Research On Biomarkers Related To Clinical Phenotype And Prognosis Of Amyotrophic Lateral Sclerosis In Cerebrospinal Fluid

Objective To compare the expression of protein in cerebrospinal fluid(CSF)between bulbar-and spinal-onset amyotrophic lateral sclerosis(ALS)so as to find biomarkers for ALS and explore the underlying mechanisms of different subtypes of ALS.Methods The participants were divided to ALS group and controls,and the ALS group was further classified to bulbar-onset ALS(BO)and spinal-onset ALS(SO).In order to discovery potential biomarker candidates,we recruited 4 bulbar-onset ALS patients,5 spinal-onset ALS patients,and 5 controls and applied tandem mass tag(TMT)labeling combined with multidimensional solid phase/liquid chromatography tandem mass spectrometry(LC-MS/MS)analysis.And then 12 bulbaronset ALS patients,34 spinal-onset ALS patients,and 34 controls were selected according to inclusion criteria for enzyme-linked immunosorbent assay(ELISA)to further validate.The CSF levels of biomarker candidates between different groups were compared and the discriminatory performance was evaluated by a receiver operating characteristic(ROC)curve analysis.To hunt for factors influencing the levels of candidate biomarkers by linear regression and affecting ALS survival through Cox regression analysis.Results 1.The results of proteomic analysis showed that 78 proteins were found significantly altered in ALS patients compared to controls.The differential proteins between BO and SO were primarily enriched in the biological process of positive regulation of immune response and regulation of defense response,and involved in hsa05322 Systemic lupus erythematosus and hsa05168 Herpes simplex virus 1 infection.2.Five promising biomarker candidates were selected for further ELISA validation.It was found that the CSF level of Lipopolysaccharidebinding protein(LBP)in ALS is higher than that in controls,especially in BO.And it showed a great discriminatory performance for ALS.There was a positive correlation between ALSFRS-R and the elevated expression of LBP.3.Another result of ELISA validation is that the CSF levels of HLA class II histocompatibility antigen,DR alpha chain(HLA-DRA)was specifically elevated in BO vs SO as there was no statistical difference in CSF HLA-DRA level between ALS and controls.Increasing HLA-DRA expression was correlated with decreased survival.Conclusion 1.The LBP in CSF was considered as diagnostic biomarker of ALS and the CSF HLA-DRA was a specific biomarker of bulbar-onset ALS.2.The level of HLA-DRA in CSF was negatively correlated with the survival of ALS.3.The CSF LBP and HLA-DRA were novel prognostic biomarkers for ALS.4.Neuroinflammation and dysbiosis of gut microbiome may be differentially involved in ALS phenotypes.