Profiling of biomarkers in alternative body fluids and point-of-care testing for optimised management of multiple sclerosis

Multiple sclerosis (MS) is a chronic, inflammatory, autoimmune, and neurodegenerative disease of the central nervous system that affects approximately 2.9 million individuals worldwide. Over the last four decades, the global incidence of MS has steadily increased, a trend partially explained by improvements in diagnostic technologies, stronger healthcare systems, and socioeconomic factors. Nonetheless, available disease-modifying therapies (DMTs) are primarily restricted to relapsing-remitting MS, leaving patients with progressive forms of the disease with limited treatment options. Moreover, standardised clinical or imaging biomarkers for monitoring disease progression are lacking, posing a critical challenge for healthcare systems and clinical practice. This thesis investigates molecular and technological strategies to improve the diagnosis and monitoring of MS, with a particular focus on saliva as a non-invasive biofluid for biomarker discovery. Given the central role of oxidative stress (OS) and inflammation in MS pathology, our first objective was to examine the regulation of redox and inflammatory responses in peripheral blood mononuclear cells (PBMCs) isolated from MS patients and healthy controls, alongside the expression of circulating cytokines and chemokines. Our results demonstrate that variations in OS-related genes, particularly Nrf2 and NF-κB, can distinguish MS patients from controls, highlighting their potential utility as diagnostic and prognostic biomarkers. A panel of 13 cytokines and chemokines was also analysed, revealing a distinction in peripheral inflammatory mechanisms between relapsing-remitting and progressive MS. Aside from blood-based measures, we also explored non-conventional biofluids as sources of immunological, inflammatory, and neurodegenerative biomarkers. A panel including NfL, CXCL13, sTREM2, and CHI3L1 was evaluated in both serum and saliva to explore multiple pathways implicated in MS pathology. To our knowledge, this is the first study to simultaneously measure salivary NfL and CHI3L1 in MS patients, with results demonstrating detectable levels that can differentiate MS individuals from healthy controls. Receiver operating characteristic (ROC) curve analyses indicated moderate diagnostic accuracy for salivary CHI3L1, with improved performance when combined with NfL, underscoring the potential of saliva as a non-invasive fluid for biomarker detection and repeated sampling in MS. Based on these findings, we developed and prototyped an antibody-based lateral flow assay (LFA) for salivary CHI3L1 detection. This proof-of-concept test successfully identified varying concentrations of CHI3L1, demonstrating the feasibility of point-of-care applications outside traditional clinical or laboratory environments. This kind of device could support near-patient testing and facilitate regular monitoring, with potential implications not only for MS but also for other neurological conditions characterized by inflammatory and neurodegenerative processes. In summary, this thesis establishes saliva as a clinically relevant and easily accessible body fluid for biomarker assessment in MS, introduces novel applications such as salivary NfL quantification and OS gene profiling in PBMCs, and advances the development of point-of-care diagnostic strategies. By integrating molecular biomarkers with translational testing approaches, this work contributes to the advancement of non-invasive, rapid, and user-friendly methods for improving monitoring, patient stratification, and disease management in MS.

Funder

University of Galway

Publisher

University of Galway

Rights

CC BY-NC-ND

cbn

Collections

University of Galway Theses (PhD Theses)