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2023 CD47 Upregulation Inhibits Phagocytic Clearance of Alloreactive Donor T Cells after Allo-HCT

Program: Oral and Poster Abstracts
Session: 701. Experimental Transplantation: Basic and Translational: Poster I
Hematology Disease Topics & Pathways:
Research, Translational Research
Saturday, December 7, 2024, 5:30 PM-7:30 PM

Haroon Shaikh, PhD1*, Cindy Flamann, PhD2,3*, Carina Matos, PhD4*, Hla Ali, MSc5*, Michael AG Kern1*, Marina Kreutz, PhD4*, Maike Buettner-Herold6*, Christopher Lischer, MSc2*, Simon Voelkl, PhD7,8,9,10*, Christian Kellner, PhD11*, Katrin Bitterer, MTA2*, Domenica Saul, MTA2*, Ernst Holler, MD, PhD12*, Alma Zernecke, MD5*, Dimitrios Mougiakakos, MD13, Andreas Beilhack14* and Heiko Bruns, PhD8,9,15*

1Department of Medicine II, University Hospital Würzburg, Würzburg, Germany
2Department of Internal Medicine 5 – Hematology/Oncology, University Hospital Erlangen, Erlangen, Germany
3University Hospital Erlangen, Erlangen, DEU
4Department of Internal Medicine III, University Hospital Regensburg, Regensburg, Germany
5Institute of Experimental Biomedicine, University Hospital Würzburg, Würzburg, Germany
6Department of Nephropathology, University Hospital Erlangen, Erlangen, Germany
7Department of Internal Medicine 5 - Hematology and Oncology, University Hospital of Erlangen, Erlangen, Germany
8Bavarian Cancer Research Center (BZKF), Erlangen, Germany
9Deutsches Zentrum Immuntherapie (DZI), Friedrich-Alexander-Universität Erlangen-Nürnberg and University Hospital Erlangen, Erlangen, Germany
10Department of Internal Medicine 5, Hematology and Oncology, University Hospital Erlangen, Erlangen, Germany
11Division of Transfusion Medicine, Cell Therapeutics and Haemostaseology, LMU University Hospital, LMU Munich, Munich, Germany
12Internal Medicine III - Hematology and Oncology, University Hospital Regensburg, Regensburg, Germany
13Department of Hematology, Oncology and Cell Therapy, Medical Faculty, Otto-von-Guericke University, Magdeburg, Germany
14Department of Internal Medicine II, University Hospital Würzburg, Würzburg, Germany
15Department of Internal Medicine 5, Hematology and Oncology, University of Erlangen, Erlangen, Bavaria, Germany

Acute graft-versus-Host disease (aGvHD) is a life-threatening complication that frequently occurs after allogeneic hematopoietic cell transplantation (allo-HCT). Resolving inflammation is a key therapeutic goal in aGvHD. Macrophage-mediated phagocytosis contributes substantially to resolve inflammatory processes. However, the role of phagocytosis after allo-HCT still remains unexplored.

Therefore, we analyzed the expression of the “don´t eat me” signal CD47 on allogeneic T cells from aGvHD patients and in two MHC major mismatch aGvHD mouse models (FVB à C57BL/6, 9 Gy TBI and C57BL/6 à Balb/C, 8 Gy TBI). We evaluated the effect of in vitro and in vivo administration of an anti-CD47 antibody on antibody-dependent cellular phagocytosis (ADCP) of alloreactive T cells using flow cytometry and confocal microscopy, bioluminescence imaging, cytokine measurements and histopathology.

Initial analysis of a global dataset revealed increased CD47 expression on intestinal T cells in patients with chronic gastrointestinal inflammation. Subsequently, we examined CD47 levels on T cells in the allo-HCT setting. Notably, intestinal T cells in patients with severe GvHD (Lerner grade III) significantly upregulated CD47 (p = 0.0079). There were no significant changes in CD24 (another “don´t eat-me”-signal) or in the “eat-me”-signals calreticulin and ATP10A. This upregulation of CD47 correlated with reduced macrophage-mediated phagocytosis. Similarly, intestinal alloreactive donor T cells highly upregulated CD47 in mice developing aGvHD after allo-HCT (p = 0.0317). In vitro studies revealed that CD47 expression is regulated by NF- kB in T cells after TCR activation and primed T cells inhibit ADCP in a CD47-dependent fashion. Transfer of CD47 knock-out T cells and bone marrow resulted in swift clearance of donor T cells after allo-HCT resulting in significantly improved clinical scores and survival compared to controls (p = <0.0001). Crucially, application of an anti-CD47 antibody significantly antagonized the impaired ADCP of alloreactive T cells. In anti-CD47 treated mice, we observed increased phagocytosis of T cells in the gastrointestinal tract (GIT) and induction of immunosuppressive responses in vivo. Besides an increase of the myeloid-derived suppressor cell population, systemic pro-inflammatory cytokine levels such as TNF, IL-1β and IFN-β decreased in the serum.

In conclusion, our data suggest that high CD47 expression impairs phagocytic clearance of alloreactive T cells after allo-HCT, potentially contributing to exaggerated inflammatory responses in the GIT of GvHD patients. Thus, CD47 emerges as potential therapeutic target to eliminate alloreactive T cells, with anti-CD47 treatment aiding the resolution of inflammation in GvHD.

Disclosures: Mougiakakos: Galapagos: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Beigene: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Miltenyi: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Beilhack: The University of Würzburg: Patents & Royalties: patent application filed for “Novel TNFR2 binding molecules.

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