Persistent Microbial Translocation and Immune Activation in HIV-1-Infected South Africans Receiving Combination Antiretroviral Therapy

Background. Microbial translocation contributes to immune activation and disease progression during chronic human immunodeficiency virus type 1 (HIV-1) infection. However, its role in the African AIDS epidemic remains controversial. Here, we investigated the relationship between markers of monocyte activation, plasma lipopolysaccharide (LPS), and HIV-1 RNA in South Africans prioritized to receive combination antiretroviral therapy (cART). Methods. Ten HIV-1-negative African controls and 80 HIV-1-infected patients with CD4 T cell counts <200 cells/mu L were sampled prior to (n = 60) or during (n = 20) receipt of effective cART. Viral load was measured by Nuclisens; LPS by the Limulus amoebocyte lysate assay; monocyte and T cell subsets by flow cytometry; and soluble CD14, cytokines, and chemokines by enzyme-linked immunosorbent assay and customized Bio-Plex plates. Results. Three distinct sets of markers were identified. CCL2, CXCL10, and CD14(+)CD16(+) monocyte levels were positively correlated with HIV-1 viremia. This finding, together with cART-induced normalization of these markers, suggests that their upregulation was driven by HIV-1. Plasma interleukin-6 was associated with the presence of opportunistic coinfections. Soluble CD14 and tumor necrosis factor were linked to plasma LPS levels and, as observed for LPS, remained elevated in patients receiving effective cART. Conclusions. Microbial translocation is a major force driving chronic inflammation in HIV-infected Africans receiving cART. Prevention of monocyte activation may be especially effective at enhancing therapeutic outcomes.