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

Abstract

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^lowCD16⁺). Among PWH, the median [IQR] CD4 nadir was 219 [32-531] cell/mm³; plasma HIV RNA (log₁₀) 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^lowCD16⁺ 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.

Keywords: Cerebrospinal fluids (CSF); Flow cytometry; HIV subtypes; Intermediate; Monocytes; Non-classical.

Fig. 1

Proportion of monocyte subsets in CSF and peripheral blood by HIV serostatus and HIV-1 subtype. Boxes show the medians and interquartile ranges and whiskers indicate the maximum and minimum values. Dots indicate the number of individuals in each group. Monocytes: CD14⁺⁺CD16⁻ (classical), CD14^lowCD16⁺ (non-classical), CD14⁺⁺CD16⁺ (intermediate). a Proportion of CD14⁺⁺CD16⁺ monocytes in the CSF and peripheral blood of individuals with HIV-1B or HIV-1C and PWoH analyzed within the CD45⁺-gated region. Pairwise comparisons were performed using Welchś t-test. ¹In CSF: HIV-1B vs. HIV-1C p = 0.03 and p = 0.10 after multiple testing correction using the BH method. P values were showed if p < 0.05. Blue dashed lines indicate mean ±two stand - ard deviations for PWoH (CSF: 0.47 ± 1.90; PB: 0.18 ± 0.28). b Proportion of monocyte subsets in the CSF and peripheral blood by HIV serostatus, analyzed within the CD64⁺ gated region. P-values were adjusted for age and sex in the adjusted model and then corrected for multiple testing using the BH method within the CSF and blood. c. Proportion of CD14⁺⁺CD16⁺ monocytes in the CSF and peripheral blood of the PWH and PWoH groups analyzed within the CD64⁺ gated region. Samples were categorized according to HIV RNA in the CSF and blood compartments. Statistical significance was set at p < 0.05. Blue dashed lines indicate mean ± two standard deviations for PWoH (CSF: 3.73 ± 16.06, PB: 4.34 ± 6.36). CSF and PB were compared using the Wilcoxon signed-rank test, and all p > 0.05; for the aviremic group not done

Fig. 2

Spearman’s rank correlation coefficients [ρ (95% CI)] for the proportions of CSF monocyte subsets in PWH, analyzed within the CD45⁺ gated region. Monocytes: CD14⁺⁺ CD16⁻ (classical), CD14⁺⁺ CD16⁺ (intermediate)