Pharmaceutical drugs supporting regeneration of small-intestinal mucosa severely damaged by ionizing radiation in mice

NVP-AUY922 relieves radiation-induced intestinal injury via regulating EPHX1

As a common side effect of radiotherapy, radiation-induced intestinal injury (RIII) greatly affects the prognosis of patients and the efficacy of radiotherapy. Current therapeutic strategies for RIII are still very limited. Thus, the identification of effective radioprotective agents is of great importance. NVP-AUY922 is an HSP90 inhibitor with favorable anti-inflammatory and antioxidant activities. It has been proven to mitigate radiation-induced lung injury. However, its effects on the alleviation of RIII remain unclear. In this study, our data indicated that NVP-AUY922 remarkably increased the survival rate after radiation exposure. NVP-AUY922 treatment could enhance the viability of intestinal stem cells (ISCs) and promote the recovery of the small intestine. In addition, it also inhibited intestinal inflammation and reshaped the gut microbiota structure. We found that the radioprotective effect of NVP-AUY922 is partially dependent on EPHX1. In addition, NVP-AUY922 could attenuate dextran sulfate sodium (DSS)-induced colitis and promote intestinal barrier recovery. Thus, our results suggest that NVP-AUY922 contributes to the amelioration of intestinal injury after radiation exposure, which offers a new approach for the prevention of RIII.

Swertiamarin relieves radiation-induced intestinal injury by limiting DNA damage

Radiotherapy is the conventional treatment for pelvic abdominal tumors. However, it can cause some damage to the small intestine and colorectal, which are very sensitive to radiation. Radiation-induced intestinal injury (RIII) affects the prognosis of radiotherapy, causing sequelae of loss of function and long-term damage to patients' quality of life. Swertiamarin is a glycoside that has been reported to prevent a variety of diseases including but not limited to diabetes, hypertension, atherosclerosis, arthritis, malaria, and abdominal ulcers. However, its therapeutic effect and mechanism of action on RIII have not been established. We investigated whether swertiamarin has a protective effect against RIII. In this article, we use irradiator to create cellular and mouse models of radiation damage. Preventive administration of swertiamarin could reduce ROS and superoxide anion levels to mitigate the cellular damage caused by radiation. Swertiamarin also attenuated RIII in mice, as evidenced by longer survival, less weight loss and more complete intestinal barrier. We also found an increase in the relative abundance of primary bile acids in irradiated mice, which was reduced by both FXR agonists and swertiamarin, and a reduction in downstream interferon and inflammatory factors via the cGAS-STING pathway to reduce radiation-induced damage.

A Novel Organoid Model of Damage and Repair Identifies HNF4α as a Critical Regulator of Intestinal Epithelial Regeneration

BACKGROUND & AIMS

Recent evidence has suggested that the intact intestinal epithelial barrier protects our body from a range of immune-mediated diseases. The epithelial layer has an impressive ability to reconstitute and repair upon damage and this process of repair increasingly is seen as a therapeutic target. In vitro models to study this process in primary intestinal cells are lacking.

METHODS

We established and characterized an in vitro model of intestinal damage and repair by applying γ-radiation on small-intestinal organoids. We then used this model to identify novel regulators of intestinal regeneration.

RESULTS

We identified hepatocyte nuclear factor 4α (HNF4α) as a pivotal upstream regulator of the intestinal regenerative response. Organoids lacking Hnf4a were not able to propagate in vitro. Importantly, intestinal Hnf4a knock-out mice showed impaired regeneration after whole-body irradiation, confirming intestinal organoids as a valuable alternative to in vivo studies.

CONCLUSIONS

In conclusion, we established and validated an in vitro damage-repair model and identified HNF4α as a crucial regulator of intestinal regeneration. Transcript profiling: GSE141515 and GSE141518.

1,4-Dithiothreitol treatment ameliorates hematopoietic and intestinal injury in irradiated mice: Potential application of a treatment for acute radiation syndrome

Radiation exposure poses a significant threat to public health, which can lead to acute hematopoietic system and intestinal system injuries due to their higher radiation sensitivity. Hence, antioxidants and thiol-reducing agents could have a potential protective effect against this complication. The dithiol compound 1,4-dithiothreitol (DTT) has been used in biochemistry, peptide/protein chemistry and clinical medicine. However, the effect of DTT on ionizing radiation (IR)-induced hematopoietic injury and intestinal injury are unknown. The current investigation was designed to evaluate the effect of DTT as a safe and clinically applicable thiol-radioprotector in irradiated mice. DTT treatment improved the survival of irradiated mice and ameliorated whole body irradiation (WBI)-induced hematopoietic injury by attenuating myelosuppression and myeloid skewing, increasing self-renewal and differentiation of hematopoietic progenitor cells/hematopoietic stem cells (HPCs/HSCs). In addition, DTT treatment protected mice from abdominal irradiation (ABI)-induced changes in crypt-villus structures and function. Furthermore, treatment with DTT significantly enhanced the ABI-induced reduction in Olfm4 positive cells and offspring cells of Lgr5⁺ stem cells, including lysozyme⁺ Paneth cells and Ki67⁺ cells. Moreover, IR-induced DNA strand break damage, and the expression of proapoptotic-p53, Bax, Bak protein and antiapoptotic-Bcl-2 protein were reversed in DTT treated mice, and DTT also promoted small intestine repair after radiation exposure via the p53 intrinsic apoptotic pathway. In general, these results demonstrated the potential of DTT for protection against hematopoietic injury and intestinal injury after radiation exposure, suggesting DTT as a novel effective agent for radioprotection.

The protective effects of Resveratrol against radiation-induced intestinal injury

Background

Intestinal injury is a potential cause of death after high-dose radiation exposure. The aim of the present study was to investigate the protective effects of resveratrol against radiation-induced small intestine injury.

Methods

C57BL/6 N mice were irradiated and treated with resveratrol and/or Ex527 (a potent Sirt1 inhibitor), and subsequent examining intestinal morphological changes, and crypt cell apoptosis. Then, the expression and enzyme activity of SOD2 in the small intestine were examined. Furthermore, Sirt1 and acetylated p53 expression was analysed.

Results

Compared to the vehicle control, treatment with resveratrol improved intestinal morphology, decreased apoptosis of crypt cells, maintained cell regeneration, and ameliorated SOD2 expression and activity. Resveratrol also regulated Sirt1 and acetylated p53 expression perturbed by irradiation in the small intestine. The protective effect of resveratrol against ionizing radiation induced small intestine injury was significantly inhibited by Ex527.

Conclusion

Our results suggest that resveratrol decreases the effects of radiation on intestinal injury at least partly via activation of Sirt1.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-017-1915-9) contains supplementary material, which is available to authorized users.

Quantification of damage due to low-dose radiation exposure in mice: construction and application of a biodosimetric model using mRNA indicators in circulating white blood cells

Biodosimetry, the measurement of radiation damage in a biologic sample, is a reliable tool for increasing the accuracy of dose estimation. Although established chromosome analyses are suitable for estimating the absorbed dose after high-dose irradiation, biodosimetric methodology to measure damage following low-dose exposure is underdeveloped. RNA analysis of circulating blood containing radiation-sensitive cells is a candidate biodosimetry method. Here we quantified RNA from a small amount of blood isolated from mice following low-dose body irradiation (<0.5 Gy) aimed at developing biodosimetric tools for situations that are difficult to study in humans. By focusing on radiation-sensitive undifferentiated cells in the blood based on Myc RNA expression, we quantified the relative levels of RNA for DNA damage-induced (DDI) genes, such as Bax, Bbc3 and Cdkn1a. The RNA ratios of DDI genes/Myc in the blood increased in a dose-dependent manner 4 h after whole-body irradiation at doses ranging from 0.1 to 0.5 Gy (air-kerma) of X-rays, regardless of whether the mice were in an active or resting state. The RNA ratios were significantly increased after 0.014 Gy (air-kerma) of single X-ray irradiation. The RNA ratios were directly proportional to the absorbed doses in water ranging from 0.1 to 0.5 Gy, based on gamma-irradiation from (137)Cs. Four hours after continuous irradiation with gamma-rays or by internal contamination with a beta-emitter, the increased RNA ratios resembled those following single irradiation. These findings indicate that the RNA status can be utilized as a biodosimetric tool to estimate low-dose radiation when focusing on undifferentiated cells in blood.