NEFL and neurosyphilis: Although it has been showed that using some found novel diagnostic biomarkers, such as C–X–C motif chemokine 13 [70, 71], CSF migration inhibitory factor [72], CSF soluble triggering receptor expressed on myeloid cells 2 [73], circulating brain-enriched GFAP, NFL, and UCH-L1 levels [74] in CSF, can assist to diagnose neurosyphilis, exploring reliable blood biomarker indicators is more convenient and acceptable to collect for diagnosing neurosyphilis.