Exploring the Role of MicroRNA125b- 5p in Regulating Microglial Mediated Neuroinflammation in Spinal Muscular Atrophy

Abstract

Spinal muscular atrophy (SMA) is a rare neuromuscular condition characterised by the degeneration of α-motor neurons at the spinal cord anterior horn, resulting in the loss of skeletal muscle fibres, progressive denervation, muscle weakness and atrophy (1). The survival motor neuron 1 (SMN1) gene is one of these duplicated genes, which differs from the homologous gene (SMN2). SMA severity manifests in patients with lower SMN2 copy numbers (2,3). MiRNA125b-5p has been considered a key player in inflammation by regulating A20/NF-κß signalling pathway, which is a crucial signalling cascade in CNS immune response (4). We hypothesise that the loss of SMN increases neuroinflammation caused by microglia. By targeting miRNA125b-5p using an antisense oligonucleotide, we believe that the NFKß1 pathway can be regulated to reduce the release of inflammatory cytokines. We used mouse BV2 cells transfected with an ASO designed to target and inhibit miRNA125b-5p. qPCR was performed using the NF-κB pathway markers: miRNA125b-5p, Tnfaip3, Nfkß1, and Tnf-α. We then investigated IL1B and Tnf-α cytokines levels using ELISA in media obtained from BV2 cells treated with designed ASO.Our preliminary results show the silencing of miRNA125b-5p expression in pre- designed ASO transfected BV2 cells. Furthermore, we show significant increased Tnfaip3 expression as hypothesised, and no significant change in expression of Nfkß1. Contrary to our expectations, we observed an increase in Tnf-α levels. We also observed the secretory cytokines, showed an increase in LPS (+ ) BV2 ASO transfected cells of Tnf-α proteins in media, while on the contrary LPS (-) BV2 ASO transfected cells showed a decrease concentration IL1b in media. believed to cause cell death via activation of innate inflammation responses.Further implications of these findings pertain to the wider applicability of obtained outcomes in clinical practice. Suppose the miRNA125b-5p can be modulated to suppress neuronal inflammation in SMA patients. The potential role of miRNA125b- 5p in other neurodegenerative diseases, thereby opening up new possibilities and challenges for potential treatments.