High-throughput proteomics and protein biomarker discovery in an experimental model of inflammatory hyperalgesia: effects of nimesulide.
OBJECTIVE
The goal of this study was to derive a systematic approach for the identification of protein species profiles that selectively identify subgroups of similar but distinct pain models and correlate with the therapeutic efficacy (or lack thereof) of drug intervention.


METHODS
Using high-throughput surface-enhanced laser desorption ionization (SELDI) mass spectrometry proteomic technology based on ProteinChip arrays, we conducted a comparative analysis of the profile of protein expression in cerebral spinal fluid (CSF) from rats exposed to either injection of complete Freund's adjuvant (CFA) [a model of inflammatory pain] or chronic constriction injury (CCI) [a model of neuropathic pain]. The CFA model was then further studied for the effects of treatment with the NSAID, nimesulide (a preferential cyclo-oxygenase [COX]-2 inhibitor).


RESULTS
Among other observations, we found that the content of two metal (copper) binding protein species (2.9 and 3.2kDa) and three anionic protein species (4.0, 6.9 and 8.2kDa) were increased in the CSF of rats with inflammatory pain in a time-dependent fashion, at 7 and 14 days after CFA injection. These changes were highly selective for the CFA model, as no detectable increase in these protein biomarkers was found in the CCI neuropathic pain model. Further, we found that most of the changes in the biomarker protein species induced by the inflammatory pain were prevented by treatment with nimesulide and correlated with the antihyperalgesic effect of this drug.


CONCLUSIONS
This study demonstrates that CSF biomarker profiles, as detected by SELDI technology, can consistently and reproducibly differentiate inflammatory from neuropathic pain, and reflect the analgesic action produced by the preferential COX-2 inhibitor, nimesulide. The characterisation and identification of these biomarkers will provide invaluable insight into the pathophysiology of pain mechanisms, in addition to further understanding of the value of nimesulide in the treatment of inflammatory pain.
D000704:Analysis of Variance; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002556:Cerebrospinal Fluid Proteins / Q000032:analysis* / Q000235:genetics; D003250:Constriction; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D004195:Disease Models, Animal; D005620:Freund's Adjuvant / Q000009:adverse effects; D006930:Hyperalgesia / Q000139:chemically induced* / Q000188:drug therapy*; D007249:Inflammation / Q000139:chemically induced / Q000188:drug therapy; D008297:Male; D010146:Pain / Q000175:diagnosis; D010147:Pain Measurement / Q000379:methods; D040901:Proteomics / Q000379:methods*; D051381:Rats; D017208:Rats, Wistar; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013449:Sulfonamides / Q000494:pharmacology*
D015415:Biomarkers; D002556:Cerebrospinal Fluid Proteins; D016861:Cyclooxygenase Inhibitors; D013449:Sulfonamides; D005620:Freund's Adjuvant; C012655:nimesulide