Monitoring and functional characterization of the lymphocytic compartment in pancreatic ductal adenocarcinoma patients.

BACKGROUND/OBJECTIVES: Pancreatic ductal adenocarcinoma (PDAC) still has a poor prognosis and current treatments including immunotherapy often fail. This might be due to the pronounced immunosuppressive milieu impairing infiltration and function of immune effector cells. This study aimed at a comprehensive analysis of immune cells in PDAC patients by determining absolute and relative peripheral blood cell numbers of immune cell subsets along with their functional capacity. METHODS: Whole blood cells or isolated peripheral blood mononuclear cells were characterized by flow cytometry. PDAC tissues were analyzed by immunohistochemistry. Anti-tumor activity of immune effector cells was determined by RTCA system. RESULTS: Our data demonstrate that relative CD4+ memory- and regulatory T cell numbers were enhanced, whereas determination of absolute cell numbers revealed generally lower immune cell numbers in PDAC patients compared to healthy controls. γδ T cells accumulated at higher numbers compared to αß T cells in the malignant ductal epithelium of PDAC tissues indicating that γδ T cells infiltrate into the tumor. Cytotoxicity against tumor cells of even small numbers of T- and NK cells could be induced by a bispecific antibody targeting CD3+ T cells to human epidermal growth factor receptor (HER)2 expressing PDAC cells or Trastuzumab. Importantly, a critical number of γδ T cells was required for significant tumor cell killing by a bispecific antibody engaging the γδ T cell receptor on γδ T cells and HER2 on tumor cells. CONCLUSION: Monitoring immune cells along with the determination of their functional capacity provides a comprehensive assessment as a prerequisite for a personalized immunotherapeutic PDAC treatment.

[A 40-year-old patient with diffuse pain in the lower backbone]. / 40-jährige Patientin mit diffusen Schmerzen im Bereich der Lendenwirbelsäule.

CASE REPORT: A 40-year-old female patient with pancreatic cancer stage IV and multiple liver metastases is reported. Palliative chemotherapy was performed with gemcitabine monotherapy. A good control of tumor growth as well as tumor-related symptoms could be achieved for years. Finally, a rapid progression within 2 months resulted in the patient's death. CONCLUSION: This case report demonstrates the problems of modern pancreatic cancer therapy. The goals of therapy are cancer control and control of tumor-related symptoms. New agents and the inclusion of tumor biology and mechanism of resistance should result in individual treatment strategies.

Tumor stroma interactions induce chemoresistance in pancreatic ductal carcinoma cells involving increased secretion and paracrine effects of nitric oxide and interleukin-1beta.

Pancreatic ductal carcinoma is characterized by a profound chemoresistance. As we have shown previously, these tumor cells can develop chemoresistance by interleukin (IL)-1beta in an autocrine and nuclear factor-kappaB-dependent fashion. Because pancreatic ductal carcinoma contains many mesenchymal stromal cells, we further investigated how tumor-stroma interactions contribute to chemoresistance by using a transwell coculture model, including murine pancreatic fibroblasts and the chemosensitive human pancreatic carcinoma cell lines T3M4 and PT45-P1. If cultured with fibroblast-conditioned medium or kept in coculture with fibroblasts, both cell lines became much less sensitive toward treatment with etoposide than cells cultured under standard conditions. Furthermore, the secretion of IL-1beta in T3M4 and PT45-P1 cells was increased by the fibroblasts, and IL-1beta-receptor blockade abolished the resistance-inducing effect during cocultivation. This stimulated IL-1beta secretion could be attributed to nitric oxide (NO) released by the fibroblasts as an IL-1beta-inducing factor. Although both tumor cells secreted only little NO, which was in line with undetectable inducible nitric oxide synthase (iNOS) expression, fibroblasts exhibited significant iNOS expression and NO secretion that could be further induced by the tumor cells. Incubation of T3M4 and PT45-P1 cells with the NO donor S-Nitroso-N-acetyl-D,L-penicillamine up-regulated IL-1beta secretion and conferred resistance toward etoposide-induced apoptosis. Conversely, the resistance-inducing effect of the fibroblasts was significantly abolished, when the specific iNOS inhibitor aminoguanidine was added during coculture. Immunohistochemistry on tissue sections from human pancreatic ductal carcinoma also revealed iNOS expression in stromal cells and IL-1beta expression in tumor cells, thus supporting the in vitro findings. These data clearly demonstrate that fibroblasts contribute to the development of chemoresistance in pancreatic carcinoma cells via increased secretion of NO, which in turn leads to an elevated release of IL-1beta by the tumor cells. These findings substantiate the implication of tumor-stromal interactions in the chemoresistance of pancreatic carcinoma.

Viral IFN-regulatory factors inhibit activation-induced cell death via two positive regulatory IFN-regulatory factor 1-dependent domains in the CD95 ligand promoter.

The CD95 (also called APO-1/Fas) system plays a major role in the induction of apoptosis in lymphoid and nonlymphoid tissues. The CD95 ligand (CD95L) is induced in response to a variety of signals, including IFN-gamma and TCR/CD3 stimulation. Here we report the identification of two positive regulatory IFN-regulatory factor-dependent domains (PRIDDs) in the CD95L promoter and its 5' untranslated region, respectively. EMSAs demonstrate specific binding of IFN-gamma-induced IFN-regulatory factor 1 (IRF-1) to the PRIDD sequences. Ectopic IRF-1 expression induces CD95L promoter activity. Furthermore, we demonstrate that PRIDDs play an important role in TCR/CD3-mediated CD95L induction. Most interestingly, viral IRFs of human herpes virus 8 (HHV8) totally abolish IRF-1-mediated and strongly reduce TCR/CD3-mediated CD95L induction. We demonstrate here for the first time that viral IRFs inhibit activation-induced cell death. Thus, these results demonstrate an important mechanism of HHV8 to modulate the immune response by down-regulation of CD95L expression. Inhibition of CD95-dependent T cell function might contribute to the immune escape of HHV8.