Background
Natural protection against CCR5-tropic HIV-1 variants is attributed to the presence of CCR5Δ32. We aimed to identify genetic and non-genetics and factors influencing CCR5 expression on CD4+ and CD8+ T cells and to assess the role of CCR5 expression in maintaining HIV control status and reservoir size in people living with HIV (PLHIV).
Methods
CCR5 expression on CD4+ and CD8+ T cell subsets was assessed using flow cytometry in PLHIV from the 2000HIV study (NTC03994835), divided into a discovery (n=1147) and validation (n=225) cohort. Part of inclusion were 114 HIV controllers (Elite controller (EC), viremic, (VC) and transient). The relationship of CCR5 expression with HIV- and non-HIV factors were assessed using Spearman’s rank correlation analysis. Genome-wide SNPs associated with CCR5 expression on CD4+ and CD8+ T cell subsets were analyzed using PLINK, with adjustments for age and gender. Significant associations were defined by a p-value < 5.32e-10 after multiple testing in the discovery cohort and a nominal P < 0.05 in the validation cohort. CCR5Δ32 was evaluated using RT-PCR. Viral reservoir size, measured as DNA copies/million CD4+ T cells, were also assessed.
Results
Percentages of CD4+ T cells subsets expressing CCR5 was positively correlated with age and CMV antibody titers and negatively with female sex and CD4 nadir. Fewer factors influenced CCR5 expression on CD8+ T cells subsets, with positive associations observed for age, CMV titers and ART duration (FDR < 0.05, discovery; p < 0.05, validation). In the 2000HIV study, 14.7% of the participants were heterozygous for the CCR5Δ32, with a higher prevalence in EC (25%) and VC (35.1%) than in transient (16.6%) and non-controllers (14.03%). The percentages of naïve and T regulatory cells expressing CCR5 was significantly lower in EC and VC than non-controllers. Genome-wide association analysis identified that rs113341849-A, located upstream CCR5 and CCR2, which co-occurs with CCR5Δ32, is linked to reduced CCR5 expression, both in terms of percentages and MFI, in a cell-type specific manner (Figure 1A). Finally, the presence of rs113341849-A and CCR5Δ32 was linked to a lower HIV reservoir size (Figure 1B) (p < 0.05 in both discovery and validation cohorts).
Conclusions
Our study shows that genetic and non-genetic factors contribute to CCR5 expression and subsequently to the maintenance of viral control and reservoir size. CCR5 blocking may be especially effective in older PLHIV, males and those with higher CMV reactivity.