Developmental origins of nonalcoholic fatty liver disease as a risk factor for exaggerated metabolic and cardiovascular-renal disease

Glucocorticoids and intrauterine programming of nonalcoholic fatty liver disease

Accumulating epidemiological and experimental evidence indicates that nonalcoholic fatty liver disease (NAFLD) has an intrauterine origin. Fetuses exposed to adverse prenatal environments (e.g., maternal malnutrition and xenobiotic exposure) are more susceptible to developing NAFLD after birth. Glucocorticoids are crucial triggers of the developmental programming of fetal-origin diseases. Adverse intrauterine environments often lead to fetal overexposure to maternally derived glucocorticoids, which can program fetal hepatic lipid metabolism through epigenetic modifications. Adverse intrauterine environments program the offspring's glucocorticoid-insulin-like growth factor 1 (GC-IGF1) axis, which contributes to postnatal catch-up growth and disturbs glucose and lipid metabolism. These glucocorticoid-driven programming alterations increase susceptibility to NAFLD in the offspring. Notably, after delivery, offspring often face an environment distinct from their in utero life. The mismatch between the intrauterine and postnatal environments can serve as a postnatal hit that further disturbs the programmed endocrine axes, accelerating the onset of NAFLD. In this review, we summarize the current epidemiological and experimental evidence demonstrating that NAFLD has an intrauterine origin and discuss the underlying intrauterine programming mechanisms, focusing on the role of overexposure to maternally derived glucocorticoids. We also briefly discuss potential early life interventions that may be beneficial against fetal-originated NAFLD.

The association between perinatal factors and cardiometabolic risk factors in children and adolescents with overweight or obesity: A retrospective two-cohort study

BACKGROUND

Children with obesity have an increased risk of cardiometabolic risk factors, but not all children carry a similar risk. Perinatal factors, i.e., gestational age (GA) and birth weight for GA, may affect the risk for metabolic complications. However, there are conflicting data whether the association between birth size and cardiometabolic risk factors is independent among children with obesity. Moreover, differential effects of GA and birth weight for GA on cardiometabolic risk factors in pediatric obesity are still unexplored. We aimed to investigate the association between birth weight for GA and cardiometabolic risk factors in children and adolescents with overweight or obesity and to assess whether the association is modified by prematurity.

METHODS AND FINDINGS

We conducted a retrospective study of 2 cohorts, using data from the world's 2 largest registers of pediatric obesity treatment-The Swedish childhood obesity treatment register (BORIS) and The Adiposity Patients Registry (APV) (1991 to 2020). Included were individuals with overweight or obesity between 2 to 18 years of age who had data of birth characteristics and cardiometabolic parameters. Birth data was collected as exposure variable and the first reported cardiometabolic parameters during pediatric obesity treatment as the main outcome. The median (Q1, Q3) age at the outcome measurement was 11.8 (9.4, 14.0) years. The main outcomes were hypertensive blood pressure (BP), impaired fasting glucose, elevated glycated hemoglobin (HbA1c), elevated total cholesterol, elevated low-density lipoprotein (LDL) cholesterol, elevated triglycerides, decreased high-density lipoprotein (HDL) cholesterol, and elevated transaminases. With logistic regression, we calculated the odds ratio (OR) and its 95% confidence interval (CI) for each cardiometabolic parameter. All the analyses were adjusted for sex, age, degree of obesity, migratory background, and register source. In total, 42,760 (51.9% females) individuals were included. Small for GA (SGA) was prevalent in 10.4%, appropriate for GA (AGA) in 72.4%, and large for GA (LGA) in 17.2%. Most individuals (92.5%) were born full-term, 7.5% were born preterm. Median (Q1, Q3) body mass index standard deviation score at follow-up was 2.74 (2.40, 3.11) units. Compared with AGA, children born SGA were more likely to have hypertensive BP (OR = 1.20 [95% CI 1.12 to 1.29], p < 0.001), elevated HbA1c (1.33 [1.06 to 1.66], p = 0.03), and elevated transaminases (1.21 [1.10 to 1.33], p < 0.001) as well as low HDL (1.19 [1.09 to 1.31], p < 0.001). On the contrary, individuals born LGA had lower odds for hypertensive BP (0.88 [0.83 to 0.94], p < 0.001), elevated HbA1c (0.81 [0.67 to 0.97], p < 0.001), and elevated transaminases (0.88 [0.81 to 0.94], p < 0.001). Preterm birth altered some of the associations between SGA and outcomes, e.g., by increasing the odds for hypertensive BP and by diminishing the odds for elevated transaminases. Potential selection bias due to occasionally missing data could not be excluded.

CONCLUSIONS

Among children and adolescents with overweight/obesity, individuals born SGA are more likely to possess cardiometabolic risk factors compared to their counterparts born AGA. Targeted screening and treatment of obesity-related comorbidities should therefore be considered in this high-risk group of individuals.

Alterations in DNA methylation associate with fatty liver and metabolic abnormalities in a multi-ethnic cohort of pre-teenage children

Non-Alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease in children. Epigenetic alterations, such as through DNA methylation (DNAm), may link adverse childhood exposures and fatty liver and provide non-invasive methods for identifying children at high risk for NAFLD and associated metabolic dysfunction. We investigated the association between differential DNAm and liver fat content (LFC) and liver injury in pre-adolescent children. Leveraging data from the Newborn Epigenetics Study (NEST), we enrolled 90    mother-child dyads and used linear regression to identify CpG sites and differentially methylated regions (DMRs) in peripheral blood associated with LFC and alanine aminotransferase (ALT) levels in 7-12yo children. DNAm was measured using Infinium HumanMethylationEPIC BeadChips (Illumina). LFC and fibrosis were quantified by magnetic resonance imaging proton density fat fraction and elastography. Median LFC was 1.4% (range, 0.3-13.4%) and MRE was 2.5 kPa (range, 1.5-3.6kPa). Three children had LFC ≥ 5%, while six (7.6%) met our definition of NAFLD (LFC ≥ 3.7%). All children with NAFLD were obese and five were Black. LFC was associated with 88 DMRs and 106 CpGs (FDR<5%). The top two CpGs, cg25474373 and cg07264203, mapped to or near RFTN2 and PRICKLE2 genes. These two CpG sites were also significantly associated with a NAFLD diagnosis. As higher LFC associates with an adverse cardiometabolic profile already in childhood, altered DNAm may identify these children early in disease course for targeted intervention. Larger, longitudinal studies are needed to validate these findings and determine mechanistic relevance.

Genetics, epigenetics and transgenerational transmission of obesity in children

Sedentary lifestyle and consumption of high-calorie foods have caused a relentless increase of overweight and obesity prevalence at all ages. Its presently epidemic proportion is disquieting due to the tight relationship of obesity with metabolic syndrome and several other comorbidities which do call for urgent workarounds. The usual ineffectiveness of present therapies and failure of prevention campaigns triggered overtime a number of research studies which have unveiled some relevant aspects of obesity genetic and epigenetic inheritable profiles. These findings are revealing extremely precious mainly to serve as a likely extra arrow to allow the clinician's bow to achieve still hitherto unmet preventive goals. Evidence now exists that maternal obesity/overnutrition during pregnancy and lactation convincingly appears associated with several disorders in the offspring independently of the transmission of a purely genetic predisposition. Even the pre-conception direct exposure of either father or mother gametes to environmental factors can reprogram the epigenetic architecture of cells. Such phenomena lie behind the transfer of the obesity susceptibility to future generations through a mechanism of epigenetic inheritance. Moreover, a growing number of studies suggests that several environmental factors such as maternal malnutrition, hypoxia, and exposure to excess hormones and endocrine disruptors during pregnancy and the early postnatal period may play critical roles in programming childhood adipose tissue and obesity. A deeper understanding of how inherited genetics and epigenetics may generate an obesogenic environment at pediatric age might strengthen our knowledge about pathogenetic mechanisms and improve the clinical management of patients. Therefore, in this narrative review, we attempt to provide a general overview of the contribution of heritable genetic and epigenetic patterns to the obesity susceptibility in children, placing a particular emphasis on the mother-child dyad.

Hepatic cytochrome P450 function is reduced by life-long Western diet consumption in guinea pig independent of birth weight

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is characterised by accumulation of triglycerides and cholesterol within the liver and dysregulation of specific hepatic cytochrome P450 (CYPs) activity. CYPs are involved in the metabolism of endogenous and exogenous chemicals. Hepatic CYP activity is dysregulated in human studies and animal models of a Western diet (WD) or low birth weight (LBW) independently, but the additive effects of LBW and postnatal WD consumption are unknown. As such, the aim of this study was to determine the independent and combined effect of birthweight and postnatal diet on hepatic CYP activity in a guinea pig model.

METHODS

LBW was generated via uterine artery ablation at mid gestation (term = 70 days gestation). Normal birthweight (NBW) and LBW pups were allocated either a control diet (CD) or WD at weaning. After 4 months of dietary intervention, guinea pigs were humanely killed, and liver tissue collected for biochemical and functional hepatic CYP activity analyses.

RESULTS

Independent of birthweight, functional activity of CYP3A was significantly reduced in female and male WD compared to CD animals (female, P < 0.0001; male, P = 0.004). Likewise, CYP1A2 activity was significantly reduced in male WD compared to CD animals (P = 0.020) but this same reduction was not observed in females.

CONCLUSION

Diet, but not birthweight, significantly altered hepatic CYP activity in both sexes, and the effect of diet appeared to be greater in males. These findings may have clinical implications for the management of NAFLD and associated co-morbidities between the sexes.

Liver Proteome Profile of Growth Restricted and Appropriately Grown Newborn Wistar Rats Associated With Maternal Undernutrition

Background

Fetal growth restriction (FGR) has been associated with adverse perinatal outcomes and epigenetic modifications that impact gene expression leading to permanent changes of fetal metabolic pathways and thereby influence development of disease in childhood and adult life. In this study, we investigated the result of maternal food restriction on liver protein expression in Wistar male newborn pups.

Materials & Methods

Ten (n = 10) timed pregnant Wistar rats on their 14th day of gestation were randomly assigned to either control (n = 4) or food restricted group (n = 6). The control group had ad libitum access to food. In the food restricted group, maternal diet was limited in a moderate fashion (50%) from day 15 of pregnancy until delivery. All rats delivered spontaneously on day 21 and newborn pups were immediately weighed. Pups born to normally nourished mothers were considered as controls, while pups born to food restricted mothers were subdivided into two groups, based on their birth weight: growth restricted (FGR) and appropriately grown (non-FGR). Rats were euthanized immediately after birth and liver tissues of 11 randomly selected male offspring (FGR n = 4, non-FGR n = 4, control n = 3) were collected and analyzed using quantitative proteomics.

Results

In total 6,665 proteins were profiled. Of these, 451 and 751 were differentially expressed in FGR and non-FGR vs. control, respectively, whereas 229 proteins were commonly expressed. Bioinformatics analysis of the differentially expressed proteins (DEPs) in FGR vs. control revealed induction of the super-pathway of cholesterol biosynthesis and inhibition of thyroid hormone metabolism, fatty acid beta oxidation and apelin liver signaling pathway. Analysis of DEPs in non-FGR vs. control groups showed inhibition of thyroid hormone metabolism, fatty acid beta oxidation, and apelin liver signaling pathway.

Conclusion

This study demonstrates the impact of prenatal food restriction on the proteomic liver profile of FGR and non-FGR offspring underlying the importance of both prenatal adversities and birth weight on liver-dependent postnatal disease.

Improvement of the hepatic lipid status in intrauterine growth retarded pigs by resveratrol is related to the inhibition of mitochondrial dysfunction, oxidative stress and inflammation

Mitochondrial dysfunction, oxidative stress and inflammation are crucial contributors to liver damage and nonalcoholic fatty liver disease (NAFLD) in adulthood in offspring affected by intrauterine growth retardation (IUGR). Resveratrol (RSV) has been reported to treat and/or prevent hepatic diseases under various pathological conditions. However, the therapeutic and/or preventive effects of RSV on hepatic abnormality in IUGR adults have not been investigated until now. The effects of IUGR and RSV on the hepatic metabolic status, mitochondrial function, redox homeostasis and inflammation in pigs in adulthood were investigated. A total of 36 pairs of IUGR and normal birth weight piglets were orally fed with 80 mg RSV per kg body weight per d or vehicle (0.5% carboxymethylcellulose) for 7-21 d after birth. And then the offspring were fed with a basal diet supplemented with 300 mg RSV per kg feed or a basal diet from weaning to slaughter at 150 d. The plasma and liver samples were collected for subsequent analysis. RSV exerted beneficial effects on hepatic injury and metabolic alterations in IUGR pigs, which may be due to improved mitochondrial function and fatty acid oxidation by intensified mitochondrial biogenesis, enhanced antioxidant levels such as glutathione reductase and total superoxide dismutase activities, increased interleukin 10 gene expression and repolarization of macrophages. RSV alleviated hepatic lipid accumulation in IUGR pigs by improving mitochondrial function, redox status and inflammation, implying that it is a potential candidate for further development as an effective clinical treatment for NAFLD associated with IUGR.

Transcriptomic comparison of liver tissue between Anqing six-end-white pigs and Yorkshire pigs based on RNA sequencing

Chinese indigenous pig and Western commercial pig breeds show different patterns of lipid metabolism, fat deposition, and fatty acid composition; for these reasons, they have become vitally important models of energy metabolism and obesity in humans. To compare the mechanisms underlying lipid metabolism between Yorkshire pigs (lean type) and Anqing six-end-white pigs (obese type), the liver transcriptomes of six castrated boars with a body weight of approximately 100 kg (three Yorkshire and three Anqing) were analyzed by RNA-seq. The total number of reads produced for each liver sample ranged from 47.05 to 62.6 million. Among 362 differentially expressed genes, 142 were up-regulated and 220 were down-regulated in Anqing six-end-white pigs. Based on these data, 79 GO terms were significantly enriched. The top 10 (the 10 with lowest corrected P-value) significantly enriched GO terms were identified, including lipid metabolic process and carboxylic acid metabolic process. Pathway analysis revealed three significantly enriched KEGG pathways including PPAR signaling pathway, steroid hormone biosynthesis, and retinol metabolism. Based on protein–protein interaction networks, multiple genes responsible for lipid metabolism were identified, such as PCK1, PPARA, and CYP7A1, and these were considered promising candidate genes that could affect porcine liver lipid metabolism and fat deposition. Our results provide abundant transcriptomic information that will be useful for animal breeding and biomedical research.

Adrenergic receptor blockade attenuates placental ischemia-induced hypertension

Preeclampsia (PE), a disorder of new-onset maternal hypertension and vascular dysfunction during pregnancy, is thought to be linked to placental ischemia-induced release of prohypertensive factors and reductions of vasoprotective factors in the maternal circulation. Although markers of sympathetic nervous activity are elevated in experimental models of placental ischemia-induced hypertension and women with PE compared with their normal pregnant counterparts, the importance of adrenergic receptor signaling in the development of hypertension in PE is unknown. Therefore, we tested the hypothesis that adrenergic receptor blockade attenuates the development of placental ischemia-induced hypertension in rats. Wistar Hannover rats underwent reduced uterine perfusion pressure (RUPP) or Sham surgeries on gestational day 14. By day 19, mean arterial blood pressure (MAP) was increased in RUPP over Sham rats. Groups of RUPP and Sham pregnant rats received terazosin and propranolol (3 mg/kg per day of each via subcutaneous osmotic minipump) to block α1- and β-adrenergic receptors, respectively, beginning on gestational day 14. Adrenergic blockade significantly attenuated the development of hypertension in the RUPP rats with a slight blood pressure-lowering response in the Sham, normal pregnant rats by day 19. In conclusion, these data implicate that placental ischemia-induced hypertension involves adrenergic receptor signaling to promote increases in blood pressure during PE.