Radiation-induced inflammation and autoimmune diseases

Ionizing radiation induces neurotoxicity in Xenopus laevis embryos through neuroactive ligand-receptor interaction pathway

Ionizing radiation (IR) poses a significant threat to both the natural environment and biological health. Exposure to specific doses of ionizing radiation early in an organism's development can lead to developmental toxicity, particularly neurotoxicity. Through experimentation with Xenopus laevis (X. laevis), we examined the effects of radiation on early developmental stage. Our findings revealed that radiation led to developmental abnormalities and mortality in X. laevis embryos in a dose-dependent manner, disrupting redox homeostasis and inducing cell apoptosis. Additionally, radiation caused neurotoxic effects, resulting in abnormal behavior and neuron damage in the embryos. Further investigation into the underlying mechanisms of radiation-induced neurotoxicity indicated the potential involvement of the neuroactive ligand-receptor interaction pathway, which was supported by RNA-Seq analysis. Validation of gene expression associated with this pathway and analysis of neurotransmitter levels confirmed our hypothesis. In addition, we further validated the important role of this signaling pathway in radiation-induced neurotoxicity through edaravone rescue experiments. This research establishes a valuable model for radiation damage studying and provides some insight into radiation-induced neurotoxicity mechanisms.

A novel nomogram based on inflammation biomarkers for predicting radiation cystitis in patients with local advanced cervical cancer

BACKGROUNDS

Platelet-to-albumin ratio (PAR) is a new systemic inflammatory prognostic indicator associated with many inflammatory diseases. However, its role in radiation cystitis (RC) is obscure. This study aimed to explore whether PAR could be used as an effective parameter for predicting the RC risk in local advanced cervical cancer (CC) treated with radiotherapy.

METHODS

A total of 319 local advanced CC patients who received radical radiotherapy at Fujian Cancer Hospital were enrolled between December 2018 and January 2021. Demographics and clinical parameters were retrospectively analyzed. Univariate and multivariate analyses were used to identify the risk factors for RC. Backward and stepwise regression was applied to construct two monograms-one with primary significant factors and the other with extra inflammatory biomarkers. A DeLong test was applied to compare the prediction abilities of two nomograms. Calibration curves and decision curve analysis (DCA) evaluated its prediction consistency, discrimination ability, and clinical net benefit.

RESULTS

Univariate analysis showed that age, tumor size, stage, total radiation dose, pelvic radiation dose, Systemic Immune-Inflammation Index (SII), platelet-to-lymphocyte ratio (PLR), and PAR were significantly associated with RC occurrence (all p < 0.05). Multivariate analyses indicated that age, tumor size, stage, total radiation dose, and PAR were independent factors (all p < 0.05). Then, the area under curve (AUC) value of the nomogramSII+PAR was higher (AUC = 0.774) compared to that of the baseline nomogram (AUC = 0.726) (pDelong = 0.02). Also, the five-cross validation confirmed the stability of the nomogramSII+PAR. Moreover, the calibration curve and DCA exhibited the nomograms' good prediction consistency and clinical practicability.

CONCLUSIONS

PAR and SII could be valued for CC patients who are treated with radiation therapy. The nomogram based on PAR and SII could stratify patients who need extra intervention and nursing care to prevent bladder radiation damage and improve patients' quality of life.

Serum microRNA profile of rhesus macaques following ionizing radiation exposure and treatment with a medical countermeasure, Ex-Rad

Exposure to ionizing radiation (IR) presents a formidable clinical challenge. Total-body or significant partial-body exposure at a high dose and dose rate leads to acute radiation syndrome (ARS), the complex pathologic effects that arise following IR exposure over a short period of time. Early and accurate diagnosis of ARS is critical for assessing the exposure dose and determining the proper treatment. Serum microRNAs (miRNAs) may effectively predict the impact of irradiation and assess cell viability/senescence changes and inflammation. We used a nonhuman primate (NHP) model-rhesus macaques (Macaca mulatta)-to identify the serum miRNA landscape 96 h prior to and following 7.2 Gy total-body irradiation (TBI) at four timepoints: 24, 36, 48, and 96 h. To assess whether the miRNA profile reflects the therapeutic effect of a small molecule ON01210, commonly known as Ex-Rad, that has demonstrated radioprotective efficacy in a rodent model, we administered Ex-Rad at two different schedules of NHPs; either 36 and 48 h post-irradiation or 48 and 60 h post-irradiation. Results of this study corroborated our previous findings obtained using a qPCR array for several miRNAs and their modulation in response to irradiation: some miRNAs demonstrated a temporary increased serum concentration within the first 24-36 h (miR-375, miR-185-5p), whereas others displayed either a prolonged decline (miR-423-5p) or a long-term increase (miR-30a-5p, miR-27b-3p). In agreement with these time-dependent changes, hierarchical clustering of differentially expressed miRNAs showed that the profiles of the top six miRNA that most strongly correlated with radiation exposure were inconsistent between the 24 and 96 h timepoints following exposure, suggesting that different biodosimetry miRNA markers might be required depending on the time that has elapsed. Finally, Ex-Rad treatment restored the level of several miRNAs whose expression was significantly changed after radiation exposure, including miR-16-2, an miRNA previously associated with radiation survival. Taken together, our findings support the use of miRNA expression as an indicator of radiation exposure and the use of Ex-Rad as a potential radioprotectant.

Fatal brainstem injury following proton radiation in a patient with medulloblastoma and a germline variant in RNF213

Brainstem injury occurs secondary to radiation to the posterior fossa in up to 2% of pediatric patients. It may occur after months to years after treatment. It has been associated with age less than 5 years and with comorbid conditions such as cerebrovascular disease, diabetes mellitus, and hypertension. Radiation necrosis is often symptomatic and can be fatal. A pathogenic variant in RNF213 was found in a patient who suffered fatal radiation necrosis. This mutation has been associated with moyamoya disease and may predispose to radiation necrosis.

Effect of adenosine treatment on ionizing radiation toxicity in zebrafish early life stages

The danger of ionizing radiation exposure to human health is a concern. Since its wide use in medicine and industry, the development of radioprotectors has been very significant. Adenosine exerts anti-inflammatory actions and promotes tissue protection and repair, by activating the P1 receptors (A1, A2A, A2B, and A3). Zebrafish (Danio rerio) is an appropriate tool in the fields of toxicology and pharmacology, including the evaluation of radiobiological outcomes and in the search for radioprotector agents. This study aims to evaluate the effect of adenosine in the toxicity induced by radiation in zebrafish. Embryos were treated with 1, 10, or 100 µM adenosine, 30 min before the exposure to 15 Gy of gamma radiation. Adenosine potentiated the effects of radiation in heart rate, body length, and pericardial edema. We evaluated oxidative stress, tissue remodeling and inflammatory. It was seen that 100 µM adenosine reversed the inflammation induced by radiation, and that A2A2 and A2B receptors are involved in these anti-inflammatory effects. Our results indicate that P1R activation could be a promising pharmacological strategy for radioprotection.

Crosstalk between Oxidative Stress and Inflammation Induced by Ionizing Radiation in Healthy and Cancerous Cells

Radiotherapy (RT) is a unique modality in cancer treatment with no replacement in many cases and uses a tumoricidal dose of various ionizing radiation (IR) types to kill cancer cells. It causes oxidative stress through reactive oxygen species (ROS) production or the destruction of antioxidant systems. On the other hand, RT stimulates the immune system both directly and indirectly by releasing danger signals from stress-exposed and dying cells. Oxidative stress and inflammation are two reciprocal and closely related mechanisms, one induced and involved by the other. ROS regulates the intracellular signal transduction pathways, which participate in the activation and expression of pro-inflammatory genes. Reciprocally, inflammatory cells release ROS and immune system mediators during the inflammation process, which drive the induction of oxidative stress. Oxidative stress or inflammation-induced damages can result in cell death (CD) or survival mechanisms that may be destructive for normal cells or beneficial for cancerous cells. The present study has focused on the radioprotection of those agents with binary effects of antioxidant and anti-inflammatory mechanisms IR-induced CD.

Cellular RNA and DNA sensing pathways are essential for the dose-dependent response of human monocytes to ionizing radiation

Circulating monocytes are important players of the inflammatory response to ionizing radiation (IR). These IR-resistant immune cells migrate to radiation-damaged tissues and differentiate into macrophages that phagocytize dying cells, but also facilitate inflammation. Besides the effect of damage-associated molecular patterns, released from irradiated tissues, the inflammatory activation of monocytes and macrophages is largely dependent on IR-induced DNA damage and aberrant transcriptional activity, which may facilitate expression of type I interferons (IFN-I) and numerous inflammation-related genes. We analyzed the accumulation of dsRNA, dsDNA fragments, and RNA:DNA hybrids in the context of induction of RNA-triggered MAVS-mediated and DNA-triggered STING-mediated signaling pathways, in primary human monocytes and a monocytic cell line, THP1, in response to various doses of gamma IR. We found that exposure to lower doses (<7.5 Gy) led to the accumulation of dsRNA, along with dsDNA and RNA:DNA hybrids and activated both MAVS and STING pathway-induced gene expression and signaling activity of IFN-I. Higher doses of IR resulted in the reduced dsRNA level, degradation of RNA-sensing mediators involved in MAVS signaling and coincided with an increased accumulation of dsDNA and RNA:DNA hybrids that correlated with elevated STING signaling and NF-κB-dependent gene expression. While both pathways activate IFN-I expression, using MAVS- and STING-knockout THP1 cells, we identified differences in the spectra of interferon-stimulated genes (ISGs) that are associated with each specific signaling pathway and outlined a large group of STING signaling-associated genes. Using the RNAi technique, we found that increasing the dose of IR activates STING signaling through the DNA sensor cGAS, along with suppression of the DDX41 helicase, which is known to reduce the accumulation of RNA:DNA hybrids and thereby limit cGAS/STING signaling activity. Together, these results indicate that depending on the applied dose, IR leads to the activation of either dsRNA-induced MAVS signaling, which predominantly leads to the expression of both pro- and anti-inflammatory markers, or dsDNA-induced STING signaling that contributes to pro-inflammatory activation of the cells. While RNA:DNA hybrids boost both MAVS- and STING-mediated signaling pathways, these structures being accumulated upon high IR doses promote type I interferon expression and appear to be potent enhancers of radiation dose-dependent pro-inflammatory activation of monocytes.

Acute irradiation causes a long-term disturbance in the heterogeneity and gene expression profile of medullary thymic epithelial cells

The thymus has the ability to regenerate from acute injury caused by radiation, infection, and stressors. In addition to thymocytes, thymic epithelial cells in the medulla (mTECs), which are crucial for T cell self-tolerance by ectopically expressing and presenting thousands of tissue-specific antigens (TSAs), are damaged by these insults and recover thereafter. However, given recent discoveries on the high heterogeneity of mTECs, it remains to be determined whether the frequency and properties of mTEC subsets are restored during thymic recovery from radiation damage. Here we demonstrate that acute total body irradiation with a sublethal dose induces aftereffects on heterogeneity and gene expression of mTECs. Single-cell RNA-sequencing (scRNA-seq) analysis showed that irradiation reduces the frequency of mTECs expressing AIRE, which is a critical regulator of TSA expression, 15 days after irradiation. In contrast, transit-amplifying mTECs (TA-mTECs), which are progenitors of AIRE-expressing mTECs, and Ccl21a-expressing mTECs, were less affected. Interestingly, a detailed analysis of scRNA-seq data suggested that the proportion of a unique mTEC cluster expressing Ccl25 and a high level of TSAs was severely decreased by irradiation. In sum, we propose that the effects of acute irradiation disrupt the heterogeneity and properties of mTECs over an extended period, which potentially leads to an impairment of thymic T cell selection.

A blinded-endpoint, randomized controlled trial of Sanyrene with natural active ingredient for prophylaxis of radiation dermatitis in patients receiving radiotherapy

BACKGROUND

Randomized controlled study was conducted to evaluate the efficacy of Sanyrene® vs. control intervention (DaBao®, a complex of hyaluronic acid and Vitamin E) for acute radiation dermatitis in patients receiving radiotherapy.

METHODS

Patients with breast cancer or head and neck cancer undergoing radiotherapy (≥ 50 Gy) were eligible. Participants were randomly assigned to either Sanyrene arm or control intervention arm in a ratio of 1:1. The primary endpoint was incidence rate of ≥ grade 2 radiation induced dermatitis. (Trial Registration: ChiCTR2100050910, registration date: 9/7/2021) RESULTS: A total of 102 eligible patients were randomly assigned into the study. The rate of ≥ grade 2 radiation dermatitis was 22% in Sanyrene group, as compared with 67.3% in the control intervention group (P<0.001). The incidence of grade 3 radiation dermatitis was 20.4% and 8.0% in control intervention group and Sanyrene group, respectively (P = 0.076). Patients in Sanyrene group had a longer median time to reach ≥ grade 2 radiation dermatitis compared to these in control intervention group, with hazard ratio of 0.231 (95%CI:0.116-0.458, p < 0.001). Mean score of SD-16 were much higher in control intervention group than Sanyrene group at end of radiotherapy (25 vs.8.3), 2 weeks after radiotherapy (22.9 vs. 0.5) and 4 weeks after radiotherapy (4.2 vs.0), with significantly statistical difference between two groups.

CONCLUSIONS

This trial suggests that Sanyrene is effective on preventing serious radiation dermatitis and improving skin related quality of life in patients with breast cancer or head and neck cancer receiving radiotherapy.

Ubiquinol preserves immune cells in gamma-irradiated rats: Role of autophagy and apoptosis in splenic tissue

Radiation has been applied in cancer treatment to eradicate tumors and displayed great therapeutic benefits for humans. However, it is associated with negative impacts on normal cells, not only cancer cells. Irradiation can trigger cell death through several mechanisms, such as apoptosis, necrosis, and autophagy. This study aimed to investigate the radioprotective efficacy of ubiquinol against radiation-induced splenic tissue injury in animals and the related involved mechanisms. Animals were classified into four groups: group 1 (normal untreated rats) received vehicle 5 % Tween 80; group 2 received 7 Gy γ-radiation; group 3 received 10 mg/Kg oral ubiquinol post-irradiation; and group 4 received 10 mg/Kg oral ubiquinol before and after (pre/post-) irradiation. Ubiquinol restored the spleen histoarchitecture, associated with improved immunohistochemical quantification of B and T lymphocyte markers and ameliorated hematological alterations induced by irradiation. Such effects may be due to an enhanced antioxidant pathway through stimulation of p62, Nrf2, and GSH, associated with reduced Keap1 and MDA. Moreover, ubiquinol decreased mTOR, thus enhanced autophagy markers viz. LC3-II. Furthermore, ubiquinol showed an antiapoptotic effect by enhancing Bcl-2 and reducing caspase-3 and Bax. Consequently, ubiquinol exerts a splenic-protective effect against irradiation via enhancing antioxidant, autophagic, and survival pathways.

Suppression of TREX1 deficiency-induced cellular senescence and interferonopathies by inhibition of DNA damage response

TREX1 encodes a major DNA exonuclease and mutations of this gene are associated with type I interferonopathies in human. Mice with Trex1 deletion or mutation have shortened life spans accompanied by a senescence-associated secretory phenotype. However, the contribution of cellular senescence in TREX1 deficiency-induced type I interferonopathies remains unknown. We found that features of cellular senescence present in Trex1^-/- mice are induced by multiple factors, particularly DNA damage. The cGAS-STING and DNA damage response pathways are required for maintaining TREX1 deletion-induced cellular senescence. Inhibition of the DNA damage response, such as with Checkpoint kinase 2 (CHK2) inhibitor, partially alleviated progression of type I interferonopathies and lupus-like features in the mice. These data provide insights into the initiation and development of type I interferonopathies and lupus-like diseases, and may help inform the development of targeted therapeutics.

A novel multifunctional radioprotective strategy using P7C3 as a countermeasure against ionizing radiation-induced bone loss

Radiotherapy is a critical component of cancer care but can cause osteoporosis and pathological insufficiency fractures in surrounding and otherwise healthy bone. Presently, no effective countermeasure exists, and ionizing radiation-induced bone damage continues to be a substantial source of pain and morbidity. The purpose of this study was to investigate a small molecule aminopropyl carbazole named P7C3 as a novel radioprotective strategy. Our studies revealed that P7C3 repressed ionizing radiation (IR)-induced osteoclastic activity, inhibited adipogenesis, and promoted osteoblastogenesis and mineral deposition in vitro. We also demonstrated that rodents exposed to clinically equivalent hypofractionated levels of IR in vivo develop weakened, osteoporotic bone. However, the administration of P7C3 significantly inhibited osteoclastic activity, lipid formation and bone marrow adiposity and mitigated tissue loss such that bone maintained its area, architecture, and mechanical strength. Our findings revealed significant enhancement of cellular macromolecule metabolic processes, myeloid cell differentiation, and the proteins LRP-4, TAGLN, ILK, and Tollip, with downregulation of GDF-3, SH2B1, and CD200. These proteins are key in favoring osteoblast over adipogenic progenitor differentiation, cell matrix interactions, and shape and motility, facilitating inflammatory resolution, and suppressing osteoclastogenesis, potentially via Wnt/β-catenin signaling. A concern was whether P7C3 afforded similar protection to cancer cells. Preliminarily, and remarkably, at the same protective P7C3 dose, a significant reduction in triple-negative breast cancer and osteosarcoma cell metabolic activity was found in vitro. Together, these results indicate that P7C3 is a previously undiscovered key regulator of adipo-osteogenic progenitor lineage commitment and may serve as a novel multifunctional therapeutic strategy, leaving IR an effective clinical tool while diminishing the risk of adverse post-IR complications. Our data uncover a new approach for the prevention of radiation-induced bone damage, and further work is needed to investigate its ability to selectively drive cancer cell death.

Considerations of Medical Preparedness to Assess and Treat Various Populations During a Radiation Public Health Emergency

During a radiological or nuclear public health emergency, given the heterogeneity of civilian populations, it is incumbent on medical response planners to understand and prepare for a potentially high degree of interindividual variability in the biological effects of radiation exposure. A part of advanced planning should include a comprehensive approach, in which the range of possible human responses in relation to the type of radiation expected from an incident has been thoughtfully considered. Although there are several reports addressing the radiation response for special populations (as compared to the standard 18-45-year-old male), the current review surveys published literature to assess the level of consideration given to differences in acute radiation responses in certain sub-groups. The authors attempt to bring clarity to the complex nature of human biology in the context of radiation to facilitate a path forward for radiation medical countermeasure (MCM) development that may be appropriate and effective in special populations. Consequently, the focus is on the medical (as opposed to logistical) aspects of preparedness and response. Populations identified for consideration include obstetric, pediatric, geriatric, males, females, individuals of different race/ethnicity, and people with comorbidities. Relevant animal models, biomarkers of radiation injury, and MCMs are highlighted, in addition to underscoring gaps in knowledge and the need for consistent and early inclusion of these populations in research. The inclusion of special populations in preclinical and clinical studies is essential to address shortcomings and is an important consideration for radiation public health emergency response planning. Pursuing this goal will benefit the population at large by considering those at greatest risk of health consequences after a radiological or nuclear mass casualty incident.

Biomimetic Prussian blue nanozymes with enhanced bone marrow-targeting for treatment of radiation-induced hematopoietic injury

There is an urgent medical need to develop effective therapies that can ameliorate damage to the radiation-exposed hematopoietic system. Nanozymes with robust antioxidant properties have a therapeutic potential for mitigating radiation-induced hematopoietic injury. However, enhancing nanozyme recruitment to injured tissues in vivo while maintaining their catalytic activity remains a great challenge. Herein, we present the design and preparation of a biomimetic nanoparticle, a mesenchymal stem cell membrane camouflaged Prussian blue nanozyme (PB@MSCM), which exhibits biocompatible surface properties and demonstrates enhanced injury site-targeting towards the irradiated murine bone marrow niche. Notably, the constructed PB@MSCM possessed redox enzyme-mimic catalytic activity and could scavenge overproduced reactive oxygen species in the irradiated bone marrow cells, both in vitro and ex vivo. More importantly, the administration of PB@MSCM significantly mitigated hematopoietic cell apoptosis and accelerated the regeneration of hematopoietic stem and progenitor cells. Our findings provide a new targeted strategy to improve nanozyme therapy in vivo and mitigate radiation-induced hematopoietic injury.

Automatic quality assurance of radiotherapy treatment plans using Bayesian networks: A multi-institutional study

Purpose

Artificial intelligence applications in radiation oncology have been the focus of study in the last decade. The introduction of automated and intelligent solutions for routine clinical tasks, such as treatment planning and quality assurance, has the potential to increase safety and efficiency of radiotherapy. In this work, we present a multi-institutional study across three different institutions internationally on a Bayesian network (BN)-based initial plan review assistive tool that alerts radiotherapy professionals for potential erroneous or suboptimal treatment plans.

Methods

Clinical data were collected from the oncology information systems in three institutes in Europe (Maastro clinic - 8753 patients treated between 2012 and 2020) and the United States of America (University of Vermont Medical Center [UVMMC] - 2733 patients, University of Washington [UW] - 6180 patients, treated between 2018 and 2021). We trained the BN model to detect potential errors in radiotherapy treatment plans using different combinations of institutional data and performed single-site and cross-site validation with simulated plans with embedded errors. The simulated errors consisted of three different categories: i) patient setup, ii) treatment planning and iii) prescription. We also compared the strategy of using only diagnostic parameters or all variables as evidence for the BN. We evaluated the model performance utilizing the area under the receiver-operating characteristic curve (AUC).

Results

The best network performance was observed when the BN model is trained and validated using the dataset in the same center. In particular, the testing and validation using UVMMC data has achieved an AUC of 0.92 with all parameters used as evidence. In cross-validation studies, we observed that the BN model performed better when it was trained and validated in institutes with similar technology and treatment protocols (for instance, when testing on UVMMC data, the model trained on UW data achieved an AUC of 0.84, compared with an AUC of 0.64 for the model trained on Maastro data). Also, combining training data from larger clinics (UW and Maastro clinic) and using it on smaller clinics (UVMMC) leads to satisfactory performance with an AUC of 0.85. Lastly, we found that in general the BN model performed better when all variables are considered as evidence.

Conclusion

We have developed and validated a Bayesian network model to assist initial treatment plan review using multi-institutional data with different technology and clinical practices. The model has shown good performance even when trained on data from clinics with divergent profiles, suggesting that the model is able to adapt to different data distributions.

Elucidations of Molecular Mechanism and Mechanistic Effects of Environmental Toxicants in Neurological Disorders

Due to rising environmental and global public health concerns associated with environmental contamination, human populations are continually being exposed to environmental toxicants, including physical chemical mutagens widespread in our environment causing adverse consequences and inducing a variety of neurological disorders in humans. Physical mutagens comprise ionizing and non-ionizing radiation, such as UV rays, IR rays, X-rays, which produces a broad spectrum of neuronal destruction, including neuroinflammation, genetic instability, enhanced oxidative stress driving mitochondrial damage in the human neuronal antecedent cells, cognitive impairment due to alterations in neuronal function, especially in synaptic plasticity, neurogenesis repression, modifications in mature neuronal networks drives to enhanced neurodegenerative risk. Chemical Mutagens including alkylating agents (EMS, NM, MMS, and NTG), Hydroxylamine, nitrous acid, sodium azide, halouracils are the major toxic mutagen in our environment and have been associated with neurological disorders. These chemical mutagens create dimers of pyrimidine that cause DNA damage that leads to ROS generation producing mutations, chromosomal abnormalities, genotoxicity which leads to increased neurodegenerative risk. The toxicity of four heavy metal including Cd, As, Pb, Hg is mostly responsible for complicated neurological disorders in humans. Cadmium exposure can enhance the permeability of the BBB and penetrate the brain, driving brain intracellular accumulation, cellular dysfunction, and cerebral edema. Arsenic exerts its toxic effect by induction of ROS production in neuronal cells. In this review, we summarize the molecular mechanism and mechanistic effects of mutagens in the environment and their role in multiple neurological disorders.

Radiation-induced PD-L1 expression in tumor and its microenvironment facilitates cancer-immune escape: a narrative review

Background and Objective

Radiotherapy (RT) is one of the fundamental anti-cancer regimens by means of inducing in situ tumor vaccination and driving a systemic anti-tumor immune response. It can affect the tumor microenvironment (TME) components consisting of blood vessels, immunocytes, fibroblasts, and extracellular matrix (ECM), and might subsequently suppress anti-tumor immunity through expression of molecules such as programmed death ligand-1 (PD-L1). Immune checkpoint inhibitors (ICIs), especially anti-programmed cell death 1 (PD-1)/PD-L1 therapies, have been regarded as effective in the reinvigoration of the immune system and another major cancer treatment. Experimentally, combination of RT and ICIs therapy shows a greater synergistic effect than either therapy alone.

Methods

We performed a narrative review of the literature in the PubMed database. The research string comprised various combinations of "radiotherapy", "programmed death-ligand 1", "microenvironment", "exosome", "myeloid cell", "tumor cell", "tumor immunity". The database was searched independently by two authors. A third reviewer mediated any discordance of the results of the two screeners.

Key Content and Findings

RT upregulates PD-L1 expression in tumor cells, tumor-derived exosomes (TEXs), myeloid-derived suppressor cells (MDSCs), and macrophages. The signaling pathways correlated to PD-L1 expression in tumor cells include the DNA damage signaling pathway, epidermal growth factor receptor (EGFR) pathway, interferon gamma (IFN-γ) pathway, cGAS-STING pathway, and JAK/STATs pathway.

Conclusions

PD-L1 upregulation post-RT is found not only in tumor cells but also in the TME and is one of the mechanisms of tumor evasion. Therefore, further studies are necessary to fully comprehend this biological process. Meanwhile, combination of therapies has been shown to be effective, and novel approaches are to be developed as adjuvant to RT and ICIs therapy.

The Effect of PD-1 Inhibitor Combined with Irradiation on HMGB1-Associated Inflammatory Cytokines and Myocardial Injury

PURPOSE

To explore the effect of PD-1 inhibitors combined with irradiation on myocardial injury and the changes of HMGB1-associated inflammatory markers.

METHODS

Four groups of five mice were used, each groupformed by randomly dividing 20 mice (group A control; group B PD-1 inhibitors; group C Irradiation; group D PD-1 inhibitors+irradiation; n = 5 for each). The mice were treated with either PD-1 inhibitors or a 15 Gy dose of single heart irradiation, or both. Hematoxylin-eosin staining assessed the morphology and pathology of heart tissue; Masson staining assessed heart fibrosis; Tunel staining evaluated heart apoptosis; flow cytometry detected CD3+, CD4+, and CD8+ T lymphocytes in heart tissues; enzyme linked immunosorbent assay evaluated IL-1β, IL-6, and TNF-ɑ of heart tissue; Western blot and quantitative real-time PCR (qPCR) detected the expression of protein and mRNA of HMGB1, TLR-4, and NF-κB p65 respectively.

RESULTS

The degree of heart injury, collagen volume fraction (CVF) and apoptotic index (AI) in groups B, C, and D were higher than group A, but the differences between the CVF and AI of group A and group B were not statistical significance (P>0.05). Similarly, the absolute counts and relative percentage of CD3+ and CD8+ T lymphocytes and the concentrations of IL-1β, IL-6, and TNF-α in heart tissue with group D were significantly higher than the other groups (P<0.05). In addition, compared with group A, the expression of protein and mRNA of HMGB1 and NF-κB p65 in other groups were higher, and the differences between each group were statistically significant while TLR4 was not. In addition, interaction by PD-1 inhibitors and irradiation was found in inflammatory indicators, especially in the expression of the HMGB1 and CD8+ T lymphocytes.

CONCLUSION

PD-1 inhibitors can increase the expression of HMGB1-associated inflammatory cytokines and aggravate radiation-induced myocardial injury.

Radioprotective effect of mistletoe extract on intestinal toxicity: in vivo study using adult zebrafish

PURPOSE

The intestine is a dose-limiting organ in the treatment of intra-abdominal cancer. We previously reported that the extract of mistletoe parasites on Quercus had a more potent radioprotective effect than amifostine in reducing the developmental toxicities of zebrafish embryos. In this study, radioprotection against intestinal toxicity was investigated in adult zebrafish.

METHODS

Wild-type adult AB zebrafish were exposed to 45-50 Gy of photon beam irradiation and/or treated with mistletoe extract orally 1 h before. The main endpoints of the study were survival and degree of deformation of the intestinal villi.

RESULTS

The median follow-up period was 10 d post-irradiation (range: 7-11 d). A total of 105 zebrafish were used, including 42 in the radiation alone, 42 in the radiation and mistletoe arms, and 21 control subjects (mistletoe alone, mock-irradiated arm). The rate of both significant deformity and death was 53% in the radiation-alone arm, whereas the corresponding rate was 30% in the radiation and mistletoe arms. Significant deformity-free survival rates at 10 d post-irradiation in the radiation alone, and radiation and mistletoe arms were 44.7% (95% confidence interval [CI]:20-54.3) and 68.4% (95% CI:53.8-86.8), respectively (p=.046). The radiation and mistletoe arms showed decreased expression of two of three inflammatory genes (IL-1β and IL-6) compared to the radiation alone group (p<.05).

CONCLUSION

The radioprotective effect against intestinal toxicity was successfully shown in an adult zebrafish model. This result suggests the possibility of clinical use of mistletoe extract for the treatment of abdominal cancers.

Opaganib Protects against Radiation Toxicity: Implications for Homeland Security and Antitumor Radiotherapy

Exposure to ionizing radiation (IR) is a lingering threat from accidental or terroristic nuclear events, but is also widely used in cancer therapy. In both cases, host inflammatory responses to IR damage normal tissue causing morbidity and possibly mortality to the victim/patient. Opaganib, a first-in-class inhibitor of sphingolipid metabolism, has broad anti-inflammatory and anticancer activity. Opaganib elevates ceramide and reduces sphingosine 1-phosphate (S1P) in cells, conditions that increase the antitumor efficacy of radiation while concomitantly suppressing inflammatory damage to normal tissue. Therefore, opaganib may suppress toxicity from unintended IR exposure and improve patient response to chemoradiation. To test these hypotheses, we first examined the effects of opaganib on the toxicity and antitumor activity of radiation in mice exposed to total body irradiation (TBI) or IR with partial bone marrow shielding. Oral treatment with opaganib 2 h before TBI shifted the LD75 from 9.5 Gy to 11.5 Gy, and provided substantial protection against gastrointestinal damage associated with suppression of radiation-induced elevations of S1P and TNFα in the small intestines. In the partially shielded model, opaganib provided dose-dependent survival advantages when administered 4 h before or 24 h after radiation exposure, and was particularly effective when given both prior to and following radiation. Relevant to cancer radiotherapy, opaganib decreased the sensitivity of IEC6 (non-transformed mouse intestinal epithelial) cells to radiation, while sensitizing PAN02 cells to in vitro radiation. Next, the in vivo effects of opaganib in combination with radiation were examined in a syngeneic tumor model consisting of C57BL/6 mice bearing xenografts of PAN02 pancreatic cancer cells and a cross-species xenograft model consisting of nude mice bearing xenografts of human FaDu cells. Mice were treated with opaganib and/or IR (plus cisplatin in the case of FaDu tumors). In both tumor models, the optimal suppression of tumor growth was attained by the combination of opaganib with IR (± cisplatin). Overall, opaganib substantially protects normal tissue from radiation damage that may occur through unintended exposure or cancer radiotherapy.

Mechanisms of FLASH effect

FLASH radiotherapy (FLASH-RT) is a novel radiotherapy technology defined as ultra-high dose rate (≥ 40 Gy/s) radiotherapy. The biological effects of FLASH-RT include two aspects: first, compared with conventional dose rate radiotherapy, FLASH-RT can reduce radiation-induced damage in healthy tissue, and second, FLASH-RT can retain antitumor effectiveness. Current research shows that mechanisms of the biological effects of FLASH-RT are related to oxygen. However, due to the short time of FLASH-RT, evidences related to the mechanisms are indirect, and the exact mechanisms of the biological effects of FLASH-RT are not completely clear and some are even contradictory. This review focuses on the mechanisms of the biological effects of FLASH-RT and proposes future research directions.

Development of an Adverse Outcome Pathway for radiation-induced microcephaly via expert consultation and machine learning

BACKGROUND

Brain development during embryogenesis and in early postnatal life is particularly complex and involves the interplay of many cellular processes and molecular mechanisms, making it extremely vulnerable to exogenous insults, including ionizing radiation (IR). Microcephaly is one of the most frequent neurodevelopmental abnormalities that is characterized by small brain size, and is often associated with intellectual deficiency. Decades of research span from epidemiological data on in utero exposure of the A-bomb survivors, to studies on animal and cellular models that allowed deciphering the most prominent molecular mechanisms leading to microcephaly. The Adverse Outcome Pathway (AOP) framework is used to organize, evaluate and portray the scientific knowledge of toxicological effects spanning different biological levels of organizations, from the initial interaction with molecular targets to the occurrence of a disease or adversity. In the present study, the framework was used in an attempt to organize the current scientific knowledge on microcephaly progression in the context of ionizing radiation (IR) exposure. This work was performed by a group of experts formed during a recent workshop organized jointly by the Multidisciplinary European Low Dose Initiative (MELODI) and the European Radioecology Alliance (ALLIANCE) associations to present the AOP approach and tools. Here we report on the development of a putative AOP for congenital microcephaly resulting from IR exposure based on discussions of the working group and we emphasize the use of a novel machine-learning approach to assist in the screening of the available literature to develop AOPs.

CONCLUSION

The expert consultation led to the identification of crucial biological events for the progression of microcephaly upon exposure to IR, and highlighted current knowledge gaps. The machine learning approach was successfully used to screen the existing knowledge and helped to rapidly screen the body of evidence and in particular the epidemiological data. This systematic review approach also ensured that the analysis was sufficiently comprehensive to identify the most relevant data and facilitate rapid and consistent AOP development. We anticipate that as machine learning approaches become more user-friendly through easy-to-use web interface, this would allow AOP development to become more efficient and less time consuming.

Recent Advances Regarding the Molecular Mechanisms of Triterpenic Acids: A Review (Part II)

Triterpenic acids are a widespread class of phytocompounds which have been found to possess valuable therapeutic properties such as anticancer, anti-inflammatory, hepatoprotective, cardioprotective, antidiabetic, neuroprotective, lipolytic, antiviral, and antiparasitic effects. They are a subclass of triterpenes bearing a characteristic lipophilic structure that imprints unfavorable in vivo properties which subsequently limit their applications. The early investigation of the mechanism of action (MOA) of a drug candidate can provide valuable information regarding the possible side effects and drug interactions that may occur after administration. The current paper aimed to summarize the most recent (last 5 years) studies regarding the MOA of betulinic acid, boswellic acid, glycyrrhetinic acid, madecassic acid, moronic acid, and pomolic acid in order to provide scientists with updated and accessible material on the topic that could contribute to the development of future studies; the paper stands as the sequel of our previously published paper regarding the MOA of triterpenic acids with therapeutic value. The recent literature published on the topic has highlighted the role of triterpenic acids in several signaling pathways including PI3/AKT/mTOR, TNF-alpha/NF-kappa B, JNK-p38, HIF-α/AMPK, and Grb2/Sos/Ras/MAPK, which trigger their various biological activities.

Boswellic acid protects against Bisphenol-A and gamma radiation induced hepatic steatosis and cardiac remodelling in rats: role of hepatic PPAR-α/P38 and cardiac Calcineurin-A/NFATc1/P38 pathways

Bisphenol-A (BPA) and gamma-radiation are two risky environmental pollutants that human beings are exposed to in everyday life and consequently they threaten human health via inducing oxidative stress, inflammation, and eventually tissue damage. This study aims at appraising the protective effect of Boswellic Acid (BA) (250 mg/kg/day, orally) administration on BPA (150 mg/kg/day, i.p) and γ-irradiation (IR) (3 Gy/week for 4 weeks up to cumulative dose of 12 Gy/experimental course) for 4 weeks-induced damage to liver and heart tissues of rats. The present results indicated a significant improvement against damage induced by BPA and IR revealed in biochemical investigations (hepatic PPAR-α/P38 and cardiac ET-1/Calcineurin-A/NFATc1/P38) and histopathological examination of liver and heart. It could be concluded that BA possesses a protective effect against these two deleterious environmental pollutants which attracted major global concerns due to their serious toxicological impact on human health.

Small Molecule Signatures of Mice Lacking T-cell p38 Alternate Activation, a Model for Immunosuppression Conditions, after Total-Body Irradiation

Several diagnostic biodosimetry tools have been in development that may aid in radiological/nuclear emergency responses. Of these, correlating changes in non-invasive biofluid small-molecule signatures to tissue damage from ionizing radiation exposure show promise for inclusion in predictive biodosimetry models. Integral to dose reconstruction has been determining how genotypic variation in the general population will affect model performance. Here, we used a mouse model that lacks the T-cell receptor specific alternative p38 pathway [p38αβY323F, double knock-in (DKI) mice] to determine how attenuated autoimmune and inflammatory responses may affect dose reconstruction. We exposed adult male DKI mice (8-10 weeks old) to 2 and 7 Gy in parallel with wild-type mice and assessed perturbations in urine (days 1, 3, 7) and serum (day 1) using a global metabolomics approach. A multidimensional scaling plot showed excellent separation of radiation-exposed groups in wild-type mice with slightly dampened responses in DKI mice. Validated metabolite panels were developed for urine [N6,N6,N6-trimethyllysine (TML), N1-acetylspermidine, spermidine, carnitine, acylcarnitine C21H35NO5, 4-aminohippuric acid] and serum [phenylalanine, glutamine, propionylcarnitine, lysophosphatidylcholine (LysoPC 14:0), LysoPC (22:5)] to determine the area under the receiver operating characteristic curve (AUROC). For both urine and serum, excellent sensitivity and specificity (AUROC > 0.90) was observed for 0 Gy vs. 7 Gy groups irrespective of genotype using identical metabolite panels. Similarly, excellent to fair classification (AUROC > 0.75) was observed for ≤2 Gy vs. 7 Gy mice for both genotypes, however, model performance declined (AUROC < 0.75) between genotypes after irradiation. Overall, these results suggest immunosuppression should not compromise small molecule multiplex panels used in dose reconstruction for biodosimetry.

Tanshinone IIA attenuates AOM/DSS-induced colorectal tumorigenesis in mice via inhibition of intestinal inflammation

CONTEXT

Tanshinone IIA is a natural extract derived from a Chinese medicinal herb with multiple bioactivities; however, whether and how tanshinone IIA protects against colorectal cancer (CRC) are uncertain.

OBJECTIVE

We investigated the potential beneficial effects of tanshinone IIA in a colitis-associated colorectal tumorigenesis mouse model and its underlying mechanisms.

MATERIALS AND METHODS

Male C57BL/6 mice were treated with azoxymethane (AOM) 10 mg/kg body weight and dextran sulphate sodium (2.5% DSS) to induce a colitis-associated cancer model. Tanshinone IIA (200 mg/kg body weight) was given to the mice intraperitoneally. After 12 weeks, all mice were sacrificed to measure tumour formation, intestinal permeability, neutrophil infiltration, and colonic inflammation. In addition, whether tanshinone IIA has inhibitory effects on neutrophil activation was determined through in vitro investigations.

RESULTS

We observed that tanshinone IIA significantly decreased tumour formation in AOM/DSS-treated mice compared to AOM/DSS-treated alone mice (0.266 ± 0.057 vs. 0.78 ± 0.153, p = 0.013). Tanshinone IIA also decreased intestinal permeability compared to that in AOM/DSS-treated alone mice (3.12 ± 0.369 vs. 5.06 ± 0.597, p = 0.034) and consequently reduced neutrophil infiltration of the colonic mucosa (53.25 ± 8.85 vs. 107.6 ± 13.09, p = 0.014) as well as intestinal inflammation in mice. Mechanistically, tanshinone IIA downregulated the NF-κB signalling pathway in the colonic tumours of AOM/DSS-treated mice. In vitro assays further validated that tanshinone IIA suppressed LPS-induced neutrophil activation.

CONCLUSION

These data suggest that tanshinone IIA alleviates colorectal tumorigenesis through inhibition of intestinal inflammation. Tanshinone IIA may have a therapeutic potential for CRC in clinical practice.

Low Dose Ionising Radiation-Induced Hormesis: Therapeutic Implications to Human Health

The concept of radiation-induced hormesis, whereby a low dose is beneficial and a high dose is detrimental, has been gaining attention in the fields of molecular biology, environmental toxicology and radiation biology. There is a growing body of literature that recognises the importance of hormetic dose response not only in the radiation field, but also with molecular agents. However, there is continuing debate on the magnitude and mechanism of radiation hormetic dose response, which could make further contributions, as a research tool, to science and perhaps eventually to public health due to potential therapeutic benefits for society. The biological phenomena of low dose ionising radiation (LDIR) includes bystander effects, adaptive response, hypersensitivity, radioresistance and genomic instability. In this review, the beneficial and the detrimental effects of LDIR-induced hormesis are explored, together with an overview of its underlying cellular and molecular mechanisms that may potentially provide an insight to the therapeutic implications to human health in the future.

A hypothesis for the pathogenesis of radiation-induced oral mucositis: when biological challenges exceed physiologic protective mechanisms. Implications for pharmacological prevention and treatment

Oral mucositis (OM) remains a significant unmet need for patients being treated with standard concomitant chemoradiation (CRT) regimens for head and neck cancers (HNC). OM's pathogenesis is complex and includes both direct and indirect damage pathways. In this paper, the field is reviewed with emphasis on the initiating and sustaining role of oxidative stress on OM's pathobiology. A hypothesis is presented which suggests that based on OM's clinical and biological trajectory, mucosal damage is largely the consequence of cumulative CRT-induced biological changes overwhelming physiologic self-protective mechanisms. Furthermore, an individual's ability to mount and maintain a protective response is dependent on interacting pathways which are primarily determined by a multiplex consisting of genomics, epigenomics, and microbiomics. Effective biologic or pharmacologic OM interventions are likely to supplement or stimulate existing physiologic damage-control mechanisms.

Low dose ionizing radiation and the immune response: what is the role of non-targeted effects?

OBJECTIVES

This review aims to trace the historical narrative surrounding the low dose effects of radiation on the immune system and how our understanding has changed from the beginning of the 20th century to now. The particular focus is on the non-targeted effects (NTEs) of low dose ionizing radiation (LDIR) which are effects that occur when irradiated cells emit signals that cause effects in the nearby or distant non-irradiated cells known as radiation induced bystander effect (RIBE). Moreover, radiation induced genomic instability (RIGI) and abscopal effect (AE) also regarded as NTE. This was prompted by our recent discovery that ultraviolet A (UVA) photons are emitted by the irradiated cells and that these photons can trigger NTE such as the RIBE in unirradiated recipients of these photons. Given the well-known association between UV radiation and the immune response, where these biophotons may pose as bystander signals potentiating processes in deep tissues as a consequence of LDIR, it is timely to review the field with a fresh lens. Various pathways and immune components that contribute to the beneficial and adverse types of modulation induced by LDR will also be revisited.

CONCLUSION

There is limited evidence for LDIR induced immune effects by way of a non-targeted mechanism in biological tissue. The literature examining low to medium dose effects of ionizing radiation on the immune system and its components is complex and controversial. Early work was compromised by lack of good dosimetry while later work mainly looks at the involvement of immune response in radiotherapy. There is a lack of research in the LDIR/NTE field focusing on immune response although bone marrow stem cells and lineages were critical in the identification and characterization of NTE where effects like RIGI and RIBE were heavily researched. This may be in part, a result of the difficulty of isolating NTE in whole organisms which are essential for good immune response studies. Models involving inter organism transmission of NTE are a promising route to overcome these issues.

Fucoxanthin alters the apelin-13/APJ pathway in certain organs of γ-irradiated mice

Apelin-13 and APJ are implicated in different key physiological processes. This work aims at exploring the radioprotective effect of fucoxanthin (FX) on γ-radiation (RAD)-induced changes in the apelin-13/APJ pathway, which causes damage in the liver, kidney, lung and spleen of mice. Mice were administered FX (10 mg kg-1 day-1, i.p) and exposed to γ-radiation (2.5 Gy week-1) for four consecutive weeks. The treatment of irradiated mice by FX resulted in a significant amendment in protein expression of the apelin-13/APJ/NF-κB signalling pathway concurrently with reduced hypoxia (hypoxia-inducible factor-1α), suppressed oxidative stress marker (malondialdehyde), enhanced antioxidant defence mechanisms (reduced glutathione and glutathione peroxidase), a modulated inflammatory response [interleukin-6 (IL-6), monocyte chemoattractant protein-1, IL-10 and α-7-nicotinic acetylcholine receptor) and ameliorated angiogenic regulators [matrix metalloproteinase (MMP-2), MMP-9 and tissue inhibitor of metalloproteinase-1), as well as the tissue damage indicator (lactate dehydrogenase) in organ tissues. In addition, there were significant improvement in serum inflammatory markers tumour necrosis factor-α, IL-10, IL-1β and C-reactive protein compared with irradiated mice. The histopathological investigation of the FX + RAD organ tissues support the biochemical findings where the improvements in the tissues' architecture were obvious when compared with those of RAD. FX was thus shown to have a noticeable radioprotective action mediated through its regulatory effect on the apelin-13/APJ/NF-κB signalling pathway attributed to its antioxidant and anti-inflammatory activity that was reflected in different physiological processes. It could be recommended to use FX in cases of radiation exposure to protect normal tissues.

Serum antinuclear autoantibodies are associated with measures of oxidative stress and lifestyle factors: analysis of LIPIDOGRAM2015 and LIPIDOGEN2015 studies

Introduction

Oxidative stress is one of many factors suspected to promote antinuclear autoantibody (ANA) formation. Reactive oxygen species can induce changes in the antigenic structure of macromolecules, causing the immune system to treat them as "neo-antigens" and start production of autoantibodies. This study was designed to evaluate the relationship between oxidative stress markers, lifestyle factors and the detection of ANA.

Material and methods

We examined measures of oxidative stress indices of free-radical damage to lipids and proteins, such as total oxidant status (TOS), concentration of protein thiol groups (PSH), and malondialdehyde (MDA), activity of superoxide dismutase (SOD) in 1731 serum samples. The parameters of the non-enzymatic antioxidant system, such as total antioxidant status (TAS) and uric acid (UA) concentration, were also measured and the oxidative stress index (OSI-index) was calculated. All samples were tested for the presence of ANA using an indirect immunofluorescence assay (IIFA).

Results

The presence of ANA in women was associated with lower physical activity (p = 0.036), less frequent smoking (p = 0.007) and drinking of alcohol (p = 0.024) accompanied by significant changes in SOD isoenzymes activity (p < 0.001) and a higher uric acid (UA) concentration (p < 0.001). In ANA positive males we observed lower concentrations of PSH (p = 0.046) and increased concentrations of MDA (p = 0.047).

Conclusions

The results indicate that local oxidative stress may be associated with increased probability of ANA formation in a sex-specific manner.

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.

Plasma Proteins As Biodosimetric Markers of Low-Dose Radiation in Mice

Long-term exposures to low-dose radiation (LDR) may trigger several specific biological responses, including dysregulation of the immune and inflammatory systems. Here, we examined whether biodosimetry of LDR can be used to protect tissues from radiation or assess cancer risk. Mice were subjected to gamma-irradiation with repeated or single-dose LDR, and then the organ indices, peripheral hemogram, and blood biochemistry were analyzed. An antibody array was applied followed by enzyme-linked immunosorbent assay to evaluate the utility of multiple plasma proteins as biomarkers of repeated LDR in a murine model. LDR induced inapparent symptoms but slight variations in peripheral blood cell counts and alterations in blood biochemical indicator levels. Specific plasma proteins in the LDR groups were altered in response to a higher dose of irradiation at the same time points or a single-dose equivalent to the same total dose. Plasma levels of interleukin (IL)-5, IL-12p40, P-selectin, and serum amyloid A1 were associated with the LDR dose and thus may be useful as dosimetric predictors of LDR in mice. Estimating the levels of certain plasma proteins may yield promising biodosimetry parameters to accurately identify individuals exposed to LDR, facilitating risk assessment of long-term LDR exposure in individuals.

Molecular Hydrogen as a Potential Clinically Applicable Radioprotective Agent

Although ionizing radiation (radiation) is commonly used for medical diagnosis and cancer treatment, radiation-induced damages cannot be avoided. Such damages can be classified into direct and indirect damages, caused by the direct absorption of radiation energy into DNA and by free radicals, such as hydroxyl radicals (•OH), generated in the process of water radiolysis. More specifically, radiation damage concerns not only direct damages to DNA, but also secondary damages to non-DNA targets, because low-dose radiation damage is mainly caused by these indirect effects. Molecular hydrogen (H₂) has the potential to be a radioprotective agent because it can selectively scavenge •OH, a reactive oxygen species with strong oxidizing power. Animal experiments and clinical trials have reported that H₂ exhibits a highly safe radioprotective effect. This paper reviews previously reported radioprotective effects of H₂ and discusses the mechanisms of H₂, not only as an antioxidant, but also in intracellular responses including anti-inflammation, anti-apoptosis, and the regulation of gene expression. In doing so, we demonstrate the prospects of H₂ as a novel and clinically applicable radioprotective agent.

Protection Against Radiation-Induced Duox1 and Duox2 Upregulation in Rat's Lung Tissues by a Combination of Curcumin and L-Selenomethionine

Background: It has been proposed that increased levels of pro-inflammatory and pro-fibrotic cytokines play a key role in radiation-induced lung injury. Interleukin-4 (IL-4) and IL-13 are two pro-fibrotic cytokines that promote the production of free radicals through stimulation of Duox1 and Duox2. In this experimental study, we aimed to evaluate the expression of IL4Ra1, Duox1, IL13Ra2, and Duox2 genes following rat’s lung irradiation. Objectives: Also, we detected the modulatory effect of a combination of curcumin and L-selenomethionine on the expression of these genes. Methods: Twenty male rats were divided into four groups as G1: control (no treatment or radiation); G2: treatment with a combination of curcumin and L-selenomethionine; G3: radiation; G4: radiation plus a combination of curcumin and L-selenomethionine. sixty-seven days after irradiation, rats were killed for detecting the expression of IL4Ra1, IL13Ra2, Duox1, and Duox2. Results: The results showed no detectable expression for IL13Ra2, while the expression of IL4Ra1, Duox1, and Duox2 was increased. Treatment with a combination of curcumin and L-selenomethionine could attenuate the expression of these genes. Conclusions: This study proposes that upregulation of Duox1 and Duox2 may be involved in radiation-induced lung injury. Treatment with a combination of curcumin and L-selenomethionine may be useful for the mitigation of lung injury through modulation of these genes.

Usefulness of Honey as an Adjunct in the Radiation Treatment for Head and Neck Cancer: Emphasis on Pharmacological and Mechanism/s of Actions

BACKGROUND

In the treatment of head and neck cancer (HNC), ionizing radiation is an important modality in achieving curative objectives. However, the effective use of radiation is compromised by the side effects resulting from the damage to the adjacent normal tissue. Preclinical studies carried out in the recent past have shown that the age old dietary agent honey, which also possess myriad medicinal use is beneficial in mitigating diverse radiation-induced side effects like mucositis, xerostomia, fatigue, weight loss and to promote healing of refractory wounds.

OBJECTIVE

The objective of this memoir is to review the beneficial effects of honey in mitigating radiation-induced side effects in HNC and to emphasize on the underlying mechanism of action for the beneficial effects Methods: Two authors searched Google Scholar, PubMed, Embase, and the Cochrane Library for publications up to December 2019 to assess the ability of honey in reducing the severity of radiation-induced ill effects in the treatment of HNC. Subsequently, the adjunct pharmacological effects and mechanism/s responsible were also searched for and appropriately used to substantiate the underlying mechanism/s of action for the beneficial effects.

RESULTS

The existing data is suggestive that honey is beneficial in mitigating the radiation-induced mucositis, xerostomia, healing of recalcitrant wounds in radiation exposed regions and multiple pathways mediate the beneficial effects especially, free radical scavenging, antioxidant, wound healing, anticancer, analgesic, anti-inflammatory, anabolic, anti-fatigue and anti-anaemic effects that add additional value to the use of honey as an adjunct in cancer therapy.

CONCLUSION

For the first time this review addresses the underlying pharmacological effects related to the beneficial effects of honey in radiation-induced damage, and attempts at emphasizes the lacunae that need further studies for optimizing the use of honey as an adjunct in radiotherapy of HNC. The authors suggest that future studies should be directed at understanding the detail molecular mechanisms responsible for the beneficial effects using validated cell culture and animal models of study. Large multi centric clinical trials with standardised honey is also needed to understand the clinical use of honey.

Same pollution sources for climate change might be hyperactivating the NLRP3 inflammasome and exacerbating neuroinflammation and SARS mortality

We have reviewed a considerable amount of recent scientific papers relating inflammation caused by air pollution with chronic and severe medical conditions. Furthermore, there are evidences relating organ inflammation caused by not only outdoor long-term but also short-term inhaled radioisotopes contained in high polluted air or in household natural radioactive background aerosols, in addition to SARS-COV-2 attached to bioaerosols, which are related with a worst evolution of severe acute respiratory syndrome patients. Reactive oxygen species (ROS) production induced by the interaction with environmental ionizing radiation contained in pollution is pointed out as a critical mechanism that predispose mainly to elder population, but not excluding young subjects, presenting previous chronic conditions of lung inflammation or neuroinflammation, which can lead to the most serious consequences.

RADIATION DAMAGE OF THE NERVOUS SYSTEM AND ENDOCANABINOIDS

The review analyzes the change of the existing paradigm of high radioresistance of the nervous system according tothe results of the study of neuropsychiatric disorders in in the aftermath of the Chornobyl accident in both earlyand remote post-accident period. The participation of the endocannabinoid system in ensuring homeostasis andpathology formation, potential possibilities of using cannabis drugs, agonists and antagonists of endocannabinoidreceptors for the treatment of early and long-term effects of radiation are considered.

Radioprotective Effect of Flavonoids on Ionizing Radiation-Induced Brain Damage

Patients receiving brain radiotherapy may suffer acute or chronic side effects. Ionizing radiation induces the production of intracellular reactive oxygen species and pro-inflammatory cytokines in the central nervous system, leading to brain damage. Complementary Chinese herbal medicine therapy may reduce radiotherapy-induced side effects. Flavonoids are a class of natural products which can be extracted from Chinese herbal medicine and have been shown to have neuroprotective and radioprotective properties. Flavonoids are effective antioxidants and can also inhibit regulatory enzymes or transcription factors important for controlling inflammatory mediators, affect oxidative stress through interaction with DNA and enhance genomic stability. In this paper, radiation-induced brain damage and the relevant molecular mechanism were summarized. The radio-neuro-protective effect of flavonoids, i.e., antioxidant, anti-inflammatory and maintaining genomic stability, were then reviewed. We concluded that flavonoids treatment may be a promising complementary therapy to prevent radiotherapy-induced brain pathophysiological changes and cognitive impairment.

Burns Impair Blood-Brain Barrier and Mesenchymal Stem Cells Can Reverse the Process in Mice

Neurological syndromes are observed in numerous patients who suffer burns, which add to the economic burden of societies and families. Recent studies have implied that blood-brain barrier (BBB) dysfunction is the key factor that induces these central nervous system (CNS) syndromes in peripheral traumatic disease, e.g., surgery and burns. However, the effect of burns on BBB and the underlying mechanism remains, largely, to be determined. The present study aimed to investigate the effect of burns on BBB and the potential of umbilical cord-derived mesenchymal stem cells (UC-MSCs), which have strong anti-inflammatory and repairing ability, to protect the integrity of BBB. BBB permeability was evaluated using dextran tracer (immunohistochemistry imaging and spectrophotometric quantification) and western blot, interleukin (IL)-6, and IL-1β levels in blood and brain were measured by enzyme-linked immunosorbent assay. Furthermore, transmission electron microscopy (TEM) was used to detect transcellular vesicular transport (transcytosis) in BBB. We found that burns increased mouse BBB permeability to both 10-kDa and 70-kDa dextran. IL-6 and IL-1β levels increased in peripheral blood and CNS after burns. In addition, burns decreased the level of tight junction proteins (TJs), including claudin-5, occludin, and ZO-1, which indicated increased BBB permeability due to paracellular pathway. Moreover, increased vesicular density after burns suggested increased transcytosis in brain microvascular endothelial cells. Finally, administering UC-MSCs at 1 h after burns effectively reversed these adverse effects and protected the integrity of BBB. These results suggest that burns increase BBB permeability through both paracellular pathway and transcytosis, the potential mechanism of which might be through increasing IL-6 and IL-1β levels and decreasing Mfsd2a level, and appropriate treatment with UC-MSCs can reverse these effects and protect the integrity of BBB after burns.

The protective role of short-chain fatty acids acting as signal molecules in chemotherapy- or radiation-induced intestinal inflammation

A compelling set of links between chemotherapy- or radiation-induced intestinal inflammation and microbial dysbiosis has emerged. It is the proportional imbalance between pathogenic and beneficial bacteria that aggravates intestinal mucositis. Bacteria that ferment fibers and produce short-chain fatty acids (SCFAs), (such as acetate, propionate, and butyrate) are typically reduced in the mucosa and feces of patients undergoing cancer therapy. In contrast, increasing lipopolysaccharide-producing bacteria result in proinflammatory events by interacting with Toll-like receptors. A collective acceptance is that bacterial metabolites are critical in recovering intestinal homeostasis. We herein review evidence supporting the positive roles carried out by SCFAs. SCFAs, acting as signaling molecules, directly activate G-coupled-receptors and inhibit histone deacetylases. Thus, SCFAs are able to strengthen the gut barrier and regulate immunomodulatory functions. Furthermore, it is possible to reverse intestinal microbial dysbiosis and subsequently suppress the secretion of proinflammatory cytokines by directly applying SCFA-producing bacteria. In addition, anticancer effects of SCFAs have proved in the colorectal cancer. In this review, we discuss microbial dysbiosis and its impact on chemotherapy- or radiation-induced intestinal mucositis. Moreover, we summarize the mechanisms of SCFA production and its effects on intestinal mucositis. This review suggests the therapeutic potential of SCFAs for the management of chemotherapy- or radiation-induced intestinal inflammation.

Alumina Ceramic Exacerbates the Inflammatory Disease by Activation of Macrophages and T Cells

(1) Background: Aluminum oxide (Al₂O₃) ceramic is one of the materials used for artificial joints, and it has been known that their fine particles (FPs) are provided by the wear of the ceramic. Al₂O₃ FPs have been shown to induce macrophage activation in vitro; however, the inflammatory effect in vivo has not been studied. (2) Methods: We examined the in vivo effect of Al₂O₃ FPs on the innate and adaptive immune cells in the mice. (3) Results: Al₂O₃ FPs promoted the activation of spleen macrophages; however, conventional dendritic cells (cDCs), plasmacytoid DCs (pDCs), and natural killer (NK) cells were not activated. In addition, increases in the CD4 and CD8 T cells was induced in the spleens of the mice treated with Al₂O₃ FPs, which differentiated into interferon-gamma (IFN-γ)-producing helper T1 (Th1) and cytotoxic T1 (Tc1) cells. Finally, the injection of Al₂O₃ FPs exacerbated dextran sulfate sodium (DSS)-induced inflammation in the colon, mediated by activated and increased number of CD4 and CD8 T cells. (4) Conclusions: These data demonstrate that FPs of Al₂O₃ ceramic may contribute to the exacerbation of inflammatory diseases in the patients.

Metformin fights against radiation-induced early developmental toxicity

Nuclear pollution intertwined accidental irradiation not only triggers acute and chronic radiation syndromes, but also endangers embryonic development in sight of uncontrollable gene mutation. Metformin (MET), a classic hypoglycemic drug, has been identified to possess multiple properties. In this study, we explored the radioprotective effects of MET on the developmental abnormalities and deformities induced by irradiation among three "star drugs". Specifically, zebrafish (Danio rerio) embryos exposed to 5.2 Gy gamma irradiation at 4 h post fertilization (hpf) showed overt developmental toxicity, including hatching delay, hatching rate decrease, developmental indexes reduction, morphological abnormalities occurrence and motor ability decline. However, MET treatment erased the radiation-induced phenotypes. In addition, MET degraded inflammatory reaction, hinders apoptosis response, and reprograms the development-related genes expression, such as sox2, sox3, sox19a and p53, in zebrafish embryos following radiation challenge. Together, our findings provide novel insights into metformin, and underpin that metformin might be employed as a promising radioprotector for radiation-induced early developmental toxicity in pre-clinical settings.

Melatonin as a Radio-Sensitizer in Cancer

Radiotherapy is one of the treatments of choice in many types of cancer. Adjuvant treatments to radiotherapy try, on one hand, to enhance the response of tumor cells to radiation and, on the other hand, to reduce the side effects to normal cells. Radiosensitizers are agents that increase the effect of radiation in tumor cells by trying not to increase side effects in normal tissues. Melatonin is a hormone produced mainly by the pineal gland which has an important role in the regulation of cancer growth, especially in hormone-dependent mammary tumors. Different studies have showed that melatonin administered with radiotherapy is able to enhance its therapeutic effects and can protect normal cells against side effects of this treatment. Several mechanisms are involved in the radiosensitization induced by melatonin: increase of reactive oxygen species production, modulation of proteins involved in estrogen biosynthesis, impairment of tumor cells to DNA repair, modulation of angiogenesis, abolition of inflammation, induction of apoptosis, stimulation of preadipocytes differentiation and modulation of metabolism. At this moment, there are very few clinical trials that study the therapeutic usefulness to associate melatonin and radiotherapy in humans. All findings point to melatonin as an effective adjuvant molecule to radiotherapy in cancer treatment.

Protective Effect of Selenium-L-methionine on Radiation-induced Acute Pneumonitis and Lung Fibrosis in Rat

BACKGROUND

In this study, we aimed to detect the changes in the level of interleukin (IL)-4 and IL-13 cytokines and their downstream genes including interleukin-13 receptor subunit alpha-2 (IL13Ra2), interleukin-4 receptor subunit alpha-1 (IL4Ra1), dual oxidase 1 (DUOX1) and dual oxidase 2 (DUOX2). The protective effects of Selenium-L-methionine on radiation-induced histopathological damages and changes in the level of these cytokines and genes were detected.

METHODS

Four groups of 20 rats (5 rats in each) namely, control; Selenium-L-methionine, radiation and radiation plus Selenium-L-methionine were used in this study. 4 mg/kg of Selenium-Lmethionine was administered 1 day before irradiation and five consecutive days after irradiation. Irradiation was done using a dose of 15 Gy 60Co gamma rays at 109 cGy/min. All rats were sacrificed 10 weeks after irradiation for detecting changes in IL-4 and IL-13 cytokines, the expressions of IL13Ra2, IL4Ra1, Duox1 and Duox2 and histopathological changes.

RESULTS

The level of IL-4 but not IL-13 increased after irradiation. This was associated with increased expression of IL4Ra1, Duox1 and Duox2, in addition to changes in morphological properties. Selenium-L-methionine could attenuate all injury markers following lung irradiation.

CONCLUSION

Selenium-L-methionine can protect lung tissues against toxic effects of ionizing radiation. It is possible that the modulation of immune responses and redox interactions are involved in the radioprotective effect of this agent.