S1PR1 and influenza: In influenza, administration of an agonist to the lipid metabolite sphingosine 1 phosphate receptor (S1P1R) expressed on pDCs was shown to suppress IFN-I signaling in mice and human cells and blunt proinflammatory responses during influenza infection in mice that showed improved survival (Teijaro et al.2011; Walsh et al.2011; Teijaro et al.2016).