Population changes in immunoglobulin-containing mononuclear cells in dextran sulfate sodium-induced coltitis

Comparative Pharmacokinetics and Tissue Distribution of M10 and Its Metabolite Myricetin in Normal and Dextran-Sodium-Sulfate-Induced Colitis Mice

M10, a novel myricetin derivative, is an anti-inflammatory agent designed for treatment of colitis. Here, we aim to investigate its pharmacokinetic behavior and tissue distribution in a mouse model with colitis. Pharmacokinetics and tissue distribution of M10 and its metabolite myricetin were compared in normal mice and in dextran-sodium-sulfate (DSS)-induced colitis mice. The role of fecal microbiota was also analyzed during metabolism of M10 in vitro. After oral administration, M10 was very low in the plasma of both normal and diseased mice. However, both M10 and myricetin were mainly distributed in the gastrointestinal tract, including the stomach, colon and small intestine, in physiological and pathological conditions. Significantly, M10 and myricetin were found in higher levels in gastrointestinal tracts with inflamed tissues than in normal tissues of mice. An in vitro assay revealed that 80% of M10 was metabolized to myricetin via fecal microbiota. After oral administration, M10 was not absorbed into circulation but mainly distributed in the inflamed submucosal tissues of colitic mice, where it was metabolized into myricetin to prevent colitis development.

Idebenone Protects against Acute Murine Colitis via Antioxidant and Anti-Inflammatory Mechanisms

Oxidative stress is a key player of the inflammatory cascade responsible for the initiation of ulcerative colitis (UC). Although the short chain quinone idebenone is considered a potent antioxidant and a mitochondrial electron donor, emerging evidence suggests that idebenone also displays anti-inflammatory activity. This study evaluated the impact of idebenone in the widely used dextran sodium sulphate (DSS)-induced mouse model of acute colitis. Acute colitis was induced in C57BL/6J mice via continuous exposure to 2.5% DSS over 7 days. Idebenone was co-administered orally at a dose of 200 mg/kg body weight. Idebenone significantly prevented body weight loss and improved the disease activity index (DAI), colon length, and histopathological score. Consistent with its reported antioxidant function, idebenone significantly reduced the colonic levels of malondialdehyde (MDA) and nitric oxide (NO), and increased the expression of the redox factor NAD(P)H (nicotinamide adenine dinucleotide phosphate) dehydrogenase quinone-1 (NQO-1) in DSS-exposed mice. Immunohistochemistry revealed a significantly increased expression of tight junction proteins, which protect and maintain paracellular intestinal permeability. In support of an anti-inflammatory activity, idebenone significantly attenuated the elevated levels of pro-inflammatory cytokines in colon tissue. These results suggest that idebenone could represent a promising therapeutic strategy to interfere with disease pathology in UC by simultaneously inducing antioxidative and anti-inflammatory pathways.

Gallic acid attenuates dextran sulfate sodium-induced experimental colitis in BALB/c mice

Gallic acid (GA) is a polyhydroxy phenolic compound that has been detected in various natural products, such as green tea, strawberries, grapes, bananas, and many other fruits. In inflammatory bowel disease, inflammation is promoted by oxidative stress. GA is a strong antioxidant; thus, we evaluated the cytoprotective and anti-inflammatory role of GA in a dextran sulfate sodium (DSS)-induced mouse colitis model. Experimental acute colitis was induced in male BALB/c mice by administering 2.5% DSS in the drinking water for 7 days. The disease activity index; colon weight/length ratio; histopathological analysis; mRNA expressions of IL-21 and IL-23; and protein expression of nuclear erythroid 2-related factor 2 (Nrf2) were compared between the control and experimental mice. The colonic content of malondialdehyde and the activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase activity were examined as parameters of the redox state. We determined that GA significantly attenuated the disease activity index and colon shortening, and reduced the histopathological evidence of injury. GA also significantly (P<0.05) reduced the expressions of IL-21 and IL-23. Furthermore, GA activates/upregulates the expression of Nrf2 and its downstream targets, including UDP-GT and NQO1, in DSS-induced mice. The findings of this study demonstrate the protective effect of GA on experimental colitis, which is probably due to an antioxidant nature of GA.

Suppressive effect of berberine on experimental dextran sulfate sodium-induced colitis

The anti-inflammatory effect of berberine was evaluated in murine model of acute experimental colitis induced by dextran sulfate sodium (DSS). Berberine, given orally at 40, 20, 10 mg/kg for 10 days, ameliorated all the supposed inflammatory symptoms of the induced colitis, such as body weightloss, blood hemoglobin reduction, high myeloperoxidase levels, and malondialdehyde content-inflamed mucosa. Furthermore, the cytokine production of splenic lymphocytes was analyzed. The results showed the IFN-γ and IL-12 were increased, but IL-4 and IL-10 were decreased in DSS-induced colitis,when those were compared with the normal control. But the administration of berberine to DSS-induced colitis mice showed lower production of IFN-γ and IL-12 and higher production of IL-4 and IL-10 than the DSS-induced colitis mice. The results suggest that the protective effects of berberine against the DSS-induced colitis may be associated with the regulation of cytokine production.

Prevention of chronic experimental colitis induced by dextran sulphate sodium (DSS) in mice treated with FR91

One of the main treatments currently used in humans to fight cancer is chemotherapy. A huge number of compounds with antitumor activity are present in nature, and many of their derivatives are produced by microorganisms. However, the search for new drugs still represents a main objective for cancer therapy, due to drug toxicity and resistance to multiple chemotherapeutic drugs. In animal models, a short-time oral administration of dextran sulfate sodium (DSS) induces colitis, which exhibits several clinical and histological features similar to ulcerative colitis (UC). However, the pathogenic factors responsible for DSS-induced colitis and the subsequent colon cancer also remain unclear. We investigated the effect of FR91, a standardized lysate of microbial cells belonging to the Bacillus genus which has been previously shown to have significant immunomodulatory effects, against intestinal inflammation. Colitis was induced in mice during 5 weeks by oral administration 2% (DSS). Morphological changes in the colonic mucosa were evaluated by hematoxylin-eosin staining and immunohistochemistry methods. Adenocarcinoma and cryptal cells of the dysplastic epithelium showed cathenin-β, MLH1, APC, and p53 expression, together with increased production of IFN-γ. In our model, the optimal dose response was the 20% FR91 concentration, where no histological alterations or mild DSS-induced lesions were observed. These results indicate that FR91 may act as a chemopreventive agent against inflammation in mice DSS-induced colitis.

The correlation between proinflammatory cytokines, MAdCAM-1 and cellular infiltration in the inflamed colon from TNF-alpha gene knockout mice

Tumour necrosis factor (TNF) is important in the development of inflammatory bowel disease. TNF-alpha-deficient mice show more severe colonic inflammation than wild-type (Wt) mice, but the underlying mechanism remains unclear. Using immunohistochemistry, enzyme-linked-immunosorbent assay and histopathology, we found that there was a higher level of macrophage infiltration in TNF-alpha(-/-) compared to Wt mice. This is consistent with higher levels of monocyte chemotactic protein-1, interleukin (IL)-6 and granulocyte monocyte colony-stimulating factor (GM-CSF) in the inflamed colon from the TNF-alpha(-/-) mice, compared to the Wt mice, following dextran sulphate sodium (DSS) challenge. There was close correlation between clinical observations and histopathological findings in both Wt and TNF-alpha(-/-) mice. The expression of mucosal addressin cell adhesion molecule 1 (MAdCAM-1) was upregulated in the colon of Wt and TNF-alpha(-/-) mice following DSS challenge. Interestingly, the induction of MAdCAM-1 was relatively lower in the inflamed colon of TNF-alpha(-/-) mice, despite the higher inflammatory cell infiltrate, compared to their Wt counterparts. On the other hand, TNF-alpha(-/-) mice had significantly lower baseline levels of colonic IL-4, IL-6 and GM-CSF. Furthermore, there was a reduction of both immunoglobulin A (IgA) and IgG in the gut from TNF-alpha(-/-) mice following DSS challenge. These data indicate that TNF-alpha deficiency alters homoeostasis of the colonic chemokine/cytokine environment and humoral immune response, resulting in an exacerbation of acute DSS-induced colitis in TNF-alpha(-/-) mice. These findings support the idea that TNF-alpha plays a role in the acute stage of intestinal inflammation.

Mouse strain differences in inflammatory responses of colonic mucosa induced by dextran sulfate sodium cause differential susceptibility to PhIP-induced large bowel carcinogenesis

In mice, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) induces a high incidence of malignant lymphoma and leukemia, but exhibits little, if any, carcinogenic activity in the large intestine after long-term exposure. However, recent studies have revealed that colonic adenocarcinomas can be efficiently and rapidly induced by combined treatment with PhIP and dextran sulfate sodium (DSS), a potent inducer of colitis. In the present study, the authors investigated the effects of inflammation on PhIP-induced carcinogenesis using two mouse strains, C57BL/6J and MSM/Ms, showing distinct temporal profiles of inflammatory responses to DSS. A long-term carcinogenesis experiment conducted with a single i.g. administration of PhIP (200 mg/kg body weight), followed by DSS treatment in drinking water for 4-6 days, revealed an increase in tumor incidence in C57BL/6J mice in accordance with the DSS intake. In contrast, neoplastic lesions were rarely observed in the MSM/Ms strain. From the short-term exposure to DSS for 4 days, C57BL/6J mice demonstrated severe chronic colitis, accompanied by hyperplastic cryptal epithelium and extensive cellular infiltration. Splenomegaly and swelling of mesenteric lymph nodes were also evident for over 1 month as chronic symptoms of systemic immunological disturbance. However, no inflammatory lesions were detected in MSM/Ms mice. The present results provide strong evidence that prolonged chronic inflammatory responses induced by DSS are directly responsible for the observed enhancement of PhIP-induced large bowel carcinogenicity.

Protective effect of hawthorn fruit on murine experimental colitis

The pathogenic mechanism and effective treatment of inflammatory bowel disease (IBD) are still unknown. In the present study, we examined the protective effect of hawthorn fruit (Crataegifructus) on two murine colitis models: dextran sulfate sodium (DSS) and 2,4,6-trinitrobenzene sulfonic acid (TNBS) colitis. Mice that developed acute colitis showed signs of diarrhea, gross rectal bleeding and weight loss within 10 days. However, hawthorn fruit (2 g/kg body weight) restored the body weight and colon length and increased hemoglobin count in these animals. Hawthorn fruit not only decreased signs of inflammation such as infiltration by polymorphonuclear leukocytes and multiple erosive lesions, but also showed improvement of leukotriene B4 (LTB4), a biochemical parameter of inflammation mass. TNBS colitis mice had significantly lower rates of survival than normal control animals; however, treatment with hawthorn fruit significantly improved survival in TNBS colitis mice. The results suggest that hawthorn fruit and the Kampo formula that contains this ingredient may have potential therapeutic utility in patients with IBD.

Differential susceptibility of inbred mouse strains to dextran sulfate sodium-induced colitis

Dextran sulfate sodium (DSS)-induced murine colitis represents an experimental model for human inflammatory bowel disease. The aim of this study was to screen various inbred strains of mice for genetically determined differences in susceptibility to DSS-induced colitis. Mice of strains C3H/HeJ, C3H/HeJBir, C57BL/6J, DBA/2J, NOD/LtJ, NOD/LtSz-Prkdc(scid)/Prkdc(scid), 129/SvPas, NON/LtJ, and NON.NOD-H2g7 were fed 3.5% DSS in drinking water for 5 days and necropsied 16 days later. Ceca and colons were scored for histological lesions based on severity, ulceration, hyperplasia, and area involved. Image analysis was used to quantitate the proportion of cecum ulcerated. Histological examination revealed significant differences among inbred strains for all parameters scored. In both cecum and colon, C3H/HeJ and a recently selected substrain, C3H/HeJBir, were highly DSS susceptible. NOD/LtJ, an autoimmune-prone strain, and NOD/LtSz-Prkdc(scid)/Prkdc(scid), a stock with multiple defects in innate and adoptive immunity, were also highly DSS susceptible. NON/LtJ, a strain closely related to NOD, was quite DSS resistant. The major histocompatibility (MHC) haplotype of NOD mice (H2g7), a major component of the NOD autoimmune susceptibility, was not crucial in determining DSS susceptibility, since NON mice congenic for this MHC haplotype retained resistance. C57BL/6J, 129/SvPas, and DBA/2J mice showed various degrees of susceptibility, depending upon the anatomical site. A greater male susceptibility to DSS-induced colonic but not cecal lesions was observed. In summary, this study demonstrates major differences in genetic susceptibility to DSS-induced colitis among inbred strains of mice. Knowledge of these strain differences in genetic responsiveness to acute inflammatory stress in the large intestine will permit design of genetic crosses to elucidate the genes involved.

Promotion of colorectal neoplasia in experimental murine ulcerative colitis

BACKGROUND

The mechanisms underlying the frequent development of colorectal carcinomas in patients with ulcerative colitis are still unknown.

AIMS

To evaluate whether mucosal necrosis and regeneration act as enhancing or promoting factors in colorectal tumorigenesis, development of multiple colorectal tumours was studied in a murine model of ulcerative colitis with azoxymethane pretreatment.

METHODS

Periods of chronic ulcerative colitis in mice were induced by three repeated administrations of 3% dextran sulphate sodium subsequent to a single azoxymethane pretreatment, to give conditions similar to the clinically observed active and remission phases.

RESULTS

In the chronic colitis group with carcinogen exposure, multiple mucosal tumours (10.5/mouse) developed in the colorectum. This occurred primarily on the left side of the large intestine or transverse colon, the sites of the most severe colitic injury. The observed lesions were high grade dysplasias and invasive adenocarcinomas. Increased cell proliferation was evidenced by high uptake of bromodeoxyuridine, and increased activities of thymidylate synthetase and thymidine kinase. No tumours were induced in the control groups with azoxymethane pretreatment or chronic colitis alone.

CONCLUSIONS

Repeated mucosal erosion with necrosis and regeneration is critical for the development of colorectal tumours in this experimental colitis system.