Proteolytic imbalance in plasma of patients with multiple sclerosis following COVID-19

Background. The present research was conducted with the following objectives: 1) to determine the plasma levels of five matrix metalloproteinases (MMPs), namely MMP-1, -2, -3, -8, -10, and tissue inhibitor of metalloproteinase-1 (TIMP-1); 2) to analyze protease activity profiles in plasma using a zymographic method; and 3) to perform preliminary analysis on plasma peptide pool composition in patients with multiple sclerosis (MS) with and without COVID-19 history. Materials and methods. We examined 97 patients with MS: 41 had been diagnosed with COVID-19 in the past 4–6 months (MS + COVID group), and 56 did not suffer from SARS-CoV-2 infection previously (MS group). The plasma of healthy volunteers (n = 30) with no evidence of disease was used as control. The enzyme-linked immunosorbent assay was used to measure MMP and TIMP-1 concentrations. Plasma MMP activity was verified by gelatin-substrate zymography. Peptide pools were extracted from the plasma of MS patients and healthy subjects. Then size exclusion chromatography was used to identify separate fractions present in peptide pools. Results. We found that plasma concentration of MMP-2 was remarkably increased in the MS group compared with healthy controls, while in the MS + COVID patients, the levels of two other MMPs, MMP-1 and -10, were elevated. Zymography showed four dominant gelatinolytic bands of 92, 84, 72, and 62 kDa in MS plasma samples, whereas only traces of MMP were detected in healthy subjects. Most of MS plasma samples showed MMP-2 lytic activity, but only a few contained MMP-9. Finally, we determined the concentration of circulating peptides. The levels of plasma peptides were higher in patients from both the MS and MS + COVID group compared to control subjects. According to our results, the development of MS was accompanied by changes in both quantity and quality of peptide pool composition compared to healthy controls. Conclusions. Thus, an advanced understanding of the role of MMPs in MS pathogenesis following infection is important in developing optimized interventions to improve health and clinical outcomes during COVID-19.