Interferon-γ-Dependent Inhibition of B Cell Activation by Bone Marrow-Derived Mesenchymal Stem Cells in a Murine Model of Systemic Lupus Erythematosus

Objective. Bone marrow-derived mesenchymal stem cells (BM-MSCs) are multipotent cells characterized by immunomodulatory properties and are therefore considered a promising tool for the treatment of immune-mediated diseases. This study was undertaken to assess the influence of murine BM-MSCs on the activation of B cells in (NZB x NZW)F-1 mice as an animal model of systemic lupus erythematosus (SLE). Methods. We evaluated the in vitro effects of BM-MSCs on the proliferation and differentiation to plasma cells of splenic mature B cell subsets, namely follicular and marginal zone B cells isolated from (NZB x NZW)F-1 mice. Lupus mice were also treated with BM-MSCs, and serum autoantibodies, proteinuria, histologic changes in the kidney, and survival rates were monitored. Results. BM-MSCs inhibited antigen-dependent proliferation and differentiation to plasma cells of follicular and marginal zone B cells in vitro. This inhibitory effect was dependent on interferon-gamma (IFN gamma) and was mediated by cell-to-cell contact, involving the programmed death 1 (PD-1)/PD ligand pathway. In vivo treatment with BM-MSCs did not affect the levels of anti-double-stranded DNA antibodies or proteinuria. However, a reduction in glomerular immune complex deposition, lymphocytic infiltration, and glomerular proliferation was observed. Conclusion. Our findings indicate that BM-MSCs affect B cell receptor-dependent activation of both follicular and marginal zone B cells from lupus mice. This inhibitory effect is IFN gamma-dependent and cell contact-dependent. MSCs in vivo do not affect the production of autoantibodies, the level of proteinuria, or the mortality rates. Nonetheless, the significant improvement in histologic findings in the kidney supports the potential role of MSCs in the prevention of glomerular damage.