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Understanding the dynamics of the immune system to cure graft-versus-host disease (GvHD).

Periodic Reporting for period 4 - GvHDCure (Understanding the dynamics of the immune system to cure graft-versus-host disease (GvHD).)

Reporting period: 2020-09-01 to 2021-05-31

What is the problem/issue being addressed?
The major problem, that is addressed in this project, is that patients with leukemia that are treated with an allogeneic hematopoietic stem cell transplantation mainly die because of a complication called graft-versus-host disease and the recurrence of the leukemia. By using mouse models and human tissue samples we developed novel therapy strategies to improve the treatment of the complication called graft-versus-host disease and the recurrence of the leukemia.
Why is it important for society?
It is important for society to find better treatment for leukemia in order to have a healthier society and to keep more young people alive that contribute with their workforce to the wealth of the society. By distributing our results in scientific journals, by reporting them in workshops, by presenting them at scientific conferences and by publishing press releases we have informed the scientific community and the public community about our results.
What are the overall objectives?
One overall objective was to understand the role of a cell population called "neutrophil granulocytes" in the development of graft-versus-host disease. We were able to show that this cell type contributes to graft-versus-host disease and we found a novel pharmacological approach to target this cell type with a drug called JAK1/2 inhibitor. This objective was important because it allowed us to extend the classical type of immunosuppressive medication given to patients with graft-versus-host disease.
Another overall objective was to characterize the role of micro RNAs in the development of graft-versus-host disease. Micro RNAs are short non-coding RNAs that interfere with gene expression at the posttranscriptional level and thereby regulate multiple pathways in different diseases. We were able to show that the micro RNA miR-146a reduces the disease called graft-versus-host disease A third overall objective was to identify new therapies for leukemia relapse. We found that inhibition of Fms-related tyrosine kinase 3 (FLT3) with sorafenib in combination with donor T cell infusions caused complete elimination of the leukemia cells in leukemia bearing mice and in patients. This observation was made in a large cohort of over 400 patients and will be an important information for physicians who treat their leukemia patients that have a FLT3-ITD mutation. This new information was also included in the guidelines for leukemia relapse treatment by the DGHO (German Society for Hematology and Oncology) which can be found at www.onkopedia.de. We found that T cells of patients relapsing with AML after allo-HCT exhibited reduced glycolysis and interferon-γ production. Functional studies in multiple mouse models of leukemia showed that leukemia-derived lactic acid (LA) interfered with T cell glycolysis and proliferation.
My research group, which is supported by the ERC grant, worked on the role of neutrophils in a disease called graft-versus-host disease (GVHD). The background of this project is that therapeutic interference with the early events of GVHD is difficult, and currently used immunosuppressive drugs mainly target donor T cells. A detailed analysis of neutrophil fate during acute GVHD and the effect on T cells is difficult because of the short lifespan of this cell type. We could show in this reporting period that neutrophils that had been photoconverted in the a section of the intestinal tract called ileum later migrated to lymph nodes located in close proximity to the intestines. We also observed that the neutrophils colocalized with T cells and presented antigen on major histocompatibility complex (MHC)-II, thereby affecting T cell expansion. We found that JAK1/JAK2 inhibition with a drug called ruxolitinib reduced neutrophil influx into the lymph nodes and acute GVHD pathogenesis.
Pathogenic kinase sinaling is not only found in immune cells that cause GVHD but also in leukemia cells that cause relapse after allo-HCT. We observed that sorafenib, a multitargeted tyrosine kinase inhibitor, increased IL-15 production by FLT3-ITD+ leukemia cells. This synergized with the allogeneic CD8+ T cell response, leading to long-term survival in six mouse models of FLT3-ITD+ AML. Sorafenib-related IL-15 production caused an increase in CD8+CD107a+IFN-γ+ T cells which eradicated leukemia in secondary recipients. Mechanistically, sorafenib reduced expression of the transcription factor ATF4, thereby blocking negative regulation of interferon regulatory factor 7 (IRF7) activation, which enhanced IL-15 transcription. Human FLT3-ITD+ AML cells obtained from sorafenib responders following sorafenib therapy showed increased levels of IL-15, phosphorylated IRF7, and a transcriptionally active IRF7 chromatin state. The mitochondrial spare respiratory capacity and glycolytic capacity of CD8+ T cells increased upon sorafenib treatment in sorafenib responders but not in nonresponders. Our findings indicate that the synergism of T cells and sorafenib is mediated via reduced ATF4 expression, causing activation of the IRF7-IL-15 axis in leukemia cells and thereby leading to metabolic reprogramming of leukemia-reactive T cells in humans.
A major progress beyond the state of the art was that we could show a novel role for neutrophil granulocytes in antigen presentation in acute GVHD. We will build on this finding and characterize more pro- and anti-inflammatory events that influence neutrophil migration and function during GVHD. We expect that we can characterize different subtypes of neutrophils that are involved in the early versus late phase of GVHD. We were able to generate preliminary by single cell sorting and RNA sequencing of neutrophils from the intestinal tract of mice developing GVHD. Our findings go beyond the state of the art as there is currently no information which neutrophil subtypes reside in the intestinal tract at different time points after transplantation. Another major discovery was that neutrophils mediate cellular communication between the inflamed tissue and the secondary lymphoid organs during GVHD development.
Our ERC work has revolutionized our understanding of the immune responses evolving after allogeneic hematopoietic stem cell transplantation for leukemia treatment. We were the first to describe the role of Damage associated molecular patterns and different myeloid cell types in the intestinal wall after allogeneic bone marrow transplantation. Our work on the function and signaling activity of these immune cells has opened a new research field, which has fundamental implications for the understanding of immune reactions in the human body after allogeneic hematopoietic stem cell transplantation, which is highly recognized at the international level.
Besides a better understanding of the disease GVHD in preclinical models, but our work also translated into two multinational, multicenter randomized phase III trials, which both met their primary endpoint of improved response compared to the control group and both were published in the New England Journal of Medicine. Zeiser R, et al. Ruxolitinib for Glucocorticoid-Refractory Acute Graft-versus-Host Disease. The New England Journal of Medicine 382: 1800-1810, 2020, Zeiser R, et al. Ruxolitinib for Glucocorticoid-Refractory Chronic Graft-versus-Host Disease. The New England Journal of Medicine 385: 228-238, 2021
GLP2 protects intestinal cells from GVHD
Lactic acid derived from leukemia
Microglia are activated by GVHD