Signals through 4-1BB inhibit T regulatory cells by blocking IL-9 production enhancing antitumor responses

• Published in: Cancer Immunology, Immunotherapy Immunotherapy, 2011-12, Vol.60 (12), p.1775-1787
• Main Authors: Smith, Shannon E., Hoelzinger, Dominique B., Dominguez, Ana Lucia, Van Snick, Jacques, Lustgarten, Joseph
• Format: Article
• Language: English
• Subjects: Adjuvants; Animals; Antibodies; Antineoplastic agents; Antitumor activity; Biological and medical sciences; Cancer; Cancer Research; Cancer vaccines; Cell Separation; DNA microarrays; Enzyme-Linked Immunosorbent Assay; Flow Cytometry; Immune response; Immunology; Immunoregulation; Immunotherapy; Immunotherapy - methods; Inflammation; Interleukin 9; Interleukin-9 - biosynthesis; Interleukin-9 - immunology; Lymphocytes; Lymphocytes T; Medical sciences; Medicine; Medicine & Public Health; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Transgenic; Neoplasms, Experimental - immunology; Oligodeoxyribonucleotides - immunology; Oncology; Original Article; Pathogens; Pharmacology. Drug treatments; Receptor mechanisms; Signal Transduction - immunology; T cell receptors; T-Lymphocytes, Regulatory - immunology; Transcription; Transgenic animals; Transgenic mice; Tumor Necrosis Factor Receptor Superfamily, Member 9 - antagonists & inhibitors; Tumor Necrosis Factor Receptor Superfamily, Member 9 - immunology; Tumors; Vaccines
• ISSN: 0340-7004; 1432-0851
• DOI: 10.1007/s00262-011-1075-6

Previous studies from our laboratory indicate that intratumoral (i.t.) injections of CpG-ODN are the most effective adjuvant strategy to induce an antitumor immune response in tolerant BALB-neuT mice but insufficient for tumor eradication. We evaluated whether this treatment strategy could be enhanced by the presence of anti-OX40 and anti-4-1BB antibodies. Treatment with anti-4-1BB resulted in a greater antitumor response than anti-OX40. The results indicate that anti-4-1BB but not anti-OX40 inhibited the suppressive function of T regulatory cells (Tregs). Through microarray analysis we evaluated the mechanism by which anti-4-1BB inhibits iTregs using the Foxp3-GFP mice. We observed specific transcriptional differences in over 100 genes in iTregs treated with anti-4-1BB, and selected those genes that remained unaffected by exposure to anti-OX40. Interleukin 9 was transcriptionally down-regulated 28-fold by anti-4-1BB treatment, and this was matched by a significant reduction of IL-9 secretion by iTregs. Furthermore, blockade of the common γ-chain receptor resulted in the inhibition of iTreg-suppressive function. More importantly, neutralization of IL-9 plus i.t. injections of CpG-ODN induces tumor rejection in BALB-neuT and MUC-1 tolerant transgenic mice. These results indicate that IL-9 plays a role in iTreg biology during the tumor inflammatory process enhancing/promoting the suppressive function of these cells and that the blockade of IL-9 could serve as a novel strategy to modulate the function of Tregs to enhance the antitumor effect of tumor vaccines.