Perturbed CD8+ T cell TIGIT/CD226/PVR axis despite early initiation of antiretroviral treatment in HIV infected individuals

Sci Rep. 2017 Jan 13:7:40354. doi: 10.1038/srep40354.

Abstract

HIV-specific CD8+ T cells demonstrate an exhausted phenotype associated with increased expression of inhibitory receptors, decreased functional capacity, and a skewed transcriptional profile, which are only partially restored by antiretroviral treatment (ART). Expression levels of the inhibitory receptor, T cell immunoglobulin and ITIM domain (TIGIT), the co-stimulatory receptor CD226 and their ligand PVR are altered in viral infections and cancer. However, the extent to which the TIGIT/CD226/PVR-axis is affected by HIV-infection has not been characterized. Here, we report that TIGIT expression increased over time despite early initiation of ART. HIV-specific CD8+ T cells were almost exclusively TIGIT+, had an inverse expression of the transcription factors T-bet and Eomes and co-expressed PD-1, CD160 and 2B4. HIV-specific TIGIThi cells were negatively correlated with polyfunctionality and displayed a diminished expression of CD226. Furthermore, expression of PVR was increased on CD4+ T cells, especially T follicular helper (Tfh) cells, in HIV-infected lymph nodes. These results depict a skewing of the TIGIT/CD226 axis from CD226 co-stimulation towards TIGIT-mediated inhibition of CD8+ T cells, despite early ART. These findings highlight the importance of the TIGIT/CD226/PVR axis as an immune checkpoint barrier that could hinder future "cure" strategies requiring potent HIV-specific CD8+ T cells.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antigens, Differentiation, T-Lymphocyte / genetics*
  • Antiretroviral Therapy, Highly Active
  • CD8-Positive T-Lymphocytes / metabolism
  • CD8-Positive T-Lymphocytes / virology
  • Female
  • Gene Expression Regulation / drug effects
  • HIV / pathogenicity
  • HIV Infections / drug therapy*
  • HIV Infections / genetics
  • HIV Infections / virology
  • Humans
  • Male
  • Middle Aged
  • Receptors, Immunologic / genetics*
  • Receptors, Virus / genetics*
  • Signal Transduction

Substances

  • Antigens, Differentiation, T-Lymphocyte
  • CD226 antigen
  • Receptors, Immunologic
  • Receptors, Virus
  • TIGIT protein, human
  • poliovirus receptor