Extrahepatic complications of nonalcoholic fatty liver disease

Treatment of patients with type 2 diabetes and non-alcoholic fatty liver disease: current approaches and future directions

Non-alcoholic fatty liver disease (NAFLD) is reaching epidemic proportions in patients with type 2 diabetes. Patients with NAFLD are at increased risk of more aggressive liver disease (non-alcoholic steatohepatitis [NASH]) and at a higher risk of death from cirrhosis, hepatocellular carcinoma and cardiovascular disease. Dysfunctional adipose tissue and insulin resistance play an important role in the pathogenesis of NASH, creating the conditions for hepatocyte lipotoxicity. Mitochondrial defects are at the core of the paradigm linking chronic excess substrate supply, insulin resistance and NASH. Recent work indicates that patients with NASH have more severe insulin resistance and lipotoxicity compared with matched obese controls with only isolated steatosis. This review focuses on available agents and future drugs under development for the treatment of NAFLD/NASH in type 2 diabetes. Reversal of lipotoxicity with pioglitazone is associated with significant histological improvement, which occurs within 6 months and persists with continued treatment (or for at least 3 years) in patients with prediabetes or type 2 diabetes, holding potential to modify the natural history of the disease. These results also suggest that pioglitazone may become the standard of care for this population. Benefit has also been reported in non-diabetic patients. Recent promising results with glucagon-like peptide 1 receptor agonists have opened another new treatment avenue for NASH. Many agents in Phase 2-3 of development are being tested, aiming to restore glucose/lipid metabolism, ameliorate adipose tissue and liver inflammation, or to inhibit liver fibrosis. By targeting a diversity of relevant pathways, combination therapy in NASH will likely provide greater success in the future. In summary, increased clinical awareness and improved screening strategies (as currently done for diabetic retinopathy and nephropathy) are needed, to translate recent treatment progress into early treatment and improved quality of life for patients with type 2 diabetes and NASH. This review summarises a presentation given at the symposium 'The liver in focus' at the 2015 annual meeting of the EASD. It is accompanied by two other reviews on topics from this symposium (by John Jones, DOI: 10.1007/s00125-016-3940-5 , and by Hannele Yki-Järvinen, DOI: 10.1007/s00125-016-3944-1 ) and a commentary by the Session Chair, Michael Roden (DOI: 10.1007/s00125-016-3911-x ).

Osteoporosis in liver disease: pathogenesis and management

Osteoporosis affects a substantial proportion of patients with chronic liver disease. Pathologic fracture in osteoporosis significantly affects quality of life and life expectancy. By some estimates, 40% of patients with chronic liver disease may experience osteoporotic fracture. In this study we review the pathogenesis, diagnosis and treatment of specific liver disease entities and their relation to osteoporosis.

Insulin resistance in development and progression of nonalcoholic fatty liver disease

Although insulin resistance (IR) is strongly associated with nonalcoholic fatty liver disease (NAFLD), the association of IR and NAFLD is not universal and correlation between IR and severity of NAFLD is still controversial. In this review, we summarize recent evidence that partially dissociates insulin resistance from NAFLD. It has also been reported that single-nucleotide polymorphisms in the diacylglycerol acyltransferase gene, rather than IR, account for the variability in liver fat content. Polymorphisms of the patatin-like phospholipase 3 gene have also been reported to be associated with NAFLD without metabolic syndrome, which suggests that genetic conditions that promote the development of fatty changes in the liver may occur independently of IR. Moreover, environmental factors such as nutrition and physical activity as well as small intestinal bacterial overgrowth have been linked to the pathogenesis of NAFLD, although some of the data are conflicting. Therefore, findings from both genetically engineered animal models and humans with genetic conditions, as well as recent studies that have explored the role of environmental factors, have confirmed the view that NAFLD is a polygenic disease process caused by both genetic and environmental factors. Therefore, IR is not the sole predictor of the pathogenesis of NAFLD.

Extrahepatic Complications of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is an important cause of liver disease that is often associated with the metabolic syndrome. There is a growing awareness that extrahepatic complications occur in individuals with NAFLD, especially an increased risk of cardiovascular disease. Development of diabetes mellitus, chronic kidney disease, colorectal cancer, and endocrinopathies has been linked to NAFLD. This article reviews the extrahepatic complications affecting individuals with NAFLD and the pathogenesis underlying their development.

Pathogenesis of nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a severe form of nonalcoholic fatty liver disease and a risk factor for cirrhosis and hepatocellular carcinoma. The pathological features of NASH include steatosis, hepatocyte injury, inflammation, and various degrees of fibrosis. Steatosis reflects disordered lipid metabolism. Insulin resistance and excessive fatty acid influx to the liver are two important contributing factors. Steatosis is also likely associated with lipotoxicity and cellular stresses such as oxidative stress and endoplasmic reticulum stress, which result in hepatocyte injury. Inflammation and fibrosis are frequently triggered by various signals such as proinflammatory cytokines and chemokines, released by injuried hepatocytes and activated Kupffer cells. Although much progress has been made, the pathogenesis of NASH is not fully elucidated. The purpose of this review is to discuss the current understanding of NASH pathogenesis, mainly focusing on factors contributing to steatosis, hepatocyte injury, inflammation, and fibrosis.

Cardiovascular Disease and Myocardial Abnormalities in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in many developed countries, affecting an estimated 30 % of the adult population. In this updated clinical review, we summarize the current knowledge regarding the strong association between NAFLD and the risk of coronary heart disease (CHD) and other functional, structural, and arrhythmic cardiac complications (e.g., left ventricular dysfunction, heart valve diseases and atrial fibrillation). We also briefly discuss the putative biological mechanisms linking NAFLD with these important extra-hepatic complications. To date, a large body of evidence has suggested that NAFLD is not simply a marker of CHD and other functional, structural, and arrhythmic cardiac complications, but also may play a part in the development and progression of these cardiac complications. The clinical implication of these findings is that patients with NAFLD may benefit from more intensive surveillance and early treatment interventions aimed at decreasing the risk of CHD and other cardiac and arrhythmic complications.

Associations between Methylenetetrahydrofolate Reductase (MTHFR) Polymorphisms and Non-Alcoholic Fatty Liver Disease (NAFLD) Risk: A Meta-Analysis

Background

C677T and A1298C are the most common allelic variants of Methylenetetrahydrofolate Reductase (MTHFR) gene. The association between MTHFR polymorphisms and the occurrence of non-alcoholic fatty liver disease (NAFLD) remains controversial. This study was thus performed to examine whether MTHFR mutations are associated with the susceptibility to NAFLD.

Methods

A first meta-analysis on the association between the MTHFR polymorphisms and NAFLD risks was carried out via Review Manager 5.0 and Stata/SE 12.0 software. The on-line databases, such as PubMed, EMBASE, CENTRAL, WOS, Scopus and EBSCOhost (updated to April 1^st, 2016), were searched for eligible case-control studies. The odd radio (OR), 95% confidence interval (CI) and P value were calculated through Mantel-Haenszel statistics under random- or fixed-effect model.

Results

Eight articles (785 cases and 1188 controls) contributed data to the current meta-analysis. For C677T, increased NAFLD risks were observed in case group under homozygote model (T/T vs C/C, OR = 1.49, 95% CI = 1.03~2.15, P = 0.04) and recessive model (T/T vs C/C+C/T, OR = 1.42, 95% CI = 1.07~1.88, P = 0.02), but not the other genetics models, compared with control group. For A1298C, significantly increased NAFLD risks were detected in allele model (C vs A, OR = 1.53, 95% CI = 1.13~2.07, P = 0.006), homozygote model (C/C vs A/A, OR = 2.81, 95% CI = 1.63~4.85, P = 0.0002), dominant model (A/C+C/C vs A/A, OR = 1.60, 95% CI = 1.06~2.41, P = 0.03) and recessive model (C/C vs A/A+A/C, OR = 2.08, 95% CI = 1.45~3.00, P<0.0001), but not heterozygote model.

Conclusion

T/T genotype of MTHFR C677T polymorphism and C/C genotype of MTHFR A1298C are more likely to be associated with the susceptibility to NAFLD.

Spaceflight Activates Lipotoxic Pathways in Mouse Liver

Spaceflight affects numerous organ systems in the body, leading to metabolic dysfunction that may have long-term consequences. Microgravity-induced alterations in liver metabolism, particularly with respect to lipids, remain largely unexplored. Here we utilize a novel systems biology approach, combining metabolomics and transcriptomics with advanced Raman microscopy, to investigate altered hepatic lipid metabolism in mice following short duration spaceflight. Mice flown aboard Space Transportation System -135, the last Shuttle mission, lose weight but redistribute lipids, particularly to the liver. Intriguingly, spaceflight mice lose retinol from lipid droplets. Both mRNA and metabolite changes suggest the retinol loss is linked to activation of PPARα-mediated pathways and potentially to hepatic stellate cell activation, both of which may be coincident with increased bile acids and early signs of liver injury. Although the 13-day flight duration is too short for frank fibrosis to develop, the retinol loss plus changes in markers of extracellular matrix remodeling raise the concern that longer duration exposure to the space environment may result in progressive liver damage, increasing the risk for nonalcoholic fatty liver disease.

Nonalcoholic fatty liver is not associated with incident chronic kidney disease: a large histology-based comparison with healthy individuals

BACKGROUND

Nonalcoholic steatohepatitis or fibrosis is associated with the increased prevalence of impaired kidney function. It is not known whether nonalcoholic fatty liver (NAFL), which is steatosis without inflammation or fibrosis, is associated with renal impairment as these individuals are not candidates for liver biopsy.

MATERIALS AND METHODS

The study group included all liver donors who underwent a preoperative liver biopsy for various reasons. NAFL was defined as more than 5% hepatocytes having steatosis and no changes of steatohepatitis and/or fibrosis. Individuals with NAFL were compared with individuals with normal liver histology. Estimated glomerular filtration rate was calculated with the Modification of Diet in Renal Disease and Chronic Kidney Disease Epidemiology Collaboration methods.

RESULTS

The mean age of the study group was 35±10.3 years and the mean BMI was 26±3.2 kg/m. A total of 187 adults having NAFL (80 men) were compared with 186 (88 men) individuals with normal liver histology (controls). Individuals with steatosis had significantly higher BMI (26.8±3.5 vs. 25.5±3.8 kg/m, P<0.001) and serum alanine transaminase levels (33.8±13.3 vs. 27.2±9.8 IU/l, P<0.000). There was no significant difference in the estimated glomerular filtration rate between the normal histology group and the NAFL group with Modification of Diet in Renal Disease (115±21.8 vs. 114.4±23.2 ml/min, P=0.803) and Chronic Kidney Disease Epidemiology Collaboration methods (113.6±14.8 vs. 113±14.7 ml/min, P=0.668). There was no significant difference as regards serum creatinine (0.73±0.16 vs. 0.74±0.16 mg%, P=0.536), proteinuria (P=0.121), diabetes (1 vs. 4, P=0.372), and hypertension (2 vs. 6, P=0.174) in individuals of both groups.

CONCLUSION

Presence of NAFL does not adversely affect renal function.

Extrahepatic Manifestations of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide with an increased prevalence of metabolic, macro- and microvascular complications. The primary causes of mortality in NAFLD are cardiovascular disease (CVD), malignancy and liver disease. NAFLD is a multisystem disease that affects a variety of extra-hepatic organ systems. The main focus of this review is to summarize the reported extra-hepatic associations, which include CVD, chronic kidney disease, obstructive sleep apnea, osteoporosis, psoriasis, colorectal cancer, iron overload and various endocrinopathies (e.g. type 2 diabetes mellitus, thyroid dysfunction, and polycystic ovarian syndrome). Due to the systemic manifestations of NAFLD patients require a multidisciplinary assessment and may benefit from more rigorous surveillance and early treatment interventions to decrease mortality related to malignancy or cardiometabolic diseases.

Type 2 Diabetes in Non-Alcoholic Fatty Liver Disease and Hepatitis C Virus Infection--Liver: The "Musketeer" in the Spotlight

The pathogenesis of type 2 diabetes (T2D) involves chronic hyperinsulinemia due to systemic and hepatic insulin resistance (IR), which if uncorrected, will lead to progressive pancreatic beta cell failure in predisposed individuals. Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of fatty (simple steatosis and steatohepatitis) and non-fatty liver changes (NASH-cirrhosis with or without hepatocellular carcinoma (HCC)) that are commonly observed among individuals with multiple metabolic derangements, notably including visceral obesity, IR and T2D. Hepatitis C virus (HCV) infection is also often associated with both hepatic steatosis and features of a specific HCV-associated dysmetabolic syndrome. In recent years, the key role of the steatotic liver in the development of IR and T2D has been increasingly recognized. Thus, in this comprehensive review we summarize the rapidly expanding body of evidence that links T2D with NAFLD and HCV infection. For each of these two liver diseases with systemic manifestations, we discuss the epidemiological burden, the pathophysiologic mechanisms and the clinical implications. To date, substantial evidence suggests that NAFLD and HCV play a key role in T2D development and that the interaction of T2D with liver disease may result in a "vicious circle", eventually leading to an increased risk of all-cause mortality and liver-related and cardiovascular complications. Preliminary evidence also suggests that improvement of NAFLD is associated with a decreased incidence of T2D. Similarly, the prevention of T2D following HCV eradication in the era of direct-acting antiviral agents is a biologically plausible result. However, additional studies are required for further clarification of mechanisms involved.

Effect of resveratrol on experimental non-alcoholic fatty liver disease depends on severity of pathology and timing of treatment

BACKGROUND AND AIM

Non-alcoholic steatohepatitis (NASH) is a leading cause of chronic liver disease with few therapeutic options. Resveratrol (RSV) prevents the development of steatosis in a number of experimental fatty liver (non-alcoholic fatty liver [NAFL]) models, but the preventive or therapeutic effects on experimental NASH are not yet clarified, and clinical results on non-alcoholic fatty liver disease are ambiguous. Thus, we aimed to compare the RSV-mediated preventive and therapeutic effects on experimental NAFL and NASH.

METHODS

We used a high-fat (HF) diet to generate a rat NAFL model and a high-fat, high-cholesterol (HFC) diet to generate a rat NASH model. The preventive and therapeutic potential of RSV was tested by adding RSV to the HF and HFC diet from study start or after 1 week of the diets. Animals were sacrificed after 8 weeks with appropriate controls. Blood and liver were harvested for analysis, including measurement of RSV metabolites.

RESULTS

Resveratrol reduced the development of histological steatosis (P = 0.03) and partly triglyceride accumulation (fold change reduced from 3.6 to 2.4, P = 0.08) in the male NAFL model, although effects were moderate. In NASH prevention, RSV reduced the accumulation of triglyceride in hepatic tissue (P < 0.01), while there was no effect on biochemical, histopathological, or transcriptional NASH changes. Further, RSV had no therapeutic effect on established NASH. We found RSV metabolites but no parent RSV in serum or liver tissue, confirming low bioavailability.

CONCLUSIONS

These experimental findings suggest that a weak hepatic benefit of RSV treatment is seen in prevention of steatosis only.

Glycosyltransferases and non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease and its incidence is increasing worldwide. However, the underlying mechanisms leading to the development of NAFLD are still not fully understood. Glycosyltransferases (GTs) are a diverse class of enzymes involved in catalyzing the transfer of one or multiple sugar residues to a wide range of acceptor molecules. GTs mediate a wide range of functions from structure and storage to signaling, and play a key role in many fundamental biological processes. Therefore, it is anticipated that GTs have a role in the pathogenesis of NAFLD. In this article, we present an overview of the basic information on NAFLD, particularly GTs and glycosylation modification of certain molecules and their association with NAFLD pathogenesis. In addition, the effects and mechanisms of some GTs in the development of NAFLD are summarized.

Liraglutide safety and efficacy in patients with non-alcoholic steatohepatitis (LEAN): a multicentre, double-blind, randomised, placebo-controlled phase 2 study

BACKGROUND

Glucagon-like peptide-1 (GLP-1) analogues reduce hepatic steatosis, concentrations of liver enzymes, and insulin resistance in murine models of fatty liver disease. These analogues are licensed for type 2 diabetes, but their efficacy in patients with non-alcoholic steatohepatitis is unknown. We assessed the safety and efficacy of the long-acting GLP-1 analogue, liraglutide, in patients with non-alcoholic steatohepatitis.

METHODS

This multicentre, double-blinded, randomised, placebo-controlled phase 2 trial was conducted in four UK medical centres to assess subcutaneous injections of liraglutide (1·8 mg daily) compared with placebo for patients who are overweight and show clinical evidence of non-alcoholic steatohepatitis. Patients were randomly assigned (1:1) using a computer-generated, centrally administered procedure, stratified by trial centre and diabetes status. The trial was designed using A'Hern's single-group method, which required eight (38%) of 21 successes in the liraglutide group for the effect of liraglutide to be considered clinically significant. Patients, investigators, clinical trial site staff, and pathologists were masked to treatment assignment throughout the study. The primary outcome measure was resolution of definite non-alcoholic steatohepatitis with no worsening in fibrosis from baseline to end of treatment (48 weeks), as assessed centrally by two independent pathologists. Analysis was done by intention-to-treat analysis, which included all patients who underwent end-of-treatment biopsy. The trial was registered with ClinicalTrials.gov, number NCT01237119.

FINDINGS

Between Aug 1, 2010, and May 31, 2013, 26 patients were randomly assigned to receive liraglutide and 26 to placebo. Nine (39%) of 23 patients who received liraglutide and underwent end-of-treatment liver biopsy had resolution of definite non-alcoholic steatohepatitis compared with two (9%) of 22 such patients in the placebo group (relative risk 4·3 [95% CI 1·0-17·7]; p=0·019). Two (9%) of 23 patients in the liraglutide group versus eight (36%) of 22 patients in the placebo group had progression of fibrosis (0·2 [0·1-1·0]; p=0·04). Most adverse events were grade 1 (mild) to grade 2 (moderate) in severity, transient, and similar in the two treatment groups for all organ classes and symptoms, with the exception of gastrointestinal disorders in 21 (81%) of 23 patients in the liraglutide group and 17 (65%) of 22 patients in the placebo group, which included diarrhoea (ten [38%] patients in the liraglutide group vs five [19%] in the placebo group), constipation (seven [27%] vs none), and loss of appetite (eight [31%] vs two [8%]).

INTERPRETATION

Liraglutide was safe, well tolerated, and led to histological resolution of non-alcoholic steatohepatitis, warranting extensive, longer-term studies.

FUNDING

Wellcome Trust, National Institute of Health Research, and Novo Nordisk.

Acetylcholine induces fibrogenic effects via M2/M3 acetylcholine receptors in non-alcoholic steatohepatitis and in primary human hepatic stellate cells

BACKGROUND

The parasympathetic nervous system (PNS), via neurotransmitter acetylcholine (ACh), modulates fibrogenesis in animal models. However, the role of ACh in human hepatic fibrogenesis is unclear.

AIMS

We aimed to determine the fibrogenic responses of human hepatic stellate cells (hHSC) to ACh and the relevance of the PNS in hepatic fibrosis in patients with non-alcoholic steatohepatitis (NASH).

METHODS

Primary hHSC were analyzed for synthesis of endogenous ACh and acetylcholinesterase and gene expression of choline acetyltransferase and muscarinic ACh receptors (mAChR). Cell proliferation and fibrogenic markers were analyzed in hHSC exposed to ACh, atropine, mecamylamine, methoctramine, and 4-diphenylacetoxy-N-methylpiperidine methiodide. mAChR expression was analyzed in human NASH scored for fibrosis.

RESULTS

We observed that hHSC synthesize ACh and acetylcholinesterase and express choline acetyltransferase and M1-M5 mAChR. We also show that M2 was increased during NASH progression, while both M2 and M3 were found upregulated in activated hHSC. Furthermore, endogenous ACh is required for hHSC basal growth. Exogenous ACh resulted in hHSC hyperproliferation via mAChR and phosphoinositide 3-kinase and Mitogen-activated protein kinase kinase (MEK) signaling pathways, as well as increased fibrogenic markers.

CONCLUSION

We show that ACh regulates hHSC activation via M2 and M3 mAChR involving the phosphoinositide 3-kinase and MEK pathways in vitro. Finally, we provide evidence that the PNS may be involved in human NASH fibrosis.

Nonalcoholic Fatty Liver Disease Is Associated With Higher 1-year All-Cause Rehospitalization Rates in Patients Admitted for Acute Heart Failure

Repeat hospitalization due to acute heart failure (HF) is a global public health problem that markedly impacts on health resource use. Identifying novel predictors of rehospitalization would help physicians to determine the optimal postdischarge plan for preventing HF rehospitalization. Nonalcoholic fatty liver disease (NAFLD) is an emerging risk factor for many heart diseases, including HF. We assessed whether NAFLD at hospital admission predicts 1-year all-cause rehospitalization in patients with acute HF. We enrolled all patients consecutively admitted for acute HF to our General Medicine Division, from January 2013 to April 2014, after excluding patients with acute myocardial infarction, severe heart valve diseases, malignancy, known liver diseases, and those with volume overload related to extracardiac causes. NAFLD was diagnosed by ultrasonography and exclusion of competing etiologies. The primary outcome of the study was the 1-year all-cause rehospitalization rate. Among the 107 patients enrolled in the study, the cumulative rehospitalization rate was 12.1% at 1 month, 25.2% at 3 months, 29.9% at 6 months, and 38.3% at 1 year. Patients with NAFLD had markedly higher 1-year rehospitalization rates than those without NAFLD (58% vs 21% at 1 y; P < 0.001 by the log-rank test). Cox regression analysis revealed that NAFLD was associated with a 5.5-fold increased risk of rehospitalization (adjusted hazard ratio 5.56, 95% confidence interval 2.46-12.1, P < 0.001) after adjustment for multiple HF risk factors and potential confounders. In conclusion, NAFLD was independently associated with higher 1-year rehospitalization in patients hospitalized for acute HF.

Glucagon-like peptide 1 decreases lipotoxicity in non-alcoholic steatohepatitis

BACKGROUND & AIMS

Insulin resistance and lipotoxicity are pathognomonic in non-alcoholic steatohepatitis (NASH). Glucagon-like peptide-1 (GLP-1) analogues are licensed for type 2 diabetes, but no prospective experimental data exists in NASH. This study determined the effect of a long-acting GLP-1 analogue, liraglutide, on organ-specific insulin sensitivity, hepatic lipid handling and adipose dysfunction in biopsy-proven NASH.

METHODS

Fourteen patients were randomised to 1.8mg liraglutide or placebo for 12-weeks of the mechanistic component of a double-blind, randomised, placebo-controlled trial (ClinicalTrials.gov-NCT01237119). Patients underwent paired hyperinsulinaemic euglycaemic clamps, stable isotope tracers, adipose microdialysis and serum adipocytokine/metabolic profiling. In vitro isotope experiments on lipid flux were performed on primary human hepatocytes.

RESULTS

Liraglutide reduced BMI (-1.9 vs. +0.04kg/m(2); p<0.001), HbA1c (-0.3 vs. +0.3%; p<0.01), cholesterol-LDL (-0.7 vs. +0.05mmol/L; p<0.01), ALT (-54 vs. -4.0IU/L; p<0.01) and serum leptin, adiponectin, and CCL-2 (all p<0.05). Liraglutide increased hepatic insulin sensitivity (-9.36 vs. -2.54% suppression of hepatic endogenous glucose production with low-dose insulin; p<0.05). Liraglutide increased adipose tissue insulin sensitivity enhancing the ability of insulin to suppress lipolysis both globally (-24.9 vs. +54.8pmol/L insulin required to ½ maximally suppress serum non-esterified fatty acids; p<0.05), and specifically within subcutaneous adipose tissue (p<0.05). In addition, liraglutide decreased hepatic de novo lipogenesis in vivo (-1.26 vs. +1.30%; p<0.05); a finding endorsed by the effect of GLP-1 receptor agonist on primary human hepatocytes (24.6% decrease in lipogenesis vs. untreated controls; p<0.01).

CONCLUSIONS

Liraglutide reduces metabolic dysfunction, insulin resistance and lipotoxicity in the key metabolic organs in the pathogenesis of NASH. Liraglutide may offer the potential for a disease-modifying intervention in NASH.

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.

Oral intake of genetically engineered high-carotenoid corn ameliorates hepatomegaly and hepatic steatosis in PTEN haploinsufficient mice

Non-alcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease. Here we show that a mouse model of haploinsufficiency in the lipid and protein phosphatase and tensin homolog protein (PTEN(+/-)) exhibits hepatomegaly, increased liver lipogenic gene expression (SREBP-1C and PPARγ) and hepatic lesions analogous to human NAFLD. The livers of PTEN(+/-) mice also contained lower levels of retinoic acid (RA) than normal, similarly to human NAFLD patients. The RA signaling pathway thus offers a novel therapeutic target for the treatment of NAFLD although the impact of nutrition in this context is unclear. We therefore fed PTEN(+/-) mice for 36weeks a diet containing genetically engineered high-carotenoid corn (HCAR) to investigate its potential beneficial effects on the hepatic symptoms of NAFLD. The HCAR diet reduced hepatomegaly and promoted the repartitioning of fatty acids in the liver, away from triacylglycerol storage. At the molecular level, the HCAR diet clearly reduced lipogenic gene expression, boosted catabolism, and increased hepatic RA levels. These results set the stage for human trials to evaluate the use of high-carotenoid foods for the reduction or prevention of steatosis in NAFLD.

The CBS/CSE system: a potential therapeutic target in NAFLD?

Non-alcoholic fatty liver disease (NAFLD) is a broad spectrum liver disorder diagnosed in patients without a history of alcohol abuse. NAFLD is growing at alarming rates worldwide. Its pathogenesis is complex and incompletely understood. The cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE) system regulates homocysteine and cysteine metabolism and contributes to endogenous hydrogen sulfide (H2S) biosynthesis. This review summarizes our current understanding of the hepatic CBS/CSE system, and for the first time, positions this system as a potential therapeutic target in NAFLD. As will be discussed, the CBS/CSE system is highly expressed and active in the liver. Its dysregulation, presenting as alterations in circulating homocysteine and (or) H2S levels, has been reported in NAFLD patients and in NAFLD-associated co-morbidities such as obesity and type 2 diabetes. Intricate links between the CBS/CSE system and a number of metabolic and stress related molecular mediators have also emerged. Various dysfunctions in the hepatic CBS/CSE system have been reported in animal models representative of each NAFLD spectrum. It is anticipated that a newfound appreciation for the hepatic CBS/CSE system will emerge that will improve our understanding of NAFLD pathogenesis, and give rise to new prospective targets for management of this disorder.

Nonalcoholic fatty liver disease severity is associated with the ratios of total cholesterol and triglycerides to high-density lipoprotein cholesterol

BACKGROUND

Limited data support the notion that lipid ratios are risk factors for nonalcoholic fatty liver disease (NAFLD). We evaluated the association between lipid ratios and NAFLD.

METHODS

This was a large population, cross-sectional, retrospective study. Data on NAFLD severity, blood pressure, fasting glucose, total cholesterol (TC), triglyceride (TG), and high-density lipoprotein cholesterol (HDL-C) levels were obtained from 44,767 examinees at single health checkup center. The enrollees were stratified into four subgroups based on their TC/HDL-C and TG/HDL-C ratios. We used multivariate analyses to evaluate the odds between lipid ratios and NAFLD.

RESULTS

The prevalence rate of fatty liver in this study was 53.76%. In the baseline subgroup with the lowest TC/HDL-C and TG/HDL-C ratios, the prevalence of NAFLD, hypertension, and diabetes was lower than that of the other three subgroups. Patients with higher lipid ratios had a significantly greater risk for advanced NAFLD.

CONCLUSIONS

Adults with high TC/HDL-C or TG/HDL-C ratios, or both, have a greater risk for NAFLD, especially advanced NAFLD.

Obesity: An overview of possible role(s) of gut hormones, lipid sensing and gut microbiota

Obesity is one of the major challenges for public health in 21st century, with 1.9 billion people being considered as overweight and 600 million as obese. There are certain diseases such as type 2 diabetes, hypertension, cardiovascular disease, and several forms of cancer which were found to be associated with obesity. Therefore, understanding the key molecular mechanisms involved in the pathogenesis of obesity could be beneficial for the development of a therapeutic approach. Hormones such as ghrelin, glucagon like peptide 1 (GLP-1) peptide YY (PYY), pancreatic polypeptide (PP), cholecystokinin (CCK) secreted by an endocrine organ gut, have an intense impact on energy balance and maintenance of homeostasis by inducing satiety and meal termination. Glucose and energy homeostasis are also affected by lipid sensing in which different organs respond in different ways. However, there is one common mechanism i.e. formation of esterified lipids (long chain fatty acyl CoAs) and the activation of protein kinase C δ (PKC δ) involved in all these organs. The possible role of gut microbiota and obesity has been addressed by several researchers in recent years, indicating the possible therapeutic approach toward the management of obesity by the introduction of an external living system such as a probiotic. The proposed mechanism behind this activity is attributed by metabolites produced by gut microbial organisms. Thus, this review summarizes the role of various physiological factors such as gut hormone and lipid sensing involved in various tissues and organ and most important by the role of gut microbiota in weight management.

Nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a disorder characterized by excess accumulation of fat in hepatocytes (nonalcoholic fatty liver (NAFL)); in up to 40% of individuals, there are additional findings of portal and lobular inflammation and hepatocyte injury (which characterize nonalcoholic steatohepatitis (NASH)). A subset of patients will develop progressive fibrosis, which can progress to cirrhosis. Hepatocellular carcinoma and cardiovascular complications are life-threatening co-morbidities of both NAFL and NASH. NAFLD is closely associated with insulin resistance; obesity and metabolic syndrome are common underlying factors. As a consequence, the prevalence of NAFLD is estimated to be 10-40% in adults worldwide, and it is the most common liver disease in children and adolescents in developed countries. Mechanistic insights into fat accumulation, subsequent hepatocyte injury, the role of the immune system and fibrosis as well as the role of the gut microbiota are unfolding. Furthermore, genetic and epigenetic factors might explain the considerable interindividual variation in disease phenotype, severity and progression. To date, no effective medical interventions exist that completely reverse the disease other than lifestyle changes, dietary alterations and, possibly, bariatric surgery. However, several strategies that target pathophysiological processes such as an oversupply of fatty acids to the liver, cell injury and inflammation are currently under investigation. Diagnosis of NAFLD can be established by imaging, but detection of the lesions of NASH still depend on the gold-standard but invasive liver biopsy. Several non-invasive strategies are being evaluated to replace or complement biopsies, especially for follow-up monitoring.

Treating morbid obesity in cirrhosis: A quest of holy grail

The problem of obesity is increasing worldwide in epidemic proportions; the situation is similarly becoming more common in patients with cirrhosis which negatively affect the prognosis of disease and also makes liver transplantation difficult especially in the living donor liver transplantation setting where low graft to recipient weight ratio negatively affects survival. Treatment of obesity is difficult in cirrhosis due to difficulty in implementation of lifestyle measures, limited data on safety of anti-obesity drugs and high risk of surgery. Currently approved anti-obesity drugs have limited data in patients with cirrhosis. Bariatric surgery remains an option in selected compensated cirrhotic patients. Endoscopic interventions for obesity are emerging and are quite promising in patients with cirrhosis as these are minimally invasive. In present review, we briefly discuss various modalities of weight reduction in obese patients and their applicability in patients with cirrhosis.

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.

Increased risk of colorectal polyps in patients with non-alcoholic fatty liver disease undergoing liver transplant evaluation

BACKGROUND

Screening colonoscopy is a standard part of the liver transplant (LT) evaluation process. We aimed to evaluate the yield of screening colonoscopy and determine whether non-alcoholic fatty liver disease (NAFLD) was associated with an increased risk of colorectal neoplasia.

METHODS

We retrospectively assessed all patients who completed LT evaluation at our center between 1/2008-12/2012. Patients <50 years old and those without records of screening colonoscopy, or with greater than average colon cancer risk were excluded.

RESULTS

A total of 1,102 patients were evaluated, 591 met inclusion criteria and were analyzed. The mean age was 60 years, 67% were male, 12% had NAFLD and 88% had other forms of chronic liver disease. Overall, 42% of patients had a polyp found on colonoscopy: 23% with adenomas, 14% with hyperplastic polyps and with 1% inflammatory polyps. In the final multivariable model controlling for age, NAFLD [odds ratio (OR) 2.41, P=0.001] and a history of significant alcohol use (OR 1.69, P=0.004) were predictive of finding a polyp on colonoscopy. In addition, NAFLD (OR 1.95, P=0.02), significant alcohol use (OR 1.70, P=0.01) and CTP class C (OR 0.57, P=0.02) were associated with adenoma, controlling for age.

CONCLUSIONS

Screening colonoscopy in patients awaiting LT yields a high rate of polyp (43%) and adenoma (22%) detection, perhaps preventing the accelerated progression to carcinoma that can occur in immunosuppressed post-LT patients. Patients with NAFLD may be at a ~2 fold higher risk of adenomas and should be carefully evaluated prior to LT.

NKT cell modulates NAFLD potentiation of metabolic oxidative stress-induced mesangial cell activation and proximal tubular toxicity

Obesity and nonalcoholic fatty liver disease (NAFLD) are associated with the development and progression of chronic kidney disease. We recently showed that NAFLD induces liver-specific cytochrome P-450 (CYP)2E1-mediated metabolic oxidative stress after administration of the CYP2E1 substrate bromodichloromethane (BDCM) (Seth RK, Das S, Kumar A, Chanda A, Kadiiska MB, Michelotti G, Manautou J, Diehl AM, Chatterjee S. Toxicol Appl Pharmacol 274: 42-54, 2014; Seth RK, Kumar A, Das S, Kadiiska MB, Michelotti G, Diehl AM, Chatterjee S. Toxicol Sci 134:291-303, 2013). The present study examined the effects of CYP2E1-mediated oxidative stress in NAFLD leading to kidney toxicity. Mice were fed a high-fat diet for 12 wk to induce NAFLD. NAFLD mice were exposed to BDCM, a CYP2E1 substrate, for 4 wk. NAFLD + BDCM increased CYP2E1-mediated lipid peroxidation in proximal tubular cells compared with mice with NAFLD alone or BDCM-treated lean mice, thus ruling out the exclusive role of BDCM. Lipid peroxidation increased IL-1β, TNF-α, and interferon-γ. In parallel, mesangial cell activation was observed by increased α-smooth muscle actin and transforming growth factor-β, which was blocked by the CYP2E1 inhibitor diallyl sulphide both in vivo and in vitro. Mice lacking natural killer T cells (CD1d knockout mice) showed elevated (>4-fold) proinflammatory mediator release, increased Toll-like receptor (TLR)4 and PDGF2 mRNA, and mesangial cell activation in the kidney. Finally, NAFLD CD1D knockout mice treated with BDCM exhibited increased high mobility group box 1 and Fas ligand levels and TUNEL-positive nuclei, indicating that higher cell death was attenuated in TLR4 knockout mice. Tubular cells showed increased cell death and cytokine release when incubated with activated mesangial cells. In summary, an underlying condition of progressive NAFLD causes renal immunotoxicity and aberrant glomerular function possibly through high mobility group box 1-dependent TLR4 signaling and mesangial cell activation, which, in turn, is modulated by intrinsic CD1D-dependent natural killer T cells.

Replacement of Dietary Saturated Fat by PUFA-Rich Pumpkin Seed Oil Attenuates Non-Alcoholic Fatty Liver Disease and Atherosclerosis Development, with Additional Health Effects of Virgin over Refined Oil

BACKGROUND AND AIMS

As dietary saturated fatty acids are associated with metabolic and cardiovascular disease, a potentially interesting strategy to reduce disease risk is modification of the quality of fat consumed. Vegetable oils represent an attractive target for intervention, as they largely determine the intake of dietary fats. Furthermore, besides potential health effects conferred by the type of fatty acids in a vegetable oil, other minor components (e.g. phytochemicals) may also have health benefits. Here, we investigated the potential long-term health effects of isocaloric substitution of dietary fat (i.e. partial replacement of saturated by unsaturated fats), as well as putative additional effects of phytochemicals present in unrefined (virgin) oil on development of non-alcoholic fatty liver disease (NAFLD) and associated atherosclerosis. For this, we used pumpkin seed oil, because it is high in unsaturated fatty acids and a rich source of phytochemicals.

METHODS

ApoE*3Leiden mice were fed a Western-type diet (CON) containing cocoa butter (15% w/w) and cholesterol (1% w/w) for 20 weeks to induce risk factors and disease endpoints. In separate groups, cocoa butter was replaced by refined (REF) or virgin (VIR) pumpkin seed oil (comparable in fatty acid composition, but different in phytochemical content).

RESULTS

Both oils improved dyslipidaemia, with decreased (V)LDL-cholesterol and triglyceride levels in comparison with CON, and additional cholesterol-lowering effects of VIR over REF. While REF did not affect plasma inflammatory markers, VIR reduced circulating serum amyloid A and soluble vascular adhesion molecule-1. NAFLD and atherosclerosis development was modestly reduced in REF, and VIR strongly decreased liver steatosis and inflammation as well as atherosclerotic lesion area and severity.

CONCLUSIONS

Overall, we show that an isocaloric switch from a diet rich in saturated fat to a diet rich in unsaturated fat can attenuate NAFLD and atherosclerosis development. Phytochemical-rich virgin pumpkin seed oil exerts additional anti-inflammatory effects resulting in more pronounced health effects.

Mechanism of Altered Metformin Distribution in Nonalcoholic Steatohepatitis

Metformin is an antihyperglycemic drug that is widely prescribed for type 2 diabetes mellitus and is currently being investigated for the treatment of nonalcoholic steatohepatitis (NASH). NASH is known to alter hepatic membrane transporter expression and drug disposition similarly in humans and rodent models of NASH. Metformin is almost exclusively eliminated through the kidney primarily through active secretion mediated by Oct1, Oct2, and Mate1. The purpose of this study was to determine how NASH affects kidney transporter expression and metformin pharmacokinetics. A single oral dose of [(14)C]metformin was administered to C57BL/6J (wild type [WT]) and diabetic ob/ob mice fed either a control diet or a methionine- and choline-deficient (MCD) diet. Metformin plasma concentrations were slightly increased in the WT/MCD and ob/control groups, whereas plasma concentrations were 4.8-fold higher in ob/MCD mice compared with WT/control. The MCD diet significantly increased plasma half-life and mean residence time and correspondingly decreased oral clearance in both genotypes. These changes in disposition were caused by ob/ob- and MCD diet-specific decreases in the kidney mRNA expression of Oct2 and Mate1, whereas Oct1 mRNA expression was only decreased in ob/MCD mice. These results indicate that the diabetic ob/ob genotype and the MCD disease model alter kidney transporter expression and alter the pharmacokinetics of metformin, potentially increasing the risk of drug toxicity.

Practical approach to non-alcoholic fatty liver disease in patients with diabetes

The prevalence of Type 2 diabetes is expected to increase in parallel with obesity rates and the ageing population. Recent studies show that Type 2 diabetes is associated with a twofold increase in the risk of non-alcoholic fatty liver disease, a leading cause of chronic liver disease. Individuals with non-alcoholic steatohepatitis, a more advanced stage of non-alcoholic fatty liver disease, are specifically at risk of developing fibrosis/cirrhosis (end-stage liver disease) and hepatocellular carcinoma; therefore, identifying individuals (with Type 2 diabetes) who are likely to develop hepatic complications is paramount. In the present clinical review, we discuss the potential impact of non-alcoholic fatty liver disease diagnosis on Type 2 diabetes, and the putative risk factors for developing non-alcoholic steatohepatitis and non-alcoholic steatohepatitis fibrosis. We highlight the limitations of currently used tools in non-alcoholic fatty liver disease diagnosis and staging, and provide an insight into future developments in the field. We present an example of a non-alcoholic fatty liver disease screening protocol and discuss the therapeutic options currently available to our patients.

Intrahepatic triglyceride content is independently associated with chronic kidney disease in obese adults: A cross-sectional study

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD) are associated with some common critical cardio-metabolic risk factors. The aim of this study was to explore the association between intrahepatic triglyceride (IHTG) content and CKD in obese subjects.

METHODS

A total of 1068 obese participants received anthropometric, biochemical measurements and hepatic ultrasonography. Of those, 485 participants received magnetic resonance spectroscopy ((1)H-MRS) for the determination of IHTG content. CKD was defined as a urinary albumin:creatinine ratio (UACR)≥30 mg/g and/or estimated glomerular filtration rate (eGFR)<60 mL/min per 1.73 m(2).

RESULTS

The prevalence of CKD was significantly higher in NAFLD subjects compared to subjects without NAFLD, while the prevalence of CKD was gradually increased as the IHTG content increased by quartiles (P for trend<0.001). After adjustment for multivariate metabolic factors, the risk of abnormal albuminuria and CKD was increased by 68% [OR (95% CI): 1.68 (1.21-2.33), P<0.01] and 54% [OR (95% CI): 1.54 (1.14-2.07), P<0.01] respectively per one standard deviation (SD) increase in IHTG content. The association between IHTG content and CKD was not changed by conventional risk factors, including age, BMI and hypertension (all P<0.05).

CONCLUSION

IHTG content is independently associated with CKD in obese adults.

Intensive lifestyle treatment for non-alcoholic fatty liver disease in children with severe obesity: inpatient versus ambulatory treatment

BACKGROUND/AIMS

Lifestyle intervention is the only established therapy for non-alcoholic fatty liver disease (NAFLD). The optimal treatment schedule and predictors of response of this treatment have not been established in children. We aimed to evaluate the 2-year efficacy of an inpatient versus ambulatory intensive lifestyle intervention for treating NAFLD in children with severe obesity.

METHODS

A cohort study of 51 severely obese non-diabetic children (mean age 14.7 (±2.4) years; BMI-z-score 3.5 (±0.5)) with liver steatosis were non-randomly allocated to inpatient treatment (2 or 6 months), ambulatory treatment or usual care. Proton Magnetic Resonance Spectroscopy determined liver steatosis and serum alanine aminotransferase (ALT) at 6 months were the primary outcome measures. Baseline variables were evaluated as predictors of treatment response.

RESULTS

Liver steatosis had disappeared in 43, 29 and 22% and serum ALT normalized in 41, 33 and 6% at the end of 6 months in the inpatient, ambulatory or usual care treatment groups, respectively. Only the proportions of ALT normalization in inpatient and ambulatory treatment compared with usual care were significantly higher. Treatment effects of inpatient and ambulatory treatment were sustained at 1.5 years follow-up. No baseline characteristic, including PNPLA3 polymorphism or leptin, was consistently predictive for treatment response.

CONCLUSIONS

A 6-month intensive inpatient and ambulatory lifestyle treatment in children with severe obesity reverses NAFLD in a minority of patients. This study suggests that inpatient compared with ambulatory intensive treatment does not importantly increase treatment success. Further efforts to optimize and individualize lifestyle interventions and additional treatments options are needed particular for children with severe obesity resistant to conventional lifestyle interventions.

Nonalcoholic Fatty Liver Disease Is Independently Associated with Early Left Ventricular Diastolic Dysfunction in Patients with Type 2 Diabetes

Accumulating evidence suggests that nonalcoholic fatty liver disease (NAFLD) is associated with left ventricular diastolic dysfunction (LVDD) in nondiabetic individuals. To date, there are very limited data on this topic in patients with type 2 diabetes and it remains uncertain whether NAFLD is independently associated with the presence of LVDD in this patient population. We performed a liver ultrasonography and trans-thoracic echocardiography (with speckle-tracking strain analysis) in 222 (156 men and 66 women) consecutive type 2 diabetic outpatients with no previous history of ischemic heart disease, chronic heart failure, valvular diseases and known hepatic diseases. Binary logistic regression analysis was used to examine the association between NAFLD and the presence/severity of LVDD graded according to the current criteria of the American Society of Echocardiography, and to identify the variables that were independently associated with LVDD, which was included as the dependent variable. Patients with ultrasound-diagnosed NAFLD (n = 158; 71.2% of total) were more likely to be female, overweight/obese, and had longer diabetes duration, higher hemoglobin A1c and lower estimated glomerular filtration rate (eGFR) than those without NAFLD. Notably, they also had a remarkably greater prevalence of mild and/or moderate LVDD compared with those without NAFLD (71% vs. 33%; P<0.001). Age, hypertension, smoking, medication use, E/A ratio, LV volumes and mass were comparable between the two groups of patients. NAFLD was associated with a three-fold increased odds of mild and/or moderate LVDD after adjusting for age, sex, body mass index, hypertension, diabetes duration, hemoglobin A1c, eGFR, LV mass index and ejection fraction (adjusted-odds ratio 3.08, 95%CI 1.5–6.4, P = 0.003). In conclusion, NAFLD is independently associated with early LVDD in type 2 diabetic patients with preserved systolic function.

Nonalcoholic fatty liver disease and decreased bone mineral density: is there a link?

PURPOSE

Liver diseases are associated with decreased bone mineral density (BMD) and evidence suggests that nonalcoholic fatty liver disease (NAFLD) affects several extra-hepatic organs, interacting with the regulation of multiple endocrine and metabolic pathways. This review focuses on the rapidly expanding body of evidence that supports a strong association between NAFLD and the risk of decreased BMD, expression of low bone mass (osteoporosis), or reduced mineralization (osteomalacia).

METHODS

We identified studies by searching PubMed for original articles published in English through March 2015 using the keywords "nonalcoholic fatty liver disease" or "fatty liver" combined with "bone mineral density", "osteoporosis", or "osteomalacia".

RESULTS

Recent cross-sectional and case-control studies involving both adults and children have consistently shown that patients with NAFLD exhibit a greater prevalence of decreased BMD compared with age-, sex-, and body mass index-matched healthy controls. Accumulating clinical and experimental evidence suggests that NAFLD may contribute to the pathophysiology of low BMD, possibly through the direct contribution of NAFLD to whole-body and hepatic insulin resistance and/or the systemic release of multiple pro-inflammatory, pro-coagulant, and pro-fibrogenic mediators.

CONCLUSIONS

Although more research is needed before firm conclusions can be drawn, it appears that there is a non-chance, statistical association between NAFLD and low BMD. This finding argues for more careful monitoring and evaluation of BMD among patients with NAFLD. The potential contribution of NAFLD itself to the development and progression of decreased BMD warrants further study.

Obesity and Gestational Diabetes Mellitus Pathways for Programming in Mouse, Monkey, and Man—Where Do We Go Next? The 2014 Norbert Freinkel Award Lecture

Obesity and gestational diabetes mellitus continue to increase worldwide and span the spectrum of age, race, ethnicity, and socioeconomic status. Alarmingly, 1 in 10 infants and toddlers is obese, and 1 in 5 youths is both obese and at risk for metabolic syndrome prior to puberty. The mechanisms underlying how poor maternal health imparts risk for future metabolic disease in the offspring are beginning to emerge in deeply phenotyped human and nonhuman primate models. Maternal diet and obesity impact fuels, hormones, and inflammation with powerful effects on fetal metabolic systems. These are accompanied by persistent changes in the infant microbiome and epigenome and in offspring behavior. These results suggest that gestational and lactational dietary exposures are driving health risks in the next generation. Whether maternal diet can prevent changes in the womb to alter infant life-course disease risk is still unknown. Controlled, mechanistic studies to identify interventions are sorely needed for a healthier next generation.

Heart valve calcification in patients with type 2 diabetes and nonalcoholic fatty liver disease

PURPOSE

Aortic valve sclerosis (AVS) and mitral annulus calcification (MAC) are two powerful predictors of adverse cardiovascular outcomes in patients with type 2 diabetes, but the etiology of valvular calcification is uncertain. Nonalcoholic fatty liver disease (NAFLD) is an emerging cardiovascular risk factor and is very common in type 2 diabetes, but whether NAFLD is associated with valvular calcification in this group of patients is presently unknown.

METHODS

We undertook a cross-sectional study of 247 consecutive type 2 diabetic outpatients with no previous history of heart failure, valvular heart diseases (aortic stenosis, mitral stenosis, moderate or severe aortic and mitral regurgitation) or hepatic diseases. Presence of MAC and AVS was detected by echocardiography. NAFLD was diagnosed by ultrasonography.

RESULTS

Overall, 139 (56.3%) patients had no heart valve calcification (HVC-0), 65 (26.3%) patients had one valve affected (HVC-1) and 43 (17.4%) patients had both valves affected (HVC-2). 175 (70.8%) patients had NAFLD and the prevalence of this disease markedly increased in patients with HVC-2 compared with either HVC-1 or HVC-0 (86.1% vs. 83.1% vs. 60.4%, respectively; p < 0.001). NAFLD was significantly associated with AVS and/or MAC (unadjusted-odds ratio 3.51, 95% CI 1.89-6.51, p < 0.001). Adjustments for age, sex, waist circumference, smoking, blood pressure, hemoglobin A1c, LDL-cholesterol, kidney function parameters, medication use and echocardiographic variables did not appreciably weaken this association (adjusted-odds ratio 2.70, 95% CI 1.23-7.38, p < 0.01).

CONCLUSIONS

Our results show that NAFLD is an independent predictor of cardiac calcification in both the aortic and mitral valves in patients with type 2 diabetes.

Influence of the PNPLA3 rs738409 Polymorphism on Non-Alcoholic Fatty Liver Disease and Renal Function among Normal Weight Subjects

In normal weight subjects (body mass index < 25 kg/m2), non-alcoholic fatty liver disease (NAFLD) is likely to coexist with metabolic diseases. The patatin-like phospholipase 3 (PNPLA3) polymorphism rs738409 (c.444C>G) is associated with the risk of NAFLD and/or renal dysfunction; however, the influence of the weight status on the associations remains unknown. We aimed to clarify the associations of the PNPLA3 polymorphism with the risk of NAFLD and/or renal dysfunction, while also paying careful attention to the weight status of the subjects. Cross-sectional and retrospective longitudinal studies with 5.5 ± 1.1 years of follow-up were conducted in 740 and 393 Japanese participants (61.2 ± 10.5 and 67.5 ± 6.0 years), respectively, during a health screening program. Among 591 subjects who did not have a habitual alcohol intake and/or hepatitis B or C virus infections, the PNPLA3 G/G genotype was associated with the risk for NAFLD in normal weight subjects [odds ratio (95% CI): 3.06 (1.11-8.43), P < 0.05]. Among all subjects, carriers of the PNPLA3 G/G genotype with a normal weight had a lower eGFR than those of the C/C genotype [partial regression coefficient (SE): -3.26 (1.48), P < 0.05]. These associations were replicated in the longitudinal analyses. Among the overweight subjects, none of the genotypes were significantly associated in the cross-sectional and longitudinal analyses; however, the power of the analyses was small, especially in the analyses among overweight subjects. The findings of this study suggest that carriers of the PNPLA3 G/G genotype with a normal weight status should nevertheless be carefully monitored for the presence of NAFLD and/or renal dysfunction.

Association of serum retinoic acid with hepatic steatosis and liver injury in nonalcoholic fatty liver disease

BACKGROUND

Retinoic acid (RA), an active metabolite of vitamin A (retinol), has been implicated in the regulation of lipid metabolism and hepatic steatosis in animal models. However, the relation between RA and liver histology in patients with nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) is unknown.

OBJECTIVE

This study aimed at examining the association of RA with NAFLD and NASH in Chinese subjects.

DESIGN

Serum RA concentration was determined by ELISA in 41 control subjects, 45 patients with NAFLD, and 38 patients with NASH. The associations of RA with adiposity, serum glucose, lipid profiles, and markers of liver damage were studied. Moreover, both mRNA and protein levels of retinoic X receptor α (RXRα) in the liver were analyzed in subjects with different degrees of hepatic steatosis.

RESULTS

Serum RA concentrations in patients with NAFLD (1.42 ± 0.47 ng/mL) and NASH (1.14 ± 0.26 ng/mL) were significantly lower than those in control subjects (2.70 ± 0.52 ng/mL) (P < 0.01). Furthermore, serum RA concentrations were significantly different between subjects with normal glucose tolerance and those with type 2 diabetes in control [2.87 ± 0.52 (n = 28) vs. 2.32 ± 0.44 ng/mL (n = 13)], NAFLD [1.61 ± 0.37 (n = 29) vs. 1.28 ± 0.41 ng/mL (n = 16)], and NASH [1.35 ± 0.34 (n = 24) vs. 1.07 ± 0.29 ng/mL (n = 14)] groups. In human liver tissue, RXRα mRNA expression was inversely correlated with the exacerbation of hepatic steatosis. Both serum RA concentrations and RXRα mRNA levels were inversely correlated with intrahepatic triglyceride content (r = -0.700, P < 0.001, and r = -0.611, P = 0.002, respectively). Compared with grade 0 severity, the concentration of RXRα protein was lower in more severe grades in patients with NAFLD.

CONCLUSION

These results show that circulating RA concentrations were lower in subjects with NAFLD and were associated with hepatic lipid metabolism and insulin resistance. This trial was registered at clinicaltrials.gov as NCT01940263.

Predictors of malignancies and overall mortality in Japanese patients with biopsy-proven non-alcoholic fatty liver disease

AIM

Some patients with non-alcoholic fatty liver disease (NAFLD) develop hepatocellular carcinoma (HCC) and have higher mortality than others. The evidence causally linking NAFLD to extrahepatic malignancies is scarce. Our aim was to determine the incidence of and risk factors for HCC, extrahepatic cancer and mortality in Japanese patients with biopsy-proven NAFLD.

METHODS

This retrospective cohort study analyzed outcomes including onset of malignant tumors and death in 312 patients with NAFLD diagnosed by liver biopsy.

RESULTS

Of 312 patients, 176 (56.4%) were diagnosed with non-alcoholic steatohepatitis. During a median follow-up period of 4.8 years (range, 0.3-15.8), six patients (1.9%) developed HCC, and 20 (6.4%) developed extrahepatic cancer. Multivariate analysis identified fibrosis stage (≥3; hazard ratio [HR], 12.3; 95% confidence interval [CI], 1.11-136.0; P = 0.041) as a predictor for HCC and type IV collagen 7s (>5 ng/mL; HR, 1.74; 95% CI, 1.08-2.79; P = 0.022) as a predictor for extrahepatic cancer. Eight patients (2.6%) died during the follow-up period. The most common cause of death was extrahepatic malignancy. None died of cardiovascular disease. Multivariate analysis identified type IV collagen 7s (>5 ng/mL; HR, 3.38; 95% CI, 1.17-9.76; P = 0.024) as a predictor for mortality.

CONCLUSION

The incidence of extrahepatic cancer was higher than that of HCC. Severe fibrosis was a predictor for HCC. Patients with NAFLD and elevated type IV collagen 7s levels are at increased risk for extrahepatic cancer and overall mortality.

Serum Chemerin Levels in relation to Osteoporosis and Bone Mineral Density: A Case-Control Study

BACKGROUND

To evaluate serum chemerin levels in patients with osteoporosis and healthy controls and to investigate the relationship between serum chemerin levels and bone mineral density (BMD).

METHODS

An age- and gender-matched case-control study was conducted. Pearson's correlation test was performed to investigate the relationship between serum chemerin levels and BMD.

RESULTS

There were 93 patients included in the osteoporosis group and 93 matched controls. Serum chemerin level was significantly higher in patients with osteoporosis (87.27 ± 5.80 ng/mL) than patients in control (71.13 ± 5.12 ng/mL) (P < 0.01). There was a negative correlation between femoral bone mineral density and chemerin in both groups (R = -0.395, P < 0.01 in osteoporosis group; R = -0.680, P < 0.01 in control) and also a negative correlation between lumbar bone mineral density with chemerin in both groups (R = -0.306, P < 0.01 in osteoporosis group; R = -0.362, P < 0.01 in control).

CONCLUSIONS

Patients with osteoporosis presented a higher level of serum chemerin, which witnessed an inverse correlation with BMD. Further studies are needed to explore the role of chemerin in the pathophysiology of osteoporosis.

Cardiovascular risk across the histological spectrum and the clinical manifestations of non-alcoholic fatty liver disease: An update

Non-alcoholic fatty liver disease (NAFLD) is considered to be an independent cardiovascular disease (CVD) risk factor. However, simple steatosis has a benign clinical course without excess mortality. In contrast, the advanced form of NAFLD, non-alcoholic steatohepatitis (NASH) with liver fibrosis increases mortality by approximately 70%, due to an increase in CVD mortality by approximately 300%. Chronic kidney disease (CKD) may be caused by NAFLD/NASH and it substantially increases CVD risk, especially in the presence of type 2 diabetes mellitus. Moreover, CKD may trigger NAFLD/NASH deterioration in a vicious cycle. NAFLD/NASH is also related to increased arterial stiffness (AS), an independent CVD risk factor that further raises CVD risk. Diagnosis of advanced liver fibrosis (mainly by simple non-invasive tests), CKD, and increased AS should be made early in the course of NAFLD and treated appropriately. Lifestyle measures and statin treatment may help resolve NAFLD/NASH and beneficially affect the CVD risk factors mentioned above.

S100A9: A Potential Biomarker for the Progression of Non-Alcoholic Fatty Liver Disease and the Diagnosis of Non-Alcoholic Steatohepatitis

Non-alcoholic fatty liver (NAFL) has the potential to progress to non-alcoholic steatohepatitis (NASH) or to promote type 2 diabetes mellitus (T2DM). However, NASH and T2DM do not always develop coordinately. Additionally, there are no definite noninvasive methods for NASH diagnosis currently. We established rat models of NAFL, NASH, and NAFL + T2DM to recapitulate different phenotypes associated with non-alcoholic fatty liver disease (NAFLD) and its progression. Histologic features of rat livers were scored according to criteria established by the Nonalcoholic Steatohepatitis Clinical Research Network. Microarray was performed to assess gene expression changes in rat livers. We find that gene expression of s100a9 was higher in NAFL group compared with control, and was increased in NASH groups and decreased in NAFL + T2DM group compared with NAFL. In contrast, srebf1, tbx21, and gimap4 only showed limited discriminating abilities in different groups. There is a significant positive correlation between serum levels of S100A9 and NAFLD Activity Score (NAS), the severity of hepatic steatosis, and lobular inflammation (r = 0.80, 0.64 and 0.86, P < 0.001). These findings suggest that S100A9 may be extremely useful in the diagnosis of NASH (AUROC: 0.947, CI: 0.845-1.049). Additionally, serum S100A9 levels displayed a strong correlation with ALT, AST and TBil (r = 0.81, 0.89 and 0.91, P < 0.001) but a weak correlation with FBG, HOMA-IR, TG, and TC (r = -0.41, -0.40, 0.47 and 0.49, P < 0.05). Conclusions: The results we provide here suggest that S100A9 may be useful as a biomarker for the hepatic and metabolic progression of NAFLD and the non-invasive diagnosis of NASH.