Isolation and gene expression profiling of intestinal epithelial cells: crypt isolation by calcium chelation from in vivo samples

The Role of Activating Transcription Factor 3 in Metformin's Alleviation of Gastrointestinal Injury Induced by Restraint Stress in Mice

Metformin is one of the most commonly used drugs for type 2 diabetes mellitus. In addition to its anti-diabetic property, evidence suggests more potential applications for metformin, such as antiaging, cellular protection, and anti-inflammation. Studies have reported that metformin activates pathways with anti-inflammatory effects, enhances the integrity of gut epithelial tight junctions, and promotes a healthy gut microbiome. These actions contribute to the protective effect of metformin against gastrointestinal (GI) tract injury. However, whether metformin plays a protective role in psychological-stress-associated GI tract injury remains elusive. We aim to elucidate the potential protective effect of metformin on the GI system and develop an effective intervention strategy to counteract GI injury induced by acute psychological stress. By monitoring the levels of GI-nonabsorbable Evans blue dye in the bloodstream, we assessed the progression of GI injury in live mice. Our findings demonstrate that the administration of metformin effectively mitigated GI leakage caused by psychological stress. The GI protective effect of metformin is more potent when used on wild-type mice than on activating-transcription-factor 3 (ATF3)-deficient (ATF3^-/-) mice. As such, metformin-mediated rescue was conducted in an ATF3-dependent manner. In addition, metformin-mediated protection is associated with the induction of stress-induced GI mRNA expressions of the stress-induced genes ATF3 and AMP-activated protein kinase. Furthermore, metformin treatment-mediated protection of CD326⁺ GI epithelial cells against stress-induced apoptotic cell death was observed in wild-type but not in ATF3^-/- mice. These results suggest that metformin plays a protective role in stress-induced GI injury and that ATF3 is an essential regulator for metformin-mediated rescue of stress-induced GI tract injury.

Differential analysis of intestinal microbiota and metabolites in mice with dextran sulfate sodium-induced colitis

BACKGROUND

Intestinal micro-ecological imbalances impair the intestinal barrier and induce intestinal inflammation, for example, ulcerative colitis (UC). According to the latest research, abnormalities in intestinal microbiota structure and their metabolites play a dominant role in UC progression; in addition, they could affect the mucus barrier based on different factors. Although numerous studies have confirmed the important role of intestinal microbiota in UC pathogenesis, the intricate connection between microbiota and metabolites and mucus barrier in UC occurrence remains unclear, and correlation analyses of differential microbiota and their metabolites under UC are relatively scarce.

AIM

To reveal the differential intestinal microbiota and metabolites in UC pathogenesis and explore more sensitive biomarker compositions.

METHODS

We used the antibiotic combination method to establish intestinal pseudo-aseptic mice; afterward, dextran sulfate sodium (DSS) was applied to establish an acute experimental colitis mice model. Colitis severity, assessed based on disease activity index, colorectal length, colorectal wet weight, and histological lesions, and mucus-related staining (mucopolysaccharide alcian blue and immunofluorescence of mucin), was compared between the pseudo-aseptic and bacterial colitis mice. Finally, differential intestinal microbiota, metabolites, and their association and correlations, were analyzed by 16s rDNA sequencing in combination with non-targeted metabolomics, through gas chromatography-mass spectrometry.

RESULTS

Compared with the pseudo-aseptic mice, intestinal bacteria positive mice were more severely ill and their intestinal mucus loss was more pronounced in DSS-induced colitis (P < 0.05), suggesting that different microbiota and metabolites could cause the different degrees of colitis. Subsequently, we observed that in addition to Klebsiella, and Bacteroides, which were widely associated with colitis, Candidatus Stoquefichus, Anaerobiospirillum, Muribaculum, and Negativibacillus may be involved in protection against colitis. Furthermore, differential metabolites of the microbiota were mainly enriched in the synthesis-related pathways of key structural sequences of mucin. In combination with the mucin-related staining and immunofluorescence results, the findings indicate that the differential microbiota and their metabolites potentially regulate the composition and function of mucus under colitis.

CONCLUSION

Microbiota and their metabolites are major factors regulating the composition and function of mucus, in turn influencing the function and structure of intestinal mucus barrier under colitis. The different microbiota and metabolites identified in the present study could be novel biomarkers for colitis.

Activating Transcription Factor 3 Protects against Restraint Stress-Induced Gastrointestinal Injury in Mice

Psychological stress increases the risk of gastrointestinal (GI) tract diseases, which involve bidirectional communication of the GI and nerves systems. Acute stress leads to GI ulcers; however, the mechanism of the native cellular protection pathway, which safeguards tissue integrality and maintains GI homeostasis, remains to be investigated. In a mouse model of this study, restraint stress induced GI leakage, abnormal tight junction protein expression, and cell death of gut epithelial cells. The expression of activating transcription factor 3 (ATF3), a stress-responsive transcription factor, is upregulated in the GI tissues of stressed animals. ATF3-deficient mice displayed an exacerbated phenotype of GI injuries. These results suggested that, in response to stress, ATF3 is part of the native cellular protective pathway in the GI system, which could be a molecular target for managing psychological stress-induced GI tract diseases.

Safety and Ethics in Endoscopic Studies in Children: Evidence From the BEECH Study in Zambia

BACKGROUND

Environmental enteropathy is an example of a poorly-understood intestinal disorder affecting millions of children worldwide, characterized by malabsorption and stunting. Although there is increasing interest in non-invasive means of assessing intestinal structure and function, the potential value of intestinal biopsy for histology, immunostaining, RNA sequencing and epigenetic work means that endoscopic biopsy remains extremely valuable. We here report our experience in the BEECH (Biomarkers of Environmental Enteropathy in CHildren) study of stunting in Zambia, in the belief that it may help address the knowledge gap regarding the safety of endoscopic biopsy in vulnerable young children.

METHODS

We report our experience of safety in 119 children undergoing endoscopic biopsy in the BEECH study in Lusaka Children's Hospital, Lusaka, and discuss ethical considerations in this light.

RESULTS

Upper gastrointestinal endoscopy was performed on children with stunting (length-for-age z score -2 or less) not responsive to nutritional interventions. Conscious sedation was provided by anaesthetists. Of 119 children, 5 (4%) developed transient desaturation, but no serious adverse events were experienced; no clinical, demographic or anaesthetic characteristics were identified as predictive of desaturation. Two children derived clinically useful information from the endoscopy, one life-saving. Of 105 lactase tests, 59 (54%) showed hypolactasia.

DISCUSSION

Children with stunting underwent endoscopy safely, and some derived clinical benefit. Safety and the possibility of clinical benefit are usually felt to be preconditions for the ethical justification for endoscopy for research in children, and we believe that these conditions were met in this study.

Protective Effects of Tyrosol Against DSS-Induced Ulcerative Colitis in Rats

In this study, the effects of tyrosol were investigated in DSS-induced experimental ulcerative colitis model. For this purpose, rats were divided into five groups of seven rats in each: control group, colitis group (DSS-4%), tyrosol group (tyrosol 20 mg/kg), sulfasalazine (sulfasalazine+DSS 100 mg/kg), and treatment group (tyrosol+DSS 20 mg/kg). In the study, the active substances were administered to all animals for a period of 21 days. At the end of the study, malondialdehyde (MDA) levels increased (p < 0.001); GSH level (p < 0.05) along with GSH.Px (p < 0.01) and CAT (p < 0.001) activities decreased in the DSS-induced colitis group. However, with the administration of tyrosol, MDA and GSH levels along with GSH.Px and CAT activities came to the same levels as the control group. In the colitis group, an increase occurred in IL-6, COX-2, and NF-κB parameters, which created a significant difference compared to the control group (p < 0.001). Similarly, TNF-α levels also significantly increased with the administration of DSS (p < 0.05) which created a significant difference compared to the control group, while there was no difference among the other groups. As for the Nrf-2 data, it decreased with the administration of DSS which created a significant difference compared to the control group (p < 0.05), while there was no difference in other groups. In the colitis-induced group, IL-6, COX-2, and NF-κB gene expression levels also similarly increased but returned to the normal levels with the administration of tyrosol. In the histopathological scoring, the negativity that increased with the administration of DSS returned to the normal levels with the administration of tyrosol+DSS. In conclusion, according to the data obtained, tyrosol fixed the destruction picture in the DSS-induced colitis model, giving rise to thought that it has a protective effect.

Intrarectally administered polaprezinc attenuates the development of dextran sodium sulfate-induced ulcerative colitis in mice

Polaprezinc (PZ), a chelate of zinc and L-carnosine, has been widely used in the treatment of gastric ulcers since 1994. In recent years, researchers have found PZ to have a beneficial effect on various experimentally induced models of colitis in mice. In the present study, 6% dextran sodium sulfate (DSS) was used to induce a model of ulcerative colitis (UC) in Institute of Cancer Research mice. The therapeutic effect and mechanism of PZ action in a model of UC was studied in order to provide an experimental basis for the clinical application of PZ in UC treatment. The effect of PZ on UC was evaluated in five groups of mice: A vehicle control only group, a DSS model control group (DSS, 6%), a validated treatment control group (DSS 6% + Mesalamine), a low-dose PZ treatment group (DSS 6% + PZ 60 mg/kg) and a high-dose PZ group (DSS 6% + PZ 120 mg/kg). After the animals were sacrificed, blood was collected and the serum levels of NF-κB and tumor necrosis factor-α (TNF-α) were measured. Changes in histology were observed by light microscopy. The protein levels of AKT, phosphorylated AKT and heat shock protein 70 (HSP70) were determined by western blot analysis. The results suggested that PZ reduced the DSS-induced increase in the inflammatory proteins TNF-α and NF-κB in the UC model. The high-dose of PZ also increased the HSP70 protein level, inhibited AKT phosphorylation in a DSS-induced UC animal model, and decreased white blood cell and neutrophil % counts compared to levels in an untreated DSS control group. Histopathology indicated that the mice of the DSS model group had irregular colonic villi, a large number of inflammatory cells and mucosal damage, whereas mice of the group treated with PZ had small intestinal villus morphology and their villi showed signs of recovery from the damage of UC. The results of the present study indicated that PZ significantly alleviates DSS-induced UC in mice, relieves diarrhea, and inhibits the phosphorylation of inflammatory factors and the inflammatory AKT signaling pathway.

The inhibitory effects of Qingchang Wenzhong granule on the interactive network of inflammation, oxidative stress, and apoptosis in rats with dextran sulfate sodium-induced colitis

BACKGROUND

Ulcerative colitis (UC) is a kind of complex immune disease, the pathogenesis of which remains elusive. Destruction of the intestinal barrier, extreme inflammation, oxidative stress, and apoptosis might play key roles in the development of UC. In previous studies, we observed that Qingchang Wenzhong granule (QCWZG) had the exact effect on the remission of UC in the clinic; however, the underlying mechanism has not been identified. This study aimed to reveal the effects of QCWZG on the intestinal physical barrier and the interactive network of inflammation, oxidative stress, and apoptosis in rats with dextran sulfate sodium (DSS)-induced colitis.

METHODS

Sixty rats were randomly divided into six groups: blank group, model group, high/mild/low-dose QCWZG groups, and mesalazine group. The rats in the experimental group drank 4% DSS for 7 days and 1% DSS for the subsequent 7 days. Different medications or distilled water was supplied by intragastric administration for 7 days. The levels of colitis and indices related to inflammation, oxidative stress, and apoptosis were assessed.

RESULTS

Compared with the model group, the QCWZG group (P < 0.05) demonstrated attenuated disease activity index, colonic mucosa disease index, histological lesions, and colonic weights; lower levels of inflammatory substances, such as interleukin (IL)-1α, IL-6, tumor necrosis factor-α, and myeloperoxidase; lower levels of malondialdehyde; and increased levels of superoxide dismutase and glutathione peroxidase. The QCWZG group also demonstrated elevated expression of Bcl-2 and occluding but downregulated db expression of Bax and caspase 3 in the colon.

CONCLUSION

QCWZG could relieve rats with DSS-induced colitis from UC symptoms by improving the intestinal physical barrier, which resists the interactive network of inflammation, oxidative stress, apoptosis, and their overactivated interactions.