Extracellular DNA as a Prognostic and Therapeutic Target in Mouse Colitis under DNase I Treatment.

The aim of this study was to investigate the potential of extracellular DNA as a prognostic and/or therapeutic target in inflammatory bowel disease. Fifty male C57BL/6J mice were used in the experiment. Acute colitis was induced by intake of 2% dextran sulphate sodium (DSS) for seven days followed by three days of water intake. DNase I was injected intravenously on days 3 and 7. Plasmatic levels of extracellular DNA (ecDNA) were measured on days 6 and 10. Weight loss, stool consistency and liquid intake were monitored throughout the experiment. Colon length and weight, myeloperoxidase activity and tumour necrosis factor α (TNF-α) levels were measured at sacrifice. DSS-treated mice displayed severe colitis, as shown by disease activity parameters. Both groups with colitis (DNase treated and untreated) had significantly poorer weight loss, colon length and stool consistency compared with control groups on water. No differences between the DNasetreated and untreated DSS groups were recorded. Myeloperoxidase activity and levels of TNF-α in colonic tissue were notably greater in both groups with colitis compared to controls. In addition, both biochemical markers were improved in the DNasetreated group with colitis compared to the untreated group. Although the disease activity was proved by several independent parameters in both groups with colitis, levels of ecDNA did not show any difference between the groups throughout or at the end of experiment. The role of ecDNA in experimental colitis has not been confirmed. However, DNase I injection resulted in some improvement, and thus should be studied in more detail.

Beneficial effects of live and dead Salmonella-based vector strain on the course of colitis in mice.

Dysbiosis of intestinal microbiota and hyperactive immune responses seem to be crucial for the uncontrolled inflammation in inflammatory bowel diseases (IBD). Modulation of the microbiome and immune stimulation of the intestinal epithelium were suggested as therapeutic approaches. In this study, live attenuated and dead bacterial cells of Salmonella Typhimurium SL7207 - a widely used bacterial vector for gene therapy were administered in DSS-induced colitis in mice. C57BL/6 mice were divided into four groups. The first group received pure water (CTRL). The other three groups received 2% dextran sulphate sodium (DSS) to induce colitis. Two DSS groups were treated with live attenuated (DSS live) or inactivated (DSS dead) Salmonella by gastric gavage. Intake of 2% DSS caused weight loss in all DSS groups compared to control mice with some improvement in DSS live group on the last day of the experiment. Significantly longer colon and improved stool consistency were reported in DSS live group, but not DSS dead group, when compared with DSS. Significant enlargement of spleens was observed only in DSS and DSS dead groups compared to control. Significant differences in stool consistency, colon length and spleen enlargement were observed between DSS live and DSS dead groups with beneficial effects of live bacteria. Interestingly, significant decrease in myeloperoxidase activity was detected in both, DSS live and DSS dead groups compared to the DSS group. On the basis of these results, progression of colitis seems to be beneficially influenced not only by live attenuated but to some extent also by inactivated Salmonella Typhimurium SL7207. Our results provide evidence that Salmonella-based gene therapy vectors are able to positively alter gut homeostasis during DSS-induced colitis. SIGNIFICANCE AND IMPACT OF THE STUDY: Restoration of gut homeostasis has a great importance in IBD. Here, we tested the nonspecific effect of the strain Salmonella Typhimurium SL7207 on the course of colitis to find out whether the potential effect would be mediated by activity of live bacterial cells or by bacterial structures that are also present in dead bacteria. Live bacterial therapy of colitis showed a beneficial effect on clinical signs as well as on macroscopic and inflammatory markers of colitis. On the other hand, therapy with dead bacteria showed inconsistent effects, negative in most clinical outcomes, positive especially in myeloperoxidase activity. Our data indicate that the beneficial effect of bacterial gene therapy vectors carrying therapeutic genes might be, at least partially, caused by the bacterial vector instead of the therapeutic gene.

Anthocyanin-Rich Diet in Chemically Induced Colitis in Mice.

The aetiology of inflammatory bowel diseases is unclear, but oxidative stress plays a key role in the pathogenesis. Anthocyanins--plant polyphenols--were shown to have antioxidant and anti-inflammatory properties. The aim of this study was to investigate the potential protective effects of anthocyanins on the oxidative status in mice with chemically induced colitis. Adult male mice were randomly divided into a control group drinking tap water and a colitis group drinking 1% dextran sulphate sodium solution. Animals had ad libitum access to a control wheat-based diet or food based on wheat producing anthocyanins. Bodyweight and stool consistency were monitored daily for 14 days. At the end of the experiment, colon length was measured and tissue samples were collected for the assessment of histology and oxidative status. Mice with colitis had lower body weight, higher stool score and shorter colon than control mice. Anthocyanins had neither an effect on stool consistency, nor on bodyweight loss and colon length. In the colon, liver and plasma, analysis of oxidative stress markers and antioxidant status revealed no significant differences between the groups. Food made from wheat producing anthocyanins did not protect mice from the consequences of chemically induced colitis. The measured biomarkers do not confirm the role of oxidative stress in this model of colitis. Further optimization of the anthocyanin-rich food might be needed before further experiments are conducted.