Loss of NAT10 alleviates maternal high-fat diet-induced hepatic steatosis in male offspring of mice.

OBJECTIVE: Metabolic dysfunction-associated steatotic liver disease (MASLD) is becoming an escalating health problem in pediatric populations. This study aimed to investigate the role of N-acetyltransferase 10 (NAT10) in maternal high-fat diet (HFD)-induced MASLD in offspring at early life. METHODS: We generated male hepatocyte-specific NAT10 knockout (Nat10HKO) mice and mated them with female Nat10fl/fl mice under chow or HFD feeding. Body weight, liver histopathology, and expression of lipid metabolism-associated genes (Srebp1c, Fasn, Pparα, Cd36, Fatp2, Mttp, and Apob) were assessed in male offspring at weaning. Lipid uptake assays were performed both in vivo and in vitro. The mRNA stability assessment and RNA immunoprecipitation were performed to determine NAT10-regulated target genes. RESULTS: NAT10 deletion in hepatocytes of male offspring alleviated perinatal lipid accumulation induced by maternal HFD, decreasing expression levels of Srebp1c, Fasn, Cd36, Fatp2, Mttp, and Apob while enhancing Pparα expression. Furthermore, Nat10HKO male mice exhibited reduced lipid uptake. In vitro, NAT10 promoted lipid uptake by enhancing the mRNA stability of CD36 and FATP2. RNA immunoprecipitation assays exhibited direct interactions between NAT10 and CD36/FATP2 mRNA. CONCLUSIONS: NAT10 deletion in offspring hepatocytes ameliorates maternal HFD-induced hepatic steatosis through decreasing mRNA stability of CD36 and FATP2, highlighting NAT10 as a potential therapeutic target for pediatric MASLD.

Sestrin2 maintains hepatic immune homeostasis and redox balance partially via inhibiting RIPK3-mediated necroptosis in metabolic dysfunction-associated steatohepatitis.

BACKGROUND & AIMS: Necroptosis, a novel type of programmed cell death, is intricately associated with inflammatory response. Currently, most studies focus on the activation of necroptosis, while the mechanisms underlying the negative regulation of necroptosis remain poorly understood. METHODS: The effects of sestrin2 (SESN2) overexpression or knockdown on the regulation of necroptosis were assessed in the TNFα/Smac-mimetic/Z-VAD-FMK (T/S/Z)-induced necroptosis model and palmitic acid (PA)-induced lipotoxicity model. Western-blot, co-Immunoprecipitation, Glutathione S-transferase pull-down, and confocal assays were employed to explore the regulatory mechanisms including protein-protein interactions and post-translational modification. Furthermore, we used GSK'872, a specific inhibitor of receptor-interacting serine/threonine-protein kinase (RIPK) 3, to evaluate the relationship between SESN2-related alterations and RIPK3-mediated necroptosis in T/S/Z-induced necroptosis model, PA-induced lipotoxicity model, and high-fat high-cholesterol diet (HFHCD)-induced non-alcoholic steatohepatitis model. RESULTS: Our findings revealed that SESN2 was upregulated under conditions that induce necroptosis and functioned as a negative regulator of necroptosis. High levels of SESN2 could equipped hepatocytes with the ability to defend against necroptotic inflammation and oxidative stress. Mechanistically, SESN2 interacted with RIPK3 and tuned down necroptosis by inhibiting the phosphorylation of RIPK3, promoting the ubiquitination of RIPK3, and preventing the formation of the RIPK1/RIPK3 necrosome. The depletion of SESN2 resulted in excessive necroptosis, accompanied by increased fat accumulation, inflammation, and oxidative stress in the experimental steatohepatitis model. Blocking necroptosis by GSK'872 reduced the liberation of pro-inflammatory cytokines and reactive oxygen species generation, but not hepatocyte fat deposition, in both PA-treated SESN2 knockout cells and HFHCD-fed SESN2 knockout mice, suggesting that the activation of RIPK3-mediated necroptosis may partially account for the hyperinflammation and excessive oxidative stress induced by SESN2 deficiency. CONCLUSION: Our results suggested that SESN2 inhibited RIPK3-mediated necroptosis; this regulation is an important for the immune homeostasis and the redox balance in the liver.

Early-life exposure to gestational diabetes mellitus predisposes offspring to pediatric nonalcoholic fatty liver disease.

Nonalcoholic fatty liver disease (NAFLD) has emerged as the prevailing chronic liver disease in the pediatric population due to the global obesity pandemic. Evidence shows that prenatal and postnatal exposure to maternal abnormalities leads to a higher risk of pediatric NAFLD through persistent alterations in developmental programming. Gestational diabetes mellitus (GDM) is a hyperglycemic syndrome which has become the most prevalent complication in pregnant women. An increasing number of both epidemiologic investigations and animal model studies have validated adverse and long-term outcomes in offspring following GDM exposure in utero. Similarly, GDM is considered a crucial risk factor for pediatric NAFLD. This review aimed to summarize currently published studies concerning the inductive roles of GDM in offspring NAFLD development during childhood and adolescence. Dysregulations in hepatic lipid metabolism and gut microbiota in offspring, as well as dysfunctions in the placenta are potential factors in the pathogenesis of GDM-associated pediatric NAFLD. In addition, potentially effective interventions for GDM-associated offspring NAFLD are also discussed in this review. However, most of these therapeutic approaches still require further clinical research for validation.

The burden and sexual dimorphism with nonalcoholic fatty liver disease in Asian children: A systematic review and meta-analysis.

BACKGROUND: Despite substantial attention paid to the epidemic of nonalcoholic fatty liver disease (NAFLD) in adults, data on the burden and sexual dimorphism of NAFLD in Asian children have not yet been synthesized. METHODS: We conducted a literature search of 735 references up to April 2021. Pooled analyses, stratified analyses and meta-regression were all performed. RESULTS: Thirty-three study populations were finally included. Nine of them comprising 20 595 children showed an overall NAFLD prevalence of 5.53% (95% CI 3.46%-8.72%), in which, 36.64% (95% CI, 27.99%-46.26%) NAFLD subjects had elevated levels of ALT. The prevalence rate of NAFLD increased about 1.6-fold from 2004 to 2010 to the last decade. Male predominant trends were observed in paediatric NAFLD (boys: 8.18%, 95% CI 4.93%-13.26%; girls: 3.60%, 95% CI 1.60%-7.87%). Moreover, meta-analysis showed that after 10 years of age, boys were more prone to have NAFLD than girls (OR = 1.75; P = .0012). In addition, the pooled prevalence of NAFLD increased sequentially in normal-weight (1.49%, 95% CI 0.88%-2.51%, n = 2610), overweight (16.72%, 95% CI 7.07%-34.65%, n = 1265) and obese children (50.13%, 95% CI 41.99%-58.27%, n = 6434 individuals). After full covariate adjustment, the multivariate meta-regression also showed that boy percentage (P = .0396) and body mass index (P < .0001) were positively correlated with prevalent NAFLD. CONCLUSIONS: In Asia, paediatric NAFLD is becoming prevalent over the recent decades, particularly among obese children and boys after 10 years old. The hormonal and chromosomal origins of paediatric NAFLD dimorphism need further investigation.

Escherichia fergusonii Promotes Nonobese Nonalcoholic Fatty Liver Disease by Interfering With Host Hepatic Lipid Metabolism Through Its Own msRNA 23487.

BACKGROUND & AIMS: Gut microbiota and microbial factors regulate the pathogenesis of nonalcoholic fatty liver disease (NAFLD) in patients with obesity and metabolic abnormalities, but little is known about their roles in nonobese NAFLD. Expansion of Escherichia is associated with NAFLD pathogenesis. We aimed to investigate the pathogenic role of Escherichia fergusonii and its products in the development of nonobese NAFLD. METHODS: We characterized the intestinal microbiome signature in a cohort of NAFLD patients and healthy controls by 16S ribosomal RNA sequencing. The role of E fergusonii was estimated in rats after 16 weeks of administration, and features of NAFLD were assessed. E fergusonii-derived microRNA-sized, small RNAs (msRNAs) were analyzed by deep sequencing. RESULTS: We detected an expansion of Escherichia_Shigella in NAFLD patients compared with healthy controls, and its increase was associated with disease severity independent of obesity. E fergusonii, a member of the genus Escherichia, induced the development of nonobese NAFLD characterized by hepatic steatosis and hepatocyte ballooning in rats without obesity. It disturbed host lipid metabolism by inhibiting hepatic lipid ß-oxidation and promoting de novo lipogenesis. We also showed that E fergusonii caused the development of hepatic inflammation and fibrosis in a sizable fraction of animals at an advanced stage of NAFLD. Mechanistically, E fergusonii-derived msRNA 23487 down-regulated host hepatic peroxisome proliferator-activated receptor α expression, which could contribute to lipid accumulation in the liver. CONCLUSIONS: These results suggest that E fergusonii promotes the pathogenesis of steatohepatitis and fibrosis in nonobese rats by secreting msRNA 23487, and it might be a potential biomarker for predicting steatohepatitis in nonobese NAFLD.

Neonatal Milk Fat Globule Membrane Supplementation During Breastfeeding Ameliorates the Deleterious Effects of Maternal High-Fat Diet on Metabolism and Modulates Gut Microbiota in Adult Mice Offspring in a Sex-Specific Way.

Exposure to adverse events in early life increases the risk of chronic metabolic disease in adulthood. The objective of this study was to determine the significance of milk fat globule membrane (MFGM)-mediated alterations in the gut microbiome to the metabolic health of offspring in the long-term. Female C57BL/6 mice were fed either a high-fat diet (HFD) or a control diet for 3 weeks before pregnancy and throughout pregnancy and lactation. During lactation, pups from the HFD group were breast-fed with or without 1,000 mg/kg BW/day MFGM supplementation (HFD and HFD-MS group, respectively). After weaning, the offspring in each group were divided into male and female subgroups. The weaned mice were then shifted to a control diet for 8 weeks. At the eleventh week, stool samples were collected for 16S rRNA gene sequencing. Serum biochemical parameters were analyzed, and intraperitoneal glucose and insulin tolerance tests were performed. Neonatal supplementation with MFGM ameliorated metabolic disorder and improved glucose tolerance in offspring exposed to maternal HFD in a sex-specific manner. Furthermore, maternal HFD induced gut microbiota perturbation in offspring in adulthood. Neonatal MFGM supplementation significantly enriched g-Parabacteroides, g-Bifidobacterium, g-Faecalibaculum, and g-Lactobacillus in male offspring exposed to maternal HFD, while significantly enriched g-Parabacteroides and g-Alistipes in female offspring exposed to maternal HFD. These bacteria may be associated with the favorable changes in metabolism that occur in adulthood. Sex differences in the changes of metagenomic pathways related to oxidative phosphorylation, citrate cycle, electron transfer carries, and ubiquinone biosynthesis were also observed in the offspring. Maternal HFD has an adverse effect on the metabolism of offspring in later life. Neonatal MFGM supplementation could modulate the structure of gut microbiota communities and may have long-term protective effects on lipid and glucose metabolism, but these effects are sex dimorphic.

Milk Fat Globule Membrane Supplementation During Suckling Ameliorates Maternal High Fat Diet-Induced Hepatic Steatosis in Adult Male Offspring of Mice.

BACKGROUND: Exposure to a maternal high-fat diet (HFD) predisposes offspring to nonalcoholic fatty liver disease. OBJECTIVES: The aim of this study was to explore whether milk fat globule membrane (MFGM) supplementation during suckling exerts a long-term protective effect on hepatic lipid metabolism in adult offspring exposed to maternal HFD. METHODS: We fed 5-week-old female C57BL/6J mice either a HFD (60% kcal fat) or control diet (CD; 16.7% kcal fat) for 3 weeks before mating, as well as throughout gestation and lactation. After delivery, male offspring from HFD dams were supplemented with 1 g/(kg body weight·day) MFGM (HFD + MFGM group) or the same volume of vehicle (HFD group) during suckling. Male offspring from CD dams were also supplemented with vehicle during suckling (CD group). All offspring were weaned onto CD for 8 weeks. Histopathology, metabolic parameters, lipogenic level, oxidative stress, and mitochondria function in the liver were analyzed. A 1-way ANOVA and a Kruskal-Wallis test were used for multi-group comparisons. RESULTS: As compared to the CD group, the HFD group had more lipid droplets in livers, and exhibited ∼100% higher serum triglycerides, ∼38% higher hepatic triglycerides, ∼75% higher serum aspartate aminotransferase, and ∼130% higher fasting blood glucose (P < 0.05). The changes of these metabolic parameters were normalized in the HFD + MFGM group. Phosphorylated mammalian targets of rapamycin and AKT were downregulated, but phosphorylated adenosine monophosphate-activated protein kinase was upregulated in the HFD + MFGM group as compared to the HFD group (P < 0.05). As compared to the CD group, the HFD group showed an ∼80% higher malondialdehyde level, and ∼20% lower superoxide dismutase activity (P < 0.05), which were normalized in the HFD + MFGM group. Additionally, mitochondria function was also impaired in the HFD group and normalized in the HFD + MFGM group. CONCLUSIONS: MFGM supplementation during suckling ameliorates maternal HFD-induced hepatic steatosis in mice via suppressing de novo lipogenesis, reinforcing antioxidant defenses and improving mitochondrial function.

Maternal High-Fat Diet Leads to Non-alcoholic Fatty Liver Disease Through Upregulating Hepatic SCD1 Expression in Neonate Rats.

Non-alcoholic fatty liver disease (NAFLD) has become the leading cause of liver disease in children, with evidence that the maternal diet and the early life nutritional environment are potential risk for such disease. This study was aimed to investigate the effects of maternal high-fat diet (HFD) on the occurrence of NAFLD in offspring rats and the underlying mechanisms. In this study, the incidence of NAFLD was compared in F1 offspring rats between the maternal HFD group and standard chow (SC) group. In addition, the expression levels of inflammatory cytokines in the placenta, in the umbilical cord blood, and in the livers of neonate offsprings were compared between two groups. HepG2 cells were treated with recombinant IL6 (rIL6) to assess stearoyl-CoA desaturase 1 (SCD1) expression and lipid synthesis in an inflammatory condition. Lipid accumulation was assayed in both SCD1 overexpression and interference HepG2 cells as well as in neonatal rats. Our results showed that HFD exposure before and throughout the pregnancy induced the elevated hepatic TG content of F1 neonates. The levels of inflammatory cytokines in the placenta, umbilical cord blood, and the livers of HFD F1 neonates were significantly higher than those of the SC group. In addition, rIL6 treatment led to TG accumulation accompanied by the upregulation of SCD1 in HepG2 cell lines. Overexpression of SCD1 led to the accumulation of TG contents in HepG2 cells, whereas Scd1 knockdown attenuated the effects of rIL6 treatment. Overexpression of SCD1 in F1 neonatal rats led to hepatic lipid accumulation. Our study indicated that maternal HFD led to intrauterine inflammation, which subsequently caused transgenerationally abnormal hepatic lipid metabolism of F1 neonates. This modulation might be mediated by upregulating SCD1 expression in hepatic cells.

Inhibition of thioredoxin 2 by intracellular methylglyoxal accumulation leads to mitochondrial dysfunction and apoptosis in INS-1 cells.

PURPOSE: To investigate the role of thioredoxin 2 (Trx2) inhibition induced by intracellular methylglyoxal (MGO) in pancreatic beta-cell mitochondrial dysfunction and apoptosis. METHODS: Rat pancreatic beta-cell line INS-1 cells were treated with Glo1 siRNAs or exogenous MGO to increase intracellular MGO. AGEs formation was detected by ELISA and mitochondrial ROS was detected by probe MitoSOX. Transmission electron microscopy (TEM) analysis and ATP content were measured to evaluate mitochondrial function. Trx2 expression was manipulated by overexpression with recombinant Trx2 lentivirus or knockdown with Trx2 siRNAs, and effects on apoptosis and insulin secretion were measured by flow cytometry and ELISA, respectively. RESULTS: The increase of intracellular MGO by Glo1 blockage or MGO treatment led to advanced glycation end products (AGEs) overproduction, mitochondrial ROS increase, and insulin secretion paralysis. These were probably due to MGO-induced inhibition of mitochondrial Trx2. Trx2 inhibition by blockage of either Glo1 or Trx2 impaired mitochondrial integrity, inhibited cytochrome C oxidases subunit 1 and 4 (Cox1 and Cox4) expression and further reduced ATP generation, and all of these might lead to insulin paralysis; whereas Trx2 overexpression partially reversed MGO-induced oxidative stress, attenuated insulin secretion by preventing mitochondrial damage. Trx2 overexpression also retarded MGO-induced apoptosis of INS-1 cell through inhibiting ASK1 activation and downregulation of the ASK1-p38 MAPK pathway. CONCLUSIONS: Our results reveal a possible mechanism for beta-cell oxidative damage upon intracellular MGO-induced Trx2 inactivation and mitochondrial dysfunction and apoptosis.