Effects of a high-fat diet during pregnancy and lactation are modulated by E. coli in rat offspring

Metabolic and Microbial Changes Associated With Diet and Obesity During Pregnancy: What Can We Learn From Animal Studies?

The intestinal microbiota changes throughout pregnancy and influences maternal metabolic adaptations to support fetal growth. Obesity induces alterations to the microbiota that include decreased microbial diversity and shifts in microbial composition, though specific species changes are inconsistent between published studies. In animal models, probiotics and exercise moderate maternal weight gain and partially correct the maternal microbiota. Supplemental Escherichia coli, however, exacerbate maternal obesity during the perinatal period, lending weight to the theory that inflammation-induced gut epithelial barrier leak influences metabolic dysregulation. Although birth weight is not always altered when offspring are exposed to an obesogenic diet during gestation, insulin resistance and lipid metabolism are impacted through adulthood in association with this exposure and can lead to increased body weight in adulthood. Postnatal offspring growth is accelerated in response to maternal overnutrition during lactation. Offspring microbiota, metabolism, and behavior are altered in response to early exposure to high fat and high sucrose diets. Consequences to this exposure include impaired glucose and insulin homeostasis, fatty liver, and neurobehavioral deficits that can be ameliorated by improving the microbial environment. In this mini review, we provide an overview of the use of translational animal models to understand the mechanisms associated with changes to the gastrointestinal microbiota due to maternal obesity and the microbial impact on the metabolic changes of pregnancy.

Maternal High-Fat Diet Exposure During Gestation and Lactation Affects Intestinal Development in Suckling Rats

Maternal health and diet influence metabolic status and play a crucial role in the development of metabolic function in offspring and their susceptibility to metabolic diseases in adulthood. The pathogenesis of various metabolic disorders is often associated with impairment in intestinal structure and function. Thus, the aim of the current study was to determine the effects of maternal exposure to a high fat diet (HFD), during gestation and lactation, on small intestinal growth and maturation in rat pups at 21 days old. Female, Wistar Han rats were fed either a breeding diet (BD) or high fat diet (HFD), from mating until the 21st day of lactation. Maternal HFD exposure increased body weight, BMI and adiposity. Compared to the maternal BD, HFD exposure influenced small intestine histomorphometry in a segment-dependent manner, changed the activity of brush border enzymes and had an impact on intestinal contractility via changes in cholinergic signaling. Moreover, offspring from the maternal HFD group had upregulated mRNA expression of cyclooxygenase (COX)-2, which plays a role in the inflammatory process. These results suggest that maternal HFD exposure, during gestation and lactation, programs the intestinal development of the offspring in a direction toward obesity as observed changes are also commonly reported in models of diet-induced obesity. The results also highlight the importance of maternal diet preferences in the process of developmental programming of metabolic diseases.

Axel AM, Safayi S, Elbrønd VS, Nielsen MO. Prenatal over- and undernutrition differentially program small intestinal growth, angiogenesis, absorptive capacity, and endocrine function in sheep

The aim was to test the hypothesis that prenatal under- and overnutrition in late gestation can program small intestinal (SI) growth, angiogenesis, and endocrine function to predispose for a hyperabsorptive state, thereby increasing the susceptibility to the adverse effects of an early postnatal obesogenic diet. Twin-pregnant ewes were exposed to adequate (NORM), LOW (50% of NORM), or HIGH (150% energy and 110% protein of NORM) diets through the last trimester (term ~147 days). From 3 days to 6 months of age, their lambs were fed either a moderate (CONV) or a high-carbohydrate high-fat (HCHF) diet. At 6 months of age, responses in plasma metabolites and insulin to refeeding after fasting were determined and then different segments of the SI were sampled at autopsy. Prenatal overnutrition impacts were most abundant in the duodenum where HIGH had increased villus amplification factor and lowered villi thickness with increased IRS-1 and reduced GH-R expressions. In jejunum, HIGH lambs had an increased expression of Lactate gene and amplified when exposed to HCHF postnatally. Specifically, in LOW, sensitivity to HCHF was affected in ileum. Thus, the mismatching LOW-HCHF nutrition increased expressions of angiogenic genes (VEGF, VEGF-R1, ANGPT1, RTK) and increased mucosa layer (tunica mucosa) thickness but reduced muscle layer (Tunica muscularis) thickness. The SI is a target of prenatal nutritional programming, where late gestation overnutrition increased and shifted digestive capacity for carbohydrates toward the jejunum, whereas late gestation undernutrition predisposed for ileal angiogenesis and carbohydrate and fat hyperabsorptive capacity upon subsequent exposure to postnatal obesogenic diet.

The Development of the Human Microbiome: Why Moms Matter

The human body is cohabitated with trillions of commensal bacteria that are essential for our health. However, certain bacteria can also cause diseases in the human host. Before the microbiome can be attributed to disease risk and pathogenesis, normal acquisition and development of the microbiome must be understood. Here, we explore the evidence surrounding in utero microbial exposures and the significant of this exposure in the proper development of the fetal and neonatal microbiome. We further explore the development of the fetal and neonatal microbiome and its relationship to preterm birth, feeding practices, and mode of delivery, and maternal diet.

Leaf mineral content govern microbial community structure in the phyllosphere of spinach (Spinacia oleracea) and rocket (Diplotaxis tenuifolia)

The plant microbiome is an important factor for plant health and productivity. While the impact of nitrogen (N) availability for plant growth and development is well established, its influence on the microbial phyllosphere community structure is unknown. We hypothesize that nitrogen impacts the growth and abundance of several microorganisms on the leaf surface. The bacterial and fungal communities of baby leaf spinach (Spinacia oleracea), and rocket (Diplotaxis tenuifolia) were investigated in a field trial for two years in a commercial setting. Nitrogen fertilizer was tested in four doses (basic nitrogen, basic + suboptimal, basic + commercial, basic + excess) with six replicates in each. Culture-independent (Illumina sequencing) and culture-dependent (viable count and identification of bacterial isolates) community studies were combined with monitoring of plant physiology and site weather conditions. This study found that alpha diversity of bacterial communities decreased in response to increasing nitrogen fertilizer dose, whereas viable counts showed no differences. Correspondingly, fungal communities of the spinach phyllosphere showed a decreasing pattern, whereas the decreasing diversity of fungal communities of rocket was not significant. Plant species and effects of annual variations on microbiome structure were observed for bacterial and fungal communities on both spinach and rocket. This study provides novel insights on the impact of nitrogen fertilizer regime on a nutrient scarce habitat, the phyllosphere.

Abundance of Enterobacteriaceae in the colon mucosa in diverticular disease

AIM

To compare gut bacterial diversity and amount of Enterobacteriaceae in colonic mucosa between patients with and without diverticular disease (DD).

METHODS

Patients in a stable clinical condition with planned elective colonoscopy were included. Blood samples and colon mucosa biopsies were collected at the colonoscopy. Study questionnaires including questions about gastrointestinal symptoms were completed by the patients and physicians. DNA from mucosa samples was isolated and the amount of Enterobacteriaceae was estimated using PCR assay. Terminal restriction fragment length polymorphism was applied to assess microbial diversity. Diversity was estimated by calculations of richness (number of terminal restriction fragments) and Shannon-Wiener and Simpson’s indices.

RESULTS

A total of 51 patients were included, 16 patients with DD [68 (62-76) years] and 35 controls [62 (40-74) years] without any diverticula. Patients with DD had significantly higher levels of Enterobacteriaceae than those without DD (P = 0.043), and there was an inverse relationship between the amount of Enterobacteriaceae and the Simpson’s index (rs = -0.361, P = 0.033) and the Shannon-Wiener index (rs = -0.299, P = 0.081). The Simpson’s index (P = 0.383), Shannon-Wiener index (P = 0.401) or number of restrictions fragments (P = 0.776) did not differ between DD and controls. The majority of patients experienced gastrointestinal symptoms, and 22 patients (43.1%) fulfilled the criteria for irritable bowel syndrome, with no difference between the groups (P = 0.212). Demography, socioeconomic status, lifestyle habits, inflammatory biomarkers, or symptoms were not related to the amount of Enterobacteriaceae or bacterial diversity.

CONCLUSION

Patients with DD had higher amount of Enterobacteriaceae in the colon mucosa compared to patients without diverticula.

Impact of maternal nutrition in pregnancy and lactation on offspring gut microbial composition and function

Evidence supporting the Developmental Origins of Health and Disease Hypothesis indicates that maternal nutrition in pregnancy has a significant impact on offspring disease risk later in life, likely by modulating developmental processes in utero. Gut microbiota have recently been explored as a potential mediating factor, as dietary components strongly influence microbiota abundance, function and its impact on host physiology. A growing body of evidence has additionally indicated that the intrauterine environment is not sterile as once presumed, indicating that maternal-fetal transmission of microbiota may occur during pregnancy. In this article, we will review the body of literature that supports this emerging hypothesis, as well as highlight the work in relevant animal models demonstrating associations with maternal gestational nutrition and the offspring gut microbiome that may influence offspring physiology and susceptibility to disease.

The early infant gut microbiome varies in association with a maternal high-fat diet

BACKGROUND

Emerging evidence suggests that the in utero environment is not sterile as once presumed. Work in the mouse demonstrated transmission of commensal bacteria from mother to fetus during gestation, though it is unclear what modulates this process. We have previously shown in the nonhuman primate that, independent of obesity, a maternal high-fat diet during gestation and lactation persistently shapes the juvenile gut microbiome. We therefore sought to interrogate in a population-based human longitudinal cohort whether a maternal high-fat diet similarly alters the neonatal and infant gut microbiome in early life.

METHODS

A representative cohort was prospectively enrolled either in the early third trimester or intrapartum (n = 163), with a subset consented to longitudinal sampling through the postpartum interval (n = 81). Multiple body site samples, including stool and meconium, were collected from neonates at delivery and by 6 weeks of age. A rapid dietary questionnaire was administered to estimate intake of fat, added sugars, and fiber over the past month (National Health and Examination Survey). DNA was extracted from each infant meconium/stool sample (MoBio) and subjected to 16S rRNA gene sequencing and analysis.

RESULTS

On average, the maternal dietary intake of fat ranged from 14.0 to 55.2 %, with an average intake of 33.1 % (σ = 6.1 %). Mothers whose diets significantly differed from the mean (±1 standard deviation) were separated into two distinct groups, a control group (n = 13, μ = 24.4 %) and a high-fat group (n = 13, μ = 43.1 %). Principal coordinate analysis revealed that the microbiome of the neonatal stool at birth (meconium) clustered differently by virtue of maternal gestational diet (PERMANOVA p = 0.001). LEfSe feature selection identified several taxa that discriminated the groups, with a notable relative depletion of Bacteroides in the neonates exposed to a maternal high-fat gestational diet (Student's t-test, p < 0.05) that persisted to 6 weeks of age.

CONCLUSIONS

Similar to the primate, independent of maternal body mass index, a maternal high-fat diet is associated with distinct changes in the neonatal gut microbiome at birth which persist through 4-6 weeks of age. Our findings underscore the importance of counseling pregnant mothers on macronutrient consumption during pregnancy and lactation.

Stress and the commensal microbiota: importance in parturition and infant neurodevelopment

The body is colonized by an enormous array of microbes that are collectively called the microbiota. During quiescent periods, microbial communities within the gut are relatively resistant to change. However, several factors that disrupt homeostasis can also significantly change gut microbial community structure. One factor that has been shown to change the composition of the gut microbiota is exposure to psychological stressors. Studies demonstrate that the commensal microbiota are involved in stressor-induced immunomodulation, but other biological effects are not yet known. This review discusses emerging evidence that the microbiota can impact the brain and behavior and indicates that stressor-induced alterations in the composition of gut microbial communities contribute to stressor-induced behavioral changes. This review will also discuss the evidence that such effects are most evident early in life, where both stress and the microbiota have been linked to birth outcomes, such as prematurity, and neurodevelopment. When considered together, a paradigm emerges in which stressor-induced alterations in commensal microbial populations significantly impact parturition and infant neurodevelopment.

Excess body weight during pregnancy and offspring obesity: potential mechanisms

The rates of child and adult obesity have increased in most developed countries over the past several decades. The health consequences of obesity affect both physical and mental health, and the excess body weight can be linked to an elevated risk for developing type 2 diabetes, cardiovascular problems, and depression. Among the factors that can influence the development of obesity are higher infant weights and increased weight gain, which are associated with higher risk for excess body weight later in life. In turn, mother's excess body weight during and after pregnancy can be linked to the risk for offspring overweight and obesity through dietary habits, mode of delivery and feeding, breast milk composition, and through the influence on infant gut microbiota. This review considers current knowledge of these potential mechanisms that threaten to create an intergenerational cycle of obesity.

Long term effects of pre- and early postnatal nutrition and environment on the gut

The Developmental Origins of Health and Disease hypothesis formulated in the early 1990 s has stimulated research on long-term effects of early nutrition and environment over the last decades. Long-term is understood in this review as physiologically relevant periods such as after weaning, around sexual maturity, and in adulthood, as opposed to early developmental periods. The small and large intestines as targets for the study of long-term effects have received little attention until recent years and the stomach has been considered very rarely. Data have accumulated for laboratory animal models but they are still scarce in the swine species. Following the epidemics of metabolic diseases and obesity in western countries, experimental evidence has been published showing that nutritional factors, including energy, fat and fatty acids, protein, and micronutrients impact various facets of gut function. These include alterations in intestinal digestive, absorptive, secretory, barrier, and defense systems, often in a way potentially detrimental to the host. Environmental factors with long-term influence include stress (e.g., maternal deprivation, neonatal gut irritation), chemical pollutants (e.g., bisphenol A), and gut microbiota disturbances (e.g., by antibiotics). Examples of such long-term effects on the gut are provided in both laboratory animals and pigs together with underlying physiological mechanisms whenever available. Experimental evidence for the involvement of underlying epigenetic modifications (e.g., genomic DNA methylation) in long-term studies has just started to emerge with regard to the gastrointestinal tract. Also, interactions between the microbiota and the host are being considered pivotal in the early programming of gut functions. Finally, suggestions for future research are provided in order to better understand and then control early programming as an attempt to optimize vital functions of the gastrointestinal tract throughout adult life.

Maternal exposure to bisphenol A and genistein has minimal effect on A(vy)/a offspring coat color but favors birth of agouti over nonagouti mice

Reports that maternal diet influences coat color in mouse offspring carrying the agouti A(vy) allele have received considerable attention because the range, from pseudoagouti (brown) to yellow, predicts adult health outcomes, especially disposition toward obesity and diabetes, in yellower mice. Bisphenol A (BPA), an endocrine-disrupting compound with estrogenic properties, fed to a/a dams harboring A(vy)/a conceptuses has been reported to induce a significant shift toward yellower mice, whereas consumption of either genistein (G) alone or in combination with BPA led to greater numbers of healthy, brown offspring. Groups of C57/B6 a/a females, which are nonagouti, were fed either a phytoestrogen-free control diet or one of six experimental diets: diets 1-3 contained BPA (50 mg, 5 mg, and 50 μg BPA/kg food, respectively); diet 4 contained G (250 mg/kg food); diet 5 contained G plus BPA (250 and 50 mg/kg food, respectively); and diet 6 contained 0.1 μg of ethinyl estradiol (EE)/kg food. Mice were bred to A(vy)/a males over multiple parities. In all, 2,824 pups from 426 litters were born. None of the diets provided any significant differences in relative numbers of brown, yellow, or intermediate coat color A(vy)/a offspring. However, BPA plus G (P < 0.0001) and EE diets (P = 0.005), but not the four others, decreased the percentage of black (a/a) to A(vy)/a offspring from the expected Mendelian ratio of 1:1. Data suggest that A(vy)/a conceptuses, which may possess a so-called "thrifty genotype," are at a competitive advantage over a/a conceptuses in certain uterine environments.