The development and ecology of the Japanese macaque gut microbiome from weaning to early adolescence in association with diet

Maternal Western Diet Programmes Bile Acid Dysregulation and Hepatic Fibrosis in Fetal and Juvenile Macaques

BACKGROUND AND AIMS

Maternal obesity increases the risk of the paediatric form of metabolic dysfunction-associated steatotic liver disease (MASLD), affecting up to 30% of youth, but the developmental origins remain poorly understood.

METHODS

Using a Japanese macaque model, we investigated the impact of maternal Western-style diet (mWSD) or chow diet followed by postweaning WSD (pwWSD) or chow diet focusing on bile acid (BA) homeostasis and hepatic fibrosis in livers from third-trimester fetuses and 3-year-old juvenile offspring.

RESULTS

Juveniles exposed to mWSD had increased hepatic collagen I/III content and stellate cell activation in portal regions. mWSD increased transcriptional signatures of FXR activation, while pwWSD impaired FXR pathway genes and increased liver BA content. Both mWSD and pwWSD increased serum BA concentrations. Notably, mWSD-exposed juvenile offspring had increased periportal CK19 expression and cholangiocyte gene expression supporting proliferation compared with maternal chow-exposed offspring. Fetuses exposed to mWSD had increased CK19 expression and hepatic BAs which correlated positively with periportal collagen deposition and negatively with markers of fetal oxygenation. In juvenile offspring, increased serum BAs correlated positively with hepatic oxidative stress and portal fibrosis without elevated liver enzymes.

CONCLUSIONS

mWSD is associated with hallmarks of paediatric MASLD including portal bile ductular reaction, portal fibrosis and dysregulated BA homeostasis. These conditions begin in utero and persist in juvenile offspring regardless of their postweaning diet. These findings implicate changes in BA metabolism that may drive developmental programming of MASLD in juvenile offspring beginning in utero.

Initiation of metformin in early pregnancy results in fetal bioaccumulation, growth restriction, and renal dysmorphology in a primate model

BACKGROUND

In recent years, pragmatic metformin use in pregnancy has stretched to include prediabetes mellitus, type 2 diabetes mellitus, gestational diabetes mellitus, and (most recently) preeclampsia. However, with its expanded use, concerns of unintended harm have been raised.

OBJECTIVE

This study developed an experimental primate model and applied ultrahigh performance liquid chromatography coupled to triple-quadrupole mass spectrometry for direct quantitation of maternal and fetal tissue metformin levels with detailed fetal biometry and histopathology.

STUDY DESIGN

Within 30 days of confirmed conception (defined as early pregnancy), 13 time-bred (timed-mated breeding) Rhesus dams with pregnancies designated for fetal necropsy were initiated on twice-daily human dose-equivalent 10 mg/kg metformin or vehicle control. Pregnant dams were maintained as pairs and fed either a control chow or 36% fat Western-style diet. Metformin or placebo vehicle control was delivered in various treats while the animals were separated via a slide. A cesarean delivery was performed at gestational day 145, and amniotic fluid and blood were collected, and the fetus and placenta were delivered. The fetus was immediately necropsied by trained primate center personnel. All fetal organs were dissected, measured, sectioned, and processed per clinical standards. Fluid and tissue metformin levels were assayed using validated ultrahigh performance liquid chromatography coupled to triple-quadrupole mass spectrometry in selected reaction monitoring against standard curves.

RESULTS

Among 13 pregnancies at gestational day 145 with fetal necropsy, 1 dam and its fetal tissues had detectable metformin levels despite being allocated to the vehicle control group (>1 μmol metformin/kg maternal weight or fetal or placental tissue), whereas a second fetus allocated to the vehicle control group had severe fetal growth restriction (birthweight of 248.32 g [<1%]) and was suspected of having a fetal congenital condition. After excluding these 2 fetal pregnancies from further analyses, 11 fetuses from dams initiated on either vehicle control (n=4: 3 female and 1 male fetuses) or 10 mg/kg metformin (n=7: 5 female and 2 male fetuses) were available for analyses. Among dams initiated on metformin at gestational day 30 (regardless of maternal diet), significant bioaccumulation within the fetal kidney (0.78-6.06 μmol/kg; mean of 2.48 μmol/kg), liver (0.16-0.73 μmol/kg; mean of 0.38 μmol/kg), fetal gut (0.28-1.22 μmol/kg; mean of 0.70 μmol/kg), amniotic fluid (0.43-3.33 μmol/L; mean of 1.88 μmol/L), placenta (0.16-1.00 μmol/kg; mean of 0.50 μmol/kg), fetal serum (0.00-0.66 μmol/L; mean of 0.23 μmol/L), and fetal urine (4.10-174.10 μmol/L; mean of 38.5 μmol/L) was observed, with fetal levels near biomolar equivalent to maternal levels (maternal serum: 0.18-0.86 μmol/L [mean of 0.46 μmol/L]; maternal urine: 42.60-254.00 μmol/L [mean of 149.30 μmol/L]). Western-style diet feeding neither accelerated nor reduced metformin bioaccumulations in maternal or fetal serum, urine, amniotic fluid, placenta, or fetal tissues. In these 11 animals, fetal bioaccumulation of metformin was associated with less fetal skeletal muscle (57% lower cross-sectional area of gastrocnemius) and decreased liver, heart, and retroperitoneal fat masses (P<.05), collectively driving lower delivery weight (P<.0001) without changing the crown-rump length. Sagittal sections of fetal kidneys demonstrated delayed maturation, with disorganized glomerular generations and increased cortical thickness. This renal dysmorphology was not accompanied by structural or functional changes indicative of renal insufficiency.

CONCLUSION

Our study demonstrates fetal bioaccumulation of metformin with associated fetal growth restriction and renal dysmorphology after maternal initiation of the drug within 30 days of conception in primates. Given these results and the prevalence of metformin use during pregnancy, additional investigation of any potential immediate and enduring effects of prenatal metformin use is warranted.

Gut microbiome in two high-altitude bird populations showed heterogeneity in sex and life stage

Gut microbiotas have important impacts on host health, reproductive success, and survival. While extensive research in mammals has identified the exogenous (e.g. environment) and endogenous (e.g. phylogeny, sex, and age) factors that shape the gut microbiota composition and functionality, yet avian systems remain comparatively less understood. Shorebirds, characterized by a well-resolved phylogeny and diverse life-history traits, present an ideal model for dissecting the factors modulating gut microbiota dynamics. Here, we provide an insight into the composition of gut microbiota in two high-altitude (ca. 3200 m above sea level) breeding populations of Kentish plover (Charadrius alexandrinus) and Tibetan sand plover (Charadrius altrifrons) in the Qinghai-Tibetan Plateau, China. By analysing faecal bacterial communities using 16S rRNA sequencing technology, we find a convergence in gut microbial communities between the two species, dominated by Firmicutes, Proteobacteria, and Bacteroidetes. This suggests that the shared breeding environment potentially acts as a significant determinant shaping their gut microbiota. We also show sex- and age-specific patterns of gut microbiota: female adults maintain a higher diversity than males, and juveniles are enriched in Rhizobiaceae and Exiguobacterium due to their vegetative food resource. Our study not only provides a comprehensive descriptive information for future investigations on the diversity, functionality, and determinants of avian microbiomes, but also underscores the importance of microbial communities in broader ecological contexts.

Maternal Western-style diet programs skeletal muscle gene expression in lean adolescent Japanese macaque offspring

Early-life exposure to maternal obesity or a maternal calorically dense Western-style diet (WSD) is strongly associated with a greater risk of metabolic diseases in offspring, most notably insulin resistance and metabolic dysfunction-associated steatotic liver disease (MASLD). Prior studies in our well-characterized Japanese macaque model demonstrated that offspring of dams fed a WSD, even when weaned onto a control (CTR) diet, had reductions in skeletal muscle mitochondrial metabolism and increased skeletal muscle insulin resistance compared to offspring of dams on CTR diet. In the current study, we employed a nested design to test for differences in gene expression in skeletal muscle from lean 3-year-old adolescent offspring from dams fed a maternal WSD in both the presence and absence of maternal obesity or lean dams fed a CTR diet. We included offspring weaned to both a WSD or CTR diet to further account for differences in response to post-weaning diet and interaction effects between diets. Overall, we found that a maternal WSD fed to dams during pregnancy and lactation was the principal driver of differential gene expression (DEG) in offspring muscle at this time point. We identified key gene pathways important in insulin signaling including PI3K-Akt and MAP-kinase, regulation of muscle regeneration, and transcription-translation feedback loops, in both male and female offspring. Muscle DEG showed no measurable difference between offspring of obese dams on WSD compared to those of lean dams fed WSD. A post-weaning WSD effected offspring transcription only in individuals from the maternal CTR diet group but not in maternal WSD group. Collectively, we identify that maternal diet composition has a significant and lasting impact on offspring muscle transcriptome and influences later transcriptional response to WSD in muscle, which may underlie the increased metabolic disease risk in offspring.

The adolescent and young adult microbiome and its association with substance use: a scoping review

AIMS

The microbiome is a critical factor in health throughout human development. The aims of this scoping review are to (i) elucidate the differences between the youth (post-natal day 21-65 for rodents, 2-7 years for non-human primates, and 10-25 years for humans) microbiome with other life stages and (ii) identify youth-specific microbial changes associated with substance use.

METHODS

Peer-reviewed studies published up to May 2023 were identified in PubMed and SCOPUS and included gut and oral microbiome studies from rodents, non-human primates, and humans (N = 1733). Twenty-six articles were determined eligible based on inclusion criteria (aim 1: n = 19, aim 2: n = 7).

RESULTS

The adolescent and young adult oral and gut microbiomes are distinct compared to other life stages, within both non-human and human models. While there is limited research in this area, the microbiome appears to be vulnerable to substance use exposure earlier in life, including substances commonly initiated and escalated during adolescence and young adulthood (i.e. alcohol, cannabis, and tobacco).

CONCLUSIONS

Studies across the lifespan indicate that adolescence and young adulthood are distinct periods of development, where the microbiome is sensitive to exposures, including substance use. There is a need for more studies focused on the adolescent and young adult microbiome and substance use, as well as focused on the oral microbiome during this developmental period. Understanding the gut and oral microbiome during adolescence and young adulthood may provide insight into the pathophysiology of substance use disorders.

Maternal Western-style diet in nonhuman primates leads to offspring islet adaptations including altered gene expression and insulin hypersecretion

Maternal overnutrition is associated with increased susceptibility to type 2 diabetes in the offspring. Rodent models have shown that maternal overnutrition influences islet function in offspring. To determine whether maternal Western-style diet (WSD) alters prejuvenile islet function in a model that approximates that of human offspring, we utilized a well-characterized Japanese macaque model. We compared islet function from offspring exposed to WSD throughout pregnancy and lactation and weaned to WSD (WSD/WSD) compared with islets from offspring exposed only to postweaning WSD (CD/WSD) at 1 yr of age. WSD/WSD offspring islets showed increased basal insulin secretion and an exaggerated increase in glucose-stimulated insulin secretion, as assessed by dynamic ex vivo perifusion assays, relative to CD/WSD-exposed offspring. We probed potential mechanisms underlying insulin hypersecretion using transmission electron microscopy to evaluate β-cell ultrastructure, qRT-PCR to quantify candidate gene expression, and Seahorse assay to assess mitochondrial function. Insulin granule density, mitochondrial density, and mitochondrial DNA ratio were similar between groups. However, islets from WSD/WSD male and female offspring had increased expression of transcripts known to facilitate stimulus-secretion coupling and changes in the expression of cell stress genes. Seahorse assay revealed increased spare respiratory capacity in islets from WSD/WSD male offspring. Overall, these results show that maternal WSD feeding confers changes to genes governing insulin secretory coupling and results in insulin hypersecretion as early as the postweaning period. The results suggest a maternal diet leads to early adaptation and developmental programming in offspring islet genes that may underlie future β-cell dysfunction.NEW & NOTEWORTHY Programed adaptations in islets in response to maternal WSD exposure may alter β-cell response to metabolic stress in offspring. We show that islets from maternal WSD-exposed offspring hypersecrete insulin, possibly due to increased components of stimulus-secretion coupling. These findings suggest that islet hyperfunction is programed by maternal diet, and changes can be detected as early as the postweaning period in nonhuman primate offspring.

Maternal obesogenic diet regulates offspring bile acid homeostasis and hepatic lipid metabolism via the gut microbiome in mice

Mice exposed in gestation to maternal high-fat/high-sucrose (HF/HS) diet develop altered bile acid (BA) homeostasis. We hypothesized that these reflect an altered microbiome and asked if microbiota transplanted from HF/HS offspring change hepatic BA and lipid metabolism to determine the directionality of effect. Female mice were fed HF/HS or chow (CON) for 6 wk and bred with lean males. 16S sequencing was performed to compare taxa in offspring. Cecal microbiome transplantation (CMT) was performed from HF/HS or CON offspring into antibiotic-treated mice fed chow or high fructose. BA, lipid metabolic, and gene expression analyses were performed in recipient mice. Gut microbiomes from HF/HS offspring segregated from CON offspring, with increased Firmicutes to Bacteriodetes ratios and Verrucomicrobial abundance. After CMT was performed, HF/HS-recipient mice had larger BA pools, increased intrahepatic muricholic acid, and decreased deoxycholic acid species. HF/HS-recipient mice exhibited downregulated hepatic Mrp2, increased hepatic Oatp1b2, and decreased ileal Asbt mRNA expression. HF/HS-recipient mice exhibited decreased cecal butyrate and increased hepatic expression of Il6. HF/HS-recipient mice had larger livers and increased intrahepatic triglyceride versus CON-recipient mice after fructose feeding, with increased hepatic mRNA expression of lipogenic genes including Srebf1, Fabp1, Mogat1, and Mogat2. CMT from HF/HS offspring increased BA pool and shifted the composition of the intrahepatic BA pool. CMT from HF/HS donor offspring increased fructose-induced liver triglyceride accumulation. These findings support a causal role for vertical transfer of an altered microbiome in hepatic BA and lipid metabolism in HF/HS offspring.NEW & NOTEWORTHY We utilized a mouse model of maternal obesogenic diet exposure to evaluate the effect on offspring microbiome and bile acid homeostasis. We identified shifts in the offspring microbiome associated with changes in cecal bile acid levels. Transfer of the microbiome from maternal obesogenic diet-exposed offspring to microbiome-depleted mice altered bile acid homeostasis and increased fructose-induced hepatic steatosis.

Maternal and early life exposures and their potential to influence development of the microbiome

At the dawn of the twentieth century, the medical care of mothers and children was largely relegated to family members and informally trained birth attendants. As the industrial era progressed, early and key public health observations among women and children linked the persistence of adverse health outcomes to poverty and poor nutrition. In the time hence, numerous studies connecting genetics ("nature") to public health and epidemiologic data on the role of the environment ("nurture") have yielded insights into the importance of early life exposures in relation to the occurrence of common diseases, such as diabetes, allergic and atopic disease, cardiovascular disease, and obesity. As a result of these parallel efforts in science, medicine, and public health, the developing brain, immune system, and metabolic physiology are now recognized as being particularly vulnerable to poor nutrition and stressful environments from the start of pregnancy to 3 years of age. In particular, compelling evidence arising from a diverse array of studies across mammalian lineages suggest that modifications to our metagenome and/or microbiome occur following certain environmental exposures during pregnancy and lactation, which in turn render risk of childhood and adult diseases. In this review, we will consider the evidence suggesting that development of the offspring microbiome may be vulnerable to maternal exposures, including an analysis of the data regarding the presence or absence of a low-biomass intrauterine microbiome.

Western diet-induced shifts in the maternal microbiome are associated with altered microRNA expression in baboon placenta and fetal liver

Maternal consumption of a high-fat, Western-style diet (WD) disrupts the maternal/infant microbiome and contributes to developmental programming of the immune system and nonalcoholic fatty liver disease (NAFLD) in the offspring. Epigenetic changes, including non-coding miRNAs in the fetus and/or placenta may also underlie this risk. We previously showed that obese nonhuman primates fed a WD during pregnancy results in the loss of beneficial maternal gut microbes and dysregulation of cellular metabolism and mitochondrial dysfunction in the fetal liver, leading to a perturbed postnatal immune response with accelerated NAFLD in juvenile offspring. Here, we investigated associations between WD-induced maternal metabolic and microbiome changes, in the absence of obesity, and miRNA and gene expression changes in the placenta and fetal liver. After ~8-11 months of WD feeding, dams were similar in body weight but exhibited mild, systemic inflammation (elevated CRP and neutrophil count) and dyslipidemia (increased triglycerides and cholesterol) compared with dams fed a control diet. The maternal gut microbiome was mainly comprised of Lactobacillales and Clostridiales, with significantly decreased alpha diversity (P = 0.0163) in WD-fed dams but no community-wide differences (P = 0.26). At 0.9 gestation, mRNA expression of IL6 and TNF in maternal WD (mWD) exposed placentas trended higher, while increased triglycerides, expression of pro-inflammatory CCR2, and histological evidence for fibrosis were found in mWD-exposed fetal livers. In the mWD-exposed fetus, hepatic expression levels of miR-204-5p and miR-145-3p were significantly downregulated, whereas in mWD-exposed placentas, miR-182-5p and miR-183-5p were significantly decreased. Notably, miR-1285-3p expression in the liver and miR-183-5p in the placenta were significantly associated with inflammation and lipid synthesis pathway genes, respectively. Blautia and Ruminococcus were significantly associated with miR-122-5p in liver, while Coriobacteriaceae and Prevotellaceae were strongly associated with miR-1285-3p in the placenta; both miRNAs are implicated in pathways mediating postnatal growth and obesity. Our findings demonstrate that mWD shifts the maternal microbiome, lipid metabolism, and inflammation prior to obesity and are associated with epigenetic changes in the placenta and fetal liver. These changes may underlie inflammation, oxidative stress, and fibrosis patterns that drive NAFLD and metabolic disease risk in the next generation.

Cecal Microbiota Modulates Fat Deposition in Muscovy Ducks

Ducks with the same genetic background vary greatly in their adiposity phenotypes. The gut microbiota plays an essential role in host physiological development and metabolism including fat deposition. However, the association of the gut microbiota with the lipogenic phenotype of ducks remains unknown. In this study, we investigated the cecal microbiota of adult Muscovy ducks and the correlation of the cecal microbiota with fat phenotypes. A total of 200 Muscovy ducks were selected from a population of 5,000 Muscovy ducks to record their abdominal fat weight and collect their cecal contents after being slaughtered and defeathered. The cecal contents were subjective to DNA isolation and 16S rRNA gene sequencing. The results were sorted according to the percentage of abdominal fat and the top 20% (n = 40) and the bottom 20% (n = 40) were set as the high and low groups, respectively. Our results indicated that in the cecum of Muscovy ducks, Bacteroidetes, Firmicutes, and Fusobacteria were the predominant phyla while Bacteroides, Oscillospiraceae_uncultured, Parabacteroides, and Bacteroidales_norank were the top 4 dominant genera. Abdominal fat weight (18.57~138.10 g) and percentage of abdominal fat (1.02~27.12%) were significantly correlated (R² = 0.92, P < 0.001). Although the lipogenic phenotypes of ducks had a significant difference (P < 0.05), the α-diversities of the high and low groups were not significantly different (P > 0.05). Nevertheless, after random forest analysis, we identified two genera, Treponema and Ruminococcus_torques_group, that were significantly associated with fat deposition in Muscovy ducks. In addition, the abundances of Treponema and Ruminococcus_torques_group gave a significantly negative and positive association with abdominal fat weight, respectively (P < 0.05). Ducks with a low level of Treponema exhibited a tendency toward a high percentage of abdominal fat (P < 0.01), while the percentage of abdominal fat in ducks with high Ruminococcus_torques_group abundance tended to be higher than that in ducks with low Ruminococcus_torques_group abundance (P < 0.01). These findings could provide the basic data on the cecal microbiota in Muscovy ducks as well as a theoretical foundation to limit the fat deposition by modulating the gut microbiota in the duck industry.

Developmental effects of in utero metformin exposure

According to the Developmental Origins of Health and Disease (DOHaD) hypothesis, the intrauterine environment influences fetal programming and development, affecting offspring disease susceptibility in adulthood. In recent years, therapeutic use of the Type 2 diabetes drug metformin has expanded to the treatment of pre-diabetes, polycystic ovarian syndrome, and gestational diabetes. Because metformin both undergoes renal excretion and binds to receptors on the placenta, the fetus receives equivalent maternal dosing. Although no teratogenic nor short-term harmful fetal impact of metformin is known to occur, the effects of metformin exposure on longer-range offspring development have not yet been fully elucidated. This review encapsulates the (albeit limited) existing knowledge regarding the potential longer-term impact of intrauterine metformin exposure on the development of key organs including the liver, central nervous system, heart, gut, and endocrine pancreas in animal models and humans. We discuss molecular and cellular mechanisms that would be altered in response to treatment and describe the potential consequences of these developmental changes on postnatal health. Further studies regarding the influence of metformin exposure on fetal programming and adult metabolic health will provide necessary insight to its long-term risks, benefits, and limitations in order to guide decisions for use of metformin during pregnancy.

Maternal diet alters human milk oligosaccharide composition with implications for the milk metagenome

Human milk is the optimal nutrition source for infants, and oligosaccharides represent the third most abundant component in milk after lactose and fat. Human milk oligosaccharides (HMO) are favorable macromolecules which are, interestingly, indigestible by the infant but serve as substrates for bacteria. Hypothesizing that the maternal diet itself might influence HMO composition, we sought to directly determine the effect maternal diet on HMO and the milk bacteria. Employing a human cross-over study design, we demonstrate that distinct maternal dietary carbohydrate and energy sources preferentially alter milk concentrations of HMO, including fucosylated species. We find significant associations between the concentration of HMO-bound fucose and the abundance of fucosidase (a bacterial gene that digests fucose moieties) harbored by milk bacteria. These studies reveal a successive mechanism by which the maternal diet during lactation alters milk HMO composition, which in turn shapes the functional milk microbiome prior to infant ingestion.

Maternal Linoleic Acid Overconsumption Alters Offspring Gut and Adipose Tissue Homeostasis in Young but Not Older Adult Rats

Maternal n-6 polyunsaturated fatty acids (PUFA) consumption during gestation and lactation can predispose offspring to the development of metabolic diseases such as obesity later in life. However, the mechanisms underlying the potential programming effect of n-6 PUFA upon offspring physiology are not yet all established. Herein, we investigated the effects of maternal and weaning linoleic acid (LA)-rich diet interactions on gut intestinal and adipose tissue physiology in young (3-month-old) and older (6-month-old) adult offspring. Pregnant rats were fed a control diet (2% LA) or an LA-rich diet (12% LA) during gestation and lactation. At weaning, offspring were either maintained on the maternal diet or fed the other diet for 3 or 6 months. At 3 months of age, the maternal LA-diet favored low-grade inflammation and greater adiposity, while at 6 months of age, offspring intestinal barrier function, adipose tissue physiology and hepatic conjugated linoleic acids were strongly influenced by the weaning diet. The maternal LA-diet impacted offspring cecal microbiota diversity and composition at 3 months of age, but had only few remnant effects upon cecal microbiota composition at 6 months of age. Our study suggests that perinatal exposure to high LA levels induces a differential metabolic response to weaning diet exposure in adult life. This programming effect of a maternal LA-diet may be related to the alteration of offspring gut microbiota.

Interactions between Environmental Exposures and the Microbiome: Implications for Fetal Programming

Decades of population-based health outcomes data highlight the importance of understanding how environmental exposures in pregnancy affect maternal and neonatal outcomes. Animal model research and epidemiological studies have revealed that such exposures are able to alter fetal programming through stable changes in the epigenome, including altered DNA methylation patterns and histone modifications in the developing fetus and infant. It is similarly known that while microbes can biotransform environmental chemicals via conjugation and de-conjugation, specific exposures can also alter the community profile and function of the human microbiome. In this review, we consider how alterations to the maternal and or fetal/infant microbiome through environmental exposures could directly and indirectly alter fetal programming. We highlight two specific environmental exposures, cadmium (Cd) and polycyclic aromatic hydrocarbons (PAHs), and outline their effects on the developing fetus and the perinatal (maternal and fetal/infant) microbiome. We further consider how chemical exposures in the setting of natural disasters may be of particular importance to environmental health.

Preliminary feasibility for recruiting and retaining black and white females to provide fecal samples for longitudinal research

As the associations between the gut microbiota and numerous health outcomes become more evident, it is important to conduct longitudinal microbiome research to advance the field beyond the identification of associations. It is also necessary to include individuals who have historically been underrepresented in biomedical research in longitudinal microbiome studies to better understand and eliminate racial/ethnic health disparities. This paper describes our experiences in recruiting and retaining participants for an ongoing, longitudinal microbiome study for which the main results will be reported at a later time. This article provides preliminary evidence of the feasibility of recruiting and retaining a racially diverse sample of females (97% completion for invited participants) for longitudinal microbiome research.