Mid Colon Research Articles

Pharmacological characterization of alpha adrenoceptor-mediated motor responses in the rat colon.

Inhibitory neuromuscular transmission in the gastrointestinal tract is mediated by intrinsic nitrergic and purinergic neurons. Purines activate G protein-coupled receptor P2Y1 receptors, increasing intracellular Ca2+ that activates small conductance calcium-activated potassium (SKCa) channels. Little is known about the effect of adrenergic receptor activation on intestinal smooth muscle. In vascular tissue, stimulation of α-adrenoceptors causes smooth muscle contraction, while their effect on intestinal tissue is poorly understood. This study aimed to pharmacologically characterize the effect of α-adrenoceptor activation in the rat colon, which shares similar inhibitory pathways to the human colon. Muscle bath experiments were performed with the rat proximal, mid, and distal colon oriented both circularly and longitudinally. The α1-adrenoceptor agonist phenylephrine (PE) (10-8-10-5 M) evoked concentration-dependent relaxations of the intestinal smooth muscle from all regions and orientations. However, in the mid-circular colon at low PE concentrations, a contraction sensitive to 10-5 M phentolamine (non-selective α-adrenoceptor blocker), the neural blocker tetrodotoxin (TTX; 10-6 M), and atropine (10-6 M) was recorded. PE-induced relaxations were insensitive to TTX (10-6 M) and the nonselective β-adrenoceptor blocker propranolol (10-6 M). In contrast, PE-induced relaxations were blocked by phentolamine (10-5 M), prazosin (10-6 M) (α1-adrenoceptor blocker), and RS17053 (10-6 M) (α1A-blocker), but not by yohimbine (10-6 M) (α2-adrenoceptor blocker). Apamin (10-6 M), a SKCa channel blocker, abolished PE-induced relaxations. Contractile responses in the circular muscle of the mid colon could be attributed to α-adrenoceptors located on enteric cholinergic neurons. Stimulation of α1A-adrenoreceptors activates SKCa channels to cause smooth muscle relaxation, which constitutes a signaling pathway that shares similarities with P2Y1 receptors.

Efficacy of colonoscopic re-examination across the entire colon: a randomized controlled trial.

In standard colonoscopic examinations, some polyps may be missed during the withdrawal phase. Re-examination of the right colon can improve the adenoma detection rate (ADR). However, the effectiveness of applying this re-examination strategy to the entire colon remains unknown. We investigated whether re-examination could increase the detection rate of polyps and adenomas throughout the colon. A randomized, controlled, single-center trial (NCT03268200) was conducted in a university hospital. Patients aged 45-75years were randomly assigned to either the study or control group. For patients in the control group, observation and polypectomy were performed once using the standard colonoscopy method. For patients in the study group, polypectomy was repeated twice during the withdrawal phase after the initial insertion of the colonoscope. These examinations were performed in the right transverse and left colons. The primary endpoints were the polyp detection rate (PDR) and ADR, defined as the proportion of patients with ≥ 1 polyp and ≥ 1 adenoma, respectively. Overall, 406 patients were enrolled (study group, n = 210; control group, n = 196) and analyzed. Generally, PDRs and ADRs were similar between the study (withdrawal 1 + 2) and control groups (withdrawal 1), except for the right colon. However, the second withdrawal review increased number of polyps and adenomas in the overall, right, mid, and left colon, respectively. The results of this trial indicated that re-examination of the entire colon during colonoscopy could be beneficial for detecting concealed polyps in patients at risk of interval cancer.

Evaluation of the efficacy of polyethylene glycol in combination with different doses of linaclotide in a fractionated bowel preparation for colonoscopy: a prospective randomized controlled study

Background and aimThe ideal bowel cleansing program still needs to be explored. The aim was to compare the bowel cleansing effect and patient tolerance of low-dose polyethylene glycol (PEG) combined with different doses of linaclotide in fractionated bowel preparation.MethodsThe subjects were randomly assigned to the 3LPEG group, 2LPEG + 2L group, or 2LPEG + L group. The primary outcome was to use the Ottawa Bowel Preparation Scale (OBPS) to evaluate the efficacy of bowel cleansing, and the secondary outcomes were the detection rate of adenomas and polyps, adverse reactions, tolerance, and defecation dynamics; subsets of patients with chronic constipation and irritable bowel syndrome were also analyzed.ResultsA total of 753 patients were randomly assigned. In ITT analysis, the success of preparation of the 2LPEG + 2L group was better than that of the 2LPEG + L group or the 3LPEG group (92.0% vs. 82.3% vs. 82.1%; P = 0.002). Compared with the 3LPEG group, the 2LPEG + L group showed similar but non-inferior results (82.3% vs. 82.1%, P > 0.05). The 2LPEG + 2L group was similar to the 2LPEG + L group in terms of adverse reaction, tolerance, willingness to reuse, and sleep quality, but both were superior to the 3LPEG group. In a subgroup analysis of chronic constipation, the 2LPEG + 2L group had the best cleansing effect on the right colon and mid colon, while in the subgroup analysis of irritable bowel syndrome, the tolerance was better in the 2LPEG + 2L group and the 2LPEG + L group than the 3LPEG group.Conclusions2LPEG + 2L is a feasible bowel preparation regimen.

Novel Role of the ALPI Gene Associated with Constipation Caused by Complement Component 3 Deficiency.

Complement component 3 (C3) deficiency has recently been reported as one of the novel causes of constipation. To identify a unique gene specific to constipation caused by C3 deficiency, the total RNA extracted from the mid colon of C3 knockout (C3 KO) mice was hybridized to oligonucleotide microarrays, and the function of the candidate gene was verified in in vitro and in vivo models. C3 KO mice used for microarrays showed definite phenotypes of constipation. Overall, compared to the wild type (WT), 1237 genes were upregulated, and 1292 genes were downregulated in the C3 KO mice. Of these, the major genes included were lysine (K)-specific demethylase 5D (KDM5D), olfactory receptor 870 (Olfr870), pancreatic lipase (PNLIP), and alkaline phosphatase intestinal (ALPI). Specifically, the ALPI gene was selected as a novel gene candidate based on alterations during loperamide (Lop)-induced constipation and intestinal bowel disease (IBD). The upregulation of ALPI expression treated with acetate recovered the expression level of mucin-related genes in primary epithelial cells of C3 KO mice as well as most phenotypes of constipation in C3 KO mice. These results indicate that ALPI plays an important role as the novel gene associated with C3 deficiency-induced constipation.

Novel insights into mechanisms of inhibition of colonic motility by loperamide.

It is well known that opiates slow gastrointestinal (GI) transit, via suppression of enteric cholinergic neurotransmission throughout the GI tract, particularly the large intestine where constipation is commonly induced. It is not clear whether there is uniform suppression of enteric neurotransmission and colonic motility across the full length of the colon. Here, we investigated whether regional changes in colonic motility occur using the peripherally-restricted mu opioid agonist, loperamide to inhibit colonic motor complexes (CMCs) in isolated mouse colon. High-resolution video imaging was performed to monitor colonic wall diameter on isolated whole mouse colon. Regional changes in the effects of loperamide on the pattern generator underlying cyclical CMCs and their propagation across the full length of large intestine were determined. The sensitivity of CMCs to loperamide across the length of colon varied significantly. Although there was a dose-dependent inhibition of CMCs with increasing concentrations of loperamide (10 nM - 1 μM), a major observation was that in the mid and distal colon, CMCs were abolished at low doses of loperamide (100 nM), while in the proximal colon, CMCs persisted at the same low concentration, albeit at a significantly slower frequency. Propagation velocity of CMCs was significantly reduced by 46%. The inhibitory effects of loperamide on CMCs were reversed by naloxone (1 μM). Naloxone alone did not change ongoing CMC characteristics. The results show pronounced differences in the inhibitory action of loperamide across the length of large intestine. The most potent effect of loperamide to retard colonic transit occurred between the proximal colon and mid/distal regions of colon. One of the possibilities as to why this occurs is because the greatest density of mu opioid receptors are located on interneurons responsible for neuro-neuronal transmission underlying CMCs propagation between the proximal and mid/distal colon. The absence of effect of naloxone alone on CMC characteristics suggest that the mu opioid receptor has little ongoing constitutive activity under our recording conditions.

Colonic transposition using mid colon for corrosive oesophageal strictures.

To evaluate mid colon as a viable alternative for reconstruction in diffuse corrosive oesophageal stricture compared to other modes. This is a prospective observational study of surgical management of corrosive oesophageal stricture using the colonic interposition graft. Eight patients were included for a period of 4years from January 2017 to December 2020 and followed up for a mean period of 32months (range of 24 to 46months). The results in these eight patients are discussed. A total of 8 patients underwent retrosternal oesophagocoloplasty and gastrojejunostomy. There was no intraoperative or hospital death. Postoperative complications included one patient each having aspiration pneumonia and anastomotic leak. A successful reconstruction can be done by securing the correct vascular pedicle and a technique of good anastomosis. From our experience, colonic transposition using mid colon as conduit can be considered as a viable alternative in patients with long segment oesophageal stricture.

A165 FCGBP IN THE COLON IS SPATIALLY DEPENDENT ON MUC2 EXPRESSION AND IS DEGRADED IN DEXTRAN SULFATE SODIUM-INDUCED COLITIS

Abstract Background The colonic mucus bilayer is an integral innate host defense mechanism that provides a physical barrier separating the lumen and its contents from the underlying epithelium. This essential barrier is produced by specialized secretory goblet cells of which Muc2 mucin is its primary product. IgG-Fc-binding protein (Fcgbp) is the second most abundant protein produced by goblet cells, which has a suggested function of crosslinking with Muc2 to stabilize the structural integrity of mucus. FCGBP is observed to decrease preceding the onset of inflammation in ulcerative colitis patients, leading to spatially distinct structural mucus weakening to contribute to the pathogenesis of the disease. Purpose Fcgbp is altered regionally in the gut and plays a role in the pathogenesis of dextran sulfate sodium (DSS)-induced colitis. The specific aims are: To characterize the spatial expression of Muc2 and Fcgbp basally in goblet cells To quantify alterations in Muc2 and Fcgbp in response to DSS-induced colitis and at restitution of disease Method mRNA and protein expression in Muc2+/+ and Muc2-/- C57BL/6 littermates were analyzed by RT-qPCR and Western blotting, respectively. Mucin granules were isolated from colonic goblet cells and the proteome quantified by liquid chromatography and tandem mass spectrometry (LC-MS/MS). Colitis was induced in Muc2+/+ mice with 3.5% (w/v) DSS in tap water for five days, whereas Muc2-/- littermates were given 1.5% (w/v) DSS in tap water for three days, ad libitum. Mice were given regular tap water for the remainder of the experiment to allow restitution of inflammation. Disease activity index (DAI) was scored based on weight loss. Mice were sacrificed at various time points up to 10 days, and colons excised and sectioned for histopathology analysis. Result(s) LC-MS/MS of mucin granules run under reducing and non-reducing conditions confirmed that Muc2 and Fcgbp were the most abundant proteins in mucin granules and were non-covalently bound to each other. mRNA and protein expression of Muc2 and Fcgbp were highly expressed in the mid colon, and regulation of Fcgbp was unaffected in Muc2-/- littermates. In response to DSS-induced colitis in Muc2+/+ mice, Muc2 transcription rapidly increased in all regions of the colon with highest expression in the mid colon. In contrast, Fcgbp transcription increased in the mid and distal colons and peaked during highest disease activity. Interestingly, Fcgbp protein expression was abrogated in the mid colon even at restitution. In Muc2-/- mice, Fcgbp transcription decreased during disease onset but returned to normal levels following removal of DSS. Image Conclusion(s) This study demonstrates that in response to DSS, Fcgbp expression was spatially degraded at the onset of disease and remained low at restitution. The disappearance of Fcgbp in the mid colon of Muc2+/+ littermates, despite Muc2 restoration, suggests that the mucus barrier remains structurally altered and functionally impaired at restitution. Supported by CIHR Disclosure of Interest None Declared

Improvement of the intestinal epithelial barrier during laxative effects of phlorotannin in loperamide-induced constipation of SD rats

BackgroundDisruptions of the intestinal epithelial barrier (IEB) are frequently observed in various digestive diseases, including irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). This study assessed the improvement in the IEB during the laxative activity of phlorotannin (Pt) harvested from Ecklonia cava in constipation by examining the changes in the expression of the regulatory proteins for the tight junction (TJ) and adherens junction (AJ), and inflammatory cytokines in Sprague Dawley (SD) rats with loperamide (Lm)-induced constipation after a Pt treatment.ResultsThe Pt treatment induced laxative activity, including the improvement of feces-related parameters, gastrointestinal transit rate, and histological structure of the mid colon in Lm-treated SD rats. In addition, significant recovery effects were detected in the histology of IEB, including the mucus layer, epithelial cells, and lamina propria in the mid colon of Lm + Pt treated SD rats. The expression levels of E-cadherin and p120-catenin for AJ and the ZO-1, occludin, and Claudin-1 genes for TJ in epithelial cells were improved remarkably after the Pt treatment, but the rate of increase was different. Furthermore, the Pt treatment increased the expression level of several inflammatory cytokines, such as TNF-α, IL-6, IL-1β, IL-13, and IL-4 in Lm + Pt treated SD rats.ConclusionsThese results provide the first evidence that the laxative activity of Pt in SD rats with Lm-induced constipation phenotypes involve improvements in the IEB.

S2031 Fibrosing Colonopathy in Chronic Alcoholic Pancreatitis: A Diagnostic Dilemma

Introduction: Fibrosing colonopathy (FC) is a rare entity that has been associated with high-dose pancreatic enzyme replacement therapy (PERT) and has been mostly reported in patients with cystic fibrosis. We present a case of chronic alcoholic pancreatitis and FC that eluded diagnosis for 4 years resulting in multiple endoscopic interventions. Case Description/Methods: A 47-year-old male with a history of substance abuse and chronic alcoholic pancreatitis presented with 1.5 days of lower abdominal pain, nausea and vomiting. He reported chronic watery diarrhea up to 5 times/day and lost 20 kg within 1 year. His current weight was 64 kg. Patient was on pancrelipase 24,000 units thrice daily, but he was intermittently non-adherent with PERT due to socioeconomic issues. He had 21 prior CT scans suggestive of colitis for which he underwent 5 lower endoscopic evaluations in the span of 4 years. Random colonic biopsies from these endoscopies were all histologically normal. Work-up for infectious, celiac, thyroid and inflammatory bowel diseases was unremarkable. Fecal elastase was undetectable. Vitamins A, D and E levels were low. After a second careful review of all prior images with radiologist, there was evidence of chronic, colonic wall thickening without inflammation consistent with FC. After excluding other pathology, exocrine pancreatic insufficiency was the likely etiology of his symptoms. The patient was continued on the current dose of PERT and nutrition consultation was recommended (Figure). Discussion: FC is a long segment colonic disease characterized by a gradual, fusiform stenosis of the lumen resulting from submucosal fibrosis. The exact pathogenesis remains unknown, but it has been associated with high doses of PERT and compounds in the enteric-coated material. FC may occur months to years after the initiation of high-dose PERT. Interestingly, our patient was on PERT for 5 years and was prescribed an appropriate dose. FC commonly manifests as abdominal pain, diarrhea, hematochezia and, in some cases, small bowel obstruction. Prior intestinal surgery is a possible risk factor for FC. On endoscopy, a loss of haustral pattern or “cobblestone” colonic mucosa may be seen. While a full thickness colonic resection is the gold standard for diagnosis, FC was diagnosed in our case based on clinical and radiologic data after exclusion of other pathology. Management of FC involves avoidance of high doses of PERT ( >10,000 units/kg/day). Surgical resection of the colon is reserved for refractory casesFigure 1.: Panel 1. Axial view (left) and coronal view (right) of an abdominopelvic computed tomography scan with intravenous contrast demonstrating colonic wall thickening of the mid and distal sigmoid colon (blue arrows).

S2065 Lipoma!, Leading Point of a Colonic Intussusception

Introduction: Intussusception is Intestine telescoping into itself. Commonly benign, self resolving condition seen in children more often. Presentation in adults is rare. It represents 1-5% of all obstructions and intussusceptions. It is commonly associated with a definable lead point in about 70-90% of the cases. There is no exact explanation of the events but luminal location of a mass plus the presence of food in the GI tract contribute to the telescoping event to the distal bowel. Case Description/Methods: A 47-year-old woman with history of anxiety and constipation, presents with 2 weeks of constipation along with recent abdominal pain, nausea, liquid bowel movements, decreased stool caliber, melena, and hematochezia. Denies weight loss. No surgeries or cancer history. No previous endoscopies. CT scan showed a descending colon to sigmoid intussusception with a possible polyp vs diverticulum as the lead point. Intussusception spanning approximately 12.7 cm in length. Patient underwent colonoscopy which revealed a large partially obstructing circumferential, firm, mobile mass in mid sigmoid colon with no bleeding. There was mucosal congestion, superficial areas of erosion but no necrosis or perforation most likely being the site of intussusception appreciated on CT. Diverticula was also found. Partial colectomy was performed. Intraoperatively, tumor involvement at the splenic flexure was noticed. Post operative course was uneventful. The patient was discharged home with no complications. Eventually, biopsy revealed an infarcted intramural lipomatous tumor, 5.5 cm in dimension, completely resected. Peritumoral intra and extramural abscess, and chronic active sclerosing mesenteritis. Diverticulosis without perforation. No evidence of malignancy (Figure 1). Discussion: Colon Intussusception in adults is commonly associated with malignancy or underlying lesions. The incidence of intussusception is about 5% and only 1/4th are symptomatic. The presentation is non-specific and episodic and thus, is difficult to diagnose. It mainly presents with abdominal pain, constipation, bleeding or diarrhea, and severe complications are complete obstruction, perforation, sepsis, ischemia, necrosis, and recurrence. CT imaging is definitive in diagnosis. Surgical intervention is the mainstay management. Prognosis depends on the underlying lesion. The mortality rate is 50% with underlying malignant lesions.Figure 1.: Colonic Mass. Intussescepted bowel.

Quantification of CGRP-immunoreactive myenteric neurons in mouse colon.

Quantitative data of biological systems provide valuable baseline information for understanding pathology, experimental perturbations, and computational modeling. In mouse colon, calcitonin gene-related peptide (CGRP) is expressed by myenteric neurons with multiaxonal (Dogiel type II) morphology, characteristic of intrinsic primary afferent neurons (IPANs). Analogous neurons in other species and gut regions represent 5-35% of myenteric neurons. We aimed to quantify proportions of CGRP-immunopositive (CGRP+) myenteric neurons. Colchicine-treated wholemount preparations of proximal, mid, and distal colon were labeled for HuC/D, CGRP, nitric oxide synthase (NOS), and peripherin (Per). The pan-neuronal markers (Hu+/Per+) co-labeled 94% of neurons. Hu+/Per- neurons comprised ∼6%, but Hu-/Per+ cells were rare. Thus, quantification was based on Hu+ myenteric neurons (8576 total; 1225±239 per animal, n=7). CGRP+ cell bodies were significantly larger than the average of all Hu+ neurons (329±13 vs. 261±12μm2 , p<.0001). CGRP+ neurons comprised 19%±3% of myenteric neurons without significant regional variation. NOS+ neurons comprised 42%±2% of myenteric neurons overall, representing a lower proportion in proximal colon, compared to mid and distal colon (38%±2%, 44%±2%, and 44%±3%, respectively). Peripherin immunolabeling revealed cell body and axonal morphology in some myenteric neurons. Whether all CGRP+ neurons were multiaxonal could not be addressed using peripherin immunolabeling. However, of 118 putatively multiaxonal neurons first identified based on peripherin immunoreactivity, all were CGRP+ (n=4). In conclusion, CGRP+ myenteric neurons in mouse colon were comprehensively quantified, occurring within a range expected of a putative IPAN marker. All Per+ multiaxonal neurons, characteristic of Dogiel type II/IPAN morphology, were CGRP+.

WE7.10 Traumatic abdominal wall hernia and CT missed severe intra-abdominal injuries

Abstract Despite traumatic abdominal wall hernia (TAWH) being a rare entity, the incidence of associated intra-abdominal injuries is extremely common. With only few cases published, TAWH remains a diagnostic as well as a therapeutic challenge. We present an obese 47-year-old female, front seat passenger, that was transferred to our hospital from a neighbouring DGH with a diagnosis of TAWH after a 30mph road traffic collision. On arrival, she was haemodynamically stable, abdominal examination showed a large hernia, extensive bruising but the abdomen was otherwise unremarkable. The CT performed before transfer showed a large hernia but no obvious other injury, no free fluid or gas was identified. Hernia repair was planned for the following day. Overnight there was a transient period of hypotension responsive to transfusion of multiple RBC units. The surgical approach was over the hernia site. Within the sac a transected end of small bowel was found and so laparotomy was undertaken, which demonstrated a bucket handle mesenteric tear of terminal ileal mesentery with infarction of 20 cm of small bowel and a complete transverse tear of mid sigmoid colon and its mesentery. Remarkably there was no intraperitoneal contamination from either injury. Our clinical case highlights that although the CT scan is the gold standard for initial diagnosis of intra-abdominal injuries in TAWH, these can still be missed. To note that failure to make a timely diagnosis can result in delayed complications with significant morbidity and mortality. Therefore, a high clinical suspicion, despite of negative imaging, is crucial to provide appropriate management.

The Role of Paracellular Transport in the Intestinal Absorption and Biopharmaceutical Characterization of Minoxidil.

The purpose of this study was to evaluate mechanisms behind the intestinal permeability of minoxidil, with special emphasis on paracellular transport, and elucidate the suitability of minoxidil to be a reference drug for Biopharmaceutics Classification System (BCS). The permeability of minoxidil (vs. metoprolol) was evaluated in-silico, in-vitro using both the PAMPA assay and across Caco-2 cell monolayers, as well as in-vivo in rats throughout the entire intestine. The permeability was studied in conditions that represent the different segments of the small intestine: upper jejunum (pH 6.5), mid small intestine (pH 7.0), distal ileum (pH 7.5), and colon (pH 6.5). Since we aimed to investigate the paracellular transport of minoxidil, we have also examined its permeability in the presence of quercetin (250 µM), which closes the tight junctions, and sodium decanoate (10 mM), which opens the tight junctions. While metoprolol demonstrated segmental-dependent rat and PAMPA permeability, with higher permeability in higher pH regions, the permeability of minoxidil was pH-independent. Minoxidil PAMPA permeability was significantly lower than its rat permeability, indicating a potential significant role of the paracellular route. In rat intestinal perfusion studies, and across Caco-2 monolayers, tight junction modifiers significantly affected minoxidil permeability; while the presence of quercetin caused decreased permeability, the presence of sodium decanoate caused an increase in minoxidil permeability. In accordance with these in-vitro and in-vivo results, in-silico simulations indicated that approximatelly 15% of minoxidil dose is absorbed paracellularly, mainly in the proximal parts of the intestine. The results of this study indicate that paracellular transport plays a significant role in the intestinal permeability of minoxidil following oral administration. Since this permeation route may lead to higher variability in comparison to transcellular, these findings diminish the suitability of minoxidil to serve as the low/high BSC permeability class benchmark.

Dysregulation of the Enteric Nervous System in the Mid Colon of Complement Component 3 Knockout Mice with Constipation Phenotypes.

Complement component 3 (C3) contributes to neurogenesis, neural migration, and synaptic elimination under normal and disease conditions of the brain, even though it has not been studied in the enteric nervous system (ENS). To determine the role of C3 in the regulatory mechanism of ENS during C3 deficiency-induced constipation, the changes in the markers of neuronal and interstitial cells of Cajal (ICCs), the markers for excitatory and inhibitory transmission of ENS, and expression of C3 receptors were analyzed in the mid colon of C3 knockout (KO) mice at 16 weeks of age. Prominent constipation phenotypes, including the decrease in stool parameters, changes in the histological structure, and suppression of mucin secretion, were detected in C3 KO mice compared to wildtype (WT) mice. The expression levels of the neuron specific enolase (NSE), protein gene product 9.5 (PGP9.5), and C-kit markers for myenteric neurons and ICCs were lower in the mid colon of C3 KO mice than WT mice. Excitatory transmission analysis revealed similar suppression of the 5-hydroxytryptamine (5-HT) concentration, expression of 5-HT receptors, acetylcholine (ACh) concentration, ACh esterase (AChE) activity, and expression of muscarinic ACh receptors (mAChRs), despite the mAChRs downstream signaling pathway being activated in the mid colon of C3 KO mice. In inhibitory transmission analysis, C3 KO mice showed an increase in the nitric oxide (NO) concentration and inducible nitric oxide synthase (iNOS) expression, while neuronal NOS (nNOS) expression, cholecystokinin (CCK), and gastrin concentration were decreased in the same mice. Furthermore, the levels of C3a receptor (C3aR) and C3bR expression were enhanced in the mid colon of C3 KO mice compared to the WT mice during C3 deficiency-induced constipation. Overall, these results indicate that a dysregulation of the ENS may play an important role in C3 deficiency-induced constipation in the mid colon of C3 KO mice.

A Trapped Colon

A Trapped Colon

Loperamide-induced Constipation Activates Inflammatory Signaling Pathways in the Mid Colon of SD Rats Via Complement C3 and its Receptors.

Complement component 3 (C3) receptors play an important role as inflammatory mediators in the innate immune system, although their mechanisms were not well studied during constipation. The aim of this study is to investigate the regulatory role of C3 and its receptors' downstream signaling during constipation. Alterations in the C3, C3a receptor (C3aR), and C3b receptor (C3bR) expressions, PI3K/AKT pathway, RhoA/MLC pathway, MAP kinase pathway, and inflammatory cytokine expressions were measured in the mid colon of loperamide (Lop) treated SD rats. Lop treatment successfully induced constipation phenotypes, including decreased stool parameters and histological structure alterations. The expression levels of C3 were significantly increased, whereas expressions of C3aR and C3bR were decreased during Lop-induced constipation. Moreover, significant upregulation was observed in the phosphorylation levels of PI3K, AKT, and GSK3β in mid colons of Lop treated SD rats. The expression of RhoA and phosphorylation of MLC were also enhanced in the Lop treated group. Furthermore, a similar pattern was detected in the MAP kinase pathway and inflammatory cytokine expressions. Subsequent to the Lop treatment, the phosphorylation of ERK and p38, as well as the mRNA levels of NF-κB, TNF-α, IL-6 and IL-1α were remarkably increased in the mid colon. These results indicate that Lop-induced constipation is tightly linked to the downregulation of C3aR and C3bR expressions, and upregulation of the C3 and C3Rs downstream signaling pathway, including PI3K/AKT, RhoA/MLC, and MAP kinase pathways as well as inflammatory cytokine expressions in the mid colon of SD rats.

Promotion of the inflammatory response in mid colon of complement component 3 knockout mice

To determine whether complement component 3 (C3) deficiency affects its receptor downstream-mediated inflammatory response, the current study was undertaken to measure alterations in the inducible nitric oxide synthase (iNOS)‑mediated cyclooxygenase‑2 (COX‑2) induction pathway, inflammasome pathway, nuclear factor-κB (NF-κB) activation, and inflammatory cytokine expressions in the mid colon of C3 knockout (KO) mice. Significant enhancement was observed in expressions of key components of the iNOS‑mediated COX‑2 induction pathway, and in the phosphorylation of mitogen‑activated protein (MAP) kinase members. A similar pattern of increase was also observed in the expression levels of inflammasome proteins in C3 KO mice. Moreover, compared to WT mice, C3 KO mice showed remarkably enhanced phosphorylation of NF-κB and Inhibitor of κB-α (IκB-α), which was reflected in entirety as increased expressions of Tumor necrosis factor (TNF), IL-6 and IL-1α. However, the levels of E-cadherin, tight junction channels and ion channels expressions were lower in the C3 KO mice, although myeloperoxidase (MPO) activity for neutrophils was slightly increased. Taken together, results of the current study indicate that C3 deficiency promotes inflammatory responses in the mid colon of C3 KO mice through activation of the iNOS‑mediated COX‑2 induction pathway, Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC)-inflammasome pathway and NF-κB signaling pathway, and the enhancement of inflammatory cytokine expressions.

Stress decreases contraction of the colon, and the effects of stress are different among the regions of the colon.

Stress affects a variety of organs. Diarrhea and constipation are closely related to stress, which involves the gastrointestinal motility of the colon. We compared the gastrointestinal motility of the proximal, mid, and distal colon in mice with stress. Stress was applied by water immersion restraint. Colon motility was measured using an isotonic transducer in the direction of the circular muscles. Electric field stimulation-induced contractions in stressed mice were reduced compared to control mice in the proximal and distal colon. On the other hand, in the mid colon, contraction in control mice and stressed mice were almost same. This interesting difference between the regions may provide a clue to the functional abnormalities in gastrointestinal motility associated with stress.

Paediatric Ulcerative Colitis Is a Fibrotic Disease and Is Linked with Chronicity of Inflammation.

Intestinal fibrosis has recently been characterised in adult ulcerative colitis and may affect motility, diarrhoea, and the symptom of urgency. We aimed to charactersze the presence of fibrosis in paediatric patients with ulcerative colitis, and its link to severity and chronicity of mucosal inflammation, as well as clinical factors of severity. We performed a single-centre cross-sectional study in children ages 1-18 years with ulcerative colitis, undergoing colectomy or proctocolectomy. Tissue cross-sections were derived from proximal, mid, and distal colon and rectum, and inflammation and fibrosis were graded based on previously developed scores. Clinical data were collected prospectively. From 62 patients, 205 intestinal sections were evaluated. Median age at diagnosis was 13 years, 100% had extensive colitis, and all resections were done for refractory disease. The presence, chronicity, and degree of inflammation were linked with the presence of fibrosis. Thickness of the muscularis mucosa was also linked with presence and chronicity of inflammation. The overall submucosal fibrosis burden was associated with prior anti-tumour necrosis factor use. Paediatric patients with ulcerative colitis exhibit colorectal submucosal fibrosis and muscularis mucosa thickening, which correlate with the presence, chronicity, and degree of mucosal inflammation. Fibrosis should be recognised as a complication of paediatric ulcerative colitis, and ulcerative colitis should be considered a progressive disease.

Inflammatory response in the mid colon of ICR mice treated with polystyrene microplastics for two weeks

BackgroundThe oral administration of polystyrene-microplastics (PS-MPs) causes chronic constipation of ICR mice, but there are no reports on their effects on the inflammatory response in the colon. To determine if the oral administration of MPs causes inflammation in the colon, the changes in the apoptosis-associated speck like protein containing a caspase recruitment domain (ASC)-inflammasome pathway, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway, and inflammatory cytokine expression were evaluated in the mid colon of ICR mice treated with 0.5 μm size PS-MPs for two weeks.ResultsThe thicknesses of the mucosa, muscle, flat luminal surface, and crypt layer were decreased significantly (p < 0.01) in the mid colon of the MPs treated group compared to the Vehicle treated group. On the other hand, a remarkable increase in the expression levels of NOD-like receptor pyrin domain-containing protein (NLRP) 3, ASC, and Cleaved Caspase (Cas)-1 protein was observed in the MPs treated group. In addition, similar increasing pattern in the levels of p-NF-κB and phospho-inhibitory subunit of NF-κB (p-IkB) α protein was detected. Four inflammatory cytokines, including NF-κB, interleukin (IL)-6, tumor necrosis factor (TNF)-α, and IL-1β, showed an increased expression level after the MPs treatment.ConclusionsTherefore, the present study suggests that PS-MPs can be a novel cause of an inflammatory response in the mid colon of ICR mice.