161P - Effect of E.coli phage lysate vaccinations on CD4 + CD25 + FoxP3+ T-regulatory cells and cytokine levels in cancer bearing mice

Date 28 September 2014
Event ESMO 2014
Session Poster Display session
Topics Basic Science
Cancer Immunology and Immunotherapy
Presenter Ketevan Gambashidze
Citation Annals of Oncology (2014) 25 (suppl_4): iv53-iv57. 10.1093/annonc/mdu325
Authors K. Gambashidze1, I. Pantsulaia2, M. Iobadze2, T. Azaladze1, A. Azaladze1, K. Kalandarishvili3, P. Khorava4, E. Jaiani5, B. Lasareishvili5, M. Tediashvili5
  • 1Pathophysiology, Tbilisi State Medical University, 0177 - Tbilisi/GE
  • 2Immunology, Tbilisi State Medical University, 0177 - Tbilisi/GE
  • 3Clinical Anatomy, Tbilisi State Medical University, 0177 - Tbilisi/GE
  • 4Surgery, Georgian National Cancer Center, 0177 - Tbilisi/GE
  • 5Phages, Eliava Institute of Bacteriophage, Microbiology and Virology, 0171 - Tbilisi/GE

Abstract

Aim

Regulatory T cells (Treg) play a key role in maintaining the balance of immune responses in human health and in disease. Generally, Tregs are considered as the most powerful inhibitors of antitumor immunity and the greatest barrier to successful immunotherapy and vaccinations. Modulation of Tregs can enhance the efficacy of cancer immunotherapy and has potential to result in tumor regression. The aim of this study was to stimulate antitumor innate immunity via suppression of Treg and activation of effector immune cells using E.coli phage lysate vaccinations.

Methods

Specimen (spleen, blood serum) were obtained from control (with Ehrlich carcinoma) and E.coli phage lysate vaccinated (0,25 ml/day, with 5 day intervals, during 5 weeks) 20–25 g C57BL/6J mice. Number of CD4+CD25+FoxP3+ Treg as well as CD3+CD4+, CD3+CD8+, NK1.1 cells were assessed using FACS Array Bioanalyzer (BD FACSCalibur, USA) and WST-8 Cell Proliferation Assay Kit. Isolated cells were stained by fluorochrome conjugated antibodies (anti-CD3, Foxp3, NK1.1, anti-CD4, anti-CD8, anti-CD25 and isotype-matched controls). Two-color data analysis for CD4CD8, CD3CD4, CD4CD25, CD25Foxp3 staining was performed using dot plots with WinMDI Software. Cytokines: IL-12, TGF-ß, IFN-ɣ were studied by ELISA according to manufactures protocol (R&D systems; BD Biosciences).

Results

Investigations have shown that E.coli phage lysate vaccinations stimulate innate and further acquired immunity manifested by increase in NK1.1, CD3CD4, CD3CD8 cells and secretion of IL-12, IFN-ɣ with further decrease in TGF-ß, CD4CD25, CD25Foxp3 compared to control. More than 5 vaccinations had no effect and further vaccinations decreased immune response. Our results indicate that although vaccinations enhance antitumor immunity and host defenses decreasing Tregs and stimulating CD3+CD4+, CD3+CD8+, NK1.1 effector immune cells, the successful treatment requires optimal regimen of vaccination.

Conclusions

E.coli phage lysate vaccinations have in vivo antitumor immunomodulatory effect and can be considered as a new immunotherapeutic approach of cancers.

Disclosure

All authors have declared no conflicts of interest.