Sulfonic Acid Colitis Research Articles

Overexpression of ATP-activated P2X7 Receptors in the Intestinal Mucosa Is Implicated in the Pathogenesis of Crohnʼs Disease

Extracellular nucleotides released in conditions of cell stress alert the immune system from tissue injury or inflammation. We hypothesized that the P2X7 receptor (P2X7-R) could regulate key elements in inflammatory bowel disease pathogenesis. Colonoscopy samples obtained from patients with Crohn's disease (CD), ulcerative colitis, and controls were used to analyze P2X7-R expression by RT and real-time PCR, immunohistochemistry, and confocal microscopy. Inflammatory response was determined by the levels of cytokines by enzyme-linked immunosorbent assay in cultures of intestinal explants. Apoptosis was determined by the TUNEL assay. P2X7-R C57BL/6 mice were treated with trinitrobenzene sulfonic acid or dextran sulfate sodium (DSS) for inducing colitis. P2X7-R was expressed in higher levels in inflamed CD epithelium and lamina propria, where it colocalizes more with dendritic cells and macrophages. Basal levels of P2X7-R mRNA were higher in CD inflamed mucosa compared with noninflamed CD and controls and were upregulated after interferon-γ in controls. Apoptotic rates were higher in CD epithelium and lamina propria compared with ulcerative colitis and controls. Levels of tumor necrosis factor-α, interleukin (IL)-1β, and IL-17 were higher, whereas IL-10 was lower in CD compared with controls. Levels of tumor necrosis factor-α-α and interleukin-1β increased after adenosine-triphosphate and decreased after KN62 treatment in CD. P2X7-R animals did not develop trinitrobenzene sulfonic acid or DSS colitis. The upregulation of P2X7-R in CD inflamed mucosa is consistent with the involvement of purinoceptors in inflammation and apoptosis. These observations may implicate purinergic signaling in the pathogenesis of intestinal inflammation, and the P2X7-R may represent a novel therapeutic target in CD.

Role of metallothioneins as danger signals in the pathogenesis of colitis

Inflammatory bowel diseases (IBDs) are recurrent intestinal pathologies characterized by a compromised epithelial barrier and an exaggerated immune activation. Mediators of immune cell infiltration may represent new therapeutic opportunities. Metallothioneins (MTs) are stress-responsive proteins with immune-modulating functions. Metallothioneins have been linked to IBDs, but their role in intestinal inflammation is inconclusive. We investigated MT expression in colonic biopsies from IBDs and acute infectious colitis patients and healthy controls and evaluated MT's role in experimental colitis using MT knockout mice and anti-MT antibodies. Antibody potential to target extracellular MT and its mechanism was tested in vitro. Biopsies of patients with active colitis showed infiltration of MT-positive cells in a pattern that correlated with the grade of inflammation. MT knockout mice displayed less severe acute dextran sulphate sodium (DSS)-induced colitis compared to congenic wild-type mice based on survival, weight loss, colon length, histological inflammation and leukocyte infiltration. Chronic DSS-colitis confirmed that Mt1 and Mt2 gene disruption enhances clinical outcome. Blockade of extracellular MT with antibodies reduced F4/80-positive macrophage infiltration in DSS- and trinitrobenzene sulphonic acid-colitis, with a tendency towards a better outcome. Whole-body single-photon emission computer tomography of mice injected with radioactive anti-MT antibodies showed antibody accumulation in the colon during colitis and clearance during recovery. Necrotic and not apoptotic cell death resulted in western blot MT detection in HT29 cell supernatant. In a Boyden chamber migration assay, leukocyte attraction towards the necrotic cell supernatant could be abolished with anti-MT antibody, indicating the chemotactic potential of endogenous released MT. Our results show that human colitis is associated with infiltration of MT-positive inflammatory cells. Since antibody blockade of extracellular MT can reduce colitis in mice, MT may act as a danger signal and may represent a novel target for reducing leukocyte infiltration and inflammation in IBD patients.

N‐(3′, 4′‐dimethoxycinnamonyl) anthranilic acid alleviated experimental colitis by inhibiting autoimmune response and inducing CD4+CD25+ regulatory T cells production

Crohn's disease treatments available today are not quite satisfactory. N-(3', 4'-dimethoxycinnamonyl) anthranilic acid (3, 4-DAA) has been proved to be effective in many autoimmune diseases. Therefore, we investigated the immunologic function of 3, 4-DAA on trinitrobenzene sulfonic acid (TNBS) colitis and human Crohn's disease. Mice with TNBS-induced colitis were treated with 3, 4-DAA or 1-methyl-tryptophan (1-MT). Colitis severity was assessed with clinical and histological scores. Cell proliferation, cytokine expression, and the percentage of CD4(+) CD25(+) T cells were measured in both mice and human samples. In mice treated with 3, 4-DAA, the clinical and histological scores were decreased (P < 0.05); the proliferation of mesenteric lymph nodes (MLNs) cells and lamina propria mononuclear cells (LPMCs) were inhibited (P < 0.05); Th1 cytokine expressions were decreased (P < 0.05), and Th2 cytokine levels were increased (P < 0.05). 3, 4-DAA also induced CD4(+) CD25(+) T cells expression (5.88 ± 2.1 vs 11.03 ± 2.93, P < 0.05) in mice MLNs. Transfer of these cells into TNBS colitis mice resulted in the reduction of the disease activity index (DAI) and histological scores. In LPMCs isolated from human Crohn's disease, 3, 4-DAA had the same effect. It can inhibit the cell proliferation, decrease Th1 cytokine expressions (P < 0.05), and increase Th2 cytokine levels (P < 0.05). The percentage of CD4(+) CD25(+) T cells were also increased (1.60 ± 0.14 vs 2.45 ± 0.50, P < 0.05). 1-MT treatment led to opposite outcomes. 3, 4-DAA can alleviate the severity of colitis through inhibiting Th1 cells response, promoting Th2 cytokines expression and inducing CD4(+) CD25(+) T cells expression.

5-Hydroxytryptophan Alleviates Inflammation-Associated Mood Disturbance in Two Mouse Models of Colitis

Anxiety and depression states are common in patients with inflammatory bowel disease (IBD) and correlate with disease activity suggesting a biologic link to inflammation. Experimentally lowered serum levels of tryptophan, the amino acid precursor of serotonin, can induce mood disturbance. We previously reported that in patients with active Crohn's disease serum tryptophan levels can be severely depressed while kynurenine levels are elevated. This elevated kynurenine/tryptophan ratio reflects increased expression of the immunomodulatory enzyme indoleamine 2,3 dioxygenase (IDO) present in active IBD and colitis models. In the current study we aimed to determine if enteral delivery of 5-hydroxytryptophan (5-HTP), the tryptophan-based serotonin precursor, improved mood disturbance or affected colitis severity in two mouse models. Dextran sodium sulfate (DSS) colitis was induced in Bl6 mice with 3% DSS given over 3 5-day courses, with 10-day recovery periods. 2,4,6 trinitrobenzene sulfonic acid (TNBS) colitis was induced in BALB/c mice using 4 escalating doses of TNBS (0.35 mg to 1.2 mg). In each experiment there were 3 groups of 7-10 mice: 1) control group (PBS gavage), 2) colitis control group (PBS gavage), and 3) colitis group with 5-HTP (0.5 mg gavage before testing). Behavior was filmed and scored at three time points: pre-colitis, after acute colitis, and after chronic colitis. Anxiety-like behavior was tested using the light-dark preference test (LDT). Depressive behavior was tested using the tail suspension test (TST). Locomotor activity (LMA) was tested at each time-point to rule out potential physical impairment prior to behavioral testing. Colitis activity was followed clinically (diarrhea, hematochezia, and weight loss) and assessed by histology and myeloperoxidase (MPO) activity. No differences in clinical or histology parameters were identified between colitis groups. Similarly, MPO activity did not differ with or without 5-HTP supplementation in both DSS and TNBS colitis. Locomotor abilities were similar in all 3 groups. No differences in mouse behavior were present at baseline or after acute colitis. Mice with chronic colitis from DSS spent significantly less time in light than controls, indicating anxiety-like behavior. This anxiety behavior was normalized by 5-HTP supplementation. Depressive behavior as measured by TST immobility time was longer in chronic DSS colitis; however, a therapeutic effect of 5-HTP was not observed. In TNBS colitis, mice had fewer entries to the light compared to controls in the LDT. This anxiety-like behavior was normalized by 5-HTP supplementation. There was no effect of TNBS colitis or 5-HTP on immobility as measured by the TST. Table 1 summarizes these findings. Anxiety- and depressive-like behavior is heightened in 2 models of chronic colitis. While anxiety behavior patterns vary by mouse strain, they are normalized by administration of the tryptophan-derived serotonin precursor 5-HTP. Importantly, colitis is not worsened by enteral supplementation with physiologic doses of 5-HTP (i.e. proportional to human dosing). With translational validation, 5-HTP may be considered an intervention for colitis-associated anxiety in IBD patients.

P095 Neutralizing responsiveness to Interleukin-33 abrogat1es experimental colitis through enhanced mucosal wound healing

Novel therapeutic principles are urgently needed to cure inflammatory bowel diseases (IBD) that have been intrinsically linked to a deregulated inflammatory cytokine network. Here we identify the interleukin (IL)-1-like cytokine IL-33 and its receptor ST2 as novel negative regulators of wound healing in the colon of mice. Study in BL6 and IL-33R/ST2 deficient mice using dextran sodium sulfate (DSS) and 2,4,6-trinitrobenzene sulfonic acid (TNBS) colitis analyzing classical parameters of inflammation. Genetic ablation of ST2 protected the colon from chemical insults by dextran sodium sulfate (DSS) and 2,4,6-trinitrobenzene sulfonic acid (TNBS) that coincided with reduced acute pro-inflammatory response together with sustained expression of cytoprotective factors, including connexin-43. Likewise, administration of an anti-ST2 blocking antibody to mice treated by dextran sodium sulfate improved signs of morbidity, whereas recombinant IL-33 increased the risk for colitis. Consistently, the colonic mucosa of ST2-deficient mice was characterized by an enhanced wound healing response in a model of acute in vivo injury in the colon. In conclusion, we report here that the IL-33/ST2 axis plays a critical role in inflammation resolution by regulating self-renewal of the colonic epithelia, indicating neutralization of ST2 may represent a novel therapeutic target for effective treatment in IBD.

Selective Glucocorticoid Receptor Agonists for the Treatment of Inflammatory Bowel Disease: Studies in Mice with Acute Trinitrobenzene Sulfonic Acid Colitis

Despite being a mainstay of inflammatory bowel disease (IBD) therapy, glucocorticoids (GCs) still carry significant risks with respect to unwanted side effects. Alternative drugs with a more favorable risk/benefit ratio than common GCs are thus highly desirable for the management of IBD. New and supposedly selective glucocorticoid receptor (GR) agonists (SEGRAs), with dissociated properties, have been described as promising candidates for circumventing therapeutic problems while still displaying full beneficial anti-inflammatory potency. Here, we report on compound A [CpdA; (2-((4-acetophenyl)-2-chloro-N-methyl)ethylammonium-chloride)] and N-(4-methyl-1-oxo-1H-2,3-benzoxazine-6-yl)-4-(2,3-dihydrobenzofuran-7-yl)-2-hydroxy-2-(trifluoromethyl)-4-methylpentanamide (ZK216348), two GR agonists for the treatment of experimental colitis. Their therapeutic and anti-inflammatory effects were tested in the acute trinitrobenzene sulfonic acid-mediated colitis model in mice against dexamethasone (Dex). In addition to their influence on immunological pathways, a set of possible side effects, including impact on glucose homeostasis, steroid resistance, and induction of apoptosis, was surveyed. Our results showed that, comparable with Dex, treatment with CpdA and ZK216348 reduced the severity of wasting disease, macroscopic and microscopic damage, and colonic inflammation. However, both SEGRAs exhibited no GC-associated diabetogenic effects, hypothalamic pituitary adrenal axis suppression, or development of glucocorticoid resistance. In addition, CpdA and ZK216348 showed fewer transactivating properties and successfully dampened T helper 1 immune response. Unlike ZK216348, the therapeutic benefit of CpdA was lost at higher doses because of toxic apoptotic effects. In conclusion, both SEGRAs acted as potent anti-inflammatory agents with a significantly improved profile compared with classic GCs. Although CpdA revealed a narrow therapeutic window, both GR agonists might be seen as a starting point for a future IBD treatment option.

Juvenile ferric iron prevents microbiota dysbiosis and colitis in adult rodents

To assess whether juvenile chronic ferric iron ingestion limit colitis and dysbiosis at adulthood in rats and mice. Two sets of experiments were designed. In the first set, recently weaned mice were either orally administered ferrous (Fe²⁺) iron salt or ferric (Fe³⁺) microencapsulated iron for 6 wk. The last week of experiments trinitrobenzene sulfonic acid (TNBS) colitis was induced. In the second set, juvenile rats received the microencapsulated ferric iron for 6 wk and were also submitted to TNBS colitis during the last week of experiments. In both sets of experiments, animals were sacrificed 7 d after TNBS instillation. Severity of the inflammation was assessed by scoring macroscopic lesions and quantifying colonic myeloperoxidase (MPO) activity. Alteration of the microflora profile was estimated using quantitative polymerase chain reaction (qPCR) by measuring the evolution of total caecal microflora, Bacteroidetes, Firmicutes and enterobacteria. Neither ferrous nor ferric iron daily exposures at the juvenile period result in any effect in control animals at adulthood although ferrous iron repeated administration in infancy limited weight gain. Ferrous iron was unable to limit the experimental colitis (1.71 ± 0.27 MPO U/mg protein vs 2.47 ± 0.22 MPO U/mg protein in colitic mice). In contrast, ferric iron significantly prevented the increase of MPO activity (1.64 ± 0.14 MPO U/mg protein) in TNBS-induced colitis. Moreover, this positive effect was observed at both the doses of ferric iron used (75 and 150 mg/kg per day po--6 wk). In the study we also compared, in both rats and mice, the consequences of chronic repeated low level exposure to ferric iron (75 mg/kg per day po--6 wk) on TNBS-induced colitis and its related dysbiosis. We confirmed that ferric iron limited the TNBS-induced increase of MPO activity in both the rodent species. Furthermore, we assessed the ferric iron incidence on TNBS-induced intestinal microbiota dysbiosis. At first, we needed to optimize the isolation and quantify DNA copy numbers using standard curves to perform by qPCR this interspecies comparison. Using this approach, we determined that total microflora was similar in control rats and mice and was mainly composed of Firmicutes and Bacteroidetes at a ratio of 10/1. Ferric juvenile administration did not modify the microflora profile in control animals. Total microflora numbers remained unchanged whichever experimental conditions studied. Following TNBS-induced colitis, the Firmicutes/Bacteroidetes ratio was altered resulting in a decrease of the Firmicutes numbers and an increase of the Bacteroidetes numbers typical of a gut inflammatory reaction. In parallel, the subdominant population, the enterobacteria was also increased. However, ferric iron supplementation for the juvenile period prevented the increase of Bacteroidetes and of enterobacteria numbers consecutive to the colitis in both the studied species at adulthood. Rats and mice juvenile chronic ferric iron ingestion prevents colitis and dysbiosis at adulthood as assessed by the first interspecies comparison.

Therapeutic Potential of Carbon Monoxide (CO) for Intestinal Inflammation

The pathogenesis of inflammatory bowel disease (IBD) is complicated and even several therapeutic strategies have been developed, they are not adequate for achieving mucosal remission in all IBD patients. Several reports have described the role of carbon monoxide (CO) in protection against chronic intestinal inflammation. CO has recently emerged as a potent immunomodulatory entity, anti-inflammatory agent, and homeostasis of physiological condition. CO reduces lipopolysaccharide-induced proinflammatory cytokines in macrophages via the effect of MAPK pathways. Interleukin-6, one of the important cytokines in the pathogenesis of IBD is also regulated by CO. Epithelial cell restitution is reported to be important factor to control IBD and CO has been reported to enhance colonic epithelial restitution through FGF15/19 expression in colonic myofibroblasts. CO also reduced mucosal damage and inflammation in several experimental animal colitis models such as interleukin-10(-/-) mouse model, TCRα(-/-) mouse model, dextran sodium sulfate colitis model, and trinitrobennzen sulfonic acid colitis model. Taken together, CO has anti-inflammatory and enhancement of restitution examined in vitro model and in vivo experimental colitis model. These results indicate that CO may have a potential to be one of the therapeutic strategies in IBD patients.

Gene Expression Profiling Identifies Mechanisms of Protection to Recurrent Trinitrobenzene Sulfonic Acid Colitis Mediated by Probiotics

Host-microbiota interactions in the intestinal mucosa play a major role in intestinal immune homeostasis and control the threshold of local inflammation. The aim of this study was to evaluate the efficacy of probiotics in the recurrent trinitrobenzene sulfonic acid (TNBS)-induced colitis model and gain more insight into protective mechanisms. Moderate chronic inflammation of the colon was induced in BALB/c mice by repetitive intrarectal challenges with TNBS. Administration of probiotics started 2 weeks before colitis induction and was continued throughout colitis development. Long-term administration of Lactobacillus plantarum NCIMB8826 or the probiotic mixture VSL#3 reduced intestinal inflammation induced by TNBS, evident from improved colon morphology and less influx of innate (CD11b(+) ) and adaptive (CD4(+) /CD8(+) ) immune cells in the intestinal mucosa and decreased proinflammatory serum cytokines (interferon-gamma [IFN-γ], interleukin [IL]-17, IL-1β, monocyte chemoattractant protein [MCP]-1) in probiotic-treated mice. Genomewide expression analysis of colonic tissues using microarrays revealed differences in expression of genes related to inflammation and immune processes between untreated and probiotic treated mice. Principal component analysis revealed that probiotic treatment resulted in a shift of gene expression profiles toward those of healthy controls. Effects of probiotics on colonic gene expression were most profound during active inflammation, in particular on gene clusters related to mast cells and antimicrobial peptides. The results were substantiated by suppression of chemokine gene expression. Our data are in favor of a model in which probiotics downregulate expression of chemokines in the colon, thereby decreasing influx of inflammatory cells and rendering mice resistant to the induction of colitis.

Proteinase‐activated receptor‐4 evoked colorectal analgesia in mice: an endogenously activated feed‐back loop in visceral inflammatory pain

Activation of proteinase-activated receptor-4 (PAR-4) from the colonic lumen has an antinociceptive effect to colorectal distension (CRD) in mice in basal conditions. We aimed to determine the functional localization of the responsible receptors and to test their role in two different hyperalgesia models. Mice received PAR-4 activating peptide (PAR-4-AP, AYPGKF-NH(2)) or vehicle intraperitoneally (IP), and abdominal EMG response to CRD was measured. The next group received PAR-4-AP intracolonically (IC) with or without 2,4,6-triaminopyrimidine, a chemical tight junction blocker, before CRD. The SCID mice were used to test the role of lymphocytes in the antihyperalgesic effect. The effects of PAR-4-AP and PAR-4-antagonist (P4pal-10) were evaluated in water avoidance stress (WAS) model and low grade 2,4,6-trinitrobenzene sulfonic acid (TNBS) colitis. Spinal Fos protein expression was visualized by immunohistochemistry. The antinociceptive effect of PAR-4-AP disappeared when was administrered IP, or with the blockade of colonic epithelial tight junctions, suggesting that PAR-4-AP needs to reach directly the nerve terminals in the colon. The CRD-induced spinal Fos overexpression was reduced by 43% by PAR-4-AP. The PAR-4-AP was antihyperalgesic in both hyperalgesia models and in mice with impaired lymphocytes. The PAR-4-antagonist significantly increased the TNBS, but not the WAS-induced colonic hyperalgesia. The antinociceptive effect of PAR-4-AP depends on its penetration to the colonic mucosa. The PAR-4 activation is endogenously involved as a feedback loop to attenuate inflammatory colonic hyperalgesia to CRD.

Colitogenic role of tumour necrosis factor (TNF) receptors in trinitrobenzene sulphonic acid colitis: TNF-R1 ablation does not affect systemic inflammatory response

Tumour necrosis factor (TNF)-α plays a critical role in the pathogenesis of T helper type 1-mediated colitis such as Crohn's disease. However, the roles of its two receptors in mediating pathology remain largely unknown. In this study, trinitrobenzene sulphonic acid (TNBS) was used to induce colitis in TNF-receptor single or double knock-out (DKO) BALB/c mice and in wild-type counterparts. TNF-R1(-/-) mice had significantly less weight loss, reduced mortality, colon shortening and oedema, colon histological damage and lower levels of colon myeloperoxidase compared with wild-type (WT) BALB/c mice. A similar manifestation was also observed in TNF-R2(-/-) and TNF-R1(-/-) TNF-R2(-/-) (TNF-R DKO) mice. Strikingly, systemic inflammatory response (including splenomegaly and monocyte expansion) was found in WT and TNF-R1(-/-) mice after TNBS, instead of TNF-R2(-/-) and TNF-R DKO mice. Attenuated pathology of colitis in TNF-R1(-/-) or TNF-R2(-/-) mice correlated with lower amounts of interleukin (IL)-6, IL-1β, monocyte chemotactic protein (MCP)-1, IL-12p70 and interferon (IFN)-γ production in the colons. Importantly, ablation of TNF-R1 or TNF-R2 reduced the number of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labelling (TUNEL)-positive apoptotic epithelial cells in the affected colons compared with WT TNBS-instilled controls, which might be due to the heightened ratio of Bcl-2/Bax and reduced activity of nuclear factor (NF)-κB. These findings suggest that either TNF-R1 or TNF-R2 plays a pathogenic role in the pathology of colitis and TNF signalling via TNF-R1 or TNF-R2 alone is not sufficient for inducing mucosal damage.

Anti-inflammatory capacity of selected lactobacilli in experimental colitis is driven by NOD2-mediated recognition of a specific peptidoglycan-derived muropeptide

Background and aimsInflammatory bowel disease (IBD) has been linked to a loss of tolerance towards the resident microflora. Therapeutic use of probiotics is known to be strain specific, but precise...

Anti‐inflammatory actions of phosphatidylinositol

Chronic inflammatory T-cell-mediated diseases such as inflammatory bowel disease (IBD) are often treated with immunosuppressants including corticosteroids. In addition to the intended T-cell suppression, these farmacons give rise to many side effects. Recently, immunosuppressive phospholipids have been proposed as less-toxic alternatives. We aimed to investigate the immunoregulatory capacities of the naturally occurring phospholipid phosphatidylinositol (PI). Systemic PI treatment dramatically reduced disease severity and intestinal inflammation in murine 2,4,6-trinitrobenzene sulfonic acid (TNBS) colitis. Moreover, PI treatment inhibited the inflammatory T-cell response in these mice, as T cells derived from colon-draining LN of PI-treated mice secreted less IL-17 and IFN-γ upon polyclonal restimulation when compared to those of saline-treated mice. Further characterization of the suppressive capacity of PI revealed that the phospholipid suppressed Th cell differentiation in vitro irrespective of their cytokine profile by inhibiting proliferation and IL-2 release. In particular, PI diminished IL-2 mRNA expression and inhibited ERK1-, ERK-2-, p38- and JNK-phosphorylation. Crucially, PI did not ablate Treg differentiation or the antigen-presenting capacity of DCs in vitro. These data validate PI as a pluripotent inhibitor that can be applied mucosally as well as systemically. Its compelling functions render PI a promising novel physiological immune suppressant.

DNFB-DNS hapten-induced colitis in mice should not be considered a model of inflammatory bowel disease5

The dinitrofluorobenzene/dinitrosulfonic acid (DNFB/DNS) model was originally described as an experimental model of intestinal inflammation resembling human ulcerative colitis (UC). Due to the absence of acceptable UC experimental models for pharmacological preclinical assays, here we examine the immune response induced in this model. Balb/c mice were sensitized by skin application of DNFB on day 1, followed by an intrarectal challenge with DNS on day 5. We further expanded this model by administering a second DNS challenge on day 15. The features of colonic inflammation and immune response were evaluated. The changes observed in colonic tissue corresponded, in comparison to the trinitrobenzene sulfonic acid (TNBS) colitis model, to a mild mucosal effect in the colon, which spontaneously resolved in less than 5 days. Furthermore, the second hapten challenge did not exacerbate the inflammatory response. In contrast to other studies, we did not observe any clear involvement of tumor necrosis factor alpha (TNF-α) or other Th1 cytokines during the initial inflammatory response; however, we found that a more Th2-humoral response appeared to mediate the first contact with the hapten. An increased humoral response was detected during the second challenge, although an increased Th1/Th17-cytokine expression profile was also simultaneously observed. On the basis of these results, although the DNFB/DNS model can display some features found in human UC, it should be considered as a model for the study of the intestinal hypersensitivity seen, for example, during food allergy or irritable bowel syndrome but not intestinal inflammation per se.

Essential role for mast cell tryptase in acute experimental colitis

Patients with inflammatory bowel disease (IBD) have increased numbers of human tryptase-β (hTryptase-β)-positive mast cells (MCs) in the gastrointestinal tract. The amino acid sequence of mouse mast cell protease (mMCP)-6 is most similar to that of hTryptase-β. We therefore hypothesized that this mMCP, or the related tryptase mMCP-7, might have a prominent proinflammatory role in experimental colitis. The dextran sodium sulfate (DSS) and trinitrobenzene sulfonic acid (TNBS) colitis models were used to evaluate the differences between C57BL/6 (B6) mouse lines that differ in their expression of mMCP-6 and mMCP-7 with regard to weight loss, colon histopathology, and endoscopy scores. Microarray analyses were performed, and confirmatory real-time PCR, ELISA, and/or immunohistochemical analyses were carried out on a number of differentially expressed cytokines, chemokines, and matrix metalloproteinases (MMPs). The mMCP-6-null mice that had been exposed to DSS had significantly less weight loss as well as significantly lower pathology and endoscopy scores than similarly treated mMCP-6-expressing mice. This difference in colitis severity was confirmed endoscopically in the TNBS-treated mice. Evaluation of the distal colon segments revealed that numerous proinflammatory cytokines, chemokines that preferentially attract neutrophils, and MMPs that participate in the remodeling of the ECM were all markedly increased in the colons of DSS-treated WT mice relative to untreated WT mice and DSS-treated mMCP-6-null mice. Collectively, our data show that mMCP-6 (but not mMCP-7) is an essential MC-restricted mediator in chemically induced colitis and that this tryptase acts upstream of many of the factors implicated in IBD.

The effect on preimplantation embryo development of non-specific inflammation localized outside the reproductive tract

The aim of this study was to evaluate the possible effect of non-specific acute inflammation localized outside the reproductive tract on the quality of preimplantation embryos. In fertilized female mice two experimental models of inflammation were used—trinitrobenzene sulfonic acid colitis and carrageenan paw oedema. Inflammation was induced during the cleavage period of embryo development and embryos were collected at 92 h post hormonal synchronization. Stereomicroscopical evaluation of in vivo derived embryos showed that the presence of inflammation in the maternal body did not affect their basic developmental abilities, i.e. there were no significant differences in the proportion of early blastocysts, morulas, slowly developing embryos and degenerates between embryonic pools obtained from mothers with induced inflammation and control mothers. In the next step, non-degenerated embryos from all mothers were cultured in vitro under standard conditions for another 24 h, and the average cell number (fluorescence DNA staining) and the incidence of cell death (fluorescence viability staining combined with TUNEL assay) were evaluated. The majority of cultured embryos reached expanded blastocyst stage. There were no significant differences in the average cell numbers of blastocysts, but blastocysts derived from mothers with induced inflammation showed a significantly higher incidence of dead cells in both experiments. The majority of dead cells were of apoptotic origin. These results show that non-specific inflammation localized outside the reproductive tract has no detrimental effect on the preimplantation embryo growth; however it can affect the embryo quality.

S1746 Rethinking the Role of IL-13 in Chronic 2,4,6-Trinitrobenzene Sulfonic Acid (TNBS) Colitis Induced Fibrosis

BACKGROUND: Mast cells play a key role in the pathophysiology of inflammatory bowel disease (IBD). Tranilast, N-(3,4-dimethoxycinnamoyl) anthranilic acid, a mast cell stabilizer, has been empirically used for IBD in Japan. The mechanism of tranilast in the improvement of IBD, however, has not yet been clearly delineated, and requires further investigation. Recently, heme oxygenase (HO)-1 has attracted attention in the pro-inflammationmechanism of tranilast. Aim: To investigate the role of tranilast for the treatment of IBD, and elucidated the mechanism and involvement of HO-1 in this effect, we administered tranilast intrarectally to dextran sulfate sodium (DSS)-induced colitis in mice. METHODS: Colitis was induced in C57BL/6(B6) mice by adding 3% DSS in drinking water ad libium for 5 days. Tranilast was administered by enema on day 0, day 2, and day 4 after induction of colitis. The disease activity index (DAI) and degree of colon injury were determined to know the clinical course of colitis. Toluidine blue staining was carried out to identify the mast cell. Staining for HO1 with immunofluorescence to evaluate the expression of HO-1 in the colon. Total RNA was extracted from colon specimens with quantitative reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Tranilast ameliorated DSS colitis clinically and pathologically with decreased number and degranulation of mast cells in the colon of DSS colitis. mRNA expression was increased for tumor necrosis factor(TNF)-α, interferon(IFN)-γ, interleukin (IL)-6, and decreased that for IL-10 in the colon of DSS colitis. In contrast, tranilast markedly decreased expression of mRNAs for the proinflammatory cytokines, and increased that of the anti-inflammatory cytokines. Moreover, tranilast increased HO-1 expression on colonic epithelial cells as well as on colon infiltrating cells of DSS colitis. CONCLUSION: Tranilast ameliorated DSS colitis by regulating mast cell degranulation, decreasing inflammatory cytokines and increasing anti-inflammatory cytokines. Tranilast might exert these effects partly through enhanced HO-1 expression in the colon, suggesting a potential adjunctive therapy for IBD.

CCL2 (pM levels) as a therapeutic agent in inflammatory bowel disease models in mice

Chemokines regulate the pathways that restrict homing of specific subsets of immune cells, and thereby fine tune the immune response at specific lymphoid and peripheral tissues. CCL2 is a chemokine that induces migration of monocytes, memory T cells, and dendritic cells. Previously, we demonstrated that pM levels of CCL2 dramatically inhibit migration of T cells. The aim was to test whether subphysiological doses of CCL2 can ameliorate murine colitis and inflammation-induced colorectal cancer. TNBS (2,4,6 trinitrobenzene sulfonic acid) colitis and dextran sodium sulfate (DSS) colitis were induced in Balb/c and C57BL/6 mice, respectively. Mice were treated daily with intraperitoneal CCL2 injections. Disease activity was assessed clinically, histologically, and by measuring inflammatory cytokine levels. In addition, an inflammatory cancer model was induced by azoxymethane-DSS (AOM-DSS) in Balb/c mice. Mice were treated daily with CCL2 for 11 weeks and then assessed for number of tumors in the colons. Daily administration of CCL2 (60-120 ng) significantly decreased the development of TNBS- and DSS-induced colitis. In a DSS-AOM model, CCL2-treated mice developed significantly fewer tumors (P < 0.005) at 11 weeks. Chronic inflammation in the CCL2-treated mice was significantly less pronounced as compared to phosphate-buffered saline-treated mice. Administration of pM levels of CCL2 significantly inhibits migration of T cells in amelioration of TNBS and DSS colitis and inhibits development of colorectal cancer in an AOM-DSS colitis model in mice. Thus, pM levels of CCL2 may be clinically beneficial as an antiinflammatory agent in IBD.

Linaclotide - a secretagogue and antihyperalgesic agent - what next?

Ongoing clinical trials suggest that linaclotide, a first-in-class, 14-amino acid peptide guanylate cyclase-C (GC-C) receptor agonist and intestinal secretagogue is an effective treatment for chronic constipation. A study in this issue of the Journal suggests that linaclotide also has antihyperalgesic effects in three common rat models of inflammation- and stress-induced hypersensitivity (i.e., acute trinitrobenzene sulfonic acid colitis, water avoidance stress [WAS], and restraint-induced stress) but not in naïve animals. In mice, linaclotide at least partly reduces hyperalgesia via GC-C receptors. Dose-effect relationships of linaclotide were complicated and non-linear. This viewpoint discusses human clinical trials with linaclotide and the results of this study. Potential mechanisms and clinical significance of these findings are explored. Collectively, these data suggest that GC-C receptors exert other, as yet poorly understood, effects on gastrointestinal sensitivity in conditions associated with inflammation and/or stress-induced increased intestinal permeability. However, the data need to be confirmed in humans and in long-term animal models. Further studies are also necessary to elucidate the mechanisms as these effects cannot be explained by linaclotide's known effects on epithelial GC-C receptors.

Modulation of the colonic epithelial cell responses and amelioration of inflammation by CD80 blockade in TNBS colitis

Inflammatory bowel diseases (IBD) result from dysregulated immune responses to the luminal antigens initiated by the colonic epithelial cells (CEC) and propagated by activated CD4+ T cells. Biological therapies are being developed that suppress inflammation and promote epithelial homeostasis. Treatment with the CD80-competitive antagonist peptide (CD80-CAP) has been shown to suppress T cell responses in multiple disease models. Here we investigated the effect of the CD80-CAP on the CEC responses in experimental colitis. Balb/c mice induced with trinitrobenzene sulfonic acid (TNBS) colitis were administered CD80-CAP/control peptide/vehicle. Administration of the CD80-CAP decreased microscopic inflammation and restored the expression of TLR-2, 3, 4 and 5 mRNA in the CEC of colitis mice to physiological levels. Furthermore, the CD80-CAP treatment suppressed Th1 cytokines and enhanced Th2 responses by the CEC in colitis mice. In conclusion, CD80-CAP administration ameliorated TNBS colitis by reducing the inflammatory cell infiltration and modulating the CEC response potentially restoring mucosal tolerance.