Effect of alpha-lipoic acid on radiation-induced small intestine injury in mice

Gliclazide protects ionizing radiation-induced intestinal injury in mice by inhibiting oxidative stress and caspase-3

Gliclazide (GLZ), an oral antihyperglycemic medication, has additional beneficial effects, such as anti-inflammatory and antioxidant properties, besides lowering blood glucose levels. In this study, the radio-protective effect of GLZ was evaluated against ionizing radiation (IR)-induced intestinal injury in mice. Eight groups of mice were randomized as follows: control, GLZ (5, 10, and 25 mg/kg), IR (6 Gy), and IR + GLZ (at 5, 10, and 25 mg/kg). GLZ was administered to the mice for eight consecutive days, after which they were exposed to X-rays at a single dose of 6 Gy. After irradiation, biochemical parameters, immunohistochemical, and histological examinations were conducted on the ileum of the mice. IR exposure increased the levels of malondialdehyde and protein carbonyl, while glutathione levels, as oxidative stress biomarkers, decreased. Apoptosis in ileum tissues was also assessed. Furthermore, histopathological changes were observed in the irradiated mice. GLZ treatment significantly mitigated these changes. The administration of GLZ resulted in a marked decrease in caspase-3 immunoreactivity in the ileum of irradiated mice. This preclinical study exhibited that GLZ has a radioprotective effect against intestinal injury by inhibiting oxidative stress and apoptosis.

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.

Protective Effects of Alpha-lipoic Acid, Resveratrol, and Apigenin Against Oxidative Damages, Histopathological Changes, and Mortality Induced by Lung Irradiation in Rats

AIM

This study investigated the protective effects of three antioxidants on radiationinduced lung injury.

BACKGROUND

Oxidative stress is one of the key outcomes of radiotherapy in normal tissues. It can induce severe injuries in lung tissue, which may lead to pneumonitis and fibrosis. Recently, interest in natural chemicals as possible radioprotectors has increased due to their reduced toxicity, cheaper price, and other advantages.

OBJECTIVE

The present study was undertaken to evaluate the radioprotective effect of Alpha-lipoic Acid (LA), Resveratrol (RVT), and Apigenin (APG) against histopathological changes and oxidative damage and survival induced by ionizing radiation (IR) in the lung tissues of rats.

METHODS

First, the lung tissue of 50 mature male Wistar rats underwent an 18 Gy gamma irradiation. Next, the rats were sacrificed and transverse sections were obtained from the lung tissues and stained with hematoxylin and eosin (H and E) and Mason trichrome (MTC) for histopathological evaluation. Then, the activity of Glutathione peroxidase (GPx), Superoxide Dismutase (SOD), and Malondialdehyde (MDA) was measured by an ELISA reader at 340, 405, and 550 nm.

RESULTS

Based on the results of this study, IR led to a remarkable increase in morphological changes in the lung. However, APG, RVT, and LA could ameliorate the deleterious effects of IR in lung tissue. IR causes an increase in GPX level, and APG+IR administration causes a decrease in the level of GPX compared to the control group. Also, the results of this study showed that RVT has significant effects in reducing MDA levels in the short term. In addition, compared to the control group, IR and RVT+IR decrease the activity of SOD in the long term in the lung tissues of rats. Also, the analysis of results showed that weight changes in IR, LA+IR, APG+IR, and control groups were statistically significant.

CONCLUSION

APG and RVT could prevent tissue damage induced by radiation effects in rat lung tissues. Hence, APG, LA, and RVT could provide a novel preventive action with their potential antioxidant anti-inflammatory properties, as well as their great safety characteristic.

Radiotherapy-associated Sensorineural Hearing Loss in Pediatric Oncology Patients

During the radiotherapeutic treatment of pediatric oncology patients, they would be at a latent risk of developing ionizing radiation-induced ototoxicity when the cochlea or auditory nerve is located within the radiation field. Sensorineural hearing loss (SNHL) is an irreversible late complication of radiotherapy, and its incidence depends on various factors such as the patient's hearing sensitivity, total radiation dose to the cochlea, radiotherapy fractionation regimen, age and chemoradiation. Importantly, this complication exhibits serious challenges to adult survivors of childhood cancer, as it has been linked to impairments in academic achievement, psychosocial development, independent living skills, and employment in the survivor population. Therefore, early detection and proper management can alleviate academic, speech, language, social, and psychological morbidity arising from hearing deficits. In the present review, we have addressed issues such as underlying mechanisms of radiation-induced SNHL, audiometric findings of pediatric cancer patients treated with radiotherapy, and management and protection measures against radiation-induced ototoxicity.

Neuroprotective effects of alpha-lipoic acid on radiation-induced brainstem injury in rats

Background and purpose

Alpha-lipoic acid (ALA) is an antioxidant with radioprotective properties. We designed the current work to assess the neuroprotective function of ALA in the presence of oxidative stress induced by radiation in the brainstem of rats.

Experimental approach

Whole-brain radiations (X-rays) was given at a single dose of 25 Gy with or without pretreatment with ALA (200 mg/kg BW). Eighty rats were categorized into four groups: vehicle control (VC), ALA, radiation-only (RAD), and radiation + ALA (RAL). The rats were given ALA intraperitoneally 1 h before radiation and killed following 6 h, thereafter superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and total antioxidant capacity (TAC) in the brainstem were measured. Furthermore, a pathological examination was carried out after 24 h, 72 h, and five days to determine tissue damage.

Findings/Results

The findings indicated that MDA levels in the brainstem were 46.29 ± 1.64 μM in the RAD group and decreased in the VC group (31.66 ± 1.72 μM). ALA pretreatment reduced MDA levels while simultaneously increasing SOD and CAT activity and TAC levels (60.26 ± 5.47 U/mL, 71.73 ± 2.88 U/mL, and 227.31 ± 9.40 mol/L, respectively). The greatest pathological changes in the rat's brainstems were seen in RAD animals compared to the VC group after 24 h, 72 h, and 5 days. As a result, karyorrhexis, pyknosis, vacuolization, and Rosenthal fibers vanished in the RAL group in three periods.

Conclusion and implications

ALA exhibited substantial neuroprotectivity following radiation-induced brainstem damage.

A systematic review of the therapeutic effects of resveratrol in combination with 5-fluorouracil during colorectal cancer treatment: with a special focus on the oxidant, apoptotic, and anti-inflammatory activities

PURPOSE

5-fluorouracil (5-FU), an effective chemotherapy drug, is commonly applied for colorectal cancer treatment. Nevertheless, its toxicity to normal tissues and the development of tumor resistance are the main obstacles to successful cancer chemotherapy and hence, its clinical application is limited. The use of resveratrol can increase 5-FU-induced cytotoxicity and mitigate the unwanted adverse effects. This study aimed to review the potential therapeutic effects of resveratrol in combination with 5-FU against colorectal cancer.

METHODS

According to the PRISMA guideline, a comprehensive systematic search was carried out for the identification of relevant literature in four electronic databases of PubMed, Web of Science, Embase, and Scopus up to May 2021 using a pre-defined set of keywords in their titles and abstracts. We screened 282 studies in accordance with our inclusion and exclusion criteria. Thirteen articles were finally included in this systematic review.

RESULTS

The in vitro findings showed that proliferation inhibition of colorectal cancer cells in the groups treated by 5-FU was remarkably higher than the untreated groups and the co-administration of resveratrol remarkably increased cytotoxicity induced by 5-FU. The in vivo results demonstrated a decrease in tumor growth of mice treated by 5-FU than the untreated group and a dramatic decrease was observed following combined treatment of resveratrol and 5-FU. It was also found that 5-FU alone and combined with resveratrol could regulate the cell cycle profile of colorectal cancer cells. Moreover, this chemotherapeutic agent induced the biochemical and histopathological changes in the cancerous cells/tissues and these alterations were synergized by resveratrol co-administration (for most of the cases), except for the inflammatory mediators.

CONCLUSION

The results obtained from this systematic review demonstrated that co-administration of resveratrol could sensitize the colorectal cancer cells to 5-FU treatment via various mechanisms, including regulation of cell cycle distribution, oxidant, apoptosis, anti-inflammatory effects.

Mechanism, Prevention, and Treatment of Radiation-Induced Salivary Gland Injury Related to Oxidative Stress

Radiation therapy is a common treatment for head and neck cancers. However, because of the presence of nerve structures (brain stem, spinal cord, and brachial plexus), salivary glands (SGs), mucous membranes, and swallowing muscles in the head and neck regions, radiotherapy inevitably causes damage to these normal tissues. Among them, SG injury is a serious adverse event, and its clinical manifestations include changes in taste, difficulty chewing and swallowing, oral infections, and dental caries. These clinical symptoms seriously reduce a patient’s quality of life. Therefore, it is important to clarify the mechanism of SG injury caused by radiotherapy. Although the mechanism of radiation-induced SG injury has not yet been determined, recent studies have shown that the mechanisms of calcium signaling, microvascular injury, cellular senescence, and apoptosis are closely related to oxidative stress. In this article, we review the mechanism by which radiotherapy causes oxidative stress and damages the SGs. In addition, we discuss effective methods to prevent and treat radiation-induced SG damage.

Synergistic Tumoricidal Effects of Alpha-Lipoic Acid and Radiotherapy on Human Breast Cancer Cells via HMGB1

PURPOSE

Radiotherapy (RT) is one of main strategies of cancer treatment. However, some cancer cells are resistant to radiation-induced cell death, including apoptosis. Therefore, alternative approaches targeting different anti-tumor mechanisms such as cell senescence are required. This study aimed to investigate the synergistic effect of alpha-lipoic acid (ALA) on radiation-induced cell death and senescence in MDA-MB-231 human breast cancer cells.

MATERIALS AND METHODS

The cells were divided into four groups depending on the cell treatment (control, ALA, RT, and ALA+RT). Cells were analyzed for morphology, apoptotic cell death, mitochondrial reactive oxygen species, membrane potential, cellular senescence, and cell cycle.

RESULTS

Our data showed that ALA significantly promoted apoptotic cell death when combined with RT, as reflected by Annexin V staining, expression of apoptosis-related factors, mitochondrial damages as well as cell morphological changes and reduction of cell numbers. In addition, ALA significantly enhanced radiation-induced cellular senescence, which was shown by increased HMGB1 expression in the cytosol fraction compared to the control, increased p53 expression compared to the control, activation of p38 as well as nuclear factor кB, and G2/M cell cycle arrest.

CONCLUSION

The current study is the first report showing a new mode of action (senescence induction) of ALA beyond apoptotic cell death in MDA-MB-231 cancer cells known to be resistant to RT.

The radioprotective effects of alpha-lipoic acid on radiotherapy-induced toxicities: A systematic review

PURPOSE

Radiation therapy is one of the main cancer treatment modalities applied in 50-70% of cancer patients. Despite the many advantages of this treatment, such as non-invasiveness, organ-preservation, and spatiotemporal flexibility in tumor targeting, it can lead to complications in irradiated healthy cells/tissues. In this regard, the use of radio-protective agents can alleviate radiation-induced complications. This study aimed to review the potential role of alpha-lipoic acid in the prevention/reduction of radiation-induced toxicities on healthy cells/tissues.

METHODS

A systematic search was performed following PRISMA guidelines to identify relevant literature on the "role of alpha-lipoic acid in the treatment of radiotherapy-induced toxicity" in the electronic databases of Web of Science, Embase, PubMed, and Scopus up to January 2021. Based on the inclusion and exclusion criteria of the present study, 278 articles were screened. Finally, 29 articles were included in this systematic review.

RESULTS

The obtained results showed that in experimental in vivo models, the radiation-treated groups had decreased survival rate and body weight compared to the control groups. It was also found that radiation can induce mild to severe toxicities on gastrointestinal, circulatory, reproductive, central nervous, respiratory, endocrine, exocrine systems, etc. However, the use of alpha-lipoic acid could alleviate the radiation-induced toxicities in most cases. This radio-protective agent exerts its effects through mechanisms of anti-oxidant, anti-apoptosis, anti-inflammatory, and so on.

CONCLUSION

According to the obtained results, it can be mentioned that co-treatment of alpha-lipoic acid with radiotherapy ameliorates the radiation-induced toxicities in healthy cells/tissues.

Mitigation of Radiation-induced Pneumonitis and Lung Fibrosis using Alpha-lipoic Acid and Resveratrol

BACKGROUND

Lung is a radiosensitive organ. Studies have shown that exposure of the lung to acute and high doses of radiation following inhalation of radioactive agents or an accidental radiological event may lead to pneumonitis and fibrosis, which are associated with a risk of death. So far, some agents have been studied for mitigation of pneumonitis and fibrosis following exposure of murine lung tissues to ionizing radiation. In this study, we aimed to detect the possible mitigatory effect of alpha-lipoic acid, resveratrol and their combination on mice pneumonitis and fibrosis markers following irradiation.

METHODS

25 mice were divided into 5 groups: control, radiation; radiation plus alpha-lipoic acid; radiation plus resveratrol; and radiation plus both resveratrol and alpha-lipoic acid. Mice chest regions were irradiated with 18 Gy using a cobalt-60 gamma rays source. Treatments started 24 h after irradiation and continued for two weeks. After 100 days, all mice were sacrificed and their lung tissues removed for histopathological evaluation.

RESULTS

Pathological study showed that exposure to radiation led to severe pneumonitis and moderate fibrosis after 100 days. Both resveratrol and alpha-lipoic acid, as well as their combination could mitigate pneumonitis and fibrosis markers. Although, resveratrol could not mitigate infiltration of most inflammatory cells as well as inflammation and vascular damage, alpha-lipoic acid and its combination were able to mitigate most damaged markers.

CONCLUSION

Alpha-lipoic acid and its combination with resveratrol were able to mitigate fibrosis and pneumonitis markers in mice lung tissues following lung irradiation. Although resveratrol has a protective effect on some markers, it has a weaker effect on lung injury. In conclusion, our results suggest that the combination of resveratrol and alpha-lipoic acid has a potent mitigatory effect compared to the single forms of these agents.

The Alpha-Lipoic Acid Improves Survival and Prevents Irinotecan-Induced Inflammation and Intestinal Dysmotility in Mice

Irinotecan, an anticancer drug, induces diarrhea and intestinal inflammation, resulting in an increase in the cost of care and in treatment delays. In this study, we investigated whether alpha-lipoic acid (α-LA) could improve irinotecan-mediated intestinal inflammation, diarrhea and dysmotility. Intestinal mucositis was induced by irinotecan injection (75 mg/kg, i.p., for 4 days) in Swiss mice. α-LA (50, 100 or 200 mg/kg, gavage) was administered daily 1 h before the injection of irinotecan. Duodenum tissues were obtained for inflammation and proliferation analysis. The outcomes: diarrhea, intestinal dysmotility, weight body loss and survival were evaluated. Compared with the control condition, irinotecan diminished (p < 0.05) intestinal villus height, caused a loss of crypt integrity and intense inflammatory cell infiltration, increased myeloperoxidase (MPO), IL-6 and IL-1β levels and decreased reduced glutathione (GSH) levels in duodenum segments and increased gastric retention and decreased liquid retention in the medial intestinal segment, resulting in increased intestinal transit, severe diarrhea and reduced survival (approximately 72%). Furthermore, α-LA (200 mg/kg) pretreatment ameliorated (p < 0.05) these irinotecan-induced effects. Our findings show that α-LA reduced irinotecan-induced inflammation, intestinal dysmotility and diarrhea, resulting in improved survival. α-LA may be a useful therapeutic agent for the treatment of gut dysmotility in patients with intestinal mucositis associated with irinotecan treatment.

Ionizing radiation induces BH4 deficiency by downregulating GTP-cyclohydrolase 1, a novel target for preventing and treating radiation enteritis

Radiation enteritis (RE) is a common side effect after radiotherapy for abdominal cancer. RE pathogenesis is complicated, with no drugs available for prevention or treatments. Intestinal ischemia is a key factor in the occurrence and development of enteritis. The effect of ionizing radiation (IR) on intestinal ischemia is unknown. Deficiency of tetrahydrobiopterin (BH4) produced by GTP-cyclohydrolase 1 (Gch1) is important in ischemic diseases. This study focused on the relationship of Gch1/BH4 between intestinal ischemia in radiation enteritis. BH4 levels were analyzed by high-performance liquid chromatography in humans and rats after radiotherapy. Intestinal blood perfusion was measured by laser doppler flow imaging. Vascular ring tests determined the diastolic functions of rat mesenteric arteries. Gene, protein, and immunohistochemical staining experiments and inhibitor interventions were used to investigate Gch1 and endothelial NOS (eNOS) in rat mesenteric arteries and endothelial cells. The results showed that IR decreased BH4 levels in patients and rats after radiotherapy and decreased intestinal blood perfusion in rats. The degree of change in intestinal ischemia was consistent with intestinal villus injury. Gch1 mRNA and protein levels and nitric oxide (NO) production significantly decreased, while eNOS uncoupling in arterial and vascular endothelial cells strongly increased. BH4 supplementation improved eNOS uncoupling and NO levels in vascular endothelia after IR. The results of this study showed that downregulation of Gch1 in intestinal blood vessels after IR is an important target in RE. BH4 supplementation may prevent intestinal ischemia and improve vascular endothelial function after IR. These findings have clinical significance for the prevention and treatment of RE.

Curcumin Protects Against Radiotherapy-Induced Oxidative Injury to the Skin

Objective

Side-effects to normal tissues reduce the therapeutic window of radiotherapy. During radiotherapy, the skin is inevitably exposed to doses of ionizing radiation, leading to varying degrees of skin damage. Natural antioxidants have been explored for their radioprotective potentials. Thus, the present study aimed to investigate the protective effect of curcumin against radiotherapy-induced oxidative damage to the skin.

Methods

Forty rats were divided into four groups as follows: vehicle control (without irradiation or drug treatment), treatment with 150 mg/kg curcumin, 10 Gy single dose irradiation only, and 150 mg/kg curcumin plus 10 Gy radiation (RC). In the treatment groups, each rat was treated orally with 150 mg/kg curcumin 1 day before irradiation to 3 consecutive days after irradiation. Weeks 1, 2, or 4 after irradiation, all rats were sacrificed and their skin tissues collected and frozen at −80°C for the determination of malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activity in skin tissues.

Results

Radiotherapy-induced oxidative injury to the skin was evidenced by elevated MDA levels as well as depleted CAT, SOD, and GSH-Px activities. However, the administration of curcumin before and after irradiation prevented radiotherapy-induced oxidative damage by significantly elevating the activities of antioxidant enzymes.

Conclusion

From the findings of the present study, curcumin showed potential for protection against radiotherapy-induced oxidative injury to the skin. However, future studies are required to evaluate its clinical efficacy.

Alpha-lipoic acid effectively attenuates ionizing radiation-mediated testicular dysfunction in rats: Crosstalk of NF-ĸB, TGF-β, and PPAR-ϒ pathways

Radiotherapy is one of the principal approaches employed in the treatment of pelvic cancers. Nevertheless, testicular dysfunction and infertility are among the most common adverse effects in young adult cancer survivors. Clinically, alpha-lipoic acid (LA) has been applied to improve the quality of sperm with a satisfactory effect. Therefore, the present study investigated the underlying mechanisms of the radioprotective effects of LA against testicular damage. Male Sprague-Dawley rats were exposed to 10 Gy of whole-body ϒ-radiation and LA (50 mg/kg, P.O.) was administered one week before and three days post-irradiation. LA showed remarkable capacity in preserving testicular tissue against radiation damage by improving histological and ultrastructural changes of disorganized seminiferous tubules, besides enhancing its diameter, germinal epithelial thickness, and Johnsen's score. Radiation instigated a significant decrease in sperm quality and quantity associated with depletion of serum testosterone levels, while the LA administration maintained spermatogenesis. Strikingly, LA exhibited antioxidant properties by restoring reduced glutathione levels and antioxidant enzyme activities such as catalase and glutathione-s-transferase, besides diminishing malondialdehyde levels in the testis of irradiated group. Furthermore, LA alleviated testicular inflammation through downregulation of nuclear factor-ĸB (NF-ĸB) expression with a subsequent reduction in interleukin (IL)-6 and cyclooxygenase-2 expression, accompanied by the augmented expression of the anti-inflammatory cytokine IL-10. Additionally, testicular fibrosis markers including Masson's trichrome and transforming growth factor (TGF)-β expression were noticeably declined in LA-treated irradiated rats, together with the upregulation of peroxisome proliferator-activated receptor-ϒ expression. Collectively, LA ameliorates radiation-mediated spermatogenesis-defects and testicular-damage via suppression of oxidative stress/NF-ĸB/TGF-β signaling.

Protective Effect of Alpha-Lipoic Acid on Salivary Dysfunction in a Mouse Model of Radioiodine Therapy-Induced Sialoadenitis

Radioiodine (RI) therapy is known to cause salivary gland (SG) dysfunction. The effects of antioxidants on RI-induced SG damage have not been well described. This study was performed to investigate the radioprotective effects of alpha lipoic acid (ALA) administered prior to RI therapy in a mouse model of RI-induced sialadenitis. Four-week-old female C57BL/6 mice were divided into four groups (n = 10 per group): group I, normal control; group II, ALA alone (100 mg/kg); group III, RI alone (0.01 mCi/g body weight, orally); and group IV, ALA + RI (ALA at 100 mg/kg, 24 h and 30 min before RI exposure at 0.01 mCi/g body weight). The animals in these groups were divided into two subgroups and euthanized at 30 or 90 days post-RI treatment. Changes in salivary ^99mTc pertechnetate uptake and excretion were tracked by single-photon emission computed tomography. Salivary histological examinations and TUNEL assays were performed. The ^99mTc pertechnetate excretion level recovered in the ALA treatment group. Salivary epithelial (aquaporin 5) cells of the ALA + RI group were protected from RI damage. The ALA + RI group exhibited more mucin-containing parenchyma and less fibrotic tissues than the RI only group. Fewer apoptotic cells were observed in the ALA + RI group compared to the RI only group. Pretreatment with ALA before RI therapy is potentially beneficial in protecting against RI-induced salivary dysfunction.

Protective Effect of Metformin, Resveratrol and Alpha-lipoic Acid on Radiation- Induced Pneumonitis and Fibrosis: A Histopathological Study

BACKGROUND

Radiation-induced pneumonitis and fibrosis are the most common side effects of chest radiotherapy. They result from massive and chronic production of Reactive Oxygen Species (ROS), inhibition of antioxidant enzymes as well as the release of several inflammatory mediators. In this study, we aimed to detect the radioprotective effects of metformin (as inhibitor of mitochondrial ROS), resveratrol (as stimulator of antioxidant defense enzymes) and alpha-lipoic acid (as direct antioxidant) for alleviating radiation-induced pneumonitis and fibrosis.

METHODS

80 Male Mice were randomly allotted to eight groups which include G1: control; G2: resveratrol; G3: alpha-lipoic acid; G4: metformin; G5: radiation; G6: radiation plus resveratrol; G7: radiation plus alpha-lipoic acid; G8: radiation plus metformin. Drugs' doses were as follows: 100 mg/kg metformin, 200 mg/kg resveratrol and 200 mg/kg alpha-lipoic acid. Irradiation with a single radiation dose of 18 Gy was performed using a cobalt-60 (60Co) gamma-ray source. After 80 days, all mice were sacrificed and their lung tissues evaluated for morphological changes using histopathological markers.

RESULTS

Irradiation led to acute pneumonitis including infiltration of inflammatory cells and damages to alveolar and vascular, as well as mild fibrosis. Metformin, alpha-lipoic acid and resveratrol were able to reduce pneumonitis and overcome radiation-induced fibrosis.

CONCLUSION

All agents could protect against radiation-induced lung injury moderately. It is possible that administering higher doses of these drugs over a long period of time could give better radioprotection of the lung.

Changes in miRNA expressions in the injured small intestine of mice following high‑dose radiation exposure

The small intestine is one of the most highly regenerative and radiosensitive tissues in mammals, including humans. Exposure to high doses of ionizing radiation causes serious intestinal damage. Recently, several investigations have been conducted using radioprotective agents to determine ways for reducing intestinal damage caused by radiation exposure. However, a thorough understanding of functional changes occurring in the small intestine of mice exposed to high-dose radiation is necessary for developing novel and more potent radioprotective agents. In this study, we examined changes in microRNA (miRNA/miR) expressions in the small intestine of mice at 72 h after X-ray exposure (10 Gy). We identified seven upregulated miRNAs and six downregulated miRNAs in the small intestine of mice following radiation exposure using miRNA microarray analysis. Particularly, miR-34a-5p was highly expressed, which was confirmed by reverse transcription-quantitative PCR. Forkhead box P1 (Foxp1) was predicted to be a target of the mRNA of miR-34a-5p using OmicsNet. Decreased Foxp1 expression in the small intestine following radiation exposure was confirmed, suggesting that Foxp1 expression recovery may induce the suppression of radiation-induced enteritis. Therefore, miR-34a-5p is a potential target molecule for developing novel radioprotective agents.

Alpha-Lipoic Acid Ameliorates Radiation-Induced Salivary Gland Injury by Preserving Parasympathetic Innervation in Rats

Radiation therapy is a standard treatment for patients with head and neck cancer. However, radiation exposure to the head and neck induces salivary gland (SG) dysfunction. Alpha lipoic acid (ALA) has been reported to reduce radiation-induced toxicity in normal tissues. In this study, we investigated the effect of ALA on radiation-induced SG dysfunction. Male Sprague-Dawley rats were assigned to the following treatment groups: control, ALA only (100 mg/kg, intraperitoneally), irradiation only, and ALA administration 24 h or 30 min prior to irradiation. The neck area, including SGs, was irradiated evenly at 2 Gy/min (total dose, 18 Gy) using a photon 6 MV linear accelerator. The rats were sacrificed at 2, 6, 8, and 12 weeks after irradiation. Radiation decreased SG weight, saliva secretion, AQP5 expression, parasympathetic innervation (GFRα2 and AchE expression), regeneration potentials (Shh and Ptch expression), salivary trophic factor levels (brain-derived neurotrophic factor and neurturin), and stem cell expression (Sca-1). These features were restored by treatment with ALA. This study demonstrated that ALA can rescue radiation-induced hyposalivation by preserving parasympathetic innervation and regenerative potentials.

Radioprotective effect of self-assembled low molecular weight Fucoidan-Chitosan nanoparticles

Fucoidan, a sulphated polysaccharide, plays a vital role in reducing cellular oxidative damage by exerting potential antioxidant activity. However, because of the negative surface charges of oligofucoidan, it shows poor oral intestinal absorption. To overcome this drawback, the oligofucoidan polysaccharides self-assembled with opposite charge based polysaccharides (chitosan) to form the chitosan-fucoidan polysaccharides (C₁-F₃P) nanoparticles (NPs) of 190-230 nm in size. The oligofucoidan and C₁-F₃P NPs were studied for their radioprotective property using mice exposed to 5 Gy radiation. The C₁-F₃P NPs prevents radiation induced lipid peroxidation and restores intestinal enzymatic and non-enzymatic antioxidants (p < 0.05) status. In addition, hematoxylin-eosin staining revealed the radioprotective effect of oligofucoidan and C₁-F₃P NPs by mitigating the loss of crypt and villi in the small intestine. Thus, the present study demonstrated that C₁-F₃P NPs can be considered as a radioprotective agent that can be used for the prevention and treatment of Gy-radiation-induced intestine injury.

Mitigation of Radiation-induced Gastrointestinal System Injury using Resveratrol or Alpha-lipoic Acid: A Pilot Histopathological Study

AIM

In this study, we aimed to determine possible mitigation of radiationinduced toxicities in the duodenum, jejunum and colon using post-exposure treatment with resveratrol and alpha-lipoic acid.

BACKGROUND

After the bone marrow, gastrointestinal system toxicity is the second critical cause of death following whole-body exposure to radiation. Its side effects reduce the quality of life of patients who have undergone radiotherapy. Resveratrol has an antioxidant effect and stimulates DNA damage responses (DDRs). Alpha-lipoic acid neutralizes free radicals via the recycling of ascorbic acid and alpha-tocopherol.

OBJECTIVE

This study is a pilot investigation of the mitigation of enteritis using resveratrol and alpha-lipoic acid following histopathological study.

METHODS

60 male mice were randomly assigned to six groups; control, resveratrol treatment, alpha-lipoic acid treatment, whole-body irradiation, irradiation plus resveratrol, and irradiation plus alpha-lipoic acid. The mice were irradiated with a single dose of 7 Gy from a cobalt-60 gamma-ray source. Treatment with resveratrol or alpha-lipoic acid started 24 h after irradiation and continued for 4 weeks. All mice were sacrificed after 30 days for histopathological evaluation of radiation-induced toxicities in the duodenum, jejunum and colon.

RESULTS AND DISCUSSION

Exposure to radiation caused mild to severe damages to vessels, goblet cells and villous. It also led to significant infiltration of macrophages and leukocytes, especially in the colon. Both resveratrol and alpha-lipoic acid were able to mitigate morphological changes. However, they could not mitigate vascular injury.

CONCLUSION

Resveratrol and alpha-lipoic acid could mitigate radiation-induced injuries in the small and large intestine. A comparison between these agents showed that resveratrol may be a more effective mitigator compared to alpha-lipoic acid.

Radiation-induced intestinal damage: latest molecular and clinical developments

Aim: To systematically review the prophylactic and therapeutic interventions for reducing the incidence or severity of intestinal symptoms among cancer patients receiving radiotherapy. Materials & methods: A literature search was conducted in the PubMed database using various search terms, including 'radiation enteritis', 'radiation enteropathy', 'radiation-induced intestinal disease', 'radiation-induced intestinal damage' and 'radiation mucositis'. The search was limited to in vivo studies, clinical trials and meta-analyses published in English with no limitation on publication date. Other relevant literature was identified based on the reference lists of selected studies. Results: The pathogenesis of acute and chronic radiation-induced intestinal damage as well as the prevention and treatment approaches were reviewed. Conclusion: There is inadequate evidence to strongly support the use of a particular strategy to reduce radiation-induced intestinal damage. More high-quality randomized controlled trials are required for interventions with limited evidence suggestive of potential benefits.

Alpha-Lipoic Acid Ameliorates Radiation-Induced Lacrimal Gland Injury through NFAT5-Dependent Signaling

Dry eye syndrome related to radiation therapy is relatively common and can severely impair a patient’s daily life. The nuclear factor of activated T cells 5(NFAT5) is well known for its osmoprotective effect under hyperosmolar conditions, and it also has immune-modulating functions. We investigated the role of NFAT5 and the protective effect of α-lipoic acid(ALA) on radiation-induced lacrimal gland (LG) injuries. Rats were assigned to control, ALA only, radiation only, and ALA administered prior to irradiation groups. The head and neck area, including the LG, was evenly irradiated with 2 Gy/minute using a photon 6-MV linear accelerator. NFAT5 expression was enhanced and localized in the LG tissue after irradiation and was related to cellular apoptosis. ALA had a protective effect on radiation-induced LG injury through the inhibition of NFAT5 expression and NFAT5-dependent signaling pathways. Functional radiation–induced damage of the LG and cornea was also restored with ALA treatment. NFAT5 expression and its dependent signaling pathways were deeply related to radiation-induced dry eye, and the condition was improved by ALA treatment. Our results suggest a potential role of NFAT5 and NF-κB in the proinflammatory effect in LGs and cornea, which offers a target for new therapies to treat dry eye syndrome.

Promising role of filgrastim and α-tocopherol succinate in amelioration of gastrointestinal acute radiation syndrome (GI-ARS) in mice

The protective role of α-tocopherol succinate (α-TCS) and the therapeutic efficacy of filgrastim were investigated in gastrointestinal acute radiation syndrome (GI-ARS) induced following 10 Gy whole-body γ-irradiation. Mice were randomly allocated into 5 groups: [1] normal-control, [2] irradiated-control, [3] subcutaneous (s.c.) injection of filgrastim (5 μg/kg/day) for 4 consecutive days given 1 h post-irradiation, [4] s.c. injection with α-TCS (400 mg/kg) 1 day prior to irradiation, [5] s.c. injection with α-TCS (400 mg/kg) 1 day prior to irradiation and filgrastim (5 μg/kg/day) for 4 consecutive days 1 h post-irradiation. Histopathological analysis, serum citrulline level, intestinal interleukin-1β (IL-1β), reduced glutathione (GSH), and malondialdehyde (MDA) contents as well as myeloperoxidase (MPO) activity were measured. Intestinal caspase-3, p53, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) immunopositivity were examined. In irradiated-control, MDA increased (249%) and GSH decreased (25%) compared to normal and were unaffected by filgrastim. α-TCS alone significantly reduced MDA (84.5%) and normalized GSH. The combination significantly reduced MDA (59%) and dramatically increased GSH (1573%), pointing to a possible synergistic action. In irradiated-control, MPO and IL-1β significantly increased (111% and 613%, respectively) compared to normal-control and both were significantly decreased in all treated groups. Compared to normal-control, citrulline significantly declined (68%) in irradiated-control; a significant elevation was achieved by treatments with α-TCS alone or combined with filgrastim (88% and 94%, respectively). The combination therapy significantly decreased the degree of irradiation-induced injury of the epithelium and cellular infiltration and showed the lowest histopathological scoring compared to the other groups (p ≤ 0.05). In irradiated-control, immune-reactive expressions of iNOS, COX-2, caspase-3, and p53 were remarkable (18.62%, 34.27%, 31.19%, and 27.44%, respectively) and after combination therapy were reduced (1.04%, 22.39%, 8.76%, and 4.91%, respectively). The current findings represent a first-hand strategy in dealing with GI-ARS with a potential preference to using a combined therapy of filgrastim and α-TCS.

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.

Reactive Oxygen Species Drive Epigenetic Changes in Radiation-Induced Fibrosis

Radiation-induced fibrosis (RIF) develops months to years after initial radiation exposure. RIF occurs when normal fibroblasts differentiate into myofibroblasts and lay down aberrant amounts of extracellular matrix proteins. One of the main drivers for developing RIF is reactive oxygen species (ROS) generated immediately after radiation exposure. Generation of ROS is known to induce epigenetic changes and cause differentiation of fibroblasts to myofibroblasts. Several antioxidant compounds have been shown to prevent radiation-induced epigenetic changes and the development of RIF. Therefore, reviewing the ROS-linked epigenetic changes in irradiated fibroblast cells is essential to understand the development and prevention of RIF.

Pravastatin Attenuates Acute Radiation-Induced Enteropathy and Improves Epithelial Cell Function

Background and Aim: Radiation-induced enteropathy is frequently observed after radiation therapy for abdominal and pelvic cancer or occurs secondary to accidental radiation exposure. The acute effects of irradiation on the intestine might be attributed to inhibition of mitosis in the crypts, as the loss of proliferative functions impairs development of the small intestinal epithelium and its barrier function. Especially, oxidative damage to intestinal epithelial cells is a key event in the initiation and progression of radiation-induced enteropathy. Pravastatin is widely used clinically to lower serum cholesterol levels and has been reported to have anti-inflammatory effects on endothelial cells. Here, we investigated the therapeutic effects of pravastatin on damaged epithelial cells after radiation-induced enteritis using in vitro and in vivo systems. Materials and Methods: To evaluate the effects of pravastatin on intestinal epithelial cells, we analyzed proliferation and senescence, oxidative damage, and inflammatory cytokine expression in an irradiated human intestinal epithelial cell line (InEpC). In addition, to investigate the therapeutic effects of pravastatin in mice, we performed histological analysis, bacterial translocation assays, and intestinal permeability assays, and also assessed inflammatory cytokine expression, using a radiation-induced enteropathy model. Results: Histological damage such as shortening of villi length and impaired intestinal crypt function was observed in whole abdominal-irradiated mice. However, damage was attenuated in pravastatin-treated animals, in which normalization of intestinal epithelial cell differentiation was also observed. Using in vitro and in vivo systems, we also showed that pravastatin improves the proliferative properties of intestinal epithelial cells and decreases radiation-induced oxidative damage to the intestine. In addition, pravastatin inhibited levels of epithelial-derived inflammatory cytokines including IL-6, IL-1β, and TNF-α in irradiated InEpC cells. We also determined that pravastatin could rescue intestinal barrier dysfunction via anti-inflammatory effects using the mouse model. Conclusion: Pravastatin has a therapeutic effect on intestinal lesions and attenuates radiation-induced epithelial damage by suppressing oxidative stress and the inflammatory response.

Alpha lipoic acid attenuates radiation-induced oral mucositis in rats

PURPOSE

Radiotherapy is currently one of the main treatment modalities for head and neck cancer; however, it also results in severe toxicity to the normal tissue, to the detriment of patients. This study aimed to investigate whether alpha lipoic acid (ALA) could protect against radiation-induced oral mucositis in a rat model.

RESULTS

On post-irradiation days 4 and 7, the epithelial layer on oral mucosa showed pronounced injury (shortening of the layer) and it is diminished by ALA pretreatment before radiation. Hif-1a expression was significantly induced in the radiation group on days 4, 7, and 28. GLUT1 expression was also induced by radiation at all time points, and the expression levels peaked on day 28. Phosphorylated p53 level was significantly higher in the radiation group on days 4 and 7, and Bax protein expression was significantly higher in the same group on day 4 than ALA-pretreated radiation group. TUNEL-positive staining was significantly lower in the ALA-pretreated radiation group.

MATERIALS AND METHODS

Rats were assigned to one of the following four groups: control, ALA only (100 mg/kg, i.p.), irradiated, and ALA administered 24 h and 30 min prior to irradiation, with the neck area including the oral mucosa evenly irradiated with 2 Gy per minute (total dose, 18 Gy) using a photon 6-MV linear accelerator. Rats were sacrificed 4, 7, 28, or 56 days after radiation.

CONCLUSIONS

The results show that ALA can be used to ameliorate radiation-induced oral mucositis with head and neck cancer.

Pharmacological Modulation of Radiation Damage. Does It Exist a Chance for Other Substances than Hematopoietic Growth Factors and Cytokines?

In recent times, cytokines and hematopoietic growth factors have been at the center of attention for many researchers trying to establish pharmacological therapeutic procedures for the treatment of radiation accident victims. Two granulocyte colony-stimulating factor-based radiation countermeasures have been approved for the treatment of the hematopoietic acute radiation syndrome. However, at the same time, many different substances with varying effects have been tested in animal studies as potential radioprotectors and mitigators of radiation damage. A wide spectrum of these substances has been studied, comprising various immunomodulators, prostaglandins, inhibitors of prostaglandin synthesis, agonists of adenosine cell receptors, herbal extracts, flavonoids, vitamins, and others. These agents are often effective, relatively non-toxic, and cheap. This review summarizes the results of animal experiments, which show the potential for some of these untraditional or new radiation countermeasures to become a part of therapeutic procedures applicable in patients with the acute radiation syndrome. The authors consider β-glucan, 5-AED (5-androstenediol), meloxicam, γ-tocotrienol, genistein, IB-MECA (N⁶-(3-iodobezyl)adenosine-5'-N-methyluronamide), Ex-RAD (4-carboxystyryl-4-chlorobenzylsulfone), and entolimod the most promising agents, with regards to their contingent use in clinical practice.

A DPP-IV-resistant glucagon-like peptide-2 dimer with enhanced activity against radiation-induced intestinal injury

Although radiotherapy is a highly effective treatment for abdominal or pelvic cancer patients, it can increase the incidence of severe gastrointestinal (GI) toxicity. As an intestinal growth factor, glucagon-like peptide 2 (GLP-2) has been shown to improve the preclinical models of both short bowel syndrome and inflammatory bowel disease by stimulating intestinal growth. Teduglutide ([Gly²]GLP-2), a recombinant human GLP-2 variant, has a prolonged half-life and stability as compared to the native GLP-2 peptide, but still requires daily application in the clinic. Here, we designed and prepared a new degradation-resistant GLP-2 analogue dimer, designated GLP-2②, with biotechnological techniques. The purity of GLP-2②reached 97% after ammonium sulphate precipitation and anion exchange chromatography purification, and the purification process was simple and cost-effective. We next confirmed that the GLP-2② exhibited enhanced activities compared with [Gly²]GLP-2, the long-acting, degradation-resistant analogue. Notably, GLP-2② offers a pharmacokinetic and therapeutic advantage in the treatment of radiation-induced intestinal injury over [Gly²]GLP-2. We further demonstrated that GLP-2② rapidly activates divergent intracellular signaling pathways involved in cell survival and apoptosis. Taken together, our data revealed a potential novel and safe peptide drug for limiting the adverse effect of radiotherapy on the gastrointestinal system.

Novel concepts in radiation-induced cardiovascular disease

Radiation-induced cardiovascular disease (RICVD) is the most common nonmalignant cause of morbidity and mortality among cancer survivors who have undergone mediastinal radiation therapy (RT). Cardiovascular complications include effusive or constrictive pericarditis, cardiomyopathy, valvular heart disease, and coronary/vascular disease. These are pathophysiologically distinct disease entities whose prevalence varies depending on the timing and extent of radiation exposure to the heart and great vessels. Although refinements in RT dosimetry and shielding will inevitably limit future cases of RICVD, the increasing number of long-term cancer survivors, including those treated with older higher-dose RT regimens, will ensure a steady flow of afflicted patients for the foreseeable future. Thus, there is a pressing need for enhanced understanding of the disease mechanisms, and improved detection methods and treatment strategies. Newly characterized mechanisms responsible for the establishment of chronic fibrosis, such as oxidative stress, inflammation and epigenetic modifications, are discussed and linked to potential treatments currently under study. Novel imaging modalities may serve as powerful screening tools in RICVD, and recent research and expert opinion advocating their use is introduced. Data arguing for the aggressive use of percutaneous interventions, such as transcutaneous valve replacement and drug-eluting stents, are examined and considered in the context of prior therapeutic approaches. RICVD and its treatment options are the subject of a rich and dynamic body of research, and patients who are at risk or suffering from this disease will benefit from the care of physicians with specialty expertise in the emerging field of cardio-oncology.