Genetics of nonalcoholic fatty liver disease

DGAT1 and DGAT2 Inhibitors for Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) Management: Benefits for Their Single or Combined Application

Inhibiting diacylglycerol acetyltransferase (DGAT1, DGAT2) enzymes (iDGAT1, iDGAT2), involved in triglyceride (TG) synthesis, improves hepatic steatosis in metabolic dysfunction-associated steatotic liver disease (MASLD) patients. However, their potential synergism in disease onset (SLD) and progression (metabolic dysfunction-associated steatohepatitis, fibrosis) has been poorly explored. We investigated iDGAT1 and iDGAT2 efficacy, alone or combined (iDGAT1/2) on fat accumulation and hepatocellular injury in hepatocytes (HepG2) and on fibrogenic processes in hepatic stellate cells (LX2). We further tested whether the addition of MitoQ antioxidant to iDGAT1/2 would enhance their effects. SLD and MASH conditions were reproduced in vitro by supplementing Dulbecco's Modified Eagle's Medium (DMEM) with palmitic/oleic acids (PAOA) alone (SLD-medium), or plus Lipopolisaccaride (LPS), fructose, and glucose (MASH-medium). In SLD-medium, iDGAT1 and iDGAT2 individually, and even more in combination, reduced TG synthesis in HepG2 cells. Markers of hepatocellular damage were slightly decreased after single iDGAT exposure. Conversely, iDGAT1/2 counteracted ER/oxidative stress and inflammation and enhanced mitochondrial Tricarboxylic acid cycle (TCA) and respiration. In HepG2 cells under a MASH-like condition, only iDGAT1/2 effectively ameliorated TG content and oxidative and inflammatory mediators, further improving bioenergetic balance. LX2 cells, challenged with SLD/MASH media, showed less proliferation and slower migration rates in response to iDGAT1/2 drugs. MitoQ combined with iDGAT1/2 improved cell viability and dampened free fatty acid release by stimulating β-oxidation. Dual DGAT inhibition combined with antioxidants open new perspectives for MASLD management.

Unravelling the complexities of non-alcoholic steatohepatitis: The role of metabolism, transporters, and herb-drug interactions

Nonalcoholic fatty liver disease (NAFLD) is a mainstream halting liver disease with high prevalence in North America, Europe, and other world regions. It is an advanced form of NAFLD caused by the amassing of fat in the liver and can progress to the more severe form known as non-alcoholic steatohepatitis (NASH). Until recently, there was no authorized pharmacotherapy reported for NASH, and to improve the patient's metabolic syndrome, the focus is mainly on lifestyle modification, weight loss, ensuring a healthy diet, and increased physical activity; however, the recent approval of Rezdiffra (Resmetirom) by the US FDA may change this narrative. As per the reported studies, there is an increased articulation of uptake and efflux transporters of the liver, including OATP and MRP, in NASH, leading to changes in the drug's pharmacokinetic properties. This increase leads to alterations in the pharmacokinetic properties of drugs. Furthermore, modifications in Cytochrome P450 (CYP) enzymes can have a significant impact on these properties. Xenobiotics are metabolized primarily in the liver and constitute liver enzymes and transporters. This review aims to delve into the role of metabolism, transport, and potential herb-drug interactions in the context of NASH.

Implementation of multiomic mass spectrometry approaches for the evaluation of human health following environmental exposure

Omics analyses collectively refer to the possibility of profiling genetic variants, RNA, epigenetic markers, proteins, lipids, and metabolites. The most common analytical approaches used for detecting molecules present within biofluids related to metabolism are vibrational spectroscopy techniques, represented by infrared, Raman, and nuclear magnetic resonance (NMR) spectroscopies and mass spectrometry (MS). Omics-based assessments utilizing MS are rapidly expanding and being applied to various scientific disciplines and clinical settings. Most of the omics instruments are operated by specialists in dedicated laboratories; however, the development of miniature portable omics has made the technology more available to users for field applications. Variations in molecular information gained from omics approaches are useful for evaluating human health following environmental exposure and the development and progression of numerous diseases. As MS technology develops so do statistical and machine learning methods for the detection of molecular deviations from personalized metabolism, which are correlated to altered health conditions, and they are intended to provide a multi-disciplinary overview for researchers interested in adding multiomic analysis to their current efforts. This includes an introduction to mass spectrometry-based omics technologies, current state-of-the-art capabilities and their respective strengths and limitations for surveying molecular information. Furthermore, we describe how knowledge gained from these assessments can be applied to personalized medicine and diagnostic strategies.

Evolution of liver fibrosis in diabetic patients with NAFLD in a follow-up study: Hepatoprotective effects of sodium-glucose co-transporter-2 inhibitors

BACKGROUND AND AIMS

Patients with non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM) are at high risk of hepatic fibrosis. To prospectively evaluate changes in fibrosis in diabetic patients with NAFLD, predisposing factors and sodium glucose cotransporter 2 inhibitors (SGLT2i) influence.

METHODS

237 T2DM outpatients (mean age 67 ± 9 years, 54% male) were enrolled and re-evaluated after 52 ± 10 months. At baseline and follow-up NAFLD and liver fibrosis (LSM) were detected by ultrasonography and Fibroscan®.

RESULTS

During follow-up an increase in LSM (6.0 ± 2.8 vs 5.8 ± 2.7 kPa, p = 0.02) and in the prescription of SGLT2i (20% vs 6%, p<0.001) was registered, despite stability of diabetic control. LSM worsened in 133(56%) subjects, 92 (39%) with worsening >10% from baseline. Patients with worsening versus non worsening of LSM had higher prevalence of increase in BMI during follow-up (45% vs 32%, p = 0.06) and lower SGLT2i prescription (15% vs 27%, p = 0.034). In multivariate analysis use of SGLT2-inhibitors at follow-up reduced the risk of LSM worsening (HR 0.34, 95% CI 0.13-0.88), even when considered>10% from baseline.

CONCLUSIONS

A high prevalence of fibrosis progression was observed in diabetic subjects with NAFLD over a nearly 5-years follow up and SGLT2-inhibitors seem to reduce the risk of worsening of liver stiffness.

Evaluation of long acting GLP1R/GCGR agonist in a DIO and biopsy-confirmed mouse model of NASH suggest a beneficial role of GLP-1/glucagon agonism in NASH patients

OBJECTIVE

The metabolic benefits of GLP-1 receptor (GLP-1R) agonists on glycemic and weight control are well established as therapy for type 2 diabetes and obesity. Glucagon's ability to increase energy expenditure is well described, and the combination of these mechanisms-of-actions has the potential to further lower hepatic steatosis in metabolic disorders and could therefore be attractive for the treatment for non-alcoholic steatohepatitis (NASH). Here, we have investigated the effects of a dual GLP-1/glucagon receptor agonist NN1177 on hepatic steatosis, fibrosis, and inflammation in a preclinical mouse model of NASH. Having observed strong effects on body weight loss in a pilot study with NN1177, we hypothesized that direct engagement of the hepatic glucagon receptor (GCGR) would result in a superior effect on steatosis and other liver related parameters as compared to the GLP-1R agonist semaglutide at equal body weight.

METHODS

Male C57Bl/6 mice were fed a diet high in trans-fat, fructose, and cholesterol (Diet-Induced Obese (DIO)-NASH) for 36 weeks. Following randomization based on the degree of fibrosis at baseline, mice were treated once daily with subcutaneous administration of a vehicle or three different doses of NN1177 or semaglutide for 8 weeks. Hepatic steatosis, inflammation and fibrosis were assessed by immunohistochemistry and morphometric analyses. Plasma levels of lipids and liver enzymes were determined, and hepatic gene expression was analyzed by RNA sequencing.

RESULTS

NN1177 dose-dependently reduced body weight up to 22% compared to vehicle treatment. Plasma levels of ALT, a measure of liver injury, were reduced in all treatment groups with body weight loss. The dual agonist reduced hepatic steatosis to a greater extent than semaglutide at equal body weight loss, as demonstrated by three independent methods. Both the co-agonist and semaglutide significantly decreased histological markers of inflammation such as CD11b and Galectin-3, in addition to markers of hepatic stellate activation (αSMA) and fibrosis (Collagen I). Interestingly, the maximal beneficial effects on above mentioned clinically relevant endpoints of NN1177 treatment on hepatic health appear to be achieved with the middle dose tested. Administering the highest dose resulted in a further reduction of liver fat and accompanied by a massive induction in genes involved in oxidative phosphorylation and resulted in exaggerated body weight loss and a downregulation of a module of co-expressed genes involved in steroid hormone biology, bile secretion, and retinol and linoleic acid metabolism that are also downregulated due to NASH itself.

CONCLUSIONS

These results indicate that, in a setting of overnutrition, the liver health benefits of activating the fasting-related metabolic pathways controlled by the glucagon receptor displays a bell-shaped curve. This observation is of interest to the scientific community, due to the high number of ongoing clinical trials attempting to leverage the positive effects of glucagon biology to improve metabolic health.

Distinct roles of telomerase activity in age-related chronic diseases: An update literature review

Although telomerase has low activity in somatic quiescent cells, it plays an significant roles in regenerative cells such as endothelial cells, hepatocytes, epithelial cells, and hemocytes. Telomerase activity and telomere length are critical factors in age-related chronic diseases as they are closely related to cell senescence. However, whether telomerase activity plays a key role in disease progression or whether the role of telomerase is unified among different diseases are unresolved. Considering that aging is the most important risk factor for neurodegenerative and metabolic diseases, this article will analyze the evidence, mechanism, and therapeutic potential of telomerase activity in several chronic disease, including type 2 diabetes, neurodegenerative diseases, atherosclerosis, heart failure and non-alcoholic fatty liver disease, in order to provide clues for the use of telomerase activity to target the treatment of age-related chronic diseases.

Sarcopenia, sarcopenic obesity and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), sarcopenia and sarcopenic obesity (SO) are highly prevalent conditions that may coexist, especially in the aging population, without any approved pharmacologic treatment for all of them. There are multiple pathophysiologic mechanisms suggested to explain an association between NAFLD and sarcopenia or SO, including alterations in the adipokines, cytokines, hepatokines and myokines, which may interplay with other factors, such as aging, diet and physical inactivity. In clinical terms, most observational studies support an association between NAFLD and sarcopenia or SO; importantly, there are few cohort studies indicating higher mortality in patients with NAFLD and sarcopenia. Their association also bears some treatment considerations: for example, pioglitazone or vitamin E, suggested as off label treatment for selected patients with nonalcoholic steatohepatitis, may be recommended in the coexistence of sarcopenia or SO, since limited evidence did not show adverse effects of them on sarcopenia and abdominal obesity. In this review, evidence linking sarcopenia and SO with NAFLD is summarized, with a special focus on clinical data. A synopsis of the major pathophysiological links between NAFLD and sarcopenia/SO is initially presented, followed by selected clinical studies and, finally, treatment considerations in patients with NAFLD and sarcopenia or SO are discussed.

Is increased myocardial triglyceride content associated with early changes in left ventricular function? A 1H-MRS and MRI strain study

Background

Type 2 diabetes (T2D) and obesity induce left ventricular (LV) dysfunction. The underlying pathophysiological mechanisms remain unclear, but myocardial triglyceride content (MTGC) could be involved.

Objectives

This study aimed to determine which clinical and biological factors are associated with increased MTGC and to establish whether MTGC is associated with early changes in LV function.

Methods

A retrospective study was conducted using five previous prospective cohorts, leading to 338 subjects studied, including 208 well-phenotyped healthy volunteers and 130 subjects living with T2D and/or obesity. All the subjects underwent proton magnetic resonance spectroscopy and feature tracking cardiac magnetic resonance imaging to measure myocardial strain.

Results

MTGC content increased with age, body mass index (BMI), waist circumference, T2D, obesity, hypertension, and dyslipidemia, but the only independent correlate found in multivariate analysis was BMI (p=0.01; R²=0.20). MTGC was correlated to LV diastolic dysfunction, notably with the global peak early diastolic circumferential strain rate (r=-0.17, p=0.003), the global peak late diastolic circumferential strain rate (r=0.40, p<0.0001) and global peak late diastolic longitudinal strain rate (r=0.24, p<0.0001). MTGC was also correlated to systolic dysfunction via end-systolic volume index (r=-0.34, p<0.0001) and stroke volume index (r=-0.31, p<0.0001), but not with longitudinal strain (r=0.009, p=0.88). Interestingly, the associations between MTGC and strain measures did not persist in multivariate analysis. Furthermore, MTGC was independently associated with LV end-systolic volume index (p=0.01, R²=0.29), LV end-diastolic volume index (p=0.04, R²=0.46), and LV mass (p=0.002, R²=0.58).

Conclusions

Predicting MTGC remains a challenge in routine clinical practice, as only BMI independently correlates with increased MTGC. MTGC may play a role in LV dysfunction but does not appear to be involved in the development of subclinical strain abnormalities.

Molecular Screening via Sanger Sequencing of the Genetic Variants in Non-Alcoholic Fatty Liver Disease Subjects in the Saudi Population: A Hospital-Based Study

Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases, along with steatosis and non-alcoholic steatohepatitis (NASH), and is associated with cirrhosis and hepatocellular carcinoma. Candidate gene and genome-wide association studies have validated the relationships between NAFLD, NASH, PNPLA3, TM6SF2, and HFE. The present study utilized five polymorphisms in three genes: PNPLA3 (I148M and K434E) TM6SF2 (E167K), and HFE (H63D and C282Y), based on undocumented case−control studies in the Saudi Arabian population. A total of 95 patients with NAFLD and 78 non-NAFLD subjects were recruited. Genomic DNA was isolated, and polymerase chain reaction and Sanger sequencing were performed using specific primers for the I148M, K434E, E167K, H63D, and C282Y. NAFLD subjects were older when compared to controls and showed the significant association (p = 0.0001). Non-significant association was found between gender (p = 0.26). However, both weight and BMI were found to be associated. Hardy−Weinberg equilibrium analysis confirmed that H63D, I148M, and K434E polymorphisms were associated. Genotype analysis showed only K434E variant was associated with NAFLD and non-NAFLD (OR-2.16; 95% CI: 1.08−4.31; p = 0.02). However, other polymorphisms performed with NAFLD and NASH were not associated (p > 0.05), and similar analysis was found when ANOVA was performed (p > 0.05). In conclusion, we confirmed that K434E polymorphism showed a positive association in the Saudi population.

Non-alcoholic fatty liver disease establishment and progression: genetics and epigenetics as relevant modulators of the pathology

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) results from metabolic dysfunctions that affect more than one-third of the world population. Over the last decades, scientific investigations have clarified many details on the pathology establishment and development; however, effective therapeutics approaches are still evasive. In addition, studies demonstrated that NAFLD establishment and progression are related to several etiologies. Recently, genetics and epigenetics backgrounds have emerged as relevant elements to the pathology onset, and, hence, deserve deep investigation to clarify molecular details on NAFLD signaling, which may be correlated with population behavior. Thus, to minimize the global problem, public health and public policies should take advantage of studies on NAFLD over the next following decades.

METHODS

In this context, we have performed a selective literature review focusing on biochemistry of lipid metabolism, genetics, epigenetics, and the ethnicity as strong elements that drive NAFLD establishment.

RESULTS

Considering the etiological agents that acts on NAFLD development and progression, the genetics and the epigenetics emerged as relevant factors. Genetics acts as a powerful element in the establishment and progression of the NAFLD. Over the last decades, details concerning genes and their polymorphisms, as well as epigenetics, have been considered relevant elements in the systems biology of diseases, and their effects on NAFLD should be considered in-depth, as well as the ethnicity, clarifying whether people are susceptible to liver diseases. Moreover, the endemicity and social problems of hepatic disfunction are far to be solved, which require a combined effort of various sectors of society.

CONCLUSION

Hence, the elements presented and discussed in this short review demonstrated their relevance to the physiological control of NAFLD, opening perspectives for research to develop new strategy to treat fatty liver diseases.

Low Lipoprotein(a) Levels Predict Hepatic Fibrosis in Patients With Nonalcoholic Fatty Liver Disease

Dyslipidemia and cardiovascular complications are comorbidities of nonalcoholic fatty liver disease (NAFLD), which ranges from simple steatosis to nonalcoholic steatohepatitis, fibrosis, and cirrhosis up to hepatocellular carcinoma. Lipoprotein(a) (Lp(a)) has been associated with cardiovascular risk and metabolic abnormalities, but its impact on the severity of liver damage in patients with NAFLD remains to be clarified. Circulating Lp(a) levels were assessed in 600 patients with biopsy-proven NAFLD. The association of Lp(a) with liver damage was explored by categorizing serum Lp(a) into quartiles. The receiver operating characteristic curve was used to analyze the accuracy of serum Lp(a) in hepatic fibrosis prediction. Hepatic expression of lipoprotein A (LPA) and of genes involved in lipid metabolism and fibrogenic processes were evaluated by RNA sequencing in a subset of patients with NAFLD for whom Lp(a) dosage was available (n = 183). In patients with NAFLD, elevated Lp(a) levels were modestly associated with circulating lipids, carotid plaques, and hypertension (P < 0.05). Conversely, patients with low serum Lp(a) displayed insulin resistance (P < 0.05), transaminase elevation (P < 0.05), and increased risk of developing severe fibrosis (P = 0.007) and cirrhosis (P = 0.002). In addition, the diagnostic accuracy of Lp(a) in predicting fibrosis increased by combining it with transaminases (area under the curve fibrosis stage 4, 0.87; P < 0.0001). Hepatic LPA expression reflected serum Lp(a) levels (P = 0.018), and both were reduced with the progression of NAFLD (P < 0.05). Hepatic LPA messenger RNA levels correlated with those of genes involved in lipoprotein release, lipid synthesis, and fibrogenesis (P < 0.05). Finally, transmembrane 6 superfamily member 2 (TM6SF2) rs58542926, apolipoprotein E (ApoE) rs445925, and proprotein convertase subtilisin/kexin type 9 (PCSK9) rs7552841, known variants that modulate circulating lipids, may influence serum Lp(a) levels (P < 0.05). Conclusion: Circulating Lp(a) combined with transaminases may represent a novel noninvasive biomarker to predict advanced fibrosis in patients with NAFLD.

Impact of Genetic Polymorphism on Response to Therapy in Non-Alcoholic Fatty Liver Disease

In the last decades, the global prevalence of non-alcoholic fatty liver disease (NAFLD) has reached pandemic proportions with derived major health and socioeconomic consequences; this tendency is expected to be further aggravated in the coming years. Obesity, insulin resistance/type 2 diabetes mellitus, sedentary lifestyle, increased caloric intake and genetic predisposition constitute the main risk factors associated with the development and progression of the disease. Importantly, the interaction between the inherited genetic background and some unhealthy dietary patterns has been postulated to have an essential role in the pathogenesis of NAFLD. Weight loss through lifestyle modifications is considered the cornerstone of the treatment for NAFLD and the inter-individual variability in the response to some dietary approaches may be conditioned by the presence of different single nucleotide polymorphisms. In this review, we summarize the current evidence on the influence of the association between genetic susceptibility and dietary habits in NAFLD pathophysiology, as well as the role of gene polymorphism in the response to lifestyle interventions and the potential interaction between nutritional genomics and other emerging therapies for NAFLD, such as bariatric surgery and several pharmacologic agents.

Drug-induced Fatty Liver Disease: Pathogenesis and Treatment

Metabolic dysfunction-associated fatty liver disease (commonly known as MAFLD) impacts global health in epidemic proportions, and the resulting morbidity, mortality and economic burden is enormous. While much attention has been given to metabolic syndrome and obesity as offending factors, a growing incidence of polypharmacy, especially in the elderly, has greatly increased the risk of drug-induced liver injury (DILI) in general, and drug-induced fatty liver disease (DIFLD) in particular. This review focuses on the contribution of DIFLD to DILI in terms of epidemiology, pathophysiology, the most common drugs associated with DIFLD, and treatment strategies.

Genetics Is of the Essence to Face NAFLD

Nonalcoholic fatty liver disease (NAFLD) is the commonest cause of chronic liver disease worldwide. It is closely related to obesity, insulin resistance (IR) and dyslipidemia so much so it is considered the hepatic manifestation of the Metabolic Syndrome. The NAFLD spectrum extends from simple steatosis to nonalcoholic steatohepatitis (NASH), a clinical condition which may progress up to fibrosis, cirrhosis and hepatocellular carcinoma (HCC). NAFLD is a complex disease whose pathogenesis is shaped by both environmental and genetic factors. In the last two decades, several heritable modifications in genes influencing hepatic lipid remodeling, and mitochondrial oxidative status have been emerged as predictors of progressive hepatic damage. Among them, the patatin-like phospholipase domain-containing 3 (PNPLA3) p.I148M, the Transmembrane 6 superfamily member 2 (TM6SF2) p.E167K and the rs641738 membrane bound-o-acyltransferase domain-containing 7 (MBOAT7) polymorphisms are considered the most robust modifiers of NAFLD. However, a forefront frontier in the study of NAFLD heritability is to postulate score-based strategy, building polygenic risk scores (PRS), which aggregate the most relevant genetic determinants of NAFLD and biochemical parameters, with the purpose to foresee patients with greater risk of severe NAFLD, guaranteeing the most highly predictive value, the best diagnostic accuracy and the more precise individualized therapy.

Multi-omics profiling: the way towards precision medicine in metabolic diseases

Metabolic diseases including type 2 diabetes mellitus (T2DM), non-alcoholic fatty liver disease (NAFLD), and metabolic syndrome (MetS) are alarming health burdens around the world, while therapies for these diseases are far from satisfying as their etiologies are not completely clear yet. T2DM, NAFLD, and MetS are all complex and multifactorial metabolic disorders based on the interactions between genetics and environment. Omics studies such as genetics, transcriptomics, epigenetics, proteomics, and metabolomics are all promising approaches in accurately characterizing these diseases. And the most effective treatments for individuals can be achieved via omics pathways, which is the theme of precision medicine. In this review, we summarized the multi-omics studies of T2DM, NAFLD, and MetS in recent years, provided a theoretical basis for their pathogenesis and the effective prevention and treatment, and highlighted the biomarkers and future strategies for precision medicine.

Telomerase: a key player in the pathogenesis of non-alcoholic fatty liver disease?

Introduction: Telomerase is a basic nuclear protein reverse transcriptase, which plays a key role in maintaining telomere stability, genome integrity, long-term cell activity, and potential continued proliferation.Area covered: This narrative review discusses key research advances involving telomerase in the development and progression of nonalcoholic fatty liver disease (NAFLD). The review evaluates 9a) whether the assessment of telomerase can be used as a noninvasive diagnostic tool; and (b) whether modification of telomerase function might be a useful potential therapeutic target for treatment of NAFLD. Furthermore, the relationship between telomerase and other chronic metabolic diseases is evaluated.Expert opinion: Several experimental and preclinical studies have suggested that telomerase plays an important role in the development of NAFLD. However, further mechanistic studies are needed to prove a causal relationship and to better elucidate whether the measurement of telomerase has utility as a diagnostic tool or whether pharmacological manipulation of telomerase has therapeutic potential in NAFLD treatment.

Bile acids profile, histopathological indices and genetic variants for non-alcoholic fatty liver disease progression

OBJECTIVE

Metabolomic studies suggest plasma levels of bile acids (BAs) are elevated amongst subjects with non-alcoholic fatty liver disease (NAFLD) compared to healthy controls. However, it remains unclear whether or not specific BAs are associated with the clinically relevant transition from nonalcoholic fatty liver (i.e. simple steatosis) to non-alcoholic steatohepatitis (NASH), or enhanced progression of hepatic fibrosis, or genetic determinants of NAFLD/NASH.

METHODS

Among sequential subjects (n=102) undergoing diagnostic liver biopsy, we examined the associations of a broad panel of BAs with distinct histopathological features of NAFLD, the presence of NASH, and their associations with genetic variants linked to NAFLD and NASH.

RESULTS

Plasma BA alterations were observed through the entire spectrum of NAFLD, with several glycine conjugated forms of the BAs demonstrating significant associations with higher grades of inflammation and fibrosis. Plasma 7-Keto-DCA levels showed the strongest associations with advanced stages of hepatic fibrosis [odds ratio(95% confidence interval)], 4.2(1.2-16.4), NASH 24.5(4.1-473), and ballooning 18.7(4.8-91.9). Plasma 7-Keto-LCA levels were associated with NASH 9.4(1.5-185) and ballooning 5.9(1.4-28.8). Genetic variants at several NAFLD/NASH loci were nominally associated with increased levels of 7-Keto- and glycine-conjugated forms of BAs, and the NAFLD risk allele at the TRIB1 locus showed strong tendency toward increased plasma levels of GCA (p=0.02) and GUDCA (p=0.009).

CONCLUSIONS

Circulating bile acid levels are associated with histopathological and genetic determinants of the transition from simple hepatic steatosis into NASH. Further studies exploring the potential involvement of bile acid metabolism in the development and/or progression of distinct histopathological features of NASH are warranted.

Cardiovascular involvement after liver transplantation: role of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis

Patients submitted to liver transplantation (LT) are exposed to high risk of cardiovascular (CV) complications which are the main determinants of both short-term and long-term morbidity and mortality in LT. Non-alcoholic fatty liver disease (NAFLD) is a very frequent condition in general population and is associated with a high risk of cardiovascular disease (CVD) which represents the first cause of death of these patients. NAFLD is predicted to become the first indication to LT and nowadays is also frequently detected in patients submitted to LT for other indications. Thus, the risk of CVD in patients submitted to LT is forecasted to increase in the next years. In this review the extent of CV involvement in patients submitted to LT and the role of NAFLD, either recurring after transplantation or as de novo presentation, in increasing CV risk is analysed. The risk of developing metabolic alterations, including diabetes, hypertension, dyslipidemia and weight gain, all manifestations of metabolic syndrome, occurring in the first months after LT, is depicted. The different presentations of cardiac involvement, represented by early atherosclerosis, coronary artery disease, heart failure and arrhythmias in patients with NAFLD submitted to LT is described. In addition, the tools to detect cardiac alterations either before or after LT is reported providing the possibility for an early diagnosis of CVD and an early therapy able to reduce morbidity and mortality for these diseases. The need for long-term concerted multidisciplinary activity with dietary counseling and exercise combined with drug treatment of all manifestations of metabolic syndrome is emphasized.

Exome-wide scan identifies significant association of rs4788084 in IL27 promoter with increase in hepatic fat content among Indians

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a global epidemic that often progresses to liver cirrhosis and hepatocellular carcinoma. In contrast to most world populations where NAFLD is mostly prevalent among obese, NAFLD among Indians and generally among South and South-East Asians is unique and highly prevalent among individuals who are lean. Genetics of NAFLD in Indian populations is understudied. In this study, we have used an exome-wide approach to identify genetic determinants of hepatic fat content (HFC) in India.

METHODS

HFC was measured in 244 participants using Proton magnetic resonance spectroscopy (H1-MRS). Quantitative trait loci (QTL) mapping was done exome-wide, to identify SNPs associated with HFC. The effects of the interaction between adiposity and QTLs on HFC were studied using a regression model. Association of the significant loci with disease severity was studied in 146 NAFLD patients among 244 participants, who underwent liver biopsy.

RESULTS

Our study identified 4 significantly associated SNPs (rs738409 and rs2281135 (PNPLA3), rs3761472 (SAMM50), rs17513722 (FAM161A) and rs4788084), with HFC after adjusting for the effects of covariates (p-value < 0.0005). rs738409, rs2281135 (PNPLA3), and rs3761472 (SAMM50) were associated with hepatocyte ballooning, lobular and portal inflammation and non-alcoholic steatohepatitis (NASH) (p-value < 0.05). rs4788048 is an eQTL for IL27 and SULT1A2 genes, both of which are highly expressed in healthy livers and are likely to be involved in NAFLD pathogenesis.

CONCLUSIONS

Our study identified the novel association of rs4788084 with HFC, which regulates the expression of IL-27, an immune regulatory gene. We further showed that adiposity affected the HFC, irrespective of the genetic predisposition.

Identifying Shared Risk Genes between Nonalcoholic Fatty Liver Disease and Metabolic Traits by Cross-Trait Association Analysis

Nonalcoholic fatty liver disease (NAFLD) generally co-occurs with metabolic disorders, but it is unclear which genes have a pleiotripic effect on NAFLD and metabolic traits. We performed a large-scale cross-trait association analysis to identify the overlapping genes between NAFLD and nine metabolic traits. Among all the metabolic traits, we found that obesity and type II diabetes are associated with NAFLD. Then, a multitrait association analysis among NAFLD, obesity and type II diabetes was conducted to improve the overall statistical power. We identified 792 significant variants by a cross-trait meta-analysis involving 100 pleiotripic genes. Moreover, we detected another two common genes by a genome-wide gene test. The results from the pathway enrichment analysis show that the 102 shared risk genes are enriched in cancer, diabetes, insulin secretion, and other related pathways. This study can help us understand the molecular mechanisms underlying comorbid NAFLD and metabolic disorders.

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

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

Association between PNPLA3 rs738409 G variant and MRI cerebrovascular disease biomarkers

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) has been associated with greater cerebral white matter hyperintensity (WMH) volume and microbleeds. The adiponutrin (PNPLA3) rs738409 G variant, a robust NAFLD susceptibility variant, has been variably associated with carotid atherosclerosis. We hypothesized that this variant is associated with WMH volume, microbleeds, covert brain infarction (CBI), and small perivascular spaces.

METHODS

We performed a cross-sectional analysis of the Northern Manhattan Study-MRI Substudy. The associations between the rs738409 G variant allele and outcomes were assessed using linear regression for WMH volume, logistic regression for microbleeds and CBI, and Poisson regression for small perivascular spaces. Models were adjusted for age, sex, principal components, diabetes, and body mass index.

RESULTS

We included 1063 Northern Manhattan Study participants who had brain MRI and genotype data available (mean age 70 ± 9 years, 61% women). The G allele frequency was 24%. The prevalence of any microbleeds and CBI were 8% and 18%, respectively. The median WMH volume and small perivascular space count score were 7.7 mL and 6, respectively. GG homozygosity, but not heterozygosity, was associated with WMH volume (β = 0.27; 95% CI, 0.03, 0.51) compared to non-carriers. Having at least one G allele was associated with the presence of microbleeds (Odds ratio, 1.78; 95% CI, 1.02, 3.12); the association was attenuated in other models. No associations were observed for CBI and small perivascular spaces.

CONCLUSION

The PNPLA3 rs738409 G allele was associated with greater WMH volume, and inconsistent associations with microbleeds were seen.

Genetic and metabolic factors: the perfect combination to treat metabolic associated fatty liver disease

The prevalence of nonalcoholic or more recently re-defined metabolic associated fatty liver disease (MAFLD) is rapidly growing worldwide. It is characterized by hepatic fat accumulation exceeding 5% of liver weight not attributable to alcohol consumption. MAFLD refers to an umbrella of conditions ranging from simple steatosis to nonalcoholic steatohepatitis which may finally progress to cirrhosis and hepatocellular carcinoma. MAFLD is closely related to components of the metabolic syndrome and to environmental factors. In addition to the latter, genetic predisposition plays a key role in MAFLD pathogenesis and strictly contributes to its progressive forms. The candidate genes which have been related to MAFLD hereditability are mainly involved in lipids remodeling, lipid droplets assembly, lipoprotein packaging and secretion, de novo lipogenesis, and mitochondrial redox status. In the recent years, it has emerged the opportunity to translate the genetics into clinics by aggregating the genetic variants mostly associated with MAFLD in polygenic risk scores. These scores might be used in combination with metabolic factors to identify those patients at higher risk to develop more severe liver disease and to schedule an individual therapeutic approach.

Updates in non-alcoholic fatty liver disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in childhood. There is an increase in disease prevalence and diagnoses as it is difficult to diagnose the problem. There are currently no effective medications. Management of NAFLD is a challenge for primary care clinicians and subspecialists. This paper provides guidelines for disease screening, diagnosis, management, and algorithm for subspecialty referral.

MBOAT7 down-regulation by genetic and environmental factors predisposes to MAFLD

Metabolic associated fatty liver disease (MAFLD) encompasses a broad spectrum of hepatic disorders, which include steatosis, nonalcoholic steatohepatitis (NASH), fibrosis and cirrhosis, that is a critical risk factor for hepatocellular carcinoma (HCC) development. Its pathogenesis is intertwined with obesity and type 2 diabetes (T2D). However, the predisposition to develop MAFLD is severely influenced by environmental and inherited cues. The rs641738 variant close to MBOAT7 gene has been identified by a genome-wide association screening in heavy drinkers. Although this variant has been associated with the entire spectrum of MAFLD, these results have not been completely replicated and the debate is still opened. Thus, functional studies that unravel the biological mechanisms underlying the genetic association with fatty liver are required. This review aims to summarize the clinical and experimental findings regarding the rs641738 variation and MBOAT7 function, with the purpose to shed light to its role as novel player in MAFLD pathophysiology.

Nutrition and Genetics in NAFLD: The Perfect Binomium

Nonalcoholic fatty liver disease (NAFLD) represents a global healthcare burden since it is epidemiologically related to obesity, type 2 diabetes (T2D) and Metabolic Syndrome (MetS). It embraces a wide spectrum of hepatic injuries, which include simple steatosis, nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis and hepatocellular carcinoma (HCC). The susceptibility to develop NAFLD is highly variable and it is influenced by several cues including environmental (i.e., dietary habits and physical activity) and inherited (i.e., genetic/epigenetic) risk factors. Nonetheless, even intestinal microbiota and its by-products play a crucial role in NAFLD pathophysiology. The interaction of dietary exposure with the genome is referred to as 'nutritional genomics,' which encompasses both 'nutrigenetics' and 'nutriepigenomics.' It is focused on revealing the biological mechanisms that entail both the acute and persistent genome-nutrient interactions that influence health and it may represent a promising field of study to improve both clinical and health nutrition practices. Thus, the premise of this review is to discuss the relevance of personalized nutritional advices as a novel therapeutic approach in NAFLD tailored management.

β-Klotho gene variation is associated with liver damage in children with NAFLD

BACKGROUND & AIM

Non-alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease in adults and children. Along with obesity, diabetes and insulin resistance, genetic factors strongly impact on NAFLD development and progression. Dysregulated bile acid metabolism and the fibroblast growth factor 19 (FGF19) pathway play a pivotal role in NAFLD pathogenesis. However, the mechanism through which the FGF19 receptor system is associated with liver damage in NAFLD remains to be defined.

METHODS

We evaluated the impact of the rs17618244 G>A β-Klotho (KLB) variant on liver damage in 249 pediatric patients with biopsy-proven NAFLD and the association of this variant with the expression of hepatic and soluble KLB. In vitro models were established to investigate the role of the KLB mutant.

RESULTS

The KLB rs17618244 variant was associated with an increased risk of ballooning and lobular inflammation. KLB plasma levels were lower in carriers of the rs17618244 minor A allele and were associated with lobular inflammation, ballooning and fibrosis. In HepG2 and Huh7 hepatoma cell lines, exposure to free fatty acids caused a severe reduction of intracellular and secreted KLB. Finally, KLB downregulation obtained by the expression of a KLB mutant in HepG2 and Huh7 cells induced intracellular lipid accumulation and upregulation of p62, ACOX1, ACSL1, IL-1β and TNF-α gene expression.

CONCLUSION

In conclusion, we showed an association between the rs17618244 KLB variant, which leads to reduced KLB expression, and the severity of NAFLD in pediatric patients. We can speculate that the KLB protein may exert a protective role against lipotoxicity and inflammation in hepatocytes.

LAY SUMMARY

Genetic and environmental factors strongly impact on the pathogenesis and progression of non-alcoholic fatty liver disease (NAFLD). The FGF19/FGFR4/KLB pathway plays a pivotal role in the pathogenesis of NAFLD. The aim of the study was to investigate the impact of a genetic variant in the KLB gene on the severity of liver disease. Our data suggest that the KLB protein plays a protective role against lipotoxicity and inflammation in hepatocytes.

Mboat7 down-regulation by hyper-insulinemia induces fat accumulation in hepatocytes

Background

Naturally occurring variation in Membrane-bound O-acyltransferase domain-containing 7 (MBOAT7), encoding for an enzyme involved in phosphatidylinositol acyl-chain remodelling, has been associated with fatty liver and hepatic disorders. Here, we examined the relationship between hepatic Mboat7 down-regulation and fat accumulation.

Methods

Hepatic MBOAT7 expression was surveyed in 119 obese individuals and in experimental models. MBOAT7 was acutely silenced by antisense oligonucleotides in C57Bl/6 mice, and by CRISPR/Cas9 in HepG2 hepatocytes.

Findings

In obese individuals, hepatic MBOAT7 mRNA decreased from normal liver to steatohepatitis, independently of diabetes, inflammation and MBOAT7 genotype. Hepatic MBOAT7 levels were reduced in murine models of fatty liver, and by hyper-insulinemia. In wild-type mice, Mboat7 was down-regulated by refeeding and insulin, concomitantly with insulin signalling activation. Acute hepatic Mboat7 silencing promoted hepatic steatosis in vivo and enhanced expression of fatty acid transporter Fatp1. MBOAT7 deletion in hepatocytes reduced the incorporation of arachidonic acid into phosphatidylinositol, consistently with decreased enzymatic activity, determining the accumulation of saturated triglycerides, enhanced lipogenesis and FATP1 expression, while FATP1 deletion rescued the phenotype.

Interpretation

MBOAT7 down-regulation by hyper-insulinemia contributes to hepatic fat accumulation, impairing phosphatidylinositol remodelling and up-regulating FATP1.

Funding

LV was supported by MyFirst Grant AIRC n.16888, Ricerca Finalizzata Ministero della Salute RF-2016–02,364,358, Ricerca corrente Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico; LV and AG received funding from the European Union Programme Horizon 2020 (No. 777,377) for the project LITMUS-“Liver Investigation: Testing Marker Utility in Steatohepatitis”. MM was supported by Fondazione Italiana per lo Studio del Fegato (AISF) ‘Mario Coppo’ fellowship.

Adolescent exposure to environmental level of PCBs (Aroclor 1254) induces non-alcoholic fatty liver disease in male mice

Polychlorinated biphenyls (PCBs) are persistent organic pollutants found in various environmental media, and there is growing evidence that PCBs may contribute to the pathogenesis of non-alcoholic fatty liver disease (NAFLD). The purposes of this study were to investigate whether environmental level of Aroclor 1254 (a commercial mixture of PCBs) exposure to adolescent male mice could induce the development of NAFLD and the mechanisms involved. Twenty-one-day-old male C57BL/6 mice were exposed to Aroclor 1254 (0.5-500 μg/kg body weight) by oral gavage once every third day for 60 days. The results showed that exposure to Aroclor 1254 increased body weight and decreased the liver-somatic index in a dose-dependent manner. Aroclor 1254 administration increased lipid accumulation in the liver and induced the mRNA expression of genes associated with lipogenesis, including acetyl-CoA carboxylase 1 (Acc1), acetyl-CoA carboxylase 2 (Acc2) and fatty acid synthase (Fasn). Moreover, Aroclor 1254 decreased peroxisome proliferator-activated receptor alpha (PPARα) signaling and lipid oxidation. In addition, we found that Aroclor 1254 administration induced oxidative stress in mouse liver and elevated the protein level of cyclooxygenase 2 (COX-2), an inflammatory molecule, possibly via the endoplasmic reticulum (ER) stress inositol-requiring enzyme 1α-X-box-binding protein-1 (IRE1α-XBP1) pathway, but not the nuclear factor-κB (NF-κB) pathway. In summary, adolescent exposure to environmental level of PCBs stimulated oxidative stress, ER stress and the inflammatory response and caused NAFLD in male mice. This work provides new insight into the idea that adolescent exposure to environmental level of PCBs might induce the development of NAFLD under the regulation of ER stress in males.

Atorvastatin for prevention of disease progression and hospitalisation in liver cirrhosis: protocol for a randomised, double-blind, placebo-controlled trial

INTRODUCTION

Patients with liver cirrhosis are often diagnosed late and once complications are present, the 2-year survival is 50%. Increasing evidence supports systemic inflammation and metabolic dysfunction in the hepatic stellate cell as key drivers of progression of cirrhosis. However, there is no registered medication, that targets inflammation and cellular dysfunction in the liver.

METHODS AND ANALYSIS

In a randomised double-blind and placebo-controlled trial with atorvastatin for liver cirrhosis, we aim to investigate clinical endpoints of survival, hospitalisations and safety, but also exploratory endpoints of genomics and protein functions in the liver.

ETHICS AND DISSEMINATION

There is no registered medication that actively prevents development of complications or systemic inflammation in liver cirrhosis. All patients continue regular clinical management during the trial period. Atorvastatin has been on the market for several years with a safety profile that is acceptable even in patients with liver disease. A beneficial effect of atorvastatin on clinical outcomes in cirrhosis will provide cheap and effective causal treatment for chronic liver disease. The trial is registered by the Danish Data Protection Agency (P-2019-635) and approved by the Danish Medicines Agency (EudraCT 2019-001806-40) and the Scientific Ethics Committee of the Capital Region of Denmark (H-19030643) before initiation. Reporting of the trial will follow the Consolidated Standards of Reporting Trials guidelines for reporting of randomised clinical trials.

TRIAL REGISTRATION NUMBER

The trial is registered in clinicaltrials.gov (NCT04072601) and in clinicaltrialsregister.eu (EudraCT 2019-001806-40) (Pre-results).

Circulating tumor DNA/circulating tumor cells and the applicability in different causes induced hepatocellular carcinoma

In 2015, liquid biopsy was rated one of the top 10 breakthrough technologies of the year by MIT Technology Review. Liquid biopsy is a type of in vitro diagnostic method involving a noninvasive blood test. It is also a breakthrough technology used to detect tumors and cancers and assist in therapeutic strategies. The most widely used markers are circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA). Primary carcinoma of the liver is a malignancy of hepatocytes or intrahepatic biliary epithelial cells. The most common type of liver cancer is hepatocellular carcinoma (HCC), the causes of which mainly include infection with hepatitis B virus (HBV) and/or hepatitis C virus (HCV), alcohol abuse, aflatoxicosis, and nonalcoholic fatty liver disease/ nonalcoholic steatohepatitis. As there are few typical clinical characteristics during the early stage of the disease, early diagnosis of HCC is very challenging. However, CTCs and ctDNA carry tumor-specific information. Therefore, the detection and analysis of CTCs and ctDNA can provide evidence for the early diagnosis of HCC and guide treatment. Furthermore, several studies have indicated that different inducers of HCC cause different DNA mutations, and accordingly, detection of specific mutations in ctDNA will facilitate the determination of the HCC type and help physicians provide distinctive therapies.

Serum lipopolysaccharides predict advanced liver disease in the general population

Background & Aims

Gut-derived endotoxemia has been implicated in the development of chronic liver disease, but its relevance at the population level remains unclear. We analyzed whether endotoxemia is associated with incident advanced liver disease in the general population.

Methods

Serum lipopolysaccharide (LPS) was measured in 6,727 (3,455 male and 3,272 female, mean age 53.4 ± 10.9 years, mean body mass index 27.2 ± 4.5) individuals participating in the Finnish population-based health examination survey FINRISK 1997. Data were linked with electronic health registers for incident advanced liver disease (hospitalization, cancer or death related to liver disease). During a mean follow-up of 16.3 ± 3.8 years (109,282 person-years), 86 liver events occurred. Univariate and multivariate Cox regression, and Kaplan-Meier analyses were performed.

Results

Serum LPS predicted incident advanced liver disease with a hazard ratio per 1 SD of 1.41 (95% CI 1.24–1.59; p ≪0.001) when adjusted for age, sex, gamma-glutamyltransferase, metabolic syndrome, alcohol use, patatin-like phospholipase domain-containing protein 3 (PNPLA3) I148M, waist-hip ratio and type 2 diabetes. This association remained robustly significant in additional multivariate analyses with various levels of adjustment. The association was accentuated among carriers of the PNPLA3 risk variant. The population attributable fraction of the highest LPS tertile for liver events was 29.7%. However, LPS was not associated with all-cause mortality.

Conclusion

Serum LPS is associated with hospitalization, cancer or death related to liver disease in the general population, with the highest tertile potentially accounting for 30% of the risk of liver disease.

Lay summary

Lipopolysaccharide, a gut-derived bacterial endotoxin, has been implicated in the development of chronic liver disease, but its relevance at the population level remains unclear. We found that serum lipopolysaccharide levels were associated with incident advanced liver disease in the general population, with the highest tertile accounting for up to 30% of the risk of hospitalization, cancer or death related to liver disease.

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Serum LPS was associated with incident advanced liver disease in the general population.

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LPS was associated with liver-related risk of hospitalization, cancer or death.

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The highest LPS tertile may account for up to 30% of the risk of incident liver disease.

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The risk of liver disease was accentuated among carriers of the PNPLA3 I143M.

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Serum LPS was not associated with all-cause mortality.

Meta-analysis of the association between MBOAT7 rs641738, TM6SF2 rs58542926 and nonalcoholic fatty liver disease susceptibility

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a kind of liver disease caused by factors other than excessive alcohol use. It is the leading cause of liver injury in developed countries. The membrane-bound O-acyltransferase 7 (MBOAT7) and transmembrane 6 superfamily member 2 (TM6SF2) are associated with lipid metabolism. Studies found a mutation on MBOAT7, rs641738 and another on TM6SF2, rs58542926 were associated with liver diseases, including NAFLD. However, the results were inconclusive and inconsistent.

METHODS

In the present meta-analysis, the databases Pubmed, Embase, Chinese National Knowledge Infrastructure, and Chinse Biomedical Literature Database were searched for related studies. The deadline of publications was July 10th, 2018. The data from included studies were extracted by 2 independent investigators. STATA 12.0 software was used in the present meta-analysis.

RESULTS

A total of 9 papers with 20 studies, including 5415 cases and 17896 controls were identified for the meta-analysis. The results indicated lower risks of NAFLD for CC genotype of TM6SF2 rs58542926 in homozygous, heterozygous, dominant and recessive models (CC vs. TT: OR = 0.33; CC vs. CT: OR = 0.58; CC vs. CT + TT: OR = 0.64; CC + CT vs. TT: OR = 0.32). These decreased risks of NAFLD also existed in Asians in all genetic models except allelic model, and in Caucasians in the heterozygous model (CC vs. CT, OR = 0.52) and the dominant model (CC + CT vs. TT, OR = 0.50). No association existed between MBOAT7 rs641738 and NAFLD risks in all genetic models (CC vs. TT: OR = 0.91; CC vs. CT: OR = 0.96; CC vs. CT + TT: OR = 0.95; CC + CT vs. TT: OR = 0.91; C vs. T: OR = 0.99).

CONCLUSION

CC genotype of TM6SF2 rs58542926 was associated with a significantly lower risk of NAFLD, while MBOAT7 rs641738 was not related to NAFLD risks.

Rare Pathogenic Variants Predispose to Hepatocellular Carcinoma in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a rising cause of hepatocellular carcinoma (HCC). We examined whether inherited pathogenic variants in candidate genes (n = 181) were enriched in patients with NAFLD-HCC. To this end, we resequenced peripheral blood DNA of 142 NAFLD-HCC, 59 NAFLD with advanced fibrosis, and 50 controls, and considered 404 healthy individuals from 1000 G. Pathogenic variants were defined according to ClinVar, likely pathogenic as rare variants predicted to alter protein activity. In NAFLD-HCC patients, we detected an enrichment in pathogenic (p = 0.024), and likely pathogenic variants (p = 1.9*10-6), particularly in APOB (p = 0.047). APOB variants were associated with lower circulating triglycerides and higher HDL cholesterol (p < 0.01). A genetic risk score predicted NAFLD-HCC (OR 4.96, 3.29-7.55; p = 5.1*10-16), outperforming the diagnostic accuracy of common genetic risk variants, and of clinical risk factors (p < 0.05). In conclusion, rare pathogenic variants in genes involved in liver disease and cancer predisposition are associated with NAFLD-HCC development.

Relationship Between Nonalcoholic Fatty Liver Disease Susceptibility Genes and Coronary Artery Disease

Coronary artery disease (CAD) is the principal cause of death in patients with nonalcoholic fatty liver disease (NAFLD). The aim of the present study was to investigate whether NAFLD is causally involved in the pathogenesis of CAD. For this, previously reported NAFLD susceptibility genes were clustered and tested for an association with CAD in the Coronary Artery Disease Genome‐Wide Replication and Meta‐Analysis plus the Coronary Artery Disease Genetics (CARDIoGRAMplusC4D) Consortium data set. The role of plasma lipids as a potential mediator was explored by using data from the Global Lipids Genetics Consortium. Statistical analyses revealed that the combination of 12 NAFLD genes was not associated with CAD in 60,801 CAD cases and 123,504 controls (odds ratio [OR] per NAFLD risk allele, 1.0; 95% confidence interval [CI], 0.99‐1.00). In a subsequent sensitivity analysis, a positive relationship was observed after exclusion of gene variants that are implicated in NAFLD through impaired very low‐density lipoprotein secretion (i.e., microsomal triglyceride transfer protein [MTTP], patatin‐like phospholipase domain containing 3 [PNPLA3], phosphatidylethanolamine N‐methyltransferase [PEMT], and transmembrane 6 superfamily member 2 [TM6SF2]) (OR, 1.01; 95% CI, 1.00‐1.02). Clustering of the excluded genes showed a significant negative relationship with CAD (OR, 0.97; 95% CI, 0.96‐0.99). A substantial proportion of the observed heterogeneity between the individual NAFLD genes in relation to CAD could be explained by plasma lipids, as reflected by a strong relationship between plasma lipids and CAD risk conferred by the NAFLD susceptibility genes (r = 0.76; P = 0.004 for low‐density lipoprotein cholesterol). Conclusion: NAFLD susceptibility genes do not cause CAD per se. The relationship between these genes and CAD appears to depend to a large extent on plasma lipids. These observations strongly suggest taking plasma lipids into account when designing a new drug to target NAFLD.

Genetic polymorphisms associated with nonalcoholic fatty liver disease in Uyghur population: a case-control study and meta-analysis

Background

Polymorphisms have been identified to predispose to NAFLD. Here, we accessed the seven polymorphisms of rs1260326, rs780094 in GCKR, rs2954021 near TRIB1, rs2228603 in NCAN, rs58542926 in TM6SF2, rs12137855 near LYPLAL1, and rs10883437 near CPN1 on NAFLD susceptibility in the Uygur population.

Material and methods

We collected 620 samples (317 NAFLD and 303 controls) for this case-control study. Meta-analysis was performed using Stata Software.

Results

Our data detected that the rs1260326 (T vs. C: OR = 1.27, 95% CI = 1.01–1.59) and rs780094 (T vs. C: OR = 1.30, 95% CI = 1.04–1.63) were significantly associated with the susceptibility to NAFLD in Uygur population. The rs1260326 and rs780094 T/T genotype are significantly associated with soda, egg, and soybean intakes in the consumption group with twice or more in a week. Furthermore, a significant haplotype effect of rs1260326/T- rs780094/T was found (OR = 1.29, 95% CI: 1.03–1.62) compared with CC haplotype. An additional meta-analysis using 4352 cases and 10,168 controls established that rs780094 (OR = 1.21, 95%CI: 1.14–1.28) is significantly associated with NAFLD. Finally, among the 4 case-control studies on rs1260326, including 712 NAFLD and 658 controls, significant associations were found in Asian, liver biopsy, adult and pediatric groups.

Conclusion

Collectively, both our case-control study and meta-analysis confirm a significant association between rs780094 and NAFLD. Additionally, our results suggest Asian-specific, liver biopsy-specific, adult-specific and pediatric-specific associations between the rs1260326 and NAFLD. Moreover, the rs1260326 and rs780094 T/T genotype are significantly associated with food habits, such as soda, egg, and soybean.

Electronic supplementary material

The online version of this article (10.1186/s12944-018-0877-3) contains supplementary material, which is available to authorized users.

Genetic and metabolic predictors of hepatic fat content in a cohort of Italian children with obesity

OBJECTIVES

To comprehensively explore metabolic and genetic contributors to liver fat accumulation in overweight/obese children.

METHODS

Two hundred thirty Italian children with obesity were investigated for metabolic parameters and genotyped for PNPLA3, TM6SF2, GCKR, and MBOAT7 gene variants. Percentage hepatic fat content (HFF%) was measured by nuclear magnetic resonance.

RESULTS

HFF% was positively related with BMI, HOMA_IR, metabolic syndrome, ALT, AST, γGT, and albumin. Carriers of [G] allele in PNPLA3, [T] allele in GCKR and [T] allele in TM6SF2 genes had significantly higher hepatic fat content than wild-type carriers. HFF% was explained for 8.7% by metabolic and for 16.1% by genetic factors and, a model including age, gender, BMI, HOMA_IR, PNPLA3, GCKR, and TM6SF2 variants was the best predictor of HFF%, explaining 24.8% of its variation (P < 0.001). A weighted-genetic risk score combining PNPLA3, GCKR, and TM6SF2 risk alleles was associated with almost eightfold higher risk of NAFLD.

CONCLUSIONS

Our data highlighted the predominant role of genetic factors in determining the amount of liver fat content in children with obesity.

miRNA Signature in NAFLD: A Turning Point for a Non-Invasive Diagnosis

Nonalcoholic fatty liver disease (NAFLD) defines a wide pathological spectrum ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) which may predispose to liver cirrhosis and hepatocellular carcinoma. It represents the leading cause of hepatic damage worldwide. Diagnosis of NASH still requires liver biopsy but due to the high prevalence of NAFLD, this procedure, which is invasive, is not practicable for mass screening. Thus, it is crucial to non-invasively identify NAFLD patients at higher risk of progression to NASH and fibrosis. It has been demonstrated that hepatic fat content and progressive liver damage have a strong heritable component. Therefore, genetic variants associated with NAFLD have been proposed as non-invasive markers to be used in clinical practice. However, genetic variability is not completely explained by these common variants and it is possible that many of the phenotypic differences result from gene-environment interactions. Indeed, NAFLD development and progression is also modulated by epigenetic factors, in particular microRNAs (miRNAs), which control at post-transcriptional level many complementary target mRNAs and whose dysregulation has been shown to have high prognostic and predictive value in NAFLD. The premise of the current review is to discuss the role of miRNAs as pathogenic factors, risk predictors and therapeutic targets in NAFLD.

S100A4 Gene is Crucial for Methionine-Choline-Deficient Diet-Induced Non-Alcoholic Fatty Liver Disease in Mice

PURPOSE

To explore the influence of S100 calcium binding protein A4 (S100A4) knockout (KO) on methionine-choline-deficient (MCD) diet-induced non-alcoholic fatty liver disease (NAFLD) in mice.

MATERIALS AND METHODS

S100A4 KO mice (n=20) and their wild-type (WT) counterparts (n=20) were randomly divided into KO/MCD, Ko/methionine-choline-sufficient (MCS), WT/MCD, and WT/MCS groups. After 8 weeks of feeding, blood lipid and liver function-related indexes were measured. HE, Oil Red O, and Masson stainings were used to observe the changes of liver histopathology. Additionally, expressions of S100A4 and proinflammatory and profibrogenic cytokines were detected by qRT-PCR and Western blot, while hepatocyte apoptosis was revealed by TUNEL staining.

RESULTS

Serum levels of aminotransferase, aspartate aminotransferase, triglyceride, and total cholesterol in mice were increased after 8-week MCD feeding, and hepatocytes performed varying balloon-like changes with increased inflammatory cell infiltration and collagen fibers; however, these effects were improved in mice of KO/MCD group. Meanwhile, total NAFLD activity scores and fibrosis were lower compared to WT+MCD group. Compared to WT/MCS group, S100A4 expression in liver tissue of WT/MCD group was enhanced. The expression of proinflammatory (TNF-α, IL-1β, IL-6) and profibrogenic cytokines (TGF-β1, COL1A1, α-SMA) in MCD-induced NAFLD mice were increased, as well as apoptotic index (AI). For MCD group, the expressions of proinflammatory and profibrogenic cytokines and AI in KO mice were lower than those of WT mice.

CONCLUSION

S100A4 was detected to be upregulated in NAFLD, while S100A4 KO alleviated liver fibrosis and inflammation, in addition to inhibiting hepatocyte apoptosis.

Non-alcoholic fatty liver disease: a narrative review of genetics

Non-alcoholic fatty liver disease (NAFLD) is now the most common cause of chronic liver diseases worldwide. It encompasses a spectrum of disorders ranging from isolated hepatic steatosis to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. One of the key challenges in NAFLD is identifying which patients will progress. Epidemiological and genetic studies indicate a strong pattern of heritability that may explain some of the variability in NAFLD phenotype and risk of progression. To date, at least three common genetic variants in the PNPLA3, TM6SF2, and GCKR genes have been robustly linked to NAFLD in the population. The function of these genes revealed novel pathways implicated in both the development and progression of NAFLD. In addition, candidate genes previously implicated in NAFLD pathogenesis have also been identified as determinants or modulators of NAFLD phenotype including genes involved in hepatocellular lipid handling, insulin resistance, inflammation, and fibrogenesis. This article will review the current understanding of the genetics underpinning the development of hepatic steatosis and the progression of NASH. These newly acquired insights may transform our strategy to risk-stratify patients with NAFLD and to identify new potential therapeutic targets.

Multiple Membrane Transporters and Some Immune Regulatory Genes are Major Genetic Factors to Gout

Gout is a common form of inflammatory arthritis caused by hyperuricemia and the deposition of Monosodium Urate (MSU) crystals. It is also considered as a complex disorder in which multiple genetic factors have been identified in association with its susceptibility and/or clinical outcomes. Major genes that were associated with gout include URAT1, GLUT9, OAT4, NPT1 (SLC17A1), NPT4 (SLC17A3), NPT5 (SLC17A4), MCT9, ABCG2, ABCC4, KCNQ1, PDZK1, NIPAL1, IL1β, IL-8, IL-12B, IL-23R, TNFA, MCP-1/CCL2, NLRP3, PPARGC1B, TLR4, CD14, CARD8, P2X7R, EGF, A1CF, HNF4G and TRIM46, LRP2, GKRP, ADRB3, ADH1B, ALDH2, COMT, MAOA, PRKG2, WDR1, ALPK1, CARMIL (LRRC16A), RFX3, BCAS3, CNIH-2, FAM35A and MYL2-CUX2. The proteins encoded by these genes mainly function in urate transport, inflammation, innate immunity and metabolism. Understanding the functions of gout-associated genes will provide important insights into future studies to explore the pathogenesis of gout, as well as to develop targeted therapies for gout.

Fatty Liver and the Forensic Pathologist

Fatty liver is a common finding in clinical practice and at autopsy. It is most commonly seen associated with alcohol abuse and in non-alcoholic fatty liver disease (NAFLD). It may also be seen in many other conditions in both adults and children. It is now recognized that NAFLD, like alcoholic liver disease, may lead to end stage liver disease. Nonalcoholic fatty liver disease is associated with increased mortality from other disorders, particularly cardiovascular diseases. Fatty liver may be seen in many conditions that concern autopsy pathologists, including drug toxicity, anorexia, hepatic ischemia, and heatstroke. In infants, steatosis is common in sudden unexpected deaths. Fatty liver has been associated with sudden death and this review examines the pathology and role of fatty liver in sudden death. Acad Forensic Pathol. 2018 8(2): 296-310.

Causal relationship of hepatic fat with liver damage and insulin resistance in nonalcoholic fatty liver

BACKGROUND AND AIMS

Nonalcoholic fatty liver disease is epidemiologically associated with hepatic and metabolic disorders. The aim of this study was to examine whether hepatic fat accumulation has a causal role in determining liver damage and insulin resistance.

METHODS

We performed a Mendelian randomization analysis using risk alleles in PNPLA3, TM6SF2, GCKR and MBOAT7, and a polygenic risk score for hepatic fat, as instruments. We evaluated complementary cohorts of at-risk individuals and individuals from the general population: 1515 from the liver biopsy cohort (LBC), 3329 from the Swedish Obese Subjects Study (SOS) and 4570 from the population-based Dallas Heart Study (DHS).

RESULTS

Hepatic fat was epidemiologically associated with liver damage, insulin resistance, dyslipidemia and hypertension. The impact of genetic variants on liver damage was proportional to their effect on hepatic fat accumulation. Genetically determined hepatic fat was associated with aminotransferases, and with inflammation, ballooning and fibrosis in the LBC. Furthermore, in the LBC, the causal association between hepatic fat and fibrosis was independent of disease activity, suggesting that a causal effect of long-term liver fat accumulation on liver disease is independent of inflammation. Genetically determined hepatic steatosis was associated with insulin resistance in the LBC and SOS. However, this association was dependent on liver damage severity. Genetically determined hepatic steatosis was associated with liver fibrosis/cirrhosis and with a small increase in risk of type 2 diabetes in publicly available databases.

CONCLUSION

These data suggest that long-term hepatic fat accumulation plays a causal role in the development of chronic liver disease.