Printed Poster | Session 2

038 – The Role of microRNAs in the Multiple Sclerosis-Associated Human Astrocytic Stress Response

Nicholas Kieran (1) – Shih-Chieh Fuh (1) – Vijay Rao (1) – Manon Blain (1) – Samuel Ludwin (2) – Jack Antel (1) – Luke Healy (1)
Montreal Neurological Institute, McGill University, Montreal, Canada (1) – Pathology, Queen’s University, Kingston, Canada (2)

Astrocytes are an understudied cell type that are involved in multiple sclerosis (MS) pathology. Although astrocytes’ homeostatic functions are well-defined, their specific role in MS requires further investigation. MicroRNAs (miRNAs) are small non-coding RNA fragments that regulate cellular function by affecting translation. miRNAs have been found to be dysregulated in many diseases, and thus the differential expression of miRNAs in MS astrocytes may alter the normal phenotype of the cells and play a role in MS pathology. Studying the miRNA signature of MS astrocytes will give insight into the astrocytic response in disease. This work will also help to define the specific cellular stresses that astrocytes are exposed to in the MS brain. We hypothesize that MS associated cellular stresses drive a unique astrocytic miRNA signature that influences the functional response of astrocytes to the disease process. We aim to analyze the miRNA profile of primary human astrocytes in situ and in vitro in a stress paradigm that recapitulates the MS tissue environment. Astrocytes were laser captured from acute active MS lesions and normal appearing white matter. These cells were analyzed for their miRNA profile using qPCR. Primary human fetal astrocytes were treated in combinations of inflammatory (IL1b), metabolic (no glucose), and hypoxic (1% O2) stress conditions. qPCR analysis of canonical stress markers was used to confirm the specific response of astrocytes to the MS-like stress conditions. Next, we used qPCR to measure expression of a panel of miRNAs in astrocytes undergoing stress. Analysis of astrocytes captured from MS lesions reveals an MS-miRNA signature in these cells. We establish in vitro stress conditions that mimic the MS environment as measured by upregulation of MS-associated markers. We confirm that astrocytes respond to the individual stressors through upregulation of response genes CXCL10 (inflammatory), HMOX1 (metabolic), and SLC16A3 (hypoxic). Finally, we identify stress conditions that result in differential expression of miRNA-210, -155, and -34a compared to control cells. Overall, we have established an in vitro stress paradigm that reflects the specific cellular stresses of MS lesional tissue leading to a differential expression of specific miRNAs in these cells. This work enhances our understanding of the molecular profile and functional role of astrocytes in the MS brain.