Kininogen Level in the Cerebrospinal Fluid May Be a Potential Biomarker for Predicting Epileptogenesis

Abstract

Purpose: Epilepsy is a highly disabling neurological disorder. Brain insult is the most critical cause of epilepsy in adults. This study aimed to find reliable and efficient biomarkers for predicting secondary epilepsy. Materials and methods: The LiCl-pilocarpine (LiCl-Pilo) chronic epilepsy rat model was used, and rat cerebrospinal fluid (CSF) was collected 5 days after status epilepticus (SE). The CSF was analyzed using the label-free LC-ESI-Q-TOF-MS/MS. Differential expression of proteins was confirmed using enzyme-linked immunosorbent assay (ELISA) and Western blotting. The corresponding protein level in the CSF of patients with encephalitis in the postacute phase was determined using ELISA and compared between patients with and without symptomatic epilepsy after encephalitis during a 2-year follow-up. Results: The proteomics and ELISA results showed that the protein level of kininogen (KNG) was obviously elevated in both CSF and hippocampus, but not in serum, 5 days after the onset of SE in LiCl-Pilo chronic epilepsy model rats. In patients with encephalitis, the protein level of KNG in the CSF in the postacute phase was significantly elevated in patients with a recurrent epileptic seizure during a 2-year follow-up than in patients without a recurrent seizure. Conclusion: KNG in the CSF may serve as a potential biomarker for predicting epileptogenesis in patients with encephalitis.

Keywords: biomarker; encephalitis; epilepsy; epileptogenesis; kininogen; pilocarpine; proteomics.

Figure 1

Proteomic analysis of CSF in SD rats 5 days after SE. (A) The concentration of total proteins in the Naïve, LiCl and LiCl-Pilo groups. (B) The fold changes in proteins differentially expressed in the CSF of the three groups. The protein in the naïve group was normalized to 1.0. (C,D) Results of proteomics analysis.

Figure 2

Verification of the upregulation of KNG in CSF during early epileptogenesis. (A) The level of KNG in CSF using ELISA. (B) The level of KNG in the hippocampus using Western blotting. (C) The level of KNG in serum using ELISA. ^*p < 0.05, ^**p < 0.01, ^***p < 0.001.

Figure 3

CSF and serum KNG protein level of encephalitis patients and controls. (A) The level of KNG in CSF of encephalitis and control patients. (B) The level of KNG in serum of encephalitis and control patients. (C) The correlation of serum and CSF KNG levels in encephalitis patients. (D) The correlation of serum and CSF KNG levels in control patients. ^**p < 0.01.

Figure 4

Correlation between acute symptomatic seizure and KNG protein level in post-acute phase CSF/ serum. (A) The level of KNG in CSF of control and encephalitis patients with and without acute phase symptomatic seizure. (B) The level of KNG in serum of control and encephalitis patients with and without acute phase symptomatic seizure. ^*p < 0.05.

Figure 5

Correlation between post-acute phase CSF and serum KNG protein level and symptomatic epilepsy in 2 years. (A) The level of KNG in CSF of control and encephalitis patients with and without symptomatic epilepsy. (B) The level of KNG in serum of control and encephalitis patients with and without symptomatic epilepsy. ^*p < 0.05, ^**p < 0.01.