The contribution of radiation-induced injury to the gastrointestinal tract in the development of multi-organ dysfunction syndrome or failure

The protective effects of ginseng on x-irradiation-induced intestinal damage in rats

Although radiotherapy is widely employed in the treatment of various malignancies in oncology patients, its use is limited by the toxic effects it causes in surrounding tissues, including the gastrointestinal system. Korean Red Ginseng (KRG) is a traditional drug reported to possess antioxidant and restorative properties in various studies. The purpose of the present study was to investigate the protective effects of KRG against radiation-associated small intestinal damage. Twenty-four male Sprague Dawley rats were randomly assigned into three groups. No procedure was performed on Group 1 (control) during the experiment, while Group 2 (x-irradiation) was exposed to radiation only. Group 3 (x-irradiation + ginseng) received ginseng via the intraperitoneal route for a week prior to x-irradiation. The rats were killed 24 h after radiation. Small intestinal tissues were evaluated using histochemical and biochemical methods. An increase in malondialdehyde (MDA) levels and a decrease in glutathione (GSH) were observed in the x-irradiation group compared to the control group. KRG caused a decrease in MDA and caspase-3 activity and an increase in GSH. Our findings show that it can prevent damage and apoptotic cell death caused by x-irradiation in intestinal tissue and can therefore play a protective role against intestinal injury in patients receiving radiotherapy.

Apigenin and Exposure to Low Dose Gamma Radiation Ameliorate Acetic Acid-Induced Ulcerative Colitis in Rats

Ulcerative colitis (UC) is an inflammatory bowel disease involving chronic and recurring colon inflammation. Current management protocols are limited by adverse effects or short-term symptomatic relief. We aimed to investigate the possible therapeutic prospect of low dose gamma (γ) irradiation or apigenin treatment in acetic acid-induced UC in rats. Induction of UC was carried out by installation of acetic acid intra-rectally. One hour post-induction, rats received a sole dose of γ-radiation (0.5 Gray) or were treated with apigenin (3 mg/kg/day, peroral) for 7 successive days. Antioxidant and anti-inflammatory effects of both agents were assessed via determination of colon malondialdehyde (MDA), reduced glutathione (GSH), total nitrate/nitrite (NOx), mucosal addressin cell adhesion molecule-1 (MAdCAM-1), and interleukin-1beta (IL-1β) contents as well as myeloperoxidase (MPO) activity. Body weight (BW), colon weight/length (W/L) ratio, disease activity index (DAI), and histopathological changes were evaluated. Gamma irradiation and apigenin significantly ameliorated the acetic acid-induced biochemical and histopathological changes. Both therapeutic approaches significantly restored colon contents of the investigated biomarkers. They modulated BW, colon W/L ratio and DAI. This study proposes low dose γ-irradiation as a new therapeutic candidate for the management of UC. We also concluded that apigenin exhibited therapeutic benefits in UC management.

Protective mechanism of a novel aminothiol compound on radiation-induced intestinal injury

PURPOSE

With the development of nuclear technology and radiotherapy, the risk of radiation injury has been increasing. Therefore, it is important to find an effective radiation-protective agent. In this study, we designed and synthesized a novel compound called compound 8, of which the radioprotective effect and mechanism were studied.

MATERIALS AND METHODS

Before being exposed to ionizing radiation, mice were pretreated with compound 8. The 30-day mortality assay, hematoxylin-eosin staining, and immunohistochemistry staining assay were performed to evaluate the anti-radiation effect of the compound 8. TUNEL and immunofluorescence assays were conducted to study the anti-radiation mechanism of compound 8.

RESULTS

Compared to the IR + vehicle group, the 30-day survival rate of mice treated with 25 mg/kg of compound 8 was significantly improved after 8 Gy total body irradiation. In the morphological study of the small intestine, we found that compound 8 could maintain crypt-villus structures in the irradiated mice. Further immunohistochemical staining displayed that compound 8 could improve the survival of Lgr5⁺ cells, ki67⁺ cells, and lysozyme⁺ cells. The results of TUNEL and immunofluorescence assays showed that compound 8 could decrease the expression of apoptosis-related caspase-8/-9, γ-H2AX, Bax, and p53.

CONCLUSIONS

These results indicate that compound 8 exerts its effects by maintaining structure and function of small intestine. It also reduces DNA damage, promotes crypt proliferation and differentiation. Moreover, it may enhance the anti-apoptotic ability of small intestinal tissue by inhibiting the activation of p53 and blocking the caspase cascade reaction. Compound 8 can protect the intestinal tract from post-radiation damage, it is thus a new and effective protective agent of radiation.

The protective effects of Xuebijing injection on intestinal injuries of mice exposed to irradiation

BACKGROUND

Gastrointestinal (GI) injury is one of the most common side effects of radiotherapy. However, there is no ideal therapy method except for symptomatic treatment in the clinic. Xuebijing (XBJ) is a traditional Chinese medicine, used to treat sepsis by injection. In this study, the protective effects of XBJ on radiation-induced intestinal injury (RIII) and its mechanism were explored.

METHODS

The effect of XBJ on survival of irradiated C57BL/6 mice was monitored. Histological changes including the number of crypts and the length of villi were evaluated by H&E. The expression of Lgr5⁺ intestinal stem cells (ISCs), Ki67⁺ cells, villin and lysozymes were examined by immunohistochemistry. The expression of cytokines in the intestinal crypt was detected by RT-PCR. DNA damage and apoptosis rates in the small intestine were also evaluated by immunofluorescence.

RESULTS

In the present study, XBJ improved the survival rate of the mice after 8.0 and 9.0 Gy total body irradiation (TBI). XBJ attenuated structural damage of the small intestine, maintained regenerative ability and promoted proliferation and differentiation of crypt cells, decreased apoptosis rate and reduced DNA damage in the intestine. Elevation of IL-6 and TNF-α was limited, but IL-1, TNF-𝛽 and IL-10 levels were increased in XBJ-treated group after irradiation. The expression of Bax and p53 were decreased after XBJ treatment.

CONCLUSIONS

Taken together, XBJ provides a protective effect on RIII by inhibiting inflammation and blocking p53-related apoptosis pathway.

Clinical comprehensive and experimental assessment of the radioprotective effect of Annona muricata leaf extract to prevent cellular damage in the ileum tissue

We report the radioprotective attitude of Annona muricata (AM) leaf extract as antioxidant material to prevent cellular damage in the ileum tissue. The protective effects of an ethyl acetate extract of AM leaves are comprehensively investigated against radiation-induced ileal damage in numerous rats. Thirty-two adult female rats were separated into 4 groups (3 intervention groups and 1 control) as follows: controls received 0.01 mL/kg distilled water, the AM group received 300 mg/kg AM leaf extract, the ionizing radiation (IR) group received a single dose of whole body radiation (8.3 Gy) after 0.01 mL/kg saline treatment, and the AM + IR group received 300 mg/kg AM leaf extract treatment and were subjected to whole body radiation (8.3 Gy) 1 h after the last gavage. All treatments are administered by oral gavage once a day for 9 days. At the end of the experiment, biochemical total oxidant status (TOS, interleukin-6, and caspase) and histological examinations are performed on blood samples as well as ileum tissue. TOS levels are found to be significantly high in rats, which received irradiation, and those in the AM group when compared to controls. These findings suggest that AM has radioprotective effects on ileum tissue, likely because of its antioxidative properties. The findings of this research may contribute to the minimizing of major side effects induced by excessive radiation exposure in patients undergoing radiotherapy and may serve as a significant impetus for further assessments. However, future studies are highly recommended to confirm safety and to determine extraction technique and dosage before human use can be considered.

Investigating the attenuating effect of telmisartan against radiation-induced intestinal injury using 18F-FDG micro-PET imaging

BACKGROUND AND OBJECTIVE

This study was aimed to investigate the ability of ¹⁸F-Fluro-deoxy-glucose (¹⁸F-FDG)-based micro-positron emission tomography (microPET) imaging to evaluate the efficacy of telmisartan, a highly selective angiotensin II receptor antagonist (ARA), in intestinal tissue recovery process after in vivo irradiation.

METHODS

Male Balb/c mice were randomly divided into four groups of control, telmisartan, irradiation, and telmisartan + irradiation. A solution of telmisartan in phosphate-buffered saline (PBS) was administered orally at 12 mg/kg body weight for seven consecutive days prior to whole body exposing to a single sub-lethal dose of 5 Gy X-rays. The mice were imaged using ¹⁸F-FDG microPET at 9 and 30 days post-irradiation. The ¹⁸F-FDG uptake in jejunum was determined according to the mean standardized uptake value (SUVmean) index. Tissues were also processed in similar time points for histological analysis.

RESULTS

The ¹⁸F-FDG microPET imaging confirmed the efficacy of telmisartan as a potent attenuating agent for ionizing radiation-induced injury of intestine in mice model. The results were also in line with the histological analysis indicating that pretreatment with telmisartan reduced damage to the villi, crypts, and intestinal mucosa compared with irradiated and non-treated group from day 9 to 30 after irradiation.

CONCLUSION

The results revealed that ¹⁸F-FDG microPET imaging could be a good candidate to replace time-consuming and invasive biological techniques for screening of radioprotective agents. These findings were also confirmed by histological examinations which indicated that telmisartan can effectively attenuates radiation injury caused by ionizing-irradiation.

Protective effects of Brownea grandiceps (Jacq.) against ϒ-radiation-induced enteritis in rats in relation to its secondary metabolome fingerprint

Radiation enteritis is the most common complication of radiotherapy in patients with pelvic malignancies. Thus, the radioprotective activity of the total hydro-alcoholic extract (BGE) and the ethyl acetate soluble fraction (EAF) of Brownea grandiceps leaves was evaluated against ϒ-radiation-induced enteritis in rats. (BGE) and (EAF) were characterized using HPLC-PDA-ESI-MS/MS analysis. The total phenolic and flavonoid contents were also quantified. In vivo administration of (BGE) (400 mg/kg) and (EAF) (200 & 400 mg/kg) prevented intestinal injury and maintained the mucosal integrity of irradiated rats through increasing villi length and promoting crypt regeneration. Also, (EAF) showed more potent antioxidant activity than (BGE) through reduction of MDA level and enhancement of GSH content and catalase enzyme activity. (BGE) and (EAF) down-regulated intestinal NF-κB expression leading to diminished expression of downstream inflammatory cytokine TNF-α. Moreover, (EAF) markedly reduced the expression of profibrotic marker TGF-β1. Seventy-nine compounds were tentatively identified, including flavonoids, proanthocyanidins, polar lipids and phenolic acids. (EAF) showed significantly higher total phenolic and flavonoid contents, as compared to (BGE). Results revealed remarkable radioprotective activity of (BGE) and (EAF), with significantly higher activity for (EAF). The chemical constituents of (BGE) and (EAF) strongly supported their radioprotective activity. To the best of our knowledge, the present study describes for the first time the radioprotective activity of B. grandiceps leaves in relation to its secondary metabolome fingerprint; emphasizing the great promise of B. grandiceps leaves, especially (EAF), to be used as natural radio-protective agent.

Preclinical Evaluation of Safety, Pharmacokinetics, Efficacy, and Mechanism of Radioprotective Agent HL-003

Amifostine is a radioprotector with high efficacy but poor safety, short half-life, no oral formulation, and poor compliance, which limits its application. With the increasing risk of exposure to radiation, the development of new radioprotective agents is critical. We previously synthesized a new amifostine derivative, the small molecule compound HL-003. In this study, we focused on evaluating the radioprotective properties of HL-003. Using the in vitro 2,2-diphenyl-1-picrylhydrazyl assay, we initially confirmed HL-003 as a strong antioxidant and demonstrated that its free radical scavenging activity was stronger than that of amifostine. Then, we performed an acute toxicity test, a 28-day toxicity test, a 30-day survival rate test, and a pharmacokinetic study, all of which provided aggregate evidence that HL-003 functioned as a small molecule radioprotector with high efficacy, a favorable safety profile, a long half-life, and oral administration. The intestinal radioprotective mechanism of HL-003 was explored in male C57 mice after abdominal irradiation by analyzing intestinal tissue samples with hematoxylin-eosin staining, immunohistochemistry, TUNEL staining, and immunofluorescence detection. The results showed that HL-003 protected intestinal DNA from radiation damage and suppressed the expression of phosphorylated histone H2AX, phosphorylated p53, and the apoptosis-related proteins caspase-8 and caspase-9, which contributed to maintaining the normal morphology of the small intestine and provided insights into the mechanism of radioprotection. Thus, HL-003 is a small molecule radioprotector with a potential application in radiation medicine.

Coenzyme Q10 attenuates inflammation and fibrosis implicated in radiation enteropathy through suppression of NF-kB/TGF-β/MMP-9 pathways

Radiation enteropathy is one the most common clinical issue for patients receiving radiotherapy for abdominal/pelvic tumors which severely affect the quality of life of cancer patients due to dysplastic lesions (ischemia, ulcer, or fibrosis) that aggravate the radiation damage. Herein, this study demonstrated the prophylactic role of coenzyme Q10 (CoQ10), a powerful antioxidant, against radiotherapy-induced gastrointestinal injury. Male Sprague Dawley rats were divided into four groups: group 1 was defined as control, and group 2 was the irradiated group. Group 3 and 4 were CoQ10 control and radiation plus CoQ10 groups, respectively. CoQ10 (10 mg/kg) was orally administered for 10 days before 10 Gy whole-body radiation and was continued for 4 days post-irradiation. CoQ10 administration protected rats delivered a lethal dose of ϒ-radiation from changes in crypt-villus structures and promoted regeneration of the intestinal epithelium. CoQ10 attenuated radiation-induced oxidative stress by decreasing lipid peroxidation and increasing the antioxidant enzyme catalase activity and reduced glutathione level. CoQ10 also counteracts inflammatory response mediated after radiation exposure through downregulating intestinal NF-ĸB expression which subsequently decreased the level of inflammatory cytokine IL-6 and the expression of COX-2. Radiation-induced intestinal fibrosis confirmed via Masson's trichrome staining occurred through upregulating transforming growth factor (TGF)-β1 and matrix metalloproteinase (MMP)-9 expression, while CoQ10 administration significantly diminishes these effects which further confirmed the anti-fibrotic property of CoQ10. Therefore, CoQ10 is a promising radioprotector that could prevent intestinal complications and enhance the therapeutic ratio of radiotherapy in patients with pelvic tumors through suppressing the NF-kB/TGF-β1/MMP-9 signaling pathway.

Protective effects of zingerone derivate on ionizing radiation-induced intestinal injury

Intestinal injury is the primary toxicity of radiotherapy for pelvic and abdominal tumors, and it is also one of the common acute complications of radiotherapy. At present, there are no effective drugs to prevent intestinal injury in the clinic. Zingerone is a natural product with radioprotective effects. In this study, a novel compound (thiazolidine hydrochloride, TZC01) was synthesized by structural modification of zingerone. The effects of TZC01 on preventing intestinal injury from radiation were further investigated in this study. C57BL/6N mice were exposed to a lethal dose of abdominal irradiation (ABI) with and without TZC01 treatments. The morphological changes of the intestine and various makers of intestinal crypt cells were investigated. Treatment with TZC01 improved the survival rate of mice exposed to 12 Gy ABI. Moreover, TZC01 protected the intestinal morphology of mice, decreased the apoptotic rate of intestinal crypt cells, maintained cell regeneration and promoted crypt cell proliferation and differentiation. This study suggests that TZC01 has preventive and therapeutic effects on radiation enteritis by promoting the proliferation and differentiation of crypt cells to protect the small intestine from the toxic effects of ionizing radiation. Furthermore, the study of TCZ01 lays a strong foundation for developing novel radioprotectors with multiple properties.

C/EBPδ protects from radiation-induced intestinal injury and sepsis by suppression of inflammatory and nitrosative stress

Ionizing radiation (IR)-induced intestinal damage is characterized by a loss of intestinal crypt cells, intestinal barrier disruption and translocation of intestinal microflora resulting in sepsis-mediated lethality. We have shown that mice lacking C/EBPδ display IR-induced intestinal and hematopoietic injury and lethality. The purpose of this study was to investigate whether increased IR-induced inflammatory, oxidative and nitrosative stress promote intestinal injury and sepsis-mediated lethality in Cebpd^−/− mice. We found that irradiated Cebpd^−/− mice show decreased villous height, crypt depth, crypt to villi ratio and expression of the proliferation marker, proliferating cell nuclear antigen, indicative of intestinal injury. Cebpd^−/− mice show increased expression of the pro-inflammatory cytokines (Il-6, Tnf-α) and chemokines (Cxcl1, Mcp-1, Mif-1α) and Nos2 in the intestinal tissues compared to Cebpd^+/+ mice after exposure to TBI. Cebpd^−/− mice show decreased GSH/GSSG ratio, increased S-nitrosoglutathione and 3-nitrotyrosine in the intestine indicative of basal oxidative and nitrosative stress, which was exacerbated by IR. Irradiated Cebpd-deficient mice showed upregulation of Claudin-2 that correlated with increased intestinal permeability, presence of plasma endotoxin and bacterial translocation to the liver. Overall these results uncover a novel role for C/EBPδ in protection against IR-induced intestinal injury by suppressing inflammation and nitrosative stress and underlying sepsis-induced lethality.

Protective Effect of Melatonin Against Radiotherapy-Induced Small Intestinal Oxidative Stress: Biochemical Evaluation

Background and Objectives: Radiation enteritis is a common side effect after radiotherapy for abdominal and pelvic malignancies. The aim of the present study was to investigate the protective effect of melatonin, known for its free radical scavenging ability, against radiotherapy-induced small intestinal oxidative damage. Materials and Methods: Thirty male Wistar rats were randomly assigned to six groups (5 rats in each) as follows: Group I (control group) rats received neither radiation nor melatonin; group II rats received only 8 Gy single dose of gamma radiation to their abdomen and pelvis regions; group III (administered with only 50 mg/kg melatonin); group IV (administered with only 100 mg/kg melatonin); group V (50 mg/kg melatonin + 8 Gy radiation), group VI (100 mg/kg melatonin + 8 Gy radiation). All rats were sacrificed after 5 days for biochemical assessments of their intestinal tissues. Results: Treatment with melatonin post irradiation significantly reduced malondialdehyde (MDA) levels as well as increased both superoxide dismutase (SOD) and catalase (CAT) activities of the irradiated intestinal tissues. In addition, melatonin administration with different doses pre irradiation led to protection of the tissues. Moreover, the 100 mg/kg dose was more effective compared to 50 mg/kg. Conclusions: The results of our study suggest that melatonin has a potent protective effect against radiotherapy-induced intestinal damage, by decreasing oxidative stress and increasing antioxidant enzymes. We recommend future clinical trials for more insights.

Rheinic acid ameliorates radiation-induced acute enteritis in rats through PPAR-γ/NF-κB

BACKGROUND

Acute radiation enteritis (ARE), a common complication of intestinal caused by abdominal and pelvic radiation therapy. Rheinic acid is a major active ingredient derived from Rhubarb. Rhubarb could suppress inflammation, tumor, fibrosis oxidative damage. However, RA as the main active component and extract monomer of Rhubarb, the pharmacological activity and the underlying molecular mechanism on various diseases has not yet been revealed.

OBJECTIVE

To determine the potential role of rheinic acid (RA) in ameliorating inflammation of rats with acute radiation enteritis (ARE), and explore the underlying mechanism.

METHODS

ARE rat model was established by irradiated with single-dose 10 Gy X-rays at a rate of 0.62 Gy/min to the abdomen. The rats were executed after orally administered with Rheinic acid 7 days and used in the subsequent experiments. Body weight, fecal characteristics and bloody of rats were used to assess the disease activity index. Histological analysis of the jejunum and colon were evaluated using H&E staining. The pro-inflammatory cytokines levels were measured by immunohistochemistry and ELISA. The levels of nitric oxide (NO), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH) were also determined. The mRNA and protein expression were examined by real-time polymerase chain reaction (qRT-PCR) and western blot, respectively.

RESULTS

Rheinic acid promoted intestinal functional recovery, and ameliorated intestinal damage and bloody stool in ARE rats. Rheinic acid strongly decreased the levels of tumor necrosis factor-α, interleukin-1, interleukin-6, NO, and MDA, whereas increased levels of anti-oxidants, SOD and GSH. Moreover, the expression of apoptosis-related proteins, cleaved caspase-3 and cleaved poly (ADP-ribose) polymerase (PARP), were decreased with RA treatment. Further study indicated that PPAR-γ was activated and thereby NF-κB and p38 MAPK signaling pathway were suppressed after rheinic acid treatment.

CONCLUSION

Rheinic acid could ameliorate acute radiation enteritis and the underlying molecular mechanism is, at least partially, through PPAR-γ/NF-κB and p38 MAPK/JNK pathways.

Flavonoids protect colon against radiation induced colitis

Radiation induced colitis is one the most common clinical issue for patients receiving radiotherapy. For this reason, we aimed to investigate the effect of antioxidant-effective flavonoids hesperidin and quercetin on the intestinal damage induced by radiation in this study. TNF-alpha, interleukin-10 (IL-10), heat shock protein 70 (HSP 70) and caspase 3, 8, 9 markers of apoptotic pathways were measured in the colon tissues of irradiated acute intestinal damage by enzyme-linked immunosorbent assay (ELISA). Irradiation of rats caused a significance increase of TNF-alpha, caspase 3/8/9 and decrease of IL-10 concentrations. Hesperidin and quercetin treatment resulted in decreased levels of TNF-alpha and increased levels of IL-10. Quercetin significantly decreased caspase 3/8/9 levels. Hesperidin produced a decreased of caspase 3/8/9 levels compared with irradiation group but this was statistically not significant. Only significant alteration of HSP 70 were seen in hesperidin treated rats. Further studies are needed to elucidate the mechanism by which flavonoids induced signaling provides protection against apoptosis and inflammation.

The protective effects of XH-105 against radiation-induced intestinal injury

Radiation-induced intestinal injury is one of the major side effects in patients receiving radiation therapy. There is no specific treatment for radiation enteritis in the clinic. We designed and synthesized a new compound named XH-105, which is expected to cleave into polyphenol and aminothiol in vivo to mitigate radiation injury. In the following study, we describe the beneficial effects of XH-105 against radiation-induced intestinal injury. C57BL/6J mice were treated by gavage with XH-105 1 hour before total body irradiation (TBI), and the survival rate was monitored. Histological changes were examined, and survival of Lgr5⁺ intestinal stem cells Ki67⁺ cells, villi⁺ enterocytes and lysozymes was determined by immunohistochemistry. DNA damage and cellular apoptosis in intestinal tissue were also evaluated. Compared to vehicle-treated mice after TBI, XH-105 treatment significantly enhanced the survival rate, attenuated structural damage of the small intestine, decreased the apoptotic rate, reduced DNA damage, maintained cell regeneration and promoted crypt proliferation and differentiation. XH-105 also reduced the expression of Bax and p53 in the small intestine. These data suggest that XH-105 is beneficial for the protection of radiation-induced intestinal injury by inhibiting the p53-dependent apoptosis signalling pathway.

Ginseng oligopeptides protect against irradiation-induced immune dysfunction and intestinal injury

Intestinal injury and immune dysfunction are commonly encountered after irradiation therapy. While the curative abilities of ginseng root have been reported in prior studies, there is little known regarding its role in immunoregulation of intestinal repairability in cancer patients treated with irradiation. Our current study aims to closely examine the protective effects of ginseng-derived small molecule oligopeptides (Panax ginseng C. A. Mey.) (GOP) against irradiation-induced immune dysfunction and subsequent intestinal injury, using in vitro and in vivo models. Expectedly, irradiation treatment resulted in increased intestinal permeability along with mucosal injury in both Caco-2 cells and mice, probably due to disruption of the intestinal epithelial barrier, leading to high plasma lipopolysaccharide (LPS) and pro-inflammatory cytokines levels. However, when the cells were treated with GOP, this led to diminished concentration of plasma LPS and cytokines (IL-1 and TNF-α), suggesting its dampening effect on inflammatory and oxidative stress, and potential role in restoring normal baseline intestinal permeability. Moreover, the Caco-2 cells treated with GOP showed high trans-epithelial electrical resistance (TEER) and low FITC-dextran paracellular permeability when compared to the control group. This could be explained by the higher levels of tight junction proteins (ZO-1 and Occludin) expression along with reduced expression of the apoptosis-related proteins (Bax and Caspase-3) noticed in the GOP-treated cells, highlighting its role in preserving intestinal permeability, through prevention of their degradation while maintaining normal levels of expression. Further confirmatory in vivo data showed that GOP-treated mice exhibited high concentrations of lymphocytes (CD3+, CD4+, CD8+) in the intestine, to rescue the irradiation-induced damage and restore baseline intestinal integrity. Therefore, we propose that GOP can be used as an adjuvant therapy to attenuate irradiation-induced immune dysfunction and intestinal injury in cancer patients.

The Protective Effect of New Compound XH-103 on Radiation-Induced GI Syndrome

Background

Radiation-induced intestinal injury is one of the side effects in patients receiving radiotherapy. The aim of the present study was to investigate the protective effect of XH-103 on radiation-induced small intestinal injury and to explore its mechanism.

Methods

C57BL/6N mice were irradiated and treated with XH-103. Firstly, the survival rate of mice exposed to 9.0 Gy and 11.0 Gy total body irradiation (TBI) was examined. Subsequently, at 3.5 d after IR, the small intestinal morphological changes were examined by HE. The numbers of crypt cells, the villus height, the expression of Ki67 and Lgr5, and the apoptotic cells in the intestinal crypts were examined by immunohistochemistry. Furthermore, the expression of p53 and Bax was analyzed by WB.

Results

Compared to the irradiation group, XH-103 improved the mice survival rate, protected the intestinal morphology of mice, decreased the apoptotic rate of intestinal crypt cells, maintained cell regeneration, and promoted crypt proliferation and differentiation. XH-103 also reduced the expression of p53 and Bax in the small intestine compared to the IR group.

Conclusion

These data demonstrate that XH-103 can prevent radiation-induced intestinal injury, which is beneficial for the protection of radiation injuries.

Expanded Characterization of a Hemi-Body Shielded Göttingen Minipig Model of Radiation-induced Gastrointestinal Injury Incorporating Oral Dosing Procedures

In collaboration with the Biomedical Advanced Research and Development Authority (BARDA), the authors recently conducted a pilot study in a hemi-body shielded model of radiation-induced gastrointestinal (GI) injury in Göttingen minipigs following exposure to radiation dose levels between 8-16 Gy. Herein, the impact of oral dosing procedures is assessed, as well as the specific causes of death in animals exposed to radiation doses of 14 and 16 Gy (n = 64; 32 male, 32 female, between 6 and 8 mo of age). Oral dosing using a 2-tablet placebo system comprised of both immediate release and enteric-coated tablets starting 24 h post-irradiation resulted in inhibited gastric emptying of the enteric-coated tablets, which were found to be retained in the stomach and/or regurgitated. This finding appears to be species-specific, as similar findings have not been reported for other large animal species (e.g., non-human primates). Mortality was primarily dictated by decreased activity, body weight loss (>35%), and/or respiratory distress, despite shielding of the lung. The cause of respiratory distress in animals that were pre-terminally euthanized varied according to the timing of death, with interstitial inflammation and extensive fibrosis observed >20 days post-irradiation. Kidney damage was also identified in most animals after day 10. Changes in the GI tract were consistent with previous studies and included collagen deposition/fibrosis. Observations of inflammatory infiltrates and interstitial inflammation/fibrosis in both shielded and unshielded organs support a strong secondary inflammatory syndrome post-irradiation.

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.

A PPAR-gamma agonist protects from radiation-induced intestinal toxicity

OBJECTIVE

Because of its anti-inflammatory, anti-fibrotic, anti-apoptotic and anti-neoplastic properties, the PPAR-γ agonist rosiglitazone is an interesting drug for investigating for use in the prevention and treatment of radiation-induced intestinal damage. We aimed to evaluate the radioprotective effect of rosiglitazone in a murine model of acute intestinal damage, assessing whether radioprotection is selective for normal tissues or also occurs in tumour cells.

METHODS

Mice were total-body irradiated (12 Gy), with or without rosiglitazone (5 mg/kg/day). After 24 and 72 hours, mice were sacrificed and the jejunum was collected. HT-29 human colon cancer cells were irradiated with a single dose of 2 (1000 cells), 4 (1500 cells) or 6 (2000 cells) Gy, with or without adding rosiglitazone (20 µM) 1 hour before irradiation. HT-29-xenografted CD1 mice were irradiated (16 Gy) with or without rosiglitazone; tumour volumes were measured for 33 days.

RESULTS

Rosiglitazone markedly reduced histological signs of altered bowel structures, that is, villi shortening, submucosal thickening, necrotic changes in crypts, oedema, apoptosis, and inflammatory infiltrate induced by irradiation. Rosiglitazone significantly decreased p-NF-kB p65 phosphorylation and TGFβ protein expression at 24 and 72 hours post-irradiation and significantly decreased gene expression of Collagen1, Mmp13, Tnfα and Bax at 24 hours and p53 at 72 hours post-irradiation. Rosiglitazone reduced HT-29 clonogenic survival, but only produced a slight reduction of xenograft tumour growth.

CONCLUSION

Rosiglitazone exerts a protective effect on normal tissues and reduces alterations in bowel structures and inflammation in a radiation-induced bowel toxicity model, without interfering with the radiation effect on HT-29 cancer cells. PPAR-γ agonists should be further investigated for their application in abdominal and pelvic irradiation.

Suppression of TNF-α and free radicals reduces systematic inflammatory and metabolic disorders: Radioprotective effects of ginseng oligopeptides on intestinal barrier function and antioxidant defense

Irradiation therapy is markedly associated with intestinal injure and oxidant stress. This study aimed to investigate the effects of ginseng (Panax ginseng C.A. Mey.) oligopeptides (GOP) on irradiation-induced intestinal injury and antioxidant defense in mice. BALB/c mice (8 weeks old) were randomly divided into six groups: vehicle control, irradiation control (IR), IR+whey protein [0.30 g/kg body weight (BW)], IR+GOP 0.15 g/kg BW, IR+GOP 0.30 g/kg BW and IR+GOP 0.60 g/kg BW. Postirradiation 30-day survival trial, white blood cells count and bone marrow hematopoietic system damage were performed to identify the injury degree induced by irradiation. Then, histopathology analysis was observed and intestinal permeability in vivo was quantified with fluorescein isothiocyanate-dextran. The enzyme-linked immunosorbent assay was used to determine antioxidant ability, plasma inflammatory cytokines, diamine oxidase (DAO) and endotoxin (LPS) levels. The immunohistochemistry assay was used to analyze the expression levels of tight junction proteins. We found that GOP-treated mice exhibited lower concentrations of plasma LPS and DAO and decreased instructors of inflammatory and oxidative stress which were linked to the lower intestinal permeability and higher tight junction proteins expression. The blockage of GOP was linked with the reduction of TNF-α and free radicals. The 15-day pretreatment of GOP could exhibit radioprotective effects, and another 15-day posttreatment benefited the quick repair of irradiation-induced injury. We confirm that GOP would exhibit effective therapeutic value on attenuating irradiation-induced hematopoietic, gastrointestinal and oxidative injury in cancer patients.

Rapid disruption of intestinal epithelial tight junction and barrier dysfunction by ionizing radiation in mouse colon in vivo: protection by N-acetyl-l-cysteine

The goals of this study were to evaluate the effects of ionizing radiation on apical junctions in colonic epithelium and mucosal barrier function in mice in vivo. Adult mice were subjected to total body irradiation (4 Gy) with or without N-acetyl-l-cysteine (NAC) feeding for 5 days before irradiation. At 2-24 h postirradiation, the integrity of colonic epithelial tight junctions (TJ), adherens junctions (AJ), and the actin cytoskeleton was assessed by immunofluorescence microscopy and immunoblot analysis of detergent-insoluble fractions for TJ and AJ proteins. The barrier function was evaluated by measuring vascular-to-luminal flux of fluorescein isothiocyanate (FITC)-inulin in vivo and luminal-to-mucosal flux in vitro. Oxidative stress was evaluated by measuring protein thiol oxidation. Confocal microscopy showed that radiation caused redistribution of occludin, zona occludens-1, claudin-3, E-cadherin, and β-catenin, as well as the actin cytoskeleton as early as 2 h postirradiation, and this effect was sustained for at least 24 h. Feeding NAC before irradiation blocked radiation-induced disruption of TJ, AJ, and the actin cytoskeleton. Radiation increased mucosal permeability to inulin in colon, which was blocked by NAC feeding. The level of reduced-protein thiols in colon was depleted by radiation with a concomitant increase in the level of oxidized-protein thiol. NAC feeding blocked the radiation-induced protein thiol oxidation. These data demonstrate that radiation rapidly disrupts TJ, AJ, and the actin cytoskeleton by an oxidative stress-dependent mechanism that can be prevented by NAC feeding.

Effect of combined radiation injury on cell death and inflammation in skin

In the event of a nuclear disaster, the individuals proximal to the source of radiation will be exposed to combined radiation injury. As irradiation delays cutaneous repair, the purpose of this study was to elucidate the effect of combined radiation and burn injury (CRBI) on apoptosis and inflammation at the site of skin injury. Male C57Bl/6 mice were exposed to no injury, thermal injury only, radiation only (1 and 6 Gy) and CRBI (1 and 6 Gy) and euthanized at various times after for skin collection. TUNEL staining revealed that the CRBI 6 Gy group had a delayed and increased apoptotic response. This correlated with decreased recovery of live cells as compared to the other injuries. Similar response was observed when cleaved-caspase-3 immunohistochemical staining was compared between CRBI 6 Gy and thermal injury. TNFR1, caspase 8, Bax and IL-6 mRNA expression revealed that the higher CRBI group had delayed increase in mRNA expression as compared to thermal injury alone. RIPK1 mRNA expression and necrotic cell counts were delayed in the CRBI 6 Gy group to day 5. TNF-α and NFκB expression peaked in the CRBI 6 Gy group at day 1 and was much higher than the other injuries. Also, inflammatory cell counts in the CRBI 6 Gy group were lower at early time points as compared to thermal injury by itself. These data suggest that CRBI delays and exacerbates apoptosis and inflammation in skin as well as increases necrosis thus resulting in delayed wound healing.

The protective effects of apocynin on ionizing radiation-induced intestinal damage in rats

BACKGROUND AND AIMS

Radiation colitis typically emerges during radiotherapy of intra-abdominal malignancies. While the underlying mechanism remains unclear, it is considered that free oxygen radicals act like cellular mediators to cause colonic damage. Apocynin (APO) prevents oxidative stress and apoptotic cell death by inhibiting NADPH oxidase, and preventing the formation of free oxygen radicals. The aim of the present study was to investigate the protective effect of APO, a strong antioxidant and antiinflammatory agent, on radiation induced colonic oxidative damage in rats.

MATERIALS AND METHODS

Rats were randomly divided into four groups (n = 8/group). Group I (control group); Group II (Group RAD) received a single dose of 800 cGy ionizing radiation to the whole abdomen with a linear accelerator (LINAC); Group III (Group APO) received a single dose of 20 mg/kg of APO intraperitoneally for five days; Group IV (Group APO+RAD) received APO for five days before radiation exposure (similar to Group III), (similar to Group II).

RESULTS

APO treatment prior to radiation led to protection in the biochemical and histopathological parameters.

CONCLUSIONS

Our study shows that APO treatment before radiation improves radiation induced colonic injury in rats, by decreasing oxidative stress and apoptosis.

Evaluation of new bone formation in irradiated areas using association of mesenchymal stem cells and total fresh bone marrow mixed with calcium phosphate scaffold

The consequences of the treatment of the squamous cell carcinomas of the upper aerodigestive tract (bone removal and external radiation therapy) are constant. Tissue engineering using biphasic calcium phosphate (BCP) and mesenchymal stem cells (MSC) is considered as a promising alternative. We previously demonstrated the efficacy of BCP and total fresh bone marrow (TBM) in regenerating irradiated bone defect. The aim of this study was to know if adding MSC to BCP + TBM mixture could improve the bone formation in irradiated bone defects. Twenty-four Lewis 1A rats received a single dose of 20 Gy to the hind limbs. MSC were sampled from non-irradiated donors and amplified in proliferative, and a part in osteogenic, medium. 3 weeks after, defects were created on femurs and tibias, which were filled with BCP alone, BCP + TBM, BCP + TBM + uncommitted MSC, or BCP + TBM + committed MSC. 3 weeks after, samples were removed and prepared for qualitative and quantitative analysis. The rate of bone ingrowth was significantly higher after implantation of BCP + TBM mixture. The adding of a high concentration of MSC, committed or not, didn't improve the bone regeneration. The association BCP + TBM remains the most efficient material for bone substitution in irradiated areas.

Single administration of p2TA (AB103), a CD28 antagonist peptide, prevents inflammatory and thrombotic reactions and protects against gastrointestinal injury in total-body irradiated mice

The goal of this study was to elucidate the action of the CD28 mimetic peptide p2TA (AB103) that attenuates an excessive inflammatory response in mitigating radiation-induced inflammatory injuries. BALB/c and A/J mice were divided into four groups: Control (C), Peptide (P; 5 mg/kg of p2TA peptide), Radiation (R; total body irradiation with 8 Gy γ-rays), and Radiation + Peptide (RP; irradiation followed by p2TA peptide 24 h later). Gastrointestinal tissue damage was evaluated by analysis of jejunum histopathology and immunohistochemistry for cell proliferation (Cyclin D1) and inflammation (COX-2) markers, as well as the presence of macrophages (F4/80). Pro-inflammatory cytokines IL-6 and KC as well as fibrinogen were quantified in plasma samples obtained from the same mice. Our results demonstrated that administration of p2TA peptide significantly reduced the irradiation-induced increase of IL-6 and fibrinogen in plasma 7 days after exposure. Seven days after total body irradiation with 8 Gy of gamma rays numbers of intestinal crypt cells were reduced and villi were shorter in irradiated animals compared to the controls. The p2TA peptide delivery 24 h after irradiation led to improved morphology of villi and crypts, increased Cyclin D1 expression, decreased COX-2 staining and decreased numbers of macrophages in small intestine of irradiated mice. Our study suggests that attenuation of CD28 signaling is a promising therapeutic approach for mitigation of radiation-induced tissue injury.

Attenuating effects of omega-3 fatty acids (Omegaven) on irradiation-induced intestinal injury in mice

Gastrointestinal injury is a major cause of death following exposure to high levels of irradiation, and no effective treatments are currently available. In this study, we examined the effect of omega-3 fatty acids (Omegaven) on intestinal injury of BALB/c mice induced by irradiation. Intravenously administered 3 days prior to irradiation for 7 consecutive days, Omegaven was shown to improve survival, intestinal morphology including villous height, crypt height and mucosal thickness and the intestinal proliferation compared with saline control. Omegaven also normalized the levels of circulating tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6), attenuated the increase of diamino oxidase (DAO) activity and malondialdehyde (MDA) level and recovered the decrease of superoxide dismutase (SOD) activity. Meanwhile, Omegaven attenuated the myelosuppression caused by irradiation. In conclusion, our results suggest that Omegaven enhanced the survival of irradiated mice and minimized the effects of radiation on gastrointestinal injury.

In vitro and in vivo protective effects of granulocyte colony-stimulating factor against radiation-induced intestinal injury

Intestinal injury is a major cause of death after high-dose radiation exposure. The use of granulocyte-colony stimulating factor (G-CSF) to treat radiation injury has focused on enhancing recovery from hematopoietic radiation syndrome. We evaluated G-CSF for its ability to protect against radiation-induced intestinal injury in rat intestinal epithelial cells (IEC-6) and BALB/c mouse models. For in vitro tests, pre-radiation addition of G-CSF to IEC-6 prevented cytotoxicity and the loss of cell viability. Pre-radiation G-CSF treatment also reduced radiation-induced cleavage of caspase-3 and p53 in IEC-6. For in vivo tests, examination 12 h after abdominal irradiation showed that G-CSF-treated mice were protected against apoptosis of the jejunal crypts. G-CSF-treated mice also showed attenuated intestinal morphological changes 3.5 days after abdominal radiation (10 Gy). G-CSF also reduced the levels of proinflammatory cytokines interleukin-6 and tumor necrosis factor-α after radiation. This study showed that G-CSF may protect against radiation-induced intestinal damage through its anti-apoptotic and anti-inflammatory effects. These results suggest that G-CSF is promising candidate for protection against intestinal mucosal injury following irradiation.

Protection by L-carnitine against radiation-induced ileal mucosal injury in the rat: pattern of oxidative stress, apoptosis and cytokines

PURPOSE

In this study, we tested the effects of L-carnitine (LC) on radiation-induced ileal mucosal damage.

MATERIALS AND METHODS

Thirty Wistar albino rats were divided into five groups. The control group received physiological saline intraperitoneally (i.p.). Radiation-1 and radiation-2 groups received whole-body X-irradiation of 8.3 Gy as a single dose. These groups were sacrificed at the 6th hour and 4th day after irradiation, respectively. The Radiation-1 + LC and the radiation-2 + LC groups received the same dose irradiation plus a daily dose of 200 mg/kg LC. LC was applied one day before and for four days after irradiation.

RESULTS

The levels of serum monocyte chemotactic protein-1 (MCP-1) and interferon gamma (IFN-γ) were significantly higher in the radiation groups when compared with the control. Treatment with LC decreased the serum MCP-1 and IFN-γ levels considerably. In the radiations groups, the Chiu score was significantly elevated compared with that of the control group. However, LC administered prior to the irradiation reduced the severity of mucosal damage. The number of apoptotic cells of the ileal crypt in the irradiated rats increased from the 6th hour after irradiation and then decreased at 4th day.

CONCLUSIONS

Our data demonstrated that LC may be beneficial to radiation enteritis.

Attenuating effects of granulocyte-colony stimulating factor (G-CSF) in radiation induced intestinal injury in mice

Gastrointestinal injury is a major cause of death following exposure to high levels of radiation, and no effective treatments are currently available. In this study, we examined the capacity of granulocyte colony-stimulating factor (G-CSF) to mitigate intestinal injury in, and improve survival of, C3H/HeN mice given a lethal dose (12 Gy) of radiation to the abdomen. G-CSF (100 μg/kg body weight) was injected subcutaneously daily for 3 days after irradiation and shown to improve survival and intestinal morphology at 3.5 days compared with saline-injected controls. The morphological features improved by G-CSF included crypt number and depth, villous length, and the length of basal lamina of 10 enterocytes. G-CSF also normalized the levels of circulating tumor necrosis factor alpha and attenuated the loss of peripheral neutrophils, caused by radiation-induced myelosuppression. In conclusion, our results suggest that G-CSF enhanced the survival of irradiated mice and minimized the effects of radiation on gastrointestinal injury.

Comparison of the dose-response relationship of radiation-induced apoptosis in the hippocampal dentate gyrus and intestinal crypt of adult mice

The present study compared the dose-response curves for the frequency of apoptosis in mouse hippocampal dentate gyrus (DG) and intestinal crypt using whole-body gamma irradiation. The incidence of gamma-ray-induced apoptosis was measured using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end-labelling (TUNEL) method. TUNEL-positive apoptotic nuclei in the DG and intestinal crypt were increased in a dose-dependent pattern (0-2 Gy). The dose-response curves were linear-quadratic, with a significant relationship between the appearance of apoptosis and irradiation dose. The slopes of the dose-response curves in the DG were much steeper (~5-6-fold) than those in the intestinal crypt within the range of 0-1 Gy exposure. Hippocampal DG might be a more effective and sensitive evaluation structure than the intestinal crypt to estimate the degree of radiation exposure in damaged organs of adult mice exposed to low irradiation dose.

ICRP publication 118: ICRP statement on tissue reactions and early and late effects of radiation in normal tissues and organs--threshold doses for tissue reactions in a radiation protection context

This report provides a review of early and late effects of radiation in normal tissues and organs with respect to radiation protection. It was instigated following a recommendation in Publication 103 (ICRP, 2007), and it provides updated estimates of 'practical' threshold doses for tissue injury defined at the level of 1% incidence. Estimates are given for morbidity and mortality endpoints in all organ systems following acute, fractionated, or chronic exposure. The organ systems comprise the haematopoietic, immune, reproductive, circulatory, respiratory, musculoskeletal, endocrine, and nervous systems; the digestive and urinary tracts; the skin; and the eye. Particular attention is paid to circulatory disease and cataracts because of recent evidence of higher incidences of injury than expected after lower doses; hence, threshold doses appear to be lower than previously considered. This is largely because of the increasing incidences with increasing times after exposure. In the context of protection, it is the threshold doses for very long follow-up times that are the most relevant for workers and the public; for example, the atomic bomb survivors with 40-50years of follow-up. Radiotherapy data generally apply for shorter follow-up times because of competing causes of death in cancer patients, and hence the risks of radiation-induced circulatory disease at those earlier times are lower. A variety of biological response modifiers have been used to help reduce late reactions in many tissues. These include antioxidants, radical scavengers, inhibitors of apoptosis, anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, growth factors, and cytokines. In many cases, these give dose modification factors of 1.1-1.2, and in a few cases 1.5-2, indicating the potential for increasing threshold doses in known exposure cases. In contrast, there are agents that enhance radiation responses, notably other cytotoxic agents such as antimetabolites, alkylating agents, anti-angiogenic drugs, and antibiotics, as well as genetic and comorbidity factors. Most tissues show a sparing effect of dose fractionation, so that total doses for a given endpoint are higher if the dose is fractionated rather than when given as a single dose. However, for reactions manifesting very late after low total doses, particularly for cataracts and circulatory disease, it appears that the rate of dose delivery does not modify the low incidence. This implies that the injury in these cases and at these low dose levels is caused by single-hit irreparable-type events. For these two tissues, a threshold dose of 0.5Gy is proposed herein for practical purposes, irrespective of the rate of dose delivery, and future studies may elucidate this judgement further.

α-Tocopherol succinate protects mice against radiation-induced gastrointestinal injury

The purpose of this study was to elucidate the role of α-tocopherol succinate (α-TS) in protecting mice from gastrointestinal syndrome induced by total-body irradiation. CD2F1 mice were injected subcutaneously with 400 mg/kg of α-TS and exposed to different doses of (60)Co γ radiation, and 30-day survival was monitored. Jejunum sections were analyzed for crypts and villi, PUMA (p53 upregulated modulator of apoptosis), and apoptosis (terminal deoxynucleotidyl transferase dUTP nick end labeling - TUNEL). The crypt regeneration in irradiated mice was evaluated by 5-bromo-2-deoxyuridine (BrdU). Bacterial translocation from gut to heart, spleen and liver in α-TS-treated and irradiated mice was evaluated by bacterial culture on sheep blood agar, colistin-nalidixic acid, and xylose-lysine-desoxycholate medium. Our results demonstrate that α-TS enhanced survival in a significant number of mice irradiated with 9.5, 10, 11 and 11.5 Gy (60)Co γ radiation when administered 24 h before radiation exposure. α-TS also protected the intestinal tissue of irradiated mice in terms of crypt and villus number, villus length and mitotic figures. TS treatment decreased the number of TUNEL- and PUMA-positive cells and increased the number of BrdU-positive cells in jejunum compared to vehicle-treated mice. Further, α-TS inhibited gut bacterial translocation to the heart, spleen and liver in irradiated mice. Our data suggest that α-TS protects mice from radiation-induced gastrointestinal damage by inhibiting apoptosis, promoting regeneration of crypt cells, and inhibiting translocation of gut bacteria.

Literature review and global consensus on management of acute radiation syndrome affecting nonhematopoietic organ systems

OBJECTIVES

The World Health Organization convened a panel of experts to rank the evidence for medical countermeasures for management of acute radiation syndrome (ARS) in a hypothetical scenario involving the hospitalization of 100 to 200 victims. The goal of this panel was to achieve consensus on optimal management of ARS affecting nonhematopoietic organ systems based upon evidence in the published literature.

METHODS

English-language articles were identified in MEDLINE and PubMed. Reference lists of retrieved articles were distributed to conferees in advance of and updated during the meeting. Published case series and case reports of ARS, publications of randomized controlled trials of relevant interventions used to treat nonirradiated individuals, reports of studies in irradiated animals, and prior recommendations of subject matter experts were selected. Studies were extracted using the Grading of Recommendations Assessment Development and Evaluation system. In cases in which data were limited or incomplete, a narrative review of the observations was made.

RESULTS

No randomized controlled trials of medical countermeasures have been completed for individuals with ARS. Reports of countermeasures were often incompletely described, making it necessary to rely on data generated in nonirradiated humans and in experimental animals. A strong recommendation is made for the administration of a serotonin-receptor antagonist prophylactically when the suspected exposure is >2 Gy and topical steroids, antibiotics, and antihistamines for radiation burns, ulcers, or blisters; excision and grafting of radiation ulcers or necrosis with intractable pain; provision of supportive care to individuals with neurovascular syndrome; and administration of electrolyte replacement therapy and sedatives to individuals with significant burns, hypovolemia, and/or shock. A strong recommendation is made against the use of systemic steroids in the absence of a specific indication. A weak recommendation is made for the use of fluoroquinolones, bowel decontamination, loperamide, and enteral nutrition, and for selective oropharyngeal/digestive decontamination, blood glucose maintenance, and stress ulcer prophylaxis in critically ill patients.

CONCLUSIONS

High-quality studies of therapeutic interventions in humans exposed to nontherapeutic radiation are not available, and because of ethical concerns regarding the conduct of controlled studies in humans, such studies are unlikely to emerge in the near future.

After the bomb drops: a new look at radiation-induced multiple organ dysfunction syndrome (MODS)

PURPOSE

There is increasing concern that, since the Cold War era, there has been little progress regarding the availability of medical countermeasures in the event of either a radiological or nuclear incident. Fortunately, since much is known about the acute consequences that are likely to be experienced by an exposed population, the probability of survival from the immediate hematological crises after total body irradiation (TBI) has improved in recent years. Therefore focus has begun to shift towards later down-stream effects, seen in such organs as the gastrointestinal tract (GI), skin, and lung. However, the mechanisms underlying therapy-related normal tissue late effects, resulting from localised irradiation, have remained somewhat elusive and even less is known about the development of the delayed syndrome seen in the context of whole body exposures, when it is likely that systemic perturbations may alter tissue microenvironments and homeostasis.

CONCLUSIONS

The sequence of organ failures observed after near-lethal TBI doses are similar in many ways to that of multiple organ dysfunction syndrome (MODS), leading to multiple organ failure (MOF). In this review, we compare the mechanistic pathways that underlie both MODS and delayed normal tissue effects since these may impact on strategies to identify radiation countermeasures.

Effect of total body irradiation on late lung effects: hidden dangers

PURPOSE

In our ongoing investigation into the consequences of a radiological terrorism or nuclear dispersion event, we assessed whether a dose range that is believed to be sub-threshold for the development of lung endpoints results in late pathological changes and, secondarily, whether those late changes affect the lung's ability to respond to subsequent challenge.

MATERIALS AND METHODS

C57BL/6J mice received total body irradiation (0.5-10 Gy) and were followed for 6-18 months after irradiation. At 12 and 15 months, a subset of mice was exposed to a second challenge (aerosolised lipopolysaccharide [LPS]).

RESULTS

Cytokines shown to be upregulated early (hours) following irradiation (interleukin [IL]6, keratinocyte chemoattractant [KC], IL1B, and IL1R2) demonstrated increases in messenger ribose nucleic acid (mRNA) expression at late time points, beginning at nine months. Although persistent, dose-dependent increases in T cell counts were seen, no other overt changes in pathophysiology were observed. Nonetheless, animals that were exposed to a secondary challenge at late time points demonstrated an increased inflammatory cell recruitment and persistence in response relative to controls.

CONCLUSIONS

We propose that, following doses that elicit little change in pathophysiology, sub-clinical radiation-induced injury increases the lungs' susceptibility to a secondary challenge, possibly through a radiation-induced alteration in the immune defense system.

Preclinical evaluation of Som230 as a radiation mitigator in a mouse model: postexposure time window and mechanisms of action

The somatostatin analog SOM230 has potent radioprophylactic and radiation mitigating properties that are unrelated to cytoprotection but appear to be due to suppression of secretion of pancreatic enzymes into the intestinal lumen. To determine the maximal postirradiation time window for administration, male CD2F1 mice were exposed to 8.5-11 Gy total-body radiation; SOM230 (0.5, 2 or 5 mg/kg) or vehicle was given by twice daily subcutaneous injections for 14 days, beginning 24-72 h after irradiation, and 30-day animal survival was recorded. The contribution of the gut to systemic cytokine levels was estimated by analyzing plasma samples obtained simultaneously from the portal vein and carotid artery. The effect of SOM230 on cell trypsin secretion was assessed in vitro and intestinal proteolytic activity was measured in vivo. SOM230 was associated with a 40-60% absolute improvement in overall postirradiation survival when treatment was started 48 h after irradiation and even exhibited a statistically significant survival benefit when started at 72 h. SOM230 ameliorated the radiation-induced decrease in chemokine (C-X-C motif) ligand 9 (CXCL9). SOM230 inhibited pancreatic acinar cell trypsin secretion in vitro in a dose-dependent fashion and reduced intraluminal and intestinal tissue proteolytic activity in vivo. SOM230 is an excellent radiation mitigator with a postirradiation time window in excess of 48 h. The mechanism likely involves preservation of intestinal barrier function due to decreased secretion of pancreatic enzymes into the bowel lumen.

Hematopoietic radiation syndrome in the Gottingen minipig

Additional large animal models for the acute radiation syndrome (ARS) would facilitate countermeasure development. We demonstrate here that Gottingen minipigs develop hematopoietic ARS symptoms similar to those observed in canines, non-human primates (NHPs) and humans. Dosimetry for whole-body γ irradiation (0.6 Gy/min) was performed using electronic paramagnetic resonance (EPR) with alanine; National Institute of Standards and Technology (NIST)-calibrated alanine pellets and water-filled Plexiglas phantoms were used. After irradiations of 1.6-2.0 Gy, blood pancytopenia was observed for several weeks, accompanied by the characteristic ARS stages: prodromal symptoms, latent period, illness and recovery or morbidity. Morbidity occurred between days 14 and 27, with a preliminary LD(50/30) estimate between 1.7 and 1.9 Gy. The criterion of whether platelet counts were <200 × 10(3)/µl 7 days postirradiation predicted whether animals would survive in 18 out of 20 cases. The degree of granulocytosis 3 h postirradiation was inversely correlated with survival. Animals euthanized based on preset morbidity criteria displayed signs of multi-organ dysfunction, including widespread internal hemorrhage and alterations in organ function reflected in blood chemistry. Circulating C-reactive protein (CRP), a marker for inflammation, became elevated within hours after irradiation, subsided after several days, and increased again after 14 days. The results support further development of the Gottingen minipig as a model for ARS.

Radiation victim management and the haematologist in the future: time to revisit therapeutic guidelines?

PURPOSE

The use of nuclear/radiation devices against the civilian population is now a realistic scenario. Haematopoietic syndrome is the primary therapeutic challenge in the case of whole body acute exposure over 2 Grays (Gy) whereas burns and combined injuries would be frequently observed in myelo-suppressed patients. Optimisation of scoring and treatments are important goals to achieve.

CONCLUSION

The European Response Category (RC) concept represents an attempt to integratively assess haematological/extrahematological radiation-induced lesions. Based on the frequently observed heterogeneity of bone marrow damage in accidental/intentional irradiations, the stimulation of residual stem cells using granulocyte Colony-stimulating factor remains the therapeutic standard after exposure to less than the lethal dose 50 % (Haematopoietic[H] score 3-H3). Allogeneic stem cell transplantation is indicated in case of medullary eradication (Haematopoietic score 4-H4) whereas extramedullary toxicity may determine the outcome. Especially in case of numerous casualties exhibiting acute radiation syndrome, the administration of survival factor combinations remains questionable, at least as a palliative treatment. In addition pleiotropic cytokines injection such as erythropoietin and keratinocyte growth factor and grafting multipotent mesenchymal stem cells - from underexposed bone marrow areas or fat tissues - could be proposed to prevent multiple organ failure syndrome development. Multi-disciplinary teams should be prepared to manage such patients.

A comparison between bone reconstruction following the use of mesenchymal stem cells and total bone marrow in association with calcium phosphate scaffold in irradiated bone

The purpose of this study was to compare bone reconstruction using either mesenchymal stem cells (MSCs) or total bone marrow (TBM) in association with biphasic calcium phosphate (BCP) granules after irradiation in a rat model. Three weeks after an external irradiation of the hind limbs of rats, four bone defects were created per animal. The defects were filled with either BCP alone, or with a mixture of BCP and TBM, or with a mixture of BCP and MSCs (adipose-derived or bone marrow-derived MSCs). Three weeks after implantations, new-bone formation was assessed. Histological examination showed osteoconductive and osteointegrative properties of BCP in irradiated tissue. The BCP-TBM mixture significantly improved bone ingrowth (p<0.05). The BCP-MSCs mixtures did not provide new-bone formation over and above that induced by BCP alone. This gives grounds for suspecting that there is a link between this result and the cellular and vascular weakness observed in irradiated bone. The BCP-TBM mixture may have induced an increased vascularization of irradiated bone. This could be due to the presence of all components in TBM that were lacking in the BCP-MSCs mixtures. BCP associated with TBM appears to be the most efficient material for bone substitution in irradiated areas.

Ginsenoside Rd prevents and rescues rat intestinal epithelial cells from irradiation-induced apoptosis

Panax ginseng has been shown to have a protective effect for irradiated animals or cells. Ginsenosides are the most active components isolated from ginseng, and ginsenoside Rd has been identified as one of the effective compounds responsible for the pharmaceutical actions of ginseng. In the present study, we studied the molecular mechanisms for the radio-protective action of ginsenoside Rd in rat intestinal epithelial IEC-6 cells. Cells were irradiated with gamma-ray, and apoptosis was examined using Hoechst staining and Western blot analysis. Treatment with ginsenoside Rd before gamma-irradiation inhibited irradiation-induced apoptosis in IEC-6 cells. Administration of Rd after irradiation also inhibited apoptosis in these cells. Irradiation of IEC-6 cells resulted in inactivation of Akt phosphorylation that was abrogated by Rd. On the other hand, irradiation activated phosphorylation of ERK1/2 but did not affect that of p38 MAPK. Inhibition of Akt phosphorylation prevented the reduction of apoptosis by Rd following irradiation. Pretreatment with an inhibitor of the MEK pathway further decreased the number of apoptotic cells. Rd decreased the ratios of Bax/Bcl-2 and Bax/Bcl-xL, the levels of cytochrome c, and the cleaved form of caspase-3 in irradiated IEC-6 cells. Our results suggest that ginsenoside Rd protects and rescues rat intestinal epithelial cells from irradiation-induced apoptosis through a pathway requiring activation of PI3K/Akt, inactivation of MEK, and also inhibition of a mitochondria/caspase pathway.

Pathological changes in the gastrointestinal tract of a heavily radiation-exposed worker at the Tokai-mura criticality accident

Gastrointestinal syndrome after high-dose acute radiation whole body exposure is difficult to treat, although it is a well-known complication. In this report, we describe the clinical and pathological features of a patient who died after the criticality accident which occurred in Japan on 30 September 1999. The patient was estimated to have been exposed to 16-25 Gy equivalent of gamma ray, and died of multiple organ failure after acute radiation syndrome, especially gastrointestinal syndrome, on day 82. The stomach and small intestine contained a large amount of blood clots and the gastrointestinal epithelial cells were almost totally depleted at autopsy. In addition, the degree of the mucosal damage was dependent on the segment of the gastrointestinal tract; the mucosa of stomach, ileum and ascending colon was entirely depleted, but the esophagus, descending and sigmoid colon and rectum retained a small portion of the epithelial cells. From the posture of the patient at the time of exposure, the absorbed dose was presumed to be highest in the right-anterior abdomen. This agreed with the pathological differences in the mucosal damage by the position in the abdomen, which depended presumably on the radiation dose. This is the first report documenting the relationship between the absorbed dose and the severity of gastrointestinal damages in vivo.