Effect of methylprednisolone on small bowel, spleen and liver changes in a murine model of inflammatory bowel disease

Effect of azithromycin on acute inflammatory lesions and colonic bacterial load in a murine model of experimental colitis

BACKGROUND

The aim of this study was to investigate the effect of the macrolide antibiotic azithromycin on mucosal changes and colonic bacterial load in a murine model of colitis.

METHODS

Colitis was induced in CD1 mice using enema of 0.2% solution of dinitrofluorobenzene, combined with skin sensitization. Four experimental groups of animals (N = 10 per group) were treated with 50 mg/kg/day azithromycin (AZ) or metronidazole (MN) perorally, starting 24 h before (AZ-1, MN-1) or 6 h after (AZ+1, MN+1) induction of colitis and for consecutive 5 days. Additional experimental mice group was treated with 10 mg/kg/day methylprednisolone intraperitoneally after induction of experimental colitis in the same manner (MP). Two control groups consisted of healthy animals (C) that received the challenge enema with phosphate-buffered saline (PBS) and animals with experimental colitis (chall) treated with equivolume of PBS perorally. Clinical score (0-5) and histopathologic score (0-30) were used to assess inflammatory changes, and colon washings were used to determine changes in bacterial load.

RESULTS

The anti-inflammatory effect of azithromycin did not differ from the effect of methylprednisolone, when compared with control group with experimental colitis. Metronidazole did not show a significant anti-inflammatory effect. Number of colonic bacteria did not differ significantly between control and experimental groups of animals.

CONCLUSIONS

We documented the anti-inflammatory effect of azithromycin in a murine model of acute colitis, suggesting that effects were targeted to oxidative burst and on mucosal/bacterial interface, independent of luminal bacterial load. Further studies should be focused on effect of azithromycin on the role of bacterial biofilm in perpetuation of chronic intestinal inflammation.

Macroscopic, microscopic and biochemical characterisation of spontaneous colitis in a transgenic mouse, deficient in the multiple drug resistance 1a gene

1 A novel animal model of spontaneous colonic inflammation, the multiple drug-resistant (mdr1) a(-/-) mouse, was identified by Panwala and colleagues in 1998. The aim of our study was to further characterise this model, specifically by measuring cytokines that have been implicated in inflammatory bowel disease (IBD) (IL-8 and IFN-gamma) in the colon/rectum of mdr1a(-/-) mice, and by determining the sensitivity of these, together with the macroscopic, microscopic and disease signs of colitis, to dexamethasone (0.05, 0.3 and 2 mg kg(-1) subcutaneously (s.c.) daily for 7 days). 2 All mdr1a(-/-) mice had microscopic evidence of inflammation in the caecum and colon/rectum, while control mice with the same genetic background did not. Significant increases in colon/rectum and caecal weights and also in cytokine levels (both IFN-gamma and IL-8) in homogenised colon/rectum were observed in mdr1a(-/-) mice compared to mdr1a(+/+) mice. 3 Dexamethasone reduced the increases in tissue weights and also microscopic grading of colitis severity, but had no effect on IFN-gamma or IL-8. 4 This study supports the similarity of the gastrointestinal inflammation present in mdr1a(-/-) mice to that of human IBD, in particular Crohn's disease. This has been demonstrated at the macroscopic and microscopic levels, and was supported further by elevations in colonic levels of IFN-gamma and IL-8 and the disease signs observed. The incidence of colitis was much higher than previously reported, with all mice having microscopic evidence of colitis. The limited variance between animals in the parameters measured suggests that this model is reproducible.

Changes of CD8+CD28- T regulatory cells in rat model of colitis induced by 2,4-dinitrofluorobenzene

AIM: To determine the changes of CD8+ T subsets especially CD8+CD28- T regulatory cells in rat model of experimental colitis induced by 2,4-dinitrofluorobenzene (DNFB).

METHODS: The rat model of experimental colitis was induced by enema with DNFB. Ten days later, colonic intraepithelial and splenic lymphocytes were isolated from colitis animals (n = 16) and controls (n = 8). The proportion of CD8+ T cells, CD8+CD28+ T cells and CD8+CD28- T regulatory cells were determined by flow cytometry.

RESULTS: The model of experimental colitis was successfully established by DNFB that was demonstrated by bloody diarrhea, weight loss and colonic histopathology. The proportion of CD8+ T cells in either splenic or colonic intraepithelial lymphocytes was not significantly different between colitis animals and controls (spleen: 34.6% ± 7.24% vs 33.5% ± 9.41%, colon: 14.0% ± 8.93% vs 18.0% ± 4.06%, P > 0.05). But CD8+CD28- T regulatory cells from colitis animals were significantly more than those from controls (spleen: 11.3% ± 2.26% vs 5.64% ± 1.01%, colon: 6.50% ± 5.37% vs 1.07% ± 0.65%, P < 0.05). In contrast, CD8+CD28+ T cells from colitis animals were less than those from controls (spleen: 23.3% ± 6.14% vs 27.8% ± 9.70%, P = 0.06; colon: 7.52% ± 4.18% vs 16.9% ± 4.07%, P < 0.05). The proportion of CD8+CD28- T regulatory cells in splenic and colon intraepithelial CD8+ T cells from colitis animals was higher than that from controls (spleen: 33.3% ± 5.49% vs 18.4% ± 7.26%, colon: 46.0% ± 14.3% vs 6.10% ± 3.72%, P < 0.005).

CONCLUSION: Experimental colitis of rats can be induced by DNFB with simplicity and good reproducibility. The proportion of CD8+CD28- T regulatory cells in rats with experimental colitis is increased, which may be associated with the pathogenesis of colitis.

Effects of dopaminergic drugs on inflammatory bowel disease induced with 2,4-dinitrofluorbenzene in BALB/c mice

The aim of the study was to demonstrate the effects of dopaminergic drugs on 2,4-dinitrofluorbenzene (DNFB) induced experimental inflammatory bowel disease (IBD) in previously sensitized BALB/c mice. The number and extent of ulcerations and erosions, the intensity of haemorrhages, oedema, and accumulation of neutrophils and eosinophils within colonic lamina propria and submucosa were scored and statistically evaluated. The 180 BALB/c mice, were allocated into three equal groups. The mice in the first experimental group were treated with domperidone (DP), a peripheral dopamine (DA) antagonist. The mice from the second experimental group were treated with bromocriptine (BC), a dopamine agonist. The mice from the control group were treated with an equivalent volume of normal saline in the same manner. Ten animals from each group were killed on days 1, 2, 3, 5 and 10, subsequent to the challenge enema of DNFB solution. Gross and microscopic examination of the colon was performed. Treatment with BC resulted in clinical improvement and decreased mortality rate by 2 of 60 (3%), while domperidone treatment increased mortality rate to 12 of 60 (20%) compared with the controls [4 of 60 (6%)]. The analysis of the microscopic lesions indicated that the beneficial effects of BC were the result of maintenance of vascular integrity.

Pentadecapeptide BPC 157 positively affects both non-steroidal anti-inflammatory agent-induced gastrointestinal lesions and adjuvant arthritis in rats

Besides a superior protection of the pentadecapeptide BPC 157 (an essential fragment of an organoprotective gastric juice peptide BPC) against different gastrointestinal and liver lesions, an acute anti-inflammatory and analgetic activity was also noted. Consequently, its effect on chronic inflammation lesions, such as adjuvant arthritis, and non-steroidal anti-inflammatory agents (NSAIAs)-induced gastrointestinal lesions was simultaneously studied in rats. In gastrointestinal lesions (indomethacin (30 mg/kg s.c.), aspirin (400 mg/kg i.g.) and diclofenac (125 mg/kg i.p.) studies, BPC 157 (10 micrograms or 10 ng/kg i.p.) was regularly given simultaneously and/or 1 h prior to drug application (indomethacin). In the adjuvant arthritis (tail-application of 0.2 mL of Freund's adjuvant) studies (14 days, 30 days, 1 year) BPC 157 (10 micrograms or 10 ng/kg i.p.), it was given as a single application (at 1 h either before or following the application of Freund's adjuvant) or in a once daily regimen (0-14th day, 14-30th day, 14th day-1 year). Given with the investigated NSAIAs, BPC 157 consistently reduced the otherwise prominent lesions in the stomach of the control rats, as well as the lesions in the small intestine in the indomethacin groups. In the adjuvant arthritis studies, the lesion's development seems to be considerably reduced after single pentadecapeptide medication, and even more attenuated in rats daily treated with BPC 157. As a therapy of already established adjuvant arthritis, its salutary effect consistently appeared already after 2 weeks of medication and it could be clearly seen also after 1 year of application. Taking together all these results, the data likely point to a special anti-inflammatory and mucosal integrity protective effect.