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PubMed1998

iNOS expression in human intestinal microvascular endothelial cells inhibits leukocyte adhesion.

Increased nitric oxide (NO) production by inducible nitric oxide synthase (iNOS) has been associated with intestinal inflammation, including human inflammatory bowel disease. However, NO can downregulate endothelial activation and leukocyte adhesion, critical steps in the inflammatory response. Using primary cultures of human intestinal microvascular endothelial cells (HIMEC), we determined the role of NO in the regulation of HIMEC activation and interaction with leukocytes. Both nonselective (NG-monomethyl-L-arginine) and specific (N-iminoethyl-L-lysine) competitive inhibitors of iNOS significantly increased binding of leukocytes by HIMEC activated with cytokines and lipopolysaccharide. Increased adhesion was reversible with the NOS substrate L-arginine and was not observed in human umbilical vein endothelial cells (HUVEC). Activation of HIMEC significantly upregulated HIMEC iNOS expression and NO production. NOS inhibitors did not augment cell adhesion molecule levels in activated HIMEC but did result in sustained increases in intracellular reactive oxygen species. In addition, antioxidant compounds reversed the effect of NOS inhibitors on HIMEC-leukocyte interaction. Taken together, these data suggest that after HIMEC activation, iNOS-derived NO is an endogenous antioxidant, downregulating leukocyte binding and potentially downregulating intestinal inflammation.

Arginine↗
PubMed2002

Effect of Pentavac and measles-mumps-rubella (MMR) vaccination on the intestine.

BACKGROUND: The safety of infant vaccination has been questioned in recent years. In particular it has been suggested that the measles, mumps, and rubella (MMR) vaccination leads to brain damage manifesting as autism consequent to the development of an "enterocolitis" in the immediate post-vaccination period. AIM: To assess if MMR vaccination is associated with subclinical intestinal inflammation, which is central to the autistic "enterocolitis" theory. METHODS: We studied 109/58 infants, before and two and four weeks after immunisation with Pentavac and MMR vaccines, for the presence of intestinal inflammation (faecal calprotectin). RESULTS: Neither vaccination was associated with any significant increase in faecal calprotectin concentrations. CONCLUSIONS: The failure of the MMR vaccination to cause an intestinal inflammatory response provides evidence against the proposed gut-brain interaction that is central to the autistic "enterocolitis" hypothesis.

Analysis of Variance↗
PubMed2005

Decreased intestinal polyp multiplicity is related to exercise mode and gender in ApcMin/+ mice.

Moderate-intensity treadmill running can alter male Apc(Min/+) mouse polyp formation. This purpose of this study was to examine whether exercise mode differentially affects Apc(Min/+) mouse intestinal polyp development in male and female mice. Male and female Apc(Min/+) mice were randomly assigned to control, treadmill (18 m/min; 60 min/day; 6 days/wk), or voluntary wheel running (24-h access) groups. Nine weeks of training decreased total intestinal polyps by 29% in male treadmill runners (66 +/- 9; P = 0.038) compared with male controls (93 +/- 7). The number of large polyps (>/=1-mm diameter) were also reduced by 38% in male treadmill runners (49 +/- 6; P = 0.005) compared with male controls (79 +/- 6). Treadmill running in female Apc(Min/+) mice and wheel running in both genders did not affect polyp number or size. Spleen weight decreased in male treadmill runners (91 +/- 9 mg; P = 0.011) and wheel runners (75 +/- 6 mg; P = 0.004) compared with controls (141 +/- 13 mg). Plasma IL-6 was reduced by 96% in male treadmill runners (1.2 +/- 0.6 pg/ml) and 78% in male wheel runners (6.6 +/- 3.3 pg/ml) compared with control mice (27.9 +/- 2.8 pg/ml; P < 0.05). Female mice responded similarly with an 86% decrease in plasma IL-6 with treadmill running (3.2 +/- 1.2 pg/ml) and 90% decrease with wheel running (2.9 +/- 2.0 pg/ml) compared with control mice (21.1 +/- 5.3 pg/ml; P < 0.05). The crypt depth-to-villus height ratio in the intestine, an indirect marker of intestinal inflammation, decreased by 21 (P = 0.024) and 24% (P = 0.029), respectively, in male and female treadmill runners but not wheel runners. Physical activity-induced attenuation of intestinal polyp number and size is dependent on exercise mode and differs between genders. The modulation of systemic and intestinal inflammation may also depend on exercise mode.

Adenomatous Polyposis Coli Protein↗
PubMed2005

Cyclical upregulated iNOS and long-term downregulated nNOS are the bases for relapse and quiescent phases in a rat model of IBD.

We previously reported that indomethacin induces a chronic intestinal inflammation in the rat where the cyclical characteristic phases of Crohn's disease are manifested with a few days' interval and lasting for several months: active phase (high inflammation, hypomotility, bacterial translocation) and reactive phase (low inflammation, hypermotility, no bacterial translocation). In this study, we investigated the possible role of both constitutive and inducible isoforms of nitric oxide (NO) synthase (NOS) and cyclooxygenase (COX) in the cyclicity of active and reactive phases in rats with chronic intestinal inflammation. Rats selected at either active or reactive phases and from 2 to 60 days after indomethacin treatment were used. mRNA expression of both constitutive and inducible NOS and COX isoforms in each phase was evaluated by RT-PCR and cellular enzyme localization by immunohistochemistry. The effects of different COX and NOS inhibitors on the intestinal motor activity were tested. mRNA expression of COX-1 was not modified by inflammation, whereas mRNA expression of neuronal NOS was reduced in all indomethacin-treated rats. In contrast, NOS and COX inducible forms showed a cyclical oscillation. mRNA expression and protein of both iNOS and COX-2 increased only during active phases. The intestinal hypomotility associated with active phases was turned into hypermotility after the administration of selective iNOS inhibitors. Sustained downregulation of constitutive NOS caused hypermotility, possibly as a defense mechanism. However, this reaction was masked during the active phases due to the inhibitory effects of NO resulting from the increased levels of the inducible NOS isoform.

Animals↗
PubMed2003

Immune networks in animal models of inflammatory bowel disease.

The animal models of inflammatory bowel disease provide a framework to define the immunopathogenesis of intestinal inflammation. Studies in these models support the hypothesis that exaggerated immune responses to normal enteric microflora are involved in the initiation and perpetuation of chronic intestinal inflammation. A major pathway involves development of acquired immune responses by the interactions of CD4+ T-cell receptor alphabeta T cells with antigen-presenting cells (dendritic cells). Immunoregulatory cells, including Tr1 cells, Th3 cells, and CD4+ CD25+ T cells and B cells, directly or indirectly affect the T-cell receptor alphabeta T cell-induced immune responses and bridge innate and acquired immunity. The study of these complicated immune networks provides the rationale for the development of new therapeutic interventions in inflammatory bowel disease.

Animals↗
PubMed1986

Increased intestinal permeability in patients with Crohn's disease and their relatives. A possible etiologic factor.

The cause of Crohn's disease is unknown, although alterations in intestinal permeability may play a primary role. Because we were interested in permeability changes that occur before the onset of intestinal inflammation, we took advantage of the known genetic predisposition to this disease and studied not only patients with Crohn's disease, but their clinically unaffected relatives as well. Intestinal permeability was assessed using the marker polyethylene glycol-400 ingested with a standard meal. We found that 17 normal volunteers absorbed 215 +/- 29.6 mg (mean +/- SE), whereas 11 patients with Crohn's disease absorbed 514 +/- 94.7 mg and their 32 healthy relatives absorbed 566 +/- 62.4 mg. The twofold increase in permeability of patients and their relatives (p less than 0.005 compared with controls) indicates that the intestinal defect in the ability to exclude larger sized molecules is not secondary to clinically recognized intestinal inflammation, but is a primary defect that may be an etiologic factor in this disease.

Adolescent↗
PubMed2000

Immunotherapy of inflammatory bowel diseases: current concepts and future perspectives.

The etiology and the pathogenesis of inflammatory bowel diseases (IBD), e.g. Crohn's disease and ulcerative colitis are still not completely understood. However, there is growing evidence that an alteration of the mucosal immune system towards luminal antigens in a genetically susceptible host plays a key role in the pathogenesis of IBD. In particular, cytokines produced by intestinal epithelial cells, lamina propria macrophages and CD4+ T cells appear to contribute to the initiation and perpetuation of intestinal inflammation in IBD. This review focuses on the role of the mucosal immune system in the pathogenesis of IBD and potential novel immunotherapeutic strategies for chronic intestinal inflammation. Such strategies include recombinant antiinflammatory cytokines, neutralizing antibodies or fusion proteins, antisense oligonucleotides and adenoviral gene transfer.

Animals↗
PubMed1990

[Mechanisms of T-cell-mediated hypersensitivity in mice infected with the intestinal helminth Trichinella spiralis].

Intestinal hypersensitivity reactions during parasitic helminth infections are T-cell-dependent. Little is known about the characteristics of T-cells that initiate and regulate intestinal inflammation or about how they do this. In this paper data are presented that indicate that during Trichinella spiralis infections in mice T-cells regulate intestinal inflammation in the same way that they regulate delayed-type hypersensitivity reactions in the skin and cellular immune responses against tumors.

Animals↗
PubMed2000

Enteroaggregative Escherichia coli expresses a novel flagellin that causes IL-8 release from intestinal epithelial cells.

Enteroaggregative Escherichia coli (EAEC) is an emerging cause of acute and persistent diarrhea worldwide. EAEC infections are associated with intestinal inflammation and growth impairment in infected children, even in the absence of diarrhea. We previously reported that prototype EAEC strains rapidly induce IL-8 production by Caco-2 intestinal epithelial cells, and that this effect is mediated by a soluble, heat-stable factor released by these bacteria in culture. We herein report the cloning, sequencing, and expression of this biologically active IL-8-releasing factor from EAEC, and its identification as a flagellin that is unique among known expressed proteins. Flagella purified from EAEC 042 and several other EAEC isolates potently release IL-8 from Caco-2 cells; an engineered aflagellar mutant of 042 does not release IL-8. Finally, cloned EAEC flagellin expressed in nonpathogenic E. coli as a polyhistidine-tagged fusion protein maintains its proinflammatory activity. These findings demonstrate a major new means by which EAEC may cause intestinal inflammation, persistent diarrhea, and growth impairment that characterize human infection with these organisms. Furthermore, they open new approaches for diagnosis and vaccine development. This novel pathogenic mechanism of EAEC extends an emerging paradigm of bacterial flagella as inflammatory stimuli.

Amino Acid Sequence↗
PubMed2001

Mucosal barrier and immune mediators.

The intestinal mucosa functions is an immunologic organ that plays a major role in the development of oral tolerance and host-defense mechanisms. Antigens must cross the intestinal epithelium in a controlled manner to interact with dendritic antigen-presenting cells, because bacteria or their products are a primary risk factor for the development of intestinal inflammation. Therefore, the regulation of the intestinal epithelial cell barrier is central to the development of intestinal immunity and inflammation, but the involved mechanisms are largely unknown. Intestinal barrier function relies on the formation of tight junctions at the apical contact areas of intestinal epithelial cells. Tight junctions have a highly dynamic structure whose permeability, assembly, or disassembly can be regulated by a variety of cellular and metabolic mediators, including cytokines, which have major functions in the immune system. Immune modulators control tight junction dependent intestinal barrier function during development, wound healing, and pathologic processes such as cancer, infection, and chronic inflammation.

Journal Article↗
PubMed2005

Transfer of colitis by Galphai2-deficient T lymphocytes: impact of subpopulations and tissue origin.

To elucidate the potential cell population(s) involved in the induction of colitis in inhibitory G protein Galphai2(-/-) mice, Galphai2-deficient or competent bone marrow or splenic and mesenteric lymph node (MLN) T cells were transferred into immunodeficient mice. The mice were followed up to 23 weeks after transfer, recording changes in body weight. Colitis was graded on hematoxylin and eosin-stained colonic tissue, and production of serum interleukin-18 and colon-derived interferon-gamma was measured using ELISA. After adoptive transfer of Galphai2(-/-) bone marrow, severe colitis developed in irradiated wild type recipients, whereas irradiated Galphai2(-/-) mice increased their life span more than 3 times after transfer of wild type bone marrow, accompanied by significant amelioration of colitis. Neither purified Galphai2(-/-) CD4(+), nor CD8(+) splenic or MLN-derived T cells could induce colitis in recombination-activating gene V(RAG) 2(-/-) recipient mice, whereas transfer of splenic Galphai2(-/-) CD3(+) T cells induced severe colitis. In contrast, transfer of Galphai2(-/-) CD3(+) T cells from the MLN caused only minor histopathological changes in the intestinal mucosa. Finally, serum levels of interleukin-18 and interferon-gamma production from colonic tissue cultures correlated well with disease severity. Our results show that bone marrow transplantation can prolong the life of Galphai2(-/-) mice and ameliorate intestinal inflammation. Splenic CD4(+) or CD8(+) T cells on their own were poor inducers of colitis, whereas the combination of both was highly involved in the induction of intestinal inflammation. Furthermore, we show that the tissue origin of CD3(+) T cells is critical for their potency to induce colitis.

Animals↗
PubMed1994

Studies on the enteropathy associated with primary hypogammaglobulinaemia.

Twelve patients with primary hypogammaglobulinaemia with diarrhoea not associated with known microbial pathogens were investigated. Histological evidence of inflammation was common in the stomach and jejunum. Moreover, eight of 10 patients undergoing colonoscopy had low grade 'microscopic colitis' with raised intraepithelial lymphocytes and an intact crypt architecture. Five of 12 patients had small intestinal inflammation on 111indium leucocyte scintigrams and all had increased faecal excretion (normal < 1%) of 111indium (over four days), which varied in intensity from mild (faecal excretion of 111indium = 1-3%) to that comparable with moderately active (7-14.5%) Crohn's disease. Three patients had small intestinal strictures superficially resembling Crohn's disease. Histologically, however, these lacked characteristic diagnostic features of Crohn's disease in two and the third patient had non-steroidal anti-inflammatory drug induced diaphragm like strictures. Six of seven who were most severely symptomatic were successfully treated with an elemental diet with rapid improvement of symptoms. The faecal excretion of 111indium was repeated in five and all improved but histologically the colitis remained unchanged. These studies show that some patients with primary hypogammaglobulinaemia have intestinal inflammation unlike that found in classic inflammatory bowel disease. Elemental diet is a useful temporary measure in the treatment of these patients.

Agammaglobulinemia↗
PubMed2000

Inflammation and intestinal metaplasia of the gastric cardia: Helicobacter pylori, gastroesophageal reflux disease, or both.

The gastric cardia is a microscopic zone that is normally found in the most proximal portion of the stomach, although cardiac-type mucosa may arise in the distal esophagus as a metaplastic phenomenon secondary to gastroesophageal reflux disease (GERD). Inflammation of the native gastric cardia is strongly associated with Helicobacter pylori infection, although there may be a second form of 'carditis' in which metaplastic cardiac-type mucosa becomes inflamed secondary to GERD. Intestinal metaplasia of the cardia may be difficult to recognize because of the difficulty in accurately identifying the esophagogastric junction by endoscopy and the histologic similarities of intestinal metaplasia in the proximal stomach and distal esophagus. However, cytokeratin 7 and 20 immunoreactivity patterns appear to be useful in distinguishing between these forms of intestinal metaplasia. The preponderance of data suggests that intestinal metaplasia of the cardia is associated with H. pylori infection as opposed to GERD, and preliminary data suggest a lower risk of progression to dysplasia and adenocarcinoma when compared to intestinal metaplasia of the distal esophagus.

Cardia↗
PubMed1999

A synthetic mimetic of CD4 is able to suppress disease in a rodent model of immune colitis.

CD4+ mucosal T cells mediate the intestinal inflammation in Crohn's disease and may serve as an important target for immune intervention. Here we assessed the therapeutic effect of a synthetic mimetic of CD4 designed to mimic both the sequence and conformation of the complementarity-determining region 3 of murine CD4 V1 domain (rD-mPGPtide) in a mouse colitis model using immunization with 2,4,6-trinitrobenzene sulfonic acid (TNB). i.v. administration of the rD-mPGPtide but not control scrambled peptide could suppress severe inflammation in the chronic colitis mouse model. After treatment with the rD-mPGPtide, a striking improvement of diarrhea and acute wasting disease was observed with decreased mortality. Serum anti-TNB antibody titers, CD45RBlowCD4+ T cells in the lamina propria and IFN-gamma mRNA expression in the mucosa were significantly decreased with the rD-mPGPtide treatment. Anti-CD4 antibody also suppressed disease by depletion of CD45RBhighCD4+ T cells in the colonic mucosa. The observation that the synthetically engineered analogue of murine CD4 inhibits inflammation in a rodent disease model by different mechanisms than anti-CD4 antibody suggests that a human version of this peptide has potential therapeutic utility in CD4+ mucosal T cell-mediated intestinal inflammation in Crohn's disease.

Animals↗
PubMed2006

Interleukin 25 regulates type 2 cytokine-dependent immunity and limits chronic inflammation in the gastrointestinal tract.

The cytokine interleukin (IL) 25 has been implicated in the initiation of type 2 immunity by driving the expression of type 2 cytokines such as IL-5 and IL-13, although its role in the regulation of immunity and infection-induced inflammation is unknown. Here, we identify a dual function for IL-25: first, in promoting type 2 cytokine-dependent immunity to gastrointestinal helminth infection and, second, in limiting proinflammatory cytokine production and chronic intestinal inflammation. Treatment of genetically susceptible mice with exogenous IL-25 promoted type 2 cytokine responses and immunity to Trichuris. IL-25 was constitutively expressed by CD4+ and CD8+ T cells in the gut of mouse strains that are resistant to Trichuris, and IL-25-deficient mice on a genetically resistant background failed to develop a type 2 immune response or eradicate infection. Furthermore, chronically infected IL-25(-/-) mice developed severe infection-induced intestinal inflammation associated with heightened expression of interferon-gamma and IL-17, identifying a role for IL-25 in limiting pathologic inflammation at mucosal sites. Therefore, IL-25 is not only a critical mediator of type 2 immunity, but is also required for the regulation of inflammation in the gastrointestinal tract.

Animals↗
PubMed1997

Beneficial effect of ursodeoxycholic acid on mucosal damage in trinitrobenzene sulphonic acid-induced colitis.

BACKGROUND: Recently we observed that ursodeoxycholic acid (UDCA) ameliorates an experimental small intestinal inflammation induced by indomethacin in the rat. In this study, we have tested whether ursodeoxycholic acid also reduces mucosal damage in the bile-independent trinitrobenzene sulphonic acid (TNB) model of experimental colitis. METHODS: Intestinal inflammation (colitis) was induced in male Sprague-Dawley rats (250-300 g) by intracolonic administration of TNB (30 mg in 50% ethanol). Rats were treated with UDCA (10 mg/kg) either for 3 days starting with the administration of TNB for an acute inflammation (n = 11) or for 8 days starting one day after induction of colitis related to a more acute/chronic inflammation (n = 11). Rats were sacrificed at day 3 or day 9, respectively. Healing of induced colitis was assessed by macroscopic and blinded microscopic analysis as well as by measurement of bowel wet weight, daily body weight, and myeloperoxidase activity. All examinations were separately performed in three colon segments (S1 3-5 cm, S2 5.5-8 cm and S3 8.5-11 cm from anus). RESULTS: UDCA treatment significantly reduced macroscopically and microscopically detectable injury in acute inflammation in segments 1 and 2. The colitis-rats with acute/chronic inflammation had less marked mucosal damage. Nevertheless, UDCA treatment led to a significant decrease of visible injury parameters which was seen exclusively at the area of maximal ulceration (S2). Furthermore, a significant increase in body weight of UDCA-treated TNB rats compared to controls from day 5 on was found. CONCLUSION: Ursodeoxycholic acid attenuates the severity of acute inflammation and inhibits the development of acute/chronic inflammation predominantly around the area of maximal ulceration in TNB-induced colitis. In addition to our previous studies and results in indomethacin induced enteritis, these data may provide a rationale for studying how UDCA modulates functions of immune cells in the colonic mucosa.

Animals↗
PubMed2003

Attenuated mild colonic inflammation and improved survival from severe DSS-colitis of transgenic Cu/Zn-SOD mice.

Mucosal tissue damage in chronic inflammatory bowel disease (IBD) is partly caused by an enduring exposure to excessive amounts of reactive oxygen metabolites (ROM). To protect themselves from the toxic effects of ROM, most intestinal cell types constitutively express the highly specific, key ROM-neutralizing cytosolic enzyme Cu/Zn-superoxide dismutase (SOD). Under inflammatory conditions, however, its protein and activity levels have consistently been reported as being decreased. To elucidate a direct functional relationship between intracellular Cu/Zn-SOD expression and intestinal inflammation, we investigated the effects of transgenic human Cu/Zn-SOD overexpression in acute and chronic murine dextran sodium sulfate (DSS)-induced colitis. When subjected to a mild form of acute colitis, the Cu/Zn-SOD overexpressing mice showed a significantly lower colonic activity of neutrophilic myeloperoxidase (MPO) than their nontransgenic littermates. This difference was particularly evident in the male animals. In contrast, a severe acute colitis did not lead to any differences in MPO activity between both groups. Yet, when the animals were subsequently allowed to recover, MPO levels were again significantly lower in the transgenes, suggesting an involvement of Cu/Zn-SOD in, particularly, the clearance of neutrophils. Specific, immunohistochemical identification of neutrophils confirmed the validity of the MPO activity measurements. In addition, transgenic animals showed a remarkable survival benefit from severe DSS colitis over their nontransgenic littermates, particularly during or shortly after the acute inflammatory phase. During the chronic inflammatory phase, which was not characterized by massive neutrophil infiltration, no effects of Cu/Zn-SOD overexpression were noted. Paradoxically, overexpression of Cu/Zn-SOD did not obviously improve the colitis-related (oxidative) injury or symptoms at any stage of the experiment. Surprisingly, however, we did observe a pronounced male gender preference for DSS susceptibility that was reflected by increased male colitis mortality. Our findings provide direct in vivo evidence for a protective, neutrophil-related role for Cu/Zn-SOD in intestinal inflammation. As such, they support the concept of SOD-based (adjunct) antioxidant treatment strategies for inflammatory bowel disease.

Acute Disease↗