The MMP-9/TIMP-1 Ratio and Concentrations of Osteopontin Are Elevated in Cerebrospinal Fluid of People With Multiple Sclerosis and Decrease After Autologous Hematopoietic Stem Cell Transplantation.

OBJECTIVES: To evaluate the utility of cerebrospinal fluid (CSF) biomarkers-matrix metalloproteinase-9 (MMP-9), tissue inhibitor of metalloproteinases-1 (TIMP-1), the MMP-9/TIMP-1 ratio, and osteopontin (OPN)-as indicators of blood-brain barrier (BBB) integrity and disease activity in people with relapsing-remitting multiple sclerosis (pwMS), and to assess their changes following autologous hematopoietic stem cell transplantation (aHSCT). METHODS: CSF samples from pwMS treated with aHSCT (n = 43) and healthy controls (n = 32) were analyzed for MMP-9, TIMP-1, and OPN concentrations using ELISA and electrochemiluminescence assays. Lumbar punctures were performed at baseline and at 1, 2, and 3-5 years post-aHSCT. Biomarker findings were compared with standard CSF parameters, prior treatments, and MRI data. RESULTS: MMP-9/TIMP-1 ratios and OPN levels were significantly elevated in pwMS compared to controls, particularly in those with gadolinium-enhancing lesions or on first-line therapies. Both biomarkers declined significantly after aHSCT and remained low during follow-up. The MMP-9/TIMP-1 ratio showed superior discriminatory capacity and correlated with inflammatory CSF markers. INTERPRETATION: CSF MMP-9/TIMP-1 ratio and OPN are elevated in MS and decrease following aHSCT, reflecting reduced inflammation and restored BBB integrity. These biomarkers may support disease monitoring and therapeutic evaluation.