Tissue factor: a mediator of inflammatory cell recruitment, tissue injury, and thrombus formation in experimental colitis

There is growing evidence for an interplay between inflammatory and coagulation pathways in acute and chronic inflammatory diseases. However, it remains unclear whether components of the coagulation pathway, such as tissue factor (TF), contribute to intestinal inflammation, and whether targeting TF will blunt the inflammatory cell recruitment, tissue injury, and enhanced thrombus formation that occur in experimental colitis. Mice were fed 3% dextran sodium sulfate (DSS) to induce colonic inflammation, with some mice receiving a mouse TF-blocking antibody (muTF-Ab). The adhesion of leukocytes and platelets in colonic venules, light/dye-induced thrombus formation in cremaster muscle microvessels, as well as disease activity index, thrombin-antithrombin (TAT) complexes in plasma, and histopathologic changes in the colonic mucosa were monitored in untreated and muTF-Ab-treated colitic mice. In untreated mice, DSS elicited the recruitment of adherent leukocytes and platelets in colonic venules, caused gross and histologic injury, increased plasma TAT complexes, and enhanced thrombus formation in muscle arterioles. muTF-Ab prevented elevation in TAT complexes, reduced blood cell recruitment and tissue injury, and blunted thrombus formation in DSS colitic mice. These findings implicate TF in intestinal inflammation and support an interaction between inflammation and coagulation in experimental colitis.     

Impaired mucosal defense to acute colonic injury in mice lacking cyclooxygenase-1 or cyclooxygenase-2

To investigate roles in intestinal inflammation for the 2 cyclooxygenase (COX) isoforms, we determined susceptibility to spontaneous and induced acute colitis in mice lacking either the COX-1 or COX-2 isoform. We treated wild-type, COX-1(-/-), COX-2(-/-), and heterozygous mice with dextran sodium sulfate (DSS) to provoke acute colonic inflammation, and we quantified tissue damage, prostaglandin (PG) E(2), and interleukin-1beta. No spontaneous gastrointestinal inflammation was detected in mice homozygous for either mutation, despite almost undetectable basal intestinal PGE(2) production in COX-1(-/-) mice. Both COX-1(-/-) and COX-2(-/-) mice showed increased susceptibility to a low-dose of DSS that caused mild colonic epithelial injury in wild-type mice. COX-2(-/-) mice were more susceptible than COX-1(-/-) mice, and selective pharmacologic blockade of COX-2 potentiated injury in COX-1(-/-) mice. At a high dose, DSS treatment was fatal to 50% of the animals in each mutant group, but all wild-type mice survived. DSS treatment increased PGE(2) intestinal secretion in all groups except COX-2(-/-) mice. These results demonstrate that COX-1 and COX-2 share a crucial role in the defense of the intestinal mucosa (with inducible COX-2 being perhaps more active during inflammation) and that neither isoform is essential in maintaining mucosal homeostasis in the absence of injurious stimuli.     

The effect of antioxidant therapy on colonic inflammation in the rat

Under normal physiological conditions, chemical and antioxidant defenses protect tissues from the damaging effects of reactive oxygen metabolites (ROM). It has been proposed that ROMs are involved in the development of tissue injury in many inflammatory diseases and also in patients with colitis. In the present study we aimed to investigate the effects of antioxidant therapy on the extent of colonic inflammation and ROM levels in the injured tissues in a trinitrobenzene sulfonic acid-induced colitis model in the rat. Sprague-Dawley rats were pretreated with the antioxidants superoxide dismutase (30,000 U/kg s.c.) or catalase (400,000 U/kg s.c.) prior to induction of colitis and they were decapitated 24 h (acute group) or 6 days (chronic group) after the induction of colitis (each group consists of eight to ten rats). Pretreatment with the antioxidants reduced the macroscopic damage score significantly in both acute and chronic groups compared with untreated colitis groups, whereas they reduced the microscopic damage score and colonic wet weight only in the chronic group. The chemiluminescence assay - a technique to assess the presence of reactive oxygen species in the tissues - values of the groups pretreated with the antioxidants showed a tendency to decrease compared with the untreated colitis group, but they were not statistically significant. Based on these findings, pretreatment with the antioxidants superoxide dismutase or catalase has beneficial effects on the extent of colonic inflammation, particularly in the chronic period, and this may support the importance of antioxidant therapy to reduce the severity of inflammatory bowel disease in humans.     

Hepatocyte growth factor facilitates colonic mucosal repair in experimental ulcerative colitis in rats

Hepatocyte growth factor (HGF) modulates intestinal epithelial cell proliferation and migration, serving as a critical regulator of intestinal wound healing. In this study, we examined the effect of administration of recombinant human HGF on colonic mucosal damage in vivo. Acute colitis was induced in rats by feeding with 5% dextran sulfate sodium (DSS) for 7 days, and colitis was subsequently maintained by feeding with 1% DSS. On the 5th day of DSS administration, osmotic pumps releasing recombinant human HGF (200 microg/day) were implanted into the peritoneum of the rats. Continuous intraperitoneal delivery of HGF led to both increased serum human HGF levels and c-Met tyrosine phosphorylation within the colonic mucosa. Compared with mock-treated rats, those administered human HGF showed a reduction in colitis-associated weight loss, large intestinal shortening, and improved colonic erosions. Enhanced epithelial regeneration and cellular proliferation were observed in rats treated with recombinant human HGF. The weights of the liver, kidneys, and spleen were not affected by HGF administration. These results indicate that HGF administration accelerates colonic mucosal repair in rats with DSS-induced colitis and suggest that recombinant human HGF may be a useful therapeutic tool to facilitate intestinal wound healing in patients with ulcerative colitis.     

Case report of zinc deficiency in an elderly woman.

Zinc deficiency is not an uncommon nutritional disorder in the elderly. It should be suspected in patients who have conditions associated with zinc deficiency (Table 1) or who have one of the potential causes of zinc deficiency (Table 2). A low serum-zinc level indicates zinc deficiency unless an acute phase response is present. The acute-phase response should be suspected in a patient with an acute illness. A C-reactive protein level is helpful in identifying the acute-phase response. Our initial treatment of zinc deficiency centers on increasing dietary zinc. Often, however, because of other common problems of geriatric patients such as dementia or depression, the patient is unable to alter his or her diet. Then, zinc supplementation may be required. Copper, iron, and lipoprotein status should be monitored if long-term zinc supplementation is needed because they may be effected by the zinc supplementation.     

小肠黏膜下层对大鼠创伤皮肤愈合的实验研究

【目的】为研究小肠黏膜下层对创伤皮肤愈合过程的影响。【方法】制备了小肠黏膜下层片剂。用SD大鼠建立全层皮肤缺损的创伤模型,分成小肠黏膜下层组、络合碘凡士林纱条组以及空白对照组,分阶段取材,宏观观察及组织学观察以上三组大鼠愈合过程。【结果】小肠黏膜下层贴附皮肤不引起排斥反应,无伤口感染。小肠黏膜下层组在愈合速度方面快于络合碘凡士林纱条,空白对照组最慢,小肠黏膜下层组愈合无瘢痕,皮肤附件生长良好,而其余二组瘢痕愈合,皮肤附件仅生长于伤口边缘处。【结论】小肠黏膜下层具有消炎、促肉芽组织生长和上皮组织生长作用,应用于皮肤创伤且能无疤愈合。     

Normal luminal bacteria, especially Bacteroides species, mediate chronic colitis, gastritis, and arthritis in HLA-B27/human beta2 microglobulin transgenic rats.

Genetic and environmental factors are important in the pathogenesis of clinical and experimental chronic intestinal inflammation. We investigated the influence of normal luminal bacteria and several groups of selected bacterial strains on spontaneous gastrointestinal and systemic inflammation in HLA-B27 transgenic rats. Rats maintained germfree for 3-9 mo were compared with littermates conventionalized with specific pathogen-free bacteria. Subsequently, germfree transgenic rats were colonized with groups of five to eight bacteria that were either facultative or strictly anaerobic. Transgenic germfree rats had no gastroduodenitis, colitis, or arthritis, but developed epididymitis and dermatitis to the same degree as conventionalized rats. Colonic proinflammatory cytokine expression was increased in transgenic conventionalized rats but was undetectable in germfree and nontransgenic rats. Colitis progressively increased over the first 4 wk of bacterial exposure, then plateaued. Only transgenic rats colonized with defined bacterial cocktails which contained Bacteroides spp. had colitis and gastritis. Normal luminal bacteria predictably and uniformly induce chronic colonic, gastric and systemic inflammation in B27 transgenic F344 rats, but all bacterial species do not have equal activities.     

Recombinant human interleukin-11 restores smooth muscle function in the jejunum and colon of human leukocyte antigen-B27 rats with intestinal inflammation

Recombinant human interleukin (rhIL)-11 has anti-inflammatory and protective effects in models of intestinal mucosal injury. Our aim was to investigate whether oral treatment with rhIL-11 reverses functional abnormalities in intestinal muscle contractility resulting from human leukocyte antigen (HLA)-B27-dependent gut inflammation. Isometric contractions were studied in jejunal and colonic longitudinal muscles. Muscle strips were isolated from HLA-B27 transgenic rats with spontaneous inflammation following treatment with enteric-coated rhIL-11 multiparticulates (500 microg/kg) or placebo multiparticulates given orally every 48 h for 2 weeks. Myeloperoxidase (MPO) activity was measured in intestinal tissue samples and served as an index of inflammation. Colonic damage was also assessed histologically. The HLA-B27 rats receiving placebo had chronic diarrhea, and MPO activity was increased in the jejunum and colon. Intestinal inflammation was associated with a decreased ability of the muscles to generate active tension in response to electrical field stimulation, carbachol, or high KCl. In the jejunum of placebo-treated HLA-B27 rats, concentration-effect curves for carbachol were shifted to lower concentrations yielding a higher EC50. Oral treatment of HLA-B27 rats with rhIL-11 suppressed the symptoms of diarrhea, normalized MPO activity, and improved the colonic damage score. Simultaneously, neurally mediated responses were improved and the maximal tension generated by carbachol or KCl was normalized in the jejunum and colon. The EC50 for carbachol in the jejunum of HLA-B27 rats was also normalized by rhIL-11 treatment. Our data demonstrate that oral administration of enteric-coated rhIL-11 suppresses intestinal inflammation and reverses intestinal smooth muscle dysfunction in HLA-B27 transgenic rats.     

Metabolic changes in glutathione and metallothionein in newborn rat liver

Metallothionein (MT) and glutathione (GSH) both contain 30% cysteine and they have distinct developmental profiles in perinatal rat liver. The metabolic relationships between these two cysteine pools were investigated in newborn rats under various experimental conditions. Injection of 2-day-old rat pups with buthionine sulfoximine, phorone or diethylmaleate decreased hepatic GSH levels without any change in high basal levels of MT or zinc. Similarly injection of L-oxothiazolidine carboxylate increased hepatic GSH levels but no changes in MT or zinc levels were observed. Administration of buthionine sulfoximine in drinking water to pregnant rats from day 14 of gestation decreased hepatic GSH concentrations in both the dams and pups with little change observed in neonatal hepatic zinc and MT levels or in gamma-glutamyltranspeptidase activity. The induction of MT synthesis by zinc salts in newborn rats was not affected by the in utero reduction of GSH levels. Although maternal hepatic GSH levels can be decreased by a sulfhydryl-deficient diet, no changes were observed in GSH, MT or zinc levels in newborn rat liver. Reduction of perinatal hepatic MT levels by in utero zinc deficiency had little effect on GSH levels. However, inhibition of the cystathionase pathway in newborn rats with propargylglycine decreased hepatic levels of MT, zinc and GSH. The results suggest that whereas there is little interaction between these two pools of cysteine, inhibition of cystathionase activity can decrease hepatic concentrations of both GSH and MT.     

Neurotensin is a proinflammatory neuropeptide in colonic inflammation

The neuropeptide neurotensin mediates several intestinal functions, including chloride secretion, motility, and cellular growth. However, whether this peptide participates in intestinal inflammation is not known. Toxin A, an enterotoxin from Clostridium difficile, mediates pseudomembranous colitis in humans. In animal models, toxin A causes an acute inflammatory response characterized by activation of sensory neurons and intestinal nerves and immune cells of the lamina propria. Here we show that neurotensin and its receptor are elevated in the rat colonic mucosa following toxin A administration. Pretreatment of rats with the neurotensin receptor antagonist SR-48, 692 inhibits toxin A-induced changes in colonic secretion, mucosal permeability, and histologic damage. Exposure of colonic explants to toxin A or neurotensin causes mast cell degranulation, which is inhibited by SR-48,692. Because substance P was previously shown to mediate mast cell activation, we examined whether substance P is involved in neurotensin-induced mast cell degranulation. Our results show that neurotensin-induced mast cell degranulation in colonic explants is inhibited by the substance P (neurokinin-1) receptor antagonist CP-96,345, indicating that colonic mast activation in response to neurotensin involves release of substance P. We conclude that neurotensin plays a key role in the pathogenesis of C. difficile-induced colonic inflammation and mast cell activation.     

Iron supplementation affects the production of pro-inflammatory cytokines in IL-10 deficient mice

BACKGROUND: Iron supplements may increase disease activity in inflammatory bowel disease through the production of the hydroxyl radical because of its catalytic activity in the Fenton reaction. The purpose of this study was to assess the effect of dietary and locally administered iron in the IL-10 knock-out (-/-) mouse, a model of chronic inflammatory bowel disease. MATERIALS AND METHODS: IL10-/- and wild-type mice received a standard or a high-iron diet (35 mg kg(-1) ferrosulphate vs. 500 mg kg(-1) ferrosulphate) after weaning. After 4 weeks the mice were sacrificed. Furthermore, a group of adult IL-10 knock-out mice was given three iron-containing enema's (0.2 mL of 1 mM ferrous-ammonium sulphate) or phosphate buffered saline. These mice were sacrificed after 1 week. Production of pro-inflammatory cytokines by colon tissue cultures, haematological parameters and histology was determined to assess inflammatory activity. RESULTS: Oral as well as rectal administration of iron resulted in increased pro-inflammatory cytokine production in IL-10-/- mice. Neutrophil counts in IL10-/- on a high iron diet increased as well. No enhanced colonic inflammation was noted on histology after iron supplementation. CONCLUSION: We conclude that dietary or topical administered iron increases pro-inflammatory cytokine production in the colon of IL10-/- mice. No significant increase of histological intestinal inflammation was observed.     

Distribution of zinc in skeletal muscle and liver tissue in normal and dietary controlled alcoholic rats.

Zinc deficiency is a concomitant of both alcoholism and cirrhosis, as indicated by plasma and tissue measurements in man. The intracellular sites of zinc distribution, the site-specific nature of alcohol/cirrhosis-related depletion, and the alcohol exposure-zinc depletion time function have not been reported. Spague-Dawley rats (16) at 5 to 6 weeks were given normal chow and 20 per cent ethanol as sole water source. Control animals (14) had tap water. In rats killed at 2, 5, 9, and 14 weeks, zinc levels were measured by atomic absorption spectroscopy in plasma (p); muscle tissue (MT), cell sap (MCS) cell sap-free (MCSF), and mitochondria (MM); liver tissue (LT), cell sap (MCS), cell sap-free fraction (LCSF), And mitochondria (LM). Control zinc levels were stable in all tissues over the 14-week study; p = 108, plus or minus 10 mug per 100 ml., MT = 125 plus or minus 18, MCS = 30.3 plus or minus 3, MCSF = 70 plus or minus 6, MM = 209 plus or minus 17, LT = 198 plus or minus 29, LCS = 125 plus or minus 11.0, LCSF = 79.5 plus or minus 11.2, and LM = 291 plus or minus 30 mug per gram of dry tissue. Ethanol-fed rats showed marked decrease in all liver zinc fractions from the earliest (2 weeks) time, with the greatest depletion in LM to 35 per cent of control. MT and p zinc showed monotonic gradual declines at the rate of 3 per cent per week, becoming statistically different from control at 9 weeks in both tissues. Normal weight gain occurred in control animals: alcohol rats gained 52 per cent of control to 5 weeks, and showed no subsequent gain, weighing 62 per cent of control levels at 14 weeks. Liver mitochondria contain the highest zinc concentration, and are most rapidly depleted. MT and p declines follow hepatic zinc loss.     

Long-term prognostic effect of treatment in chronic non-ulcerative colitis and dyskinesia of the large intestine

The efficiency of stepwise therapeutic courses was assessed on the basis of clinical data, and histomorphologic and histochemical findings in large-intestinal mucosa of patients with chronic non-ulcerative colitis and colodyskinesia, followed up for 6 to 15 years. The duration of remissions in chronic colitis and colodyskinesia depends on the diet and regular meal-taking, adequate long-term combined treatment taking into account histomorphologic and morphometric parameters of large-intestinal inflammation, the extent of disturbance in intestinal microbiocenosis, and the clinical pattern of functional intestinal disorders. Recurrent acute attacks of colodyskinesia (its hyperkinetic variant, in particular) may result in inflammation of colonic mucosa.     

Dietary vitamin e supplementation attenuates hypertension in Dahl salt-sensitive rats

There is strong evidence that excess dietary salt (NaCl) is a major factor contributing to the development of hypertension. Salt-sensitive humans and rats develop hypertension even on a normal-salt diet. Salt sensitivity is associated with glucose intolerance and insulin resistance in both humans and animal models, including Dahl salt-sensitive (DSS) rats. In insulin resistance, impaired glucose metabolism leads to elevated endogenous aldehydes that bind sulfhydryl groups of membrane proteins, altering calcium channels, and increasing cytosolic free calcium ([Ca2+]i) and blood pressure. Vitamin E lowers tissue aldehyde conjugates, cytosolic [Ca2+]i, and blood pressure in spontaneously hypertensive rats and fructose-induced hypertensive Wistar Kyoto rats, models of insulin resistance. This study investigated the effect of a normal-salt diet on tissue aldehyde conjugates, cytosolic [Ca2+]i, and blood pressure in DSS rats and the effect of vitamin E supplementation on blood pressure and associated biochemical changes in these animals. Seven-week-old DSS rats were divided into 3 groups of 6 animals each and treated for 6 weeks with diets as follows: low-salt (0.4% NaCl); normal-salt (0.7% NaCl) and normal salt (0.7% NaCl) plus vitamin E (34 mg/kg feed). At completion, animals in the normal-salt group had significantly elevated systolic blood pressure, cytosolic [Ca2+]i, and tissue aldehyde conjugates compared with the low-salt group. They also showed smooth muscle cell hyperplasia in small arteries and arterioles of the kidney. Dietary vitamin E supplementation significantly attenuated the increase in systolic blood pressure and associated biochemical and histopathologic changes.     

Influence of dietary amiloride supplement on the zinc status of growing rats with marginal zinc supply

We divided 36 male pathogen-free Sprague-Dawley rats with an average live mass (LM) of 51 g into four treatment groups of nine animals each. They received for a period of 28 trial days a semisynthetic purified diet based on casein for ad libitum consumption, supplemented with 5 ppm zinc (groups 1–3) or 57 ppm zinc (group 4) as zinc sulfate. In addition to the diet, groups 2 and 3 were given a diuretic supplement of amiloride at the therpeutic dose rate (0.4 mg amiloride/kg LM^0.75 per day) or in a dosage corresponding to the chronic toxicity level (maximum tolerated dose; 0.8 mg amiloride/kg LM^0.75 per day). The supplementation with amiloride, acting as a potential Zn-binding ligand at the selected dosage levels, had no influence on the animals' live weight during the 28-day trial period; weight gain was determined solely by the dietary Zn concentration. Amiloride administered at the therapeutic or the maximum tolerated dose produced no evidence of a diminished Zn status in terms of the alkaline phosphatase activity in the serum or the Zn concentration in the serum, femur and testes. Medication with amiloride at the maximum tolerated dose even exerted a positive effect on the zinc supply status as demonstrated by the raised Zn concentration in the serum. This suggests that zinc supplementation may not be required during medication with amiloride in human medicine.     

Inhibition of adenosine deaminase attenuates inflammation in experimental colitis

Adenosine modulates the immune system and inhibits inflammation via reduction of cytokine biosynthesis and neutrophil functions. Drugs able to prevent adenosine catabolism could represent an innovative strategy to treat inflammatory bowel disorders. In this study, the effects of 4-amino-2-(2-hydroxy-1-decyl)pyrazole[3,4-d]pyrimidine (APP; novel adenosine deaminase inhibitor), erythro-9-(2-hydroxy-3-nonyl)adenine hydrochloride (EHNA; standard adenosine deaminase inhibitor), and dexamethasone were tested in rats with colitis induced by 2,4-dinitrobenzenesulfonic acid (DNBS). DNBS-treated animals received APP (5, 15, or 45 micromol/kg), EHNA (10, 30, or 90 micromol/kg), or dexamethasone (0.25 micromol/kg) i.p. for 7 days starting 1 day before colitis induction. DNBS caused bowel inflammation associated with decrease in food intake and body weight. Animals treated with APP or EHNA, but not dexamethasone, displayed greater food intake and weight gain than inflamed rats. Colitis induced increment in spleen weight, which was counteracted by all test drugs. DNBS administration was followed by macroscopic and microscopic inflammatory colonic alterations, which were ameliorated by APP, EHNA, or dexamethasone. In DNBS-treated rats, colonic myeloperoxidase, malondialdehyde, and tumor necrosis factor (TNF)-alpha levels as well as plasma TNF-alpha and interleukin-6 were increased. All test drugs lowered these phlogistic indexes. Inflamed colonic tissues displayed an increment of inducible nitric-oxide synthase mRNA, which was unaffected by APP or EHNA, but reduced by dexamethasone. Cyclooxygenase-2 expression was unaffected by DNBS or test drugs. These findings indicate that 1) inhibition of adenosine deaminase results in a significant attenuation of intestinal inflammation and 2) the novel compound APP is more effective than EHNA in reducing systemic and intestinal inflammatory alterations.     

The effect of prebiotic supplementation with inulin on cardiometabolic health: Rationale,design, and methods of a controlled feeding efficacy trial in adults at risk of type 2 diabetes

Prediabetes is associated with low-grade chronic inflammation that increases the risk for developing type 2 diabetes (T2D) and cardiovascular disease (CVD). An elevated lipopolysaccharide concentration, associated with dysbiosis of the intestinal microbiota, has been implicated in the development of both T2D and CVD. Selective modulation of the intestinal microbiota with prebiotics reduces intestinal permeability and endotoxin concentrations, inflammation, and metabolic dysfunction in rodents. The effect of prebiotic supplementation on cardio-metabolic function in humans at risk for T2D is not known. The primary aim of this trial is to determine the influence of prebiotic supplementation with inulin on insulin sensitivity and skeletal muscle metabolic flexibility in adults at risk for T2D. We hypothesize that prebiotic supplementation with inulin will improve insulin sensitivity and skeletal muscle metabolic flexibility. We will randomize 48 adults (40–75 yrs) with prediabetes or a score ≥ 5 on the American Diabetes Association (ADA) risk screener to 6 weeks of prebiotic supplementation with inulin (10 g/day) or placebo. Subjects will be provided with all food for the duration of the study, to avoid potential confounding through differences in dietary intake between individuals. Intestinal permeability, serum endotoxin concentrations, insulin sensitivity, skeletal muscle metabolic flexibility, endothelial function, arterial stiffness, and fecal bacterial composition will be measured at baseline and following treatment. The identification of prebiotic supplementation with inulin as an efficacious strategy for reducing cardio-metabolic risk in individuals at risk of T2D could impact clinical practice by informing dietary recommendations and increasing acceptance of prebiotics by the scientific and medical community.     

Glucagon-like peptide-2 and common therapeutics in a murine model of ulcerative colitis

The intestinal hormone glucagon-like peptide-2 (GLP-2) enhances bowel growth and reduces the severity of colonic injury in dextran sulfate sodium (DSS)-induced colitis in mice. In humans, ulcerative colitis is normally treated with aminosalicylates (ASAs) and corticosteroids (CSs) to reduce inflammation. However, whether the intestinotropic effects of GLP-2 are altered when combined with ASAs and/or CSs has not previously been explored. Thus, each agent [vehicle, ASA (sulfasalazine), CS (methylprednisolone), and ASA + CS] was administered alone or with GLP-2 to normal mice or mice with 3.5% DSS in the drinking water, for 10 consecutive days. GLP-2 treatment of DSS-mice increased survival and small intestinal weight (p < 0.05), and decreased body weight loss and colonic damage (p < 0.05). Furthermore, GLP-2 increased the number of proliferating cells in the colonic crypts of DSS-mice (p < 0.05). Administration of ASA, CS, or ASA + CS alone did not affect growth of the intestine in DSS-mice. However, administration of GLP-2 in combination with ASA was permissive for the beneficial effects of GLP-2 on survival and colonic damage, whereas CS treatment prevented these effects of GLP-2. Concomitant administration of GLP-2 with ASA + CS resulted in intermediate effects. No differences between colonic myeloperoxidase activity or IkappaB levels (an inhibitor of the nuclear factor-kappaB pro-inflammatory pathway) were found for any of these therapeutic agents. When taken together, the ability of GLP-2 to protect colonic mucosal architecture in DSS-colitis, and its effectiveness when given in combination with ASA, but not with CS, suggests a novel approach for the treatment of patients with colitis.     

JAM-A regulates permeability and inflammation in the intestine in vivo

Recent evidence has linked intestinal permeability to mucosal inflammation, but molecular studies are lacking. Candidate regulatory molecules localized within the tight junction (TJ) include Junctional Adhesion Molecule (JAM-A), which has been implicated in the regulation of barrier function and leukocyte migration. Thus, we analyzed the intestinal mucosa of JAM-A–deficient (JAM-A^−/−) mice for evidence of enhanced permeability and inflammation. Colonic mucosa from JAM-A^−/− mice had normal epithelial architecture but increased polymorphonuclear leukocyte infiltration and large lymphoid aggregates not seen in wild-type controls. Barrier function experiments revealed increased mucosal permeability, as indicated by enhanced dextran flux, and decreased transepithelial electrical resistance in JAM-A^−/− mice. The in vivo observations were epithelial specific, because monolayers of JAM-A^−/− epithelial cells also demonstrated increased permeability. Analyses of other TJ components revealed increased expression of claudin-10 and -15 in the colonic mucosa of JAM-A^−/− mice and in JAM-A small interfering RNA–treated epithelial cells. Given the observed increase in colonic inflammation and permeability, we assessed the susceptibility of JAM-A^−/− mice to the induction of colitis with dextran sulfate sodium (DSS). Although DSS-treated JAM-A^−/− animals had increased clinical disease compared with controls, colonic mucosa showed less injury and increased epithelial proliferation. These findings demonstrate a complex role of JAM-A in intestinal homeostasis by regulating epithelial permeability, inflammation, and proliferation.     

Different effects of dietary chenodeoxycholic acid and ursodeoxycholic acid on colonic adenylate cyclase in the rat

The oral administration of dietary chenodeoxycholic acid (1%), but not of ursodeoxycholic acid (1%), to male Sprague Dawley rats results in a significant increase in the colonic adenylate cyclase activity without any influence on the colonic cyclic-AMP phosphodiesterase activity. No effect of chronic bile acid feeding on the response of colonic adenylate cyclase to prostaglandin E2 and vasoactive intestinal peptide is observed. These data emphasize a dependence of the cyclic-AMP adenylate cyclase activation on the chemical structure of the bile acid. This may be of pathophysiologic relevance with respect to the frequently observed diarrhea as a side effect of oral chenodeoxycholic, but not ursodeoxycholic acid therapy for cholesterol gallstone dissolution in man.