Increased CCL24 and CXCL7 levels in the cerebrospinal fluid of patients with neurosyphilis

Background: Monocytes are recruited into the cerebrospinal fluid (CSF) of patients with neurosyphilis, suggesting abnormal chemokine expression. We aimed to investigate the aberrant expression of chemokines in the CSF of these patients.

Methods: CSF and serum samples were collected from patients with neurosyphilis between July 2017 and June 2019 in the Dermatology Department, Second Affiliated Hospital of Zhejiang University. Differences in the expression of 38 chemokines between patients with and without neurosyphilis were detected using RayBio^® Human Chemokine Antibody Array C1. CCL24 and CXCL7 levels in the patients' CSF and serum were further measured using RayBio^® CCL24 and CXCL7 ELISA kits.

Results: Ninety-three CSF and serum samples of patients with syphilis were collected. Antibody array analysis showed that the CSF levels of CCL24 (P = .0185), CXCL7 (P < .0001), CXCL13 (P < .0001), CXCL10 (P < .0001), and CXCL8 (P < .0001) were significantly higher in patients with than without neurosyphilis. ELISA confirmed significantly higher CCL24 and CXCL7 levels in the CSF of patients with than without neurosyphilis (CCL24: 6.082 ± 1.137 pg/mL vs 1.773 ± 0.4565 pg/mL, P = .0037; CXCL7: 664.3 ± 73.19 pg/mL vs 431.1 ± 90.54 pg/mL, P = .0118). Increased CCL24 and CXCL7 expression was seen throughout all neurosyphilis stages, had moderate diagnostic efficiency for neurosyphilis, and correlated poorly with CSF cell count and Venereal Disease Research Laboratory titer. CSF CCL24 levels also correlated poorly with CSF protein concentration.

Conclusion: Abnormally high CSF chemokines levels may play a role in the pathogenesis of neurosyphilis.