Serum ferritin level is associated with liver fibrosis and incident liver-related outcomes independent of HFE genotype in the general population.

BACKGROUND & AIMS: Hyperferritinemia reflects iron accumulation in the body and has been associated with metabolic disturbances and alcohol use, and is also a common finding in individuals diagnosed with liver disease. The major genetic regulator of iron metabolism is the HFE gene. METHODS: The aim of this this study was to investigate the association between serum ferritin and liver fibrosis using the enhanced liver fibrosis (ELF) test, and the association between ferritin and liver-related outcomes in a Finnish population-based cohort of 6194 individuals (45% male, mean [± standard deviation] age, 52.9 ± 14.9 years; body mass index 26.9 ± 4.7 kg/m2). The effects of HFE variants on these associations were also evaluated. RESULTS: Serum ferritin levels were significantly associated with liver fibrosis, as estimated by enhanced liver fibrosis (ELF) test in weighted linear regression analysis. Serum ferritin was significantly associated with both all liver-related outcomes (n = 92) and severe liver-related outcomes (n = 54) in weighted Cox regression analysis (hazard ratio [HR] per 1 SD, 1.11 [95% confidence interval (CI) 1.02-1.21]; p = 0.012 and HR 1.11 [95% CI 1.02-1.21]; p = 0.013, respectively). However, there was association neither between HFE risk variants and ELF test nor between HFE risk variants and liver-related outcomes. CONCLUSION: Serum ferritin levels were associated with liver fibrosis and incident liver disease, independent of HFE genotype in the general population. Furthermore, data demonstrated that metabolic disturbances and alcohol use were major risk factors for hyperferritinemia.

Attribution of diabetes to the development of severe liver disease in the general population.

BACKGROUND AND AIMS: Diabetes is associated with advanced liver disease and predicts mortality regardless of the primary aetiology of the liver disease. Even a family history of diabetes has been linked to advanced liver fibrosis in non-alcoholic fatty liver disease (NAFLD). However, the fraction of liver-related outcomes in the general population that are attributable to diabetes remains unclear. METHODS: The population attributable fraction (PAF) of diabetes for liver disease as a time-dependent exposure was estimated in the Finnish FINRISK study (n = 28 787) and the British Whitehall II study (n = 7855). We also assessed the predictive ability of a family history of diabetes for liver-related outcomes. Incident diabetes data were from drug purchase/reimbursement and healthcare registries (FINRISK) or follow-up examinations (Whitehall II). Incident severe liver outcomes were identified through linkage with national healthcare registries. RESULTS: Diabetes was associated with a two-fold risk of liver-related outcomes in both the FINRISK (HR, 1.92; p < .001) and Whitehall II (HR, 2.37; p < .001) cohorts, and this remained significant after adjusting for multiple confounders. PAF analyses demonstrated that diabetes explained 12-14% of the risk for severe liver-related outcomes after 10 and 20 years of follow-up. Also, maternal diabetes increased the risk of liver-related outcomes in the FINRISK (HR, 1.43; p = .044) and Whitehall II (HR, 2.04; p = .051) cohorts. CONCLUSION: Approximately 12%-14% of severe liver-related outcomes are attributable to diabetes at the population level. The association between maternal diabetes and liver disease might suggest a mitochondrial genetic mechanism.

Incidence of liver-related morbidity and mortality in a population cohort of non-alcoholic fatty liver disease.

BACKGROUND & AIMS: Non-alcoholic fatty liver disease (NAFLD) increases morbidity and mortality. However, patients in biopsy-based cohorts are highly selected and the absolute risks of liver- and non-liver outcomes in NAFLD in population remains undefined. We analysed both liver-related and non-liver-related outcomes in Finnish population cohorts of NAFLD. METHODS: We included 10 993 individuals (6707 men, mean age 53.3 ± 12.6 years) with NAFLD (fatty liver index ≥60) from the Finnish population-based FINRISK and Health 2000 studies. Liver fibrosis was assessed by the dAAR score, and genetic risk by a recent polygenic risk score (PRS-5). Incident liver-related outcomes, cardiovascular disease (CVD), cancer and chronic kidney disease (CKD) were identified through linkage with national registries. RESULTS: Mean follow-up was 12.1 years (1128 069 person-years). The crude incidence rate of liver-related outcomes in NAFLD was 0.97/1000 person-years. The cumulative incidence increased with age, being respectively 2.4% and 1.5% at 20 years in men and women aged 60 years at baseline, while the relative risks for CVD and cancer were 9-16 times higher. The risk of CKD exceeded that of liver outcomes at a baseline age around 50 years. 20-year cumulative incidence of liver-related outcomes was 4.3% in the high, and 1.5% in the low PRS-5 group. The dAAR score associated with liver outcomes, but not with extra-hepatic outcomes. CONCLUSION: The absolute risk of liver-related outcomes in NAFLD is low, with much higher risk of CVD and cancer, emphasizing the need for more individualized and holistic risk-stratification in NAFLD.

Comprehensive Pharmacogenomic Study Reveals an Important Role of UGT1A3 in Montelukast Pharmacokinetics.

To identify the genetic basis of interindividual variability in montelukast exposure, we determined its pharmacokinetics and sequenced 379 pharmacokinetic genes in 191 healthy volunteers. An intronic single nucleotide variation (SNV), strongly linked with UGT1A3*2, associated with reduced area under the plasma concentration-time curve (AUC0-∞ ) of montelukast (by 18% per copy of the minor allele; P = 1.83 × 10-10 ). UGT1A3*2 was associated with increased AUC0-∞ of montelukast acyl-glucuronide M1 and decreased AUC0-∞ of hydroxymetabolites M5R, M5S, and M6 (P < 10-9 ). Furthermore, SNVs in SLCO1B1 and ABCC9 were associated with the AUC0-∞ of M1 and M5R, respectively. In addition, a candidate gene analysis suggested that CYP2C8 and ABCC9 SNVs also affect the AUC0-∞ of montelukast. The found UGT1A3 and ABCC9 variants associated with increased expression of the respective genes in human liver samples. Montelukast and its hydroxymetabolites were glucuronidated by UGT1A3 in vitro. These results indicate that UGT1A3 plays an important role in montelukast pharmacokinetics, especially in UGT1A3*2 carriers.

Effects of Genetic Variants on Carboxylesterase 1 Gene Expression, and Clopidogrel Pharmacokinetics and Antiplatelet Effects.

Several single nucleotide variations (SNVs) affect carboxylesterase 1 (CES1) activity, but the effects of genetic variants on CES1 gene expression have not been systematically investigated. Therefore, our aim was to investigate effects of genetic variants on CES1 gene expression in two independent whole blood sample cohorts of 192 (discovery) and 88 (replication) healthy volunteers and in a liver sample cohort of 177 patients. Furthermore, we investigated possible effects of the found variants on clopidogrel pharmacokinetics (n = 106) and pharmacodynamics (n = 46) in healthy volunteers, who had ingested a single 300 mg or 600 mg dose of clopidogrel. Using massively parallel sequencing, we discovered two CES1 SNVs, rs12443580 and rs8192935, to be strongly and independently associated with a 39% (p = 4.0 × 10-13 ) and 31% (p = 2.5 × 10-8 ) reduction in CES1 whole blood expression per copy of the minor allele. These findings were replicated in the replication cohort. However, these SNVs did not affect CES1 liver expression, or clopidogrel pharmacokinetics or pharmacodynamics. Conversely, the CES1 c.428G>A missense SNV (rs71647871) impaired the hydrolysis of clopidogrel, increased exposure to clopidogrel active metabolite and enhanced its antiplatelet effects. In conclusion, the rs12443580 and rs8192935 variants reduce CES1 expression in whole blood but not in the liver. These tissue-specific effects may result in substrate-dependent effects of the two SNVs on CES1-mediated drug metabolism.

Ketone body production is differentially altered in steatosis and non-alcoholic steatohepatitis in obese humans.

BACKGROUND & AIMS: Levels of ketone bodies have been reported to be both increased and decreased in individuals with non-alcoholic fatty liver disease. We investigated whether the metabolism of ketone bodies is different in simple steatosis and in non-alcoholic steatohepatitis (NASH). METHODS: Serum low molecular weight molecules including ketone bodies were measured using high-throughput proton (1H) nuclear magnetic resonance in 116 (76 categorized unequivocally to those with normal liver, simple steatosis or NASH) morbidly obese individuals [age 47.3 ± 8.7 (mean ± SD) years, body mass index 45.1 ± 6.1 kg/m(2) , 39 men and 77 women] with histological assessment of NASH and analysis of gene expression in the liver. Finally, we correlated ß-hydroxybutyrate (ß-OHB) levels with NASH predicting score in Metabolic Syndrome in Men Study (METSIM) population study (n = 8749 non-diabetic men). RESULTS: Levels of ketone bodies were lower in individuals with NASH compared to individuals with simple steatosis (P = 0.004 and P = 0.018 for ß-OHB and acetoacetate respectively). Lower levels of ß-OHB were associated with the NASH predicting score in the METSIM study (P = 0.001). Liver inflammation correlated with mRNA expression of genes regulating ketolysis in the liver (Spearman correlation 0.379-0.388, P < 0.0006 for ACAT1, ACSS2 and BDH1). CONCLUSION: Lower levels of ketone bodies in individuals with NASH compared to individuals with simple steatosis suggest a decrease in ketone body metabolism in NASH.

Lipoprotein subclass metabolism in nonalcoholic steatohepatitis.

Nonalcoholic steatohepatitis (NASH) is associated with increased synthesis of triglycerides and cholesterol coupled with increased VLDL synthesis in the liver. In addition, increased cholesterol content in the liver associates with NASH. Here we study the association of lipoprotein subclass metabolism with NASH. To this aim, liver biopsies from 116 morbidly obese individuals [age 47.3 ± 8.7 (mean ± SD) years, BMI 45.1 ± 6.1 kg/m², 39 men and 77 women] were used for histological assessment. Proton NMR spectroscopy was used to measure lipid concentrations of 14 lipoprotein subclasses in native serum samples at baseline and after obesity surgery. We observed that total lipid concentration of VLDL and LDL subclasses, but not HDL subclasses, associated with NASH [false discovery rate (FDR) < 0.1]. More specifically, total lipid and cholesterol concentration of VLDL and LDL subclasses associated with inflammation, fibrosis, and cell injury (FDR < 0.1), independent of steatosis. Cholesterol concentration of all VLDL subclasses also correlated with total and free cholesterol content in the liver. All NASH-related changes in lipoprotein subclasses were reversed by obesity surgery. High total lipid and cholesterol concentration of serum VLDL and LDL subclasses are linked to cholesterol accumulation in the liver and to liver cell injury in NASH.

A population-based study on the prevalence of NASH using scores validated against liver histology.

BACKGROUND & AIMS: Non-alcoholic steatohepatitis (NASH) is a leading cause of chronic liver disease in Western countries. Diagnosis of NASH requires a liver biopsy. We estimated the prevalence of NASH non-invasively in a population-based study using scores validated against liver histology. METHODS: Clinical characteristics, PNPLA3 genotype at rs738409, and serum cytokeratin 18 fragments were measured in 296 consecutive bariatric surgery patients who underwent a liver biopsy to discover and validate a NASH score ('NASH score'). We also defined the cut-off for NASH for a previously validated NAFLD liver fat score to diagnose NASH in the same cohort ('NASH liver fat score'). Both scores were validated in an Italian cohort comprising of 380, mainly non-bariatric surgery patients, who had undergone a liver biopsy for NASH. The cut-offs were utilized in the Finnish population-based D2D-study involving 2849 subjects (age 45-74 years) to estimate the population prevalence of NASH. RESULTS: The final 'NASH Score' model included PNPLA3 genotype, AST and fasting insulin. It predicted NASH with an AUROC 0.774 (0.709, 0.839) in Finns and 0.759 (0.711, 0.807) in Italians (NS). The AUROCs for 'NASH liver fat score' were 0.734 (0.664, 0.805) and 0.737 (0.687, 0.787), respectively. Using 'NASH liver fat score' and 'NASH Score', the prevalences of NASH in the D2D study were 4.2% (95% CI: 3.4, 5.0) and 6.0% (5.0, 6.9%). Sensitivity analysis was performed by taking into account stochastic false-positivity and false-negativity rates in a Bayesian model. This analysis yielded population prevalences of NASH of 3.1% (95% stimulation limits 0.2-6.8%) using 'NASH liver fat score' and 3.6% (0.2-7.7%) using 'NASH Score'. CONCLUSIONS: The population prevalence of NASH in 45-74 year old Finnish subjects is ∼ 5%.