Research Alert

Newswise — Background: Neuromyelitis optica spectrum disorders (NMOSD), anti-MOG-antibody associated disease (MOGAD) and multiple sclerosis (MS) may be difficult to differentiate. Detection of antibodies (Ab) targeting AQP4 and MOG is the diagnostic gold standard for the former two diseases, but has limited sensitivity and long laboratory turnaround time. Neutrophil granulocyte (NG) invasion of brain tissue is a key differentiator of NMOSD from MS, and has also been described in MOGAD.

Objectives: To examine the capability to differentiate NMOSD/MOGAD from MS by the profile of secreted primary (elastase (Ela); myeloperoxidase (MPO)) and secondary (matrix metalloproteinase-8 (MMP-8); neutrophil gelatinase-associated lipocalin (NGAL)) neutrophil granule products in CSF.

Methods: CSF from patients with NMOSD (n=42), MOGAD (n=6) and RRMS (n=41) were evaluated for Ela, MPO, MMP-8, NGAL, and compared with markers of neuronal (NfL) and astrocyte (GFAP, S100B) damage by conventional ELISA or single molecule array assay. CSFs from healthy controls (HC) (n=25) served as reference. The association between biomarkers and disease groups was assessed in linear models. The kinetic change of biomarkers in function of time since last relapse was modelled across disease groups. ROC curves and area under the curve (AUC) were calculated to estimate the potential to differentiate NMOSD/MOGAD from RRMS in acute disease phase (≤20 days after relapse), as well as between acute NMOSD and MOGAD. The association of biomarkers with EDSS in acute NMOSD and RRMS was assessed by linear models and Spearman correlation.

Results: All disease groups had elevated NfL vs HC (p<0.01), while GFAP levels were increased only in NMOSD (p<0.01). In acute NMOSD, all 4 NG markers were increased vs HC and acute RRMS (all p<0.01). In MOGAD, Ela, MPO and MMP-8 were increased vs HC (p<0.025) and acute RRMS (p<0.04). AUC in ROC analyses comparing acute NMOSD/MOGAD vs acute RRMS was high (Ela and NGAL: 0.91; MPO: 0.82; MMP-8: 0.81). In acute NMOSD, S100B and GFAP levels were increased in 89% (AUC=0.82) and 83% (AUC=0.80) of patients, respectively, vs median values of MOGAD. In acute NMOSD, EDSS scores correlated with all 4 NG markers (all p<0.01), and GFAP (p<0.031), but not with NfL and S100B (both p=0.21).

Conclusion: NG-specific biomarkers correlate with current EDSS scores in NMOSD. They show high sensitivity and specificity for rapid differentiation of acute NMOSD and MOGAD vs RRMS, similar to those reported for Ab against AQP4 and MOG. As the 4 NG biomarkers can be measured within few hours, as compared to an up to 2-week turnaround time for gold-standard cell-based assays for AQP4 and MOG, they could support individual decision making for acute therapeutic intervention. Further, increased S100B and GFAP levels differentiate acute NMOSD from MOGAD. NG markers may have a role in the diagnosis of Ab-negative NMOSD.

Presenter: MD David Leppert, University Hospital Basel and University of Basel, Neurologic Clinic and Policlinic, Departments of Medicine, Biomedicine and Clinical Research, Petersgraben 4, 4031, Basel, CH

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