45P - Hypoxia promotes IL-10 secretion by reactivated CTLs while limiting their expansion

Date 20 November 2015
Event ESMO Symposium on Immuno-Oncology 2015
Session Welcome reception and general Poster viewing
Topics Cancer Immunology and Immunotherapy
Presenter Romain Vuillefroy de Silly
Citation Annals of Oncology (2015) 26 (suppl_8): 5-14. 10.1093/annonc/mdv514
Authors R. Vuillefroy de Silly, M. Derouazi, P. Dietrich, P.R. Walker
  • Médecine Interne - Centre Of Oncology, Laboratory of tumor immunology-Hôpitaux Universitaires de Genève(HUG), 1202 - Geneva/CH

Abstract

Aim

Cytotoxic T Lymphocytes (CTLs) represent an attractive cell population to eradicate cancer, as reflected by the increasing number of strategies (i.e. vaccines and cell-based immunotherapies) that aim at improving their intratumoral effector functions. However, hypoxia is often found in solid tumors and its impact on tumor-infiltrating lymphocytes (TILs) is still unclear. As CTLs will face pathologically low oxygen fractions in the tumor, we aimed to decipher hypoxia impact on CTLs to understand how to fine-tune CD8+-based immunotherapies.

Methods

We studied clonal populations of gp100 and ova antigen-specific CD8+ T cells from Pmel-1 and OT-I mice, respectively. CTLs were generated under physiological oxygen fraction (physioxia; 5% O2), which can be found in lymph nodes, and CTLs were reactivated either under physioxia or hypoxia (1% O2), to mimic reactivation in the tumor bed, with αCD3/αCD28 –coated beads. Oxygen levels were controlled using a hypoxia workstation and hypoxic chambers. RNA profile, killing capacities, expansion and cytokine secretion were assayed. The experiments were recapitulated using CD8+ TILs from E.G7-bearing mice.

Results

Despite not modifying CTL killing capacities, hypoxia dramatically decreased cell expansion after CTL reactivation by decreasing both viability and proliferation rate. At the RNA and protein level, hypoxia did not cause major modifications, but it increased the expression of IL-2Rα, 4-1BB, and unexpectedly of IL-10. Of interest, IL-10 was induced even under physioxia, and its secretion was further enhanced under hypoxia, whereas it was weakly secreted under classical culture conditions (21% O2). Importantly, IL-10 expression and its enhancement under hypoxia were confirmed using CD8+ TILs ex vivo.

Conclusions

Our data show that hypoxia has immunosuppressive effects by limiting CTL expansion. Interestingly, we observed that the immunomodulatory cytokine IL-10 represents an unanticipated product of CTLs in vivo and that its secretion is enhanced under hypoxia. Further studies are ongoing to address whether IL-10 produced by CTLs have a role in tumor growth control. The results could help to guide optimisation of immunotherapy strategies using adoptive cell transfer.

Clinical trial identification

Disclosure

All authors have declared no conflicts of interest.