentation, ultrasonographically evident hepatic steatosis and compatible liver histology, including a NAFLD activity score of 7, but was shown conclusively to have cystic fibrosis. Further we present a clinical strategy for diagnosis of childhood NAFLD, which would discriminate between this patient and actual normal-body-weight NAFLD children in our clinical practice.

CONCLUSION

NAFLD requires affirmative diagnostic criteria and should not be merely a diagnosis of exclusion.

Review article: hepatic steatosis and insulin resistance

Hepatic steatosis may be both an adaptive phenomenon and an example of lipotoxicity. Its prevalence ranks in the same order of magnitude of insulin resistance in the general population. Studies support the finding that hepatic steatosis is secondary to insulin resistance and not vice versa. A steatotic liver will further contribute to the development of insulin resistance through impaired clearance of insulin from the portal blood, creating a vicious cycle. Insulin resistance is the leading force in the pathogenesis and natural history of non-alcoholic fatty liver disease. Dysfunction of energetic homeostasis and the interaction of adiponectin, leptin and tumour necrosis factor-alpha are key events in the pathogenesis of steatosis and insulin resistance. Insulin resistance represents the frame within which hepatic and extrahepatic non-alcoholic fatty liver disease-related clinical manifestations are to be anticipated and interpreted.