Blood Sugar Coating Patterns May Reveal MS Type Without Antibody Testing
Plasma N-glycan profiling distinguishes MS from AQP4-Ab NMOSD and MOGAD with up to 80.5% accuracy, offering a noninvasive diagnostic complement.
Summary
Researchers analyzed plasma N-glycan profiles from 120 patients with relapsing-remitting MS, secondary progressive MS, MOGAD, and AQP4-Ab NMOSD using advanced liquid chromatography coupled with high-resolution mass spectrometry. Distinct glycan signatures were identified for each disease category. Antibody-defined diseases showed increased monosialylation, trigalactosylation, highly branched N-glycans, and antennary fucosylation compared with MS — and these differences held even when antibody levels were undetectable. The approach achieved 80.5% accuracy distinguishing MS from antibody-defined diseases, 77.8% for MOGAD vs AQP4-Ab NMOSD, and 75.2% for RRMS vs SPMS. These findings suggest plasma glycomics could complement existing diagnostic tools, especially during periods of antibody seronegativty.
Detailed Summary
Differentiating multiple sclerosis from antibody-mediated demyelinating diseases like AQP4-Ab NMOSD and MOGAD is a persistent clinical challenge, particularly when antibody titers fall below detection thresholds during remission or after immunotherapy. Misdiagnosis carries serious consequences: MS-specific treatments can trigger relapses in antibody-defined diseases, while emerging targeted therapies for NMOSD require precise patient selection. This study explored whether plasma N-glycan profiling — a measure of sugar molecule modifications on blood proteins — could serve as a reliable, noninvasive diagnostic adjunct.
One hundred twenty patients were recruited from Oxford University Hospitals: 30 each with RRMS, SPMS, MOGAD, and AQP4-Ab NMOSD. Plasma N-glycans were released enzymatically, fluorescently labeled, and analyzed using ultra-high-performance hydrophilic interaction liquid chromatography (HILIC-UHPLC) coupled with high-resolution Orbitrap mass spectrometry. Orthogonal partial least-squares discriminant analysis (OPLS-DA) was applied with 10-fold cross-validation and permutation testing to identify disease-discriminating glycan features.
The analysis revealed statistically distinct N-glycome profiles across all four disease groups. When distinguishing MS (RRMS + SPMS combined) from antibody-defined diseases (MOGAD + AQP4-Ab NMOSD combined), the model achieved 80.5% accuracy. Separating MOGAD from AQP4-Ab NMOSD reached 77.8% accuracy, and distinguishing RRMS from SPMS yielded 75.2% accuracy. Key discriminatory glycan traits in antibody-defined diseases versus MS included increased monosialylation (OR = 2.57, p < 0.0001), trigalactosylation (OR = 2.70, p < 0.0001), highly branched N-glycans (OR = 2.32, p = 0.0002), and antennary fucosylation (OR = 2.89, p < 0.0001). Critically, these differences were independent of antibody serostatus at the time of sampling.
These findings align with established immunological roles of N-glycans: branching and fucosylation patterns modulate T-cell and B-cell activation and influence Fcγ receptor binding, relevant to the pathophysiology of both cell-mediated (MS) and antibody-mediated (NMOSD, MOGAD) diseases. The elevation of GlycA-related N-acetylglucosamine signals in progressive MS also mirrors prior NMR metabolomics findings, reinforcing biological plausibility.
However, the study has important limitations. The cohort is single-center and relatively small (n = 30 per group), and demographic imbalances exist — notably, SPMS and AQP4-Ab NMOSD groups had significantly more female patients and were older than RRMS and MOGAD groups. Causality cannot be established from cross-sectional data, and the mechanistic link between specific glycan alterations and disease pathology requires further investigation. Longitudinal and multicenter validation is needed before clinical adoption.
Key Findings
- Plasma N-glycan profiling distinguished MS from antibody-defined diseases with 80.5% accuracy independent of antibody serostatus.
- Antennary fucosylation was the strongest individual discriminator (OR = 2.89) favoring antibody-defined diseases over MS.
- MOGAD and AQP4-Ab NMOSD were separated with 77.8% accuracy; RRMS and SPMS with 75.2% accuracy.
- Trigalactosylation and monosialylation were significantly elevated in antibody-defined diseases versus MS.
- Highly branched N-glycans were enriched in NMOSD and MOGAD, consistent with differences in B-cell-driven immunity.
Methodology
Cross-sectional cohort study of 120 patients (30 per group: RRMS, SPMS, MOGAD, AQP4-Ab NMOSD) from a single UK center. Plasma N-glycans were analyzed by HILIC-UHPLC coupled to Orbitrap high-resolution mass spectrometry with fluorescence detection. OPLS-DA with 10-fold cross-validation, 100 repetitions, and permutation testing was used for classification modeling.
Study Limitations
Single-center design and small group sizes (n = 30 per group) limit generalizability and statistical power. Significant demographic imbalances — particularly age and sex differences between SPMS/AQP4-Ab NMOSD and RRMS/MOGAD groups — may confound glycan comparisons. Cross-sectional design precludes causal inference, and longitudinal validation is needed to assess stability of glycan signatures over time and treatment.
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