Nonalcoholic Fatty Liver Disease for Identification of Preclinical Carotid Atherosclerosis

Systematic review with meta-analysis: Steatosis severity and subclinical atherosclerosis in metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent liver condition recognised as an independent risk factor for cardiovascular disease (CVD). However, there is ongoing debate regarding the effective strategy for cardiovascular risk assessment in MASLD.

AIM

To investigate the relationship between liver imaging, specifically focusing on the severity of steatosis and subclinical atherosclerosis.

METHODS

We conducted a thorough search across four databases, from 1950 to April 2023, to identify eligible studies employing imaging to explore the relationship between different degrees of steatosis and subclinical atherosclerosis among MASLD. Additionally, we conducted a quality assessment using the Newcastle Ottawa Scale, performed a meta-analysis employing the DerSimonian-Liard random-effects model, and conducted subgroup analyses for validation.

RESULTS

In total, 19 studies, encompassing 147,411 middle-aged individuals without previous CVD (74.94% male; mean age 45.53 years [SD 10.69]; mean BMI 24.3 kg/m2 [SD 3.35]), were included. The pooled odds ratio for subclinical atherosclerosis was 1.27 (95% CI: 1.13-1.41, I2  = 76.68%) in mild steatosis and significantly increased to 1.68 (95% CI: 1.41-2.00, I2  = 89.02%) in moderate to severe steatosis. Sensitivity analysis, focusing on high-quality studies, consistently supported this finding and the results remained robust across subgroup analyses. Furthermore, meta-regression revealed that a higher mean AST and ALT, alongside a lower mean HDL, were significant moderators of this association.

CONCLUSIONS

Even mild steatosis is associated with CVD risk, and steatosis severity further intensifies this association. These findings suggest that liver fat quantification enhances CVD risk stratification in patients with MASLD.

Hepatic cholesterol transport and its role in non-alcoholic fatty liver disease and atherosclerosis

Non-alcoholic fatty liver disease (NAFLD) is a quickly emerging global health problem representing the most common chronic liver disease in the world. Atherosclerotic cardiovascular disease represents the leading cause of mortality in NAFLD patients. Cholesterol metabolism has a crucial role in the pathogenesis of both NAFLD and atherosclerosis. The liver is the major organ for cholesterol metabolism. Abnormal hepatic cholesterol metabolism not only leads to NAFLD but also drives the development of atherosclerotic dyslipidemia. The cholesterol level in hepatocytes reflects the dynamic balance between endogenous synthesis, uptake, esterification, and export, a process in which cholesterol is converted to neutral cholesteryl esters either for storage in cytosolic lipid droplets or for secretion as a major constituent of plasma lipoproteins, including very-low-density lipoproteins, chylomicrons, high-density lipoproteins, and low-density lipoproteins. In this review, we describe decades of research aimed at identifying key molecules and cellular players involved in each main aspect of hepatic cholesterol metabolism. Furthermore, we summarize the recent advances regarding the biological processes of hepatic cholesterol transport and its role in NAFLD and atherosclerosis.

Hexim1 heterozygosity stabilizes atherosclerotic plaque and decreased steatosis in ApoE null mice fed atherogenic diet

Hexim-1 is an inhibitor of RNA polymerase II transcription elongation. Decreased Hexim-1 expression in animal models of chronic diseases such as left ventricular hypertrophy, obesity and cancer triggered significant changes in adaptation and remodeling. The main aim of this study was to evaluate the role of Hexim1 in lipid metabolism focused in the progression of atherosclerosis and steatosis. We used the C57BL6 apolipoprotein E (ApoE null) crossed bred to C57BL6Hexim1 heterozygous mice to obtain ApoE null - Hexim1 heterozygous mice (ApoE-HT). Both ApoE null backgrounds were fed high fat diet for twelve weeks. Then, we evaluated lipid metabolism, atherosclerotic plaque formation and liver steatosis. In order to understand changes in the transcriptome of both backgrounds during the progression of steatosis, we performed Affymetrix mouse 430 2.0 microarray. After 12 weeks of HFD, ApoE null and ApoE-HT showed similar increase of cholesterol and triglycerides in plasma. Plaque composition was altered in ApoE-HT. Additionally, liver triglycerides and steatosis were decreased in ApoE-HT mice. Affymetrix analysis revealed that decreased steatosis might be due to impaired inducible SOCS3 expression in ApoE-HT mice. In conclusion, decreased Hexim-1 expression does not alter cholesterol metabolism in ApoE null background after HFD. However, it promotes stable atherosclerotic plaque and decreased steatosis by promoting the anti-inflammatory TGFβ pathway and blocking the expression of the inducible and pro-inflammatory expression of SOCS3 respectively.

Non-alcoholic fatty liver disease and dyslipidemia: An update

Non-alcoholic fatty liver (NAFLD) is the most common liver disease worldwide, progressing from simple steatosis to necroinflammation and fibrosis (leading to non-alcoholic steatohepatitis, NASH), and in some cases to cirrhosis and hepatocellular carcinoma. Inflammation, oxidative stress and insulin resistance are involved in NAFLD development and progression. NAFLD has been associated with several cardiovascular (CV) risk factors including obesity, dyslipidemia, hyperglycemia, hypertension and smoking. NAFLD is also characterized by atherogenic dyslipidemia, postprandial lipemia and high-density lipoprotein (HDL) dysfunction. Most importantly, NAFLD patients have an increased risk for both liver and CV disease (CVD) morbidity and mortality. In this narrative review, the associations between NAFLD, dyslipidemia and vascular disease in NAFLD patients are discussed. NAFLD treatment is also reviewed with a focus on lipid-lowering drugs. Finally, future perspectives in terms of both NAFLD diagnostic biomarkers and therapeutic targets are considered.