TGN020 application against aquaporin 4 improved multiple sclerosis by inhibiting astrocytes, microglia, and NLRP3 inflammasome in a cuprizone mouse model

Abstract

In multiple sclerosis (MS), activation of the astrocytes and microglia induces a cascading inflammatory response. Overexpression of the aquaporin 4 (AQP4) in the glia is a trigger for this reaction. This study aimed to block AQP4 by injecting TGN020 to alleviate the symptoms of MS. Total of 30 male mice were randomly divided into control (intact), cuprizone model of MS (fed with 0.2% cuprizone for 35 days), and TGN020-treated (received daily intraperitoneal injections of 200 mg/kg TGN020 with cuprizone intake) groups. Astrogliosis, M1-M2 microglia polarization, NLRP3 inflammasome activation, and demyelination were investigated in the corpus callosum by immunohistochemistry, real-time PCR, western blot, and luxol fast blue staining. The Rotarod test was performed for a behavior assessment. AQP4 inhibition caused a significant decrease in the expression of the astrocyte-specific marker, GFAP. It also changed the microglia polarization from M1 to M2 indicated by a significant downregulation of iNOS, CD86, MHC-ІІ, and upregulation of arginase1, CD206, and TREM-2. In addition, western blot data showed a significant decrease in the NLRP3, caspase1, and IL-1b proteins in the treatment group, which indicated inflammasome inactivation. The molecular changes following the TGN020 injection resulted in remyelination and motor recovery enhancement in the treatment group. In conclusion, the results draw the attention to the role of AQP4 in the cuprizone model of MS.

Keywords: Aquaporin 4; Inflammasome; Multiple sclerosis; TGN-020.