| 1. |
- Dongiovanni, P., et al.
(författare)
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Transmembrane 6 Superfamily Member 2 Gene Variant Disentangles Nonalcoholic Steatohepatitis From Cardiovascular Disease
- 2015
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Ingår i: Hepatology. - : Ovid Technologies (Wolters Kluwer Health). - 0270-9139 .- 1527-3350. ; 61:2, s. 506-514
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Tidskriftsartikel (refereegranskat)abstract
- Excess hepatic storage of triglycerides is considered a benign condition, but nonalcoholic steatohepatitis (NASH) may progress to fibrosis and promote atherosclerosis. Carriers of the TM6SF2 E167K variant have fatty liver as a result of reduced secretion of very-low-density lipoproteins (VLDLs). As a result, they have lower circulating lipids and reduced risk of myocardial infarction. In this study, we aimed to assess whether TM6SF2 E167K affects liver damage and cardiovascular outcomes in subjects at risk of NASH. Liver damage was evaluated in 1,201 patients who underwent liver biopsy for suspected NASH; 427 were evaluated for carotid atherosclerosis. Cardiovascular outcomes were assessed in 1,819 controls from the Swedish Obese Subjects (SOS) cohort. Presence of the inherited TM6SF2 E167K variant was determined by TaqMan assays. In the liver biopsy cohort, 188 subjects (13%) were carriers of the E167K variant. They had lower serum lipid levels than noncarriers (P<0.05), had more-severe steatosis, necroinflammation, ballooning, and fibrosis (P<0.05), and were more likely to have NASH (odds ratio [OR]: 1.84; 95% confidence interval [CI]: 1.23-2.79) and advanced fibrosis (OR, 2.08; 95% CI: 1.20-3.55), after adjustment for age, sex, body mass index, fasting hyperglycemia, and the I148M PNPLA3 risk variant. However, E167K carriers had lower risk of developing carotid plaques (OR, 0.49; 95% CI: 0.25-0.94). In the SOS cohort, E167K carriers had higher alanine aminotransferase ALT and lower lipid levels (P<0.05), as well as a lower incidence of cardiovascular events (hazard ratio: 0.61; 95% CI: 0.39-0.95). Conclusions: Carriers of the TM6SF2 E167K variant are more susceptible to progressive NASH, but are protected against cardiovascular disease. Our findings suggest that reduced ability to export VLDLs is deleterious for the liver. (Hepatology 2015;61:506-514)
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| 2. |
- Mancina, Rosellina Margherita, et al.
(författare)
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Paradoxical Dissociation Between Hepatic Fat Content and De Novo Lipogenesis Due to PNPLA3 Sequence Variant
- 2015
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Ingår i: Journal of Clinical Endocrinology & Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 100:5
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Tidskriftsartikel (refereegranskat)abstract
- Context: Nonalcoholic fatty liver disease (NAFLD) is an emerging epidemic disease characterized by increased hepatic fat, due to an imbalance between synthesis and removal of hepatic lipids. In particular, increased hepatic de novo lipogenesis (DNL) is a key feature associated with NAFLD. The genetic variations I148M in PNPLA3 and E167K in TM6SF2 confer susceptibility to NAFLD. Objective: Here we aimed to investigate the contribution of DNL to liver fat accumulation in the PNPLA3 I148M or TM6SF2 E167K genetic determinants of NAFLD. Patients and Methods: The PNPLA3 I148M and TM6SF2 E167K were genotyped in two well-characterized cohorts of Europeans. In the first cohort (Helsinki cohort; n = 88), we directly quantified hepatic DNL using deuterated water. In the second cohort (Milan cohort; n = 63), we quantified the hepatic expression of SREBP1c that we have found previously associated with increased fat content. Liver fat was measured by magnetic resonance proton spectroscopy in the Helsinki cohort, and by histological assessment of liver biopsies in the Milan cohort. Results: PNPLA3 148M was associated with lower DNL and expression of the lipogenic transcription factor SREBP1c despite substantial increased hepatic fat content. Conclusions: Our data show a paradoxical dissociation between hepatic DNL and hepatic fat content due to the PNPLA3 148M allele indicating that increased DNL is not a key feature in all individuals with hepatic steatosis, and reinforces the contribution of decreased mobilization of hepatic triglycerides for hepatic lipid accumulation in subject with the PNPLA3 148M allele.
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| 3. |
- Baselli, G. A., et al.
(författare)
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Liver transcriptomics highlights interleukin-32 as novel NAFLD-related cytokine and candidate biomarker
- 2020
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Ingår i: Gut. - : BMJ. - 0017-5749 .- 1468-3288. ; 69, s. 1855-1866
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Efforts to manage non-alcoholic fatty liver disease (NAFLD) are limited by the incomplete understanding of the pathogenic mechanisms and the absence of accurate non-invasive biomarkers. The aim of this study was to identify novel NAFLD therapeutic targets andbiomarkers by conducting liver transcriptomic analysis in patients stratified by the presence of the PNPLA3 I148M genetic risk variant. Design: We sequenced the hepatic transcriptome of 125 obese individuals. 'Severe NAFLD' was defined as the presence of steatohepatitis, NAFLD activity score ≥4 or fibrosis stage ≥2. The circulating levels of the most upregulated transcript, interleukin-32 (IL32), were measured by ELISA. Results: Carriage of the PNPLA3 I148M variant correlated with the two major components of hepatic transcriptome variability and broadly influenced gene expression. In patients with severe NAFLD, there was an upregulation of inflammatory and lipid metabolism pathways. IL32 was the most robustly upregulated gene in the severe NAFLD group (adjusted p=1×10-6), and its expression correlated with steatosis severity, both in I148M variant carriers and non-carriers. In 77 severely obese, and in a replication cohort of 160 individuals evaluated at the hepatology service, circulating IL32 levels were associated with both NAFLD and severe NAFLD independently of aminotransferases (p<0.01 for both). A linear combination of IL32-ALT-AST showed a better performance than ALT-AST alone in NAFLD diagnosis (area under the curve=0.92 vs 0.81, p=5×10-5). Conclusion: Hepatic IL32 is overexpressed in NAFLD, correlates with hepatic fat and liver damage, and is detectable in the circulation, where it is independently associated with the presence and severity of NAFLD. © 2020 American Medical Association. All rights reserved.
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| 4. |
- Mondul, A., et al.
(författare)
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PNPLA3 1148M Variant Influences Circulating Retinol in Adults with Nonalcoholic Fatty Liver Disease or Obesity
- 2015
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Ingår i: Journal of Nutrition. - : Elsevier BV. - 0022-3166. ; 145:8, s. 1687-1691
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Tidskriftsartikel (refereegranskat)abstract
- Background: Retinal is a lipid-soluble essential nutrient that is stored as retinyl esters in lipid droplets of hepatic stellate cells. Patatin-like phospholipase domain-containing 3 (PNPLA3), through its retinyl-palmitate lipase activity, releases retinol from lipid droplets in hepatic stellate cells in vitro and ex vivo. We have shown that the genetic variant 1148M (rs738409) reduces the PNPLA3 retinyl-palmitate lipase activity. Objective: The aim of the present genetic association study was to test whether overweight/obese carriers of the PNPLA3 148M mutant allele had lower circulating concentrations of retinal than individuals who are homozygous for the 1481 allele. Methods: PNPLA31148M (rs738409) was genotyped by Taqman assay in 76 overweight/obese individuals [BMI (kg/m(2))>= 25; mean +/- SD age: 59.7 +/- 11.4 y; male gender: 70%] with a histologic diagnosis of nonalcoholic fatty liver disease (NAFLD; namely the Milan NAFLD cohort) and in 413 obese men (BMI >= 30; mean SD age: 57.1 +/- 4.9 y) from the alpha-Tocopherol, (beta-Carotene Cancer Prevention (ATBC) Study. Serum concentrations of retinal and alpha-tocopherol were measured by HPLC in both cohorts. beta-Carotene concentrations in the ATBC study were measured by using HPLC. Results: The PNPLA3 148M mutant allele was associated with lower fasting circulating concentrations of retinal (beta = -0.289, P = 0.03) in adults with NAFLD (Milan NAFLD cohort). The PNPLA3148M mutant allele was also associated with lower fasting circulating concentrations of retinal in adults with a BMI >= 30 (ATBC study; [beta = -0.043, P = 0.041. Conclusion: We showed for the first time, to our knowledge, that carriers of the PNPLA3148M allele with either fatty liver plus obesity or obesity alone have lower fasting circulating retinol concentrations.
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| 5. |
- Pelusi, S, et al.
(författare)
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Prevalence and Risk Factors of Significant Fibrosis in Patients With Nonalcoholic Fatty Liver Without Steatohepatitis.
- 2019
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Ingår i: Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association. - : Elsevier BV. - 1542-7714. ; 17:11
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Tidskriftsartikel (refereegranskat)abstract
- In patients with nonalcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis (NASH) is a risk factor for the development of fibrosis. However, fibrosis has been observed in livers of patients without NASH. We aimed to estimate the prevalence of fibrosis in patients without NASH and risk factors for fibrosis.We analyzed data from 1738 subjects (44.9% with severe obesity) in a cross-sectional liver biopsy cohort enrolled at referral centers in Italy and Finland. Biopsy specimens were analyzed histologically by a blinded pathologist at each center, and a diagnosis of NASH was made based on steatosis (≥5% of hepatocytes), hepatocellular ballooning, and lobular inflammation. We also collected data on demographic features, metabolic comorbidities, and genetic factors, and performed logistic regression analyses. Findings were validated using data from 118 consecutive patients with NAFLD who underwent sequential liver biopsies at tertiary referral centers in Italy.In the cross-sectional cohort, 132 of 389 patients (33.9%) with significant fibrosis had no NASH and 39 patients (10.0%) had no inflammation. The dissociation between NASH and fibrosis was significantly greater in patients with severe obesity (P < .005). Steatosis, ballooning, and lobular inflammation each were associated independently with significant fibrosis (P < .001); age, adiposity, fasting hyperglycemia, and the PNPLA3 I148M variant also were associated with fibrosis. In patients without, but not in those with, NASH, significant fibrosis was associated with steatosis grade and the PNPLA3 I148M variant. In patients without NASH, age, fasting hyperglycemia, ballooning, and inflammation were associated with fibrosis. In the validation cohort, 16 of 47 patients (34.0%) with clinically significant fibrosis did not have NASH at baseline. In patients with fibrosis without baseline NASH, worsening of fibrosis (based on later biopsies) was associated with fasting hyperglycemia and more severe steatosis (P= .016).In an analysis of biopsy specimens collected from patients with NAFLD at a single time point, one third of patients with significant fibrosis did not have NASH. We validated this finding in a separate cohort. In patients without NASH, fasting hyperglycemia, severe steatosis, mild inflammation or ballooning, and the PNPLA3 I148M variant identified those at risk of significant fibrosis.
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| 6. |
- Pirazzi, Carlo, et al.
(författare)
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PNPLA3 has retinyl-palmitate lipase activity in human hepatic stellate cells
- 2014
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 23:15, s. 4077-4085
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Tidskriftsartikel (refereegranskat)abstract
- Retinoids are micronutrients that are stored as retinyl esters in the retina and hepatic stellate cells (HSCs). HSCs are key players in fibrogenesis in chronic liver diseases. The enzyme responsible for hydrolysis and release of retinyl esters from HSCs is unknown and the relationship between retinoid metabolism and liver disease remains unclear. We hypothesize that the patatin-like phospholipase domain-containing 3 (PNPLA3) protein is involved in retinol metabolism in HSCs. We tested our hypothesis both in primary human HSCs and in a human cohort of subjects with non-alcoholic fatty liver disease (N = 146). Here we show that PNPLA3 is highly expressed in human HSCs. Its expression is regulated by retinol availability and insulin, and increased PNPLA3 expression results in reduced lipid droplet content. PNPLA3 promotes extracellular release of retinol from HSCs in response to insulin. We also show that purified wild-type PNPLA3 hydrolyzes retinyl palmitate into retinol and palmitic acid. Conversely, this enzymatic activity is markedly reduced with purified PNPLA3 148M, a common mutation robustly associated with liver fibrosis and hepatocellular carcinoma development. We also find the PNPLA3 I148M genotype to be an independent (P = 0.009 in a multivariate analysis) determinant of circulating retinol-binding protein 4, a reliable proxy for retinol levels in humans. This study identifies PNPLA3 as a lipase responsible for retinyl-palmitate hydrolysis in HSCs in humans. Importantly, this indicates a potential novel link between HSCs, retinoid metabolism and PNPLA3 in determining the susceptibility to chronic liver disease.
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| 7. |
- Prill, S., et al.
(författare)
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The TM6SF2 E167K genetic variant induces lipid biosynthesis and reduces apolipoprotein B secretion in human hepatic 3D spheroids
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- There is a high unmet need for developing treatments for nonalcoholic fatty liver disease (NAFLD), for which there are no approved drugs today. Here, we used a human in vitro disease model to understand mechanisms linked to genetic risk variants associated with NAFLD. The model is based on 3D spheroids from primary human hepatocytes from five different donors. Across these donors, we observed highly reproducible differences in the extent of steatosis induction, demonstrating that inter-donor variability is reflected in the in vitro model. Importantly, our data indicates that the genetic variant TM6SF2 E167K, previously associated with increased risk for NAFLD, induces increased hepatocyte fat content by reducing APOB particle secretion. Finally, differences in gene expression pathways involved in cholesterol, fatty acid and glucose metabolism between wild type and TM6SF2 E167K mutation carriers (N = 125) were confirmed in the in vitro model. Our data suggest that the 3D in vitro spheroids can be used to investigate the mechanisms underlying the association of human genetic variants associated with NAFLD. This model may also be suitable to discover new treatments against NAFLD.
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