Project description:The brain-gut axis serves as the bidirectional connection between the gut microbiome, the intestinal barrier and the immune system that might be relevant for the pathophysiology of inflammatory demyelinating diseases. People with multiple sclerosis have been shown to have an altered microbiome, increased intestinal permeability and changes in bile acid metabolism. Experimental evidence suggests that these changes can lead to profound alterations of peripheral and central nervous system immune regulation. Besides being of pathophysiological interest, the brain-gut axis could also open new avenues of therapeutic targets. Modification of the microbiome, the use of probiotics, fecal microbiota transplantation, supplementation with bile acids and intestinal barrier enhancers are all promising candidates. Hopefully, pre-clinical studies and clinical trials will soon yield significant results.
Project description:AimTo investigate the dysfunction of the immunological barrier of the intestinal mucosa during endotoxemia and to elucidate the potential mechanism of this dysfunction.MethodsMale Wistar rats were randomly distributed into two groups: control group and lipopolysaccharide (LPS) group. Endotoxemia was induced by a single caudal venous injection of LPS. Animals were sacrificed in batches 2, 6, 12 and 24 h after LPS infusion. The number of microfold (M)-cells, dendritic cells (DCs), CD4(+) T cells, CD8(+) T cells, regulatory T (Tr) cells and IgA(+) B cells in the intestinal mucosa were counted after immunohistochemical staining. Apoptotic lymphocytes were counted after TUNEL staining. The levels of interleukin (IL)-4, interferon (IFN)-gamma and forkhead box P3 (Foxp3) in mucosal homogenates were measured by ELISA. The secretory IgA (sIgA) content in the total protein of one milligram of small intestinal mucus was detected using a radioimmunological assay.ResultsThis research demonstrated that LPS-induced endotoxemia results in small intestinal mucosa injury. The number of M-cells, DCs, CD8(+) T cells, and IgA(+) B cells were decreased while Tr cell and apoptotic lymphocyte numbers were increased significantly. The number of CD4(+) T cells increased in the early stages and then slightly decreased by 24 h. The level of IL-4 significantly increased in the early stages and then reversed by the end of the study period. The level of IFN-gamma increased slightly in the early stages and then decreased markedly by the 24 h time point. Level of Foxp3 increased whereas sIgA level decreased.ConclusionMucosal immune dysfunction forms part of the intestinal barrier injury during endotoxemia. The increased number and function of Tr cells as well as lymphocyte apoptosis result in mucosal immunodeficiency.
Project description:BackgroundLiangxue Tongyu prescription (LTP) is a commonly used formula for acute intracerebral hemorrhage (AICH) in clinical practice that has significant ameliorative effects on neurological deficits and gastrointestinal dysfunction, yet the mechanism remains elusive. The aim of this study was to investigate the pathway by which LTP alleviates brain damage in AICH rats.MethodsThe AICH rat models were established by autologous caudal arterial blood injection. The neurological function scores were evaluated before and after treatment. The water content and the volume of Evans blue staining in the brain were measured to reflect the degree of brain damage. RT-PCR was used to detect the inflammatory factors of the brain. Western blotting was used to detect the expression of the tight junction proteins zonula occludens 1 (ZO-1), occludin (OCLN), and claudin (CLDN) in the brain and colon, followed by mucin 2 (MUC2), secretory immunoglobulin A (SIgA), and G protein-coupled receptor 43 (GPR43) in the colon. Flow cytometry was used to detect the ratios of helper T cells 17 (Th17) and regulatory T cells (Treg) in peripheral blood, and the vagus nerve (VN) discharge signals were collected.ResultsLTP reduced the brain damage of the AICH rats. Compared with the model group, LTP significantly improved the permeability of the colonic mucosa, promoted the secretion of MUC2, SigA, and GPR43 in the colon, and regulated the immune balance of peripheral T cells. The AICH rats had significantly faster VN discharge rates and lower amplitudes than normal rats, and these abnormalities were corrected in the LTP and probiotics groups.ConclusionLTP can effectively reduce the degree of brain damage in AICH rats, and the mechanism may be that it can play a neuroprotective role by regulating the function of the intestinal mucosal barrier.
Project description:Background: Intestinal mucosal barrier dysfunction plays an important role in the development of diabetes mellitus (DM). Berberine (BBR), a kind of isoquinoline alkaloid, is widely known to be effective for both DM and diarrhea. Here, we explored whether the anti-diabetic effect of BBR was related to the intestine mucosal barrier. Methods and Results: The rat model of T2DM was established by high glucose and fat diet feeding and intravenous injection of streptozocin. Then, those diabetic rats were treated with BBR at different concentrations for 9 weeks. The results showed, in addition to hyperglycemia and hyperlipidemia, diabetic rats were also characterized by proinflammatory intestinal changes, altered gut-derived hormones, and 2.77-fold increase in intestinal permeability. However, the treatment with BBR significantly reversed the above changes in diabetic rats, presenting as the improvement of the high glucose and triglyceride levels, the relief of the inflammatory changes of intestinal immune system, and the attenuation of the intestinal barrier damage. BBR treatment at a high concentration also decreased the intestinal permeability by 27.5% in diabetic rats. Furthermore, BBR regulated the expressions of the molecules involved in TLR4/MyD88/NF-κB signaling pathways in intestinal tissue of diabetic rats. Conclusion: The hypoglycemic effects of BBR might be related to the improvement in gut-derived hormones and the attenuation of intestinal mucosal mechanic and immune barrier damages.
Project description:Exposure to microgravity or weightlessness leads to various adaptive and pathophysiological alterations in digestive structures and physiology. The current study was carried out to investigate responses of intestinal mucosal barrier functions to simulated weightlessness, by using the hindlimb unloading rats model. Compared with normal controls, simulated weightlessness damaged the intestinal villi and structural integrity of tight junctions, up-regulated the expression of pro-apoptotic protein Bax while down-regulated the expression of anti-apoptotic protein Bcl-2, thus improved the intestinal permeability. It could also influence intestinal microbiota composition with the expansion of Bacteroidetes and decrease of Firmicutes. The predicted metagenomic analysis emphasized significant dysbiosis associated differences in genes involved in membrane transport, cofactors and vitamins metabolism, energy metabolism, and genetic information processing. Moreover, simulated weightlessness could modify the intestinal immune status characterized by the increase of proinflammatory cytokines, decrease of secretory immunoglobulin A, and activation of TLR4/MyD88/NF-κB signaling pathway in ileum. These results indicate the simulated weightlessness disrupts intestinal mucosal barrier functions in animal model. The data also emphasize the necessity of monitoring and regulating astronauts' intestinal health during real space flights to prevent breakdowns in intestinal homeostasis of crewmembers.
Project description:Although high-fat diet (HFD)-related dysbiosis is involved in the development of steatohepatitis, its pathophysiology especially in the small intestine remains unclear. We comprehensively investigated not only the liver pathology but also the microbiome profile, mucosal integrity and luminal environment in the small intestine of mice with HFD-induced obesity. C57BL/6J mice were fed either a normal diet or an HFD, and their small-intestinal contents were subjected to microbial 16S rDNA analysis. Intestinal mucosal permeability was evaluated by FITC-dextran assay. The levels of bile acids in the small-intestinal contents were measured by liquid chromatography/mass spectrometry. The expression of tight junction molecules, antimicrobial peptides, lipopolysaccharide and macrophage marker F4/80 in the small intestine and/or liver was examined by real-time RT-PCR and immunohistochemistry. The abundance of Lactobacillus was markedly increased and that of Clostridium was drastically decreased in the small intestine of mice fed the HFD. The level of conjugated taurocholic acid was significantly increased and those of deconjugated cholic acid/secondary bile acids were conversely decreased in the small-intestinal contents. The expression of occludin, antimicrobial Reg IIIβ/γ and IL-22 was significantly decreased in the small intestine of HFD-fed mice, and the intestinal permeability was significantly accelerated. Infiltration of lipopolysaccharide was significantly increased in not only the small-intestinal mucosa but also the liver of HFD-fed mice, and fat drops were apparently accumulated in the liver. Pathophysiological alteration of the luminal environment in the small intestine resulting from a HFD is closely associated with minimal inflammation involving the gut-liver axis through disturbance of small-intestinal mucosal integrity.
Project description:BackgroundSimo decoction (SMD) is a traditional prescription for treating gastrointestinal diseases. More and more evidences prove that SMD can treat constipation by regulating intestinal microbiota and related oxidative stress indicators, but the specific mechanism is still unclear.MethodsA network pharmacological analysis was used to predict the medicinal substances and potential targets of SMD to alleviate constipation. Then, 15 male mice were randomly divided into normal group (MN group), natural recovery group (MR group), and SMD treatment group (MT group). Constipation model mice were constructed by gavage of Folium sennae decoction and control of diet and drinking water, and SMD was used for intervention after successful modeling. The levels of 5-hydroxytryptamine (5-HT), vasoactive intestinal peptide (VIP), superoxide dismutase (SOD), malondialdehyde (MDA), and fecal microbial activities were measured, and the intestinal mucosal microbiota was sequenced.ResultNetwork pharmacology analysis showed that a total of 24 potential active components were obtained from SMD, and 226 target proteins were obtained after conversion. Meanwhile, we obtained 1,273 and 424 disease-related targets in the GeneCards database and the DisGeNET database, respectively. After combination and deduplication, the disease targets shared 101 targets with the potential active components of SMD. When the mice were intervened with SMD, the 5-HT, VIP, MDA, SOD content, and microbial activity in MT group were close to MN group, and Chao 1 and ACE in MT group were significantly higher than that in MR group. In the Linear discriminant analysis Effect Size (LEfSe) analysis, the abundance of beneficial bacteria such as Bacteroides, Faecalibacterium, Alistipes, Subdoligranulum, Lactiplantibacillus, and Phascolarctobacterium in MT group increased. At the same time, there were some associations between microbiota and brain-gut peptides and oxidative stress indicators.ConclusionSMD can promote intestinal health and relieve constipation through brain-bacteria-gut axis associating with intestinal mucosal microbiota and alleviate oxidative stress.
Project description:BackgroundLumenal glucose initiates changes in gastrointestinal (GI) function, including inhibition of gastric emptying, stimulation of pancreatic exocrine and endocrine secretion, and intestinal fluid secretion. Glucose stimulates the release of GI hormones and 5-hydroxytryptamine (5-HT), and activates intrinsic and extrinsic neuronal pathways to initiate changes in GI function. The precise mechanisms involved in luminal glucose-sensing are not clear; studying gut endocrine cells is difficult due to their sparse and irregular localization within the epithelium.MethodsHere we show a technique to determine activation of gut epithelial cells and the gut-brain pathway in vivo in rats using immunohistochemical detection of the activated, phosphorylated, form of calcium-calmodulin kinase II (pCaMKII).Key resultsPerfusion of the gut with glucose (60 mg) increased pCaMKII immunoreactivity in 5-HT-expressing enterochromaffin (EC) cells, cytokeratin-18 immunopositive brush cells, but not in enterocytes or cholecystokinin-expressing cells. Lumenal glucose increased pCaMKII in neurons in the myenteric plexus and nodose ganglion, nucleus of the solitary tract, dorsal motor nucleus of the vagus and the arcuate nucleus. pCaMKII expression in neurons, but not in EC cells, was significantly attenuated by pretreatment with the 5-HT(3) R antagonist ondansetron. Deoxynojirimycin, a selective agonist for the putative glucose sensor, sodium-glucose cotransporter-3 (SGLT-3), mimicked the effects of glucose with increased pCaMKII in ECs and neurons; galactose had no effect.Conclusions & inferencesThe data suggest that native EC cells in situ respond to glucose, possibly via SGLT-3, to activate intrinsic and extrinsic neurons and thereby regulate GI function.
Project description:Inflammatory bowel disease (IBD), a chronic intestinal inflammatory condition, awaits safe and effective preventive strategies. Naturally occurring flavonoid compounds are promising therapeutic candidates against IBD due to their great antioxidant potential and ability to reduce inflammation and improve immune signaling mediators in the gut. In this study, we utilized two maize near-isogenic lines flavan-4-ols-containing P1-rr (F+) and flavan-4-ols-lacking p1-ww (F-) to investigate the anti-inflammatory property of flavan-4-ols against carboxymethylcellulose (CMC)-induced low-grade colonic inflammation. C57BL/6 mice were exposed to either 1% CMC (w/v) or water for a total of 15 weeks. After week six, mice on CMC treatment were divided into four groups. One group continued on the control diet. The second and third groups were supplemented with F+ at 15% or 25% (w/w). The fourth group received diet supplemented with F- at 15%. Here we report that mice consuming F+(15) and F+(25) alleviated CMC-induced increase in epididymal fat-pad, colon histology score, pro-inflammatory cytokine interleukin 6 expression and intestinal permeability compared to mice fed with control diet and F-(15). F+(15) and F+(25) significantly enhanced mucus thickness in CMC exposed mice (p < 0.05). These data collectively demonstrated the protective effect of flavan-4-ol against colonic inflammation by restoring intestinal barrier function and provide a rationale to breed for flavan-4-ols enriched cultivars for better dietary benefits.
Project description:Low molecular seleno-aminopolysaccharide (LSA) was synthesized with sodium selenite and low molecular aminopolysaccharide (LA), which is an organic selenium compound. This study is aimed to investigate the protective effect of LSA on the intestinal mucosal barrier in weaning stress rats by detecting the intestinal tissue morphology and function, mucosal thickness and permeability, the structure of MUC2, antioxidant index, the expression level of intracellular transcription factor NF-E2-related factor 2 (Nrf2), and its related factors. The results showed that LSA significantly increased the height of intestinal villi (p < 0.05) and increased the thickness of intestinal mucosa and the number of goblet cells, which indicated that LSA has a protective effect on the intestinal mucosal barrier that is damaged by weaning. Moreover, LSA significantly reduced the level of DAO, D-LA, and LPS compared with the weaning group (p < 0.05), which indicated that LSA reduced the intestinal damage and permeability of weaning rats. In addition, LSA could increase the number and length of glycans chains and the abundance of acid glycans structures in the MUC2 structure, which indicated that LSA alleviated the changes of intestinal mucus protein structure. LSA significantly increased the levels of GSH-Px, SOD, LDH, and CAT, while it decreased the level of MDA in serum and intestinal tissue, which suggested that LSA significantly enhanced the antioxidant capacity and reduced oxidative stress of weaning rats. RT-PCR results showed that LSA significantly increased the expression level of antioxidant genes (GSH-Px, SOD, Nrf2, HO-1), glycosyltransferase genes (GalNT1, GalNT3, GalNT7) and mucin gene (MUC2) in intestinal mucosa (p < 0.05). The results of western blot showed that the LSA activated the Nrf2 signaling pathway by down-regulating the expression of Keap1and up-regulating the expression of Nrf2, and protected the intestinal mucosa from oxidative stress. Overall, LSA could play a protective role in intestinal mucosal barrier of weaning rats by activating the Nrf2 pathway and alleviating the alnormal change of mucin MUC2.