Serum miR-199a-3p and miR-103a-3p are possible biomarkers for the onset of multiple sclerosis

Why tiny blood clues matter in a big brain disease

Multiple sclerosis (MS) is a lifelong disease in which the body’s own defenses attack the brain and spinal cord, often striking people in the prime of life. Doctors know that catching MS early and tracking how it evolves can make a real difference, but the tools they have today are either invasive, like spinal taps, or not sensitive enough in the earliest stages. This study explores whether two microscopic molecules floating in the blood could serve as simple, non‑invasive clues that MS has begun and how it might progress.

Small messengers in the bloodstream

Our cells constantly release short strands of genetic material called microRNAs into the blood. These tiny messengers help fine‑tune which genes are turned on or off, and their patterns often change when disease is present. The researchers focused on two such molecules, named miR‑199a‑3p and miR‑103a‑3p, because earlier work suggested they might be involved in MS and in the body’s control of inflammation and cell growth. By looking for these molecules in blood, the team hoped to find a kind of chemical fingerprint that distinguishes people with MS from healthy individuals.

Comparing people with and without MS

The study involved 185 people with MS and 57 healthy volunteers. Among those with MS, some had just recently developed symptoms, others had a relapsing form with flare‑ups followed by recovery, and others had a progressive form with steady worsening over time. From a small amount of blood, the team measured how many copies of each microRNA were present using a highly sensitive technique that can count individual molecules. This allowed them to compare levels across the different groups and ask whether the pattern in blood matched the stage or type of the disease.

Early spikes in microRNA signals

The results showed that both microRNAs were generally higher in people with MS than in healthy volunteers. But the most striking changes appeared in those at the very beginning of their illness. People with short‑duration MS had especially high levels of miR‑199a‑3p, even more than those with long‑standing relapsing or progressive disease. The second microRNA, miR‑103a‑3p, was also increased in newly diagnosed and relapsing patients, but not in those with progressive MS, where its level dropped back toward that of healthy people. When the researchers combined both signals in a statistical model, the ability to tell newly diagnosed patients apart from healthy volunteers improved compared with using either marker alone.

What these signals may be doing

Computer‑based analyses suggested that these two microRNAs influence networks of genes involved in fat processing and inflammatory responses. Fats are important building blocks of the insulating sheath that wraps nerve fibers, which is damaged in MS, and they also help maintain the barrier that protects the brain from harmful substances in the blood. Both microRNAs have been linked in other studies to dampening inflammatory activity. The authors propose that their rise early in MS may be part of the body’s attempt to counteract harmful immune attacks and preserve nerve insulation, an effort that seems to fade once the disease becomes steadily progressive.

Promise and next steps for patient care

For people living with MS or at risk of developing it, the key message is that a simple blood test might one day help doctors spot the disease sooner and follow how it changes over time. Measuring these two microRNAs together distinguished early MS from healthy status with reasonable accuracy, suggesting they could become useful add‑on tools alongside brain scans and clinical exams. The authors caution that more work is needed: the same people must be followed over years, and the exact gene pathways controlled by these microRNAs must be tested in detail. Still, the study adds to growing evidence that tiny molecules in a blood sample can reveal early warning signs of brain disease and may eventually guide more timely and tailored MS treatment.

Citation: Agostini, S., Mancuso, R., Pasanisi, M.B. et al. Serum miR-199a-3p and miR-103a-3p are possible biomarkers for the onset of multiple sclerosis. Sci Rep 16, 12089 (2026). https://doi.org/10.1038/s41598-026-42973-3

Keywords: multiple sclerosis, biomarkers, blood test, microRNA, neuroinflammation