Dissecting the effect of ileal faecal diversion on the intestine using single-cell sequencing.

BACKGROUND: Although ileal faecal diversion is commonly used in clinical settings, complications accompany it. Elucidating the intestinal changes caused by ileal faecal diversion will help resolve postoperative complications and elucidate the pathogenic mechanisms of associated intestinal disorders, such as Crohn's disease (CD). Therefore, our study aimed to provide new insights into the effects of ileal faecal diversion on the intestine and the potential mechanisms. METHODS: Single-cell RNA sequencing was performed on proximal functional and paired distal defunctioned intestinal mucosae from three patients with ileal faecal diversion. We also performed in vitro cellular and animal experiments, tissue staining and analysed public datasets to validate our findings. RESULTS: We found that the epithelium in the defunctioned intestine tended to be immature, with defective mechanical and mucous barriers. However, the innate immune barrier in the defunctioned intestine was enhanced. Focusing on the changes in goblet cells, we demonstrated that mechanical stimulation promotes the differentiation and maturation of goblet cells through the TRPA1-ERK pathway, indicating that the absence of mechanical stimulation may be the main cause of defects in the goblet cells of the defunctioned intestine. Furthermore, we found obvious fibrosis with a pro-fibrotic microenvironment in the defunctioned intestine and identified that monocytes may be important targets for faecal diversion to alleviate CD. CONCLUSIONS: This study revealed the different transcription landscapes of various cell subsets and the potential underlying mechanisms within the defunctioned intestine, when compared to the functional intestine, based on the background of ileal faecal diversion. These findings provide novel insights for understanding the physiological and pathological roles of the faecal stream in the intestine.

Structure Composition and Intracellular Transport of Clathrin-Mediated Intestinal Transmembrane Tight Junction Protein.

Tight junctions (TJs) are located in the apical region of the junctions between epithelial cells and are widely found in organs such as the brain, retina, intestinal epithelium, and endothelial system. As a mechanical barrier of the intestinal mucosa, TJs can not only maintain the integrity of intestinal epithelial cells but also maintain intestinal mucosal permeability by regulating the entry of ions and molecules into paracellular channels. Therefore, the formation disorder or integrity destruction of TJs can induce damage to the intestinal epithelial barrier, ultimately leading to the occurrence of various gastrointestinal diseases, such as inflammatory bowel disease (IBD), gastroesophageal reflux disease (GERD), and irritable bowel syndrome (IBS). However, a large number of studies have shown that TJs protein transport disorder from the endoplasmic reticulum to the apical membrane can lead to TJs formation disorder, in addition to disruption of TJs integrity caused by external pathological factors and reduction of TJs protein synthesis. In this review, we focus on the structural composition of TJs, the formation of clathrin-coated vesicles containing transmembrane TJs from the Golgi apparatus, and the transport process from the Golgi apparatus to the plasma membrane via microtubules and finally fusion with the plasma membrane. At present, the mechanism of the intracellular transport of TJ proteins remains unclear. More studies are needed in the future to focus on the sorting of TJs protein vesicles, regulation of transport processes, and recycling of TJ proteins, etc.

Polycatechol-Derived Mesoporous Polydopamine Nanoparticles for Combined ROS Scavenging and Gene Interference Therapy in Inflammatory Bowel Disease.

Benefiting from the evolution of nanotechnology, the combination therapy by gene interference and reactive oxygen species (ROS) scavenging are expected, which holds great potential in inflammatory bowel disease (IBD) therapy. However, the functional integration of different therapeutic modules through interface modification of gene vectors for safe and efficient treatment is urgently needed. Herein, we present a catechol chemistry-mediated core-shell nanoplatform for ROS scavenging-mediated oxidative stress alleviation and siRNA-mediated gene interference in a dextran sulfate sodium (DSS)-induced colitis model. The nanoplatform is constructed by employing mesoporous polydopamine nanoparticles (MPDA NPs) with surface modification of amines as the porous core for TNF-α-siRNA loading (31 wt %) and exerts an antioxidant function, while PDA-induced biomineralization of the calcium phosphate (CaP) coating is used as the pH-sensitive protective shell to prevent siRNA from premature release. The CaP layer degraded under weakly acidic subcellular conditions (lysosomes); thus, the synergistic integration of catechol and cation moieties on the exposed surface of MPDA resulted in an efficient lysosomal escape. Subsequently, effective ROS scavenging caused by the electron-donating ability of MPDA and efficient knocking down (40.5%) of tumor necrosis factor-α (TNF-α) via sufficient cytosolic gene delivery resulted in a synergistic anti-inflammation therapeutic effect both in vitro and in vivo. This work establishes the first paradigm of synergistic therapy in IBD by ROS scavenging and gene interference.