Targeting astrocyte and motor neuron specific miRNAs to prevent neuro-immune dysregulation in ALS

Abstract

Event Abstract Back to Event Targeting astrocyte and motor neuron specific miRNAs to prevent neuro-immune dysregulation in ALS Ana R. Vaz1, 2, Catarina Sequeira1, Daniela Vizinha1, Marta Barbosa1, Cátia Gomes1 and Dora Brites1, 2, 3* 1 Research Institute for Medicines (iMed.ULisboa), Portugal 2 Faculdade de Farmácia, Universidade de Lisboa, Department of Biochemistry and Human Biology, Portugal 3 Faculdade de Farmácia, Universidade de Lisboa, Portugal Amyotrophic lateral sclerosis (ALS) is characterized by motor neurons (MNs) loss and glial reactivity in brain and spinal cord (SC). A dysregulated expression of microRNAs (miRNAs) have been implicated in neurodegeneration and neuroinflammation in ALS. MiRNA(miR)-124 is elevated in the cerebrospinal fluid of ALS patients and in the SC of the ALS mice with the G93A mutation in human superoxide dismutase-1 (mSOD1). We demonstrated that this miRNA is upregulated in MN-NSC-34 overexpressing mSOD1 and in small extracellular vesicles isolated from cell secretome [1]. We also observed miR-155 upregulation in the SC of pe-symptomatic mSOD1 mice [2], often associated with mSOD1 microglia [3], but with unknown effect when expressed by astrocytes. In contrast, miR-146a was downregulated either in the cortical brain (CB) of symptomatic mSOD1 mice and in isolated astrocytes [4], suggesting distinct miRNA deregulation depending on the CNS region. Here, we evaluated the effects of miR-155/146a/124 modulation in astrocytic and MN function. For that, we used primary astrocytes from mSOD1 mice pups (CB or SC) and mSOD1 MN-NSC-34. Cells were transfected with anti-miR-155 (SC astrocytes), premiR-146a (CB astrocytes) or pre/anti-miR-124 (MN). We also explored whether changes in MN-miR-124 expression impact on secretome-mediated astrocytic function. Downregulation of miR-155 in mSOD1 SC astrocytes counteracted the inflammatory milieu, by decreasing TNF-α/IL-1β/HMGB1/miR-124, and increasing IL-6/IL-10/SOCS1/miR-146a expression, without changing the astrocytic aberrant phenotype (GFAPlow/Cx43high/S100Bhigh). However, miR-146a upregulation in mSOD1 CB astrocytes neutralized both the phenotypic aberrancy and the inflammatory profile. The upregulation of miR-124 in WT-MNs mimicked the pathological features of mSOD1-MNs, namely inflammatory-associated-miRNAs (increased miR-125b/decreased miR-146a/-21), synaptic dysfunction (increased synaptophysin/decreased PDS-95), neurite loss, reduced mitochondria viability and axonal transport deficits (increased dynein/decreased kinesin), while miR-124 downregulation was able to prevent those dysfunctionalities in mSOD1-MNs. The astrocytic aberrant phenotype of mSOD1 SC astrocytes was observed in WT cells upon incubation with secretome from mSOD1-MNs or pre-miR-124-WT-MN, but prevented in the presence of the secretome of anti-miR-124-mSOD1-MN. More importantly, secretome derived from anti-miR-124-mSOD1-MN rescued the aberrant phenotype of mSOD1 SC astrocytes by increasing GFAP/GLT-1 expression. Overall, our results highlight that combined modulation of specific miRNAs in different target cells may represent a promising therapeutic potential in ALS disease. Acknowledgements Funded by SCML (ALS Research Grant ELA-2015-002) and FCT (PTDC/MED-NEU/31395/2017 and LISBOA-01-0145-FEDER-031395 to DB, UID/DTP/04138/2013 to iMed.ULisboa, and fellowship ARV-SFRH/BPD/76590/2011).