Phosphatase and tensin homolog (PTEN) in antigen-presenting cells controls Th17-mediated autoimmune arthritis

Introduction: Autoreactive T cells are a central element in many systemic autoimmune diseases. The generation of these pathogenic T cells is instructed by antigen-presenting cells (APCs). However, signaling pathways in APCs that drive autoimmune diseases, such as rheumatoid arthritis, are not understood. Methods: We measured phenotypic maturation, cytokine production and induction of T cell proliferation of APCs derived from wt mice and mice with a myeloid-specific deletion of PTEN (myeloid PTEN-/-) in vitro and in vivo. We induced collagen-induced arthritis (CIA) and K/BxN serum transfer arthritis in wt and myeloid-specific PTEN-/- mice. We measured the cellular composition of lymph nodes by flow cytometry and cytokines in serum and after ex vivo stimulation of T cells. Results: We show that myeloid-specific PTEN-/- mice are almost protected from CIA. Myeloid-specific deletion of PTEN leads to a significant reduction of cytokine expression pivotal for the induction of systemic autoimmunity such as interleukin (IL)-23 and IL-6, leading to a significant reduction of a Th17 type of immune response characterized by reduced production of IL-17 and IL-22. In contrast, myeloid-specific PTEN deficiency did not affect K/BxN serum transfer arthritis, which is independent of the adaptive immune system and solely depends on innate effector functions. Conclusions: These data demonstrate that the presence of PTEN in myeloid cells is required for the development of CIA. Deletion of PTEN in myeloid cells inhibits the development of autoimmune arthritis by preventing the generation of a pathogenic Th17 type of immune response.