UC San Diego

BACKGROUND:The objective was to compare the effect of HIV-1C and HIV-1B subtypes on neurofilament light (NfL) CSF levels and ratios of NfL to tau proteins. Additional comparisons were performed between people with HIV (PWH), Alzheimer's Disease (AD), and HIV negative controls (HIV-).We also calculated the diagnostic characteristics of CSF NfL and ratios in HIV associated neurocognitive disorder (HAND) diagnosis. METHODS:CSF NfL, T-tau, and P-tau181 concentrations were measured using immunoassays in a total of 108 CSF samples, including PWH (n=68), HIV- (n=16), and AD (n=24). These proteins were compared between HIV-1B (n=27) and HIV-1C (n=26) using multiple linear regression adjusted for nadir CD4 and plasma viral load suppression. Comparisons between PWH, HIV-, and AD were adjusted for gender and age. RESULTS:CSF neurocytoskeleton proteins and their ratios were comparable in HIV-1B and HIV-1C. However the HIV-1C group had a higher proportion of samples of CSF NfL above the reference value (n=14, 53.85 %) than HIV-1B (n=8, 29.63 %), p=0.098. The values of CSF NfL were higher in the AD group [2578(1864;3500) pg/mL] compared to PWH [683(500;1197) pg/mL, p<0.001] and control [660(539;802) pg/mL, p=0.012] groups. The value of CSF NfL and ratios for HAND diagnosis was poor. CONCLUSION:The effects of HIV-1B and HIV-1C on CSF NfL and tau ratios were comparable. The differences in CSF neurocytoskeleton proteins between PWH and AD individuals suggested they might not share the same mechanisms of impairment. Further research is necessary to evaluate CSF NfL on the differential diagnoses of HAND with AD.