Evolution of the gut microbiome in infancy within an ecological context

Urinary metabolome of infants with colic treated with Lactobacillus reuteri DSM 17938: a pilot randomized trial

BACKGROUND

Lactobacillus reuteri DSM 17938 is the only probiotic recommended for treatment of colicky infants, but its mechanism of action is not clear. The study aim was to examine urinary metabolomic fingerprint of colicky breastfed infants before and after 1 month of orally administered Lactobacillus reuteri DSM 17938 or placebo.

METHODS

This randomized, blinded, placebo-controlled clinical trial was carried out with a well-documented probiotic. Thirty-two infants were enrolled, 16 in the probiotic group and 16 in the placebo group. Urine samples were collected from each subject before starting supplementation and at the end of the study period. Metabolomic profiles were obtained using a gas chromatography/mass spectrometry instrument. Subsequently, to compare groups before and after probiotic supplementation, univariate and multivariate statistical analysis were performed.

RESULTS

In the L. reuteri treated group all metabolites for all class of nutrients (sugars, amino acids, carboxylic acids) resulted more abundant after the study period. The comparison with a control group (placebo treated), confirmed this effect on urines.

CONCLUSIONS

The metabolomic analysis of urine samples from infants treated with L. reuteri DSM 17938 allowed to detect some interesting features related to the effect of this treatment on urinary metabolome. To validate the results, a test on a larger cohort is required.

Clinically Integrated Breastfeeding Peer Counseling to Promote Breastfeeding Equity

OBJECTIVE

 This study aimed to determine whether clinically integrated Breastfeeding Peer Counseling (ci-BPC) added to usual lactation care reduces disparities in breastfeeding intensity and duration for Black and Hispanic/Latine participants.

STUDY DESIGN

 This study is a pragmatic, randomized control trial (RCT) of ci-BPC care at two ci-BPC-naïve obstetrical hospital facilities in the greater Chicago area. Participants will include 720 patients delivering at Hospital Site 1 and Hospital Site 2 who will be recruited from eight prenatal care sites during midpregnancy. Participants must be English or Spanish speaking, planning to parent their child, and have no exposure to ci-BPC care prior to enrollment. Randomization will be stratified by race and ethnicity to create three analytic groups: Black, Hispanic/Latine, and other races.

RESULTS

 The primary outcome will be breastfeeding duration. Additional outcomes will include the proportion of breastmilk feeds during the delivery admission, at 6-week postdelivery, and at 6-month postdelivery. A process evaluation will be conducted to understand implementation outcomes, facilitators, and barriers to inform replication and scaling of the innovative ci-BPC model.

CONCLUSION

This research will produce findings of relevance to perinatal patients and their families, the vast majority of whom desire to provide breastmilk to their infants and require support to succeed with their feeding goals. As the largest RCT of ci-BPC in the United States to date, this research will improve the quality of evidence available regarding the effectiveness of ci-BPC at reducing disparities. These findings will help patients and stakeholders determine the benefits of accepting and adopting the program and inform policies focused on improving perinatal care and reducing maternal/child health disparities. This study is registered with Clinical Trial (identifier: NCT05441709).

KEY POINTS

· Ci-BPC can promote racial breastfeeding equity.. · Ci-BPC has not been tested as a generalized lactation strategy in prior trials and is underused.. · This RCT will identify if ci-BPC can reduce breastfeeding disparities for Black and Hispanic patients..

U.S. Breastfeeding Outcomes at the Intersection: Differences in Duration Among Racial and Ethnic Groups With Varying Educational Attainment in a Nationally Representative Sample

BACKGROUND

As breastfeeding rates in the United States increase, barriers persist for Black, Latine, and low-socioeconomic status household dyads when compared to White and high-socioeconomic status household dyads. Previous breastfeeding disparities research has almost exclusively considered the influence of race, ethnicity, and socioeconomic status separately, although these attributes are not randomly distributed across the population.

RESEARCH AIM

To identify breastfeeding duration patterns by race/ethnicity and educational attainment in a nationally representative U.S. National Immunization Survey sample.

METHOD

We conducted a cross-sectional, secondary analysis of the U.S. Centers for Disease Control and Prevention's 2020 National Immunization Survey-Child public-use data. To examine breastfeeding and exclusive breastfeeding durations at the intersection of race/ethnicity and educational attainment, we created a 12-item, cross-classified variable using three educational attainment groups and four race/ethnicity groups. We used linear regressions to test these associations.

RESULTS

In all, 83% of the sample breastfed. Mean durations of breastfeeding were 7.5 (SE = 1.95) months and exclusive breastfeeding duration was 4.9 (SE = 0.87) months. In adjusted models, multi-race/other high-educational attainment participants had the longest breastfeeding duration by almost 3 weeks (β: 19.53, 95% CI [5.27, 33.79]), and Black low-educational attainment participants exclusively breastfed for 1 month less than White high-educational attainment participants (β:-30.23, 95% CI [-40.87, -19.58]).

CONCLUSIONS

Examining race/ethnicity and educational attainment together provides an intersectional understanding of breastfeeding outcomes and can inform targeted, culturally appropriate interventions.

Release of HMGB1 and Toll-like Receptors 2, 4, and 9 Signaling Are Modulated by Bifidobacterium animalis subsp. lactis BB-12 and Salmonella Typhimurium in a Gnotobiotic Piglet Model of Preterm Infants

Gnotobiotic (GN) animals with defined microbiota allow us to study host-microbiota and microbiota-microbiota interferences. Preterm germ-free (GF) piglets were mono-associated with probiotic Bifidobacterium animalis subsp. lactis BB-12 (BB12) to ameliorate/prevent the consequences of infection with the Salmonella Typhimurium strain LT2 (LT2). Goblet cell density; expression of Toll-like receptors (TLRs) 2, 4, and 9; high mobility group box 1 (HMGB1); interleukin (IL)-6; and IL-12/23p40 were analyzed to evaluate the possible modulatory effect of BB12. BB12 prevented an LT2-induced decrease of goblet cell density in the colon. TLRs signaling modified by LT2 was not influenced by the previous association with BB12. The expression of HMGB1, IL-6, and IL12/23p40 in the jejunum, ileum, and colon and their levels in plasma were all decreased by BB12, but these changes were not statistically significant. In the colon, differences in HMGB1 distribution between the GF and LT2 piglet groups were observed. In conclusion, the mono-association of GF piglets with BB12 prior to LT2 infection partially ameliorated the inflammatory response to LT2 infection.

Rapid evolution and strain turnover in the infant gut microbiome

While the ecological dynamics of the infant gut microbiome have been intensely studied, relatively little is known about evolutionary dynamics in the infant gut microbiome. Here we analyze longitudinal fecal metagenomic data from >700 infants and their mothers over the first year of life and find that the evolutionary dynamics in infant gut microbiomes are distinct from that of adults. We find evidence for more than 10-fold increase in the rate of evolution and strain turnover in the infant gut compared to healthy adults, with the mother-infant transition at delivery being a particularly dynamic period in which gene loss dominates. Within a few months after birth, these dynamics stabilize, and gene gains become increasingly frequent as the microbiome matures. We furthermore find that evolutionary changes in infants show signatures of being seeded by a mixture of de novo mutations and transmissions of pre-evolved lineages from the broader family. Several of these evolutionary changes occur in parallel across infants, highlighting candidate genes that may play important roles in the development of the infant gut microbiome. Our results point to a picture of a volatile infant gut microbiome characterized by rapid evolutionary and ecological change in the early days of life.

Exfoliated epithelial cell transcriptome reflects both small and large intestinal cell signatures in piglets

Assessing intestinal development and host-microbe interactions in healthy human infants requires noninvasive approaches. We have shown that the transcriptome of exfoliated epithelial cells in feces can differentiate breast-fed and formula-fed infants and term and preterm infants. However, it is not fully understood which regions of the intestine that the exfoliated cells represent. Herein, the transcriptional profiles of exfoliated cells with that of the ileal and colonic mucosa were compared. We hypothesized that exfoliated cells in the distal colon would reflect mucosal signatures of more proximal regions of the gut. Two-day-old piglets (n = 8) were fed formulas for 20 days. Luminal contents and mucosa were collected from ileum (IL), ascending colon (AC), and descending (DC) colon, and mRNA was extracted and sequenced. On average, ∼13,000 genes were mapped in mucosal tissues and ∼10,000 in luminal contents. The intersection of detected genes between three mucosa regions and DC exfoliome indicated an approximately 99% overlap. On average, 49% of the genes in IL, AC, and DC mucosa were present in the AC and DC exfoliome. Genes expressed predominantly in specific anatomic sites (stomach, pancreas, small intestine, colon) were detectable in exfoliated cells. In addition, gene markers for all intestinal epithelial cell types were expressed in the exfoliome representing a diverse array of cell types arising from both the small and large intestine. Genes were mapped to nutrient absorption and transport and immune function. Thus, the exfoliome represents a robust reservoir of information in which to assess intestinal development and responses to dietary interventions.NEW & NOTEWORTHY The transcriptome of exfoliated epithelial cells in stool contain gene signatures from both small and large intestinal mucosa affording a noninvasive approach to assess gut health and function.

The Role of the Microbiota-Gut-Brain Axis in the Health and Illness Condition: A Focus on Alzheimer's Disease

Trillions of commensal microbes live in our body, the majority in the gut. This gut microbiota is in constant interaction with the homeostatic systems, the nervous, immune and endocrine systems, being fundamental for their appropriate development and function as well as for the neuroimmunoendocrine communication. The health state of an individual is understood in the frame of this communication, in which the microbiota-gut-brain axis is a relevant example. This bidirectional axis is constituted in early age and is affected by many environmental and lifestyle factors such as diet and stress, among others, being involved in the adequate maintenance of homeostasis and consequently in the health of each subject and in his/her rate of aging. For this, an alteration of gut microbiota, as occurs in a dysbiosis, and the associated gut barrier deterioration and the inflammatory state, affecting the function of immune, endocrine and nervous systems, in gut and in all the locations, is in the base of a great number of pathologies as those that involve alterations in the brain functions. There is an age-related deterioration of microbiota and the homeostatic systems due to oxi-inflamm-aging, and thus the risk of aging associated pathologies such as the neurodegenerative illness. Currently, this microbiota-gut-brain axis has been considered to have a relevant role in the pathogenesis of Alzheimer's disease and represents an important target in the prevention and slowdown of the development of this pathology. In this context, the use of probiotics seems to be a promising help.

Monoassociation of Preterm Germ-Free Piglets with Bifidobacterium animalis Subsp. lactis BB-12 and Its Impact on Infection with Salmonella Typhimurium

Preterm germ-free piglets were monoassociated with probiotic Bifidobacterium animalis subsp. lactis BB-12 (BB12) to verify its safety and to investigate possible protection against subsequent infection with Salmonella Typhimurium strain LT2 (LT2). Clinical signs of salmonellosis, bacterial colonization in the intestine, bacterial translocation to mesenteric lymph nodes (MLN), blood, liver, spleen, and lungs, histopathological changes in the ileum, claudin-1 and occludin mRNA expression in the ileum and colon, intestinal and plasma concentrations of IL-8, TNF-α, and IL-10 were evaluated. Both BB12 and LT2 colonized the intestine of the monoassociated piglets. BB12 did not translocate in the BB12-monoassociated piglets. BB12 was detected in some cases in the MLN of piglets, consequently infected with LT2, but reduced LT2 counts in the ileum and liver of these piglets. LT2 damaged the luminal structure of the ileum, but a previous association with BB12 mildly alleviated these changes. LT2 infection upregulated claudin-1 mRNA in the ileum and colon and downregulated occludin mRNA in the colon. Infection with LT2 increased levels of IL-8, TNF-α, and IL-10 in the intestine and plasma, and BB12 mildly downregulated them compared to LT2 alone. Despite reductions in bacterial translocation and inflammatory cytokines, clinical signs of LT2 infection were not significantly affected by the probiotic BB12. Thus, we hypothesize that multistrain bacterial colonization of preterm gnotobiotic piglets may be needed to enhance the protective effect against the infection with S. Typhimurium LT2.

Colonization of Germ-Free Piglets with Mucinolytic and Non-Mucinolytic Bifidobacterium boum Strains Isolated from the Intestine of Wild Boar and Their Interference with Salmonella Typhimurium

Non-typhoidal Salmonella serovars are worldwide spread foodborne pathogens that cause diarrhea in humans and animals. Colonization of gnotobiotic piglet intestine with porcine indigenous mucinolytic Bifidobacterium boum RP36 strain and non-mucinolytic strain RP37 and their interference with Salmonella Typhimurium infection were compared. Bacterial interferences and impact on the host were evaluated by clinical signs of salmonellosis, bacterial translocation, goblet cell count, mRNA expression of mucin 2, villin, claudin-1, claudin-2, and occludin in the ileum and colon, and plasmatic levels of inflammatory cytokines IL-8, TNF-α, and IL-10. Both bifidobacterial strains colonized the intestine comparably. Neither RP36 nor RP37 B. boum strains effectively suppressed signs of salmonellosis. Both B. boum strains suppressed the growth of S. Typhimurium in the ileum and colon. The mucinolytic RP36 strain increased the translocation of S. Typhimurium into the blood, liver, and spleen.

The human gut microbiota is neither an organ nor a commensal

The recent explosive increase in the number of works on gut microbiota has been accompanied by the spread of rather vague or improper definitions, chosen more for common use than for experimental evidence. Among them are those defining the human gut microbiota as an organ of our body or as a commensal. But, is the human gut microbiota an organ or a commensal? Here, we address this issue to spearhead a reflection on the real roles of the human gut microbiota in our life. Actually, the misuse of the vocabulary used to describe the properties and functions of the gut microbiota may generate confusion and cause misunderstandings both in the scientific community and among the general public.