Amino acid metabolism is altered in people with multiple sclerosis (MS), found a new study published in the Polish Journal of Neurology and Neurosurgery. Moreover, it is influenced by the clinical type of the disease. 

“Serum amino acids may be considered as potential molecular biomarkers of MS, components of individualized therapeutic agents, or laboratory indicators to monitor the intensity of physical rehabilitation,” the researchers concluded.

It is already known that amino acid metabolism is crucial in regulating immune responses. Here, a team of researchers from Poland led by Zdzisław Maciejek, MD, analyzed the amino acid profiles in the serum of 121 patients with MS—a disease characterized by an autoimmune attack to the myelin sheath surrounding nerve cells—and 53 healthy controls. 

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Of these 121 patients, 41 had relapsing-remitting MS (RRMS), 55 had secondary progressive MS (SPMS), and 25 had primary progressive MS (PPMS). The patients’ median Expanded Disability Status Scale (EDSS) score was 6. 

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The researchers tested the serum concentration of 29 different amino acids. They found that the total amino acid concentration in the serum of patients with MS was significantly higher than that of healthy controls. 

The researchers then analyzed the concentration of each amino acid independently and found that the concentrations of arginine, 1-methyl-L-histidine, and proline were higher in MS patients compared to healthy people. However, the concentration of circulating citrulline, α-aminobutyric acid, and tryptophan were higher in the serum of healthy controls. 

When they analyzed patients by type of disease, the researchers found that the highest level of total serum amino acid occurred in patients with PPMS, while the lowest occurred in patients with RRMS. 

The researchers also reported higher serum levels of beta-aminoisobutyric acid in patients with PPMS compared to patients with RRMS and SPMS.

Finally, they found that the serum levels of aspartic acid were significantly higher in patients with PPMS compared to those with RRMS. 

The researchers reported no significant differences in total amino acid concentration in MS patients who had an EDSS score of 5 or less and those with an EDSS score of more than 5. “From visual inspection, no trend was observed in total amino acids concentration with respect to the EDSS score,” they wrote.

They speculated that the recorded differences may be the result of the amino acids participating in immune responses, neurodegeneration processes, and muscle protein construction.


Rzepiński Ł, Kośliński P, Kowalewski M, Koba M, Maciejek Z. Serum amino acid profiling in differentiating clinical outcomes of multiple sclerosis. Neurol Neurochir Pol. Published online August 1, 2023. doi:10.5603/PJNNS.a2023.0054