Clinical Characteristics And Pathogenesis In Antibodies-associated-optic Neuritis And The Mechanism Research Of Promoting Remyelination In Central Nervous System

Objective:With the identification of MOG-IgG,people gradually realized optic neuritis had distinct clinical characteristics and pathologies with different serum antibodies.The unique features of MOG-ON remained unclear and had not been reported due to the small overall number of MOG-ON patients in cohorts and racial diversity.Therefore,we predominantly analyzed the unique clinical features and different pathology of MOG-ON.We use ELISA and iTRAQ methods to detect the serum and cerebrospinal fluid(CSF)separately,to study the differences in immunopathogenesis based on chemokine profile in AQP4-ON and MOG-ON,and to screen for proteins with significant differential expression between the two groups,providing more meaningful statistics for further validation and identification of biomarkers indifferent subtypes of ON,and contributing to explore the pathophysiological mechanism of different subtypes of ON.In addition,this subject will further study the molecular mechanism of which CXCL12 promote the differentiation of OPCs and contribute to the repair of myelin sheath in central nervous system.Our research would further verify the hypothesis by observing in vivo and vitro,trying to reveal the mechanism partially and provide new scientific evidence to promote the remyelination and improve prognosis.Methods:(1)Clinical data analysis was undertaken in adults with ON admitted between December 2014 and January 2016.Patients were classified into three groups based on aquaporin-4 antibody(AQP4-Ab)and MOG-Ab status:AQP4-ON,MOG-ON and seronegative-ON.In addition,patients diagnosed with CRION were recruited from December 2015 to April 2017.Based on antibody status,they were assigned to either the MOG-CRION or seronegative-CRION groups.(2)We measured 52 cytokines/chemokines using ELISA in 59 serum samples,which were divided into three groups according to serum antibodies status:HCs,AQP4-ON and MOG-ON.We further screened and compared the different proteins in CSF samples with different antibodies using iTRAQ-based protein identification/quantification approach.(3)Over-expression of CXCL12 in spinal cord(SC)of lewis rat by injected AAV9/CXCL12-GFP after surgery of intrathecal catheter implantation.Then EAE were induced,behavior test and immunofluorescent staining were used to evaluate the effect of Up-regulation of CXCL12.in vitro,oligodendrocyte precursor cells(OPCs)were separated and culture with CXCL12,immunofluorescent staining for function detecting.Results:(1)76%in the MOG-ON group showed good visual recovery(>20/40)in the final visit,which is statistically better than that in the AQP4-ON and seronegative-ON groups.9.5%of adults with ON showed dependency on steroid,which was particularly prominent in the MOG-ON group(35.5%).A larger proportion of canalicular segment involved in MOG-ON adults.A total of 33 CRION patients(38 eyes)were assessed,and 81.8%of them were adults(≥18 years).76.3%of affected eyes showed severe visual loss(<20/200)duringthe first optic neuritis episode,and 72.5%demonstrated good visual recovery(>20/40)during the final follow-up.The intraorbital and canalicular segments were highly involved in the orbital MRI of CRION patients.During the final follow-up,MOG-CRION patients had more bilateral involvement and higher annualised relapse rates compared with the seronegative-CRION patients.(2)Eleven of 52 measured serum cytokine/chemokines(CCL22/MDC,CCL13/MCP-4,CCL21/6Ckine,CCL27/CTACK,CCL8/MCP-2,CXCL14/BRAK,Contactin-1,Kallilrein 6/Neurosin,Midkine,VCAM-1 and Fas)were significantly different between MOG-ON group and controls.Ten of 52 measured serum cytokine/chemokines(CCLI/I-309,CCL22/MDC,CCL28,CCL17/TARC,CCL27/CTACK,CXCL2/GRO beta Contactin-1,Midkine,Chemerin and Synuclein-alpha)were significantly different between AQP4-ON group and controls.C5/C5a and Midkine were significantly higher in AQP4-ON group compared to MOG-ON group.180 different proteins were identified between AQP4-ON and MOG-ON group,including 99 upregulated proteins and 81 downregulated proteins.The involved pathways included complement and coagulation cascades and microbial metabolism in diverse environments.(3)CXCL12-GFP was overexpressed in lumbar enlargement of spinal cord by AAV.Over-expression of CXCL12 can significantly alleviated clinical scores and symptoms by inhibited leukocyte infiltration and protected myelin sheath in each stage of EAE.Regular addition of AMD3100,an CXCR4 antagonist,reversed the protection of CXCL12.In vitro,lOng/ml CXCL12 could promoted the differentiation of OPCs into olgodendrocytes.Moreover,we also found a proportion of NG2+OPCs co-express the CXCL 12 or CXCR4.Conclusion:(1)MOG-ON had the smallest proportion of acute demyelinating ON in Chinese adults.One third of adults with MOG-ON predominantly showed a substantial dependency on steroids and relapse on steroid reduction or cessation,which rarely presented in AQP4-ON and seronegative-ON adults.CRION was predominantly found in adults with unilateral ON and exhibited a higher rate of seropositive MOG-IgG.MOG-CRION,which may be a disparate subtype of MOG-IgG-induced demyelinating disease that needs further investigation,was found in younger patients at onset,with more bilateral involvement and more relapse tendency.(2)Our findings suggest that the differences of mean concentration in CXCL6/GCP-2,Midkine and C5/C5a probably reveal different immunologic mechanism between AQP4-ON and MOG-ON group.This cytokine/chemokine profiling provides new insight into NMO pathogenesis associated with MOG antibody seropositivity and provides guidance to monitor inflammation and response to treatment in a way.In addition,we screened more different proteins and the pathways,and verified the different roles of complement and coagulation cascades between the two groups,which contributing to the exploration of pathology in different subtypes of ON.(3)Over-expression of CXCL12 in the CNS by AAV9 can alleviated the clinical scores of EAE,significantly decreased infiltration of leukocytes in peak stage of EAE.In vitro,CXCL12 can promoted the maturation and differentiation of OPCs into oligodendrocytes.Our data indicated that CXCL12 effectively protected white matter in SC and inhibited the syndromes of EAE.In summary,our research studied the unique clinical characteristics and pathology of MOG-ON with other types of optic neuritis,and further verified the weaker role of complement and coagulation cascades in MOG-ON,contributing to investigate the potential biomarkers and different pathologies with different ON subtypes.In addition,our study found that CXCL12 could promote the regeneration of myelin sheath by promoting the differentiation and maturation of OPCs,which accumulated new scientific evidence for exploring possible ways to promote remyelination and improve the visual prognosis of patients.