Abstract: TH-OR103
Advancing a Humanized Mouse Model to Study the Regulation of Germinal Center Response in Alloimmunity
Session Information
- Transplantation: Basic and Translational Advances
October 24, 2024 | Location: Room 25, Convention Center
Abstract Time: 05:00 PM - 05:10 PM
Category: Transplantation
- 2101 Transplantation: Basic
Authors
- Choi, John Yongjoon, Mass General Brigham Inc, Boston, Massachusetts, United States
- Yu, Samuel Mon-Wei, Icahn School of Medicine at Mount Sinai, New York, New York, United States
- Bonventre, Joseph V., Mass General Brigham Inc, Boston, Massachusetts, United States
- Brehm, Michael, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States
- Azzi, Jamil R., Mass General Brigham Inc, Boston, Massachusetts, United States
Background
In a fully mismatched mouse kidney transplant model, we showed that regulatory CD8 T cells (CD8 Tregs) are essential in controlling germinal center response, thus inhibiting antibody-mediated rejection. Thus far, humanized mice models have failed to develop mature immune subsets due to a lack of proper thymic education and human cytokines, significantly hindering the clinical translatability of our pre-clinical findings. To overcome such limits, we established a novel humanized model that allows us to study the mechanism of germinal center regulation.
Methods
NSG, NSG-hu-IL6, NSG-hu-IL15, and NSG-hu-IL6/IL15 mice that produce physiological levels of respective human cytokines were engrafted with fetal bone marrow, liver, and thymus tissue (BLT). Upon human immune cell engraftment, 8 to 10 3D-kidney organoids derived from H9 or BJFF embryonic stem cells were engrafted under the host kidney capsule. Mice were sacrificed on day 20 or 30 for the analysis. Spleens were harvested for immunophenotyping. T cells isolated from the spleen were co-cultured with 2D-kidney organoids to induce memory response. Serum was obtained to measure specific human cytokine levels and the development of alloantibodies. Kidney organoid allografts were harvested for light microscopy, immunofluorescence, and immunophenotyping of graft-infiltrating immune cells.
Results
NSG-BLT mice developed mature T cells that rejected kidney organoid allografts. T cells isolated from NSG-BLT demonstrated memory response, judged by cytokine excretion (TNFa, IFNg) and proliferation upon re-exposure to the alloantigens (2D-organoids). Ex vivo human IL15 salvaged NK and CD8 Treg functionality isolated from NSG-BLT, while NSG-hu-IL15-BLT hosts naturally developed mature NK and CD8 Tregs. While NSG-BLT shows limited B Cell frequency and maturation, NSG-hu-IL6-BLT showed significantly increased Tfh, class-switched B cells as we all as memory B cells, signifying the enhanced germinal center response. Finally, reduced germinal center response was observed in NSG-hu-IL6/IL15-BLT compared to NSG-hu-IL6-BLT hosts, suggesting the immunoregulatory role of CD8 Treg.
Conclusion
Exploiting our advanced humanized mice kidney organoid transplant model, we show that human CD8 Treg plays an essential role in germinal center response in alloimmunity.
Funding
- NIDDK Support