Association between gastrointestinal motility and macrophage/mast cell distribution in mice during the healing stage after DSS‑induced colitis

Research Progress of Central and Peripheral Corticotropin-Releasing Hormone in Irritable Bowel Syndrome with Comorbid Dysthymic Disorders

Irritable bowel syndrome (IBS) is considered a stress disorder characterized by psychological and gastrointestinal dysfunction. IBS patients not only suffer from intestinal symptoms such as abdominal pain, diarrhea, or constipation but also, experience dysthymic disorders such as anxiety and depression. Studies have found that corticotropin-releasing hormone plays a key role in IBS with comorbid dysthymic disorders. Next, we will summarize the effects of corticotropin-releasing hormone from the central nervous system and periphery on IBS with comorbid dysthymic disorders and relevant treatments based on published literatures in recent years.

Surface functionalization affects the retention and bio-distribution of orally administered mesoporous silica nanoparticles in a colitis mouse model

Besides the many advantages of oral drug administration, challenges like premature drug degradation and limited bioavailability in the gastro-intestinal tract (GIT) remain. A prolonged residence time in the GIT is beneficial for enhancing the therapeutic outcome when treating diseases associated with an increased intestinal clearance rate, like inflammatory bowel disease (IBD). In this study, we synthesized rod-shaped mesoporous silica nanoparticles (MSNs) functionalized with polyethylene glycol (PEG) or hyaluronic acid (HA) and investigated their bio-distribution upon oral administration in vivo. The negatively charged, non-toxic particles showed different accumulation behavior over time in healthy mice and in mice with dextran sulfate sodium (DSS)-induced intestinal inflammation. PEGylated particles were shown to accumulate in the lower intestinal tract of healthy animals, whereas inflammation promoted retention of HA-functionalized particles in this area. Overall systemic absorption was low. However, some particles were detected in organs of mice with DSS-induced colitis, especially in the case of MSN-PEG. The in vivo findings were connected to surface chemistry-related differences in particle adhesion on Caco-2/Raji and mucus-producing Caco-2/Raji/HT29 cell co-culture epithelial models in vitro. While the particle adhesion behavior in vivo was mirrored in the in vitro results, this was not the case for the resorption results, suggesting that the in vitro model does not fully reflect the erosion of the inflamed epithelial tissue. Overall, our study demonstrates the possibility to modulate accumulation and retention of MSNs in the GIT of mice with and without inflammation through surface functionalization, which has important implications for the formulation of nanoparticle-based delivery systems for oral delivery applications.

Assessing acute colitis induced by dextran sulfate sodium in rats and its impact on gastrointestinal fluids

Dextran sulfate sodium (DSS) is commonly used to induce colitis in rats. While the DSS-induced colitis rat model can be used to test new oral drug formulations for the treatment of inflammatory bowel disease, the effect of the DSS treatment on the gastrointestinal tract has not been thoroughly characterized. Additionally, the use of different markers to assess and confirm successful induction of colitis is somewhat inconsistent. This study aimed to investigate the DSS model to improve the preclinical evaluation of new oral drug formulations. The induction of colitis was evaluated based on the disease activity index (DAI) score, colon length, histological tissue evaluation, spleen weight, plasma C-reactive protein, and plasma lipocalin-2. Furthermore, the study investigated how the DSS-induced colitis affected the luminal pH, lipase activity, and concentrations of bile salts, polar lipids, and neutral lipids. For all evaluated parameters, healthy rats were used as a reference. The DAI score, colon length, and histological evaluation of the colon were effective disease indicators in DSS-induced colitis rats, while spleen weight, plasma C-reactive protein, and plasma lipocalin-2 were not. The luminal pH of the colon and bile salt- and neutral lipid concentrations in regions of the small intestine were lower in DSS-induced rats compared to healthy rats. Overall, the colitis model was deemed relevant for investigating ulcerative colitis-specific formulations.

Diarrhea-predominant Irritable Bowel Syndrome-like Symptoms in Patients With Quiescent Crohn's Disease: Comprehensive Analysis of Clinical Features and Intestinal Environment Including the Gut Microbiome, Organic Acids, and Intestinal Permeability

Background/Aims

Diarrhea-predominant irritable bowel syndrome (IBS-D)-like symptoms frequently occur in patients with quiescent Crohn's disease (CD). To investigate the factors underlying IBS-D-like symptoms in patients with quiescent CD, we performed a comprehensive analysis of the clinical features and intestinal environment in those patients.

Methods

We performed a prospective observational study of 27 patients with quiescent CD (CD activity index [CDAI] ≤ 150; C-reactive protein ≤ 0.3 mg/dL). The presence and severity of IBS-D-like symptoms, health-related quality of life, disease-specific quality of life, and status of depression and anxiety were evaluated. The level of intestinal permeability, fecal calprotectin and organic acids and the profiles of gut microbiome were analyzed.

Results

Twelve of the 27 patients with quiescent CD (44.4%) had IBS-like symptoms, and these patients showed a significantly higher CDAI, IBS severity index and anxiety score than those without. The inflammatory bowel disease questionnaire score was significantly lower in the patients with IBS-D-like symptoms. There were no significant differences in small intestinal/colonic permeability or the levels of organic acids between the patients with and without IBS-D-like symptoms. Fusicatenibacter was significantly less abundant in the patients with IBS-D-like symptoms whereas their fecal calprotectin level was significantly higher (384.8 ± 310.6 mg/kg) than in patients without (161.0 ± 251.0 mg/kg). The receiver operating characteristic curve constructed to predict IBS-D-like symptoms in patients with quiescent CD using the fecal calprotectin level (cutoff, 125 mg/kg) showed a sensitivity and specificity of 73.3% and 91.7%, respectively.

Conclusion

Minimal inflammation is closely associated with the development of IBS-D-like symptoms in patients with quiescent CD.

Probiotics, prebiotics, and synbiotics in chronic constipation: Outstanding aspects to be considered for the current evidence

This integrative aimed to evaluate the effects and the potential mechanism of action of prebiotics, probiotics, and synbiotics on constipation-associated gastrointestinal symptoms and to identify issues that still need to be answered. A literature search was performed in the PubMed database. Animal models (n = 23) and clinical trials (n = 39) were included. In animal studies, prebiotic, probiotic, and synbiotic supplementation showed a decreased colonic transit time (CTT) and an increase in the number and water content of feces. In humans, inulin is shown to be the most promising prebiotic, while B. lactis and L. casei Shirota probiotics were shown to increase defecation frequency, the latter strain being more effective in improving stool consistency and constipation symptoms. Overall, synbiotics seem to reduce CTT, increase defecation frequency, and improve stool consistency with a controversial effect on the improvement of constipation symptoms. Moreover, some aspects of probiotic use in constipation-related outcomes remain unanswered, such as the best dose, duration, time of consumption (before, during, or after meals), and matrices, as well as their effect and mechanisms on the regulation of inflammation in patients with constipation, on polymorphisms associated with constipation, and on the management of constipation via 5-HT. Thus, more high-quality randomized control trials (RCTs) evaluating these lacking aspects are necessary to provide safe conclusions about their effectiveness in managing intestinal constipation.

Association between impaired healing after orthognathic surgery and irritable bowel syndrome: A case report and literature review

Introduction

In the disease irritable bowel syndrome (IBS), gastrointestinal function is worsened even though no organic abnormalities are observed in the gastrointestinal mucosa. We report the case of an orthognathic surgery patient with suspected irritable bowel syndrome.

Case

In September 2017, a 15-year-old Japanese female was referred to us with dental crowding, malocclusion, and mandibular protrusion. In June 2019, a disagreement with classmates led to abdominal pain, diarrhea, and hemorrhage; in August 2019, a preoperative blood test showed sudden anemia, and her surgery was thus postponed. Subsequent upper and lower gastrointestinal endoscopy revealed no organic abnormality, and no definitive diagnosis was made. In March 2020, after an improvement in anemia was observed, a segmental Le Fort I osteotomy and bilateral sagittal split ramus osteotomy (BSSRO) were performed under general anesthesia. On the third post-operative day, due to the mucosal dehiscence adjacent to the suture part, the titanium plate was exposed, and irrigation of the wound with normal saline solution and oral hygiene instruction was continued daily for 2 weeks. Two years and eight months have passed since the surgery, and the healing of the oral mucosa and bone has been uneventful.

Discussion

The relationship between IBS and post-operative impaired healing associated with the fragility of the oral mucosa is unknown. However, psychological stress has been reported as a cause of IBS and to be related to oral microorganisms.

Conclusion

Reducing risk factors for IBS and maintaining proper perioperative oral hygiene is essential in managing similar cases.

•

Irritable bowel syndrome (IBS) is a functional gastrointestinal disease with recurrent abdominal pain.

•

It is difficult to diagnose IBS since the clinical symptoms are confusing.

•

IBS and psychological stress affect post-surgical healing.

•

Reducing risk factors for IBS and maintaining proper perioperative oral hygiene is essential in the management.

Mast cell mediation of visceral sensation and permeability in irritable bowel syndrome

Abnormalities of mast cell structure or function may play prominent roles in irritable bowel syndrome (IBS) symptom genesis. Mast cells show close apposition to sensory nerves and release bioactive substances in response to varied stimuli including infection, stress, and other neuroendocrine factors. Most studies focus on patients who develop IBS after enteric infection or who report diarrhea-predominant symptoms. Three topics underlying IBS pathogenesis have been emphasized in recent investigations. Visceral hypersensitivity to luminal stimulation is found in most IBS patients and may contribute to abdominal pain. Mast cell dysfunction also may disrupt epithelial barrier function which alters mucosal permeability potentially leading to altered bowel function and pain. Mast cell products including histamine, proteases, prostaglandins, and cytokines may participate in hypersensitivity and permeability defects, especially with diarrhea-predominant IBS. Recent experimental evidence indicates that the pronociceptive effects of histamine and proteases are mediated by the generation of prostaglandins in the mast cell. Enteric microbiome interactions including increased mucosal bacterial translocation may activate mast cells to elicit inflammatory responses underlying some of these pathogenic effects. Therapies to alter mast cell activity (mast cell stabilizers) or function (histamine antagonists) have shown modest benefits in IBS. Future investigations will seek to define patient subsets with greater potential to respond to therapies that address visceral hypersensitivity, epithelial permeability defects, and microbiome alterations secondary to mast cell dysfunction in IBS.

The Role of Intestinal Macrophages in Gastrointestinal Homeostasis: Heterogeneity and Implications in Disease

Intestinal macrophages play a key role in the gut immune system and the regulation of gastrointestinal physiology, including gut motility and secretion. Their ability to keep the gut from chronic inflammation despite constantly facing foreign antigens has been an important focus in gastrointestinal research. However, the heterogeneity of intestinal macrophages has impeded our understanding of their specific roles. It is now becoming clear that subsets of intestinal macrophages play diverse roles in various gastrointestinal diseases. This occurs through a complex interplay between cytokine production and enteric nervous system activation that differs for each pathologic condition. Key diseases and disorders in which intestinal macrophages play a role include postoperative ileus, inflammatory bowel disease, necrotizing enterocolitis, as well as gastrointestinal disorders associated with human immunodeficiency virus and Parkinson's disease. Here, we review the identification of intestinal macrophage subsets based on their origins and functions, how specific subsets regulate gut physiology, and the potential for these heterogeneous subpopulations to contribute to disease states. Furthermore, we outline the potential for these subpopulations to provide unique targets for the development of novel therapies for these disorders.

Transitional changes in gastrointestinal transit and rectal sensitivity from active to recovery of inflammation in a rodent model of colitis

Patients with ulcerative colitis are typically suspected of an inflammatory flare based on suggestive symptoms of inflammation. The aim of this study was to evaluate the impact of inflammation on colonic motility and rectal sensitivity from active to recovery of inflammation. Male rats were given drinking water with 5% dextran sulfate sodium for 7 days. Inflammation, intestinal motor and sensory functions were investigated weekly for 6 weeks. (1) The disease activity index score, fecal calprotectin and tumor necrosis factor alpha were increased from Day 0 to Day 7 (active inflammation) and then decreased gradually until recovery. (2) Distal colon transit was accelerated on Day 7, and then remained unchanged. Whole gut transit was delayed on Day 7 but accelerated from Day 14 to Day 42. (3) Rectal compliance was unaffected from Day 0 to Day 7, but decreased afterwards. (4) Rectal hypersensitivity was noted on Day 7 and persistent. (5) Plasma acetylcholine was decreased on Day 7 but increased from Day 14 to Day 42. Nerve growth factor was increased from Day 7 to Day 42. DSS-induced inflammation leads to visceral hypersensitivity that is sustained until the resolution of inflammation, probably mediated by NGF. Rectal compliance is reduced one week after the DSS-induced inflammation and the reduction is sustained until the resolution of inflammation. Gastrointestinal transit is also altered during and after active colonic inflammation.

Effects of Mast Cells Induced by NSAIDs Impair Intestinal Epithelial Barrier Function In Vivo and In Vitro

To explore the correlation between altered expression of mast cells and PAR-2 and impaired mucosal barrier in NSAIDs enteropathy through animal and cell experiments, and to elucidate the role of mast cells and PAR-2 in the pathogenesis of NSAIDs enteropathy and the regulatory mechanism of the tight junction of intestinal epithelium. Animal experiments: the NSAIDs-related small intestine injury model was established by intragastric administration of diclofenac sodium, and mast cells were detected by toluidine blue staining. Cell experiments: Intestinal epithelial cell line (IEC-6) was applied with diclofenac sodium and its activity was detected by CCK-8.IEC-6 and RBL-2H3 were co-cultured to evaluate the permeability of intestinal epithelial cells by detecting the concentration of potassium ion and LDH. The expressions of tight junction proteins (zo-1, claudin-1, occludin), cytoskeletal components (actin, tubulin, keratin) and par-2 were analyzed by Western Blot. In animal experiments, the number of mast cells was significantly increased after 24 h of action of diclofenac sodium. In cell experiments, the survival rate of IEC-6 cells decreased significantly when the concentration of diclofenac sodium is more than 50 μg/mL; after 24 h of co-culture, the potassium and LDH concentration in the co-culture group were significantly higher, and the expression of ZO-1, claudin-1, occludin, tubulin, and keratin was decreased. Mast cells activate PAR-2 in intestinal epithelial cells, downregulate the related proteins of cell tight junctions and cytoskeletal proteins, and increase the permeability of intestinal epithelial cells.

Gut macrophages: key players in intestinal immunity and tissue physiology

The mammalian gastrointestinal tract harbors a large reservoir of tissue macrophages, which, in concert with other immune cells, help to maintain a delicate balance between tolerance to commensal microbes and food antigens, and resistance to potentially harmful microbes or toxins. Beyond their roles in resistance and tolerance, recent studies have uncovered novel roles played by tissue-resident, including intestinal-resident macrophages in organ physiology. Here, we will discuss recent advances in the understanding of the origin, phenotype and function of macrophages residing in the different layers of the intestine during homeostasis and under pathological conditions.

The Link between Type III Reg and STAT3-Associated Cytokines in Inflamed Colonic Tissues

Reg (regenerating gene) family proteins are known to be overexpressed in gastrointestinal (GI) tissues under conditions of inflammation. However, the pathophysiological significance of Reg family protein overexpression and its regulation is still unclear. In the present study, we investigated the profile of Reg family gene expression in a colitis model and focused on the regulation of Reg IIIβ and IIIγ, which are overexpressed in inflamed colonic mucosa. C57BL/6 mice were administered 2% dextran sulfate sodium (DSS) in drinking water for five days, and their colonic tissues were investigated histopathologically at interval for up to 12 weeks. Gene expression of the Reg family and cytokines (IL-6, IL-17, and IL-22) was evaluated by real-time RT-PCR, and Reg IIIβ/γ expression was examined by immunohistochemistry. The effects of cytokines on STAT3 phosphorylation and HIP/PAP (type III REG) expression in Caco2 and HCT116 cells were examined by Western blot analysis. Among Reg family genes, Reg IIIβ and IIIγ were alternatively overexpressed in the colonic tissues of mice with DSS-induced colitis. The expression of STAT3-associated cytokines (IL-6, IL-17, and IL-22) was also significantly increased in those tissues, being significantly correlated with that of Reg IIIβ/γ. STAT3 phosphorylation and HIP/PAP expression were significantly enhanced in Caco2 cells upon stimulation with IL-6, IL-17, and IL-22. In HCT116 cells, those enhancements were also observed by IL-6 and IL-22 stimulations but not IL-17. The link between type III Reg and STAT3-associated cytokines appears to play a pivotal role in the pathophysiology of DSS-induced colitis.