Fig. 1: Correlation of CSF and plasma protein levels.
From: Disruption of the cerebrospinal fluid–plasma protein balance in cognitive impairment and aging
a, Schematic showing routes for proteins to reach the CSF. Proteins can be locally produced either in the brain or in peripheral organs, secreted to the blood and transported into the CSF across the brain barrier system. b, Protein source annotation for the 2,304 proteins robustly detected in CSF. Fourfold enrichment of bulk GTEx RNA expression in the relevant tissues was required for annotation as CNS derived or peripheral organ derived. c,d, Histogram of Pearson’s coefficients for correlations between CSF and plasma levels in the Stanford cohort (n = 304) for CNS proteins (c) and peripheral proteins (d). e, Bar plot showing the percentage of proteins with positive CSF–plasma correlations (Pearson’s r > 0.2) by protein source. Two-proportion z-test P values: P = 1.2 × 10−33 (peripheral versus both), P = 5.5 × 10−12 (peripheral versus CNS) and P = 9.3 × 10−3 (both versus CNS). f, Correlation between CSF and plasma leptin levels. g, Schematic showing that leptin is secreted by adipose tissue and uses leptin receptor-mediated transport to cross the BBB. h, Enrichment for UniProt domains within the set of peripheral proteins with correlated CSF and plasma levels (r < 0.2). CP, choroid plexus; Ig, immunoglobulin; LDL, low-density lipoprotein; LepR, leptin receptor.
