Transmembrane 6 Superfamily Member 2 Research Articles

Abstract P181: Association Between Non-Alcoholic Fatty Liver Disease Risk SNP Variants and Lipid Metabolism

Introduction: The impact of non-alcoholic fatty liver disease (NAFLD) risk SNP variants on ipid metabolism in the general population has yet to be determined. We aimed to assess this association using a large prospective cohort study. Methods: A total of 1488 Japanese men and women (median age 62 years and median body mass index 24.7 kg/m2) free of cardiovascular disease were studied. Among NAFLD risk SNPs, variants of patatin-like phospholipase domain containing 3 (PNPLA3), transmembrane 6 superfamily member 2 (TM6SF2), glucokinase regulator (GCKR), and neurocan (NCAN) were assessed. Plasma total cholesterol, low-density lipoprotein cholesterol (LDL-C), small dense LDL-C (sdLDL-C), LDL-triglycerides (LDL-TG), high-density lipoprotein cholesterol (HDL-C), HDL3-C, triglycerides (TG), lipoprotein(a), and adiponectin were measured at both baseline and after a five-year follow-up. Univariate and multivariate analyses, Kruskal-Wallis, Wilcoxon’s rank sum, and paired t-tests were performed to examine the associations between NAFLD risk SNPs and lipoproteins. Results: All of the measured lipoproteins increased significantly over the 5 years. The TM6SF2 variant did not affect lipoproteins at baseline. However, after 5 years, the non-major allele group had significantly lower HDL-C and HDL3-C and significantly higher LDL-C, sdLDL-C, and LDL-TG than the major allele group. For the GCKR variant, TG, LDL-C, sdLDL-C, and LDL-TG were significantly higher in the non-major allele group at baseline; LDL-C, sdLDL-C, and LDL-TG were still significantly higher in the non-major allele group at 5 years than the CC group. The PNPLA3 and NCAN variants did not affect lipoproteins in this study. Conclusions: NAFLD risk SNP variants might influence atherogenic lipoprotein metabolism.

Basic and translational evidence supporting the role of TM6SF2 in VLDL metabolism.

Transmembrane 6 superfamily member 2 ( TM6SF2 ) gene was identified through exome-wide studies in 2014. A genetic variant from glutamic acid to lysine substitution at amino acid position 167 (NM_001001524.3:c.499G> A) (p.Gln167Lys/p.E167K, rs58542926) was discovered (p.E167K) to be highly associated with increased hepatic fat content and reduced levels of plasma triglycerides and LDL cholesterol. In this review, we focus on the discovery of TM6SF2 and its role in VLDL secretion pathways. Human data suggest TM6SF2 is linked to hepatic steatosis and cardiovascular disease (CVD), hence understanding its metabolic pathways is of high scientific interest. Since its discovery, completed research studies in cell, rodent and human models have defined the role of TM6SF2 and its links to human disease. TM6SF2 resides in the endoplasmic reticulum (ER) and the ER-Golgi interface and helps with the lipidation of nascent VLDL, the main carrier of triglycerides from the liver to the periphery. Consistent results from cells and rodents indicated that the secretion of triglycerides is reduced in carriers of the p.E167K variant or when hepatic TM6SF2 is deleted. However, data for secretion of APOB, the main protein of VLDL particles responsible for triglycerides transport, are inconsistent. The identification of genetic variants that are highly associated with human disease presentation should be followed by the validation and investigation into the pathways that regulate disease mechanisms. In this review, we highlight the role of TM6SF2 and its role in processing of liver triglycerides.

Inhibition of cellular factor TM6SF2 suppresses secretion pathways of Hepatitis B, Hepatitis C and Hepatitis D viruses.

Chronic viral hepatitis is caused by hepatitis B virus, hepatitis C virus or hepatitis D virus (HBV, HCV, and HDV). Despite different replication strategies, all these viruses rely on secretion through the host endoplasmic reticulum-Golgi pathway, providing potential host targets for antiviral therapy. Knockdown of transmembrane 6 superfamily member 2 (TM6SF2) in virus cell culture models reduced secretion of infectious HCV virions, HDV virions and HBV subviral particles. Moreover, in a cohort of people with hepatitis B a TM6SF2 polymorphism (rs58542926 CT/TT, which causes protein misfolding and reduced TM6SF2 in the liver) correlated with lower concentrations of subviral particles in blood, complementing our previous work showing decreased HCV viral load in people with this polymorphism. In conclusion, the host protein TM6SF2 plays a key role in secretion of HBV, HCV and HDV, providing the potential for novel pan-viral agents to treat people with chronic viral hepatitis.

The Intersection of Genetic Factors, Aberrant Nutrient Metabolism and Oxidative Stress in the Progression of Cardiometabolic Disease.

Cardiometabolic disease (CMD), which encompasses metabolic-associated fatty liver disease (MAFLD), chronic kidney disease (CKD) and cardiovascular disease (CVD), has been increasing considerably in the past 50 years. CMD is a complex disease that can be influenced by genetics and environmental factors such as diet. With the increased reliance on processed foods containing saturated fats, fructose and cholesterol, a mechanistic understanding of how these molecules cause metabolic disease is required. A major pathway by which excessive nutrients contribute to CMD is through oxidative stress. In this review, we discuss how oxidative stress can drive CMD and the role of aberrant nutrient metabolism and genetic risk factors and how they potentially interact to promote progression of MAFLD, CVD and CKD. This review will focus on genetic mutations that are known to alter nutrient metabolism. We discuss the major genetic risk factors for MAFLD, which include Patatin-like phospholipase domain-containing protein 3 (PNPLA3), Membrane Bound O-Acyltransferase Domain Containing 7 (MBOAT7) and Transmembrane 6 Superfamily Member 2 (TM6SF2). In addition, mutations that prevent nutrient uptake cause hypercholesterolemia that contributes to CVD. We also discuss the mechanisms by which MAFLD, CKD and CVD are mutually associated with one another. In addition, some of the genetic risk factors which are associated with MAFLD and CVD are also associated with CKD, while some genetic risk factors seem to dissociate one disease from the other. Through a better understanding of the causative effect of genetic mutations in CMD and how aberrant nutrient metabolism intersects with our genetics, novel therapies and precision approaches can be developed for treating CMD.

Abstract 13791: Non-Alcoholic Fatty Liver Disease Risk SNP Variants Affect Lipid Metabolism

Introduction: The impact of non-alcoholic fatty liver disease (NAFLD) risk SNP variants on changes in lipid metabolism in the general population has yet to be determined. We aimed to assess this association using a large prospective cohort study. Methods: A total of 1488 Japanese men and women (median age 62 years and median body mass index 24.7 kg/m2) free of cardiovascular disease were studied. Among NAFLD risk SNPs, variants of patatin-like phospholipase domain containing 3 (PNPLA3), transmembrane 6 superfamily member 2 (TM6SF2), glucokinase regulator (GCKR), and neurocan (NCAN) were assessed. Plasma total cholesterol, low-density lipoprotein cholesterol (LDL-C), small dense LDL-C (sdLDL-C), LDL-triglycerides (LDL-TG), high-density lipoprotein cholesterol (HDL-C), HDL3-C, triglycerides (TG), lipoprotein(a), and adiponectin were measured at both baseline and after a five-year follow-up. Univariate and multivariate analyses, Kruskal-Wallis, Wilcoxon’s rank sum, and paired t-tests were performed to examine the associations between NAFLD risk SNPs and lipoproteins. Results: All of the measured lipoproteins increased significantly over 5 years. The TM6SF2 variant did not affect lipoproteins at baseline. However, after 5 years, the nonCC group had significantly lower HDL-C and HDL3-C and significantly higher LDL-C, sdLDL-C, and LDL-TG than the CC group. For the GCKR variant, TG, LDL-C, sdLDL-C, and LDL-TG were significantly higher in the CT/TT group at baseline, and LDL-C, sdLDL-C, and LDL-TG were still significantly higher in the same group at 5 years versus the CC group. The PNPLA3 and NCAN variants did not affect lipoproteins in this study. Conclusions: NAFLD risk SNP variants associated with gene products regulating both glucose and lipid metabolism can affect atherogenic lipoprotein levels.

Gene Variants Implicated in Steatotic Liver Disease: Opportunities for Diagnostics and Therapeutics.

Non-alcoholic fatty liver disease (NAFLD) describes a steatotic (or fatty) liver occurring as a consequence of a combination of metabolic, environmental, and genetic factors, in the absence of significant alcohol consumption and other liver diseases. NAFLD is a spectrum of conditions. Steatosis in the absence of inflammation is relatively benign, but the disease can progress into more severe forms like non-alcoholic steatohepatitis (NASH), liver cirrhosis, and hepatocellular carcinoma. NAFLD onset and progression are complex, as it is affected by many risk factors. The interaction between genetic predisposition and other factors partially explains the large variability of NAFLD phenotype and natural history. Numerous genes and variants have been identified through large-scale genome-wide association studies (GWAS) that are associated with NAFLD and one or more subtypes of the disease. Among them, the largest effect size and most consistent association have been patatin-like phospholipase domain-containing protein 3 (PNPLA3), transmembrane 6 superfamily member 2 (TM6SF2), and membrane-bound O-acyltransferase domain containing 7 (MBOAT7) genes. Extensive in vitro and in vivo studies have been conducted on these variants to validate these associations. The focus of this review is to highlight the genetics underpinning the molecular mechanisms driving the onset and progression of NAFLD and how they could potentially be used to improve genetic-based diagnostic testing of the disease and develop personalized, targeted therapeutics.

A study of genetic variants, genetic risk score and DNA methylation of PNPLA3 and TM6SF2 in alcohol liver cirrhosis.

Genetic and epigenetic factors are associated with thedevelopment of alcohol-associated liver disease (AALD). The single nucleotide polymorphisms (SNPs), rs738409 in Patatin-like phospholipase domain-containing protein (PNPLA3) and rs58542926 in Transmembrane 6 Superfamily Member 2 (TM6SF2) are strongly associated with AALD in different global populations, Hence, we analyzed the genetic risk score for these variants and deoxyribonucleic acid (DNA) methylation levels of the PNPLA3 and TM6SF2 genes among cases (alcohol liver cirrhosis) and controls (heavy drinkers without cirrhosis). We studied patients with alcohol use disorder (AUD) with cirrhosis (AUD-C + ve, n = 136) and without cirrhosis (AUD-C-ve, n = 107) drawn from the clinical services of St. John's Medical College Hospital (SJMCH) (Gastroenterology and Psychiatry) and Centre for Addiction Medicine (CAM),National Institute of Mental Health and Neurosciences, (NIMHANS). Genotype data was generated for rs738409 (PNPLA3) and rs58542926 (TM6SF2) and used to calculate unweighted genetic risk score (uGRS) and weighted genetic risk scores (wGRS). DNA methylation levels were estimated by pyrosequencing at PNPLA3 and TM6SF2 loci. Overall we observed a significantly higher genetic risk score (weighted genetic risk score, wGRS) in individuals with alcohol use disorder compared to control population (p = < 0.01). Further, uGRS and wGRS were associated with thediagnosis of cirrhosis, even after correcting for age of onset, quantity and frequency of drinking. We also found hypomethylation at CpG2 of TM6SF2 gene in AUD-C + ve compared to AUD-C-ve (P = 0.02). We found that a genetic risk score based on SNPs in the PNPLA3 and TM6SF2 genes was significantly associated with cirrhosis in patients with AUD, suggesting a potential utility in identifying patients at risk and providing pre-emptive interventions. These may include interventions that aim to alter DNA methylation, which may be one of the mechanisms through which elevated genetic risk may influence thedevelopment of cirrhosis.

Abstract P555: Variants of Neurocan, a Nonalcoholic Fatty Liver Disease Risk Allele, Are Associated With Plaque Development in the Carotid Artery Over 5 Years

Introduction: Nonalcoholic fatty liver disease (NAFLD) genetic risk alleles are associated with lipid metabolism. However, the association between those variants and atherosclerosis has not yet been fully evaluated. Hypothesis: We hypothesized that NAFLD risk alleles are associated with the progression of atherosclerosis. Methods: A total of 1,050 Japanese men and women (median age 55 years and median body mass index 22.9 kg/m2) free of cardiovascular disease, dyslipidemia, hypertension, and diabetes were studied. . Among NAFLD risk SNPs, variants of patatin-like phospholipase domain containing 3 ( PNPLA3 ), transmembrane 6 superfamily member 2 ( TM6SF2 ), glucokinase regulator ( GCKR ), and neurocan ( NCAN ) were assessed. Plasma total cholesterol, low-density lipoprotein cholesterol (LDL-C), small dense LDL-C, LDL-triglycerides, high-density lipoprotein cholesterol (HDL-C), HDL3-C, triglycerides, remnant-like particle cholesterol, lipoprotein(a), and adiponectin were also measured. At both baseline and after a five-year follow-up, carotid intima-media thickness (cIMT) was assessed. Atherosclerosis was defined as cIMT ≥ 1.1mm or the presence of a plaque. Univariate and multivariate analyses and chi-square and Fisher’s exact tests were performed to examine the associations between NAFLD risk SNPs, lipoproteins, and progression of atherosclerosis. Results: Both median and maximum cIMT of total participants did not differ between baseline and after a five-year follow-up. Among participants without atherosclerosis at baseline, the rate of plaque development was 13.8% (121/880) with the major allele (CC) of NCAN being significantly higher than other alleles. Variants of NCAN were associated with the development of plaque ( P = 0.04, Fisher’s exact test). Participants with the CT allele of NCAN had significantly lower RLP cholesterol at baseline than those with the CC allele (7.6 mg/dl vs. 10.5 mg/dl, P = 0.02). Variants of PNPLA3 , TM6SF2 , GCKR , and NCAN were not associated with changes in lipoproteins. Conclusions: A NCAN variant, one of the NAFLD risk SNPs, was associated with the development of plaque independent of lipoprotein alterations among healthy Japanese participants.

Association between non-alcoholic fatty liver disease and subclinical hypothyroidism in children with obesity.

We aimed (i) evaluating the relationship between non-alcoholic fatty liver disease (NAFLD) and thyroid function tests, (ii) testing if the relationship between NAFLD and thyroid dysfunction could be driven by the obesity and the IR degree, and (iii) exploring the influence of the patatin-like phospholipase domain-containing protein-3 (PNPLA3) I148Mand the transmembrane 6 superfamily member 2 (TM6SF2) E167K polymorphisms on the association between NAFLD and thyroid function in children. We examined 2275 children and adolescents with obesity. Subclinical hypothyroidism (SH) was defined by thyroid-stimulating hormone (TSH) > 4.2μUI/ml with normal fT3 and fT4. Children with NAFLD showed higher SH prevalence than those without NAFLD (15.7% Vs 7.4%;p = 0.001) and showed an adjusted odds ratio (aOR) to have SH of 1.68 (95% CI:1.01-2.80;p = 0.04) while patients with SH had an aOR to show NAFLD of 2.13(95% CI:1.22-3.73;p = 0.008). Patients having severe obesity and IR degree presented an aOR to show both NAFLD and SH of 3.61 (95% CI:1.78-7.33;p < 0.0001). Subjects with NAFLD carrying the TM6SF2 167K allele had lower TSH levels than non-carriers (p = 0.03) and showed an aOR to have SH of 0.10 (95% CI: 0.01-0.79;p = 0.02). No differences were found in carriers of the PNPLA3 148M allele. A general linear model for TSH variance showed a significant association of TSH with TM6SF2 genotypes only in the NAFLD group (p = 0.001). Children with obesity and NAFLD presented increase risk of SH and vice versa likely due to the adverse effect of duration of obesity, obesity degree, and IR. The TM6SF2 E167K exerts a protective role against SH in children with obesity and NAFLD.

MTARC1 and HSD17B13 Variants Have Protective Effects on Non-Alcoholic Fatty Liver Disease in Patients Undergoing Bariatric Surgery

The severity of hepatic steatosis is modulated by genetic variants, such as patatin-like phospholipase domain containing 3 (PNPLA3) rs738409, transmembrane 6 superfamily member 2 (TM6SF2) rs58542926, and membrane-bound O-acyltransferase domain containing 7 (MBOAT7) rs641738. Recently, mitochondrial amidoxime reducing component 1 (MTARC1) rs2642438 and hydroxysteroid 17-beta dehydrogenase 13 (HSD17B13) rs72613567 polymorphisms were shown to have protective effects on liver diseases. Here, we evaluate these variants in patients undergoing bariatric surgery. A total of 165 patients who underwent laparoscopic sleeve gastrectomy and intraoperative liver biopsies and 314 controls were prospectively recruited. Genotyping was performed using TaqMan assays. Overall, 70.3% of operated patients presented with hepatic steatosis. NASH (non-alcoholic steatohepatitis) was detected in 28.5% of patients; none had cirrhosis. The increment of liver fibrosis stage was associated with decreasing frequency of the MTARC1 minor allele (p = 0.03). In multivariate analysis MTARC1 was an independent protective factor against fibrosis ≥ 1b (OR = 0.52, p = 0.03) and ≥ 1c (OR = 0.51, p = 0.04). The PNPLA3 risk allele was associated with increased hepatic steatosis, fibrosis, and NASH (OR = 2.22, p = 0.04). The HSD17B13 polymorphism was protective against liver injury as reflected by lower AST (p = 0.04) and ALT (p = 0.03) activities. The TM6SF2 polymorphism was associated with increased ALT (p = 0.04). In conclusion, hepatic steatosis is common among patients scheduled for bariatric surgery, but the MTARC1 and HSD17B13 polymorphisms lower liver injury in these individuals.

What do we know about nutrient-based strategies targeting molecular mechanisms associated with obesity-related fatty liver disease?

Obesity is a risk factor for developing nonalcoholic fatty liver disease (NAFLD), and the associated molecular mechanisms could be targeted with nutrient-based strategies. Therefore, it is necessary to review the current mechanisms to propose further treatments. Obesity facilitates the onset of insulin resistance, lipidic abnormalities, hepatic fat accumulation, lipid peroxidation, mitochondrial dysfunction, excessive reactive oxygen species (ROS) production, and inflammation, all related to further steatosis progression and fibrosis. Microbiota alterations can also influence liver disease by the translocation of pathogenic bacteria, energy extraction from short chain fatty acids (SCFAs), intestinal suppression of the expression of fasting-induced adipose factor (FIAF), reduction of bile acids, and altered choline metabolism. There are also genetic polymorphisms in metabolic proteins that predispose to a higher risk of liver diseases, such as those found in the patatin-like phospholipase domain-containing 3 (PNPLA3), transmembrane 6 superfamily member 2 (TM6SF2), membrane-bound O-acyltransferase domain-containing 7 (MBOAT7) or also known as lysophosphatidylinositol acyltransferase 1 (LPIAT1), transmembrane channel-like 4 genes (TMC4), fat mass and obesity-associated protein (FTO), the b Klotho (KLB) and carboxylesterase (CES1). No clear dietary guidelines target all mechanisms related to NAFLD development and progression. However, energy and carbohydrate intake restriction, regular physical exercise, supplementation of antioxidants, and restoration of gut microbiota seem to have beneficial effects on the new proposed features of NAFLD.

Abstract 11228: Association Between Nonalcoholic Fatty Liver Disease Risk Alleles and Atherosclerosis

Introduction: Nonalcoholic fatty liver disease (NAFLD) risk alleles are associated with lipid metabolisms. However, the association between those variants and atherosclerosis has not yet been fully evaluated. Hypothesis: We hypothesized that NAFLD genetic risk alleles are associated with the progression of atherosclerosis. Methods: A total of 1,050 Japanese men and women (median age 55 years and median body mass index 22.9 kg/m2) free of cardiovascular disease, dyslipidemia, hypertension, and diabetes were studied. Among NAFLD risk SNPs, variants of patatin-like phospholipase domain containing 3 ( PNPLA3 ), transmembrane 6 superfamily member 2 ( TM6SF2 ), glucokinase regulator ( GCKR ), and neurocan ( NCAN ) were assessed. Plasma total cholesterol, low-density lipoprotein cholesterol (LDL-C), small dense LDL-C, LDL-triglycerides, high-density lipoprotein cholesterol (HDL-C), HDL3-C, triglycerides, remnant-like particle cholesterol, lipoprotein(a), and adiponectin were also measured. At both baseline and after a five-year follow-up, carotid intima-media thickness (cIMT) was assessed. Atherosclerosis was defined as cIMT more than 1.1mm or the presence of a plaque. Univariate and multivariate analyses and chi-square and Fisher’s exact tests were performed to examine the associations between NAFLD risk SNPs, lipoproteins, and progression of atherosclerosis. Results: Both median and maximum cIMT of total participants did not differ between baseline and after a five-year follow-up. Among participants without atherosclerosis at baseline, the rate of plaque development was 13.8% (121/880) with the major allele (CC) of NCAN being significantly higher than other alleles. Variants of NCAN were associated with the development of plaque ( P = 0.04, Fisher’s exact test). Variants of PNPLA3 , TM6SF2 , GCKR , and NCAN were not associated with changes in lipoproteins. Conclusions: A NCAN variant, one of the NAFLD risk SNPs, was associated with the development of plaque independent of lipoproteins alterations among healthy Japanese participants.

TM6SF2 rs58542926 is related to hepatic steatosis, fibrosis and serum lipids both in adults and children: A meta-analysis.

Findings about the associations between transmembrane 6 superfamily member 2 (TM6SF2) rs58542926 and nonalcoholic fatty liver disease have not been consistently replicated, particularly in steatosis and fibrosis. The present study aimed to investigate the associations between the rs58542926T allele and the spectrum of NAFLD and its related metabolic phenotypes. Systematic literature research was performed to analyse the associations between rs58542926 and the spectrum of NAFLD and its related metabolic phenotypes. A random effects meta-analysis with a dominant genetic model was applied. Data from 123,800 individuals across 44 studies were included in the current meta-analysis.rs58542926 T allele was associated with an increased risk of NAFLD in both adults (OR=1.62;95% CI: 1.40, 1.86) and children (OR=2.87; 95% CI: 1.85, 4.46). Children had a stronger association with NAFLD (P=0.01). rs58542926 T allele was also positively associated with steatosis progression (mean difference=0.22; 95% CI: 0.05, 0.39) and fibrosis stage (OR=1.50;95% CI: 1.20, 1.88) in adults. The TM6SF2 rs58542926 T allele was positively associated with ALT in both adults and children (both P<0.01) and only with higher AST in adults (P<0.01). The rs58542926 T allele was negatively associated with serum total cholesterol (TC), low-density lipoprotein (LDL), and triglycerides (TGs) in both adults and children (all P<0.01).The serum level of TG was much lower in adults than in children (P<0.01). TM6SF2 rs58542926 is involved in the entire spectrum of NAFLD and its related metabolic phenotype, and differences in serum lipid levels were observed between adults and children. https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42021288163.

Profiling of cell-free DNA methylation and histone signatures in pediatric NAFLD: A pilot study.

Nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in children and adolescents, increasing the risk of its progression toward nonalcoholic steatohepatitis (NASH), cirrhosis, and cancer. There is an urgent need for noninvasive early diagnostic and prognostic tools such as epigenetic marks (epimarks), which would replace liver biopsy in the future. We used plasma samples from 67 children with biopsy-proven NAFLD, and as controls we used samples from 20 children negative for steatosis by ultrasound. All patients were genotyped for patatin-like phospholipase domain containing 3 (PNPLA3), transmembrane 6 superfamily member 2 (TM6SF2), membrane bound O-acyltransferase domain containing 7 (MBOAT7), and klotho-β (KLB) gene variants, and data on anthropometric and biochemical parameters were collected. Furthermore, plasma cell-free DNA (cfDNA) methylation was quantified using a commercially available kit, and ImageStream(X) was used for the detection of free circulating histone complexes and variants. We found a significant enrichment of the levels of histone macroH2A1.2 in the plasma of children with NAFLD compared to controls, and a strong correlation between cfDNA methylation levels and NASH. Receiver operating characteristic curve analysis demonstrated that combination of cfDNA methylation, PNPLA3 rs738409 variant, coupled with either high-density lipoprotein cholesterol or alanine aminotransferase levels can strongly predict the progression of pediatric NAFLD to NASH with area under the curve >0.87. Conclusion: Our pilot study combined epimarks and genetic and metabolic markers for a robust risk assessment of NAFLD development and progression in children, offering a promising noninvasive tool for the consistent diagnosis and prognosis of pediatric NAFLD. Further studies are necessary to identify their pathogenic origin and function.

The impact of polymorphism in PNPLA3 and TM6SF2 genes on the susceptibility and survival of hepatitis C-related hepatocellular carcinoma

BackgroundGenetic variants of Patatin-like phospholipase domain-containing protein 3 (PNPLA3) and transmembrane 6 superfamily member 2 (TM6SF2) genes have been reported with the development of hepatocellular carcinoma (HCC). This study aims to explore the role of The PNPLA3 rs738409 and TM6SF2 rs58542926 single-nucleotide polymorphisms (SNPs) on the incidence and survival of HCV-induced HCC in Egyptians.Methods and resultsThis case-control study included (120) HCC and (144) hepatitis C virus (HCV) patients. Baseline clinical, laboratory, tumor characteristics data, HCC recurrence, and overall survival were collected. PNPLA3 rs738409 and TM6SF2 rs58542926 polymorphism were detected by TaqMan allelic discrimination assay. We found that HCC patients were significantly older with male predominance. A significant difference between the TT genotypes of TM6SF2 frequency was observed in HCC compared with HCV patients. Moreover, the T allele of TM6SF2 distributions revealed a significant contribution to the different stages of HCC (p=0.03). Both PNPLA3 rs738409 and TM6SF2 rs58542926 variants showed a significant relation with treatment response according to the modified RECIST criteria. Age and diabetes mellitus were the independent factors associated with the development of HCC by multivariate regression analysis.ConclusionsTM6SF2 rs58542926 polymorphism, not PNPLA3 rs738409, could be implicated in the development of HCV-induced HCC and its progression.

Myeloid TM6SF2 Deficiency Inhibits Atherosclerosis.

Genetic variants in transmembrane 6 superfamily member 2 (TM6SF2), such as E167K, are associated with atherosclerotic cardiovascular disease (ASCVD). Chronic inflammation and lipid-laden macrophage foam cell formation are the central pathogeneses in the development of atherosclerosis. This study was undertaken to illustrate the biological function of TM6SF2 in macrophages and its role during atherosclerosis development. We generated myeloid cell-specific Tm6sf2 knockout mice on ApoE-deficient background (LysM Cre+/Tm6sf2fl/fl/ApoE−/−, TM6 mKO) with littermate LysM Cre−/Tm6sf2fl/fl/ApoE−/− (Control) mice as controls. Mice were fed a Western diet for 12 weeks to induce atherosclerosis. Myeloid Tm6sf2 deficiency inhibited atherosclerosis and decreased foam cells in the plaques without changing the plasma lipid profile. RNA sequencing of bone marrow-derived macrophages (BMDMs) from TM6 mKO mice demonstrated the downregulation of genes associated with inflammation, cholesterol uptake, and endoplasmic reticulum (ER) stress. TM6SF2 was upregulated by oxidized low-density lipoprotein (oxLDL) in macrophages. Silencing TM6SF2 in THP-1-derived macrophages and Tm6sf2 deficiency in BMDMs reduced inflammatory responses and ER stress and attenuated cholesterol uptake and foam cell formation, while the overexpression of TM6SF2 showed opposite effects. In conclusion, myeloid TM6SF2 deficiency inhibits atherosclerosis development and is a potential therapeutic target for the treatment of atherogenesis.

Genetic variants associated with metabolic dysfunction-associated fatty liver disease in western China.

IntroductionWe aimed to confirm the association between some single nucleotide polymorphisms (SNPs) and metabolic dysfunction‐associated fatty liver disease (MAFLD) in western China.MethodsA total of 286 cases and 250 healthy controls were enrolled in our study. All samples were genotyped for patatin‐like phospholipase domain containing 3 (PNPLA3) rs738409, transmembrane 6 superfamily member 2 (TM6SF2) rs58542926, membrane‐bound O‐acyltransferase domain containing 7 (MBOAT7) rs641738, glucokinase regulator (GCKR) rs1260326 and rs780094, and GATA zinc finger domain containing 2A (GATAD2A) rs4808199. Using logistic regression analysis, we evaluated the association between MAFLD and each SNP under different models. Multiple linear regression was used to find the association between SNPs and laboratory characteristics. Multifactor dimensionality reduction was applied to test SNP–SNP interactions.ResultsThe recessive model and additive model of PNPLA3 rs738409 variant were related to MAFLD (odds ratio [OR] = 1.791 and 1.377, respectively, p = 0.038 and 0.027, respectively). However, after Benjamini‐Hochberg adjustment for multiple tests, all associations were no longer statistically significant. PNPLA3 rs738409 correlated with AST levels. GCKR rs780094 and rs1260326 negatively correlated with serum glucose but positively correlated with triglycerides in MAFLD. Based on MDR analysis, the best single‐locus and multilocus models for MAFLD risk were rs738409 and six‐locus models, respectively.ConclusionsIn the Han population in western China, no association was found between these SNPs and the risk of MAFLD. PNPLA3 rs738409 was associated with aspartate aminotransferase levels in MAFLD patients. GCKR variants were associated with increased triglyceride levels and reduced serum fasting glucose in patients with MAFLD.

Influence of Type 2 Diabetes in the Association of PNPLA3 rs738409 and TM6SF2 rs58542926 Polymorphisms in NASH Advanced Liver Fibrosis.

Nonalcoholic steatohepatitis (NASH) is a leading cause of cirrhosis in western countries. Insulin resistance (IR), type 2 diabetes (T2D), and the polymorphisms patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 and transmembrane 6 superfamily member 2 (TM6SF2) rs58542926 are independent risk factors of NASH. Nevertheless, little is known about the interaction between IR and T2D with these polymorphisms in the pathogenesis of NASH and the development of advanced fibrosis. Thus, our study aimed to investigate this relationship. This is a cross-sectional study including NASH patients diagnosed by liver biopsy, at the Vall d’Hebron University Hospital. A total of 140 patients were included (93 T2D, 47 non-T2D). T2D (OR = 4.67; 95%CI 2.13–10.20; p < 0.001), PNPLA3 rs738409 and TM6SF2 rs58542926 polymorphisms (OR = 3.94; 95%CI 1.63–9.54; p = 0.002) were independently related with advanced liver fibrosis. T2D increased the risk of advance fibrosis on top of the two polymorphisms (OR = 14.69; 95%CI 3.03–77.35; p = 0.001 for PNPLA3 rs738409 and OR = 11.45; 95%CI 3.16–41.55; p < 0.001 for TM6SF2 rs58542926). In non-T2D patients, the IR (HOMA-IR ≥ 5.2, OR = 14.33; 95%CI 2.14–18.66; p = 0.014) increased the risk of advanced fibrosis when the polymorphisms were present (OR = 19.04; 95%CI 1.71–650.84; p = 0.042). The T2D and IR status increase the risk of advanced fibrosis in patients with NASH carrying the PNPLA3 rs738409 and/or TM6SF2 rs58542926 polymorphisms, respectively.

Evaluation of the association of a variant in PNPLA3 and TM6SF2 with fibrosis progression in patients with chronic hepatitis C infection after eradication: A retrospective study.

The relationship of single nucleotide polymorphisms (SNPs) in patatin-like phospholipase domain containing 3 (PNPLA3) rs738409, transmembrane 6 superfamily member 2 (TM6SF2) rs58542926, and membrane bound O-acyltransferase domain containing 7 (MBOAT7) rs641738 with outcomes in patients with hepatitis C infection (HCV) is unclear. This study aimed to evaluate the association of PNPLA3, TM6SF2, and MBOAT7 with the baseline fibrosis stage and progression of liver fibrosis after HCV eradication with direct antiviral agents (DAAs). A total of 171 patients who received the DAAs at the Peking University First Hospital between June 2015 and June 2020 were included in the retrospective cohort. Transient elastography was used to determine liver stiffness measurements (LSMs) at the baseline, the end of treatment (EOT), 24weeks after treatment (W24), and the last follow-up (LFU) visit. We used the QIAamp Blood Mini Kit (Qiagen) for whole blood genomic DNA extraction and polymerase chain reaction for PNPLA3, TM6SF2, and MBOAT7 amplification of the target gene. The PNPLA3 rs738409 SNP was associated with the baseline fibrosis stage in multivariate logistic regression analysis adjusted for other factors, and the adjusted odds ratio (OR) for advanced fibrosis (≥F3) at baseline was 2.52 (95% confidence interval[CI]=1.096-5.794, p=0.03). The G and GG alleles were predictive of advanced fibrosis (OR=1.98, 95% CI=1.021-4.196, p=0.015; OR=3.12, 95% CI=1.572-6.536, p=0.005). Similarly, the OR of TM6SF2 rs58542926 at baseline was 2.608 (95% CI=1.081-6.29, p=0.033). T and TT alleles were predictive of advanced fibrosis (OR=2.3, 95% CI=1.005-5.98, p=0.007; OR=3.05, 95% CI=1.32-6.87, p=0.001). After adjustment, the MBOAT7 rs641738 T plus TT alleles were not independently associated with the baseline fibrosis stage (95% CI=0.707-2.959, p=0.312). At the EOT, there were 35 patients and 136 patients in the fibrosis improvement and fibrosis non-improvement group, respectively. Logistic regression analysis showed that the G allele in PNPLA3 rs738409 was associated with fibrosis progression (OR=2.47, 95% CI=1.125-5.89, p=0.003). The GG alleles were predictive of fibrosis progression (OR=2.95, 95% CI=1.35-6.35, p=0.005). Similarly, the ORs of the T and TT alleles in TM6SF2 rs58542926 for fibrosis progression were 1.82 and 2.21, respectively (95% CI=1.006-5.373, p=0.045; 95% CI=1.18-5.75, p=0.01). At the W24 visit, we found that there was an association between the G allele in PNPLA3 rs738409 and fibrosis progression (OR=2.218, 95% CI=1.095-5.631, p=0.015). Moreover, GG alleles were also predictive for fibrosis progression (OR=2.558, 95% CI=1.252-5.15, p=0.008). Similarly, the OR of T allele and TT alleles in TM6SF2 rs58542926 for fibrosis progression was 2.056 and 2.652 (95% CI=1.013-5.592, p=0.038; 95% CI=1.25-5.956, p=0.015). For additional affirmation, we surveyed fibrosis progression utilizing the Cox proportional hazards model. G and GG alleles in PNPLA3 rs738409 were associated with an increased risk of progression to advanced fibrosis in multivariate model (hazard ratio [HR]1.566, 95% CI=1.02-2.575, p=0.017; and HR2.109, 95% CI=1.36-3.271, p=0.001, respectively). Besides, T and TT alleles in TM6SF2 rs58542926 were associated with an increased risk of progression to advanced fibrosis in multivariate model (HR=1.322, 95% CI=1.003-1.857, p=0.045; and HR=1.855, 95% CI=1.35-2.765, p=0.006, respectively). In contrast, rs641738 in MBOAT7 did not show a significant trend in the univariate and multivariate models. The PNPLA3 CG/GG SNP at rs738409 and TM6SF2 CT/TT SNP at rs58542926 were associated with the baseline fibrosis stage and fibrosis progression after HCV eradication with DAAs.

Metabolic Syndrome but Not Fatty Liver-Associated Genetic Variants Correlates with Glomerular Renal Function Decline in Patients with Non-Alcoholic Fatty Liver Disease.

The association between non-alcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD) has been extensively demonstrated. Recent studies have focused attention on the role of patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 polymorphism in the association between NAFLD and CKD in non-metabolic adults and children, but the genetic impact on NAFLD-CKD association is still a matter of debate. The aim of the study was to investigate the impact of PNPLA3, transmembrane 6 superfamily member 2 (TM6SF2), membrane-bound O-acyltransferase domain containing 7 (MBOAT7) and glucokinase regulatory protein (GCKR) gene variants rather than metabolic syndrome features on renal function in a large population of NAFLD patients. The present study is a post hoc analysis of the Plinio Study (ClinicalTrials.gov: NCT04036357). PNPLA3, TM6SF2, MBOAT7 and GCKR genes were analyzed by using real-time PCR with TaqMan probes. Glomerular filtration rate (GFR) was estimated with CKD-EPI. We analyzed 538 NAFLD; 47.2% had GFR < 90 mL/min/1.73 m2 while 5.9% had GFR < 60 mL/min/1.73 m2. The distribution of genotypes was superimposable according to GFR cut-offs. Results from the multivariable regression model did not show any correlation between genotypes and renal function. Conversely, metabolic syndrome was highly associated with GFR < 90 mL/min/1.73 m2 (odds ratio (OR): 1.58 [1.10–2.28]) and arterial hypertension with GFR < 60 mL/min/1.73 m2 (OR: 1.50 [1.05–2.14]). In conclusion, the association between NAFLD and CKD might be related to the shared metabolic risk factors rather than the genetic NAFLD background.