Cytomegalovirus immune responses are associated with lower serum NfL and disability accumulation risk at multiple sclerosis onset

Background: Infection by cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) play a prognostic role in multiple sclerosis (MS).Objectives: To explore whether humoral immune responses to HCMV and EBV at disease onset were associated with changes in serum and cerebrospinal fluid (CSF) levels of inflammatory and neurodegeneration biomarkers.Methods: Ninety-eight MS patients with a median follow-up of 20 years were included in the study. The levels of a panel of nine biomarkers were measured in serum (N = 60) and CSF (N = 61) samples of patients at the time of the first demyelinating event.Results: Immune responses to HCMV inversely correlated with serum neurofilament light chain (sNfL) levels (rho = -0.367; p = 0.039). sNfL levels were reduced in patients with high immune responses to HCMV (p = 0.006). Elevated sNfL levels were associated with higher risk of Expanded Disability Status Scale (EDSS) 3.0 (p = 0.016), 4.0 (p = 0.009) and 6.0 (p = 0.003), and with higher risk of developing secondary progressive MS (p = 0.003) and to receive treatment (p = 0.032). Serum soluble CD21 levels were increased in patients with high immune responses to EBV nuclear antigen 1 (p = 0.020).Conclusions: High immune responses to HCMV are associated with limited disease progression and central nervous system (CNS) injury in MS patients. These findings reinforce the protective role of HCMV infection in MS.