Some studies have shown a more aggressive clinical course in multiple sclerosis (MS) patients of North African origin residing in Europe. It has been established that some genetic and environmental factors interact in a complex way by means of epigenetics to produce the pathology and the symptoms in MS. One of these epigenetic mechanisms is microRNAs (miRNAs), small non-coding RNA molecules that participate in the regulation of gene expression.
The objective of this study was to identify the existence of a differential profile of circulating cerebrospinal fluid (CSF) miRNAs between individuals with MS based on their ethnic origin.
A cohort of 20 individuals was studied: 10 European origin (MS-E) and 10 North African origin individuals (MS-NA). MS-NA individuals were subclassified according to migration age (before or after 15 years old).
216 miRNAs were analyzed in CSF using TaqMan OpenArray Human Advanced MicroRNA panels. Differential expression of the normalized value of each miRNA was studied using the U Mann-Whitney test.
When comparing the expression of miRNAs in CSF between MS-E and MS-NA, overexpression of miR-335-5p and miR-653-3p was observed in MS-NA (p= 0.008 and p= 0.027, respectively). Furthermore, two other miRNAs (miR-143-3p and miR-20a-5p) showed a tendency to be deregulated.
A sub-analysis was performed in which MS-NA was divided according to the age of migration. miR-145-5p, miR-150-5p and miR-653-3p showed significant differences between some of the 3 groups. Specifically, miR-150-5p, previously related to inflammation and MS in CSF, showed very low levels in MS-NA that migrated older than 15 years of age.
The results show the presence of a differential expression in miRNAs between MS patients according to their ethnic origin. In patients of North African origin who migrated at an early age, an overexpression of miRNAs clearly related to inflammation is observed.