Correlation between patatin-like phospholipase domain-containing protein 3 gene polymorphisms and liver cirrhosis in a chinese han population with chronic hepatitis B

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.

Association between PNPLA3 gene polymorphisms and risk of hepatitis B virus-related hepatocellular carcinoma in Han population in China:a case-control study

BACKGROUND AND AIM

Several recent studies showed that the genetic polymorphisms in the PNPLA3 region (rs738408, rs738409, rs2294918, rs2294919 and rs2281135) were with related to various kinds of liver diseases. We analyzed the five single-nucleotide polymorphisms (SNPs) for major HBV outcomes in Han Chinese.

METHODS

A total of 2410 samples were involved and peripheral blood samples were collected in this study. The SNPs in the PNPLA3 region were genotyped by using Matrix-assisted laser desorption/ionization time of flight mass spectrometry.

RESULTS

Our study indicated the clear relationship between the PNPLA3 rs2294918, rs2294919 and HBV-related HCC after control for the effects of sex, drinking and smoking. Health subjects with the PNPLA3 rs2294919 TC genotype would have a 0.605 (95% CI: 0.413, 0.886; p = .010) times lower odds of having HCC, and those with the rs2294918 AG genotype would have a 1.872 (95% CI: 1.256, 2.792; p = .002) times higher odds of having HCC, whereas the values of sex, age, drinking and smoking were fixed. In addition, CA haplotype of the haplotype block of rs738409 and rs2281135 was also associated with HBV-related HCC.

CONCLUSIONS

Our study suggested that PNPLA3 loci (rs2294918, rs2294919) were associated with HBV-related HCC in Han Chinese.

Concurrent fatty liver increases risk of hepatocellular carcinoma among patients with chronic hepatitis B

BACKGROUND AND AIMS

Concurrent fatty liver in hepatitis B virus (HBV)-infected patients without significant alcohol intake is a frequent and increasingly alarming problem because of the non-alcoholic fatty liver disease pandemic. The risk of HBV-related hepatocellular carcinoma (HCC) development was increased by concomitant obesity and diabetes. Direct evidence of the hepatocarcinogenic effect of fatty liver in chronic HBV remains elusive. We aimed to evaluate the risk of concurrent histologically proven fatty liver in HBV hepatocarcinogenesis.

METHODS

We conducted a retrospective cohort study on a liver biopsy cohort of HBV-infected patients without significant alcohol intake to evaluate the prevalence of concurrent histologically proven fatty liver and its association with subsequent HCC development. We also examined nine polymorphisms on six non-alcoholic fatty liver disease-related candidate genes (ADIPOQ, APOC3, GCKR, LEPR, PNPLA3, and PPARG).

RESULTS

Among 270 HBV-infected patients, concurrent fatty liver was found in 107 patients (39.6%) and was associated with metabolic risks, cirrhosis (P = 0.016) and PNPLA3 rs738409 CG/GG genotype (P = 0.002). At a median follow-up of 79.9 months, 11 patients (4.1%) developed HCC, and nine of them had concurrent fatty liver. By multivariable Cox analysis, concurrent fatty liver (HR 7.27, 95% confidence interval: 1.52-34.76; P = 0.013), age, cirrhosis, and APOC3 rs2854116 TC/CC genotype (HR 3.93, 95% confidence interval: 1.30-11.84; P = 0.013) were independent factors predicting HCC development.

CONCLUSIONS

Concurrent fatty liver is common in HBV-infected patients and an independent risk factor potentiating HBV-associated HCC development by 7.3-fold. The risk of HBV-related HCC is increased by APOC3 gene polymorphism, and further characterization is required by its role.

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.

Insights from Genome-Wide Association Analyses of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is caused by hepatic steatosis, which can progress to nonalcoholic steatohepatitis, fibrosis/cirrhosis, and hepatocellular carcinoma in the absence of excessive alcohol consumption. Nonalcoholic fatty liver disease will become the number one cause of liver disease worldwide by 2020. Nonalcoholic fatty liver disease is correlated albeit imperfectly with obesity and other metabolic diseases such as diabetes, hyperlipidemia, and cardiovascular disease, but exactly how having one of these diseases contributes to the development of other metabolic diseases is only now being elucidated. Development of NAFLD and related metabolic diseases is genetically influenced in the population, and recent genome-wide association studies (GWASs) have discovered genetic variants that associate with these diseases. These GWAS-associated variants cannot only help us to identify individuals at high risk of developing NAFLD, but also to better understand its pathophysiology so that we can develop more effective treatments for this disease and related metabolic diseases in the future.

Patatin-Like Phospholipase Domain-Containing 3 I148M Variant Is Associated with Liver Steatosis and Fat Distribution in Chronic Hepatitis B

BACKGROUND

The patatin-like phospholipase domain-containing 3 gene (PNPLA3) has been associated with liver steatosis and disease progression in nonalcoholic steatohepatitis and chronic hepatitis C.

AIMS

The aim of the present study was to evaluate the influence of the PNPLA3 I148M polymorphisms on the clinical, histological, viral, and host parameters in Italian patients with chronic hepatitis B (CHB).

METHODS

Ninety-nine patients with CHB entered the study and underwent a clinical, histological, virological, and biochemical evaluation. PNPLA3 (p.I148M) variants were genotyped.

RESULTS

PNPLA3 rare variant (148M) was significantly associated with liver steatosis (p = 0.0019) and cholesterol (p = 0.04) levels, but not with fibrosis or histological activity index. The 13 patients with severe liver steatosis (score > 3) (38%) were more frequently homozygous for PNPLA3 148M variant than the 86 without (6%, p = 0.003). At logistic regression analysis, severe steatosis was independently associated with the rare allele (p = 0.001) and waist circumference, but not with body mass index (BMI).

CONCLUSIONS

In our CHB patients, the PNPLA3 polymorphisms influenced the development of liver steatosis, but not fibrosis status. The association of PNPLA3 p.I148M with liver steatosis increased with the greater amount of abdominal fat, irrespective of BMI.

Association between patain-like phospholipase domain-containing protein 3 rs738409(C>G) single nucleotide polymorphism and etiology of liver cirrhosis in a Chinese Han population

AIM: To determine whether patain-like phospholipase domain-containing protein 3 (PNPLA3) rs738409 single nucleotide polymorphism (SNP) affects the severity of hepatic damage, susceptibility and prognosis of liver cirrhosis with various liver diseases.

METHODS: We enrolled 224 Chinese Han patients diagnosed with liver cirrhosis, of whom 88 had hepatitis B virus (HBV)-related cirrhosis, 83 had alcoholic liver cirrhosis and 53 had hepatitis C virus (HCV)-related cirrhosis. Two hundred healthy volunteers were enrolled as a control group. TaqMan genotyping assay was used to investigate the association of PNPLA3 SNPs (rs738409) with the risk of liver cirrhosis.

RESULTS: The G allele of the PNPLA3 I148M variant was significantly different between alcoholic liver cirrhosis and the control (OR = 1.902, P < 0.001), and was associated with HBV-related liver cirrhosis (OR = 1.452, P = 0.047). There was no significant association between PNPLA3 rs738409 genotype and HCV-related cirrhosis (P = 0.056). There was no correlation between PNPLA3 rs738409 genotype and liver cirrhosis with hepatocellular carcinoma (P = 0.965).

CONCLUSION: PNPLA3 rs738409 C > G is associated with alcoholic liver cirrhosis and HBV-related liver cirrhosis in a Chinese Han population.

Association of PNPLA3 I148M Variant With Chronic Viral Hepatitis, Autoimmune Liver Diseases and Outcomes of Liver Transplantation

CONTEXT

The PNPLA3 I148M variant has been recognized as a genetic determinant of liver fat content and a genetic risk factor of liver damage progression associated with steatohepatitis. The I148M variant is associated with many chronic liver diseases. However, its potential association with inflammatory and autoimmune liver diseases has not been established.

EVIDENCE ACQUISITION

We systemically reviewed the potential associations of I148M variant with chronic viral hepatitis, autoimmune liver diseases and the outcome of liver transplantation, explored the underlying molecular mechanisms and tried to translate them into more individualized decision-making and personalized medicine.

RESULTS

There were associations between I148M variant and chronic viral hepatitis and autoimmune liver diseases and differential associations of I148M variant in donors and recipients with post-liver transplant outcomes. I148M variant may activate the development of steatosis caused by host metabolic disorders in chronic viral hepatitis, but few researches were found to illustrate the mechanisms in autoimmune liver diseases. The peripherally mediated mechanism (via extrahepatic adipose tissue) may play a principal role in triglyceride accumulation regardless of adiponutrin activity in the graft liver.

CONCLUSIONS

Evidences have shown the associations between I148M variant and mentioned diseases. I148M variant induced steatosis may be involved in the mechanism of chronic viral hepatitis and genetic considered personalized therapies, especially for PSC male patients. It is also crucial to pay attention to this parameter in donor selection and prognosis estimation in liver transplantation.