A Colonic Organoid Model Challenged with the Large Toxins of Clostridioides difficile TcdA and TcdB Exhibit Deregulated Tight Junction Proteins.

BACKGROUND: Clostridioides difficile toxins TcdA and TcdB are responsible for diarrhea and colitis. Lack of functional studies in organoid models of the gut prompted us to elucidate the toxin's effects on epithelial barrier function and the molecular mechanisms for diarrhea and inflammation. METHODS: Human adult colon organoids were cultured on membrane inserts. Tight junction (TJ) proteins and actin cytoskeleton were analyzed for expression via Western blotting and via confocal laser-scanning microscopy for subcellular localization. RESULTS: Polarized intestinal organoid monolayers were established from stem cell-containing colon organoids to apply toxins from the apical side and to perform functional measurements in the organoid model. The toxins caused a reduction in transepithelial electrical resistance in human colonic organoid monolayers with sublethal concentrations. Concomitantly, we detected increased paracellular permeability fluorescein and FITC-dextran-4000. Human colonic organoid monolayers exposed to the toxins exhibited redistribution of barrier-forming TJ proteins claudin-1, -4 and tricellulin, whereas channel-forming claudin-2 expression was increased. Perijunctional F-actin cytoskeleton organization was affected. CONCLUSIONS: Adult stem cell-derived human colonic organoid monolayers were applicable as a colon infection model for electrophysiological measurements. The TJ changes noted can explain the epithelial barrier dysfunction and diarrhea in patients, as well as increased entry of luminal antigens triggering inflammation.

CDT of Clostridioides difficile Induces MLC-Dependent Intestinal Barrier Dysfunction in HT-29/B6 Epithelial Cell Monolayers.

Background: Clostridioides difficile binary toxin (CDT) defines the hypervirulence of strains in nosocomial antibiotic-induced colitis with the highest mortality. The objective of our study was to investigate the impact of CDT on the intestinal epithelial barrier and to enlighten the underlying molecular mechanisms. Methods: Functional measurements of epithelial barrier function by macromolecular permeability and electrophysiology were performed in human intestinal HT-29/B6 cell monolayers. Molecular analysis of the spatial distribution of tight junction protein and cytoskeleton was performed by super-resolution STED microscopy. Results: Sublethal concentrations of CDT-induced barrier dysfunction with decreased TER and increased permeability for 332 Da fluorescein and 4 kDa FITC-dextran. The molecular correlate to the functional barrier defect by CDT was found to be a tight junction protein subcellular redistribution with tricellulin, occludin, and claudin-4 off the tight junction domain. This redistribution was shown to be MLCK-dependent. Conclusions: CDT compromised epithelial barrier function in a human intestinal colonic cell model, even in sublethal concentrations, pointing to barrier dysfunction in the intestine and leak flux induction as a diarrheal mechanism. However, this cannot be attributed to the appearance of apoptosis and necrosis, but rather to an opening of the paracellular leak pathway as the result of epithelial tight junction alterations.

Prophylactic Salpingectomy during Hysterectomy for Benign Disease: A Prospective Study to Evaluate High-Grade Serous Ovarian Carcinoma Precursors.

Recent findings suggest that high-grade serous ovarian cancer can originate in the fallopian tube. Not only has that made the identification of precursor lesions pivotal in early detection and prevention of these cancers, prophylactic salpingectomy alongside hysterectomy for benign indications has been increasingly proposed as well. The present prospective single-center study included 273 women who underwent opportunistic salpingectomy alongside laparoscopic supracervical hysterectomy. Uterine and tubal histopathological results as well as intra- and postoperative complications were evaluated. The complication rate was 3.3%, of which none were caused by salpingectomy. Uterine histopathology diagnosed 181 patients (66.8%) with uterine myomas, 60 patients (22.1%) with adenomyosis, 29 patients (10.7%) with adenomyomatosis, and, 1 patient (0.4%) without pathological abnormality. p53 signatures were detected in 221 right fallopian tubes (80.9%) and in 229 left tubes (83.9%). In total, 8 patients showed bilateral STIL (2.9%), whereas in 1 patient (0.4%) STIL was detected in the left tube only. No STIC were detected. Laparoscopic opportunistic salpingectomy is demonstrated to be both safe and feasible. It appears to be promising to reduce the risk for ovarian cancer, yet more studies are needed to undoubtedly confirm this.