TNF-α-induced protein 3 levels in lung dendritic cells instruct TH2 or TH17 cell differentiation in eosinophilic or neutrophilic asthma.

Background: It is currently unknown why allergen exposure or environmental triggers in patients with mild-to-moderate asthma result in TH2-mediated eosinophilic inflammation, whereas patients with severe asthma often present with TH17-mediated neutrophilic inflammation. The activation state of dendritic cells (DCs) is crucial for both TH2 and TH17 cell differentiation and is mediated through nuclear factor κB activation. Ablation of TNF-α-induced protein 3 (TNFAIP3), one of the crucial negative regulators of nuclear factor κB activation in myeloid cells and DCs, was shown to control DC activation.

Objective: In this study we investigated the precise role of TNFAIP3 in myeloid cells for the development of TH2- and TH17-cell mediated asthma.

Methods: We exposed mice with conditional deletion of the Tnfaip3 gene in either myeloid cells (by using the lysozyme M [LysM] promotor) or specifically in DCs (by using the Cd11c promotor) to acute and chronic house dust mite (HDM)-driven asthma models.

Results: We demonstrated that reduced Tnfaip3 gene expression in DCs in either Tnfaip3CD11c or Tnfaip3LysM mice dose-dependently controlled development of TH17-mediated neutrophilic severe asthma in both acute and chronic HDM-driven models, whereas wild-type mice had a purely TH2-mediated eosinophilic inflammation. TNFAIP3-deficient DCs induced HDM-specific TH17 cell differentiation through increased expression of the TH17-instructing cytokines IL-1β, IL-6, and IL-23, whereas HDM-specific TH2 cell differentiation was hampered by increased IL-12 and IL-6 production.

Conclusions: These data show that the extent of TNFAIP3 expression in DCs controls TH2/TH17 cell differentiation. This implies that reducing DC activation could be a new pharmacologic intervention to treat patients with severe asthma who present with TH17-mediated neutrophilic inflammation.