Correlation between different methods to measure microbial translocation and its association with immune activation in long-term suppressed HIV-1-infected individuals.

Introduction: Microbial translocation (MT) has been proposed as one of the triggering mechanisms of persistent immune activation associated to HIV-1 infection. Our objectives were to determine the correlation between different measurements of MT in suppressed HIV-1-infected individuals and to evaluate its correlation with immune activation.

Methods: Eighteen suppressed HIV-1-infected patients with CD4+ T-cell count above 350 cells per cubic millimeter and undetectable plasma viral load, included in antiretroviral treatment intensification clinical trials, were evaluated. Samples obtained at baseline and at established time points during the trials were analyzed. Lipopolysaccharide (LPS), lipopolysaccharide binding protein (LBP), soluble CD14 (sCD14), and bacterial 16S ribosomal DNA (16S rDNA), and markers of immune activation were determined.

Results: We analyzed 126 plasma samples from the 18 patients. LPS significantly correlated with sCD14 (P < 0.001, r = 0.407) and LBP (P = 0.042, r = 0.260). Also, a significant correlation was found between sCD14 and LBP (P = 0.009, r = 0.325) but not between bacterial 16S rDNA and LPS, sCD14, or LBP (P = 0.346, P = 0.405, and P = 0.644). On the other hand, no significant correlation was found between LPS, sCD14, or LBP and CD4 (P = 0.418, P = 0.619, and P = 0.728) or CD8 T-cell activation (P = 0.352, P = 0.275, and P = 0.124). Bacterial 16S rDNA correlated with activated CD4 T cells (P = 0.005, r = 0.104) but not with activated CD8 T cells (P = 0.171).

Conclusions: There is a good correlation in the quantification of LPS, sCD14, and LBP levels, but not with bacterial 16S rDNA, as measurements of MT. We are unable to ensure that MT directly triggers T-cell immune activation at least among these patients with relatively good immune recovery and under treatment intensification.