Pre-Human Immunodeficiency Virus (HIV) infection Th17 CD4+ T cells as predictors of early HIV disease progression
Interleukin-17-producing T helper (Th17) CD4+ T cells are highly susceptible to HIV infection and are depleted early in people living with HIV. Here, we investigated whether systemic Th17 cell levels prior to HIV infection are associated with subsequent HIV disease progression. We analyzed archived cryopreserved peripheral blood mononuclear cells (PBMCs) collected within one year prior to HIV acquisition from participants enrolled in a South African cohort (HIV Vaccine Trials Network [HVTN] 503; n = 35) and an East African cohort (Partners Pre-exposure Prophylaxis/Couples Observational Study [PP/COS]; n = 32). Th17 cell frequencies were quantified by flow cytometry. In HVTN 503, higher pre-HIV IL-17+ CD4+ T cell frequencies were inversely correlated with CD4/CD8 ratio measured both within 180 days (Spearman rank R = -0.42, p = 0.012) and beyond 180 days (R = -0.55, p = 0.001) after HIV infection, and were associated with faster CD4+ T cells decline (adjusted hazard ratio [aHR] = 3.5, 95% CI: 1.2-9.9, p = 0.020). In contrast, no significant association with CD4 decline was observed in the PP/COS cohort (HR = 1.2, 95% CI: 0.4-3.4, p = 0.795). Sex-stratified analyses in HVTN 503 indicated a more pronounced association between pre-HIV IL-17+ CD4+ T cells and faster CD4 decline in males than females. In analyses combining all cohorts, higher pre-HIV IL-17+ CD4+ T cell frequencies remained associated with faster CD4 decline, particularly among younger participants (HR = 3.5; 95% CI: 1.35-9.22, p = 0.010). Pre-HIV IL-17+ CD4+ T cell frequencies were not associated with peak or set-point viral load in either cohort. Together, these findings suggest that pre-HIV Th17 cells abundance may influence subsequent HIV disease progression independently of early viral replication. Author SummaryHIV infection leads to progressive damage of the immune system, but the rate at which this damage occurs varies widely between individuals. Understanding the factors that influence HIV disease progression is essential for improving prevention and treatment strategies. Previous studies have suggested that immune characteristics present before infection may shape disease outcomes after HIV acquisition. In this study, we examined whether the abundance of IL-17-producing CD4+ T cells, known as Th17 cells, measured prior to HIV acquisition, were associated with markers of disease progression after infection. We analyzed blood samples from individuals who were HIV-negative at the time of sampling and later acquired HIV during follow-up. We found that individuals with higher pre-infection levels of Th17 cells experienced faster immune decline after HIV infection, including more rapid loss of CD4+ T cells and lower CD4/CD8 ratios. These associations were observed independently of viral load and varied by cohort, age and sex. Our findings indicate that immune conditions present before HIV infection can influence subsequent disease progression and suggest that Th17 cells may serve as biomarkers to identify individuals at higher risk of rapid HIV-related immune damage.