The chemically induced mouse colitis model is the most commonly used animal model for human inflammatory bowel disease, among which dextran sulfate sodium induced colitis model is the most widely used。In the preparation of a dextran sulfate induced model, different concentrations of dextran sulfate and different strains of mice showed varying degrees of lesion severity in the intestinal segments of different mice. Therefore, it is unreasonable to take a sample of a certain segment of the colon for pathological evaluation. The entire colon should be made into a “Swiss roll” and the pathological changes should be comprehensively evaluated by dividing it into upper, middle and lower segments of the colon.The anal canal lesion is severe, it should be evaluated separately. Only by comprehensively and correctly evaluating the intestinal lesion can the therapeutic effect of drugs be correctly evaluated.

It is important to select a suitable in vitro experimental model to study the pathology and pharmacological mechanisms of inflammatory bowel disease (IBD), thereby developing advanced therapeutic drugs. Immortalized cell lines, as a classic in vitro model, offer several advantages in the research and drug evaluation of IBD, such as high efficiency, low cost, simple operation and intuitive experimental results. However, these models cannot recapitulate the multicellular composition and intercellular interaction of intestinal tissue in vivo and may lose genetic characteristics after multiple passages in vitro. The development of organoids and organs-on-a-chip has promoted the technological innovation of in vitro models by significantly improving our capability to simulate the architecture and function of IBD. The enhanced reproducibility of the organoid model to the microenvironment of the source tissue also confers improved predictive capability for patient treatment response. This paper reviews the current research status of these models by discussing their characteristics, advantages, disadvantages, and their applications in evaluation of IBD therapeutic drugs and development of advanced therapeutic drugs, as well as in the exploration of pharmacological mechanisms.

OBJECTIVE To analyze the dynamic changes of cell types and protein expression during the occurrence and development of ulcerative colitis. METHODS Single-cell sequencing technology was used to analyze the intestinal tissues of ulcerative colitis model mice and normal mice. After quality control, a total of 58 714 cells were used to construct a colitis dataset for downstream analysis. Then, the changes of epithelial compartments in the process of colitis occurrence and development were analyzed by means of dimensionality reduction clustering, GO analysis and Monocle quasi-time analysis. RESULTS Compared with the normal samples, the interaction between cell subsets in colitis samples changed significantly. The analysis revealed that most epithelial cell subtypes were destroyed and reduced in number during the colitis phase. The Wnt pathway was inhibited, which is important for maintaining stem cell function. The Ppia-Bsg ligand receptor pair was highly expressed in normal samples. CONCLUSION The depletion of Ppia secreted by stromal cells in the inflammatory state leads to stem cell senescence, which ultimately disrupts the homeostasis of epithelial cells and aggravates colitis.

OBJECTIVE To investigate the potential therapeutic effects and underlying mechanisms of total alkaloids derived from processed Aconitum carmichaelii Debx (ACA) on ulcerative colitis (UC) in mice. METHODS The chemical composition of ACA was analyzed using liquid chromatography-mass spectrometry. A mouse model of UC was induced using dextran sodium sulfate (DSS) to assess the effects of continuous administration of salicylazosulfapyridine(SASP) (200 mg·kg^-1) and ACA (10 and 20 mg·kg^-1) over seven days, evaluating parameters such as body weight, disease activity index, colon length, and pathological damage to the colon. The anti-inflammatory activity and mechanisms of ACA were investigated through in vitro experiments, enzyme-linked immunosorbent assay, and Western blotting. RESULTS ACA is primarily composed of various characteristic monomeric alkaloids. Treatment with ACA (10 and 20 mg/kg) significantly mitigated weight loss, disease index elevation, colon shortening, and pathological damage induced by DSS in the mice. Additionally, ACA reduced the levels of inflammatory factors, including IL-1β, IL-18, and IL-6, elevated by DSS in colitis. The in vitro inflammatory model further demonstrated that ACA functions as a specific inhibitor, MCC950, similar to the NLRP3 inflammasome, which suppresses the secretion of the aforementioned inflammatory factors in the supernatant of LPS- and Nigericin-induced THP-1 cells. Protein expression analysis suggested that this effect may be linked to the inhibition of the NLRP3 signaling pathway. CONCLUSION ACA contains multiple structurally similar monomeric alkaloids that exhibit anti-UC activity in mice, potentially exerting anti-inflammatory effects through the inhibition of the NLRP3 inflammasome.

OBJECTIVE To explore the mechanism of action of coptisine derivative Q3 against dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in mice from the perspective of changes in the inflammatory signaling pathway TLR4/NF-κB and compositions of the intestinal microbiota. METHODS Fifty mice were randomly divided into normal control group, model group, sulfasalazine (SASP) group, Q3-low dose group, Q3-high dose group, with 10 in each group. Mice in the groups except the control group were orally administered with 2.5% DSS solution to induce UC model. The SASP was given 700 mg·kg^-1·d^-1 of sulfasalazine by intragastric administration, and the Q3 low and high dose groups were given 50 and 100 mg·kg^-1·d^-1 of Q3, respectively. The other groups were given an equal amount of distilled water. After 6 days of administration, the mouse colon tissues were taken for DAI score and length measurement. HE staining was used to detect the degree of pathological damage in each group. 16S rRNA high-throughput sequencing was used to detect changes in intestinal flora in the intestinal contents of mice. Immunohistochemistry and Western blot were used to detect the expression of TLR4 and p-p65 in colon tissue. The protein expressions of TLR4, p-p65 and p-IκBα and the nuclear translocation of NF-κB p65 in IEC6 cells and RAW264.7 cells were detected by Western blot and immunofluorescence. RESULTS In the DSS-induced mouse ulcerative colitis model, compared with the model group, in vivo Q3 could significantly improve the weight loss, colon length, and increase in DAI scores of UC mice. HE staining results showed that Q3 significantly improved the intestinal pathological damages such as tract epithelial damage, crypt structure disorder and goblet cell reduction; immunohistochemistry and Western blot results showed that Q3 could significantly reduce the expression of TLR4 and p-p65 in the colon tissue of mice in the model group. The results of 16S rRNA showed that Q3 could increase the biodiversity of intestinal microbiota and regulate the composition of intestinal microbiota after DSS administration. It was also shown that in vitro Q3 could inhibit the nuclear translocation of NF-κB p65 in both IEC6 and RAW264.7 cells by immunofluorescence. CONCLUSION Q3 can improve intestinal inflammation by inhibiting the TLR4/NF-κB pathway and regulating the composition of intestinal flora, exerting anti-UC effects, which is expected to become a candidate compound for the treatment of UC.