Prostaglandin D₂ amplifies lupus disease through basophil accumulation in lymphoid organs

In systemic lupus erythematosus (SLE), autoantibody production can lead to kidney damage and failure, known as lupus nephritis. Basophils amplify the synthesis of autoantibodies by accumulating in secondary lymphoid organs. Here, we show a role for prostaglandin D₂ (PGD₂) in the pathophysiology of SLE. Patients with SLE have increased expression of PGD₂ receptors (PTGDR) on blood basophils and increased concentration of PGD₂ metabolites in plasma. Through an autocrine mechanism dependent on both PTGDRs, PGD₂ induces the externalization of CXCR4 on basophils, both in humans and mice, driving accumulation in secondary lymphoid organs. Although PGD₂ can accelerate basophil-dependent disease, antagonizing PTGDRs in mice reduces lupus-like disease in spontaneous and induced mouse models. Our study identifies the PGD₂/PTGDR axis as a ready-to-use therapeutic modality in SLE.