Cerebrospinal Fluid Biomarkers For Epileptogenesis

BACKGROUND & PURPOSE:Epilepsy is a highly disabling neurologic disorder.In adults,epilepsy is usually secondary to various brain insults.There is an urgent need to early identify patients at high risk of epilepsy after brain insults before recurrent seizure attacks.Therefore,it is of great clinical importance to find reliable and efficient biomarkers for epilepsy.METHODS:LiCl-pilocarpine chronic epilepsy SD rat model was applied in our study.On fifth day from status epilepticus induced by pilocarine(ie,the epileptogensis period or the latent period),rat cerebrospinal fluid(CSF)was collected.Twelve rats displayed spontaneous recurrent seizure(grade 2 or severer)in 24 hour video monitoring was recruited in LiCl-Pilocarpine group.Twelve sham-modeling LiCl group rats and eight Na?ve group rats were also used.All 32 CSF samples were processed for analyse by label-free LC-ESI-Q-TOF-MS/MS.The differentially expressed protein was confirmed by Elisa and the protein level of interested and its offspring proteins were tested by western blot.To further verify its possibility as biomarker for epileptogenesis,encephalitis patients were recruited and post-acute phase CSF was collected.Patients were followed up for two years to find out if they had sympatomatic epilepsy.The protein level of post-acute phase in CSF between patients with and without epilepsy after encephalitis was compared by Elisa.RESULTS:The overall protein level of CSF 5 days after status epilepticus induced by pilocarpine were not significantly elevated compared with control.All 32samples(12 LiCl-Pilocarpine CSF,12 LiCl group CSF and 8 Na?ve group CSF)was analysed by proteomics.Among 146 proteins identified,glyceraldehyde-3-phosphate dehydrogenase(GAPDH),T-Kininogen 1,T-Kininogen 2,lactate dehydrogenase(LDH),alpha 1 acid glycoprotein and adenylate kinase isoenzyme 1(AK1)were differentially expressed with significance(significance-10 lg P>15).However,only T-kininogen and alpha1 acid glycoprotein were obvious elevated in LiCl-Pilocarpine CSF than LiCl and Na?ve CSF,which provided possibility as a candidate for biomarker of epileptogenesis.In this study,we chose kininogen as further study target.Elisa was conducted to confirm the result that kininogen was elevated in CSF 5 days after status epilepticus induced by pilocarpine.At the same time point,the protein level of kininogen was also elevated in hippocampus and is independent of its change in serum,which implied that the elevated kininogen should be mainly synthesised in brain.In epileptogenesis period in our model,the protein level of bradykinin B1 receptor and B2 receptor were not significantly changed compare with controls.Among three nitric oxide synthases(NOS),offspring proteins regulated by bradykinin receptors,endothelial NOS and inducible NOS were obviously reduced.To investigate the possibility of kininogen as a biomarker for epileptogenesis,we recruited 12 encephalitis and 5 control patients.Kininogen in post-acute phase CSF was significantly elevated in encephalitis patients developed epilepsy in 2 years follow-up than that in patients without epilepsy.CONCLUSIONS:Protein level of kininogen was elevated in LiCl-pilocarpine rat CSF in epileptogenesis period and post-acute phase CSF of patients with epilepsy after encephalitis.Kininogen might be a candidate for biomarker of epileptogenesis.Further study is needed to confirm this finding.