Molecular regulation mechanism of intestinal stem cells in mucosal injury and repair in ulcerative colitis

Thymoquinone Ameliorates Gut Epithelial Injury by Suppressing the JNK Signaling Pathway Based on Its Anti-Oxidant Property

Ulcerative colitis is one of the most common sorts of inflammatory bowel disease. This study investigates the protective effects of thymoquinone against sodium dodecyl sulfate (SDS)-induced intestinal damage and elucidates the underlying mechanisms using the Drosophila melanogaster model of ulcerative colitis. We found that Drosophila fed thymoquinone from larval to adult stages were resistant to SDS injury in adulthood. Thymoquinone pretreatment significantly restored the abnormal behaviors and intestinal morphological defects in Drosophila exposed to SDS. Moreover, thymoquinone protected the intestinal barrier function by inhibiting the overactivated c-Jun N-terminal kinase (JNK) pathway in the intestine induced by SDS. Further studies indicated that thymoquinone inhibits the JNK pathway by reducing intestinal reactive oxygen species (ROS) levels. This research provides novel pathological and mechanistic insights into the potential application of thymoquinone in developing functional foods or natural medicines, highlighting its significance in treating ulcerative colitis.

Caffeic Acid Protects Against Ulcerative Colitis via Inhibiting Mitochondrial Apoptosis and Immune Overactivation in Drosophila

Background

Ulcerative colitis (UC) is a chronic intestinal inflammation that is prone to relapse and is difficult to fully recover; therefore, there is a need for safer alternative treatments. Caffeic acid (CA) is a natural polyphenolic compound that has antioxidant and anti-inflammatory properties. However, the beneficial effects and mechanisms of action of CA in UC remain unclear.

Purpose

This study evaluated the protective effect of CA against dextran sulfate sodium (DSS)-induced intestinal injury in Drosophila melanogaster model.

Results

Oral administration of CA significantly reduced body damage in UC flies, improved their survival rate, restored damaged digestion, and improved locomotion. CA supplementation significantly alleviated intestinal damage in UC flies by restoring excretion balance, repairing intestinal atrophy, improving acid-base balance imbalance, inhibiting intestinal structural destruction, inhibiting intestinal epithelial cell death and intestinal stem cell (ISC) excessive proliferation, and reducing the number of harmful bacteria. Mechanistic studies found that CA significantly reduced the expression of Toll and Imd pathway genes (including Myd88, Dif, PGRP-LC, Imd, Rel, and Dpt), reduced ROS levels and the expression of apoptosis-related genes (Debcl, Cyt-c-p, DrlCE, Dronc, and Dark), and increased ATP and MFN2 levels.

Conclusion

CA alleviated intestinal damage mainly by inhibiting the Toll and Imd signaling pathways and inhibiting apoptosis mediated by mitochondrial damage. These findings suggest that CA holds promise as a potential therapeutic for UC treatment.

The Intestinal Macrophage-Intestinal Stem Cell Axis in Inflammatory Bowel Diseases: From Pathogenesis to Therapy

The gut plays a crucial role in digestion and immunity, so its balance is essential to overall health. This balance relies on dynamic interactions between intestinal epithelial cells, immune cells, and crypt stem cells. Inflammatory bowel disease (IBD), which consists of ulcerative colitis and Crohn's disease, is a chronic relapsing inflammatory disease of the gastrointestinal tract closely related to immune dysfunction. Stem cells, known for their ability to self-renew and differentiate, play an important role in repairing damaged intestinal epithelium and maintaining homeostasis in vivo. Macrophages are key gatekeepers of intestinal immune homeostasis and have a significant impact on IBD. Current research has focused on the link between epithelial cells and stem cells, but interactions with macrophages, which have been recognized as attractive targets for the development of new therapeutic approaches to disease, have been less explored. Recently, the developing field of immunometabolism has reinforced that metabolic reprogramming is a key determinant of macrophage function and subsequent disease progression. The aim of this review is to explore the role of the macrophage-stem cell axis in the maintenance of intestinal homeostasis and to summarize potential approaches to treating IBD by manipulating the cellular metabolism of macrophages, as well as the main opportunities and challenges faced. In summary, our overview provides a framework for understanding the critical role of macrophage immunometabolism in maintaining gut health and potential therapeutic targets.

LGR5: An emerging therapeutic target for cancer metastasis and chemotherapy resistance

Cancer stem cells play an important role in tumor progression and chemotherapy resistance. Leucine-rich G repeat-containing protein-coupled receptor 5 (LGR5) has been identified as a cancer stem cell marker in several cancer types. LGR5 is involved in cancer development and progression via several pathways including WNT/β-catenin signaling pathway. LGR5 plays a role in tumor progression by promoting cancer cell migration, invasion, metastasis, and angiogenesis in many cancers including colorectal, brain, gastric, and ovarian cancer. This review summarises the current knowledge on the expression and functional role of LGR5 in cancers, the molecular mechanisms regulated by LGR5, and the relationship between LGR5 and chemotherapy resistance. The review also includes highlights potential strategies to inhibit LGR5 expression and function. The majority of functional studies have shown that LGR5 plays an important role in promoting cancer progression, metastasis and chemotherapy resistance however, in some contexts LGR5 can also activate tumor-suppressive pathways and LGR5 negative cells can also promote cancer progression. The review highlights that targeting LGR5 is a promising anti-cancer treatment but the functional effect of LGR5 on tumor cells is complex may be dependent on cancer type, tumor microenvironment and cross-talk with other molecules in the LGR5 signaling pathway.

Critical Knowledge Gaps and Future Priorities Regarding the Intestinal Barrier Damage After Traumatic Brain Injury

The analysis aims to provide a comprehensive understanding of the current landscape of research on the Intestinal barrier damage after traumatic brain injury (TBI), elucidate specific mechanisms, and address knowledge gaps to help guide the development of targeted therapeutic interventions and improve outcomes for individuals with TBI. A total of 2756 relevant publications by 13,778 authors affiliated within 3198 institutions in 79 countries were retrieved from the Web of Science. These publications have been indexed by 1139 journals and cited 158, 525 references. The most productive author in this field was Sikiric P, and the University of Pittsburgh was identified as the most influential institution. The United States was found to be the leading country in terms of article output and held a dominant position in this field. The International Journal of Molecular Sciences was identified as a major source of publications in this area. In terms of collaboration, the cooperation between the United States and China was found to be the most extensive among countries, institutions, and authors, indicating a high level of influence in this field. Keyword co-occurrence network analysis revealed several hotspots in this field, including the microbiome-gut-brain axis, endoplasmic reticulum stress, cellular autophagy, ischemia-reperfusion, tight junctions, and intestinal permeability. The analysis of keyword citation bursts suggested that ecological imbalance and gut microbiota may be the forefront of future research. The findings of this study can serve as a reference and guiding perspective for future research in this field.

The intestinal epithelial-macrophage-crypt stem cell axis plays a crucial role in regulating and maintaining intestinal homeostasis

The intestinal tract plays a vital role in both digestion and immunity, making its equilibrium crucial for overall health. This equilibrium relies on the dynamic interplay among intestinal epithelial cells, macrophages, and crypt stem cells. Intestinal epithelial cells play a pivotal role in protecting and regulating the gut. They form vital barriers, modulate immune responses, and engage in pathogen defense and cytokine secretion. Moreover, they supervise the regulation of intestinal stem cells. Macrophages, serving as immune cells, actively influence the immune response through the phagocytosis of pathogens and the release of cytokines. They also contribute to regulating intestinal stem cells. Stem cells, known for their self-renewal and differentiation abilities, play a vital role in repairing damaged intestinal epithelium and maintaining homeostasis. Although research has primarily concentrated on the connections between epithelial and stem cells, interactions with macrophages have been less explored. This review aims to fill this gap by exploring the roles of the intestinal epithelial-macrophage-crypt stem cell axis in maintaining intestinal balance. It seeks to unravel the intricate dynamics and regulatory mechanisms among these essential players. A comprehensive understanding of these cell types' functions and interactions promises insights into intestinal homeostasis regulation. Moreover, it holds potential for innovative approaches to manage conditions like radiation-induced intestinal injury, inflammatory bowel disease, and related diseases.

Claudin-7 is essential for the maintenance of colonic stem cell homoeostasis via the modulation of Wnt/Notch signalling

Intestinal stem cells (ISCs) play a crucial role in the continuous self-renewal and recovery of the intestinal epithelium. In previous studies, we have revealed that the specific absence of Claudin-7 (Cldn-7) in intestinal epithelial cells (IECs) can lead to the development of spontaneous colitis. However, the mechanisms by which Cldn-7 maintains homeostasis in the colonic epithelium remain unclear. Therefore, in the present study, we used IEC- and ISC-specific Cldn-7 knockout mice to investigate the regulatory effects of Cldn-7 on colonic Lgr5+ stem cells in the mediation of colonic epithelial injury and repair under physiological and inflammatory conditions. Notably, our findings reveal that Cldn-7 deletion disrupts the self-renewal and differentiation of colonic stem cells alongside the formation of colonic organoids in vitro. Additionally, these Cldn-7 knockout models exhibited heightened susceptibility to experimental colitis, limited epithelial repair and regeneration, and increased differentiation toward the secretory lineage. Mechanistically, we also established that Cldn-7 facilitates the proliferation, differentiation, and organoid formation of Lgr5+ stem cells through the maintenance of Wnt and Notch signalling pathways in the colonic epithelium. Overall, our study provides new insights into the maintenance of ISC function and colonic epithelial homoeostasis.

Advancements in hydrogel-based drug delivery systems for the treatment of inflammatory bowel disease: a review

Inflammatory bowel disease (IBD) is a chronic disorder that affects millions of individuals worldwide. However, current drug therapies for IBD are plagued by significant side effects, low efficacy, and poor patient compliance. Consequently, there is an urgent need for novel therapeutic approaches to alleviate IBD. Hydrogels, three-dimensional networks of hydrophilic polymers with the ability to swell and retain water, have emerged as promising materials for drug delivery in the treatment of IBD due to their biocompatibility, tunability, and responsiveness to various stimuli. In this review, we summarize recent advancements in hydrogel-based drug delivery systems for the treatment of IBD. We first identify three pathophysiological alterations that need to be addressed in the current treatment of IBD: damage to the intestinal mucosal barrier, dysbiosis of intestinal flora, and activation of inflammatory signaling pathways leading to disequilibrium within the intestines. Subsequently, we discuss in depth the processes required to prepare hydrogel drug delivery systems, from the selection of hydrogel materials, types of drugs to be loaded, methods of drug loading and drug release mechanisms to key points in the preparation of hydrogel drug delivery systems. Additionally, we highlight the progress and impact of the hydrogel-based drug delivery system in IBD treatment through regulation of physical barrier immune responses, promotion of mucosal repair, and improvement of gut microbiota. In conclusion, we analyze the challenges of hydrogel-based drug delivery systems in clinical applications for IBD treatment, and propose potential solutions from our perspective.