Changes of intestinal microbiota in early life

Streptococcus Thermophilus UASt-09 Upregulates Goblet Cell Activity in Colonic Epithelial Cells to a Greater Degree than other Probiotic Strains

Probiotics have been widely used in maintaining gastrointestinal health, despite their actual mechanism remaining obscure. There are several hypotheses behind the beneficial effects of probiotics including the regulation of intestinal barrier function and improvement in immune responses in the gastrointestinal system. Multiple probiotics have been introduced in the market as effective dietary supplements in improving gastrointestinal integrity, but there are no or few studies that demonstrate their underlying mechanism. In the current study, we investigated and compared the efficacy of four probiotics (based on different bacterial species) in refining gastrointestinal health by improving mucus biosynthesis and intestinal immune response under in-vitro conditions. By analyzing the gene expression of mucus biosynthesis and intestinal immune response markers, we found that probiotic Streptococcus thermophilus UASt-09 showed promising potential in refining mucosal barrier and gastrointestinal health in human colonic epithelial cells, as compared to other commercial probiotics.

The Italian arm of the PREPARE study: an international project to evaluate and license a maternal vaccine against group B streptococcus

BACKGROUND

Group B streptococcus (GBS) is a leading cause of sepsis, pneumonia and meningitis in infants, with long term neurodevelopmental sequelae. GBS may be associated with poor pregnancy outcomes, including spontaneous abortion, stillbirth and preterm birth. Intrapartum antibiotic prophylaxis (IAP) is currently the only way to prevent early-onset disease (presenting at 0 to 6 days of life), although it has no impact on the disease presenting over 6 days of life and its implementation is challenging in resource poor countries. A maternal vaccine against GBS could reduce all GBS manifestations as well as improve pregnancy outcomes, even in low-income countries.

MAIN BODY

The term "PREPARE" designates an international project aimed at developing a maternal vaccination platform to test vaccines against neonatal GBS infections by maternal immunization. It is a non-profit, multi-center, interventional and experimental study (promoted by the St George University of London. [UK]) with the aim of developing a maternal vaccination platform, determining pregnancy outcomes, and defining the extent of GBS infections in children and mothers in Africa. PREPARE also aims to estimate the protective serocorrelates against the main GBS serotypes that cause diseases in Europe and Africa and to conduct two trials on candidate GBS vaccines. PREPARE consists of 6 work packages. In four European countries (Italy, UK, Netherlands, France) the recruitment of cases and controls will start in 2020 and will end in 2022. The Italian PREPARE network includes 41 centers. The Italian network aims to collect: GBS isolates from infants with invasive disease, maternal and neonatal sera (cases); cord sera and GBS strains from colonized mothers whose infants do not develop GBS infection (controls).

SHORT CONCLUSION

PREPARE will contribute information on protective serocorrelates against the main GBS serotypes that cause diseases in Europe and Africa. The vaccine that will be tested by the PREPARE study could be an effective strategy to prevent GBS disease.

Time to Positivity of Neonatal Blood Cultures for Early-onset Sepsis

BACKGROUND

In newborns at risk for early-onset sepsis, empiric antibiotics are often initiated while awaiting the results of blood cultures. The duration of empiric therapy can be guided by the time to positivity (TTP) of blood cultures. The objective of the study was to determine the TTP of neonatal blood cultures for early-onset sepsis and the factors which may impact TTP.

METHODS

Observational study of blood cultures growing pathogenic species obtained within 72 hours of birth from infants born at 23-42 weeks gestation, at 19 hospitals in Northern California, Boston, and Philadelphia. TTP was defined as the time from blood culture collection to the time organism growth was reported by the microbiology laboratory.

RESULTS

A total of 594 blood cultures growing pathogenic bacteria were identified. Group B Streptococcus and Escherichia coli accounted for 74% of blood culture isolates. Median TTP was 21.0 hours (interquartile range, 17.1-25.3 hours). Blood cultures were identified as positive by 24 hours after they were obtained in 68% of cases; by 36 hours in 94% of cases; and by 48 hours in 97% of cases. Neither the administration of maternal intrapartum antibiotic prophylaxis, gestational age <35 weeks, nor blood culture system impacted median TTP.

CONCLUSIONS

Pathogens are isolated by 36 hours after blood culture collection in 94% of neonatal early blood cultures, regardless of maternal antibiotic administration. TTP information can inform decisions regarding the duration of empiric neonatal antibiotic therapies.

Potential Elimination of Human Gut Resistome by Exploiting the Benefits of Functional Foods

Recent advances in technology over the last decades have strived to elucidate the diverse and abundant ecosystem of the human microbiome. The intestinal microbiota represents a densely inhabited environment that offers a plethora of beneficial effects to the host's wellbeing. On the other hand, it can serve as a potential reservoir of Multi-Drug Resistant (MDR) bacteria and their antibiotic-resistant genes (ARgenes), which comprise the "gut resistome." ARgenes, like antibiotics, have been omnipresent in the environment for billions of years. In the context of the gut microbiome, these genes may conflate into exogenous MDR or emerge in commensals due to mutations or gene transfers. It is currently generally accepted that Antimicrobial Resistance (AMR) poses a serious threat to public health worldwide. It is of paramount importance that researchers focus on, amongst other parameters, elaborating strategies to manage the gut resistome, particularly focusing on the diminution of AMR. Potential interventions in the gut microbiome field by Fecal Microbiota Transplant (FMT) or functional foods are newly emerged candidates for the uprooting of MDR strains and restoring dysbiosis and resilience. Probiotic nutrition is thought to diminish gut colonization from pathobionts. Yet only a few studies have explored the effects of antibiotics use on the reservoir of AR genes and the demanding time for return to normal by gut microbiota-targeted strategies. Regular administration of probiotic bacteria has recently been linked to restoration of the gut ecosystem and decrease of the gut resistome and AR genes carriers. This review summarizes the latest information about the intestinal resistome and the intriguing methods of fighting against AMR through probiotic-based methods and gut microbial shifts that have been proposed. This study contains some key messages: (1) AMR currently poses a lethal threat to global health, and it is pivotal for the scientific community to do its utmost in fighting against it; (2) human gut microbiome research, within the last decade especially, seems to be preoccupied with the interface of numerous diseases and identifying a potential target for a variety of interventions; (3) the gut resistome, comprised of AR genesis, presents very early on in life and is prone to shifts due to the use of antibiotics or dietary supplements; and (4) future strategies involving functional foods seem promising for the battle against AMR through intestinal resistome diminution.

Intrapartum beta-lactam antibiotics for preventing group B streptococcal early-onset disease: can we abandon the concept of 'inadequate' intrapartum antibiotic prophylaxis?

Introduction: Neonatal sepsis remains a serious and potentially fatal illness. Intrapartum antibiotic prophylaxis (IAP) prevents group B streptococcal (GBS) early-onset sepsis. The optimal duration of IAP (adequate IAP) to reduce vertical transmission of GBS has been debated. Understanding the mechanism of action of IAP may help in minimizing neonatal evaluation and unnecessary antibiotic use.Areas covered: In recent years, several studies on pharmacokinetics and clinical use of IAP have been published. Although penicillin and ampicillin are the most preferred antibiotics, the clinical efficacy of non-beta-lactam antibiotics, including clindamycin and vancomycin, used in cases of penicillin anaphylaxis-associated allergy, remains debatable. This is a narrative review of the literature regarding the impact of 'inadequate' IAP on the clinical management of women and newborns.Expert opinion: Recent evidence suggests that 'inadequate' IAP with beta-lactams is more effective in preventing vertical transmission of GBS than previously thought. Newborns exposed to intrapartum beta-lactams and who are asymptomatic at birth are likely uninfected, irrespective of IAP duration before delivery. Hence, we may abandon the concept of 'inadequate' IAP with beta-lactams in early-onset GBS sepsis, relying primarily on clinical signs observed at birth for managing IAP-exposed neonates.

Relationship Between Mutans Streptococci and Lactobacilli in the Oral Cavity and Intestine of Obese and Eutrophic Children With Early Childhood Caries-Preliminary Findings of a Cross-Sectional Study

This brief communication assessed whether there was any relationship between the counts of lactobacilli (LB) and mutans streptococci (MS) in the oral cavity and intestine of obese and eutrophic children with early childhood caries (ECC). Seventy-eight preschoolers were assigned into the following groups: 1. obese children with ECC (OECC), 2. eutrophic children with ECC (EECC), 3. obese caries-free children (OCF), and 4. eutrophic caries-free children (ECF). The diagnosis of obesity and ECC was based on the World Health Organization criteria. Dental plaque and fecal samples were collected to assess the counts of MS and LB using selective media. Data were evaluated by Poisson regression analysis, Wilcoxon test, and Sign test. Microbial indicators of ECC in obese children were MS counts in the intestine [rate ratio (RR): 4.38] and presence of LB in the oral cavity (RR: 2.12). The indicators in eutrophic children were MS levels and the presence of LB, both in the oral cavity (RR: 6.35/1.50) and intestine (RR: 2.35/2.38) (p < 0.05). The comparison between MS levels in the mouth and in the intestine revealed significant differences only in the ECF group (p = 0.04). Regarding LB presence in the mouth vs. in the intestine, except for the OCF group (p = 0.03), no other statistical differences were found. Our preliminary findings highlighted that the levels of MS and the presence of LB in the oral cavity, as well as in the lower gastrointestinal tract were associated with ECC. Moreover, obesity was found to influence this relationship.

The microbiota composition of the offspring of patients with gestational diabetes mellitus (GDM)

The microbiota composition of the offspring of women with gestational diabetes mellitus (GDM), a common pregnancy complication, is still little known. We investigated whether the GDM offspring gut microbiota composition is associated with the maternal nutritional habits, metabolic variables or pregnancy outcomes. Furthermore, we compared the GDM offspring microbiota to the microbiota of normoglycemic-mother offspring. Fecal samples of 29 GDM infants were collected during the first week of life and assessed by 16S amplicon-based sequencing. The offspring's microbiota showed significantly lower α-diversity than the corresponding mothers. Earlier maternal nutritional habits were more strongly associated with the offspring microbiota (maternal oligosaccharide positively with infant Ruminococcus, maternal saturated fat intake inversely with infant Rikenellaceae and Ruminococcus) than last-trimester maternal habits. Principal coordinate analysis showed a separation of the infant microbiota according to the type of feeding (breastfeeding vs formula-feeding), displaying in breast-fed infants a higher abundance of Bifidobacterium. A few Bacteroides and Blautia oligotypes were shared by the GDM mothers and their offspring, suggesting a maternal microbial imprinting. Finally, GDM infants showed higher relative abundance of pro-inflammatory taxa than infants from healthy women. In conclusion, many maternal conditions impact on the microbiota composition of GDM offspring whose microbiota showed increased abundance of pro-inflammatory taxa.

Developmental and age-dependent plasticity of GABAA receptors in the mouse colon: Implications in colonic motility and inflammation

Lifelong functional plasticity of the gastrointestinal (GI) tract is essential for health, yet the underlying molecular mechanisms are poorly understood. The enteric nervous system (ENS) regulates all aspects of the gut function, via a range of neurotransmitter pathways, one of which is the GABA-GABA_A receptor (GABA_AR) system. We have previously shown that GABA_A receptor subunits are differentially expressed within the ENS and are involved in regulating various GI functions. We have also shown that these receptors are involved in mediating stress-induced colonic inflammation. However, the expression and function of intestinal GABA_ARs, at different ages, is largely unexplored and was the focus of this study. Here we show that the impact of GABA_AR activation on colonic contractility changes from early postnatal period through to late adulthood, in an age-dependant manner. We also show that the highest levels of expression for all GABA_AR subunits is evident at postnatal day (P) 10 apart from the α3 subunit which increased with age. This increase in the α3 subunit expression in late adulthood (18 months old) is accompanied by an increase in the expression of inflammatory markers within the mouse colon. Finally, we demonstrate that the deletion of the α3 subunit prevents the increase in the expression of colonic inflammatory markers associated with healthy ageing. Collectively, the data provide the first demonstration of the molecular and functional plasticity of the GI GABA_AR system over the course of a lifetime, and its possible role in mediating the age-induced colonic inflammation associated with healthy ageing.

Modulation of Nerve Cell Differentiation: Role of Polyphenols and of Contactin Family Components

In this study the mechanisms are explored, which modulate expression and function of cell surface adhesive glycoproteins of the Immunoglobulin Supergene Family (IgSF), and in particular of its Contactin subset, during neuronal precursor developmental events. In this context, a specific topic concerns the significance of the expression profile of such molecules and their ability to modulate signaling pathways activated through nutraceuticals, in particular polyphenols, administration. Both in vitro and in vivo approaches are chosen. As for the former, by using as a model the human SH-SY5Y neuroblastoma line, the effects of grape seed polyphenols are evaluated on proliferation and commitment/differentiation events along the neuronal lineage. In SH-SY5Y cell cultures, polyphenols were found to counteract precursor proliferation while promoting their differentiation, as deduced by studying their developmental parameters through the expression of cell cycle and neuronal commitment/differentiation markers as well as by measuring neurite growth. In such cultures, Cyclin E expression and BrdU incorporation were downregulated, indicating reduced precursor proliferation while increased neuronal differentiation was inferred from upregulation of cell cycle exit (p27^–Kip) and neuronal commitment (NeuN) markers as well as by measuring neurite length through morphometric analysis. The polyphenol effects on developmental parameters were also explored in vivo, in cerebellar cortex, by using as a model the TAG/F3 transgenic line, which undergoes delayed neural development as a consequence of Contactin1 adhesive glycoprotein upregulation and premature expression under control of the Contactin2 gene (Cntn-2) promoter. In this transgenic line, a Notch pathway activation is known to occur and polyphenol treatment was found to counteract such an effect, demonstrated through downregulation of the Hes-1 transcription factor. Polyphenols also downregulated the expression of adhesive glycoproteins of the Contactin family themselves, demonstrated for both Contactin1 and Contactin2, indicating the involvement of changes in the expression of the underlying genes in the observed phenotype. These data support the hypothesis that the complex control exerted by polyphenols on neural development involves modulation of expression and function of the genes encoding cell adhesion molecules of the Contactin family and of the associated signaling pathways, indicating potential mechanisms whereby such compounds may control neurogenesis.

Patterned progression of gut microbiota associated with necrotizing enterocolitis and late onset sepsis in preterm infants: a prospective study in a Chinese neonatal intensive care unit

Necrotizing enterocolitis (NEC) and late-onset sepsis (LOS) are two common premature birth complications with high morbidity and mortality. Recent studies in Europe and America have linked gut microbiota dysbiosis to their etiology. However, similar studies in Asian populations remain scant. In this pilot study, we profiled gut microbiota of 24 Chinese preterm infants from birth till death or discharge from NICU. Four of them developed NEC and three developed LOS. Unexpectedly, we detected highly-diversified microbiota with similar compositions in all patients shortly after birth. However, as patients aged, the microbial diversities in case groups differed significantly from that of the control group. These differences emerged after the third day of life and persisted throughout the course of both NEC and LOS. Using a Zero-Inflated Beta Regression Model with Random Effects (ZIBR), we detected higher Bacillus (p = 0.032) and Solibacillus (p = 0.047) before the onset of NEC and LOS. During NEC progression, Enterococcus, Streptococcus and Peptoclostridium were the dominant genera while during LOS progression; Klebsiella was the only dominant genus that was also detected by the diagnostic hemoculture. These results warrant further studies to identify causative microbial patterns and underlying mechanisms.