EXPRESSION AND GENETIC ANALYSIS OF MICRORNAS IN MULTIPLE SCLEROSIS AND ITS ANIMAL MODEL EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS
Creators: name: CANTONI, CLAUDIA
Publisher: name: Universit� degli Studi di Milano
Year: 2013

description: Multiple sclerosis (MS) affects about 2.5 million people worldwide. MS is a chronic inflammatory demyelinating disease of the central nervous system (CNS) and a common cause of neurologic disability in young adults.Clinically, the course of MS can be relapsing-remitting (RRMS), primary progressive (PPMS), non-relapsing or relapsing secondary progressive (SPMS). Experimental Autoimmune Encephalomyelitis (EAE) is the prime animal model for MS study and it has been instrumental for the development of four immune modulatory MS therapies thus far. MicroRNAs (miRNAs) are a novel class of small, non-coding RNAs recently discovered to regulate gene expression post-transcriptionally. MicroRNAs are now extensively studied as possible clinical biomarkers. They also represent potential therapeutic targets as they have been implicated in the pathogenesis of several human diseases, including autoimmune diseases as MS. Dysregulation of several miRNAs has been observed in blood cells and CNS tissues of MS compared to control subjects by microarray profiling. Given these premises the aims of my work are: 1) Perform a wide gene expression analysis for miRNAs and targets mRNAs in mononuclear cells from the blood (PBMC) of MS patients and healthy controls; 2) Analyze deeply miRNAs which are known to be highly correlated in the subpopulation of CD4+ cells; 3) Determine whether serum levels of extracellular microRNAs are altered in MS; 4) Evaluate the role of miR-223 in vivo during EAE. First 104 miRNAs transcripts were found to be deregulated between MS cases and controls. Among the best hits, let-7g and miR-150 were confirmed to be deregulated using quantitative PCR in a second sample of MS and controls; genome wide mRNA expression levels of 37.794 transcripts have been obtained on the same two cohorts and correlated with miRNAs expression profile to understand their in vivo effect and to identify potential novel targets of disease. Furthermore we also found that three best characterized miRNAs in CD4+ T cells, miR-21, miR-146a and ?b, were statistically significant higher expressed in the PBMCs of RRMS patients as compared with controls. In the analysis of circulating miRNAs the expression profile of 88 best characterized miRNAs was performed in a discovery cohort consisting of serum from 7 MS samples and 3 controls.The results identified three significantly downregulated miRNAs: miR-15b, miR-23a and miR-223. After data validation and replication in two independent populations, only miR-15b and miR-223 were confirmed to be significantly downregulated in MS patients versus controls. Since several lines of evidence suggest that miR-223 is involved in the MS pathogenesis we performed an active EAE experiment in miR-223 knock out (miR-223 KO) mice showing that miR-223 KO display a less severe EAE clinical course compared to littermate control mice. In conclusion, data here presented suggest that miRNAs dysregulation may contribute to the pathogenesis of MS and highlight the possibility to define different disease entities of MS with specific miRNAs profile. This aspect needs to be further investigated considering also that alteration in miRNAs expression in blood or body fluids may lead to the identification of new disease biomarkers of therapeutic targets.