Development of a novel guinea pig model producing transgenerational endothelial transcriptional changes driven by maternal food restriction and a second metabolic insult of high-fat diet.
Developmental programming of chronic adverse cardiovascular health outcomes has been studied both using numerous human populations and an array of animal models. However, the mechanisms that produce transgenerational effects have been difficult to study due to a lack of developmentally relevant models. As such, how increased disease risk is carried to the second generation has been poorly studied. We hypothesized that the endothelium which mediates many acute and chronic vascular inflammatory responses is a key player in these effects, and epidemiological studies implicate transgenerational nutritional effects on endothelial health. To study the mutigenerational effects of maternal undernutrition on offspring endothelial health, we developed a model of transgenerational nutritional stress in guinea pigs, a translationally relevant precocial species with a relatively short lifespan. First- and second- generation offspring were subjected to a high fat diet in adolescence to exacerbate negative cardiovascular health. To assess transcriptional changes, we performed bulk RNA-sequencing in carotid artery endothelial cells, with groups stratified as prenatal control or food restricted, and postnatal control or high fat diet. We detected statistically significant gene alterations for each dietary permutation, some of which were unique to treatments and other transcriptional signatures shared by multiple or all conditions. These findings highlight a core group of genes altered by high fat diet that is shared by all cohorts and a divergence of transgenerational effects between the prenatal ad libitum and dietary restriction groups. This study establishes the groundwork for this model to be used to better understand the interplay of prenatal stress and genetic reprogramming. Overall design: Two adult male (550-600g) and 8 nulliparous female (400-450g) Hartley Guinea Pigs were purchased from Charles River Laboratories and housed in individual cages. All animals were weighed three times per week. Purchased animals were fed a standard, control chow (LabDiets 5025, 13% energy from fat, 27% from protein, 60% from carbohydrate) ad libitum for 3 weeks to acclimate and weight and food intake were recorded daily. Following this acclimatization period, half of the female guinea pigs received 70% of the average (per kg body weight) daily ad libitum diet (PR; Prenatal Food Restriction) for 3 weeks; the remainder of the females (PC; Prenatal Ad libitum Control), and all males received 100% of the average (per kg body weight) daily ad libitum diet. Male and female guinea pigs were mated overnight, and mating confirmed by the presence of a vaginal plug. Control guinea pigs remained on their designated diet for the duration of gestation (~70 days) and throughout lactation (~28d days). Food-restricted dams remained on 70% of ad libitum diet until 34dGA (days gestational age, ~mid gestation), after which they were placed on 90% of ad libitum diet until the end of lactation; this increase in feed is to prevent weight loss during the latter half of pregnancy.Offspring were born spontaneously and litter size was culled to 3 pups per dam. Offspring were housed with their mother until weaning at 28 days. Pup selection for culling was pseudo-random in order to maintain equal numbers of male and female offspring in each study group, and to maintain equal mean pup weights between culled and unculled groups. After weaning, all offspring were fed a control diet until at least 8 weeks of age. A subset of female F1 offspring were used as breeders to produce F2 offspring, and remained on an ad libitum control chow diet for the remainder of the study, including during pregnancy. F1 breeders were mated with newly-purchased unrelated adult male Hartley Guinea Pigs purchased from Charles River Laboratories, as described above. At 8 weeks of age, half of remaining non-breeding F1 offspring were fed ad libitum control chow (PC-C or PR-C) while other half were placed on an ad libitum high-fat chow (PC-H or PR-H) for 12 weeks; food intake was monitored daily, and animals were weighed 3 times per week. The high fat chow was based on the standard lab chow LabDiet 5025, supplemented with 0.25% cholesterol, 15% fat from pork fat, and 2.5% fructose (38% energy from fat, 20% from protein, 42% from carbohydrate). Offspring diets were pseudo-randomly assigned to avoid siblings receiving the same treatment. Offspring were born spontaneously and treated as described above for the non-breeding F1 offspring. At 8 weeks of age, offspring received either ad libitum control chow (PC-C-C or PR-C-C) or ad libitum high-fat chow (PC-C-H or PR-C-H). At 20 weeks of age, 3 animals each from PC-C, PC-H, PR-C, PR-H, PC-C-C, PC-C-H, PR-C-C, PR-C-H were euthanized with intravenous overdose of commercial barbituate (Somnasol, 390mg/ml pentobarbital sodium). A carotid artery was rapidly cannulated in situ. The vessel was flushed with 1X PBS (Gibco) to remove blood, followed by 100uL of TRIzol Reagent (Invitrogen) to collect endothelial cell contents. RNA was isolated using RNeasy Micro kit (Qiagen) and quality was assessed using Agilent 2100 Bioanalyzer with RNA 6000 Pico chip by the OHSU Gene Profiling Shared Resource. All samples had an RNA Integrity Number (RIN) score of above 5.0. Samples were stored at -80C until sequencing. Short-read sequencing assays were performed by the OHSU Massively Parallel Sequencing Shared Resource. Raw data was checked for quality using FastQC, trimmed using Trimmomatic, aligned using STAR, and analyzed for differential gene expression using DESeq2 in R.