Is liver fat detrimental to vessels?: intersections in the pathogenesis of NAFLD and atherosclerosis. Clin Sci (Lond). 2008;115:1-12. [PMID: 19016656 DOI: 10.1042/cs20070311]

Towards harnessing the value of organokine crosstalk to predict the risk for cardiovascular disease in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. Importantly, NAFLD increases the risk for cardiovascular disease (CVD). A causal relationship has been substantiated. Given the pandemic proportions of NAFLD, a reliable scoring system for predicting the risk of NAFLD-associated CVD is an urgent medical need. We here review cumulative evidence suggesting that systemically released organokines - especially certain adipokines, hepatokines, and cardiokines - may serve this purpose. The underlying rationale is that these signalers directly communicate between white adipose tissue, liver, and heart as key players in the pathogenesis of NAFLD and resultant CVD events. Moreover, evidence suggests that these organ-specific cytokines are secreted in a biologically predetermined, cascade-like pattern. Consequently, upon pinpointing organokines of relevance, we sketch requirements to establish an algorithm predictive of the CVD risk in patients with NAFLD. Such an algorithm, as to be consolidated in the form of an applicable equation, may be improved continuously by machine learning. To the best of our knowledge, such an option has not yet been considered. Establishing and implementing a reliable algorithm for determining the NAFLD-associated CVD risk has the potential to save many NAFLD patients from life-threatening CVD events.

Emerging Role of Nuclear Receptors for the Treatment of NAFLD and NASH

Non-alcoholic fatty liver (NAFLD) over the past years has become a metabolic pandemic linked to a collection of metabolic diseases. The nuclear receptors ERRs, REV-ERBs, RORs, FXR, PPARs, and LXR are master regulators of metabolism and liver physiology. The characterization of these nuclear receptors and their biology has promoted the development of synthetic ligands. The possibility of targeting these receptors to treat NAFLD is promising, as several compounds including Cilofexor, thiazolidinediones, and Saroglitazar are currently undergoing clinical trials. This review focuses on the latest development of the pharmacology of these metabolic nuclear receptors and how they may be utilized to treat NAFLD and subsequent comorbidities.

Non-alcoholic/Metabolic-Associated Fatty Liver Disease and Helicobacter pylori Additively Increase the Risk of Arterial Stiffness

Background

Non-alcoholic fatty liver disease (NAFLD) and Helicobacter pylori (Hp) infection have a close association with an increased risk of cardiovascular disease. Metabolic dysfunction-associated fatty liver disease (MAFLD) is characterized by metabolic dysfunction in NAFLD. We investigated the synergistic effects of NAFLD/MAFLD and Hp infection on the risk of arterial stiffness in an asymptomatic population.

Methods

We included individuals who underwent abdominal ultrasonography, anti-Hp IgG antibody evaluations and cardio-ankle vascular index (CAVI) during health screening tests between January 2013 and December 2017. Arterial stiffness was defined using CAVI. A logistic regression model was used to analyze the independent and synergistic effects of NAFLD/MAFLD and Hp infection on the risk of arterial stiffness.

Results

Among 3,195 subjects (mean age 54.7 years, 68.5% male), the prevalence of increased arterial stiffness was 36.4%. In the multivariate analysis, subjects with NAFLD but without Hp infection and those with both NAFLD and Hp infection had a significantly higher risk of increased arterial stiffness [odds ratio (OR) 1.61, 95% confidence interval (CI) 1.15–2.26, and OR 2.23, 95% CI 1.63–3.06, respectively], than subjects without Hp infection and NAFLD. Regarding MAFLD, Hp infection additively increased the risk of arterial stiffness in subjects with MAFLD (OR 2.13, 95% CI 1.64–2.78).

Conclusions

An interactive effect of Hp infection on the risk of arterial stiffness in individuals with NAFLD/MAFLD was observed. Hp infection additively increases the risk of arterial stiffness in subjects with NAFLD or MAFLD.

Role of the sympathetic nervous system in cardiometabolic control: implications for targeted multiorgan neuromodulation approaches

Sympathetic overdrive plays a key role in the perturbation of cardiometabolic homeostasis. Diet-induced and exercise-induced weight loss remains a key strategy to combat metabolic disorders, but is often difficult to achieve. Current pharmacological approaches result in variable responses in different patient cohorts and long-term efficacy may be limited by medication intolerance and nonadherence. A clinical need exists for complementary therapies to curb the burden of cardiometabolic diseases. One such approach may include interventional sympathetic neuromodulation of organs relevant to cardiometabolic control. The experience from catheter-based renal denervation studies clearly demonstrates the feasibility, safety and efficacy of such an approach. In analogy, denervation of the common hepatic artery is now feasible in humans and may prove to be similarly useful in modulating sympathetic overdrive directed towards the liver, pancreas and duodenum. Such a targeted multiorgan neuromodulation strategy may beneficially influence multiple aspects of the cardiometabolic disease continuum offering a holistic approach.

Association of gamma-glutamyl transferase with subclinical coronary atherosclerosis and cardiac outcomes in non-alcoholics

In an asymptomatic population, we determined the relationship between serum gamma-glutamyl transferase (GGT) and subclinical atherosclerosis, using coronary computed tomography angiography (CCTA). This was a retrospective observational cohort study which analyzed 5120 consecutive asymptomatic individuals with no prior history of coronary artery disease or significant alcohol intake who voluntarily underwent CCTA as part of a general health examination. All subjects were stratified into tertiles based on GGT levels. Degree and extent of subclinical coronary atherosclerosis were evaluated using CCTA. Cardiac events were a composite of all-cause death, myocardial infarction, unstable angina, and coronary revascularization. After adjustment for cardiovascular risk factors, there were no significant differences among GGT tertiles in terms of adjusted odds ratios for non-calcified and mixed plaques. The risk of any atherosclerotic and calcified plaques, significant stenosis, multi-vessel disease, and significant stenosis in the left main or proximal left anterior descending artery was higher in the third GGT tertile than in the first tertile (all p < 0.05). Over a median 5.4-year follow-up, the third GGT tertile had significant adjusted hazards ratios for cardiac events than did the first GGT tertile, even after stepwise adjustment for cardiovascular risk factors (all p < 0.01). In asymptomatic individuals, elevated GGT was independently associated with high-risk feature atherosclerosis and poorer cardiac outcomes.

Associations between Vaspin Levels and Coronary Artery Disease

The relationship between serum vaspin levels and metabolic or coronary artery disease is currently of interest for researchers. Although adipokine concentrations have been shown to be increased significantly in atherosclerotic lesions, the role adipokines in the atherosclerotic process remains to be elucidated. Vaspin is a new biological marker associated with obesity and impaired insulin sensitivity. Plasma vaspin concentration has been shown to correlate with the severity of coronary artery disease. Vascular inflammation triggered by vaspin inhibits atherogenesis by suppressing macrophage foam cell formation and vascular smooth muscle cell migration and proliferation. Vaspin also contributes to plaque stabilization by increasing collagen content and reducing the intraplaque macrophage to vascular smooth muscle cell ratio. The therapeutic goal concerning vaspin is to fight atherosclerosis and related diseases, as well as to maintain vascular health.

Helicobacter pylori infection combined with non-alcoholic fatty liver disease increase the risk of atherosclerosis: Focus in carotid artery plaque

Atherosclerosis has severe consequences on human health. Carotid artery plaques are a condition typically caused by atherosclerosis. Previous studies showed that nonalcoholic fatty liver disease (NAFLD) and Helicobacter pylori (H pylori) are risks factors for carotid artery plaque formation. We hypothesize that the combination of NAFLD with H pylori infection increases the risk of carotid artery plaque formation.A total of 4669 subjects aged > 40 years who underwent routine health checkups between January 2006 and December 2015 were retrospectively reviewed. A serial examination, including abdominal ultrasound, carotid artery ultrasound and esophago-gastroduodenoscopy (EGD), and biopsy urease testing, was conducted.In total, 2402 subjects were enrolled. There were no differences in H pylori infection status among patients with or without NAFLD. There was a trend of more participants with both NAFLD and H pylori infection (number [N]=583) presenting carotid artery plaque (N = 187,32.08%) than participants without NAFLD and H pylori infection (N = 589) who presented plaque formation (N = 106, 18.00%). Participants who had both H pylori infection and NAFLD had the highest risk of any carotid artery plaque (odds ratio [OR], 1.93; 95% confidence interval [CI], 1.413-2.636) based on a multivariate logistic regression analysis. This analysis also showed that age >60 years, male sex, low-density lipoprotein (LDL) >130 mg/dL, and H pylori infection were independent risk factors for concomitant NAFLD and carotid artery plaque formation.The combination of H pylori infection and NAFLD increases carotid artery plaque formation. H pylori eradication and NAFLD control may be warranted to prevent carotid artery plaque formation.

Association between non-alcoholic fatty liver disease and subclinical coronary atherosclerosis: An observational cohort study

BACKGROUND & AIMS

There are limited data on the association between non-alcoholic fatty liver disease (NAFLD) and subclinical coronary atherosclerosis. This study investigated the influence of NAFLD on subclinical coronary atherosclerosis as detected by coronary computed tomography angiography (CCTA) in an asymptomatic population.

METHODS

A total of 5,121 consecutive asymptomatic individuals with no prior history of coronary artery disease or significant alcohol intake voluntarily underwent abdominal ultrasonography and CCTA as part of a general health examination. Fatty liver was assessed by ultrasonography examination. The fatty liver index and NAFLD fibrosis score were also calculated. Coronary atherosclerotic plaques on CCTA were evaluated. The association between NAFLD and subclinical coronary atherosclerosis was determined by logistic regression analysis.

RESULTS

Of the study participants, 1,979 (38.6%) had ultrasonography-diagnosed NAFLD. After adjustment for cardiovascular risk factors, there were no statistically significant differences in the adjusted odds ratios of NAFLD for calcified plaque (1.03; 95% CI 0.89-1.20; p = 0.673) and mixed plaque (1.15; 95% CI 0.93-1.42; p = 0.214). However, adjusted odds ratios for any atherosclerotic plaque (1.18; 95% CI 1.03-1.35; p = 0.016) and non-calcified plaque (1.27; 95% CI 1.08-1.48; p = 0.003) were significantly higher in NAFLD. In addition, there was a significant association of fatty liver index ≥30 with non-calcified plaque (1.37; 95% CI 1.14-1.65; p = 0.001) and NAFLD fibrosis score ≥-1.455 with non-calcified plaque (1.20; 95% CI 1.08-1.42; p = 0.030).

CONCLUSIONS

In this large cross-sectional study of asymptomatic individuals undergoing CCTA, NAFLD was consistently associated with non-calcified plaque, suggesting an increased cardiovascular risk.

LAY SUMMARY

In asymptomatic individuals, non-alcoholic fatty liver disease (NAFLD) was an independent risk factor for non-calcified plaque, which has been known as a vulnerable plaque associated with sudden and unexpected cardiac events. Therefore, appropriate medical therapy for NAFLD was required to reduce future cardiac events.

Non-Alcoholic Fatty Liver Disease: The Emerging Burden in Cardiometabolic and Renal Diseases

As the number of individuals with non-alcoholic fatty liver disease (NAFLD) has increased, the influence of NAFLD on other metabolic diseases has been highlighted. Accumulating epidemiologic evidence indicates that NAFLD not only affects the liver but also increases the risk of extra-hepatic diseases such as type 2 diabetes mellitus, metabolic syndrome, dyslipidemia, hypertension, cardiovascular or cerebrovascular diseases, and chronic kidney disease. Non-alcoholic steatohepatitis, an advanced type of NAFLD, can aggravate these inter-organ relationships and lead to poorer outcomes. NAFLD induces insulin resistance and exacerbates systemic chronic inflammation and oxidative stress, which leads to organ dysfunction in extra-hepatic tissues. Although more research is needed to identify the pathophysiological mechanisms and causal relationship between NAFLD and cardiometabolic and renal diseases, screening for heart, brain, and kidney diseases, risk assessment for diabetes, and a multidisciplinary approach for managing these patients should be highly encouraged.

Non-alcoholic fatty liver disease and progression of coronary artery calcium score: a retrospective cohort study

BACKGROUND AND AIM

Non-alcoholic fatty liver disease (NAFLD), a hepatic manifestation of the metabolic syndrome, was associated with subclinical atherosclerosis in many cross-sectional studies, but the prospective association between NAFLD and the progression of atherosclerosis has not been evaluated. This study was conducted to evaluate the association between NAFLD and the progression of coronary atherosclerosis.

METHODS

This retrospective cohort study included 4731 adult men and women with no history of cardiovascular disease (CVD), liver disease or cancer at baseline who participated in a repeated regular health screening examination between 2004 and 2013. Fatty liver was diagnosed by ultrasound based on standard criteria, including parenchymal brightness, liver-to-kidney contrast, deep beam attenuation and bright vessel walls. Progression of coronary artery calcium (CAC) scores was measured using multidetector CT scanners.

RESULTS

The average duration of follow-up was 3.9 years. During follow-up, the annual rate of CAC progression in participants with and without NAFLD were 22% (95% CI 20% to 23%) and 17% (16% to 18%), respectively (p<0.001). The multivariable ratio of progression rates comparing participants with NAFLD with those without NAFLD was 1.04 (1.02 to 1.05; p<0.001). The association between NAFLD and CAC progression was similar in most subgroups analysed, including in participants with CAC 0 and in those with CAC >0 at baseline.

CONCLUSIONS

In this large cohort study of adult men and women with no history of CVD, NAFLD was significantly associated with the development of CAC independent of cardiovascular and metabolic risk factors. NAFLD may play a pathophysiological role in atherosclerosis development and may be useful to identify subjects with a higher risk of subclinical disease progression.

Association between non-alcoholic hepatic steatosis and hyper reactive blood pressure response on the exercise treadmill test

AIMS

Non-alcoholic hepatic steatosis (HS) is associated with hypertension and increased cardiovascular risk. While Blood pressure hyper-reactive response (HRR) during peak exercise indicates an increased risk of incident hypertension and increased cardiovascular risk, no data on the association of non-alcoholic HS and HRR exists. In this study, we have evaluated the association of HS with HRR.

METHODS

We included 13 410 consecutive individuals with a mean age: 42.4  ±  8.9 years, 3561 (26.6%) female with normal resting blood pressure and without a previous diagnosis of hypertension, who underwent symptom limited exercise treadmill test, abdominal ultrasonography and clinical and laboratory evaluation. HS was detected by abdominal ultrasonography. HRR was defined by a peak exercise systolic blood pressure  >220 mmHg and/or elevation of 15 mmHg or more in diastolic blood pressure from rest to peak exercise.

RESULTS

The prevalence of HS was 29.5% (n  =  3956). Overall, 4.6% (n  =  619) of the study population presented a HRR. Subjects with HS had a higher prevalence of HRR (8.1 vs. 3.1%, odds ratio 2.8, 95% CI 2.4-3.3, P  <  0.001). After adjustment for body mass index, waist circumference, fasting plasma glucose and low density lipoprotein cholesterol, HS (odds ratio 1.4, 95% CI 1.1-1.6, P  =  0.002) remained independently associated with HRR. HS was additive to obesity markers in predicting exercise HRR.

CONCLUSIONS

Non-alcoholic HS is independently associated with hyper-reactive exercise blood pressure response.

Assessment of Cardiovascular Parameters in Obese Children and Adolescents with Non-Alcoholic Fatty Liver Disease

OBJECTIVE

The aim of this study was to evaluate the periaortic fat thickness (PAFT) using conventional echocardiography in obese children and adolescents with non-alcoholic fatty liver disease (NAFLD).

METHODS

Two hundred and ninety-seven obese children and adolescents were included in the study. Anthropometric measurements were made in all subjects, and fasting venous blood samples were taken for determination of glucose, insulin, total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Ultrasonography of the liver was used for assessment of NAFLD and the subjects were grouped as NAFLD and non-NAFLD. Echocardiography was performed in all subjects.

RESULTS

PAFT was higher in patients with NAFLD compared with the non-NAFLD group. In patients with NAFLD, PAFT was positively correlated with waist circumference and with total cholesterol levels. In multiple regression analysis, waist circumference (β=0.28, p=<0.001) was found to be the best predictor of PAFT.

CONCLUSION

Conventional echocardiography may be used to determine increased PAFT at an early stage in obese children and adolescents with NAFLD for careful monitoring of cardiovascular risk.

Nonalcoholic fatty liver disease and age are strong indicators for atherosclerosis in morbid obesity

OBJECTIVE

Whether nonalcoholic fatty liver disease (NAFLD) can predict atherosclerosis in obese patients remains unclear. The aim of our study was to investigate the usefulness of NAFLD and other cardiometabolic parameters in predicting subclinical atherosclerosis in obese patients.

DESIGN, PATIENTS AND MEASUREMENTS

We studied 314 consecutive obese subjects (223 women; mean age, 45·04 ± 9·34 years; body mass index 44·3 ± 5 kg/m(2) ) and 47 healthy lean individuals. Hepatic steatosis and atherosclerosis [carotid intima-media thickness (cIMT) >0·8 mm and/or presence of plaques] were evaluated ultrasonographically. Liver biopsies were obtained in 51 patients.

RESULTS

In obese patients, mean c-IMT was greater in those with NAFLD (P < 0·001). Hepatic steatosis and age were independent predictors of atherosclerosis: the NAFLD-associated OR for atherosclerosis was 5·96 (95%CI, 1·60-22·25; P = 0·008) in men and 8·26 (95%CI, 4·02-16·99; P < 0·001) in women, and the age-associated OR for atherosclerosis was 1·14 (95%CI, 1·07-1·22; P < 0·001) in men and 1·12 (95%CI, 1·08-1·17; P < 0·001) in women. The sensitivity, specificity and positive and negative predictive values of steatosis for atherosclerosis were 78·70%, 70·50%, 74·00% and 75·60% (AUC = 0·840) in men ≥43·5 years and 86·90%, 52·50%, 68·80% and 76·80% (AUC = 0·761) in women ≥47·5 years, respectively. Agreement between ultrasound-diagnosed steatosis and histology was good (ICC = 0·79). Combined NAFLD and age was the strongest predictor of atherosclerosis in obesity.

CONCLUSIONS

Nonalcoholic fatty liver disease and age may be independent risk factors for carotid atherosclerosis in obese individuals. Obese men and women with steatosis aged over 43·5 and 47·5 years, respectively, should be screened for carotid atherosclerosis. However, further evidence is necessary before suggesting an intervention based on current findings.

γ-Glutamyltransferase, but not markers of hepatic fibrosis, is associated with cardiovascular disease in older people with type 2 diabetes mellitus: the Edinburgh Type 2 Diabetes Study

AIMS/HYPOTHESIS

We examined the association of prevalent and incident cardiovascular disease (CVD) with chronic liver disease in a cohort of community-based people with type 2 diabetes, in order to clarify the relationship between these two important conditions.

METHODS

1,066 participants with type 2 diabetes aged 60-75 years underwent assessment of a range of liver injury markers (non-specific injury, steatosis, steatohepatitis, fibrosis, portal hypertension). Individuals were followed up for incident cardiovascular events.

RESULTS

At baseline there were 370/1,033 patients with prevalent CVD, including 317/1,033 with coronary artery disease (CAD). After a mean follow-up of 4.4 years there were 44/663 incident CVD events, including 27/663 CAD events. There were 30/82 CVD-related deaths. Risk of dying from or developing CVD was no higher in participants with steatosis than in those without (HR 0.90; 95% CI 0.40, 2.00; p > 0.05). The only notable relationship was with γ-glutamyltransferase (GGT) (incident CVD: adjusted HR for doubling GGT 1.24 [95% CI 0.97, 1.59] p = 0.086; incident CAD: adjusted HR 1.33 [95% CI 1.00, 1.78] p = 0.053), suggesting that in our study population, chronic liver disease may have little effect on the development of, or mortality from, CVD.

CONCLUSIONS/INTERPRETATION

An independent association between GGT and CVD warrants further exploration as a potentially useful addition to current cardiovascular risk prediction models in diabetes. However, overall findings failed to suggest that there is a clinical or pathophysiological association between chronic liver disease and CVD in elderly people with type 2 diabetes.

Association Between Psychological Distress and Liver Disease Mortality: A Meta-analysis of Individual Study Participants

BACKGROUND & AIMS

Risk factors for cardiovascular disease, such as obesity and hypertension, have been associated with nonalcoholic fatty liver disease. Psychological distress (symptoms of anxiety and depression) is a risk factor for cardiovascular disease, so it might also be associated, directly or indirectly, with liver disease. We investigated the relationship between psychological distress (measured by the 12-item General Health Questionnaire [GHQ]) and liver disease mortality.

METHODS

We performed a meta-analysis of data from individual participants in 16 prospective studies of the general population in the United Kingdom, initiated from 1994 through 2008. Subjects were assigned to groups based on GHQ score: 0 (no distress), 1-3, 4-6, or 7-12.

RESULTS

We analyzed data from 166,631 individuals (55% women; mean ± SD age, 46.6 ± 18.4 years; range, 16-102 years). During a mean follow-up period of 9.5 years, 17,368 participants died (457 with liver disease). We found a significant increase in liver disease mortality with increase in GHQ score (Ptrend < .001). The age- and sex-adjusted hazard ratio for the highest GHQ score category (ie, 7-12), compared with the 0 score category, was 3.48 (95% confidence interval: 2.68-4.52). After adjustment for health behaviors, socioeconomic status, body mass index, and diabetes, this hazard ratio decreased to 2.59 (95% confidence interval: 1.82-3.68).

CONCLUSIONS

Based on a meta-analysis, psychological distress is associated with liver disease mortality, although this finding requires additional analysis. Although one is not likely to cause the other, we provide additional evidence for the deleterious effects of psychological problems on physical health.

Diagnosis and management of cardiovascular risk in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is increasingly recognized as an important cardiovascular risk (CVR) factor. This is a narrative clinical review aimed at answering how diagnosis and management of CVR should be conducted in the individual patient with NAFLD. To this end, the authors performed an extensive search of the existing literature on PubMed (1993-2014) using pertinent keywords. To date, CVR among patients with NAFLD might be assessed with the Framingham risk score equation or other risk calculators, to be adapted to the true CVR in the specific population being assessed; however, the use of these CVR calculators needs to be validated by future studies in larger cohorts of NAFLD patients of various ethnic backgrounds in order to substantiate their clinical relevance as a foundation for the primary prevention of cardiovascular diseases in this group of patients. Early and aggressive drug treatment of CVR should be started in NAFLD patients with a history of cardiovascular events, established diabetes or who are at high (calculated) CVR. Whether such an aggressive pharmacological approach is also justified in patients with NAFLD, who are at intermediate or low CVR, remains debatable. Currently, there are no clinical trials showing that the treatment of NAFLD per se (either associated or unassociated with traditional CVR factors) will result in decreased risk of cardiovascular events. Accordingly, drug treatment should be better individualized, aiming at correcting all the coexisting cardio-metabolic risk factors of the individual patient with NAFLD. To this end, an overview of the lifestyle interventions and the available drugs is offered, emphasis being conveyed to statins and metformin, which promise to cover worrying complications of NAFLD such as the risk of developing hepatocellular carcinoma.

The association of liver enzymes with biomarkers of subclinical myocardial damage and structural heart disease

BACKGROUND & AIMS

Patients with non-alcoholic fatty liver disease (NAFLD) are thought to be at increased risk of cardiovascular morbidity and mortality. However, the relationships between NAFLD and subclinical myocardial injury or structural heart disease are unknown.

METHODS

We conducted a cross-sectional analysis of 8668 participants from the Atherosclerosis Risk in Communities (ARIC) Study, who showed no clinical evidence of cardiovascular disease. We used levels of liver enzymes (alanine aminotransferase [ALT], aspartate aminotransferase [AST] and gamma-glutamyl transpeptidase [GGT]), in the context of no history of elevated alcohol consumption as non-invasive surrogates of NAFLD. We used highly sensitive cardiac troponin T (hs-cTnT) and N-terminal pro-Brain natriuretic peptide (NT-proBNP) as biomarkers of myocardial damage and function.

RESULTS

In this population-based study (mean age 63 years, 60% women, 78% white), higher levels of ALT, AST, and GGT, even within the normal range, were significantly and independently associated with detectable (hs-cTnT >3 ng/L) and elevated (hs-cTnT ⩾14 ng/L) concentrations of hs-cTnT. The adjusted odds ratios (95% confidence interval) for elevated liver enzymes (vs. normal levels) with elevated hs-cTnT were: 1.65 (1.28-2.14) for ALT, 1.90 (1.36-2.68) for AST, and 1.55 (1.13-2.12) for GGT. Furthermore, there was evidence for inverse associations of ALT and AST with NT-proBNP.

CONCLUSIONS

Our results suggest that elevated liver enzyme levels in the absence of elevated alcohol consumption may be associated with subclinical myocardial injury. The inverse association between NT-proBNP and both ALT and AST supports the recently described metabolic role of natriuretic peptides.

A concise review of non-alcoholic fatty liver disease. Atherosclerosis. 2015;239:192-202. [PMID: 25617860 DOI: 10.1016/j.atherosclerosis.2015.01.001]

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome and the incidence of which is rising rapidly due to the increasing epidemic of obesity in both adults and children. The initial accumulation of fat followed by subsequent inflammation is central to the development of liver damage, and is critically influenced by host factors including age, gender, presence of diabetes, genetic polymorphisms and more recently by the gut microbiome. An increasing body of data suggest that NAFLD is also an independent risk factor of cardiovascular disease, which remains the commonest cause of mortality in such patients. This review focusses on the pathogenesis of NAFLD, and the evolution of new approaches to the management and treatment of NAFLD.

Almonds inhibit dyslipidemia and vascular dysfunction in rats through multiple pathways

BACKGROUND

Almonds are reported to be protective against cardiovascular diseases (CVDs); however, the possible mode of action has only infrequently been explored.

OBJECTIVE

This study aimed at investigating the mechanistic basis for the benefits of almonds in atherosclerotic CVDs.

METHODS

Three studies in 3 groups of rats were designed with the use of tyloxapol (study 1), a high-fat diet (HFD; study 2), and white-flour fructose (WFF; study 3). In each of the studies, the first group acted as the control [administered saline in study 1 and fed a normal diet (ND) in studies 2 and 3]; the second and third groups were treated with tyloxapol in study 1, an HFD in study 2, and WFF in study 3. The third group in each study was also fed almonds (3 g/kg) for 4 wk, after which blood was collected for biochemical evaluation. Livers and aortas were isolated from the rats in studies 1 and 2 for enzyme assays and vascular analysis, respectively.

RESULTS

Almond supplementation significantly (P < 0.05) prevented hyperlipidemia in all of the rat models. Supplementation suppressed cholesterol synthesis, leading to a 65% inhibition of tyloxapol-induced activation of hepatic β-hydroxy-β-methylglutaryl coenzyme A reductase. The almond intervention inhibited by 56% the HFD-induced increase in serum concentrations of hepatic aminotransferases. Almonds also protected against an HFD-induced increase in uric acid (0.9-fold), phosphorus (1.1-fold), alkaline phosphatase (4.6-fold), and γ-glutamyltransferase (1-fold), with resultant concentrations that were not different from those in ND-fed rats (P > 0.05). Almonds partially restored the vascular reactivity of isolated aortas and prevented HFD-induced endothelial dysfunction by reducing inhibition of endothelial nitric oxide (NO) synthase and promoting NO release. The 70% decrease in HDL cholesterol that was observed in the WFF group was prevented by almond supplementation; serum and LDL cholesterol were also normalized.

CONCLUSIONS

The inhibition of de novo cholesterol synthesis, prevention of hepatic damage, and restoration of vascular function via the protection of endothelium and influence on the NO pathway are some of the mechanisms underlying the medicinal value of almonds in CVDs.

Nonalcoholic fatty liver disease and aging: Epidemiology to management

Nonalcoholic fatty liver disease (NAFLD) is common in the elderly, in whom it carries a more substantial burden of hepatic (nonalcoholic steatohepatitis, cirrhosis and hepatocellular carcinoma) and extra-hepatic manifestations and complications (cardiovascular disease, extrahepatic neoplasms) than in younger age groups. Therefore, proper identification and management of this condition is a major task for clinical geriatricians and geriatric hepatologists. In this paper, the epidemiology and pathophysiology of this condition are reviewed, and a full discussion of the link between NAFLD and the aspects that are peculiar to elderly individuals is provided; these aspects include frailty, multimorbidity, polypharmacy and dementia. The proper treatment strategy will have to consider the peculiarities of geriatric patients, so a multidisciplinary approach is mandatory. Non-pharmacological treatment (diet and physical exercise) has to be tailored individually considering the physical limitations of most elderly people and the need for an adequate caloric supply. Similarly, the choice of drug treatment must carefully balance the benefits and risks in terms of adverse events and pharmacological interactions in the common context of both multiple health conditions and polypharmacy. In conclusion, further epidemiological and pathophysiological insight is warranted. More accurate understanding of the molecular mechanisms of geriatric NAFLD will help in identifying the most appropriate diagnostic and therapeutic approach for individual elderly patients.

Sex-specific prevalence of fatty liver disease and associated metabolic factors in Wuhan, south central China

BACKGROUND

This study aimed to investigate the sex-specific prevalence and metabolic risk factors of fatty liver disease (FLD), and to predict the prevalence of steatohepatitis with liver fibrosis in Wuhan, south central China.

METHODS

A cross-sectional study was conducted among 25,032 participants who underwent health checkups from 2010 to 2011 in Zhongnan hospital.

RESULTS

The prevalence of FLD was higher among men than among women (31.8 vs. 12.9%, P<0.0001). However, it increased markedly with age among women, and in the age-groups above 60 years, the prevalence was similar between men and women (26.4 vs. 27.6%, P>0.05). FLD was associated with obesity, increased levels of total cholesterol, triglycerides (TG), low-density lipoproteins, serum uric acid, aspartate aminotransferase, alanine aminotransferase, and fasting blood sugar, an aspartate aminotransferase/alanine aminotransferase ratio of less than 1, and a decreased level of high-density lipoprotein in both sexes. Multiple regression analyses showed that obesity, elevated levels of fasting blood sugar, TG, total cholesterol, and alanine aminotransferase, an aspartate aminotransferase/alanine aminotransferase ratio of less than 1, serum uric acid levels, and decreased high-density lipoprotein levels were related to FLD in men, whereas age played a more prominent role in women. The prevalence of steatohepatitis with advanced fibrosis, estimated using the BMI, age, ALT, and TG index (BAAT index), was 2.5% in men and 1.4% in women; more women with FLD had a BAAT score of 3 or higher compared with men (9.0 vs. 6.6%).

CONCLUSION

The prevalence of FLD in China is high among men and elderly women and is mainly related to various metabolic parameters. The prevalence of steatohepatitis with advanced fibrosis is considerably high among individuals with FLD.

Chronic hepatitis C virus infection and atherosclerosis: Clinical impact and mechanisms

Hepatitis C virus (HCV) infection represents a major health issue worldwide due to its burden of chronic liver disease and extrahepatic manifestations including cardiovascular diseases, which are associated with excess mortality. Analysis of published studies supports the view that HCV infection should be considered a risk factor for the development of carotid atherosclerosis, heart failure and stroke. In contrast, findings from studies addressing coronary artery disease and HCV have yielded conflicting results. Therefore, meta-analytic reviews and prospective studies are warranted. The pathogenic mechanisms connecting HCV infection, chronic liver disease, and atherogenesis are not completely understood. However, it has been hypothesized that HCV may promote atherogenesis and its complications through several direct and indirect biological mechanisms involving HCV colonization and replication within arterial walls, liver steatosis and fibrosis, enhanced and imbalanced secretion of inflammatory cytokines, oxidative stress, endotoxemia, mixed cryoglobulinemia, perturbed cellular and humoral immunity, hyperhomocysteinemia, hypo-adiponectinaemia, insulin resistance, type 2 diabetes and other components of the metabolic syndrome. Understanding these complex mechanisms is of fundamental importance for the development of novel therapeutic approaches to prevent and to treat vascular complications in patients with chronic HCV infection. Currently, it seems that HCV clearance by interferon and ribavirin treatment significantly reduces non-liver-related mortality; moreover, interferon-based treatment appears to decrease the risk of ischemic stroke.

Fatty liver predicts the risk for cardiovascular events in middle-aged population: a population-based cohort study

OBJECTIVE

We investigated if the differences in liver fat content would predict the development of non-fatal and fatal atherosclerotic endpoints (coronary heart disease and stroke).

DESIGN, SETTING AND PARTICIPANTS

Our study group is a population-based, randomly recruited cohort (Oulu Project Elucidating Risk of Atherosclerosis, OPERA), initiated in 1991. The cohort consisted of 988 middle-aged Finnish participants.

INTERVENTION

Total mortality and hospital events were followed up to 2009 based on the registry of the National Institute for Health and Welfare and the National death registry.

MAIN OUTCOME MEASURE

The severity of hepatic steatosis was measured by ultrasound and divided into three groups (0-2). Cox regression analysis was used in the statistical analysis.

RESULTS

In the follow-up of years 1991-2009, 13.5% of the participants with non-fatty liver, 24.2% of participants having moderate liver fat content and 29.2% of the participants having severe fatty liver experienced a cardiovascular event during the follow-up time (p<0.001). Severe liver fat content predicted the risk for future risk of cardiovascular event even when adjusted for age, gender and study group (HR 1.92, CI 1.32 to 2.80, p<0.01). When further adjustments for smoking, alcohol consumption, low-density lipoprotein-cholesterol, body mass index and systolic blood pressure were conducted, the risk still remained statistically significant (HR 1.74, CI 1.16 to 2.63, p<0.01). Statistical significance disappeared with further adjustment for QUICKI.

CONCLUSIONS

Liver fat content increases the risk of future cardiovascular disease event in long-term follow-up but it is seems to be dependent on insulin sensitivity.

Simple steatosis is a more relevant source of serum inflammatory markers than omental adipose tissue

BACKGROUND AND AIMS

Serum inflammatory biomarkers are closely associated with the risk of cardiovascular disease. However, the major source of these biomarkers is not yet determined. Therefore, we aimed to assess whether simple steatosis or visceral adiposity was a more relevant predictor for serum inflammatory biomarkers.

METHODS

A double approach was used: i) clinical: 50 patients with biopsy-proven simple steatosis, 50 non-simple steatosis overweight patients, and 50 controls were explored for their serum biomarkers (high-sensitivity C-reactive protein, plasminogen activator inhibitor-1 activity, tumor necrosis factor α, and fibrinogen levels) and for visceral adiposity (measured by computed tomography); ii) experimental: using a rat simple steatosis model the effect of omentectomy on inflammatory biomarkers was investigated.

RESULTS

Serum inflammatory biomarkers were significantly higher in the simple steatosis group than in the overweight group. Using multivariate analysis, simple steatosis, visceral adiposity index and visceral adiposity were independently associated with inflammatory biomarkers. In particular, serum inflammatory biomarkers increased with the severity of liver histology (p<0.05), but no with visceral adipose tissue increase. In rats with simple steatosis, the omentectomy treatment was not associated with a decrease of serum inflammatory biomarkers in rats with simple steatosis.

CONCLUSIONS

Clinical and experimental data both indicate that simple steatosis may be more associated with inflammatory biomarkers than omental adipose tissue.

The fatty liver index is associated with increased mortality in subjects referred to coronary angiography

BACKGROUND AND AIMS

Fatty liver index (FLI), a surrogate parameter for nonalcoholic fatty liver disease, is an emerging risk factor for cardiovascular diseases and mortality. We aimed to evaluate whether FLI is associated with all-cause, cardiovascular, and non-cardiovascular mortality as well as fatal cancer in a cohort of subjects routinely referred to coronary angiography.

METHODS AND RESULTS

FLI was calculated using BMI (body mass index), waist circumference (WC), triglycerides (TG) and gamma-glutamyl transferase (GGT) in 3270 subjects who were referred to coronary angiography (1997-2000). The main outcome measures were Cox proportional hazard ratios (HRs) for mortality from all causes, cardiovascular causes, non-cardiovascular causes, and fatal cancer. After a median follow-up time of 7.7 years, 740 subjects (22.6%) had died. There were 437 deaths due to cardiovascular disease and 303 deaths due to non-cardiovascular disease. Age-, sex-, and BMI-adjusted HRs (with 95% confidence intervals) for all-cause, cardiovascular, and non-cardiovascular mortality in the highest compared to the lowest FLI quartile were 2.56 (1.90-3.43; p < 0.001), 2.17 (1.47-3.22; p < 0.001), and 3.49 (2.16-5.66; p < 0.001), respectively. In age-, sex-, and BMI-adjusted analyzes, we found no significant association of FLI with fatal cancer. Multivariate adjusted HRs for all-cause, cardiovascular, non-cardiovascular mortality, and fatal cancer in the highest compared to the lowest FLI quartile were 2.17 (1.58-2.99; p < 0.001), 1.64 (1.07-2.51; p = 0.023), 3.72 (2.22-6.24; p < 0.001), and 2.33 (1.01-5.41; p = 0.048) respectively.

CONCLUSION

In subjects referred to coronary angiography, high FLI levels are independently associated with increased all-cause, cardiovascular, and non-cardiovascular mortality as well as fatal cancer.

Pharmacological agents for nonalcoholic steatohepatitis

The rationale for specific pharmacologic therapy in nonalcoholic steatohepatitis (NASH) is determined by the potential for disease progression and the difficulties, in many patients, to successfully implement diet and lifestyle changes in the long term. Because they correct insulin resistance, insulin-sensitizing agents are attractive candidates for the treatment of NASH. However, two randomized studies have shown that vitamin E, despite having no effect on insulin sensitivity, achieves interesting histological and biochemical efficacy. This review provides an insight into the therapeutic efficacy and safety issues of different pharmacological agents tested in human NASH.

Relationship of serum fetuin-A levels with coronary atherosclerotic burden and NAFLD in patients undergoing elective coronary angiography

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) patients are prone to coronary artery disease (CAD). Fetuin-A inhibits arterial calcification, induces insulin resistance, and is increased in NAFLD. Data on fetuin-A levels in CAD are conflicting. We tried to ascertain whether NAFLD and CAD are associated and if fetuin-A predicts CAD and/or NAFLD.

METHODS

CAD was diagnosed by ≥50% stenosis in coronary arteries and NAFLD by ultrasound imaging in the absence of any other liver disease. Seventy patients who underwent elective coronarography at our hospital were recruited in this cross-sectional study. Twenty-four patients had no CAD (9 with and 15 without NAFLD) and 46 had CAD (20 with and 26 without NAFLD). Standard anthropometric indices and metabolic parameters were recorded. Fetuin-A was determined by enzyme-linked immunosorbent assay (ELISA). Visceral fat thickness and visceral/subcutaneous fat ratio were assessed by ultrasonography.

RESULTS

NAFLD was not associated with CAD, probably owing to the limited series. Fetuin-A was significantly lower, whereas visceral fat thickness and visceral/subcutaneous fat ratio were higher in patients with CAD versus those without CAD. Younger age and higher body mass index (BMI), waist circumference, triglycerides, fasting glucose, homeostasis model assessment, spleen area, subcutaneous fat thickness, and prevalence of metabolic derangements were associated with NAFLD. At multivariate analysis, elevated fetuin-A levels were an independent negative predictor of CAD [odds ratio (OR)=0.995, P=0.049]. Fetuin-A was an independent predictor of NAFLD (OR=1.005, P=0.036) in the model including BMI.

CONCLUSIONS

This prospective cross-sectional study demonstrates high fetuin-A levels to be independently associated with NAFLD and a lower risk of coronarographically diagnosed CAD.

High fat diets and pathology in the guinea pig. Atherosclerosis or liver damage?

Animal models have been widely used to investigate the relationship between diet and atherosclerosis and also to study disease etiology and possible interventions. Guinea pigs have been suggested to be a more "realistic" model for atherosclerosis due to their many similarities to humans. However, few published studies actually reported observations of characteristic atherosclerotic lesions and even fewer of advanced lesions. Studies, by our group, of guinea pigs fed on a high-fat diet revealed similar observations, with indications primarily of fatty streaks but little evidence of atherosclerotic plaques. This review discusses the feasibility of the guinea pig as a model for dietary-induced atherosclerosis. As it stands, current evidence raises doubt as to whether guinea pigs could serve as a realistic model for atherosclerosis. However, our own data and the literature suggest that they could be useful models for studying lipoprotein metabolism, non-alcoholic fatty liver disease, and dietary interventions which may help regulate these conditions.

Increased risk of cardiovascular disease and chronic kidney disease in NAFLD

NAFLD is very common in the general population and its prevalence is increasing worldwide in parallel with the increasing incidences of obesity and metabolic diseases, mainly type 2 diabetes. In some cases, however, the diagnosis of NAFLD remains uncertain because other causes of liver disease are not easy to exclude in patients who are diagnosed with NAFLD after a biochemical or ultrasonographic analysis. Several studies have documented a strong association between NAFLD and traditional and nontraditional risk factors for cardiovascular disease (CVD) and chronic kidney disease (CKD). Accordingly, patients with NAFLD have an increased prevalence and incidence of both CVD and CKD. It is reasonable to believe that NAFLD, CVD and CKD share common risk factors (such as visceral obesity, insulin resistance, dysglycaemia, dyslipidaemia and hypertension) and therefore that NAFLD might simply be a marker rather than a causal risk factor of CVD and CKD. In this context, the identification of NAFLD might be an additional clinical feature to improve the stratification of patients for their risk of CVD and CKD. Growing evidence suggests that in patients with NAFLD, especially if NASH is present, several molecules released from the steatotic and inflamed liver might have pathogenic roles in the development of atherosclerosis and kidney damage. If these findings are confirmed by further studies, NAFLD could become a target for the prevention and treatment of CVD and CKD. NAFLD, whatever its role (marker or causal risk factor), is therefore a clinical condition that deserves greater attention from gastroenterologists, endocrinologists, cardiologists and nephrologists, as well as internists and general practitioners.

Portal hypertensive cardiovascular pathology: the rescue of ancestral survival mechanisms?

The portal system derives from the vitelline system, which is an extra-embryonic venous system. It could be suggested that this extraembryonic origin determines some of the characteristics attributed to portal hypertension, both compensated, i.e. prehepatic, and decompensated, i.e. fibrotic or cirrhotic. The experimental models most frequently used for studying both types of portal hypertension are portal vein ligation and common bile duct ligation in rats, respectively. We propose that in partial portal vein ligated rats, a low-grade inflammatory response, formed by the successive expression of three overlapping phenotypes - ischemia-reperfusion, vitellogenic-like and remodeling or gastrulation-like - is produced. The names of these inflammatory phenotypes developed in compensated portal hypertension are based on some metabolic similarities that can be established with the abovementioned phases of embryonic development. In bile-duct ligated rats, decompensation related to hepatic insufficiency would induce a high-grade inflammatory response. In this experimental model, the splanchnic interstitium, the mesenteric lymph and the peritoneal mesothelium seem to create an inflammatory axis that produces ascites. The functional comparison between the ascitic and the amniotic fluids would imply that, in the decompensated portal hypertensive syndrome, the abdominal mesothelium acquires properties of the amniotic membranes or amnion. In conclusion, the hypothetical comparison between the inflammatory portal hypertensive evolutive types and the evolutive phases of embryonic development could allow for translational research.

Treatment of atherogenic liver based on the pathogenesis of nonalcoholic fatty liver disease: a novel approach to reduce cardiovascular risk?

Nonalcoholic fatty liver disease (NAFLD), which spans a spectrum of conditions ranging from simple steatosis to progressive nonalcoholic steatohepatitis (NASH), is the most common chronic liver disease and a relevant public health issue. The prevalence of NAFLD depends on adiposity, age, gender and ethnicity. The natural history of liver disease in those with NAFLD critically depends on liver histological changes. However, cardiovascular mortality is increased in NAFLD, particularly in middle-aged adults. Against such a background, this review consists of three sections. First, data on NAFLD as a novel mechanism of increased cardiovascular risk via hyperinsulinism, pro-thrombotic potential, and subclinical inflammation are summarized. Next, the role of atherogenic liver in the development of manifestations of oxidative stress and atherosclerosis is emphasized. Finally, whether and how treating NAFLD will mechanistically result in reduced cardiovascular risk through ameliorated metabolic syndrome is discussed.

Risk of cardiovascular disease and chronic kidney disease in diabetic patients with non-alcoholic fatty liver disease: just a coincidence?

Non-alcoholic fatty liver disease (NAFLD) is estimated to afflict ~20-30% of the general population, and over 70% of the patients with Type 2 diabetes. Given the expected rise in the prevalence of obesity and diabetes, NAFLD will be, if not already there, an epidemic. The consequences of NAFLD are numerous, and range from progression to chronic liver disease with its associated morbidity and mortality, to worsening insulin resistance and Type 2 diabetes, to being a contributor to both cardiovascular disease (CVD) and chronic kidney disease (CKD). NAFLD is, therefore, a complex problem with implications far beyond the liver. This review focuses on the rapidly expanding body of clinical evidence suggesting that NAFLD is associated with an increased prevalence and incidence of both CVD and CKD in patients with diabetes. This association appears to be independent of obesity, hypertension, and other potential confounding factors. However, given the heterogeneity and small number of observational studies, further research is urgently required to corroborate the prognostic role of NAFLD in the development and progression of CVD and CKD among patients with diabetes, and to further elucidate the complex and intertwined mechanisms that link NAFLD with these adverse outcomes.

Circulating vaspin levels and epicardial adipose tissue thickness are associated with impaired coronary flow reserve in patients with nonalcoholic fatty liver disease

BACKGROUND

Patients with nonalcoholic fatty liver disease (NAFLD) have a reduced coronary flow reserve (CFR) and an increased risk of cardiovascular disease. The fat cells that surround coronary arteries may play a central and underrecognized role in development of cardiovascular disease through the systemic secretion of adipokines. We therefore evaluated the relation of epicardial fat thickness, serum levels of epicardial fat-related adipokines (chemerin and vaspin), and CFR in patients with NAFLD.

METHODS

We investigated 54 patients with biopsy-proven NAFLD and 56 age- and sex-matched controls. CFR and epicardial fat thickness (EFT) were measured by transthoracic echocardiography. Serum levels of chemerin and vaspin were measured by ELISA.

RESULTS

EFT was significantly higher (0.64 ± 0.13 vs. 0.54 ± 0.10 cm, P<0.001) and CFR significantly lower (2.11 ± 0.45 vs. 2.52 ± 0.62, P < 0.001) in patients with NAFLD than in controls. Serum levels of vaspin and chemerin were both significantly increased in patients with NAFLD compared with controls. Stepwise regression analysis showed that EFT (β=-0.53, t=-3.7, P<0.001), serum vaspin levels (β=-0.30, t=-2.5, P=0.014), and liver fibrosis (β=-0.31, t=-2.11, P=0.041), in the order they entered into the model, were independent predictors of CFR in NAFLD patients.

CONCLUSION

Our data suggest the presence of a complex interplay between EFT, serum vaspin, and liver histology in promoting an impaired hyperemic stimulation of coronary blood flow in patients with NAFLD.

Liver ATP synthesis is lower and relates to insulin sensitivity in patients with type 2 diabetes

OBJECTIVE

Steatosis associates with insulin resistance and may even predict type 2 diabetes and cardiovascular complications. Because muscular insulin resistance relates to myocellular fat deposition and disturbed energy metabolism, we hypothesized that reduced hepatic ATP turnover (fATP) underlies insulin resistance and elevated hepatocellular lipid (HCL) contents.

RESEARCH DESIGN AND METHODS

We measured hepatic fATP using (31)P magnetic resonance spectroscopy in patients with type 2 diabetes and age- and body mass-matched controls. Peripheral (M and M/I) and hepatic (suppression of endogenous glucose production) insulin sensitivity were assessed with euglycemic-hyperinsulinemic clamps.

RESULTS

Diabetic individuals had 29% and 28% lower peripheral and hepatic insulin sensitivity as well as 42% reduced fATP than controls. After adjusting for HCL, fATP correlated positively with peripheral and hepatic insulin sensitivity but negatively with waist circumference, BMI, and fasting plasma glucose. Multiple regression analysis identified waist circumference as an independent predictor of fATP and inorganic phosphate (P(I)) concentrations, explaining 65% (P = 0.001) and 56% (P = 0.003) of the variations. Hepatocellular P(I) primarily determined the alterations in fATP.

CONCLUSIONS

In patients with type 2 diabetes, insulin resistance relates to perturbed hepatic energy metabolism, which is at least partly accounted for by fat depots.

A simple index of lipid overaccumulation is a good marker of liver steatosis

BACKGROUND

Liver steatosis is often found in association with common cardiometabolic disorders, conditions that may all occur in a shared context of abdominal obesity and dyslipidemia. An algorithm for identifying liver steatosis is the fatty liver index (FLI). The lipid accumulation product (LAP) is an index formulated in a representative sample of the US population to identify cardiometabolic disorders. Because FLI and LAP share two components, namely waist circumference and fasting triglycerides, we evaluated the ability of LAP to identify liver steatosis in the same study population from the Northern Italian town where FLI was initially developed.

METHODS

We studied 588 individuals (59% males) aged 21 to 79 years. Liver steatosis was detected by ultrasonography and coded ordinally as none, intermediate and severe. 44% of the individuals had liver steatosis. Using proportional-odds ordinal logistic regression, we evaluated the ability of log-transformed LAP (lnLAP) to identify liver steatosis. We considered the benefits to our model of including terms for sex, age, suspected liver disease and ethanol intake. We calculated the 3-level probability of liver steatosis according to lnLAP and sex, providing tables and nomograms for risk assessment.

RESULTS

An ordinal proportional-odds model consisting of lnLAP and sex offered a reasonably accurate identification of liver steatosis. The odds of more severe vs. less severe steatosis increased for increasing values of lnLAP (odds ratio [OR] = 4.28, 95%CI 3.28 to 5.58 for each log-unit increment) and was more likely among males (OR = 1.88, 95%CI 1.31 to 2.69).

CONCLUSION

In a study sample of adults from Northern Italy, the simple calculation of LAP was a reasonably accurate approach to recognizing individuals with ultrasonographic liver steatosis. LAP may help primary care physicians to select subjects for liver ultrasonography and intensified lifestyle counseling, and researchers to select patients for epidemiologic studies. A more thorough assessment of LAP's potential for identifying liver steatosis will require its cross-evaluation in external populations.

Hexosamine biosynthesis pathway flux promotes endoplasmic reticulum stress, lipid accumulation, and inflammatory gene expression in hepatic cells

There is increasing evidence that endoplasmic reticulum (ER) stress contributes to the development of atherosclerosis in diabetes mellitus. The purpose of this study was to determine the effects of increased hexosamine biosynthesis pathway (HBP) flux on ER stress levels and the complications of ER stress associated with diabetes and atherosclerosis in hepatic cells. Glutamine:fructose-6-phosphate amidotransferase (GFAT), the rate-limiting enzyme of the HBP, was overexpressed in HepG2 cells by use of an adenoviral expression system. The ER stress response and downstream effects, including activation of lipid and inflammatory pathways, were determined using real-time PCR, immunoblot analysis, and cell staining techniques. GFAT overexpression resulted in increased expression of ER stress markers, including Grp78, Grp94, calreticulin, and GADD153, relative to cells infected with an empty adenoviral vector. In addition, GFAT overexpression promoted lipid, but not cholesterol, accumulation in hepatic cells as well as inflammatory pathway activation. Treatment with 6-diazo-5-oxo-norleucine, a GFAT antagonist, blocked the effects of GFAT overexpression. Consistent with our in vitro data, hyperglycemic mice presented with elevated markers of hepatic ER stress, glucosamine and lipid accumulation. Together, these data suggest that HBP flux-induced ER stress plays a role in the development of hepatic steatosis and atherosclerosis under conditions of hyperglycemia.

A role for Sp1 in transcriptional regulation of phosphatidylethanolamine N-methyltransferase in liver and 3T3-L1 adipocytes

Phosphatidylcholine is made in all nucleated mammalian cells via the CDP-choline pathway. Another major pathway for phosphatidylcholine biosynthesis in liver is catalyzed by phosphatidylethanolamine N-methyltransferase (PEMT). We have now identified 3T3-L1 adipocytes as a cell culture model that expresses PEMT endogenously. We have found that PEMT mRNA and protein levels increased dramatically in 3T3-L1 cells upon differentiation to adipocytes. 5'-Deletion analysis of the PEMT promoter-luciferase constructs stably expressed in 3T3-L1 adipocytes identified a regulatory region between -471 and -371 bp (relative to the transcriptional start site). Competitive and supershift assays demonstrated binding sites for transcription factors Sp1, Sp3 (-408 to -413), and YY1 (-417 to -420). During differentiation of 3T3-L1 cells to adipocytes, the amount of Sp1 protein decreased by approximately 50% just prior to activation of PEMT. Transduction of 3T3-L1 adipocytes with retrovirus containing Sp1 cDNA demonstrated that Sp1 inhibited PEMT transcriptional activity. Similarly, short hairpin RNA directed against Sp1 in 3T3-L1 adipocytes enhanced PEMT transcriptional activation. Chromatin immunoprecipitation assays confirmed that Sp1 binds to the PEMT promoter, and this interaction decreases upon differentiation to adipocytes. These experiments directly link increased PEMT expression in adipocytes to decreased transcriptional expression of Sp1. In addition, our data established that Sp1 binding was required for tamoxifen-mediated inhibition of Pemt promoter activity.

Nonalcoholic fatty liver disease in primary aldosteronism: a pilot study

BACKGROUND

An impairment of glucose metabolism, contributing to the increased cardiovascular risk, has been shown in primary aldosteronism (PA). Insulin resistance is associated with nonalcoholic fatty liver disease (NAFLD) and may play a role in its pathophysiology. The aim of this study was to investigate the association between NAFLD and PA, and to identify determinants of NAFLD in this condition.

METHODS

A total of 40 patients with PA, 40 sex-, age-, and body mass index matched patients with low-renin essential hypertension (LREH) and 40 normotensive subjects were studied. According to ultrasound detection of fatty liver, each group was subdivided in two subsets: with NAFLD and without NAFLD. Patients with diabetes, obesity, and hyperlipidemia were excluded.

RESULTS

Prevalence of NAFLD in PA was similar to that observed in LREH patients, and higher (P < 0.01) than in normotensive controls. Serum potassium was lower in PA than in LREH patients with NAFLD (P < 0.001), while it was similar in PA and LREH patients without NAFLD. At univariate analysis, plasma aldosterone, homeostasis model assessment (HOMA) index and hypokalemia were determinants of NAFLD in PA (P < 0.05), while HOMA index was associated with NAFLD in LREH (P < 0.05). At multivariable analysis, only hypokalemia remained associated with NAFLD in PA (P = 0.02).

CONCLUSIONS

The results of this pilot study suggest that, in the absence of major risk factors for liver disease, NAFLD is a frequent finding in PA. Patients with PA and hypokalemia are more insulin resistant and have higher prevalence of NAFLD than those with normokalemia, indicating greater risk for metabolic and liver disease in this subgroup.

Abnormal hepatic energy homeostasis in type 2 diabetes

Increased hepatocellular lipids relate to insulin resistance and are typical for individuals with type 2 diabetes mellitus (T2DM). Steatosis and T2DM have been further associated with impaired muscular adenosine triphosphate (ATP) turnover indicating reduced mitochondrial fitness. Thus, we tested the hypothesis that hepatic energy metabolism could be impaired even in metabolically well-controlled T2DM. We measured hepatic lipid volume fraction (HLVF) and absolute concentrations of gammaATP, inorganic phosphate (Pi), phosphomonoesters and phosphodiesters using noninvasive (1)H/ (31)P magnetic resonance spectroscopy in individuals with T2DM (58 +/- 6 years, 27 +/- 3 kg/m (2)), and age-matched and body mass index-matched (mCON; 61 +/- 4 years, 26 +/- 4 kg/m (2)) and young lean humans (yCON; 25 +/- 3 years, 22 +/- 2 kg/m (2), P < 0.005, P < 0.05 versus T2DM and mCON). Insulin-mediated whole-body glucose disposal (M) and endogenous glucose production (iEGP) were assessed during euglycemic-hyperinsulinemic clamps. Individuals with T2DM had 26% and 23% lower gammaATP (1.68 +/- 0.11; 2.26 +/- 0.20; 2.20 +/- 0.09 mmol/L; P < 0.05) than mCON and yCON individuals, respectively. Further, they had 28% and 31% lower Pi than did individuals from the mCON and yCON groups (0.96 +/- 0.06; 1.33 +/- 0.13; 1.41 +/- 0.07 mmol/L; P < 0.05). Phosphomonoesters, phosphodiesters, and liver aminotransferases did not differ between groups. HLVF was not different between those from the T2DM and mCON groups, but higher (P = 0.002) than in those from the yCON group. T2DM had 13-fold higher iEGP than mCON (P < 0.05). Even after adjustment for HLVF, hepatic ATP and Pi related negatively to hepatic insulin sensitivity (iEGP) (r =-0.665, P = 0.010, r =-0.680, P = 0.007) but not to whole-body insulin sensitivity.

CONCLUSION

These data suggest that impaired hepatic energy metabolism and insulin resistance could precede the development of steatosis in individuals with T2DM.

The DGAT2 gene is a candidate for the dissociation between fatty liver and insulin resistance in humans

The enzyme DGAT (acyl-CoA:diacylglycerol acyltransferase) catalyses the final step of triacylglycerol (triglyceride) synthesis. Mice overexpressing hepatic DGAT2 fed a high-fat diet develop fatty liver, but not insulin resistance, suggesting that DGAT2 induces a dissociation between fatty liver and insulin resistance. In the present study, we investigated whether such a phenotype also exists in humans. For this purpose, we determined the relationships between genetic variability in the DGAT2 gene with changes in liver fat and insulin sensitivity in 187 extensively phenotyped subjects during a lifestyle intervention programme with diet modification and an increase in physical activity. Changes in body fat composition [MR (magnetic resonance) tomography], liver fat and intramyocellular fat ((1)H-MR spectroscopy) and insulin sensitivity [OGTT (oral glucose tolerance test) and euglycaemic-hyperinsulinaemic clamp] were determined after 9 months of intervention. A change in insulin sensitivity correlated inversely with changes in total body fat, visceral fat, intramyocellular fat and liver fat (OGTT, all P<0.05; clamp, all P< or =0.03). Changes in total body fat, visceral fat and intramyocellular fat were not different between the genotypes of the SNPs (single nucleotide polymorphisms) rs10899116 C>T and rs1944438 C>T (all P> or =0.39) of the DGAT2 gene. However, individuals carrying two or one copies of the minor T allele of SNP rs1944438 had a smaller decrease in liver fat (-17+/-10 and -24+/-5%; values are means+/-S.E.M.) compared with subjects homozygous for the C allele (-39+/-7%; P=0.008). In contrast, changes in insulin sensitivity were not different among the genotypes (OGTT, P=0.76; clamp, P=0.53). In conclusion, our findings suggest that DGAT2 mediates the dissociation between fatty liver and insulin resistance in humans. This finding may be important in the prevention and treatment of insulin resistance and Type 2 diabetes in subjects with fatty liver.