HIV persists in CCR6+CD4+ T cells from colon and blood during antiretroviral therapy

Abstract

Objectives To investigate the contribution of colon and blood CD4+ T-cell subsets expressing the chemokine receptor CCR6 to HIV persistence during ART. Design Matched sigmoid biopsies and blood samples (n=13) as well as leukapheresis (n=20) were collected from chronically HIV-infected individuals receiving ART. Subsets of CD4+ T-cells with distinct differentiation/polarization profiles were identified using surface markers as follows: memory (TM, CD45RA-), central memory (TCM; CD45RA−CCR7+), effector (TEM/TM; CD45RA−CCR7−), Th17 (CCR6+CCR4+), Th1Th17 (CCR6+CXCR3+), Th1 (CCR6−CXCR3+), and Th2 (CCR6−CCR4+). Methods We used polychromatic flow cytometry for cell sorting, nested real-time PCR for HIV-DNA quantification, ELISA and flow cytometry for HIV-p24 quantification. HIV reactivation was induced by TCR-triggering in the presence/absence of all-trans retinoic acid. Results Compared to blood, the frequency of CCR6+ TM was higher in the colon. In both colon and blood compartments, CCR6+ TM were significantly enriched in HIV-DNA when compared to their CCR6− counterparts (n=13). In blood, integrated HIV-DNA levels were significantly enriched in CCR6+ versus CCR6− TCM of 4/5 individuals and CCR6+ versus CCR6− TEM of 3/5 individuals. Among blood TCM, Th17 and Th1Th17 contributed the most to the pool of cells harboring integrated HIV-DNA despite their reduced frequency compared to Th2 which were infected the least. HIV reactivation was induced by TCR triggering and/or retinoic acid exposure at higher levels in CCR6+ versus CCR6− TM, TCM, and TEM. Conclusions CCR6 is a marker for colon and blood CD4+ T-cells enriched for replication-competent HIV-DNA. Novel eradication strategies should target HIV persistence in CCR6+CD4+ T-cells from various anatomic sites.

HIV-1 selectively targets gut-homing CCR6+CD4+ T cells via mTOR-dependent mechanisms

“…Of particular importance, Li et al recently demonstrated that acitretin, a RA derivative, increases HIV transcription in CD4 + T cells from ART-treated HIV-infected individuals and enhances RIG-I signaling, thus leading to an antiviral response and the apoptosis of infected cells (68). Similarly, in a previous report (37) and in this manuscript, we demonstrated that ATRA significantly increases HIV reactivation in a VOA without significant changes observed in T cell survival/proliferation. Differences between our results and those published by Li et al (68) may be explained by differences in the experimental design.…”

“…Of particular importance, we found that CCR6 + cells but not CCR6 -T cells infiltrating the colons of HIV-infected individuals receiving ART express a unique molecular signature, including superior levels of CCR5, integrin β7, and phosphorylated mTOR expression, likely as a consequence of ATRA exposure in the intestinal environment (12,41). In line with our recent report that HIV DNA persists in colon-infiltrating CCR6 + T cells during ART (37), it remains to be determined whether mTOR expression identifies a fraction of CCR6 + T cells enriched in HIV DNA and whether mTOR activation contributes to residual HIV replication in colon-infiltrating CCR6 + T cells during ART. While this manuscript was in preparation for submission, Besnard et al reported the results of a shR-NA screen that revealed mTOR as a regulator of HIV latency (86) via mechanisms involving CDK9 and NF-κB activation that controls Tat-dependent HIV transcription (86).…”

“…These two reports (86,87) further support the conclusions of our current study, which reveals the key role played by mTOR in regulating multiple postentry and postintegration HIV replication steps in gut-homing Th17-polarized CCR6 + T cells. In conclusion, our findings point to CCR6 as a "zip code" molecule expressed on the surface of CD4 + T cells transcriptionally programmed to become HIV targets upon recruitment into the intestine and provide a detailed molecular explanation for preferential HIV/SIV replication and persistence in gut-homing CCR6 + CD4 + T cells (24,25,37,42). Most significantly, we reveal the role of the mTOR pathway in regulating effector functions as well as HIV permissiveness in gut-homing CCR6 + Th17 cells at multiple postentry levels.…”

“…+ T cells during ART (37). These advances orient our search for immunotherapeutic strategies to limit HIV infection/persistence in mucosal Th17 cells in the ART era.…”

“…In a very recent study, we demonstrated that ATRA facilitates HIV reactivation from latency in CCR6 + CD4 + T cells from ART-treated individuals (37). To determine whether HIV reservoir reactivation was dependent on mTOR activity, an optimized viral outgrowth assay (VOA) was performed in the presence/absence of ATRA and mTORC1/2 inhibitor INK128 ( Figure 9A).…”