Expression Of Chemokines In Cerebrospinal Fluid Of Patients With Neurosyphilis

Background:Syphilis is a chronic sexually transmitted disease caused by Treponema pallidum.In2015,WHO estimated that China had 3 million syphilis patients,accounting for 15%of the global syphilis patients.Approximately 10%of syphilis patients eventually develop neurosyphilis,causing a series of serious consequences such as dementia,consciousness disorder,blindness,paralysis,etc.,which is a great burden to the patients themselves,their families and society.Currently,the diagnosis of neurosyphilis is mainly based on clinical manifestations,serological antibody test,cerebrospinal fluid exam and other comprehensive judgments.Chemokines are a kind of small molecular cytokines,which can induce the biological effects of chemotactic inflammatory cells by binding to G protein coupled transmembrane receptors.According to the function of chemokines,chemokines are mainly divided into two categories:one is to promote inflammation and to promote immune cells to reach the inflammatory site;the other is promoting homeostasis,which is involved in the control of immune cell development and residence and migrationA large number of neurosyphilis patients have abnormal CSF examination,especially the immune cells invade the central nervous system through the disrupted blood-brain barrier,which makes the elevation of white-cell count and protein concentration.But the increase of white-cell count or protein concentration in CSF is not only seen in neurosyphilis,but also in many other central nervous system infections and autoimmune inflammatory diseases.In HIV infected patients,even if there is no obvious inflammatory reaction,the level of white cells and protein in CSF is also increased.It was previously reported by Wang et al.that only CXCL13,CXCL10 and CXCL8 were increased in CSF of neurosyphilis patients.Wang et al.conducted chemokine screening through a quantitative chemokine antibody array from Raybio Corp.,while Raybio Corp.also supplies a semi quantitative chemokine antibody array,and the chemokines detected by the two arrays are not identical.Objective:The increase of white cells in cerebrospinal fluid of neurosyphilis indicates the abnormal expression of chemokines,which functioned by chemotactic immune cell recruitment and residence.In our study,we intend to use Raybio semi quantitative chemokine antibody array to screen,and further study the abnormal expression of chemokine in cerebrospinal fluid of neurosyphilis patients,and its significance in assisting diagnosis of neurosyphilis.Methods:46 CSF and serum samples of syphilitic patients were collected from July 2017 to June 2019 in the Department of Dermatology,Second Affiliated Hospital of Zhejiang University,47 CSF and serum of non-neurosyphilis patients were set as control.The different expression of 38 chemokines between neurosyphilis and non-neurosyphilis patients were detected by Ray Bio~?Human Chemokine Antibody Array C1.The levels of CCL24 and CXCL7 in the CSF and serum of neurosyphilis and non-neurosyphilis patients were measured by Ray Bio~?CCL24 and CXCL7 ELISA kits.The expression of CXCL8 and CXCR1,besides of other chemokines and their receptors in CSF of neurosyphilis and non-neurosyphilis patients were compared by q RT-PCR.Results:A total of ninety-three CSF and serum samples of syphilitic patients were collected.The CSF levels of CCL24(p=0.0185)and CXCL7(p<0.0001),along with CXCL13(p<0.0001),CXCL10(p<0.0001)and CXCL8(p<0.0001)of neurosyphilis patients were increased compared with that of non-neurosyphilis patients.Both the levels of CCL24(6.082±1.137pg/ml,1.773±0.4565pg/ml,p=0.0037)and CXCL7(664.3±73.19pg/ml,431.1±90.54pg/ml,p=0.0118)were increased in the CSF of neurosyphilis patients.The CCL24 and CXCL7 were distributed through all stages of neurosyphilis(p>0.05),had moderate diagnostic performance for neurosyphilis(AUC of CCL24=0.791,AUC of CXCL7=0.6624).and were poorly correlated with CSF cell count(CCL24,r=0.2748,p=0.0645;CXCL7,r=-0.02615,p=0.8694),VDRL titer(CCL24,r=-0.02845,p=0.8903;CXCL7,r=0.08473,p=0.7077),and serum RPR titer(CCL24,r=0.06733,p=0.6641;CXCL7,r=-0.2196,p=0.1733).CXCL7 was positively correlated with CSF protein concentration(r=0.4436,p=0.0033).CCL24 was poorly correlated with CSF protein concentration(r=0.05484,p=0.7174).The expression of CXCL8(p=0.0209)and CXCR1(p=0.0429)in CSF of neurosyphilis was higher than that of non-neurosyphilis,while there was no significant difference in the expression of other chemokines and their receptors,including CCL24,CXCL7,CXCL13,CXCL10 and their receptors.Conclusion:In the CSF of neurosyphilis,CCL24,CXCL7,CXCL13,CXCL10 and CXCL8 were abnormal expressed in CSF of neurosyphilis.Elevated level of CCL24 and CXCL7 in CSF of neurosyphilis is the first report to our knowledge.No evidence was found about the increased chemokines in CSF of neurosyphilis,including CCL24,CXCL7,CXCL13,CXCL10,were direct released by white cells in CSF.The increase of CCL24 and CXCL7in cerebrospinal fluid of neurosyphilis may be the result of repeated penetration of blood-brain barrier by spirochetes,continuous injury of vascular endothelial cells and directly activation of platelets.It provides a new way to study the pathogenesis and treatment target of neurosyphilis...