Spi6 protects alloreactive CD4(+) but not CD8 (+) memory T cell from granzyme B attack by double-negative T regulatory cell

Am J Transplant. 2014 Mar;14(3):580-93. doi: 10.1111/ajt.12614.

Abstract

Memory T (Tm) cells pose a major barrier to long-term transplant survival. Whether regulatory T cells (Tregs)can control them remains poorly defined. Previously,we established that double-negative (DN) Tregs suppress effector T (Teff) cells. Here, we demonstrate that DNTregs effectively suppress CD4+/CD8+Teff and CD8+Tm but not CD4+Tm cells, whereas the suppression on CD8+Tm is abrogated by perforin (PFN) deficiency in DNTregs. Consistently, in a BALB/c to B6-Rag1-/-skin transplantation, transfer of DN Tregs suppressed the rejection mediated by CD4þ/CD8+Teff and CD8+Tmcells (76.0±4.9, 87.5±5.0 and 63.0±4.7 days, respectively)but not CD4þTmcells (25.3±1.4 days). Both CD8þ effector memory T and central memory T compartments significantly reduced after DN Treg transfer. CD4+Tm highly expresses granzyme B (GzmB) inhibitor serine protease inhibitor-6 (Spi6). Spi6 deficiency renders CD4þTm susceptible to DN Treg suppression. In addition,transfer of WT DN Tregs, but not PFN-/-DN Tregs,inhibited the skin allograft rejection mediated by Spi6-/-CD4þTm(75.5±7.9 days). In conclusion, CD4+ and CD8+Tm cells differentially respond toDNTregs’ suppression.The GzmB resistance conferred by Spi6 in CD4þTm cells might hint at the physiological significance of Tmpersistence

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • CD4-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / immunology*
  • Fas Ligand Protein / physiology
  • Flow Cytometry
  • Granzymes / physiology*
  • Immunologic Memory / immunology*
  • Membrane Proteins / physiology*
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Pore Forming Cytotoxic Proteins / physiology
  • RNA, Messenger / genetics
  • Real-Time Polymerase Chain Reaction
  • Reverse Transcriptase Polymerase Chain Reaction
  • Serpins / physiology*
  • Skin Transplantation*
  • T-Lymphocytes, Regulatory / immunology*

Substances

  • Fas Ligand Protein
  • Membrane Proteins
  • Pore Forming Cytotoxic Proteins
  • RNA, Messenger
  • Serpins
  • perforin, mouse
  • Granzymes
  • Serpinb9 protein, mouse