The intestinal microbiome is a unique ecosystem and an essential mediator of metabolism and obesity in mammals. However, studies investigating the impact of the diet on the establishment of the gut microbiome early in life are generally lacking, and most notably so in primate models. Here we report that a high-fat maternal or postnatal diet, but not obesity per se, structures the offspring’s intestinal microbiome in Macaca fuscata (Japanese macaque). The resultant microbial dysbiosis is only partially corrected by a low-fat, control diet after weaning. Unexpectedly, early exposure to a high-fat diet diminished the abundance of non-pathogenic Campylobacter in the juvenile gut, suggesting a potential role for dietary fat in shaping commensal microbial communities in primates. Our data challenge the concept of an obesity-causing gut microbiome, and rather provide evidence for a contribution of the maternal diet in establishing the microbiota, which in turn affects intestinal maintenance of metabolic health.

The origins of nonalcoholic fatty liver disease (NAFLD) may lie in early intrauterine exposures. Here we examined the maternal response to chronic maternal high-fat (HF) diet and the impact of postweaning healthy diet on mechanisms for NAFLD development in juvenile nonhuman primate (NHP) offspring at 1 year of age. Pregnant females on HF diet were segregated as insulin resistant (IR; HF+IR) or insulin sensitive (IS; HF+IS) compared with control (CON)-fed mothers. HF+IR mothers have increased body mass, higher triglycerides, and increased placental cytokines. At weaning, offspring were placed on a CON or HF diet. Only offspring from HF+IR mothers had increased liver triglycerides and upregulated pathways for hepatic de novo lipid synthesis and inflammation that was irreversible upon switching to a healthy diet. These juvenile livers also showed a combination of classical and alternatively activated hepatic macrophages and natural killer T cells, in the absence of obesity or insulin resistance. Our findings suggest that maternal insulin resistance, including elevated triglycerides, insulin, and weight gain, initiates dysregulation of the juvenile hepatic immune system and development of de novo lipogenic pathways that persist in vitro and may be an irreversible “first hit” in the pathogenesis of NAFLD in NHP.

Background: Role of CCAAT/enhancer-binding protein ␤ in obesity-induced inflammation remains unexplored. Results: Bone marrow-chimeric mice studies show that C/EBP␤ deletion regulates dietary-induced systemic inflammation and insulin resistance. Conclusion: C/EBP␤ expression in response to palmitate or high-fat diet controls transcriptional regulatory networks in macrophages and adipocytes critical for inflammation, lipid metabolism, and insulin resistance. Significance: Attenuating C/EBP␤ is an attractive target for ameliorating nutrition-induced inflammation.