Dynamics of SIV-specific CXCR5+ CD8 T cells during chronic SIV infection

GH Mylvaganam, D Rios… - Proceedings of the …, 2017 - National Acad Sciences
GH Mylvaganam, D Rios, HM Abdelaal, S Iyer, G Tharp, M Mavigner, S Hicks, A Chahroudi
Proceedings of the National Academy of Sciences, 2017National Acad Sciences
A significant challenge to HIV eradication is the elimination of viral reservoirs in germinal
center (GC) T follicular helper (Tfh) cells. However, GCs are considered to be immune
privileged for antiviral CD8 T cells. Here, we show a population of simian immunodeficiency
virus (SIV)-specific CD8 T cells express CXCR5 (CXC chemokine receptor type 5, a
chemokine receptor required for homing to GCs) and expand in lymph nodes (LNs)
following pathogenic SIV infection in a cohort of vaccinated macaques. This expansion was …
A significant challenge to HIV eradication is the elimination of viral reservoirs in germinal center (GC) T follicular helper (Tfh) cells. However, GCs are considered to be immune privileged for antiviral CD8 T cells. Here, we show a population of simian immunodeficiency virus (SIV)-specific CD8 T cells express CXCR5 (C-X-C chemokine receptor type 5, a chemokine receptor required for homing to GCs) and expand in lymph nodes (LNs) following pathogenic SIV infection in a cohort of vaccinated macaques. This expansion was greater in animals that exhibited superior control of SIV. The CXCR5+ SIV-specific CD8 T cells demonstrated enhanced polyfunctionality, restricted expansion of antigen-pulsed Tfh cells in vitro, and possessed a unique gene expression pattern related to Tfh and Th2 cells. The increase in CXCR5+ CD8 T cells was associated with the presence of higher frequencies of SIV-specific CD8 T cells in the GC. Following TCR-driven stimulation in vitro, CXCR5+ but not CXCR5– CD8 T cells generated both CXCR5+ as well as CXCR5– cells. However, the addition of TGF-β to CXCR5– CD8 T cells induced a population of CXCR5+ CD8 T cells, suggesting that this cytokine may be important in modulating these CXCR5+ CD8 T cells in vivo. Thus, CXCR5+ CD8 T cells represent a unique subset of antiviral CD8 T cells that expand in LNs during chronic SIV infection and may play a significant role in the control of pathogenic SIV infection.
National Acad Sciences