Harnessing murine models of Crohn's disease ileitis to advance concepts of pathophysiology and treatment.

Crohn's disease (CD) and ulcerative colitis (UC) are both characterized by chronic inflammation and severe dysfunction of the gastrointestinal tract. These two forms of inflammatory bowel disease (IBD) represent distinct clinical disorders with diverse driving mechanisms; however, this divergence is not reflected in currently approved therapeutics that commonly target general proinflammatory pathways. A compelling need therefore remains to understand factors that differentiate the topology and the distinct clinical manifestations of CD versus UC, in order to develop more effective and specialized therapies. Animal models provide valuable platforms for studying IBD heterogeneity and deciphering disease-specific mechanisms. Both the established and the newly developed ileitis mouse models are characterized by various disease initiating mechanisms and diverse phenotypic outcomes that reflect the complexity of human CD-ileitis. Microbial dysbiosis, destruction of epithelial barrier integrity, immune cell deregulation, as well as the recently described genome instability and stromal cell activation have all been proposed as the triggering factors for the development of ileitis-associated pathology. In this review, we aim to critically evaluate the mechanistic underpinnings of murine models of CD-ileitis, discuss their phenotypic similarities to human disease, and envisage their further exploitation for the development of novel targeted and personalized therapeutics.

Short- and Long-term Outcomes Following Side-to-side Strictureplasty and its Modification Over the Ileocaecal Valve for Extensive Crohn's Ileitis.

BACKGROUND AND AIMS: Postoperative recurrence remains a challenging problem in patients with Crohn's disease [CD]. To avoid development of short bowel syndrome, strictureplasty techniques have therefore been proposed. We evaluated short- and long-term outcomes of atypical strictureplasties in CD patients with extensive bowel involvement. METHODS: Side-to-side isoperistaltic strictureplasty [SSIS] was performed according to the Michelassi technique or modification of this over the ileocaecal valve [mSSIS]. Ninety-day postoperative morbidity was assessed using the comprehensive complication index [CCI]. Clinical recurrence was defined as symptomatic, endoscopically or radiologically confirmed, stricture/inflammatory lesion requiring medical treatment or surgery. Surgical recurrence was defined as the need for any surgical intervention. Endoscopic remission was defined as ≤i1, according to the modified Rutgeerts score. Deep remission was defined as the combination of endoscopic remission and absence of clinical symptoms. Perioperative factors related to clinical recurrence were evaluated. RESULTS: A total of 52 CD patients [SSIS n = 12; mSSIS n = 40] were included. No mortality occurred. Mean CCI was 10.3 [range 0-33.7]. Median follow-up was 5.9 years [range 0.8-9.9]. Clinical recurrence [19 patients] was 29.7% and 39.6% after 3 and 5 years, respectively. Surgical recurrence [seven patients] was 2% and 14.1% after 3 and 5 years, respectively. At the end of the follow-up, 92% of patients kept the original strictureplasty and deep remission was observed in 25.7% of the mSSIS patients. None of the perioperative variables considered showed a significant association with clinical recurrence. CONCLUSIONS: SSIS is safe, effective, and provides durable disease control in patients with extensive CD ileitis.

Late-onset Crohn's disease: a comparison of disease behaviour and therapy with younger adult patients: the Italian Group for the Study of Inflammatory Bowel Disease 'AGED' study.

BACKGROUND: Disease phenotype and outcome of late-onset Crohn's disease are still poorly defined. METHODS: In this Italian nationwide multicentre retrospective study, patients diagnosed ≥65 years (late-onset) were compared with young adult-onset with 16-39 years and adult-onset Crohn's disease 40-64 years. Data were collected for 3 years following diagnosis. RESULTS: A total of 631 patients (late-onset 153, adult-onset 161, young adult-onset 317) were included. Colonic disease was more frequent in late-onset (P < 0005), stenosing behaviour was more frequent than in adult-onset (P < 0003), but fistulising disease was uncommon. Surgery rates were not different between the three age groups. Systemic steroids were prescribed more frequently in young adult-onset in the first year, but low bioavailability steroids were used more frequently in late-onset in the first 2 years after diagnosis (P < 0.036, P < 0.041, respectively). The use of immunomodulators and anti-TNF's even in patients with more complicated disease, that is, B2 or B3 behaviour (Montreal classification), remained significantly inferior (P < 0.0001) in late-onset compared to young adult-onset. Age at diagnosis, Charlson comorbidity index, and steroid used in the first year were negatively associated with the use of immunomodulators and biologics. Comorbidities, related medications and hospitalizations were more frequent in late-onset. Polypharmacy was present in 56% of elderly Crohn's disease patients. CONCLUSION: Thirty-two percent of late-onset Crohn's disease presented with complicated disease behaviour. Despite a comparable use of steroids and surgery, immunomodulators and biologics were used in a small number of patients.

Should We Divide Crohn's Disease Into Ileum-Dominant and Isolated Colonic Diseases?

Crohn's disease (CD) is an inflammatory bowel disease that can involve any region of the gastrointestinal tract. First described in 1932 as terminal ileitis or regional enteritis, it predominately involves the ileum with or without colonic involvement. Isolated colonic CD was first described in 1960 and since then the phenotypic classification of CD has evolved to stratify patients into isolated ileal, ileocolonic, or isolated colonic involvement. In the current review we evaluate the published literature regarding differences in epidemiology, natural history, pathogenesis, response to therapy, and disease monitoring, when stratified by disease location. Based on the available evidence consideration could be given to a new classification for CD, which splits it into ileum dominant (isolated ileal and ileocolonic) and isolated colonic disease. This may allow for a more optimized approach to clinical care and scientific research for CD.

Chronic Kidney Disease Elicits an Intestinal Inflammation Resulting in Intestinal Dysmotility Associated with the Activation of Inducible Nitric Oxide Synthesis in Rat.

This study was conducted to investigate whether chronic kidney disease (CKD) affects intestinal inflammation and intestinal motility and the underlying mechanisms. Rats were randomized into control group and uremic group. Uremia rats were induced by the 5/6 kidney resection, while the control went through the same procedures but without any kidney resection. Intestinal motility was assessed by charcoal transport assay; intestinal inflammation was assessed by analyses of levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10 in the ileum tissue. The inducible nitric oxide synthesis (iNOS) activity was assessed in the ileum tissue. The results showed that the intestinal motility in uremic group was significantly decreased compared with that in the control group on postoperative weeks 8 and 10. Meanwhile, the uremic group presented significantly higher concentrations of TNF-α, IL-6, and IL-10 than control group on postoperative weeks 8 and/or 10, and higher gene expression on postoperative weeks 6, 8, and 10. Furthermore, the intestinal iNOS activity in the uremic group was significantly increased compared with that in control group on postoperative weeks 8 and 10. These results suggest that CKD could induce intestinal inflammation and lead to intestinal dysmotility, which may be associated with iNOS activation in the intestine.

Case report of a pair of siblings with cryptogenic multifocal ulcerating stenosing enteritis: A rare disease easily to be misdiagnosed as Crohn disease.

RATIONALE: The rare disease cryptogenic multifocal ulcerous stenosing enteritis (CMUSE) is characterized by multiple and recurring small intestinal ulcers with stenosis of unknown causes. In clinic, it is difficult to be differentiated from the inflammatory bowel disease, especially the Crohn disease. PATIENT CONCERNS: Here we report a pair of siblings who suffered from long-time anemia and abdominal pain and misdiagnosed with inflammatory bowel disease (IBD) for many years. DIAGNOSES: They were finally diagnosed with CMUSE with intestinal obstruction. INTERVENTIONS AND OUTCOMES: They both accepted surgical treatment and recovered well. No abdominal symptom appeared in the two-year follow-up. LESSONS: This report underscores that CMUSE patients may have a long course of suffering from anemia and abdominal pain, normal inflammatory markers and normal colon, and sometimes have a family history of CMUSE. Surgery of segmental bowel resection is a good way to solve intractable intestinal obstruction in CMUSE.

A prospective 12-week mucosal healing assessment of small bowel Crohn's disease as detected by capsule endoscopy.

BACKGROUND: Mucosal healing is increasingly recognized as an important treatment goal in Crohn's disease (CD). Data from colonic disease shows improved long-term outcomes in patients achieving complete mucosal healing. Little is currently known of this with respect to ileitis, which is increasingly diagnosed using small bowel capsule endoscopy. The study aimed to prospectively assess mucosal healing and deep remission rates in a cohort of symptomatic small bowel CD patients commencing biologic or immunomodulator therapy. METHODS: Baseline demographics, quality of life questionnaires and Harvey-Bradshaw index were collected along with C-reactive protein and calprotectin. Capsule endoscopy Crohn's disease activity (CECDAI) index was used to assess ileitis severity. All parameters were reassessed at week 12. Results at baseline and week 12 were compared using two-tailed Wilcoxon analysis, P value less than 0.05 was considered significant. RESULTS: In total, 43 patients of 71 screened underwent 80 small bowel capsule endoscopies. On the basis of the CECDAI, 39 (90%) demonstrated active small bowel CD at baseline with 37 (86%) undergoing 12-week assessment. Overall there was a statistically significant symptomatic and biochemical improvement at week 12. Furthermore, 10 (27%) had demonstrated a normalization in CECDAI (<3.5), which was statistically significant (P<0.0005, 95% confidence interval 0.12-0.15). However, no patient had achieved full mucosal healing. CONCLUSION: In patients with active small bowel CD early symptomatic and biochemical response to treatment is not mirrored by mucosal healing. Repeat mucosal healing assessment in this cohort is warranted following a longer duration of treatment to identify potential mucosal healing and deep remission rates.

Correlation between morphological expansion and impairment of intra- and prelesionary motility in inflammatory small bowel lesions in patients with Crohn's disease - preliminary data.

INTRODUCTION: The aim of this study is to investigate if alterations of intra- and prelesionary motility in inflamed small-bowel segments correlate with length, wall-thickness and prelesionary dilatation of inflammatory small bowel lesions in patients suffering from Crohn's disease assessed with MRI. METHODS AND MATERIALS: This retrospective IRB approved study included 25 patients (12 males, 18-77y) with inflammatory lesions examined using (MRE) magnetic resonance imaging enterography. Cine MRE was performed using a coronal 2D steady-state free precession sequence (TR 2.9, TE 1.25) on a 1.5T MRI scanner. Small bowel motility was examined using a dedicated MR-motility assessment software (Motasso, Vers. 1.0, Sohard AG, Bern, Switzerland). Motility patterns (contraction frequency, relative occlusion rate and mean diameter) were assessed in correlation to wall thickness, length and prelesionary dilatation of the lesions. Statistical analysis was performed by calculation of the Pearson's-Correlation coefficient. RESULTS: The length of the inflammatory segments, the wall thickening and prelesionary dilatation did not correlate with the frequency of the contractions (r=0.17, p=0.477; r=0.316, p=0.123; r=0.161, p=0.441) or the impairment of luminal occlusion (r=0.274, p=0.184; r=0.199, p=.0339; r=0.015, p=0.945) and only the prelesionary dilatation (r=0.410, p=0.042) correlated to the mean luminal diameter of the segment. CONCLUSION: The degree of motility impairment within inflammatory small bowel lesions does not significantly correlate with the extent of the lesion but with the motility measured in prelesionary, non-affected segments, suggesting an interdependent functional aspect of inflammation even in morphologically non-affected small bowel segments.

Loss of estrogen-mediated immunoprotection underlies female gender bias in experimental Crohn's-like ileitis.

The incidence and severity of Crohn's disease (CD) are increased in female patients. Using SAMP1/YitFc (SAMP) mice, a spontaneous model of chronic intestinal inflammation that displays histologic and pathogenic similarities to human CD, we investigated the potential mechanism(s) contributing to sex differences observed in CD. Similar to gender differences observed in CD patients, SAMP female (SAMP-F) mice displayed an earlier onset and more severe ileitis compared with SAMP male (SAMP-M) mice. Furthermore, T-regulatory cells (Tregs) from gut-associated lymphoid tissue (GALT) of SAMP-F mice were reduced in frequency and impaired in their in vitro and in vivo suppressive functions compared with that of SAMP-M mice. Given the interaction between sex hormones and Treg function, we investigated the possible role of estrogen (E2) in SAMP ileitis. SAMP-M mice responded to exogenous E2 administration by expanding Treg frequency and reducing ileal inflammation, whereas SAMP-F mice were resistant. Conventional T cells and Tregs responded differentially to estrogen signaling, leading to distinct immunoprotective effects mediated by distinct estrogen receptor (ER) isoforms. These mechanisms were impaired in T cells from SAMP-F mice. Thus, hormone signaling influences the expansion and function of GALT Tregs in an ER-dependent manner and contributes to gender-based differences in experimental CD.

Anti-IL-6 antibody treatment but not IL-6 knockout improves intestinal barrier function and reduces inflammation after binge ethanol exposure and burn injury.

Interleukin 6 (IL-6) is an inflammatory cytokine known to be elevated in chronic diseases and after insults such as trauma and infection. Although necessary for the development of B cells and Th17 cells, IL-6, at elevated levels, can also cause tissue damage and lead to a rise in inflammation. Previous work in our laboratory has shown that IL-6 is increased both systemically and in multiple organ systems including the ileum after ethanol exposure and burn injury. As this combined insult causes elevated intestinal morphological damage, tight junction protein localization alterations, and phosphorylated myosin light chain levels, we sought to determine the role of IL-6 in these intestinal responses using a model of binge ethanol exposure and burn injury. Interleukin 6 antibody treatment after the combined insult reduced morphological changes in the ileum, bacterial translocation, and phosphorylated myosin light chain levels relative to either injury alone. Zonula occludens protein 1 and occludin localization was also reestablished in wild-type mice given IL-6 antibody after ethanol and burn. Interleukin 6-knockout mice given ethanol and burn injury also had reduced intestinal damage; however, no changes in bacterial translocation or tight junction protein localization were observed as compared with similarly treated wild-type mice. These data suggest that IL-6 may have a role in intestinal tissue damage observed after the combined insult of binge ethanol exposure and burn injury, although complete loss of IL-6 does not seem to be beneficial in this model. Modulation of IL-6 may present a new option for preventing intestinal damage and associated inflammation after a combined insult of ethanol exposure and burn injury.

Innate dysfunction promotes linear growth failure in pediatric Crohn's disease and growth hormone resistance in murine ileitis.

BACKGROUND: Growth failure remains a common complication of pediatric Crohn's disease (CD) and has been associated with small bowel involvement and need for surgery. We have reported that patients with elevated (≥ 1.6 µg/mL) granulocyte macrophage colony stimulating factor autoantibodies (GM-CSF Ab) are more likely to experience complicated ileal disease requiring surgery. We hypothesized that concurrent GM-CSF Ab and CARD15 risk allele carriage (C15(+) GMAb(+) ) would be associated with growth failure in CD and growth hormone (GH) resistance in murine ileitis. METHODS: We enrolled 229 pediatric CD patients at two sites and determined CARD15 genotype, serum GM-CSF Ab, and GH binding protein (GHBP), and height (HTz) and weight (WTz) z-scores at diagnosis. Ileitis was induced in card15-deficient mice by GM-CSF neutralization and nonsteroidal antiinflammatory drug (NSAID) exposure. Hepatic GH receptor (GHR) abundance and GH-dependent Stat5 activation were determined by western blot and Igf-I mRNA expression by real-time polymerase chain reaction (PCR). RESULTS: Mean (95% confidence interval [CI]) HTz at diagnosis was reduced to -0.48 (-4.2, 2.3) in C15(+) GMAb(+) patients, compared to -0.07 (-4.9, 3.4) in disease controls (P ≤ 0.05). Circulating GHBP, as a marker for tissue GHR abundance, was reduced in C15(+) GMAb(+) patients. Hepatic GHR abundance, GH induction of Stat5 tyrosine phosphorylation, and Igf-I mRNA expression were reduced in male card15-deficient mice with ileitis due to GM-CSF neutralization and NSAID exposure. CONCLUSIONS: Innate dysfunction due to concurrent genetic variation in CARD15 and neutralizing GM-CSF Ab is associated with linear growth failure in pediatric CD, and hepatic GH resistance in murine ileitis.

Pathogenesis of gastritis in ileitis-prone SAMP1/Yit mice.

Inflammatory bowel disease is a chronic inflammatory disease of the gut which manifests as ulcerative colitis or Crohn's disease. One of the most studied animal models of spontaneous Crohn's disease is the senescence-accelerated mouse (SAMP1/Yit strain) model. In SAMP1/Yit mice, although many immunological responses are perturbed, some evidence suggests that the primary defect lies in the epithelial cell barrier. In the process of studying epithelial permeability, we observed that the stomach in SAMP1/Yit mice also had increased permeability. Upon further examination, these mice were shown to have marked, chronic gastritis with focal to diffuse aggregates of mononuclear cells of mixed lineages. These aggregates were located predominantly in the oxyntic mucosa, with occasional lesions in the forestomach but with relatively fewer cellular infiltrates in the antral mucosa. Real-time RT PCR showed an increase in several helper T cell (Th cell)-derived pro-inflammatory cytokines in the gastric mucosa of SAMP1/Yit mice. However, many of the cells in the aggregates of SAMP1/Yit mice were B cells. SAMP1/Yit B cells exacerbate ileitis when co-transferred into immunodeficient recipients. The gastritis also reflects a contribution by B cells. As SAMP1/Yit mice were derived from AKR mice, we examined AKR mice and determined that they too have an increased occurrence of gastritis, although they do not develop ileitis. B cells contributed to the gastric inflammation in these mice also. Thus, SAMP1/Yit mice display gastritis as well as ileitis, and B cells appear to play a role in the pathogenesis of inflammation at both sites. This review will discuss some of the mechanisms that may account for these different manifestations of gastrointestinal disease.

Inhibitory effects of bromelain, a cysteine protease derived from pineapple stem (Ananas comosus), on intestinal motility in mice.

BACKGROUND: Bromelain (BR) is a cysteine protease with inhibitory effects on intestinal secretion and inflammation. However, its effects on intestinal motility are largely unexplored. Thus, we investigated the effect of this plant-derived compound on intestinal contractility and transit in mice. METHODS: Contractility in vitro was evaluated by stimulating the mouse isolated ileum, in an organ bath, with acetylcholine, barium chloride, or electrical field stimulation. Motility in vivo was measured by evaluating the distribution of an orally administered fluorescent marker along the small intestine. Transit was also evaluated in pathophysiologic states induced by the pro-inflammatory compound croton oil or by the diabetogenic agent streptozotocin. KEY RESULTS: Bromelain inhibited the contractions induced by different spasmogenic compounds in the mouse ileum with similar potency. The antispasmodic effect was reduced or counteracted by the proteolytic enzyme inhibitor, gabexate (15 × 10(-6) mol L(-1) ), protease-activated receptor-2 (PAR-2) antagonist, N(1) -3-methylbutyryl-N(4) -6-aminohexanoyl-piperazine (10(-4) mol L(-1) ), phospholipase C (PLC) inhibitor, neomycin (3 × 10(-3) mol L(-1) ), and phosphodiesterase 4 (PDE4) inhibitor, rolipram (10(-6) mol L(-1) ). In vivo, BR preferentially inhibited motility in pathophysiologic states in a PAR-2-antagonist-sensitive manner. CONCLUSIONS & INFERENCES: Our data suggest that BR inhibits intestinal motility - preferentially in pathophysiologic conditions - with a mechanism possibly involving membrane PAR-2 and PLC and PDE4 as intracellular signals. Bromelain could be a lead compound for the development of new drugs, able to normalize the intestinal motility in inflammation and diabetes.

The critical role of the MyD88-dependent pathway in non-CNS MPTP-mediated toxicity.

A growing body of evidence supports a role of inflammation in the loss of central nervous system neurons both to acute and chronic insults, while its contribution to the loss of neurons in the enteric nervous system remains largely uninvestigated. We have addressed this issue by exploring the role of inflammation in dopaminergic (DAergic) myenteric neuronal degeneration secondary to MPTP lesioning in mice deficient in MyD88, a protein implicated in the cascade of events leading to the innate immune response. Our results show that MPTP-treated MyD88 knock out (MyD88(-/-)) mice were protected against the toxin-induced TH-immunoreactive neuronal degeneration at the level of the myenteric plexus of the distal ileum, which causes a 50% loss of such neurons in MPTP-treated WT mice. Interestingly, the density of macrophages was the same in the MyD88(-/-) mice subjected to MPTP, as opposed to the increase in density observed in wild-type (WT) mice treated with the toxin, which was due to an infiltration of monocyte from the blood to the myenteric tissue. Furthermore, in MPTP-treated MyD88(-/-) mice, resident macrophages exhibited a predominant pro-repair phenotype, which could have contributed to the protection of DAergic neurons in the myenteric plexus. Taken together, our results suggest a critical role for the MyD88-dependent pathway in the gastrointestinal DAergic degeneration induced by MPTP.

Paneth's disease.

In about 70% of patients Crohn's disease (CD) affects the small intestine. This disease location is stable over time and associated with a genetic background different from isolated colonic disease. A characteristic feature of small intestinal host defense is the presence of Paneth cells at the bottom of the crypts of Lieberkühn. These cells produce different broad spectrum antimicrobial peptides (AMPs) most abundantly the α-defensins HD-5 and -6 (DEFA5 und DEFA6). In small intestinal Crohn's disease both these PC products are specifically reduced. As a functional consequence, ileal extracts from Crohn's disease patients are compromised in clearing bacteria and enteroadherent E. coli colonize the mucosa. Mechanisms for defective antimicrobial Paneth cell function are complex and include an association with a NOD2 loss of function mutation, a disturbance of the Wnt pathway transcription factor TCF7L2 (also known as TCF4), the autophagy factor ATG16L1, the endosomal stress protein XBP1, the toll-like receptor TLR9, the calcium mediated potassium channel KCNN4 as well as mutations or inactivation of HD5. Thus we conclude that small intestinal Crohn's disease is most likely a complex disease of the Paneth cell: Paneth's disease.

Slow synaptic transmission in myenteric AH neurons from the inflamed guinea pig ileum.

We investigated the effect of inflammation on slow synaptic transmission in myenteric neurons in the guinea pig ileum. Inflammation was induced by the intraluminal injection of trinitrobenzene sulfonate, and tissues were taken for in vitro investigation 6-7 days later. Brief tetanic stimulation of synaptic inputs (20 Hz, 1 s) induced slow excitatory postsynaptic potentials (EPSPs) in 49% and maintained postsynaptic excitation that lasted from 27 min to 3 h in 13% of neurons from the inflamed ileum. These neurons were classified electrophysiologically as AH neurons; 10 were morphological type II neurons, and one was type I. Such long-term hyperexcitability after a brief stimulus is not encountered in enteric neurons of normal intestine. Electrophysiological properties of neurons with maintained postsynaptic excitation were similar to those of neurons with slow EPSPs. Another form of prolonged excitation, sustained slow postsynaptic excitation (SSPE), induced by 1-Hz, 4-min stimulation, in type II neurons from the inflamed ileum reached its peak earlier but had lower amplitude than that in control. Unlike slow EPSPs and similar to SSPEs, maintained excitation was not inhibited by neurokinin-1 or neurokinin-3 receptor antagonists. Maintained postsynaptic excitation was not influenced by PKC inhibitors, but the PKA inhibitor, H-89, caused further increase in neuronal excitability. In conclusion, maintained excitation, observed only in neurons from the inflamed ileum, may contribute to the dysmotility, pain, and discomfort associated with intestinal inflammation.

Overexpression of interleukin-23, but not interleukin-17, as an immunologic signature of subclinical intestinal inflammation in ankylosing spondylitis.

OBJECTIVE: Subclinical gut inflammation is common in spondylarthritis, but the immunologic abnormalities underlying this process are undefined. Perturbation of the interleukin-23 (IL-23)/Th17 axis has emerged as a fundamental trigger of chronic inflammation. This study was undertaken to investigate the expression and tissue distribution of IL-23/Th17-related molecules in Crohn's disease (CD) and in subclinical gut inflammation in ankylosing spondylitis (AS). METHODS: Quantitative gene expression analysis of Th1/Th2 and IL-23/Th17 responses was performed in intestinal biopsy samples obtained from 12 patients with CD, 15 patients with AS, and 13 controls. IL-23 tissue distribution and identification of IL-23-producing cells were evaluated by immunohistochemistry. RESULTS: We demonstrated a strong and significant up-regulation of IL-23p19 transcripts in the terminal ileum in patients with AS and patients with CD. IL-23 was abundantly produced by infiltrating monocyte-like cells in inflamed mucosa from AS and CD patients. Notably, we also identified Paneth cells as a major source of IL-23 in patients with AS, patients with CD, and normal controls. Unlike CD, in AS patients, IL-23 was not associated with up-regulation of IL-17 and the IL-17-inducing cytokines IL-6 and IL-1beta. Finally, while the Th1-related cytokines interferon-gamma, IL-12p35, and IL-27p28 were overexpressed only in CD patients, IL-4, IL-5, and STAT-6 were also significantly increased in AS patients. CONCLUSION: Our findings indicate that overexpression of IL-23, but not IL-17, is a pivotal feature of subclinical gut inflammation in AS. Identification of resident Paneth cells as a pivotal source of IL-23 in physiologic and pathologic conditions strongly suggests that IL-23 is a master regulator of gut mucosal immunity, providing a pathophysiologic significance to the reported association between IL-23 receptor polymorphisms and intestinal inflammation.

Intestinal barrier function in response to abundant or depleted mucosal glutathione in Salmonella-infected rats.

BACKGROUND: Glutathione, the main antioxidant of intestinal epithelial cells, is suggested to play an important role in gut barrier function and prevention of inflammation-related oxidative damage as induced by acute bacterial infection. Most studies on intestinal glutathione focus on oxidative stress reduction without considering functional disease outcome. Our aim was to determine whether depletion or maintenance of intestinal glutathione changes susceptibility of rats to Salmonella infection and associated inflammation.Rats were fed a control diet or the same diet supplemented with buthionine sulfoximine (BSO; glutathione depletion) or cystine (glutathione maintenance). Inert chromium ethylenediamine-tetraacetic acid (CrEDTA) was added to the diets to quantify intestinal permeability. At day 4 after oral gavage with Salmonella enteritidis (or saline for non-infected controls), Salmonella translocation was determined by culturing extra-intestinal organs. Liver and ileal mucosa were collected for analyses of glutathione, inflammation markers and oxidative damage. Faeces was collected to quantify diarrhoea. RESULTS: Glutathione depletion aggravated ileal inflammation after infection as indicated by increased levels of mucosal myeloperoxidase and interleukin-1beta. Remarkably, intestinal permeability and Salmonella translocation were not increased. Cystine supplementation maintained glutathione in the intestinal mucosa but inflammation and oxidative damage were not diminished. Nevertheless, cystine reduced intestinal permeability and Salmonella translocation. CONCLUSION: Despite increased infection-induced mucosal inflammation upon glutathione depletion, this tripeptide does not play a role in intestinal permeability, bacterial translocation and diarrhoea. On the other hand, cystine enhances gut barrier function by a mechanism unlikely to be related to glutathione.

Bovine glycomacropeptide ameliorates experimental rat ileitis by mechanisms involving downregulation of interleukin 17.

BACKGROUND AND PURPOSE: Bovine glycomacropeptide (BGMP) is an inexpensive, non-toxic milk peptide with anti-inflammatory effects in rat experimental colitis but its mechanism of action is unclear. It is also unknown whether BGMP can ameliorate inflammation in proximal regions of the intestine. Our aim was therefore two-fold: first, to determine the anti-inflammatory activity of BGMP in the ileum; second, to characterise its mechanism of action. EXPERIMENTAL APPROACH: We used a model of ileitis induced by trinitrobenzenesulphonic acid in rats. Rats were treated orally with BGMP and its efficacy compared with that of oral 5-aminosalicylic acid or vehicle, starting 2 days before ileitis induction. KEY RESULTS: BGMP pretreatment (500 mg kg(-1) day(-1)) resulted in marked reduction of inflammatory injury, as assessed by lower extension of necrosis and damage score, myeloperoxidase, alkaline phosphatase, inducible nitric oxide synthase, interleukin 1beta, tumour necrosis factor and interleukin 17. These effects were generally comparable to those of 5-aminosalicylic acid (200 mg kg(-1) day(-1)). Neither compound affected the production of interferon gamma, tumour necrosis factor and interleukin 2 by mesenteric lymph node cells isolated from animals with ileitis. The expression of Foxp3 was increased in ileitis and not reduced significantly by BGMP or aminosalicylate treatment. CONCLUSIONS AND IMPLICATIONS: These results demonstrate that BGMP has anti-inflammatory activity in the ileum with similar efficacy to 5-aminosalicylic acid. The mechanism of action may involve Th17 and regulatory T cells and perhaps macrophages but probably not Th1 lymphocytes. Patients with Crohn's ileitis may benefit from treatment with BGMP.