Background
The human gut has a high burden of HIV, but little is known about the phenotypes of HIV reservoir cells at this site or the influence of the local microenvironment. Here, we used standard and 40-parameter multiplexed ion beam imaging by time of flight (MIBI-TOF) microscopy to study the HIV reservoir and their associated environments from 5 different regions of the gut of ART-suppressed PWH (ART-PWH).
Methods
Fresh tissue specimens from duodenum (DDM), jejunum (JJM), ileum (ILM), colon (CLR) and rectum (RCT) were obtained through the Last Gift rapid autopsy program from n=6 ART-PWH and n=2 people without HIV (PWOH). Slices from FFPE tissues were prepared for multiplexed RNAscope (to detect HIV RNA) and confocal immunofluorescence imaging (to detect HIV p24). A subset of the samples was used for MIBI-TOF imaging.
Results
While on average 85% [range 74-100%] of the HIV RNA+CD4+ T cells in the DDM, CLR, and RCT expressed p24, only 45% [range 25-79%] in the JJM and ILM were p24+. To test the hypothesis that immune-mediated recognition and depletion of p24+CD4+ cells may be occurring in the JJM and ILM, we used MIBI-TOF to assess phenotypic features of the p24+CD4+ cells and their local environment in JJM of an ART-PWH. Relative to uninfected CD4+ T cells, p24+CD4+ T cells expressed higher levels of HIV coreceptor CCR5 (p=0.0056), checkpoint receptors (PDL1 (p<0.0001), TIGIT (p=0.0009)), Tfh marker CXCR5 (p=0.0018), inflammatory/cytolytic markers (Galectin-9 (p<0.0001), Granzyme B (p=0.0006)), proliferation marker Ki67 (p<0.0001), and differentiation marker AIOLOS (p<0.0001). These p24+ cells were in closer proximity to NK cells and dendritic cells (DCs) than to other subsets including B cells, CD8+ T cells, monocytes and macrophages (M0; p<0.0001). The overall numbers of macrophages were significantly decreased (p=0.0072) in the JJM of ART-PWH compared to the JJM of PWOH.
Conclusions
Our data suggest that p24+CD4+ T cells are distributed throughout the entire gut of ART-PWH, but that JJM and ILM may possess distinct mechanisms that preferentially eliminate these cells. p24+CD4+ cells in JJM of ART-PWH exhibit distinct phenotypic features including evidence of recent proliferation (Ki67). Their spatial localization suggests they may be recruiting subsets of innate cells (NK cells and DCs), which can help eliminate infected cells, while M0 may be depleted. Overall, our results point to active crosstalk between HIV-infected cells and innate immune effector cells in the gut of ART-PWH.