Association between PNPLA3 rs738409 variant and 5-year estimated glomerular filtration rate decline in post-menopausal women with type 2 diabetes: A panel-data analysis

The extrahepatic markers in postmenopausal women with metabolic dysfunction-associated steatotic liver disease: A systematic review

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent, multifactorial systemic metabolic disorder, now recognized as the most common chronic liver disease globally. Female susceptibility to MASLD varies across menstrual states, influenced by genetic factors, age, menopausal status, and physical activity. Postmenopausal women, experiencing a significant reduction in estrogen, are particularly vulnerable to metabolic imbalances, increasing their risk of MASLD, disease progression, liver fibrosis, insulin resistance, and adverse cardiovascular events compared to premenopausal women and age-matched men. This review systematically synthesizes current research on extrahepatic abnormalities associated with MASLD in postmenopausal women. This review identifies key extrahepatic markers associated with MASLD in postmenopausal women, highlighting gaps in current research and proposing targeted screening and management strategies. (Graphical Abstract).

Impact of PNPLA3 I148M on Clinical Outcomes in Patients With MASLD

BACKGROUND AND AIMS

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a heterogenous clinical and histopathological entity, where multiple metabolic co-factors are intertwined with high interindividual variability. The impact and severity of each factor (including obesity and type 2 diabetes) define a systemic dysmetabolism that can lead to either advanced liver disease and its complication (including hepatocellular carcinoma and clinical events related to portal hypertension) or extrahepatic events: incident cardiovascular disease, chronic kidney disease and extrahepatic cancers. The balance between environmental factors and genetic susceptibility has unique implications in MASLD: the intermittent injury of metabolic co-factors, their fluctuation over time and their specific management, are counterbalanced by the presence of gene variants that can significantly impact the disease at multiple levels. The I148M variant in the PNPLA3 gene is the most investigated genetic susceptibility that induces a more severe steatohepatitis, enhanced fibrogenesis and can shape the incidence of long-term clinical events regardless of, or worsened by, other metabolic risk factors.

METHODS AND RESULTS

In this review, we will summarise the updated evidence on the natural history of MASLD accounting for classical metabolic risk factors, the role of PNPLA3 in clinical sub-phenotyping (e.g., 'lean MASLD'), impact on disease severity and fibrosis progression, as well as its role for prognostication, alone or in combination with non-invasive tools into polygenic risk scores.

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.

PNPLA3 as a driver of steatotic liver disease: navigating from pathobiology to the clinics via epidemiology

Steatotic liver disease (SLD), particularly metabolic dysfunction-associated SLD, represents a significant public health concern worldwide. Among the various factors implicated in the development and progression of this condition, the patatin-like phospholipase domain-containing protein 3 (PNPLA3 ) gene has emerged as a critical player. Variants of PNPLA3 are associated with altered lipid metabolism, leading to increased hepatic fat accumulation and subsequent inflammation and fibrosis. Understanding the role of PNPLA3 not only enhances our comprehension of the pathomechanisms driving SLD but also informs potential therapeutic strategies. The molecular mechanisms through which PNPLA3 variants contribute to lipid dysregulation and hepatocyte injury in SLD are critically discussed in the present review article. We extensively analyze clinical cohorts and population-based studies underpinning the association between PNPLA3 polymorphisms and the risk of developing SLD, and its liver-related and protean extrahepatic outcomes, in concert with other risk modifiers, notably including age, sex, and ethnicity in adults and children. We also discuss the increasingly recognized role played by the PNPLA3 gene in liver transplantation, autoimmune hepatitis, and acquired immunodeficiency syndrome. Finally, we examine the clinical implications of PNPLA3 diagnostics regarding risk stratification and targeted therapies for patients affected by SLD in the context of precision medicine approaches.

PNPLA3 rs738409 polymorphism and kidney dysfunction: an association beyond nonalcoholic fatty liver disease?

This commentary is primarily devoted to a recent observational study by Mantovani and colleagues (Aliment Pharmacol Ther. 2023; 57: 1093-102) examining the adverse effect of the patatin-like phospholipase domain-containing protein-3 (PNPLA3 ) rs738409 G allele on the kidney function in a cohort of 1,144 middle-aged Italian individuals with metabolic dysfunction. In this study, the authors found that the PNPLA3 rs738409 G allele was significantly associated with lower levels of estimated glomerular filtrate rate (eGFR), even after adjusting for not only common anthropometric and cardiometabolic risk factors but also ethnicity, serum liver enzymes, use of drugs against dyslipidemia and chronic kidney disease polygenic risk score. Additionally, in a subgroup of 144 patients followed for a median of 17 months, the authors also found that the PNPLA3 rs738409 G allele was independently associated with a faster eGFR decline. Commenting on the cohort study by Mantovani et al ., we also summarized the rapidly expanding evidence linking the PNPLA3 rs738409 variant with the risk of kidney disease. Furthermore, we discussed the potential research implications of these findings.

Adverse effect of PNPLA3 p.I148M genetic variant on kidney function in middle-aged individuals with metabolic dysfunction

BACKGROUND

The PNPLA3 p.I148M variant is the main genetic determinant of nonalcoholic fatty liver disease, and PNPLA3 silencing is being evaluated to treat this liver condition. Data suggest that the p.I148M variant predisposes to kidney damage, but the relative contribution to kidney function, compared to overall genetic susceptibility, is not defined.

AIMS

We aimed to assess the effect of PNPLA3 p.I148M on the estimated glomerular filtration rate (eGFR) in individuals with metabolic dysfunction.

METHODS

We included 1144 middle-aged individuals from the Liver-Bible-2022 cohort. Glomerular filtration rate (eGFR) was estimated using the Chronic Kidney Disease Epidemiology Collaboration equation. The effect of PNPLA3 p.I148M on eGFR_CKD-EPI levels was tested under additive genetic models adjusted for clinical predictors, ethnicity and a polygenic risk score of chronic kidney disease (PRS-CKD). In a subset of 144 individuals, we examined the effect of PNPLA3 p.I148M on eGFR_CKD-EPI over a median follow-up of 17 months.

RESULTS

The p.I148M variant was associated with lower eGFR_CKD-EPI levels (-1.24 mL/min/1.73 m² per allele, 95% CI: -2.32 to -0.17; p = 0.023), independent of age, sex, height, waist circumference, systolic blood pressure, LDL-cholesterol, transaminases, fasting insulin, albuminuria, lipid-lowering drugs, ethnicity and PRS-CKD score. In the prospective evaluation, the p.I148M variant was independently associated with faster eGFR_CKD-EPI decline (ΔeGFR_CKD-EPI -3.57 mL/min/1.73 m² per allele, 95% CI: -6.94 to -0.21; p = 0.037).

CONCLUSIONS

We found a detrimental impact of the PNPLA3 p.I148M variant on eGFR_CKD-EPI levels in middle-aged individuals with metabolic dysfunction. This association was independent of established risk factors, ethnicity and genetic predisposition to CKD. PNPLA3 p.I148M silencing may protect against kidney damage progression in carriers.