Prostaglandin D2 (
PGD2), an
eicosanoid with both pro- and anti-inflammatory properties, is the most abundantly expressed
prostaglandin in the brain. Here we show that
PGD2 signaling through the D-
prostanoid receptor 1 (DP1) receptor is necessary for optimal microglia/macrophage activation and IFN expression after
infection with a neurotropic coronavirus. Genome-wide expression analyses indicated that
PGD2/DP1 signaling is required for up-regulation of a putative
inflammasome inhibitor, PYDC3, in CD11b+ cells in the CNS of infected mice. Our results also demonstrated that, in addition to
PGD2/DP1 signaling, type 1 IFN (IFN-I) signaling is required for PYDC3 expression. In the absence of Pydc3 up-regulation, IL-1β expression and, subsequently, mortality were increased in infected DP1-/- mice. Notably, survival was enhanced by
IL1 receptor blockade, indicating that the effects of the absence of DP1 signaling on clinical outcomes were mediated, at least in part, by
inflammasomes. Using bone marrow-derived macrophages in vitro, we confirmed that PYDC3 expression is dependent upon DP1 signaling and that IFN priming is critical for PYDC3 up-regulation. In addition, Pydc3 silencing or overexpression augmented or diminished IL-1β secretion, respectively. Furthermore, DP1 signaling in human macrophages also resulted in the up-regulation of a putative functional analog, POP3, suggesting that
PGD2 similarly modulates
inflammasomes in human cells. These findings demonstrate a previously undescribed role for
prostaglandin signaling in preventing excessive
inflammasome activation and, together with previously published results, suggest that
eicosanoids and
inflammasomes are reciprocally regulated.