Detection of HHV-6 miRNA in Multiple Sclerosis patients

HHV-6 miRNAs and antibodies were identified and significantly correlated with each other in serum and CSF of MS patients.

Both Epstein-Barr virus (EBV) and HHV-6A have been incriminated as potential causal factors in multiple sclerosis (MS). Increasingly, human miRNAs have been found to play roles in human disease. So it is plausible that EBV and HHV-6A might influence the course of MS through miRNAs that they encode. 

Dominguez-Mozo et al. at Hospital Clínico San Carlos and Hospital Universitario Quirónsalud, both in Madrid, measured HHV-6A/B microRNAs (miRNAs) in the cerebrospinal fluid (CSF) of untreated MS patients (n=43) and in patients with other neurological diseases (OND) (n=23). The following miRNAs were detected in the serum and results are demonstrated below (Table 1):

Table 1: HHV-6 miRNA presence in CSF and serum of MS and OND patients (Dominguez-Mozo 2020)

Levels of several of the miRNAs correlated significantly with each other: 

miR-2 and miR-3-5p (r=0.839 p = 10^-13)
miR-2 and miR-U86 (r = 0.578, p = 0.001)
miR-3-5p and miR-U86 (r = 0.698, p = 1.34 x 10^-5)
miR-2 and miR-3-5p (r = 0.626, p = 8.52 x 10^-4) 

Levels of anti-HHV-6A/B IgG in CSF, as well as intrathecal antibody production, were both statistically significantly higher in the CSF patients positive for miR-3-5p. Anti-HHV-6 IgG, but not IgM, levels were also significantly higher in serum of patients with MS than in patients with OND. MS patients with increased intrathecal anti-HHV-6A/B antibody production had a higher frequency of relapses.

At the same time, levels of these various miRNAs were not significantly different in the serum or CSF when patients with MS were compared to patients with OND, although the power of the study to recognize any differences as significant was poor. Thus, it is unclear if these HHV-6 microRNAs play a role in the pathogenesis of MS.

Read the full article: Dominguez-Mozo 2020