Diagnosis and therapy of nonalcoholic steatohepatitis

Non-invasive diagnosis of steatosis and fibrosis

The prognosis and management of liver disease greatly depends on the amount of liver fibrosis. Non-alcoholic fatty liver disease (NAFLD), ranging from simple steatosis to non-alcoholic steatohepatitis (NASH), is emerging as a major cause of liver disease in Western countries because of the increasing prevalence of obesity and type 2 diabetes. A key issue in patients with NAFLD is the differentiation of NASH from simple steatosis. It is particularly important to identify NASH patients as they are at greatest risk of developing complications such as cirrhosis, liver failure and hepatocellular carcinoma. The limitations of liver biopsy (invasive procedure, sampling errors, interobserver variability and non-dynamic fibrosis evaluation) have stimulated the search for non-invasive approaches for the assessment of steatosis and liver fibrosis in patients with NAFLD. A variety of methods, including serum markers, imaging techniques such as ultrasound, CT, MRI and measurement of liver stiffness by transient elastography, have been proposed for the non-invasive assessment of steatosis and hepatic fibrosis. This review discusses the advantages and limitations of these different methods in clinical practice.

Management of chemotherapy-associated hepatotoxicity in colorectal liver metastases

Effective systemic drugs are increasingly used to treat patients with colorectal liver metastases. Recent trials have shown that chemotherapy can reduce the size of metastases that are unresectable rendering them resectable, and decrease postoperative recurrence rates in patients with initially resectable tumours. The increasing use of chemotherapy for colorectal liver metastases has raised awareness of the potential hepatotoxicities induced by systemic drugs and the effects of these drugs on outcome after hepatic resection. In this Review, we outline the rationale for the use of perioperative chemotherapy for colorectal liver metastases, associations between specific agents and patterns of liver injury, and strategies to treat patients with suspected or known chemotherapy-associated hepatotoxicity.

Prevention of steatohepatitis by pioglitazone: implication of adiponectin-dependent inhibition of SREBP-1c and inflammation

BACKGROUND/AIMS

Peroxisome proliferator-activated receptor gamma (PPARgamma) agonist drugs, like pioglitazone (PGZ), are proposed as treatments for steatohepatitis. Their mechanisms of action remain ill-clarified.

METHODS

To test the hypothesis that PGZ improves steatohepatitis through adiponectin-dependent stimulation of AMPK and/or PPARalpha, mice lacking adiponectin (Adipo(-/-)) or the AMPKalpha1 catalytic subunit (AMPKalpha1(-/-)) or wild-type (Wt) mice were fed the methionine and choline deficient (MCD) diet, supplemented or not with PGZ.

RESULTS

In Wt mice, PGZ increased circulating levels of adiponectin and reduced the severity of MCD-induced steatohepatitis but there was no evidence of activation of AMPK or PPARalpha and their downstream targets. By contrast, PGZ completely repressed nuclear translocation of SREBP-1c, a key transcription factor for de novo lipogenesis. This effect was lacking in Adipo(-/-) mice in which PGZ failed to prevent steatohepatitis. Surprisingly, AMPKalpha1(-/-) mice were resistant to MCD-induced steatohepatitis, a status also associated with repression of SREBP-1c.

CONCLUSIONS

The preventive effect of PGZ on MCD-induced steatohepatitis depends on adiponectin upregulation but apparently does not involve AMPK or PPARalpha activation. The inhibition of SREBP-1c and dependent repression of lipogenesis are likely to participate in this effect. The mechanisms by which PGZ and adiponectin control SREBP-1c and inflammation remain to be elucidated.

Risk factors for chemotherapy-associated liver injuries: A multivariate analysis of a group of 146 patients with colorectal metastases

BACKGROUND

Chemotherapy for colorectal liver metastases (CLM) may be associated with pathologic changes to the liver parenchyma, possibly increasing the risk of surgery. The aim of this study was to determine the risk factors for chemotherapy-associated liver injuries (CALI).

METHODS

From 1998 to 2006, 146 patients underwent a liver resection for CLM within 3 months of preoperative chemotherapy. CALI were defined as follows: steatosis > or =30%, or steatohepatitis, or moderate or severe sinusoidal lesions. Univariate and multivariate analysis were used to examine the relationship between CALI and 36 other preoperative factors.

RESULTS

Pathologic examination showed CALI in 74/146 patients (51%), including sinusoidal lesions (n = 50), steatosis > or = 30% (n = 32), and steatohepatitis (n = 15). Twenty-three patients had overlapping CALI. In multivariate analysis, BMI > 27 (P = .002), hyperglycemia > 7 mmol/l (P = .006), and an interval between chemotherapy and surgery < 4 weeks (P = .011) were independent risk factors for CALI, whereas aspirin intake was associated with reduced risk of CALI (P = .002). In multivariate analysis, synchronous metastases (P = .015), unresectable liver metastases at diagnosis (P = .034), GGT plasma level > 1.5N (P = .028), and oxaliplatin-based chemotherapy (P < .01) were risk factors for sinusoidal lesions. Aspirin intake was associated with reduced risk for sinusoidal lesions (P = .03). In multivariate analysis, BMI > 27 (P = .026) was the only risk factor for steatosis or steatohepatitis.

CONCLUSION

In patients with CLM, there are few preoperative risk factors for CALI. In patients treated by oxaliplatin-based chemotherapy, aspirin intake appears to be associated with a reduced risk of sinusoidal lesions and should be tested in a randomized phase II study.

Nonalcoholic fatty liver disease and nonalcoholic steatohepatitis: Selected practical issues in their evaluation and management

Nonalcoholic fatty liver disease (NAFLD) is among the most common causes of chronic liver disease in the western world. It is now recognized that these patients have myriad of important co-morbidities (e.g., diabetes, hypothyroidism and metabolic syndrome). The workup of patients with suspected NAFLD should consist of excluding competing etiologies and systemic evaluation of metabolic comorbidities. NAFLD is histologically categorized into steatosis and steatohepatitis, two states with fairly dichotomous natural history. While significant progress has been made in terms of noninvasively predicting advanced fibrosis, insufficient progress has been made in predicting steatohepatitis. Currently, liver biopsy remains the gold standard for the histological stratification of NAFLD. While sustained weight loss can be effective to treat NASH, it is often difficult to achieve. Foregut bariatric surgery can be quite effective in improving hepatic histology in selected patients without liver failure or significant portal hypertension. Thiazolidinediones have shown promise and the results from the ongoing, large multicenter study should become available soon. Large multicenter studies of CB, receptor anatagonists are also underway but their results will not be available for several years. Several recent studies have highlighted that cardiovascular disease is the single most important cause of morbidity and mortality in this patient population.

CONCLUSION

Health care providers should not only focus on liver disease but also concentrate on aggressively modifying and treating their cardiovascular risk factors.

Non-alcoholic steatohepatitis and animal models: understanding the human disease

Non-alcoholic fatty liver disease includes a broad spectrum of liver abnormalities ranging from simple steatosis to non-alcoholic steatohepatitis (NASH), which can progress to cirrhosis and hepatocellular carcinoma. Patients with primary NASH have the metabolic (or insulin resistance) syndrome, condition typically associated with obesity, diabetes, hyperlipidemia and hypertension. To understand the mechanisms implicated in development of NASH, animal models of non-alcoholic fatty liver disease have been generated. These have greatly improved our understanding of some of the aspects of this disease. The challenge now is to identify the common mechanisms between the animal models and humans, which could eventually lead to a better prognosis and development of novel therapeutic strategies.

Nonalcoholic fatty liver disease: the potential role of nutritional management

PURPOSE OF REVIEW

To review available data pertaining to dietary imbalances and metabolic alterations leading to the development of fatty liver disease and nutritional managements.

RECENT FINDINGS

The importance of treating fatty liver disease is now firmly recognized not only because of the risk of progression toward a more aggressive liver disease but also because the fatty liver is an important provider of cardiovascular risks. The ideal diet for nonalcoholic fatty liver disease/nonalcoholic steatohepatitis patients should reduce fat mass and inflammation in the adipose tissue, restore insulin sensitivity, and provide low amounts of substrates for de-novo lipogenesis, but scientific evidence to recommend specific diets is currently lacking. Moderate weight loss, low-calorie diets, reduction in saturated fatty acids intake, together with an increase in monosaturated and n-3 polyunsaturated fatty acids appear to be beneficial. Excessive consumption of high glycemic index carbohydrates appears deleterious, as it favors hyperglycemia and hyperinsulinemia and stimulates de-novo lipogenesis. Physical exercise is an important component of the approach, as it improves insulin sensitivity. Behavioral therapy promotes long-term compliance to lifestyle modifications.

SUMMARY

One panacea is unlikely to be found, the more useful approach is probably multimodal and includes tailored lifestyle modifications. Randomized controlled trials are needed to establish dietary recommendations. While awaiting such trials, reduced consumption of simple sugar, especially sweetened beverages, and incremental increase in physical activity must be encouraged.