Project description:“Dysbiosis" of the maternal gut microbiome, in response to environmental challenges such as infection, altered diet and stress during pregnancy, has been increasingly associated with abnormalities in offspring brain function and behavior. However, whether the maternal gut microbiome regulates neurodevelopment in the absence of environmental challenge remains unclear. In addition, whether the maternal microbiome exerts such influences during critical periods of embryonic brain development is poorly understood. Here we investigate how depletion, and selective reconstitution, of the maternal gut microbiome influences fetal neurodevelopment in mice. Embryos from antibiotic-treated and germ-free dams exhibit widespread transcriptomic alterations in the fetal brain relative to conventionally-colonized controls, with reduced expression of several genes involved in axonogenesis. In addition, embryos from microbiome-depleted mothers exhibit deficient thalamocortical axons and impaired thalamic axon outgrowth in response to cell-extrinsic guidance cues and growth factors. Consistent with the importance of fetal thalamocortical axonogenesis for shaping neural circuits for sensory processing, restricted depletion of the maternal microbiome from pre-conception through mid-gestation yields offspring that exhibit tactile hyposensitivity in select sensorimotor behavioral tasks. Gnotobiotic colonization of antibiotic-treated dams with a limited consortium of spore-forming bacteria indigenous to the gut microbiome prevents abnormalities in fetal brain gene expression, fetal thalamocortical axonogenesis and adult tactile sensory behavior associated with maternal microbiome depletion. Metabolomic profiling reveals that the maternal microbiota regulates levels of numerous small molecules in the maternal serum as well as the brains of fetal offspring. Select microbiota-dependent metabolites – trimethylamine N-oxide, 5-aminovalerate, imidazole propionate, and hippurate – sufficiently promote axon outgrowth from fetal thalamic explants. Moreover, maternal supplementation with the metabolites during early gestation abrogates deficiencies in fetal thalamocortical axons and prevents abnormalities in tactile sensory behavior in offspring from microbiome-depleted dams. Altogether, these findings reveal that the maternal gut microbiome promotes fetal thalamocortical axonogenesis and select tactile sensory behaviors in mice, likely by signaling of microbially modulated metabolites to neurons in the developing brain.

Project description:Zika virus (ZIKV) has emerged as a significant public health concern due to its association with severe neurological outcomes in infants, including microcephaly and congenital Zika syndrome (CZS). However, while the majority of ZIKV infections during pregnancy do not result in CZS, the potential long-term neurological effects of mild or inapparent maternal infections remain poorly understood. In this study, we adapted a model of maternal ZIKV infection in human STAT2 knock-in (hSTAT2) mice to investigate the effects of ZIKV infection during mid-gestation, aiming to mirror typical asymptomatic infections as they occur in humans. We found that maternal ZIKV infection at mid-gestation leads to vertical transmission without causing overt developmental deficits or clinical signs in dams or offspring. Despite the absence of immediate clinical signs, transcriptomic analyses revealed significant changes in the developing fetal brain, particularly in genes related to synaptic function and neuronal development. These molecular alterations were associated with increased synaptic density in the hippocampus and heightened susceptibility to chemically induced seizures in offspring, suggesting subtle yet significant long-term neurological consequences. Using motion sequencing (MoSeq), an unsupervised machine learning approach that profiles naturalistic motor behavior, we also identified persistent, sex-biased alterations in the content and structure of spontaneous behavior in offspring exposed to maternal ZIKV infection. Our findings highlight that even mild maternal ZIKV infections can disrupt fetal neurodevelopment, underscoring the need for enhanced monitoring and public health measures for children exposed to ZIKV in utero but who do not experience severe developmental alterations at birth. Additionally, our study provides a valuable animal model and comprehensive, cell type-specific transcriptomic datasets that will facilitate new lines of investigation into the impact of inapparent maternal ZIKV infections on fetal and childhood brain development.

Project description:The microorganisms colonizing the gastrointestinal tract of animals, collectively referred to as the gut microbiome, affect numerous host behaviors dependent on the central nervous system (CNS). Studies comparing germ-free mice to normally colonized mice have demonstrated influences of the microbiome on anxiety-related behaviors, voluntary activity, and gene expression in the CNS. Additionally, there is epidemiologic evidence supporting an intergenerational influence of the maternal microbiome on neurodevelopment of offspring and behavior later in life. There is limited experimental evidence however directly linking the maternal microbiome to long-term neurodevelopmental outcomes, or knowledge regarding mechanisms responsible for such effects. Here we show that that the maternal microbiome has a dominant influence on several offspring phenotypes including anxiety-related behavior, voluntary activity, and body weight. Adverse outcomes in offspring were associated with features of the maternal microbiome including bile salt hydrolase (Bsh) expression, abundance of certain bile acids, and hepatic expression of S1pr2. In cross-foster experiments, offspring resembled their birth dam phenotypically, despite faithful colonization in the postnatal period with the surrogate dam microbiome. Genome-wide methylation analysis of hippocampal DNA identified microbiome-associated differences in methylation of 196 loci in total, 176 of which were imprinted by the maternal microbiome. Further, single-cell transcriptional analysis revealed accompanying differences in expression of several differentially methylated genes within certain hippocampal cell clusters, and vascular expression of genes associated with bile acid transport. Inferred cell-to-cell communication in the hippocampus based on coordinated ligand-receptor expression revealed differences in expression of neuropeptides associated with satiety. Collectively, these data provide proof-of-principle that the maternal gut microbiome has a dominant influence on the neurodevelopment underlying certain offspring behaviors and activities, and selectively affects genome methylation and gene expression in the offspring CNS in conjunction with that neurodevelopment.

			Action	DRS
	ERR9970960.fastq.gz	Fastqsanger.gz
	ERR9970951.fastq.gz	Fastqsanger.gz
	ERR9970952.fastq.gz	Fastqsanger.gz
	ERR9970953.fastq.gz	Fastqsanger.gz
	ERR9970954.fastq.gz	Fastqsanger.gz

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