## 4 Discussion
The effect of DSS on body weight loss was observed; an initial small increase in body weight for up to 3 days, which began to decrease with bleeding and diarrhoea. The treatment group showed significant differences in weight loss when treated with 1.5%, 2.5%, and 3.5% DSS. The loss in weight in the 2.5% and 3.5% DSS groups had been observed since the 4 th day, whereas the loss in weight in the 1.5% group was seen on the 6 th day of the experiment. The disease activity index score graph demonstrates a noticeable difference between the 1.5%, 2.5%, and 3.5% DSS-treated groups. The DAI score was observable on the 2 nd day for the 2.5% and 3.5% DSS-treated mice. In contrast, it was visible on the 5 th day of the experiment for the 1.5% DSS-treated group. The length of the colon reduced as the disease developed and was significantly shorter on day 4. The 2.5% DSS-treated mice had the shortest colon lengths when compared with the 1.5% and 3.5% DSS-treated mice. A histological study of the colon sections stained by haematoxylin and eosin showed marked inflammation. BALB/c mice were treated with three different concentrations of DSS for 7 days, and the mice were sacrificed to collect their colons. The extent of inflammation in the 2.5% DSS-treated mice was significantly greater than in the 1.5% group. The crypt and epithelial layer were almost fully damaged, and severe infiltration of inflammatory cells into the mucosa was seen in the 3.5% DSS-treated group. The group treated with 1.2% DSS (C) showed less crypt damage than the 2.5% and 3.5% DSS-treated groups. The appearance of neutrophils is more evident in C (2.5% DSS), and its epithelial structure maintained its position. However, the extent of cryptic abscesses and epithelial tissue damage is more prominent in D (3.5% DSS). This higher extent of epithelial damage may cause death due to chronic inflammatory conditions in mice and may cause irreversible chronic inflammation [23]. Therefore, 2.5% could be a suitable concentration to study the colitis model and to recover inflammation by stopping the administration of DSS. DSS induces colitis and involves the disruption of the protective epithelial barrier. This has led to the investigation of the factors that help maintain and reclaim cellular integrity after the damage. However, the healing of the colon depends on the extent of epithelial damage. Excessive damage to the epithelium layer leads to loss of life. In this case, the use of a 2.5% DSS solution offers the advantage of reversing the cellular damage to the epithelial layer of the colon. Several studies have investigated the role of TLR, cytokines, and proteins derived from the epithelial layer itself on damage reversal. The TLR2 ligand was found to reduce the severity of DSS on epithelial cells, while its deficiency promotes colitis. In addition to this, TLR4 activation reduces the DSS-mediated action on the epithelial cells by releasing growth factors that stimulate the cells positively [44,45]. In yet another study, it was shown that the Wnt pathway inhibited by Dkk1 was positively correlated with colonic renewal [46]. As it appears from the above discussion, this study could be useful for selecting the right concentration of DSS to induce inflammation. However, a crucial point to be noted here is that DSS induces inflammation but does not accurately mimic ulcerative colitis in humans. The most significant difference is the involvement of the T-cell proinflammatorycy cytokine response in chronic DSS colitis and polarised T-cell-mediated responses in human IBD.