近日，美国加州大学旧金山分校S. V. Lynch及其团队发现，妊娠时期胎儿肠道的活菌定殖高度受限。相关论文于2020年2月24日在线发表在《自然—医学》杂志上。

Title: Viable bacterial colonization is highly limited in the human intestine in utero

Author: E. Rackaityte, J. Halkias, E. M. Fukui, V. F. Mendoza, C. Hayzelden, E. D. Crawford, K. E. Fujimura, T. D. Burt, S. V. Lynch

Issue&Volume: 2020-02-24

Abstract: Mucosal immunity develops in the human fetal intestine by 11–14 weeks of gestation, yet whether viable microbes exist in utero and interact with the intestinal immune system is unknown. Bacteria-like morphology was identified in pockets of human fetal meconium at mid-gestation by scanning electron microscopy (n=4), and a sparse bacterial signal was detected by 16S rRNA sequencing (n=40 of 50) compared to environmental controls (n=87). Eighteen taxa were enriched in fetal meconium, with Micrococcaceae (n=9) and Lactobacillus (n=6) the most abundant. Fetal intestines dominated by Micrococcaceae exhibited distinct patterns of T cell composition and epithelial transcription. Fetal Micrococcus luteus, isolated only in the presence of monocytes, grew on placental hormones, remained viable within antigen presenting cells, limited inflammation ex vivo and possessed genomic features linked with survival in the fetus. Thus, viable bacteria are highly limited in the fetal intestine at mid-gestation, although strains with immunomodulatory capacity are detected in subsets of specimens.

DOI: 10.1038/s41591-020-0761-3

Source: https://www.nature.com/articles/s41591-020-0761-3