Distinct, alcohol-modulated effects of PNPLA3 genotype on progression of chronic hepatitis C

Interaction Between Alcohol Consumption and PNPLA3 Variant in the Prevalence of Hepatic Steatosis in the US Population

BACKGROUND & AIMS

To our knowledge, the interaction between alcohol consumption and PNPLA3 genotype on hepatic steatosis has not been explored in a representative sample. To examine the interaction between alcohol consumption and PNPLA3 genotype on hepatic steatosis in the US adult population.

METHODS

Cross-sectional study of 4,674 adult participants of the Third National Health and Nutrition Examination Survey, Phase 2 (1991-1994) with data on PNPLA3 genotype, self-reported alcohol consumption, ultrasound-defined hepatic steatosis and socio-demographic characteristics.

RESULTS

In 1991-1994 in the U.S. population, the weighted allele frequency of the G (risk) allele of the rs738409 at PNPLA3 was 25.4%. We confirmed both a J shaped association between alcohol consumption and hepatic steatosis among those with the CC genotype of PNPLA3, and a higher prevalence of hepatic steatosis among those with PNPLA3 gene G variant. We found evidence of an interaction of PNPLA3 G allele presence on the association between moderate alcohol consumption and hepatic steatosis on both the multiplicative (relative prevalence ratio [RPR]=1.95, 95% confidence interval [CI] 1.04-3.65) and additive scales (relative excess risk due to interaction=0.49, 95% CI 0.13-0.85). Compared to never drinkers, moderate alcohol drinking was associated with a 48% decreased risk of hepatic steatosis only among those without PNPLA3 G allele (PR=0.52, 95% CI 0.26-1.05), with no association among those with at least one copy of the PNPLA3 G allele (PR=1.02, 95% CI 0.68-1.54).

CONCLUSIONS

Our results suggest that a highly common and strong genetic susceptibility to liver disease is modifiable by the level of alcohol consumption. Keeping alcohol consumption low may offset genetic predisposition to liver disease.

PNPLA3 gene and kidney disease

Chronic kidney disease (CKD) is a disease regularly seen in clinical practice. At present, CKD is described as a change of kidney structure and/or function and it is classified in relation to cause, values of glomerular filtration rate and albuminuria category. Seeing that CKD is closely linked to the development of end-stage renal disease and other comorbidities, the determination of additional independent predictors for CKD is clinically necessary. At present, there is evidence associating non-alcoholic fatty liver disease (NAFLD) with CKD, thereby suggesting that NAFLD patients may require intensive surveillance to reduce their risk of CKD. In 2008, genome-wide association studies documented an association between the variant rs738409 (C > G p.I148M) in the patatin-like phospholipase domain containing 3 (PNPLA3) gene (mainly implicated in the lipid regulation) and the entire spectrum of NAFLD (i.e., liver steatosis, non-alcoholic steatohepatitis, fibrosis, and hepatocellular carcinoma). In the last years, accumulating epidemiological evidence suggests the existence of a relationship between PNPLA3 rs738409 and risk of CKD, indicating that rs738409 may also contribute to the kidney injury. This is of particular scientific interest, as such association may explain, at least in part, the epidemiological association between liver and kidney disease. In this narrative review, we will discuss the accumulating evidence regarding the association between PNPLA3 rs738409 and risk of CKD, the putative biological mechanisms underpinning such relationship, and the possible future perspective.

Patatin-like phospholipase domain-containing protein 3 (PNPLA3): A potential role in the association between liver disease and bipolar disorder

OBJECTIVE

Due to the increased prevalence of liver disease in patients with bipolar disorder, we examined the potential role of the patatin-like phospholipase domain-containing protein 3 (PNPLA3) variant among individuals with bipolar disorder and those with no mood disorder.

METHODS

We used the National Health and Nutrition Examination Survey (NHANES) database (aged 15-39 years) to identify a group of individuals with a bipolar diagnosis and a control group of individuals with no mood disorder. A total of 1931 individuals were randomly selected, one from each family containing information on the PNPLA3 genotype to be used in the analysis.

RESULTS

Analyses revealed individuals with the recessive variant genotype (MM) had an adjusted odds ratio for bipolar disorder of about 4.6 compared to individuals with either IM or II genotypes of the PNPLA3 variant.

LIMITATIONS AND CONCLUSIONS

Limitations of this study include the use of a lay-administered survey in for diagnosis of bipolar disorder in NHANES. The association between the PNPLA3 variant and bipolar disorder may help guide further work on medication effectiveness, treatment options, prevention approaches, and understanding potential medication side effects among specific subgroups of individuals with the MM genotype.

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.

A Variant in PNPLA3 Associated With Fibrosis Progression but not Hepatocellular Carcinoma in Patients With Hepatitis C Virus Infection

BACKGROUND & AIMS

A single nucleotide polymorphism (SNP) in the patatin-like phospholipase domain containing 3 gene (PNPLA3, rs738409) has been associated with fibrosis and development of hepatocellular carcinoma (HCC) in patients with nonalcoholic steatohepatitis, although its association with outcomes in patients with hepatitis C virus (HCV) infection is less clear. We evaluated the association between this SNP in PNPLA3 and fibrosis progression and development of HCC among HCV-infected patients.

METHODS

We performed a secondary analysis of data from participants in the Hepatitis C Antiviral Long-Term Treatment against Cirrhosis (HALT-C) trial. Patients were randomly assigned to groups given weekly pegylated interferon or no further therapy for 3.5 y and then followed without further treatment until October 2009. Multivariate logistic regression was used to identify factors associated with fibrosis at baseline, fibrosis progression (defined as 2-point increase in Ishak score), and HCC development.

RESULTS

Among 937 HCV patients with known PNPLA3 genotype, 384 (41.0%) had cirrhosis at baseline. The PNPLA3 CG/GG SNP at rs738409 was significantly associated with the presence of cirrhosis (odds ratio [OR], 1.76; 95% confidence interval [CI], 1.34-2.30), after adjusting for age, sex, diabetes, and race. Among 493 patients without cirrhosis at baseline who had at least 1 follow-up biopsy, 142 had fibrosis progression. In multivariate analyses, fibrosis progression was associated with obesity (OR, 1.67; 95% CI, 1.11-2.51) and the PNPLA3 CG/GG genotype (OR, 1.70; 95% CI, 1.13-2.56). PNPLA3 genotype was not associated with HCC development (P = .85). Using these data to update prior meta-analysis results, the rs738409 SNP in PNPLA3 was not significantly associated with development of HCC in HCV-infected patients (OR 1.29; 95% CI, 0.97-1.99).

CONCLUSIONS

Based on data from the HALT-C trial, the PNPLA3 CG/GG SNP at rs738409 is associated with fibrosis progression but not development of HCC in patients with HCV infection.

Alcoholic liver disease and hepatitis C virus infection

Alcohol consumption and hepatitis C virus (HCV) infection have a synergic hepatotoxic effect, and the coexistence of these factors increases the risk of advanced liver disease. The main mechanisms of this effect are increased viral replication and altered immune response, although genetic predisposition may also play an important role. Traditionally, HCV prevalence has been considered to be higher (up to 50%) in alcoholic patients than in the general population. However, the presence of advanced alcoholic liver disease (ALD) or intravenous drug use (IDU) may have confounded the results of previous studies, and the real prevalence of HCV infection in alcoholic patients without ALD or prior IDU has been shown to be lower. Due to the toxic combined effect of HCV and alcohol, patients with HCV infection should be screened for excessive ethanol intake. Patients starting treatment for HCV infection should be specifically advised to stop or reduce alcohol consumption because of its potential impact on treatment efficacy and adherence and may benefit from additional support during antiviral therapy. This recommendation might be extended to all currently recommended drugs for HCV treatment. Patients with alcohol dependence and HCV infection, can be treated with acamprosate, nalmefene, topiramate, and disulfiram, although baclofen is the only drug specifically tested for this purpose in patients with ALD and/or HCV infection.

Alcoholic liver disease and hepatitis C virus infection

Alcohol consumption and hepatitis C virus (HCV) infection have a synergic hepatotoxic effect, and the coexistence of these factors increases the risk of advanced liver disease. The main mechanisms of this effect are increased viral replication and altered immune response, although genetic predisposition may also play an important role. Traditionally, HCV prevalence has been considered to be higher (up to 50%) in alcoholic patients than in the general population. However, the presence of advanced alcoholic liver disease (ALD) or intravenous drug use (IDU) may have confounded the results of previous studies, and the real prevalence of HCV infection in alcoholic patients without ALD or prior IDU has been shown to be lower. Due to the toxic combined effect of HCV and alcohol, patients with HCV infection should be screened for excessive ethanol intake. Patients starting treatment for HCV infection should be specifically advised to stop or reduce alcohol consumption because of its potential impact on treatment efficacy and adherence and may benefit from additional support during antiviral therapy. This recommendation might be extended to all currently recommended drugs for HCV treatment. Patients with alcohol dependence and HCV infection, can be treated with acamprosate, nalmefene, topiramate, and disulfiram, although baclofen is the only drug specifically tested for this purpose in patients with ALD and/or HCV infection.

Effect of PNPLA3 rs738409 variant (I148 M) on hepatic steatosis, necroinflammation, and fibrosis in Japanese patients with chronic hepatitis C

BACKGROUND

Host genetic factors have been suspected to influence histological liver damage in chronic liver disease. The nonsynonymous single-nucleotide polymorphism rs738409 C > G in the patatin-like phospholipase domain-containing 3 gene (PNPLA3, also known as adiponutrin), encoding the I148 M protein variant, has been identified as a novel genetic marker for hepatic steatosis and fibrosis in nonalcoholic fatty liver disease and alcoholic liver disease. We aimed to determine whether the PNPLA3 rs738409 variant was associated with hepatic steatosis, necroinflammation, and fibrosis in Japanese patients with chronic hepatitis C.

METHODS

In a cross-sectional study in Japan, we analyzed 276 patients with chronic hepatitis C who underwent liver biopsy. Genotyping for rs738409 was performed using the TaqMan genotyping assay.

RESULTS

The frequencies of the rs738409 CC, CG, and GG genotypes were 32.6, 46.4, and 21.0 %, respectively. Multivariate analysis revealed that the GG genotype was independently associated with the presence of steatosis [odds ratio (OR) 2.58, 95 % confidence interval (CI) 1.37-4.84, p = 0.003], severe necroinflammatory activity (OR 2.16, 95 % CI 1.12-4.16, p = 0.02), and advanced fibrosis (OR 2.10, 95 % CI 1.07-4.11, p = 0.03), after adjustment for age, sex, body mass index, and diabetes.

CONCLUSIONS

The PNPLA3 rs738409 variant influences histological liver damage in Japanese patients with chronic hepatitis C. The G allele homozygotes are at higher risk for hepatic steatosis, severe necroinflammation, and advanced fibrosis.

Association of diabetes and PNPLA3 genetic variants with disease severity of patients with chronic hepatitis C virus infection

BACKGROUND & AIMS

Genetic variants of patatin-like phospholipase domain-containing 3 (PNPLA3) and diabetes are associated with liver disease severity, in patients with chronic hepatitis C (CHC) infection. We aimed at exploring their interaction in determining hepatitis C virus (HCV)-related liver fibrosis.

METHODS

The PNPLA3 genetic polymorphism at rs738409 was verified in 1077 biopsy-proven CHC patients. Other clinical variables, including diabetes status, were analysed for factors associated with bridging fibrosis.

RESULTS

Patients with advanced liver fibrosis had higher proportions of the GG genotype (14.5% vs. 10.4%, p=0.06 in recessive model) and GG/GC genotype carriage (64.0% vs. 56.8%, p=0.03 in dominant model). Stepwise logistic regression analysis revealed that factors predictive of advanced liver fibrosis included age (odds ratio [OR]: 1.02, 95% confidence intervals [CI]: 1.008-1.037, p=0.002), diabetes (OR: 1.81, CI: 1.236-2.653, p=0.002), α-fetoprotein (OR: 1.006, CI: 1.001-1.01, p=0.01), platelet counts (OR: 1.009, CI: 1.006-1.012, p<0.001), and PNPLA3 rs738409 CG/GG genotype (OR: 1.34, CI: 1.006-1.785, p=0.046). When patients were grouped according to their diabetes status, the PNPLA3 genetic variants were associated with advanced liver fibrosis in diabetic patients only, but not in non-diabetic patients. The PNPLA3 gene was the most important predictive factor of bridging fibrosis in diabetic patients, using the recessive model (OR: 4.53, CI: 1.356-15.106, p=0.014) or the dominant model (OR: 2.20, CI: 1.026-4.734, p=0.04). Compared to non-diabetic patients, patients with the diabetes/GG genotype were more likely to have advanced liver fibrosis (OR: 8.79, CI: 2.889-26.719, p<0.001), followed by those with diabetes/non-GG genotype (OR: 1.55, CI: 1.048-2.286, p=0.03).

CONCLUSIONS

The effect of PNPLA3 genetic variants in HCV-related advanced liver fibrosis was enhanced in diabetic patients. The strong genetic-environmental interaction contributed to the high risk of advanced liver disease in CHC patients.

Insulin resistance and steatosis in HBV-HCV co-infected patients: Role of PNPLA3 polymorphisms and impact on liver fibrosis progression

AIM: To evaluate steatosis, insulin resistance (IR) and patatin-like phospholipase domain-containing 3 (PNPLA3) and their relation to disease progression in hepatitis B and C viruses (HCV-HBV) co-infected patients.

METHODS: Three hundred and thirty patients with biopsy proven chronic hepatitis were enrolled: 66 had HBV-HCV, 66 HBV and 198 HCV infection. Prevalence of steatosis, IR and PNPLA3 polymorphisms and their relation to anthropometric, biochemical, virological and histological parameters were evaluated.

RESULTS: Prevalence of steatosis in group HBV-HCV was similar to that in HCV (47.0% vs 49.5%, respectively); group HBV showed the lowest steatosis (33.3%). Group HBV-HCV had a lesser degree of steatosis than HCV (P = 0.016), lower HCV RNA levels (P = 0.025) and lower prevalence and degree of IR (P = 0.01). PNPLA3 polymorphisms were associated with steatosis. Group HBV-HCV showed higher levels of liver fibrosis than group HCV (P = 0.001), but similar to that observed in HBV group. In HBV-HCV group, liver fibrosis was not associated with steatosis, IR or PNPLA3. HBV infection was the independent predictor of advanced liver fibrosis.

CONCLUSION: HBV-HCV co-infected patients have lower degree of hepatic steatosis, IR and HCV RNA than HCV mono-infected; co-infected patients showed a more rapid liver fibrosis progression that seems to be due to the double infection and/or HBV dominance.

Interaction between PNPLA3 I148M variant and age at infection in determining fibrosis progression in chronic hepatitis C

Background and Aims

The PNPLA3 I148M sequence variant favors hepatic lipid accumulation and confers susceptibility to hepatic fibrosis and hepatocellular carcinoma. The aim of this study was to estimate the effect size of homozygosity for the PNPLA3 I148M variant (148M/M) on the fibrosis progression rate (FPR) and the interaction with age at infection in chronic hepatitis C (CHC).

Methods

FPR was estimated in a prospective cohort of 247 CHC patients without alcohol intake and diabetes, with careful estimation of age at infection and determination of fibrosis stage by Ishak score.

Results

Older age at infection was the strongest determinant of FPR (p<0.0001). PNPLA3 148M/M was associated with faster FPR in individuals infected at older age (above the median, 21 years; −0.64±0.2, n = 8 vs. −0.95±0.3, n = 166 log₁₀ FPR respectively; p = 0.001; confirmed for lower age thresholds, p<0.05), but not in those infected at younger age (p = ns). The negative impact of PNPLA3 148M/M on fibrosis progression was more marked in subjects at risk of altered hepatic lipid metabolism (those with grade 2–3 steatosis, genotype 3, and overweight; p<0.05). At multivariate analysis, PNPLA3 148M/M was associated with FPR (incremental effect 0.08±0.03 log₁₀ fibrosis unit per year; p = 0.022), independently of several confounders, and there was a significant interaction between 148M/M and older age at infection (p = 0.025). The association between 148M/M and FPR remained significant even after adjustment for steatosis severity (p = 0.032).

Conclusions

We observed an interaction between homozygosity for the PNPLA3 I148M variant and age at infection in determining fibrosis progression in CHC patients.

Role of FDFT1 polymorphism for fibrosis progression in patients with chronic hepatitis C

BACKGROUND

In chronic hepatitis C (CHC), steatosis is associated with fibrosis and impaired response to antiviral therapy. Recently, a polymorphism of single nucleotide polymorphism SNP rs2645424 of farnesyl diphosphate farnesyl transferase 1 (FDFT1) was identified in NAFLD/NASH as a possible causal link to steatosis and fibrosis progression. SNP rs738409 in the adiponutrin gene (PNPLA3) is a well described factor for steatosis. This study evaluated the relation of these SNPs on steatosis, fibrosis and treatment response in CHC.

METHODS

The SNPs rs738409478 and rs2645424 were determined by real-time PCR in 478 patients with CHC (m/f: 314/164; mean age: 44.9 ± 10.7; GT1: 387, GT4: 91) who completed treatment with peg-IFN-α-2a/ribavirin. All had a pretreatment liver biopsy. Steatosis and fibrosis were graded by board-certified pathologists according to Brunt and METAVIR respectively.

RESULTS

The distribution of FDFT1 rs2645424 was GG: 186 (38.9%), AG: 222 (46.4%) and AA: 70 (14.6%) and of the rs738409 PNPLA3 allele: CC: 269 (56.3%), CG: 177 (37.0%) and GG: 32 (6.7%). Overall, FDTF1 polymorphism was not linked to the extent of steatosis or fibrosis. However, in patients without steatosis the AA genotype was associated with advanced fibrosis [AA: 8/20 (40.0%), AG: 6/70 (8.5%), GG: 9/57 (16.1%), P = 0.003]. In contrast, the minor PNPLA3 allele was associated with both steatosis and advanced fibrosis (P < 0.001). Both SNPs did not influence treatment response.

CONCLUSION

The minor allele in FDFT1 was associated with advanced fibrosis in the non-steatotic but not in the steatotic subgroup. This may reflect different metabolic pathways in fibrosis progression for steatotic and non-steatotic patients with CHC.

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 and progressive liver disease

The 148 Isoleucine to Methionine protein variant (I148M) of patatin-like phospholipase domain-containing 3 (PNPLA3), a protein is expressed in the liver and is involved in lipid metabolism, has recently been identified as a major determinant of liver fat content. Several studies confirmed that the I148M variant predisposes towards the full spectrum of liver damage associated with fatty liver: from simple steatosis to steatohepatitis and progressive fibrosis. Furthermore, the I148M variant represents a major determinant of progression of alcohol related steatohepatitis to cirrhosis, and to influence fibrogenesis and related clinical outcomes in chronic hepatitis C virus hepatitis, and possibly chronic hepatitis B virus hepatitis, hereditary hemochromatosis and primary sclerosing cholangitis. All in all, studies suggest that the I148M polymorphism may represent a general modifier of fibrogenesis in liver diseases. Remarkably, the effect of the I148M variant on fibrosis was independent of that on hepatic steatosis and inflammation, suggesting that it may affect both the quantity and quality of hepatic lipids and the biology of non-parenchymal liver cells besides hepatocytes, directly promoting fibrogenesis. Therefore, PNPLA3 is a key player in liver disease progression. Assessment of the I148M polymorphism will possibly inform clinical practice in the future, whereas the determination of the effect of the 148M variant will reveal mechanisms involved in hepatic fibrogenesis.

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.

Patatin-like phospholipase domain-containing 3 I148M affects liver steatosis in patients with chronic hepatitis B

Steatosis is a common histopathological feature of chronic hepatitis B (CHB) and has been associated with severity of liver disease. Recently, the rs738409 I148M patatin-like phospholipase domain-containing 3 (PNPLA3) polymorphism has been demonstrated to influence steatosis susceptibility and fibrosis progression in patients with different liver diseases, but no data are yet available for CHB. The aim of this study was to evaluate whether PNPLA3 I148M influences steatosis susceptibility in a large series of patients with CHB. We enrolled 235 treatment-naïve CHB patients consecutively examined by percutaneous liver biopsy. In ≥2-cm-long liver tissue cores, steatosis and fibrosis were staged by Kleiner and METAVIR scores, respectively. The I148M polymorphism was determined by Taqman assays. Steatosis was present in 146 (62%) patients, of whom 24 (10%) had severe (>33% of hepatocytes) steatosis. Steatosis was independently associated with age (odds ratio [OR]: 2.67; confidence interval [CI]: 1.50-4.92; for age ≥50 years), body mass index (BMI; OR, 2.84; CI, 1.30-6.76; for BMI ≥27.5 kg/m(2) ), diabetes or impaired fasting glucose (OR, 4.45; CI, 1.10-30.0), and PNPLA3 148M allele (OR, 1.62; CI, 1.00-7.00; for each 148M allele). Independent predictors of severe steatosis were BMI (OR, 3.60; CI, 1.39-9.22; for BMI ≥27.5 kg/m(2) ) and PNPLA3 148M allele (OR, 6.03; CI, 1.23-5.0; for each 148M allele). PNPLA3 148M alleles were associated with a progressive increase in severe steatosis in patients with acquired cofactors, such severe overweight and a history of alcohol intake (P = 0.005).

CONCLUSION

In CHB patients, the PNPLA3 I148M polymorphism influences susceptibility to steatosis and, in particular, when associated with severe overweight and alcohol intake, severe steatosis.

Abdominal fat interacts with PNPLA3 I148M, but not with the APOC3 variant in the pathogenesis of liver steatosis in chronic hepatitis C

The patatin-like phospholipase domain-containing 3 gene (PNPLA3) and the apolipoprotein C3 gene (APOC3) have been studied in relation to liver steatosis and liver disease outcome. The aim of this study was to evaluate the influence of PNPLA3 p.I148M and APOC3 rs2854116 and rs2854117 polymorphisms on the clinical and histological presentation of chronic hepatitis C in an Italian population and their relationship with viral and anthropometric parameters. Patients with hepatitis C (n = 166) entered the study receiving a clinical, histological, virological and biochemical evaluation. APOC3 (rs2854116 and rs2854117) and PNPLA3 (p.I148M) variants were genotyped. PNPLA3 polymorphisms were associated with liver steatosis, which was significantly higher in patients with p.148I/M (P = 0.034) and p.148M/M (P = 0.004) variants than those homozygous for the PNPLA3 wild type. Excluding patients with HCV genotype 3, the association with liver steatosis and PNPLA3 variants was more marked (p.148I/I genotype vs p.148I/M, P = 0.02, and vs p.148M/M, P = 0.005). The APOC3 polymorphism was not associated with any of the evaluated parameters. Among the interacting factors, BMI and waist circumference correlated with liver steatosis (P = 0.008 and 0.004, respectively). Relationship between waist circumference and liver steatosis was analysed for the different PNPLA3 genotypes. Homozygous 148M patients showed a stronger correlation between waist circumference and steatosis than those carrying the other genotypes (P = 0.0047). In our hepatitis C-infected population, the PNPLA3 polymorphism influenced the development of liver steatosis, but not fibrosis progression. APOC3 polymorphisms had no effect on the development of steatosis and no influence on the PNPLA3 polymorphism. The amount of abdominal fat can increase the association of PNPLA3 p.I148M with liver steatosis.

Implications of PNPLA3 polymorphism in chronic hepatitis C patients receiving peginterferon plus ribavirin

BACKGROUND

Homozygosity for the PNPLA3 p.I148M polymorphism influences steatosis and fibrogenesis in chronic hepatitis C (CHC).

AIM

To evaluate the effect of p.148M/M on sustained virological response (SVR) and viral kinetics in patients who underwent antiviral therapy with peg-interferon and ribavirin, stratified according to viral genotype and fibrosis severity, and secondarily, the interaction with interleukin-28B ( IL28B ) genotype on liver damage.

METHODS

In this observational study, we considered 602 treatment-naïve consecutive patients from tertiary referral centres in Milan and Vienna [61% genotype 1 (G1), 30% advanced fibrosis, 33% IL28B rs12979860 CC].

RESULTS

The p.148M/M genotype, detected in 8% of patients, did not influence SVR in the overall series (P = 0.29), but it was associated with SVR (3/17, 17% vs. 56/121, 46%; P = 0.034) and complete early viral response (4/17, 23% vs. 68/121, 56%; P = 0.018) in G1/4 patients with advanced fibrosis. After adjustment for age, viral load, IL28B CC genotype, treatment dose, and steatosis, p.148M/M remained a predictor of SVR in G1/4 patients with advanced fibrosis (OR 0.23, 95% CI 0.04-0.87). The p.148M/M genotype was associated with more advanced fibrosis in the overall series (P = 0.049), whereas the rs12979860 IL28B CC genotype only in patients negative for p.148M/M (P = 0.017), independently of age, BMI and alanine transaminase levels (OR 1.51, 95% CI 1.01-2.27).

CONCLUSIONS

PNPLA3 p.148M/M genotype was negatively associated with SVR and early viral kinetics independently of steatosis, albeit only in difficult-to-cure G1/4 patients with advanced fibrosis, whereas stratification for the p.148M/M PNPLA3 genotype unmasked an association between IL28B CC genotype and more severe liver fibrosis.

A common variant of PNPLA3 (p.I148M) is not associated with alcoholic chronic pancreatitis

Background

Chronic pancreatitis (CP) is an inflammatory disease that in some patients leads to exocrine and endocrine dysfunction. In industrialized countries the most common aetiology is chronic alcohol abuse. Descriptions of associated genetic alterations in alcoholic CP are rare. However, a common PNPLA3 variant (p.I148M) is associated with the development of alcoholic liver cirrhosis (ALC). Since, alcoholic CP and ALC share the same aetiology PNPLA3 variant (p.I148M) possibly influences the development of alcoholic CP.

Methods

Using melting curve analysis we genotyped the variant in 1510 patients with pancreatitis or liver disease (961 German and Dutch alcoholic CP patients, 414 German patients with idiopathic or hereditary CP, and 135 patients with ALC). In addition, we included in total 2781 healthy controls in the study.

Results

The previously published overrepresentation of GG-genotype was replicated in our cohort of ALC (p-value <0.0001, OR 2.3, 95% CI 1.6–3.3). Distributions of genotype and allele frequencies of the p.I148M variant were comparable in patients with alcoholic CP, idiopathic and hereditary CP and in healthy controls.

Conclusions

The absence of an association of PNPLA3 p.I148M with alcoholic CP seems not to point to a common pathway in the development of alcoholic CP and alcoholic liver cirrhosis.

IL28B, HCV core mutations, and hepatocellular carcinoma: does host genetic make-up shape viral evolution in response to immunity?

Mutations in the core sequence of the HCV genome have been reported to influence treatment response, fibrosis progression, and hepatocarcinogenesis in Asian patients with genotype-1 chronic hepatitis C (CHC). In this issue, Miura et al. report data consistent with a causal relationship between the R70 → Q70 core variant and hepatocellular carcinoma (HCC) risk in CHC genotype-1b patients, by the prospective evaluation of changes in the consensus sequence in the entire open reading frame between treatment failure and HCC development or end of follow-up, and validation of the initial findings in a confirmatory cohort. Furthermore, they observed an association between the IL28B genotype, which is believed to influence the immune response to viral infection, and the direction of time-dependent changes in core residue 70, with unfavorable IL28B genotypes linked to a preferential shift to the 70Q associated with HCC. Although this association needs to be validated in independent cohorts, and IL28B variants did not influence HCC risk, these results suggest that IL28B genotype might not only influence the behavior of the innate immune system in the presence of HCV genotype-1 infection but also shape the resultant viral evolution, with possible consequences on major clinical outcomes, such as HCC development, and treatment response.

Impact of patatin-like phospholipase-3 (rs738409 C>G) polymorphism on fibrosis progression and steatosis in chronic hepatitis C

Only 20% of patients with chronic hepatitis C (CHC) will develop cirrhosis, and fibrosis progression remains highly unpredictable. A recent genome-wide association study identified a genetic variant in the patatin-like phospholipase-3 (PNPLA3) gene (rs738409 C>G) associated with steatosis that was further demonstrated to influence severity of fibrosis in nonalcoholic fatty liver disease. The aim of this study was to assess the impact of this polymorphism on histological liver damage and response to antiviral therapy in CHC. We recruited 537 Caucasian CHC patients from three European centers (Brussels, Belgium [n = 229]; Hannover, Germany [n = 171]; Lyon, France [n = 137]); these patients were centrally genotyped for the PNPLA3 (rs738409 C>G) polymorphism. We studied the influence of rs738409 and other variants in the PNPLA3 region on steatosis and fibrosis assessed both in a cross-sectional and longitudinal manner. Seven other variants previously associated with fibrosis progression were included. Finally, we explored the impact of rs738409 on response to standard antiviral therapy using the interferon lambda 3 (IL28B) [rs12979860 C>T] variant both as a comparator and as a positive control. After adjustment for age, sex, body mass index, alcohol consumption, and diabetes, rs738409 mutant G allele homozygote carriers remained at higher risk for steatosis (odds ratio [OR] 2.55, 95% confidence interval [CI] 1.08-6.03, P = 0.034), fibrosis (OR 3.13, 95% CI 1.50-6.51, P = 0.002), and fibrosis progression (OR 2.64, 95% CI 1.22-5.67, P = 0.013). Conversely, rs738409 was not independently associated with treatment failure (OR 1.07, 95% CI 0.46-2.49, P = 0.875) and did not influence clinical or biological variables.

CONCLUSION

The PNPLA3 (rs738409 C>G) polymorphism favors steatosis and fibrosis progression in CHC. This polymorphism may represent a valuable genetic predictor and a potential therapeutic target in CHC liver damage.