Background:  Studies of ART intensification in suppressed patients fail to show consistent reductions in plasma HIV RNA. We hypothesized that in patients receiving intensification, reductions in HIV RNA and in immune activation may be seen in the gut.

Methods:  In 7 HIV⁺ men with viral load <40 copies/mL for 3 to 12 yrs and a CD4 count >200, we performed a pilot study of 12 week intensification with raltegravir (RLG) alone (n = 4), RLG + EFV (n = 2), or RLG + DRV/RTV (n = 1). Gut cells were obtained by upper and lower endoscopy with biopsies from 4 gut sites (duodenum, ileum, colon, and rectum) at time 0 and 12 wks. Study outcomes included plasma HIV RNA (modified Abbott assay), HIV DNA from peripheral blood mononuclear cells and 4 gut sites (real time PCR), HIV RNA from peripheral blood mononuclear cells and 4 gut sites (real time RT PCR), T cell subsets, and activation markers (flow cytometry). Pre- and post-intensification values were compared using the paired Wilcoxon signed rank test.

Results:  HIV was detectable in plasma (RNA) and in peripheral blood mononuclear cells (DNA and unspliced RNA) in all patients at baseline (medians: 2.3 copies/mL, 591 copies/10⁶ cells, 44.4 copies/10⁶ cells). HIV DNA was detectable in the duodenum in 63% of patients (median 61 copies/10⁶ cells) and in the ileum, colon, and rectum in 100% of patients at baseline (medians: 370, 473, and 545 copies/10⁶ cells). Unspliced HIV RNA was detectable in each gut site in the majority (63 to 88%) of patients at baseline (median: 8, 24, 7, and 10 copies/10⁶ cells in duodenum, ileum, colon, and rectum). Intensification resulted in no consistent change in HIV RNA in the plasma, peripheral blood mononuclear cells, or gut, though there was a trend (5 of 7) towards decreased unspliced HIV RNA per 10⁶ CD4⁺ T cells in the ileum (from mean of 3438 to 682). There was a trend towards decreased activation (CD38⁺, HLA-DR⁺, and dual+) of CD4⁺ and CD8⁺ T cells in all sites, which was greatest for CD8⁺ T cells in the ileum (mean of 25.6 to 20.2% CD38⁺HLA^-DR⁺) and in peripheral blood mononuclear cells. There was also a trend towards increased CD4 as % of all cells (6 of 7; from a mean of 1.9 to 2.9%) and as % of T cells (5 of 7; from 27.5 to 33.5%) in the ileum.

Conclusions:  In suppressed patients, most HIV RNA in the plasma, peripheral blood mononuclear cells, and gut is not the result of ongoing replication that can be reduced by short-term intensification with raltegravir. However, intensification reduced HIV RNA, reduced immune activation, and increased CD4⁺ T cells in the ileum, suggesting that the ileum may support ongoing productive infection in some patients on ART, even if the contribution to plasma RNA is not discernible.