The prenatal maternal microbiome, including the gut microbiota, has been suggested to influence the incidence of allergies in offspring. Moreover, epidermal barrier dysfunction in early infancy has been attributed to the development of subsequent allergies. We hypothesized that the prenatal microbiome may affect the gut microbiota, acting as an initial trigger to alter immune development in the foetus. The maternal microbial composition may be linked to the prevalence of dermatitis in early infancy (DEI) of the offspring, leading to subsequent allergic symptoms. This study was conducted as part of the Chiba Study of Mother and Child Health (C-MACH) birth cohort that was initiated in 2013; 434 healthy pregnant women at < 13 weeks of gestation were recruited. DEI was assessed for up to 4 months after birth, and allergic symptoms were determined in 10-month-old infants using questionnaires. Other information related to the maternal microbiome was obtained from questionnaires filled out during pregnancy. Stool samples were collected from pregnant women at 12 (n = 59) and 32 weeks (n = 58) of gestation, which were used for gut microbiota analysis using barcoded 16S rRNA gene sequencing. Symptoms of allergy, especially of inherited allergies, show a higher prevalence at 10 months after birth in the DEI group. DEI occurrence was negatively correlated with family size and cat ownership. The diversity of Proteobacteria at 12 weeks of gestation and the relative abundance of Actinobacteria at 32 weeks of gestation in maternal feces were lower at both time points of gestation in the DEI group. In addition, the diversity of Proteobacteria in prenatal feces was negatively correlated with family size at 12 weeks, and with dog ownership at both gestational time points. The composition of the maternal microbiome may influence the risk of allergies in offspring, even before birth. Furthermore, the diversity of Proteobacteria and the relative abundance of Actinobacteria in maternal feces were negatively associated with DEI, which may be associated with the risk of allergy development in infancy. This early trigger may be a good predictor of allergy development during infancy and childhood.

Erratum: Commensal microbe-derived butyrate induces the differentiation of colonic regulatory T cells

Bacterial cancer therapy (BCT) shows great promise for treatment of solid tumors, yet basic mechanisms of bacterial-induced tumor suppression remain undefined. Attenuated strains of Salmonella enterica serovar Typhimurium ( S Tm) have commonly been used in mouse models of BCT in xenograft and orthotopic transplant cancer models. We aimed to better understand the tumor epithelium–targeted mechanisms of BCT by using autochthonous mouse models of intestinal cancer and tumor organoid cultures to assess the effectiveness and consequences of oral treatment with aromatase A–deficient S Tm ( STm ^Δ aroA ). STm ^Δ aroA delivered by oral gavage significantly reduced tumor burden and tumor load in both a colitis-associated colorectal cancer (CAC) model and in a spontaneous Apc ^min/+ intestinal cancer model. STm ^Δ aroA colonization of tumors caused alterations in transcription of mRNAs associated with tumor stemness, epithelial-mesenchymal transition, and cell cycle. Metabolomic analysis of tumors demonstrated alteration in the metabolic environment of STm ^Δ aroA -treated tumors, suggesting that STm ^Δ aroA imposes metabolic competition on the tumor. Use of tumor organoid cultures in vitro recapitulated effects seen on tumor stemness, mesenchymal markers, and altered metabolome. Furthermore, live STm ^Δ aroA was required, demonstrating active mechanisms including metabolite usage. We have demonstrated that oral BCT is efficacious in autochthonous intestinal cancer models, that BCT imposes metabolic competition, and that BCT has direct effects on the tumor epithelium affecting tumor stem cells.