Unique RNA expression profiles associated with plasma neurofilament light chain measurements in relapsing-remitting multiple sclerosis and neuromyelitis optica

Lukasz S. Wylezinski^1,2, Cheryl L. Sesler¹, Guzel I. Shaginurova¹, Elena V. Grigorenko¹, Franklin R. Cockerill, III^1,3,4, Michael K. Racke⁵, and Charles F. Spurlock, III^1,2,6

¹ Decode Health, Nashville, TN, USA 37203

² Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37203

³ Department of Medicine, Rush University Medical Center, Chicago, IL 60612

⁴ Trusted Health Advisors, Scottsdale, AZ 85251

⁵ Quest Diagnostics, Secaucus, NJ, 07094

⁶ Wagner School of Public Health, New York University, New York, NY 10012

Relapsing-remitting multiple sclerosis (RRMS) and neuromyelitis optica (NMO) are autoimmune diseases resulting in irreversible neurological damage. Neurofilament light chain (NfL) is released upon nerve injury and has been identified as a biomarker for neuronal damage. Studies have shown that NfL correlates with disease activity in RRMS and NMO, suggesting the utility of this biomarker to monitor disease progression and therapeutic response. Identifying RNA expression patterns preceding nerve damage and the release of NfL in the blood may allow for earlier intervention and therapeutic targeting. This study aimed to determine if RNA expression patterns identified in whole blood corresponded with changes in plasma NfL levels in RRMS and NMO. Treatment-naïve RRMS (n=40) and NMO (n=20) patients were grouped by plasma NfL levels and evaluated separately. Total RNA sequencing was performed using peripheral whole blood to examine coding and non-coding RNA expression profiles. Differential gene expression and biological pathway analyses were performed to identify differences in patients with high (33-668 pg/mL) and low levels (2-12 pg/mL) of circulating plasma NfL. Thousands of differentially expressed genes were identified in patients exhibiting high versus low NfL plasma measurements in RRMS and NMO. Genes associated with protein kinase function were modulated in RRMS, while genes involved in cytokine regulation were perturbed in NMO. Interestingly, two distinct expression patterns emerged among RRMS (n=20) and NMO (n=10) patients with the highest NfL levels, further separating these individuals. Transcriptional differences were significant among these RRMS and NMO subgroups, while plasma NfL measurements were not. When comparing altered gene expression between RRMS and NMO subgroups, genes associated with impaired transcriptional activity and host defense exhibited significant differences. Our findings support the hypothesis that significant transcriptional differences correlate with plasma NfL levels in RRMS and NMO. Further analysis uncovered significantly different RNA profiles in RRMS and NMO patients exhibiting the highest levels of plasma NfL, implicating the importance of RNA processing and pathogen response. Tracking transcriptional differences in combination with NfL could inform our understanding of biological processes that lead to neuronal damage and guide the identification of future therapeutic targets in RRMS and NMO.