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

The Radiosensitizing Potentials of Silymarin/Silibinin in Cancer: A Systematic Review

INTRODUCTION

Although radiotherapy is one of the main cancer treatment modalities, exposing healthy organs/tissues to ionizing radiation during treatment and tumor resistance to ionizing radiation are the chief challenges of radiotherapy that can lead to different adverse effects. It was shown that the combined treatment of radiotherapy and natural bioactive compounds (such as silymarin/silibinin) can alleviate the ionizing radiation-induced adverse side effects and induce synergies between these therapeutic modalities. In the present review, the potential radiosensitization effects of silymarin/silibinin during cancer radiation exposure/radiotherapy were studied.

METHODS

According to the PRISMA guideline, a systematic search was performed for the identification of relevant studies in different electronic databases of Google Scholar, PubMed, Web of Science, and Scopus up to October 2022. We screened 843 articles in accordance with a predefined set of inclusion and exclusion criteria. Seven studies were finally included in this systematic review.

RESULTS

Compared to the control group, the cell survival/proliferation of cancer cells treated with ionizing radiation was considerably less, and silymarin/silibinin administration synergistically increased ionizing radiation-induced cytotoxicity. Furthermore, there was a decrease in the tumor volume, weight, and growth of ionizing radiation-treated mice as compared to the untreated groups, and these diminutions were predominant in those treated with radiotherapy plus silymarin/ silibinin. Furthermore, the irradiation led to a set of biochemical and histopathological changes in tumoral cells/tissues, and the ionizing radiation-induced alterations were synergized following silymarin/silibinin administration (in most cases).

CONCLUSION

In most cases, silymarin/silibinin administration could sensitize the cancer cells to ionizing radiation through an increase of free radical formation, induction of DNA damage, increase of apoptosis, inhibition of angiogenesis and metastasis, etc. However, suggesting the use of silymarin/silibinin during radiotherapeutic treatment of cancer patients requires further clinical studies.

The Anti-hypoxia Potentials of Trans-sodium Crocetinate in Hypoxiarelated Diseases: A Review

Crocetin is a kind of apocarotenoid carboxylic acid extracted from saffron (Crocus sativus L.), which is effective in upregulating tissue oxygenation. However, crocetin is difficult to solubilize. It was shown that the trans isomer of crocetin is effective in improving oxygen diffusivity, while its cis isomer appears not to be. Hence, the isolated trans isomer of crocetin or trans-sodium crocetinate (TSC) can be used instead of crocetin. It is shown that TSC can upregulate hypoxic tissue oxygenation and be effective in treating some hypoxia-related diseases. Moreover, experimental and clinical studies have reported no adverse effects following TSC treatment, even at high doses. The current study will discuss the potential role of TSC in hemorrhagic shock, ischemia, brain tumor radiotherapy, and others.

The Chemoprotective Potentials of Alpha-lipoic Acid against Cisplatin-induced Ototoxicity: A Systematic Review

PURPOSE

Ototoxicity is one of the major adverse effects of cisplatin therapy which restrict its clinical application. Alpha-lipoic acid administration may mitigate cisplatin-induced ototoxicity. In the present study, we reviewed the protective potentials of alpha-lipoic acid against the cisplatin-mediated ototoxic adverse effects.

METHODS

Based on the PRISMA guideline, we performed a systematic search for the identification of all relevant studies in various electronic databases up to June 2022. According to the inclusion and exclusion criteria, the obtained articles (n=59) were screened and 13 eligible articles were finally included in the present study.

RESULTS

The findings of in-vitro experiments showed that cisplatin treatment significantly reduced the auditory cell viability in comparison with the control group; nevertheless, the alpha-lipoic acid co-administration protected the cells against the reduction of cell viability induced by cisplatin treatment. Moreover, the in-vivo results of the auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) tests revealed a decrease in DPOAE and an increase in ABR threshold of cisplatin-injected animals; however, it was shown that alpha-lipoic acid co-treatment had an opposite pattern on the evaluated parameters. Other findings demonstrated that cisplatin treatment could significantly induce the biochemical and histopathological alterations in inner ear cells/tissue; in contrast, alpha-lipoic acid co-treatment ameliorated the cisplatin-mediated biochemical and histological changes.

CONCLUSION

The findings of audiometry, biochemical parameters, and histological evaluation showed that alpha-lipoic acid co-administration alleviates the cisplatin-induced ototoxicity. The protective role of alpha-lipoic acid against the cisplatin-induced ototoxicity can be due to different mechanisms of anti-oxidant, anti-apoptotic, anti-inflammatory activities, and regulation of cell cycle progression.

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.

Modulation of radiation-induced intestinal injury by radioprotective agents: a cellular and molecular perspectives

The gastrointestinal (GI) system has rapidly proliferating and differentiating cells, which make it one of the most radiosensitive organs in the body. Exposure to high dose of ionising radiation (IR) during radiotherapy may generate a variety of reactive oxygen species (ROS) and reactive nitrogen species (RNS) including radicals, cause some side effects such as nausea, vomiting, diarrhoea, pain, ulceration, mal-absorption etc. Irradiation disrupts GI system by damaging proliferating stem cells of the crypts that alters the histology and physiology of intestine. Radiation damage reflects the qualitative and quantitative changes in intestinal epithelial stem cells like enterocytes, enteroendocrine cells, goblet cells and Paneth cells. The damaging effects of radiation to bio-molecules and cellular structures can alter gene signalling cascades and grounds genomic instability, protein modifications, cell senescence and cell death. The signalling pathways of GI tract includes Wnt, BMP, Hedgehog, PTEN/PI3K and Notch plays an important role in self-renewal of intestinal stem cells (ISCs) and maintaining the balance between self-renewal and differentiation of ISCs. Various radiation countermeasures including radioprotectors and mitigators are under development phase globally but still not approved for clinical applications during any radiation emergencies. In view of above, present review highlights cellular and molecular interruptions of GI system due to acute and chronic GI radiation injury, role of radioprotectors in signalling cascade modulations in GI epithelium and involvement of ISC markers in radioprotection.

A Systematic Review of the Chemo/Radioprotective Effects of Melatonin against Ototoxic Adverse Effects Induced by Chemotherapy and Radiotherapy

BACKGROUND

Although chemotherapy and radiotherapy are effective in cancer treatment, different adverse effects induced by these therapeutic modalities (such as ototoxicity) restrict their clinical use. Co-treatment of melatonin may alleviate the chemotherapy/radiotherapy-induced ototoxicity.

OBJECTIVE

In the present study, the otoprotective potentials of melatonin against the ototoxicity induced by chemotherapy and radiotherapy were reviewed.

METHODS

According to the PRISMA guideline, a systematic search was carried out to identify all relevant studies on "the role of melatonin against ototoxic damage associated with chemotherapy and radiotherapy" in the different electronic databases up to September 2022. Sixty-seven articles were screened based on a predefined set of inclusion and exclusion criteria. Seven eligible studies were finally included in this review.

RESULTS

The in vitro findings showed that cisplatin chemotherapy significantly decreased the auditory cell viability compared to the control group; in contrast, the melatonin co-administration increased the cell viability of cisplatin-treated cells. The results obtained from the distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) tests demonstrated a decreased amplitude of DPOAE and increased values of ABR I-IV interval and ABR threshold in mice/rats receiving radiotherapy and cisplatin; nevertheless, melatonin co-treatment indicated an opposite pattern on these evaluated parameters. It was also found that cisplatin and radiotherapy could significantly induce the histological and biochemical changes in the auditory cells/tissue. However, melatonin co-treatment resulted in alleviating the cisplatin/radiotherapy-induced biochemical and histological changes.

CONCLUSION

According to the findings, it was shown that melatonin co-treatment alleviates the ototoxic damage induced by chemotherapy and radiotherapy. Mechanically, melatonin may exert its otoprotective effects via its anti-oxidant, anti-apoptotic, and anti-inflammatory activities and other mechanisms.

Polyphenols as Potential Protectors against Radiation-Induced Adverse Effects in Patients with Thoracic Cancer

Radiotherapy is one of the standard treatment approaches used against thoracic cancers, occasionally combined with chemotherapy, immunotherapy and molecular targeted therapy. However, these cancers are often not highly sensitive to standard of care treatments, making the use of high dose radiotherapy necessary, which is linked with high rates of radiation-induced adverse effects in healthy tissues of the thorax. These tissues remain therefore dose-limiting factors in radiation oncology despite recent technological advances in treatment planning and delivery of irradiation. Polyphenols are metabolites found in plants that have been suggested to improve the therapeutic window by sensitizing the tumor to radiotherapy, while simultaneously protecting normal cells from therapy-induced damage by preventing DNA damage, as well as having anti-oxidant, anti-inflammatory or immunomodulatory properties. This review focuses on the radioprotective effect of polyphenols and the molecular mechanisms underlying these effects in the normal tissue, especially in the lung, heart and esophagus.

Immunoregulation by resveratrol; implications for normal tissue protection and tumour suppression

Immune reactions are involved in both tumour and normal tissue in response to therapy. Elevated secretion of certain chemokines, exosomes and cytokines triggers inflammation, pain, fibrosis and ulceration among other normal tissue side effects. On the other hand, secretion of tumour-promoting molecules suppresses activity of anticancer immune cells and facilitates the proliferation of malignant cells. Novel anticancer drugs such as immune checkpoint inhibitors (ICIs) boost anticancer immunity via inducing the proliferation of anticancer cells such as natural killer (NK) cells and CD8+ T lymphocytes. Certain chemotherapy drugs and radiotherapy may induce anticancer immunity in the tumour, however, both have severe side effects for normal tissues through stimulation of several immune responses. Thus, administration of natural products with low side effects may be a promising approach to modulate the immune system in both tumour and normal organs. Resveratrol is a well-known phenol with diverse effects on normal tissues and tumours. To date, a large number of experiments have confirmed the potential of resveratrol as an anticancer adjuvant. This review focuses on ensuing stimulation or suppression of immune responses in both tumour and normal tissue after radiotherapy or anticancer drugs. Later on, the immunoregulatory effects of resveratrol in both tumour and normal tissue following exposure to anticancer agents will be discussed.

Protective Potentials of Alpha-Lipoic Acid against Ionizing Radiation-Induced Brain Damage in Rats

Background

This study was aimed at determining the effects of alpha-lipoic acid on ionizing irradiation-induced oxidative damage and apoptosis in the brain of rats.

Methods

The animals were exposed to whole-brain X-radiation with a 15 Gy single dose in the absence or presence of alpha-lipoic acid (200 mg/kg body weight) pretreatment for one week. The rats were divided into four groups (5 rats in each group): vehicle control, alpha-lipoic acid alone (ALA), radiation alone (RAD), and radiation plus alpha-lipoic acid (RAD+ALA). In the next stage, malondialdehyde (MDA), nitric oxide, catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) in the brain tissue of the rats were measured. Furthermore, the Western blot analysis technique was performed to assess the NOX2, NOX4, and caspase-3 protein expression levels.

Results

Twenty-four hours after the irradiation, MDA and nitric oxide levels in the irradiated rats were significantly higher than those in the control group (p < 0.001); however, the pretreatment with alpha-lipoic acid resulted in a significant reduction in these stress oxidative markers (p < 0.05). Moreover, a significant decrease in CAT, SOD, and GPx levels was observed in the radiation group alone compared to the control group (p < 0.01); in contrast, the activities of these antioxidant enzymes significantly increased in the radiation plus alpha-lipoic acid group in comparison to the radiation group alone (p < 0.05). The results of Western blot analysis revealed that NOX2, NOX4, and caspase-3 protein expressions significantly elevated in the irradiated rats compared to the control group (p < 0.001). The pretreatment with alpha-lipoic acid could significantly decrease the expression levels of NOX2, NOX4, and caspase-3 in comparison with the radiation group alone (p < 0.05).

Conclusion

According to the obtained findings, it can be mentioned that the alpha-lipoic acid pretreatment could mitigate the ionizing irradiation-induced oxidative damage and apoptosis in the brain of the rats.

Radioprotective Mechanisms of Arbutin: A Systematic Review

PURPOSE

Efforts to produce radioprotective agents of high potential are appropriate strategies for overcoming possible IR toxicity in organisms. The present research aims to evaluate the signaling pathways and mechanisms through which arbutin exerts radioprotective effects on organisms.

METHODS

The databases of PubMed, Web of Sciences, Google Scholar, and Scopus were searched to find studies that reported radioprotective effects for arbutin. Besides, the data were searched within the time period from 2010 to 2020.

RESULTS

Five research articles met our criteria, which were included in the analysis based on their relevance to the topic. The present systematic review provides conclusions about various mechanisms and pathways through which arbutin induces radioprotection.

CONCLUSIONS

Based on the relevant studies, various mechanisms can be proposed for inducing radioprotective effects by arbutin, including inhibition of oxidative stress, apoptosis, and inflammation.

Alpha-Lipoic Acid as a Nutritive Supplement for Humans and Animals: An Overview of Its Use in Dog Food

Simple Summary

A review of human and animal studies involving alpha-lipoic acid supplementation was conducted to determine the utility of alpha-lipoic acid in dog food. The present literature shows that alpha-lipoic acid has utility as a nutritive additive at concentrations of 2.7–4.94 mg/kg body weight/day and improves antioxidant capacity in dogs.

Abstract

Alpha-lipoic acid (a-LA) is used as a nutritive additive in dog food. Therefore, we performed a systematic review of studies published to date in PubMed, Google Scholar, Cochrane Library and MedlinePlus involving alpha-lipoic acid supplementation, which included human clinical trials as well as animal studies, to evaluate its utility as a supplement in foods for healthy, adult dogs. While an upper limit of alpha-lipoic acid intake in humans has not been conclusively determined, the levels for oral intake of a-LA have been better defined in animals, and distinct differences based on species have been described. The maximum tolerated oral dose of a-LA in dogs has been reported as 126 mg/kg body weight and the LD₅₀ as 400 to 500 mg/kg body weight. The antioxidant, anti-inflammatory and neuro-protective benefits of alpha-lipoic acid in dogs were observed at concentrations much lower than the maximum tolerated dose or proposed LD₅₀. At concentrations of 2.7–4.94 mg/kg body weight/day, alpha-lipoic acid is well tolerated and posed no health risks to dogs while providing improved antioxidant capacity. This review thereby supports the utility of alpha-lipoic acid as an effective nutritive additive in dog food.

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.

Protection Against Ionizing Radiation-Induced Normal Tissue Damage by Resveratrol: A Systematic Review

The use of some agents as radioprotectors has been evaluated for protection against normal tissue toxicity following exposure to ionizing radiation. Resveratrol, a natural flavonoid, with antioxidant and anti-inflammatory properties has attracted research interests for its radioprotective potential. This study systematically evaluates existing studies to examine the radioprotective effectiveness of resveratrol. A literature search of the electronic databases, including PubMed, Scopus, and Embase was conducted to retrieve articles investigating the protective effect of resveratrol against ionizing radiation-induced damage to normal tissues. The search timeframe ranged from the inception of each database to January 2020. From an initial search of 231 articles, and after the removal of duplicates as well as applying the predetermined inclusion and exclusion criteria, 33 articles were finally included for this systematic review. Results showed promising protective effect of resveratrol against ionizing radiation-induced damage to normal tissues. Furthermore, no adverse effect was observed after administering resveratrol. Resveratrol showed the potential to protect against ionizing radiation-induced damage to normal tissue cells via notable mechanisms, including anti-apoptotic and anti-inflammatory effects. However, further studies on the efficacy of clinical translation of resveratrol would open up more insights, while other gray areas such as the optimal radioprotective dosage of resveratrol requires further investigation. Overall, resveratrol is a potential double-edged sword in cancer therapy while protecting healthy tissues.

Regulation of the regeneration of intestinal stem cells after irradiation

Background

Radiation enteritis is common in cancer patients with abdominal and pelvic malignant tumors that have received radiotherapy. Regeneration of intestinal stem cells is a critical process for intestine self-repairing post-irradiation. In this study, we attempted to find out the molecules that promote the regeneration of intestinal stem cells to repair the irradiation damage.

Methods

Male C57BL/6 mice were given a single dose of 12 Gy irradiation, and in vitro cultured organoids were given 6 Gy X-rays to construct the regeneration of intestinal stem cells. Hematoxylin and eosin (H&E) staining was performed for morphological observation. In situ hybridization was used to detect the expression of Lgr5, and immunofluorescence staining was adopted to detect the expression of CD44. FACS was used to sort CD44 positive cells of crypts. RNA was then extracted, and RNA-Seq was performed. The Wnt11 over-expression cell line was constructed to collect the Wnt11 conditioned medium (CM).

Results

The results showed both Lgr5 and CD44 located at the bottom of normal crypts. The expression of Lgr5 was lower at day 3.5, 5, but recovered at day 10 post-irradiation compared with the control. However, the expression of CD44 was higher at day 3.5, 5, but recovered at day 10 post-irradiation compared with the control group. The quantitative real-time polymerase chain reaction (qRT-PCR) assay showed consistent results. RNA-Seq results showed that Wnt11 was over-expressed in the irradiation group. After irradiation adding Wnt11 condition medium to culture, the intestinal organoids resulted in a bigger size and more buddings of the newborn organoids compared with the control group.

Conclusions

The expression of CD44 increases during the radiation-induced regeneration of intestinal stem cells while Lgr5 decreases, adding Wnt11 CM can facilitate the proliferation of the newborn organoids after irradiation. Wnt11 is a potential target to promote the regeneration of intestinal stem cells to repair the radiation injury.