Ivan Pavlovic: The Quieting Storm: Longitudinal Analysis of CSF Biomarkers Following Autologous Hematopoietic Stem Cell Transplantation for Multiple Sclerosis

Abstract

Multiple sclerosis (MS) is a chronic inflammatory and neurodegenerative disease of the central nervous system, driven by immune-mediated damage to myelin and axons. Although several disease-modifying therapies (DMTs) can reduce inflammatory activity, some patients continue to experience relapses and accumulating disability. For these individuals, autologous hematopoietic stem cell transplantation (aHSCT) represents a potent therapeutic option capable of inducing long-term remission. The studies included in this thesis aimed to elucidate how aHSCT influences key molecular processes in MS through cerebrospinal fluid (CSF) biomarker analysis. Paper I investigated circulating cell-free mitochondrial DNA (ccf-mtDNA) as a marker of inflammation in MS. Concentrations were elevated in people with MS (pwMS) compared with healthy controls and decreased markedly after intervention with aHSCT, indicating normalization of inflammatory activity. Paper II examined microRNAs (miRNAs) biomarkers of inflammatory disease activity. Twelve dysregulated miRNAs were identified, of which a recurring four-miRNA cluster (miR-16-5p, miR-21-5p, miR-146a-5p, miR-150-5p) showed strong associations with disease activity and normalized after aHSCT, reflecting a rebalanced immune milieu. Paper III focused on the blood–brain barrier (BBB), assessing the MMP-9/TIMP-1 ratio and osteopontin (OPN) as markers of barrier integrity. Both were elevated before treatment and declined significantly after aHSCT, suggesting restoration of structural and functional BBB stability. Paper IV explored biomarkers associated with progressive disease; galectin-9 (Gal-9), growth differentiation factor (GDF-)15, and chitinase 3-like protein 1 (CHI3L1, YKL-40); all of which decreased following aHSCT, indicating reduced glial activation and mitigation of progression-related mechanisms. Collectively, these studies demonstrate that aHSCT induces profound and sustained molecular remission across inflammatory, structural, and degenerative domains of MS. The findings highlight the value of CSF biomarkers in understanding treatment mechanisms and underscore the need for integrative biomarker strategies to guide optimal timing and patient selection for aHSCT.