Central role of B cells in interleukin-23 dependent neuroinflammation in the GF-IL23 model.

Interleukin (IL)-23 is one of the critical cytokines in autoimmune neuroinflammation. To further clarify the local function of IL-23 on the course of neuroinflammation, we recently established a transgenic mouse model with astrocyte-specific expression of IL-23 (GF-IL23). The GF-IL23 mice spontaneously developed a progressive ataxic phenotype with cerebellar infiltration with high amounts of B cells most prominent in the subarachnoid and perivascular space. To enlighten the B cell role in GF-IL23 mice, we generated GF-IL23 mice on a B cell knockout (k.o.) background (GF-IL23 B cell k.o.). GF-IL23 B cell k.o. mice compared with GF-IL23 mice had no infiltrates or only minor infiltration, and no antibody deposition was detected in the cerebellum. Furthermore, microglia, astrocyte activation, hypervascularization and demyelination were reduced in GF-IL23 B cell k.o. mice compared with GF-IL23 mice. Cytokines and chemokine receptors like IL-12a, cerebrospinal fluid 2 and CXCR3 were downregulated. Our study indicates that B cells are essential in IL-23-dependent neuroinflammation in the GF-IL23 model.