Adiponectin polymorphisms and non-alcoholic fatty liver disease risk: a meta-analysis

Role of genetic variants and DNA methylation of lipid metabolism-related genes in metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD), is one of the most common chronic liver diseases, which encompasses a spectrum of diseases, from metabolic dysfunction-associated steatotic liver (MASL) to metabolic dysfunction-associated steatohepatitis (MASH), and may ultimately progress to MASH-related cirrhosis and hepatocellular carcinoma (HCC). MASLD is a complex disease that is influenced by genetic and environmental factors. Dysregulation of hepatic lipid metabolism plays a crucial role in the development and progression of MASLD. Therefore, the focus of this review is to discuss the links between the genetic variants and DNA methylation of lipid metabolism-related genes and MASLD pathogenesis. We first summarize the interplay between MASLD and the disturbance of hepatic lipid metabolism. Next, we focus on reviewing the role of hepatic lipid related gene loci in the onset and progression of MASLD. We summarize the existing literature around the single nucleotide polymorphisms (SNPs) associated with MASLD identified by genome-wide association studies (GWAS) and candidate gene analyses. Moreover, based on recent evidence from human and animal studies, we further discussed the regulatory function and associated mechanisms of changes in DNA methylation levels in the occurrence and progression of MASLD, with a particular emphasis on its regulatory role of lipid metabolism-related genes in MASLD and MASH. Furthermore, we review the alterations of hepatic DNA and blood DNA methylation levels associated with lipid metabolism-related genes in MASLD and MASH patients. Finally, we introduce potential value of the genetic variants and DNA methylation profiles of lipid metabolism-related genes in developing novel prognostic biomarkers and therapeutic targets for MASLD, intending to provide references for the future studies of MASLD.

Bombax ceiba Linn. leaf extract rich in phenolic compounds to mitigate non-alcoholic fatty liver-related complications in experimental model

OBJECTIVES

Obesity, diabetes mellitus, insulin resistance (IR), and hypertriglyceridemia are common features observed in non-alcoholic fatty liver diseases (NAFLD). There is a critical medical necessity to find novel therapeutics that can halt the development of NAFLD.

METHODS

Bombax ceiba Linn. leaf extract was prepared and its phytochemical profile was determined. Standard and high carbohydrate high-fat diets (HCHF) were prepared. Rats were fed HCHF for 18 weeks to induce a non-alcoholic fatty liver (NAFL) model. Forty male rats were divided into control, B. ceiba Linn. leaf extract, NAFL, prophylactic, and treated groups. Serum fasting blood sugar (FBS), insulin, insulin resistance (HOMA-IR), cholesterol, high-density lipoprotein (HDL), triglycerides (TG), low density lipoprotein (LDL), alanine aminotransferase (ALT), aspartate aminotransferase (AST), intelectin-1 (ITLN1), p38 MAP kinase (MAPK), peroxisome proliferator-activated receptor alpha (PPAR-α), and interleukin-6 (IL-6) were evaluated.

RESULTS

Data obtained showed that HCHF-induced NAFL resulting in a significant increase in FBS, serum insulin, HOMA-IR, cholesterol, LDL, TG, ALT, AST, and IL-6 and a significant decrease in serum levels of HDL, ITLN1, p38 MAP kinase, and PPAR-α compared to the control group. The analysis of B. ceiba Linn. leaf extract showed high content of phenol compounds which may cause a significant decrease in the levels of FBS, insulin, HOMA-IR values, lipid profile, and levels of IL-6 while a significant increase in serum levels of LDL, ITLN1, p38 MAP kinase, and PPAR-α compared to the NAFL group.

CONCLUSIONS

B. ceiba Linn. Leaf extract is a highly protective and promising therapeutic agent against inflammation and oxidative stress in the NAFLD model induced by HCHF.

Correlation of Adiponectin Gene Polymorphisms rs266729 and rs3774261 With Risk of Nonalcoholic Fatty Liver Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Increasing evidence has suggested an association of adiponectin gene polymorphisms rs1501299, rs2241766, rs266729 and rs3774261 with risk of nonalcoholic fatty liver disease (NAFLD). This correlation has been extensively meta-analyzed for the first two polymorphisms, but not the second two.

METHODS

The PubMed, EMBASE, Google Scholar, and China National Knowledge Infrastructure databases were searched for relevant literature. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated.

RESULTS

A total of 10 case-control studies on rs266729 (2,619 cases and 1,962 controls) and 3 case-control studies on rs3774261 (562 cases and 793 controls) were included. Meta-analysis showed that rs266729 was associated with significantly higher NAFLD risk based on the following five models: allelic, OR 1.72, 95% CI 1.34-2.21, P < 0.001; recessive, OR 2.35, 95% CI 1.86-2.95, P < 0.001; dominant, OR 1.84, 95% CI 1.34-2.53, P < 0.001; homozygous, OR 2.69, 95% CI 1.84-3.92, P < 0.001; and heterozygous, OR 1.72, 95% CI 1.28-2.32, P < 0.001. This association between rs266729 and NAFLD risk remained significant for all five models among studies with Asian, Chinese and Caucasian samples. The rs2241766 polymorphism was associated with significantly higher NAFLD risk according to the recessive model (OR 1.87, 95% CI 1.15-3.04, P = 0.01).

CONCLUSION

Polymorphisms rs266729 and rs3774261 in the adiponectin gene may be risk factors for NAFLD. These findings may pave the way for novel therapeutic strategies, but they should be verified in large, well-designed studies.

Association between APOC3 polymorphisms and non-alcoholic fatty liver disease risk: a meta-analysis

BACKGROUND AND AIM

The apolipoprotein C3 (APOC3) polymorphism has been reported to predispose to non-alcoholic fatty liver disease (NAFLD). However, the results remain inconclusive. This meta-analysis aimed to provide insights into the association between APOC3 polymorphisms and NAFLD risk.

METHODS

Studies with terms "NALFD" and "APOC3" were retrieved from PubMed, Web of Science, CNKI and Wanfang databases up to August 1, 2019. Pooled odds ratio (OR) and 95% confidence interval (95% CI) for the association of APOC3 polymorphisms and NAFLD risk were calculated using fixed and random-effects models.

RESULTS

A total of twelve studies from eleven articles were included. Of them, eight studies (1750 cases and 2181 controls) reported the strong association of variant rs2854116 with NAFLD and six studies (1523 cases and 1568 controls) found the association of rs2854117 polymorphism with NAFLD. Overall, a statistically significant association between rs2854116 polymorphism of APOC3 gene and NAFLD risk was found only under dominant model. However, association of rs2854117 polymorphism with NAFLD risk was not detected under all four genetic models. In sub-group analysis of NAFLD subjects based on country, no association among them in China was detected. Besides, four studies analyze the association between the two polymorphisms and clinical characteristics in all subjects or NAFLD patients, and we also failed detect any association between the wild carriers and variant carriers.

CONCLUSION

The meta-analyses suggests that the rs2854116 polymorphism but not rs2854117 polymorphism in APOC3 gene might be a risk factor for NAFLD among Asians. That is, individuals with CT+CC genotype have higher risk of developing NAFLD. However, studies with sufficient sample size are needed for the further validation.

Circulating ectodysplasin A is a potential biomarker for nonalcoholic fatty liver disease

BACKGROUND

Ectodysplasin A (EDA), a new hepatokine, may be involved in energy metabolism. This study aims to 1) investigate the role of EDA in hepatic steatosis in C57BL/6 mice and HepG2 cells; 2) evaluate serum EDA in nonalcoholic fatty liver disease (NAFLD) in human.

METHODS

This study comprises an experimental study in vitro and in vivo and a hospital based case-control study. Western blotting, qPCR and ELISA were used to measure EDA levels. siRNA and shRNA were performed to knockdown EDA. An Adipokine Magnetic Bead Panel was performed to measure serum adipokines.

RESULTS

Increased levels of hepatic and secreted EDA were detected in steatosis, in vivo and in vitro. Steatosis was ameliorated by EDA knockdown in vitro, while intrahepatic triglycerides content and liver enzymes were improved in vivo. Furthermore, knockdown of EDA upregulated lipolytic genes and suppressed lipogenic genes. Serum EDA in subjects with NAFLD was higher. Moreover, it reveals associations between circulating EDA and higher odds of NAFLD, while circulating EDA presented a practicable performance to identify NAFLD. Lastly, serum EDA level was dependent on BMI, TNF-α, T2DM and obesity.

CONCLUSIONS

EDA aggravates steatosis by striking balance between lipid deposition and elimination. It was a potential biomarker of NAFLD.

The effects of curcumin on the metabolic parameters of non-alcoholic fatty liver disease: a meta-analysis of randomized controlled trials

AIMS

Evidence indicates that curcumin seems to improve outcomes in non-alcoholic fatty liver disease (NAFLD). A meta-analysis was performed to evaluate the effects of curcumin inNAFLD.

METHODS

We searched PubMed, EMBASE, and the Cochrane Library from inception through March 2018 to identify randomized controlled trials (RCTs) evaluating the role of curcumin inNAFLD. The mean difference (MD) and 95% confidence interval (CI) were calculated.

RESULTS

Four RCTs with a total of 229 NAFLD patients were included. Curcumin was more likely to lower LDL-C, triglycerides, FBS, HOMA-IR, weight and AST levels compared with placebo, and the difference was statistically significant [MD = - 27.02, 95% CI (- 52.30, - 1.74); MD = - 33.20, 95% CI (- 42.30, - 24.09); MD = - 5.63, 95% CI (- 10.36, - 0.90); MD = - 0.53, 95% CI (- 1.00, - 0.05); MD = - 2.27, 95% CI (- 3.11, - 1.44); MD = - 7.43, 95% CI (- 11.31, - 3.54), respectively]. However, the beneficial effect of curcumin did not achieve statistical significance in lowering total cholesterol, HDL-C, HbA1c, ALT or insulin levels [MD = - 30.47,95% CI (- 60.89. - 0.06); MD = - 0.98, 95% CI (- 2.88, 0.92); MD = - 0.41, 95% CI (- 1.41, 0.59); MD = - 6.02, 95% CI (- 15.61, 3.57); MD = - 0.92, 95% CI (- 2.33, 0.49)].

CONCLUSIONS

Curcumin is effective in lowering LDL-C, triglycerides, FBS, HOMA-IR, weight, and AST levels in NAFLD patients, and it is well tolerated. Further RCTs are required to confirm our findings.

Obesity genetics and cardiometabolic health: Potential for risk prediction

The increasing burden of obesity worldwide and its effect on cardiovascular disease (CVD) risk is an opportunity for evaluation of preventive approaches. Both obesity and CVD have a genetic background and polymorphisms within genes which enhance expression of variant proteins that influence CVD in obesity. Genome-based prediction may therefore be a feasible strategy, but the identification of genetically driven risk factors for CVD manifesting as clinically recognized phenotypes is a major challenge. Clusters of such risk factors include hyperglycaemia, hypertension, ectopic liver fat, and inflammation. All involve multiple genetic pathways having complex interactions with variable environmental influences. The factors that make significant contributions to CVD risk include altered carbohydrate homeostasis, ectopic deposition of fat in muscle and liver, and inflammation, with contributions from the gut microbiome. A futuristic model depends on harnessing the predictive power of plausible genetic variants, phenotype reversibility, and effective therapeutic choices based on genotype-phenotype interactions. Inverting disease phenotypes into ideal cardiovascular health metrics could improve genetic and epigenetic assessment, and form the basis of a future model for risk detection and early intervention.

Relationship Between Nonalcoholic Fatty Liver Disease Susceptibility Genes and Coronary Artery Disease

Coronary artery disease (CAD) is the principal cause of death in patients with nonalcoholic fatty liver disease (NAFLD). The aim of the present study was to investigate whether NAFLD is causally involved in the pathogenesis of CAD. For this, previously reported NAFLD susceptibility genes were clustered and tested for an association with CAD in the Coronary Artery Disease Genome‐Wide Replication and Meta‐Analysis plus the Coronary Artery Disease Genetics (CARDIoGRAMplusC4D) Consortium data set. The role of plasma lipids as a potential mediator was explored by using data from the Global Lipids Genetics Consortium. Statistical analyses revealed that the combination of 12 NAFLD genes was not associated with CAD in 60,801 CAD cases and 123,504 controls (odds ratio [OR] per NAFLD risk allele, 1.0; 95% confidence interval [CI], 0.99‐1.00). In a subsequent sensitivity analysis, a positive relationship was observed after exclusion of gene variants that are implicated in NAFLD through impaired very low‐density lipoprotein secretion (i.e., microsomal triglyceride transfer protein [MTTP], patatin‐like phospholipase domain containing 3 [PNPLA3], phosphatidylethanolamine N‐methyltransferase [PEMT], and transmembrane 6 superfamily member 2 [TM6SF2]) (OR, 1.01; 95% CI, 1.00‐1.02). Clustering of the excluded genes showed a significant negative relationship with CAD (OR, 0.97; 95% CI, 0.96‐0.99). A substantial proportion of the observed heterogeneity between the individual NAFLD genes in relation to CAD could be explained by plasma lipids, as reflected by a strong relationship between plasma lipids and CAD risk conferred by the NAFLD susceptibility genes (r = 0.76; P = 0.004 for low‐density lipoprotein cholesterol). Conclusion: NAFLD susceptibility genes do not cause CAD per se. The relationship between these genes and CAD appears to depend to a large extent on plasma lipids. These observations strongly suggest taking plasma lipids into account when designing a new drug to target NAFLD.

Genetic and Epigenetic Culprits in the Pathogenesis of Nonalcoholic Fatty Liver Disease

Nonalcoholic Fatty Liver Disease (NAFLD) constitutes a wide spectrum of liver pathology with hepatic steatosis at the core of this pathogenesis. Variations of certain genetic components have demonstrated increased susceptibility for hepatic steatosis. Therefore, these inciting variants must be further characterized in order to ultimately provide effective, targeted therapies for NAFLD and will be the focus of this review. Several genetic variants revealed an association with NAFLD through Genome-wide Association Study, meta-analyses, and retrospective case-control studies. PNPLA3 rs738409 and TM6SF2 rs58542926 are the two genetic variants providing the strongest evidence for association with NAFLD. However, it remains to be determined if these genetic variants serve as the primary culprit which induces the pathogenesis of NAFLD. Prospective and intervention studies are urgently needed to firmly establish a cause-and-effect relationship between the presence of certain genetic variants and risk of NAFLD development and progression.

Recent advances in understanding the role of adipocytokines during non-alcoholic fatty liver disease pathogenesis and their link with hepatokines

Non-alcoholic fatty liver disease (NAFLD) is currently considered the main cause of chronic liver disease worldwide. Mechanisms leading to the development and progression of this disease are topics of great interest for researchers and clinicians. The current multi-hit hypothesis has thrown the crosstalk between liver and adipose tissue into sharp focus. It is well known that adipose tissue produces circulating factors, known as adipocytokines, which exert several effects on liver cells, promoting the onset of NAFLD and its progression to non-alcoholic steatohepatitis in obese subjects. In a similar way, hepatocytes may also respond to obesogenic stimuli by producing and releasing hepatokines into the circulation. Here, the authors provide an overview of recent advances in our understanding of the role of the most relevant adipocytokines and hepatokines in NAFLD pathogenesis, highlighting their possible molecular and functional interactions.

Nonalcoholic fatty liver disease: a negative risk factor for colorectal cancer prognosis

Nonalcoholic fatty liver disease (NAFLD) is known to be associated with an increased risk of colorectal cancer (CRC). However, the relationship between NAFLD and the prognosis of CRC remains unclear. The primary objective of this study was to evaluate the overall survival (OS) and disease-free survival (DFS) rates in patients with CRC and the secondary objective was to compare clinicopathologic variables which were stratified by NAFLD. We performed a large cohort study of 1314 patients who were first diagnosed with CRC between January 2006 and April 2011. Postoperative follow-up data were collected from out-patient medical records, telephone consultations, and social security death indices. The Kaplan-Meier method was used to calculate the cumulative survival rate. Clinicopathologic variables were analyzed by univariate analysis and multivariate analysis through a Cox proportional hazard regression model. The mean follow-up time was 52.7 ± 25.3 months. Upon baseline comparison, the NAFLD group had significantly higher values of body mass index, triglycerides, and uric acid and significantly lower values of high-density lipoprotein, compared with the non-NAFLD group (P < 0.05 for all). There were no significant differences between the 2 groups with regard to tumor location, TNM staging, tumor differentiation, carcinoembryonic antigen, and vascular invasion. The cumulative 1-, 3-, and 5-year OS rates were 96.1%, 85.2%, and 80.6%, respectively, in the NAFLD group, which were statistically significantly higher than the OS rates of 91.6%, 76.2%, and 67.8%, respectively, in the non-NAFLD group (P = 0.075, P = 0.002, P = 0.030, respectively). There was no difference in DFS rates between the CRC patients with and without NAFLD (P = 0.267). Multivariate analysis showed that the presence of NAFLD was an independent negative risk factor for OS after adjusting for clinicopathologic covariates (hazard ratio = 0.593; 95% confidence interval 0.442, 0.921; P = 0.020), but not for DFS (P = 0.270). NAFLD may play a protective role in OS for CRC patients. Further studies are needed to elucidate the molecular mechanisms of putative protective effects in CRC patients with NAFLD.