Role of Interferon-γ-Producing Th1 Cells in a Murine Model of Type I Interferon-Independent Autoinflammation Resulting From DNase II Deficiency

Abstract

Objective: Patients with hypomorphic mutations in DNase II develop a severe and debilitating autoinflammatory disease. This study was undertaken to compare the disease parameters in these patients to those in a murine model of DNase II deficiency, and to evaluate the role of specific nucleic acid sensors and identify the cell types responsible for driving the autoinflammatory response.

Methods: To avoid embryonic death, Dnase2^-/- mice were intercrossed with mice that lacked the type I interferon (IFN) receptor (Ifnar^-/- ). The hematologic changes and immune status of these mice were evaluated using complete blood cell counts, flow cytometry, serum cytokine enzyme-linked immunosorbent assays, and liver histology. Effector cell activity was determined by transferring T cells from Dnase2^-/- × Ifnar^-/- double-knockout (DKO) mice into Rag1^-/- mice, and 4 weeks after cell transfer, induced changes were assessed in the recipient mice.

Results: In Dnase2^-/- × Ifnar^-/- DKO mice, many of the disease features found in DNase II-deficient patients were recapitulated, including cytopenia, extramedullary hematopoiesis, and liver fibrosis. Dnase2^+/+ × Rag1^-/- mice (n > 22) developed a hematologic disorder that was attributed to the transfer of an unusual IFNγ-producing T cell subset from the spleens of donor Dnase2^-/- × Ifnar^-/- DKO mice. Autoinflammation in this murine model did not depend on the stimulator of IFN genes (STING) pathway but was highly dependent on the chaperone protein Unc93B1.

Conclusion: Dnase2^-/- × Ifnar^-/- DKO mice may be a valid model for exploring the innate and adaptive immune mechanisms responsible for the autoinflammation similar to that seen in DNASE2-hypomorphic patients. In this murine model, IFNγ is required for T cell activation and the development of clinical manifestations. The role of IFNγ in DNASE2-deficient patient populations remains to be determined, but the ability of Dnase2^-/- mouse T cells to transfer disease to Rag1^-/- mice suggests that T cells may be a relevant therapeutic target in patients with IFN-related systemic autoinflammatory diseases.