DNGR1-mediated deletion of A20/Tnfaip3 in dendritic cells alters T and B-cell homeostasis and promotes autoimmune liver pathology

Abstract

Dendritic cells (DCs) are central regulators of tolerance versus immunity. The outcome depends amongst others on DC subset and activation status. Whereas CD11b⁺ type 2 conventional DCs (cDC2s) initiate proinflammatory helper T (Th)-cell responses, CD103⁺ cDC1s are crucial for regulatory T-cell (Treg) induction and CD8⁺ T-cell activation. DC activation is controlled by the transcription factor NF-κB. Ablation of A20/Tnfaip3, a critical regulator of NF-κB activation, in DCs leads to constitutive DC activation and development of systemic autoimmunity. We hypothesized that the activation status of cDCs controls the development of autoimmunity. To target cDCs, DNGR1(Clec9a)-cre-mediated excision of A20/Tnfaip3 was used through generation of Tnfaip3^fl/flxClec9a^+/cre (Tnfaip3^DNGR1-KO) mice. Immune cell activation was evaluated at 31-weeks of age. We found that DNGR1-cre-mediated deletion of A20/Tnfaip3 resulted in liver pathology characterized by inflammatory infiltrates adjacent to the portal triads. Both cDC subsets as well as monocyte-derived DCs (moDCs) in Tnfaip3^DNGR1-KO livers harbored an activated phenotype. Specifically, the costimulatory molecule CD40 in liver cDCs and moDCs was regulated by A20/Tnfaip3 expression. Livers from Tnfaip3^DNGR1-KO mice had augmented proportions of Th1, Th17, Treg, and follicular Th (Tfh)-cells compared to control mice, accompanied by an increase in IgA-producing plasma cells. Serum IgA from Tnfaip3^DNGR1-KO mice recognized self-proteins, specifically cytoplasmic proteins in liver periportal regions. These data show that enhanced activation of cDCs and moDCs, due to A20/Tnfaip3 ablation, promotes the development of organ-specific autoimmunity but not systemic autoimmunity. This model could be useful to examine the pathobiological processes contributing to autoimmune liver diseases.