Exploring Nasal Structural-Microbial Interactions in Multiple Sclerosis-Associated Olfactory Impairment

Area of Science:

• Neurology
• Microbiology
• Otorhinolaryngology

Background:

• Olfactory dysfunction is common in multiple sclerosis (MS) but poorly understood.
• No prior studies have investigated the nasal mucosal microbiota in MS patients.
• This study explores links between smell function, nasal microbes, and turbinate volume in MS.

Purpose of the Study:

• To investigate the relationship between olfactory function, nasal microbiota composition, and superior turbinate volume in MS patients.
• To identify potential microbial biomarkers associated with olfactory impairment in MS.

Main Methods:

• A single-center observational study involving 42 MS patients and 37 healthy controls (HC).
• Olfactory function assessed using the University of Pennsylvania Smell Identification Test (UPSIT).
• Deep nasal microbiota profiling and MRI-based superior turbinate volume measurements were performed.

Main Results:

• MS patients with lower UPSIT scores had reduced Prevotella buccalis abundance.
• In healthy controls, UPSIT scores correlated positively with superior turbinate volume; this correlation was absent in MS patients.
• Superior turbinate volume negatively correlated with several bacterial genera (Cupriavidus, Methylobacterium-Methylorubrum, Ideonella, Acinetobacter) in MS patients.

Conclusions:

• Alterations in nasal microbiota may be associated with olfactory dysfunction and mucosal changes in MS.
• Prevotella buccalis is a potential microbial correlate of olfactory impairment in MS, though its role requires further investigation.
• Larger studies are needed to establish causality and explore the diagnostic/therapeutic potential of nasal microbiome features in MS.