Gracilaria fisheri oligosaccharides ameliorate inflammation and colonic epithelial barrier dysfunction in mice with acetic acid-induced colitis

Objective:To investigate the effect of Gracilaria fisheri oligosaccharides(GFO)on inflammation and colonic epithelial barrier dysfunction in colitis mice.Methods:The animals were treated by oral gavage with distilled water,1000 mg/kg inulin,100,500,or 1000 mg/kg GFO for 14 d,or treated with 50 mg/kg mesalamine for 5 d after colitis induction(on day 10).Histopathology,inflammatory cytokines,colonic permeability,and tight junction proteins were investigated by hematoxylin and eosin staining,immunohistochemical staining,Ussing chamber technique,and Western blotting assays,respectively.Results:GFO ameliorated histological damage in colitis mice when compared to untreated colitis mice.Treatments with 100,500,and 1000 mg/kg GFO reduced TNF-αexpression,while IL-1βwas significantly reduced in colitis mice treated with 500 and 1000 mg/kg.Compared to untreated colitis mice,GFO increased transepithelial electrical resistance,reduced fluorescein isothiocyanate-dextran paracellular flux,and modulated tight junction proteins(occludin and claudin 2)in colitis mice.Conclusions:GFO has anti-inflammatory activity and could modulate colonic epithelial barrier dysfunction in acetic acid-induced colitis mice.Furthermore,GFO could modulate the expression of tight junction proteins that play important roles in colonic barrier function.

Moxibustion down-regulates colonic epithelial cell apoptosis and repairs tight junctions in rats with Crohn's disease

AIM: To investigate the effects of moxibustion on down-regulation of the colonic epithelial cell apoptosis and repair of the tight junctions in rats with Crohn's disease (CD). METHODS: Sixty male Sprague-Dawley rats were randomly divided into a normal control (NC) group, a model control (MC) group, an herbs-partitioned moxibustion (HPM) group, a mild-warm moxibustion (MWM) group and a salicylazosulphapyridine (SASP) group, with 12 rats in each group. The CD model rats were treated with trinitrobenzene sulphonic acid to induce intestinal inflammation. The rats in the HPM and MWM groups were treated at the Tianshu (ST25) and Qihai (CV6) acupoints once daily for 14 d, and the SASP group was fed SASP twice daily for 14 d. No additional treatment was given to the MC and NC groups. Themicrostructure of the colonic epithelium was observed under a transmission electron microscope, the transepithelial resistance was measured using a shortcircuit current, colonic epithelial cell apoptosis was determined by terminal deoxynucleotidyl transferasemediated dUTP-biotin nick end labelling assay, and the expression of occludin, claudin-1 and zonula occludens-l (ZO-1) in the colonic epithelial junction was determined by Western blotting and immunofluorescence staining. RESULTS: Compared with the MC group, the microstructure of the colonic epithelial barrier was signifi-cantly improved in rats treated with HPM, MWM or SASP, meanwhile, the current flow was reduced signifi-cantly, with values of 168.20 ± 6.14 vs 99.70 ± 3.13, 99.10 ± 4.28 and 120.30 ± 3.65 mA, respectively (P = 0.001). However, the HPM and MWM groups had higher current flow rates than the SASP group (99.70 ± 3.13, 99.10 ± 4.28 vs 120.30 ± 3.65 mA, P = 0.001). The number of the apoptotic colonic epithelial cells in HPM, MWM and SASP groups was largely reduced (61.5 ± 16.91 vs 15.5 ± 8.89, 14.8 ± 6.27 and 24.7 ± 9.68, respectively (P = 0.001); and the expression of occlu- din, claudin-1 and ZO-1 in the MWM and HPM groups was signifi cantly enhanced (0.48 ± 0.10, 0.64 ± 0.09 vs 0.18 ± 0.05 for occludin, 0.12 ± 0.02, 0.17 ± 0.03 vs 0.05 ± 0.01 for claudin-1, and 0.08 ± 0.01, 0.11 ± 0.01 vs 0.02 ± 0.01 for ZO-1). And in SASP group, the expression of occludin and ZO-1 was also signifi cantly increased (0.27 ± 0.04 vs 0.18 ± 0.05 for occludin and 0.05 ± 0.01 vs 0.02 ± 0.01 for ZO-1), but there was no significant difference for claudin-1. The HPM and MWM groups had higher expression of occludin, claudin-1 and ZO-1 than the SASP group. CONCLUSION: HPM and MWM treatment can down-regulate apoptosis of colonic epithelial cells, repair tight junctions and enhance colonic epithelial barrier function in rats with CD.

Vitamin A deficiency suppresses CEACAM1 to impair colonic epithelial barrier function via downregulating microbial-derived short-chain fatty acids

Vitamin A (VA) plays an essential role in modulating both the gut microbiota and gut barrier function.Short-chain fatty acids (SCFAs),as metabolites of the gut microbiota,protect the physiological intestinal barrier;however,they are compromised when VA is deficient.Thus,there is an urgent need to understand how and which SCFAs modulate colonic epithelial barrier integrity in VA deficiency (VAD).Herein,compared with normal VA rats (VAN),at the beginning of pregnancy,we confirmed that the colonic desmosome junction was impaired in the VAD group,and the amounts of acetate,propionate,and butyrate declined because of the decreased abundance of SCFA-producing bacteria (Romboutsia ,Collinsella ,and Allobaculum ).The differentially expressed genes correlated with the gut barrier and the histone deacetylase complex between the VAD and VAN groups were enriched by RNA sequencing.In the VAD group,the expression levels of colonic CEA cell adhesion molecule 1 (CEACAM1) were down-regulated,and the levels of histone deacetylase 1 (HDAC1) and HDAC3 were up-regulated.Intriguingly,the above changes in the VAD groups were rescued by VA supplementation in the early postnatal period.Further study indicated that in Caco-2 cells,butyrate treatment significantly repressed the enrichment of HDAC3 on the promoter of the CEACAM1 gene to induce its expression.Our findings support that butyrate intervention can alleviate the impairment of colonic barrier function caused by VAD,and timely postnatal VA intervention may reverse the damage caused by VAD on gut barrier integrity during pregnancy.

Aquaporin-8 expression is reduced in ileum and induced in colon of patients with ulcerative colitis

AIM： To study susceptibility genes which may play a potential role in the pathogenesis and etiology of inflammatory bowel disease （IBD）. METHODS： To identify potential susceptibility genes we performed global gene expression profiling in patients with IBD and control specimens. For determination of an intrinsic gene expression profile in ulcerative colitis （UC） and Crohn＇s disease （CD） compared to normal subjects, mucosal biopsies of non-inflamed regions of the colon and the terminal ileum were subjected to DNA microarray analysis. Real-time RT-PCR and immunohistochemistry were used for verification of selected regulated candidate genes and a genetic analysis was performed. RESULTS： We could show that aquaporin-8 （AQP8） mRNA and protein levels were significantly increased in the colon of UC patients compared to controls. Genetic analysis of the six exons and the promoter region of AQPS, however, revealed no mutations or polymorphisms in IBD patients. CONCLUSION： Our results suggest that upregulation of AQP8 in the colon of UC patients represents a secondary phenomenon which may, due to altered water exchange of the distal intestinal mucosa, disturb the physiologic colonic mucus barrier and thus lead to chronic inflao mmation and ulceration.

PEGylated bacteria restore intestinal mucosal barrier

The mucosal barrier of the gastrointestinal tract(GIT)is crucial for the overall health of the body.Its disruption permits the infiltration of intestinal microorganisms into the underlying mucosa,resulting in infections and inflammatory conditions,such as inflammatory bowel disease(IBD),metabolic disorders,and autoimmune diseases^(1,2).Therefore,strategies to protect the mucosal barrier from exogenous stimuli or to facilitate its recovery have become increasingly important.Currently,immunomodulators,corticosteroids,and biological agents have been widely employed to treat IBD by alleviating inflammation and enhancing mucosal healing.Unfortunately,they can also produce serious systemic toxicity^(3,4);therefore,there is an urgent need for exploiting innovative strategies to fortify the intestinal mucosal barrier against the invasion of exogenous damaging factors.