Low-density lipoprotein receptor–related protein 1 attenuates house dust mite–induced eosinophilic airway inflammation by suppressing dendritic cell–mediated adaptive immune responses

Low-density lipoprotein receptor–related protein 1 (LRP-1) is a scavenger receptor that regulates adaptive immunity and inflammation. LRP-1 is not known to modulate the pathogenesis of allergic asthma. We sought to assess whether LRP-1 expression by dendritic cells (DCs) modulates adaptive immune responses in patients with house dust mite (HDM)–induced airways disease. LRP-1 expression on peripheral blood DCs was quantified by using flow cytometry. The role of LRP-1 in modulating HDM-induced airways disease was assessed in mice with deletion of LRP-1 in CD11c + cells ( Lrp1 fl/fl ; CD11c -Cre) and by adoptive transfer of HDM-pulsed CD11b + DCs from Lrp1 fl/fl ; CD11c -Cre mice to wild-type (WT) mice. Human peripheral blood myeloid DC subsets from patients with eosinophilic asthma have lower LRP-1 expression than cells from healthy nonasthmatic subjects. Similarly, LRP-1 expression by CD11b + lung DCs was significantly reduced in HDM-challenged WT mice. HDM-challenged Lrp1 fl/fl ; CD11c-Cre mice have a phenotype of increased eosinophilic airway inflammation, allergic sensitization, T H 2 cytokine production, and mucous cell metaplasia. The adoptive transfer of HDM-pulsed LRP-1–deficient CD11b + DCs into WT mice generated a similar phenotype of enhanced eosinophilic inflammation and allergic sensitization. Furthermore, CD11b + DCs in the lungs of Lrp1 fl/fl ; CD11c -Cre mice have an increased ability to take up HDM antigen, whereas bone marrow–derived DCs display enhanced antigen presentation capabilities. This identifies a novel role for LRP-1 as a negative regulator of DC-mediated adaptive immune responses in the setting of HDM-induced eosinophilic airway inflammation. Furthermore, the reduced LRP-1 expression by circulating myeloid DCs in patients with eosinophilic asthma suggests a possible role for LRP-1 in modulating type 2–high asthma.