Cerebrospinal fluid secretory Ca2+-dependent phospholipase A2 activity is increased in Alzheimer disease.
BACKGROUND
The phospholipase A(2) (PLA2) family comprises multiple isoenzymes that vary in their physicochemical properties, cellular localizations, calcium sensitivities, and substrate specificities. Despite these differences, PLA2s share the ability to catalyze the synthesis of the precursors of the proinflammatory mediators. To investigate the potential of PLA2 as a biomarker in screening neuroinflammatory disorders in both clinical and research settings, we developed a PLA2 assay and determined the predominant types of PLA2 activity in cerebrospinal fluid (CSF).


METHODS
We used liposomes composed of a fluorescent probe (bis-Bodipy FL C11-PC [1,2-bis-(4,4- difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-undecanoyl)-sn-glycero-3-phosphocholine]) and 1,2-dioleoyl-l-alpha-phosphatidylcholine as a substrate to measure CSF PLA2 activity in a 96-well microtiter plate format. We established the type of CSF PLA2 activity using type-specific inhibitors of PLA2.


RESULTS
Using 5 microL CSF per assay, our PLA2 activity assay was reproducible with CVs <15% in 2 CSF samples and for recombinant secretory Ca(2+)-dependent PLA2 (sPLA2) in concentrations ranging from 0.25 to 1 micromol/L. This PLA2 assay allowed identification of sPLA2 activity in lumbar CSF from healthy individuals 20-77 years old that did not depend on either sex or age. Additionally, CSF sPLA2 activity was found to be increased (P = 0.0008) in patients with Alzheimer disease.


CONCLUSIONS
Adult human CSF has sPLA2 activity that can be measured reliably with the assay described. This enzyme activity in the CSF is independent of both sex and age and might serve as a valuable biomarker of neuroinflammation, as we demonstrated in Alzheimer disease.
Chalbot
Sonia
S
New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314-6399, USA.
Zetterberg
Henrik
H
Blennow
Kaj
K
Fladby
Tormod
T
Grundke-Iqbal
Inge
I
Iqbal
Khalid
K
D000328:Adult; D000368:Aged; D000544:Alzheimer Disease / Q000134:cerebrospinal fluid / Q000201:enzymology*; D015415:Biomarkers / Q000134:cerebrospinal fluid; D002118:Calcium / Q000502:physiology*; D005456:Fluorescent Dyes; D006801:Humans; D008875:Middle Aged; D010713:Phosphatidylcholines; D054497:Phospholipases A2, Secretory / Q000134:cerebrospinal fluid*; D012016:Reference Values; D055815:Young Adult
C095153:1,2-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diazaindacene-3-dodecanoyl)-sn-glycero-3-phosphocholine; D015415:Biomarkers; D005456:Fluorescent Dyes; D010713:Phosphatidylcholines; D054497:Phospholipases A2, Secretory; C017251:1,2-oleoylphosphatidylcholine; D002118:Calcium