Recombinant Thrombomodulin Modulates Murine Colitis Possibly via High-Mobility Group Box 1 Protein Inhibition.

BACKGROUND AND AIM: Thrombomodulin (TM) is an anticoagulant cofactor protein. We hypothesized that its recombinant soluble TM (rhTM) form, widely used to treat disseminated intravascular coagulation, might have anti-inflammatory action in inflammatory bowel disease (IBD), possibly through its inhibition of high-mobility group box 1 protein (HMGB1). METHODS: We investigated inflammatory effects of HMGB1 and anti-inflammatory effect of rhTM in dextran sulfate sodium (DSS)-treated mice, some cell lines and ulcerative colitis (UC) patients, particularly focusing on changes of vascular endothelial adhesion molecules. RESULTS: Treatments with rhTM significantly attenuated DSS-treated mice clinically and histologically. The mRNA levels of proinflammatory cytokines and adhesion molecules were decreased by rhTM. Increased inflammatory cells in the colonic mucosa strongly expressed HMGB1 in the cytoplasm in the DSS-treated mice and UC patients' colonic mucosa, which were significantly decreased by rhTM in mice. In in vitro experiments, rhTM significantly decreased the mRNA levels of tumor necrosis factor-alpha (TNF-α) and adhesion molecules increased by endotoxin exposures in RAW 264.7 (macrophage cell line) and bEND.3 cells (endothelial cell line), suggesting the proinflammatory role of HMGB1 in TNF-α production from macrophages. CONCLUSIONS: These findings suggest that rhTM may be useful for the treatment of IBD by attenuating inflammatory cytokine production and adhesion molecule expression, partly because of its inhibition of HMGB1.

Beneficial effect of an omega-6 PUFA-rich diet in non-steroidal anti-inflammatory drug-induced mucosal damage in the murine small intestine.

AIM: To investigate the effect of a fat rich diet on non-steroidal anti-inflammatory drug (NSAID)-induced mucosal damage in the murine small intestine. METHODS: C57BL6 mice were fed 4 types of diets with or without indomethacin. One group was fed standard laboratory chow. The other groups were fed a fat diet consisting of 8% w/w fat, beef tallow (rich in SFA), fish oil, (rich in omega-3 PUFA), or safflower oil (rich in omega-6 PUFA). Indomethacin (3 mg/kg) was injected intraperitoneally from day 8 to day 10. On day 11, intestines and adhesions to submucosal microvessels were examined. RESULTS: In the indomethacin-treated groups, mucosal damage was exacerbated by diets containing beef tallow and fish oil, and was accompanied by leukocyte infiltration (P < 0.05). The mucosal damage induced by indomethacin was significantly lower in mice fed the safflower oil diet than in mice fed the beef tallow or fish oil diet (P < 0.05). Indomethacin increased monocyte and platelet migration to the intestinal mucosa, whereas safflower oil significantly decreased monocyte and platelet recruitment (P < 0.05). CONCLUSION: A diet rich in SFA and omega-3 PUFA exacerbated NSAID-induced small intestinal damage via increased leukocyte infiltration. Importantly, a diet rich in omega-6-PUFA did not aggravate inflammation as monocyte migration was blocked.

Phlebosclerotic colitis that was difficult to distinguish from collagenous colitis.

Phlebosclerotic colitis is a rare and recently known disease entity and its etiology is still to be elucidated. Some phlebosclerotic colitis cases are difficult to distinguish from collagenous colitis because of the similarity of pathological findings. In all Japanese case reports of phlebosclerotic colitis in which an association with the use of Chinese herbal medicine is suspected, sansisi (gardenia fruit) was included, suggesting pathogenesis of this disease. We report a case of phlebosclerotic colitis that wasdifficult to be distinguished from collagenous colitis, and an association with the use of Chinese herbal medicine was suspected as the cause of the disease.

Trans fatty acids in diets act as a precipitating factor for gut inflammation?

Fatty acids in our daily diet are broadly classified into cis and trans fatty acids (TFAs). TFAs are formed during the manufacturing process of hydrogenated vegetable oils such as margarine. Modern diets such as deep-fried products, frozen foods, and packaged snacks commonly include large quantities of margarine containing TFAs. Although an increased report in the effects of the diet containing TFAs on a risk factor of metabolic syndrome, diabetes mellitus, and coronary heart disease has been observed in the recent years, influence on intestinal inflammation remains unknown. This review describes pro-inflammatory effects of TFAs in our diary diet on various systemic disorders and also discusses a possible role of TFAs on gut inflammation.

1,4-Dihydroxy-2-naphthoic acid from Propionibacterium freudenreichii reduces inflammation in interleukin-10-deficient mice with colitis by suppressing macrophage-derived proinflammatory cytokines.

The anti-inflammatory mechanism of prebiotics has recently been shown to have an impact on the host immune system. DHNA from Propionibacterium freudenreichii is known to promote the proliferation of Bifidobacterium and can ameliorate colitis, although its mode of action remains unknown. In this study, we investigated whether DHNA attenuates inflammation in piroxicam-treated IL-10(-/-) mice, particularly focusing on the changes of the host immune mechanism. DHNA was administered to IL-10(-/-) mice with colitis, and the expression of adhesion molecules and mRNA levels of proinflammatory cytokines were determined. DHNA pretreatment attenuated the piroxicam-induced histological changes. The increased F4/80-positive cell infiltration and VCAM-1 expression were decreased by DHNA administration. The increased mRNA levels of proinflammatory cytokines were also suppressed by DHNA. In in vitro experiments, increased mRNA levels of proinflammatory cytokines after endotoxin exposure were decreased significantly by DHNA pretreatment in RAW264.7, a macrophage cell line, and IL-10(-/-) mice BMMs, whereas the expression of VCAM-1 in bEnd.3 cells, a endothelial cell line, was not affected. Taken together, these findings suggest that administration of DHNA is useful for the treatment of colitis in piroxicam-treated IL-10(-/-) mice and that attenuation of colitis by DHNA may partly be a result of its direct action on intestinal macrophages to inhibit proinflammatory cytokine production.

Involvement of autotaxin/lysophospholipase D expression in intestinal vessels in aggravation of intestinal damage through lymphocyte migration.

Lysophosphatidic acid (LPA) has a critical role in lymphocyte migration to secondary lymphoid organs. Autotaxin (ATX)/lysophospholipase D, in the vascular endothelium, is the main enzyme involved in LPA production. Whether ATX is involved in pathological lymphocyte migration to the inflamed mucosa has not been studied. We investigated the involvement of ATX in inflammatory bowel disease patients and two murine models of colitis. Tissue samples were obtained by intestinal biopsies from patients with Crohn's disease and those with ulcerative colitis with informed consent. ATX immunoreactivity was colocalized with MAdCAM-1-positive high-endothelial-like vessels, close to sites of lymphocyte infiltration. Enhanced expression of ATX mRNA was observed in the inflamed mucosa from Crohn's disease and ulcerative colitis patients. ATX mRNA expression level was remarkably higher in the actively inflamed mucosa than in the quiescent mucosa in the same patient. In the T-cell-transferred mouse model, ATX mRNA expression level gradually increased as colitis developed. In the dextran sodium sulfate mouse model, the expression level was considerably higher in colonic mucosa of chronically developed colitis than in colonic mucosa of acute colitis. Administration of an ATX inhibitor, bithionol, remarkably decreased lymphocyte migration to the intestine and ameliorated both dextran sodium sulfate-induced colitis and CD4-induced ileocolitis. In transwell assays, administration of bithionol or 1-bromo-3(s)-hydroxy-4-(palmitoyloxy) butylphosphonate (BrP-LPA) significantly decreased transmigration of splenocytes through high-endothelial-like vessels induced by TNF-α. We conclude that enhanced expression of ATX in the active mucosa has been implicated in the pathophysiology of inflammatory bowel disease through enhancing aberrant lymphocyte migration to the inflamed mucosa.

Endoscopic finding of spontaneous hemorrhage correlates with tumor necrosis factor alpha expression in colonic mucosa of patients with ulcerative colitis.

BACKGROUND: Ulcerative colitis (UC) is an intractable colonic disease, and it shows several endoscopic findings. Recently, it was reported that the expression level of mucosal tumor necrosis factor alpha (TNF-α) was useful for predicting patient response to infliximab. However, no data regarding the value of endoscopic findings to predict treatment efficacy or cytokine expression level exist. OBJECTIVE: We investigated the expression of leukocyte adhesion-related molecules and cytokines in colonic mucosa and compared it to endoscopic findings. METHODS: One hundred and fifty-nine patients were enrolled. Tissue samples were obtained by colonic biopsy from patients with UC. Colitis activity was determined by Matts' criteria. The degree of mRNA expression of TNF-α, interferon gamma (IFN-γ), interleukin (IL)-8, IL-17A, and mucosal vascular addressin adhesion molecule-1 (MAdCAM-1) in mucosal samples was determined by real-time quantitative polymerase chain reaction. These expression levels were compared with the degree of Matts' grade and individual endoscopic findings. RESULTS: The expression of TNF-α, IFN-γ, IL-8, IL-17A, and MAdCAM-1 mRNA significantly increased as Matts' endoscopic grade elevated. Actively inflamed mucosa with spontaneous hemorrhage revealed a significantly increased expression level of TNF-α mRNA than that without spontaneous hemorrhage. No other individual endoscopic parameter was significantly correlated with the expression level of TNF-α mRNA. CONCLUSIONS: Inflamed mucosa with spontaneous hemorrhage may suggest increased expression of TNF-α mRNA levels in colonic mucosa of UC patients, which could predict a lower response to infliximab treatment and more aggressive induction regime or change to other therapy should be taken into account.

Dietary lipids and sweeteners regulate glucagon-like peptide-2 secretion.

Glucagon-like peptide-2 (GLP-2) is a potent intestinal growth factor derived from enteroendocrine L cells. Although food intake is known to increase GLP-2 secretion, its regulatory mechanisms are largely unknown as a result of its very short half-life in venules. The aims of this study were to compare the effects of luminal nutrients on the stimulation of GLP-2 secretion in vivo using lymph samples and to clarify the involvement of the sweet taste receptor in this process in vitro. Lymph samples were collected from the thoracic duct after bolus administration of dietary lipids or sweetening agents into the duodenum of rats. Human enteroendocrine NCI-H716 cells were also used to compare the effects of various nutrients on GLP-2 secretion. GLP-2 concentrations were measured by ELISA in vivo and in vitro. GLP-2 secretion was enhanced by polyunsaturated fatty acid- and monounsaturated fatty acid-rich dietary oils, dietary carbohydrates, and some kinds of sweeteners in rats; this effect was reproduced in NCI-H716 cells using α-linolenic acid (αLA), glucose, and sweeteners. GLP-2 secretion induced by sweetening agents was inhibited by lactisole, a sweetness-antagonizing inhibitor of T1R3. In contrast, lactisole was unable to inhibit GLP-2 secretion induced by αLA alone. Our results suggested that fatty acid- and sweetener-induced GLP-2 secretion may be mediated by two different pathways, with the sweet taste receptor involved in the regulation of the latter.

Indomethacin-induced small intestinal injury is ameliorated by cilostazol, a specific PDE-3 inhibitor.

BACKGROUND: Neutrophil migration, one of the major factors predisposing to nonsteroidal anti-inflammatory drugs (NSAIDs)-induced intestinal lesions, consists of several steps, including interaction with P-selectin from platelets. Cilostazol, a specific phosphodiesterase (PDE)-3 inhibitor, suppresses the expression of P-selectin from platelets and reduces interaction between platelets and leukocytes, leading to inflammatory amelioration in several disease models. We tried to clarify the therapeutic effectiveness of cilostazol for NSAID-induced small intestinal lesions. SUBJECTS AND METHODS: 1) Anti-PSGL-1 antibody (2 mg/kg) or cilostazol (100 mg/kg) was administered to mice one hour before Indomethacin (IND, 2.5 mg/kg) administration for 4 days to evaluate small intestinal lesions. 2) IND-induced migratory behaviors of neutrophils and platelets were evaluated in intestinal vessels by an intravital microscopy. RESULTS: i) IND induced small intestinal lesions with an increase in MPO activity. Anti-PSGL-1 antibody and cilostazol ameliorated intestinal lesions along with suppression of MPO activity. ii) Intravital microscopy revealed that administration of IND increased migration of platelet-bearing neutrophils. Cilostazol treatment ameliorated neutrophil migration by blocking interaction between platelets and neutrophils. CONCLUSION: Our results suggest that enhanced platelets-bearing neutrophil migration is critically involved in the pathogenesis of IND-induced small intestinal lesions and suggest a potential application of cilostazol for prevention of NSAID-induced small intestinal lesions.

HIF-1 in T cells ameliorated dextran sodium sulfate-induced murine colitis.

HIF-1 is active in hypoxia, such as inflamed mucosa, and HIF-1 in epithelium has been reported to control inflamed mucosa in IBD models. Although T cells play an important role for pathogenesis of IBD, the function of HIF-1 in T cells remains to be elucidated. We aimed to clarify the function of HIF-1 in T cells in IBD with focus on the balance between Treg and Teff. Double immunohistochemistry of colonic mucosa in IBD patients showed that HIF-1 was expressed in T cells infiltrating the inflamed mucosa, suggesting that HIF-1 in T cells is involved in the pathogenesis. DSS administration to T cell-specific HIF-1α KO mice showed more severe colonic inflammation than control mice with the up-regulation of Th1 and Th17. Hypoxic stimulation in vitro increased Treg activation in WT T cells but not in HIF-1-deleted T cells. In contrast, hypoxic stimulation increased Th17 activation, and the degree was higher in HIF-1-deleted cells than in control cells. These results show that hypoxia controls intestinal inflammation by regulating cytokine balance in a HIF-1-dependent manner, suggesting that strengthening HIF-1 induction in T cells at the sites of inflammation might be a therapeutic strategy for IBD regulation.

Physiological stress exacerbates murine colitis by enhancing proinflammatory cytokine expression that is dependent on IL-18.

Psychological stress is an environmental factor considered to be a precipitating factor of inflammatory bowel disease. Interleukin (IL)-18 plays a role in stress-induced aggravation in some diseases. The aim of this study was to establish a model of murine colitis exacerbated by psychological stress and to clarify the role of IL-18 in this model. Male C57Bl/6 mice and IL-18(-/-) mice were used for this study. The mice received dextran sulfate sodium (DSS) for induction of colitis. Some mice were exposed to psychological stress using a communication box. Body weight, colonic length, and histological inflammation were measured for assessment of colitis. Tumor necrosis factor (TNF)-α and IL-18 expression in the colon and IL-18 expression in the adrenal gland were analyzed using real-time PCR. The effect of anti-IL-18 antibody was also investigated. Effects of TNF-α and IL-18 on cytokine expressions were studied using the colonic epithelial cell line LS174T. Induction of psychological stress in DSS-treated wild-type mice significantly exacerbated colitis with enhanced expression of proinflammatory cytokines and IL-18. However, induction of psychological stress in DSS-treated IL-18(-/-) mice did not aggravate colitis compared with that in the IL-18(-/-) group given only DSS treatment. Stress-induced aggravation of colitis was ameliorated significantly by anti-IL-18 antibody treatment. IL-18 did not enhance TNF-α-induced expression of intercellular adhesion molecule-1 or IL-8 in LS174T. We established a model of colitis exacerbated by psychological stress. Psychological stress enhanced IL-18 expression and plays a proinflammatory role in stress-induced aggravation of colitis.