The impact of patatin-like phospholipase domain-containing protein 3 polymorphism on hepatocellular carcinoma prognosis

Personalized medicine and nutrition in hepatology for preventing chronic liver disease in Mexico

Chronic liver disease is a global health issue. Patients with chronic liver disease require a fresh approach that focuses on the genetic and environmental factors that contribute to disease initiation and progression. Emerging knowledge in the fields of Genomic Medicine and Genomic Nutrition demonstrates differences between countries in terms of genetics and lifestyle risk factors such as diet, physical activity, and mental health in chronic liver disease, which serves as the foundation for the implementation of Personalized Medicine and Nutrition (PerMed-Nut) strategies. Most of the world's populations have descended from various ethnic groupings. Mexico's population has a tripartite ancestral background, consisting of Amerindian, European, and African lineages, which is common across Latin America's regional countries. The purpose of this review is to discuss the genetic and environmental components that could be incorporated into a PerMed-Nut model for metabolic-associated liver disease, viral hepatitis B and C, and hepatocellular carcinoma in Mexico. Additionally, the implementation of the PerMed-Nut approach will require updated medicine and nutrition education curricula. Training and equipping future health professionals and researchers with new clinical and investigative abilities focused on preventing liver illnesses in the field of genomic hepatology globally is a vision that clinicians and nutritionists should be concerned about.

Clinical Practice Guidelines of the Russian Scientific Liver Society, Russian Gastroenterological Association, Russian Association of Endocrinologists, Russian Association of Gerontologists and Geriatricians and National Society for Preventive Cardiology on Diagnosis and Treatment of Non-Alcoholic Liver Disease

Aim:present clinical guidelines, aimed at general practitioners, gastroenterologists, cardiologists, endocrinologists, comprise up-to-date methods of diagnosis and treatment of non-alcoholic fatty liver disease.Key points.Nonalcoholic fatty liver disease, the most wide-spread chronic liver disease, is characterized by accumulation of fat by more than 5 % of hepatocytes and presented by two histological forms: steatosis and nonalcoholic steatohepatitis. Clinical guidelines provide current views on pathogenesis of nonalcoholic fatty liver disease as a multisystem disease, methods of invasive and noninvasive diagnosis of steatosis and liver fibrosis, principles of nondrug treatment and pharmacotherapy of nonalcoholic fatty liver disease and associated conditions. Complications of nonalcoholic fatty liver disease include aggravation of cardiometabolic risks, development of hepatocellular cancer, progression of liver fibrosis to cirrhotic stage.Conclusion.Progression of liver disease can be avoided, cardiometabolic risks can be reduced and patients' prognosis — improved by the timely recognition of diagnosis of nonalcoholic fatty liver disease and associated comorbidities and competent multidisciplinary management of these patients.

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

Background

Genetic 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 results

This 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.

Conclusions

TM6SF2 rs58542926 polymorphism, not PNPLA3 rs738409, could be implicated in the development of HCV-induced HCC and its progression.

MAFLD: Renovation of clinical practice and disease awareness of fatty liver

Recently, international expert panels have proposed a new definition of fatty liver: metabolic dysfunction-associated fatty liver disease (MAFLD). MAFLD is not just a simple renaming of non-alcoholic fatty liver disease (NAFLD). The unique feature of MAFLD is the inclusion of metabolic dysfunctions, which are high-risk factors for events. In addition, MAFLD is independent of alcohol intake and the co-existing causes of liver disease. This new concept of MAFLD may have a widespread impact on patients, medical doctors, medical staff, and various stakeholders regarding fatty liver. Thus, MAFLD may renovate clinical practice and disease awareness of fatty liver. In this review, we introduce the definition of and rationale for MAFLD. We further describe representative cases showing how the diagnostic processes differ between MAFLD and NAFLD. We also summarize recent studies comparing MAFLD with NAFLD and discuss the impact of MAFLD on clinical trials, Japanese populations, and disease awareness.

The National Consensus statement on the management of adult patients with non-alcoholic fatty liver disease and main comorbidities

The National Consensus was prepared with the participation of the National Medical Association for the Study of the Multimorbidity, Russian Scientific Liver Society, Russian Association of Endocrinologists, Russian Association of Gerontologists and Geriatricians, National Society for Preventive Cardiology, Professional Foundation for the Promotion of Medicine Fund PROFMEDFORUM. The aim of the multidisciplinary consensus is a detailed analysis of the course of non-alcoholic fatty liver disease (NAFLD) and the main associated conditions. The definition of NAFLD is given, its prevalence is described, methods for diagnosing its components such as steatosis, inflammation and fibrosis are described. The association of NAFLD with a number of cardio-metabolic diseases (arterial hypertension, atherosclerosis, thrombotic complications, type 2 diabetes mellitus (T2DM), obesity, dyslipidemia, etc.), chronic kidney disease (CKD) and the risk of developing hepatocellular cancer (HCC) were analyzed. The review of non-drug methods of treatment of NAFLD and modern opportunities of pharmacotherapy are presented. The possibilities of new molecules in the treatment of NAFLD are considered: agonists of nuclear receptors, antagonists of pro-inflammatory molecules, etc. The positive properties and disadvantages of currently used drugs (vitamin E, thiazolidinediones, etc.) are described. Special attention is paid to the multi-target ursodeoxycholic acid (UDCA) molecule in the complex treatment of NAFLD as a multifactorial disease. Its anti-inflammatory, anti-oxidant and cytoprotective properties, the ability to reduce steatosis an independent risk factor for the development of cardiovascular pathology, reduce inflammation and hepatic fibrosis through the modulation of autophagy are considered. The ability of UDCA to influence glucose and lipid homeostasis and to have an anticarcinogenic effect has been demonstrated. The Consensus statement has advanced provisions for practitioners to optimize the diagnosis and treatment of NAFLD and related common pathogenetic links of cardio-metabolic diseases.

Research progress, challenges and perspectives on PNPLA3 and its variants in Liver Diseases

The human patatin-like phospholipase domain-containing 3 gene (PNPLA3) is highly expressed in liver and adipose tissue and encodes a transmembrane polypeptide chain containing 481 amino acids. The I148M variant of PNPLA3 is a single nucleotide polymorphism, which is related to a variety of liver and cardiovascular diseases and their complications (such as non-alcoholic fatty liver disease, liver fibrosis, coronary artery disease). This review mainly describes the pathophysiological effects of PNPLA3 and its variants, and their roles in the progression of liver disease and its complications.

Interplay of PNPLA3 and HSD17B13 Variants in Modulating the Risk of Hepatocellular Carcinoma among Hepatitis C Patients

A single-nucleotide polymorphism causing a C to G change in the PNPLA3 gene (rs738409) is associated with disease severity and development of hepatocellular carcinoma (HCC) in nonalcoholic fatty liver disease; the insertion variant rs72613567:TA of the 17β-hydroxysteroid dehydrogenase type 13 (HSD17B13) mitigates this detrimental effect. Our aim was to evaluate if the same holds true in chronic hepatitis C virus infection (HCV). With a case control retrospective study design, we selected 110 patients who developed HCC on a background of HCV infection, matching each patient for sex and age (±30 months) to three HCV-infected, non-HCC patients. All participants underwent genotyping for PNPLA3 and HSD17B13 gene variants. Both univariate and multivariate analyses of risk factors for advanced disease and HCC were performed. Carriage of PNPLA3 G∗ allele was associated with a trend of progressively more severe liver disease, from mild fibrosis to significant fibrosis, cirrhosis, and HCC (p = 0.007). When the HSD17B13:TA status of these patients was taken into account, the abovementioned trend was strengthened among HSD17B13 major allele homozygotes and completely blunted among carriers of the minor allele (p = 0.0003 and 0.953, respectively). In a conditional logistic regression model including diabetes and AST to platelet ratio index among predictor variables, the unfavourable genetic profile characterized by the coexistence of the PNPLA3 minor allele and HSD17B13 major allele (vs. all other possible combinations) was an independent risk factor for HCC (OR = 2.00, 95% CI: 1.23-3.26) together with a history of alcohol abuse. In conclusion, carriage of the combination PNPLA3 minor allele and HSD17B13 major allele may represent a risk factor for HCC among HCV-infected patients. The interplay between the two genes may explain some of the controversy on this topic and may be exploited to stratify HCC risk in hepatitis C.

Familial non-alcoholic steatohepatitis leading to hepatocellular carcinoma

BACKGROUND AND AIMS

Non-alcoholic steatohepatitis (NASH) has been associated with fibrosis that may progress to cirrhosis. The purpose of this study was to examine hepatocytes and perisinusoidal cells in liver biopsies of 3 families (3 males and 4 females) with non-cirrhotic and cirrhotic NASH to determine unique histological changes during a period of 2-7 years from diagnosis.

METHODS

In this study, hepatocytes, stellate cells and Kupffer cells were analyzed using light and electron microscopy, and immunohistochemistry with specific anti-macrophage antibody staining of liver biopsies.

RESULTS

Body mass index of all patients was over 28, and all viral, metabolic markers were negative. Alcohol consumption was insignificant. In all liver biopsies, diffuse, non-zonal macrovesicular steatosis involved 40-70% of liver samples. The lobular hepatocytes showed prominent ballooning hepatocyte degeneration. No Mallory Denk hyaline bodies (MDBs) were observed in three of the patients. MDBs developed in ballooned hepatocytes of four individuals that also presented foci of lobular inflammation. The apoptotic bodies were stained by cytokeratin 18. The trichrome stain revealed portal to portal bridging fibrosis. In one family, there was a three-fold increase in relative numbers of perisinusoidal macrophages in the older sister with NASH compared to livers of the younger siblings. The special finding in livers of patients with NASH was accumulation of groups of perisinusoidal macrophages, which was not associated with focal necrosis.

CONCLUSION

Perisinusoidal macrophages appear to accumulate in NASH. It is possible that collections of macrophages are a response to chronic portal endotoxemia or lipotoxic activation of immuno-mediators. The persistent activation of these macrophages could lead to the chronic release of pro-inflammatory cytokines and contribute to chronic inflammation, fibrosis and cirrhosis leading to HCC.

PNPLA3-A Potential Therapeutic Target for Personalized Treatment of Chronic Liver Disease

Patatin-like phospholipase domain-containing protein 3 (PNPLA3) is a lipid droplet-associated protein that has been shown to have hydrolase activity toward triglycerides and retinyl esters. The first evidence of PNPLA3 being associated with fatty liver disease was revealed by a genome-wide association study (GWAS) of Hispanic, African American, and European American individuals in the Dallas Heart Study back in 2008. Since then, numerous GWAS reports have shown that PNPLA3 rs738409[G] (148M) variant is associated with hepatic triglyceride accumulation (steatosis), inflammation, fibrosis, cirrhosis, and even hepatocellular carcinoma regardless of etiologies including alcohol- or obesity-related and others. The frequency of PNPLA3(148M) variant ranges from 17% in African Americans, 23% in European Americans, to 49% in Hispanics in the Dallas Heart Study. Due to high prevalence of obesity and alcohol consumption in modern societies, the PNPLA3(148M) gene variant and environment interaction poses a serious concern for public health, especially chronic liver diseases including alcohol-related liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD). Therefore, PNPLA3(148M) variant is a potential therapeutic target for chronic liver disease in the rs738409 allele carriers. Currently, there is no approved drug specifically targeting the PNPLA3(148M) variant yet. With additional mechanistic studies, novel therapeutic strategies are expected to be developed for the treatment of the PNPLA3(148M) variant-associated chronic liver diseases in the near future.

Association of PNPLA3 rs738409 polymorphism with liver steatosis but not with cirrhosis in patients with HBV infection: Systematic review with meta-analysis

BACKGROUND

Hepatitis B virus (HBV) infection is a worldwide health issue and is well known for being the main cause of developing secondary liver complications such as cirrhosis and hepatocellular carcinoma (HCC). The PNPLA3 rs738409 polymorphism has been investigated conclusively with occurrence risk of steatosis and cirrhosis. Therefore, performing a meta-analysis of the available studies with the aim of clarifying the association between rs738409 and occurrence risk of steatosis and cirrhosis among HBV-infected patients would be helpful.

METHODS

Chronic HBV infection was defined as the persistence of HBsAg for more than 6 months. To gather sufficient data for this meta-analysis, reliable databases were conclusively searched using appropriate keywords. Only studies that satisfied the inclusion criteria were enrolled in the present study.

RESULTS

This meta-analysis pooled four studies with 1135 cases of chronic hepatitis B (CHB) to evaluate the impact of PNPLA3 SNP on liver steatosis and also pooled five studies with 3713 cases of CHB to evaluate the impact of PNPLA3 SNP on cirrhosis. The association of rs738409 with each complication was investigated. The rs738409 was found to be associated with steatosis in recessive [p = 4.57 × 10^-6 , odds ratio (OR) = 2.85], dominant (p = 4.35 × 10^-6 , OR = 1.84), co-dominant (p = 6.18 × 10^-8 ; OR = 3.74) and allelic (p = 9.79 × 10^-9 ; OR = 1.78) models. No association was found between rs738409 and cirrhosis development in recessive (p = 0.99, OR = 1.00), dominant (p = 0.30, OR = 0.92), co-dominant (p = 0.74; OR = 0.96) and allelic (p = 0.45; OR = 0.96) models.

CONCLUSIONS

Although the PNPLA3 rs738409 G allele has been associated with the risk of steatosis in CHB patients, no association between this polymorphism and the risk of cirrhosis was seen.

Independent and additive effects of PNPLA3 and TM6SF2 polymorphisms on the development of non-B, non-C hepatocellular carcinoma

BACKGROUND

This study was aimed at evaluating the association between single nucleotide polymorphisms (SNPs) in the PNPLA3, NCAN, TM6SF2 and MBOAT7 and hepatocellular carcinoma (HCC) development in Thai patients according to underlying etiologies of liver disease.

METHODS

These SNPs were determined by allelic discrimination in blood samples of 105 healthy controls and 530 patients with HCC [270 with hepatitis B virus (HBV-HCC), 131 with hepatitis C virus (HCV-HCC), and 129 with non-B, non-C HCC (NBNC-HCC) matched for age and gender].

RESULTS

G allele of PNPLA3 rs738409 variant was significantly higher in NBNC-HCC (49%) compared to healthy controls (32%), HBV-HCC (32%) and HCV-HCC (31%) (P < 0.001). T allele of TM6SF2 rs58542926 was more prevalent in NBNC-HCC (24%) than in healthy controls (8%), HBV-HCC (10%) and HCV-HCC (12%) (P < 0.001). The distribution of NCAN (rs2228603) and MBOAT7 (rs641738) was not different between groups. In multivariate logistic regression analysis, PNPLA3 rs738409 (OR 2.06, 95% CI 1.24-3.43; P = 0.005) and TM6SF2 rs58542926 (OR 2.22, 95% CI 1.34-3.65; P = 0.002) were independently associated with NBNC-HCC compared to viral-related HCC (VR-HCC). The proportion of patients with NBNC-HCC increased significantly along with the increase of the number of risk alleles. There was no association between these SNPs and overall survival in patients with HCC.

CONCLUSIONS

These data showed that PNPLA3 and TM6SF2 polymorphisms were independently linked to NBNC-HCC but not HBV- or HCV-HCC in Thai populations. In addition, the risk genotypes might interact with each other through tumor development in patients with NBNC-HCC.

Host genetic factors associated with hepatocellular carcinoma in patients with hepatitis C virus infection: A systematic review

Hepatitis C virus (HCV)-infected patients are at risk of developing hepatocellular carcinoma (HCC). Individuals at heightened risk could be targeted by intensive follow-up surveillance. We have conducted a systematic review of the literature to identify host genetic predisposition to HCC in HCV-infected patients. A comprehensive search of Medline and Embase databases was performed, and the strength of evidence of associations for each gene on development of HCC was evaluated. We identified 166 relevant studies, relating to 137 different genes, or combinations thereof. Seventeen genes were classified as having "good" evidence of an association, a significant association was observed for 37 genes but this finding had not yet been replicated, 56 genes had mixed or limited evidence of an association, and 27 genes showed no association. IFNL3/4, TNF-α and PNPLA3 genes had the most evidence of an association. There was, however, considerable heterogeneity in study design and data quality. In conclusion, we identified a number of genes with evidence of association with HCC, but also a need for more standardized approaches to address this clinically critical question. It is important to consider the underlying mechanism of these relationships and which are confounded by the presence of other HCC risk factors and response to therapy. We also identified many genes where the evidence of association is contradictory or requires replication, as well as a number where associations have been studied but no evidence found. These findings should help to direct future studies on host genetic predisposition to HCC in HCV-infected patients.

Combination of PNPLA3 and TLL1 polymorphism can predict advanced fibrosis in Japanese patients with nonalcoholic fatty liver disease

BACKGROUND

Hepatic fibrosis is an independent risk factor for mortality and liver-related events in patients with nonalcoholic fatty liver disease (NAFLD). PNPLA3 rs738409 has been associated with fibrosis in viral and non-viral hepatitis. TLL1 rs17047200 also has been associated with developing hepatocellular carcinoma probably via hepatic fibrogenesis. We estimated the impact of these genetic polymorphisms on hepatic fibrosis in Japanese patients with NAFLD.

METHODS

We analyzed the association between these genetic variants and the backgrounds of 817 individuals who received health checkups (health check cohort) from 2012 to 2014. Then, we investigated the relationship between genetic variants and liver histology in 258 consecutive patients with biopsy-proven NAFLD in Japan (NAFLD cohort) from 2012 to 2017 (UMIN000027399).

RESULTS

The prevalence of PNPLA3 CG/GG in the NAFLD cohort was higher than that in the health check cohort (p < 0.001). The prevalence of patients with advanced fibrosis (stages 3-4) was higher for PNPLA3 genotype CG/GG than CC (p = 0.048) and for TLL1 genotype AT/TT than AA (p = 0.044). The high-risk group which had at least two risk alleles of these variants was more likely to have advanced fibrosis (p = 0.004). Multivariate analysis identified body mass index [odds ratio (OR) 1.123, serum AST (OR 1.037, p = 0.004], serum albumin (OR 0.247, p = 0.032), and genetic high risk (OR 2.632, p = 0.026) as predictors of advanced fibrosis.

CONCLUSIONS

In Japanese patients with NAFLD, individuals with risk alleles of PNPLA3 and TLL1 may have a risk of advanced fibrosis.

Suppressed Fat Mobilization Due to PNPLA3 rs738409 -Associated Liver Damage in Heavy Drinkers: The Liver Damage Feedback Hypothesis

PNPLA3 variant rs738409 has been identified as important progression factor in patients with ALD and NAFLD, the most common liver diseases worldwide. These findings point towards similarities between metabolism of alcohol and fat with regard to the PNPLA3 gene. However, despite many efforts, neither the mechanisms of PNPLA3-related liver damage nor the physiological role of PNPLA3 are fully understood. Based on a large monocentric cohort of Caucasian heavy drinkers we could recently provide evidence that PNPLA3 GG primarily correlated with signs of liver damage (steatohepatitis, ballooning) but less with steatosis. Moreover, upon alcohol withdrawal, PNPLA3 GG carriers showed a delayed inflammation-associated resolution of liver stiffness. In line with the histological findings, hepatic fat content as quantified by CAP (controlled attenuation parameter) did not depend on PNPLA3 status and decreased equally in all genotypes by ca. 30 dB/m during alcohol withdrawal. Preliminary additional analysis from this large cohort indicates that PNPLA3 GG carriers (8.2%) drink significantly less high percentage beverages (23% vs 55%, p < 0.001) but show no metabolic phenotype such as increased weight, BMI or diabetes. On the molecular level, key molecules, important for lipolysis and flow of free fatty acids to the liver were drastically reduced in G carriers. These included the liver-synthesized serum ApoA1, the LD-associated protein perilipin5 and the recently identified hepato-protective transcriptional cofactor transducin beta-like-related 1 (TBLR1). Based on these findings, we here introduce the liver damage feedback hypothesis. Accordingly, PNPLA3-mediated liver damage (e.g. by enhanced metabolic activity) suppresses the mobilization of fat towards the liver at various levels (reduced serum lipid flux to the liver and fat mobilization from peripheric adipose tissues, suppressed hepatocyte fat release and avoidance of high percentage alcohol beverages). Finally, the liver damage feedback hypothesis identifies a novel and central role of liver damage on systemic fat homeostasis, which has not been appreciated so far.

Development of hepatocellular carcinoma in Japanese patients with biopsy-proven non-alcoholic fatty liver disease: Association between PNPLA3 genotype and hepatocarcinogenesis/fibrosis progression

AIM

Some patients with non-alcoholic fatty liver disease (NAFLD) develop hepatocellular carcinoma (HCC). Patatin-like phospholipase domain containing 3 (PNPLA3) rs738409 (encoding the I148M variant) has been associated with advanced fibrosis and HCC. We determined the risk factors for HCC, including the PNPLA3 rs738409 polymorphism, in Japanese patients with biopsy-proven NAFLD.

METHODS

In this retrospective cohort study, we analyzed hepatocarcinogenesis in 238 patients. PNPLA3 rs738409 genotype was determined by allelic discrimination in 130 patients. Among them, 86 patients who were followed up for >5 years and without liver cirrhosis were analyzed to clarify the relationship between PNPLA3 genotype and long-term changes in biomarkers.

RESULTS

Of 238 patients, PNPLA3 genotype frequencies were: CC, 0.14; CG, 0.46; and GG, 0.40. During a follow-up period of 6.1 years, 10 patients (4.2%) with non-alcoholic steatohepatitis developed HCC. The cumulative rate of HCC was 1.9% at the end of the 5th year and 8.3% at the end of the 10th year. Multivariate analysis identified PNPLA3 genotype GG (hazard ratio, 6.36; P = 0.019) and fibrosis stage (fibrosis stage 3/4; hazard ratio, 24.4; P = 0.011) as predictors of HCC development. In the long follow-up cohort, a larger reduction in platelet count was found in the GG group (P = 0.032) despite a larger reduction in alanine aminotransferase (P = 0.023) compared to that in the CC/CG group.

CONCLUSIONS

In Japanese patients with NAFLD, severe fibrosis and PNPLA3 GG genotype were predictors of HCC development, independent of other known risk factors. Patients with the PNPLA3 GG genotype have the potential for a decreased platelet count, even when alanine aminotransferase levels are well controlled.

PNPLA3 gene in liver diseases

Genome-wide association studies (GWAS) in the field of liver diseases have revealed previously unknown pathogenic loci and generated new biological hypotheses. In 2008, a GWAS performed in a population-based sample study, where hepatic liver fat content was measured by magnetic spectroscopy, showed a strong association between a variant (rs738409 C>G p.I148M) in the patatin-like phospholipase domain containing 3 (PNPLA3) gene and nonalcoholic fatty liver disease. Further replication studies have shown robust associations between PNPLA3 and steatosis, fibrosis/cirrhosis, and hepatocellular carcinoma on a background of metabolic, alcoholic, and viral insults. The PNPLA3 protein has lipase activity towards triglycerides in hepatocytes and retinyl esters in hepatic stellate cells. The I148M substitution leads to a loss of function promoting triglyceride accumulation in hepatocytes. Although PNPLA3 function has been extensively studied, the molecular mechanisms leading to hepatic fibrosis and carcinogenesis remain unclear. This unsuspected association has highlighted the fact that liver fat metabolism may have a major impact on the pathophysiology of liver diseases. Conversely, alone, this locus may have limited predictive value with regard to liver disease outcomes in clinical practice. Additional studies at the genome-wide level will be required to identify new variants associated with liver damage and cancer to explain a greater proportion of the heritability of these phenotypes. Thus, incorporating PNPLA3 and other genetic variants in combination with clinical data will allow for the development of tailored predictive models. This attractive approach should be evaluated in prospective cohorts.

The impact of PNPLA3 and JAZF1 on hepatocellular carcinoma in non-viral hepatitis patients with type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is an established independent risk factor for hepatocellular carcinoma (HCC). T2DM is associated with non-alcoholic steatohepatitis (NASH), which is a major cause of non-HBV and non-HCV-related HCC; nevertheless, it has been difficult to identify those patients with T2DM who have a high risk of developing HCC. The aim of this study was to identify genetic determinants that predispose T2DM patients to HCC by genotyping T2DM susceptibility loci and PNPLA3.

METHODS

We recruited 389 patients with T2DM who satisfied the following three criteria: negative for HBs-Ag and anti-HCV Ab, alcohol intake <60 g/day, and history of T2DM >10 years. These patients were divided into two groups: T2DM patients with HCC (DM-HCC, n = 59) or those without HCC (DM-non-HCC, n = 330). We genotyped 51 single-nucleotide polymorphisms (SNPs) previously reported as T2DM or NASH susceptibility loci (PNPLA3) compared between the DM-HCC and DM-non-HCC groups with regard to allele frequencies at each SNP.

RESULTS

The SNP rs738409 located in PNPLA3 was the greatest risk factor associated with HCC. The frequency of the PNPLA3 G allele was significantly higher among DM-HCC individuals than DM-non-HCC individuals (OR 2.53, p = 1.05 × 10(-5)). Among individuals homozygous for the PNPLA3 G allele (n = 115), the frequency of the JAZF1 rs864745 G allele was significantly higher among DM-HCC individuals than DM-non-HCC individuals (OR 3.44, p = 0.0002).

CONCLUSIONS

PNPLA3 and JAZF1 were associated with non-HBV and non-HCV-related HCC development among Japanese patients with T2DM.

Significant Association Between Adiponutrin and Hepatocellular Carcinoma Risk

ADPN I148M polymorphism has been consistently reported to play a role in liver-associated diseases, such as alcoholic liver disease, chronic hepatitis C, and liver fat and fibrosis in nonalcoholic fatty liver disease. This significant association was also indicated in a series of hepatocellular carcinoma (HCC) studies, where the significance may be affected due to the small sample sizes. The aim of this study was to reexamine the ADPN-HCC association by use of meta-analysis. Biweekly computer-based literature searches plus manual screening were undertaken in an effort to identify all studies that met the predefined inclusion criteria. The Mantel-Haenszel method was selected to estimate risk effects (odds ratio [OR] and 95% confidence interval [CI]). To examine reliability of the pooled risk effects, we additionally performed sensitivity analysis and publication bias tests. Ten studies (1335 HCC patients and 2927 HCC-free controls) were identified for the meta-analysis. We found significantly increased risk of HCC attributable to presence of ADPN I148M polymorphism, with the highest risk associated with the M/M genotype under the recessive model of inheritance (OR = 2.23, 95% CI = 1.87-2.67, between-study heterogeneity: P = 0.468). The significant increase persisted in Caucasian and African when data were stratified by ethnicity. Subgroup analysis according to source of controls revealed similar risk effects. Our meta-analysis indicates that I148M polymorphism in the ADPN gene may independently contribute to the progression of HCC irrespective of the etiologies.

PNPLA3 I148M associations with liver carcinogenesis in Japanese chronic hepatitis C patients

Aim

To investigate associations between patatin-like phospholipase domain-containing 3 (PNPLA3) genotypes and fibrosis and hepatocarcinogenesis in Japanese chronic hepatitis C (CHC) patients.

Methods

Two hundred and thirty-one patients with CHC were examined for PNPLA3 genotypes, liver stiffness measurements (LSM), and hepatocellular carcinoma (HCC) from May 2010 to October 2012 at Fujita Health University Hospital. The rs738409 single nucleotide polymorphism (SNP) encoding for a functional PNPLA3 I148M protein variant was genotyped using a TaqMan predesigned SNP genotyping assay. LSM was determined as the velocity of a shear wave (Vs) with an acoustic radiation force impulse. Vs cut-off values for cirrhosis were set at 1.55 m/s. We excluded CHC patients with a sustained virological response or relapse after interferon treatment.

Results

PNPLA3 genotypes were CC, CG, and GG for 118, 72, and 41 patients, respectively. Multivariable logistic regression analysis selected older age (OR = 1.06; 95% CI: 1.03–1.09; p < 0.0001), higher body mass index (BMI) (OR= 1.12; 95% CI: 1.03–1.22; p = 0.0082), and PNPLA3 genotype GG (OR = 2.07; 95% CI: 0.97–4.42; p = 0.0599) as the factors independently associated with cirrhosis. When 137 patients without past history of interferon treatment were separately assessed, multivariable logistic regression analysis selected older age (OR = 1.05; 95% CI: 1.02–1.09; p = 0.0034), and PNPLA3 genotype GG (OR = 3.35; 95% CI: 1.13–9.91; p = 0.0291) as the factors independently associated with cirrhosis. Multivariable logistic regression analysis selected older age (OR = 1.12; 95% CI: 1.07–1.17; p < 0.0001), PNPLA3 genotype GG (OR = 2.62; 95% CI: 1.15–5.96; p = 0.0218), and male gender (OR = 1.83; 95% CI: 0.90–3.71); p = 0.0936) as the factors independently associated with HCC.

Conclusion

PNPLA3 genotype I148M is one of risk factors for developing HCC in Japanese CHC patients, and is one of risk factors for progress to cirrhosis in the patients without past history of interferon treatment.

Progress in understanding association of PNPLA3 I148M (rs738409) single nucleotide polymorphism with hepatocellular carcinoma and hepatic cirrhosis

Patatin-like phospholipase domain containing 3 (PNPLA3), also called adiponutrin, is mainly expressed in the hepatocellular membrane and involved in lipid metabolism. The rs738409 genetic variant causes an isoleucine-to-methionine substitution at amino acid position 148 (I148M). Recently, genome-wide association studies have described associations of PNPLA3 I148M with plasma liver enzyme levels, steatosis and fibrosis severity. Studies found that PNPLA3 I148M is associated with progression of alcoholic liver cirrhosis, clinical outcome and prognosis of alcohol related hepatocellular carcinoma (HCC), and clinical outcomes of chronic hepatitis C. PNPLA3 I148M plays an important role in liver disease progression, which can be an independent risk factor for HCC.

Association between the PNPLA3 (rs738409 C>G) variant and hepatocellular carcinoma: Evidence from a meta-analysis of individual participant data

The incidence of hepatocellular carcinoma (HCC) is increasing in Western countries. Although several clinical factors have been identified, many individuals never develop HCC, suggesting a genetic susceptibility. However, to date, only a few single-nucleotide polymorphisms have been reproducibly shown to be linked to HCC onset. A variant (rs738409 C>G, encoding for p.I148M) in the PNPLA3 gene is associated with liver damage in chronic liver diseases. Interestingly, several studies have reported that the minor rs738409[G] allele is more represented in HCC cases in chronic hepatitis C (CHC) and alcoholic liver disease (ALD). However, a significant association with HCC related to CHC has not been consistently observed, and the strength of the association between rs738409 and HCC remains unclear. We performed a meta-analysis of individual participant data including 2,503 European patients with cirrhosis to assess the association between rs738409 and HCC, particularly in ALD and CHC. We found that rs738409 was strongly associated with overall HCC (odds ratio [OR] per G allele, additive model=1.77; 95% confidence interval [CI]: 1.42-2.19; P=2.78 × 10(-7) ). This association was more pronounced in ALD (OR=2.20; 95% CI: 1.80-2.67; P=4.71 × 10(-15) ) than in CHC patients (OR=1.55; 95% CI: 1.03-2.34; P=3.52 × 10(-2) ). After adjustment for age, sex, and body mass index, the variant remained strongly associated with HCC.

CONCLUSION

Overall, these results suggest that rs738409 exerts a marked influence on hepatocarcinogenesis in patients with cirrhosis of European descent and provide a strong argument for performing further mechanistic studies to better understand the role of PNPLA3 in HCC development.

Molecular mechanisms and new treatment strategies for non-alcoholic steatohepatitis (NASH)

Non-alcoholic steatohepatitis (NASH) is a severe form of non-alcoholic fatty liver disease (NAFLD), in which most patients exhibit non-progressive, non-alcoholic fatty liver (NAFL) attributable to simple steatosis. Multiple hits, including genetic differences, fat accumulation, insulin resistance and intestinal microbiota changes, account for the progression of NASH. NAFLD is strongly associated with obesity, which induces adipokine secretion, endoplasmic reticulum (ER) and oxidative stress at the cellular level, which in turn induces hepatic steatosis, inflammation and fibrosis. Among these factors, gut microbiota are acknowledged as having an important role in initiating this multifactorial disease. Oxidative stress is considered to be a key contributor in the progression from NAFL to NASH. Macrophage infiltration is apparent in NAFL and NASH, while T-cell infiltration is apparent in NASH. Although several clinical trials have shown that antioxidative therapy with vitamin E can effectively control hepatitis pathology in the short term, the long-term effects remain obscure and have often proved to be ineffective in many other diseases. Several long-term antioxidant protocols have failed to reduce mortality. New treatment modalities that incorporate current understanding of NAFLD molecular pathogenesis must be considered.

The effect of PNPLA3 on fibrosis progression and development of hepatocellular carcinoma: a meta-analysis

OBJECTIVES

The PNPLA3 rs738409 single-nucleotide polymorphism is known to promote nonalcoholic steatohepatitis (NASH), but its association with fibrosis severity and hepatocellular carcinoma (HCC) risk is less well-defined. The objectives of this study were to determine the association between PNPLA3 and liver fibrosis severity, HCC risk, and HCC prognosis among patients with liver disease.

METHODS

We performed a systematic literature review using the Medline, PubMed, Scopus, and Embase databases through May 2013 and a manual search of national meeting abstracts from 2010 to 2012. Two investigators independently extracted data on patient populations, study methods, and results using standardized forms. Pooled odds ratios (ORs), according to PNPLA3 genotype, were calculated using the DerSimonian and Laird method for a random effects model.

RESULTS

Among 24 studies, with 9,915 patients, PNPLA3 was associated with fibrosis severity (OR 1.32, 95% confidence interval (CI) 1.20-1.45), with a consistent increased risk across liver disease etiologies. Among nine studies, with 2,937 patients, PNPLA3 was associated with increased risk of HCC in patients with cirrhosis (OR 1.40, 95% CI 1.12-1.75). On subgroup analysis, increased risk of HCC was demonstrated in patients with NASH or alcohol-related cirrhosis (OR 1.67, 95% CI 1.27-2.21) but not in those with other etiologies of cirrhosis (OR 1.33, 95% CI 0.96-1.82). Three studies, with 463 patients, do not support an association between PNPLA3 and HCC prognosis but are limited by heterogeneous outcome measures. For all outcomes, most studies were conducted in homogenous Caucasian populations, and studies among racially diverse cohorts are needed.

CONCLUSIONS

PNPLA3 is associated with an increased risk of advanced fibrosis among patients with a variety of liver diseases and is an independent risk factor for HCC among patients with nonalcoholic steatohepatitis or alcohol-related cirrhosis.

PNPLA3 I148M polymorphism, clinical presentation, and survival in patients with hepatocellular carcinoma

Background & Aims

Aim of this study was to evaluate whether the PNPLA3 I148M polymorphism, previously associated with hepatocellular carcinoma (HCC) risk, influences the clinical presentation of HCC and survival.

Methods

we considered 460 consecutive HCC patients referred to tertiary care centers in Northern Italy, 353 with follow-up data.

Results

Homozygosity for PNPLA3 148M at risk allele was enriched in HCC patients with alcoholic liver disease or nonalcoholic fatty liver disease (ALD&NAFLD: relative risk 5.9, 95% c.i. 3.5–9.9; other liver diseases: relative risk 1.9, 95% c.i. 1.1–3.4). In ALD&NAFLD patients, the PNPLA3 148M allele was associated with younger age, shorter history of cirrhosis, less advanced (Child A) cirrhosis at HCC diagnosis, and lower HCC differentiation grade (p<0.05). Homozygosity for PNPLA3 148M was associated with reduced survival in the overall series (p = 0.009), and with a higher number of HCC lesions at presentation (p = 0.007) and reduced survival in ALD&NAFLD patients (p = 0.003; median survival 30, 95% c.i. 20–39 vs. 45, 95% c.i. 38–52 months), but not in those with HCC related to other etiologies (p = 0.86; 48, 95% c.i. 32–64 vs. 55, 95% c.i. 43–67 months). At multivariate Cox regression analysis, homozygosity for PNPLA3 148M was the only negative predictor of survival in ALD&NAFLD patients (HR of death 1.57, 95% c.i. 1.12–2.78).

Conclusions

PNPLA3 148M is over-represented in ALD&NAFLD HCC patients, and is associated with occurrence at a less advanced stage of liver disease in ALD&NAFLD. In ALD&NAFLD, PNPLA3 148M is associated with more diffuse HCC at presentation, and with reduced survival.

Predictive impact of polymorphism of PNPLA3 on HCC development after interferon therapy in Japanese patients with chronic hepatitis C

The impact of single-nucleotide polymorphisms (SNP) of patatin-like phospholipase domain-containing protein 3 (PNPLA3) on development of hepatocellular carcinoma (HCC) is not clarified for Japanese patients with chronic hepatitis C. The present study investigated the associations of rs738409 PNPLA3 with HCC development after the antiviral therapy with peg-interferon and ribavirin for Japanese patients with hepatitis C virus serotype 1 and high viral load. Of the 271 patients enrolled in the study, 20 patients developed HCC, during a median follow-up period of 4.6 years. Multivariate analysis in the proportional hazards models revealed that sex, body mass index, platelet counts, and alpha feroprotein (AFP) had significant associations with HCC development (p = 0.011, 0.029, 0.0002, and 0.046, respectively). Multivariate regression analysis revealed that PNPLA3 148 M was significantly associated with serum AFP level (p = 0.032), other than body mass index, platelet count, and alanine aminotransferase (p = 0.0006, 0.0002, and 0.037, respectively), and that serum AFP level was significantly associated with PNPLA3 148 M (p = 0.017). Serum AFP level is an important factor in predicting HCC development after the antiviral therapy for Japanese patients with chronic hepatitis C, the mechanism of which might involve its significant associations with the SNP genotype of PNPLA3.

Genomic aspects of NAFLD pathogenesis

Non-alcoholic fatty liver disease (NAFLD) is the most predominant liver disease worldwide and hepatic manifestation of the metabolic syndrome. Its histology spectrum ranges from steatosis, to steatohepatitis (NASH) that can further progress to cirrhosis and hepatocellular carcinoma (HCC). The increasing incidence of NAFLD has contributed to rising numbers of HCC occurrences. NAFLD progression is governed by genetic susceptibility, environmental factors, lifestyle and features of the metabolic syndrome, many of which overlap with HCC. Gene expression profiling and genome wide association studies have identified novel disease pathways and polymorphisms in genes that may be potential biomarkers of NAFLD progression. However, the multifactorial nature of NAFLD and the limited number of sufficiently powered studies are among the current limitations for validated biomarkers of clinical utility. Further studies incorporating the links between circadian regulation and hepatic metabolism might represent an additional direction in the search for predictive biomarkers of liver disease progression and treatment outcomes.