A comprehensive review of the current and future role of the microbiome in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is expected to become the second most common cause of cancer death in the USA by 2030, yet progress continues to lag behind that of other cancers, with only 9% of patients surviving beyond 5 years. Long-term survivorship of PDAC and improving survival has, until recently, escaped our understanding. One recent frontier in the cancer field is the microbiome. The microbiome collectively refers to the extensive community of bacteria and fungi that colonise us. It is estimated that there is one to ten prokaryotic cells for each human somatic cell, yet, the significance of this community in health and disease has, until recently, been overlooked. This review examines the role of the microbiome in PDAC and how it may alter survival outcomes. We evaluate the possibility of employing microbiomic signatures as biomarkers of PDAC. Ultimately this review analyses whether the microbiome may be amenable to targeting and consequently altering the natural history of PDAC

Bile microbiome signatures associated with pancreatic ductal adenocarcinoma compared to benign disease: a UK pilot study

Pancreatic ductal adenocarcinoma (PDAC) has a very poor survival. The intra-tumoural microbiome can influence pancreatic tumourigenesis and chemoresistance and, therefore, patient survival. The role played by bile microbiota in PDAC is unknown. We aimed to define bile microbiome signatures that can effectively distinguish malignant from benign tumours in patients presenting with obstructive jaundice caused by benign and malignant pancreaticobiliary disease. Prospective bile samples were obtained from 31 patients who underwent either Endoscopic Retrograde Cholangiopancreatography (ERCP) or Percutaneous Transhepatic Cholangiogram (PTC). Variable regions (V3-V4) of the 16S rRNA genes of microorganisms present in the samples were amplified by Polymerase Chain Reaction (PCR) and sequenced. The cohort consisted of 12 PDAC, 10 choledocholithiasis, seven gallstone pancreatitis and two primary sclerosing cholangitis patients. Using the 16S rRNA method, we identified a total of 135 genera from 29 individuals (12 PDAC and 17 benign). The bile microbial beta diversity significantly differed between patients with PDAC vs. benign disease (Permanova p = 0.0173). The separation of PDAC from benign samples is clearly seen through unsupervised clustering of Aitchison distance. We found three genera to be of significantly lower abundance among PDAC samples vs. benign, adjusting for false discovery rate (FDR). These were Escherichia (FDR = 0.002) and two unclassified genera, one from Proteobacteria (FDR = 0.002) and one from Enterobacteriaceae (FDR = 0.011). In the same samples, the genus Streptococcus (FDR = 0.033) was found to be of increased abundance in the PDAC group. We show that patients with obstructive jaundice caused by PDAC have an altered microbiome composition in the bile compared to those with benign disease. These bile-based microbes could be developed into potential diagnostic and prognostic biomarkers for PDAC and warrant further investigation

Elevated myeloid-derived suppressor cells in pancreatic, esophageal and gastric cancer are an independent prognostic factor and are associated with significant elevation of the Th2 cytokine interleukin-13

We undertook a comprehensive analysis of circulating myeloid-derived suppressor cells (MDSCs) and T regulatory cells (Tregs) in pancreatic, esophageal and gastric cancer patients and investigated whether MDSCs are an independent prognostic factor for survival. We evaluated a series of plasma cytokines and in particular re-evaluated the Th2 cytokine interleukin-13 (IL-13). Peripheral blood was collected from 131 cancer patients (46 pancreatic, 60 esophageal and 25 gastric) and 54 healthy controls. PBMC were harvested with subsequent flow cytometric analysis of MDSC (HLADR− Lin1low/− CD33+ CD11b+) and Treg (CD4+ CD25+ CD127low/− FoxP3+) percentages. Plasma IL-2, IL-4, IL-5, IL-6, IL-10, IL-12 (p70), IL-13, IL-17, G-CSF, IFN-γ, TNF-α and VEGF levels were analyzed by the Bio-Plex cytokine assay. Plasma arginase I levels were analyzed by ELISA. MDSCs and Tregs were statistically significantly elevated in pancreatic, esophageal and gastric cancer compared with controls, and MDSC numbers correlated with Treg levels. Increasing MDSC percentage was associated with increased risk of death, and in a multivariate analysis, MDSC level was an independent prognostic factor for survival. A unit increase in MDSC percentage was associated with a 22% increased risk of death (hazard ratio 1.22, 95% confidence interval 1.06–1.41). Arginase I levels were also statistically significantly elevated in upper gastrointestinal cancer patients compared with controls. There was Th2 skewing for cytokine production in all three diseases, and importantly there were significant elevations of the pivotal Th2 cytokine interleukin-13, an increase that correlated with MDSC levels

T-cell memory: lessons from Epstein-Barr virus infection in man.

Epstein-Barr virus offers an ideal opportunity to follow the human T-cell response to a virus infection over time from its acute primary phase, as seen in infectious mononucleosis patients, into the memory phase that accompanies life-long virus persistence. Here we review recent evidence on the development and maturation of cytotoxic T-cell memory using this viral system

EN2:A candidate antigen for the development of targeted therapies in ovarian cancer.

Background: Ovarian cancer remains the most lethal gynaecologic tumour in the Western world. Stimulation of the immune system to consolidate response to chemotherapy can potentially be beneficial however so far none of the vaccination strategies have offered survival advantage. Thus identifying and targeting clinically relevant antigens for immunotherapy continues to be an important research strategy. We have evaluated Engrailed-2 (EN2) as a potential target for vaccine strategy. EN2 is a homeodomain-containing transcription factor with a multifunctional role in neural development. There is evidence that over-expression of EN2 protein maybe linked to tumour development. Methods: Ovarian cancer cell lines were analysed by FACS for EN2 cell surface expression. EN2 expression in ovarian cancer tissue arrays were done by immunohistochemistry. A serum analysis (ELISA) was done to evaluate the presence of antibodies to EN2 in ovarian cancer patients and age-matched controls. A set of potentially immunogenic HLA-A2 restricted epitopes from the EN2 protein was identified using a computer algorithm SYFPEITHI. These peptides have been tested on HLA-A2 positive ovarian cancer patients’ PBMC using an in vitro culture method. The specificity of these T cell lines was analysed against T2 target cells loaded with or without EN2 peptides Results: Cell surface expression of EN2 was observed in ovarian cancer cell lines OVCAR3, OV90, CaOV-3, ES-2 and SKOV-3 of which ES-2 and SKOV3 showed strong expression. EN2 was also present in approximately 80% of ovarian cancer tissues whereas EN-2 expression was very low (<10%) or absent in normal tissues. Out of the 67 ovarian cancer patients 20.9% (14/67) had antibodies against EN2 compared to 2.4% (1/42) of age-matched female controls. 4 of the identified EN2 epitopes were able to generate peptide specific cytotoxic T lymphocytes in the ovarian cancer patients tested. Conclusions: The over-expression and immunogenicity of EN2 in ovarian cancer makes it a credible antigen to exploit as a novel target for ovarian cancer immunotherapy.

Cancer cell-derived extracellular vesicles activate hepatic stellate cells in colorectal cancer

Colorectal cancer (CRC) is the 2nd leading cause of cancer-related deaths worldwide, primarily due to the development of metastatic disease. The liver is the most frequently affected site. The metastatic cascade relies on a complex interaction between the immune system, tumor, and distant organs. Communication between the tumor and the metastatic site can be mediated by tumor-derived extracellular vesicles (EVs) and their cargo. The mechanisms underlying this process are starting to be understood through research that has rapidly expanded over the past 15 years. One crucial aspect is the remodeling of the microenvironment at the site of metastasis, which is essential for the formation of a premetastatic niche and the subsequent establishment of metastatic deposits. In the evaluated study, the authors use cellular experiments and a mouse model to investigate how tumour derived extracellular vesicles and their microRNA contents interact with hepatic stellate cells (HSCs). They demonstrate how this may lead to remodelling of the microenvironment and the formation of colorectal liver metastasis using their experimental model. In this mini review, we examine the current evidence surrounding tumour derived EVs and their effect on the tumour microenvironment to highlight potential areas for future research in CRC and other malignancies.</p