Sex differences in the impact of nonalcoholic fatty liver disease on cardiovascular risk factors

Strain- and sex-dependent variability in hepatic microcirculation and liver function in mice

BACKGROUND

The integrity and functionality of the hepatic microcirculation are essential for maintaining liver health, which is influenced by sex and genetic background. Understanding these variations is crucial for addressing disparities in liver disease outcomes.

AIM

To investigate the sexual dimorphism and genetic heterogeneity of liver microcirculatory function in mice.

METHODS

We assessed hepatic microhemodynamics in BALB/c, C57BL/6J, and KM mouse strains using laser Doppler flowmetry and wavelet analysis. We analyzed the serum levels of alanine transaminase, glutamic acid aminotransferase, total bile acid, total protein, alkaline phosphatase, and glucose. Histological and immunohistochemical staining were employed to quantify microvascular density and the expression levels of cluster of differentiation (CD) 31, and estrogen receptor α, and β. Statistical analyses, including the Mantel test and Pearson correlation, were conducted to determine the relationships among hepatic function, microcirculation, and marcocirculation between different sexes and across genetic backgrounds.

RESULTS

We identified sex-based disparities in hepatic microhemodynamics across all strains, with males exhibiting higher microvascular perfusion and erythrocyte concentration, but lower blood velocity. Strain-specific differences were evident, particularly in the endothelial oscillatory characteristics of the erythrocyte concentration. No sex-dependent differences in estrogen receptor expression were observed, while significant variations in CD31 expression and microvascular density were observed. The correlations highlighted relationships between hepatic microhemodynamics and liver function indicators.

CONCLUSION

Our findings indicate the influence of genetic and sex differences on hepatic microcirculation and liver function, highlighting the necessity of incorporating both genetic background and sex into hepatic physiology studies and potential liver disease management strategies.

Interaction between non-alcoholic fatty liver disease and obesity on the risk of developing cardiovascular diseases

BACKGROUNDS

This investigation seeks to explore the correlation between nonalcoholic fatty liver disease (NAFLD) and cardiovascular diseases (CVDs), and to to provide evidence for the prevention and treatment of CVDs.

METHODS

This study utilized data from the Jinchang cohort platform, including 19,399 participants without pre-existing major CVDs. Based on the general population and gender stratification, Cox models were used to analyze the risk of NAFLD for CVDs. The combined effect of NAFLD and different obesity indicators on CVDs was analyzed by additive and multiplicative interaction models and subgroups.

RESULTS

There were 3129 NAFLD patients out of 19399 subjects, and 723 (23.11%) of them had the CVD. After adjusting for multiple confounding factors, the Cox model revealed a 1.17-fold increase in the risk of CVDs among patients with NAFLD compared to those without NAFLD. Moreover, there was no notable disparity in CVDs risk among most NAFLD patients at the same level of obesity. The results indicated no additive interaction between NAFLD and obesity concerning CVDs risk, but rather a positive multiplicative interaction. Using the normal population as a reference, it was found that people with both obesity and NAFLD significantly increased the risk of developing CVDs, with HRs and 95% CIs of 1.790 (1.508, 2.126), 1.356 (1.213, 1.517), and 1.807 (1.503, 2.174), respectively, for BMI, WC, and the combination of BMI and WC.

CONCLUSIONS

NAFLD and obesity are independent risk factors for CVDs. The synergy of obesity and NAFLD implies that NAFLD patients should control weight gain. Larger BMI and WC values may increase the CVDs risk for NAFLD patients, especially women.

The association between healthy eating index-2015 with anthropometric, cardiometabolic and hepatic indices among patients with non-alcoholic fatty liver disease

BACKGROUND

Obesity, cardiovascular diseases, and metabolic disorders are common problems among participants with non-alcoholic fatty liver disease (NAFLD). However, the association between these problems and the healthy eating index-2015 (HEI-2015) remains unknown. Although the HEI-2015 originated from American dietary guidelines, its comprehensive evaluation of diet quality provides valuable insights for various populations, including Iranians. Therefore, the objective of this study was to investigate the association between anthropometric, hepatic, and cardio-metabolic indices with HEI-2015 scores in participants with NAFLD.

METHODS

We conducted a cross-sectional analysis of data from the Hoveyzeh Cohort Study, which included adults aged 35 to 70 years between 2016 and 2018. A total of 664 participant with NAFLD (452 females and 212 males) were included in the analysis. The HEI-2015 was assessed using the Food Frequency Questionnaire (FFQ). Various indices, including the body shape index (ABSI), atherogenic index of plasma (AIP), visceral adiposity index (VAI), lipid accumulation product (LAP), cardiometabolic index (CMI), lipoprotein combine index (LCI), AST/ALT ratio, ALD/NAFLD index, and hepatic steatosis index (HSI), were calculated.

RESULTS

No significant differences were observed in anthropometric, cardio-metabolic, and hepatic indices across the quartiles of HEI-2015. However, among participants with NAFLD, men had significantly higher AIP and LCI levels, while women had significantly higher BMI, ABSI, VAI, LAP, and CMI levels. Additionally, women with NAFLD exhibited higher AST/ALT and HSI levels but lower ALD/NAFLD levels compared to men with NAFLD. Linear regression analysis among men with NAFLD revealed a significant negative correlation between HEI-2015 score and HSI in both the unadjusted model (β=-0.131, SE = 0.058, p = 0.024) and the adjusted model for energy intake (β=-0.129, SE = 0.058, p = 0.028).

CONCLUSION

The present study demonstrated a correlation between lower HEI-2015 scores and an increased risk of steatosis in men with NAFLD. Moreover, our findings highlighted gender-related differences in NAFLD and cardio-metabolic disorders.

Characterizing Factors Associated with Excess Body Weight: A Descriptive Study Using Principal Component Analysis in a Population with Overweight and Obesity

Obesity is a worldwide epidemic, making it crucial to understand how it can be effectively prevented/treated. Considering that obesity is a multifactorial condition, this article carried out a baseline cross-sectional study of the variables involved in the disorder. Eighty-four subjects with overweight/obesity were recruited. Dietary baseline information was obtained by analysing three 24 h recalls. Resting metabolic rate was measured using indirect calorimetry, physical activity was measured through accelerometry, cardiometabolic parameters were determined in blood samples and body composition via anthropometry and bioimpedance. A univariant and multivariate exploratory approach was carried out using principal component analysis (PCA). Large inter-individual variability was observed in dietetic, biochemical, and physical activity measurements (coefficient of variation ≥ 30%), but body composition was more uniform. Volunteers had an unbalanced diet and low levels of physical activity. PCA reduced the 26 analysed variables to 4 factors, accounting for 65.4% of the total data variance. The main factor was the "dietetic factor", responsible for 24.0% of the total variance and mainly related to energy intake, lipids, and saturated fatty acids. The second was the "cardiometabolic factor" (explaining 16.8% of the variability), the third was the "adiposity factor" (15.2%), and the last was the "serum cholesterol factor" (9.4%).

Effect of Intermittent Fasting on Lipid Profile, Anthropometric and Hepatic Markers in Non-Alcoholic Fatty Liver Disease (NAFLD): A Systematic Review

BACKGROUND

The first-line treatment for non-alcoholic fatty liver disease (NAFLD) is lifestyle modification; this should accompany any pharmacological intervention. Intermittent fasting (IF) has shown benefits over metabolic and cardiovascular parameters. Non-religious IF includes Time-Restricted Feeding (TRF), Alternate-Day Fasting (ADF), and 5:2 IF interventions.

OBJECTIVE

To evaluate the effects of IF on anthropometric, liver damage, and lipid profile markers in subjects with NAFLD.

METHODS

A bibliographic search was carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using PubMed and Scopus databases.

RESULTS

Five studies involving 470 patients with NAFLD were included. In relation to anthropometric markers, all the articles reported body weight reduction (2.48-7.63%), but only ADF and 5:2 IF reported a body weight reduction >5%; also, all the articles reported fat mass reduction. Concerning hepatic markers, all the articles reported a reduction in hepatic steatosis and alanine aminotransferase activity, but no changes in fat-free mass and high-density lipoprotein cholesterol levels. There were variable results on fibrosis, other liver enzymes, waist circumference and body mass index, as well as the levels of triglycerides, total cholesterol, and low-density lipoprotein cholesterol.

CONCLUSION

Any form of IF could be potentially beneficial for NAFLD treatment and some associated cardiometabolic parameters. However, it is necessary to evaluate the effects and safety of IF in long-term studies involving a higher number of participants with different stages of NAFLD. The effect of IF on NAFLD-associated vascular risk also needs evaluation.

Fibrosis-4 Index Predicts Long-Term All-Cause, Cardiovascular and Liver-Related Mortality in the Adult Korean Population

BACKGROUND & AIMS

Associations between hepatic fibrosis and mortality remain to be fully elucidated in large population-based studies. This study aimed to evaluate the associations of the fibrosis-4 index (FIB-4) with all-cause, cardiovascular, cancer, and liver-related mortality in the adult Korean population without viral hepatitis.

METHODS

Baseline data were retrieved from the Korea National Health and Nutrition Examination Survey, and mortality data were retrieved from the Korean Cause of Death data registry. Adults (age, ≥19 y) without viral hepatitis B or C, liver cirrhosis, any cancer, stroke, myocardial infarction, angina pectoris, or renal failure at baseline were eligible. Presumed hepatic fibrosis was evaluated with FIB-4. Hazard ratios (HRs) and 95% CIs were calculated using multivariable Cox regression analysis, and Kaplan-Meier estimates of the cumulative mortality were evaluated.

RESULTS

There were 46,456 individuals with a median follow-up period of 8.6 years (interquartile range, 6.3-10.6 y). Kaplan-Meier curves for cumulative mortality showed that participants with a FIB-4 of ≥2.67 (vs FIB-4, <2.67) had higher cumulative all-cause, cardiovascular, cancer, and liver-related mortality. In the fully adjusted model, Cox regression analysis revealed that presumed advanced hepatic fibrosis (FIB-4, ≥2.67) remained associated with all-cause mortality (HR, 1.64; 95% CI, 1.23-2.18), cardiovascular mortality (HR, 2.96; 95% CI, 1.60-5.46), and liver-related mortality (HR, 10.50; 95% CI, 4.70-23.44), but not cancer mortality, after adjusting for confounders including central obesity and insulin resistance. Excluding participants with an estimated alcohol intake of 30 grams or more for men and 20 grams or more for women did not affect the results.

CONCLUSIONS

At the population level, liver fibrosis estimated by FIB-4 was associated with increased cumulative all-cause, cardiovascular, and liver-related mortality.

Current status of disparity in liver disease

Disparities have emerged as an important issue in many aspects of healthcare in developed countries and may be based on race, ethnicity, sex, geographical location, and socioeconomic status. For liver disease specifically, these potential disparities can affect access to care and outcome in viral hepatitis, chronic liver disease, and hepatocellular carcinoma. Shortages in hepatologists and medical providers versed in liver disease may amplify these disparities by compromising early detection of liver disease, surveillance for hepatocellular carcinoma, and prompt referral to subspecialists and transplant centers. In the United States, continued efforts have been made to address some of these disparities with better education of healthcare providers, use of telehealth to enhance access to specialists, reminders in electronic medical records, and modifying organ allocation systems for liver transplantation. This review will detail the current status of disparities in liver disease and describe current efforts to minimize these disparities.

Nonalcoholic fatty liver disease shows significant sex dimorphism

Nonalcoholic fatty liver disease (NAFLD), which has been renamed metabolic dysfunction-associated fatty liver disease, is a growing global medical problem. The incidence of NAFLD and its associated end-stage liver disease is increasing each year, and many research advancements have been achieved to date. This review focuses on the current knowledge of the sex differences in NAFLD and does not elaborate on areas without differences. Studies have revealed significant sex differences in the prevalence, influencing factors, pathophysiology, complications and therapies of NAFLD. Men have a higher incidence than women. Compared with women, men exhibit increased visceral fat deposition, are more susceptible to leptin resistance, lack estrogen receptors, and tend to synthesize fatty acids into fat storage. Male patients will experience more severe hepatic fibrosis and a higher incidence of liver cancer. However, once NAFLD occurs, women show a faster progression of liver fibrosis, higher levels of liver cell damage and inflammation and are less likely to undergo liver transplantation than men. In general, men have more risk factors and more severe pathophysiological reactions than women, whereas the development of NAFLD is faster in women, and the treatments for women are more limited than those for men. Thus, whether sex differences should be considered in the individualized prevention and treatment of NAFLD in the future is worth considering.

Magnetic Resonance Imaging Assessment of Abdominal Ectopic Fat Deposition in Correlation With Cardiometabolic Risk Factors

PURPOSE

Ectopic fat accumulation and abdominal fat distribution may have different cardiometabolic risk profiles. This study aimed to assess the associations between various magnetic resonance imaging (MRI)-acquired fat depots and cardiometabolic risk factors.

METHODS

A total of 320 subjects with median age of 59 years, 148 men and 172 women, were enrolled in the study. Visceral adipose tissue (VAT) area and fat fraction (FF), subcutaneous adipose tissue (SAT) area and FF at the L1-L2 levels, preperitoneal adipose tissue (pPAT) area and FF, hepatic FF, pancreatic FF, and intramuscular FF were assessed by MRI FF maps. The associations of various MRI-acquired fat depots with blood pressure, glucose, and lipid were examined using sex-stratified linear regression. Logistic regression stratified by sex was used to analyze the association of various MRI-acquired fat depots with the risk of hypertension, T2DM, and dyslipidemia.

RESULTS

The intraclass correlation coefficient (ICC) values were >0.9, which suggested good interobserver and intraobserver agreement. VAT area, V/S, hepatic fat, pancreatic fat, and pPAT rather than SAT area were significantly associated with multiple cardiometabolic risk factors (all p < 0.05). However, the patterns of these correlations varied by sex and specific risk factors. Also, VAT and SAT FF were only significantly associated with multiple cardiometabolic risk factors in women (all p < 0.05).

CONCLUSIONS

VAT, hepatic fat, pancreatic fat, and pPAT were associated with cardiovascular metabolic risk factors independent of BMI. The patterns of these correlations were related to gender. These findings further the understanding of the association between ectopic fat deposition and cardiometabolic risk factors and help to better understand the obesity heterogeneity.

Hepatic Igf1-Deficiency Protects Against Atherosclerosis in Female Mice

Atherosclerosis is the leading cause of cardiovascular disease (CVD), with distinct sex-specific pathogenic mechanisms that are poorly understood. Aging, a major independent risk factor for atherosclerosis, correlates with a decline in circulating insulin-like growth factor-1 (IGF-1). However, the precise effects of Igf1 on atherosclerosis remain unclear. In the present study, we assessed the essential role of hepatic Igf1, the major source of circulating IGF-1, in atherogenesis. We generated hepatic Igf1-deficient atherosclerosis-prone apolipoprotein E (ApoE)-null mice (L-Igf1-/-ApoE-/-) using the Cre-loxP system driven by the Albumin promoter. Starting at 6 weeks of age, these mice and their littermate controls, separated into male and female groups, were placed on an atherogenic diet for 18 to 19 weeks. We show that hepatic Igf1-deficiency led to atheroprotection with reduced plaque macrophages in females, without significant effects in males. This protection from atherosclerosis in females was associated with increased subcutaneous adiposity and with impaired lipolysis. Moreover, this impaired lipid homeostasis was associated with disrupted adipokine secretion with reduced circulating interleukin-6 (IL-6) levels. Together, our data show that endogenous hepatic Igf1 plays a sex-specific regulatory role in atherogenesis, potentially through athero-promoting effects of adipose tissue-derived IL-6 secretion. These data provide potential novel sex-specific mechanisms in the pathogenesis of atherosclerosis.

Impact of liver-specific GLUT8 silencing on fructose-induced inflammation and omega oxidation

Excessive consumption of high-fructose diets is associated with insulin resistance, obesity, and non-alcoholic fatty liver disease (NAFLD). However, fructose differentially affects hepatic regulation of lipogenesis in males and females. Hence, additional studies are necessary in order to find strategies taking gender disparities in fructose-induced liver damage into consideration. Although the eighth member of facilitated glucose transporters (GLUT8) has been linked to fructose-induced macrosteatosis in female mice, its contribution to the inflammatory state of NAFLD remains to be elucidated. Combining pharmacological, biochemical, and proteomic approaches, we evaluated the preventive effect of targeted liver GLUT8 silencing on liver injury in a mice female fructose-induced non-alcoholic steatohepatitis female mouse model. Liver GLUT8-knockdown attenuated fructose-induced ER stress, recovered liver inflammation, and dramatically reduced fatty acid content, in part, via the omega oxidation. Therefore, this study links GLUT8 with liver inflammatory response and suggests GLUT8 as a potential target for the prevention of NAFLD.

Nonalcoholic fatty liver disease and cardiovascular disease phenotypes

Nonalcoholic fatty liver disease is increasingly recognized as a major global health problem. Intertwined with diabetes, metabolic syndrome, and obesity, nonalcoholic fatty liver disease embraces a spectrum of liver conditions spanning from steatosis to inflammation, fibrosis, and liver failure. Compared with the general population, the prevalence of cardiovascular disease is higher among nonalcoholic fatty liver disease patients, in whom comprehensive cardiovascular risk assessment is highly desirable. Preclinical effects of nonalcoholic fatty liver disease on the heart include both metabolic and structural changes eventually preceding overt myocardial dysfunction. Particularly, nonalcoholic fatty liver disease is associated with enhanced atherosclerosis, heart muscle disease, valvular heart disease, and arrhythmias, with endothelial dysfunction, inflammation, metabolic dysregulation, and oxidative stress playing in the background. In this topical review, we aimed to summarize current evidence on the epidemiology of nonalcoholic fatty liver disease, discuss the pathophysiological links between nonalcoholic fatty liver disease and cardiovascular disease, illustrate nonalcoholic fatty liver disease-related cardiovascular phenotypes, and finally provide a glimpse on the relationship between nonalcoholic fatty liver disease and cardiac steatosis, mitochondrial (dys)function, and cardiovascular autonomic dysfunction.

Low Liver Density Is Linked to Cardiovascular Comorbidity in COPD: An ECLIPSE Cohort Analysis

Purpose

Fatty liver disease is associated with cardiometabolic disorders and represents a potential key comorbidity in Chronic Obstructive Pulmonary Disease (COPD). Some intermediary mechanisms of fatty liver disease (including its histological component steatosis) include tissue hypoxia, low-grade inflammation and oxidative stress that are key features of COPD. Despite these shared physiological pathways, the effect of COPD on the prevalence of hepatic steatosis, and the association between hepatic steatosis and comorbidities in this population remain unclear. Liver density measured by computed tomography (CT)-scan is a non-invasive surrogate of fat infiltration, with lower liver densities reflecting more fat infiltration and a liver density of 40 Hounsfield Units (HU) corresponding to a severe 30% fat infiltration.

Patients and Methods

We took advantage of the international cohort ECLIPSE in which non-enhanced chest CT-scans were obtained in 1554 patients with COPD and 387 healthy controls to analyse the liver density at T12-L1.

Results

The distribution of liver density was similar and the prevalence of severe steatosis (density<40 HU) was not different (4.7% vs 5.2%, p=0.7) between COPD and controls. In patients with COPD, the lowest liver density quartile was associated, after age and sex adjustment, with coronary artery disease (OR_a=1.59, 95% CI 1.12 to 2.24) and stroke (OR_a=2.20, 95% CI 1.07 to 4.50), in comparison with the highest liver density quartile.

Conclusion

The present data indicate that a low liver density emerged as a predictor of cardiovascular comorbidities in the COPD population. However, the distribution of liver density and the prevalence of severe steatosis were similar in patients with COPD and control subjects.

NAFLD and HIV: Do Sex, Race, and Ethnicity Explain HIV-Related Risk?

PURPOSE OF REVIEW

Here, we review the epidemiology, diagnosis, and management of non-alcoholic fatty liver disease (NAFLD) in the general population, discuss HIV-specific differences in NAFLD pathogenesis, and summarize what is known regarding differences in NAFLD by race/ethnicity and sex.

RECENT FINDINGS

The reported prevalence of NAFLD among people living with HIV varies by age, body mass index, comorbidity, and method of NAFLD diagnosis, but is generally thought to be greater among HIV-infected compared to HIV-uninfected populations. Minorities and women tend to experience poorer HIV treatment outcomes (Meditz et al. J Infect Dis. 203(4):442-51, 2011; Beer et al. Medicine (Baltimore). 95(13):e 3171, 2016; Gant et al. MMWR Morb Mortal Wkly Rep. 66(40):1065-72, 2017; Millett et al. Lancet. 380(9839):341-8, 2012; Wejnert et al. J Infect Dis. 213(5):776-83, 2016), and are at the greatest risk for significant weight gain with HIV treatment (Erlandson et al. Medicine (Baltimore). 95(46):e 5399, 2016). Thus, women and minorities living with HIV may be at a higher risk of developing NAFLD and progressive liver disease. Disparities in the diagnosis, progression, and prognosis of NAFLD and HIV-associated NAFLD may be, in part, explained by genetic and sex differences; however, data is limited.

Non-HDL cholesterol and LDL cholesterol in the dyslipidemic classification in patients with nonalcoholic fatty liver disease

BACKGROUND

Low-density lipoprotein cholesterol (LDL-C) always underestimates the true cholesterol burden in patients with nonalcoholic fatty liver disease (NAFLD). We aimed to compare LDL-C and non-high-density lipoprotein cholesterol (non-HDL-C) in the identification of high-risk dyslipidemic phenotypes in those with NAFLD.

METHODS

We conducted a cross-sectional analysis using a cohort of 9560 apparently healthy Chinese adults who underwent comprehensive health checkups including abdominal ultrasonography.

RESULTS

Among 3709 patients with NAFLD, the prevalence of abnormal LDL using LDL-C was 68.5%, whereas the prevalence was relatively lower when using non-HDL-C (55.9%). The concordance between non-HDL-C- and LDL-C-based diagnoses of abnormal LDL was similar in the hypertriglyceridemic (ҝ = 0.56; 95% CI 0.52-0.60) and normotriglyceridemic subgroups (ҝ = 0.47; 95% CI 0.44-0.51). Non-HDL-C detected fewer patients with abnormal LDL than LDL-C in normotriglyceridemic patients. However, non-HDL-C detected more patients with abnormal LDL than LDL-C in hypertriglyceridemic patients: 114 of the 1662 patients considered as abnormal LDL according to LDL-C fell into the normonon-HDL-C phenotype, whereas 204 of the 1662 patients considered as abnormal LDL according to non-HDL-C fell into the normoLDL-C phenotype.

CONCLUSION

Among patients with NAFLD, LDL-C is superior to non-HDL-C in the detection of high-risk phenotypes in normotriglyceridemic patients, whereas non-HDL-C seems to be superior in hypertriglyceridemic patients.

Aberrant activation of the human sex-determining gene in early embryonic development results in postnatal growth retardation and lethality in mice

Sexual dimorphisms are prevalent in development, physiology and diseases in humans. Currently, the contributions of the genes on the male-specific region of the Y chromosome (MSY) in these processes are uncertain. Using a transgene activation system, the human sex-determining gene hSRY is activated in the single-cell embryos of the mouse. Pups with hSRY activated (hSRYON) are born of similar sizes as those of non-activated controls. However, they retard significantly in postnatal growth and development and all die of multi-organ failure before two weeks of age. Pathological and molecular analyses indicate that hSRYON pups lack innate suckling activities, and develop fatty liver disease, arrested alveologenesis in the lung, impaired neurogenesis in the brain and occasional myocardial fibrosis and minimized thymus development. Transcriptome analysis shows that, in addition to those unique to the respective organs, various cell growth and survival pathways and functions are differentially affected in the transgenic mice. These observations suggest that ectopic activation of a Y-located SRY gene could exert male-specific effects in development and physiology of multiple organs, thereby contributing to sexual dimorphisms in normal biological functions and disease processes in affected individuals.