Amino Acid Levels as Potential Biomarkers of Multiple Sclerosis in Elderly Patients: Preliminary Report

BACKGROUND AND PURPOSE: Aging in multiple sclerosis is associated with both disease- and age-dependent neurodegeneration. Serum metabolomic profiling of amino acids seems to be a promising method for searching for biomarkers of neurodegenerative disorders. The aim of this study was to determine the profile of nonessential amino acids in the serum of elderly patients with secondary progressive multiple sclerosis (SPMS). METHODS: We used high-performance liquid chromatography to evaluate the serum concentrations of nonessential amino acids in subjects aged >65 years: six patients with SPMS and 20 control subjects (CS). RESULTS: The serine and alanine levels were significantly higher in SPMS patients than in CS, whereas the concentrations of aspartic acid, arginine, and cysteine were significantly lower in SPMS patients. These observations indicate that amino acids may be involved in SPMS neurodegeneration mechanisms. There were no significant differences in the serum concentrations of the other four amino acids investigated (glutamic acid, glycine, proline, and tyrosine) between patients with SPMS and CS. CONCLUSIONS: The preliminary results obtained in the study suggest that the metabolism of some amino acids is altered in patient with SPMS. We also conclude that amino acid profiling might be helpful in searching for putative biomarkers of central nervous system diseases. However, considering the multifactorial, heterogeneous, and complex nature of SPMS, further validation research involving larger study samples is required before applying these biomarkers in diagnostic practice.