Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 2017 05 19() doi 10.1093/cid/cix473
HIV-infected individuals with previous syphilis have cognitive impairment. We tested the hypothesis that neurosyphilis causes cognitive impairment in HIV by amplifying HIV-related CNS inflammation.
132 HIV-infected participants enrolled in a study of CSF abnormalities in syphilis underwent the mental alternation test (MAT), venipuncture and lumbar puncture. CSF concentrations of chemokine (C-X-C motif) ligand 10 (CXCL10), chemokine (C-C motif) ligand 2 (CCL2) and neurofilament light (NFL) were determined by commercial assays. The proportion of peripheral blood mononuclear cells (PBMCs) and of CSF white blood cells (WBCs) that were activated monocytes (CD14+CD16+) was determined by flow cytometry. Neurosyphilis was defined as detection of T. pallidum 16S RNA in CSF or CSF white blood cells (WBCs) >20/ul or a reactive CSF-Venereal Disease Research Laboratory (VDRL) test; uncomplicated syphilis was defined as undetectable CSF T. pallidum, CSF WBCs ≤5/ul and nonreactive CSF-VDRL. MAT <18 was considered low. Results
Median proportion of PBMCs that were activated monocytes (16.6 vs. 5.3), and median CSF CXCL10 (10,658 vs. 2,530 units), CCL2 (519 vs. 337 units) and HIV RNA (727 vs. 50 c/ml) were higher in neurosyphilis than in uncomplicated syphilis (P≤0.001 for all comparisons). Neurosyphilis was not related to low MAT scores. Participants with low MAT scores had higher median CSF CXCL10 (10,299 vs.3,650 units, P=0.008) and CCL2 (519 vs. 365 units, P=0.04) concentrations than those with high MAT scores.
Neurosyphilis may augment HIV-associated CNS inflammation, but it does not explain cognitive impairment in HIV-infected individuals with syphilis.