Patatin-like Phospholipase Domain-containing Research Articles

PNPLA3(148M) is a gain-of-function mutation that promotes hepatic steatosis by inhibiting ATGL-mediated triglyceride hydrolysis.

PNPLA3(148M) (patatin-like phospholipase domain-containing protein 3) is the most impactful genetic risk factor for steatotic liver disease (SLD). A key unresolved issue is whether PNPLA3(148M) confers a loss- or gain-of-function. Here we test the hypothesis that PNPLA3 causes steatosis by sequestering ABHD5 (α/β hydrolase domain containing protein 5), the cofactor of ATGL (adipose TG lipase), thus limiting mobilization of hepatic triglyceride (TG). We quantified and compared the physical interactions between ABHD5 and PNPLA3/ATGL in cultured hepatocytes using NanoBiT complementation assays and immunocytochemistry. Recombinant proteins purified from human cells were used to compare TG hydrolytic activities of PNPLA3 and ATGL in the presence or absence of ABHD5. Adenoviruses and adeno-associated viruses were used to express PNPLA3 in liver-specific Atgl-/- mice and to express ABHD5 in livers of Pnpla3M/M mice, respectively. ABHD5 interacted preferentially with PNPLA3 relative to ATGL in cultured hepatocytes. No differences were seen in the strength of the interactions between ABHD5 with PNPLA3(WT) and PNPLA3(148M). In contrast to prior findings, we found that PNPLA3, like ATGL, is activated by ABHD5 in in vitro assays using purified proteins. PNPLA3(148M)-associated inhibition of TG hydrolysis required that ATGL be expressed and that PNPLA3 be located on LDs. Finally, overexpression of ABHD5 reversed the hepatic steatosis in Pnpla3M/M mice. These findings support the premise that PNPLA3(148M) is a gain-of-function mutation that promotes hepatic steatosis by accumulating on LDs and inhibiting ATGL-mediated lipolysis in an ABHD5-dependent manner. Our results predict that reducing, rather that increasing, PNPLA3 expression will be the best strategy to treat PNPLA3(148M)-associated SLD. Steatotic liver disease (SLD) is a common complex disorder associated with both environmental and genetic risk factors. PNPLA3(148M) is the most impactful genetic risk factor for SLD and yet its pathogenic mechanism remains controversial. Here we provide evidence that PNPLA3(148M) promotes triglyceride (TG) accumulation by sequestering ABHD5, thus limiting its availability to activate ATGL. Although the substitution of methionine for isoleucine reduces the TG hydrolase activity of PNPLA3, the loss of enzymatic function is not directly related to the steatotic effect of the variant. It is the resulting accumulation of PNPLA3 on LDs that confers a gain-of-function by interfering with ATGL-mediated TG hydrolysis. These findings have implications for the design of potential PNPLA3(148M)-based therapies. Reducing, rather than increasing, PNPLA3 levels is predicted to reverse steatosis in susceptible individuals.

Significance of the influence of patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 polymorphism on non alcoholic fatty liver disease

Significance of the influence of patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 polymorphism on non alcoholic fatty liver disease

Ambient air pollution exposure is associated with liver fat and stiffness in Latino youth with a more pronounced effect in those with PNPLA3 genotype and more advanced liver disease

BackgroundExposure to ambient air pollutants has emerged as a risk for metabolic-dysfunction associated steatotic liver disease (MASLD). ObjectivesWe sought to examine associations between short-term (prior month) and long-term (prior year) ambient air pollution exposure with hepatic fat fraction (HFF) and liver stiffness in Latino youth with obesity. A secondary aim was to investigate effect modification by patatin-like phospholipase domain-containing protein 3 (PNPLA3) genotype and liver disease severity. MethodsData was analyzed from 113 Latino youth (age 11–19) with obesity in Southern California. Individual exposure to particulate matter with aerodynamic diameter ≤ 2.5μm (PM2.5), ≤ 10μm (PM10), nitrogen dioxide (NO2), 8-hour maximum ozone (8hrMax-O3), 24-hr O3, and redox-weighted oxidative capacity (Oxwt) were estimated using residential address histories and United States Environmental Protection Agency air quality observations. HFF and liver stiffness were measured using magnetic resonance imaging. Linear models were used to determine associations between short-term and long-term exposure to air pollutants with HFF and liver stiffness. Modification by PNPLA3 and liver disease severity was then examined. ResultsShort-term exposure to 8hrMax-O3 was positively associated with HFF. Relationships between air pollution exposure and HFF were not impacted by PNPLA3 genotype or liver disease severity. Long-term exposure to 8hrMax-O3 and Oxwt were positively associated with liver stiffness. Associations between air pollution exposure and liver stiffness depended on PNPLA3 genotype, such that individuals with GG genotypes exhibited stronger, more positive relationships between short-term exposure to PM10, 8hrMax-O3, 24-hr O3, and Oxwt and liver stiffness than individuals with CC/CG genotypes. In addition, relationships between short-term exposure to NO2 and liver stiffness were stronger in those with severe liver disease. DiscussionAir pollution exposure may be a risk factor for liver disease among Latino youth with obesity, particularly in those with other preexisting risks for liver damage.

Role of PNPLA3 in Hepatic Stellate Cells and Hepatic Cellular Crosstalk.

Since its discovery, the patatin-like phospholipase domain containing 3 (PNPLA3) (rs738409 C>G p.I148M) variant has been studied extensively to unravel its molecular function. Although several studies proved a causal relationship between the PNPLA3 I148M variant and MASLD development and particularly fibrosis, the pathological mechanisms promoting this phenotype have not yet been fully clarified. We summarise the latest data regarding the PNPLA3 I148M variant in hepatic stellate cells (HSCs) activation and macrophage biology or the path to inflammation-induced fibrosis. Elegant but contradictory studies have ascribed PNPLA3 a hydrolase or an acyltransferase function. The PNPLA3 I148M results in hepatic lipid accumulation, which predisposes the hepatocyte to lipotoxicity and lipo-apoptosis, producing DAMPs, cytokines and chemokines leading to recruitment and activation of macrophages and HSCs, propagating fibrosis. Recent studies showed that the PNPLA3 I148M variant alters HSCs biology via attenuation of PPARγ, AP-1, LXRα and TGFβ activity and signalling. The advent of refined techniques in isolating HSCs has made PNPLA3's direct role in HSCs for liver fibrosis development more apparent. However, many other mechanisms still need detailed investigations.

6428 Update on Genetic F6428 actors of Nonalcoholic Fatty Liver Disease

Abstract Disclosure: H.M. Heshmati: None. Background: Nonalcoholic fatty liver disease (NAFLD) is a pandemic with a prevalence of 25% among the adult population worldwide. NAFLD is a spectrum of liver disorders ranging from simple steatosis to nonalcoholic steatohepatitis (NASH). NASH can progress to cirrhosis and hepatocellular cancer. The pathogenesis of NAFLD is complex and multifactorial, involving metabolic, epigenetic, and genetic factors. Several medical conditions (e.g., obesity, type 2 diabetes, inflammation, insulin resistance, disrupted gut microbiome, and impaired intestinal barrier function) are important risk factors associated with and/or contributing to NAFLD. This review presents an update on the genetic factors of NAFLD identified by the genome-wide association studies (GWAS). Methods: A systematic search of literature was conducted using the search terms nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, cirrhosis, hepatocellular cancer, obesity, type 2 diabetes, epigenetics, and genetics. Results: Evidence for the contribution of genetic factors to NAFLD is further emphasized by the ethnic differences in the prevalence of NAFLD (e.g., higher prevalence among Hispanic American compared to African American adults). Based on the results of the GWAS, several genetic modifiers are relevant to NAFLD development and progression. They include variations in patatin-like phospholipase domain-containing protein 3 (PNPLA3), transmembrane 6 superfamily 2 (TM6SF2), membrane-bound O-acyltransferase domain-containing protein 7 (MBOAT7), glucokinase regulatory protein (GCKR), programmed cell death protein 1 (PDCD1), and hydroxysteroid 17β-dehydrogenase 13 (HSD17B13) genes (non-exhaustive list). These genetic modifiers interact with the metabolic and epigenetic factors for the development and progression of NAFLD and are responsible for the variability in the severity of NAFLD. The PNPLA3 gene variant (rs738409), which is the first and the best validated genetic modifier, is associated with a high risk of development and progression of NAFLD. The PDCD1 gene variant (rs7421861) is independently associated with hepatocellular cancer development. In contrast, the HSD17B13 gene variant (rs72613567) may have a protective effect for NAFLD risk. Conclusion: NAFLD is a multifactorial condition with a complex pathogenesis involving the interactions between metabolic, epigenetic, and genetic factors. The prevalence and risk of NAFLD differ across populations mainly due to genetic polymorphisms. Genetic factors relevant to NAFLD include variations in PNPLA3, TM6SF2, MBOAT7, GCKR, PDCD1, and HSD17B13 genes. A better understanding of these genetic modifiers and their mechanisms of action should allow a better risk prediction of the development of NAFLD and its progression to cirrhosis and hepatocellular cancer and help the development of new and selected therapies for NAFLD. Presentation: 6/3/2024

Role of patatin-like phospholipase domain-containing 3 gene for decreasing kidney function in recently diagnosed diabetes mellitus

AimsWe examined the association of the G allele in the single-nucleotide polymorphism (SNP) rs738409 in the third exon of patatin-like phospholipase domain-containing 3 gene (PNPLA3) gene, with chronic kidney disease in diabetes endotypes. MethodsParticipants with recent-onset diabetes (n=707) from the prospective German Diabetes Study (GDS) underwent cluster assignment, detailed phenotyping, genotyping and magnetic resonance spectroscopy to quantify hepatocellular lipid content (HCL). ResultsSevere insulin-resistant diabetes (SIRD) had the lowest glomerular filtration rates (eGFR) and highest HCL compared to severe insulin-deficient, moderate obesity-related, moderate age-related and severe autoimmune diabetes endotypes (all p<0.05). HCL was negatively associated with eGFR (r=-0.287, p<0.01) across all groups. Stratification by G-allele carrier status did not reveal any association between HCL and eGFR among the endotypes. However, the proportion of G-allele carriers increased from 44% for eGFR >60 ml/min to 52% for eGFR <60 ml/min (p<0.05). ConclusionsThe PNPLA3 polymorphism may contribute to declining kidney function independently of liver lipids.

Glycaemic control metrics and metabolic dysfunction-associated steatotic liver disease in children and adolescents with type 1 diabetes.

The aim was to examine the prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD), a risk factor for atherosclerotic cardiovascular disease, and its association with glycaemic control metrics in children and adolescents with type 1 diabetes (T1D). We enrolled 244 children and adolescents with T1D (115 girls, mean age: 16.2 ± 3.2 years). The diagnosis of MASLD was defined by the presence of hepatic steatosis on ultrasonography in combination with at least one of five common cardiometabolic risk factors. Metrics of short-term and long-term glycaemic control, blood pressure, lipids, anthropometric characteristics and three genetic variants strongly related to MASLD susceptibility (rs738409 [patatin-like phospholipase domain-containing 3], rs58542926 [transmembrane 6 superfamily member 2] and rs1260326 [glucokinase regulator]) were assessed. Characteristics of these subjects with and without MASLD were compared using the unpaired Student t test, Mann-Whitney test or χ2 test as appropriate. Logistic regression analyses were performed to determine the main independent predictors of MASLD. The prevalence of MASLD was 27.5% in children and adolescents with T1D. Blood pressure, total cholesterol, low-density lipoprotein (LDL) cholesterol, non-high-density lipoprotein cholesterol, HbA1c and time above range (TAR) were significantly higher in subjects with MASLD than in those without MASLD. Mean HbA1c values from diabetes onset (adjusted odds ratio [OR]: 1.703, 95% confidence interval [CI]: 1.040-2.787, p = 0.034), TAR (adjusted OR: 1.028, 95% CI: 1.009-1.047, p = 0.006) and plasma LDL cholesterol (adjusted OR: 1.045, 95% CI: 1.013-1.078, p = 0.004) were independently associated with the presence of MASLD. MASLD is a common condition in children and adolescents with T1D. The mean HbA1c values from diabetes onset, TAR and LDL cholesterol levels were the independent predictors of MASLD.

Non-alcoholic fatty liver disease: Genetic susceptibility

The prevalence of Non-alcoholic Fatty Liver Disease (NAFLD) is increasing, particularly in individuals who consume minimal to no alcohol. Currently, NAFLD affects at least 32% of the global population. Although not all but approximately 5-10% cases of NAFLD progress to non-alcoholic steatohepatitis (NASH), a condition arising from lipotoxicity. Patients with NASH may further develop liver fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). However, it is important to note that progression from NAFLD to NASH and HCC is not inevitable for all patients. The pathogenesis of HCC in the context of NAFLD and NASH remains poorly understood, however, fat accumulation, often due to obesity or metabolic syndrome, leads to lipotoxicity. In individuals with type 2 diabetes (T2D), elevated insulin levels promote lipolysis in adipose tissue and activate lipid-synthesizing enzymes such as fatty acid synthase (FAS) and stearoyl-CoA desaturase 1 (SCD1), which contribute to lipid accumulation in the liver. Additionally, high glucose levels in T2D can alter gene regulation by activating carbohydrate response-element binding protein (ChREBP) and insulin can increase the activity of sterol regulatory element binding protein (SREBP-1c). These lipogenic transcription factors are known to directly or indirectly activate patatin-like phospholipase domain-containing protein 3 (PNPLA3). Recent research has found elevated levels of angiotensinogen (AGT) and des-angiotensin in both experimental animals and patients with NAFLD. Emerging evidence highlights the significance of genetic factors in the risk of developing NAFLD. Here we explore the association between specific genes and hepatosteatosis, detailing the roles of T2D and obesity in the progression from NAFLD to NASH, and involvement of hepatic stellate cells in liver fibrosis. Additionally, we examine the impact of genes such as PNPLA3, MBOAT7, TM6SF2, GKRP, CCN3, and AGT as well as role of single nucleotide polymorphisms in gene regulation and their contribution to the risk of NAFLD.

Sex-specific effects of PNPLA3 I148M.

Metabolic dysfunction-associated steatotic liver disease (MASLD, previously termed NAFLD, nonalcoholic fatty liver disease) is a complex multifactorial disease showing generally higher prevalence and severity in men than in women. With respect to women, men are also more prone to develop metabolic dysfunction-associated steatohepatitis, fibrosis and liver-related complications. Several genetic, hormonal, environmental and lifestyle factors may contribute to sex differences in MASLD development, progression and outcomes. However, after menopause, the sex-specific prevalence of MASLD shows an opposite trend between men and women, pointing to the relevance of oestrogen signalling in the sexual dimorphism of MASLD. The patatin-like phospholipase domain-containing protein 3 (PNPLA3) gene, that encodes a triacylglycerol lipase that plays a crucial role in lipid metabolism, has emerged as a key player in the pathogenesis of MASLD, with the I148M variant being strongly associated with increased liver fat content and disease severity. Recent advances indicate that carrying the PNPLA3 I148M variant can be a risk factor for MASLD especially for women. To elucidate the molecular mechanisms underlying the sex-specific role of PNPLA3 I148M in the development of MASLD, several invitro, exvivo and invivo models have been developed.

MiR-206 Suppresses Triacylglycerol Accumulation via Fatty Acid Elongase 6 in Dairy Cow Mammary Epithelial Cells.

Cow milk possesses high nutritional value due to its rich array of beneficial fatty acids. It is important to understand the mechanisms involved in lipid metabolism in dairy cows. These mechanisms are driven by a complex molecular regulatory network. In addition, there are many regulatory factors involved in the process of fatty acid metabolism, including transcription factors and non-coding RNAs, amongst others. MicroRNAs (miRNAs) can regulate the expression of target genes and modulate various biological processes, including lipid metabolism. Specifically, miR-206 has been reported to impair lipid accumulation in nonruminant hepatocytes. However, the effects and regulatory mechanisms of miR-206 on lipid metabolism in bovine mammary cells remain unclear. In the present study, we investigated the effects of miR-206 on lipid-related genes and TAG accumulation. The direct downstream gene of miR-206 was subsequently determined via a dual-luciferase assay. Finally, the fatty acid content of bovine mammary epithelial cells (BMECs) upon ELOVL6 inhibition was examined. The results revealed that miR-206 overexpression significantly decreased triacylglycerol (TAG) concentration and abundances of the following: acetyl-coenzyme A carboxylase alpha (ACACA); fatty acid synthase (FASN); sterol regulatory element binding transcription factor 1 (SREBF1); diacylglycerol acyltransferase 1 (DGAT1); 1-acylglycerol-3-phosphate O-acyltransferase 6 (AGPAT6); lipin 1 (LPIN1); and fatty acid elongase 6 (ELOVL6). Overexpression of miR-206 was also associated with an increase in patatin-like phospholipase domain-containing 2 (PNPLA2), while inhibition of miR-206 promoted milk fat metabolism in vitro. In addition, we found that ELOVL6 is a direct target gene of miR-206 through mutation of the binding site. Furthermore, ELOVL6 intervention significantly decreased the TAG levels and elongation indexes of C16:0 and C16:1n-7 in BMECs. Finally, ELOVL6 siRNA partially alleviated the increased TAG accumulation caused by miR-206 inhibition. In summary, we found that miR-206 inhibits milk fatty acid synthesis and lipid accumulation by targeting ELOVL6 in BMECs. The results presented in this paper may contribute to the development of strategies for enhancing the quality of cow milk and its beneficial fatty acids, from the perspective of miRNA-mRNA networks.

Vliv polymorfizmů PNPLA3 rs738409 a TM6SF2 rs58542926 dárce a příjemce na dlouhodobé přežívání pacientů po transplantaci jater

Summary Introduction: The variants rs738409 c.444C&gt;G (p.I148M) in patatin-like phospholipase domain-containing 3 (PNPLA3) and rs58542926 c.499G&gt;A (p.E167K) in TM6SF2 (transmembrane 6 superfamily member 2) are significant genetic risk factors of development and progression of non-alcoholic fatty liver disease (NAFLD). In both variants, increased liver-specific mortality was described, while the impact on all-cause mortality was not proved. The aim of the study was to evaluate the impact of PNPLA3 rs738409 and TM6SF2 rs58542926 genotypes of the donor and recipient respectively on long-term patient survival after LT. Methods: We evaluated long-term patient survival in a cohort of 268 adult LT recipients, in whom PNPLA3 rs738409 and TM6SF2 rs58542926 genotypes of the donor and recipient respectively were available and steatosis was evaluated in liver graft biopsy 6–30 months after LT. The median fol low-up was 17 years. The Kaplan-Meier model was used for the survival estimates and the Cox proportional hazard model was used to assess the predictive value of the chosen variables. Results: Increased recipient age (P &lt; 0.001), male sex (P = 0.014), alcoholic (P = 0.021) or HCV (P = 0.042) etiology of liver cirrhosis, and presence of hepatocellular carcinoma (P = 0.009) negatively influenced long-term patient survival after LT. PNPLA3 rs738409 and TM6SF2 rs58542926 genotypes of the recipient and donor respectively had no effect on patient survival. Conclusion: Although PNPLA3 c.444G and TM6SF2 c.499A variants of the donor increase the risk of steatosis of the liver graft after LT, we did not prove a negative impact of these genotypes of the donor and recipient on long-term patient survival after LT. Keywords PNPLA3, TM6SF2, steatosis, MASLD, NAFLD, liver transplantation, patient survival

Investigation on the mechanism of hepatotoxicity of dictamnine on juvenile zebrafish by integrating metabolomics and transcriptomics

Dictamnine(DIC), as the key pharmacological component of the classical Chinese herbal medicine cortex dictamni, possesses multiple pharmacological activities such as anti-microbial, anti-allergic, anti-cancer, and anti-inflammatory activities, however it is also the main toxicant of cortex dictamni induced hepatic damage, yet the underlying molecular mechanisms causing hepatic damage are still largely unknown. With the purpose of explore possibilities hepatotoxicity of dictamnine in zebrafish and to identify the key regulators and metabolites involved in the biological process, we administered zebrafish to dictamnine at a sub-lethal dose (<LC10) for 24 h and performed biochemical index tests, pathological observations, metabolomics, and transcriptomics analyses. The results showed that the liver function indexes such as ALT and AST were affected after the exposure treatment with dictamnine, and the hepatic damage, lipid droplet formation, and increased apoptosis were observed in zebrafish by HE, oil red O(ORO), and Acridine orange hydrochloride(AO)staining. Transcriptome sequencing analysis showed that dictamnine exposure could generate 5696 down-regulated and 4936 up-regulated DEGs(Differential Expressed Genes); metabolomics analysis showed that 36 potential biomarkers were disturbed by dictamnine exposure treatment in juvenile zebrafish. Integration of metabolomics data and transcriptomics data showed that Patatin like phospholipase domain containing 3 Gene Patatin Like Phospholipase Domain Containing 3(PNPLA3), Lactase Gene(LCT), and Galactosidase Beta 1(GLB1) genes were involved in the regulation of 12 key potential biomarkers related to Galactose metabolism and Glycerophospholipid metabolism, such as LysoPC(16:0/0:0) and UDP-4-dehydro-6-deoxy-D-glucose, which in turn regulated pathways of Galactose metabolism and Glycerophospholipid metabolism and consequently induced hepatotoxicity. The comprehensive evaluation of the hepatotoxicity induced by dictamnine was realized from multiple levels, perspectives and indexes by the integrated evaluation method of zebrafish modeling, which supported the applicability of zebrafish in the evaluation of hepatotoxicity of traditional Chinese medicine, and supplied the scientific basis for elucidating the molecular mechanism of the hepatotoxicity induced by dictamnine, as well as guided the development of the toxicity-reducing therapies by dictamnine in the future.

Biallelic null variants in PNPLA8 cause microcephaly by reducing the number of basal radial glia.

Patatin-like phospholipase domain-containing lipase 8 (PNPLA8), one of the calcium-independent phospholipase A2 enzymes, is involved in various physiological processes through the maintenance of membrane phospholipids. Biallelic variants in PNPLA8 have been associated with a range of paediatric neurodegenerative disorders. However, the phenotypic spectrum, genotype-phenotype correlations and the underlying mechanisms are poorly understood. Here, we newly identified 14 individuals from 12 unrelated families with biallelic ultra-rare variants in PNPLA8 presenting with a wide phenotypic spectrum of clinical features. Analysis of the clinical features of current and previously reported individuals (25 affected individuals across 20 families) showed that PNPLA8-related neurological diseases manifest as a continuum ranging from variable developmental and/or degenerative epileptic-dyskinetic encephalopathy to childhood-onset neurodegeneration. We found that complete loss of PNPLA8 was associated with the more profound end of the spectrum, with congenital microcephaly. Using cerebral organoids generated from human induced pluripotent stem cells, we found that loss of PNPLA8 led to developmental defects by reducing the number of basal radial glial cells and upper-layer neurons. Spatial transcriptomics revealed that loss of PNPLA8 altered the fate specification of apical radial glial cells, as reflected by the enrichment of gene sets related to the cell cycle, basal radial glial cells and neural differentiation. Neural progenitor cells lacking PNPLA8 showed a reduced amount of lysophosphatidic acid, lysophosphatidylethanolamine and phosphatidic acid. The reduced number of basal radial glial cells in patient-derived cerebral organoids was rescued, in part, by the addition of lysophosphatidic acid. Our data suggest that PNPLA8 is crucial to meet phospholipid synthetic needs and to produce abundant basal radial glial cells in human brain development.

A PNPLA3-Deficient iPSC-Derived Hepatocyte Screen Identifies Pathways to Potentially Reduce Steatosis in Metabolic Dysfunction-Associated Fatty Liver Disease.

The incidence of nonalcoholic fatty liver disease (NAFLD), or metabolic dysfunction-associated fatty liver disease (MAFLD), is increasing in adults and children. Unfortunately, effective pharmacological treatments remain unavailable. Single nucleotide polymorphisms (SNPs) in the patatin-like phospholipase domain-containing protein (PNPLA3 I148M) have the most significant genetic association with the disease at all stages of its progression. A roadblock to identifying potential treatments for PNPLA3-induced NAFLD is the lack of a human cell platform that recapitulates the PNPLA3 I148M-mediated onset of lipid accumulation. Hepatocyte-like cells were generated from PNPLA3-/- and PNPLA3I148M/M-induced pluripotent stem cells (iPSCs). Lipid levels were measured by staining with BODIPY 493/503 and were found to increase in PNPLA3 variant iPSC-derived hepatocytes. A small-molecule screen identified multiple compounds that target Src/PI3K/Akt signaling and could eradicate lipid accumulation in these cells. We found that drugs currently in clinical trials for cancer treatment that target the same pathways also reduced lipid accumulation in PNPLA3 variant cells.

PNPLA3 variation and kidney disease.

Accumulating epidemiological evidence shows that the patatin-like phospholipase domain-containing protein-3 (PNPLA3) rs738409 G allele, which is the most robust genetic variant associated with greater susceptibility to metabolic dysfunction-associated steatotic liver disease (MASLD), is significantly associated with impaired kidney function in both adults and children, regardless of the presence of common renal risk factors, MASLD severity, and other potential confounders. Although some prospective studies have reported a significant association between the PNPLA3 rs738409 G allele and the increased risk of developing chronic kidney disease (CKD), the epidemiological evidence about a possible direct effect of the PNPLA3 rs738409 G allele on the risk of developing CKD is still limited. Experimentally, PNPLA3 is expressed in renal podocytes, pericytes, and proximal tubule cells, thus supporting the notion that the mutant PNPLA3 protein may play a role in developing renal steatosis and fibrosis. However, it cannot be ruled out that a part of the adverse effect of the PNPLA3 rs738409 G allele on kidney function may be driven by a direct impact of this genetic variant on the development and progression of MASLD. It is possible to hypothesize that identifying the PNPLA3 genotype might help identify individuals at higher risk of CKD and those at greater risk of advanced MASLD. In this narrative minireview, we summarize the current epidemiological data about the association between the PNPLA3 rs738409 G allele and the risk of CKD and abnormal albuminuria. We also briefly discuss the putative biological mechanisms underpinning this association and its potential and future clinical implications.

Evidence That Peripheral Leptin Resistance in Omental Adipose Tissue and Liver Correlates with MASLD in Humans.

Leptin regulates lipid metabolism, maximizing insulin sensitivity; however, peripheral leptin resistance is not fully understood, and its contribution to metabolic dysfunction-associated steatotic liver disease (MASLD) is unclear. This study evaluated the contribution of the leptin axis to MASLD in humans. Forty-three participants, mostly female (86.04%), who underwent cholecystectomy were biopsied. Of the participants, 24 were healthy controls, 8 had MASLD, and 11 had metabolic dysfunction-associated steatohepatitis (MASH). Clinical and biochemical data and the gene expression of leptin, leptin receptor (LEPR), suppressor of cytokine signaling 3 (SOCS3), sterol regulatory element-binding transcription factor 1 (SREBF1), stearoyl-CoA desaturase-1 (SCD1), and patatin-like phospholipase domain-containing protein 2 (PNPLA2), were determined from liver and adipose tissue. Higher serum leptin and LEPR levels in the omental adipose tissue (OAT) and liver with MASH were found. In the liver, LEPR was positively correlated with leptin expression in adipose tissue, and SOCS3 was correlated with SREBF1-SCD1. In OAT, SOCS3 was correlated with insulin resistance and transaminase enzymes (p < 0.05 for all. In conclusion, we evidenced the correlation between the peripheral leptin resistance axis in OAT-liver crosstalk and the complications of MASLD in humans.

Are transmembrane 6 superfamily member 2 gene polymorphisms associated with steatohepatitis after pancreaticoduodenectomy?

After pancreaticoduodenectomy, 20-40% of patients develop steatotic liver disease (SLD), and steatohepatitis can be a problem. Although patatin-like phospholipase domain-containing 3 protein (PNPLA3) and transmembrane 6 superfamily member 2 (TM6SF2) polymorphisms are involved in SLD and steatohepatitis development, whether this is the case after pancreaticoduodenectomy is unclear. Forty-three patients with pancreatic cancer who underwent pancreaticoduodenectomy at our hospital between April 1, 2018, and March 31, 2021, were included. We extracted DNA from noncancerous areas of residual specimens after pancreaticoduodenectomy and determined PNPLA3 and TM6SF2 gene polymorphisms using real-time polymerase chain reaction. SLD was defined as a liver with an attenuation value of ≤40 HU or a liver-to-spleen ratio of ≤0.9 on computed tomography. We defined high hepatic fibrosis indexes (HFI) instead of steatohepatitis as a Fibrosis-4 index of ≥2.67 or nonalcoholic fatty liver disease fibrosis score of ≥0.675 in patients with SLD. The cumulative incidence of SLD (P = 0.299) and high HFI (P = 0.987) after pancreaticoduodenectomy were not significantly different between the PNPLA3 homozygous and minor allele groups. The incidences of high HFI at 1 year after pancreaticoduodenectomy were 16.8% and 27.0% in the TM6SF2 major homozygous and minor allele groups, respectively, with a significant difference in the cumulative incidence (P = 0.046). The TM6SF2 minor allele may contribute to steatohepatitis development after pancreaticoduodenectomy.

THU-206 Deep learning-based predictive modeling of patatin-like phospholipase domain-containing protein 3 variant carriers using magnetic resonance imaging data

THU-206 Deep learning-based predictive modeling of patatin-like phospholipase domain-containing protein 3 variant carriers using magnetic resonance imaging data

The health care experience of adults with metabolic dysfunction-associated steatohepatitis and influence of PNPLA3: A qualitative study.

Metabolic dysfunction-associated steatohepatitis (MASH) is a progressive form of metabolic dysfunction-associated steatotic liver disease, for which there is limited information about patient experience, including the patient journey. In this study, we conducted interviews with patients with MASH to qualitatively evaluate the patient journey and help elucidate the experiences of this patient population. We also investigated if the patatin-like phospholipase domain-containing protein 3 (PNPLA3) I148M variant (non-Hispanic) or being of Hispanic ethnicity may influence patient experiences because these 2 subgroups develop advanced liver disease more frequently than other patient groups. One-to-one interviews were conducted with 28 adults (with PNPLA3 I148M genetic variant, n = 10; Hispanic, n = 8) living in the United States who had been diagnosed with MASH with liver fibrosis. Patients were asked open-ended questions about their experiences before, at, and after their diagnosis. The data collected found that patients experienced a long process of misdiagnoses before their diagnosis of MASH, a lack of clear information provided by clinicians, and limited accessibility to support groups. Hispanic patients reported "impact on family/friends" (75%) and "fear of disease progression" (75%) more frequently than the other patient cohorts interviewed. This is the first report of "fear of progression" in patients with MASH. No patients who were White and had the PNPLA3 I148M variant reported nausea/vomiting, in contrast to other patient cohorts. This qualitative study identified key aspects of the patient journey that are important for clinical providers and medical teams to recognize. We also propose a new algorithm that could be developed to help screen relatives of patients who are found to carry the PNPLA3 I148M variant.

Metabolomics biomarkers of hepatocellular carcinoma in a prospective cohort of patients with cirrhosis

Background & AimsThe effectiveness of surveillance for hepatocellular carcinoma (HCC) in patients with cirrhosis is limited, due to inadequate risk stratification and suboptimal performance of the screening modalities. MethodsWe developed a multicenter prospective cohort of cirrhotic patients undergoing surveillance with MRI, and applied global untargeted metabolomics to 612 longitudinal serum samples from 203 patients. Among them, 37 developed HCC during follow-up. ResultsWe identified 150 metabolites with significant abundance changes in samples collected prior to HCC (Cases) compared to samples from patients who didn’t develop HCC (Controls). Tauro-conjugated bile acids and gamma-glutamyl amino acids were increased, while acyl-cholines and deoxycholate derivatives were decreased. Seven amino acids including serine and alanine, had strong associations with HCC risk, while strong protective effects were observed for N-acetylglycine and glycerophosphorylcholine. Machine learning using the 150 metabolites, age, gender, patatin-like phospholipase domain-containing protein 3 (PNPLA3) and transmembrane 6 superfamily member 2 (TMS6SF2) SNPs, identified 15 variables giving optimal performance. Among them, N-acetylglycine had the highest AUC in discriminating Cases and Controls. When restricting Cases to samples collected within 1 year prior to HCC (Cases-12M), additional metabolites including microbiota-derived metabolites were identified. The combination of the top 6 variables identified by machine learning (alpha-fetoprotein, 6-bromotryptophan, N-acetylglycine, salicyluric glucuronide, testosterone sulfate and age) had good performance in discriminating Cases-12M from Controls (AUC=0.88 [0.83-0.93]). Finally, 23 metabolites distinguished Cases with Liver Imaging Reporting and Data System (LI-RADS)-3 lesions from Controls with LI-RADS-3 lesions, with reduced abundance of acyl-cholines and glycerophosphorylcholine-related lysophospholipids in Cases-LR3. ConclusionsThis study identified N-acetylglycine, amino acids, bile acids and choline-derived metabolites as main biomarkers of HCC risk, and microbiota-derived metabolites as main contributors to HCC development. Impact and ImplicationsThe effectiveness of surveillance for hepatocellular carcinoma (HCC) in patients with cirrhosis is limited. There is an urgent need for improvement in risk stratification and new screening modalities, blood biomarkers in particular. Longitudinal collection of paired blood samples and MRI images from cirrhotic patients is particularly valuable in assessing how early blood and imaging markers become positive during the period when lesions are observed to obtain a diagnosis of HCC. We generated a multicenter prospective cohort of patients with cirrhosis under surveillance with contrast MRI, applied untargeted metabolomics on 612 serum samples from 203 patients and identified metabolites associated with risk of HCC development. Such biomarkers may significantly improve early stage HCC detection for cirrhotic patients undergoing HCC surveillance, a critical step to increasing curative treatment opportunities and reducing mortality.