Emerging Serum microRNAs as Early Signals in MS

The search for accessible, non-invasive biomarkers in multiple sclerosis (MS) has been an ongoing challenge. MicroRNAs, with their stability in serum and regulatory role in gene expression, have emerged as compelling candidates. In a recent study published in Scientific Reports, investigators explored two circulating microRNAs—miR-199a-3p and miR-103a-3p—as potential early indicators of disease onset.

Study Design

This cross-sectional observational study enrolled 185 individuals across the MS disease spectrum and 59 healthy controls. Participants were stratified into clinically relevant subgroups, including those in the early stage of disease within two years of onset, individuals with relapsing disease, those with progressive disease, and a cohort of healthy controls.

All samples were collected under controlled conditions, with efforts to minimize confounders such as recent relapse or corticosteroid exposure. Serum microRNA levels were quantified using ddPCR, and statistical comparisons were performed across groups.

Signals that Shift with Disease Stage

Both miR-199a-3p and miR-103a-3p appear measurably elevated in individuals with MS compared to healthy controls, with statistically significant differences (miR-199a-3p: p=0.001; miR-103a-3p: p=0.05).

A nuanced pattern emerges when examining disease subtypes. miR-199a-3p is elevated across all MS groups, but it appears most pronounced early in the disease course, with significant differences between early-stage and both relapsing (p=0.02) and progressive disease (p=0.01).

miR-103a-3p behaves differently. Its elevation is confined to early and relapsing disease (p=0.007 and p=0.009, respectively), while levels in progressive MS return toward those seen in healthy individuals. This change suggests that miR-103a-3p may reflect a defensive mechanism against active inflammatory or immune processes that are more prominent earlier in the disease, whereas miR-199a-3p may represent a more sustained biological response.

When both microRNAs are considered together, their diagnostic performance improves. Combined analysis enhances the ability to distinguish early MS from healthy controls, supported by significant model performance.

Biological Context: Beyond Detection

The study offers thoughtful insight into potential mechanisms. miR-199a-3p is known to regulate the AKT/mTOR signaling pathway, a central node in cellular growth and immune activation. In experimental MS models, this pathway contributes to chronic inflammation. miR-103a-3p, meanwhile, has demonstrated anti-inflammatory effects, including suppression of cytokines such as TNF-α and IL-1β.

Both microRNAs are also linked to fatty acid metabolism pathways, processes relevant to myelin integrity and blood–brain barrier function. This raises an interesting possibility: these circulating signals might not merely be markers, but rather participants in disease-modifying pathways.

Clinical Interpretation and Caution

The study’s cross-sectional design limits insight into how these biomarkers evolve over time. In addition, downstream gene targets were not directly assessed, and while treatment effects were explored, their influence cannot be fully excluded.

However, even with these limitations, the results position miR-199a-3p and miR-103a-3p as compelling candidates for early detection. Their stability in serum and non-invasive accessibility offer clear practical advantages over more invasive approaches such as cerebrospinal fluid analysis. With further validation in longitudinal and real-world settings, these microRNAs could contribute meaningfully to earlier diagnosis and more tailored clinical decision-making in MS.

Reference:
Agostini S, Mancuso R, Pasanisi MB, et al. Serum miR-199a-3p and miR-103a-3p are possible biomarkers for the onset of multiple sclerosis. Sci Rep. Published online March 5, 2026. doi:10.1038/s41598-026-42973-3