Susan Bengs

Doxycycline, metronidazole and isotretinoin: Do they modify microRNA/mRNA expression profiles and function in murine T-cells?

Inflammatory bowel disease (IBD) may develop due to an inflammatory response to commensal gut microbiota triggered by environmental factors in a genetically susceptible host. Isotretinoin (acne therapy) has been inconsistently associated with IBD onset and flares but prior treatment with antibiotics, also associated with IBD development, complicates the confirmation of this association. Here we studied in mice whether doxycycline, metronidazole or isotretinoin induce epigenetic modifications, and consequently change T-cell mRNA expression and/or function directly after treatment and after a 4 week recovery period. Isotretinoin induced IL-10 signaling in Tregs and naive T-cells directly after treatment and reduced effector T-cell proliferation alone and in co-culture with Tregs. Metronidazole activated processes associated with anti-inflammatory pathways in both T-cell subsets directly after the treatment period whereas doxycycline induced an immediate pro-inflammatory expression profile that resolved after the recovery period. Long-term changes indicated an inhibition of proliferation by doxycycline and induction of beneficial immune and metabolic pathways by metronidazole. Persistent alterations in microRNA and mRNA expression profiles after the recovery period indicate that all three medications may induce long-term epigenetic modifications in both T-cell subsets. Yet, our data do not support the induction of a long-term pro-inflammatory phenotype in murine Tregs and naive T-cells.

Effects of oral antibiotics and isotretinoin on the murine gut microbiota

Inflammatory bowel disease (IBD) may develop due to an immunogenic response to commensal gut microbiota triggered by environmental factors in the genetically susceptible host. Isotretinoin, applied in the treatment of severe acne, has been variably associated with IBD, but prior treatment with antibiotics, also associated with IBD development, confounds confirmation of this association. This study investigated the effects of doxycycline, metronidazole (frequently used in the treatment of acne and IBD, respectively) and isotretinoin on murine gut (faecal) microbiota after 2 weeks of treatment and after a 4-week recovery period. Faecal microbiota composition was assessed by 16S rRNA gene sequencing on the GS-FLX 454 platform with primers directed against the variable regions V1-V2. Doxycycline had a modest effect on bacterial richness and evenness, but had pronounced persistent and significant effects on the abundance of certain operational taxonomic units compared with the control group. In contrast, metronidazole induced a pronounced reduction in diversity after treatment, but these effects did not persist after the recovery period. This study demonstrates differential effects of antibiotics on the gut microbiota with doxycycline, unlike metronidazole, mediating long-term changes in the murine gut microbiota. Isotretinoin had no significant effect on the faecal microbiota.

Age- and sex-dependent changes in sympathetic activity of the left ventricular apex assessed by 18F-DOPA PET imaging

Background Sexual dimorphism in cardiac sympathetic outflow has recently gained attention in the context of Takotsubo cardiomyopathy. Previous studies suggest that there are sex- and age-dependent differences in peripheral autonomic control, however, data on cardiac-specific sympathetic activation in aged women and men are lacking. Methods and results Regional quantitative analysis of cardiac fluorine-18 (18F)- Dihydroxyphenylalanine (DOPA) uptake was retrospectively performed in 133 patients (69 females, mean age 52.4±17.7 years) referred for assessment of neuroendocrine tumours (NET) by Positron-Emission-Tomography. Cardiac 18F-DOPA uptake was significantly higher in women as compared to men (1.33±0.21 vs. 1.18±0.24, p<0.001). This sex-difference was most pronounced in the apical region of the left ventricle (LV, 1.30±0.24 in women vs. 1.13±0.25 in men, p<0.001) and in individuals >55 years of age (1.39±0.25 in women vs. 1.09±0.24 in men, p<0.001). Women showed a prominent increase in myocardial 18F-DOPA uptake with age with the strongest increase seen in the LV apical region (r = 0.34, p = 0.004). Accordingly, sex and age were selected as significant predictors of LV apical 18F-DOPA uptake in a stepwise linear regression model. No age-dependent changes of cardiac 18F-DOPA uptake were observed in men or in the right ventricular region. Conclusion Our study suggests that aging is related to sex-specific changes in regional cardiac sympathetic activity. Future studies will have to assess whether the increase in LV apical 18F-DOPA uptake with age in women is of pathogenic relevance for the higher susceptibility of postmenopausal women to conditions associated with increased sympathetic activity.

Tu1985 Loss of Integrin β6 (ITGB6) Protects From Colon Cancer Development In Vivo

Background: Colorectal carcinoma (CRC) represents the 3rd most frequent malignancy in industrialised countries and the 2nd most common cause of cancer-related deaths. Nearly each 4th of CRC patients develop metastatic disease that can only hardly be treated. A central process in CRC progression and metastasis is epithelial-mesenchymal-transition (EMT), which is partially mediated by certain integrins. An important molecule contributing to EMT in epithelial cells is integrin β6 (ITGB6), which has been associated with proliferation and invasion of colon cancer cells. We have recently shown that ITGB6 can be detected in the serum of CRC patients. ITGB6 serum levels above the threshold of 2/ml are associated with 100% metastatic disease and correlate with poor survival. Here, we investigated the relevance of ITGB6 in the development of colon cancer in mouse models in vivo. Methods: We performed the azoxymethane (AOM)/dextran sodium sulphate (DSS) colon cancer model in female weight-matched ITGB6-/and C57BL/6J wild-type (WT) littermates. ITGB6-/and WT mice were randomly assigned to either a saline/water group (n=6-9) or an AOM/DSS group (n=11-14). Mice were treated 3 cycles, each for 7 day with 1% DSS followed by 14 days recovery period with drinking water. At the 1st day of each DSS cycle and the 2nd day of each water cycle, mice were treated interperitoneally with AOM (10 /kg body weight). Control animals were treated with saline at the same time points. All mice were weighed and monitored throughout the experiment and killed 15 weeks after the treatment start. Results: AOM/DSS-treated ITGB6-/mice (n=14) suffered from aggravated DSS-induced colitis, when compared to AOM/DSS-treated WT mice (n=10). Clinical signs of colitis such as enhanced weight loss (p<.01), increased number of mice with rectal bleeding and severe diarrhoea were clearly more observed in ITGB6-/mice during DSS-treatment. Interestingly, by mouse endoscopy, we detected no colon tumours at all in AOM/DSS-treated ITGB6-/mice, whereas AOM/DSS-treated WT mice displayed up to 4 tumours per animal (p<.001). These findings could be fully confirmed by histologic analysis of the mouse colon. Colon tumours of WT mice featured also an invasive pattern infiltrating into the lamina muscularis mucosae of the intestinal epithelium. DSS/AOM-treated WT mice only revealed hyper proliferative epithelium, but no signs of malignancy in the histopathologic assessment. Conclusions: In summary, we demonstrate that ITGB6-/completely protects mice from AOM/ DSS-induced colon tumour formation. In contrast, WT mice receiving AOM/DSS regularly developed colon tumours. Furthermore, we also found an aggravation of colitis symptoms in ITGB6-/mice, whereas WT mice showed only mild colitis symptoms. Taken together our results suggest that ITGB6 might play a crucial role for colon cancer development.