Abstract: TH-PO257

Non-Classical MHC Class I Molecules Regulate Development and Maintenance of Kidney Double Negative αβ T Cells

Session Information

Category: Acute Kidney Injury

  • 001 AKI: Basic

Authors

  • Sadasivam, Mohanraj, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
  • Noel, Sanjeev, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
  • Lee, Sul A, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
  • Hamad, Abdel, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
  • Rabb, Hamid, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
Background

Despite strong evidence that immune cells mediate early injury and repair from ischemic acute kidney injury (AKI), the underlying mechanisms are poorly understood. A recently characterized subset of αβ T cells that is double negative (DN) for both CD4 and CD8 coreceptors is present in significant numbers in normal mouse and human kidney. Unlike CD4+ and CD8+ T cells, DN T cells divide actively in the steady state and rapidly increase in response to AKI. In addition, kidney DN T cells secrete anti-inflammatory cytokines IL-10 and IL-27, possess an in vitro and in vivo regulatory function and ameliorate AKI in mice. However, the exact MHC restriction element(s) required for homeostatic DN T cells development and maintenance is not known.

Methods

C57BL/6J (WT), B6.129P2-B2mtm1Unc/J (β2m KO), B6.129S2-H2dlAb1-Ea/J (MHC II KO) and B6.129P2-H2-K1tm1Bpe H2-D1tm1Bpe/DcrJ (KD KO) mice were used for analyses. The lymphocytes from the kidney, lymph node and thymus were isolated and analyzed for activation (CD69, CD44, CD62L & CD28), proliferation (Ki67) and apoptosis (annexin V). In vitro functional analysis of cytokines were performed by flow cytometry. Adoptive transfer of T and B cells were performed to assess the regulation of kidney DN T cells.

Results

Our data demonstrate that lack of β2m, but not classical MHC class Ia or class II molecule significantly reduces the frequency (WT, 28.8±3 vs. β2m KO, 9.5±2 vs. MHC II KO, 32.3±2; P<0.05) and the absolute number (WT, 3,355±1,077 vs. β2m KO, 1,016±471 vs. MHC II KO, 1,538±639; P<0.05) of kidney DN T cells. Subsequent studies show the reduction is due to impaired activation (P<0.001) and proliferation (P<0.05), and increased apoptosis (P<0.05) by kidney DN T cell. Further, most of the defects were restored by adoptive transfer of CD8 T cell from wild type mice, leading to activation and expansion (P<0.001) of endogenous DN T cells in β2m KO mice.

Conclusion

Our data indicate a critical role of β2m dependent MHC class Ib molecules in regulating homeostasis and activation of kidney DN T cells. Furthermore, CD8 T cells are appearing to be a source of MHC class Ib molecules and one strong candidate (Qa2) is being investigated using knockout mice, bone marrow chimera and adoptive transfer in the steady state and ischemic AKI.

Funding

  • NIDDK Support