Background
Long-term antiretroviral therapy (ART) in people with HIV (PWH) has been related to reduced levels of competent proviruses. We aimed to evaluate how time on ART affects reservoir size, reactivation capacity and cytotoxic response.
Methods
Cross-sectional study with 64 PWH who were on ART for <1 year (<1y)(n=11), 1 to 10 years (1-10y)(n=20), 10 to 20 years (10-20y)(n=16), and >20 years (>20y)(n=17). HIV-1 reservoir size was quantified by ddPCR in peripheral blood mononuclear cells (PBMCs). Proviral reactivation was analyzed by flow cytometry in purified CD4+ T cells using anti-p24-gag. Immune exhaustion markers, phenotype of cytotoxic cells, and CD4 memory subpopulations were also determined. Direct cell cytotoxicity (DCC) was assessed by measuring caspase-3 levels in TZM-bl cells infected with HIV-1 after co-culturing with participants’ PBMCs (1:2).
Results
1) Most participants were male (83%, IQR 77-87). Median age was 30(IQR 24.5-35.5), 42.5(IQR 37.8-49.0), 49.5(IQR 45.8-54.3), and 56(IQR 54-60) years-old for <1y, 1-10y, 10-20y, and >20y cohorts, respectively. Time on ART was <1, 8(IQR 6-9), 15(IQR 13-19), and 28(IQR 25-31) years. Median nadir, CD4 and CD8 count were 219(IQR 153.8-379.8), 822(IQR 539-976), and 816(IQR 611-1227), respectively, for all cohorts. Median CD4/CD8 was 0.52(IQR 0.38-0.78), 0.76(IQR 0.53-1.20), 0.98(IQR 0.77-1.38), and 0.86(IQR 0.61-1.23), respectively. 2) CD4+ naive (TN) cells decreased with longer ART duration, while TCM and TEM increased. There were no differences in TEMRA between groups. 3) CD4 from <1y cohort showed significantly higher levels of LAG-3, PD1, and TIGIT than 10-20y and >20y cohorts, as well as CD57 and CD32, while KLRG1 was significantly higher in >20y. 4) HIV-1 reservoir was higher in <1y than cohorts with longer time on ART. 5) Proviral reactivation in CD4 (p24-gag+) was lower as time on ART progressed: 1.9-fold(p=0.0287) in 1-10y, 2.3-fold(p=0.0051), and 2.4-fold(p=0.0039), compared to <1y (Figure 1A). 6) Cytotoxic response against infected TZM cells was 2.4-fold (p=0.0417) and 2.4-fold (p=0.0396) higher in >20y compared to the <1y and 10-20y cohort (Figure 1B), which could be related to enhanced NKT subpopulations.
Conclusions
PWH on long-term ART showed reduced capacity for proviral reactivation and lower expression of exhaustion markers in CD4+ T cells, with improved cytotoxic response against HIV-1-infected cells. Time on ART should be considered for HIV cure interventions to achieve higher efficacy.
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