Propionate-engineered probiotics reduce radiation-induced intestinal damage.

Reply to: “Uncovering the molecular events associated with increased intestinal permeability in liver cirrhosis: The pivotal role of enterocyte tight junctions and future perspectives”

Young animals are highly susceptible to intestinal damage due to incomplete intestinal development, making them vulnerable to external stimuli. Weaning stress in piglets, for instance, disrupts the balance of intestinal microbiota and metabolism, triggering intestinal inflammation and resulting in gut damage. Caffeic acid (CA), a plant polyphenol, can potentially improve intestinal health. Here, we evaluated the effects of dietary CA on the intestinal barrier and microbiota using a lipopolysaccharide (LPS)-induced intestinal damage model. Eighteen piglets were divided into three groups: control group (CON), LPS group (LPS), and CA + LPS group (CAL). On the 21st and 28th day, six piglets in each group were administered either LPS (80 μg/kg body weight; Escherichia coli O55:B5) or saline. The results showed that dietary CA improved the intestinal morphology and barrier function, and alleviated the inflammatory response. Moreover, dietary CA also improved the diversity and composition of the intestinal microbiota by increasing Lactobacillus and Terrisporobacter while reducing Romboutsia. Furthermore, the LPS challenge resulted in a decreased abundance of 14 different bile acids and acetate, which were restored to normal levels by dietary CA. Lastly, correlation analysis further revealed the potential relationship between intestinal microbiota, metabolites, and barrier function. These findings suggest that dietary CA could enhance intestinal barrier function and positively influence intestinal microbiota and its metabolites to mitigate intestinal damage in piglets. Consuming foods rich in CA may effectively reduce the incidence of intestinal diseases and promote intestinal health in piglets.

Anthocyanin Improves Glucose Homeostasis in Obese Mice via Beneficial Regulation of Intestinal Microbiota and Barrier Function (OR34-08-19)

Lung cancer survival is poor and radiotherapy patients often suffer serious treatment side effects. The esophagus is particularly sensitive leading to reduced food intake or even fistula formation. Only few direct techniques exist to measure radiation-induced esophageal damage, for which knowledge is needed to improve the balance between risk of tumor recurrence and complications. Optical coherence tomography (OCT) is a minimally-invasive imaging technique that obtains cross-sectional, high-resolution (1-10µm) images and is capable of scanning the esophageal wall up to 2-3mm depth. In this study we investigated the feasibility of OCT to detect esophageal radiation damage in mice. In total 30 mice were included in 4 study groups (1 main and 3 control groups). Mice underwent cone-beam CT imaging for initial setup assessment and dose planning followed by single-fraction dose delivery of 4, 10, 16, and 20Gy on 5mm spots, spaced 10mm apart. Mice were repeatedly imaged using OCT: pre-irradiation and up to 3 months post-irradiation. The control groups received either OCT only, irradiation only, or were sham-operated. We used histopathology as gold standard for radiation-induced damage diagnosis. The study showed edema in both the main and OCT-only groups. Furthermore, radiation-induced damage was primarily found in the highest dose region (distal esophagus). Based on the histopathology reports we were able to identify the radiation-induced damage in the OCT images as a change in tissue scattering related to the type of induced damage. This finding indicates the feasibility and thereby the potentially promising role of OCT in radiation-induced esophageal damage assessment.

The effect of heme oxygenase-1 induction by octreotide on radiation enteritis

ABSTRACTRadiation-induced enteritis is a major side effect in cancer patients undergoing abdominopelvic radiotherapy. The Nrf2/HO-1 pathway is a critical endogenous antioxidant stress pathway, but its precise role in radiation-induced enteritis remains to be clarified. Polysaccharides extracted from Rheum tanguticum (RTP) can protect the intestinal cells from radiation-induced damage, but the underlying mechanism is unknown. SD rats and IEC-6 cells were exposed to 12 or 10 Gy X-ray radiation. Rat survival, and histopathological and immunohistochemical profiles were analyzed at different time points. Indicators of oxidative stress and inflammatory response were also assessed. Cell viability, apoptosis and Nrf2/HO-1 expression were evaluated at multiple time points. Significant changes were observed in the physiological and biochemical indexes of rats after radiation, accompanied by significant oxidative stress response. The mRNA and protein expression of Nrf2 peaked at 12 h after irradiation, and HO-1 expression peaked at 48 h after irradiation. RTP administration reduced radiation-induced intestinal damage, upregulated Nrf2/HO-1, improved physiological indexes, significantly decreased apoptosis and inflammatory factors, and upregulated HO-1, particularly at 48 h after irradiation. In conclusion, Nrf2 is activated in the early stage of radiation-induced intestinal injury and plays a protective role. RTP significantly ameliorates radiation-induced intestinal injury via the regulation of Nrf2 and its downstream protein HO-1.

The NF-κB-Regulated miR-221/222/Syndecan-1 Axis and Intestinal Mucosal Barrier Function in Radiation Enteritis

Effects of trapidil on intestinal mucosal barrier function and bacterial translocation after intestinal ischemia and reperfusion in an experimental rat model

In this work, we explored the role and mechanism of sea buckthorn oil in reducing radiation-induced skin damage. The radiation-induced rat skin injury model was established using strontium-90. Rats were treated with sea buckthorn oil twice a day postirradiation, and skin damage was observed at different times and evaluated using an injury score. Skin pathological changes were observed using hematoxylin and eosin (H&E) staining. Western blotting and immunohistochemistry were used to detect the expression of vascular growth and pathway proteins. ELISA was used to detect the secretion level of inflammatory factors. Immunohistochemistry was used to detect macrophage polarization marker proteins. We found that sea buckthorn oil can alleviate radiation-induced skin damage, accelerate skin vascular regeneration, and promote the up-regulation of vascular endothelial growth factor (VEGF) and its receptor (VEGFR). These results demonstrate the beneficial effects of sea buckthorn oil on radiation-induced skin damage. Furthermore, the levels of IL-1β and TNF-α in the sea buckthorn oil treatment group were significantly lower than those in the control group, while the levels of IL-4 and IL10 were significantly higher (P < 0.05). CD206 expression also increased in the sea buckthorn oil treatment group, while CD16 expression decreased compared to the control group (P < 0.05). Western blotting showed that PI3K, Akt and ERK expression increased in the sea buckthorn oil treatment group (P < 0.05). The beneficial effect of sea buckthorn oil in reducing the inflammatory response in irradiated rats was diminished when they were treated with PI3K inhibitor. We conclude that sea buckthorn oil may regulate macrophage M2 polarization by increasing the PI3K-Akt-ERK signaling pathway, thereby inhibiting the inflammatory response and promoting skin vascular regeneration to prevent and treat radiation-induced skin damage.

The Par complex (Par-6/Par-3/aPKC) plays a key role in the maintenance of the intestinal barrier function through the regulation of epithelial junction formation. The aryl hydrocarbon receptor (AhR) has been shown to be an important regulator for intestinal homeostasis. In this study, we investigated the role of the AhR activation on the regulation of Par complex. AhR activation by 6-formylindolo (3,2-b) carbazole (FICZ) represses the abnormal expression of the Par complex in a mouse model of dextran sulphate sodium (DSS)-induced colitis. In T84 cells, overexpression of Par-6 causes intestinal barrier dysfunction. Lipopolysaccharide (LPS)-induced intestinal epithelial barrier dysfunction and increase in Par-6 expression was prevented by AhR activation. However, FICZ did not alter the expression of Par-3 or aPKC. Furthermore, AhR activation alleviated LPS-induced increase of Par-6 through repressing the expression of activating protein-2γ (Ap-2γ). These results reveal the protective effects of AhR activation on LPS induced disruption of intestinal epithelial barrier function through suppressing the expression of Par-6 expression. Our findings provide novel insights into the protective role of AhR in intestinal barrier function.

Bacillus coagulans alleviates intestinal barrier injury induced by Klebsiella pneumoniae in rabbits by regulating the TLR4/MyD88/NF-κB signalling pathway.

Intestinal mucosal mechanical barrier is one of the most important structure to maintain the body homeostasis. The occurrences of inflammatory bowel disease, necrotizing enterocolitis and poor prognosis of patients with obstructive jaundice are closely related to the damage of the mucosal barrier function. Long-term high fat diet and obstructive jaundice can cause the abnormality of bile acids metabolism. These pathological conditions are often associated with the destruction of intestinal mucosal barrier function. So the correlations between abnormal bile metabolism and intestinal mucosal mechanical barrier function have aroused interests of many researchers. They found that bile acids the important component of bile are closely related to the intestinal barrier function. The paper reviewed the recent articles and summarized the mechanisms of the deficiency of bile acids, excessive bile acids and abnormal bile acids composition damaging the intestinal mucosal barrier function. It will provide refe-rence for the new fields of study, prevention of the toxic effects of bile acids and the improvement of the prognosis of patients. Key words: Inflammatory bowel disease; Bile acids; Intestinal barrier function; High-fat diet; Obstructive jaundice

ObjectivesIntestinal barrier dysfunction plays an important role in acute necrotizing pancreatitis (ANP) and intestinal microbiota dysbiosis was involved in intestinal barrier failure. Paneth cells protect intestinal barrier and are associated with intestinal microbiota. Here, we investigated changes in intestinal microbiota and antimicrobial peptides of Paneth cells in ileum during ANP.MethodsRats with ANP were established by retrograde injection of 3.5% sodium taurocholate into biliopancreatic duct and sacrificed at 24h and 48h, respectively. Injuries of pancreas and distal ileum were evaluated by histopathological score. Intestinal barrier function was assessed by plasma diamine oxidase activity (DAO) and D-lactate. Systemic and intestinal inflammation was evaluated by TNFα, IL-1β and IL-17A concentration by ELISA, respectively. 16S rRNA high throughput sequencing on fecal samples was used to investigate the changes in intestinal microbiota in the ANP group at 48h. Lysozyme and α-defensin5 were measured by real-time PCR, western blot and immunofluoresence.ResultsANP rats had more severe histopathological injuries in pancreas and distal ileum, injured intestinal barrier and increased expression of TNFα, IL-1β and IL-17A in plasma and distal ileum compared with those of the sham-operated (SO) group. Principal component analysis (PCA) showed structural segregation between the SO and ANP groups. Operational taxonomic unit (OTU) number and ACE index revealed decreased microbiota diversity in the ANP group. Taxonomic analysis showed dysbiosis of intestinal microbiota structure. At phyla level, Saccharibacteria and Tenericutes decreased significantly. At genus level, Escherichia-Shigella and Phascolarctobacterium increased significantly, while Candidatus_Saccharimonas, Prevotellaceae_UCG-001, Lachnospiraceae_UCG-001, Ruminiclostridium_5 and Ruminococcaceae_UCG-008 decreased significantly. Lysozyme and α-defensin5 mRNA expression levels decreased significantly in ANP group at 48h. Protein expression of lysozyme decreased in ANP groups at 24h and 48h. Meanwhile, the relative abundance of Escherichia-Shigella correlated inversely with the decrease in lysozyme.ConclusionThe disorder in intestinal microbiota and decreases of Paneth cell antimicrobial peptides might participate in the pathogenesis of intestinal barrier dysfunction during ANP.

IntroductionMelatonin (MEL) is a crucial neuroendocrine hormone primarily produced by the pineal gland. Pinealectomy (PINX) has been performed on an endogenous MEL deficiency model to investigate the functions of pineal MEL and its relationship with various diseases. However, the effect of PINX on the gastrointestinal tract (GIT) MEL levels and gut microbiome in pigs has not been previously reported.MethodsBy using a newly established pig PINX model, we detected the levels of MEL in the GIT by liquid chromatography–tandem mass spectrometry. In addition, we examined the effects of PINX on the expression of MEL synthesis enzymes, intestinal histomorphology, and the intestinal barrier. Furthermore, 16S rRNA sequencing was performed to analyze the colonic microbiome.ResultsPINX reduced serum MEL levels but did not affect GIT MEL levels. Conversely, MEL supplementation increased MEL levels in the GIT and intestinal contents. Neither PINX nor MEL supplementation had any effect on weight gain, organ coefficient, serum biochemical indexes, or MEL synthetase arylalkylamine N-acetyltransferase (AANAT) expression in the duodenum, ileum, and colon. Furthermore, no significant differences were observed in the intestinal morphology or intestinal mucosal barrier function due to the treatments. Additionally, 16S rRNA sequencing revealed that PINX had no significant impact on the composition of the intestinal microbiota. Nevertheless, MEL supplementation decreased the abundance of Fibrobacterota and increased the abundance of Actinobacteriota, Desulfobacterota, and Chloroflexi.ConclusionWe demonstrated that synthesis of MEL in the GIT is independent of the pineal gland. PINX had no influence on intestinal MEL level and microbiota composition in pigs, while exogenous MEL alters the structure of the gut microbiota.

\n \n Normal tissue toxicity still remains a dose-limiting factor in clinical radiation therapy. Intestinal radiation toxicity is characterized by mucosal injury, inflammation, vascular activation followed by development of progressive vascular fibrosis/sclerosis and radiation enteritis. The endothelium is known to play a critical role in radiation-induced intestinal injury. Previous studies showed that endothelial cell (EC) apoptosis plays a central role in early radiation-induced intestinal injury. Recently, we demonstrated that plasminogen activator inhibitor type 1 (PAI-1) is an essential mediator of late intestinal radiation toxicity. PAI-1 knockout mice (PAI-1 -/-) are protected against intestinal radiation-induced damage with increased survival and better intestinal function compared with wild type mice (Wt). However, it is not clear whether PAI-1 plays a role in acute radiation-induced intestinal damages. We hypothesized that PAI-1 could contribute to the radiosensitivity of the endothelium in acute phases of radiation enteropathy. \nIn vitro, irradiation stimulates PAI-1 expression (mRNA and protein) in EC 4 hours to 48 hours after irradiation. Moreover, FACS analyses (Sub-G1 and AnnexinV) and caspase assay showed that apoptosis is rapidly induced 4h to 24h after irradiation. These results suggest that PAI-1 could play a key role in radiation-induced EC cell death. To prove that PAI-1 is involved, molecular modulation of PAI-1 expression was performed using an expression vector and a RNA interference strategy. In EC overexpressing PAI-1 (pCMV PAI-1), radiation-induced apoptosis is increased 6h after 10Gy irradiation compared with EC transfected with a control vector. 48 hours after PAI-1 siRNA transfection, PAI-1 mRNA and protein levels are decreased by 85%. Sub-G1 and Annexin V flow cytometry analyses showed that radiation-induced apoptosis is decreased in siRNA-PAI-1 transfected EC. These preliminary results show that PAI-1 plays a role in the radiosensitivity of EC. To prove the relevance of our in vitro results, radiation-induced EC apoptosis in vivo was monitored in a model radiation enteropathy. After exposure of an intestinal segment to 19 Gy radiation, acute intestinal radiation injury are assessed in Wt and PAI-1 -/- mice 4 hours to 3 days after irradiation. Radiation injury score (RIS) is monitored and radiation-induced EC apoptosis is followed by double immunolabelling TUNEL or caspase-3 / CD31. RIS is reduced in PAI-1 -/- mice compared to Wt mice suggesting that acute EC apoptosis is reduced in PAI-1 -/- mice.\n This current and ongoing work should allow to determine the putative role of PAI-1 in radiation-induced endothelial cells apoptosis and consequently in intestinal radiation injury. \n\n \n