CXCL13 and TH1/Th2 cytokines in the serum and cerebrospinal fluid of neurosyphilis patients

Abstract

Neurosyphilis is a chronic infectious disease with involvement of central nervous system infection by Treponema pallidum. This study was to investigate the contents of B lymphocyte chemokine 1 (BLC-1/chemokine [C-X-C motif] ligand 13), Th1 cytokines (Interleukin [IL]-2, IL-12, and Interferon [IFN]-γ), and Th2 cytokines (IL-6 and IL-10) in serum and cerebrospinal fluid (CSF) of HIV-negative patients with neurosyphilis before and after treatment, aiming to elucidate roles of CXCL13 and Th1/Th2 cytokines in immune response to and pathogenesis of neurosyphilis.Enzyme-linked immunosorbent assay was employed to detect the contents of CXCL13, IL-2, IL-12, IFN-γ, IL-6, and IL-10 in serum and CSF of 47 HIV-negative patients with neurosyphilis, 36 syphilis patients without neurological involvement and 23 controls (noninfectious intracranial disease) before, 3 and 12 months after treatment with high dose penicillin.Results showed that there was no significant difference in blood CXCL13 content among 3 groups (P > .05); CSF CXCL13 content in neurosyphilis patients was significantly higher than in other 2 groups (P < .001), and positively related to leucocyte count, protein concentration, and IgG index. IL-6 and IL-10 contents of the serum and CSF in neurosyphilis patients were markedly higher than in other 2 groups (P < .05 or .01), but IL-2, IL-12, and IFN-γ of the serum and CSF were significantly lower than in other 2 groups (P < .05 or .01). The IL-6, IL-10, IL-2, IL-12, and IFN-γ contents of the serum and CSF were comparable between control group and syphilis group (P > .05). CSF CXCL13 content was positively related with IL-6 and IL-10 content, while negatively related to IL-12 content in neurosyphilis patients. CSF IL-6 content was negatively related with IL-12 content. In neurosyphilis patients, the CSF CXCL13 content reduced significantly at 3 and 12 months (P < .001), the CSF IL-2 and IL-12 contents increased significantly at 12 months, and CSF IL-6 contents reduced significantly at 12 months after treatment (P < .05 or .01).It is concluded that neurosyphilis patients did not have normal immune function. CXCL13 and Th1/Th2 cytokines are involved in the immune response of neurosyphilis patients. CSF CXCL13 and Th1/Th2 cytokines contents may be used for the diagnosis and evaluation of therapeutic efficacy of neurosyphilis.

Figure 1

Correlation between CSF CXCL13 and CSF leukocyte count. CSF CXCL13 content was positively related to CSF leukocyte count (Spearman correlation analysis, r = 0.3245, P = .0261).

Figure 2

Correlation between CSF CXCL13 and CSF protein concentration. CSF CXCL13 content was positively related to protein concentration (Spearman correlation analysis, r = 0.5435, P < .0001).

Figure 3

Correlation between CSF CXCL13 and CSF IgG index. CSF CXCL13 content was positively related to IgG index (Spearman correlation analysis, r = 0.7500, P < .0001).