BMT-CT Division Researcher Craig Byersdorfer Awarded New NIH R01 Grant

Craig A. Byersdorfer, MD, PhD, assistant professor of medicine in the Division of Blood and Marrow Transplantation and Cellular Therapies at UPMC Children’s was awarded a National Institutes of Health (NIH) R01 grant to continue his studies on T cell-mediated graft-versus-host disease in allogeneic hematopoietic stem cell transplantation (alloHSCT). Dr. Byersdorfer’s new grant (1R01HL14556-01) will investigate the role of the AMP-activated protein kinase in graft-versus-host disease (GVHD) causing cells.

alloHSCT is a curative therapy for many life-threatening conditions, but its benefits are often overshadowed by the risks of acute GVHD where donor T cells attack and destroy tissues in the host, notably the skin, liver, and gastrointestinal tract. Targeting the specialized metabolism of alloreactive T cells represents one way to overcome the risks of GVHD, but still retain the benefits of immune reconstitution and graft-versus-tumor effects.

Dr. Byersdorfer’s new investigation will probe the mechanisms of why alloreactive T cells lacking the AMP-activated protein kinase cause less GVHD. The end goal will be to translate these findings into human T cells in an effort to design better therapies for GVHD and comparable T cell-mediated immune disorders.

Technical Abstract

New therapies to distinguish pathogenic T cells from T cells mediating beneficial immune responses are necessary to improve the safety and applicability of alloHSCT. Previous work by Dr. Byersdorfer’s team, along with current preliminary data suggest that targeting alloreactive T cell metabolism may allow for this selective intervention. Specifically, the data demonstrate that the deletion of AMPK in donor cells mitigates GVHD but still preserves lymphopenia-driven immune reconstitution and T cell-driven graft-versus-tumor (GVT) effects.

Mechanistically, Dr. Byersdorfer’s data further suggest that lower rates of GVHD result from a decreased sensitivity of AMPK knock-out (KO) cells to the effects of pro-inflammatory cytokines. From this, the research team has formed the central hypothesis that AMPK is activated early posttransplant in a tissue-specific fashion, increasing local T cell sensitivity to pro-inflammatory cytokines. In the absence of AMPK, inflammatory signals are blunted, stabilizing regulatory T cell (Treg) development and decreasing effector responses. These changes mitigate GVHD, while GVT responses are unaffected because increased cytokine sensitivity is unnecessary for inducing leukemia-directed cytotoxicity and because leukemia clearance occurs at sites where AMPK activation is less pronounced.

Dr. Byersdorfer’s team will test this hypothesis in the new study with three specific aims. The first aim will determine the location and temporal necessity of AMPK by eliminating AMPK in T cells at defined times posttransplant and quantitating AMPK activation in cells recovered from multiple tissues simultaneously. The relationship between AMPK activation and cytokine sensitivity also will be defined by measuring cytokine responses following stimulation with an array of AMPK agonists.
The second aim of the study will elucidate mechanisms linking AMPK deficiency to improved GVHD and decreased cytokine sensitivity by comparing the GVHD potential of single KO cells to cells lacking both AMPK and the interleukin-6 (IL-6) receptor. In addition, mass spectrometry will be used to measure phosphorylation of novel AMPK target proteins in cytokine-stimulated and alloreactive T cells.

The final aim of the study will determine the GVHD and GVT potential of AMPK-deficient human T cells after decreasing AMPK levels using CRISPR/Cas9 gene editing and short hairpin RNA transduction, followed by transplantation of modified cells into xenogeneic models of GVHD and immunodeficient models of GVT.

These studies will deepen the understanding of AMPK activation, how this activation impacts cytokine sensitivity, and whether these findings can be translated into human cells. If successful, Dr. Byersdorfer’s studies will define a novel mechanism linking energy sensing to T cell effector function that will likely extend beyond GVHD to include the robust and sustained activation of any T cell, including during autoimmunity and following solid organ transplantation.