Undernourishment in utero and hepatic steatosis in later life: A potential issue in Japanese people

Transcriptome analysis reveals hepatic disordered lipid metabolism, lipotoxic injury, and abnormal development in IUGR sheep fetuses due to maternal undernutrition during late pregnancy

Although lipid metabolism in fetal livers under intrauterine growth restriction (IUGR) conditions has been widely studied, the implications of maternal undernutrition on fetal hepatic lipid metabolism, lipotoxic injury, and abnormal development remain largely unknown. Therefore, this study investigated the effects of maternal undernutrition on disordered hepatic lipid metabolism, lipotoxic injury, and abnormal development in IUGR sheep fetuses using transcriptome analysis. Seventeen singleton ewes were randomly divided into three groups on day 90 of pregnancy: a control group (CG; 0.63 MJ metabolic energy/body weight (ME/BW)0.75/day, n = 5), maternal undernutrition group 1 (MU1; 0.33 MJ ME/BW0.75/day, n = 6), and maternal undernutrition group 2 (MU2; 0.20 MJ ME/BW0.75/day, n = 6). The fetuses were euthanized and recovered on day 130 of pregnancy. The levels of free fatty acids (FFA) in maternal blood (P < 0.01), fetal blood (P < 0.01), and fetal livers (P < 0.05) were increased in the MU1 and MU2 groups, but fetal hepatic triglyceride (TG) levels in the MU2 group (P < 0.01) and β-hydroxybutyrate levels in the MU1 and MU2 groups (P < 0.01) were decreased compared to the CG. Severe inflammatory cell infiltration and increased non-alcoholic fatty liver disease activity scores were observed in MU1 and MU2 fetuses (P < 0.01). Progressive deposition of fetal hepatic reticular fibers and collagen fibers in the fetal livers of the MU1 and MU2 groups and significant hepatic fibrosis were observed in the MU2 fetuses (P < 0.05). Gene set enrichment analysis showed that genes involved in lipid accumulation and FFA beta oxidation were downregulated in both MU groups compared to those in the controls. The fetal liver mRNA expression of the β-oxidation regulator, acetyl-CoA acetyltransferase 1, and the TCA regulator, isocitrate dehydrogenase were reduced in MU1 (P < 0.05) and MU2 (P < 0.01) fetuses, and downregulated mRNA expression of long chain fatty acid CoA ligase 1 (P < 0.05) and glycerol-3-phosphate acyltransferase (P < 0.01) was observed in MU2 fetuses. Differentially expressed genes (DEGs) in MU1 versus CG (360 DEGs) and MU2 versus CG (746 DEGs) were identified using RNA sequencing. Bioinformatics analyses of the 231 intersecting DEGs between MU1 versus CG and MU2 versus CG indicated that neutrophil extracellular traps (NETs) were induced and played a central role in fetal hepatic injury in IUGR sheep. Increased maternal blood myeloperoxidase (MPO) levels (P < 0.01), NE (Elane)-positive areas in fetal liver sections (P < 0.05), and fetal liver MPO protein expression (P < 0.01) were found in the MU1 and MU2 groups; however, MPO levels were reduced in the fetal membrane (P < 0.01) and fetal blood (P < 0.05) in the MU1 group, and in the maternal-fetal placenta and fetal blood in the MU2 group (P < 0.01). Analysis of gene expression trends in the intersecting DEGs between MU1 versus CG (129 DEGs) and MU2 versus CG (515 DEGs) further revealed that 30 hub genes were essential regulators of the G2/M cell cycle, all of which were associated with hepatocellular carcinoma. G0/G1 phase cells of the fetal liver were reduced in the MU1 (P < 0.05) and MU2 (P < 0.01) groups, whereas G2/M phase cells were elevated in the MU1 and MU2 groups (P < 0.01). The representatives of upregulated hub genes and fetal liver protein expression of maternal embryonic leucine zipper kinase and protein regulator of cytokinesis 1 were progressively enhanced in the MU1 and MU2 groups (P < 0.01), and topoisomerase II alpha protein expression in the MU2 group (P < 0.05), as expected. These results indicate that FFA overload, severe lipotoxic injury, and NETs were induced, and disease-promoting regulators of the G2/M cell cycle were upregulated in the fetal liver of IUGR sheep. These findings provide new insights into the pathogenesis of impaired hepatic lipid metabolism and abnormal development and the molecular origin of post-natal liver disease in IUGR due to maternal undernutrition. This information can support the development of new therapeutic strategies.

Induction of the Lipid Droplet Formation Genes in Steatohepatitis Mice by Embryo/Postnatal Nutrient Environment Is Associated with Histone Acetylation around the Genes

Recently, we have demonstrated that mice, cultured embryos in α-minimum essential medium (αMEM) and subsequent fed a high-fat, high-sugar diet, developed steatohepatitis. In this study, we investigated using these samples whether the expression of lipid droplet formation genes in the liver is higher in MEM mice, whether these expressions are regulated by histone acetylation, writers/readers of histone acetylation, and the transcriptional factors of endoplasmic reticulum stress. Mice were produced by two-cell embryos in αMEM or standard potassium simplex-optimized medium (control) in vitro for 48 h, and implanted into an oviduct for spontaneous delivery. MEM and control-mice were fed a high-fat, high-sugar diet for 18 wk, and then liver samples were collected and analyzed by histology, qRT-PCR, and chromatin immunoprecipitation assay. Gene expression of Cidea, Cidec, and Plin4 were higher in MEM mice and histone H3K9 acetylation, BRD4, and CBP were higher in MEM mice than in control mice around those genes. However, the binding of endoplasmic reticulum stress-related transcription factors (ATF4, CHOP and C/EBPα) around those genes in the liver, was not clearly differed between MEM mice and control mice. The increased expression of Cidea, Cidec and Plin4 in the liver, accompanied by the development of steatohepatitis in mice induced is positively associated with increased histone H3K9 acetylation and CBP and BRD4 binding around these genes.

Metabolomics and Lipidomics Study Unveils the Impact of Tauroursodeoxycholic Acid on Hyperlipidemic Mice

Bear bile powder is an essential, traditional and valuable Chinese herbal medicine that clears heat, calms the liver, and improves eyesight. Early studies have shown that bear bile powder has lipid-lowering activity, but due to the scarcity of natural bear bile powder resources, it has yet to be used on a large scale. Researchers have found that tauroursodeoxycholic acid (TUDCA) is the primary characteristic bioactive substance of bear bile powder. This study aimed to investigate the therapeutic effect of TUDCA on high-fat diet (HFD)-induced hyperlipidemia. A hyperlipidemia model was established by feeding mice high-fat chow, following the intervention of different concentrations of TUDCA (25/50/100 mg/kg) orally, the hallmark biochemical indexes (total cholesterol (TC), total triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C)), histopathological examination (hematoxylin-eosin (HE) staining and oil red O (ORO) staining), and metabolomic analysis of serum and liver. The results showed that TUDCA could downregulate total TC, TG, LDL-C, upregulate HDL-C, reduce fat deposition in hepatocytes, reverse hepatocyte steatosis, and exhibit prominent lipid-lowering activity. In addition, it may play a therapeutic role by regulating glycerophospholipid metabolism.

Gestation Food Restriction and Refeeding Compensate Maternal Energy Status and Alleviate Metabolic Consequences in Juvenile Offspring in a Rabbit Model

Nutritional status during gestation can influence mother and offspring metabolism. Undernutrition in pregnancy affects women in both western and developing countries, and it is associated with a high prevalence of chronic diseases in later life. The present work was conducted in the rabbit model, as a longitudinal study, to examine the effect of food restriction during early and mid-gestation, and re-feeding ad libitum until the end of pregnancy on metabolic status and body reserves of mother and, its association with development and metabolism of fetuses and female offspring to the juvenile stage. Little changes in live body weight (LBW), compensatory feed intake, similar body reserves, and metabolism were observed in dams. Placenta biometry and efficiency were slightly affected, but fetal BW and phenotype were not modified. However, hyperinsulinemia, insulin resistance, and hypertriglyceridemia were demonstrated in pre-term fetuses. In the juvenile period, these changes were not evidenced, and a similar pattern of growth and serum metabolic parameters in offspring of food-restricted mothers were found, except in serum aminotransferases levels, which increased. These were associated with higher liver fibrosis. Maternal food restriction in the early and mid-pregnancy followed by re-feeding in our rabbit model established a compensatory energy status in dams and alleviated potential long-term consequences in growth and metabolism in the offspring, even if fetal metabolism was altered.

Fetal alcohol spectrum disorder predisposes to metabolic abnormalities in adulthood

Prenatal alcohol exposure (PAE) affects at least 10% of newborns globally and leads to the development of fetal alcohol spectrum disorders (FASDs). Despite its high incidence, there is no consensus on the implications of PAE on metabolic disease risk in adults. Here, we describe a cohort of adults with FASDs that had an increased incidence of metabolic abnormalities, including type 2 diabetes, low HDL, high triglycerides, and female-specific overweight and obesity. Using a zebrafish model for PAE, we performed population studies to elucidate the metabolic disease seen in the clinical cohort. Embryonic alcohol exposure (EAE) in male zebrafish increased the propensity for diet-induced obesity and fasting hyperglycemia in adulthood. We identified several consequences of EAE that may contribute to these phenotypes, including a reduction in adult locomotor activity, alterations in visceral adipose tissue and hepatic development, and persistent diet-responsive transcriptional changes. Taken together, our findings define metabolic vulnerabilities due to EAE and provide evidence that behavioral changes and primary organ dysfunction contribute to resultant metabolic abnormalities.

Excessive folic acid supplementation in pregnant mice impairs insulin secretion and induces the expression of genes associated with fatty liver in their offspring

Objective

Previous human and animal studies have shown that excessive maternal intake of folic acid (FA) predisposes to impaired glucose tolerance in the offspring. However, the underlying mechanism is unknown. Therefore, we aimed to determine whether excessive supplementation with FA during pregnancy affects the glucose tolerance of mouse offspring.

Research methods & procedures

Pregnant C57BL/6J mice were fed AIN93G diet containing either 2 mg [control group (CN)] or 40 mg [high FA group (HFA)] FA/kg diet throughout their pregnancies. On postnatal days (PD)22 and 50, fasting blood glucose was measured in the offspring of both groups, and an oral glucose tolerance test (OGTT) was performed on PD50. On PD53, tissues were collected, and the tissue masses, area of insulin expression in the pancreas, liver triglyceride content, and gene expression were determined.

Results

The blood glucose concentrations at 60 and 120 min of the OGTT were higher in female HFA than CN offspring. The serum fasting and non-fasting insulin concentrations and the area of insulin expression in the pancreas were lower in HFA than CN offspring. The liver triglyceride content was higher in female, and tended to be higher in male (P < 0.05), HFA offspring than CN offspring (P < 0.05). The liver mRNA expression of fat synthesis genes, such as Pparγ2 (male and female) and Cidec (male), was higher in HFA than CN offspring (P < 0.05).

Conclusion

Excessive maternal supplementation of FA in mice leads to lower insulin synthesis and an impairment in hepatic fat metabolism in the offspring.

Tauroursodeoxycholic acid inhibits intestinal inflammation and barrier disruption in mice with non-alcoholic fatty liver disease

BACKGROUND AND PURPOSE

The gut-liver axis is associated with the progression of non-alcoholic fatty liver disease (NAFLD). Targeting the gut-liver axis and bile acid-based pharmaceuticals are potential therapies for NAFLD. The effect of tauroursodeoxycholic acid (TUDCA), a candidate drug for NAFLD, on intestinal barrier function, intestinal inflammation, gut lipid transport and microbiota composition was analysed in a murine model of NAFLD.

EXPERIMENTAL APPROACH

The NAFLD mouse model was established by feeding mice a high-fat diet (HFD) for 16 weeks. TUDCA was administered p.o. during the last 4 weeks. The expression levels of intestinal tight junction genes, lipid metabolic and inflammatory genes were determined by quantitative PCR. Tissue inflammation was evaluated by haematoxylin and eosin staining. The gut microbiota was analysed by 16S rRNA gene sequencing.

KEY RESULTS

TUDCA administration attenuated HFD-induced hepatic steatosis, inflammatory responses, obesity and insulin resistance in mice. Moreover, TUDCA attenuated gut inflammatory responses as manifested by decreased intestinal histopathology scores and inflammatory cytokine levels. In addition, TUDCA improved intestinal barrier function by increasing levels of tight junction molecules and the solid chemical barrier. The components involved in ileum lipid transport were also reduced by TUDCA administration in HFD-fed mice. Finally, the TUDCA-treated mice showed a different gut microbiota composition compared with that in HFD-fed mice but similar to that in normal chow diet-fed mice.

CONCLUSIONS AND IMPLICATIONS

TUDCA attenuates the progression of HFD-induced NAFLD in mice by ameliorating gut inflammation, improving intestinal barrier function, decreasing intestinal fat transport and modulating intestinal microbiota composition.

Developmental Origins of Nonalcoholic Fatty Liver Disease (NAFLD)

Nonalcoholic fatty liver disease (NAFLD) is a hepatic manifestation of metabolic syndrome. Its prevalence is currently increasing not only in developed obese countries but also in developing countries. Recent findings from human cohorts and animal studies suggest that a nutritional imbalance in the early critical period is causatively associated with the incidence of NAFLD in later life. Based on the current theory of the developmental origins of health and disease (DOHaD), undernourishment and overnourishment in utero are both hypothesized to prime the predisposition for hepatic fat storage. Current knowledge on the developmental origins of NAFLD is introduced in this chapter.