The intestinal mucosal barrier (IMB), which consists of mechanical barrier, chemical barrier, biological barrier and immune barrier, plays an important role in the maintenance of intestinal epithelium integrity and defense against invasion of bacteria, endotoxins and foreign antigens. Impaired IMB, characterized by increased intestinal mucosal permeability (IMP) and decreased transmembrane resistance (TR), has been implicated in the pathogenesis of various digestive, urinary, circulatory, neurological and metabolic dysfunctions. Electrophysiological recording of TR in the ex vivo intestinal tissues or cultured epithelial cell monolayers, or biochemical quantification of transepithelial movement of orally-administered molecular probes or specific endogenous protein molecules has frequently been used in the evaluation of IMB. In this paper, the composition and function of IMB will be summarized, with emphasis on the evaluation methods of IMP.
Cells, Cultured ; Inosine Monophosphate/metabolism* ; Intestinal Mucosa ; Permeability

Objective: To study the mechanisms of cold exposure mediated ileum mechanical barrier injury in mice. Methods: Twenty mice were randomly divided into the control and cold exposure groups. Both the control and cold exposure groups were placed in the climate room with (24±2)℃ and 40% humidity. The mice in the cold exposure group were moved to the climate room at (4±2)℃ every day for 3 hours for three consecutive weeks. Three weeks later, the ileum tissues of mice were collected. Changes in ileum tissue structure were observed by hematoxylin-eosin staining and Masson staining. The related protein expression levels of the tight junction, inflammatory cytokines, and the NF-κB pathway were detected by Western blot. Results: Compared with the control group, the circular muscle layer of the ileum in cold exposed mice became thin, a large number of inflammatory cells infiltrated, the length of villi became short, the depth of recess was increased, and tissue fibrosis appeared. The expression levels of ideal tight junction-associated proteins in cold exposed mice were decreased significantly (P＜0.05), while the protein expression levels of IL-1β, IL-6 and phosphorescent p65 were increased significantly (P＜0.05). Conclusion: Cold exposure can damage the tight junction of the mouse ileum, destroy the integrity of the mechanical barrier and activate the NF-κB signaling pathway to promote the occurrence of the inflammatory response.
Animals ; Cytokines/metabolism* ; Ileum/metabolism* ; Intestinal Mucosa ; Mice ; NF-kappa B/metabolism* ; Tight Junctions/metabolism*

Animals ; Chickens ; Cold Temperature ; adverse effects ; Gastric Mucosa ; metabolism ; pathology ; physiopathology ; Intestinal Mucosa ; metabolism ; pathology ; physiopathology ; Male ; Serum ; metabolism

OBJECTIVETo investigate the role of cyclic adenosine monophosphate(cAMP) in the regulation of intestinal epithelial barrier function under hypoxia.

METHODSIntestinal epithelial barrier was established by Caco-2 monolayers. Cells were divided into four groups: normoxia (Nx), normoxia plus Forskolin(Nx+FSK), hypoxia(Hx), hypoxia plus SQ22536(Hx+SQ22536). cAMP concentrations of different groups were assessed by cAMP enzyme immunoassay kit. RT-PCR and Western blotting were used to detect the mRNA and protein expressions of claudin-1 and occludin under normoxic and hypoxic condition. Caco-2 monolayers were grown on Millicell filters, and transepithelial electrical resistance(TER) was measured using a Millipore electric resistance system.

RESULTSThe concentration of cAMP under hypoxic conditions(Hx group) was higher compared with Nx group [(6.30±0.50) pmol/L vs. (2.38±0.18) pmol/L, P<0.01]. At the same time, both mRNA and protein expressions of claudin-1 and occluding were lower in Hx group than those in Nx group(all P<0.05). TER decreased by 76.30±0.64(P<0.01). When the monolayers were exposed to hypoxia plus SQ22536 (Hx+SQ22536 group), the concentration of cAMP was(2.12±0.23) pmol/L, which was lower than that under hypoxic conditions(Hx group, P<0.01). Both mRNA and protein expressions of claudin-1 and occludin were higher compared to Hx group (all P<0.01). TER increased by 32.96±2.16 (P<0.05).

CONCLUSIONWhen Caco-2 cells are exposed to hypoxia, barrier function, claudin-1 and occludin expression are diminished in parallel with a high level of intracellular cAMP compared with the normoxic condition. Inhibition of the intracellular cAMP level under hypoxia can maintain the intestinal epithelial function through regulating the claudin-1 and occludin expression and attenuate the permeability of intestinal mucosa.

Adenosine Monophosphate ; Caco-2 Cells ; Claudin-1 ; metabolism ; Humans ; Intestinal Mucosa ; metabolism ; Intestines ; Occludin ; metabolism

OBJECTIVETo explore the protective effects of two types of ischemic postconditioning (IP) on intestinal mucosa barrier in rabbits with crush injury of the hind limb.

METHODSThis study was conducted between August and December 2008 in the Department of Trauma Surgery, Daping Hospital, Third Military Medical University, Chongqing, China. The model of crush injury to the hind limb of rabbits was firstly developed by a 25 kg object with the right hind limbs fixed by wooden splints, and then two types of IP were established, including occluding/opening the common iliac artery and vein alternatively (traditional IP, IP A) and binding/loosening the proximum of the injured hind limb alternatively (modified IP, IP B). Thirty-six male New Zealand white rabbits were randomly divided into three groups: IP A group, IP B group and control group, with 12 rabbits in each group. The serum levels of diamine oxidase (DAO) and intestinal fatty acid-binding protein (I-FABP) were detected at 2, 6, 12 and 24 hours after injury. Pathological changes of ileum were examined at 24 hours after injury.

RESULTSThe serum levels of I-FABP at 2, 6, 12 and 24 hours after injury in both IP A and IP B groups had a significant decrease, compared with control group. DAO levels also showed the same change trend at 2 and 6 hours after injury, but showed no significant difference between two IP groups. No difference in pathological changes of ileum was found among the three groups.

CONCLUSIONSIP can protect intestinal mucosa barrier function on the model of hind limb crush injury in rabbits. Meanwhile the modified IP B shows the same protection as the traditional IP A, and is worth applying in clinic.

Amine Oxidase (Copper-Containing) ; metabolism ; Animals ; Hindlimb ; injuries ; Intestinal Mucosa ; metabolism ; Ischemic Postconditioning ; Male ; Rabbits

OBJECTIVETo study the expression and distribution of aquaporin 3 (AQP3) and aquaporin 9 (AQP9) in colonic mucosa of patients with functional constipation, and to examine the relationship of constipation with AQP3 and AQP9.

METHODSImmunohistochemistry and semi-quantitative Western blotting were used to detect the expression and distribution of AQP3 and AQP9 in colonic mucosa of 45 patients with functional constipation (trial group) and 21 cases without constipation (control group). Gray scale ratios of AQP3 and AQP9 to beta-actin protein as interior reference were relative amounts of AQP3 and AQP9.

RESULTSImmunohistochemistry showed that AQP3 was distributed mainly in basement and cavosurface membrane of epithelial cell of colonic mucosa and AQP9 mainly in basement membrane of goblet cell in cavosurface colonic mucosa. Western blotting revealed that the average values of gray scale ratios of AQP3 in ascending colon of trial group and control group were 0.905 and 0.798 (P<0.05),while those of AQP9 were 0.544 and 0.543 (P>0.05), respectively. The average values of gray scale ratios of AQP3 in descending colon of trial group and control group were 0.697 and 0.701 (P>0.05), while those of AQP9 were 0.575 and 0.732 (P<0.05), respectively.

CONCLUSIONSUp-regulated expression of AQP3 in ascending colon and down-regulated expression of AQP9 in descending colon are presented in patients with functional constipation as compared to patients without functional constipation. AQP3 and AQP9 may play a significant role in the onset and development of constipation.

Adult ; Aged ; Aquaporin 3 ; metabolism ; Aquaporins ; metabolism ; Constipation ; metabolism ; Female ; Humans ; Intestinal Mucosa ; metabolism ; Male ; Middle Aged

OBJECTIVETo explore the changes in the PGE(2) and PGI(2), TXA(2) levels and PGT mRNA expression in the intestinal mucosa in scalded rats.

METHODSWistar rats inflicted with TBSA 30% III degree scald were employed as the model. The PGE(2) and PGI(2) and TXA(2) contents in the intestinal mucosa were measured by radioimmunoassay, and the expression of PGT mRNA was detected by in situ hybridization.

RESULTSThe PGE(2) and PGI(2) levels in intestinal mucosa were increased at 12 postburn hours (PBHs) and thereafter decreased dramatically (P < 0.05). The TXA(2) level in intestinal mucosa of scalded rats was obviously higher than that of normal level at 24 and 48 PBHs (P < 0.05), and the expression of PGT mRNA seemed to be increased after scalding.

CONCLUSIONThe decrease of PGE(2) level and the increase of TXA(2) level in the intestinal mucosa of scalded rats might be involved in rat mucosal injury, and PGT played an important role in the regulation of PGs levels.

Animals ; Burns ; metabolism ; pathology ; Intestinal Mucosa ; metabolism ; pathology ; Organic Anion Transporters ; metabolism ; Prostaglandins ; analysis ; RNA, Messenger ; metabolism ; Rats ; Rats, Wistar

Animals ; Gene Expression Regulation ; physiology ; Gills ; metabolism ; Intestinal Mucosa ; metabolism ; Lancelets ; genetics ; metabolism ; Liver ; metabolism ; MicroRNAs ; biosynthesis ; genetics

No abstract available.
Animals ; Apoptosis/*physiology ; Claudins/*metabolism ; Colitis/*physiopathology ; Intestinal Mucosa/*physiopathology ; Mannose-Binding Lectin/*immunology

OBJECTIVE: To study the biodegradation properties of multi-laminated small intestinal submucosa (mSIS) through in vitro and in vivo experiments, comparing with Bio-Gide, the most widely used collagen membrane in guided bone regeneration (GBR) technique, for the purpose of providing basis to investigate whether mSIS meets the requirements of GBR in dental clinics. METHODS: The degradation properties were evaluated in vitro and in vivo. In vitro degradation was performed using prepared collagenase solution. Morphology of mSIS and Bio-Gide in degradation solution were observed and the degradation rate was calculated at different time points. In in vivo experiments, nine New Zealand rabbits were used for subcutaneous implantation and were divided into three groups according to observation intervals. Six unconnected subcutaneous pouches were made on the back of each animal and were embedded with mSIS and Bio-Gide respectively. At the end of weeks 4, 8, and 12 after operation, gross observation and HE staining were used to evaluate the degree of degradation and histocompatibility. RESULTS: In vitro degradation experiments showed that mSIS membrane was completely degraded at the end of 12 days, while Bio-Gide was degraded at the end of 7 days. Besides, mSIS maintained its shape for longer time in the degradation solution than Bio-Gide, indicating that mSIS possessed longer degradation time, and had better ability to maintain space than Bio-Gide. In vivo biodegradation indicated that after 4 weeks of implantation, mSIS remained intact. Microscopic observation showed that collagen fibers were continuous with a few inflammatory cells that infiltrated around the membrane. Bio-Gide was basically intact and partially adhered with the surrounding tissues. HE staining showed that collagen fibers were partly fused with surrounding tissues with a small amount of inflammatory cells that infiltrated as well. Eight weeks after operation, mSIS was still intact, and was partly integrated with connective tissues, whereas Bio-Gide membrane was mostly broken and only a few residual fibers could be found under microscope. Only a small amount of mSIS debris could be observed 12 weeks after surgery, and Bio-Gide could hardly be found by naked eye and microscopic observation at the same time. CONCLUSION In vitro degradation time of mSIS is longer than that of Bio-Gide, and the space-maintenance ability of mSIS is better. The in vivo biodegradation time of subcutaneous implantation of mSIS is about 12 weeks and Bio-Gide is about 8 weeks, both of which possess good biocompatibility.
Animals ; Biocompatible Materials/metabolism* ; Bone Regeneration ; Connective Tissue ; Intestinal Mucosa ; Intestine, Small ; Membranes, Artificial ; Rabbits