Notch is a pleiotropic signaling family that has been implicated in pathogenesis of allergic airway diseases; however， the distinct function of individual Notch ligands remains elusive. We investigated whether Notch ligands， Jagged1 and DLL4， exert differential effects in OVA-induced allergic asthma. We found that whilst Jagged1 inhibition mitigated Th2-dominated airway inflammation， blockage of DLL4 aggravated the Th2-mediated asthma phenotypes. Additionally， Jagged1 signaling blockage enhanced IL-17 production and neutrophilic airway infiltration. In vitro， exogenous Jagged1 induced Th2-skewed responses， whereas augmented DLL4 signaling displayed a dual role by promoting expansion of both Tregs ... More
Notch is a pleiotropic signaling family that has been implicated in pathogenesis of allergic airway diseases; however， the distinct function of individual Notch ligands remains elusive. We investigated whether Notch ligands， Jagged1 and DLL4， exert differential effects in OVA-induced allergic asthma. We found that whilst Jagged1 inhibition mitigated Th2-dominated airway inflammation， blockage of DLL4 aggravated the Th2-mediated asthma phenotypes. Additionally， Jagged1 signaling blockage enhanced IL-17 production and neutrophilic airway infiltration. In vitro， exogenous Jagged1 induced Th2-skewed responses， whereas augmented DLL4 signaling displayed a dual role by promoting expansion of both Tregs and Th17. In vivo， DLL4 blockage impaired Treg differentiation which plausibly resulted in exaggerated asthma phenotypes. On the contrary， administration of DLL4-expressing antigen-presenting cells promoted endogenous Treg expansion and ameliorated the allergic responses. Therefore， whilst Jagged1 induces Th2-skewed inflammation， DLL4 elicits an essential self-regulatory mechanism via Treg-mediated pathway that counterbalances Jagged1-induced Th2 responses and facilitates resolution of the airway inflammation to restore homeostasis. These findings uncover a disparate function of Jagged1 and DLL4 in allergic airway diseases， hinting feasibility of Notch ligand-specific targeting in therapy of allergic airway diseases.
