A Noninvasive Clinical Scoring Model Predicts Risk of Nonalcoholic Steatohepatitis in Morbidly Obese Patients

Effects of obstructive sleep apnea on non-alcoholic fatty liver disease in patients with obesity: a systematic review

INTRODUCTION

Obesity has been linked to non-alcoholic fatty liver disease (NAFLD), a widespread chronic liver ailment, as well as obstructive sleep apnea (OSA). The development of NAFLD is influenced by repeated intermittent hypoxia, a feature of OSA.

METHODS

This systematic review (SR) investigated CENTRAL, PubMed, and EMBASE databases. The endpoint of this SR was to assess which OSA-related indicators could predict the presence of NAFLD and the effect of bariatric metabolic surgery (BMS) on improving OSA and NAFLD over time.

RESULTS

Compared to previous SRs published in 2013, 14 new publications were added to our SR, alongside studies conducted prior to 2013. The SR ultimately included 28 studies (18 cross-sectional and 10 cohort trials). In the majority of studies, significant correlations were observed between OSA, OSA-related outcomes, and NAFLD. However, the apnea-hypopnea index (AHI) alone proved to be an inadequate predictor of NAFLD. Instead, respiratory and metabolic changes were found to alleviate oxidative stress induced by hypoxemia. Six studies involved patients who underwent BMS, with one evaluating patients before and after BMS, revealing associations between increased OSA and NAFLD improvement following BMS. Six months after surgery, 100% of patients in the mild-to-moderate OSA group were free from fatty liver, and an 89% reduction was observed in the severe OSA group.

CONCLUSION

For the first time, BMS has been tested in treating both OSA and NAFLD pre and postoperative with positive results. Further research, ideally with histological and functional data, is needed to confirm these findings. The SR identified 14 distinct liver outcome tests; however, high heterogeneity and incomplete data precluded a meta-analysis. It is imperative to pay greater attention to the influence of OSA-related factors and uniformity in liver outcomes testing concerning NAFLD. To accomplish this, study designs should be enhanced by incorporating more comprehensive pre- and postoperative evaluations, extending follow-up periods, and employing a more consistent methodology for liver diagnosis in patients with obesity.

Development, Validation, and Application of a Scoring Model for Non-alcoholic Steatohepatitis

PURPOSE

The aim of this study was to explore risk factors of NASH and then develop a non-invasive scoring model in Chinese patients with obesity. A scoring system was then applied to assess the effect of sleeve gastrectomy on NASH.

METHODS

A total of 243 patients with obesity were included and divided into NASH group and non-NASH group according to the pathological results of liver biopsy. Logistic regression was used to determine risk factors of NASH. A scoring model was derived by risk factors of NASH. Then, postoperative follow-up was performed in 70 patients.

RESULTS

Among the 243 patients, 118 (48.56%) patients showed NASH. Multivariate logistic regression identified aspartate aminotransferase (AST) (>21.50 IU/L), high-density lipoprotein cholesterol (HDL-C) (<1.155mmol/L), and homeostasis model assessment (HOMA-IR) (>9.368) as independent risk factors of NASH. The model included above risk factors showed a negative predictive value (NPV) of 70.38% in the low-risk category and a positive predictive value (PPV) of 85.71% in the high-risk category, with the area under the receiver operator curve (AUROC) of 0.737. Bariatric surgery resulted in a sharp decline in AST and HOMA-IR and a significant increase of HDL-C. The points of scoring model were improved at 6 months after surgery.

CONCLUSION

A non-invasive scoring model was derived by the risk factors of NASH included AST, HDL-C, and HOMA-IR and applied to the postoperative follow-up. After sleeve gastrectomy, the above risk factors and points of scoring model were significantly improved.

Expanding Pharmacists' Role in the Management of Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) stands as an increasingly pressing global health challenge, underscoring the need for timely identification to facilitate effective treatment and prevent the progression of chronic liver disorders. Given the projected scarcity of specialized healthcare professionals, particularly hepatologists and gastroenterologists, the role of pharmacists emerges as pivotal in NAFLD management. This article sheds light on the potential of pharmacists within community pharmacy settings, not as diagnostic entities, but as facilitators in recognizing and screening individuals at elevated NAFLD risk using validated non-invasive tools like portable devices and calculators. By prioritizing patient education, referrals, and continuous monitoring, pharmacists can refine NAFLD management, ultimately advancing patient outcomes. Enhancing pharmacists' impact in early NAFLD detection and management can be facilitated through collaborations with healthcare institutions and the incorporation of patient self-assessment tools. This collaborative approach holds promise for further promoting improved liver health within the community.

Prevalence and predictors of non-alcoholic steatohepatitis in patients with morbid obesity

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is highly prevalent in morbid obesity (MO). A considerable proportion of patients with MO have non-alcoholic steatohepatitis (NASH). Liver biopsy (LB) is the only procedure that reliably differentiates NASH from other stages of NAFLD, but its invasive nature prevents it from being generalisable. Hence, non-invasive assessment is critical in this group of patients.

OBJECTIVES

To report NAFLD/NASH prevalence in a cohort of patients with MO and to identify predictors of NASH.

METHODS

Fifty-two consecutive patients subjected to bariatric surgery in a University hospital in Spain underwent LB. Anthropometric, clinical and biochemical variables were registered. According of the results of the LB, individuals were classified by whether they had NASH or not. Multiple logistic regression analysis was performed to identify independent factors associated with NASH.

RESULTS

NAFLD was reported in 94.2% of the patients, simple steatosis was present in 51.92% and NASH in 42.31%. Meanwhile, 17.3% of patients exhibited significant fibrosis (≥F2). HIGHT score for NASH risk was established using five independent predictors: systemic Hypertension, Insulin resistance, Gamma-glutamyl transferase, High density lipoprotein cholesterol and alanine Transaminase. This score ranges from 0 to 7 and was used to predict NASH in our cohort (area under the receiver operator characteristic curve 0.846). A score of 4 or greater implied high risk (sensitivity 77.3%, specificity 73.3%, positive predictive value 68%, negative predictive value 81.5%, accuracy 75%).

CONCLUSIONS

NAFLD is practically a constant in MO with a considerable proportion of patients presenting NASH. The combination of five independent predictors in a scoring system may help the clinician optimise the selection of patients with MO for LB.

Multidimensional Biomarker Analysis Including Mitochondrial Stress Indicators for Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is accompanied by a complex and multifactorial pathogenesis with sequential progressions from inflammation to fibrosis and then to cancer. This heterogeneity interferes with the development of precise diagnostic and prognostic strategies for NAFLD. The current approach for the diagnosis of simple steatosis, steatohepatitis, and cirrhosis mainly consists of ultrasonography, magnetic resonance imaging, elastography, and various serological analyses. However, individual dry and wet biomarkers have limitations demanding an integrative approach for the assessment of disease progression. Here, we review diagnostic strategies for simple steatosis, steatohepatitis and hepatic fibrosis, followed by potential biomarkers associated with fat accumulation and mitochondrial stress. For mitochondrial stress indicators, we focused on fibroblast growth factor 21 (FGF21), growth differentiation factor 15 (GDF15), angiopoietin-related growth factor and mitochondrial-derived peptides. Each biomarker may not strongly indicate the severity of steatosis or steatohepatitis. Instead, multidimensional analysis of different groups of biomarkers based on pathogenic mechanisms may provide decisive diagnostic/prognostic information to develop a therapeutic plan for patients with NAFLD. For this purpose, mitochondrial stress indicators, such as FGF21 or GDF15, could be an important component in the multiplexed and contextual interpretation of NAFLD. Further validation of the integrative evaluation of mitochondrial stress indicators combined with other biomarkers is needed in the diagnosis/prognosis of NAFLD.

Prevalence and predictors of non-alcoholic steatohepatitis in patients with morbid obesity

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is highly prevalent in morbid obesity (MO). A considerable proportion of patients with MO have non-alcoholic steatohepatitis (NASH). Liver biopsy (LB) is the only procedure that reliably differentiates NASH from other stages of NAFLD, but its invasive nature prevents it from being generalisable. Hence, non-invasive assessment is critical in this group of patients.

OBJECTIVES

To report NAFLD/NASH prevalence in a cohort of patients with MO and to identify predictors of NASH.

METHODS

Fifty-two consecutive patients subjected to bariatric surgery in a University hospital in Spain underwent LB. Anthropometric, clinical and biochemical variables were registered. According of the results of the LB, individuals were classified by whether they had NASH or not. Multiple logistic regression analysis was performed to identify independent factors associated with NASH.

RESULTS

NAFLD was reported in 94.2% of the patients, simple steatosis was present in 51.92% and NASH in 42.31%. Meanwhile, 17.3% of patients exhibited significant fibrosis (≥F2). HIGHT score for NASH risk was established using five independent predictors: systemic Hypertension, Insulin resistance, Gamma-glutamyl transferase, High density lipoprotein cholesterol and alanine Transaminase. This score ranges from 0 to 7 and was used to predict NASH in our cohort (area under the receiver operator characteristic curve 0.846). A score of 4 or greater implied high risk (sensitivity 77.3%, specificity 73.3%, positive predictive value 68%, negative predictive value 81.5%, accuracy 75%).

CONCLUSIONS

NAFLD is practically a constant in MO with a considerable proportion of patients presenting NASH. The combination of five independent predictors in a scoring system may help the clinician optimise the selection of patients with MO for LB.

Sleep disorder in patients with chronic liver disease: a narrative review

Sleep disturbance is a common feature of chronic liver disease (CLD) with impact on health-related quality of life; 60-80% of patients with CLD report subjective poor sleep; frequent presentations of sleep disturbance include insomnia, reduced sleep efficiency, increased sleep latency, reduced time in rapid eye movement (REM) sleep, restless leg syndrome and excessive daytime sleepiness (EDS). Key contributors to sleep disturbance include hepatic encephalopathy (HE) and circadian rhythm imbalance due to altered melatonin metabolism. Specific conditions causing CLD, such as non-alcoholic fatty liver disease (NAFLD), chronic viral hepatitis and primary biliary cholangitis (PBC) result in different types of sleep disturbance, and the treatment of these conditions can often also lead to sleep disturbance. There are currently limited management options for sleep disturbance in CLD. Obstructive sleep apnoea (OSA) is a common condition that causes chronic intermittent hypoxia due to airway collapse during sleep. This chronic intermittent hypoxia appears to contribute to the development of NAFLD. The presence of reactive oxygen species and the overexpression of hypoxia inducible factor 1-alpha secondary to hypoxia may be responsible for the second 'hit' of the 'two-hit' hypothesis of NAFLD. Treatment of the intermittent hypoxia with continuous positive airway pressure therapy has limited efficacy against liver dysfunction. There remain many outstanding areas of investigation in the management of sleep disturbance in CLD, and of liver dysfunction in OSA.

The diagnostic conundrum in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) has become the most common liver alteration worldwide. It encompasses a spectrum of disorders that range from simple steatosis to a progressive form, defined non-alcoholic steatohepatitis (NASH), that can lead to advanced fibrosis and eventually cirrhosis and hepatocellular carcinoma. On liver histology, NASH is characterized by the concomitant presence of significant fat accumulation and inflammatory reaction with hepatocellular injury. Until now, liver biopsy is still required to differentiate simple steatosis from NASH and evaluate the degree of liver fibrosis. Unfortunately, this technique has well-known limitations, including invasiveness and expensiveness. Moreover, it may be biased by sampling error and intra- or inter-observed variability. Furthermore, due to the increasing prevalence of NAFLD worldwide, to program a systematic screening with liver biopsy is not imaginable. In recent years, different techniques were developed and validated with the aim of non-invasively identifying NASH and assess liver fibrosis degrees. The non-invasive tests range from simple blood-tests analyses to composite scores and complex imaging techniques. Nevertheless, even if they could represent cost-effective strategies for diagnosing NASH, advanced fibrosis and cirrhosis, their accuracy and consequent usefulness are to be discussed. With this aim, in this review the authors summarize the current state of non-invasive assessment of NAFLD. In particular, in addition to the well-established tests, the authors describe the future perspectives in this field, reporting the latest tests based on OMICS, gut-miocrobioma and micro-RNAs. Finally, the authors provide an accurate assessment of how these non-invasive tools perform in clinical practice depending on the clinical context, with the aim of giving the clinicians a useful tool to try to resolve the diagnostic conundrum of NAFLD.

Clinical Characteristics and Outcome of Morbidly Obese Bariatric Patients with Concurrent Hepatitis C Viral Infection

BACKGROUND

Hepatitis C virus (HCV) is an important cause of liver cirrhosis and its complications. The safety and efficacy of bariatric surgery in patients with HCV infection is not clear.

METHODS

Charts were reviewed to identify patients with HCV infection before bariatric surgery. Bariatric surgical patients with non-alcoholic steatohepatitis (NASH) and without NASH (non-NASH) were recruited as comparative groups. Demographic variables, perioperative data, follow-up, and HCV-related parameters were extracted and compared.

RESULTS

Forty-seven bariatric patients between 2000 and 2016 that suffered from HCV infection were identified. The mean age and body mass index (BMI) at baseline were 34.5 ± 9.9 years and 40.4 ± 7.7 kg/m², respectively. The HCV(+) group was associated with female sex, older age, lower BMI, and waist circumference than both NASH and non-NASH groups. Both HCV(+) and NASH groups had higher liver function tests and incidence of metabolic syndrome than non-NASH group. The HCV(+) group had lower uric acid and albumin level than the NASH group. Early major postoperative complication occurred in 1 (2.1%) patient of the HCV(+) group. At follow-up, the mean BMI decreased to 29.1 ± 7.1 kg/m² and total weight loss was 25% for the HCV(+) group at 5 years after surgery. The weight loss curves were similar between the HCV(+) group and NASH group. During follow-up, no patients died but one patient with HCV(+) developed flare up of hepatitis after gastric bypass. The mean liver transaminase level remained in normal range for the HCV(+) group.

CONCLUSION

Co-existence of HCV infection does not influence the outcome of bariatric surgery but continued monitoring of the liver function is indicated.

Differentiation between stages of non-alcoholic fatty liver diseases using surface-enhanced Raman spectroscopy

Non-alcoholic fatty liver disease (NAFLD) is a chronic disorder progressing from an initial benign accumulation of fat (NAFL) towards steatohepatitis (NASH), a degenerative form that can lead to liver cirrhosis and cancer. The development of non-invasive, rapid and accurate method to diagnose NASH is of high clinical relevance. Surface-enhanced Raman spectroscopy (SERS) of plasma was tested as a method to distinguish NAFL from NASH. SERS spectra from plasma of female patients diagnosed with NAFL (n = 32) and NASH (n = 35) were obtained in few seconds, using a portable Raman spectrometer. The sample consisted of 5 μL of biofluid deposited on paper coated with Ag nanoparticles. The spectra show consistent differences between the NAFL and NASH patients, with the uric acid/hypoxanthine band area ratio statistically different (p-value <0.001) between the two groups. The average figures of merit for a diagnostic test based on these ratios, as derived from a repeated 4-fold cross-validation of a logistic regression model, are all between 0.73 and 0.79, with an average area under the curve of 0.81. We conclude that SERS may be a reliable and rapid method to discriminate NAFLD from NASH.

Obstructive Sleep Apnea, Hypoxia, and Nonalcoholic Fatty Liver Disease

Recent studies have demonstrated that obstructive sleep apnea (OSA) is associated with the development and evolution of nonalcoholic fatty liver disease (NAFLD), independent of obesity or other shared risk factors. Like OSA, NAFLD is a prevalent disorder associated with major adverse health outcomes: Patients with NAFLD may develop cirrhosis, liver failure, and hepatocellular carcinoma. One major finding that has emerged from these studies is that the OSA-NAFLD association is related to the degree of nocturnal hypoxemia in OSA. Animal models have therefore largely focused on intermittent hypoxia, a key manifestation of OSA, to shed light on the mechanisms by which OSA may give rise to the complex metabolic disturbances that are seen in NAFLD. Intermittent hypoxia leads to tissue hypoxia and can result in oxidative stress, mitochondrial dysfunction, inflammation, and overactivation of the sympathetic nervous system, among many other maladaptive effects. In such models, intermittent hypoxia has been shown to cause insulin resistance, dysfunction of key steps in hepatic lipid metabolism, atherosclerosis, and hepatic steatosis and fibrosis, each of which is pertinent to the development and/or progression of NAFLD. However, many intriguing questions remain unanswered: Principally, how aggressively should the clinician screen for NAFLD in patients with OSA, and vice versa? In this review, we attempt to apply the best evidence from animal and human studies to highlight the relationship between these two disorders and to advocate for further trials aimed at defining these relationships more precisely.

NonInvasive Biomarkers in Nonalcoholic Fatty Liver Disease: Are We There Yet?

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. NAFLD encompasses a spectrum of disease ranging from simple steatosis (NAFL) to nonalcoholic steatohepatitis (NASH), cirrhosis and hepatocellular carcinoma. However, despite the growing recognition of this important disease burden, there are significant challenges to accurately and noninvasively diagnose the various forms of NAFLD, especially to differentiate benign steatosis from the progressive NASH. This is of utmost importance because although liver biopsy is considered the current imperfect 'gold' standard for diagnosing NASH and staging fibrosis, it is an invasive procedure with significant limitations. Although, a number of noninvasive markers have been or are currently undergoing investigation, until date, no highly sensitive and specific tests are available to differentiate NASH from simple steatosis. At the moment, further investigations are needed before prediction models or blood-based biomarkers become available and acceptable for routine clinical care. There is a great need for developing inexpensive, easily accessible, highly sensitive and specific biomarkers that permit not only the identification of patients at high risk of adverse outcomes, but also the monitoring of disease progression and response after therapeutic interventions.

Non-alcoholic Fatty Liver Disease and Diabetes Mellitus

Nonalcoholic fatty liver disease (NAFLD) has emerged as the leading liver disease globally. NAFLD patients can have a progressive phenotype, non-alcoholic steatohepatitis (NASH) that could lead to cirrhosis, liver failure and cancer. There is a close bi-directional relationship between NAFLD and type 2 diabetes mellitus (T2DM); NAFLD increases the risk for T2DM and its complications whereas T2DM increases the severity of NAFLD and its complications. The large global impact of NAFLD and T2DM on healthcare systems requires a paradigm shift from specialty care to early identification and risk stratification of NAFLD in primary care and diabetes clinics. Approach to diagnosis, risk stratification and management of NAFLD is discussed. In addition to optimizing the control of coexisting cardiometabolic comorbidities, early referral of NAFLD patients at high risk of having NASH or significant fibrosis to hepatology specialist care may improve management and allow access for clinical trials. Lifestyle modifications, vitamin E, pioglitazone and metformin are currently available options that may benefit patients with T2DM and NAFLD. The burst of clinical trials investigating newer therapeutic agents for NAFLD and NASH offer hope for new, effective and safe therapies in the near future.

Histologic Findings of Advanced Fibrosis and Cirrhosis in Patients With Nonalcoholic Fatty Liver Disease Who Have Normal Aminotransferase Levels

OBJECTIVES

Patients with nonalcoholic fatty liver disease (NAFLD) and normal aminotransferase levels may have advanced liver histology. We conducted a study to characterize the prevalence of and factors associated with advanced liver histology in patients with histologically characterized NAFLD and normal aminotransferase levels.

METHODS

We evaluated 534 adults with biopsy-proven NAFLD and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) <40U/L within 3 months of their liver biopsy. Histological phenotypes of primary interest were nonalcoholic steatohepatitis (NASH) with stage 2-3 fibrosis (NASH F2-3) and cirrhosis. Using multiple logistic regression models with Akaike's Information Criteria (AIC), we identified variables associated with these histological phenotypes. We developed and internally validated their clinical prediction models.

RESULTS

The prevalence of NASH F2-F3 and cirrhosis was 19% and 7%, respectively. The best multiple regression AIC model for NASH F2-3 consisted of type 2 diabetes, white race, lower low-density lipoprotein, lower platelet count, higher AST/ALT ratio, higher serum triglycerides, and hypertension. The best AIC model for cirrhosis consisted of lower platelet count, lower AST/ALT ratio, higher body mass index, and female sex. The area under the receiver operator curves of the prediction models were 0.70 (95% confidence interval: 0.65-0.76) for detecting NASH-F2-3 and 0.85 (95% confidence interval: 0.77-0.92) for detecting cirrhosis. When models were fixed at maximum Youden's index, their positive and negative predictive values were 35% and 88% for NASH F2-F3 and 30% and 98% for cirrhosis, respectively.

DISCUSSION

Clinically significant histological phenotypes are observed in patients with NAFLD and normal aminotransferase levels. Our models can assist the clinicians in excluding advanced liver histology in NAFLD patients with normal aminotransferase levels.

Noninvasive Assessment of Liver Disease in Patients With Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is estimated to afflict approximately 1 billion individuals worldwide. In a subset of NAFLD patients, who have the progressive form of NAFLD termed nonalcoholic steatohepatitis (NASH), it can progress to advanced fibrosis, cirrhosis, hepatocellular carcinoma, and liver-related morbidity and mortality. NASH is typically characterized by a specific pattern on liver histology, including steatosis, lobular inflammation, and ballooning with or without peri-sinusoidal fibrosis. Thus, key issues in NAFLD patients are the differentiation of NASH from simple steatosis and identification of advanced hepatic fibrosis. Until now, liver biopsy has been the gold standard for identifying these 2 critical end points, but has well-known limitations, including invasiveness; rare but potentially life-threatening complications; poor acceptability; sampling variability; and cost. Furthermore, due to the epidemic proportion of individuals with NAFLD worldwide, liver biopsy evaluation is impractical, and noninvasive assessment for the diagnosis of NASH and fibrosis is needed. Although much of the work remains to be done in establishing cost-effective strategies for screening for NASH, advanced fibrosis, and cirrhosis, in this review, we summarize the current state of the noninvasive assessment of liver disease in NAFLD, and we provide an expert synthesis of how these noninvasive tools could be utilized in clinical practice. Finally, we also list the key areas of research priorities in this area to move forward clinical practice.

Chronic intermittent hypoxia promotes the development of experimental non-alcoholic steatohepatitis by modulating Treg/Th17 differentiation

The present study aims to characterize the effect of chronic intermittent hypoxia and HIF1α on the non-alcoholic steatohepatitis (NASH) process in mice, and to explore the role of the Treg/Th17 balance in the formation of NASH inflammation and fibrosis. To achieve this purpose, simple steatosis was induced in mice by high-fat diet administration. Subsequently, chronic intermittent hypoxia was simulated by intraperitoneally injecting sodium nitrite. The changes of inflammation, fibrosis, and Treg/Th17 balance in the liver were quantified under chronic intermittent hypoxia condition and after tail vein injection of HIF1α-siRNA. In addition, T cells were cultured in vitro, and HIF1α expression was either blocked or overexpressed under chronic intermittent hypoxia or normal conditions. Then, the changes of Treg/Th17 balance, inflammatory factors, and cell pathways were measured in each group. Our results demonstrated that chronic intermittent hypoxia accelerates the NASH process, while tail vein injection of HIF1α-siRNA improves liver histology and function. Chronic intermittent hypoxia alters the ratio of Th17 and Treg cells through HIF1α and mTOR signaling, and increases the expressions of NF-κB, IL-6, and IL-17, but decreases IL-10 expression. Inhibition of the mTOR-HIF1α-TLR4-IL-6 pathway increases the ratio of Treg/Th17. Thus, chronic intermittent hypoxia modulates the Treg/Th17 balance by inducing HIF1α, resulting in the activation of the mTOR-HIF1α-TLR4-IL-6 pathway, which accelerates the formation of NASH and fibrosis.

Non-alcoholic fatty liver disease-From the cardiologist perspective

Non-alcoholic fatty liver disease (NAFLD) includes a range of disorders characterized by excess accumulation of triglycerides within the liver. While simple steatosis may be clinically stable, non-alcoholic steatohepatitis (NASH) can be progressive. Inflammation is believed to be the driving force behind NASH and the progression to fibrosis and subsequent cirrhosis. NAFLD is globally considered a significant health concern not only because of its incidence but also because of its economic impact. The fact that NAFLD is associated with cardiovascular disease is widely recognized, as well as the fact that NAFLD patient mortality rises when such an association is present. In particular, NAFLD is associated with coronary and carotid atherosclerosis, endothelial dysfunction and arterial rigidity, ventricles function, valves morphology, congestive heart failure, and arrhythmias (especially atrial fibrillation). Additionally, the hypercoagulability status in NAFLD patient may be suggested by the presence of inflammatory and coagulation markers. In order to differentiate between milder forms and the more severe ones that necessitate aggressive therapy, individualized risk scores may be used. This narrative review will analyze and interpret the papers published in PubMed in the last 16 years, in an attempt to expand our understanding of the NASH as a possible cardiovascular risk factor.

Long-term effect of bariatric surgery on resolution of nonalcoholic steatohepatitis (NASH): An external validation and application of a clinical NASH score

BACKGROUND

Nonalcoholic steatohepatitis (NASH) is an important etiology of end-stage liver disease. Long-term effect of bariatric surgery in improvement of NASH is not clear.

OBJECTIVES

To validate a scoring system for predicting NASH in morbidly obese patients and using it to evaluate the long-term effect of bariatric surgery on NASH.

SETTING

Tertiary referral hospital, Taiwan.

METHODS

A new 5-point clinical NASH (C-NASH) score incorporating body mass index, alanine aminotransferase, and triglyceride was validated in a group of 307 bariatric patients (mean age 30.2 years, incorporating body mass index 45.0 kg/m²) with concurrent liver biopsy from 2003 to 2008. Remission of NASH in 5741 obese patients undergoing bariatric/metabolic surgery with long-term follow-up was then evaluated using the C-NASH score.

RESULTS

Among 307 patients with liver biopsy, the prevalence of NASH was 44.0%. At baseline, the NASH group had significantly worse fasting glucose levels, triglycerides, uric acid, aspartate aminotransferase, alanine aminotransferase, gamma glutamyl transferase, and glycated hemoglobin. The diagnostic sensitivity of C-NASH score was 84.4%, and the accuracy was 68.4%. Among 5741 bariatric patients, the prevalence of high risk for NASH evaluated by C-NASH score was 40.9%. Postoperative follow-up showed good weight loss and almost complete remission of high risk for NASH up to 10 years. Patients with gastric banding had less weight loss, higher mean level of C-NASH score, and a higher incidence of high risk for NASH compared with other procedures at follow-up.

CONCLUSION

This study demonstrated that improvement in C-NASH score suggesting remission of NASH is durable up to 10 years in all kinds of bariatric procedures.

Non-invasive assessment of non-alcoholic fatty liver disease: Clinical prediction rules and blood-based biomarkers

The correct identification of patients at increased risk of non-alcoholic steatohepatitis (NASH) and advanced fibrosis is a critical step in the assessment of non-alcoholic fatty liver disease (NAFLD). Since liver biopsy is invasive, expensive and prone to sampling error, several clinical prediction rules and blood-based biomarkers have been developed as attractive and affordable alternatives for identification of patients at high risk of NASH and advanced fibrosis. Current biomarkers constitute predictive models (e.g. NAFLD fibrosis score, FIB-4 index and BARD score) or direct measures of inflammation (e.g. circulating keratin 18 fragments), or fibrosis (e.g. FibroTest®, ELF™ or Pro-C3 tests). In the clinical setting, biomarkers may discriminate between patients with NASH or advanced fibrosis, predict dynamic changes in NASH/fibrosis over time, and provide long-term prognostic information. Although clinically useful, current biomarker predictions may be influenced by hepatic and extrahepatic conditions (e.g. age, patient comorbidities, and fibrosis or NASH prevalence), which may lead to inaccurate estimates in small subsamples of patients. No highly sensitive and specific tests are available to differentiate NASH from simple steatosis. However, diagnostic accuracy can be improved by combining blood biomarkers. NAFLD fibrosis score and FIB-4 index are both cost-effective and highly sensitive tools to exclude patients with advanced fibrosis. Moreover, their higher scores may identify patients at higher risk of non-liver- and liver-related morbidity and mortality. More expensive tests such as FibroTest or ELF are more specific for detection of patients with significant and advanced fibrosis. Recent efforts have concentrated on "omics" approaches for developing and validating novel biomarkers. Herein, we describe currently available clinical prediction rules and blood-based biomarkers for identifying NASH and advanced fibrosis in patients with NAFLD, discussing their advantages and disadvantages, as well as their potential clinical utility for predicting dynamic changes over time and identifying patients at increased risk of adverse outcomes.

The association of nonalcoholic steatohepatitis and obstructive sleep apnea

BACKGROUND AND AIM

The association between obstructive sleep apnea (OSA) and abnormal liver enzymes has been reported in multiple studies. The existing literature regarding the relationship between OSA and nonalcoholic steatohepatitis (NASH) is conflicting. Thus we aimed to determine the relationship between OSA and NASH from a large database.

PATIENTS AND METHODS

A cross-sectional study was performed using the 2012 Nationwide Inpatient Sample. We identified adult patients (18-90 years) who had a diagnosis of OSA using the International Classification of Diseases 9th version codes. The control group was comprised of adult individuals with no discharge records of OSA. NASH diagnosis was also identified using the International Classification of Diseases 9th version codes. The association between OSA and NASH was calculated using univariable and multivariable logistic regression.

RESULTS

A total of 30 712 524 hospitalizations were included. The OSA group included 1 490 150 patients versus 29 222 374 in the control non-OSA group. The OSA group average age was 61.8±0.07 years (44.2% females) compared with 57.0±0.11 years (60.1% females) in the non-OSA group. NASH prevalence was significantly higher in the OSA group compared with the non-OSA group [2% (95% confidence interval (CI): 1.9, 2.1) vs. 0.65% (95% CI: 0.63, 0.66), P<0.001]. After adjusting for obesity, diabetes, hypertension, dyslipidemia, the metabolic syndrome and Charlson comorbidity index, OSA patients were three times more likely to have NASH [adjusted odds ratio: 3.1 (95% CI: 3.0-3.3), P<0.001].

CONCLUSION

Patients with OSA are three times more likely to have NASH compared with patients without OSA after controlling for other confounders. These data indicate that OSA should be considered as an independent risk factor for developing NASH.

Transcriptional regulation of PNPLA3 and its impact on susceptibility to nonalcoholic fatty liver Disease (NAFLD) in humans

The increased expression of PNPLA3^148M leads to hepatosteatosis in mice. This study aims to investigate the genetic control of hepatic PNPLA3 transcription and to explore its impact on NAFLD risk in humans. Through a locus-wide expression quantitative trait loci (eQTL) mapping in two human liver sample sets, a PNPLA3 intronic SNP, rs139051 A>G was identified as a significant eQTL (p = 6.6×10^-8) influencing PNPLA3 transcription, with the A allele significantly associated with increased PNPLA3 mRNA. An electrophoresis mobility shift assay further demonstrated that the A allele has enhanced affinity to nuclear proteins than the G allele. The impact of this eQTL on NAFLD risk was further tested in three independent populations. We found that rs139051 did not independently affect the NAFLD risk, whilst rs738409 did not significantly modulate PNPLA3 transcription but was associated with NAFLD risk. The A-G haplotype associated with higher transcription of the disease-risk rs738409 G allele conferred similar risk for NAFLD compared to the G-G haplotype that possesses a lower transcription level. Our study suggests that the pathogenic role of PNPLA3^148M in NAFLD is independent of the gene transcription in humans, which may be attributed to the high endogenous transcription level of PNPLA3 gene in human livers.

Derivation and validation of a scoring system for predicting nonalcoholic steatohepatitis in Taiwanese patients with severe obesity

BACKGROUND

Nonalcoholic steatohepatitis (NASH) is common in severely obese Asians and may progress to advanced liver disease. Although invasive, liver biopsy is the gold standard for NASH diagnosis. Scoring systems for predicting NASH in obese Asians are scarce.

OBJECTIVES

To develop and validate a scoring system to predict NASH in Taiwanese patients with severe obesity.

SETTING

University hospital, Taiwan.

METHODS

Preoperative clinical and laboratory data were obtained from 180 severely obese patients who underwent bariatric surgery. NASH was evaluated by liver histopathology. Patients were divided into 2 groups: a derivation cohort (n = 120) and a validation cohort (n = 60).

RESULTS

Of the 180 patients, 91 (50.6%) had NASH. Multivariate analysis identified body mass index (BMI), alanine aminotransferase (ALT), and triglyceride as independent predictors for NASH in the derivation group. A weighted sum of the score was: [(1 for presence of 45 kg/m² ≧ BMI>40 kg/m²) or (2 for presence of BMI>45 kg/m²)+(2 for presence of ALT>40 IU/L)+(1 for presence of triglyceride>140 mg/L)]. The area under the receiver operating characteristic curve of this model was .80 and .82 in derivation and validation cohort, respectively. Patients were further divided into low- and high-risk for NASH by using a cutoff score of 3. Diagnostic accuracy was 74% and 80% in derivation and validation cohorts, respectively.

CONCLUSION

We developed and subsequently validated a simple clinical scoring system incorporating BMI, ALT, and triglyceride to predict NASH in Taiwanese patients with severe obesity.

Nonalcoholic fatty liver disease and obstructive sleep apnea

Obstructive sleep apnea (OSA) and more importantly its hallmark, chronic intermittent hypoxia (CIH), are established factors in the pathogenesis and exacerbation of nonalcoholic fatty liver disease (NAFLD). This has been clearly demonstrated in rodent models exposed to intermittent hypoxia, and strong evidence now also exists in both paediatric and adult human populations. OSA and CIH induce insulin-resistance and dyslipidemia which are involved in NAFLD physiopathogenesis. CIH increases the expression of the hypoxia inducible transcription factor HIF1α and that of downstream genes involved in lipogenesis, thereby increasing β-oxidation and consequently exacerbating liver oxidative stress. OSA also disrupts the gut liver axis, increasing intestinal permeability and with a possible role of gut microbiota in the link between OSA and NAFLD. OSA patients should be screened for NAFLD and vice versa those with NAFLD for OSA. To date there is no evidence that treating OSA with continuous positive airway pressure (CPAP) will improve NAFLD but it might at least stabilize and slow its progression. Nevertheless, these multimorbid patients should be efficiently treated for all their metabolic co-morbidities and be encouraged to follow weight stabilization or weight loss programs and physical activity life style interventions.

The Metabolic Syndrome and Its Influence on Nonalcoholic Steatohepatitis

Nonalcoholic steatohepatitis (NASH) and the metabolic syndrome (MetS) are highly prevalent in the Western population. Their pathogenesis is closely linked to insulin resistance, which serves as a therapeutic target for the management of these conditions. This review article reviews the research supporting the influence of MetS on NASH and includes studies supporting their similar epidemiology, pathogenesis, and treatment.

Obstructive Sleep Apnea Is Associated with Nonalcoholic Steatohepatitis and Advanced Liver Histology

BACKGROUND AND AIMS

Nonalcoholic fatty liver disease (NAFLD) and obstructive sleep apnea (OSA) are growing in prevalence in the USA. Existing data on the relationship between OSA and NAFLD are conflicting and limited by the use of various histologic definitions of nonalcoholic steatohepatitis (NASH). Using a robust definition of NASH in a large, well-characterized cohort, we sought to evaluate whether OSA was associated with NASH and advanced fibrosis.

METHODS

Two hundred and thirteen subjects undergoing weight loss surgery were queried for OSA and then underwent liver biopsy. NASH was defined, as recommended by the American Association for the Study of Liver Disease, by the presence of all of the following: >5 % macrovesicular steatosis, lobular inflammation, and hepatocyte ballooning. NAFLD activity score (NAS) was also determined for each subject.

RESULTS

Subjects with OSA had significantly higher alanine and aspartate aminotransferase levels than subjects without OSA (ALT 54.1 vs. 37.7 U/L, P = 0.0007; AST 31.7 vs. 20.5 U/L, P = 0.0007). OSA was associated with the presence of NASH, and this remained significant after adjusting for age, gender, race, and diabetes mellitus (P = 0.03 OR 2.01; 95 %, 1.05-3.87). Steatosis grade, lobular inflammation grade, NAS score, and fibrosis stage were all significantly associated with the presence of OSA and remained so after adjustment.

CONCLUSIONS

OSA is associated with elevated aminotransferase levels, the presence of NASH, and advanced NASH histology. Further studies are needed to evaluate the impact of OSA treatment on NASH.

Composite prognostic models across the non-alcoholic fatty liver disease spectrum: Clinical application in developing countries

Heterogeneity in clinical presentation, histological severity, prognosis and therapeutic outcomes characteristic of non-alcoholic fatty liver disease (NAFLD) necessitates the development of scientifically sound classification schemes to assist clinicians in stratifying patients into meaningful prognostic subgroups. The need for replacement of invasive liver biopsies as the standard method whereby NAFLD is diagnosed, graded and staged with biomarkers of histological severity injury led to the development of composite prognostic models as potentially viable surrogate alternatives. In the present article, we review existing scoring systems used to (1) confirm the presence of undiagnosed hepatosteatosis; (2) distinguish between simple steatosis and NASH; and (3) predict advanced hepatic fibrosis, with particular emphasis on the role of NAFLD as an independent cardio-metabolic risk factor. In addition, the incorporation of functional genomic markers and application of emerging imaging technologies are discussed as a means to improve the diagnostic accuracy and predictive performance of promising composite models found to be most appropriate for widespread clinical adoption.

Non-invasive Testing for NASH and NASH with Advanced Fibrosis: Are We There Yet?

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent etiology of chronic liver disease in America. NAFLD can be broadly classified in two subtypes: nonalcoholic fatty liver (NAFL), which is generally considered a benign condition with negligible risk of progression to cirrhosis, and nonalcoholic steatohepatitis (NASH), which is generally considered to be progressive with substantial risk of progression to cirrhosis. Additionally, recent studies suggest the odds of liver mortality increases amongst NASH patients with advanced fibrosis (bridging fibrosis ± cirrhosis). Liver biopsy examination is the current gold standard to accurately discriminate between NAFL vs. NASH as well as diagnose advanced fibrosis. However, due to its invasive nature, risk of bleeding (and even rarely death), prohibitive cost, and sampling error, liver biopsies are imperfect for diagnosis and monitoring of NAFLD. As a result, noninvasive biomarkers that can accurately detect NASH and advanced fibrosis without biopsy are needed. This article will discuss the most novel noninvasive biomarkers in diagnosing NASH and advanced fibrosis.

The Wide and Complex Field of NAFLD Biomarker Research: Trends

Background. Nonalcoholic fatty liver disease is now acknowledged as a complex public health issue linked to sedentary lifestyle, obesity, and related disorders like type 2 diabetes and metabolic syndrome. Aims. We aimed to retrieve its trends out of the huge amount of published data. Therefore, we conducted an extensive literature search to identify possible biomarker and/or biomarker combinations by retrospectively assessing and evaluating common and novel biomarkers to predict progression and prognosis of obesity related liver diseases. Methodology. We analyzed finally 62 articles accounting for 157 cohorts and 45,288 subjects. Results. Despite the various approaches, most cohorts were considerably small and rarely comparable. Also, we found that the same standard parameters were measured rather than novel biomarkers. Diagnostics approaches appeared incomparable. Conclusions. Further collaborative investigations on harmonizing ways of data acquisition and identifying such biomarkers for clinical use are necessary to yield sufficient significant results of potential biomarkers.

A population-based study on the prevalence of NASH using scores validated against liver histology

BACKGROUND & AIMS

Non-alcoholic steatohepatitis (NASH) is a leading cause of chronic liver disease in Western countries. Diagnosis of NASH requires a liver biopsy. We estimated the prevalence of NASH non-invasively in a population-based study using scores validated against liver histology.

METHODS

Clinical characteristics, PNPLA3 genotype at rs738409, and serum cytokeratin 18 fragments were measured in 296 consecutive bariatric surgery patients who underwent a liver biopsy to discover and validate a NASH score ('NASH score'). We also defined the cut-off for NASH for a previously validated NAFLD liver fat score to diagnose NASH in the same cohort ('NASH liver fat score'). Both scores were validated in an Italian cohort comprising of 380, mainly non-bariatric surgery patients, who had undergone a liver biopsy for NASH. The cut-offs were utilized in the Finnish population-based D2D-study involving 2849 subjects (age 45-74 years) to estimate the population prevalence of NASH.

RESULTS

The final 'NASH Score' model included PNPLA3 genotype, AST and fasting insulin. It predicted NASH with an AUROC 0.774 (0.709, 0.839) in Finns and 0.759 (0.711, 0.807) in Italians (NS). The AUROCs for 'NASH liver fat score' were 0.734 (0.664, 0.805) and 0.737 (0.687, 0.787), respectively. Using 'NASH liver fat score' and 'NASH Score', the prevalences of NASH in the D2D study were 4.2% (95% CI: 3.4, 5.0) and 6.0% (5.0, 6.9%). Sensitivity analysis was performed by taking into account stochastic false-positivity and false-negativity rates in a Bayesian model. This analysis yielded population prevalences of NASH of 3.1% (95% stimulation limits 0.2-6.8%) using 'NASH liver fat score' and 3.6% (0.2-7.7%) using 'NASH Score'.

CONCLUSIONS

The population prevalence of NASH in 45-74 year old Finnish subjects is ∼ 5%.

Association of obstructive sleep apnoea with the presence and severity of non-alcoholic fatty liver disease. A systematic review and meta-analysis

Obstructive sleep apnoea syndrome (OSAS) and non-alcoholic fatty liver disease (NAFLD) are common in clinical practice. NAFLD encompasses simple steatosis and non-alcoholic steatohepatitis (NASH): both confer an increased risk of cardiovascular disease and diabetes; NASH increases also liver-related risk. Growing experimental evidence connects chronic intermittent hypoxia of OSAS to NAFLD. We reviewed English and non-English articles and international meeting abstracts through December 2012. Observational studies were included if they assessed OSAS by polysomnography and NAFLD by histological, radiological or biochemical criteria. Two reviewers evaluated retrieved articles by appropriate quality scores. Main outcomes were pooled using random- or fixed-effects models. The effect of age, sex and body mass index (BMI) on effect estimates was assessed by meta-regression. Eighteen cross-sectional studies (2,183 participants) were included. Pooled odds ratios (ORs) of OSAS for the presence of NAFLD, as defined by histology, radiology, and AST or ALT elevation, were 2.01(95% CI: 1.36-2.97), 2.99(1.79-4.99), 2.36(1.46-3.82) and 2.60(1.88-3.61), respectively. Pooled ORs of OSAS for NASH, fibrosis-any stage, or advanced fibrosis in biopsy-proven NAFLD patients were 2.37(1.59-3.51), 2.16(1.45-3.20) and 2.30(1.21-4.38). The magnitude and direction of effects were unaffected by age, sex and BMI. In conclusion, OSAS is associated with an increased risk of NAFLD, NASH and fibrosis. OSAS patients should be screened for the presence and severity of NAFLD.

Noninvasive biomarkers for the diagnosis of steatohepatitis and advanced fibrosis in NAFLD

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of abnormal liver enzymes in both adults and children. NAFLD has a histologic spectrum ranging from simple steatosis to nonalcoholic steatohepatitis (NASH), advanced fibrosis, and cirrhosis. It is imperative to distinguish simple steatosis from NASH since the latter has a progressive disease course and can lead to end-stage liver disease. Liver biopsy has been considered as the gold standard for the diagnosis of NASH. However, liver biopsy is invasive, costly, and can rarely cause significant morbidity (risk of morbidity, 0.06-0.35%; risk of mortality, 0.1-0.01%). Imaging studies such as ultrasonography, computed tomography, and magnetic resonance imaging have limited sensitivity in detecting steatosis and cannot distinguish steatosis from NASH. Alanine aminotransferase (ALT) has been used as a surrogate marker for liver injuries. However, ALT is not an ideal marker for either diagnosis of NAFLD or distinguishing steatosis from NASH. Better noninvasive biomarkers or panels of biomarkers that are cheaper, reliable, and reproducible are urgently needed for patients with NASH to assist in establishing diagnosis, providing risk information, and monitoring disease progression and treatment response. In this article, we plan to concisely review the current advances in the use of biomarkers for the diagnosis of NASH.

The role of nutrients in the development, progression, and treatment of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of liver disease in adults and children and is currently the third most common indication for liver transplantation in North America. Its pathogenesis is thought to be secondary to multiple "hits" derived from the dietary components, adipose tissue, immune system, and intestinal microbiota. Lack of physical activity may contribute as well. Nutrients may exert their effect directly or through alteration of the intestinal microbiota. Research focusing on specific dietary components predisposing to NAFLD has shown conflicting results. Total energy intake, and macronutrients, has been linked to the development of NAFLD. Fructose not only contributes to hepatic steatosis but may trigger inflammatory signals as well. Polyunsaturated fatty acids are thought to exert anti-inflammatory effects. The role of vitamins as well as minerals in this field is actively being investigated. In this review, we discuss the evidence-linking macronutrients (such as carbohydrates and fat in general and fructose, fiber, short chain fatty acids, polyunsaturated fatty, and choline specifically) and micronutrients (such as vitamin E and C and minerals) with the development and treatment of NAFLD. We also discuss the literature on physical activity and NAFLD.

Characteristics of patients with the "malignant obesity hypoventilation syndrome" admitted to an ICU

BACKGROUND

The incidence of obesity in westernized nations is increasing at an alarming rate. We have noted an increasing number of patients admitted to our intensive care unit (ICU) with hypercapnic respiratory failure and multisystem organ dysfunction related to obesity. We have coined the term the malignant obesity hypoventilation syndrome (MOHS) to describe this entity.

METHODS

We reviewed the hospital records of all patients who were admitted to our ICU over an 8-month period, with a body mass index (BMI) greater than 40 kg/m² and a PaCO₂ greater than 45 mm Hg. We excluded patients with musculoskeletal disease, intrinsic lung disease, and those with >20 pack-year smoking history.

RESULTS

Sixty-one patients (8% of all admissions) met the inclusion criteria for our study. The patients' mean BMI was 48.9 ± 8.6 kg/m². The patients' mean age was 59 ± 11; 47 (77%) were female and 56 (92%) were black. All patients were admitted to the ICU with hypercapnic respiratory failure. The patients had been admitted to our hospital on average 6 times over the previous 2 years; 75% had been erroneously diagnosed and treated for chronic obstructive pulmonary disease (COPD)/asthma and 86% had been treated with diuretics for congestive cardiac failure. All patients had type 2 diabetes and the metabolic syndrome. Three patients had a tracheotomy in place at admission and required mechanical ventilation. All of the remaining patients were treated with noninvasive bilevel positive airway pressure (BiPAP), with 23 patients failing BiPAP and requiring mechanical ventilation. Seven patients had a tracheotomy performed. On the basis of unexplained abnormalities of liver function tests, 39 patients (64%) were presumptively diagnosed with nonalcoholic steatohepatitis (NASH). Pulmonary function tests were suggestive of a restrictive pattern in all patients tested. By echocardiography 43 (71%) patients had left ventricular hypertrophy and 37 (61%) patients had features of left ventricular diastolic dysfunction. Forty-seven (77%) patients had pulmonary hypertension, which was moderate to severe (pulmonary systolic pressure >45 mm Hg) in 25 cases. All patients had an elevated C-reactive protein (9.4 ± 6.9 mg/dL), and all but 1 were vitamin D deficient (13.5 ± 8.5 ng/mL). Eleven patients (18%) died during the index hospitalization.

CONCLUSIONS

MOHS is a serious multisystem disorder with a high mortality that appears to be relatively common, frequently misdiagnosed, and inadequately treated.

Metabolic consequences of ENPP1 overexpression in adipose tissue

Ectonucleotide pyrophosphate phosphodiesterase (ENPP1) has been shown to negatively modulate insulin receptor and to induce cellular insulin resistance when overexpressed in various cell types. Systemic insulin resistance has also been observed when ENPP1 is overexpressed in multiple tissues of transgenic models and attributed largely to tissue insulin resistance induced in skeletal muscle and liver. Another key tissue in regulating glucose and lipid metabolism is adipose tissue (AT). Interestingly, obese patients with insulin resistance have been reported to have increased AT ENPP1 expression. However, the specific effects of ENPP1 in AT have not been studied. To better understand the specific role of AT ENPP1 on systemic metabolism, we have created a transgenic mouse model (C57/Bl6 background) with targeted overexpression of human ENPP1 in adipocytes, using aP2 promoter in the transgene construct (AdiposeENPP1-TG). Using either regular chow or pair-feeding protocol with 60% fat diet, we compared body fat content and distribution and insulin signaling in adipose, muscle, and liver tissues of AdiposeENPP1-TG and wild-type (WT) siblings. We also compared response to intraperitoneal glucose tolerance test (IPGTT) and insulin tolerance test (ITT). Our results show no changes in Adipose ENPP1-TG mice fed a regular chow diet. After high-fat diet with pair-feeding protocol, AdiposeENPP1-TG and WT mice had similar weights. However, AdiposeENPP1-TG mice developed fatty liver in association with changes in AT characterized by smaller adipocyte size and decreased phosphorylation of insulin receptor Tyr(1361) and Akt Ser(473). These changes in AT function and fat distribution were associated with systemic abnormalities of lipid and glucose metabolism, including increased plasma concentrations of fatty acid, triglyceride, plasma glucose, and insulin during IPGTT and decreased glucose suppression during ITT. Thus, our results show that, in the presence of a high-fat diet, ENPP1 overexpression in adipocytes induces fatty liver, hyperlipidemia, and dysglycemia, thus recapitulating key manifestations of the metabolic syndrome.

Inflammation in nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) describes a range of disorders characterized by excess accumulation of triglyceride within the liver. While simple steatosis may be clinically stable, nonalcoholic steatohepatitis (NASH) can be progressive. Inflammation is believed to be the driving force behind NASH and the progression to fibrosis and subsequent cirrhosis. This article will review and interpret the current literature in an attempt to expand our understanding of the environmental and genetic causes of inflammation and its effects in NAFLD.

Systematic review of performance of non-invasive biomarkers in the evaluation of non-alcoholic fatty liver disease

This systematic review evaluates the many studies carried out to discover and evaluate non-invasive markers of non-alcoholic fatty liver disease (NAFLD). Many different strategies and methods have been used in this task, from the discovery of new markers by global 'shotgun' studies to hypothesis-driven approaches, to the development of algorithm tests based on routinely available clinical and biochemical parameters. We examined the various different approaches, summarising the findings in an attempt to give an overview of the field of non-invasive markers in NAFLD, encompassing markers of steatosis, necro-inflammation and fibrosis. The body of literature surrounding this topic is complex and varied, encompassing not only different methodologies but also different patient characteristics, different disease definitions, as well as different end points. This reflects the heterogeneity of NAFLD, which, however, introduces considerably difficulty when trying to draw a conclusion between studies. We have divided this review into three main chapters based on the characteristics of the studies. The Genomics/Proteomics chapter reviews studies using a non-hypothesis-driven approach to biomarker discovery. Thereafter, we evaluate studies of association - studies that target-specific markers, comparing levels between disease and control groups. Finally, we examine the algorithm tests - mathematical systems developed on the basis of previously described markers and assessed, usually, by receiver operator curve analysis. While radiological examination and investigations offer important diagnostic information, such studies are not discussed in this review - the body of literature surrounding blood and anthropological markers is complex and varied, demanding close attention.

Non-invasive diagnosis of nonalcoholic fatty liver and nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the USA and many other parts of the world. Its prevalence continues to rise; currently affecting about one in four adults and 10% of children in the USA. NAFLD represents a wide spectrum of conditions ranging from fatty liver, which in general follows a benign, no-progressive clinical course, to nonalcoholic steatohepatitis (NASH), a more serious form of NAFLD that may progress to cirrhosis and end-stage liver disease. Currently, the diagnosis of NASH requires an invasive liver biopsy with drawbacks of sampling and interpretation error. Clinical risk factors for NASH include diabetes and the metabolic syndrome; however, these are not sufficiently predictive of the condition by themselves. Routine liver enzyme levels are not reliable; however, novel plasma hepatocyte cell death markers either alone or in combination with clinical risk factors are potential non-invasive diagnostic tools for the future. This review provides a concise overview of the role non-invasive diagnostic tools for the differentiation of fatty liver from NASH as well as for the determination of presence and extent of fibrosis.

Influence of Sleeve Gastrectomy on NASH and Type 2 Diabetes Mellitus

Background. Nonalcoholic fatty liver disease is present in up to 85% of adipose patients and may proceed to nonalcoholic steatohepatitis (NASH). With insulin resistance and obesity being the main risk factors for NASH, the effect of isolated sleeve gastrectomy (ISG) on these parameters was examined. Methods. 236 patients underwent ISG with intraoperative liver biopsy from December 2002 to September 2009. Besides demographic data, pre-operative weight/BMI, HbA1c, AST, ALT, triglycerides, HDL and LDL levels were determined. Results. A significant correlation of NASH with higher HbA1c, AST and ALT and lower levels for HDL was observed (P < .05, <.0001, <.0001, <.01, resp.). Overall BMI decreased from 45.0 ± 6.8 to 29.7 ± 6.5 and 31.6 ± 4.4 kg/m(2) at 1 and 3 years. An impaired weight loss was demonstrated for patients with NASH and patients with elevated HbA1c (plateau 28.08 kg/m(2) versus 29.79 kg/m(2) and 32.30 kg/m(2) versus 28.79 kg/m(2), resp.). Regarding NASH, a significant improvement of AST, ALT, triglyceride and HDL levels was shown (P < .0001 for all). A resolution of elevated HbA1c was observed in 21 of 23 patients. Summary. NASH patients showed a significant loss of body weight and amelioration of NASH status. ISG can be successfully performed in these patients and should be recommended for this subgroup.

A new composite model including metabolic syndrome, alanine aminotransferase and cytokeratin-18 for the diagnosis of non-alcoholic steatohepatitis in morbidly obese patients

BACKGROUND

Non-invasive approaches are useful to differentiate simple steatosis from non-alcoholic steatohepatitis (NASH) in obese and morbidly obese patients.

AIM

To develop a new scoring system to diagnose definitive NASH.

METHODS

Preoperative clinical and biological data including serum caspase 3-generated cytokeratin-18 fragments (CK18) and surgical liver biopsies were obtained from 464 morbidly obese patients who had undergone bariatric surgery. The cohort was divided into two groups: training group (n = 310) and validation group (n = 154). Definitive NASH was defined according to Kleiner's classification with a Non-alcoholic fatty liver disease Activity Score (NAS) ≥5.

RESULTS

  Alanine aminotransferase (ALT), CK18 fragments and the presence of metabolic syndrome were independent predictors for discriminating patients with NAS ≥5 in the training group. These three parameters were used to carry out a scoring system for the prediction of NAS ≥5. Whereas serum CK18 fragment alone had an area under the receiver operating characteristic (AUROC) curve = 0.74, AUROC curves of the scoring system were 0.88 and 0.83 in the training group and the validation group, respectively.

CONCLUSION

A simple and non-invasive composite model (the Nice Model) including metabolic syndrome, ALT and CK18 fragments is able to predict accurately a non-alcoholic fatty liver disease activity score ≥5 in morbidly obese subjects.

Nonalcoholic steatohepatitis: risk factors and diagnosis

Nonalcoholic steatohepatitis (NASH) represents the progressive form of nonalcoholic fatty liver disease with greater potential to lead to liver-related morbidity and mortality. Diagnosing NASH mandates more intensive clinical management and consideration for clinical trials. Currently, the diagnosis of NASH requires a liver biopsy, which is invasive, with drawbacks in sampling and interpretation error. Clinical risk factors for NASH include diabetes and the metabolic syndrome; however, these are not sufficiently predictive of the condition by themselves. Routine liver aminotransaminase levels are not reliable; however, novel plasma hepatocyte apoptosis markers, either alone or in combination with clinical risk factors, are potential noninvasive diagnostic tools for the future.

Metabolic consequences of intermittent hypoxia: relevance to obstructive sleep apnea

Obstructive sleep apnea (OSA) is recurrent obstruction of the upper airway leading to sleep fragmentation and intermittent hypoxia (IH) during sleep. There is growing evidence from animal models of OSA that IH is independently associated with metabolic dysfunction, including dyslipidemia and insulin resistance. The precise mechanisms by which IH induces metabolic disturbances are not fully understood. Over the last decade, several groups of investigators developed a rodent model of IH, which emulates the oxyhemoglobin profile in human OSA. In the mouse model, IH induces dyslipidemia, insulin resistance and pancreatic endocrine dysfunction, similar to those observed in human OSA. Recent reports provided new insights in possible mechanisms by which IH affects lipid and glucose metabolism. IH may induce dyslipidemia by up-regulating lipid biosynthesis in the liver, increasing adipose tissue lipolysis with subsequent free fatty acid flux to the liver, and inhibiting lipoprotein clearance. IH may affect glucose metabolism by inducing sympathetic activation, increasing systemic inflammation, increasing counter-regulatory hormones and fatty acids, and causing direct pancreatic beta-cell injury. IH models of OSA have improved our understanding of the metabolic impact of OSA, but further studies are needed before we can translate recent basic research findings to clinical practice.