Early-Stage IL-15 Signaling Paradoxically Subverts Human NK Cell Maturation and KIR Acquisition — ASN Events
  1. Schedule
  2. Lightning Session Two
  3. Early-Stage IL-15 Signaling Paradoxically Subverts Human NK Cell Maturation and KIR Acquisition

Early-Stage IL-15 Signaling Paradoxically Subverts Human NK Cell Maturation and KIR Acquisition (#265)

Michael A Ruesch 1 2 3 4 , Noah Koenigs 1 3 4 , Caprice D Eisele 1 3 4 , Megan Broughton 1 , Isaac Elmer 5 , Kyoko Yamaguchi 1 3 6 , Kinda Sara 1 4 , Ansel P Nalin 7 , Amir Horowitz 8 , Stephen K Anderson 9 , Bethany L Mundy-Bosse 1 10 , Christopher C Oakes 1 6 10 , Aharon Freud 1 4
  1. Ohio State University Comprehensive Cancer Center, Ohio State University, Columbus, OH, United States
  2. Medical Scientist Training Program, Ohio State University, Columbus, OH, United States
  3. Biomedical Sciences Graduate Program, Ohio State University, Columbus, OH, United States
  4. Department of Pathology, Ohio State University, Columbus, OH, United States
  5. Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States
  6. Department of Bioinformatics, Ohio State University, Columbus, OH, United States
  7. Department of Radiation Oncology, MD Anderson, Houston, TX, United States
  8. Department of Immunology and Immunotherapy, Icahn School of Medicine at Mount Sinai, New York, NY, United States
  9. Basic Science Program, Frederick National Laboratory for Cancer Research, Frederick, MD, United States
  10. Division of Hematology, Ohio State University, Columbus, OH, United States

Interleukin (IL)-15 is essential for human NK cell development and KIR acquisition. However, despite the presence of high amounts of IL-15, most NK cells derived in vitro from CD34+ hematopoietic progenitor cells (HPCs) or reconstituted in vivo following hematopoietic stem cell transplantation (HSCT) are hypomature and lack KIRs. We hypothesized that the timing of IL-15 exposure impacts NK cell maturation and KIR acquisition. Human blood CD34+ HPCs were cultured ex vivo with OP9-DL1 stroma and with FLT3 ligand (FL), c-KIT ligand (KL), and IL-3 for two weeks followed by FL and KL without IL-3 for two more weeks. IL-15 was also added either continuously (15-C) starting at day 0 (d0) or delayed (15-D) starting at d14. At d28, the 15-D NK cells produced more IFN-γ, killed more K562 target cells, and expressed significantly more KIRs than 15-C NK cells. 15-D NK cells also more closely matched ex vivo isolated NK cells by epigenetic and transcriptional profiling. At d14, we identified a Lin-NKp46+CD161+CD94+KIR- NK precursor population in both conditions, but only precursors from 15-D cultures generated KIR+ NK cells in single cell cloning assays. Epigenetic and transcriptional analyses of this precursor population highlighted distinct patterns in the two conditions and suggested intrinsic priming for KIR acquisition and maturation in 15-D NK precursors. Mechanistically, chemical inhibition of factors downstream of IL-15 (AKT, MEK/ERK, mTOR, STAT3, and STAT5) during only the first two weeks of 15-C cultures revealed that mTOR inhibition uniquely restored NK cell function and KIR acquisition. Together, these findings reveal a previously unknown developmental window during which IL-15 signaling through mTOR can paradoxically suppress human NK cell maturation and KIR acquisition. The observed inhibitory effects of early IL-15 signaling have important implications for the design and generation of NK cell adoptive therapies and for optimizing NK cell functions following HSCT.