To identify markers in the CSF of multiple sclerosis (MS) subtypes, we used a two-step proteomic approach: (i) Discovery proteomics compared 169 pooled CSF from MS subtypes and inflammatory/degenerative CNS diseases (NMO spectrum and Alzheimer disease) and healthy controls. (ii) Next, 299 proteins selected by comprehensive statistics were quantified in 170 individual CSF samples. (iii) Genes of the identified proteins were also screened among transcripts in 73 MS brain lesions compared to 25 control brains. F-test based feature selection resulted in 8 proteins differentiating the MS subtypes, and secondary progressive (SP)MS was the most different also from controls. Genes of 7 out these 8 proteins were present in MS brain lesions: GOLM was significantly differentially expressed in active, chronic active, inactive and remyelinating lesions, FRZB in active and chronic active lesions, and SELENBP1 in inactive lesions. Volcano maps of normalized proteins in the different disease groups also indicated the highest amount of altered proteins in SPMS. Apolipoprotein C-I, apolipoprotein A-II, augurin, receptor-type tyrosine-protein phosphatase gamma, and trypsin-1 were upregulated in the CSF of MS subtypes compared to controls. This CSF profile and associated brain lesion spectrum highlight non-inflammatory mechanisms in differentiating CNS diseases and MS subtypes and the uniqueness of SPMS.
Bibliografisk noteFunding Information:
Immunohistochemistry and RNAscope of chronic active brain lesion. Human postmortem brain tissue were supplied by the UK Multiple Sclerosis Tissue Bank (UK Multicentre Research Ethics Committee, MREC/02/2/39), funded by the Multiple Sclerosis Society of Great Britain and Northern Ireland (registered charity 207,495). Fresh-frozen blocks containing chronic active lesion from progressive MS patients were sectioned (10-μm), PFA-fixed, blocked in PBS with 10% normal horse serum (NHS) and immunostained with rabbit CHI3L1 (monoclonal antibody) 1:200 (Abcam) followed by biotinylated secondary antibody (Jackson Immu-noresearch Laboratories, Cambridgeshire, UK), avidin/biotin staining (Vector Laboratories, Burlingame, CA) and 3,3′-diaminobenzidine (DAB) staining (Vector Laboratories, Burlingame, CA). The RNAscope 2.5 Duplex Assay (ACD Biosystems) was performed according to the ACD protocol for fresh-frozen tissue. Chronic active lesions were hybridized with two mRNA probes per experiment. Hs-GFAP (Cat No. 311801) was used as the astrocyte marker together with Hs-CHI3L1 (Cat No. 408121). The probes were amplified according to manufacturer’s instructions and labeled with the following red or green color for each experiment. The Hs-CHI3L1 probe was also combined with immunohistochemistry (anti-GFAP and anti-MHCII, Abcam) as described above.
Lundbeckfonden R118-A11472, OTKA-K77892, Scleroseforeningen R431-A29926-B15690 and R399-A28099-B15690, Region of Southern Denmark 14/24200, Jascha Fonden 5589, Direktør Ejnar Jonasson kaldet Johnsen og hustrus mindelegat 5609, Odense University Hospital (OUH) A474 (to ZI), OTKA-NN109841, GINOP 2.3.2-15-2016-00049. JB is grateful for financial support from JB’s VILLUM Young Investigator Grant nr. 13154. NA received funding from JB’s SDU2020 grant. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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