Tumor microenvironment in esophageal adenocarcinoma: A fight between immunity and tolerance

229 The efficacy of therapeutic Dendritic Cell vaccination against cancer to raise an anti-tumour T-cell response has recently been questioned because of the limited rate of clinical outcomes. It has been demonstrated that in cancer patients the immune system is tolerant to tumour growth and metastasis and it is speculated that one of the reason for this phenomenon is the immune-suppressive tumour microenvironment. Immune suppression can be mediated by several growth factors and cytokines that impair adequate immune responses. The main goal of this study is to gain insight in the immunologic tumour environment of esophageal adenocarcinomas by determining the expression of several growth modulating factors, and assessing the cytokine profile. To this aim, biopsies of both tumour and normal tissues were collected during endoscopy procedure from 14 esophageal adenocarcinoma patients, snap frozen and used either to stain them for the factors: HER-2, COX-2, VEGF, TGF-beta, Indoleamine 2,3-Dyoxigenase (IDO), CXCR1 and CXCL3, using fluorescent immuno-histochemistry, or to isolate RNA to measure mRNA levels of several cytokines, such as IL6, IL10, IL12, IL8, IL1-beta by quantitative PCR (Taqman), or to obtain lysates to measure cytokine protein levels by performing cytometric bead array (CBA). Immunohistochemistry showed that HER-2, COX-2, VEGF, and TGF-beta expression is up-regulated in the tumour biopsies in 80% of the patients analyzed, as compared to the expression in the normal biopsies. IDO expression was significantly higher in tumour tissues as compared to normal tissues in 90% of the patients analyzed, as well as the CXCR1 and CXCL3. CBA assay showed that IL-8 and IL-1 beta levels are significantly higher in the tumour tissues compared to normal tissues, in 13 (90%) and 8 (60%) of the cases respectively. IL-6 was up-regulated only in 6 of the cases (28%) and IL-10, IL-12, IL-4, TNF-alpha and IFN-gamma were not detected in any of the tumour as not in the normal lysates. Quantitative PCR using Taqman confirmed that IL-8 mRNA level is significantly higher in the tumor of 90% of the cases, and significantly lower in the normal biopsies, whereas analysis of the mRNA levels of IL-6, IL-1 beta, IL-10 and IL-12 didn’t prove any expression neither in normal nor in tumor tissues. From these results, we conclude that tumour environment is characterized by a lack of molecules enhancing the immune-response against cancer, and by a wide range of immuno-suppressive growth factors and cytokines. For future treatment of patients with immunotherapy it will be of importance to combine this strategy with tumour environment modulating agents in order to achieve a powerful immunogenic environment that may significantly improve tumour response.