Age-related blood transcriptional regulators affect disease progression in pediatric multiple sclerosis.

Background: Pediatric onset multiple sclerosis patients (POMS) are defined as multiple sclerosis with an onset before the age of 18 years. Compared to adult onset multiple sclerosis (AOMS), POMS has more severe disease activity at onset, but better recovery. Little is known about the molecular mechanism responsible for the differences in the clinical presentations.

Methods: Peripheral Blood Mononuclear Cells samples were taken from 22 POMS patients (mean age 14.1 ± 2.4 years, 15 females, 7 male), and 16 AOMS patients, (mean age 30.8 ± 6.1 years,10 females, 6 males), and gene-expression were analyzed using Affymetrix Inc. HU-133-A2 microarrays. Differentially Expressed Genes (DEGs) that significantly distinguished between POMS and AOMS with pvalue <0.05 after false discovery rate correction were evaluated using Partek software. Twenty-one matched age and gender control was applied to clarify age-related changes. Clinical assessment was performed by analysis of expanded disability status scale (EDSS) and brain MRI lesion loads. Gene functional analysis was performed by Ingenuity Pathway Analysis software.

Results: Compared to AOMS, POMS had higher EDSS (3.0 IQR 2.0-3.0 and 2.0 IQR 2.0-3.0, p = 0.005), volume of T1 (2.72 mm, IQR 0.44-8.39 mm and 0.5 mm IQR 0-1.29 mm respectively, p = 0.04) and T2 (3.70 mm, IQR 1.3-9.6 and 0.96 mm, IQR 0.24-4.63 respectively, p = 0.02) brain MRI lesions. The POMS transcriptional profile was characterized by 551 DEGs, enriched by cell cycling, B lymphocyte signaling and senescent pathways (p < 0.02). Of these, 183 DEGs significantly correlated with T2 lesions volume. The POMS MRI correlated DEGs (n = 183) and their upstream regulators (n = 718) has overlapped with age related DEGs obtained from healthy subjects (n = 497). This evaluated common DEGs (n = 29) defined as POMS age-related regulators, suggesting to promote effect on disease severity.

Conclusion: Our finding of higher transcriptional levels of genes involved in cell cycle, cell migration and B cell proliferation that promoted by transcriptional level of age-associated genes and transcription factors allows better understanding of the more aggressive clinical course that defines the POMS.