Interaction Between Alcohol Consumption and PNPLA3 Variant in the Prevalence of Hepatic Steatosis in the US Population

PNPLA3 rs738409, environmental factors and liver-related mortality in the U.S. Population

BACKGROUND & AIMS

Little is known about the interplay between patatin-like phospholipase domain protein 3 (PNPLA3 rs738409 C>G), environmental factors, and the risk of liver-related death (LRD).

METHODS

4,361 adults were selected from NHANES III, 1991-1994. All participants were linked to the National Death Index until 2019 (mean follow-up: 23.2 years). LRD was the study outcome. Associations of PNPLA3, diet, light alcohol intake, smoking, and BMI (kg/m2) with LRD were examined using competing risk regression models.

RESULTS

PNPLA3 G-allele was significantly associated with LRD (adjusted subhazard ratio [adj.sHR]: 2.9, 95% CI: 1.4-5.8). Non-heavy alcohol intake (adj.sHR: 2.2, 95% CI: 1.1-4.5), top quartiles of monounsaturated fat (MUFA) (adj.sHR: 0.43, 95% CI: 0.12-0.99), and cholesterol (adj.sHR: 2.6, 95% CI: 1.00-8.8) and coffee intake ≥3 cups/day (adj.sHR: 0.05, 95% CI: 0.06-0.10), former/current smoking (adj.sHR: 1.8, 95% CI: 1.2-2.6), BMI (adj.sHR: 1.1, 95% CI: 1.03-1.2), and healthy eating index (HEI) (adj.sHR: 0.96, 95% CI: 0.93-0.98) were associated with LRD. Joint effects between PNPLA3 and environmental factors showed that the risk of LRD was significantly increased in carriers of the G-allele with non-heavy alcohol intake (adj.sHR: 3.7), higher consumption (top quartile) of cholesterol (adj.sHR: 4.1), former (adj.sHR: 4.3) or current (adj.sHR: 3.5) smoking, or BMI ≥30 (adj.sHR: 4.0) kg/m2. The effects of the G-allele on the risk of LRD were significantly attenuated in those with top quartile consumption of MUFA (adj.sHR: 0.5) or ≥3 cups/day of coffee (adj.sHR: 0.09). HEI was inversely associated with LRD across all PNPLA3 genotypes (adj.sHR: 0.94, 0.96, and 0.97 for CC, CG, and GG, respectively).

CONCLUSIONS

PNPLA3 is associated with LRD and this relationship is significantly modified by anthropometric and environmental factors.

Global Epidemiological Impact of PNPLA3 I148M on Liver Disease

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) has increased exponentially over the past three decades, in parallel with the global rise in obesity and type 2 diabetes. It is currently the most common cause of liver-related morbidity and mortality. Although obesity has been identified as a key factor in the increased prevalence of MASLD, individual differences in susceptibility are significantly influenced by genetic factors. PNPLA3 I148M (rs738409 C>G) is the variant with the greatest impact on the risk of developing progressive MASLD and likely other forms of steatotic liver disease. This variant is prevalent across the globe, with the risk allele (G) frequency exhibiting considerable variation. Here, we review the contribution of PNPLA3 I148M to global burden and regional differences in MASLD prevalence, focusing on recent evidence emerging from population-based sequencing studies and prevalence assessments. We calculated the population attributable fraction (PAF) as a means of quantifying the impact of the variant on MASLD. Furthermore, we employ quantitative trait locus (QTL) analysis to ascertain the associations between rs738409 and a range of phenotypic traits. This analysis suggests that these QTLs may underpin pleiotropic effects on extrahepatic traits. Finally, we outline potential avenues for further research and identify key areas for investigation in future studies.

Mild-moderate alcohol consumption and diabetes are associated with liver fibrosis in patients with biopsy-proven MASLD

Background

It is unclear whether patients with metabolic dysfunction-associated steatotic liver disease (MASLD) are allowed variable low levels of alcohol. This study aimed to evaluate the effect of mild-moderate alcohol consumption on the biochemical and histological characteristics of patients with MASLD.

Methods

Alcohol consumption was assessed in 713 patients with steatotic liver disease (SLD) who underwent liver biopsy. Non-drinking, mild-moderate drinking, and excessive drinking were defined as 0 g/day, 1-<20 g/day, and >20 g/day for women and 0 g/day, 1-<30 g/day, and >30 g/day for men, respectively. Liver biopsies were scored according to the NASH CRN system.

Results

A total of 713 participants (median age 39.0 years and 77.1% male) with biopsy-proven SLD were enrolled, including 239 nondrinkers, 269 mild-moderate drinkers and 205 excessive drinkers. Excessive drinking was associated with increased risks for lobular inflammation and liver fibrosis compared to nondrinkers and mild-moderate drinkers. Compared with non-drinkers, mild-moderate drinkers had significantly lower odds for steatosis (OR = 0.60, 95% CI = 0.38-0.93, p = 0.025), hepatocellular ballooning (OR = 0.52, 95% CI = 0.29-0.91, p = 0.020) and fibrosis (OR = 0.50, 95% CI = 0.31-0.81, p = 0.005). However, in non-excessive drinkers with type 2 diabetes mellitus (T2DM), there was no association between mild-moderate alcohol consumption and liver fibrosis (OR = 0.562, 95% CI = 0.207-1.530, p = 0.257).

Conclusions

Mild-moderate alcohol consumption might be protective against liver fibrosis in MASLD patients, which is modified by the presence of T2DM. However, further longitudinal studies are needed to determine the effect of ongoing alcohol consumption on disease severity.

Racial and ethnic disparities in alcohol-associated liver disease in the United States: A systematic review and meta-analysis

BACKGROUND

Alcohol-associated liver disease (ALD), encompassing alcohol-associated hepatitis and alcohol-associated cirrhosis, is rising in the United States. Racial and ethnic disparities are evident within ALD; however, the precise nature of these disparities is poorly defined.

METHODS

We conducted a search of the PubMed/MEDLINE and EMBASE databases to identify studies published from inception through September 2023 that reported ALD incidence, prevalence, and mortality within the United States, stratified by race and ethnicity. We calculated pooled prevalence and incidence by race and ethnicity, including risk ratios and ORs for ALD pooled prevalence and alcohol-associated hepatitis/alcohol-associated cirrhosis pooled proportions, and OR for ALD mortality using the DerSimonian and Laird method for random-effect models.

RESULTS

We identified 25 relevant studies (16 for quantitative meta-analysis), comprising 76,867,544 patients. ALD prevalence was highest in Hispanic (4.5%), followed by White (3.1%) and Black (1.4%) individuals. Pooled risk ratios of ALD prevalence were 1.64 (95% CI: 1.12-2.39) for Hispanic and 0.59 (95% CI: 0.35-0.87) for Black compared to White individuals. Mortality among those with ALD did not significantly differ between White and Hispanic (OR: 1.54, 95% CI: 0.9-2.5; I2=0%), Black (OR: 1.2, 95% CI: 0.8-1.6; I2=0%), or Native American (OR: 2.41, 95% CI: 0.9-2.9) individuals, while there was a significant difference between White and Asian (OR: 0.1; 95% CI: 0.03-0.5) individuals. Most data were cross-sectional and assessed to be of poor or fair quality.

CONCLUSIONS

Differences were observed in ALD epidemiology, including higher prevalence among Hispanic and lower prevalence among Black individuals, although there were smaller differences in ALD mortality. Differences in ALD prevalence and prognosis remain poorly defined based on existing data, highlighting a need for higher-quality epidemiological studies in this area.

A nutrigenetic precision approach for the management of non-alcoholic fatty liver disease

BACKGROUND & AIMS

The Patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 single nucleotide polymorphism (SNP) is one of the major genetic determinant of non-alcoholic fatty liver disease (NAFLD) and is strongly regulated by changes in energy balance and dietary factors. We aimed to investigate the association between the PNPLA3 rs738409 SNP, nutrient intake and NAFLD severity.

METHOD

PNPLA3-rs738409 SNP was genotyped in 181 patients with NAFLD who completed the EPIC Food Frequency Questionnaire. Liver steatosis was evaluated by Controlled Attenuation Parameter (CAP) (Fibroscan®530, Echosens). According to the established cut-off, a CAP value ≥ 300 dB/m was used to identify severe steatosis (S3). An independent group of 46 biopsy-proven NAFLD subjects was used as validation cohort.

RESULTS

Overall, median age was 53 years (range 44; 62) and 60.2% of patients were male. Most subjects (56.3%) had S3 and showed increased liver stiffness (p < 0.001), AST (p = 0.003) and ALT levels (p < 0.001) compared to those with CAP<300 dB/m. At logistic regression analyses we found that the interaction between carbohydrates intake and the carriers of the PNPLA3 G risk allele was significantly associated with S3 (p = 0.001). The same result was confirmed in the validation cohort, were the interaction between high carbohydrate intake (48%) and PNPLA3 SNP was significantly associated with steatosis ≥33% (p = 0.038).

CONCLUSION

The intake of greater than or equal to 48% carbohydrate in NAFLD patients carriers of the CG/GG allele of PNPLA3 rs738409 may increase the risk of significant steatosis.

Fatty Liver Disease-Alcoholic and Non-Alcoholic: Similar but Different

In alcohol-induced liver disease (ALD) and in non-alcoholic fatty liver disease (NAFLD), there are abnormal accumulations of fat in the liver. This phenomenon may be related to excessive alcohol consumption, as well as the combination of alcohol consumption and medications. There is an evolution from simple steatosis to steatohepatitis, fibrosis and cirrhosis leading to hepatocellular carcinoma (HCC). Hepatic pathology is very similar regarding non-alcoholic fatty liver disease (NAFLD) and ALD. Initially, there is lipid accumulation in parenchyma and progression to lobular inflammation. The morphological changes in the liver mitochondria, perivenular and perisinusoidal fibrosis, and hepatocellular ballooning, apoptosis and necrosis and accumulation of fibrosis may lead to the development of cirrhosis and HCC. Medical history of ethanol consumption, laboratory markers of chronic ethanol intake, AST/ALT ratio on the one hand and features of the metabolic syndrome on the other hand, may help in estimating the contribution of alcohol intake and the metabolic syndrome, respectively, to liver steatosis.

Analysis of alcohol use, consumption of micronutrient and macronutrients, and liver health in the 2017-2018 National Health and Nutrition Examination Survey

BACKGROUND

Alcohol use is a major global healthcare burden that contributes to numerous adverse health outcomes, including liver disease. Many factors influence individual susceptibility to alcohol-associated diseases, including nutritional factors. The objective of the current study was to examine inter-relations among alcohol, dietary micronutrients and macronutrient consumption, and liver health by analyzing data from the 2017-2018 National Health and Nutrition Examination Survey (NHANES).

METHODS

Based on self-reported alcohol consumption, NHANES respondents were assigned to one of four categories: never drinkers (lifetime abstainers), non-drinkers (past-year abstainers), moderate drinkers (1/2 drinks per day for females/males, respectively), and heavy drinkers (>1/>2 drinks per day for females/males, respectively, and/or frequent binge drinking). Survey-weighted regression analyses (adjusted for gender, age, race, education, and body mass index) were performed to examine associations between alcohol intake, dietary, and liver health characteristics.

RESULTS

Individuals categorized as heavy drinkers were significantly younger, most often well-educated males with low incidences of diabetes and other comorbidities. They consumed the most overall calories and various micronutrients, indicating a diet that was not necessarily nutrient poor. Neither moderate nor heavy drinkers had liver steatosis or fibrosis as measured by liver elastography, although heavy drinkers had modestly elevated plasma biomarkers of liver injury, including ALT, AST, and GGT, compared with the other groups.

CONCLUSIONS

Our findings suggest that the category of heavy drinkers in the 2017-2018 NHANES consisted of generally healthy individuals with high-energy intake and no evidence of liver steatosis or fibrosis. However, slightly increased plasma liver markers may indicate a risk of future progression to more advanced stages of liver disease over time in some individuals. Several limitations should be considered when interpreting these data, including the potential misclassification of drinking categories and the lack of standardized cutoff scores for fatty liver as assessed by elastography, among others.