The small intestine: barrier, permeability and microbiota

New noninvasive biomarkers of intestinal inflammation and increased intestinal permeability in pediatric inflammatory bowel diseases and their correlation with fecal calprotectin: a pilot study

BACKGROUND

Increased intestinal permeability is considered to play a crucial role in the pathogenesis of inflammatory bowel diseases (IBD). Therefore, recently, the use of non-invasive biomarkers in both diagnosis and monitoring IBD is emphasized. The aim of this study was to investigate fecal and serum zonulin and serum I-FABP in pediatric IBD patients and their correlation with fecal calprotectin (FCP).

METHODS

Seventy-one individuals: 32 Crohn's disease (CD) patients, 33 ulcerative colitis (UC) patients and 6 controls were examined for fecal and serum zonulin and plasma I-FABP. Values were correlated to FCP and to each other for all children included in the study. A stool specimen and blood samples were collected during check-up visits at hospital. Then fecal and serum zonulin, I-FABP and FCP were tested by ELISA Test. Non-parametric statistical tests were used for data analysis.

RESULTS

The level of fecal zonulin and FCP were higher in IBD patients compared to control group (CG): median for CD - 46.0 (7.0-3854) ng/mL, 252.0 (77.0-1054.2) ug/g; UC - 115.3 (50.7-418.3) ng/mL, 40 (16.0-1883.0) ug/g; CG - 60.8 (31.8-123.0) ng/mL, 41.5 (31.0-323.0) ug/g, respectively, (P<0.05). No statistically significant difference in concentrations of serum zonulin and I-FABP was reported between patients and CG (P=0.55). The only correlation that has been reported was between fecal zonulin and FCP and the strongest one was in CD: CD-R =0.73, UC-R =0.67, All-R =0.67, CG-R =0.65.

CONCLUSIONS

According to our results it seems that only fecal zonulin may serve as another, next to FCP, biomarker of intestinal damage in IBD. However, both fecal and serum zonulin as well as I-FABP need further studies to assess their usefulness in diagnostics and monitoring in IBD.

Fermentation of Ganoderma lucidum and Raphani Semen with a probiotic mixture attenuates cyclophosphamide-induced immunosuppression through microbiota-dependent or -independent regulation of intestinal mucosal barrier and immune responses

BACKGROUND

Probiotic fermentation is a promising strategy for improving the nutritional and functional properties of traditional Chinese medicines (TCMs). Ganoderma lucidum and Raphani Semen are famous TCMs that have been shown to help alleviate immune system disorders. However, few studies have experimentally investigated the effects of probiotic-fermented G.lucidum and Raphani Semen on the immune system.

PURPOSE

We established the in vitro fermentation of G. lucidum and Raphani Semen with a probiotic mixture (Bifidobacterium longum, Lactobacillus acidophilus, and l. fermentum) (GRFB), investigated its ameliorating effect against cyclophosphamide (CTX)-induced immunosuppression, and explored its possible mechanisms.

METHODS

First, the different components in GRFB were identified by high-performance liquid chromatography. Second, its immune-stimulatory activities were evaluated in CTX-treated mice. Lastly, its possible in vitro and in vivo mechanisms were studied.

RESULTS

Probiotic fermentation of G. lucidum and Raphani Semen altered some of its chemical constituents, potentially helping improve the ability of GRFB to alleviate immunosuppression. As expected, GRFB effectively ameliorated CTX-induced immunosuppression by increasing the number of splenic lymphocytes and regulating the secretion of serum and ileum cytokines. GRFB supplementation also effectively improved intestinal integrity in CTX-treated mice by upregulating tight junction proteins. It also protects against CTX-induced intestinal dysbiosis by increasing the abundance of beneficial bacteria and reducing the abundance of harmful bacteria. GRFB could directly promote intestinal immunity but not systemic immunity in vitro, suggesting a microbiota-dependent regulation of GRFB. Interestingly, cohousing CTX-induced immunosuppressed mice with GRFB-treated mice promoted their symptoms recovery. Enhanced CTX-induced immunosuppression by GRFB in vitro depended on the gut microbiota. Remarkably, a Kyoto Encyclopedia of Genes and Genomes analysis showed that the GRFB-reprogrammed microbiota was significantly enriched in DNA damage repair pathways, which contribute to repairing the intestinal mucosal barrier.

CONCLUSION

This is the first study to suggest that compare with unfermented G. lucidum and Raphani Semen, GRFB can more effectively promote intestinal immunity and manipulate the gut microbiota to promote immunostimulatory activity and repair immunosuppression-induced intestinal barrier damage by biotransforming G.lucidum and Raphani Semen components.

Fecal and Circulating Biomarkers for the Non-Invasive Assessment of Intestinal Permeability

The study of intestinal permeability is gaining growing interest due to its relevance in the onset and progression of several gastrointestinal and non-gastrointestinal diseases. Though the involvement of impaired intestinal permeability in the pathophysiology of such diseases is recognized, there is currently a need to identify non-invasive biomarkers or tools that are able to accurately detect alterations in intestinal barrier integrity. On the one hand, promising results have been reported for novel in vivo methods based on paracellular probes, i.e., methods that can directly assess paracellular permeability and, on the other hand, on fecal and circulating biomarkers able to indirectly assess epithelial barrier integrity and functionality. In this review, we aimed to summarize the current knowledge on the intestinal barrier and epithelial transport pathways and to provide an overview of the methods already available or currently under investigation for the measurement of intestinal permeability.

The Barrier-Enhancing Function of Soluble Yam (Dioscorea opposita Thunb.) Polysaccharides in Rat Intestinal Epithelial Cells, as Affected by the Covalent Se Conjugation

The non-starch yam polysaccharides (YP) are the bioactive substances of edible yam, while Se is an essential nutrient for the human body. Whether a covalent conjugation of Se to YP might cause bioactivity change for the resultant selenylated YP in the intestine is still insufficiently studied, including the critical intestinal barrier function. In this study, two selenylated YP products, namely, YPSe-I and YPSe-II, with corresponding Se contents of 795 and 1480 mg/kg, were obtained by the reaction of YP and Na2SeO3 in the presence of HNO3 and then assessed for their bioactivities to a cell model (i.e., rat intestinal epithelial IEC-6 cells). The results showed that YP, YPSe-I, and YPSe-II at 5–80 μg/mL dosages could promote cell growth with treatment times of 12–24 h. The three samples also could improve barrier integrity via increasing cell monolayer resistance and anti-bacterial activity against E. coli or by reducing paracellular permeability and bacterial translocation. Additionally, the three samples enhanced F-actin distribution and promoted the expression of the three tight junction proteins, namely, zonula occluden-1, occludin, and claudin-1. Meanwhile, the expression levels of ROCK and RhoA, two critical proteins in the ROCK/RhoA singling pathway, were down-regulated by these samples. Collectively, YPSe-I and, especially, YPSe-II were more potent than YP in enhancing the assessed bioactivities. It is thus concluded that this chemical selenylation of YP brought about enhanced activity in the cells to promote barrier integrity, while a higher selenylation extent of the selenylated YP induced much activity enhancement. Collectively, the results highlighted the important role of the non-metal nutrient Se in the modified polysaccharides.