Dynamic Associations of Milk Components With the Infant Gut Microbiome and Fecal Metabolites in a Mother–Infant Model by Microbiome, NMR Metabolomic, and Time-Series Clustering Analyses

Background: The gut microbiome and fecal metabolites of breastfed infants changes during lactation, and are influenced by breast milk components. This study aimed to investigate dynamic associations of milk components with the infant gut microbiome and fecal metabolites throughout the lactation period in a mother–infant model.Methods: One month after delivery, breast milk and subsequent infant feces were collected in a pair for 5 months from a mother and an exclusively breastfed infant. Composition of the fecal microbiome was determined with 16S rRNA sequencing. Low-molecular-weight metabolites, including human milk oligosaccharides (HMOs), and antibacterial proteins were measured in feces and milk using 1H NMR metabolomics and enzyme-linked immunosorbent assays. The association of milk bioactive components with the infant gut microbiome and fecal metabolites was determined with Python clustering and correlation analyses.Results: The HMOs in milk did not fluctuate throughout the lactation period. However, they began to disappear in infant feces at the beginning of month 4. Notably, at this time-point, a bifidobacterium species switching (from B. breve to B. longum subsp. infantis) occurred, accompanied by fluctuations in several metabolites including acetate and butyrate in infant feces.Conclusions: Milk bioactive components, such as HMOs, might play different roles in the exclusively breastfed infants depending on the lactation period.

482. SARS-CoV-2 Prevalence in Feces of Very Young Children, A Longitudinal Study

Background Understanding the disease burden of SARS- CoV-2 in young children has been challenging as the majority are asymptomatic or experience mild symptoms and were rarely tested. SARS-CoV-2 is traditionally detected through respiratory secretions but has also been reported in feces where shedding may continue for weeks after respiratory samples show resolution. We examined the prevalence of SARS-CoV-2 in already collected fecal samples from young children through the pandemic as well as associated demographic factors. Methods As part of an ongoing longitudinal microbiome study in Northern Virginia, serial stools samples were collected from infants before and throughout the Covid-19 pandemic. Reverse transcription quantitative-PCR detecting SARS-CoV-2 nucleocapsid gene in the N1 and N2 regions was performed. Penalized logistic regression models were developed to evaluate the association between fecal positivity and potential risk factors. Results The overall prevalence of SARS-CoV-2 in infant feces was 1.69 % (13 samples) with a prevalence at delivery, 2, 6, 12 and 24 months of 0, 0, 2.56, 1.96, and 0.85 % respectively. Fecal positivity was first detected 31 days before the reported first case of Covid-19 in Northern Virginia; prevalence rates peaked in September at 4.5% (Figure 1). Only one infant who tested positive was symptomatic with COVID-19 21 days before his stool was collected. Of the 13 positive samples, 8 reported Hispanic ethnicity and 7 reported an essential worker (Table 1). Penalized logistic regression model showed association between Hispanic ethnicity and testing positive (OR 5.04 (95% CI 1.7 – 15.0)) that remained after controlling for the presences of an essential worker (OR 4.7 (95% CI 1.6 – 14.0)). Conclusion Prevalence of SARS- CoV-2 in infant stool correlated with the prevalence of COVID-19 during the pandemic, with higher rates in those of Hispanic ethnicity corelating with regional trends. Fecal positivity in asymptomatic infants even before quarantine restrictions supports the early but silent transmission of SARS-CoV-2. This study likely underestimates true prevalence rates as stool samples were stored without viral preservative. There are many socioeconomic factors that predispose to disease while ethnicity may be a mediating or confounding factor Disclosures All Authors: No reported disclosures

The Species-Level Composition of the Fecal Bifidobacterium and Lactobacillus Genera in Indonesian Children Differs from That of Their Mothers

The infant gut microbiota plays a critical role in early life growth and derives mainly from maternal gut and breast milk. This study aimed to analyze the differences in the gut microbiota, namely Bifidobacterium and Lactobacillus communities at species level among breast milk as well as maternal and infant feces at different time points after delivery. Fifty-one mother–infant pairs from Indonesia were recruited, and the breast milk and maternal and infant feces were collected and analyzed by high throughput sequencing (16S rRNA, Bifidobacterium groEL and Lactobacillus groEL genes). PCoA results showed bacterial composition was different among breast milk and maternal and infant feces within the first two years. The abundance of Bifidobacterium and Bacteroides were significantly higher in infant feces compared to their maternal feces from birth to two years of age, and maternal breast milk within six months after birth (p < 0.05), whereas the abundance of Blautia, Prevotella, and Faecalibacterium was higher in maternal feces compared to that in breast milk within six months and infant feces within one year after birth, respectively (p < 0.05). The relative abundances of Bacteroides and Lactobacillus was higher and lower in infant feces compared to that in maternal feces only between one and two years of age, respectively (p < 0.05). For Bifidobacterium community at species level, B. adolescentis, B. ruminantium, B. longum subsp. infantis, B. bifidum, and B. pseudolongum were identified in all samples. However, the profile of Bifidobacterium was different between maternal and infant feces at different ages. The relative abundances of B. adolescentis and B. ruminantium were higher in maternal feces compared to those in infant feces from birth to one year of age (p < 0.05), while the relative abundances of B. longum subsp. infantis and B. bifidum were higher in infant feces compared to those in maternal feces beyond three months, and the relative abundance of B. pseudolongum was only higher in infant feces between three and six months (p < 0.05). For Lactobacillus community, L. paragasseri showed higher relative abundance in infant feces when the infant was younger than one year of age (p < 0.05). This study showed bacterial composition at the genus level and Bifidobacterium and Lactobacillus communities at the species level were stage specific in maternal breast milk as well as and maternal and infant feces.

Lactobacillus paracasei R3 protects against dextran sulfate sodium (DSS)-induced colitis in mice via regulating Th17/Treg cell balance

Inflammatory bowel diseases (IBD), mainly comprising ulcerative colitis (UC) and Crohn's Disease, are most often a polygenic disorder with contributions from the intestinal microbiome, defects in barrier function, and dysregulated host responses to microbial stimulation. Strategies that target the microbiota have emerged as potential therapies and, of these, probiotics have gained the greatest attention. Herein, we isolated a strain of Lactobacillus paracasei R3 (L.p R3) with strong biofilm formation ability from infant feces. Interestingly, we also found L.p R3 strain can ameliorate the general symptoms of murine colitis, alleviate inflammatory cell infiltration and inhibit Th17 while promote Treg function in murine dextran sulfate sodium (DSS)-induced colitis. Overall, this study suggested that L.p R3 strain significantly improves the symptoms and the pathological damage of mice with colitis and influences the immune function by regulating Th17/Treg cell balance in DSS-induced colitis in mice.

Variation in Human Milk Composition Is Related to Differences in Milk and Infant Fecal Microbial Communities

Previously published data from our group and others demonstrate that human milk oligosaccharide (HMOs), as well as milk and infant fecal microbial profiles, vary by geography. However, little is known about the geographical variation of other milk-borne factors, such as lactose and protein, as well as the associations among these factors and microbial community structures in milk and infant feces. Here, we characterized and contrasted concentrations of milk-borne lactose, protein, and HMOs, and examined their associations with milk and infant fecal microbiomes in samples collected in 11 geographically diverse sites. Although geographical site was strongly associated with milk and infant fecal microbiomes, both sample types assorted into a smaller number of community state types based on shared microbial profiles. Similar to HMOs, concentrations of lactose and protein also varied by geography. Concentrations of HMOs, lactose, and protein were associated with differences in the microbial community structures of milk and infant feces and in the abundance of specific taxa. Taken together, these data suggest that the composition of human milk, even when produced by relatively healthy women, differs based on geographical boundaries and that concentrations of HMOs, lactose, and protein in milk are related to variation in milk and infant fecal microbial communities.

Lactobacillus Paracasei R3 Protects Against Dextran Sulfate Sodium (DSS)-Induced Colitis in Mice via Regulating Th17/Treg Cell Balance

Inflammatory bowel diseases (IBD), mainly comprising ulcerative colitis (UC) and Crohn's Disease, are most often a polygenic disorder with contributions from the intestinal microbiome, defects in barrier function, and dysregulated host responses to microbial stimulation. Strategies that target the microbiota have emerged as potential therapies and, of these, probiotics have gained the greatest attention. Herein, we isolated a strain of Lactobacillus paracasei R3 (L.p R3) with strong biofilm formation ability from infant feces. Interestingly, we also found L.p R3 strain can ameliorate the general symptoms of murine colitis, alleviate inflammatory cell infiltration and inhibit Th17 while promote Treg function in murine DSS-induced colitis. Overall, this study suggested that L.p R3 strain significantly improves the symptoms and the pathological damage of mice with colitis and influences the immune function by regulating Th17/Treg cell balance in DSS-induced colitis in mice.

An Examination of Lactobacillus paracasei GKS6 and Bifidobacterium lactis GKK2 Isolated from Infant Feces in an Aged Mouse Model

Supplementary which could maintain normal physiological mechanisms and functions while aging has drawn our attention due to the population aging in recent years. Probiotics have been believed with desirable properties such as antioxidation and anti-inflammatory for delaying the aging process. However, the age-related experiments conducted in the mammalian models with probiotics were few. In this study, we demonstrated the effects of administration of probiotics Lactobacillus paracasei GKS6 (GKS6) and Bifidobacterium lactis GKK2 (GKK2), respectively, at the dosage of 5.0 × 109 cfu/kg BW/day for fourteen weeks in senescence-accelerated mouse prone 8 (SAMP8) mice. The three-month-old SAMP8 mice were divided into three groups: control, mice fed with GKS6, and mice fed with GKK2. There were ten females and ten males in each group. The SAMP8 mice fed with probiotics GKS6 and GKK2 showed a significantly lower degree of aging followed by Takeda’s grading method on the eleventh week of the experiment. The GKK2 group showed significantly increased forelimb grip strength in male SAMP8 mice and muscle fiber number in both genders. Compared to the control, both GKS6 and GKK2 presented a significant increase in liver superoxide dismutase and catalase activities. In addition, a significant decrease in the levels of liver thiobarbituric acid-reactive substances was observed in the probiotics group. These results suggested that probiotics GKS6 and GKK2 could act as antioxidants in delaying the process of aging and preventing age-related muscle loss.