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Abstract: SA-PO598

Double-Negative T-Cells That Express PD-1 Are Early Responders During Ischemic AKI

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

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

Unconventional T cells (e.g. Tregs and γδT cells) are increasingly recognized for their roles in maintaining homeostasis and protecting non-lymphoid tissues against injury/stress. CD4-CD8- double negative (DN) αβT cells are abundant in mouse and human kidneys, actively dividing in steady state and involved in protecting against ischemic AKI. However, there is less knowledge about DN T cells residing in kidney are known.

Methods

C57BL/6J (WT), B6.129P2-B2mtm1Unc/J (β2m KO), B6.129S2-H2dlAb1-Ea/J (MHC II KO), B6.129P2-H2-K1tm1Bpe H2-D1tm1Bpe/DcrJ (KD KO) and Nu/J mice were used for this study, n=3-7/group. Human kidney samples were from nephrectomies for renal cancers. Kidney lymphocytes were isolated and analyzed by flow cytometry.

Results

Our data demonstrates that kidney DN T cells are thymus-derived as lack of thymus significantly reduced the absolute count of DN T cells in kidney (WT, 2.2x104 vs. Nu/J, 0.24x104, P<0.05) and also comprised of two (PD-1+ and NK1.1+) subsets whose development and homeostasis are dependent on non-classical MHC class I molecules. Development of the NK1.1+ subset is restricted by β2m-dependent non-classical MHC molecules as the frequency of NK1.1+ DN T cells was significantly reduced in β2m KO (10.3±2) but not in KD-deficient mice (21.5±2) then WT mice (23.1±3, P<0.001). In contrast, homeostasis but not development of the PD-1 subset is regulated by β2m-dependent non-classical MHC molecules as the frequency of PD-1+ DN T cells was significantly higher in β2m KO (70.2±5) then WT mice (44.2±3 P<0.001). DN T-cells are present in kidney of β2m KO mice, but lose their phenotypic activation (>60%, P<0.001), spontaneous steady proliferation (>40%, P<0.05) and undergo apoptosis. DN T cells retained in kidneys of β2m KO mice are mostly PD-1+ and remain functionally responsive to external stimuli as indicated by their rapid activation and expansion in response to ischemic AKI. Both normal human kidney and cancer samples express the PD-1+ (% normal, 39.5±8 vs. tumor, 47.9±7.8) and NK1.1+ subsets (% normal, 26.2±8.4 vs. tumor, 23.0±8.3).

Conclusion

These findings demonstrate that kidney DN T cells, particularly PD-1+ DN T cells, are early responders of the renal immune surveillance system utilizing recognition/activation/regulation mechanisms that differ from conventional T cells.

Funding

  • NIDDK Support