In vivo electroporation-mediated transfer of interleukin-35 gene decreases demyelination in animal model of multiple sclerosis

Abstract

Introduction: Multiple sclerosis (MS) is an immune-mediated demyelinating disease, in which T cell tolerance is deteriorated to myelin antigens. Interleukin-35 (IL-35) is a novel anti-inflammatory cytokine, which belongs to the IL-12 family and includes p35 and Epstein-Barr virus (Ebi3). Evidence demonstrates that IL-35 has a potential to ameliorate autoimmune diseases by suppressing inflammatory lymphocytes and inducing regulatory lymphocytes. In this study, we aimed to clarify the IL-35 expression profile in response to experimental autoimmune encephalomyelitis (EAE), a model of MS in mice, and investigate the therapeutic potential of IL-35 by overexpressing it in EAE mice. Methods: Experimental autoimmune encephalomyelitis was induced in C57BL/6 mice by immunisation with MOG35-55 peptide. Mice were sacrificed at 14 days (initiative phase), 21 days (progressive phase), and 28 days (recovery phase) after immunisation. For electrotransfer of IL-35, recombinant murine IL-35 was encoded in pIGneo DNA plasmid and transferred into bilateral tibialis anterior muscles of EAE mice by electroporation at 10 days and 17 days after immunisation. Mice were sacrificed at 21 days after immunisation. Results: Expression of Ebi3 and p35 was downregulated during the progressive phase of EAE and upregulated during the recovery phase. Experimental autoimmune encephalomyelitis severity was attenuated in IL-35–transferred EAE mice. Correspondingly, the fluorescence intensity of myelin basic protein was elevated in IL-35–transferred EAE mice (P<0.001) accompanied with marked decrease of glial fibrillary acidic protein–positive (GFAP+) cells in the white matter of spinal cord from IL-35–transferred EAE mice compared with that from empty vector–transferred EAE mice (P<0.001). However, the fluorescence intensity of ionised calcium-binding adaptor molecule 1 did not show any significant difference. Conclusion: Taken together, these results demonstrate that in troducing IL-35 by electroporation effectively reduces EAE severity and prevents demyelination, which is probably through inhibiting the activation of GFAP+ astrocytes but not through microglia inactivation.