Hepatic steatosis and insulin resistance: does etiology make a difference?

Metabolic characteristics of patients with MetALD: Caveats of a new definition

BACKGROUND AND AIMS

Recently, a new entity was introduced, MetALD, which includes patients with metabolic dysfunction-associated steatotic liver disease (MASLD), who consume moderate amounts of alcohol. However, little is known regarding the metabolic and clinical characteristics of these patients.

METHODS

Data from the National Health and Nutrition Examination Surveys 2017-2020 was used. Participants without valid transient elastography (TE) measurements, incomplete alcohol consumption report, or with alternative etiologies of liver steatosis were excluded.

RESULTS

A total of 6901 patients were included in the study, of which 106 (1.5%) had MetALD. Overall, MetALD patients showed a metabolic profile that was more similar to patients with alcohol related liver disease (ALD) than MASLD. Specifically, while patients with MetALD showed values in-between MASLD and ALD for body mass index (BMI), aspartate transaminase (AST), alanine transaminase (ALT), gamma glutamyltransferase (GGT) and haemoglobin A1c, they had similar high-density lipoprotein cholesterol (HDL-C), blood pressure, prevalence of diabetes and insulin resistance to ALD patients. Increasing alcohol consumption was associated with lower insulin resistance and A1c and higher triglycerides, HDL-C and blood pressure. Moreover, while AST, ALT and GGT increased with alcohol consumption, this did not translate into worse hepatic steatosis or liver fibrosis by TE.

CONCLUSIONS

MetALD patients share some characteristics with MASLD, but they resemble ALD patients more, especially after adjusting for BMI. Alcohol consumption produces a dissociation between insulin resistance and some cardiometabolic risk factors (blood pressure and HDL-C), which may make the current classification of patients challenging.

TyG-GGT is a Reliable Non-Invasive Predictor of Advanced Liver Fibrosis in Overweight or Obese Individuals

BACKGROUND

Liver fibrosis is a predisposing factor for liver cancer. This study will investigate the predictive role of the Triglyceride-glucose and Gamma-glutamyl transferase index (TyG-GGT) as a non-invasive indicator of advanced liver fibrosis in individuals with obesity or overweight.

METHOD

We enrolled patients who underwent metabolic and bariatric surgery as well as intraoperative liver biopsies at Zhejiang provincial people's hospital from August 2020 to March 2023. Clinical characteristics, comorbidities, laboratory data, and pathological variables of patients were collected and analysed. Then, we conducted logistics regression model to compare the performance of the TyG-GGT index with other 4 non-invasive models.

RESULTS

A total of 65 patients were included in this study. 43(66.2%) of them were female, with the mean body mass index (BMI) of 39.0 ± 7.3 kg/m2. Meanwhile, 24(36.9%) patients were diagnosed with diabetes. Advanced liver fibrosis were observed in 16.9% of patients, while liver cirrhosis was found in 4.6% of patients. The multivariable logistics regression showed that TyG-GGT was an independent risk factor of advanced liver fibrosis (OR = 6.989, P = 0.049). Additionally, compared to another 4 non-invasive liver fibrosis models (NFS = 0.66, FIB4 = 0.65, METS-IR = 0.68, APRI = 0.65), TyG-GGT exhibits the highest AUC value of 0.75.

CONCLUSIONS

More than one-third of patients undergoing metabolic and bariatric surgery are afflicted with nonalcoholic steatohepatitis (NASH), and a significant proportion exhibit advanced fibrosis. TyG-GGT was a potentially reliable predictor for screening individuals with overweight or obesity at high risk of advanced liver fibrosis, thus providing clinical guidance for early intervention in this targeted group.

Low cholesterol states: clinical implications and management

INTRODUCTION

Hypocholesterolemia results from genetic - both monogenic and polygenic - and non-genetic causes and can sometimes be a source of clinical concern. We review etiologies and sequelae of hypocholesterolemia and therapeutics inspired from genetic hypocholesterolemia.

AREAS COVERED

Monogenic hypocholesterolemia disorders caused by the complete absence of apolipoprotein (apo) B-containing lipoproteins (abetalipoproteinemia and homozygous hypobetalipoproteinemia) or an isolated absence of apo B-48 lipoproteinemia (chylomicron retention disease) lead to clinical sequelae. These include gastrointestinal disturbances and severe vitamin deficiencies that affect multiple body systems, i.e. neurological, musculoskeletal, ophthalmological, and hematological. Monogenic hypocholesterolemia disorders with reduced but not absent levels of apo B lipoproteins have a milder clinical presentation and patients are protected against atherosclerotic cardiovascular disease. Patients with heterozygous hypobetalipoproteinemia have somewhat increased risk of hepatic disease, while patients with PCSK9 deficiency, ANGPTL3 deficiency, and polygenic hypocholesterolemia typically have anunremarkable clinical presentation.

EXPERT OPINION

In patients with severe monogenic hypocholesterolemia, early initiation of high-dose vitamin therapy and a low-fat diet are essential for optimal prognosis. The molecular basis of monogenic hypocholesterolemia has inspired novel therapeutics to help patients with the opposite phenotype - i.e. elevated apo B-containing lipoproteins. In particular, inhibitors of PCSK9 and ANGPTL3 show important clinical impact.

Understanding NAFLD: From Case Identification to Interventions, Outcomes, and Future Perspectives

While non-alcoholic fatty liver disease (NAFLD) is a prevalent and frequent cause of liver-related morbidity and mortality, it is also strongly associated with cardiovascular disease-related morbidity and mortality, likely driven by its associations with insulin resistance and other manifestations of metabolic dysregulation. However, few satisfactory pharmacological treatments are available for NAFLD due in part to its complex pathophysiology, and challenges remain in stratifying individual patient's risk for liver and cardiovascular disease related outcomes. In this review, we describe the development and progression of NAFLD, including its pathophysiology and outcomes. We also describe different tools for identifying patients with NAFLD who are most at risk of liver-related and cardiovascular-related complications, as well as current and emerging treatment options, and future directions for research.

Analysis of the effect of glutamyltransferase on hyperlipidemia based on decision tree

Objectives

This study is designed to analyze the potential influencing factors of hyperlipidemia, and to explore the relationship between liver function indicators such as gamma-glutamyltransferase (GGT) and hyperlipidemia.

Methods

Data were derived from 7599 outpatients who visited the Department of Endocrinology of the First Hospital of Jilin University (2017-2019). A multinomial regression model is used to identify related factors of hyperlipidemia and the decision tree method is used to explore the general rules in hyperlipidemia patients and non-hyperlipidemia patients on these factors.

Results

The average of age, body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure, aspartate aminotransferase, alanine aminotransferase (ALT), GGT and glycosylated hemoglobin (HbA1c) in the hyperlipidemia group are higher than those in the non-hyperlipidemia group. In multiple regression analysis, SBP, BMI, fasting plasma glucose, 2-h postprandial blood glucose, HbA1c, ALT, GGT are associated with triglyceride. For people with HbA1c less than 6.0%, controlling GGT within 30 IU/L reduces the prevalence of hypertriglyceridemia by 4%, and for people with metabolic syndrome with impaired glucose tolerance controlling GGT within 20 IU/L reduces the prevalence of hypertriglyceridemia by 11%.

Conclusions

Even when GGT is in the normal range, the prevalence of hypertriglyceridemia increases with its gradual increase. Controlling GGT in people with normoglycemia and impaired glucose tolerance can reduce the risk of hyperlipidemia.

Antifibrotic effect and long-term outcome of SGLT2 inhibitors in patients with NAFLD complicated by diabetes mellitus

The aim of this retrospective multicenter study was to clarify the antifibrotic effect and long-term outcome of sodium glucose cotransporter 2 inhibitors (SGLT2-Is) in patients with nonalcoholic fatty liver disease (NAFLD) complicated by type 2 diabetes mellitus (T2DM). Of the 1262 consecutive patients with T2DM who recently received SGLT2-Is, 202 patients with NAFLD had been receiving SGLT2-Is for more than 48 weeks and were subjected to this analysis. Furthermore, 109 patients who had been on SGLT2-I therapy for more than 3 years at the time of analysis were assessed for the long-term effects of SGLT2-Is. Significant decreases in body weight, liver transaminases, plasma glucose, hemoglobin A1c, and Fibrosis-4 (FIB-4) index were found at week 48. Overall, the median value of FIB-4 index decreased from 1.42 at baseline to 1.25 at week 48 (p < 0.001). In the low-risk group (FIB-4 index < 1.3), there was no significant change in the FIB-4 index. In the intermediate-risk (≥1.3 and <2.67) and high-risk (≥2.67) groups, the median levels significantly decreased from 1.77 and 3.33 at baseline to 1.58 and 2.75 at week 48, respectively (p < 0.001 for both). Improvements in body weight, glucose control, liver transaminases, and FIB-4 index were found at 3 years of SGLT2-I treatment. In the intermediate-risk and high-risk groups (≥1.3 FIB-4 index), the FIB-4 index maintained a significant reduction from baseline throughout the 3 years of treatment. Conclusion: This study showed that SGLT2-Is offered a favorable effect on improvement in FIB-4 index as a surrogate marker of liver fibrosis in patient with NAFLD complicated by T2DM, especially those with intermediate and high risks of advanced fibrosis, and this antifibrotic effect is sustained for the long term.

Association of distinct γ-glutamyltransferase trajectories with incident hyperglycemia using latent class growth mixture modeling: A longitudinal cohort study of Chinese adults

AIMS

To elucidate the association between distinct latent γ-glutamyltransferase (GGT) increasing trajectories in life time and incident hyperglycemia.

METHODS

4547 subjects were followed up for 3 years (January 2016-December 2019), and data regarding fasting plasma glucose, HbA_1c, GGT, and other indices were recorded. Latent class growth mixed modeling (LCGMM) was used to analyze GGT latent trajectories.

RESULTS

A three-class quadratic model was selected as the best fit by LCGMM. Subjects were categorized into three latent classes: high-increasing (n = 98, 2.16%), low-increasing (n = 364, 8.01%), and stable (n = 4085, 89.83%) classes. Adjusted hazard ratios of hyperglycemia for the high-increasing and low-increasing classes were 1.341 (1.076-2.051) and 1.264 (1.048-1.525) when compared with stable class, respectively. Odds Ratios (ORs) of GGT slopes were confirmed in the 28-57-year age group, shaped like an "M", ranging from 1.144 (1.059, 1.237) to 2.502 (1.384-3.862). Significant differences in the associations between model-estimated GGT values and hyperglycemia incidence were observed from 28 to 51 years of age, with ORs ranging from 1.011 (1.011, 1.012) to 1.014 (1.012, 1.019).

CONCLUSIONS

Our study demonstrated that subjects in GGT increasing classes exhibited higher risks of developing hyperglycemia. A steeper GGT slope is a more effective predictor of hyperglycemia than the GGT value.

The triglycerides and glucose (TyG) index: A new marker associated with nonalcoholic steatohepatitis (NASH) in obese patients

AIM

Diagnosis of nonalcoholic steatohepatitis (NASH) relies on liver biopsy. Noninvasive tools would be useful to target patients to refer for a biopsy. We aimed to determine the diagnostic value of the triglycerides and glucose (TyG) index, an insulin-resistance indicator, to predict NASH.

METHODS

Our study included grade II-III obese patients aged 18-65 years undergoing bariatric surgery and included in the COMET (COllection of MEtabolic Tissues) biobank (NCT02861781). Liver biopsies performed during bariatric surgery were collected from the biobank along with blood derivatives. Biopsies were analysed according to the steatosis, activity and fibrosis (SAF) scoring system to diagnose NASH, nonalcoholic fatty liver disease (NAFLD), and fibrosis. Logistic regression models were performed to identify factors predicting NASH, NAFLD, and fibrosis.

RESULTS

Of 238 analysed subjects (mean age 43±12 years, 33.6% men), 29% had type 2 diabetes. Steatosis was present in 67.2%, while NASH and advanced fibrosis (stage F3) were diagnosed in 18.1% and 2.9% respectively. TyG index was independently associated with NASH (odds ratio (OR): 4.7 [95% confidence interval: 2.3;9.5] P < 0.0001), NAFLD (OR: 2.0 [1.1;3.7] P = 0.03) and stages 2-3 fibrosis (OR: 4.0 [1.5;10.8] P = 0.007). NASH was also predicted by gamma-glutamyl transferase (GGT) with an area under the ROC curve: 0.79 [0.71;0.87 P = 0.04] for GGT and TyG index combined.

CONCLUSION

In our cohort of severely obese patients, TyG index, when associated with GGT level, exhibited high diagnostic performance to predict NASH. Although validation in larger populations is needed, this result may be of considerable clinical value to predict need for liver biopsy.

Low cardiopulmonary fitness is associated with higher liver fat content and higher gamma-glutamyltransferase concentrations in the general population - "The Sedentary's Liver"

BACKGROUND

We investigated the association between low cardiorespiratory fitness and liver fat content (LFC) in the general population.

MATERIALS AND METHODS

We evaluated data from 2151 adults (51.1% women) from two population-based cohorts of the Study of Health in Pomerania (SHIP-2 and SHIP-TREND-0). We analysed the cross-sectional associations of peak oxygen uptake (VO_2peak ) with LFC, assessed by magnetic resonance imaging proton density fat fraction, as well as serum gamma-glutamyltransferase (GGT) and aminotransferase concentrations by multivariable regression models.

RESULTS

We observed significant inverse associations of VO_2peak with LFC and serum GGT, but not with serum aminotransferase levels. Specifically, a 1 L/min lower VO_2peak was associated with a 1.09% (95% confidence interval [CI]: 0.45-1.73; P = .002) higher LFC and a 0.18 μkatal/L (95% CI: 0.09-0.26; P < .001) higher GGT levels. The adjusted odds ratio (OR) for the risk of prevalent hepatic steatosis (HS) by a 1 L/min decrease in VO_2peak was 1.61 (95% CI: 1.22-2.13; P = .001). Compared to subjects with high VO_2peak , obese and overweight individuals with low VO_2peak had 1.78% (95% CI: 0.32-3.25; P = .017) and 0.94% (95% CI: 0.15-1.74; P = .021) higher mean LFC, respectively. Compared to those with high VO_2peak , low VO_2peak was independently associated with a higher risk of prevalent HS in the obese (adjusted-OR 2.29, 95% CI=1.48-3.56; P < .001) and overweight (adjusted OR 1.57, 95% CI=1.16-2.14; P = .04) groups.

CONCLUSIONS

Lower VO_2peak was significantly associated with greater LFC and higher serum GGT levels in a population-based cohort of adult individuals. Our results suggest that low VO_2peak might be a risk factor for HS.

Clinical characteristics of metabolic associated fatty liver disease (MAFLD) in subjects with myotonic dystrophy type 1 (DM1)

BACKGROUND

Myotonic dystrophy type 1 (DM1) is a rare inherited neuromuscular disease associated with insulin resistance, and its association with metabolically associated fatty liver disease (MAFLD) has never been explored in prospective studies. The aim of this study was to assess the clinical features of MAFLD in DM1 patients.

METHODS

We investigated the prevalence and the diagnostic features of MAFLD in a cohort of 29 outpatient fully characterized DM1 patients; afterward, we compared the selected cohort of DM1-MAFLD individuals with a propensity-matched cohort of non-DM1-MAFLD RESULTS: 13/29 (44.83%) DM1 patients received a clinical diagnosis of MAFLD. Compared to DM1 patients with normal liver, DM1-MAFLD individuals showed a higher male prevalence (p = 0.008), BMI (p = 0.014), HOMA score (p = 0.012), and GGT levels (p = 0.050). The statistical comparison showed that the DM1-MAFLD group had a more severe MAFLD according to the FIB4 score than non-DM1-MAFLD patients. This association of a more severe form of liver disease with DM1 remained significant after logistic regression analysis (OR: 6.12, 95% CI 1.44- 26.55).

A clinical model to predict fibrosis on liver biopsy in paediatric subjects with nonalcoholic fatty liver disease

The incidence of nonalcoholic fatty liver disease (NAFLD) in children is rapidly increasing. Liver fibrosis is a poor prognostic feature that independently predicts cirrhosis. The time that intercedes the first medical encounter and biopsy is rate-limiting to multi-modal treatment. This study aimed to identify non-invasive parameters to predict advanced NAFLD and fibrosis. We conducted a single-center, retrospective 10-year analysis of 640 paediatric patients who underwent liver biopsy. 55 patients, age 3-21 years, had biopsy-confirmed NAFLD. We assessed primary outcomes, NAFLD activity score (NAS) and fibrosis scores, against non-invasive parameters by linear regression, by using binary cutoff values, and by a multivariate logistic regression fibrosis prediction model. NAS correlated with platelets and female sex. Fibrosis scores correlated with platelet counts, gamma glutamyl transferase (GGT), and ultrasound shear wave velocity. 25-hydroxy-vitamin D and GGT differentiated mild versus moderate-to-advanced fibrosis. Our multivariate logistical regression model-based scoring system predicted F2 or higher (parameters: BMI%, vitamin D, platelets, GGT), with sensitivity and specificity of 0.83 and 0.95 (area under the ROC curve, 0.944). We identify a clinical model to identify high-risk patients for expedited biopsy. Stratifying patients to abbreviate time-to-biopsy can attenuate delays in aggressive therapy for high-risk patients.

HCV eradication in recurrent hepatitis C after liver transplantation normalizes enhanced endothelial activation

The increased risk of cardiovascular disease (CVD) conferred by hepatitis C virus (HCV) is especially relevant after liver transplantation (LT), but its mechanism is still not well defined. This study aimed to evaluate the influence of HCV eradication in inflammatory and endothelial activation markers after LT. We evaluated inflammatory (TNF-alfa, IL-6, IL-8, and MCP-1) and endothelial activation (E-selectin, ICAM-1, VCAM-1, and MMP-9) markers before and after eradication in 45 LT recipients with HCV infection (LT+/HCV+) and 44 non-transplanted HCV-infected patients (LT-/HCV+). We also considered an additional group of 40 LT recipients without HCV infection (LT+/HCV-). LT+/HCV+ patients presented a higher endothelial activation status before eradication compared with LT+/HCV- patients. However, levels of E-selectin, ICAM-1, VCAM-1, and MMP-9 were comparable between LT+/HCV+ and LT-/HCV+ patients before eradication. HCV eradication decreased ICAM-1 (5466.55 pg/ml vs. 3354.88 pg/ml, P < 0.001) and VCAM-1 (10456.52 pg/ml vs. 6658.85 pg/ml, P < 0.001) levels in LT+/HCV+ and LT-/HCV+ patients. Remarkably, HCV eradication restored levels of endothelial activation markers of LT+/HCV+ patients compared with that of LT+/HCV- patients. HCV plays a major role in endothelial dysfunction after LT. Furthermore, HCV eradication restores endothelial activation despite the exposure to immunosuppressive therapy.

Association of PAF and its metabolic enzymes with GGT and the Fatty Liver Index in healthy volunteers

BACKGROUND

Platelet-activating factor (PAF) is a lipid inflammatory mediator implicated in liver disease. Its main biosynthetic enzymes are cytidine diphosphate (CDP)-choline:1-alkyl-2-acetyl-sn-glycerol-cholinephosphotransferase (PAF-CPT) and acetyl-coenzyme A: lyso-PAF-acetyltransferases (Lyso-PAF-AT), while PAF acetylhydrolase (PAF-AH) and lipoprotein-associated phospholipase A2 (Lp-PLA2) degrade PAF.

OBJECTIVE

To explore the relation of PAF metabolism with liver diseases and non-alcoholic fatty liver disease, as reflected by the fatty liver index (FLI).

METHODS

In 106 healthy volunteers, PAF concentration, the activity of its metabolic enzymes, and gamma-glutamyl transferase (GGT) were measured in whole blood, leukocytes, and serum, respectively, and the FLI was calculated. Partial correlations and linear regression models were used.

RESULTS

In males, serum GGT activity was positively correlated with abdominal fat (as assessed by analysis of a manually defined region of interest in dual-energy X-ray absorptiometry), triacylglycerols, bound-PAF, and Lp-PLA2, while the FLI was positively correlated with Lp-PLA2 activity. In females, serum GGT activity was negatively associated with high-density lipoprotein cholesterol (HDL-C) (age-adjusted correlations, all p<0.05). Lp-PLA2 was a significant determinant of serum GGT activity in males after controlling for age, low-density lipoprotein cholesterol (LDL-C), and abdominal fat. The addition of bound-PAF in the model significantly increased the explained variance of serum GGT activity (total variance explanation 30%).

CONCLUSION

Bound-PAF and Lp-PLA2 activity predicted serum GGT activity, while Lp-PLA2 was also related to FLI. Our findings shed light on the metabolic pathways linking Lp-PLA2 to other atherosclerosis and/or oxidative markers, such as HDL-C, LDL-C, GGT, and FLI, and underline the important role of PAF.

Normalization of γ-glutamyl transferase levels is associated with better metabolic control in individuals with nonalcoholic fatty liver disease

BACKGROUND

The normalization of liver biochemical parameters usually reflects the histological response to treatment for nonalcoholic fatty liver disease (NAFLD). Researchers have not clearly determined whether different liver enzymes exhibit various metabolic changes during the follow-up period in patients with NAFLD.

METHODS

We performed a retrospective analysis of patients with NAFLD who were receiving therapy from January 2011 to December 2019. Metabolism indexes, including glucose levels, lipid profiles, uric acid levels and liver biochemical parameters, were measured. Magnetic resonance imaging-based proton density fat fraction (MRI-PDFF) and liver ultrasound were used to evaluate steatosis. All patients received recommendations for lifestyle modifications and guideline-recommended pharmacological treatments with indications for drug therapy for metabolic abnormalities.

RESULTS

Overall, 1048 patients with NAFLD were included and received lifestyle modification recommendations and pharmaceutical interventions, including 637 (60.7%) patients with abnormal GGT levels and 767 (73.2%) patients with abnormal ALT levels. Patients with concurrent ALT and GGT abnormalities presented higher levels of metabolism indexes and higher liver fat content than those in patients with single or no abnormalities. After 12 months of follow-up, the cumulative normalization rate of GGT was considerably lower than that of ALT (38% vs. 62%, P < 0.001). Greater weight loss resulted in higher cumulative normalization rates of GGT and ALT. Weight loss (OR = 1.21, 95% CI 1.11-1.32, P < 0.001), ALT normalization (OR = 2.75, 95% CI 1.41-5.36, P = 0.01) and lower TG and HOMA-IR values (OR = 2.03, 95% CI 1.11-3.71, P = 0.02; OR = 2.04, 95% CI 1.07-3.89, P = 0.03) were independent protective factors for GGT normalization. Elevated baseline GGT (OR = 0.99, 95% CI 0.98-0.99, P = 0.01) was a risk factor.

CONCLUSIONS

For NAFLD patients with concurrently increased ALT and GGT levels, a lower normalization rate of GGT was observed, rather than ALT. Good control of weight and insulin resistance was a reliable predictor of GGT normalization.

Renaming NAFLD to MAFLD: Could the LDE System Assist in This Transition?

Our understanding of fatty liver syndromes and their relationship with the metabolic syndrome has improved over recent decades and, paralleling this, we are now at the dawn of the NAFLD (nonalcoholic fatty liver disease) to MAFLD (metabolic-associated fatty liver disease) transition. The pitfalls of NAFLD diagnosis, together with disappointing results in therapeutic trials, and the inconsistencies and risks inherent in a "negative" definition (such as "nonalcoholic") as opposed to a "positive" one (i.e., "metabolic") are predicted to facilitate the proposed renaming of NAFLD to MAFLD. However, a premature change of terminology would not necessarily address major unmet needs in this area, and may even become counterproductive. As an aid to selecting more homogeneous cohorts of patients, I propose the LDE (Liver, Determinants, Extra-hepatic) classification system which, in principle, may help to assess the natural course of disease as well as the efficacy of novel drugs in patients with NAFLD/MAFLD.

Fatty liver index and risk of diabetes incidence: A systematic review and dose-response meta-analysis of cohort studies

AIMS

Fatty Liver Index (FLI) is a surrogate index for diagnosis of Fatty Liver Disease (FLD). We performed a dose-response meta-analysis to investigate the relationship between FLI and diabetes incidence in prospective cohort studies.

METHODS

We conducted a systematic search of articles up to November 2019 in PubMed, SCOPUS, Cochrane library, and Embase. Hazard Ratios (HRs) with corresponding 95% confidence intervals (CIs) of studies were pooled using meta-analysis with DerSimonian and Laird random-effects models to find combined HRs. Dose-response effect of this relationship was also assessed.

RESULTS

Twenty-seven studies providing 70,918 participants were included in the meta-analysis. Pooled results showed that the highest category of FLI was associated with an increased incidence of diabetes [HR: 2.88, 95% CI: 2.18-3.81; P for heterogeneity: 0.001]. Subgroup analysis based on sex, continent, and the quality of study could not explain the source of heterogeneity. The pooled HR from the random-effects dose-response model indicated a significant association between FLI level and risk of diabetes incidence (Coef=0.0239, p=0.001).

CONCLUSION

Our dose-response meta-analysis revealed a direct relationship between FLI and HR of diabetes incidence.

Phenotypic Differences Between Polygenic and Monogenic Hypobetalipoproteinemia

OBJECTIVE

Primary hypobetalipoproteinemia is characterized by LDL-C (low-density lipoprotein cholesterol) concentrations below the fifth percentile. Primary hypobetalipoproteinemia mostly results from heterozygous mutations in the APOB (apolipoprotein B) and PCSK9 genes, and a polygenic origin is hypothesized in the remaining cases. Hypobetalipoproteinemia patients present an increased risk of nonalcoholic fatty liver disease and steatohepatitis. Here, we compared hepatic alterations between monogenic, polygenic, and primary hypobetalipoproteinemia of unknown cause. Approach and Results: Targeted next-generation sequencing was performed in a cohort of 111 patients with hypobetalipoproteinemia to assess monogenic and polygenic origins using an LDL-C-dedicated polygenic risk score. Forty patients (36%) had monogenic hypobetalipoproteinemia, 38 (34%) had polygenic hypobetalipoproteinemia, and 33 subjects (30%) had hypobetalipoproteinemia from an unknown cause. Patients with monogenic hypobetalipoproteinemia had lower LDL-C and apolipoprotein B plasma levels compared with those with polygenic hypobetalipoproteinemia. Liver function was assessed by hepatic ultrasonography and liver enzymes levels. Fifty-nine percent of patients with primary hypobetalipoproteinemia presented with liver steatosis, whereas 21% had increased alanine aminotransferase suggestive of liver injury. Monogenic hypobetalipoproteinemia was also associated with an increased prevalence of liver steatosis (81% versus 29%, P<0.001) and liver injury (47% versus 0%) compared with polygenic hypobetalipoproteinemia.

CONCLUSIONS

This study highlights the importance of genetic diagnosis in the clinical care of primary hypobetalipoproteinemia patients. It shows for the first time that a polygenic origin of hypobetalipoproteinemia is associated with a lower risk of liver steatosis and liver injury versus monogenic hypobetalipoproteinemia. Thus, polygenic risk score is a useful tool to establish a more personalized follow-up of primary hypobetalipoproteinemia patients.

Human and molecular genetics shed lights on fatty liver disease and diabetes conundrum

The causal role of abdominal overweight/obesity, insulin resistance and type 2 diabetes (T2D) on the risk of fatty liver disease (FLD) has robustly been proven. A consensus of experts has recently proposed the novel definition of 'metabolic dysfunction-associated fatty liver disease, MAFLD' instead of 'nonalcoholic fatty liver disease, NAFLD', emphasizing the central role of dysmetabolism in the disease pathogenesis. Conversely, a direct and independent contribution of FLD per se on risk of developing T2D is still a controversial topic. When dealing with FLD as a potential risk factor for T2D, it is straightforward to think of hepatic insulin resistance as the most relevant underlying mechanism. Emerging evidence supports genetic determinants of FLD (eg PNPLA3, TM6SF2, MBOAT7, GCKR, HSD17B13) as determinants of insulin resistance and T2D. However, recent studies highlighted that the key molecular mechanism of dysmetabolism is not fat accumulation per se but the degree of hepatic fibrosis (excess liver fat content-lipotoxicity), leading to reduced insulin clearance, insulin resistance and T2D. A consequence of these findings is that drugs that will ameliorate liver fat accumulation and fibrosis in principle may also exert a beneficial effect on insulin resistance and risk of T2D in individuals with FLD. Finally, initial findings show that these genetic factors might be directly implicated in modulating pancreatic beta-cell function, although future studies are needed to fully understand this relationship.

The effect of adiponectin in the pathogenesis of non-alcoholic fatty liver disease (NAFLD) and the potential role of polyphenols in the modulation of adiponectin signaling

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases worldwide, as it affects up to 30 % of adults in Western countries. Moreover, NAFLD is also considered an independent risk factor for cardiovascular diseases. Insulin resistance and inflammation have been identified as key factors in the pathophysiology of NAFLD. Although the mechanisms associated with the development of NAFLD remain to be fully elucidated, a complex interaction between adipokines and cytokines appear to play a crucial role in the development of this condition. Adiponectin is the most common adipokine known to be inversely linked with insulin resistance, lipid accumulation, inflammation and NAFLD. Consequently, the focus has been on the use of new therapies that may enhance hepatic expression of adiponectin downstream targets or increase the serum levels of adiponectin in the treatment NAFLD. While currently used therapies show limited efficacy in this aspect, accumulating evidence suggest that various dietary polyphenols may stimulate adiponectin levels, offering potential protection against the development of insulin resistance, inflammation and NAFLD as well as associated conditions of metabolic syndrome. As such, this review provides a better understanding of the role polyphenols play in modulating adiponectin signaling to protect against NAFLD. A brief discussion on the regulation of adiponectin during disease pathophysiology is also covered to underscore the potential protective effects of polyphenols against NAFLD. Some of the prominent polyphenols described in the manuscript include aspalathin, berberine, catechins, chlorogenic acid, curcumin, genistein, piperine, quercetin, and resveratrol.

Epidemiology and pathophysiology of the association between NAFLD and metabolically healthy or metabolically unhealthy obesity

The prevalence of nonalcoholic fatty liver disease (NAFLD) is continuing to rise in many countries, paralleling the epidemic of obesity worldwide. In the last years, the concept of metabolically healthy obesity [MHO, generally defined as obesity without metabolic syndrome (MetS)] has raised considerable scientific interest. MHO is a complex phenotype with risks intermediate between metabolically healthy individuals with normal-weight (NWMH) and patients who are obese and metabolically unhealthy (MUO, i.e. obesity with MetS). In this review we aimed to examine the association and pathophysiological link of NAFLD with MHO and MUO. Compared to NWMH individuals, patients with obesity, regardless of the presence of MetS features, are at higher risk of all-cause mortality and cardiovascular events. Moreover, MHO patients have a greater risk of NAFLD development and progression compared to NWMH individuals. However, this risk is generally lower than that of MUO patients, suggesting a stronger adverse effect of coexisting MetS disorders than obesity per se on the severity of NAFLD. Nevertheless, since MHO is a dynamic state (with a significant proportion of MHO subjects progressing to MUO over time) and NAFLD itself may predict the transition from MHO to MUO, we believe that any effort should be made to identify NAFLD in all obese individuals, although they appear to be "metabolically healthy". Future research is needed to better understand the role of NAFLD and other pathogenic factors potentially involved in the transition from MHO to MUO and to elucidate how this transition may affect the presence and severity of NAFLD.

Hypobetalipoproteinemia and abetalipoproteinemia: liver disease and cardiovascular disease

PURPOSE OF REVIEW

Several mutations in the apolipoprotein (apo) B, proprotein convertase subtilisin kexin 9 (PCSK9) and microsomal triglyceride transfer protein genes result in low or absent levels of apoB and LDL cholesterol (LDL-C) in plasma which cause familial hypobetalipoproteinemia (FHBL) and abetalipoproteinemia (ABL). Mutations in the angiopoietin-like protein 3 ANGPTL3 gene cause familial combined hypolipidemia (FHBL2). Clinical manifestations range from none-to-severe, debilitating and life-threatening disorders. This review summarizes recent genetic, metabolic and clinical findings and management strategies.

RECENT FINDINGS

Fatty liver, cirrhosis and hepatocellular carcinoma have been reported in FHBL and ABL probably due to decreased triglyceride export from the liver. Loss of function mutations in PCSK-9 and ANGPTL3 cause FHBL but not hepatic steatosis. In 12 case-control studies with 57 973 individuals, an apoB truncation was associated with a 72% reduction in coronary heart disease (odds ratio, 0.28; 95% confidence interval, 0.12-0.64; P = 0.002). PCSK9 inhibitors lowered risk of cardiovascular events in large, randomized trials without apparent adverse sequelae.

SUMMARY

Mutations causing low LDL-C and apoB have provided insight into lipid metabolism, disease associations and the basis for drug development to lower LDL-C in disorders causing high levels of cholesterol. Early diagnosis and treatment is necessary to prevent adverse sequelae from FHBL and ABL.

Exogenous natural EPA-enriched phosphatidylcholine and phosphatidylethanolamine ameliorate lipid accumulation and insulin resistance via activation of PPARα/γ in mice

Dietary eicosapentaenoic acid in the form of phosphatidylcholine and phosphatidylethanolamine improves lipid accumulation and insulin resistance via activation of PPARα/γ.

Overview of the Pathogenesis, Genetic, and Non-Invasive Clinical, Biochemical, and Scoring Methods in the Assessment of NAFLD

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease worldwide. It represents a range of disorders, including simple steatosis, nonalcoholic steatohepatitis (NASH), and liver cirrhosis, and its prevalence continues to rise. In some cases, hepatocellular carcinoma (HCC) may develop. The develop;ment of non-invasive diagnostic and screening tools is needed, in order to reduce the frequency of liver biopsies. The most promising methods are those able to exclude advanced fibrosis and quantify steatosis. In this study, new perspective markers for inflammation, oxidative stress, apoptosis, and fibrogenesis; emerging scoring models for detecting hepatic steatosis and fibrosis; and new genetic, epigenetic, and multiomic studies are discussed. As isolated biochemical parameters are not specific or sensitive enough to predict the presence of NASH and fibrosis, there is a tendency to use various markers and combine them into mathematical algorithms. Several predictive models and scoring systems have been developed. Current data suggests that panels of markers (NAFLD fibrosis score, Fib-4 score, BARD score, and others) are useful diagnostic modalities to minimize the number of liver biopsies. The review unveils pathophysiological aspects related to new trends in current non-invasive biochemical, genetic, and scoring methods, and provides insight into their diagnostic accuracies and suitability in clinical practice.

Is nonalcoholic fatty liver disease associated with the development of prostate cancer? A nationwide study with 10,516,985 Korean men

Background

Growing evidence supports that prostate cancer (PCa) is a metabolic syndrome-related cancer, but the evidence is lacking regarding the association between nonalcoholic fatty liver disease (NAFLD) and PCa. We aimed to investigate whether PCa is related with NAFLD in Korean adults.

Methods

Data from the National Health Insurance Corporation between 2009 and 2012 were analyzed using multivariate logistic regression method. NALFD was defined based on the fatty liver index (FLI) and hepatic steatosis index (HSI). Newly diagnosed PCa was identified using the claims data.

Results

NAFLD based on FLI and HSI was identified in 2,002,375 (19%) and 2,629,858 (25%) of 10,516,985 subjects, respectively. Each FLI ≥ 60 and HSI ≥ 36 was independently associated with the development of PCa after adjusting for other confounders (hazard ratio (HR) 1.09, 95% CI: 1.06–1.12 and HR 1.19, 95% CI: 1.16–1.23). The association was more prominent among those who were older (FLI, ≥ 65 years old and HSI, ≥ 40 years old), were not currently smoking, were presently consuming alcohol (< 30g/day) and had null components of metabolic syndrome than each counterpart. Non-obese persons with NAFLD defined by HSI had a higher risk of developing PCa than those with body mass index > 25 Kg/m².

Conclusions

NAFLD defined by FLI or HSI may help identify high-risk individuals for developing PCa particular in the elderly, even in the absence of obesity or metabolic syndrome. Future studies on this topic should necessarily be repeated based on ultrasonographic findings.

Hypertension, diabetes, atherosclerosis and NASH: Cause or consequence?

Non-alcoholic fatty liver disease (NAFLD) has become one of the most common forms of chronic liver disease worldwide and its prevalence is expected to continue rising. NAFLD has traditionally been considered a consequence of metabolic syndrome (MetS). However, the link between NAFLD and MetS components, especially type 2 diabetes mellitus (T2DM), hypertension (HTN), and cardiovascular disease (CVD) is more complex than previously thought. Indeed, the adverse effects of NAFLD extend far beyond the liver, with a large body of clinical evidence now suggesting that NAFLD may precede and/or promote the development of T2DM, HTN and atherosclerosis/CVD. The risk of developing these cardiometabolic diseases parallels the underlying severity of NAFLD. Accumulating evidence suggests that the presence and severity of NAFLD is associated with an increased risk of incident T2DM and HTN. Moreover, long-term prospective studies indicate that the presence and severity of NAFLD independently predicts fatal and nonfatal CVD events. In this review, we critically discuss the rapidly expanding body of clinical evidence that supports the existence of a bi-directional relationship between NAFLD and various components of MetS, particularly T2DM and HTN, as well as the current knowledge regarding a strong association between NAFLD and CVD morbidity and mortality. Finally, we discuss the most updated putative biological mechanisms through which NAFLD may contribute to the development of HTN, T2DM and CVD.

Association between plasma gamma-glutamyltransferase fractions and metabolic syndrome among hypertensive patients

Among the risk factors associated to metabolic syndrome (MetS), hypertension shows the highest prevalence in Italy. We investigated the relationship between the newly identified serum γ-glutamyltransferase (GGT) fractions, b- s- m- f-GGT, and risk factors associated to MetS in hypertensive patients. A total of ninety-five consecutive hypertensive patients were enrolled. GGT fractions were analysed by gel-filtration chromatography, and hepatic steatosis was evaluated by ultrasound. MetS was diagnosed in 36% of patients. Considering the whole group, b- and f-GGT showed the highest positive correlation with BMI, glucose, triglycerides and insulin, and the highest negative correlation with HDL cholesterol. While both serum triglycerides and insulin were independently associated with b-GGT levels, only triglycerides were independently associated with f-GGT. The values of b-GGT activity increased with steatosis grade (g0 = 1.19; g2 = 3.29; ratio g2/g0 = 2.75, p < 0.0001 linear trend). Patients with MetS showed higher levels of b-GGT, m-GGT and f-GGT [median (25^th-75^th) U/L: 3.19 (1.50-6.59); 0.55 (0.26-0.81); 10.3 (9.1-13.6); respectively] as compared to subjects presenting with one or two MetS criteria [1.75 (0.95-2.85), p < 0.001; 0.33 (0.19-0.60), p < 0.05; 8.8 (7.0-10.6), p < 0.001]. Our data point to a potential role for b- and f-GGT fractions in identifying MetS patients among hypertensive subjects, thus providing a minimally invasive blood-based tool for MetS diagnosis.

GLP-1 receptor agonist, liraglutide, ameliorates hepatosteatosis induced by anti-CD3 antibody in female mice

AIMS

Hepatosteatosis is mainly induced by obesity and metabolic disorders, but various medications also induce hepatosteatosis. The administration of anti-CD3 antibody was shown to induce hepatosteatosis, but changes in lipid and glucose metabolism remain unclear. We investigated the mechanism of hepatosteatosis induced by anti-CD3 antibody and the effects of glucagon-like peptide-1 (GLP-1) receptor agonist that was recently shown to affect immune function in metabolic disorders.

METHODS

Anti-CD3 antibody was administered to female BALB/c and C.B-17-scid mice with or without reconstitution by naïve CD4-positive splenocytes. Hepatic lipid content, serum lipid profile and glucose tolerance were evaluated. Splenic CD4-positive T lymphocytes were stimulated with the GLP-1R agonist, liraglutide, and cytokine production was measured. The effect of liraglutide on metabolic parameters in vivo was investigated in a T-cell activation-induced hepatosteatosis model.

RESULTS

The administration of anti-CD3 antibody induced hepatosteatosis, hyperlipidemia, and glucose intolerance. C.B-17-scid mice reconstituted with CD4-positive T lymphocytes developed hepatosteatosis induced by anti-CD3 antibody. Liraglutide suppressed CD4-positive T lymphocyte cytokine expression in vitro and in vivo, and improved hepatosteatosis, glucose tolerance, and insulin sensitivity.

CONCLUSIONS

Liraglutide suppressed the activation of CD4-positive T lymphocytes, and improved hepatosteatosis and metabolic disorders induced by T-cell activation in female mice.

Serum apoB levels independently predict the development of non-alcoholic fatty liver disease: A 7-year prospective study

BACKGROUND & AIMS

Cross-sectional studies have shown that apolipoprotein B (apoB) is positively associated with the prevalence of non-alcoholic fatty liver disease (NAFLD). This study aimed to investigate the prospective relationship between the serum apoB levels and the development of NAFLD in a Chinese population.

METHODS

A cohort of 7077 initially NAFLD-free participants was enrolled in this prospectively study. The incidence of NAFLD was calculated among participants with different baseline serum apoB quintiles. Cox proportional hazards regression analyses were conducted to calculate the risks for incident NAFLD.

RESULTS

During 41 555 person-year follow-ups, 1139 incident NAFLD cases were identified. The baseline apoB levels were linear and positively correlated with NAFLD incidence. The incidence was 16.99, 22.63, 24.73, 37.51 and 42.77 per 1000 person-year follow-up for participants with baseline apoB levels in quintiles 1-5, respectively. Compared with participants with baseline apoB levels in quintile 1, the hazard ratios (95% confidence interval) for incident NAFLD were 1.353 (1.100-1.663), 1.482 (1.207-1.820), 2.232 (1.832-2.720) and 2.543 (2.082-3.106) for participants with baseline apoB levels in quintile 2-5, respectively. The hazard ratios were attenuated but remained statistically significant after adjusting for age, gender, body mass index and variables associated with metabolic syndrome.

CONCLUSION

Elevated serum apoB levels independently predict an increased risk for incident NAFLD.

Hepatic lipid accumulation: cause and consequence of dysregulated glucoregulatory hormones

Fatty liver can be diet, endocrine, drug, virus or genetically induced. Independent of cause, hepatic lipid accumulation promotes systemic metabolic dysfunction. By acting as peroxisome proliferator-activated receptor (PPAR) ligands, hepatic non-esterified fatty acids upregulate expression of gluconeogenic, beta-oxidative, lipogenic and ketogenic genes, promoting hyperglycemia, hyperlipidemia and ketosis. The typical hormonal environment in fatty liver disease consists of hyperinsulinemia, hyperglucagonemia, hypercortisolemia, growth hormone deficiency and elevated sympathetic tone. These endocrine and metabolic changes further encourage hepatic steatosis by regulating adipose tissue lipolysis, liver lipid uptake, de novo lipogenesis (DNL), beta-oxidation, ketogenesis and lipid export. Hepatic lipid accumulation may be induced by 4 separate mechanisms: (1) increased hepatic uptake of circulating fatty acids, (2) increased hepatic de novo fatty acid synthesis, (3) decreased hepatic beta-oxidation and (4) decreased hepatic lipid export. This review will discuss the hormonal regulation of each mechanism comparing multiple physiological models of hepatic lipid accumulation. Nonalcoholic fatty liver disease (NAFLD) is typified by increased hepatic lipid uptake, synthesis, oxidation and export. Chronic hepatic lipid signaling through PPARgamma results in gene expression changes that allow concurrent activity of DNL and beta-oxidation. The importance of hepatic steatosis in driving systemic metabolic dysfunction is highlighted by the common endocrine and metabolic disturbances across many conditions that result in fatty liver. Understanding the mechanisms underlying the metabolic dysfunction that develops as a consequence of hepatic lipid accumulation is critical to identifying points of intervention in this increasingly prevalent disease state.

Adiponectin deficiency rescues high-fat diet-induced hepatic injury, apoptosis and autophagy loss despite persistent steatosis

Background &aims:Low levels of adiponectin (APN), an adipose-derived adipokine, are associated with obesity and non-alcoholic steatohepatitis although its role in high-fat diet-induced hepatic injury and steatosis remains unclear. Here we hypothesized that APN deficiency alters fat diet-induced hepatic function. To this end, we examined the effect of APN deficiency on high-fat diet-induced hepatic injury, apoptosis and steatosis.

METHODS

Adult wild type and APN knockout mice were fed a low- or high-fat diet for 20 weeks. Serum levels of liver enzymes aspartate aminotransferase (AST), alanine aminotransferase (ALT), cholesterol, hepatic triglycerides, steatosis, pro-inflammatory cytokines, apoptosis and autophagy were examined.

RESULTS

High-fat feeding led to elevated body (48.2%) and liver weights (18.8%), increased levels of ALT (87.8%), serum cholesterol (104.4%), hepatic triglycerides (305.6%) and hepatic fat deposition as evidenced by Oil Red O staining, along with a reduced AST/ALT ratio and unchanged AST. Although APN knockout itself did not affect hepatic function and morphology, it reconciled fat diet-induced hepatic injury (P<0.05 vs WT-HF group) without reversing changes in body and liver weights, serum cholesterol and hepatic steatosis. In addition, fat diet intake promoted AMPK phosphorylation, p62 accumulation and apoptosis, including elevated Bax and cleaved Caspase-3 and downregulated Bcl-2, along with suppressed phosphorylation of Akt, STAT3 and JNK, and the autophagy makers Atg7, Beclin-1 and LC3B (P<0.05 vs WT-LF group) without affecting hepatic interlelukin-6 and tumor necrosis factor-α levels, the effects were reversed or significantly attenuated by APN knockout (P<0.05 vs WT-HF group). In vitro study using HepG2 cells revealed that STAT3 activation rescued palmitic acid-induced cell injury whereas STAT3 inhibition nullified APN knockdown-offered beneficial effects.

CONCLUSIONS

Our results revealed that high-fat diet intake promotes hepatic steatosis, apoptosis and interrupted autophagy. APN knockout elicits protective effect against hepatic injury possibly associated with autophagy regulation despite persistent hepatic steatosis.

Pathogenesis of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common and important chronic liver disease in the world. As the prevalence of obesity increases in adults and children, the incidence of NAFLD has increased rapidly, reaching 17% to 33%. NAFLD is clinically divided into two forms: simple fatty liver (SFL) and non-alcoholic steatohepatitis (NASH), with NASH accounting for 1/3-1/2 of all NAFLD cases. The probability of developing cirrhosis is 0.6%-3.0% in patients with SFL for 10-20 years, and as high as 15%-25% in patients with NASH for 10-15 years. Approximately 1% of cirrhosis cases develop hepatocellular carcinoma each year. The pathogenesis of NAFLD is still not completely clear. It is generally believed that age, sex, obesity, insulin resistance, cytokines, gene polymorphism, and intestinal microflora are involved in the pathogenesis of NAFLD. An in-depth understanding of the pathogenesis of NAFLD can provide a basis for treatment of this disease. In recent years, cytokines or genes have been reported as targets for NAFLD treatment with appreciated effects. Since there is currently no specific treatment for NAFLD, targeted therapy may have a profound impact on the prognosis of the disease.

Role of γ-glutamyl transferase levels in prediction of high cardiovascular risk among patients with non-alcoholic fatty liver disease

BACKGROUND & OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) is an important cause of elevated liver functions. There is evidence showing an association between NAFLD and subclinical atherosclerosis independent of traditional risk factors. We undertook this retrospective study to determine the association of Framingham cardiovascular risk scoring system with liver function tests and inflammatory markers and to find the role of liver function tests in determination of CVD risk among non-obese and non-diabetic subjects with non-alcoholic fatty liver disease.

METHODS

A total of 2058 patients were included in the study. Framingham cardiovascular risk scoring was done of all patients according to the age, gender, systolic blood pressure, serum total cholesterol and HDL cholesterol levels, smoking and antihypertensive medication history. Liver function test, lipid profile, insulin, uric acid, ferritin levels, etc. were determined.

RESULTS

According to the ultrasonography findings, patients were grouped as without any fatty infiltration of the liver (control group) (n=982), mild (n= 473), moderate (n=363) and severe fatty liver disease (n= 240) groups. In severe fatty liver disease group, the mean Framingham cardiovascular risk score was significantly higher than that of other groups. t0 here was a positive correlation between GGT, uric acid and ferritin levels with Framingham cardiovascular score. In multivariate analysis, high GGT levels were positively associated with high-risk disease presence (OR: 3.02, 95% CI: 2.62-3.42) compared to low GGT levels independent of the age and sex.

INTERPRETATION & CONCLUSIONS

Cardiovascular disease risk increases with the presence and stage of fatty liver disease. Our findings showed a positive correlation between elevated GGT levels and Framingham cardiovascular risk scoring system among non-diabetic, non-obese adults which could be important in clinical practice. Though in normal limits, elevated GGT levels among patients with fatty liver disease should be regarded as a sign of increased cardiovascular disease risk. Larger studies are warranted to elucidate the role of GGT in prediction of cardiovascular risk.

Fatty liver is associated with an increased risk of diabetes and cardiovascular disease - Evidence from three different disease models: NAFLD, HCV and HIV

Fatty liver, which frequently coexists with necro-inflammatory and fibrotic changes, may occur in the setting of nonalcoholic fatty liver disease (NAFLD) and chronic infections due to either hepatitis C virus (HCV) or human immunodeficiency virus (HIV). These three pathologic conditions are associated with an increased prevalence and incidence of cardiovascular disease (CVD) and type 2 diabetes (T2D). In this multidisciplinary clinical review, we aim to discuss the ever-expanding wealth of clinical and epidemiological evidence supporting a key role of fatty liver in the development of T2D and CVD in patients with NAFLD and in those with HCV or HIV infections. For each of these three common diseases, the epidemiological features, pathophysiologic mechanisms and clinical implications of the presence of fatty liver in predicting the risk of incident T2D and CVD are examined in depth. Collectively, the data discussed in this updated review, which follows an innovative comparative approach, further reinforce the conclusion that the presence of fatty/inflamed/fibrotic liver might be a shared important determinant for the development of T2D and CVD in patients with NAFLD, HCV or HIV. This review may also open new avenues in the clinical and research arenas and paves the way for the planning of future, well-designed prospective and intervention studies.

Effect of Intragastric Balloons on Liver Enzymes: A Systematic Review and Meta-Analysis

BACKGROUND

Intragastric balloons (IGBs) are safe and effective in inducing weight loss in obese patients. The objective of this study was to review and analyze the available data of the effect of IGB on markers of nonalcoholic fatty liver disease (NAFLD) and liver enzymes.

METHODS

Searches were performed of MEDLINE and Embase databases from inception through January 2016. Study inclusion criteria were the following: ≥5 overweight or obese adult patients undergoing intragastric balloon placement, with liver tests [alanine aminotransferase (ALT) or gamma-glutamyl transpeptidase (GGT)] or markers of NAFLD (e.g., imaging, biopsy) reported before balloon insertion and after balloon removal at 6 months.

RESULTS

Nine observational studies and one randomized trial were identified. ALT decreased by -10.02 U/l (95 % CI, -13.2, -6.8), GGT decreased by -9.82 U/l (95 % CI, -12.9, -6.8), and BMI decreased by -4.98 kg/m(2) (-5.6, -4.4) with IGB therapy. Hepatic steatosis improved from baseline after 6 months of balloon therapy by magnetic resonance imaging (fat fraction, 16.7 ± 10.9-7.6 ± 9.8, p = 0.003), ultrasound (severe liver steatosis, 52-4 %, p < 0.0001). Histological NAFLD activity score was lower after 6 months of IGB versus control with sham endoscopy and diet (2 ± 0.75 vs. 4 ± 2.25, p = 0.03).

CONCLUSION

The use of intragastric balloon decreases liver enzymes and is potentially an effective short-term treatment for NAFLD as part of a multidisciplinary approach. Larger, more rigorous trials are needed to confirm the effect of IGBs on NAFLD.

Non-alcoholic fatty liver disease and risk of cardiovascular disease

Non-alcoholic fatty liver disease (NAFLD) has become the leading cause of chronic liver diseases worldwide, causing considerable liver-related mortality and morbidity. During the past decade, it has also become increasingly evident that NAFLD is a multisystem disease that affects many extra-hepatic organ systems, including the heart and the vascular system. In this updated clinical review, we discuss the rapidly expanding body of clinical and epidemiological evidence that supports a strong association of NAFLD with cardiovascular diseases (CVDs) and other functional and structural myocardial abnormalities. We also discuss some recently published data that correlate NAFLD due to specific genetic polymorphisms with the risk of CVDs. Finally, we briefly examine the assessment tools for estimating the global CVD risk in patients with NAFLD as well as the conventional and the more innovative pharmacological approaches for the treatment of CVD risk in this group of patients.

Genetic Factors That Affect Risk of Alcoholic and Nonalcoholic Fatty Liver Disease

Genome-wide association studies and candidate gene studies have informed our understanding of factors contributing to the well-recognized interindividual variation in the progression and outcomes of alcoholic liver disease and nonalcoholic fatty liver disease. We discuss the mounting evidence for shared modifiers and common pathophysiological processes that contribute to development of both diseases. We discuss the functions of proteins encoded by risk variants of genes including patatin-like phospholipase domain-containing 3 and transmembrane 6 superfamily member 2, as well as epigenetic factors that contribute to the pathogenesis of alcoholic liver disease and nonalcoholic fatty liver disease. We also discuss important areas of future genetic research and their potential to affect clinical management of patients.

Evidence that non-alcoholic fatty liver disease and polycystic ovary syndrome are associated by necessity rather than chance: a novel hepato-ovarian axis?

Increasing evidence suggests that non-alcoholic fatty liver disease (NAFLD) and polycystic ovary syndrome (PCOS) are associated with obesity, insulin resistance, metabolic syndrome, cardiovascular disease, cirrhosis, and liver tumors. On these grounds, we have hypothesized that NAFLD and PCOS occur more frequently than expected by chance alone. We have tested this hypothesis by reviewing the clinical and biological evidence that supports a significant association between NAFLD and PCOS. PubMed was extensively searched for articles published through March 2015 using the keywords "nonalcoholic fatty liver disease" or "fatty liver" combined with "PCOS." Several cross-sectional and case-control studies have consistently demonstrated that the prevalence of NAFLD is remarkably increased in young women with PCOS, independent of overweight/obesity and other coexisting metabolic syndrome features, and that these women are more likely to have the more severe forms of NAFLD (non-alcoholic steatohepatitis, advanced fibrosis, and cirrhosis). Accumulating evidence suggests that NAFLD, especially its necro-inflammatory form, may exacerbate hepatic and systemic insulin resistance and releases multiple pro-inflammatory, pro-coagulant, and pro-fibrogenic mediators that may play important roles in the pathophysiology of PCOS. These findings call for more active and systematic search for NAFLD among women with PCOS. Conversely, gastroenterologists/hepatologists need to be aware of the presence of PCOS among female patients with NAFLD and compatible clinical features. Finally, all these patients should undergo regular follow-up not only for liver-related complications but also for cardio-metabolic diseases.

Extrahepatic manifestations in chronic hepatitis C virus carriers

Patients with chronic hepatitis C virus (HCV) infection frequently present with extrahepatic manifestations covering a large spectrum, involving different organ systems leading to the concept of systemic HCV infection. These manifestations include autoimmune phenomena and frank autoimmune and/or rheumatic diseases and may dominate the course of chronic HCV infection. Chronic HCV infection causes liver inflammation affecting the development of hepatic diseases. HCV is also a lymphotropic virus that triggers B cells and promotes favorable conditions for B lymphocyte proliferation, including mixed cryoglobulinemia (MC) and MC vasculitis, which is the most prominent extrahepatic manifestation of chronic HCV infection. HCV may also promote a low-grade chronic systemic inflammation that may affect the development of some extrahepatic manifestations, particularly cardiovascular and cerebral vascular diseases. Recognition of extrahepatic symptoms of HCV infection could facilitate early diagnosis and treatment. The development of direct-acting antiviral agents (DDAs) has revolutionized HCV treatment. DDAs, as well as new B-cell-depleting or B-cell-modulating monoclonal antibodies, will expand the panorama of treatment options for HCV-related extrahepatic manifestations including cryoglobulinemic vasculitis. In this context, a proactive, integrated approach to HCV therapy should maximize the benefits of HCV therapy, even when liver disease is mild.

Epidemiological modifiers of non-alcoholic fatty liver disease: Focus on high-risk groups

An improved understanding of non-alcoholic fatty liver disease epidemiology would lead to identification of individuals at high risk of developing chronic liver disease and extra-hepatic complications, thus contributing to more effective case finding of non-alcoholic fatty liver disease among selected groups. We aimed to illustrate the epidemiology of non-alcoholic fatty liver disease in high-risk groups, which were identified based on existing literature. To this end, PubMed was searched to retrieve original articles published until May 2015 using relevant and pertinent keywords "nonalcoholic fatty liver disease" and "diabetes", "obesity", "hyperlipidaemia", "familial heterozygous hypobetalipoproteinaemia", "hypertension", "metabolic syndrome", "ethnicity", "family history" or "genetic polymorphisms". We found that age, sex and ethnicity are major physiological modifiers of the risk of non-alcoholic fatty liver disease, along with belonging to "non-alcoholic fatty liver disease families" and carrying risk alleles for selected genetic polymorphisms. Metabolic syndrome, diabetes, obesity, mixed hyperlipidaemia and hypocholesterolaemia due to familial hypobetalipoproteinaemia are the major metabolic modifiers of non-alcoholic fatty liver disease risk. Compared with these metabolic conditions, however, arterial hypertension appears to carry a relatively more modest risk of non-alcoholic fatty liver disease. A better understanding of the epidemiology of non-alcoholic fatty liver disease may result in a more liberal policy of case finding among high-risk groups.

The association between the serum levels of uric acid and alanine aminotransferase in a population-based cohort

BACKGROUND & AIMS

Elevated serum uric acid levels reflect and also cause both oxidative stress and insulin resistance and are frequently observed in patients with the metabolic syndrome. A strong association exists between the metabolic syndrome and non-alcoholic fatty liver disease (NAFLD). Therefore, we aimed to test the association between uric acid and elevated alanine aminotransferase (ALT), as a surrogate for NAFLD, using real-world data.

METHODS

Data used for the cross-sectional study were obtained from Maccabi Healthcare System, a 2-million member health maintenance organization in Israel. The population consisted of individuals aged 20-60 years who underwent blood tests for ALT and uric acid between 1997 and 2012. Individuals with secondary liver disease, celiac, and inflammatory bowel-disease were excluded. Subgroup analysis was performed in subjects who were given the diagnosis of fatty liver in their medical records (n = 2628).

RESULTS

The study population included 82,608 people (32.5% men, mean age 43.91 ± 10.15 years). There was a significant positive dose-response association between serum uric acid levels and the rate of elevated serum ALT (P for trend <0.001). In multivariable model, controlling for potential confounders, the association between uric acid and elevated ALT persisted (OR = 2.10, 95% CI 1.93-2.29, for the fourth quartile vs. the first). This association was maintained in all categories of gender and BMI. Similar results were observed among patients diagnosed with fatty liver (OR = 1.77, 1.22-2.57).

CONCLUSIONS

Serum uric acid is independently associated with elevated ALT, as a surrogate for NAFLD, and thus may serve as a serum marker for liver damage and should be further investigated as a risk factor for NAFLD.

Lipid dysregulation in hepatitis C virus, and impact of statin therapy upon clinical outcomes

The hepatitis C virus (HCV) is one of the most common causes of chronic liver disease and the leading indication for liver transplantation worldwide. Every aspect of the HCV life cycle is closely tied to human lipid metabolism. The virus circulates as a lipid-rich particle, utilizing lipoprotein cell receptors to gain entry into the hepatocyte. It has also been shown to upregulate lipid biosynthesis and impair lipid degradation, resulting in significant intracellular lipid accumulation and circulating hypocholesterolemia. Patients with chronic hepatitis C (CHC) are at increased risk of hepatic steatosis, fibrosis, and cardiovascular disease including accelerated atherosclerosis. HMG CoA Reductase inhibitors, or statins, have been shown to play an important role in the modulation of hepatic steatosis and fibrosis, and recent attention has focused upon their potential therapeutic role in CHC. This article reviews the hepatitis C viral life cycle as it impacts host lipoproteins and lipid metabolism. It then describes the pathogenesis of HCV-related hepatic steatosis, hypocholesterolemia and atherosclerosis, and finally describes the promising anti-viral and anti-fibrotic effects of statins, for the treatment of CHC.

Potential impact of joint association of alanine aminotransferase and gamma-glutamyltransferase on insulin resistance in Japan: The Toranomon Hospital Health Management Center Study 19 (TOPICS 19)

AIM

To investigate the potential impact of joint association of alanine aminotransferase (ALT) and γ-glutamyltransferase (GGT) on insulin resistance and β-cell dysfunction in healthy Japanese individuals with a normal range of liver enzymes.

METHODS

This study included 1010 individuals (545 men and 465 women) aged 20-89 years who underwent an oral glucose tolerance test for health screening. Participants were divided into four groups on the basis of median values for ALT and GGT: (i) both ALT and GGT low (both-low); (ii) ALT high and GGT low (ALT-high); (iii) ALT low and GGT high (GGT-high); and (iv) both ALT and GGT high (both-high). Logistic regression analysis was used to investigate the relationship between liver enzyme and insulin dynamics, such as Homeostasis Model of Assessment - Insulin Resistance (HOMA-IR) and insulinogenic index (IGI). The insulin resistance was defined when HOMA-IR was 2.5 or more. IGI of less than 0.4 was considered to be decreased early-phase insulin secretion.

RESULTS

Mean values of HOMA-IR in men was 1.5 in the both-low group, 1.8 in ALT-high, 1.8 in GGT-high and 2.8 in both-high. The mean HOMA-IR in women was 1.3 in the both-low group, 1.3 in ALT-high, 1.6 in GGT-high and 2.0 in both-high. HOMA-IR in the both-high group was significantly higher than that in the both-low group regardless of the difference of sex. Multivariate analysis showed that insulin resistance occurred when the patient had high liver enzymes.

CONCLUSION

Combining the two liver function markers would be effective for identifying individuals with insulin resistance.

Nonalcoholic fatty liver disease: a precursor of the metabolic syndrome

The conventional paradigm of nonalcoholic fatty liver disease representing the "hepatic manifestation of the metabolic syndrome" is outdated. We identified and summarized longitudinal studies that, supporting the association of nonalcoholic fatty liver disease with either type 2 diabetes mellitus or metabolic syndrome, suggest that nonalcoholic fatty liver disease precedes the development of both conditions. Online Medical databases were searched, relevant articles were identified, their references were further assessed and tabulated data were checked. Although several cross-sectional studies linked nonalcoholic fatty liver disease to either diabetes and other components of the metabolic syndrome, we focused on 28 longitudinal studies which provided evidence for nonalcoholic fatty liver disease as a risk factor for the future development of diabetes. Moreover, additional 19 longitudinal reported that nonalcoholic fatty liver disease precedes and is a risk factor for the future development of the metabolic syndrome. Finally, molecular and genetic studies are discussed supporting the view that aetiology of steatosis and lipid intra-hepatocytic compartmentation are a major determinant of whether fatty liver is/is not associated with insulin resistance and metabolic syndrome. Data support the novel paradigm of nonalcoholic fatty liver disease as a strong determinant for the development of the metabolic syndrome, which has potentially relevant clinical implications for diagnosing, preventing and treating metabolic syndrome.

Homozygous MTTP and APOB mutations may lead to hepatic steatosis and fibrosis despite metabolic differences in congenital hypocholesterolemia

BACKGROUND & AIMS

Non-alcoholic steatohepatitis leading to fibrosis occurs in patients with abetalipoproteinemia (ABL) and homozygous or compound heterozygous familial hypobetalipoproteinemia (Ho-FHBL). We wanted to establish if liver alterations were more frequent in one of both diseases and were influenced by comorbidities.

METHODS

We report genetic, clinical, histological and biological characteristics of new cases of ABL (n =7) and Ho-FHBL (n = 7), and compare them with all published ABL (51) and Ho-FHBL (22) probands.

RESULTS

ABL patients, diagnosed during infancy, presented mainly with diarrhea, neurological and ophthalmological impairments and remained lean, whereas Ho-FHBL were diagnosed later, with milder symptoms often becoming overweight in adulthood. Despite subtle differences in lipid phenotype, liver steatosis was observed in both groups with a high prevalence of severe fibrosis (5/27 for Ho-FHBL vs. 4/58 for ABL (n.s.)). Serum triglycerides concentration was higher in Ho-FHBL whereas total and HDL-cholesterol were similar in both groups. In Ho-FHBL liver alterations were found to be independent from the apoB truncation size and apoB concentrations.

CONCLUSIONS

Our findings provide evidence for major liver abnormalities in both diseases. While ABL and Ho-FHBL patients have subtle differences in lipid phenotype, carriers of APOB mutations are more frequently obese. These results raise the question of a complex causal link between apoB metabolism and obesity. They suggest that the genetic defect in VLDL assembly is critical for the occurrence of liver steatosis leading to fibrosis and shows that obesity and insulin resistance might contribute by increasing lipogenesis.