Upregulation of PD-1 follows tumour development in the AOM/DSS model of inflammation-induced colorectal cancer in mice.

Chronic inflammation may drive development of cancer as observed in inflammation-induced colorectal cancer (CRC). Though immune cells can infiltrate the tumour microenvironment, cancer cells seem to evade anti-tumour responses, which is one of the established hallmarks of cancer. Targeting the programmed cell death protein-1 (PD-1)/PD-L1 signalling pathway is currently at the forefront in the development of anti-tumour immunity-based therapies for multiple malignancies. By blocking the immune-checkpoint of activated T-cells, it is possible to rewire the adaptive resistance induced by the PD-1 ligands expressed in the tumour microenvironment. However, adverse immunotherapy-modulated events could complicate the treatment of individuals with preexisting chronic inflammatory conditions. In this study, we investigated the expression of different systemic and mucosal T-cell subsets during the course of azoxymethane (AOM)/dextran sulphate sodium (DSS)-induced colitis and colitis-associated CRC. In addition, we examined the expression of PD-1 and its ligands PD-L1 and PD-L2 as well as other molecular targets related to T-cell exhaustion. We found a significant increase in PD-1 expression on all examined mucosal T-cell subsets of the colon and the ileum, which correlated with disease progression. We also observed an upregulation of PD-L1 and PD-L2 mRNA expression throughout the AOM/DSS regime. Blocking PD-1 signalling with an anti-PD1 antibody did not affect the tumour burden in the AOM/DSS-treated mice, but did potentiate the weight loss in the third DSS cycle, indicating possible immune-mediated toxicity. This raises a concern for patients with colitis-associated CRCs and should be further investigated.

Rectal Insulin Instillation Inhibits Inflammation and Tumor Development in Chemically Induced Colitis.

BACKGROUND AND AIMS: Epithelial expression of the insulin receptor in the colon has previously been reported to correlate with extent of colonic inflammation. However, the impact of insulin signalling in the intestinal mucosa is still unknown. Here, we investigated the effects of inactivating the epithelial insulin receptor in the intestinal tract, in an experimental model of inflammation-induced colorectal cancer. METHODS: The mice were generated by utilizing the intestinal- and epithelial-specific villin promoter and the Cre-Lox technology. All mice included in the cohorts were generated by crossing [vil-Cre-INSR+/-] × [INSRfl/fl] to obtain [vil-Cre-INSR-/-], and their floxed littermates [INSRfl/fl] served as the control group. For the intervention study, phosphate-buffered saline with or without insulin was instilled rectally in anaesthetized wild-type mice with chemically induced colitis. RESULTS: We found higher endoscopic colitis scores together with potentiated colonic tumorigenesis in the knockout mice. Furthermore, we showed that topically administered insulin in inflamed colons of wild-type mice reduced inflammation-induced weight loss and improved remission in a dose-dependent manner. Mice receiving rectal insulin enemas exhibited lower colitis endoscopic scores and reduced cyclooxygenase 2 mRNA expression, and developed significantly fewer and smaller tumours compared with the control group receiving phosphate-buffered saline only. CONCLUSIONS: Rectal insulin therapy could potentially be a novel treatment, targeting the epithelial layer to enhance mucosal healing in ulcerated areas. Our findings open up new possibilities for combination treatments to synergize with the existing anti-inflammatory therapies.

Effects of household washing on bacterial load and removal of Escherichia coli from lettuce and "ready-to-eat" salads.

Customer demands for fresh salads are increasing, but leafy green vegetables have also been linked to food-borne illness due to pathogens such as Escherichia coli O157:H7. As a safety measure, consumers often wash leafy vegetables in water before consumption. In this study, we analyzed the efficiency of household washing to reduce the bacterial content. Romaine lettuce and ready-to-eat mixed salad were washed several times in flowing water at different rates and by immersing the leaves in water. Lettuce was also inoculated with E. coli before washing. Only washing in a high flow rate (8 L/min) resulted in statistically significant reductions (p < .05), "Total aerobic count" was reduced by 80%, and Enterobacteriaceae count was reduced by 68% after the first rinse. The number of contaminating E. coli was not significantly reduced. The dominating part of the culturable microbiota of the washed lettuce was identified by rRNA 16S sequencing of randomly picked colonies. The majority belonged to Pseudomonadaceae, but isolates from Enterobacteriaceae and Staphylococcaceaceae were also frequently found. This study shows the inefficiency of tap water washing methods available for the consumer when it comes to removal of bacteria from lettuce. Even after washing, the lettuce contained high levels of bacteria that in a high dose and under certain circumstances may constitute a health risk.