| Background and purposeNeuromyelitis optica(NMO)is an autoimmune demyelinating disease in the central nervous system(CNS)mainly involving optic nerve and spinal cord,mediated mainly by humoral immunity and widely involving cellular immunity.In 2015,Wingerchuk formally put forward to the international diagnostic criteria for neuromyelitis optica spectrum disorder(NMOSD).The prevalence rate is about 1 to5cases per 100,000 population one year,the non-Caucasus is susceptible to the disease,and the majority is young and middle-aged women with high recurrence rate and disability rate.At present,the traditional treatment methods cannot effectively control the recurrence and progress of the disease,so it is urgent to explore new targets for immunotherapy.Follicular helper T cells(Tfh)was a new CD4~+T cell subset found in human tonsil.It played a key role in the germinal center(GC)formation in secondary lymphoid,differentiation of B cells into plasma cells as well as memory cells and antibodies production.Therefore,the number and the balance of function of Tfh cells is essential in humoral immunity,and excessive activation of Tfh cells or over expression of related molecules can lead to all kinds of autoimmune diseases.Studies had shown that Tfh cells and Tfh cell related molecules were involved in the pathogenesis of immune diseases.Tfh cells express a variety of immune markers,including transcription factor B cell lymphoma 6(Bcl-6),chemokine CXC motif receptor 5(CXCR5),programmed death-1(PD-1),inducible T-cell costimulatory(ICOS),CD40 ligand(CD40L)and other molecules,and also secreting cytokines such as IL-21,IL-4,in which Tfh cell subtype expressing CD4,CXCR5 and PD-1molecules represents one of phenotypes of Tfh cells in circulating blood.Chemokine C-X-C motif ligand 13(CXCL13),also known as B lymphocyte chemoattractant-1(BLC-1),is one of the important members of the chemokine family,playing an important role in the development,the migration and accumulation of B cells in secondary lymphoid tissue.At the same time,it is indicated that CXCL13 can be used as a plasma marker of germinal center,which could reflect the effect of the humoral immunity of B cells helped by Tfh cells.In this study,we detected the proportion of CD4~+CXCR5~+PD-1~+Tfh cells in peripheral blood and plasma CXCL13 levels in patients with NMOSD,and analyzed the relationship between Tfh cell,CXCL13 and stages,subtypes and the clinical features of the disease,and the correlation and mechanisms of interaction between Tfh cell and CXCL13,discussing the role of circulating Tfh cells and serum CXCL13in the pathogenesis and relapse of NMOSD to provide the basis in searching for new immune-therapy targets.Methods:Collect peripheral blood and serum of patients with NMOSD admitted to the the Department of Neurology in the First Affiliated Hospital of Zhengzhou University from October 2016 to December 2017,gathering the clinical data and laboratory examination results of patients,including 30 NMOSD cases in acute stage and 26NMOSD cases in remission stage,other non-inflammatory neurological diseases cases(ONND group)including 8 cases of transient ischemic attack(TIA),5 cases of benign paroxysmal positional vertigo(BPPV),4 cases of idiopathic epilepsy and 3cases of multiple system atrophy.20 healthy volunteers(health control,HC)in the same period of the hospital were used as the control group.The ratio of CD4~+CXCR5~+PD-1~+Tfh cells in peripheral blood and levels of CXCL13 in serum were measured by flow cytometry and enzyme-linked immunosorbent assay(ELISA),respectively.SPSS24 software was used to deal with data,and quantitative data was expressed in the form of mean±standard deviation or median(P25,P75).The?~2 test was used to compare the categorical data.The comparison of quantitative data was performed by two independent samples t test.When analyzing multiple groups of quantitative data,ANOVA or Kruskal-Wallis methods were used,then comparisons between the two groups were conducted.When P<0.05,the difference is statistically significant.Results:1.Comparison of the proportion of Tfh cells in peripheral blood among NMOSD group,ONND group and control groupThe proportion of peripheral blood CD4~+CXCR5~+PD-1~+Tfh cells in acute NMOSD group,remittent NMOSD group,ONND group and HC group were,respectively,(10.38±3.81)%,(6.07±2.03)%,(5.57±2.42)%and(3.95±2)%,the difference was statistically significant(P<0.001),and the proportion of peripheral blood CD4~+CXCR5~+PD-1~+Tfh in acute group was significantly higher than that in remission group,ONND group and HC group(P<0.01,P<0.001,P<0.001).2.Comparison of serum CXCL13 levels among NMOSD group,ONND group and control groupSerum CXCL13 levels in acute NMOSD group,remittent NMOSD group,ONND group and HC group were respectively 233.57±116.81pg/ml,158.64±61.08pg/ml,71.80±31.97pg/ml,46.10±24.48pg/ml,they had a significant statistical difference,and the levels in acute phase and remittent phase of NMOSD group were higher than that in ONND group and HC group(P<0.001,P<0.001;P<0.01,P<0.001).3.The relationship between the proportion of Tfh cells in peripheral blood,serum CXCL13 levels and AQP4 antibody,myelopathy in patients with NMOSDIn NMOSD acute and remittent stages,blood Tfh cell ratio and serum CXCL13levels of AQP4-IgG(+)group were significantly higher than that of AQP4-IgG(-)group,(P=0.001,P=0.013;P=0.047,P=0.049).And the both in patients with long segment spinal cord lesions(segmental lesions?3)were obviously higher than that of short segment spinal cord lesions(segmental lesions<3)during acute and remittent phases.(P<0.001,P=0.003;P<0.001,P=0.003).4.The correlation between the proportion of Tfh cells in peripheral blood and the levels of serum CXCL13 in patients with NMOSDIn NMOSD acute and remission phases,blood Tfh cells ratio and serum CXCL13 levels were positively correlated,and they had a significant statistical difference(r=0.796,P<0.01;r=0.736,P<0.01).5.The correlation between the proportion of Tfh cells in peripheral blood,the levels of serum CXCL13 and the scores of EDSS and ARR in patients with NMOSDThe proportion of Tfh cells in peripheral blood and serum CXCL13 levels of NMOSD patients in acute stage were both positively correlated with EDSS scores,(r=0.688,P<0.001;r=0.740,P<0.001).There was a positive correlation between Tfh cells ratio and EDSS scores in remission period(r=0.464,P=0.017),but there was no significant relationship between CXCL13 levels and EDSS scores(r=0.148,P=0.469).The proportion of Tfh cells in peripheral blood and serum CXCL13 levels were both positively correlated with ARR in acute phase of NMOSD(r=0.522,P=0.003,r=0.503,P=0.005).There was a positive correlation between Tfh cells ratio and ARR in remission period(r=0.429,P=0.029),but there was no significant relationship between serum CXCL13 levels and ARR(r=0.304,P=0.131).6.The correlation between the proportion of Tfh cells in peripheral blood,serum CXCL13 levels and CSF protein and cell number in patients with acute NMOSDThe blood proportion of Tfh cells and serum CXCL13 levels were both positively correlated with cerebrospinal fluid protein content in acute NMOSD patients,and they had a significant statistical difference(r=0.543,P=0.005;r=0.467,P=0.019).There was no obvious relationship between the cell number of cerebrospinal fluid and the two(r=0.299,P=0.147;r=0.112,P=0.595).Conclusion:1.Peripheral blood Tfh cells and serum CXCL13 are involved in the pathogenesis of NMOSD,and they are associated with disease activity which can be used as biomarkers of NMOSD.2.CXCL13 may be used as a biological marker of Tfh cells and B cells immune activity,indicating that Tfh-B cells disorder is a key link in the pathogenesis of NMOSD.3.Peripheral blood Tfh cells and serum CXCL13 are can be used as indicators of disease severity,characteristics of lesions and prognosis.4.Peripheral blood Tfh cells and serum CXCL13 may participate in the pathogenesis of the disease through enhancing the immune response of central nervous system. |
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