Prostaglandin E Regulates Bipotent Monocyte-Dendritic Progenitor Cell Lineage-Commitment.

The factors/mechanisms regulating multipotent or bipotent hematopoietic progenitor cells lineage-commitment are not well understood. In this study, we found that prostaglandin E (PGE) is a crucial physiological regulator of lineage choice for the bipotential monocyte-dendritic progenitor cell (MDP). Inhibition of endogenous PGE biosynthesis in mice by the dual cyclooxygenase inhibitor, indomethacin, enhances bone marrow and spleen monocyte (MO) differentiation and reduces dendritic cell (DC) differentiation. Ex vivo treatment of purified MDP with indomethacin preferentially increases MO development at the expense of DC generation, whereas addition of exogenous PGE reverses the indomethacin-mediated alteration in MDP differentiation potential. Treatment of MDP with selective EP receptor agonists demonstrated that EP1 signaling promotes MDP differentiation into DC at the expense of MO generation. Conversely, EP1 receptor knockout mice showed reduced DC and increased MO differentiation. Mechanistic studies revealed that PGE increases expression of the tyrosine kinase receptor Flt3 on MDP and increases the DC-lineage-related transcription factor PU.1, while reducing expression of M-CSFR and the MO-lineage-related transcription factor MafB. These data indicate that PGE-EP1 signaling plays a critical role in MDP lineage commitment and DC and MO differentiation.