Search

The identification of genetic variants associated with fatty liver disease (FLD) from genome-wide association studies started in 2008 when single nucleotide polymorphisms in PNPLA3 , the gene encoding patatin-like phospholipase domain-containing 3, were found to be associated with altered hepatic fat content. Since then, several genetic variants associated with protection from, or an increased risk of, FLD have been identified. The identification of these variants has provided insight into the metabolic pathways that cause FLD and enabled the identification of potential therapeutic targets. In this mini-review, we will examine the therapeutic opportunities derived from genetically validated targets in FLD, including oligonucleotide-based therapies targeting PNPLA3 and HSD17 B 1 3 that are currently being evaluated in clinical trials for the treatment of NASH (non-alcoholic steatohepatitis). [ABSTRACT FROM AUTHOR]

Background: The polymorphism associated with liver fat content, which is well-known as PNPLA3 rs738409 (Patatin-like phospholipase domain-containing protein 3), is one of the critical subjects widely investigated in the literature regarding the prevalence of non-alcoholic fatty liver disease (NAFLD) worldwide. The present research aimed to study the bioinformatics investigations of this polymorphism together with the in vitro analyses among patients with NAFLD. Materials and Methods: In this case-control study, after performing bioinformatics analysis, the laboratory examination was performed in several steps. Genomic DNA was extracted from the blood of 53 NAFLD patients and 107 subjects with normal liver ultrasounds. PNPLA3 rs738409 was genotyped by the polymerase chain reaction-restriction fragment length polymorphism method. The laboratory test results, including fasting blood sugar, triglyceride, cholesterol, high-density lipoprotein, low-density lipoprotein, alanine aminotransferase, and aspartate aminotransferase were collected from medical records. Finally, statistical analysis was performed using SPSS software, version 18.0. Results: The frequency of the G allele was 56% and 36% among patients and in the control group, respectively. The frequency of genotypes was 35.8% and 47.7% (CC), 17% and 31.8% (CG), 47.2% and 20.6% (GG) in patients and control groups, respectively. The adjusted odds ratios for PNPLA3 rs738409 C>G were 3.0 (95% confidence interval [CI]: 1.28-6.98, P=.011) and 0.68 (95% CI: 0.25- 1.83, P = .44) for GG and CG genotypes, respectively. Conclusion: The findings showed the association between the GG genotype and the presence of NAFLD. Furthermore, the bioinformatics findings suggested the probable risk of the disease incidence regarding the change of hydropathic characteristics resulting from the amino acid substitution.

Abstract Background The present study investigates if common missense functional variants p.I148M and p.E167K in PNPLA3 and TM6SF2 genes, respectively, associate with development of hepatic fibrosis and cirrhosis in a geographically novel cohort of Pakistani chronic hepatitis C (CHC) patients. Methods In total, 502 Pakistani CHC patients [242 males, median age 40 years, 220 with significant hepatic fibrosis, including 114 with cirrhosis] were genotyped for PNPLA3 and TM6SF2 variants using TaqMan genotyping assays. Associations between genotypes, biochemical and clinical parameters were evaluated. Results Genotypic distributions for PNPLA3 and TM6SF2 polymorphisms conformed to Hardy–Weinberg equilibrium and did not associate with fibrosis grades ≥ F2 or cirrhosis in any of the genetic models tested (all p = > 0.05). PNPLA3 and TM6SF2 variants did not modulate baseline characteristics and serum markers of liver injury in CHC patients. Similarly, increasing number of risk alleles of PNPLA3 and TM6SF2 polymorphisms had no trend effect on serum liver enzyme activities or proportion of CHC patients with significant or advanced fibrosis or cirrhosis (p = > 0.05). The same trend of no association with hepatic fibrosis or cirrhosis persisted in the multivariate logistic regression models adjusting for age, gender, body mass index and HCV viral load (p = > 0.05). Conclusions PNPLA3 and TM6SF2 variants do not appear to modulate development of hepatic fibrosis or cirrhosis in present CHC patients of Pakistani origin, and may be of more relevance in liver pathology involving abnormalities in hepatic fat accumulation. These results also reflect the divergent associations observed for different genetic modifiers of hepatic fibrosis and cirrhosis in distinct ethnicities.

AIM: To evaluate plasma and aqueous levels of adiponutrin and pannexin 1 in patients with and without diabetic retinopathy. METHODS: The study included three age and gender-matched groups of 20 cataract patients with no diabetes or additional disease (Group C), 20 cataract patients with diabetes and no retinopathy (Group DM+C), and 20 cataract patients with diabetic retinopathy (Group DR+C). All the patients were examined with respect to body mass index (BMI), fasting plasma glucose, hemoglobin A1c (HbA1c), and lipid profile. Phacoemulsification and intraocular lens (Phaco+IOL) implantation were performed to all patients in all the groups, and aqueous samples were taken during the operation. The plasma and aqueous adiponutrin and pannexin 1 levels were analyzed using enzyme-linked immunosorbent assays. RESULTS: A statistically significant difference was determined between the groups with respect to BMI, fasting plasma glucose, and HbA1c levels (P

Background: The present study investigates if common missense functional variants p.I148M and p.E167K in PNPLA3 and TM6SF2 genes, respectively, associate with development of hepatic fibrosis and cirrhosis in a geographically novel cohort of Pakistani chronic hepatitis C (CHC) patients.Methods: In total, 502 Pakistani CHC patients [242 males, median age 40 years, 220 with significant hepatic fibrosis, including 114 with cirrhosis] were genotyped for PNPLA3 and TM6SF2 variants using TaqMan genotyping assays. Associations between genotypes, biochemical and clinical parameters were evaluated.Results: Genotypic distributions for PNPLA3 and TM6SF2 polymorphisms conformed to Hardy-Weinberg equilibrium and did not associate with fibrosis grades ≥ F2 or cirrhosis in any of the genetic models tested (all p =  > 0.05). PNPLA3 and TM6SF2 variants did not modulate baseline characteristics and serum markers of liver injury in CHC patients. Similarly, increasing number of risk alleles of PNPLA3 and TM6SF2 polymorphisms had no trend effect on serum liver enzyme activities or proportion of CHC patients with significant or advanced fibrosis or cirrhosis (p =  > 0.05). The same trend of no association with hepatic fibrosis or cirrhosis persisted in the multivariate logistic regression models adjusting for age, gender, body mass index and HCV viral load (p =  > 0.05).Conclusions: PNPLA3 and TM6SF2 variants do not appear to modulate development of hepatic fibrosis or cirrhosis in present CHC patients of Pakistani origin, and may be of more relevance in liver pathology involving abnormalities in hepatic fat accumulation. These results also reflect the divergent associations observed for different genetic modifiers of hepatic fibrosis and cirrhosis in distinct ethnicities. [ABSTRACT FROM AUTHOR]

Background Variants of adiponutrin (PNPLA3) and adiponectin (ADIPOQ) genes were considered to be associated with non-alcoholic fatty liver disease (NAFLD). Although the prevalence of NAFLD is increasing, there are limited numbers of studies about the association in Indonesian population. Objective To confirm whether specific variants of adiponutrin (PNPLA3) and adiponectin (ADIPOQ) genes are associated with NAFLD in Indonesian patients. Methods Data and DNA of 152 participants were obtained from a previous study in Dr. Kariadi Hospital, Semarang, Indonesia. PCR-RFLP analysis was performed for detection of PNPLA3 rs738409 and ADIPOQ rs2241767 variants. The diagnosis and severity of NAFLD were assessed according to NAFLD activity score (NAS) based on histopathology assessment of liverbiopsy. Results Allele G of PNPLA3rs738409 was associated with NAFLD in both bivariate (p=0.009, OR 2.52, CI 95% 1.25–5.07) and multivariate (p=0.008, OR 2.62, CI 95% 1.29%–5.32%) analysis, while ADIPOQ rs2241767 had no significant association. In NAFLD participants, both genotypes showed allele G was higher in the group of possible non-alcoholic steatohepatitis (NASH) – NASH (NAS >2) than in the simple steatosis group (NAS

Hypertensive disease today is one of the most common cardiovascular diseases, as well as the most common disease associated with obesity. Evaluation of the level of adipokines, namely adiponutrin and galanin, depending on the degree and duration of hypertension, the degree of obesity and their correction against the background of combined antihypertensive therapy is relevant for further understanding of this comorbidity and improvement of the early diagnostics. 127 people were examined, including 107 patients with hypertension of degree 1–3 and 20 healthy persons. Of the patients included in the study, the adiponutrin and the galanin levels were determined in 58 patients, out of which 22 were prescribed different regimens of combined antihypertensive therapy. To determine the level of adiponutrin and galanin, an enzyme-linked immunosorbent assay was used. A significant increase was found in the blood serum of the examined adipokines in comparison with the control group: the galanin level was 4.8 times higher than in the control group, the adiponutrin level in patients with this comorbid pathology was 3.3 times higher than that in the control group. The galanin level is most pronounced in patients with hypertension of degree 3 and obesity of degree 3, which is confirmed by the presence of a direct correlation with systolic, diastolic and pulse blood pressure, very low density lipoprotein cholesterol. The adiponutrin level in the blood serum increased correspondingly to the increase in body mass index: in patients with obesity of degree 3 it was 15.8 times higher than this indicator in patients with normal body weight, 8.8 times higher than in patients with overweight, 6.1 times higher than in patients with obesity of degree 1 and 2.5 times higher than in patients with obesity of degree 2. The levels of the studied adipokines in patients differed also relative to the duration of hypertension. There was a 1.8-, 5.1-, 5.2-fold increase (respectively, ≤5, 6–10, >10 years) of the galanin content in the blood serum compared to the control group. Also an increase of the serum adiponutrin level was noted in comparison with the control group. Against the background of combined antihypertensive therapy, we observed favourable dynamics of galanin and adiponutrin. It is important to conduct further studies to assess the activity of galanin and adiponutrin with a longer follow-up period in wider populations.

Background and aims: Non-alcoholic fatty liver disease is one of a chronic liver diseases, characterized by an unusual accumu- lation of fats in hepatocytes. It's a multifactorial disease and the pathogenesis is not completely known. The genetic association is seen, where the patatin-like phospholipase domain-containing protein 3 (PNPLA3) is the most relevant genetic association. PNPLA3 encodes for a protein called adiponutrin (ADPN), which has triglyceride hydrolase and acyltransferase activity. Hepatic fat accumulation results due to excess lipogenesis or decreased fat export. Liver biopsy is the only gold standard available for differentiating the stages of NAFLD, but it's an invasive procedure that may lead to potential infections. The study aimed to eval- uate serum levels of ADPN in stages of NAFLD. Materials and methods: This is an observational study comprised of 60 NAFLD cases, among which 10 subjects were stage 1 (simple steatosis) and 50 subjects stage 2 (non-alcoholic steatohepatitis-NASH). Blood samples were collected from the subjects and serum ADPN levels were assessed by enzyme-linked immunosorbent assay. Results: The serum levels of ADPN were significantly decreased in NASH as compared to simple steatosis (p<0.00l). Conclu- sions: ADPN serum level was inversely associated with the progression of NAFLD. [ABSTRACT FROM AUTHOR]

Non-alcoholic steatohepatitis (NASH) is a disorder marked by alterations in hepatic lipid homeostasis as well as liver injury in the form of cell death, inflammation and fibrosis. Research into the pathophysiology of NASH is dynamic. New concepts from the fields of cell biology, microbiology, immunology and genetics are being tested for their applicability to NASH; discoveries in each of these areas are enriching our understanding of this complex disease. This review summarizes how recent developments from the bench and bedside are merging with more traditional concepts to reshape our view of NASH pathogenesis. Highlights include human studies that emphasize the role of de novo lipogenesis in NASH and experimental work uncovering a role for the inflammasome in NASH. Genetic predispositions to NASH are being clarified, and intestinal microbiome is emerging as a determinant of fatty liver. These unique ideas are now taking their place within an integrated picture of NASH pathogenesis.

Liver fibrosis is the common consequence of chronic liver diseases (CLD). Recently liver stiffness measurements (LSM) = 9.1 kPa, as determined by transient elastography (TE), were demonstrated to predict significant fibrosis (stages = F2) in a population-based setting. The PNPLA3 (adiponutrin) p.I148M polymorphism enhances the risk of liver injury. The aim of our study was to investigate the association between the procholestatic ABCB4 polymorphism c.711A>T and LSM = 9.1 kPa in humans as well as the interaction between ABCB4 and PNPLA3 in a mouse model of chronic cholestasis. Prospectively, we recruited 712 patients with CLD (278 women, age 50 ± 13 years) with available TE results; liver biopsy results were available in 165 individuals. The ABCB4 c.711 genotype was determined by PCR-based assays. Pnpla3 expression and liver injury were studied in Abcb4-/- mice and wild-type controls. Overall, median LSM in our cohort was 6.7 kPa, and 226 individuals had LSM = 9.1 kPa. Carriers of the ABCB4 variant c.711A presented more frequently with LSM = 9.1 kPa (OR = 1.33, P = 0.020) and FIB-4 score = 2.67 (OR = 1.38, P = 0.040). The presence of the risk allele was associated (P = 0.002) with FIB-4. In a multivariate model, the ABCB4 variant (OR = 1.43, P = 0.047) as well as BMI (P = 0.043, OR = 1.04) and age (OR = 1.02, P < 0.010) were independent risk factors for fibrosis stage = F2. Abcb4 deficiency in mice led to enhanced liver injury, coupled with a decrease (P = 0.020) of hepatic Pnpla3 expression. To conclude, the procholestatic variant ABCB4 c.711A>T might represent a new genetic risk factor for clinically significant liver fibrosis. Lower expression of Pnpla3 in fibrotic Abcb4-/- livers points to the interaction between phospholipid metabolism and PNPLA3 in progressive liver injury. [ABSTRACT FROM AUTHOR]

Background and Aims: Emerging evidence suggests an association between patatin‐like phospholipase domain‐containing protein‐3 (PNPLA3) rs738409 (I148M protein variant) and risk of chronic kidney disease (CKD), but the mechanisms underpinning this association are poorly understood. Methods: We studied 157 patients with type 2 diabetes (T2DM) who underwent ultrasonography and vibration‐controlled transient elastography for diagnosing nonalcoholic fatty liver disease (NAFLD). CKD was defined as estimated glomerular filtration rate (e‐GFR) <60 mL/min/1.73 m2 and/or abnormal albuminuria. We surveyed PNPLA3 mRNA expression in human tissues, using the liver as a positive control, and also measured PNPLA3 mRNA and protein expression levels in human cell lines represented in the kidney and the liver. Results: In all, 112 patients had NAFLD and 43 had CKD. Patients homozygous for the I148M variant (n = 11) had lower e‐GFR levels (60.6 ± 11.7 vs 77.8 ± 15.9 vs 83.5 ± 16.5 mL/min/1.73 m2, P =.0001) and higher prevalence of CKD (63.6% vs 24.2% vs 25.0%, P =.028), compared to those with I/M (n = 66) and I/I (n = 80) PNPLA3 genotype. The association of I148M homozygosity with lower e‐GFR levels (P <.0001) and higher risk of CKD (adjusted‐odds ratio 6.65; 95% CI 1.65‐26.8, P =.008) was independent of liver disease severity (as detected by liver stiffness ≥7kPa) and other risk factors. PNPLA3 mRNA expression was greatest in liver and renal cortex, and podocytes showed high PNPLA3 mRNA and protein levels, comparable to that of hepatocytes and hepatic stellate cells respectively. Conclusions: The PNPLA3 I148M variant was associated with CKD, independently of common renal risk factors and severity of NAFLD PNPLA3 expression levels were particularly high in renal podocytes. [ABSTRACT FROM AUTHOR]

Liver steatosis is one of the side effects of chemotherapy. The PNPLA3 p.I148M, TM6SF2 p.E167K and MBOAT7 p.G17E variants represent genetic determinants for progressive liver diseases. Here, we investigate their association with chemotherapy-associated steatosis. Prospectively, we recruited 87 patients undergoing systemic chemotherapy for gastrointestinal cancers. Hepatic fat (controlled attenuation parameter, CAP) and liver stiffness (LSM) were measured non-invasively before the initiation of chemotherapy (T0) and after at least two (T1) and four cycles (T2). Genetic variants were genotyped using allelic discrimination assays. In the final dataset (n = 60) patients demonstrated the following CAP values: T0 – 215.0 ± 55.7 dB/m, T1 – 223.3 ± 53.6 dB/m, T2 – 223.4 ± 56.7 dB/m, consistent with mild steatosis. Initial CAP correlated with BMI (P < 0.01) and serum triglyceride concentrations (P = 0.03). Whereas at T0 none of the variants was associated with CAP or LSM, carriers of the prosteatotic PNPLA3 p.148M allele showed significantly (P = 0.008) higher steatosis at T1 as compared to patients carrying the homozygous wild-type genotype [II]. Our preliminary results show that patients carrying the PNPLA3 p.I148 M risk allele might be prone to hepatic fat accumulation during chemotherapy. Further studies are be needed to validate the clinical value of these findings. [ABSTRACT FROM AUTHOR]

Patatin-like phospholipase domain containing proteins (PNPLAs) play diverse roles in lipid metabolism. In this review, we focus on the enzymatic properties and predicted 3D structures of PNPLA1-5. PNPLA2-4 exert both catabolic and anabolic functions. Whereas PNPLA1 is predominantly expressed in the epidermis and involved in sphingolipid biosynthesis, PNPLA2 and 4 are ubiquitously expressed and exhibit several enzymatic activities, including hydrolysis and transacylation of various (glycero-)lipid species. This review summarizes known biological roles for PNPLA-mediated hydrolysis and transacylation reactions and highlights open questions concerning their physiological function. • PNPLA2-4 exert both catabolic and anabolic functions as hydrolases and transacylases. • PNPLA1 is only described as a transacylase and is crucial for acylceramide biosynthesis. • PNPLA5 is only described as a possible TAG hydrolase. • Open questions include the physiological relevance of trancylation processes of PNPLA2-4. • The regulation of the balance between hydrolysis and transacylation also needs to be investigated in more detail. • The role of transacylation in the biosynthesis of other bioactive lipids besides FAHFAs still requires further studies. [ABSTRACT FROM AUTHOR]

Francesca Virginia Bruschi, Matteo Tardelli, Thierry Claudel, Michael Trauner Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology & Hepatology, Department of Internal Medicine III, Medical University of Vienna, Austria Abstract: A single-nucleotide polymorphism occurring in the sequence of the human patatin-like phospholipase domain-containing 3 gene (PNPLA3), known as I148M variant, is one of the best characterized and deeply investigated variants in several clinical scenarios, because of its tight correlation with increased risk for developing hepatic steatosis and more aggressive part of the disease spectrum, such as nonalcoholic steatohepatitis, advanced fibrosis and cirrhosis. Further, the I148M variant is positively associated with alcoholic liver diseases, chronic hepatitis C–related cirrhosis and hepatocellular carcinoma. The native gene encodes for a protein that has not yet a fully defined role in liver lipid metabolism and, according to recent observations, seems to be divergently regulated among distinct liver cells type, such as hepatic stellate cells. Therefore, the aim of this review is to collect the latest data regarding PNPLA3 expression in human liver and to analyze the impact of its genetic variant in human hepatic pathologies. Moreover, a description of the current biochemical and metabolic data pertaining to PNPLA3 function in both animal models and in vitro studies is summarized to allow a better understanding of the relevant pathophysiological role of this enzyme in the progression of hepatic diseases. Keywords: adiponutrin, liver disease, genetic polymorphism, gene expression, metabolism

The PNPLA3 p.I148M, TM6SF2 p.E167K, and MBOAT7 rs641738 variants represent genetic risk factors for nonalcoholic fatty liver disease (NAFLD). Here we investigate if these polymorphisms modulate both steatosis and fibrosis in patients with NAFLD. We recruited 515 patients with NAFLD (age 16–88 years, 280 female patients). Liver biopsies were performed in 320 patients. PCR-based assays were used to genotype the PNPLA3, TM6SF2, and MBOAT7 variants. Carriers of the PNPLA3 and TM6SF2 risk alleles showed increased serum aspartate aminotransferase and alanine transaminase activities (P < 0.05). The PNPLA3 genotype was associated with steatosis grades S2–S3 (P < 0.001) and fibrosis stages F2–F4 (P < 0.001). The TM6SF2 genotype was associated with steatosis (P = 0.003) but not with fibrosis (P > 0.05). The MBOAT7 variant was solely associated with increased fibrosis (P = 0.046). In the multivariate model, variants PNPLA3 (P = 0.004) and TM6SF2 (P = 0.038) were associated with steatosis. Fibrosis stages were affected by the PNPLA3 (P = 0.042) and MBOAT7 (P = 0.021) but not by the TM6SF2 polymorphism (P > 0.05). The PNPLA3, TM6SF2, and MBOAT7 variants are associated with increased liver injury. The TM6SF2 variant seems to modulate predominantly hepatic fat accumulation, whereas the MBOAT7 polymorphism is linked to fibrosis. The PNPLA3 polymorphism confers risk of both increased steatosis and fibrosis.

Abstract Objective Comorbid NAFLD is increasingly being diagnosed in patients with diabetes and nondiabetic endocrinopathies. The aim of this study was to assess hepatic steatosis noninvasively by transient elastography in patients with acromegaly. Design A cross‐sectional study including 22 patients with acromegaly. Methods Hepatic steatosis was quantified using controlled attenuation parameter (CAP) during elastography. Anthropometric measurements were obtained, serum liver function tests and lipid and hormone profiles were measured, and prosteatogenic gene variants were genotyped using standard assays. Results In total, 41% of patients were women (mean age 60 ± 14.7 years, mean BMI 31.2 ± 4.6 kg/m2). Hepatic steatosis, as defined by CAP > 248 dB/m, was present in 66% of patients. Five (45%) of the patients with hepatic steatosis also had fibrosis, and one presented with cirrhosis. Nine patients were carriers of the PNPLA3 p.I148M prosteatogenic [M] risk allele, eight of whom were heterozygotes. CAP values were significantly (P = .045) higher in these patients and corresponded to advanced steatosis, as compared to patients with the wild‐type genotype, who demonstrated CAP values consistent with mild steatosis (311 ± 33 dB/m. vs 254 ± 62 dB/m). CAP values did not differ significantly in carriers of distinct TM6SF2 and MBOAT7 genotypes; however, carriers of the risk alleles displayed higher CAP as compared to wild‐type patients. Conclusions This study shows that in patients with acromegaly, carriers of the PNPLA3 susceptibility allele are at risk of developing hepatic steatosis, as assessed by CAP. Comorbid NAFLD might compound prognosis in such patients; thus, further research into the pathomechanisms and treatment of NAFLD in acromegaly is warranted.

Background: The prevalence of nonalcoholic fatty liver disease (NAFLD) in patients with type 2 diabetes mellitus (T2DM) is high, though its severity is often underestimated. Our aim is to provide an estimate of the prevalence of severe NAFLD in T2DM and identify its major predictors. Methods: T2DM patients (n=328) not previously known to have NAFLD underwent clinical assessment, transient elastography with measure of liver stiffness (LS) and controlled attenuation parameter (CAP), and genotyping for patatin like phospholipase domain containing 3 (PNPLA3) and 17ß-hydroxysteroid-dehydrogenase type 13 (HSD17B13). Results: Median LS was 6.1 kPa (4.9 to 8.6). More than one-fourth patients had advanced liver disease, defined as LS ≥7.9 kPa (n=94/238, 29%), and had a higher body mass index (BMI) than those with a LS <7.9 kPa. Carriage of the G allele in the PNPLA3 gene was associated with higher LS, being 5.9 kPa (4.7 to 7.7) in C/C homozygotes, 6.1 kPa (5.2 to 8.7) in C/G heterozygotes, and 6.8 kPa (5.8 to 9.2) in G/G homozygotes (P=0.01). This trend was absent in patients with =1 mutated HSD17B13 allele. In a multiple linear regression model, BMI and PNPLA3 genotype predicted LS, while age, gender, disease duration, and glycosylated hemoglobin did not fit into the model. None of these variables was confirmed to be predictive among carriers of at least one HSD17B13 mutated allele. There was no association between CAP and polymorphisms of PNPLA3 or HSD17B13. Conclusion: Advanced NAFLD is common among T2DM patients. LS is predicted by both BMI and PNPLA3 polymorphism, the effect of the latter being modulated by mutated HSD17B13. [ABSTRACT FROM AUTHOR]

Evidence is emerging that PNPLA3 rs738409 polymorphism (the major genetic variant associated with susceptibility to non-alcoholic fatty liver disease [NAFLD]) is associated with chronic kidney disease (CKD) in non-diabetic individuals. Currently, little is known about this association in type 2 diabetic (T2DM) patients with and without NAFLD. We studied 101 Caucasian post-menopausal women with T2DM, consecutively attending our diabetes outpatient service during a 3-month period. Glomerular filtration rate (eGFR CKD-EPI) was estimated using the CKD-Epidemiology Collaboration (CKD-EPI) equation, whilst albuminuria was measured with an immunonephelometric assay on morning spot urine samples. NAFLD was detected either by fatty liver index (FLI ≥ 60, n = 101) or by ultrasonography (n = 77). Genotyping was performed by TaqMan-Based RT-PCR system. Eight patients had G/G, 41 G/C and 52 C/C PNPLA3 rs738409 genotypes, and 21 (20.8%) patients had CKD (eGFR CKD-EPI < 60 mL/min/1.73 m2 or abnormal albuminuria). Compared to those with G/C or C/C genotypes, patients with G/G genotype had significantly lower eGFR CKD-EPI (63.7 ± 11 vs. 77.4 ± 17 vs. 81.9 ± 15 mL/min/1.73 m2, P = 0.014) and higher prevalence of CKD (50% vs. 24.4% vs. 13.5%, P = 0.04). After adjustment for age, duration of diabetes, haemoglobin A 1c , HOMA-estimated insulin resistance, systolic blood pressure, hypertension treatment and FLI ≥ 60, rs738409 G/G genotype was independently associated with both lower eGFR CKD-EPI (β coefficient: −15.5, 95% CI −26.0 to −5.0, P = 0.004) and higher risk of CKD (adjusted-odds ratio 8.05, 95% CI 1.26–41.4, P = 0.03). Similar results were found when we adjusted for hepatic steatosis on ultrasography (instead of FLI ≥ 60). Regardless of the presence of NAFLD and common cardio-renal risk factors, in post-menopausal women with T2DM, the G/G genotype of rs738409 in the PNPLA3 gene was strongly associated with lower eGFR CKD-EPI and higher prevalence of CKD. [ABSTRACT FROM AUTHOR]

The I148M substitution in patatin-like phospholipase domain containing 3 (PNPLA3I148M) determines a genetic form of nonalcoholic fatty liver disease. To elucidate the mode of PNPLA3 action in human hepatocytes, we studied effects of WT PNPLA3 (PNPLA3WT) and PNPLA3I148M on HuH7 cell lipidome after [13C]glycerol labeling, cellular turnover of oleic acid labeled with 17 deuterium atoms ([D17]oleic acid) in triacylglycerols (TAGs), and subcellular distribution of the protein variants. PNPLA3I148M induced a net accumulation of unlabeled TAGs, but not newly synthesized total [13C]TAGs. Principal component analysis (PCA) revealed that both PNPLA3WT and PNPLA3I148M induced a relative enrichment of TAGs with saturated FAs or MUFAs, with concurrent enrichment of polyunsaturated phosphatidylcholines. PNPLA3WT associated in PCA with newly synthesized [13C]TAGs, particularly 52:1 and 50:1, while PNPLA3I148M associated with similar preexisting TAGs. PNPLA3WT overexpression resulted in increased [D17]oleic acid labeling of TAGs during 24 h, and after longer incubations their turnover was accelerated, effects not detected with PNPLA3I148M. PNPLA3I148M localized more extensively to lipid droplets (LDs) than PNPLA3WT, suggesting that the substitution alters distribution of PNPLA3 between LDs and endoplasmic reticulum/cytosol. This study reveals a function of PNPLA3 in FA-selective TAG remodeling, resulting in increased TAG saturation. A defect in TAG remodeling activity likely contributes to the TAG accumulation observed in cells expressing PNPLA3I148M.

Aim To examine the role of nucleotide binding oligomerization domain -like receptor family pyrin domain -containing 3 (NLRP3) inflammasomes in the development of non-alcoholic fatty liver disease (NAFLD). Methods Levels of mRNAs encoding NLRP3, apoptosis -associated speck -like protein containing a caspase recruitment domain, procaspase -1, interleukin (IL) -1β, and IL -18 were quantified by real-time polymerase chain reaction in 91 liver samples and 37 blood samples from biopsy -proven patients with NAFLD. Adiponutrin (also called PNPLA3) polymorphisms (rs738409, C > G) were determined in 74 samples by genotyping assays. Serum IL -1β and IL -18 levels were measured by enzyme-linked immunosorbent assay and liver tissue caspase -1 expression by immunostaining. Results Hepatic NLRP3, procaspase -1, IL -1β, and IL -18 mRNA levels were significantly higher in NAFLD patients than in controls and were significantly associated with adiponutrin G alleles. Blood procaspase -1 mRNA was significantly higher in NAFLD patients than in healthy controls. Hepatic procaspase -1 and IL -1β mRNA levels correlated significantly with lobular inflammation, hepatocyte ballooning, and NAFLD activity score. Serum IL -18 levels were significantly higher in NAFLD patients than in controls, while IL -1β levels were non -significantly higher. Serum IL -1β and IL -18 concentrations correlated significantly with steatosis, NAFLD activity score, and transaminase levels. Serum IL -1β levels were significantly associated with adiponutrin G alleles. Scattered caspase -1 -positive cells were present in portal tracts and inflammatory foci and around ballooning hepatocytes. Immunofluorescence staining showed that caspase-1 colocalized with the macrophage marker CD68. Conclusions The NLRP3 inflammasomes are primed in the liver, influenced by adiponutrin genotypes, and activated in Kupffer cells and/or macrophages in NAFLD, leading to histological progression through IL -1β and IL -18 production. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the potential use of the I148M/PNPLA3 (rs738409) gene polymorphism as a susceptibility marker for premature coronary artery disease (pCAD) and/or cardiovascular risk factors in Mexican type 2 diabetes mellitus patients (T2DM). The polymorphism was genotyped by 5′ exonuclease TaqMan assays in a group of 2572 subjects (1103 with pCAD and 1469 healthy controls) belonging to the Genetics of Atherosclerotic Disease (GEA) Mexican Study. Anthropometric and biochemical measurements were performed in all individuals. The association between the I148M/PNPLA3 (rs738409) gene polymorphism with pCAD and other metabolic and cardiovascular risk factors was evaluated using logistic regression analysis under different statistical approaches including dominant, recessive, heterozygous, additive, and co-dominant models. The polymorphism was not associated with pCAD in the whole group of participants, however, when patients and controls were divided into those with and without T2DM, under additive model, the polymorphism was associated with the presence of pCAD only in patients with T2DM (OR = 1.20, 95% CI: 1.01–1.42, P add = 0.042). On the other hand, under several models adjusted for age, gender, body mass index and T2DM, the polymorphism was associated with increased risk of fatty liver and elevated levels of alanine transaminase (ALT) in the whole group of pCAD patients and controls. In the control group, the polymorphism was associated with insulin resistance and coronary artery calcification (CAC) score ≥ 10 under several models. The results suggest that the I148M/PNPLA3 (rs738409) polymorphism is associated with the presence of pCAD in T2DM patients and with some cardiometabolic parameters. The association detected with CAC in the control group indicates that this polymorphism could be a marker for subclinical atherosclerosis. [ABSTRACT FROM AUTHOR]

Background & Aims Obesity and its related co-morbidities such as non-alcoholic fatty liver disease ( NAFLD) are increasing dramatically worldwide. The genetic variation in Patatin-like phospholipase domain-containing protein 3 ( PNPLA3), which is also called adiponutrin ( ADPN), in residue 148 (I148M, rs738409) has been associated with NAFLD. However, the regulation and function of PNPLA3 in metabolic diseases remains unclear. Laparoscopic gastric banding ( LAGB) of severely obese patients reduces body weight, liver and adipose tissue inflammation. In this study, we investigated whether weight loss induced by LAGB affected PNPLA3 expression in hepatic and adipose tissue. Methods Liver and subcutaneous adipose tissue samples were collected from 28 severely obese patients before and 6 months after LAGB. PNPLA3 expression was assessed by quantitative real-time PCR. To understand whether inflammatory stimuli regulated PNPLA3 expression, we studied the effect of tumour necrosis factor alpha ( TNFα) and lipopolysaccharide ( LPS) on PNPLA3 expression in human adipocytes and hepatocytes. Results PNPLA3 was strongly expressed in the liver and clearly detectable in subcutaneous adipose tissue of obese patients. Weight loss induced by LAGB of severely obese patients led to significantly increased adipose, but not hepatic, tissue expression of PNPLA3. Subcutaneous PNPLA3 expression negatively correlated with body-mass-index, fasting glucose and fasting insulin. TNFα potently suppressed PNPLA3 expression in adipocytes but not hepatocytes. Conclusions Weight loss induced by LAGB restored adipose tissue PNPLA3 expression which is suppressed by TNFα. Further studies will be required to determine the functional impact of PNPLA3 and its related genetic variation on adipose tissue inflammation and NAFLD. [ABSTRACT FROM AUTHOR]

Several publications have described biological roles for human patatin-like phospholipases (PNPLAs) in the regulation of adipocyte differentiation. Here, we report on the characterization and expression profiling of 10 human PNPLAs. A variety of bioinformatics approaches were used to identify and characterize all PNPLAs encoded by the human genome. The genes described represent a divergent family, most with a highly conserved ortholog in several mammalian species. In silico characterization predicts that two of the genes function as integral membrane proteins and are regulated by cAMP/cGMP. A structurally guided protein alignment of the patatin-like domain identifies a number of conserved residues in all family members. Quantitative PCR was used to determine the expression profile of each family member. Affymetrix-based profiling of a human preadipocyte cell line identified several members that are differentially regulated during cell differentiation. Cumulative data suggest that patatin-like genes normally expressed at very low levels are induced in response to environmental signals. Given the observed conservation of the patatin fold and lipase motif in all human PNPLAs, a single nomenclature to describe the PNPLA family is proposed.

Background Obesity is the major trigger of nonalcoholic fatty liver disease (NAFLD). NAFLD is further favored by the patatin-like phospholipase domain-containing 3 (PNPLA3) p.I148M, transmembrane 6 superfamily member 2 (TM6SF2) p.E167K, and membrane-bound O-acyltransferase domain containing 7 (MBOAT7) rs641738 variants. Objectives To investigate the relationship between the PNPLA3, TM6SF2, and MBOAT7 genotypes and the outcomes of bariatric surgery. Setting University hospital. Methods Prospectively we monitored 84 obese individuals (body mass index 35–64 kg/m 2 ) scheduled for bariatric surgery. The PNPLA3 p.I148M, TM6SF2 p.E167K, and MBOAT7 rs641738 variants were genotyped using restriction fragment length polymorphism analysis and TaqMan assays. Hepatic steatosis was determined before surgery using analysis of liver biopsy samples and a novel magnetic resonance imaging–based equation. One year later, steatosis was reevaluated by magnetic resonance imaging. Results The presence of the PNPLA3 allle [M] was associated with increased hepatic triglyceride content ( P = .03), steatosis detected by magnetic resonance imaging ( P = 0.04), and decreased serum glucose concentrations ( P = .04). Neither variant TM6SF2 nor MBOAT7 increased hepatic steatosis (all P >.05); however, the MBOAT7 polymorphism was associated with increased triglyceride, total cholesterol, low density lipoprotein, and serum glucose levels (all P <.05). Patients carrying the prosteatotic PNPLA3 allele [M] lost more weight ( P <.01) and liver fat ( P = .04) one year after surgery, as compared to individuals having the common genotype. The PNPLA3 genotype and initial grade of steatosis, but not the TM6SF2 or MBOAT7 variants, were independent predictors of NAFLD improvement ( P = .03 and P <.01, respectively). Conclusion In obese patients, the presence of the PNPLA3 p.I148M allele might be associated with greater improvement of hepatic steatosis after bariatric surgery in comparison to carriers of PNPLA3 wild-type alleles. [ABSTRACT FROM AUTHOR]

In the past 2 decades, advances in genetics have improved our understanding of liver disease and physiology. Firstly, developments in genomic technologies drove the identification of genes responsible for monogenic (Mendelian) liver diseases. Over the last decade, genome-wide association studies allowed for the dissection of the genetic susceptibility to complex liver diseases such as fatty liver disease and drug-induced liver injury, in which environmental co-factors play critical roles. The findings have allowed the identification and elaboration of pathophysiological processes, have indicated the need for reclassification of liver diseases and risk factors and have already pointed to new disease treatments. This is illustrated by the interaction of alcohol, overnutrition and the PNPLA3 gene, which represents an 'infernal triangle' for the liver. In the future, genetics will allow further stratification of liver diseases and contribute to personalized (precision) medicine, offering novel opportunities for translational research and clinical care of our patients. [ABSTRACT FROM AUTHOR]

Background Non-alcoholic fatty liver disease ( NAFLD) is becoming the most prevalent liver disorder. The PNPLA3 (adiponutrin) variant p.I148M has been identified as common genetic modifier of NAFLD. Our aim was to assess the relationships between genetic risk and non-invasively measured liver fat content. Methods Hepatic steatosis was quantified by transient elastography, using the controlled attenuation parameter ( CAP) in 174 patients with chronic liver diseases (50% women, age 18-77 years). In addition, a cohort of 174 gender-matched healthy controls (50% women, age 32-77 years) was recruited. The PNPLA3 mutation as well as the novel NAFLD-predisposing genetic variant ( TM6 SF2 p.E167K) were genotyped with allele-specific probes. Results The PNPLA3 genotype correlated significantly ( P = 0.001) with hepatic CAP measurements. The p.148M risk allele increased the odds of developing liver steatosis ( OR = 2.39, P = 0.023). In multivariate models, BMI and PNPLA3 mutation were both independently associated with CAP values ( P < 0.001 and P = 0.007, respectively). Carriers of the TM6 SF2 risk allele presented with increased aminotransferase activities ( ALT: P = 0.007, AST: P = 0.004), but the presence of this variant did not affect CAP values. Conclusions The PNPLA3 p.I148M variant represents the most important prosteatotic genetic risk factor. NAFLD carriers of this variant should be followed up carefully, with elastography and CAP being ideally suited for this purpose. [ABSTRACT FROM AUTHOR]

Background: The adiponutrin (PNPLA3) p.I148M and transmembrane 6 superfamily member 2 (TM6SF2) p.E167K variants represent risk factors for non-alcoholic fatty liver disease (NAFLD). In this study, we assessed the effects of caloric restriction on liver phenotypes in NAFLD patients in relation to the PNPLA3 and TM6SF2 genotypes. Methods: We genotyped both variants in 143 individuals with NAFLD (55 females, age 18-74 years) and 180 controls (85 females, age 33-66 years). Liver steatosis was assessed using the ultrasound- based Hamaguchi score. A 4-month dietetic intervention, consisting of restriction of daily caloric intake without changes in physical activity, was performed. Results: Both PNPLA3 (p = 0.002) and TM6SF2 (p = 0.041) variants were associated with NAFLD before intervention. Overall, 88 patients completed the intervention, which led to a significant decrease of steatosis, ALT activities, body mass index, hip and waist circumferences, and waist-hip ratio (all p < 0.0001). Hepatic steatosis and anthropometric traits improved significantly (p < 0.05) in carriers of either PNPLA3 or TM6SF2 risk genotype. The improvement of phenotypic traits, apart from WHR (p = 0.02), was not modified by the presence of PNPLA3 or TM6SF2 variants. Conclusions: The PNPLA3 and TM6SF2 polymorphisms are associated with NAFLD assessed by the Hamaguchi score. Neither PNPLA3 nor TM6SF2 risk alleles impair the response to dietetic intervention in NAFLD. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome and comprises a liver disease spectrum ranging from steatosis to nonalcoholic steatohepatitis (NASH) with risk of progression to liver cirrhosis and hepatocellular carcinoma (HCC). Associated metabolic conditions and comorbidities such as obesity, diabetes and cardiovascular diseases are common and require concerted management. Adiponutrin (PNPLA3) variants may help to identify NAFLD patients at higher risk for liver disease progression towards advanced fibrosis and HCC. The therapeutic options in NAFLD/NASH include lifestyle modification, pharmacological treatment, bariatric surgery for patients with morbid obesity and treatment of complications of liver cirrhosis and HCC, including liver transplantation. Insulin sensitizers and antioxidative treatment strategies with vitamin E are among the best-established pharmacological approaches, but both drugs have long-term safety issues and there is limited evidence in cirrhotic patients. Treatment of concomitant/underlying metabolic conditions with statins or metformin may also have beneficial effects on portal hypertension, complications of liver cirrhosis and HCC prevention. The bile acid receptor FXR may be a promising novel therapeutic target for the treatment of NAFLD/NASH, fibrosis and portal hypertension, but the prognostic implications of associated changes in low- and high-density lipoprotein cholesterol require further studies. Morbidly obese NASH patients can benefit from bariatric surgery which may reduce liver fibrosis but carries a risk of decompensation in patients with advanced liver cirrhosis. When carefully selected, patients with NASH cirrhosis undergoing liver transplantation have a good outcome. This review summarizes recent progress in the management of patients with liver cirrhosis due to NASH. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background & Aims We aimed to assess the association between the patatin-like phospholipase domain-containing-3 ( PNPLA3) I148M polymorphism, liver histology and long-term outcome in chronic hepatitis B ( CHB) patients. Methods We enrolled 531 consecutive treatment naïve CHB patients diagnosed from 1985 to 2012 with an available liver biopsy for reassessment, and sample for genetic testing. Data on all-cause mortality and hepatocellular carcinoma ( HCC) at long-term follow-up were obtained from national database registries. Results The prevalence of steatohepatitis increased with PNPLA3 CC (14%), CG (20%) and GG (43%) ( P < 0.001). The association was altered by both gender ( P = 0.010) and overweight ( P = 0.015): the effect of PNPLA3 on steatohepatitis was most pronounced among non-overweight females (adjusted OR 13.4, 95% CI: 3.7-51.6, P < 0.001), and non-overweight males (adjusted OR 2.4, 95% CI: 1.4-4.3, P = 0.002). Furthermore, PNPLA3 GG genotype was associated with iron depositions ( OR 2.8, 95% CI: 1.2-6.4, P = 0.014) and lobular inflammation ( OR 2.2, 95% CI: 1.1-4.5, P = 0.032), but not with advanced fibrosis ( OR 1.1, 95% CI: 0.7-1.8, P = 0.566). The median follow-up was 10.1 years (interquartile range 5.6 - 15.8), during which 13 patients developed HCC and 28 died. Steatohepatitis was associated with all-cause mortality [Hazard ratio ( HR) 3.1, 95% CI: 1.3-7.3, P = 0.006] and HCC ( HR 2.8, 95% CI: 0.9-9.2, P = 0.078), but no significant association was observed for PNPLA3. Conclusions In this cohort of biopsied CHB patients, PNPLA3 was independently associated with steatosis, steatohepatitis, lobular inflammation and iron depositions, but not with advanced fibrosis, HCC development or all-cause mortality. The effect of PNPLA3 on steatohepatitis was particularly pronounced among female patients without severe overweight. [ABSTRACT FROM AUTHOR]

The isoleucine to methionine substitution at position 148 in the patatin-like phospholipase domain containing 3 protein (PNPLA3; I148M variant, rs738409) is associated with liver fat accumulation and an increased risk of chronic liver disease ranging from hepatitis to hepatocellular carcinoma. This review discusses the interaction between the PNPLA3 I148M variant and obesity/intake of specific nutrients in determining the susceptibility to liver disease. We present the results of several studies showing that obesity or alcohol abuse enhances the effect of the PNPLA3 I148M variant on the liver. We also show that specific nutrients interact with the PNPLA3 I148M variant in modulating liver disease susceptibility. [ABSTRACT FROM AUTHOR]

Patatin-like phospholipase domain-containing protein 3 (PNPLA3), commonly known as adiponutrin, is part of a novel subfamily of triglyceride lipase enzymes with potential effects on triglyceride metabolism in adipose and hepatic tissues. The predicted bovine PNPLA3 sequence has been identified, but expression of the gene had not been examined. The objectives of this study were to confirm the predicted bovine PNPLA3 gene sequence, determine expression of the bovine PNPLA3 gene in response to whole-animal energy balance, identify single nucleotide polymorphisms present in dairy cows, and verify the presence of the protein in the liver. Using liver biopsy samples collected from cows at +28 d relative to calving (DRTC), RNA was isolated and used to generate a cDNA template for amplification of the entire predicted coding sequence of PNPLA3 via PCR. To determine if energy balance alters the expression of PNPLA3, RNA was isolated and mRNA expression quantified in liver samples from mid-lactation cows after a 5-d ad libitum period (n = 5) and after a subsequent 5-d 50% feed restriction period (n = 5), and in samples collected from cows at -- 14, +1, +14, and +28 DRTC (n = 16). The presence of PNPLA3 protein was detected by Western blot in liver protein samples collected at +28 DRTC. Expression of hepatic PNPLA3 was decreased after a period of feed restriction (8.14 vs. 1.08 ± 2.17 arbitrary units, ad libitum vs. fasted). Expression of PNPLA3 mRNA was decreased at +1 and +14 DRTC compared with -14 DRTC (23.35, 7.28, 10.17, and 14.5 ± 4.9 arbitrary units, -14, +1, +14, and +28 DRTC, respectively). The presence of PNPLA3 protein was detected as a 55-kDa band in hepatic protein isolations from liver tissue collected at +28 DRTC. These data confirm the presence and sequence of the bovine hepatic PNPLA3 gene and single nucleotide polymorphisms. Furthermore, these data indicate responsiveness of bovine hepatic PNPLA3 to energy balance. [ABSTRACT FROM AUTHOR]

Highlights: [•] Human adiponutrin is present in plasma as disulfide bond-dependent multimers. [•] Human plasma adiponutrin circulates in the low nM range, estimated to 1.25–4nM. [•] Adiponutrin is secreted by HepG2 cells in the presence of oleate. [Copyright &y& Elsevier]