Proteomics analysis of perilymph and cerebrospinal fluid in mouse.
OBJECTIVE
Proteins in perilymph may alter the delivery profile of implantable intracochlear drug delivery systems through biofouling. Knowledge of protein composition will help anticipate interactions with delivered agents.


METHODS
Analysis of mouse perilymph.


METHODS
Protein composition of perilymph and cerebrospinal fluid (CSF) was analyzed using a capillary liquid chromatography-mass spectrometry-based iTRAQ quantitative proteomics approach. We searched against a mouse subset of the Uniprot FASTA protein database. We sampled perilymph from the apex of the mouse cochlea to minimize CSF contamination.


RESULTS
More than 50 explicit protein isoforms were identified with very high confidence. iTRAQ reporter ions allowed determination of relative molar amounts of proteins between perilymph and CSF. Protein in perilymph was almost three times more concentrated than in CSF. More than one-third of the proteins in perilymph comprised protease inhibitors, with serpins being the predominant group. Apolipoproteins constituted 16%. Fifteen percent of the proteins were enzymes. Albumin was the most abundant single protein (14%). Proteins with relatively high perilymph/CSF ratios included broad-spectrum protease inhibitors and apolipoproteins.


CONCLUSIONS
Some proteins found in perilymph, such as albumin and HMW kininogen, have been implicated in biofouling through adsorption to device materials. The relatively large quantities of apolipoprotein and albumin may serve as a reservoir for acidic and lipophilic drugs. Alpha-2-glycoprotein can bind basic drugs.


CONCLUSIONS
Perilymph is similar in protein composition to CSF, though amounts are 2.8 times higher. Protease inhibitors comprise the largest category of proteins.
Charles Stark Draper Laboratory, Cambridge, Massachusetts, USA.
Erin E Leary
EE
Swan
Marcello
M
Peppi
Zhiqiang
Z
Chen
Karin M
KM
Green
James E
JE
Evans
Michael J
MJ
McKenna
Mark J
MJ
Mescher
Sharon G
SG
Kujawa
William F
WF
Sewell
D000818:Animals; D002555:Cerebrospinal Fluid / Q000737:chemistry*; D002853:Chromatography, Liquid; D008297:Male; D013058:Mass Spectrometry; D051379:Mice; D010498:Perilymph / Q000737:chemistry*; D040901:Proteomics