The indoleamine 2,3-dioxygenase pathway controls complement-dependent enhancement of chemo-radiation therapy against murine glioblastoma

• Type of Material: Article
• Authors: Minghui Li, Georgia Regents University; Aaron R Bolduc, Georgia Regents University; Md Nasrul Hoda, Georgia Regents University; Denise N Gamble, Georgia Regents University; Sarah-Bianca Dolisca, Georgia Regents University; Anna K Bolduc, Georgia Regents University; Kelly Hoang, Georgia Regents University; Claire Ashley, Georgia Regents University; David McCall, Georgia Regents University; Amyn M Rojiani, Georgia Regents University; Bernard L Maria, Georgia Regents University; Olivier Rixe, Georgia Regents University; Tobey MacDonald, Emory University; Peter S Heeger, The Immunology Institute; Andrew L Mellor, Georgia Regents University; David H Munn, Georgia Regents University; Theodore S Johnson, Georgia Regents University
• Language: English
• Date: 2014-07-07
• Publisher: BioMed Central
• Publication Version: Final Published Version
• Copyright Statement: © 2014 Li et al.; licensee BioMed Central Ltd.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://www.immunotherapyofcancer.org/content/2/1/21
• Title of Journal or Parent Work: Journal for ImmunoTherapy of Cancer
• ISSN: 2051-1426
• Volume: 2
• Issue: 21
• Grant/Funding Information: This study was supported by the Alex’s Lemonade Stand Foundation (to TSJ), Hyundai Hope on Wheels Foundation (to TSJ), the Beez Foundation (to TSJ), the Elizabeth and Lovick Corn Foundation (to DHM), the Virendra Mahesh Research Award (to DHM), the National Cancer Institute, NIH (R01 CA112431 to DHM), and the National Institute of Allergy and Infectious Diseases, NIH (R01 AI071185 to PSH, R01 AI103447 to ALM, and U01 AI083005 to ALM).
• Keywords: Indoleamine; Chemotherapy; Radiation therapy; Complement; NLG919; Tumor; IDO; Immunotherapy; Indoximod
• Research Categories: Health Sciences, Oncology; Health Sciences, Pathology; Health Sciences, Immunology

Abstract

Background: Indoleamine 2,3-dioxygenase (IDO) is an enzyme with immune-suppressive properties that is commonly exploited by tumors to evade immune destruction. Anti-tumor T cell responses can be initiated in solid tumors, but are immediately suppressed by compensatory upregulation of immunological checkpoints, including IDO. In addition to these known effects on the adaptive immune system, we previously showed widespread, T cell-dependent complement deposition during allogeneic fetal rejection upon maternal treatment with IDO-blockade. We hypothesized that IDO protects glioblastoma from the full effects of chemo-radiation therapy by preventing vascular activation and complement-dependent tumor destruction. Methods: To test this hypothesis, we utilized a syngeneic orthotopic glioblastoma model in which GL261 glioblastoma tumor cells were stereotactically implanted into the right frontal lobes of syngeneic mice. These mice were treated with IDO-blocking drugs in combination with chemotherapy and radiation therapy. Results: Pharmacologic inhibition of IDO synergized with chemo-radiation therapy to prolong survival in mice bearing intracranial glioblastoma tumors. We now show that pharmacologic or genetic inhibition of IDO allowed chemo-radiation to trigger widespread complement deposition at sites of tumor growth. Chemotherapy treatment alone resulted in collections of perivascular leukocytes within tumors, but no complement deposition. Adding IDO-blockade led to upregulation of VCAM-1 on vascular endothelium within the tumor microenvironment, and further adding radiation in the presence of IDO-blockade led to widespread deposition of complement. Mice genetically deficient in complement component C3 lost all of the synergistic effects of IDO-blockade on chemo-radiation-induced survival. Conclusions: Together these findings identify a novel mechanistic link between IDO and complement, and implicate complement as a major downstream effector mechanism for the beneficial effect of IDO-blockade after chemo-radiation therapy. We speculate that this represents a fundamental pathway by which the tumor regulates intratumoral vascular activation and protects itself from immune-mediated tumor destruction.