Gut-associated cGMP mediates colitis and dysbiosis in a mouse model of an activating mutation in GUCY2C

cDNA Display Selection of Interacting Peptide Ligands of the Guanylate Cyclase C Receptor

Guanylate cyclase C (GC-C), a receptor expressed on the apical membrane of intestinal mucosal cells, is activated by heat-stable enterotoxin (STa) produced by enterotoxigenic Escherichia coli, as well as the endogenous ligands guanylin and uroguanylin. In this study, novel peptides that interact with GC-C were generated using the cDNA display method, and their binding affinity and biological activity were evaluated. While the linear peptide library did not yield peptides with sufficient affinity for GC-C, three cyclic peptides (GCC-P1, GCC-P2, and GCC-P3), each containing two cysteine residues within a 15-residue sequence, were obtained from a cyclic peptide library containing nine-residue random sequences. GC-P2 exhibited significant binding affinity in Biacore assays, although the affinity was lower than those reported for known ligands. Notably, GCC-P2 and GCC-P3 demonstrated enhanced cGMP activity when used in combination with linaclotide. However, the agonist activity of these peptides was minimal, indicating that further modifications may be necessary to develop them for clinical applications. This study successfully extracted consensus sequences of peptide motifs that bind to GC-C from a highly diverse nine-residue random sequence library, which provides fundamental insights for the discovery and optimization of novel GC-C ligands.

Gut Dysbiosis Drives Inflammatory Bowel Disease Through the CCL4L2-VSIR Axis in Glycogen Storage Disease

Patients with glycogen storage disease type Ib (GSD-Ib) frequently have inflammatory bowel disease (IBD). however, the underlying etiology remains unclear. Herein, this study finds that digestive symptoms are commonly observed in patients with GSD-Ib, presenting as single or multiple scattered deep round ulcers, inflammatory pseudo-polyps, obstructions, and strictures, which differ substantially from those in typical IBD. Distinct microbiota profiling and single-cell clustering of colonic mucosae in patients with GSD are conducted. Heterogeneous oral pathogenic enteric outgrowth induced by GSD is a potent inducer of gut microbiota immaturity and colonic macrophage accumulation. Specifically, a unique population of macrophages with high CCL4L2 expression is identified in response to pathogenic bacteria in the intestine. Hyper-activation of the CCL4L2-VSIR axis leads to increased expression of AGR2 and ZG16 in epithelial cells, which mediates the unique progression of IBD in GSD-Ib. Collectively, the microbiota-driven pathomechanism of IBD is demonstrated in GSD-Ib and revealed the active role of the CCL4L2-VSIR axis in the interaction between the microbiota and colonic mucosal immunity. Thus, targeting gut dysbiosis and/or the CCL4L2-VISR axis may represent a potential therapy for GSD-associated IBD.

Updated Clinical Perspectives and Challenges of Chimeric Antigen Receptor-T Cell Therapy in Colorectal Cancer and Invasive Breast Cancer

In recent years, the incidence of colorectal cancer (CRC) and breast cancer (BC) has increased worldwide and caused a higher mortality rate due to the lack of selective anti-tumor therapies. Current chemotherapies and surgical interventions are significantly preferred modalities to treat CRC or BC in advanced stages but the prognosis for patients with advanced CRC and BC remains dismal. The immunotherapy technique of chimeric antigen receptor (CAR)-T cells has resulted in significant clinical outcomes when treating hematologic malignancies. The novel CAR-T therapy target antigens include GUCY2C, CLEC14A, CD26, TEM8/ANTXR1, PDPN, PTK7, PODXL, CD44, CD19, CD20, CD22, BCMA, GD2, Mesothelin, TAG-72, CEA, EGFR, B7H3, HER2, IL13Ra2, MUC1, EpCAM, PSMA, PSCA, NKG2D. The significant aim of this review is to explore the recently updated information pertinent to several novel targets of CAR-T for CRC, and BC. We vividly described the challenges of CAR-T therapies when treating CRC or BC. The immunosuppressive microenvironment of solid tumors, the shortage of tumor-specific antigens, and post-treatment side effects are the major hindrances to promoting the development of CAR-T cells. Several clinical trials related to CAR-T immunotherapy against CRC or BC have already been in progress. This review benefits academicians, clinicians, and clinical oncologists to explore more about the novel CAR-T targets and overcome the challenges during this therapy.

The metabolic impact of bacterial infection in the gut

Bacterial infections of the gut are one of the major causes of morbidity and mortality worldwide. The interplay between the pathogen and the host is finely balanced, with the bacteria evolving to proliferate and establish infection. In contrast, the host mounts a response to first restrict and then eliminate the infection. The intestine is a rapidly proliferating tissue, and metabolism is tuned to cater to the demands of proliferation and differentiation along the crypt-villus axis (CVA) in the gut. As bacterial pathogens encounter the intestinal epithelium, they elicit changes in the host cell, and core metabolic pathways such as the tricarboxylic acid (TCA) cycle, lipid metabolism and glycolysis are affected. This review highlights the mechanisms utilized by diverse gut bacterial pathogens to subvert host metabolism and describes host responses to the infection.

Investigating the Crime Scene-Molecular Signatures in Inflammatory Bowel Disease

Inflammatory bowel diseases (IBD) are without cure and troublesome to manage because of the considerable diversity between patients and the lack of reliable biomarkers. Several studies have demonstrated that diet, gut microbiota, genetics and other patient factors are essential for disease occurrence and progression. Understanding the link between these factors is crucial for identifying molecular signatures that identify biomarkers to advance the management of IBD. Recent technological breakthroughs and data integration have fuelled the intensity of this research. This research demonstrates that the effect of diet depends on patient factors and gut microbial activity. It also identifies a range of potential biomarkers for IBD management, including mucosa-derived cytokines, gasdermins and neutrophil extracellular traps, all of which need further evaluation before clinical translation. This review provides an update on cutting-edge research in IBD that aims to improve disease management and patient quality of life.

A novel frameshift mutation in TRPV6 is associated with hereditary pancreatitis

Introduction: Hereditary pancreatitis (HP) is a rare debilitating disease with incompletely understood etio-pathophysiology. The reduced penetrance of genes such as PRSS1 associated with hereditary pancreatitis indicates a role for novel inherited factors. Methods: We performed whole-exome sequencing of three affected members of an Indian family (Father, Son, and Daughter) with chronic pancreatitis and compared variants with those seen in the unaffected mother. Results: We identified a novel frameshift mutation in exon 11 of TRPV6 (c.1474_1475delGT; p.V492Tfs*136), a calcium channel, in the patients. Functional characterization of this mutant TRPV6 following heterologous expression revealed that it was defective in calcium uptake. Induction of pancreatitis in mice induced Trpv6 expression, indicating that higher expression levels of the mutant protein and consequent dysregulation of calcium levels in patients with chronic pancreatitis could aggravate the disease. Discussion: We report a novel frameshift mutation in TRPV6 in an Indian family with HP that renders the mutant protein inactive. Our results emphasize the need to expand the list of genes used currently for evaluating patients with hereditary pancreatitis.

New insights into bacterial mechanisms and potential intestinal epithelial cell therapeutic targets of inflammatory bowel disease

The global incidence of inflammatory bowel disease (IBD) has increased rapidly in recent years, but its exact etiology remains unclear. In the past decade, IBD has been reported to be associated with dysbiosis of gut microbiota. Although not yet proven to be a cause or consequence of IBD, the common hypothesis is that at least some alterations in the microbiome are protective or pathogenic. Furthermore, intestinal epithelial cells (IECs) serve as a protective physical barrier for gut microbiota, essential for maintaining intestinal homeostasis and actively contributes to the mucosal immune system. Thus, dysregulation within the intestinal epithelium increases intestinal permeability, promotes the entry of bacteria, toxins, and macromolecules, and disrupts intestinal immune homeostasis, all of which are associated with the clinical course of IBD. This article presents a selective overview of recent studies on bacterial mechanisms that may be protective or promotive of IBD in biological models. Moreover, we summarize and discuss the recent discovery of key modulators and signaling pathways in the IECs that could serve as potential IBD therapeutic targets. Understanding the role of the IECs in the pathogenesis of IBD may help improve the understanding of the inflammatory process and the identification of potential therapeutic targets to help ameliorate this increasingly common disease.

Inactivation of the MSTN gene expression changes the composition and function of the gut microbiome in sheep

Background

Myostatin (MSTN) negatively regulates the muscle growth in animals and MSTN deficient sheep have been widely reported previously. The goal of this study was to explore how MSTN inactivation influences their gut microbiota composition and potential functions.

Results

We compared the slaughter parameters and meat quality of 3 MSTN-edited male sheep and 3 wild-type male sheep, and analyzed the gut microbiome of the MSTN-edited sheep (8 female and 8 male sheep) and wild-type sheep (8 female and 8 male sheep) through metagenomic sequencing. The results showed that the body weight, carcass weight and eye muscle area of MSTN-edited sheep were significantly higher, but there were no significant differences in the meat quality indexes. At the microbial level, the alpha diversity was significantly higher in the MSTN-edited sheep (P < 0.05), and the microbial composition was significantly different by PCoA analysis in the MSTN-edited and wild-type sheep. The abundance of Firmicutes significantly increased and Bacteroidota significantly decreased in the MSTN-edited sheep. At genus level, the abundance of Flavonifractor, Subdoligranulum, Ruthenibacterium, Agathobaculum, Anaerotignum, Oribacterium and Lactobacillus were significantly increased in the MSTN-edited sheep (P < 0.05). Further analysis of functional differences was found that the carotenoid biosynthesis was significantly increased and the peroxisome, apoptosis, ferroptosis, N-glycan biosynthesis, thermogenesis, and adipocytokines pathways were decreased in the MSTN-edited sheep (P < 0.05). Moreover, carbohydrate-active enzymes (CAZymes) results certified the abundance of the GH13_39, GH4, GH137, GH71 and PL17 were upregulated, and the GT41 and CBM20 were downregulated in the MSTN-edited sheep (P < 0.05).

Conclusions

Our study suggested that MSTN inactivation remarkably influenced the composition and potential function of hindgut microbial communities of the sheep, and significantly promoted growth performance without affecting meat quality.

Guanylyl cyclase C as a diagnostic and therapeutic target in colorectal cancer

Colorectal cancer remains a major cause of mortality in the USA, despite advances in prevention and screening. Existing therapies focus primarily on generic treatment such as surgical intervention and chemotherapy, depending on disease severity. As personalized medicine and targeted molecular oncology continue to develop as promising treatment avenues, there has emerged a need for effective targets and biomarkers of colorectal cancer. The transmembrane receptor guanylyl cyclase C (GUCY2C) regulates intestinal homeostasis and has emerged as a tumor suppressor. Further, it is universally expressed in advanced metastatic colorectal tumors, as well as other cancer types that arise through intestinal metaplasia. In this context, GUCY2C satisfies many characteristics of a compelling target and biomarker for gastrointestinal malignancies.

Diet-Induced Host-Microbe Interactions: Personalized Diet Strategies for Improving Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is an idiopathic inflammatory disease. Environmental sanitization, modern lifestyles, advanced medicines, ethnic origins, host genetics and immune systems, mucosal barrier function, and the gut microbiota have been delineated to explain how they cause mucosal inflammation. However, the pathogenesis of IBD and its therapeutic targets remain elusive. Recent studies have highlighted the importance of the human gut microbiota in health and disease, suggesting that the pathogenesis of IBD is highly associated with imbalances of the gut microbiota or alterations of epithelial barrier function in the gastrointestinal (GI) tract. Moreover, diet-induced alterations of the gut microbiota in the GI tract modulate immune responses and perturb metabolic homeostasis. This review summarizes recent findings on IBD and its association with diet-induced changes in the gut microbiota; furthermore, it discusses how diets can modulate host gut microbes and immune systems, potentiating the impact of personalized diets on therapeutic targets for IBD.

Hydroxytyrosol Alleviates Dextran Sulfate Sodium-Induced Colitis by Modulating Inflammatory Responses, Intestinal Barrier, and Microbiome

Hydroxytyrosol (HT), a polyphenol derived from olive oil, was examined against dextran sulfate sodium (DSS)-induced colitis to study its potential in preventing colitis and the underlying mechanisms involved. The low dose and high dose of HT used in mice were 10 and 50 mg/kg, respectively. Research findings have shown that HT is effective in preventing colitis by alleviating the signs of colitis. HT intervention significantly reduces colitis markers such as myeloperoxidase (MPO) and proinflammatory cytokine (IL-6, IL-1β, and TNF-α). Also, mice treated with a high dose of HT showed increased secretion of antioxidant enzymes (heme oxygenase-1 (HO) and anti-inflammatory cytokine (IL-10) by 2.32- and 2.28-fold, respectively, in comparison to the DSS-treated group. Modulation effects of HT on the antioxidant signal pathway (NRF2) and the inflammatory pathway (NF-κB) were confirmed. Meanwhile, HT promoted the regeneration of the intestinal barrier and maintained intestinal functional homeostasis by boosting the regeneration of goblet cells and the expression of mucin protein (Muc2) and tight junction (TJ) proteins (claudin-1, occludin, and Zonula Occludens-1). Moreover, HT intervention obviously transformed the gut microbiota, leading to a lower abundance of inflammation-related microbes (e.g., Bacteroidaceae and Desulfovibrionaceae) and a higher level of short-chain fatty acids (SCFAs) producing bacteria (e.g., Lachnospiraceae, Muribaculaceae, ASF356, and Colidextribacter). Scientific evidence for the beneficial effect of the "Mediterranean diet" (MD) on intestinal health was achieved by elucidating the alleviation mechanism of hydroxytyrosol on colitis.

Receptor Guanylyl Cyclase C and Cyclic GMP in Health and Disease: Perspectives and Therapeutic Opportunities

Receptor Guanylyl Cyclase C (GC-C) was initially characterized as an important regulator of intestinal fluid and ion homeostasis. Recent findings demonstrate that GC-C is also causally linked to intestinal inflammation, dysbiosis, and tumorigenesis. These advances have been fueled in part by identifying mutations or changes in gene expression in GC-C or its ligands, that disrupt the delicate balance of intracellular cGMP levels and are associated with a wide range of clinical phenotypes. In this review, we highlight aspects of the current knowledge of the GC-C signaling pathway in homeostasis and disease, emphasizing recent advances in the field. The review summarizes extra gastrointestinal functions for GC-C signaling, such as appetite control, energy expenditure, visceral nociception, and behavioral processes. Recent research has expanded the homeostatic role of GC-C and implicated it in regulating the ion-microbiome-immune axis, which acts as a mechanistic driver in inflammatory bowel disease. The development of transgenic and knockout mouse models allowed for in-depth studies of GC-C and its relationship to whole-animal physiology. A deeper understanding of the various aspects of GC-C biology and their relationships with pathologies such as inflammatory bowel disease, colorectal cancer, and obesity can be leveraged to devise novel therapeutics.