Proteomic Analysis Of The Differential Protein Expression In The Human Cerebrospinal Fluid After Acute Traumatic Brain Injury

Traumatic brain injury (TBI) is a serious clinical problem associated with a high mortality rate and high disability rate . TBI patients are usually initially assessed by the Glasgow Coma Score (GCS) on hospital admission and during routine neurologic examinations in the acute phase of care. Conventional diagnosis of TBI is dependent on neuroimaging techniques such as computed tomography (CT) scanning, magnetic resonance imaging (MRI) and single-photon emission CT scanning(SPECT). Though, the current TBI diagnostic means are valuable in the assessment of the TBI patient's general brain functional status,there still are lacking in the ability to precisely define and quantify the actual intensity of the brain injury during the first hours and days after injury, at a time when therapeutic intervention is most likely to be effective.So some biomarkers of proven clinical utility for TBI are needed.The recent studies have suggested that primary TBI initiates a cascade of molecular and cellular events which include changes in gene and protein expression, resulting in neurons dysfunction and/or death. Proteomics is a science and methodology of the study of the proteome, which include all proteins expressed in a particular cell or tissue in a special time point. SELDI-TOF (surface-enhanced laser desorption/ionization time of flight) mass spectrometry has been prover to be one of the recently developed sophisticatedtechnologies, which, based on capturing proteins/peptides by chemically modified surface, is specifically powerful for analyzing the complex biological samples. We had applied this technology in analyzing the CSF proteins to discover relevant TBI protein biomarkers Materials and MethodsNinteen cerebrospinal fluid samples(including 9 acute severe TBI case and 9 acute mild TBI) and three self-pairs cerebrospinal fluid acute severe TBI (at the different post-trauma time-point) were detected by SELDI-TOF-MS. Our method analyzing all the data relies on the undecimated discrete wavelet transform (UDWT) as a first step to denoise of spectra. After denoising, the spectra performed baseline correction and Mass calibration The proteomic peaks detected and quantified by an algorithm locates all local maxima height in each denoised, baseline-corrected, calibrated spectrum. The matched peak across spectra is defined as peaks cluster. The spectra that do not have a peak within a given cluster will be assigned a maximal height in the cluster for the peak. The normalization is performed only by the identified peak clusters.All these processing were performed by the Cancer Institute of ZheJiang University - ProteinChip Data Analysis System (ZUCI-PDAS, www.zlzx.net) designed by Yu Jiekai based on MATLAB Web Server 1.2.4 (The MathWorks Inc., Natick MA). Using SELDI-TOF-MS, we expect to find out new protein biomarkers to be detected and monitored in cerebrospinal fluids ,It can provide confirmation of the severity of injury related to the levels of clinical markers, monitor pathological procedures progress and identify drug therapy targets. Results1 .Among the total(25) of protein peaks detected, the relative intensity of 10 protein peaks was shown to be differentially altered on H4 chips in CSF between severe TBI group and mild TBI injury group(P<0.05). there were 9 protein peaks that showed the increase of protein expression and only 1 protein peak that showed the reduction of protein expression in CSF of severe TBI group.2. There were 10 peaks detected for discriminating severe TBI from mild TBI The peaks were between 2k and 20k Da. Peaks with a mlz <2kDa were mainly ion noise form the matrix and therefore should be excluded. The discriminant pattern combined with the mlz of the 2 candidate biomarkers were 8571 m/z,5408 mlz, separating severe TBI from mild TBI with the specificity of 100%, sensitivity of 100% .3. In the three self-pairs cerebrospinal fluid of acute severe TBI (at the different time-point post-trauma), The protein peak 8605 were reduced at 24 h and 72 h after injury .which showed some CSF protein expression in different levels on the progress of severe TBI.Conclusion:1 .The alteration of protein expression patterns in CSF could be induced after brain injury..The protein expression patterns of severe TBI group and mild TBI group in CSF are different,2. . The discriminant pattern combined with the mlz of the 2 candidate biomarkers are 8571 > 5408, separating severe TBI patients from mild TBI with the specificity of 100%, sensitivity of 100% <>3. Variable changes in the expression of the proteins takes place of severe TBI group. At the time point 24h -. 48h and 72h post trauma, since the primarybrain injury, The protein peak 8605 were reduced continuouslyo4. Our study results confirm that the different severity of TBI may make the protein expression level changes with proteomic technique. The proteins expressing in different levels will make different influence on the progress and prognosis of TBI. These differential proteins may become the target in future research. They could be biomarkers of brain injury and be regarded as useful for molecular, diagnosis or therapy of brain injury.