title: The soluble transcobalamin receptor (sCD320) is present in cerebrospinal fluid and correlates to dementia-related biomarkers tau proteins and amyloid-beta.
abstract: BACKGROUND
  Cellular uptake of vitamin B12 (B12) demands binding of the vitamin to transcobalamin (TC) and recognition of TC-B12 (holoTC) by the receptor CD320. Recently, we identified a soluble form of CD320 (sCD320) in human plasma. Here we present data on the occurrence of this soluble receptor in cerebrospinal fluid (CSF) and show its correlations to dementia-related biomarkers tau proteins and amyloid-beta.
  
  
  METHODS
  We collected 223 cerebrospinal fluid samples and corresponding plasma samples (n = 46). We measured CSF and plasma sCD320, holoTC and total TC employing in-house ELISA methods and CSF phospho-tau (181P) (p-tau), total tau (t-tau) and amyloid-beta 1-42 (Aβ) (n = 177) employing commercial ELISA kits (Innogenetics Company). Size exclusion chromatography was performed on a Superdex 200 column.
  
  
  RESULTS
  The median sCD320 concentration in CSF (14 pmol/L) is around five times lower than in plasma (72 pmol/L). No correlation was observed between plasma and CSF sCD320 levels (n = 46), while the behavior upon size exclusion chromatography was the same. In CSF, sCD320 correlates to holoTC and total TC (Spearman's correlation (Rs) = 0.325, 0.232 (n = 218, 217) respectively, p < 0.01). Interestingly, sCD320 correlates to p-tau and t-tau (Rs = 0.599, 0.569 (n = 173, 176) respectively, p < 0.001) and to Aβ (Rs = 0.265, p < 0.001 (n = 177)).
  
  
  CONCLUSIONS
  We document for the first time the occurrence of sCD320 in human CSF. We report that the concentration of sCD320 correlates to the dementia-related biomarkers p-tau, t-tau and Aβ.
authors.affiliation: Department of Clinical Biochemistry, Aarhus University Hospital , Aarhus , Denmark.
authors.forename: Omar
authors.initials: O
authors.lastname: Abuyaman
authors.forename: Ebba
authors.initials: E
authors.lastname: Nexo
mesh_terms: D016229:Amyloid beta-Peptides / Q000097:blood*; D015415:Biomarkers / Q000134:cerebrospinal fluid*; D003704:Dementia / Q000097:blood / Q000134:cerebrospinal fluid*; D006801:Humans; D010446:Peptide Fragments / Q000097:blood*; D011956:Receptors, Cell Surface / Q000032:analysis* / Q000097:blood; D014155:Transcobalamins / Q000032:analysis / Q000134:cerebrospinal fluid; D016875:tau Proteins / Q000134:cerebrospinal fluid*
chemical_list: D016229:Amyloid beta-Peptides; D015415:Biomarkers; D010446:Peptide Fragments; D011956:Receptors, Cell Surface; D014155:Transcobalamins; C075222:amyloid beta-protein (1-42); D016875:tau Proteins; C028176:transcobalamin receptor
keywords: CD320; amyloid beta-protein (1-42); cobalamin; phosphorylated tau; vitamin B12