Sex- or gender-specific medicine in hepatology

Synergistic effects of prenatal nicotine exposure and post-weaning high-fat diet on hypercholesterolaemia in rat offspring of different sexes

Hypercholesterolaemia is considered a disease with intrauterine origin. Recently, we reported that prenatal nicotine exposure (PNE) induced an abnormal level of total cholesterol in rat offspring before and after birth. However, there were little data about sex differences in serum cholesterol level in PNE offspring. In addition, many previous studies reported that blood cholesterol is associated with daily diet. This study was designed to analyse the interaction among PNE, high-fat diet (HFD) and sex on cholesterol metabolism in the rat. Pregnant Wistar rats were administered 2 mg/kg nicotine subcutaneously from gestational day (GD) 11 until parturition. After weaning, pups were fed with normal diet or HFD till 24 weeks, and then, serum cholesterol phenotypes and hepatic cholesterol metabolism-related genes were tested. Results showed that PNE manifested a distinct programming effect on cholesterol phenotype and cholesterol metabolism-related genes. HFD aggregated PNE-induced hypercholesterolaemia in adult offspring and exacerbated liver cholesterol metabolism dysfunction in PNE offspring. There was no sex difference in serum cholesterol level, but there were interactions among PNE, HFD and sex on cholesterol metabolic genes in adult offspring, which indicates that cholesterol metabolism in female offspring is more likely to be affected by PNE and HFD. In conclusion, HFD exacerbated PNE-induced hypercholesterolaemia, and sex differences existed in liver cholesterol metabolic genes in PNE- or HFD-treated offspring.

Lessons from hepatocyte-specific Cyp51 knockout mice: impaired cholesterol synthesis leads to oval cell-driven liver injury

We demonstrate unequivocally that defective cholesterol synthesis is an independent determinant of liver inflammation and fibrosis. We prepared a mouse hepatocyte-specific knockout (LKO) of lanosterol 14α-demethylase (CYP51) from the part of cholesterol synthesis that is already committed to cholesterol. LKO mice developed hepatomegaly with oval cell proliferation, fibrosis and inflammation, but without steatosis. The key trigger was reduced cholesterol esters that provoked cell cycle arrest, senescence-associated secretory phenotype and ultimately the oval cell response, while elevated CYP51 substrates promoted the integrated stress response. In spite of the oval cell-driven fibrosis being histologically similar in both sexes, data indicates a female-biased down-regulation of primary metabolism pathways and a stronger immune response in males. Liver injury was ameliorated by dietary fats predominantly in females, whereas dietary cholesterol rectified fibrosis in both sexes. Our data place defective cholesterol synthesis as a focus of sex-dependent liver pathologies.

Gender specific medicine in liver diseases: A point of view

Gender medicine focuses on the patho-physiological, clinical, prevention and treatment differences in diseases that are equally represented in men and women. The purpose of gender medicine is to ensure that each individual man and woman receives the best treatment possible based on scientific evidence. The concept of “gender” includes not only the sexual characteristics of individuals but also physiological and psychological attributes of men and women, including risk factors, protective/aggravating effects of sexual hormones and variances linked to genetics and corporal structures that explain biological and physiological differences between men and women. It is very important to consider all the biological, physiological, functional, psychological, social and cultural characteristics to provide patients with individualized disease management. Herein, we critically analyze the literature regarding gender differences for diseases and acquired conditions of the most representative hepatic pathologies: primary biliary cirrhosis, autoimmune hepatitis, primary sclerosing cholangitis, non alcoholic fatty liver disease and alcoholic liver disease, and viral chronic hepatitis B and C. The last section addresses hemochromatosis, which is a prevalent iron overload disorder in the Caucasian population. This review aims to describe data from the literature concerning viral chronic hepatitis during pregnancy, management during pregnancy and delivery, and new effective drugs for the prevention of maternal infection transmission without significant adverse effects or complications.

Sex differences in the hepatic cholesterol sensing mechanisms in mice

Cholesterol is linked to many multifactorial disorders, including different forms of liver disease where development and severity depend on the sex. We performed a detailed analysis of cholesterol and bile acid synthesis pathways at the level of genes and metabolites combined with the expression studies of hepatic cholesterol uptake and transport in female and male mice fed with a high-fat diet with or without cholesterol. Lack of dietary cholesterol led to a stronger response of the sterol sensing mechanism in females, resulting in higher expression of cholesterogenic genes compared to males. With cholesterol in the diet, the genes were down-regulated in both sexes; however, males maintained a more efficient hepatic metabolic flux through the pathway. Females had higher content of hepatic cholesterol but this was likely not due to diminished excretion but rather due to increased synthesis and absorption. Dietary cholesterol and sex were not important for gallbladder bile acids composition. Neither sex up-regulated Cyp7a1 upon cholesterol loading and there was no compensatory up-regulation of Abcg5 or Abcg8 transporters. On the other hand, females had higher expression of the Ldlr and Cd36 genes. These findings explain sexual dimorphism of cholesterol metabolism in response to dietary cholesterol in a high-fat diet in mice, which contributes to understanding the sex-basis of cholesterol-associated liver diseases.

SNPs in the promoter region of the osteopontin gene as a possible host factor for sex difference in hepatocellular carcinoma development in patients with HCV

AIMS

Four single nucleotide polymorphisms (SNPs) exist in the promoter region of the osteopontin (OPN) gene, namely, the SNPs at nucleotide (nt) -155, -616, and -1748 showing linkage disequilibrium to each other, and an independent SNP at nt -443. The significance of these SNPs in the risk of hepatocellular carcinoma (HCC) development was examined in patients with hepatitis C virus (HCV).

METHODS

The SNPs at nt -155 and nt -443 were analyzed in 120 patients with HCC. The promoter activity was measured in HepG2 cells by the dual-luciferase reporter assay. The electrophoretic mobility shift assay was performed using nuclear extracts from the cells.

RESULTS

Peripheral platelet counts at the time of HCC detection were greater in women with homozygous deletion at nt -155 and C/C or C/T at nt -443 than in those showing other allelic combinations, while no such difference was observed in men. The promoter activity was greater in oligonucleotides with deletions at nt -155 and C at nt -443 than in those with other haplotypes. The mobility shift assay showed double and single complexes with oligonucleotides around nt -155 and nt -443, respectively. Binding activities were greater in deletion than in G in the case of the retarded complex in the former assay and in T than in C in the latter assay. The other complex in the former assay included SRY, showing an equivalent binding activity to oligonucleotides with both alleles.

CONCLUSION

OPN promoter SNPs may play a role in the sexual difference in the risk of HCC development through the regulation of OPN expression in patients with HCV.

Comparative hepatic proteome analysis between lean and obese rats fed a high-fat diet reveals the existence of gender differences

Gender differences in obesity stem from metabolic and hormonal differences between sexes and contribute to differences between women and men in health risks attributable to obesity. We hypothesized that liver may be an ideal target for the evaluation of gender differences in obesity development in response to a high-fat diet (HFD). Therefore, to test this hypothesis, we performed a global proteome analysis in the liver of lean and obese rats of both genders who were fed an HFD through 2-DE combined with MALDI-TOF-MS. When rats were exposed to HFD, male rats gained more body weight with increased values of plasma biochemical parameters than female rats. Image analysis and further statistical analysis of a 2-DE protein map allowed for the detection and identification of 34 proteins that were significantly modulated in a gender-dependent manner. We found 19 proteins showing identical gender-different regulation in both normal diet (ND) and HFD. Five proteins also showed clear gender differences in both ND and HFD; however, their regulation modes in HFD were opposite to those in ND. Of particular interest, 10 proteins showed gender differences only in either ND or HFD rats. Present proteomic insight into gender-dimorphic protein modulation in liver would aid in the improvement of gender awareness in the health-care system and in implementation of evidence-based gender-specific clinical recommendations.

Dietary cholesterol, female gender and n-3 fatty acid deficiency are more important factors in the development of non-alcoholic fatty liver disease than the saturation index of the fat

Background

The central feature of NAFLD is a disturbed fatty-acid metabolism with hepatic lipid accumulation. However, the factors that determine the severity of NAFLD, including the role of nutrition, gender, and plasma lipid levels, remain to be determined.

Methods

High-fat diets (42 en% fat), containing 0.2% cholesterol, were fed to male and female wild-type and hyperlipidemic APOE2ki C57BL/6J mice for three weeks. The fats were, in order of decreasing saturation, fractionated palm fat (fPF; ~95%), cocoa butter (CB; ~60%), olive oil (OO; ~15%), sunflower oil (SO; ~12%), and high-oleic-acid sunflower oil (hoSO; ~7%). Plasma and liver triglycerides (concentration and composition), liver inflammation (Ccl2, Cd68, Tnf-α mRNA), and infiltration of macrophages (Cd68, Cd11b immunohistochemistry) and neutrophils (Mpo) were quantified.

Results

Addition of cholesterol to a low-fat diet decreased plasma HDL and increased (V)LDL levels in APOE2ki mice. Plasma cholesterol levels in female, but not male APOE2ki mice correlated significantly with inflammation. Kupffer cells of inflamed livers were swollen. Wild-type mice refused the highly saturated fPF diet. The high-fat CB, OO, and SO diets induced hyperglycemia and a 2-fold increase in hepatic fat content in male, but not female wild-type mice (in females, hepatic fat content was similar to that in males fed a high-fat diet). All high-fat diets induced macrovesicular setatosis. APOE2ki mice were protected against high-fat diet-induced steatosis and hyperglycemia, except when fed a hoSO diet. This diet caused a 5-fold increase in liver triglyceride and mead-acid content, and an increased expression of lipogenic genes, suggesting a deficiency in poly-unsaturated fatty acids. Irrespective of the composition of the high-fat diet, oleic acid was the main triglyceride component of liver fat in wild-type and APOE2ki mouse livers. Liver inflammation was dependent on genotype (APOE2ki > wild type), gender (female > male), and cholesterol content (high > low) of the diet, but not on dietary fat composition.

Conclusions

Dietary cholesterol plays a determining, independent role in inflammation, especially in female mice. The fatty-acid saturation of the diet hardly affected hepatic steatosis or inflammation.