Cerebrospinal fluid CD14++CD16+ monocytes in HIV-1 subtype C compared with subtype B

CD14(++)CD16(+) monocytes are susceptible to HIV-1 infection, and cross the blood-brain barrier. HIV-1 subtype C (HIV-1C) shows reduced Tat protein chemoattractant activity compared to HIV-1B, which might influence monocyte trafficking into the CNS. We hypothesized that the proportion of monocytes in CSF in HIV-1C is lower than HIV-1B group. We sought to assess differences in monocyte proportions in cerebrospinal fluid (CSF) and peripheral blood (PB) between people with HIV (PWH) and without HIV (PWoH), and by HIV-1B and -C subtypes. Immunophenotyping was performed by flow cytometry, monocytes were analyzed within CD45 + and CD64 + gated regions and classified in classical (CD14(++)CD16(-)), intermediate (CD14(++)CD16(+)), and non-classical (CD14(low)CD16(+)). Among PWH, the median [IQR] CD4 nadir was 219 [32-531] cell/mm(3); plasma HIV RNA (log(10)) was 1.60 [1.60-3.21], and 68% were on antiretroviral therapy (ART). Participants with HIV-1C and -B were comparable in terms of age, duration of infection, CD4 nadir, plasma HIV RNA, and ART. The proportion of CSF CD14(++)CD16(+) monocytes was higher in participants with HIV-1C than those with HIV-1B [2.00(0.00-2.80) vs. 0.00(0.00-0.60) respectively, p = 0.03 after BH correction p = 0.10]. Despite viral suppression, the proportion of total monocytes in PB increased in PWH, due to the increase in CD14(++)CD16(+) and CD14(low)CD16(+) monocytes. The HIV-1C Tat substitution (C30S31) did not interfere with the migration of CD14(++)CD16(+) monocytes to the CNS. This is the first study to evaluate these monocytes in the CSF and PB and compare their proportions according to HIV subtype.

Automated summary

This study investigated the proportion differences of monocytes in cerebrospinal fluid (CSF) and peripheral blood (PB) between individuals with HIV-1C and HIV-1B subtypes, and found a higher proportion of CD14(++)CD16(+) monocytes in the CSF of HIV-1C patients. Furthermore, despite viral suppression, the total monocyte proportion in PB increased in people with HIV due to the increase in CD14(++)CD16(+) and CD14(low)CD16(+) monocytes.