Aplastic anemia (AA) is a rare disease characterized by immune-mediated suppression of bone marrow (BM) function resulting in progressive pancytopenia. Stem cell transplant and immunosuppressive therapies remain the major treatment choices for AA patients with limited benefit and undesired side effects. Here, we report for the first time the therapeutic utility of Nrf2-induced metabolically reprogrammed tolerogenic dendritic cells (TolDCs) in the suppression of AA in mice. CDDO-DFPA-induced Nrf2 activation resulted in a TolDC phenotype as evidenced by induction of IL-4, IL-10, and TGF-β and suppression of TNFα IFN-γ and IL-12 levels in Nrf2+/+ but not Nrf2−/− DCs. Cellular metabolism holds the key to determining DC immunogenic or tolerogenic cell fate. Although immature and LPS-induced (mature) Nrf2+/+ and Nrf2−/− DCs exhibited similar patterns of oxidative phosphorylation (OXPHOS) and glycolysis, only Nrf2+/+ DCs partially restored OXPHOS and reduced glycolysis during CDDO-DFPA-induced Nrf2 activation. These results were further confirmed by altered glucose uptake and lactate production. We observed significantly enhanced HO-1 and reduced iNOS/NO production in Nrf2+/+ compared to Nrf2−/− DCs, suggesting Nrf2-dependent TolDC induction is linked to suppression of the inhibitory effect of NO on OXPHOS. Furthermore, Nrf2−/− DCs demonstrated higher antigen-specific T cell proliferation. Lastly, TolDC administration improved hematopoiesis and survival in AA murine model, with decreased Th17 and increased Treg cells. Concomitantly, immunohistochemical analysis of AA patient BM biopsies displayed higher DCs, T cells, and iNOS expression accompanied with lower Nrf2 and HO-1 expression when compared to normal subjects. These results provide new insight into the therapeutic utility of metabolically reprogrammed TolDCs by CDDO-DFPA induced Nrf2 signaling in the treatment of AA.
Bibliographical noteFunding Information:
We wish to thank Dr. Mukesh K. Jain for valuable discussions and assistance with the Seahorse XFp Analyzer, Jennifer Mikulan (CWRU Histology core), and Adam Kresek (CWRU IHC core) for their assistance with tissue analyses. We are thankful to Dr. Emily Barker for her editorial assistance. We also acknowledge the support of the Jane and Lee Seidman Chair in Pediatric Cancer Innovation (John Letterio). This work was supported by the Department of Defense (W81XWH-12-1-0452), the Angie Fowler Adolescent and Young Adult Cancer Research Initiative at the Case Comprehensive Cancer Center, the Amy Gaynor Fund at Rainbow Babies & Children's Hospital, and the Callahan Graduate Scholar Award for Hsi-Ju Wei from the F.J. Callahan Foundation.
© 2018 Elsevier Ltd
- Aplastic anemia
- Bone marrow failure
- Tolerogenic dendritic cell