| BackgroundInflammatory bowel disease (IBD) represents a group of idiopathic chronic inflammatory intestinal conditions, including Crohn’s disease (CD) and ulcerative colitis (UC). In CD, inflammatory condition may affect any part of the GI tract from mouth to anus. It mainly causes abdominal pain, diarrhea, vomiting and weight loss. While in UC, inflammation starts in the rectum and generally extends proximally in a continuous manner through the entire colon. Bloody diarrhea, presence of blood and mucus mixed with stool, accompanied by lower abdominal cramping are the characteristic symptoms of the disease. With long term of bowel symptoms and systemic symptoms, the quality of life and social function of IBD patients are affected severely.Although the basic etiology of IBD is unknown, there are several factors that may contribute to the pathogenesis of this disease, such as dysregulation of immune system or commensal bacteria, oxidative stress and inflammatory mediators. In order to understand these different etiological factors, a number of experimental models are available in the scientific research, including chemical-induced, bacterial infection-induced, spontaneous, genetically engineered models. Various types of IBD animal models have their own characteristics. Using2,4,6-Trinitrobenzene sulfonic acid(TNBS)/ethanol enema to induce colitis is the most common method.Alkaline phosphatases (AP) are hydrolase enzymes that catalyze the breakdown of monophosphate esters by removal of their phosphate groups. AP are grouped into four types:IAP, placental alkaline phosphatase (PLAP), germ cell alkaline phosphatase and the tissue non-specific alkaline phosphatases (TNAP). Recent studies indicate that IAP of IBD patients significantly reduced, exogenous IAP can partially relieve intestinal inflammation in patients with IBD. The relationship and internal mechanisms between IAP and IBD is still not well understood.ObjectiveThis study tries to provide evidence for applying this traditional IBD animal models to explore the interaction and correlation mechanisms between IAP and IBD by testing the expression of IAP in TNBS-induced recurrence colitis mice model.MethodsFemale BALB/c mice (20±2g) were randomized into three groups:the chronic inflammation group, the acute inflammation group and the control group. Mice in the control group received saline intracolonically and the other groups received TNBS/ethanol enema. Animal models were evaluated by observing the changes of symptoms, bowel pathology and serous levels of TNF-a were detected by enzyme-linked immunosorbent assay (ELISA). The expression of colonic IAP was measured by ELISA and the expression of IAP mRNA was evaluated by real time quantitative PCR.All data were expressed as the mean±standard deviation (SD) and analyzed with the SPSS17.0software. The statistical differences between the groups were compared using one-way analysis of variance (ANOVA), followed by Bonferroni test. P<0.05was considered significant.ResultsNo mice died in this experiment.24h after TNBS/ethanol enema, mice appeared unresponsive, cowered, with blood and mucus in stool.72h after TNBS/ethanol enema, mucous bloody stool gradually diminished.1week after TNBS/ethanol enema, mucous bloody stool disappeared and the mice returned to normal. Using enemas repeatedly led to the recurrence of symptoms. Mice in the control group had normal appetite and gaining weight. In the chronic inflammation group, some parts of the intestine were distorted, narrow. In the acute inflammation group, mice had intestinal edema, transmural necrosis with bleeding. The lesions could involve the whole colon. The control group was normal. Histological examination showed mice in the chronic inflammation group had an increased local infiltration of lymphocytes and existence of dysplasia and mice in the acute inflammation group had diffuse hyperemia and hemorrhage of colon mucosa, goblet cells decreased, infiltration of neutrophils and epithelial erosions, ulcers. The control group was normal.Serous levels of TNF-a in the chronic inflammation group and acute inflammation group were significantly higher than that of the control group (P<0.05). There was no statistically significant difference in the expressions of colonic IAP and IAP mRNA between the chronic inflammation group and acute inflammation group, but their expressions were significantly lower compared with the control group (P<0.05). ConclusionsRepeatedly TNBS/ethanol administration can induce chronic colitis animal models. On this basis, receiving TNBS/alcohol intracolonically at high concentration again can cause acute inflammatory response. This model is similar to the IBD’s performance.TNF-a plays a role in TNBS-induced colitis mice, which is similar to the situation of IBD. Serous level of TNF-a in IBD patients is also significantly higher.The expression of IAP in TNBS-induced colitis mice models is significantly lower compared with the control group. The results show we could apply this traditional IBD animal model to explore the interaction and correlation mechanisms between IAP and IBD. |
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