The Maternal–Fetal Gut Microbiota Axis: Physiological Changes, Dietary Influence, and Modulation Possibilities

Abstract

The prenatal period and the first years of life have a significant impact on the health issues and life quality of an individual. The appropriate development of the immune system and the central nervous system are thought to be major critical determining events. In parallel to these, establishing an early intestinal microbiota community is another important factor for future well-being interfering with prenatal and postnatal developmental processes. This review aims at summarizing the main characteristics of maternal gut microbiota and its possible transmission to the offspring, thereby affecting fetal and/or neonatal development and health. Since maternal dietary factors are potential modulators of the maternal–fetal microbiota axis, we will outline current knowledge on the impact of certain diets, nutritional factors, and nutritional modulators during pregnancy on offspring’s microbiota and health.

The Entero-Mammary Pathway and Perinatal Transmission of Gut Microbiota and SARS-CoV-2

“…Further, in our work, three representative taxa of the phylum Firmicutes ( Lachnospirraceae , Colidextribacter , Flavonifractor ) were positively correlated with the presence of SARS-CoV-2 in MRS, and Faecalibacterium UBA1819 was positively correlated with SARS-CoV-2 detection in nasopharyngeal swabs by Spearman analysis. Interestingly, Colidexibacter massiliensis species have been isolated from the human colon of obese patients [ 32 ], and an increase in the abundance of members of the families Ruminococacceae , Lachnospiraceae, and Enterocacaceae has been linked to the diagnosis of gestational diabetes mellitus (GDM) [ 33 , 34 ]. On the other hand, Flavonifractor plautii , a bacterium involved in the degradation of anticancer flavonoids, has been found in patients with colorectal cancer [ 35 ].…”

Inflammatory Signatures of Maternal Obesity as Risk Factors for Neurodevelopmental Disorders: Role of Maternal Microbiota and Nutritional Intervention Strategies

“…In particular, excessive BMI during pregnancy has been related to reduced alpha diversity and higher abundance of bacterial species such as Staphylococcus aureus , Escherichia coli , and in general of Proteobacteria, and lower counts of species such as Bifidobacterium longum and Bacteroides fragilis [ 75 , 76 ]. This abundance in Proteobacteria may lead to pro-inflammatory changes enhancing maternal gut permeability favoring the translocation of maternal intestinal bacteria to the fetus, eventually priming immune activation through the toll-like receptors (TLRs) [ 77 , 78 ]. Besides alive bacteria, many microbiota-derived microbial compounds such as LPS or flagellin may increase the production of pro-inflammatory cytokines (e.g., TNF-alpha, IL-6 and IL-1beta) activating the TLRs and affecting fetal development [ 78 , 79 ].…”

“…This abundance in Proteobacteria may lead to pro-inflammatory changes enhancing maternal gut permeability favoring the translocation of maternal intestinal bacteria to the fetus, eventually priming immune activation through the toll-like receptors (TLRs) [ 77 , 78 ]. Besides alive bacteria, many microbiota-derived microbial compounds such as LPS or flagellin may increase the production of pro-inflammatory cytokines (e.g., TNF-alpha, IL-6 and IL-1beta) activating the TLRs and affecting fetal development [ 78 , 79 ]. To this regard, studies performed in non-human primates and rodents have provided evidence that microbial maternal dysbiosis, deriving from HFD consumption, a model of maternal obesity, is associated with increased inflammation and is accompanied by elevated anxiety levels and reduced social behavior in the offspring [ 40 , 80 ].…”

“…SCFAs concentrations increase significantly in maternal gut throughout pregnancy and recent preclinical studies have provided evidence for their beneficial effects on embryonal development acting as signaling molecules through G-protein receptors (GPR) GPR41 and GPR43 [ 84 , 85 ]. In particular, SCFAs have a major impact on fetal immune system development affecting cytokine synthesis and anti-inflammatory activities (see [ 78 ] and references therein).…”

“…A further—though debated—mechanism through which changes in microbiota might contribute to modulate fetal brain development refers to the hypothesis of an intrauterine origin of fetal microbiota [ 77 , 78 ]. Given the importance of the microbiota-gut-brain axis for (neuro)development, gastrointestinal tract colonization represents indeed a milestone [ 89 ].…”