5-ASA and lycopene decrease the oxidative stress and inflammation induced by iron in rats with colitis

Background Supplementation of 5-aminosalicylic acid (5-ASA) and of iron are among the principal therapies in patients with inflammatory bowel disease. Therapeutic iron, as well as heme iron from chronic mucosal bleeding, can increase iron-mediated oxidative stress in colitis. This study was designed to examine the influence of iron supplementation on histological expression and oxidative status relative to 5-ASA treatment and antioxidant treatment.Methods Colitis was induced using the iodoacetamide rat model, and rats were divided into different dietary groups of 6 rats each: 1, normal chow diet (control); 2, diet supplemented with iron; 3, iron supplementation and lycopene; 4, iron and -carotene; 5, 5-ASA; 6, 5-ASA and lycopene; 7, 5-ASA and iron; 8, 5-ASA, iron, and lycopene. The animals were killed after 3 days and the weight of the ulcerated area recorded. Mucosal specimens were histologically evaluated. Myeloperoxidase (MPO) was measured to evaluate inflammatory status (U/g). Malondialdehyde (MDA) was measured in colonic tissue (µmol/g) and superoxide dismutase (SOD) in erythrocytes to assess the degree of tissue oxidative stress.Results Significantly more severe colitis, including necrosis, ulceration, and hemorrhage, was seen in colonic biopsies of rats with colitis when iron was supplemented. This pathology was attenuated when iron was given in combination with 5-ASA and/or lycopene. There was no significant benefit from adding -carotene.Conclusions Iron supplementation can amplify the inflammatory response and subsequent mucosal damage in a rat model of colitis. We suggest that the resultant oxidative stress generated by iron supplementation leads to the extension and propagation of crypt abscesses, either through direct membrane disruption by lipid peroxidation or through the generation of secondary toxic oxidants. Simultaneous treatment with 5-ASA and/or lycopene minimizes the potential hazard of iron. Therefore, we suggest giving iron supplementation with 5-ASA or lycopene or both.     

Iron Supplementation May Aggravate Inflammatory Status of Colitis in a Rat Model

Iron supplementation is one of the principal therapies in inflammatory bowel disease. Iron is a major prooxidative agent; therefore therapeutic iron as well as heme iron from chronic mucosal bleeding can increase the iron-mediated oxidative stress in colitis by facilitating the Fenton reaction, namely production of hydroxyl radicals. In the present study colitis was induced in the iodoacetamide rat model. Forty male Whistar rats were divided into four groups, each group receiving a different diet regimen in parallel with colitis induction: Malondialdehyde was measured to assess the degree of tissue oxidative stress. There were microscopic changes, and significantly more severe colitis was seen in colonic biopsies when iron was supplemented. It was concluded that iron supplementation can amplify the inflammatory response and enhance the subsequent mucosal damage in a rat model of colitis. We suggest that the resultant oxidative stress generated by iron supplementation leads to the extension and propagation of crypt abscesses.     

Rebamipide, an Antiulcer Drug, Prevents DSS-Induced Colitis Formation in Rats

This study was conducted to investigate the efficacy of rebamipide against experimental colitis induced by dextran sulfate sodium (DSS) in a rat model of inflammatory bowel disease. Experimental colitis was induced in male Wistar rats by oral administration of 3% DSS solution for one week. The rats were provided with standard diet containing 0.105% rebamipide (160 mg/kg/day) for 1 week. In rats treated with rebamipide, clinical (body weight loss, bloody diarrhea, reduced physical activity, severe anemia, shortened colonic length, and perianal injury) and histopathological (pathological lesion score) findings of DSS colitis were significantly less than in rats with DSS colitis not treated with rebamipide. Rebamipide thus inhibited the induction of colitis. Rebamipide significantly reduced concentrations of both interleukin-1 and GRO/CINC-1 (IL-8-like substance) and cell infiltrates in colonic wall, in parallel with decreased activity of myeloperoxidase. It also reduced expression of IL-1 mRNA but did not influence expression of GRO/CINC-1 mRNA. The attenuation of colonic indices of colitis by rebamipide in this rat model suggests that this drug might have beneficial effects in the treatment of human ulcerative colitis. These effects of rebamipide are attributable to its inhibition of inflammatory cytokine-mediated granulocyte (neutrophil) infiltration into the colon.     

Lisofylline and lysophospholipids ameliorate experimental colitis in rats

BACKGROUND: Intestinal inflammatory processes initiate a chain reaction in which membrane-bound lipids generate eicosanoids and phospholipids. Bioactive lipid mediators play a pivotal role in the pathogenesis of intestinal inflammation and colonic mucosa from patients with inflammatory bowel disease contains high levels of phospholipids. Therefore, we investigated the effects of lysophosphatidic acid and lysophosphatidylethanolamine, two natural occurring phospholipids and lisofylline, which decreases lipid peroxidation, in an in-vivo model of intestinal inflammation. METHODS: Colitis was induced by rectal administration of ethanol and trinitrobenzene sulfonic acid in rats. Rats were treated once daily with either lysophosphatidic acid or lysophosphatidylethanolamine rectally or twice daily intraperitoneally with lisofylline following induction of colitis. Rats were sacrificed after 7 days and the effect of lysophosphatidic acid, lysophosphatidylethanolamine, and lisofylline on colonic damage and inflammation were assessed using standardized macroscopical and histological injury scores. RESULTS: Treatment with lysophosphatidic acid, lysophosphatidylethanolamine, and lisofylline significantly reduced the degree of inflammation and necrosis in the distal colon compared to control rats. In addition, the weight loss was significantly less in the treatment groups compared to controls. Histological studies revealed a significant reduction of epithelial damage and colonic inflammation. CONCLUSION: The administration of anti-inflammatory lysophospholipids and suppression of proinflammatory lipid metabolites by lisofylline may provide new approaches to ameliorate intestinal inflammation.     

The Effect of Melatonin on Plasma Markers of Inflammation and on Expression of Nuclear Factor-Kappa Beta in Acetic Acid-Induced Colitis in the Rat

Background and Aims

Melatonin may be involved in gastrointestinal tract physiology and could affect inflammation-related gastrointestinal disorders. Rat models of ulcerative colitis imply melatonin is beneficial. To determine potential pathophysiological mechanisms, we assessed colonic nuclear factor-kappa beta expression and measured serum levels of pentraxin-3, lipid peroxides, and total thiols in an acetic acid model of this disease.

Materials and Methods

Thirty rats were divided into five groups: a control group, an acetic acid-induced colitis group, a group treated with melatonin before colitis induction, a group treated short-term after colitis induction, and a group treated long-term after colitis induction. After four weeks, blood samples were taken for measurement of pentraxin-3, lipid peroxide, and total thiols. Sections of the colon were taken for histopathological examination and immunohistochemical detection of nuclear factor-kappa beta expression.

Results

Melatonin administration reduced nuclear factor-kappa beta immunohistochemical expression, reduced serum levels of lipid peroxide and pentraxin-3, and maintained serum levels of total thiols. However, in long-term treatment the protective effect of melatonin was not as marked.

Conclusion

Melatonin is effective in prevention and short-term treatment of the inflammatory process in acetic-acid induced colitis whereas the benefit of long-term treatment is unclear. Benefit may be linked to protection mechanisms against inflammatory processes by inhibiting the nuclear factor-kappa beta and conserving endogenous antioxidant reserves of total thiols, thus reducing the level of colonic damage possibly caused by lipid peroxides.     

Changes of colonic vasoactive intestinal peptide and cholinergic activity in rats with chemical colitis

The vasoactive intestinal peptide concentration was examined in the colonic wall and portal venous plasma of rats with chemical colitis by radioimmunoassay, and the colonic localization was determined with immunocytochemistry. Colonic acetylcholine esterase activity was also measured, and the response of vasoactive intestinal peptide to acetylcholine administration was determined. Colitis was induced by administration of dextran sulfate for three months. The chemical colitis was histologically similar to active human ulcerative colitis. We observed a significant increase of immunostained neurons and nerve fibers and a significant rise in the colonic wall vasoactive intestinal peptide content in chemical colitis rats, while plasma concentrations of the peptide did not change significantly. Colonic acetylcholine esterase activity was significantly elevated in colitis rats compared with control rats. Systemic administration of acetylcholine significantly increased the colonic and plasma vasoactive intestinal peptide concentrations in colitis rats. These findings demonstrated a positive association between colitis activity and an increase of vasoactive intestinal peptide and suggested that increased vagal tone promoted the peptide's release.     

Magnetic resonance imaging of experimental mouse colitis and association with inflammatory activity

BACKGROUND: Ulcerative colitis and Crohn's disease are the major chronic inflammatory bowel diseases affecting the gastrointestinal tract in humans. Imaging techniques such as endoscopy and computed tomography are used to monitor disease activity. Magnetic resonance imaging (MRI) is emerging as a diagnostic modality, and studies have shown that MRI can be used in the diagnostic procedure of patients with inflammatory bowel disease. The aim of the present study was to investigate the role of MRI in quantitatively reflecting inflammation in an experimental mouse colitis model. METHODS: Colonic inflammation was induced by exposing mice to dextran sulfate sodium. MRI was used to assess colon wall thickness, T2-weighted (T2w) signal, and contrast-enhanced T1-weighted (T1w) signal in inflamed and healthy animals in vivo. Haptoglobin and interleukin-1beta served as systemic and local inflammatory markers, and macroscopic ex vivo scoring of the colon was performed to assess colonic inflammation. RESULTS: Dextran sulfate sodium-exposed animals displayed increased levels of inflammatory markers and higher inflammatory score compared with healthy animals. Colon wall thickness and contrast-enhanced T1w signal were significantly increased in dextran sulfate sodium-exposed compared with healthy animals. In addition, the T2w signal was positively correlated with haptoglobin levels and colon wall thickness in the inflamed animals. CONCLUSIONS: Our results show that MRI can be used to depict healthy and inflamed mouse colon and that the T2w signal, contrast-enhanced T1w signal, and colon wall thickness may be used to characterize inflammation in experimental colitis. These potential biomarkers may be useful in the evaluation of putative drugs in longitudinal studies in both mice and humans.     

Tetradecylthioacetic Acid Attenuates Inflammation and Has Antioxidative Potential During Experimental Colitis in Rats

Background

The fatty acid analogue tetradecylthioacetic acid (TTA) is a moderate pan-activator of peroxisome proliferator-activated receptors (PPARs), and has in previous studies showed potential as an antioxidant and anti-inflammatory agent, both through PPAR and non-PPAR mediated mechanisms.

Aims

This study aimed to determine whether TTA could alleviate dextran sulfate sodium (DSS)-induced colitis in rats.

Methods

Male Wistar rats were fed a control diet (control- and DSS-group) or a diet supplemented with 0.4 % TTA (TTA + DSS-group) for 30 days, and DSS was added to the drinking water the last 7 days. Ultrasound measurements were performed at day 29. At day 30, rats were sacrificed and the distal colon was removed for histological evaluation and measurement of cytokine levels, oxidative damage, and gene expression.

Results

The disease activity index was not improved in the TTA + DSS-group compared to the DSS-group. However, ultrasound measurements showed a significantly reduced colonic wall thickening in the TTA + DSS-group. TNF-α, IL-1β, and IL-6 were reduced at the protein and mRNA level in the TTA + DSS-group. Moreover, TTA-treated rats demonstrated reduced colonic oxidative damage, while inducible nitric oxide synthase 2 mRNA expression was elevated in both the DSS- and TTA + DSS-groups. PPARγ signaling may be involved in the anti-inflammatory response to TTA, as Pparg mRNA expression was significantly upregulated in colon.

Conclusions

This study demonstrated that the pan-PPAR agonist TTA reduced colonic oxidative damage and cytokine levels in a rat model of colitis, and its potential to ameliorate colitis should be further explored.     

Paradoxical effects of constitutive human IL-32{gamma} in transgenic mice during experimental colitis

Inflammatory cytokines mediate inflammatory bowel diseases (IBDs) and cytokine blocking therapies often ameliorate the disease severity. IL-32 affects inflammation by increasing the production of IL-1, TNFα, and several chemokines. Here, we investigated the role of IL-32 in intestinal inflammation by generating a transgenic (TG) mouse expressing human IL-32γ (IL-32γ TG). Although IL-32γ TG mice are healthy, constitutive serum and colonic tissue levels of TNFα are elevated. Compared with wild-type (WT) mice, IL-32γ TG mice exhibited a modestly exacerbated acute inflammation early following the initiation of dextran sodium sulfate (DSS)-induced colitis. However, after 6 d, there was less colonic inflammation, reduced tissue loss, and improved survival rate compared with WT mice. Associated with attenuated tissue damage, colonic levels of TNFα and IL-6 were significantly reduced in the IL-32γ TG mice whereas IL-10 was elevated. Cultured colon explants from IL-32γ TG mice secreted higher levels of IL-10 compared with WT mice and lower levels of TNFα and IL-6. Constitutive levels of IL-32γ itself in colonic tissues were significantly lower following DSS colitis. Although the highest level of serum IL-32γ occurred on day 3 of colitis, IL-32 was below constitutive levels on day 9. The ability of IL-32γ to increase constitutive IL-10 likely reduces TNFα, IL-6, and IL-32 itself accounting for less inflammation. In humans with ulcerative colitis (UC), serum IL-32 is elevated and colonic biopsies contain IL-32 in inflamed tissues but not in uninvolved tissues. Thus IL-32γ emerges as an example of how innate inflammation worsens as well as protects intestinal integrity.     

Exacerbation of dextran sulfate sodium-induced colitis by dietary iron supplementation: role of NF-κB

Background In colitis, iron therapy may be given to treat anemia, but it may also be detrimental based on our previous studies using a rat model with colitis where iron supplementation increased disease activity and oxidative stress. This effect was partially reduced by an antioxidant.Aims The aim of this study was to further evaluate, in rats with dextran sulfate sodium (DSS)-induced colitis, the effect of iron on neutrophilic infiltration, cytokines and nuclear factor kappa-B (NF-κB)-associated inflammation and to determine whether the addition of vitamin E would be beneficial.Methods Colitis was induced with DSS at 50 g/l in drinking water for 7 days. DSS rats were randomized to the following: DSS, receiving a control, non-purified diet (iron, 270 mg and dl-α-tocopherol acetate, 49 mg/kg); DSS+iron (diet+iron, 3,000 mg/kg); DSS+vitamin E (diet+dl-α-tocopherol acetate, 2,000 mg/kg); or the DSS+iron+vitamin E. Colonic inflammation, myeloperoxidase activity (MPO), lipid peroxides (LPO), proinflammatory cytokines [tumor necrosis factor (TNF)-α, interleukin (IL)-1, IL-6] and NF-κB binding activity were measured.Results The DSS+iron group showed a significant increase in inflammatory scores, MPO, TNF-α, IL-1, LPO and NF-κB activity compared to DSS or DSS+vitamin E. The addition of vitamin E to iron (DSS+iron+vitamin E group) significantly reduced the inflammatory scores, TNF-α and IL-6. None of the other parameters were affected.Conclusion Iron increases disease activity in colitis, and this is associated with oxidative stress, neutrophilic infiltration, increased cytokines and activation of NF-κB. This detrimental effect was partially reduced by vitamin E.     

R-spondin1, a novel intestinotrophic mitogen, ameliorates experimental colitis in mice

BACKGROUND & AIMS: R-spondin 1 (Rspo1) is a novel epithelial mitogen that stimulates the growth of mucosa in both the small and large intestine. METHODS: We investigated the therapeutic potential of Rspo1 in ameliorating experimental colitis induced by dextran sulfate sodium (DSS) or trinitrobenzene sulfonic acid (TNBS) as well as nonsteroidal anti-inflammatory drug-induced colitis in interleukin (IL)-10-deficient mice. RESULTS: Therapeutic administration of recombinant Rspo1 protein reduced the loss of body weight, diarrhea, and rectal bleeding in a mouse model of acute or chronic DSS-induced colitis. Histologic evaluation revealed that Rspo1 improved mucosal integrity in both villus and/or crypt compartments in the small intestine and colon by stimulating crypt cell growth and mucosal regeneration in DSS-treated mice. Moreover, Rspo1 significantly reduced DSS-induced myeloperoxidase activity and inhibited the overproduction of proinflammatory cytokines, including tumor necrosis factor-alpha, IL-1alpha, IL-6, interferon-gamma, and granulocyte-macrophage colony-stimulating factor, in mouse intestinal tissue, indicating that Rspo1 may reduce DSS-induced inflammation by preserving the mucosal barrier function. Likewise, Rspo1 therapy also alleviated TNBS-induced interstitial inflammation and mucosal erosion in the mouse colon. Furthermore, Rspo1 substantially decreased the histopathologic severity of chronic enterocolitis by repairing crypt epithelium and simultaneously suppressing inflammatory infiltration in piroxicam-exposed IL-10(-/-) mice. Endogenous Rspo1 protein was localized to villus epithelium and crypt Paneth cells in mouse small intestine. CONCLUSIONS: Our results show that Rspo1 may be clinically useful in the therapeutic treatment of inflammatory bowel disease by stimulating crypt cell growth, accelerating mucosal regeneration, and restoring intestinal architecture.     

Expression of Alkaline Sphingomyelinase in Yeast Cells and Anti-inflammatory Effects of the Expressed Enzyme in a Rat Colitis Model

Alkaline sphingomyelinase (Alk-SMase) is a key enzyme in the intestinal tract for digestion of dietary sphingomyelin (SM), which generates lipid messengers with cell-cycle regulating effects. The enzyme is significantly decreased in ulcerative colitis and colon cancer. Based on this information, we wanted to investigate whether the enzyme had preventive effects against murine colitis. We report herein a method to express a biologically active Alk-SMase from Pichia pastoris yeast cells. By using the expressed enzyme to treat a rat colitis model induced by dextran sulfate sodium, we found that intrarectal instillation of Alk-SMase once daily for 1 week significantly reduced the inflammation score and protected the colonic epithelium from inflammatory destruction. We found a tendency for decreased tumor necrosis factor (TNF)-α expression in the Alk-SMase-treated group. This study, for the first time, provides a method to produce the enzyme and shows the potential applicability of the enzyme in the treatment of inflammatory bowel diseases.     

Immunostimulatory DNA ameliorates experimental and spontaneous murine colitis

BACKGROUND & AIMS: Impaired mucosal barrier, cytokine imbalance, and dysregulated CD4(+) T cells play important roles in the pathogenesis of experimental colitis and human inflammatory bowel disease. Immunostimulatory DNA sequences (ISS-DNA) and their synthetic oligonucleotide analogs (ISS-ODNs) are derived from bacterial DNA, are potent activators of innate immunity at systemic and mucosal sites, and can rescue cells from death inflicted by different agents. We hypothesized that these combined effects of ISS-DNA could inhibit the damage to the colonic mucosa in chemically induced colitis and thereby limit subsequent intestinal inflammation. METHODS: The protective and the anti-inflammatory effect of ISS-ODN administration were assessed in dextran sodium sulfate-induced colitis and in 2 models of hapten-induced colitis in Balb/c mice. Similarly, these effects of ISS-ODN were assessed in spontaneous colitis occurring in IL-10 knockout mice. RESULTS: In all models of experimental and spontaneous colitis examined, ISS-ODN administration ameliorated clinical, biochemical, and histologic scores of colonic inflammation. ISS-ODN administration inhibited the induction of colonic proinflammatory cytokines and chemokines and suppressed the induction of colonic matrix metalloproteinases in both dextran sodium sulfate- and hapten-induced colitis. CONCLUSIONS: As the colon is continuously exposed to bacterial DNA, these findings suggest a physiologic, anti-inflammatory role for immunostimulatory DNA in the GI tract. Immunostimulatory DNA deserves further evaluation for the treatment of human inflammatory bowel disease.     

Low-dose oral ferrous fumarate aggravated intestinal inflammation in rats with DSS-induced colitis

BACKGROUND: Oral ferrous iron therapy may reinforce intestinal inflammation. One possible mechanism is by catalyzing the production of reactive oxygen species. We studied the effects of low-dose oral ferrous fumarate on intestinal inflammation and plasma redox status in dextran sulfate sodium (DSS)-induced colitis in rats. METHODS: Forty male Wistar rats were divided into 5 groups: no intervention, sham gavage (distilled water), ferrous fumarate, DSS, and ferrous fumarate + DSS. Ferrous fumarate was dissolved in distilled water (0.60 mg Fe/kg per day) and administered by gavage on days 1 to 14. All rats were fed a standard diet. Colitis was induced by 5% DSS in drinking water on days 8 to 14. Rats were killed on day 16. Histologic colitis scores, fecal granulocyte marker protein, plasma malondialdehyde, plasma antioxidant vitamins, and plasma aminothiols were measured. RESULTS: DSS significantly increased histologic colitis scores (P < 0.001) and fecal granulocyte marker protein (P < 0.01). Ferrous fumarate further increased histologic colitis scores (P < 0.01) in DSS-induced colitis. DSS + ferrous fumarate decreased plasma vitamin A compared with controls (P < 0.01). Otherwise, no changes were seen in plasma malondialdehyde, plasma antioxidant vitamins, or plasma aminothiols. CONCLUSION: Low-dose oral ferrous iron enhanced intestinal inflammation in DSS-induced colitis in rats.     

Intracellular polyamine levels of intestinal epithelial cells in inflammatory bowel disease

Polyamines and their acetylated derivatives are a prerequisite for cellular metabolism and considered to be essential for proliferation and differentiation of the rapidly renewing intestinal mucosa. However, their role during mucosal inflammation is less clear. Polyamine concentrations were determined in isolated colonic epithelial cells (CECs) from endoscopic biopsies from 26 patients with inflammatory bowel disease (IBD) and 40 controls as well as colon samples from mice with and without acute or chronic dextran sodium sulfate (DSS)-induced colitis. In patients with ulcerative colitis, CEC spermidine and N8-acetylspermidine levels were significantly enhanced and spermine levels were reduced compared with healthy controls. A correlation of polyamine levels of patients with IBD with their corresponding inflammatory index revealed that increased concentrations of spermidine, N8-acetylspermidine, and N1-acetylspermine were found in CECs from the most severe inflamed mucosal areas. Using acute and chronic DSS colitis as a model of mucosal inflammation, we found enhanced levels of spermidine and spermine in acute colitis, whereas in chronic inflammation, CEC spermine concentrations were decreased. Our data indicate a lack of the anti-inflammatory polyamine spermine in severe ulcerative colitis and chronic DSS colitis, which may aggravate the disease. Increased spermidine and N8-acetylspermidine levels reflect increased uptake and metabolism likely due to accelerated proliferation and regeneration of CECs.     

Induction of Colitis in Young Rats by Dextran Sulfate Sodium

Models using dextran sulfate sodium (DSS) to induce experimental colitis in rodents have been performed mostly in adult animals. For this reason, we aimed to develop a model of colitis in young rats. DSS was administered to 30-day-old rats at concentrations ranging from 0.5 to 5% in drinking water. Young rats were remarkably sensitive to DSS since clinical symptoms rapidly rose with 5% DSS and most animals died after the fifth day. With 1 and 2% DSS, the severity of mucosal lesions was also high on day 7, the animals showing leukocytosis and anemia. At 0.5% DSS, leukocytosis and mild colonic lesions were induced. This concentration of DSS significantly increased myeloperoxidase activity and goblet cell number in the colon, indicating mucosal inflammation. Since food consumption was not reduced by 0.5% DSS, we suggest that this protocol can be used to study the effects of dietary supplements on intestinal inflammatory processes.     

Spatial organization of bacterial flora in normal and inflamed intestine： A fluorescence in situ hybridization study in mice

AIM: To study the role of intestinal flora in inflammatory bowel disease (IBD). METHODS: The spatial organization of intestinal flora was investigated in normal mice and in two models of murine colitis using fluorescence in situ hybridization. RESULTS: The murine small intestine was nearly bacteria-free. The normal colonic flora was organized in three distinct compartments (crypt, interlaced, and fecal), each with different bacterial compositions. Crypt bacteria were present in the cecum and proximal colon. The fecal compartment was composed of homogeneously mixed bacterial groups that directly contacted the colonic wall in the cecum but were separated from the proximal colonic wall by a dense interlaced layer. Beginning in the middle colon, a mucus gap of growing thickness physically separated all intestinal bacteria from contact with the epithelium. Colonic inflammation was accompanied with a depletion of bacteria within the fecal compartment, a reduced surface area in which feces had direct contact with the colonic wall, increased thickness and spread of the mucus gap, and massive increases of bacterial concentrations in the crypt and interlaced compartments. Adhesive and infiltrative bacteria were observed in inflamed colon only, with dominant Bacteroides species. CONCLUSION: The proximal and distal colons are functionally different organs with respect to the intestinal flora, representing a bioreactor and a segregation device. The highly organized structure of the colonic flora, its specific arrangement in different colonic segments, and its specialized response to inflammatory stimuli indicate that the intestinal flora is an innate part of host immunity that is under complex control.     

Down-regulation of endothelial adhesion molecules and leukocyte adhesion by treatment with superoxide dismutase is beneficial in chronic immune experimental colitis

Modulation of adhesion molecule expression that govern trafficking of leukocytes into the inflamed intestine is envisioned as a new strategy for treatment of inflammatory bowel disease (IBD). This study was designed to determine the impact of reducing oxidative stress on adhesion molecules expression and leukocyte recruitment in experimental chronic colitis. For that purpose, colitic interleukin-10 knockout and wild-type mice were studied. Groups of animals were treated with Cu/Zn superoxide dismutase (SOD1) 13 mg/kg/d or vehicle for either 7 or 14 days. Expression of vascular cell adhesion molecule-1 and mucosal addressin cell adhesion molecule-1 were determined; leukocyte-endothelial cell interactions in colonic venules were studied with intravital microscopy; and changes in colon pathology and biomarkers of colitis severity were determined. Development of colitis was associated with a marked increase in endothelial vascular cell adhesion molecule-1 and mucosal addressin cell adhesion molecule-1 expression, which were significantly reduced by treatment with SOD1. The increase in leukocyte rolling and adhesion in colonic venules of colitic mice were significantly reduced by administration of SOD1. This treatment markedly reduced colonic lipid hydroperoxidation, myeoloperoxidase activity, and plasma levels of serum amyloid A protein and resulted in significant, although modest, reductions in histologic damage score. The therapeutic value of SOD1 when administered prophylactically was assessed in the dextran sulfate sodium model of colitis with similar positive results. These results indicate that SOD1 affords significant amelioration of colonic inflammatory changes in experimental colitis. Down-regulation of adhesion molecule expression, reduction of lipid hydroperoxidation, and recruitment of leukocytes into the inflamed intestine contribute to this beneficial effect.     

Dietary resistant starch and chronic inflammatory bowel diseases

These studies were performed to test the benefit of resistant starch on ulcerative colitis via prebiotic and butyrate effects. Butyrate, propionate, and acetate are produced in the colon of mammals as a result of microbial fermentation of resistant starch and other dietary fibers. Butyrate plays an important role in the colonic mucosal growth and epithelial proliferation. A reduction in the colonic butyrate level induces chronic mucosal atrophy. Short-chain fatty acid enemas increase mucosal generation, crypt length, and DNA content of the colonocytes. They also ameliorate symptoms of ulcerative colitis in human patients and rats injected with trinitrobenzene sulfonic acid (TNBS). Butyrate, and also to a lesser degree propionate, are substrates for the aerobic energy metabolism, and trophic factors of the colonocytes. Adverse butyrate effects occur in normal and neoplastic colonic cells. In normal cells, butyrate induces proliferation at the crypt base, while inhibiting proliferation at the crypt surface. In neoplastic cells, butyrate inhibits DNA synthesis and arrests cell growth in the G1 phase of the cell cycle. The improvement of the TNBS-induced colonic inflammation occurred earlier in the resistant starch (RS)-fed rats than in the RS-free group. This benefit coincided with activation of colonic epithelial cell proliferation and the subsequent restoration of apoptosis. The noncollagenous basement membrane protein laminin was regenerated initially in the RS-fed group, demonstrating what could be a considered lower damage to the intestinal barrier function. The calculation of intestinal short-chain fatty acid absorption confirmed this conclusion. The uptake of short-chain fatty acids in the colon is strongly inhibited in the RS-free group, but only slightly reduced in the animals fed with RS. Additionally, RS enhanced the growth of intestinal bacteria assumed to promote health. Further studies involving patients suffering from ulcerative colitis are necessary to determine the importance of RS in the therapy of a number of intestinal diseases and the maintenance of health. Accepted: 11 August 1999     

Enhanced survival and mucosal repair after dextran sodium sulfate-induced colitis in transgenic mice that overexpress growth hormone

BACKGROUND & AIMS: Growth hormone (GH) is used as therapy for inflammatory bowel disease (IBD), but the specific effects on intestine are unknown. Transgenic mice overexpressing GH (MT1-bGH-TG) were used to test whether increased plasma GH levels alter inflammation or crypt damage during dextran sodium sulfate (DSS)-induced colitis. METHODS: MT1-bGH-TG and wild-type (WT) littermates were given 3% DSS for 5 days followed by up to 10 days of recovery. Colitis and epithelial cell proliferation were evaluated histologically. Plasma insulin-like growth factor (IGF)-I and colonic IGF-I, interleukin (IL)-1beta, and intestinal trefoil factor (ITF) messenger RNAs (mRNAs) were measured. RESULTS: DSS induced similar disease onset in MT1-bGH-TG and WT. More MT1-bGH-TG survived than WT. By recovery day 7, MT1-bGH-TG had less inflammation and crypt damage, elevated plasma IGF-I, and increased colonic ITF expression relative to WT. Colonic IL-1beta was elevated in DSS-treated MT1-bGH-TG and WT, but IL-1beta mRNA abundance correlated with disease only in WT. MT1-bGH-TG showed earlier increases in epithelial cell proliferation than WT during recovery but only WT showed atypical repair. CONCLUSIONS: GH does not alter susceptibility to acute DSS-induced colitis but enhances survival, remission of inflammation, and mucosal repair during recovery. GH therapy may be beneficial during active IBD by improving mucosal repair.