Early antiretroviral therapy and its impact on natural killer cell dynamics in HIV-1 infected men who have sex with men: a cross-sectional pilot study evaluating the impact of early ART initiation on NK cell perturbation in HIV infection

Phenotypic changes and functional impairment of natural killer (NK) cells occur early in HIV-1 infection. Antiretroviral therapy (ART) effectively restores CD4+ T cell counts and suppresses HIV-1 to undetectable levels. The role and efficacy of immediate ART initiation in mitigating NK cell aberrations remain to be elucidated comprehensively. This study hypothesized that HIV-1 infection negatively influences NK cell evolution and that early ART initiation restores these perturbations. Blood samples were collected longitudinally from five acutely HIV-1 infected men who have sex with men in Nairobi, Kenya. Participants were immediately initiated on ART after HIV-1 diagnosis. Blood samples were drawn pre-infection and at sequential bi-weekly post-infection time points. Peripheral blood mononuclear cells were stained with panel NK cells surface markers to assess HIV-induced phenotypic changes by flow cytometry. Some cells were also stimulated overnight with K562 cell line, IL-2, and IL-15 and stained for flow cytometry functionality. HIV-1 infection was associated with significant reductions in the production of IFN-γ (P = 0.0264), expression of CD69 (P = 0.0110), and expression of NK cell inhibitory receptor Siglec7 (P = 0.0418). We observed an increased NK cell degranulation (P = 0.0100) and an upregulated expression of cell exhaustion marker PD-1 (P = 0.0513) at post-infection time points. These changes mainly were restored upon immediate initiation of ART, except for Siglec7 expression, whose reduced expression persisted despite ART. Some HIV-associated changes in NK cells may persist despite the immediate initiation of ART in acute HIV-1 infections. Our findings suggest that understanding NK cell dynamics and their restoration after ART can offer insights into optimizing HIV-1 treatment and potentially slowing disease progression.IMPORTANCENatural killer (NK) cells play a crucial role in controlling of HIV-1 replication and progression to disease. Perturbations of their functionality may therefore result in deleterious disease outcomes. Previous studies have demonstrated reduced NK cell functionality in chronic HIV-1 infection that positively correlated to HIV-1 viral load. This may suggest that control of HIV-1 viremia in acute HIV-1 infection may aid in enhancing NK cell response boosting the inate immunity hence effective control of viral spread and establishment of viral reservoir. Antiretroviral therapy (ART) effectively supresses HIV-1 viremia to undectable levels and restores CD4+ T cell counts. Our study highlights the significant role of early ART initiation in mitigating NK cell disruptions caused by acute HIV-1 infection. Our results suggest that early initiation of ART could have benefits beyond suppressing viral load and restoring CD4+ T cell counts. In addition, it could boost the innate immunity necessary to control disease progression.