Radiation-induced Intestinal Injury Research Articles

Naringenin Alleviates Radiation-Induced Intestinal Injury by Inhibiting TRPV6 in Mice.

Naringenin (NAR) possesses unique anti-inflammatory, antiapoptosis effects and various bioactivities; however, its role against radiation-induced intestinal injury (RIII) remains unclear. This study aims to investigate whether NAR has protective effects against radiation-induced intestinal injury and the underlying mechanisms. C57BL/6J mice are exposed to a single dose of 13Gy X-ray total abdominal irradiation (TAI), then gavaged with NAR for 7 days. NAR treatment prolongs the survival rate, protects crypts and villi from damage, alleviates the level of radiation-induced inflammation, and mitigates intestinal barrier damage in the irradiated mice. Additionally, NAR reduces immune cell infiltration and intestinal epithelial cell apoptosis. NAR also shows radioprotective effects in human colon cancer cells (HCT116) and human intestinal epithelial cells (NCM460). It reduces cell damage by reducing intracellular calcium ion levels and reactive oxygen species (ROS) levels. NAR-mediated radioprotection is associated with the downregulation of transient receptor potential vanilloid 6 (TRPV6), and inhibition of apoptosis pathway. Notably, treatment with NAR fails to further increase the protective effects of the TRPV6 inhibitor 2-APB, indicating that TRPV6 inhibition is essential for NAR activity. NAR inhibits the apoptosis pathway by downregulating TRPV6 and reducing calcium ion level, thereby alleviating RIII. Therefore, NAR is a promising therapeutic drug for RIII.

Oral Curcumin-Thioketal-Inulin Conjugate Micelles against Radiation-Induced Enteritis.

Radiation-induced enteritis is an unavoidable complication associated with pelvic tumor radiotherapy, significantly influencing the prognosis of cancer patients. The limited availability of commercial gastrointestinal radioprotectors in clinical settings poses a substantial challenge in preventing radiation enteritis. Despite the inherent radioprotective characteristics of Cur in vitro, its poor solubility in water, instability, and low bioavailability lead to inferior therapeutic effects in vivo. Herein, we developed novel ROS-responsive micelles (CTI) from inulin and curcumin, aimed at mitigating radiation enteritis. CTI micelles had excellent solubility and stability. Importantly, CTI improved the cytotoxicity and bioavailability of curcumin, thereby showing enhanced effectiveness in neutralizing ROS induced by radiation, safeguarding against DNA damage, and reducing radiation-induced cellular mortality. Moreover, in a radiation enteritis mice model, CTI not only alleviated severe radiation-induced intestinal injury but also improved redox-related indicators and reduced inflammatory cytokine expression. Furthermore, CTI effectively increased gut microbiota abundance and maintained gut homeostasis. In conclusion, CTI could be a promising candidate for the clinical management of radiation enteritis. Our study provides a new perspective for radioprotection using natural antioxidants.

Fraxin (7-hydroxy-6-methoxycoumarin 8-glucoside) confers protection against ionizing radiation-induced intestinal epithelial injury in vitro and in vivo

The small intestine exhibits remarkable sensitivity to ionizing radiation (IR), which significantly hampers the effectiveness of radiotherapy in the treatment of abdominal and pelvic tumors. Unfortunately, no effective medications are available to treat radiation-induced intestinal damage (RIID). Fraxin (7-hydroxy-6-methoxycoumarin 8-glucoside), is a coumarin derivative extracted from the Chinese herb Cortex Fraxini. Several studies have underscored the anti-inflammatory, antibacterial, antioxidant, and immunomodulatory properties of fraxin. However, the efficacy of fraxin at preventing or mitigating RIID remains unclear. Thus, the present study aimed to investigate the protective effects of fraxin against RIID in vitro and in vivo and to elucidate the underlying mechanisms. The study findings revealed that fraxin markedly ameliorated intestinal injuries induced by 13 Gy whole abdominal irradiation (WAI), which was accompanied by a significant increase in the population of Lgr5+ intestinal stem cells (ISCs) and Ki67+ progeny. Furthermore, fraxin mitigated WAI-induced intestinal barrier damage, and reduced oxidative stress and intestinal inflammation in mice. Transcriptome sequencing of fraxin-treated mice revealed upregulation of IL-22, a pleiotropic cytokine involved in regulating the function of intestinal epithelial cells. Moreover, in both human intestinal epithelial cells and ex vivo cultured mouse intestinal organoids, fraxin effectively ameliorated IR-induced damage by promoting the expression of IL-22. The radioprotective effects of fraxin were partially negated in the presence of an IL-22-neutralizing antibody. In summary, fraxin is demonstrated to possess the ability to alleviate RIID and maintain intestinal homeostasis, suggesting that fraxin might serve as a strategy for mitigating accidental radiation exposure- or radiotherapy-induced RIID.

Extracellular miRNAs in the serum and feces of mice exposed to high‑dose radiation.

Exposure to high-dose radiation causes life-threatening intestinal damage. Histopathology is the most accurate method of judging the extent of intestinal damage following death. However, it is difficult to predict the extent of intestinal damage. The present study investigated extracellular microRNAs (miRNAs or miRs) in serum and feces using a radiation-induced intestinal injury mouse model. A peak of 25-200 nucleotide small RNAs was detected in mouse serum and feces by bioanalyzer, indicating the presence of miRNAs. Microarray analysis detected four miRNAs expressed in the small intestine and increased by >2-fold in serum and 19 in feces following 10 Gy radiation exposure. Increased miR-375-3p in both serum and feces suggests leakage due to radiation-induced intestinal injury and may be a candidate for high-dose radiation biomarkers.

MitoQ and its hyaluronic acid-based nanopreparation mitigating gamma radiation-induced intestinal injury in mice: alleviation of oxidative stress and apoptosis.

Perturbations produced by ionizing radiation on intestinal tissue are considered one of highly drastic challenges in radiotherapy. Animals were randomized into five groups. The first group was allocated as control, and the second was subjected to whole body γ-irradiation (10 Gy). The third was administered HA NP (17.6 mg/kg/day; i.p.) and then irradiated. The fourth one received MitoQ (2 mg/kg/day; i.p.) and then irradiated. The last group received MitoQ/HA NP (2 mg/kg/day; i.p.) for 5 days prior to irradiation. Mice were sacrificed a week post-γ-irradiation for evaluation. MitoQ/HA NP ameliorated mitochondrial oxidative stress as indicated by rising (TAC) and glutathione peroxidase and decreasing malondialdehyde, showing its distinguished antioxidant yield. That impacted the attenuation of apoptosis, which was revealed by the restoration of the anti-apoptotic marker and lessening proapoptotic caspase-3. Inflammatory parameters dwindled via treatment with MitoQ/HA NP. Moreover, this new NP exerts its therapeutic action through a distinguished radioprotective pathway (Hmgb1/TLR-4.) Subsequently, these antioxidants and their nanoparticles conferred protection to intestinal tissue as manifested by histopathological examination. These findings would be associated with its eminent antioxidant potential through high mitochondria targeting, enhanced cellular uptake, and ROS scavenging. This research underlines MitoQ/HA NP as a new treatment for the modulation of intestinal damage caused by radiotherapy modalities.

Nocardia rubra cell-wall skeleton mitigates whole abdominal irradiation-induced intestinal injury via regulating macrophage function.

Ionizing radiation (IR)-induced intestinal injury is a major side effect and dose-limiting toxicity in patients receiving radiotherapy. There is an urgent need to identify an effective and safe radioprotectant to reduce radiation-induced intestinal injury. Immunoregulation is considered an effective strategy against IR-induced injury. The purpose of this article was to investigate the protective effect of Nocardia rubra cell wall skeleton (Nr-CWS), an immunomodulator, on radiation-induced intestinal damage and to explore its potential mechanism. C57BL/6J male mice exposed to 12Gy whole abdominal irradiation (WAI) were examined for survival rate, morphology and function of the intestine and spleen, as well as the gut microbiota, to comprehensively evaluate the therapeutic effects of Nr-CWS on radiation-induced intestinal and splenetic injury. To further elucidate the underlying mechanisms of Nr-CWS-mediated intestinal protection, macrophages were depleted by clodronate liposomes to determine whether Nr-CWS-induced radioprotection is macrophage dependent, and the function of peritoneal macrophages stimulated by Nr-CWS was detected in vitro. Our data showed that Nr-CWS promoted the recovery of intestinal barrier function, enhanced leucine-rich repeat-containing G protein-coupled receptor 5+ intestinal stem cell survival and the regeneration of intestinal epithelial cells, maintained intestinal flora homeostasis, protected spleen morphology and function, and improved the outcome of mice exposed to 12Gy WAI. Mechanistic studies indicated that Nr-CWS recruited macrophages to reduce WAI-induced intestinal damage. Moreover, macrophage depletion by clodronate liposomes blocked Nr-CWS-induced radioprotection. In vitro, we found that Nr-CWS activated the nuclear factor kappa-B signaling pathway and promoted the phagocytosis and migration ability of peritoneal macrophages. Our study suggests the therapeutic effect of Nr-CWS on radiation-induced intestinal injury, and provides possible therapeutic strategy and potential preventive and therapeutic drugs to alleviate it.

Enteric α-Defensin Contributes to Recovery of Radiation-Induced Intestinal Injury by Modulating Gut Microbiota and Fecal Metabolites.

The effect of ionizing radiation on the gastrointestinal tract is a common complication of abdominal and pelvic radiotherapy. However, the pathological features of radiation enteropathy and its effective medical intervention regimen is still a global challenge. Here, we explored the role and mechanism of enteric alpha-defensins (EαDs) in protecting against radiation enteropathy. To address this, we utilized EαDs-deficiency mice, in which the matrix metallopeptidase 7 to activate Paneth cell α-defensins was knockout (KO) mice, and the complementary wild-type (WT) control mice for this study. Remarkably, the KO mice were more susceptible to 5.0 Gy total-body irradiation, resulting in worse clinic scores and lower survival rate, compared with the wild-type mice. Histological examination indicated that the KO mice were subjected to slow recovery of intestinal villus and mucosa function, characterized by the reduced expression of TFF3, Glut1 and Muc2. In addition, compared with the wild-type controls, the KO mice experienced serious inflammation response in intestinal tissue, indicated by the remarkably increased expression level of IL-1β, IL-6 and IL-12. Using high-throughput sequencing analysis, we found that the intestinal bacterial community of the KO mice was more prone to dysbiosis than that of the WT mice, with significantly increased abundance of opportunistic pathogenic bacteria, such as Streptococcus sp. and Escherichia-Shigella sp., whereas remarkably decreased probiotics harboring Lactobacillus sp., Desulfovibrio sp. etc. Fecal metabolomics analysis indicated that the relative abundance of 31 metabolites arose significantly different between WT and KO mice on day 10 after radiation exposure. A subset of differential metabolites to regulate host metabolism and immunity, such as acetic acid, acetate, butanoic acid, was negatively correlated with the alteration of gut microbiota in the irradiated KO mice. This study provides new insight into EαDs contribution to the recovery of radiation-induced intestinal damage, and suggests a potential novel target to prevent the adverse effects of radiotherapy.

Radiation-Induced Intestinal Injury: Injury Mechanism and Potential Treatment Strategies.

Radiation-induced intestinal injury (RIII) is one of the most common intestinal complications caused by radiotherapy for pelvic and abdominal tumors and it seriously affects the quality of life of patients. However, the treatment of acute RIII is essentially symptomatic and nutritional support treatment and an ideal means of prevention and treatment is lacking. Researchers have conducted studies at the cellular and animal levels and found that some chemical or biological agents have good therapeutic effects on RIII and may be used as potential candidates for clinical treatment. This article reviews the injury mechanism and potential treatment strategies based on cellular and animal experiments to provide new ideas for the diagnosis and treatment of RIII in clinical settings.

Single-cell map of dynamic cellular microenvironment of radiation-induced intestinal injury

Intestine is a highly radiation-sensitive organ that could be injured during the radiotherapy for pelvic, abdominal, and retroperitoneal tumors. However, the dynamic change of the intestinal microenvironment related to radiation-induced intestine injury (RIII) is still unclear. Using single-cell RNA sequencing, we pictured a dynamic landscape of the intestinal microenvironment during RIII and regeneration. We showed that the various cell types of intestine exhibited heterogeneous radiosensitivities. We revealed the distinct dynamic patterns of three subtypes of intestinal stem cells (ISCs), and the cellular trajectory analysis suggested a complex interconversion pattern among them. For the immune cells, we found that Ly6c+ monocytes can give rise to both pro-inflammatory macrophages and resident macrophages after RIII. Through cellular communication analysis, we identified a positive feedback loop between the macrophages and endothelial cells, which could amplify the inflammatory response induced by radiation. Besides, we identified different T cell subtypes and revealed their role in immunomodulation during the early stage of RIII through inflammation and defense response relevant signaling pathways. Overall, our study provides a valuable single-cell map of the multicellular dynamics during RIII and regeneration, which may facilitate the understanding of the mechanism of RIII.

Von Willebrand factor promotes radiation-induced intestinal injury (RIII) development and its cleavage enzyme rhADAMTS13 protects against RIII by reducing inflammation and oxidative stress

Patients with abdominopelvic cancer undergoing radiotherapy commonly develop radiation-induced intestinal injury (RIII); however, its underlying pathogenesis remains elusive. The von Willebrand factor (vWF)/a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) axis has been implicated in thrombosis, inflammation, and oxidative stress. However, its role in RIII remains unclear. In this study, the effect of radiation on vWF and ADAMTS13 expression was firstly evaluated in patients with cervical cancer undergoing radiotherapy and C57BL/6J mice exposed to different doses of total abdominal irradiation. Then, mice with the specific deletion of vWF in the platelets and endothelium were established to demonstrate the contribution of vWF to RIII. Additionally, the radioprotective effect of recombinant human (rh) ADAMTS13 against RIII was assessed. Results showed that both the patients with cervical cancer undergoing radiotherapy and RIII mouse model exhibited increased vWF levels and decreased ADAMTS13 levels. The knockout of platelet- and endothelium-derived vWF rectified the vWF/ADAMTS13 axis imbalance; improved intestinal structural damage; increased crypt epithelial cell proliferation; and reduced radiation-induced apoptosis, inflammation, and oxidative stress, thereby alleviating RIII. Administration of rhADAMTS13 could equally alleviate RIII. Our results demonstrated that abdominal irradiation affected the balance of the vWF/ADAMTS13 axis. vWF exerted a deleterious role and ADAMTS13 exhibited a protective role in RIII progression. rhADAMTS13 has the potential to be developed into a radioprotective agent.

[Management of radiation-induced intestinal injury:from multi-disciplinary team team to holistic integrative management].

Radiation-induced intestinal injury is a radiation injury of the colon and rectum after radiotherapy for pelvic malignant tumors. This condition affects multiple organs in the pelvis, making treatment challenging. In clinical practice, the most effective protocol is often determined through discussion by a multi-disciplinary team (MDT). However, due to the severity and complexity of radiation enteritis, many patients still experience poor diagnosis and treatment outcomes. Holistic integrative management (HIM) is a rapidly developing concept that has greatly enhanced clinical medicine in recent years. It improves the level of diagnosis, treatment, prevention, and rehabilitation from multiple dimensions of prevention, screening, diagnosis, treatment, and rehabilitation. In the context of radiation-induced intestinal injury, HIM also calls for the implementation of an individualized management system that focuses on the patient as a whole within the healthcare team. From the perspective of HIM, this article introduces some of the latest progress of radiation-induced intestinal injury in recent years.

[Imaging diagnosis and evaluation of radiation-induced intestinal injury].

Radiation-induced intestinal injury significantly impacts the quality of life and even prognosis of patients. Timely diagnosis and accurate assessment are crucial in clinical practice. Imaging examinations play a vital role in the diagnosis and evaluation of radiation-induced intestinal injury. CT offers fast scanning speed and wide coverage but has limited soft tissue resolution. On the other hand, MRI offers superior soft tissue resolution, along with the capability for multi-sequence and multi-parameter imaging, and the ability to assess the effect of tumor treatment. However, its scanning range is restricted. Endorectal ultrasound enables observation of rectal wall thickness, submucosal blood flow signals, and the development of micro-ulcers and fistulas. The key imaging features of radiation-induced intestinal injury include intestinal wall thickening, layered enhancement on contrast-enhanced scans, fistula formation, and abscess formation, and so on. Previous studies have established correlations between certain imaging features and the severity as well as prognosis of the disease. Nonetheless, these imaging features lack specificity, and require differentiation from tumors, ischemic changes, and other intestinal inflammatory lesions, considering the patient's radiotherapy history in conjunction with the imaging findings.

Gut Microbiota-Derived D-Tagatose from EGCG Attenuates Radiation-Induced Intestinal Injury

As a rapidly self-renewing tissue, the small intestine is particularly sensitive to ionizing radiation, which limits the outcomes of radiotherapy against abdominal malignancies, resulting in poor prognosis. The polyphenol (-)-epigallocatechin-3-gallate (EGCG), a major bioactive constituent of green tea, is beneficial in radiation-induced intestinal injury (RIII) alleviation. However, the bioavailability of EGCG in vivo is very low, with only 0.1% to 1.6% being absorbed into the intestine of mice. It is unclear whether gut microbial metabolites mediated by EGCG exert an effect to protect against radiation-induced intestinal injury. Male C57BL/6J mice were subjected to 13 Gy abdominal irradiation after EGCG gavage, and the severity of intestinal tissue damage was evaluated by HE staining, immunohistochemistry, and TUNEL assays. Fresh fecal samples were collected after the end of gavage, and then fecal sterile fecal filtrate (SFF) was obtained. Stool samples were collected 3 d after irradiation. The gut microbiome was detected by 16S rRNA sequencing, the metabolites were detected by GC‒MS analysis, and then the metabolites were applied to male C57BL/6J mice, observing and evaluating the severity of RIII. We first explored the effect of oral EGCG delivery on radiation-induced intestinal injury. Our results revealed that EGCG pre-supplementation prolongs survival time, prevents weight loss in mice and mitigates radiation-induced intestinal injury in irradiated mice. Using 16S rRNA gene-based microbiota analysis, we first found that EGCG ameliorated ionizing radiation-induced gut microbiota dysbiosis and enriched short-chain fatty acid (SCFA)-producing bacteria such as Roseburia, Ruminococcus, and Clostridia_UCG-014. In addition, metabolomic profiling analysis showed that the gut microbiota modulated EGCG-induced metabolic reprogramming in colonic tissues, particularly by enhancing galactose metabolism. Notably, EGCG supplementation resulted in the enrichment of the microbiota-derived galactose metabolism metabolite D-tagatose. Furthermore, exogenous treatment with D-tagatose reproduced similar protective effects as EGCG to protect against radiation-induced intestinal injury (RIII). D-tagatose restored the length of villi and improved the number of goblet cells, Ki-67-positive cells and Lgr5+ ISCs, while the number of TUNEL-positive cells in the intestinal tissues decreased significantly. To validate these discoveries, we performed fecal sterile fecal filtrate (SFF) from EGCG-dosed mice to untreated mice before ionizing radiation. SFF from EGCG-dosed mice alleviated the RIII over SFF from control mice superiorly. This study provides the first data indicating that oral EGCG ameliorated radiation-induced intestinal injury (RIII) by regulating the gut microbiota and metabolites. Our findings provide novel insights into D-tagatose derived by gut microbiota from EGCG-mediated remission of RIII.

Green Tea Derivative (–)-Epigallocatechin-3-Gallate (EGCG) for Prevention of Acute Radiation-Induced Intestinal Injury: A Prospective Phase II Clinical Study in Pelvic Cancer Patients

Radiation-induced intestinal injury (RIII) remains the most common dose-limiting toxicity following radiotherapy (RT) for pelvic malignancies. However, few efficient and safe methods for the prevention of RIII are available in the clinical practice. Our previous study proved that the green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) efficiently attenuates radiation-induced intestinal injury (RIII) in animal level. Therefore, this prospective phase II clinical study (ChiCTR2100053703) evaluated the efficacy of EGCG in the prevention of RIII. Cervical or endometrial cancer patients who received adjuvant or radical RT in our department were enrolled, 400mg EGCG was taken daily, and RIII was evaluated weekly according to the RTOG criteria. Between February 2022 to January 2023, 37 patients were enrolled (30 were cervical cancer and the other 7 were endometrial cancer), and were followed-up regularly. Among them, the majority patients (75.7%, 28 patients) developed grade 0 or 1 RIII, for which no medical intervention was required. Meanwhile, the occurrence of grade 2 RIII was 24.3% (9 patients), which was significantly lower than that in the historical controls (usually 60% to 80%). Besides that, no patients developed grade 3 or worse RIII. In this phase II clinical trial, compared to historical controls, the prophylactic use of EGCG significantly reduced the incidence and severity of RIII in patients receiving pelvic RT. Therefore, EGCG has the potential to become a novel medical countermeasure for the prevention of RIII for pelvic cancer patients.

Probiotic Consortia and their Metabolites Protect Intestine Against Radiation Injury by Improving Intestinal Epithelial Homeostasis

The intestine is a highly radiosensitive tissue that is susceptible to structural and functional damage due to systemic as well as localized radiation exposure. Unfortunately, no therapeutic agents are available at present to manage radiation-induced intestinal injuries (RIII). Probiotics, especially Lactobacillus or Bifidobacterium, are orally taken as food supplements or microbial drugs by patients with gastrointestinal disorders due to their safety, efficacy, and power to restore the gut microenvironment. Our results demonstrate that probiotic consortia and their metabolites could exert protective roles in the RIII mouse model by restoring the structure of the gut microbiota and regulating redox imbalance. Moreover, the effect of probiotic consortia is better than that of any single probiotic strain. Male C57BL/6J mice were treated with 13 Gy of whole abdominal irradiation (WAI). Probiotics were administered by gavage before (once a day for 30 days) WAI. The survival and body weight were recorded, while the severity of RIII was evaluated by HE staining, immunohistochemistry (IHC) and TUNEL assay of gut tissues. Meanwhile, stool samples were obtained 3.5 d after irradiation. Gut microbiome were measured by 16S rRNA sequencing, and metabolites were detected by LC-MS analysis. For sterile fecal filtrate (SFF), the supernatants were collected and passed through 70 and 0.2μm filters. Compared to the control, probiotic consortia (Lactobacillus plantarum, Bifidobacterium longum, Lactobacillus paracasei) treatment significantly increased survival rates by 50% (P<0.05) and improved clinical scores of mice after WAI. HE staining showed that probiotics mitigated RIII, as reflected by the dramatic attenuation of crypt-villus architecture destruction. IHC results showed that probiotic consortia treatment markedly increased the Lgr5+ cells, Paneth cells, and Ki67+ cells (P<0.001) per crypt, indicating that probiotics promoted the proliferation and differentiation of ISCs after WAI. Consistent with the H&E staining, the level of CD4/CD8 was increased by the probiotic consortia compared with that of the control group. The probiotic consortia modulated the structure of the gut microbiota and metabolites in the RIII mouse model. To further investigate the impact of metabolites on RIII, crude probiotic fermentation metabolites were administered to the RIII mouse model. Specifically, mice fed the mixed-metabolite daily for 7 days before IR had significantly more Lgr5+ and Ki67+cells in the SI crypt than mice of control. Moreover, treatment with mixed metabolites resulted in insignificant changes in SOD, MDA, GSH and T-AOC activity compared to the control group in intestinal tissues. In the present study, we demonstrate that probiotic consortia and their metabolites treatment attenuate RIII by modulating the structure and composition of the gut microbiota and regulating redox imbalance.

7-Hydroxy-6-Methoxycoumarin 8-Glucoside (Fraxin) Confers Protection against Ionizing Radiation-Induced Intestinal Epithelial Cell Death Both In Vitro and In Vivo

The small intestine is highly sensitive to ionizing radiation. Radiation-induced intestinal injury (RIII) limits the therapeutic effect of tumor radiotherapy. However, there are currently few effective treatments available for the prevention or mitigation of RIII. Fraxin, structurally a derivative of a coumarin glucoside extracted from the herbal Cortex Qinpi, has the advantages of low toxicity and relatively low cost. Some studies have proven that Fraxin has anti-inflammatory and antibacterial effects. Our results show that Fraxin can not only promote the regeneration of intestinal stem cells and repair the intestinal structure caused by irradiation but also regulate the composition of gut microbiota and then play an immunomodulatory role through IL-22 signaling pathways, resulting in radioprotective effects. Human intestinal epithelial cells (HIECs) and intestinal organs were used as experimental models in vitro. The experimental group was irradiated with 6 Gy, detected by a cell counting kit, cell cloning, apoptosis, γ-H2AX and 8-OHdG IF. Male C57BL/6 mice aged 6-8 weeks were given a single dose of whole abdominal irradiation (WAI) at 13 Gy, detected by HE staining, IHC, IF and TUNEL methods, and survival and body weight changes were recorded, fecal samples and small intestinal tissue samples were collected 6 hours and 3 days after irradiation, and the gut microbiota was detected by 16S rRNA sequencing. Whole small intestinal tissue was analyzed by genomic transcript spectrum and RNA sequencing. Compared with vehicle treatment, Fraxin administration significantly improved the quality of life after WAI and maintained the body weight of mice. In addition, the crypt-villus architecture of the intestinal tracts in mice treated with Fraxin was well preserved, and the number of goblet cells, Lgr5+ intestinal stem cells (ISCs) and their daughter cells, Ki67+ proliferating cells increased significantly, reducing the structural damage caused by radiation. Meanwhile, Fraxin improved the expression of tight junction proteins such as E-cadherin and Claudin-3 after WAI, strikingly reduced the levels of FITC-dextran in serum, maintained the integrity of the intestinal barrier. In addition, we have confirmed that Fraxin can increase the cell viability of HIECs, reduce the 8OHdG fluorescence intensity induced by IR, and reduce γ H2AX lesions and apoptosis. Fraxin administration recovered the disorder of the structure of gut microbiota after irradiation and promoted the expression of probiotics, and KEGG pathway analysis suggested that it was related to immunity. Transcriptional sequencing showed that the IL-22 signaling pathway was significantly activated in the Fraxin treatment group, suggesting that Fraxin may have a protective effect on intestinal radiation through IL-22. In conclusion, Fraxin treatment attenuate RIII by modulating the composition of the gut microbiota and activate the IL-22 signaling pathway to reduce RIII.

Therapeutic mechanism of Liangxue-Guyuan-Yishen decoction on intestinal stem cells and tight junction proteins in gastrointestinal acute radiation syndrome rats.

On the basis of the previous research, the Traditional Chinese Medicine theory was used to improve the drug composition for gastrointestinal acute radiation syndrome (GI-ARS). The purpose of this study was to study the therapeutic mechanism of Liangxue-Guyuan-Yishen decoction (LGYD) on GI-ARS and to provide a new scheme for the treatment of radiation injury. Here, we investigated the effects of LGYD on intestinal stem cells (ISCs) in a GI-ARS rat model. Rat health and survival and the protective efficacy of LGYD on the intestines were analyzed. The active principles in LGYD were detected using liquid chromatography-mass spectrometry (LC-MS). ISC proliferation, intestinal epithelial tight junction (TJ) protein expression and regulatory pathways were explored using immunohistochemistry, western blotting (WB) and reverse transcription quantitative polymerase chain reaction (RT-qPCR), respectively. Involvement of the WNT and MEK/ERK pathways in intestinal recovery was screened using network pharmacology analysis and validated by WB and RT-qPCR. LGYD administration significantly improved health and survival in GI-ARS rats. Pathological analysis showed that LGYD ameliorated radiation-induced intestinal injury and significantly promoted LGR5+ stem cell regeneration in the intestinal crypts, upregulated TJ protein, and accelerated crypt reconstruction in the irradiated rats. LC-MS revealed ≥13 constituents that might contribute to LGYD's protective effects. Collectively, LGYD can promote crypt cell proliferation and ISCs after radiation damage, the above effect may be related to WNT and MEK/ERK pathway.

Perillaldehyde Mitigates Ionizing Radiation-Induced Intestinal Injury by Inhibiting Ferroptosis via the Nrf2 Signaling Pathway.

Gastrointestinal toxicity is one of the major side effects of abdominopelvic tumor radiotherapy. Studies have shown that perillaldehyde (PAH) has antioxidant, antiinflammatory, antimicrobial activity, and antitumor effects. This study aims to determine whether PAH has radioprotective effects on radiation-induced intestinal injury and explore the underlying mechanisms. C57BL/6J mice are gavaged with PAH for 7 days, then exposed to a single dose of 13 Gy X-ray total abdominal irradiation (TAI). PAH treatment prolongs the survival time, promotes the survival of crypt cells, attenuates radiation-induced DNA damage, and mitigates intestinal barrier damage in the irradiated mice. PAH also shows radioprotective effects in intestinal crypt organoids and human intestinal epithelial cells (HIEC-6). PAH-mediated radioprotection is associated with the upregulation of nuclear factor erythroid-2 related factor 2 (Nrf2), activation of the antioxidant pathway, and inhibition of ferroptosis. Notably, treatment with the Nrf2 inhibitor ML385 abolishes the protective effects of PAH, indicating that Nrf2 activation is essential for PAH activity. PAH inhibits ionizing radiation (IR)-induced ferroptosis and attenuates intestinal injury after irradiation by activating Nrf2 signaling. Therefore, PAH is a promising therapeutic strategy for IR-induced intestinal injury.

Ferroptosis triggered by STAT1- IRF1-ACSL4 pathway was involved in radiation-induced intestinal injury

Radiation-induced intestinal injury (RIII), a common gastrointestinal complication caused by radiotherapy on pelvic, abdominal and retroperitoneal tumors, seriously affects the life quality of patients and may result in termination of radiotherapy. At present, the pathogenesis of RIII has not been fully understood. Herein, we demonstrated that ferroptosis played a critical role in RIII occurrence. The RNA sequencing analysis strongly hinted ferroptosis was involved in RIII mice. In line with this, the levels of 4-hydroxynonenal (4-HNE) and malondialdehyde (MDA), markers of lipid peroxidation, remarkably increased in RIII mice. And the ferroptosis inhibitor, Ferrostatin-1 (Fer-1), improved the mice survival and alleviated intestinal fibrosis in vivo. Moreover, our results revealed that arachidonic acid (AA) enhanced ferroptosis in cultured intestinal epithelial cells (IECs) and organoids in vitro after irradiation, and AA gavage aggravated RIII in mice. Mechanistic studies revealed the level of ACSL4 protein significantly increased in mouse jejunums and IECs after irradiation. Radiation-induced ferroptosis in IECs was also prevented following ACSL4 knockdown or with the function inhibitor of ACSL4. Furthermore, we found that transcription of ACSL4 induced by irradiation was regulated by STAT1/IRF1 axis, and AMPK activation triggered by AA negatively regulated radiation-induced ferroptosis. Taken together, our results suggest that ferroptosis mediates RIII and reducing dietary AA intake as well as targeting the STAT1-IRF1-ACSL4 axis or AMPK may be the potential approaches to alleviate RIII.

Paneth cell dysfunction in radiation injury and radio-mitigation by human α-defensin 5.

The mechanism underlying radiation-induced gut microbiota dysbiosis is undefined. This study examined the effect of radiation on the intestinal Paneth cell α-defensin expression and its impact on microbiota composition and mucosal tissue injury and evaluated the radio-mitigative effect of human α-defensin 5 (HD5). Adult mice were subjected to total body irradiation, and Paneth cell α-defensin expression was evaluated by measuring α-defensin mRNA by RT-PCR and α-defensin peptide levels by mass spectrometry. Vascular-to-luminal flux of FITC-inulin was measured to evaluate intestinal mucosal permeability and endotoxemia by measuring plasma lipopolysaccharide. HD5 was administered in a liquid diet 24 hours before or after irradiation. Gut microbiota was analyzed by 16S rRNA sequencing. Intestinal epithelial junctions were analyzed by immunofluorescence confocal microscopy and mucosal inflammatory response by cytokine expression. Systemic inflammation was evaluated by measuring plasma cytokine levels. Ionizing radiation reduced the Paneth cell α-defensin expression and depleted α-defensin peptides in the intestinal lumen. α-Defensin down-regulation was associated with the time-dependent alteration of gut microbiota composition, increased gut permeability, and endotoxemia. Administration of human α-defensin 5 (HD5) in the diet 24 hours before irradiation (prophylactic) significantly blocked radiation-induced gut microbiota dysbiosis, disruption of intestinal epithelial tight junction and adherens junction, mucosal barrier dysfunction, and mucosal inflammatory response. HD5, administered 24 hours after irradiation (treatment), reversed radiation-induced microbiota dysbiosis, tight junction and adherens junction disruption, and barrier dysfunction. Furthermore, HD5 treatment also prevents and reverses radiation-induced endotoxemia and systemic inflammation. These data demonstrate that radiation induces Paneth cell dysfunction in the intestine, and HD5 feeding prevents and mitigates radiation-induced intestinal mucosal injury, endotoxemia, and systemic inflammation.