Fibroblastic reticular cells (FRCs) are a population of stromal cells found in lymph nodes that are crucial for the maintenance of immunological niches and the support of immune responses during inflammation. The roles of FRCs in the development and function of lymphoid tissues are hot topics in both immunology and stromal biology. However, the molecular regulators of fibroblast–immune crosstalk are not well defined. In this preprint (not peer reviewed), Makris et al. use a combination of transcriptomic and histological approaches to show that podoplanin (PDPN) is a key regulator of FRC identity and function.

PDPN is a cell-surface marker commonly used to identify FRCs in lymph nodes. Loss of this glycoprotein during embryonic development impedes lymph node development. The authors showed that loss of PDPN specifically in FRCs, through use of a PdgfraCreERT2 × Pdpnflox/flox (PdgfraΔPDPN) mouse line, resulted in aberrant extracellular matrix production, which confirms previous work suggesting that PDPN is important for lymph node structure.