Immune cells direct epithelial maturation during early human lung development

The adult human lung harbours a significant proportion of immune cells, which are known to play a crucial role in both normal lung homeostasis and pathogenesis. In this work, we collected CD45-enriched human lung cells from 6 to 22 week post conception (pcw) and built a single-cell transcriptome and proteome atlas. We showed a biphasic mode of immune cell development peaking at 8-9 and 20 pcw respectively. The developing immune cells potentially modulate the maturation of the epithelium through signalling molecules. We demonstrated using the lung organoid model that IL-1ß was required for epithelium differentiation. Overall, we provide a resource for the community of lung biologists and immunologists and provide insights on the interaction between the innate immune system and epithelium during fetal development.