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Nerve remodelling during intestinal inflammation.

The intestinal mucosa contains a dense nerve network and many inflammatory cells, and these may interact through the exchange of regulatory molecules. Evidence suggests that intestinal mucosal mast cells are innervated, and it is known that the density of this cell type changes significantly in nematode-infected rats. Recent data indicates that rat jejunal mucosal nerves remodel after Nippostrongylus brasiliensis infection, with degenerative and regenerative phases during the acute and recovery stages of inflammation. Seven weeks postinfection there is a net increase in the density and number per villus of mucosal nerves. These changes suggest that mucosal nerves exhibit structural plasticity in inflamed tissues, which must impact on interactions between the enteric nervous system and other mucosal elements in disease.

Animals

99Tcm-labelled IgG scanning does not predict the distribution of intestinal inflammation in patients with inflammatory bowel disease.

In order to assess the value of 99Tcm-labelled-immunoglobulin G(99Tcm-IgG) in the assessment of the activity and distribution of intestinal inflammation in patients with inflammatory bowel disease (IBD), 99Tcm-IgG scans were performed in 18 patients. Patients were divided clinically into two groups, those with (ten patients) and those without (eight patients), intestinal inflammation. Disease activity and distribution were assessed by 111In-oxine granulocyte scanning and/or histological extent of inflammation at endoscopy or surgery in all patients with IBD and most of those without intestinal inflammation. In the assessment of the presence or absence of inflammation, a sensitivity of 80% and specificity of 87% were achieved. However, when the localization of intestinal inflammation was evaluated, only five of eight true positive scans were concordant with the distribution of intestinal inflammation as determined by other methods. Thus, significant areas of inflammation were missed in five of ten patients with IBD (two false negative, three incorrect localization of inflammation). Although 99Tcm-IgG scanning appears to have moderate sensitivity and acceptable specificity in the detection of intestinal inflammation, it performs poorly in assessing the distribution of inflammation and is, therefore, of little value in the assessment of patients with suspected or proven IBD.

Australia

Value of positive technetium-99m leucocyte scans in predicting intestinal inflammation.

The value of positive scans of autologous 99mTc-labelled leucocytes in the detection of intestinal inflammation was assessed in 29 patients with known inflammatory bowel disease and a high probability of intestinal inflammation and 58 with a low probability of intestinal inflammation comprising 37 with intestinal symptoms and 21 with suspected abscess. Autologous leucocytes were labelled with 99mTc using either of the established methods. In patients with inflammatory bowel disease, 3/13 with ileocaecal and 1/11 with colonic accumulation of 99mTc were incorrectly diagnosed in that there was no histological evidence of inflammation in those regions. In the low probability patients, all 26 positive images were false positives: there were 19 in the ileocaecal and 7 in colonic regions and no differences between the two subgroups. False positives were more common in low probability than high probability patients (p = 0.011). The results were independent of the 99mTc cell labelling technique used. Three false positive patients also had normal scans for 111In-labelled granulocytes. The time of first detection of 99mTc in the bowel was earlier in true than in false positive patients (92% v 33% within 1 h, p = 0.008), the false positive rates in the first hour of imaging being 5% in high and 15% in low probability patients. In 99mTc scintigraphy, the appearance of the isotope in the intestine occurs commonly in the absence of inflammation irrespective of the cell labelling technique used. In high probability patients, imaging at 1 h can more reliably discriminate true from false positives and retain clinical usefulness. In low probability patients specificity remains unacceptable and 99mTc-labelled leucocyte scanning in these patients is of little value as a positive predictor of intestinal inflammation.

Adolescent

Blood and protein loss via small-intestinal inflammation induced by non-steroidal anti-inflammatory drugs.

Nearly three-quarters of patients on long-term treatment with non-steroidal anti-inflammatory drugs (NSAIDs) have small-intestinal inflammation, the consequences of which are largely unknown. Two potentially important complications, blood and protein loss from the small intestine, have been studied. 49 patients on NSAIDs underwent study with an indium-111 labelled leucocyte technique which localises and measures intestinal inflammation. 32 patients underwent simultaneous study with technetium-99m labelled red blood cells (RBC), which showed identical sites of localisation to 111In-leucocytes in 19. Intestinal blood loss was measured in 8 patients by use of chromium-51 labelled RBC, and a significant correlation between blood loss and intestinal inflammation was found. Intestinal protein loss was assessed in 9 patients with 51Cr-labelled proteins; patients with NSAID-induced small-intestinal inflammation were found to have a protein-losing enteropathy. These studies show that small intestinal inflammation caused by NSAIDs is associated with blood and protein loss, both of which may contribute to the general ill-health of rheumatic patients.

Anti-Inflammatory Agents, Non-Steroidal

Nonsteroidal antiinflammatory drug-induced intestinal inflammation in humans.

This study examines the effects of nonsteroidal antiinflammatory drugs on the small intestine in humans. Using an 111In-leukocyte technique in patients with rheumatoid arthritis (n = 90) and osteoarthritis (n = 7), it appears that nonsteroidal antiinflammatory drugs cause small intestinal inflammation in two-thirds of patients on long-term treatment and on discontinuation, the inflammation may persist for up to 16 mo. The prevalence and magnitude of the intestinal inflammation was unrelated to the type and dose of nonsteroidal drugs and previous or concomitant second-line drug treatment. There was a significant inverse correlation (r = -0.29, p less than 0.05) between fecal 111In excretion and hemoglobin levels in patients treated with nonsteroidal antiinflammatory drugs. The kinetics of fecal indium 111 excretion in patients treated with nonsteroidal antiinflammatory drugs was almost identical to that of patients with small bowel Crohn's disease. Eighteen patients on nonsteroidal antiinflammatory drugs underwent a radiologic examination of the small bowel and 3 were found to have asymptomatic ileal disease with ulceration and strictures. Nineteen patients on nonsteroidal antiinflammatory drugs, 20 healthy controls, and 13 patients with Crohn's ileitis underwent a dual radioisotopic ileal function test with tauro 23 (75Se) selena-25-homocholic acid and cobalt 58-labeled cyanocobalamine. On day 4, more than half of the patients with rheumatoid arthritis had evidence of bile acid malabsorption, but the ileal dysfunction was much milder than seen in patients with Crohn's ileitis.

Adolescent

The pathogenesis and consequence of non steroidal anti-inflammatory drug induced small intestinal inflammation in man.

Non steroidal anti-inflammatory drugs (NSAID's) have recently been shown to cause small intestinal inflammation in the majority of patients receiving these on a regular basis for more than one year. The development of inflammation is preceded by an NSAID effect to increase small intestinal permeability. Increased intestinal permeability is shown to be related to drug potency to inhibit cyclooxygenase and the effect is systemically mediated rather than a local irritant one. More recently, increased intestinal permeability due to NSAID's has been reduced by concomitant prostaglandin administration, showing that prostaglandins are essential for maintaining intestinal integrity in man. It is proposed that altered intestinal permeability allows the mucosa to be exposed to bacterial degradation products or other toxins and together with reduced chemotaxic response and altered neutrophil function due to NSAID's, this series of events leads to bacterial invasion of the mucosa which is evident by the techniques of 111Indium leucocyte scans and faecal collections. The consequence of such inflammation is that it may explain intestinal perforations and strictures which are occasionally seen in subjects on NSAID's. Most patients with NSAID-induced small intestinal inflammation may be bleeding from the intestine, loosing protein and some have ileal dysfunction. The small intestine may be a greater source of morbidity than the stomach, in patients receiving NSAID's.

Anti-Inflammatory Agents, Non-Steroidal

RADX protects against intestinal inflammation by restraining IFI16-mediated innate immunity.

Genomic instability is increased in patients with inflammatory bowel disease (IBD), yet whether it contributes directly to disease pathogenesis remains unclear. Here, we identify RADX, a structural antagonist to RAD51 and a key regulator of replication fork stability, as a critical suppressor of intestinal inflammation by limiting innate immune sensing of replication-associated DNA damage. RADX deficiency exacerbates experimental colitis, with macrophages serving as the principal mediators of this phenotype. Mechanistically, RADX competes with the DNA sensor IFI16 for binding to single-stranded DNA (ssDNA). Loss of RADX promotes ssDNA accumulation, triggering IFI16-dependent activation of NF-κB signaling and inflammasome assembly, thereby driving intestinal inflammation. Consistent with these findings, two RADX variants identified in patients with IBD associate with reduced RADX protein expression, increased DNA damage signaling, and elevated IL-1β levels. Pharmacological inhibition of RAD51 with RI-1 alleviated colitis in both wild-type and Radx-deficient mice. Together, these findings establish a mechanistic link between genome instability and intestinal inflammation, identify a RADX-IFI16 checkpoint that restrains pathogenic innate immune activation, and nominate modulation of replication stress as a therapeutic strategy for IBD.

Animals

Can sonography diagnose acute colonic diverticulitis in patients with acute intestinal inflammation? A prospective study.

In a prospective study of 123 patients with clinical signs of acute intestinal inflammation, the sensitivity of ultrasonography in diagnosing acute colonic diverticulitis was 84.6% and the specificity 80.3%. The predictive value of a positive and a negative sonogram was 76.0% and 87.7%, respectively. Of the 52 patients with subsequently proven acute colonic diverticulitis, 44 presented sonographically with a thickened (greater than 4 mm) hypoechoic bowel wall. In 15 patients, enlarged fluid-filled bowel loops were also present. Air-containing diverticula were demonstrated in 3 patients, abscesses in 8 patients, and colovesical fistulae in 2 patients. Eight large abscesses were successfully treated without emergency surgery by percutaneous sonographically guided evacuation. The described sonographic abnormalities strongly suggest acute colonic diverticulitis, particularly when localized in the left lower abdomen.

Acute Disease

Histopathology of intestinal inflammation related to reactive arthritis.

This study has identified a group of patients with inflammatory chronic, or relapsing acute arthritis who even in the absence of gastrointestinal symptoms have histological evidence of ileocolitis. At colonoscopy simultaneous biopsies of the terminal ileum and colon were taken from 108 patients with reactive arthritis (n = 55) or ankylosing spondylitis (n = 53), 47 patients with other rheumatic diseases and 19 control patients suffering from colonic polyps, adenocarcinoma, or chronic constipation. All control patients and all but one patient with rheumatoid arthritis, juvenile chronic arthritis, systemic lupus erythematosus, lumbar back ache, and psoriatic arthritis did not have histological evidence of acute or chronic inflammatory bowel disease. In contrast, in 30 of 35 (56.6%) patients with ankylosing spondylitis, and in 37 of 55 (67%) patients with reactive arthritis, regardless of HLA B27 phenotype, there was histological evidence of inflammatory bowel disease with features either of acute enterocolitis, or early Crohn's disease. Only 18 of 67 (27%) of the patients with histological gut inflammation, however, had intestinal symptoms.

Adolescent

Epithelial proliferation in response to gastrointestinal inflammation.

Intestinal inflammation seems invariably to be associated with increased epithelial proliferation. In the small bowel the pathological consequences of this area an increase in the crypt proliferative compartment and a decrease in the absorptive villus compartment, which can lead to malabsorption. In the colon, it is more difficult to examine changes in cell proliferation, but using Ki67, epithelial proliferation has been shown to be increased in ulcerative colitis and parasitic infection. The teleological advantage of increasing epithelial proliferation during intestinal inflammation is presumably in an effort to get rid of parasitized or infected epithelial cells, or to rapidly replace cells which have been lost. Rejection of helminth parasites from rodent small bowel is associated with partial villous atrophy and crypt hypertrophy, which is probably part of the host response making the mucosa inhospitable to the parasites. The short-term nutritional disadvantage of malabsorption is outweighed by the long-term advantage of being parasite-free. However, when the intestinal inflammation is elicited by a dietary constituent, the consequences are only pathological. At the moment there is no information as to the mechanisms by which inflammatory cells alter mucosal morphology and epithelial renewal. The restructuring of mucosal morphology in the flat-mucosa involves considerable adaptation of the connective tissue elements of the lamina propria. Whether this occurs in response to changes in epithelial renewal is not known. Finally, it is clear that activated T cells in the lamina propria can produce a flat-mucosa. In diseases such as Trichuris dysentery and ulcerative colitis there is no or very little T cell activation, even though epithelial proliferation is increased. Increased epithelial proliferation therefore may occur in response to different inflammatory stimuli.

Animals

Plasma kinin-precursor levels in clinical intestinal inflammation.

Plasma kinin-precursor (kininogen) concentrations were measured in the peripheral venous blood of 7 untreated patients with inflammatory bowel diseases, 12 healthy subjects, and 5 uncomplicated fracture cases. The mean plasma kininogen levels were significantly raised (P less than 0.025) in patients with intestinal inflammation (7.0 +/- 1.0 micrograms BK Eq/ml), as compared with the value found in healthy subjects (5.7 +/- 0.7 micrograms BK Eq/ml), and in fracture cases (5.0 +/- 1.2 micrograms BK Eq/ml). The packed cell volume did not differ (P greater than 0.05) between patients and control groups. Thus, the raised plasma kininogen levels observed in patients were not the result of nonspecific changes in plasma volume. It is suggested that raised plasma kininogen might be due to increased synthesis to provide substrate for excessive kinin-formation, to a potent inflammatory agent, or to high synthesis of acute-phase reactants. The possible significance of this observation is discussed.

Acute-Phase Reaction

UHRF1 deficiency exacerbates intestinal inflammation by epigenetic modulation of NPY1R gene methylation.

Epigenetic modifications play a crucial role in the pathogenesis of inflammatory bowel disease (IBD) by mediating gene-environment interactions. We previously showed that UHRF1, a central regulator of DNA methylation, contributes to cancer progression; however, its function in IBD remains poorly understood. Here, we revealed that UHRF1 was frequently reduced in inflamed tissues of patients with IBD and that its deficiency exacerbated intestinal epithelial cell (IEC) damage. Through a multilevel approach incorporating human cell models and an intestinal epithelial-specific Uhrf1-KO mouse model, we established UHRF1 as a key mitigator of IBD progression. Mechanistically, UHRF1 bound to the NPY1R promoter, promoted its methylation, and led to transcriptional suppression. The NPY1R upregulation resulting from UHRF1 deficiency attenuated cAMP/PKA/CREB signaling in IECs, thereby enhancing NF-κB activation and subsequent proinflammatory responses, which compromised intestinal epithelial barrier integrity. Furthermore, we identified miR-141 as a negative regulator of NPY1R, highlighting its potential as a therapeutic agent. Collectively, our results identified the UHRF1/NPY1R regulatory axis as a critical epigenetic mechanism in intestinal inflammation and underscored its dual promise for IBD diagnostics and therapy.

Animals

An inflammatory bowel disease-linked lncRNA suppresses transcription factor T-BET expression in T cells to limit intestinal inflammation.

Among the tens of thousands of annotated long noncoding RNAs (lncRNAs) in the human genome, only a small fraction have been functionally characterized. Here, we show that a well-established inflammatory bowel disease (IBD) risk locus encoded a conserved lncRNA, lnc15 (2310015A10Rik/ENSMUSG00000097729), whose structure was destabilized by risk-associated variants, leading to its degradation. Deletion of lnc15 in mice resulted in molecular features of inflammation under steady-state conditions and conferred heightened susceptibility to experimental colitis. Lnc15 was abundantly expressed in T cells, with highest expression in regulatory T (Treg) cells. Mechanistically, lnc15 suppressed the transcription factor T-BET by recruiting the CCR4-NOT RNA degradation complex to Tbx21 mRNA. Our study identifies that lnc15 simultaneously enhances Treg cell suppressive function and impairs conventional T cell pathogenicity in the context of intestinal inflammation. Collectively, these findings identify lnc15 as a functional lncRNA that links noncoding genetic variation to immune regulation and prevention of mucosal inflammation. VIDEO ABSTRACT.

RNA, Long Noncoding

Metronidazole reduces intestinal inflammation and blood loss in non-steroidal anti-inflammatory drug induced enteropathy.

This study assessed the effect of metronidazole on the gastroduodenal mucosa, intestinal permeability, blood loss, and inflammation in patients on non-steroidal anti-inflammatory drugs (NSAIDs). Thirteen patients were studied before and after 2-12 weeks' treatment with metronidazole 800 mg/day, while maintaining an unchanged NSAID intake. Intestinal inflammation, as assessed by the faecal excretion of indium-111 labelled neutrophils, and blood loss, assessed with chromium-51 labelled red cells, were significantly reduced after treatment (mean (SD) 111In excretion 4.7 (4.7)% v 1.5 (1.3)% (N < 1.0%), p < 0.001, 51Cr red cells loss 2.6 (1.6) ml/day v 0.9 (0.5) ml/day (N < 1.0 ml/day), p < 0.01). Intestinal permeability assessed as the 5 hour urinary excretion ratio of 51CrEDTA/L-rhamnose did not change significantly (0.133 (0.046) v 0.154 (0.064), p > 0.1) and there were no significant changes in the endoscopic or microscopic appearances of the gastroduodenal mucosa. These results suggest that the neutrophil is the main damaging effector cell in NSAID induced enteropathy. The main neutrophil chemo-attractant in this enteropathy may be a metronidazole sensitive microbe.

Aged

Congenital diarrhea with intestinal inflammation and epithelial immaturity.

We report an interesting case of congenital inflammatory bowel disease and intestinal epithelial immaturity that presented as secretory diarrhea. No infectious, metabolic, or anatomical basis for these findings was identified. As differentiated from previous reports of neonatal enteropathies, this infant demonstrated involvement of both the small and large intestine with histopathologic findings of acute and chronic inflammation, extensive submucosal fibrosis, and "flat" small intestine mucosa. In addition, this patient had a polyamine deficiency (a primary or secondary phenomenon), which may have contributed to delayed epithelial maturation. These findings suggest that the inflammatory bowel disease and altered epithelial maturation contributed to a fatal intractable diarrhea.

Diarrhea, Infantile

[Chronic nonspecific intestinal inflammations in older patients and their surgical treatment].

The author describes his experience with the treatment of chronic non-specific inflammations of the small and large intestine in elderly patients. They are difficult to diagnose as they are less frequent at that age. They are operated late, only when there are already serious complications (peritonitis, toxic megacolon, intractable haemorrhage and septicaemia) and the mortality is high. The author recommends therefore to pay more attention to this condition in advanced age groups.

Age Factors