Genetic background in nonalcoholic fatty liver disease: A comprehensive review

Liver Fibrosis in Some Patients with Non-Alcoholic Fatty Liver Disease: from Diagnosis to Prognosis

The purpose of this publication was to update knowledge about non-alcoholic fatty liver disease (NAFLD) and fibrogenesis, as well as factors that have a positive or negative prognostic value in relation to the formation and progression of liver fibrosis. This review article contains the current literature dates about pathogenetic factors of the development of liver fibrosis in NAFLD and conceptual ideas about its diagnosis at this moment. Obviously, along with genetic and epigenetic factors, hyper- and disproduction of organokines affect to the progression of the disease. Evaluation of the quantitative and qualitative composition of the microbiota, the integrity of the epithelial intestinal barrier are perceptual fields for research this problem. Non-invasive proprietary and non-proprietary scales for assessing the risk of steatosis and fibrosis, transient elastometry are suitable for routine assessment of individual risk of disease development and progression. This scientific review demonstrates proofs of necessity to develop individual strategies for the management of patients with NAFLD in relation to its metabolic activity and the stage of liver fibrosis.

Team players in the pathogenesis of metabolic dysfunctions-associated steatotic liver disease: The basis of development of pharmacotherapy

Nutrient metabolism is regulated by several factors. Social determinants of health with or without genetics are the primary regulator of metabolism, and an unhealthy lifestyle affects all modulators and mediators, leading to the adaptation and finally to the exhaustion of cellular functions. Hepatic steatosis is defined by presence of fat in more than 5% of hepatocytes. In hepatocytes, fat is stored as triglycerides in lipid droplet. Hepatic steatosis results from a combination of multiple intracellular processes. In a healthy individual nutrient metabolism is regulated at several steps. It ranges from the selection of nutrients in a grocery store to the last step of consumption of ATP as an energy or as a building block of a cell as structural component. Several hormones, peptides, and genes have been described that participate in nutrient metabolism. Several enzymes participate in each nutrient metabolism as described above from ingestion to generation of ATP. As of now several publications have revealed very intricate regulation of nutrient metabolism, where most of the regulatory factors are tied to each other bidirectionally, making it difficult to comprehend chronological sequence of events. Insulin hormone is the primary regulator of all nutrients' metabolism both in prandial and fasting states. Insulin exerts its effects directly and indirectly on enzymes involved in the three main cellular function processes; metabolic, inflammation and repair, and cell growth and regeneration. Final regulators that control the enzymatic functions through stimulation or suppression of a cell are nuclear receptors in especially farnesoid X receptor and peroxisome proliferator-activated receptor/RXR ligands, adiponectin, leptin, and adiponutrin. Insulin hormone has direct effect on these final modulators. Whereas blood glucose level, serum lipids, incretin hormones, bile acids in conjunction with microbiota are intermediary modulators which are controlled by lifestyle. The purpose of this review is to overview the key players in the pathogenesis of metabolic dysfunction-associated steatotic liver disease (MASLD) that help us understand the disease natural course, risk stratification, role of lifestyle and pharmacotherapy in each individual patient with MASLD to achieve personalized care and target the practice of precision medicine. PubMed and Google Scholar databases were used to identify publication related to metabolism of carbohydrate and fat in states of health and disease states; MASLD, cardiovascular disease and cancer. More than 1000 publications including original research and review papers were reviewed.

Impact and usefulness of the transition to the new MAFLD classification for non-B, non-C HCC: a retrospective cohort study

BACKGROUND

Metabolic dysfunction-associated fatty liver disease (MAFLD) represents a new classification system for fatty liver disease. In this study, we investigated the clinical characteristics of patients with MAFLD-hepatocellular carcinoma (HCC) in comparison with those with nonalcoholic fatty liver disease (NAFLD) and considered the validity and challenges of the new criteria.

METHODS

This study included 237 untreated non-B, non-C HCC patients with hepatic steatosis. We examined the profile and laboratory findings of patients with MAFLD-HCC and NAFLD-HCC. We also classified MAFLD-HCC patients according to the factors on which the diagnosis was based and compared their clinical characteristics.

RESULTS

A total of 222 (94%) and 101 (43%) patients were diagnosed with MAFLD and NAFLD, respectively. MAFLD-HCC patients were more likely to be male than NAFLD-HCC, but there were no significant differences in metabolic indices, noninvasive liver fibrosis score or HCC status. In a study of MAFLD-HCC patients by diagnostic factor, those with overweight only were younger and had advanced liver fibrosis histologically, and when limited to patients younger than 70 years, the majority were overweight. Redefinition of overweight as BMI ≥ 25 reduced the number of MAFLD-HCC patients by only 5, from 222 to 217.

CONCLUSIONS

MAFLD accounted for the majority of non-B, non-C HCC cases with hepatic steatosis. Examination of additional cases and revision of the detailed criteria is needed so that it can be used to efficiently select patients with fatty liver who are at high risk of developing HCC.

Polymorphisms of the GCLC Gene Are Novel Genetic Markers for Susceptibility to Psoriasis Associated with Alcohol Abuse and Cigarette Smoking

The aim of this pilot study was to investigate whether single nucleotide polymorphisms (SNP) in the gene encoding the catalytic subunit of glutamate cysteine ligase (GCLC) are associated with the risk and clinical features of psoriasis. A total of 944 unrelated individuals, including 474 patients with a diagnosis of psoriasis and 470 healthy controls, were recruited for the study. Six common SNPs in the GCLC gene were genotyped using the MassArray-4 system. Polymorphisms rs648595 (OR = 0.56, 95% CI 0.35-0.90; P_perm = 0.017) and rs2397147 (OR = 0.54, 95% CI 0.30-0.98; P_perm = 0.05) were associated with susceptibility to psoriasis in males. In the male group, diplotype rs2397147-C/C × rs17883901-G/G was associated with a decreased risk of psoriasis (FDR-adjusted p = 0.014), whereas diplotype rs6933870-G/G × rs17883901-G/G (FDR-adjusted p = 0.045) showed an association with an increased disease risk in females. The joint effects of SNPs with tobacco smoking (rs648595 and rs17883901) and alcohol abuse (rs648595 and rs542914) on psoriasis risk were observed (P_perm ≤ 0.05). We also found multiple sex-independent associations between GCLC gene polymorphisms and various clinical features such as earlier disease onset, the psoriatic triad, and specific localizations of skin lesions. The present study is the first to show that polymorphisms of the GCLC gene are significantly associated with the risk of psoriasis and related to its clinical features.

Development of a prediction protocol for the screening of metabolic associated fatty liver disease in children with overweight or obesity

BACKGROUND

The early detection and management of children with metabolic associated fatty liver disease (MAFLD) is challenging.

OBJECTIVE

To develop a non-invasive and accurate prediction protocol for the identification of MAFLD among children with overweight/obesity candidates to confirmatory diagnosis.

METHODS

A total of 115 children aged 8-12 years with overweight/obesity, recruited at a primary care, were enrolled in this cross-sectional study. The external validation was performed using a cohort of children with overweight/obesity (N = 46) aged 8.5-14.0 years. MAFLD (≥5.5% hepatic fat) was diagnosed by magnetic resonance imaging (MRI). Fasting blood biochemical parameters were measured, and 25 candidates' single nucleotide polymorphisms (SNPs) were determined. Variables potentially associated with the presence of MAFLD were included in a multivariate logistic regression.

RESULTS

Children with MAFLD (36%) showed higher plasma triglycerides (TG), insulin, homeostasis model assessment of insulin resistance (HOMA-IR), alanine aminotransferase (ALT), aspartate transaminase (AST), glutamyl-transferase (GGT) and ferritin (p < 0.05). The distribution of the risk-alleles of PPARGrs13081389, PPARGrs1801282, HFErs1800562 and PNLPLA3rs4823173 was significantly different between children with and without MAFLD (p < 0.05). Three biochemical- and/or SNPs-based predictive models were developed, showing strong discriminatory capacity (AUC-ROC: 0.708-0.888) but limited diagnostic performance (sensitivity 67%-82% and specificity 63%-69%). A prediction protocol with elevated sensitivity (72%) and specificity (84%) based on two consecutive steps was developed. The external validation showed similar results: sensitivity of 70% and specificity of 85%.

CONCLUSIONS

The HEPAKID prediction protocol is an accurate, easy to implant, minimally invasive and low economic cost tool useful for the early identification and management of paediatric MAFLD in primary care.

A randomized, placebo-controlled clinical trial of hydrogen/oxygen inhalation for non-alcoholic fatty liver disease

Non‐alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide with increasing incidence consistent with obesity, type 2 diabetes and cardiovascular diseases. No approved medication was currently available for NAFLD treatment. Molecular hydrogen (H₂), an anti‐oxidative, anti‐inflammatory biomedical agent is proved to exhibit therapeutic and preventive effect in various diseases. The purpose of this study was to investigate the effect of hydrogen/oxygen inhalation on NAFLD subjects and explore the mechanism from the perspective of hepatocyte autophagy. We conducted a randomized, placebo‐controlled clinical trial of 13‐week hydrogen/oxygen inhalation (China Clinical Trial Registry [#ChiCTR‐IIR‐16009114]) including 43 subjects. We found that inhalation of hydrogen/oxygen improved serum lipid and liver enzymes. Significantly improved liver fat content detected by ultrasound and CT scans after hydrogen/oxygen inhalation was observed in moderate–severe cases. We also performed an animal experiment based on methionine and choline‐deficient (MCD) diet‐induced mice model to investigate effect of hydrogen on mouse NASH. Hydrogen/oxygen inhalation improved systemic inflammation and liver histology. Promoted autophagy was observed in mice inhaled hydrogen/oxygen and treatment with chloroquine blocked the beneficial effect of hydrogen. Moreover, molecular hydrogen inhibited lipid accumulation in AML‐12 cells. Autophagy induced by palmitic acid (PA) incubation was further promoted by 20% hydrogen incubation. Addition of 3‐methyladenine (3‐MA) partially blocked the inhibitory effect of hydrogen on intracellular lipid accumulation. Collectively, hydrogen/oxygen inhalation alleviated NAFLD in moderate–severe patients. This protective effect of hydrogen was possibly by activating hepatic autophagy.

Potential Blood DNA Methylation Biomarker Genes for Diagnosis of Liver Fibrosis in Patients With Biopsy-Proven Non-alcoholic Fatty Liver Disease

Background and objective

This pilot study aimed to identify potential blood DNA methylation (BDM) biomarker genes for the diagnosis of liver fibrosis in non-alcoholic fatty liver disease (NAFLD).

Methods

We included a total of 16 NAFLD patients with significant (SLF, liver fibrosis stage ≥ 2) and 16 patients with non-significant liver fibrosis (NSLF, fibrosis stages 0–1). The association between BDM and liver fibrosis was analyzed. Genes were selected based on a stepwise-filtering with CpG islands containing significant differentially methylated probes.

Results

The two groups of patients were distinguishable through both t-distributed stochastic neighbor embedding (t-SNE) analysis and unsupervised hierarchical clustering analysis based on their BDM status. BDM levels were significantly higher in the NSLF group than in the SLF group. The methylation levels in the island and shelf regions were also significantly higher in the NSLF group, as well as the methylation levels in the first exon, 3′-untranslated region, body, ExonBnd, non-intergenic region, transcription start site (TSS)1500, and TSS200 regions (all p &lt; 0.05). BDM status was associated with greater histological liver fibrosis, but not with age, sex, or other histological features of NAFLD (p &lt; 0.05). The methylation levels of the hypomethylated CpG island region of CISTR, IFT140, and RGS14 genes were increased in the NSLF group compared to the SLF group (all p &lt; 0.05).

Conclusion

BDM may stratify NAFLD patients with significant and non-significant liver fibrosis. The CISTR, IFT140, and RGS14 genes are potential novel candidate BDM biomarkers for liver fibrosis and these pilot data suggest further work on BDM biomarkers is warranted.

Role of age, gender and ethnicity in the association between visceral adiposity index and non-alcoholic fatty liver disease among US adults (NHANES 2003-2018): cross-sectional study

OBJECTIVES

The association between visceral adiposity index (VAI) and the prevalence of non-alcoholic fatty liver disease (NAFLD) has not been fully determined. Here, we aimed to explore the association between VAI and NAFLD in the general US population, and further investigate whether the association involves population differences.

DESIGN

Cross-sectional population-based study.

SETTING

The National Health and Nutrition Examination Survey (2003-2018).

PARTICIPANTS

A total of 7522 participants aged 20 years or older who have complete information for NAFLD assessment test were included in this study.

PRIMARY AND SECONDARY OUTCOME MEASURES

NAFLD was assessed by the modified fatty liver index for the US population (USFLI) using a cut-off point of 30. Correlation between VAI and NAFLD prediction scores was calculated using the partial correlation analysis. Logistic regression models were further used to estimate ORs and 95% CIs.

RESULTS

Insulin resistance (IR), inflammation and waist circumference-adjusted partial correlation analysis indicated that VAI scores were positively correlated with USFLI (r=0.404 for men, and r=0.395 for women; p<0.001). In a comparison of the highest versus the lowest quartiles of VAI, multivariable logistic regression analysis demonstrated a positive association between VAI and NAFLD (OR (95% CI)=1.97 (1.12 to 3.47) for men, OR (95% CI)=4.03 (1.98 to 8.20) for women). The stratified analyses revealed that the positive association involves age/gender-specific and ethnic differences. As for the impact of metabolic disorders, our results revealed that the association was independent of IR and diabetes, but it would be confounded by other metabolic disorders. However, no significant association was found between VAI and hepatic fibrosis.

CONCLUSION

VAI is positively associated with the prevalence of NAFLD, but not hepatic fibrosis among US adults, and the association involves age/gender-specific and ethnic differences. The results reported here have important public health implications in NAFLD screening in the future.

Association of UCP3 Polymorphisms with Nonalcoholic Steatohepatitis and Metabolic Syndrome in Nonalcoholic Fatty Liver Disease Brazilian Patients

Background: We investigated the possible association of uncoupling protein 3 gene (UCP3) single nucleotide polymorphisms (SNPs) with nonalcoholic steatohepatitis (NASH) and metabolic syndrome (MetS) in nonalcoholic fatty liver disease (NAFLD) Brazilian patients. Methods: UCP3 SNPs rs1726745, rs3781907, and rs11235972 were genotyped in 158 biopsy-proven NAFLD Brazilian patients. Statistics was performed with JMP, R, and SHEsis softwares. Results: The TT genotype of rs1726745 was associated with less occurrence of MetS (P = 0.006) and with lower body mass index (BMI) in the entire NAFLD sample (P = 0.01) and in the NASH group (P = 0.02). The rs1726745-T was associated with lower values of AST (P = 0.001), ALT (P = 0.0002), triglycerides (P = 0.01), and total cholesterol (P = 0.02) in the entire NAFLD sample. Between groups, there were lower values of aminotransferases strictly in individuals with NASH (AST, P = 0.002; ALT, P = 0.0007) and with MetS (AST, P = 0.002; ALT, P = 0.001). The rs3781907-G was associated with lower GGT elevation values in the entire NAFLD sample (P = 0.002), in the NASH group (P = 0.004), and with MetS group (P = 0.003) and with protection for advanced fibrosis (P = 0.01). The rs11235972-A was associated with lower GGT values in the entire NAFLD sample (P = 0.006) and in the NASH group (P = 0.01) and with MetS group (P = 0.005), with fibrosis absence (P = 0.01) and protection for advanced fibrosis (P = 0.01). The TAA haplotype was protective for NASH (P = 0.002), and TGG haplotype was protective for MetS (P = 0.01). Conclusion: UCP3 gene variants were associated with protection against NASH and MetS, in addition to lower values of liver enzymes, lipid profile, BMI and, lesser fibrosis severity in the studied population.

Causal Relationship Between Complement C3, C4, and Nonalcoholic Fatty Liver Disease: Bidirectional Mendelian Randomization Analysis

The complement system is activated during the development of nonalcoholic fatty liver disease (NAFLD). We aimed to evaluate the causal relationship between serum C3 and C4 levels and NAFLD. After exclusion criteria, a total of 1600 Chinese Han men from the Fangchenggang Area Male Health and Examination Survey cohort were enrolled in cross-sectional analysis, while 572 participants were included in the longitudinal analysis (average follow-up of 4 years). We performed a bidirectional Mendelian randomization (MR) analysis using two C3-related, eight C4-related and three NAFLD-related gene loci as instrumental variables to evaluate the causal associations between C3, C4, and NAFLD risk in cross-sectional analysis. Per SD increase in C3 levels was significantly associated with higher risk of NAFLD (OR = 1.65, 95% CI 1.40, 1.94) in cross-sectional analysis while C4 was not (OR = 1.04, 95% CI 0.89, 1.21). Longitudinal analysis produced similar results (HR_C3 = 1.20, 95% CI 1.02, 1.42; HR_C4 = 1.10, 95% CI 0.94, 1.28). In MR analysis, there were no causal relationships for genetically determined C3 levels and NAFLD risk using unweighted or weighted GRS_C3 (β_{E_unweighted} = -0.019, 95% CI -0.019, -0.019, p = 0.202; β_{E_weighted} = -0.019, 95% CI -0.019, -0.019, p = 0.322). Conversely, serum C3 levels were significantly effected by the genetically determined NAFLD (β_{E_unweighted} = 0.020, 95% CI 0.020, 0.020, p = 0.004; β_{E_weighted} = 0.021, 95% CI 0.020, 0.021, p = 0.004). Neither the direction from C4 to NAFLD nor the one from NAFLD to C4 showed significant association. Our results support that the change in serum C3 levels but not C4 levels might be caused by NAFLD in Chinese Han men.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43657-021-00023-0.

The Specific NLRP3 Antagonist IFM-514 Decreases Fibrosis and Inflammation in Experimental Murine Non-Alcoholic Steatohepatitis

Background and Aims: Activation of the inflammasome NLRP3 (NOD-, LRR- and pyrin domain containing 3) contributes to the development of non-alcoholic fatty liver disease (NAFLD) and progression to non-alcoholic steatohepatitis (NASH). Therefore, this study explored the therapeutic effects of a novel and selective NLRP3 antagonist in a murine dietary model of NASH.

Methods: Groups of 12-week-old ApoE^-/- mice were fed ad lib for 7 weeks with a methionine/choline deficient (MCD) and western diet (WD). After 3 weeks of diet-induced injury, mice were injected i. p. with the NLRP3 antagonist IFM-514 (100 mg/kg body weight) or vehicle (0.5% carmellose) every day, 5 days/week for a further 4 weeks. Several markers of inflammation, fibrosis and steatosis were evaluated. Whole transcriptome sequencing and panel RNA expression analysis (NanoString) were performed.

Results: IFM-514 inhibited IL-1β production in mice challenged with 20 mg/kg lipopolysaccharide, and in mouse and human inflammatory cells in vitro. IFM-514 inhibited hepatic inflammation in the in vivo non-alcoholic steatohepatitis model assessed by H&E staining and in the hepatic gene expression of inflammasome-related proinflammatory cytokines. This effect was associated with significant reduction in caspase-1 activation. Similarly, IFM-514 was efficacious in vivo in MDC-fed ApoE^-/- mice, markedly reducing portal pressure, Sirius red staining and 4-hydroxyproline content compared to vehicle-treated mice. Moreover, IFM-514 significantly reduced hepatic steatosis in MCD-fed ApoE^-/- mice, as evidenced by NAFLD scores, oil red O staining, hepatic triglycerides and gene expression. In WD treated animals, similar trends in inflammation and fibrosis were observed, although not sufficient IFM-514 levels were reached.

Conclusion: Overall, IFM-514 reduced liver inflammation and fibrosis, with mild effects on liver steatosis in experimental murine NASH. Blocking of NLRP3 may be an attractive therapeutic approach for NASH patients.

Genome-wide analysis of blood lipid metabolites in over 5000 South Asians reveals biological insights at cardiometabolic disease loci

BACKGROUND

Genetic, lifestyle, and environmental factors can lead to perturbations in circulating lipid levels and increase the risk of cardiovascular and metabolic diseases. However, how changes in individual lipid species contribute to disease risk is often unclear. Moreover, little is known about the role of lipids on cardiovascular disease in Pakistan, a population historically underrepresented in cardiovascular studies.

METHODS

We characterised the genetic architecture of the human blood lipidome in 5662 hospital controls from the Pakistan Risk of Myocardial Infarction Study (PROMIS) and 13,814 healthy British blood donors from the INTERVAL study. We applied a candidate causal gene prioritisation tool to link the genetic variants associated with each lipid to the most likely causal genes, and Gaussian Graphical Modelling network analysis to identify and illustrate relationships between lipids and genetic loci.

RESULTS

We identified 253 genetic associations with 181 lipids measured using direct infusion high-resolution mass spectrometry in PROMIS, and 502 genetic associations with 244 lipids in INTERVAL. Our analyses revealed new biological insights at genetic loci associated with cardiometabolic diseases, including novel lipid associations at the LPL, MBOAT7, LIPC, APOE-C1-C2-C4, SGPP1, and SPTLC3 loci.

CONCLUSIONS

Our findings, generated using a distinctive lipidomics platform in an understudied South Asian population, strengthen and expand the knowledge base of the genetic determinants of lipids and their association with cardiometabolic disease-related loci.

Nutrigenomics and Nutrigenetics in Metabolic- (Dysfunction) Associated Fatty Liver Disease: Novel Insights and Future Perspectives

Metabolic- (dysfunction) associated fatty liver disease (MAFLD) represents the predominant hepatopathy and one of the most important systemic, metabolic-related disorders all over the world associated with severe medical and socio-economic repercussions due to its growing prevalence, clinical course (steatohepatitis and/or hepatocellular-carcinoma), and related extra-hepatic comorbidities. To date, no specific medications for the treatment of this condition exist, and the most valid recommendation for patients remains lifestyle change. MAFLD has been associated with metabolic syndrome; its development and progression are widely influenced by the interplay between genetic, environmental, and nutritional factors. Nutrigenetics and nutrigenomics findings suggest nutrition’s capability, by acting on the individual genetic background and modifying the specific epigenetic expression as well, to influence patients’ clinical outcome. Besides, immunity response is emerging as pivotal in this multifactorial scenario, suggesting the interaction between diet, genetics, and immunity as another tangled network that needs to be explored. The present review describes the genetic background contribution to MAFLD onset and worsening, its possibility to be influenced by nutritional habits, and the interplay between nutrients and immunity as one of the most promising research fields of the future in this context.

Role of non-alcoholic fatty liver disease in the evolution of renal function in patients with diabetes mellitus

BACKGROUND

Increasing prevalence in type 2 diabetes mellitus (T2DM) have influenced in an increasing prevalence of chronic kidney disease (CKD). Little is known about the influence of non-alcoholic fatty liver disease (NAFLD) on progression of CKD. The aim of this study was to analyse the role of NAFLD and its severity in the progression of renal function in patients with T2DM.

METHODS

Retrospective and observational study, including patients with T2DM and estimated glomerular filtration rate (eGFR) >30 ml/min/1,73m2. NAFLD was defined with presence of compatible ultrasonography and/or presence of fibrosis using NAFLD score. Patients were classified in three groups according to the NAFLD score; group 1 <-1.85, group 2 -1.85 to 0.18, and group 3 > 0.18.

RESULTS

A total of 102 patients were included (67.6% males, median age 59 [53-64] years), with median time of T2DM evolution was 70 [39-131] months. Group 3 had lower eGFR (84.8  ±  40.4 vs 71.4  ±  30.6 ml/min/1.73m2; p = 0.03) and higher proteinuria at baseline (0.56  ±  0.77 vs 1.59  ±  2.70 g/24h; p = 0.05). After a follow-up time of 75.8  ±  23.9 months, group 3 had a significant decrease in eGFR (66.6  ±  33.3 vs 36.8  ±  23.1 ml/min/1.73m2; p = <0.01), and higher risk of CKD progression (OR 7.50; CI 95% 2.76-20.35; p = <0.001) defined as decrease in > 50% eGFR.

CONCLUSIONS

The presence of NAFLD with high-risk fibrosis confers higher risk of CKD progression in patients with T2DM. Therefore, NAFLD should be a risk factor evaluated in these patients to optimise treatment.

Non-alcoholic fatty liver and chronic kidney disease: Retrospect, introspect, and prospect

With the growing prevalence of obesity and diabetes in the United States and across the world, a rise in the overall incidence and prevalence of non-alcoholic fatty liver disease (NAFLD) is expected. The risk factors for NAFLD are also associated with the development of chronic kidney disease (CKD). We review the epidemiology, risk factors, genetics, implications of gut dysbiosis, and specific pathogenic mechanisms linking NAFLD to CKD. Mechanisms such as ectopic lipid accumulation, cellular signaling abnormalities, and the interplay between fructose consumption and uric acid accumulation have led to the emergence of potential therapeutic implications for this patient population. Transplant evaluation in the setting of both NAFLD and CKD is also reviewed. Potential strategies for surveillance and management include the monitoring of comorbidities, the use of non-invasive fibrosis scoring systems, and the measurement of laboratory markers. Lastly, we discuss the management of patients with NAFLD and CKD, from preventative measures to experimental interventions.

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.

High-normal thyroid function predicts incident non-alcoholic fatty liver disease among middle-aged and elderly euthyroid subjects

BACKGROUND

Thyroid hormones (THs) influence hepatic lipid homeostasis through multiple pathways, suggesting that THs may predict the risk of non-alcoholic fatty liver disease (NAFLD). However, prospective studies on the association between THs levels and incident NAFLD in euthyroid subjects are limited. This prospective cohort study aimed to explore whether THs were associated with the development of NAFLD in middle-aged and elderly euthyroid subjects.

METHODS

A total of 6,462 subjects without baseline NAFLD were included in the cohort study (~6-year follow-up period, median: 4.2 years). Chemiluminescence immunoassay was used to measure serum free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH), and NAFLD was diagnosed by abdominal ultrasonography. Multivariable Cox proportional hazards regression models were used to assess the association between baseline THs, TSH, and the risk of NAFLD.

RESULTS

During the follow-up period, 1,675 subjects developed NAFLD. The incidence rate of NAFLD was 85.0 per 1000 person-years. Compared with the lowest FT3, FT4, and TSH quartiles, the multivariable-adjusted hazard ratios (95% confidence interval) of incident NAFLD for highest quartiles were 1.30 (1.12, 1.51), 1.07 (0.93, 1.23), 0.82 (0.71, 0.95) (P <0.001, =0.56, =0.01, respectively), respectively.

CONCLUSIONS

In middle-aged and elderly euthyroid subjects, high-normal FT3 and low-normal TSH are independently associated with a higher incidence of NAFLD.

Association of xenobiotic-metabolizing enzymes (GSTM1 and GSTT 1), and pro-inflammatory cytokines (TNF-α and IL-6) genetic polymorphisms with non-alcoholic fatty liver disease

Previous studies have revealed that genetic polymorphisms of the Glutathione S-transferase M1 and T1 (GSTM1 and GSTT1), tumor necrosis factor-α (TNF-α), and interleukin 6 (IL-6) are associated with the presence of non-alcoholic fatty liver disease (NAFLD) in many populations. This study was conducted to investigate the association of the GSTM1, GSTT1, TNF-α rs1800629, and IL-6 rs1800795 with NAFLD in the general Iranian population. A case-control analysis included 242 NAFLD patients and 324 healthy controls from Iranian adults. After the physical examination, the genotypes were determined by polymerase chain reaction(PCR). The GSTM1 null, GSTT1 null, TNF-α AG/AA, and IL-6 CG/CC genotypes were deemed to be high-risk. The null allele of GSTM1 and A allele of TNF-α were more frequent in NAFLD patients even after Bonferroni's correction (P values<0.005, adjusted odds ratio (OR), 1.66 and 2.02; 95% confidence intervals (CI), (1.18-2.32) and (1.34-3.34), respectively. The IL-6 CC/CG genotype association with NAFLD was not significant after correction (P value = 0.04) Polymorphisms of xenobiotic and pro-inflammatory genes are associated with NAFLD in the Iranian population and seem to be a useful tool for NAFLD prevention and care.

In vitro analysis of hepatic stellate cell activation influenced by transmembrane 6 superfamily 2 polymorphism

Non‑alcoholic steatohepatitis (NASH) may progress via liver fibrosis along with hepatic stellate cell (HSC) activation. A single nucleotide polymorphism (SNP; rs58542926) located in transmembrane 6 superfamily 2 (TM6SF2) has been reported to be significantly associated with fibrosis in patients with NASH, but the precise mechanism is still unknown. The present study aimed to explore the role of TM6SF2 in HSC activation in vitro. Plasmids producing TM6SF2 wild-type (WT) and mutant type (MT) containing E167K amino acid substitution were constructed, and the activation of LX‑2 cells was analyzed by overexpressing or knocking down TM6SF2 under transforming growth factor β1 (TGFβ) treatment. Intracellular α‑smooth muscle actin (αSMA) expression in LX‑2 cells was significantly repressed by TM6SF2‑WT overexpression and increased by TM6SF2 knockdown. Following treatment with TGFβ, αSMA expression was restored in TM6SF2‑WT overexpressed LX‑2 cells and was enhanced in TM6SF2 knocked‑down LX‑2 cells. Comparing αSMA expression under TM6SF2‑WT or ‑MT overexpression, expression of αSMA in TM6SF2‑MT overexpressed cells was higher than that in TM6SF2‑WT cells and was further enhanced by TGFβ treatment. The present study demonstrated that intracellular αSMA expression in HCS was negatively regulated by TM6SF2 while the E167K substitution released this negative regulation and led to enhanced HSC activation by TGFβ. These results suggest that the SNP in TM6SF2 may relate to sensitivity of HSC activation.

Triose Kinase Controls the Lipogenic Potential of Fructose and Dietary Tolerance

The surge in fructose consumption is a major factor behind the rapid rise of nonalcoholic fatty liver disease in modern society. Through flux and genetic analyses, we demonstrate that fructose is catabolized at a much higher rate than glucose, and triose kinase (TK) couples fructolysis with lipogenesis metabolically and transcriptionally. In the absence of TK, fructose oxidation is accelerated through the activation of aldehyde dehydrogenase (ALDH) and serine biosynthesis, accompanied by increased oxidative stress and fructose aversion. TK is also required by the endogenous fructolysis pathway to drive lipogenesis and hepatic triglyceride accumulation under high-fat diet and leptin-deficient conditions. Intriguingly, a nonsynonymous TK allele (rs2260655_A) segregated during human migration out of Africa behaves as TK null for its inability to rescue fructose toxicity and increase hepatic triglyceride accumulation. Therefore, we posit TK as a metabolic switch controlling the lipogenic potential of fructose and its dietary tolerance.

Immunity-related GTPase induces lipophagy to prevent excess hepatic lipid accumulation

BACKGROUND & AIMS

Currently, only a few genetic variants explain the heritability of fatty liver disease. Quantitative trait loci (QTL) analysis of mouse strains has identified the susceptibility locus Ltg/NZO (liver triglycerides from New Zealand obese [NZO] alleles) on chromosome 18 as associating with increased hepatic triglycerides. Herein, we aimed to identify genomic variants responsible for this association.

METHODS

Recombinant congenic mice carrying 5.3 Mbp of Ltg/NZO were fed a high-fat diet and characterized for liver fat. Bioinformatic analysis, mRNA profiles and electrophoretic mobility shift assays were performed to identify genes responsible for the Ltg/NZO phenotype. Candidate genes were manipulated in vivo by injecting specific microRNAs into C57BL/6 mice. Pulldown coupled with mass spectrometry-based proteomics and immunoprecipitation were performed to identify interaction partners of IFGGA2.

RESULTS

Through positional cloning, we identified 2 immunity-related GTPases (Ifgga2, Ifgga4) that prevent hepatic lipid storage. Expression of both murine genes and the human orthologue IRGM was significantly lower in fatty livers. Accordingly, liver-specific suppression of either Ifgga2 or Ifgga4 led to a 3-4-fold greater increase in hepatic fat content. In the liver of low-fat diet-fed mice, IFGGA2 localized to endosomes/lysosomes, while on a high-fat diet it associated with lipid droplets. Pulldown experiments and proteomics identified the lipase ATGL as a binding partner of IFGGA2 which was confirmed by co-immunoprecipitation. Both proteins partially co-localized with the autophagic marker LC3B. Ifgga2 suppression in hepatocytes reduced the amount of LC3B-II, whereas overexpression of Ifgga2 increased the association of LC3B with lipid droplets and decreased triglyceride storage.

CONCLUSION

IFGGA2 interacts with ATGL and protects against hepatic steatosis, most likely by enhancing the binding of LC3B to lipid droplets.

LAY SUMMARY

The genetic basis of non-alcoholic fatty liver disease remains incompletely defined. Herein, we identified members of the immunity-related GTPase family in mice and humans that act as regulators of hepatic fat accumulation, with links to autophagy. Overexpression of the gene Ifgga2 was shown to reduce hepatic lipid storage and could be a therapeutic target for the treatment of fatty liver disease.

Noncoding RNAs in Nonalcoholic Fatty Liver Disease: Potential Diagnosis and Prognosis Biomarkers

Nonalcoholic fatty liver disease (NAFLD) is currently the most common chronic liver disease worldwide in part due to the concomitant obesity pandemic and insulin resistance (IR). It is increasingly becoming evident that NAFLD is a disease affecting numerous extrahepatic vital organs and regulatory pathways. The molecular mechanisms underlying the nonalcoholic steatosis formation are poorly understood, and little information is available on the pathways that are responsible for the progressive hepatocellular damage that follows lipid accumulation. Recently, much research has focused on the identification of the epigenetic modifications that contribute to NAFLD pathogenesis. Noncoding RNAs (ncRNAs) are one of such epigenetic factors that could be implicated in the NAFLD development and progression. In this review, we summarize the current knowledge of the genetic and epigenetic factors potentially underlying the disease. Particular emphasis will be put on the contribution of microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs) to the pathophysiology of NAFLD as well as their potential use as therapeutic targets or as markers for the prediction and the progression of the disease.

Risk factors for histological progression of non-alcoholic steatohepatitis analyzed from repeated biopsy cases

BACKGROUND AND AIM

The most important prognostic factor for non-alcoholic steatohepatitis (NASH) is liver fibrosis. The aim of this study is to examine clinical parameters involved in pathological progression in NASH patients who underwent repeated liver biopsy and to analyze the response to treatment with respect to NASH-related single nucleotide polymorphisms (SNPs). We performed longitudinal analysis of genetic and clinical factors associated with progression of NASH.

METHODS

Eighty NASH patients who had undergone serial liver biopsies were enrolled in this retrospective cohort study. Histological exacerbation was determined based on non-alcoholic fatty liver disease activity score (NAS) and liver fibrosis.

RESULTS

About 22.5% had progression of fibrosis, 22.5% had improvement of fibrosis, and 55.0% had no change. NAS increased in 12.5%, decreased in 61.3%, and remained stable in the remaining 26.3%. We examined factors associated with histological progression versus non-progression. Poor response of alanine aminotransferase (ALT) levels, increase in HbA1c levels, and presence of the tumor necrosis factor risk allele in the rs1799964 SNP were identified as independent risk factors contributing to histological progression in NASH patients. In addition, we found that the histological progression rate varies with ALT response, HbA1c levels, and rs1799964 genotype.

CONCLUSIONS

In this study, we clarified the serum ALT level and the clinical significance of HbA1c to evaluate the progression of fibrosis in Japanese NASH patients. Furthermore, the tumor necrosis factor SNP was more likely to be involved in the response than PNPLA3 SNP. By simultaneously evaluating three factors, it is possible to estimate the risk of histological progression more accurately.

Association of Genetic and Environmental Factors with Non-Alcoholic Fatty Liver Disease in a Chinese Han Population

Lifestyle choices such as the intake of sweets, history of diseases, and genetic variants seem to play a role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). To explore which genetic and environmental factors are associated with NAFLD in a Chinese Han population, we conducted this study. We collected the medical reports, lifestyle details, and blood samples of individuals and used the polymerase chain reaction-ligase detection reaction method to genotype the single-nucleotide polymorphism (SNPs) from the 2113 eligible people. The GG genotype of the additive model of rs7493 in the PON2, the CC genotype of the additive and recessive models of rs7593130 in the ADCY3, together with dyslipidemia, regular intake of egg and sweets and hypertension, increased the risk of NAFLD (adjusted OR > 1, p < 0.05). The TT genotype of the additive and dominant models of rs11583680 in the PCSK9, together with the regular intake of vegetable, reduced the risk of NAFLD (adjusted OR < 1, p < 0.05). In addition, interactions between some variables were found. Eventually, we identified three SNPs and six environmental factors associated with NAFLD. These results provide the theoretical basis for gene and other risk factors screening to prevent NAFLD.

The Role of Bone Morphogenetic Protein Signaling in Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) affects over 30% of adults in the United States. Bone morphogenetic protein (BMP) signaling is known to contribute to hepatic fibrosis, but the role of BMP signaling in the development of NAFLD is unclear. In this study, treatment with either of two BMP inhibitors reduced hepatic triglyceride content in diabetic (db/db) mice. BMP inhibitor-induced decrease in hepatic triglyceride levels was associated with decreased mRNA encoding Dgat2, an enzyme integral to triglyceride synthesis. Treatment of hepatoma cells with BMP2 induced DGAT2 expression and activity via intracellular SMAD signaling. In humans we identified a rare missense single nucleotide polymorphism in the BMP type 1 receptor ALK6 (rs34970181;R371Q) associated with a 2.1-fold increase in the prevalence of NAFLD. In vitro analyses revealed R371Q:ALK6 is a previously unknown constitutively active receptor. These data show that BMP signaling is an important determinant of NAFLD in a murine model and is associated with NAFLD in humans.

Long noncoding RNA CCAT1 inhibits miR-613 to promote nonalcoholic fatty liver disease via increasing LXRα transcription

Nonalcoholic fatty liver disease (NAFLD) is regarded as a threat to public health; however, the pathologic mechanism of NAFLD is not fully understood. We attempted to identify abnormally expressed long noncoding RNA (lncRNAs) and messenger RNA that may affect the occurrence and development of NAFLD in this study. The expression of differentially expressed lncRNAs in NAFLD was determined in oleic acid (OA)-treated L02 cells, and the functions of CCAT1 in lipid droplet formation were evaluated in vitro. Differentially expressed genes (DEGs) were analyzed by microarray analysis, and DEGs related to CCTA1 were selected and verified by weighted correlation network analysis. The dynamic effects of LXRα and CCTA1 on lipid droplet formation and predicted binding was examined. The binding between miR-631 and CCAT1 and LXRα was verified. The dynamic effects of miR-613 inhibition and CCTA1 silencing on lipid droplet formation were examined. The expression and correlations of miR-631, CCAT1, and LXRα were determined in tissue samples. As the results show, CCAT1 was induced by OA and upregulated in NAFLD clinical samples. CCAT1 silencing significantly suppressed lipid droplet accumulation in vitro. LXRα was positively correlated with CCAT1. By inhibiting miR-613, CCAT1 increased the transcription of LXRα and promoted LXRα expression. The expression of LXRα was significantly increased in NAFLD tissues and was positively correlated with CCAT1. In conclusion, CCAT1 increases LXRα transcription by serving as a competing endogenous RNA for miR-613 in an LXRE-dependent manner, thereby promoting lipid droplet formation and NAFLD. CCAT1 and LXRα might be potent targets for NAFLD treatment.

Genetic Risk for Hepatic Fat among an Ethnically Diverse Cohort of Youth: The Exploring Perinatal Outcomes among Children Study

OBJECTIVE

To assess the importance of genetic and nongenetic risk factors contributing to hepatic fat accumulation in a multiethnic population of youth.

STUDY DESIGN

We investigated the relationship between genetic factors and hepatic fat fraction (HFF) in 347 children aged 12.5-19.5 years. We examined 5 single nucleotide polymorphisms previously associated with HFF and a weighted genetic risk score (GRS) and examined how these associations varied with ethnicity (Hispanic vs non-Hispanic white) and body mass index (BMI) category. We also compared how much variation in HFF was explained by genetic factors vs cardiometabolic factors (BMI z-score and the Homeostasis Model of Insulin Resistance) or diet.

RESULTS

PNPLA3 rs738409 and the GRS were each associated with HFF among Hispanic (β = 0.39; 95% CI, 0.16-0.62; P = .001; and β = 0.20; 95% CI, 0.05-0.34; P = .007, respectively) but not non-Hispanic white (β = 0.04; 95% CI, -0.18 to 0.26; P = .696; and β = 0.03; 95% CI, -0.09 to 0.14; P = .651, respectively) youth. Cardiometabolic risk factors explained more of the variation in HFF than genetic risk factors among non-lean Hispanic individuals (27.2% for cardiometabolic markers vs 6.4% for rs738409 and 4.3% for the GRS), and genetic risk factors were more important among lean individuals (2.7% for cardiometabolic markers vs 12.6% for rs738409 and 4.4% for the GRS).

CONCLUSIONS

Poor cardiometabolic health may be more important than genetic factors when predicting HFF in overweight and obese young populations. Genetic risk is an important contributor to pediatric HFF among lean Hispanics, but further studies are necessary to elucidate the strength of the association between genetic risk and HFF in non-Hispanic white youth.

Risk of Kidney Dysfunction IN Nafld

Background:

The timely identification of traditional and non-traditional precursors and risk factors for chronic kidney disease (CKD) (a common systemic disease defined as a decreased kidney function documented by reduced glomerular filtration rate, or markers of kidney damage, or both) is relevant in clinical practice, as CKD increases the risk of end-stage renal disease and other serious comorbidities. A possible relationship between non-alcoholic fatty liver disease (NAFLD) (which is to date the most common chronic disease worldwide) and CKD has recently gained significant attention of researchers.

Methods :

A systematic literature search using appropriate keywords was made in order to identify relevant articles that have investigated the association between NAFLD and CKD.

Results:

Several observational studies and meta-analyses have reported the existence of an independent association between NAFLD and risk of CKD in patients with and without diabetes. However, whilst the association between NAFLD and risk of prevalent CKD is strong across various patient populations, whether NAFLD is independently associated with the development and progression of CKD is still debatable. Moreover, emerging evidence now suggests a potential association between patatin-like phospholipase domain-containing protein-3 (PNPLA3) rs738409 genotype (the most important genetic variant associated to NAFLD) and decreasing kidney function, independent of NAFLD.

Conclusions :

Convincing evidence now indicates that CKD is increased among patients with NAFLD. For this reason, patients with NAFLD should be regularly monitored for renal function and, on the other hand , NAFLD should be considered in all patients with CKD, especially if they are obese or have type 2 diabetes.

Application of Deep Learning in Quantitative Analysis of 2-Dimensional Ultrasound Imaging of Nonalcoholic Fatty Liver Disease

OBJECTIVES

To verify the value of deep learning in diagnosing nonalcoholic fatty liver disease (NAFLD) by comparing 3 image-processing techniques.

METHODS

A total of 240 participants were recruited and divided into 4 groups (normal, mild, moderate, and severe NAFLD groups), according to the definition and the ultrasound scoring system for NAFLD. Two-dimensional hepatic imaging was analyzed by the envelope signal, grayscale signal, and deep-learning index obtained by 3 image-processing techniques. The values of the 3 methods ranged from 0 to 65,535, 0 to 255, and 0 to 4, respectively. We compared the values among the 4 groups, draw receiver operating characteristic curves, and compared the area under the curve (AUC) values to identify the best image-processing technique.

RESULTS

The envelope signal value, grayscale value, and deep-learning index had a significant difference between groups and increased with the severity of NAFLD (P < .05). The 3 methods showed good ability (AUC > 0.7) to identify NAFLD. Meanwhile, the deep-learning index showed the superior diagnostic ability in distinguishing moderate and severe NAFLD (AUC = 0.958).

CONCLUSIONS

The envelope signal and grayscale values were vital parameters in the diagnosis of NAFLD. Furthermore, deep learning had the best sensitivity and specificity in assessing the severity of NAFLD.

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

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

Effect of vitamin E in non-alcoholic fatty liver disease: a systematic review and meta-analysis of randomised controlled trials

The efficacy of vitamin E among patients with non-alcoholic fatty liver disease (NAFLD) is unclear. The current qualitative and quantitative analyses aimed to ascertain the efficacy of vitamin E on clinical outcomes of patients with NAFLD. A systematic search of randomised controlled trials (RCTs) was performed using databases (PubMed, ProQuest, Scopus, EBSCOhost and Ovid) from inception to July 2018. Trials meeting the inclusion criteria were subjected to quality assessment using the Jadad Scoring. All trials meeting the prerequisites information for meta-analysis were subjected to quantitative synthesis of results. Nine RCTs (five in adults and four in children) were included. Four of the five RCTs on adults demonstrated significant improvements in alanine transaminase and other liver function surrogates in patients with NAFLD. On the other hand, only one of the four RCTs conducted on children showed significant improvements in liver functions with the use of vitamin E. Although quantitative synthesis of available data revealed insignificant differences between vitamin E and placebo, still the use of vitamin E improves the level of alanine transaminase and aspartate transaminase by -1.96 and -0.59, with heterogeneity of I²=67% and I²=0%, respectively. Adjuvant vitamin E therapy provides significant biochemical and histological improvements in adult patients with NAFLD, while paediatric patients showed insignificant efficacy compared with placebo. Lifestyle interventions along with vitamin E can provide much better results. Data, including the impact of vitamin E on hepatic histology, are still lacking. Moreover, the short duration of trials limits the conclusion on the safety and efficacy of proposed treatments.

An intronic variant in the GCKR gene is associated with multiple lipids

Previous studies have shown that an intronic variant rs780094 of the GCKR gene (glucokinase regulatory protein) is significantly associated with several metabolites, but the associations of this genetic variant with different lipids is largely unknown. Therefore, we applied metabolomics approach to measure metabolites in a large Finnish population sample (METSIM study) to investigate their associations with rs780094 of GCKR. We measured metabolites by mass spectrometry from 5,181 participants. P < 5.8 × 10-5 was considered as statistically significant given 857 metabolites included in statistical analyses. We found novel negative associations of the T allele of GCKR rs780094 with serine and threonine, and positive associations with two metabolites of tryptophan, indolelactate and N-acetyltryptophan. Additionally, we found novel significant positive associations of this genetic variant with 12 glycerolipids and 19 glycerophospholipids. Significant negative associations were found for three glycerophospholipids (all plasmalogen-cholines), and two sphingolipids. Significant novel associations were also found with gamma-glutamylthreonine, taurocholenate sulfate, and retinol. Our study adds new information about the pleiotropy of the GCKR gene, and shows the associations of the T allele of GCKR rs780094 with lipids.

Relationship Between PNPLA3 rs738409 Polymorphism and Decreased Kidney Function in Children With NAFLD

Emerging evidence suggests that patatin-like phospholipase domain-containing protein-3 (PNPLA3) rs738409 genotype (the major genetic variant associated with susceptibility to nonalcoholic fatty liver disease [NAFLD]) is associated with decreased kidney function in adults. Currently, it is uncertain whether this association also occurs in children/adolescents and whether any association is independent of liver disease severity. We enrolled a sample of 142 Caucasian children and adolescents with biopsy-proven NAFLD, presenting to the Liver Unit of the "Bambino Gesù" Children's Hospital. The glomerular filtration rate (e-GFR) was estimated using the Bedside Schwartz equation, whereas 24-hour proteinuria was measured using a radioimmunoassay method. Genotyping for the PNPLA3 rs738409 genotype was undertaken using the single-nucleotide polymorphism genotyping allelic discrimination method. Overall, 45 children had G/G, 56 had G/C, and 41 had C/C PNPLA3 rs738409 genotype, respectively. Children with G/G genotype had significantly lower e-GFR (107.5 ± 20 versus 112.8 ± 18 versus 125.3 ± 23 mL/min/1.73 m² , P = 0.002) and higher 24-hour proteinuria (58.5 ± 21 versus 53.9 ± 22 versus 42.9 ± 20 mg/day, P = 0.012) compared with those with either G/C or C/C genotypes. After adjustment for age, sex, systolic blood pressure, measures of adiposity, homeostasis model assessment-estimated insulin resistance and biopsy-confirmed nonalcoholic steatohepatitis and stage of liver fibrosis, the presence of rs738409 G/G genotype was independently associated with both lower e-GFR (β coefficient: -23.6; 95% confidence interval [CI]: -36.3 to -10.8; P < 0.001) and higher 24-hour proteinuria (β coefficient: 15.3; 95% CI: 1.12 to 30.5; P = 0.046). Conclusion: Regardless of established renal risk factors and the histological severity of NAFLD, the PNPLA3 G/G genotype was strongly associated with decreasing kidney function and increasing 24-hour proteinuria in children/adolescents with histologically confirmed NAFLD.

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.

Molecular pathways of nonalcoholic fatty liver disease development and progression

Nonalcoholic fatty liver disease (NAFLD) is a main hepatic manifestation of metabolic syndrome. It represents a wide spectrum of histopathological abnormalities ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) with or without fibrosis and, eventually, cirrhosis and hepatocellular carcinoma. While hepatic simple steatosis seems to be a rather benign manifestation of hepatic triglyceride accumulation, the buildup of highly toxic free fatty acids associated with insulin resistance-induced massive free fatty acid mobilization from adipose tissue and the increased de novo hepatic fatty acid synthesis from glucose acts as the "first hit" for NAFLD development. NAFLD progression seems to involve the occurrence of "parallel, multiple-hit" injuries, such as oxidative stress-induced mitochondrial dysfunction, endoplasmic reticulum stress, endotoxin-induced, TLR4-dependent release of inflammatory cytokines, and iron overload, among many others. These deleterious factors are responsible for the triggering of a number of signaling cascades leading to inflammation, cell death, and fibrosis, the hallmarks of NASH. This review is aimed at integrating the overwhelming progress made in the characterization of the physiopathological mechanisms of NAFLD at a molecular level, to better understand the factor influencing the initiation and progression of the disease.

Genetically Regulated Bilirubin and Risk of Non-alcoholic Fatty Liver Disease: A Mendelian Randomization Study

Mildly elevated serum bilirubin levels were reported to be associated with decreased risk of non-alcoholic fatty liver disease (NAFLD). Whether this is a causal relationship remains unclear. We tested the hypothesis that genetically elevated plasma bilirubin levels are causally related to reduce risk of NAFLD. A total of 403 eligible participants were enrolled. NAFLD was determined by liver ultrasonography. The uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) gene variants (UGT1A1^*6 and UGT1A1^*28) were genotyped through sequencing. We applied a Mendelian randomization approach to assess the effects of genetically elevated bilirubin levels on NAFLD. NAFLD was diagnosed in 19% of participants in our study (NAFLD = 76; Non-NAFLD = 327). The variants of UGT1A1^*28 and UGT1A1^*6 were strongly associated with increased total bilirubin (TB), direct bilirubin (DB), and indirect bilirubin (IB) levels (each P < 0.001). These two common variants explain 12.7% (TB), 11.4% (IB), and 10.2% (DB) of the variance in bilirubin levels, respectively. In logistic regression model, after multifactorial adjustment for sex, age, aminotransferase (ALT), white blood count (WBC), and body mass index (BMI), variant UGT1A1^*28 (OR = 1.39; 95%CI: 0.614–3.170; P = 0.43) and UGT1A1^*6 (OR = 1.64, 95%CI, 0.78–3.44; P = 0.19) genotypes were not significantly associated with the risk of NAFLD. Moreover, the plasma bilirubin level (TB, IB, and DB) were not significantly associated with the risk of NAFLD (P > 0.30). A Mendelian randomization analysis of the UGT1A1 variants suggests that bilirubin is unlikely causally related with the risk of NAFLD.

The rs626283 Variant in the MBOAT7 Gene is Associated with Insulin Resistance and Fatty Liver in Caucasian Obese Youth

OBJECTIVES

Non alcoholic fatty liver disease (NAFLD) is a leading cause of liver damage in childhood, its occurrence is influenced by genetic and environmental factors. Recently, the rs626283 polymorphism in the MBOAT7 gene has been found to be associated with alcoholic liver disease and NAFLD in adults.

METHODS

In a multiethnic cohort of obese children and adolescents we genotyped the rs626283 polymorphism in the MBOAT7 gene, evaluated insulin sensitivity by an oral glucose tolerance test, and measured the intra-hepatic fat content (HFF%) by magnetic resonance imaging.

RESULTS

In Caucasian youth, the minor allele (C) was associated with HFF% in (P=0.003), fasting insulin (P=0.03), area under the curve of glucose (P=0.03), and lower degree of whole-body insulin sensitivity (P=0.01) independent of age, gender, and body mass index z-score. A partial correlation showed that the association between the rs626283 variant and insulin resistance was driven by the presence of hepatic steatosis (P=0.009). However, there was no association between the rs626283 and hepatic steatosis among Hispanic and African American children and youth. The association between the rs626283 in the MBOAT7 gene among Caucasians was independent of the PNPLA3 rs738409, GCKR 1260326, and TM6SF2 rs58542926 (P=0.01). The four polymorphisms combined explained~19% of the HFF% in Caucasian obese children and adolescents.

CONCLUSIONS

The rs626283 variant in the MBOAT7 gene is associated with NAFLD and may affect glucose metabolism by modulating intra-hepatic fat content in Caucasian obese children and adolescents.

Vitamin D and Nonalcoholic Fatty Liver Disease: Bi-directional Mendelian Randomization Analysis

Background

Vitamin D deficiency is associated with nonalcoholic fatty liver disease (NAFLD) in many cross-sectional studies. However, the causality between them has not been established. We used bi-directional mendelian randomization (MR) analysis to explore the causal relationship between 25-hydroxyvitamin D [25(OH)D] and NAFLD.

Methods

9182 participants were included from a survey in East China from 2014 to 2016. We calculated weighted genetic risk scores (GRS) for 25(OH)D concentration and NAFLD based on 25(OH)D-related and NAFLD-related single nucleotide polymorphisms. Presence of liver steatosis was assessed using ultrasound. Instrumental variable was used to measure the causal relationship between them.

Results

An SD increase in the 25(OH)D GRS was significantly associated with 25(OH)D (β 1.29, 95%CI − 1.54, − 1.04, P < 0.05) but not with NAFLD (OR 0.97, 95%CI 0.92, 1.01). An SD increase in NAFLD GRS was also strongly associated with NAFLD (OR 1.09, 95%CI 1.04, 1.15, P < 0.05) but not with 25(OH)D (β − 0.15, 95%CI − 0.41, 0.10). Using an instrumental variable estimator, no associations were found for genetically instrumented 25(OH)D with NAFLD and for genetically instrumented NAFLD with 25(OH)D.

Conclusion

Our results support the conclusion that there is no causal association between vitamin D and NAFLD using a bi-directional MR approach in a Chinese population.

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The causality between vitamin D and NAFLD was controversial in human beings.

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Using mendelian randomization analysis, 25(OH)D and NAFLD are not causally associated.

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Long-term vitamin D deficiency may not affect the development of NAFLD.

Genetic variants in COL13A1, ADIPOQ and SAMM50, in addition to the PNPLA3 gene, confer susceptibility to elevated transaminase levels in an admixed Mexican population

Non-alcoholic fatty liver disease (NAFLD) is the accumulation of extra fat in liver cells not caused by alcohol. Elevated transaminase levels are common indicators of liver disease, including NAFLD. Previously, we demonstrated that PNPLA3 (rs738409), LYPLAL1 (rs12137855), PPP1R3B (rs4240624), and GCKR (rs780094) are associated with elevated transaminase levels in overweight/obese Mexican adults. We investigated the association between 288 SNPs identified in genome-wide association studies and risk of elevated transaminase levels in an admixed Mexican-Mestizo sample of 178 cases of NAFLD and 454 healthy controls. The rs2896019, rs12483959, and rs3810622 SNPs in PNPLA3 and rs1227756 in COL13A1 were associated with elevated alanine aminotransferase (ALT, ≥40IU/L). A polygenic risk score (PRS) based on six SNPs in the ADIPOQ, COL13A1, PNPLA3, and SAMM50 genes was also associated with elevated ALT. Individuals carrying 9-12 risk alleles had 65.8% and 48.5% higher ALT and aspartate aminotransferase (AST) levels, respectively, than those with 1-4 risk alleles. The PRS showed the greatest risk of elevated ALT levels, with a higher level of significance than the individual variants. Our findings suggest a significant association between variants in COL13A1, ADIPOQ, SAMM50, and PNPLA3, and risk of NAFLD/elevated transaminase levels in Mexican adults with an admixed ancestry. This is the first study to examine high-density single nucleotide screening for genetic variations in a Mexican-Mestizo population. The extent of the effect of these variations on the development and progression of NAFLD in Latino populations requires further analysis.

Interferon lambda 4 rs368234815 TT>δG variant is associated with liver damage in patients with nonalcoholic fatty liver disease

The interferon (IFN) lambda 3/4 (IFNL3/4) locus, influencing innate immunity regulation, has been associated with the severity of hepatitis and fibrosis progression during chronic hepatitis C infection, while contrasting results were reported in nonalcoholic fatty liver disease. In this study, we examined whether rs12979860 and the linked causal rs368234815 variant encoding for the alternative IFNL4 protein variant are associated with liver fibrosis and damage in a large multicenter cohort of patients at risk of nonalcoholic steatohepatitis. To clarify the mechanism, we also evaluated the impact on IFN-stimulated gene hepatic expression in a subset of patients. We considered 946 consecutive Italian individuals at risk of nonalcoholic steatohepatitis with liver histology evaluated according to Kleiner. The rs368234815 TT>δG, rs12979860 C>T, and patatin-like phospholipase-3 rs738409 C>G polymorphisms were genotyped; and IFN-stimulated gene hepatic expression (n = 16) was tested by TaqMan assays. We found that the rs368234815 TT allele was independently associated with severe F3-F4 fibrosis (odds ratio, 1.53; 95% confidence interval, 1.15-2.31; P = 0.005) and with severe (grade 2-3) lobular necroinflammation (odds ratio, 1.47; 95% confidence interval, 1.14-1.88; P = 0.002). The impact of rs368234815 on liver damage was generally more marked in nonobese individuals, where association with severe fibrosis, necroinflammation, and nonalcoholic steatohepatitis was observed (P < 0.05). IFN-stimulated genes were hypo-expressed in the liver of patients carrying the IFNL4 rs368234815 TT/TT genotype (P < 0.05). Similar results were observed when considering the rs12979860 polymorphism, which was in high linkage disequilibrium with rs368234815 (R² = 0.87).

CONCLUSION

The IFNL4 genotype is associated with severity of fibrosis in nonalcoholic fatty liver disease patients of European ancestry, likely by modulating the activation of innate immunity and necroinflammation. (Hepatology 2017;66:1885-1893).

MTP genetic variants associated with non-alcoholic fatty liver in metabolic syndrome patients

This study was performed for investigation the relationship between variants of MTP gene polymorphism and the development of NAFLD in patients with and without MS. The study was included 174 NAFLD patients (106 with MS and 68 without MS), and 141 healthy control subjects. The 493 G/T polymorphism of MTP gene was evaluated by PCR-RFLP method. The frequency of MTP TT genotype and T allele were significantly higher in NAFLD patients when compared to healthy controls. Moreover, a significant association in MTP gene polymorphism was observed in NAFLD patients with MS compared to NAFLD patients without MS and controls. Our study suggested that MTP 493 G/T gene polymorphism may act as susceptibility biomarker for NAFLD and MS.

Human germline hedgehog pathway mutations predispose to fatty liver

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) is the most common form of liver disease. Activation of hedgehog (Hh) signaling has been implicated in the progression of NAFLD and proposed as a therapeutic target; however, the effects of Hh signaling inhibition have not been studied in humans with germline mutations that affect this pathway.

METHODS

Patients with holoprosencephaly (HPE), a disorder associated with germline mutations disrupting Sonic hedgehog (SHH) signaling, were clinically evaluated for NAFLD. A combined mouse model of Hh signaling attenuation (Gli2 heterozygous null: Gli2^+/-) and diet-induced NAFLD was used to examine aspects of NAFLD and hepatic gene expression profiles, including molecular markers of hepatic fibrosis and inflammation.

RESULTS

Patients with HPE had a higher prevalence of liver steatosis compared to the general population, independent of obesity. Exposure of Gli2^+/- mice to fatty liver-inducing diets resulted in increased liver steatosis compared to wild-type mice. Similar to humans, this effect was independent of obesity in the mutant mice and was associated with decreased expression of pro-fibrotic and pro-inflammatory genes, and increased expression of PPARγ, a potent anti-fibrogenic and anti-inflammatory regulator. Interestingly, tumor suppressors p53 and p16INK4 were found to be downregulated in the Gli2^+/- mice exposed to a high-fat diet.

CONCLUSIONS

Our results indicate that germline mutations disrupting Hh signaling promotes liver steatosis, independent of obesity, with reduced fibrosis. While Hh signaling inhibition has been associated with a better NAFLD prognosis, further studies are required to evaluate the long-term effects of mutations affecting this pathway. Lay summary: Non-alcoholic fatty liver disease (NAFLD) is characterized by excess fat deposition in the liver predominantly due to high calorie intake and a sedentary lifestyle. NAFLD progression is usually accompanied by activation of the Sonic hedgehog (SHH) pathway leading to fibrous buildup (scar tissue) and inflammation of the liver tissue. For the first time patients with holoprosencephaly, a disease caused by SHH signaling mutations, are shown to have increased liver steatosis independent of obesity. This observation was recapitulated in a mouse model of attenuated SHH signaling that also showed increased liver steatosis but with decreased fibrosis and inflammation. While SHH inhibition is associated with a good NAFLD prognosis, this increase in liver fat accumulation in the context of SHH signaling inhibition must be studied prospectively to evaluate its long-term effects, especially in individuals with Western-type dietary habits.

Interpreting lipoproteins in nonalcoholic fatty liver disease

PURPOSE OF REVIEW

The pathophysiologies of nonalcoholic fatty liver disease (NAFLD), metabolic syndrome, and cardiovascular disease are closely interlinked and associated with atherogenic dyslipidemia. Liver and cardiovascular disease may silently progress to advanced stages if alarming signs, such as abdominal obesity, elevated fasting and postprandial triglycerides, and low HDL cholesterol are overlooked. We review the metabolic mechanisms in NAFLD at the cellular level in the context of standard clinical lipid measurements.

RECENT FINDINGS

We discuss the pathogenesis of NAFLD, nonalcoholic steatohepatitis (NASH), and metabolic syndrome, atherogenic dyslipidemia, lipotoxicity, and lipophagy.

SUMMARY

Physicians should infer from biomarkers or clinical findings that their abdominally obese patients are at risk of severe cardiovascular, liver fatty disease, or both. Physicians should carry out laboratory tests of plasma cholesterol, triglycerides, LDL and HDL cholesterol, non-HDL cholesterol, apolipoprotein B and platelets, and for diabetes, but importantly, plasma triglycerides also in the nonfasting state. But note, clinical routine plasma lipid and lipoprotein measurements are not necessarily reliable for interpreting severe metabolic changes. Notably, in advanced stages of NAFLD (i.e., late steatohepatitis and cirrhosis), routine lipid profiles do not necessarily show any more abnormalities.

Fibronectin Type III Domain-Containing Protein 5 rs3480 A>G Polymorphism, Irisin, and Liver Fibrosis in Patients With Nonalcoholic Fatty Liver Disease

CONTEXT

Contrasting data have been reported on the role of irisin, a novel myokine encoded by the fibronectin type III domain-containing protein 5 (FNDC5) gene, in nonalcoholic fatty liver disease (NAFLD) pathogenesis. We tested in patients with suspected nonalcoholic steatohepatitis (NASH) the association of FNDC5 variants, hepatic expression, and circulating irisin with liver damage (F2 to F4 fibrosis as main outcome). We also investigated whether irisin modulates hepatocellular fat accumulation and stellate cell activation in experimental models.

METHODS

We considered 593 consecutive patients who underwent liver biopsy for suspected NASH and 192 patients with normal liver enzymes and without steatosis. FNDC5 rs3480 and rs726344 genotypes were assessed by 5' nuclease assays. Hepatic irisin expression was evaluated in mice fed a high-fat diet or treated with CCl4. The effect of irisin was evaluated in fat-laden HepG2 hepatocytes and in hepatic stellate cells (HSCs).

RESULTS

In patients at risk for NASH [odds ratio (OR) = 0.64, 95% confidence interval (CI), 0.47 to 0.87; P = 0.005], and more so in the high-risk subgroup of those with impaired fasting glucose/diabetes (OR = 0.44, 95% CI, 0.26 to 0.74; P = 0.002), the rs3480 A>G variant was independently associated with protection from F2 to F4 fibrosis. Irisin is expressed in human activated HSC, where it mediated fibrogenic actions and collagen synthesis, and is overexpressed in NAFLD patients with F2 to F4 fibrosis and CCl4-treated mice. However, Irisin does not affect fat accumulation in HepG2 and is not induced by high-fat-diet-inducing NAFLD.

CONCLUSIONS

The FNDC5 rs3480 variant is associated with protection from clinically significant fibrosis in patients with NAFLD, while irisin expression is correlated with the severity of NAFLD and may be involved in extracellular matrix deposition. These data suggest that irisin is involved in regulation of hepatic fibrogenesis.

Systems biology of personalized nutrition

Personalized nutrition is fast becoming a reality due to a number of technological, scientific, and societal developments that complement and extend current public health nutrition recommendations. Personalized nutrition tailors dietary recommendations to specific biological requirements on the basis of a person's health status and goals. The biology underpinning these recommendations is complex, and thus any recommendations must account for multiple biological processes and subprocesses occurring in various tissues and must be formed with an appreciation for how these processes interact with dietary nutrients and environmental factors. Therefore, a systems biology-based approach that considers the most relevant interacting biological mechanisms is necessary to formulate the best recommendations to help people meet their wellness goals. Here, the concept of "systems flexibility" is introduced to personalized nutrition biology. Systems flexibility allows the real-time evaluation of metabolism and other processes that maintain homeostasis following an environmental challenge, thereby enabling the formulation of personalized recommendations. Examples in the area of macro- and micronutrients are reviewed. Genetic variations and performance goals are integrated into this systems approach to provide a strategy for a balanced evaluation and an introduction to personalized nutrition. Finally, modeling approaches that combine personalized diagnosis and nutritional intervention into practice are reviewed.

Lipid droplets and liver disease: from basic biology to clinical implications

Lipid droplets are dynamic organelles that store neutral lipids during times of energy excess and serve as an energy reservoir during deprivation. Many prevalent metabolic diseases, such as the metabolic syndrome or obesity, often result in abnormal lipid accumulation in lipid droplets in the liver, also called hepatic steatosis. Obesity-related steatosis, or NAFLD in particular, is a major public health concern worldwide and is frequently associated with insulin resistance and type 2 diabetes mellitus. Here, we review the latest insights into the biology of lipid droplets and their role in maintaining lipid homeostasis in the liver. We also offer a perspective of liver diseases that feature lipid accumulation in these lipid storage organelles, which include NAFLD and viral hepatitis. Although clinical applications of this knowledge are just beginning, we highlight new opportunities for identifying molecular targets for treating hepatic steatosis and steatohepatitis.

MiR-149 Compromises the Reactions of Liver Cells to Fatty Acid via its Polymorphism and Increases Non-Alcoholic Fatty Liver Disease (NAFLD) Risk by Targeting Methylene Tetrahydrofolate Reductase (MTHFR)

BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is a worldwide health problem, and microRNA (miRNA) has been reported to be involved in NAFLD. The objective of our study was to explore the effect of polymorphism in miR-149 on the pathogenesis of NAFLD. MATERIAL AND METHODS Real-time PCR was performed to explore the effect of long-chain fatty acid (FFA) on the level of miR-149 and methylene tetrahydrofolate reductase (MTHFR). Then in-silicon analysis and luciferase assay were investigated to verify MTHFR was the target gene of miR-149. Finally, Western-blot analysis and real-time PCR were performed to confirm the control of MTHFR by miR-149. RESULTS In this study, we found that miR-149 was apparently upregulated in hepatocytes genotyped as TT treated with FFA; and MTHFR in hepatocytes genotyped as TT treated with FFA was evidently downregulated compared to control. Whereas, FFA had no obvious effect on MTHFR level in hepatocytes genotyped as CC. We searched an online miRNA database and found that miR-149 was a regulator of MTHFR expression, which was confirmed by luciferase assay. In hepatocytes genotyped as TT and treated with or without FFA, miR-149 mimic dose-dependently decreased the level of MTHFR, and miR-149 inhibitor dose-dependently increased the level of MTHFR. And in hepatocytes genotyped as CC treated with or without FFA exhibited a similar inhibition effect of miR-149 on expression of MTHFR. CONCLUSIONS The data suggested that the polymorphism in miR-149 played an important role in the development of NAFLD via altering the expression of miR-149 as well as its target, MTHFR.