RESUMEN
The human fetal immune system begins to develop early during gestation; however, factors responsible for fetal immune-priming remain elusive. We explored potential exposure to microbial agents in utero and their contribution toward activation of memory T cells in fetal tissues. We profiled microbes across fetal organs using 16S rRNA gene sequencing and detected low but consistent microbial signal in fetal gut, skin, placenta, and lungs in the 2nd trimester of gestation. We identified several live bacterial strains including Staphylococcus and Lactobacillus in fetal tissues, which induced in vitro activation of memory T cells in fetal mesenteric lymph node, supporting the role of microbial exposure in fetal immune-priming. Finally, using SEM and RNA-ISH, we visualized discrete localization of bacteria-like structures and eubacterial-RNA within 14th weeks fetal gut lumen. These findings indicate selective presence of live microbes in fetal organs during the 2nd trimester of gestation and have broader implications toward the establishment of immune competency and priming before birth.
Asunto(s)
Bacterias/metabolismo , Desarrollo Embrionario , Feto/citología , Feto/microbiología , Leucocitos/citología , Adulto , Bacterias/genética , Bacterias/ultraestructura , Proliferación Celular , Células Dendríticas/metabolismo , Femenino , Feto/ultraestructura , Tracto Gastrointestinal/embriología , Tracto Gastrointestinal/ultraestructura , Humanos , Memoria Inmunológica , Activación de Linfocitos/inmunología , Viabilidad Microbiana , Embarazo , Segundo Trimestre del Embarazo , ARN Bacteriano/genética , ARN Ribosómico 16S/genética , Reproducibilidad de los Resultados , Linfocitos T/citologíaRESUMEN
We employed scRNA sequencing to extensively characterize the cellular landscape of human liver from development to disease. Analysis of â¼212,000 cells representing human fetal, hepatocellular carcinoma (HCC), and mouse liver revealed remarkable fetal-like reprogramming of the tumor microenvironment. Specifically, the HCC ecosystem displayed features reminiscent of fetal development, including re-emergence of fetal-associated endothelial cells (PLVAP/VEGFR2) and fetal-like (FOLR2) tumor-associated macrophages. In a cross-species comparative analysis, we discovered remarkable similarity between mouse embryonic, fetal-liver, and tumor macrophages. Spatial transcriptomics further revealed a shared onco-fetal ecosystem between fetal liver and HCC. Furthermore, gene regulatory analysis, spatial transcriptomics, and in vitro functional assays implicated VEGF and NOTCH signaling in maintaining onco-fetal ecosystem. Taken together, we report a shared immunosuppressive onco-fetal ecosystem in fetal liver and HCC. Our results unravel a previously unexplored onco-fetal reprogramming of the tumor ecosystem, provide novel targets for therapeutic interventions in HCC, and open avenues for identifying similar paradigms in other cancers and disease.