Ketogenic Diet Protects from Experimental Colitis in a Mouse Model Regardless of Dietary Fat Source

While ketogenic diets (KDs) may have potential as adjunct treatments for gastrointestinal diseases, there is little knowledge on how the fat source of these diets impacts intestinal health. The objective of this study was to investigate how the source of dietary fat of KD influences experimental colitis. We fed nine-week-old male C57BL/6J mice (n = 36) with a low-fat control diet or KD high either in saturated fatty acids (SFA-KD) or polyunsaturated linoleic acid (LA-KD) for four weeks and then induced colitis with dextran sodium sulfate (DSS). To compare the diets, we analyzed macroscopic and histological changes in the colon, intestinal permeability to fluorescein isothiocyanate-dextran (FITC-dextran), and the colonic expression of tight junction proteins and inflammatory markers. While the effects were more pronounced with LA-KD, both KDs markedly alleviated DSS-induced histological lesions. LA-KD prevented inflammation-related weight loss and the shortening of the colon, as well as preserved Il1b and Tnf expression at a healthy level. Despite no significant between-group differences in permeability to FITC-dextran, LA-KD mitigated changes in tight junction protein expression. Thus, KDs may have preventive potential against intestinal inflammation, with the level of the effect being dependent on the dietary fat source.

Ketogenic Diet High in Saturated Fat Promotes Colonic Claudin Expression without Changes in Intestinal Permeability to Iohexol in Healthy Mice

Ketogenic diets (KDs) have been studied in preclinical models of intestinal diseases. However, little is known of how the fat source of these diets influences the intestinal barrier. Herein, we studied the impact of four-week feeding with KD high either in saturated fatty acids (SFA-KD) or polyunsaturated linoleic acid (LA-KD) on paracellular permeability of the intestine to iohexol in healthy male C57BL/6J mice. We investigated jejunal and colonic tight junction protein expression, histological changes, and inflammatory markers (Il1b, Il6, Tnf, and Lcn2), as well as the activity and expression of intestinal alkaline phosphatase (IAP) in feces and jejunal tissue, respectively, and plasma lipopolysaccharide. KDs did not change intestinal permeability to iohexol after two or twenty-six days of feeding regardless of fat quality. SFA-KD, but not LA-KD, upregulated the colonic expression of tight junction proteins claudin-1 and -4, as well as the activity of IAP. Both KDs resulted in increased epithelial vacuolation in jejunum, and this was pronounced in SFA-KD. Jejunal Il1β expression was lower and colonic Il6 expression higher in LA-KD compared to SFA-KD. In colon, Tnf mRNA was increased in LA-KD when compared to controls. Overall, the results suggest that KDs do not influence intestinal permeability to iohexol but elicit changes in colonic tight junction proteins and inflammatory markers in both jejunum and colon. Future research will show whether these changes become of importance upon proinflammatory insults.

The Clip Approach: A Visual Methodology to Support the (Re)Construction of Life Narratives

Major life changes may cause an autobiographical rupture and a need to work on one's narrative identity. This article introduces a new qualitative interview methodology originally developed to facilitate 10 prostate cancer patients and five spouses in the (re)creation of their life narratives in the context of a series of interventive interviews conducted over a timespan of several months. In "The Clip Approach" the interviewees' words, phrases, and metaphors are reflected back in a physical form ("the Clips") as visual artifacts that allow the interviewees to re-enter and re-consider their experience and life and re-construct their narratives concerning them. Honoring the interviewees as authors facilitates autobiographical reasoning, building a bridge between the past and the future, and embedding the illness experience as part of one's life narrative. The Clip Approach provides new tools for both research and practice-potentially even a low-threshold psychosocial support method for various applicability areas.

Chromatin accessibility is associated with CRISPR-Cas9 efficiency in the zebrafish (Danio rerio)

CRISPR-Cas9 technology is routinely applied for targeted mutagenesis in model organisms and cell lines. Recent studies indicate that the prokaryotic CRISPR-Cas9 system is affected by eukaryotic chromatin structures. Here, we show that the likelihood of successful mutagenesis correlates with transcript levels during early development in zebrafish (Danio rerio) embryos. In an experimental setting, we found that guide RNAs differ in their onset of mutagenesis activity in vivo. Furthermore, some guide RNAs with high in vitro activity possessed poor mutagenesis activity in vivo, suggesting the presence of factors that limit the mutagenesis in vivo. Using open access datasets generated from early developmental stages of the zebrafish, and guide RNAs selected from the CRISPRz database, we provide further evidence for an association between gene expression during early development and the success of CRISPR-Cas9 mutagenesis in zebrafish embryos. In order to further inspect the effect of chromatin on CRISPR-Cas9 mutagenesis, we analysed the relationship of selected chromatin features on CRISPR-Cas9 mutagenesis efficiency using publicly available data from zebrafish embryos. We found a correlation between chromatin openness and the efficiency of CRISPR-Cas9 mutagenesis. These results indicate that CRISPR-Cas9 mutagenesis is influenced by chromatin accessibility in zebrafish embryos.