Neurolymphatic biomarkers of brain endothelial inflammatory activation: Implications for multiple sclerosis diagnosis

Aims: Multiple sclerosis (MS) is the leading cause of non-traumatic neurological disability in young adults, and its diagnosis is often delayed due to the lack of diagnostic markers. Initiation of disease -modifying therapy in the early stages of MS is especially critical because currently available therapy mostly target relapsing-remitting MS, and is less effective as disease progresses into the more chronic form of secondary-progressive MS. Therefore, exploring specific and sensitive biomarkers will facilitate an expedited and more accurate diagnosis to allow currently available therapies to be more effective. Main methods: Western blotting was conducted to detect the expression of neurolymphatic proteins in human brain endothelial cells in culture. Additionally, using a cohort of 150 patients with relapsing remitting MS, 26 with secondary progressive MS, and 60 healthy control samples, neurolymphatic protein expression was detected in serum samples using dot blot analysis. Key findings: Human brain microvascular endothelial cells express neurolymphatic markers. Neurolymphatic protein abundance increases with tumor necrosis factor (TNF)-α stimulation but decreases with interferon (IFN)- γ or combined (TNF + IFN) treatment. Circulating neurolymphatic protein levels is significantly lower in MS patients. Further, one of the markers, FOXC2, is associated with the clinical stages of MS, with significantly lower expression in secondary progressive MS compared to relapsing remitting MS. Significance: Our findings describe brain endothelial expression of neurolymphatic proteins, which is altered under inflammatory stress, and provide a possibility of using a collective pool of circulating neurolymphatic proteins as a diagnostic and prognostic biomarker of MS.