Changes in the Expression and Distribution of Claudins, Increased Epithelial Apoptosis, and a Mannan-Binding Lectin-Associated Immune Response Lead to Barrier Dysfunction in Dextran Sodium Sulfate-Induced Rat Colitis

Abstract

Background/AimsThis animal study aimed to define the underlying cellular mechanisms of intestinal barrier dysfunction.MethodsRats were fed 4% with dextran sodium sulfate (DSS) to induce experimental colitis. We analyzed the sugars in 24-hour urine output by high pressure liquid chromatography. The expression of claudins, mannan-binding lectin (MBL), and MBL-associated serine proteases 2 (MASP-2) were detected in the colonic mucosa by immunohistochemistry; and apoptotic cells in the colonic epithelium were detected by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling method assay.ResultsThe lactulose and sucralose excretion levels in the urine of rats with DSS-induced colitis were significantly higher than those in the control rats. Mannitol excretion was lower and lactulose/mannitol ratios and sucralose/mannitol ratios were significantly increased compared with those in the control group (p<0.05). Compared with the controls, the expression of sealing claudins (claudin 3, claudin 5, and claudin 8) was significantly decreased, but that of claudin 1 was increased. The expression of pore-forming claudin 2 was upregulated and claudin 7 was downregulated in DSS-induced colitis. The epithelial apoptotic ratio was 2.8%±1.2% in controls and was significantly increased to 7.2%±1.2% in DSS-induced colitis. The expression of MBL and MASP-2 in the intestinal mucosa showed intense staining in controls, whereas there was weak staining in the rats with colitis.ConclusionsThere was increased intestinal permeability in DSS-induced colitis. Changes in the expression and distribution of claudins, increased epithelial apoptosis, and the MASP-2-induced immune response impaired the intestinal epithelium and contributed to high intestinal permeability.

African green monkeys avoid SIV disease progression by preventing intestinal dysfunction and maintaining mucosal barrier integrity

“…We assessed the AGM capacity to maintain mucosal barrier integrity [3,4] by examining three different conditions associated with gut damage: apoptosis, fibrosis and loss of tight junctions between epithelial cells [92][93][94][95]. Apoptosis was measured in the gut and LNs by assessing the levels of active caspase-3, a central component of both the extrinsic and intrinsic apoptosis pathways [96].…”

Translational safety biomarkers of colonic barrier integrity in the rat

“…In contrast to sucralose, lactulose and mannitol have been shown to be equally susceptible to colonic bacterial degradation, and their relevance in colonic permeability assessment is therefore debated (Anderson et al, ; Meddings & Gibbon, ; Rao et al, ). However, studies in rats and humans have demonstrated that lactulose and mannitol could be of value in colitis models (Rao et al, ; Yuan et al, ). Our results indicated that, following ibuprofen and Na‐C treatment, colonic permeability increased for all three sugars when administered locally in the colon.…”

“…When evaluating intestinal permeability using a mixture of sugars as probe molecules, often ratios of the urinary level of two sugars are used for interpretation (Anderson et al, ; Mishra & Makharia, ; Pernet et al, ), and this has also been applied in rat colitis models (Meddings & Gibbon, ; Yuan et al, ). Ratios are used to correct for individual variation in intestinal transit and renal clearance (Mishra & Makharia, ; Rao et al, ).…”

“…FD4, PEG and TST dose levels were based on available literature, taking into account their maximum solubility (Aguirre et al, ; Gruber et al, ; Haque et al, ; Joly Condette et al, ; Meddings & Gibbons, ; Pantzar et al, ; Yuan et al, ).…”

“…It has been used to characterize rodent intestinal epithelial permeability in surgery models after intra‐intestinal instillation as well as after in vivo oral administration (Aguirre et al, ; Haque et al, ; Joly Condette et al, ; Puppa et al, ). A combination of the probe molecules lactulose, mannitol and sucralose, also known as the triple sugar test (TST), was selected based on reports of increased excretion in urine after intestinal permeability enhancement in rats and humans (Anderson et al, ; Grootjans et al, ; Krugliak, Hollander, Schlaepfer, Nguyen, & Ma, ; Meddings & Gibbons, ; Rao et al, ; Yuan et al, ). These sugars have a molecular weight of 342, 182 and 398 Da, respectively.…”