Impact of Maternal Obesity on Liver Disease in the Offspring: A Comprehensive Transcriptomic Analysis and Confirmation of Results in a Murine Model

Perinatal obesity primes the hepatic metabolic stress response in the offspring across life span

Perinatal obesity is associated with an increased risk of metabolic diseases and hepatic dysfunction in offspring. However, the underlying mechanisms of this metabolic programming remain incompletely understood. This study aimed to elucidate the influence of maternal obesity and early life exposure to high-fat diet on offspring liver phenotype, hepatokine profile, and key components of hepatic metabolism. To this end, we employed a murine high-fat diet-induced perinatal obesity model, investigating the offspring in early life and late adulthood. After exposure to perinatal obesity, the offspring showed a significantly increased body weight in early life with no histological signs of steatosis, but a dysregulated hepatokine profile. Proteomic profiling, followed by molecular analyses, revealed a decreased lipogenesis and increased fatty acid oxidation, suggesting a protective mechanism against the development of steatosis. These changes were accompanied by increased markers of lipid peroxidation and DNA damage, indicating increased oxidative stress. Concomitantly, the antioxidative enzymes catalase and superoxide dismutase 2 were significantly reduced and oxidative phosphorylation was impaired, implying an altered oxidative stress response. While changes in oxidative stress level were only detected in early life, the lipid metabolism was altered across life span. This metabolic programming could determine the resilience and susceptibility to chronic liver disease later in life.

Pathophysiological Role of Neutrophil Extracellular Traps in Diet-Induced Obesity and Metabolic Syndrome in Animal Models

The global pandemic of obesity poses a serious health, social, and economic burden. Patients living with obesity are at an increased risk of developing noncommunicable diseases or to die prematurely. Obesity is a state of chronic low-grade inflammation. Neutrophils are first to be recruited to sites of inflammation, where they contribute to host defense via phagocytosis, degranulation, and extrusion of neutrophil extracellular traps (NETs). NETs are web-like DNA structures of nuclear or mitochondrial DNA associated with cytosolic antimicrobial proteins. The primary function of NETosis is preventing the dissemination of pathogens. However, neutrophils may occasionally misidentify host molecules as danger-associated molecular patterns, triggering NET formation. This can lead to further recruitment of neutrophils, resulting in propagation and a vicious cycle of persistent systemic inflammation. This scenario may occur when neutrophils infiltrate expanded obese adipose tissue. Thus, NETosis is implicated in the pathophysiology of autoimmune and metabolic disorders, including obesity. This review explores the role of NETosis in obesity and two obesity-associated conditions-hypertension and liver steatosis. With the rising prevalence of obesity driving research into its pathophysiology, particularly through diet-induced obesity models in rodents, we discuss insights gained from both human and animal studies. Additionally, we highlight the potential offered by rodent models and the opportunities presented by genetically modified mouse strains for advancing our understanding of obesity-related inflammation.

Single-cell RNA transcriptomics in mice reveals embryonic origin of fibrosis due to maternal obesity

BACKGROUND

Over 40% of pregnant women in the USA are obese which negatively affects fetal development and offspring health. Maternal obesity (MO) leads to fibrotic infiltration in multiple tissues and organs of offspring during their adulthood although the origin and mechanisms are unclear.

METHODS

C57BL/6J female mice were fed a control and high-fat diet to mimic MO condition. Embryonic somatic tissues were obtained at E9.5, E11.5, and E13.5 (equivalent to 6 weeks of human pregnancy) from control (CON) and MO mice for single-cell RNA-sequencing (scRNA-seq). To explore the role of AMP-activated protein kinase (AMPK), AMPK was activated by metformin and A769662, and knocked out in embryonic mesenchymal cells (EMC) using AMPKα1 floxed mice.

FINDINGS

Using unsupervised clustering, we identified three major cell populations with fibrogenic capacity. Compared to CON, the population of fibrogenic cells increased dramatically (by ∼125%) due to MO, supporting an embryonic origin of fibrosis in the offspring. MO induced inflammatory response and elevated expression of transforming growth factor β (TGFβ) signalling and fibrogenic genes in embryos. MO inhibited AMPK and its activation by metformin and A769662 inhibited TGFβ signalling and fibrogenesis.

INTERPRETATION

MO profoundly enhances embryonic fibrogenesis, explaining the origin of fibrosis in the offspring of mothers living with obesity. Our data underscore the importance of early intervention, before 5-6 weeks of pregnancy, in improving embryonic development, and AMPK is an amiable target for suppressing excessive fibrogenesis in MO embryos to assist increasing populations of obese mothers having healthy children.

FUNDING

This work was funded by National Institutes of Health Grant R01HD067449.

Both Maternal High-Fat and Post-Weaning High-Carbohydrate Diets Increase Rates of Spontaneous Hepatocellular Carcinoma in Aged-Mouse Offspring

Both maternal obesity and postnatal consumption of obesogenic diets contribute to the development of metabolic dysfunction-associated steatotic liver disease (MASLD) and hepatocellular carcinoma (HCC). However, there is no consensus as to whether diets that are high in fat or carbohydrates/sugars differentially influence the development of HCC. Moreover, the long-term effects of prenatal HF exposure on HCC and whether this is influenced by postnatal diet has not yet been evaluated. C57BL/6 dams were fed either a low-fat, high-carbohydrate control (C) or low-carbohydrate, high-fat (HF) diet. At weaning, male and female offspring were fed the C or HF diet, generating four diet groups: C/C, C/HF, HF/C and HF/HF. Tissues were collected at 16 months of age and livers were assessed for MASLD and HCC. Glucose regulation and pancreatic morphology were also evaluated. Liver tissues were assessed for markers of glycolysis and fatty acid metabolism and validated using a human HCC bioinformatic database. Both C/HF and HF/HF mice developed obesity, hyperinsulinemia and a greater degree of MASLD than C/C and HF/C offspring. However, despite significant liver and pancreas pathology, C/HF mice had the lowest incidence of HCC while tumour burden was highest in HF/C male offspring. The molecular profile of HCC mouse samples suggested an upregulation of the pentose phosphate pathway and a downregulation of fatty acid synthesis and oxidation, which was largely validated in the human dataset. Both pre-weaning HF diet exposure and post-weaning consumption of a high-carbohydrate diet increased the risk of developing spontaneous HCC in aged mice. However, the influence of pre-weaning HF feeding on HCC development appeared to be stronger in the context of post-weaning obesity. As rates of maternal obesity continue to rise, this has implications for the future incidence of HCC and possible dietary manipulation of offspring carbohydrate intake to counteract this risk.

Maternal obesity increases the risk of hepatocellular carcinoma through the transmission of an altered gut microbiome

Background & Aims

Emerging evidence suggests that maternal obesity negatively impacts the health of offspring. Additionally, obesity is a risk factor for hepatocellular carcinoma (HCC). Our study aims to investigate the impact of maternal obesity on the risk for HCC development in offspring and elucidate the underlying transmission mechanisms.

Methods

Female mice were fed either a high-fat diet (HFD) or a normal diet (ND). All offspring received a ND after weaning. We studied liver histology and tumor load in a N-diethylnitrosamine (DEN)-induced HCC mouse model.

Results

Maternal obesity induced a distinguishable shift in gut microbial composition. At 40 weeks, female offspring of HFD-fed mothers (HFD offspring) were more likely to develop steatosis (9.43% vs. 3.09%, p = 0.0023) and fibrosis (3.75% vs. 2.70%, p = 0.039), as well as exhibiting an increased number of inflammatory infiltrates (4.8 vs. 1.0, p = 0.018) and higher expression of genes involved in fibrosis and inflammation, compared to offspring of ND-fed mothers (ND offspring). A higher proportion of HFD offspring developed liver tumors after DEN induction (79.8% vs. 37.5%, p = 0.0084) with a higher mean tumor volume (234 vs. 3 μm3, p = 0.0041). HFD offspring had a significantly less diverse microbiota than ND offspring (Shannon index 2.56 vs. 2.92, p = 0.0089), which was rescued through co-housing. In the principal component analysis, the microbiota profile of co-housed animals clustered together, regardless of maternal diet. Co-housing of HFD offspring with ND offspring normalized their tumor load.

Conclusions

Maternal obesity increases female offspring's susceptibility to HCC. The transmission of an altered gut microbiome plays an important role in this predisposition.

Impact and implications

The worldwide incidence of obesity is constantly rising, with more and more children born to obese mothers. In this study, we investigate the impact of maternal diet on gut microbiome composition and its role in liver cancer development in offspring. We found that mice born to mothers with a high-fat diet inherited a less diverse gut microbiome, presented chronic liver injury and an increased risk of developing liver cancer. Co-housing offspring from normal diet- and high-fat diet-fed mothers restored the gut microbiome and, remarkably, normalized the risk of developing liver cancer. The implementation of microbial screening and restoration of microbial diversity holds promise in helping to identify and treat individuals at risk to prevent harm for future generations.

Maternal Weight Management to Prevent the Developmental Programming of MAFLD in Offspring of Obese Mothers

The global surge of obesity amongst women of reproductive age has raised concerns surrounding the health consequences for their offspring as there is a formidable link between an obesogenic maternal environment and the developmental programming of metabolic dysfunction in the offspring. Specifically, the offspring of mothers with obesity have a three-fold higher risk of developing metabolic-associated fatty liver disease (MAFLD) compared to the offspring of healthy-weight mothers. Given the burgeoning burden of obesity and its comorbidities, it is essential to focus research efforts on methods to alleviate the intergenerational onset of obesity and MAFLD. This review summarizes the current research surrounding the developmental programming of MAFLD in the offspring of mothers with obesity and examines the potential for weight interventions to prevent such metabolic dysfunction in the offspring. It focuses on the benefits of pre-pregnancy interventional strategies, including dietary and exercise intervention, to ameliorate adverse liver health outcomes in the offspring. The utility and translation of these interventions for humans may be difficult for prospective mothers with obesity, thus the use of pre-pregnancy therapeutic weight loss aids, such as glucagon-like peptide-1 receptor agonists, is also discussed.

Severe gestational diabetes mellitus in lean dams is associated with low IL-1α levels and affects the growth of the juvenile mouse offspring

We investigated how maternal gestational diabetes (GDM) impacts the metabolic status of offspring. GDM was induced in CD1 mice consuming a fast-food diet (FFD) by repeated low-dose streptozotocin injections before mating. Offspring of normoglycemic standard chow or the FFD consuming dams served as controls. In 4-week-old offspring weaned to standard chow, plasma concentrations of extracellular DNA, inflammatory markers, and parameters of the cardiometabolic status (glycemia, liver lipid content; body, organ, and fat weight) were determined. Two-factor analysis of variance indicated that the male offspring of GDM dams manifest postnatal growth retardation and lower relative kidney weight. Regardless of sex, GDM offspring manifest the lowest IL-1α levels, and other inflammatory markers showed mild and inconsistent alterations. Offspring of dams consuming the FFD displayed higher liver triacylglycerols content. The three groups of offspring showed no significant differences in glycemia and extracellular DNA. Partial least squares-discriminant analysis indicated that male GDM offspring present lower kidney, body, and brown adipose tissue weights; lower IL-1α levels, and higher concentrations of GM-CSF and IL-10 compared with their FFD counterparts. The model failed to select discriminative variables in females. In conclusion, in mice, maternal GDM in the absence of obesity adversely affects the early growth of juvenile male offspring.