Oxidative Stress in Radiation-Induced Cardiotoxicity

Pyrrolidine Dithiocarbamate Might Mitigate Radiation-Induced Heart Damage at an Early Stage in Rats

Objective: Radiation-induced heart damage (RIHD) is becoming an increasing concern due to offsetting clinical benefits of radiotherapy to a certain extent. Pyrrolidine dithiocarbamate (PDTC) as an antioxidant has been implicated in cardioprotective effects. We aimed to investigate whether pyrrolidine dithiocarbamate could attenuate heart damage at an early stage post-irradiation and unveil the potential mechanisms. Methods: A total of 15 adult male Sprague-Dawley rats were randomized into the control, irradiation (IR), and PDTC plus irradiation (PDTC + IR) groups. Hearts were irradiated with a single fraction of 20.0 Gy. Rats received daily intraperitoneal injection of PDTC for 14 days. At the 14th day post-irradiation, echocardiography was performed, and rats were killed. Morphological damage was examined by hematoxylin-eosin (HE) stain and Masson's trichrome stain. The collagen volume fraction (CVF) was applied for semi-quantitative analysis. The protein levels were analyzed by Western blot and mRNA levels by quantitative real-time PCR. Results: No significant damage to systolic function of left ventricular was induced at an early stage post-irradiation. HE staining of cardiac tissue showed that the disordered arrangement of myocardial cells and abnormal cell infiltration were alleviated in the PDTC + IR group. The increased CVF in the irradiation group was inhibited in the PDTC + IR group (22.05 ± 2.64% vs. 9.99 ± 1.65%, p < 0.05). The protein levels of nuclear factor-kappa B (NF-κB), hypoxia-inducible factor-1α (HIF-1α), and COL-1 were downregulated after treatment with PDTC (p < 0.05), and there was a declining trend in the protein of the connective tissue growth factor (CTGF). The mRNA expression of NF-κB and HIF-1α in the PDTC plus irradiation group was lower than that in the irradiation group (p < 0.05), and there was a declining trend in the mRNA expression of the connective tissue growth factor and COL-1. Conclusion: PDTC alleviates myocardial cell disordered arrangement, abnormal cell infiltration, and pro-fibrotic change at an early stage in rats with radiation-induced heart damage. Such a protective effect is closely associated with the downregulation of NF-κB.

Betaine modulates MIF-mediated oxidative stress, inflammation, and fibrogenesis in Thioacetamide-induced Nephrotoxicity

BACKGROUND

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine with chemokine properties released by various immune and nonimmune cells. It contributes to the pathogenesis of many inflammatory, autoimmune diseases and malignant tumors.

OBJECTIVE

Our study aimed to investigate the role of betaine in the modulation of MIF-mediated oxidative stress, inflammation, and fibrogenesis during toxic kidney damage induced by thioacetamide (TAA).

METHODS

The experiment is performed on wild-type and knockout MIF-/- C57BL/6 mice. They are randomly divided into groups: Control; Bet-group, received betaine (2% wt/v dissolved in drinking water); MIF-/- mice group; MIF-/-+Bet; TAA-group, treated with TAA (200 mg/kg b.w.), intraperitoneally, 3x/week/8 weeks); TAA+Bet; MIF-/-+TAA, and MIF-/-+TAA+Bet group. After eight weeks of treatment, animals are sacrificed and kidney samples are taken to determine oxidative stress parameters, proinflammatory cytokines, profibrogenic factors, and histopathology of renal tissue Results: In MIF-/-mice, TAA decreases malondialdehyde (MDA) concentration, IL-6, tumor necrosis factor-alpha (TNF-, transforming growth factor-beta 1 (TGF-1) and plateled-derived growth factor-BB (PDGF-BB) and increases superoxide dismutases (SOD) and catalase (CAT) activities, as well as glutathione (GSH) content in kidneys, compared to TAA group. Betaine alleviates the mechanism of MIF-mediated effects in TAA-induced nephrotoxicity, reducing MDA, IL-6, TNF-, TGF-1, and PDGF-BB, and increasing SOD and CAT activity, as well as GSH levels.

CONCLUSION

MIF mediates TAA-induced nephrotoxicity by increasing oxidative stress, inflammation, and profibrogenic mediators. MIF-targeted therapy could potentially alleviate oxidative stress and inflammation in the kidney, as well as pathohistological changes in renal tissue, but the exact mechanism of its action is not completely clear. Betaine alleviates MIF nephrotoxic effects by increasing the antioxidative capacity of kidney cells, and decreasing lipid peroxidation and cytokine production in the renal tissue. It suggests that betaine can be used for the prevention of kidney damage.

Effect of Hydrogen Inhalation Therapy on Hearing Loss of Patients With Nasopharyngeal Carcinoma After Radiotherapy

Objective

To evaluate the clinical efficacy and safety of hydrogen inhalation in improving hearing loss in patients with long-term survival of nasopharyngeal carcinoma after radiotherapy.

Methods

The eustachian tube dysfunction score, pure tone air conduction threshold, bone conduction threshold, the score of tympanogram and otoscope were prospectively observed in patients with deafness after radiotherapy only or combined radiotherapy and chemotherapy for nasopharyngeal carcinoma. Paired t test and one-way analysis of variance were used to analyze the data before and after treatment.

Results

A total of 17 patients were observed. The median time from radiotherapy to now was 228 months, and the median time from the diagnose of deafness to now was 92 months. After 4 weeks of hydrogen inhalation, the score of eustachian tube dysfunction, air conduction and bone conduction hearing thresholds were significantly reduced, P values were 0.0293, 0.0027, 0.0404, respectively. The mean air-bone gap, the score of otoendoscopy and tympanogram were also decreased, but the differences were not significant (P = 0.2079, P = 0.0536, P = 0.1056). Patients with radiotherapy alone and concurrent chemo-radiotherapy had significantly lower air conduction hearing threshold after hydrogen absorption (P = 0.0142, P = 0.0495). The results of air and bone hearing thresholds before, 4 and 12 weeks after hydrogen inhalation showed a descending trend. The air and bone hearing thresholds before hydrogen inhalation were 74.69 ± 27.03 dB and 45.70 ± 21.58 dB, respectively. At the 12th week, the mean values of air and bone hearing thresholds were the lowest, which were 66.88 ± 20.88 dB and 40.94 ± 18.93 dB, respectively, but there was no significant difference in air and bone hearing thresholds among all groups (P = 0.6755, P = 0.7712). After hydrogen inhalation treatment, no adverse reactions such as nosebleed, chest pain, dyspnea, nausea, vomiting, dizziness, earache and allergic reaction were observed.

Conclusion

This is the first prospective study on the effect of hydrogen inhalation on hearing improvement in patients with deafness after radiotherapy/chemotherapy for nasopharyngeal carcinoma, suggesting that continuous hydrogen inhalation may be an alternative rehabilitation therapy for these patients.

Long-Term Cardiac Damage Associated With Abdominal Irradiation in Mice

Aims: Irradiation is an effective treatment for tumors but has been associated with cardiac dysfunction. However, the precise mechanisms remain incompletely elucidated. This study investigated the long-term cardiac damage associated with abdominal irradiation and explored possible mechanisms.

Methods and Results: Wild-type C57BL6/J mice were divided into two groups: untreated controls (Con) and treatment group receiving 15 Gy of abdominal gamma irradiation (AIR). Both groups received normal feeding for 12 months. The AIR group showed reductions in left ventricular ejection fraction (LVEF), fractional shortening (FS), left ventricular end-diastolic internal diameter (LVID; d), left ventricular end-diastolic volume (LV Vol. diastolic volume (LV Vol; d) and mitral transtricuspid flow late diastolic filling velocity (MV A). It also showed increased fibrosis, reduced conduction velocity and increased conduction heterogeneity. Non-targeted metabolomics showed the differential metabolites were mainly from amino acid metabolism. Further KEGG pathway annotation and enrichment analysis revealed that abnormalities in arginine and proline metabolism, lysine degradation, d-arginine and d-ornithine metabolism, alanine, aspartate and glutamate metabolism, and arginine biosynthesis.

Conclusion: Abdominal irradiation causes long-term damage to the non-irradiated heart, as reflected by electrical and structural remodeling and mechanical dysfunction associated with abnormal amino acid biosynthesis and metabolism.

Exosomes: Potential Player in Endothelial Dysfunction in Cardiovascular Disease

Exosomes are spherical bilayer membrane vesicles with an average diameter of 40-100 nm. These particles perform a wide range of biological activities due to their contents, including proteins, nucleic acids, lipids, lncRNA, and miRNA. Exosomes are involved in inflammation induction, oxidative stress and apoptosis, which can be effective in endothelial dysfunction. Due to the induction of mentioned processes in the endothelial cells, the intercellular connections are destroyed, cell permeability increases and finally cell efficiency decreases and functional defects occur. Cardiovascular disease (CVDs) are of consequences of endothelial dysfunction. Thus by identifying the exosome signaling pathways, which induce inflammation, oxidative stress, and apoptosis, endothelial dysfunction and subsequently CVDs can be reduced; exosomes can be used for appropriate target therapy.

Multi-faced roles of reactive oxygen species in anti-tumor T cell immune responses and combination immunotherapy

T cells play a central role in anti-tumor immunity, and reactive oxygen species (ROS) lie at the crossroad on the anti-tumor T cell responses. To activate efficient T cell immunity, a moderate level of ROS is needed, however, excessive ROS would cause toxicity to the T cells, because the improper level leads to the formation and maintenance of an immunosuppressive tumor microenvironment. Up to date, strategies that modulate ROS, either increasing or decreasing, have been widely investigated. Some of them are utilized in anti-tumor therapies, showing inevitable impacts on the anti-tumor T cell immunity with both obverse and reverse sides. Herein, the impacts of ROS-increasing and ROS-decreasing treatments on the T cell responses in the tumor microenvironment are reviewed and discussed. At the same time, outcomes of combination immunotherapies are introduced to put forward inspirations to unleash the potential of immunotherapies.

Prediction of cardiac events following concurrent chemoradiation therapy for non-small-cell lung cancer using FDG PET

OBJECTIVE

No imaging biomarkers are available for the prediction of cardiac events following concurrent chemoradiation therapy (CCRT) for non-small-cell lung cancer (NSCLC). We evaluated whether F-18 fluorodeoxyglucose positron emission tomography (FDG PET) early after CCRT, in addition to cardiac dosimetry, could predict late cardiac events in NSCLC.

METHODS

We retrospectively enrolled 133 consecutive patients with locally advanced, unresectable stage III NSCLC, who underwent FDG PET early after CCRT and survived at least 6 months. The primary endpoint was cardiac event ≥ grade 2 according to the Common Terminology Criteria for Adverse Events (version 5.0). Myocardial FDG uptake was measured and its association with the risk of cardiac events was evaluated.

RESULTS

FDG PET was performed after a median interval of 11 days of completing CCRT. Overall, 42 (32%) patients experienced cardiac events during a median follow-up of 45 months. The mean heart dose, maximum left ventricular (LV) standardized uptake value (SUV), changes in maximum and mean LV SUV, right ventricular uptake, tumor stage, white blood cell count, and diabetes were associated with cardiac events in univariable analysis. In multivariable analysis, maximum LV SUV (cutoff > 12.84; hazard ratio [95% confidence interval] = 2.140 [1.140-4.016]; p = 0.018) was an independent predictor of cardiac events along with the mean heart dose (> 11.1 Gy; 3.646 [1.792-7.417]; p < 0.001) and tumor stage (IIIB; 1.986 [1.056-3.734]; p = 0.033). It remained predictive of cardiac events in those with higher mean heart dose but not in those with lower mean heart dose.

CONCLUSIONS

Early FDG PET after CCRT for NSCLC could aid in predicting late cardiac events, especially in patients with higher mean heart dose.

Evaluating the role of propolis and bee venom on the oxidative stress induced by gamma rays in rats

Honeybee products consist of many substances, which have long been known for their medicinal and health-promoting properties. This study set out to appraise the protective potential of Egyptian propolis (EP) and bee venom (BV) separately or combined against total body irradiation (TBI) induced oxidative injury in rats. Besides, we assessed the bioactive components in EP and BV using HPLC and UPLC/ ESI-MS analysis in the positive ion mode. The animals were subjected to a source of gamma ionizing radiation at a dose of 6 Gy. Propolis and BV were administered independently and in combination before 14 days of γ-irradiation. Liver and kidney functions were estimated besides, DNA damage index (8- OHdG) by ELISA. Antioxidants, including glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) were detected. Gene expression technique investigated for BAX, BCL2, and in plasma also miR125b expression in serum of rats. Besides, the histopathological for the brain, liver, kidney, and heart were investigated. In addition, lipid peroxidation was investigated in plasma and in the previous organs. The present results provide opportunities to advance the use of bee products as promising medicinal sources.

MicroRNA-223-3p Protect Against Radiation-Induced Cardiac Toxicity by Alleviating Myocardial Oxidative Stress and Programmed Cell Death via Targeting the AMPK Pathway

Objectives: Radiotherapy improves the survival rate of cancer patients, yet it also involves some inevitable complications. Radiation-induced heart disease (RIHD) is one of the most serious complications, especially the radiotherapy of thoracic tumors, which is characterized by cardiac oxidative stress disorder and programmed cell death. At present, there is no effective treatment strategy for RIHD; in addition, it cannot be reversed when it progresses. This study aims to explore the role and potential mechanism of microRNA-223-3p (miR-223-3p) in RIHD.

Methods: Mice were injected with miR-223-3p mimic, inhibitor, or their respective controls in the tail vein and received a single dose of 20 Gy whole-heart irradiation (WHI) for 16 weeks after 3 days to construct a RIHD mouse model. To inhibit adenosine monophosphate activated protein kinase (AMPK) or phosphodiesterase 4D (PDE4D), compound C (CompC) and AAV9-shPDE4D were used.

Results: WHI treatment significantly inhibited the expression of miR-223-3p in the hearts; furthermore, the levels of miR-223-3p decreased in a radiation time-dependent manner. miR-223-3p mimic significantly relieved, while miR-223-3p inhibitor aggravated apoptosis, oxidative damage, and cardiac dysfunction in RIHD mice. In addition, we found that miR-223-3p mimic improves WHI-induced myocardial injury by activating AMPK and that the inhibition of AMPK by CompC completely blocks these protective effects of miR-223-3p mimic. Further studies found that miR-223-3p lowers the protein levels of PDE4D and inhibiting PDE4D by AAV9-shPDE4D blocks the WHI-induced myocardial injury mediated by miR-223-3p inhibitor.

Conclusion: miR-223-3p ameliorates WHI-induced RIHD through anti-oxidant and anti-programmed cell death mechanisms via activating AMPK by PDE4D regulation. miR-223-3p mimic exhibits potential value in the treatment of RIHD.

"Radio-Protective Effect of Aminocaproic Acid in Human Spermatozoa"

BACKGROUND

The negative effects of ionizing radiation on organs and the reproductive system are well known and documented. Exposure to gamma radiation can lead to oligospermia, azoospermia and DNA damage. Up to date, there is no effective pharmaceutical compound for protecting the male reproductive system and sperm.

OBJECTIVE

This study aimed at investigating the ability of Ɛ-aminocaproic acid (EACA) to prevent the damage of human spermatozoa and DNA induced by ionizing radiation.

MATERIALS AND METHODS

Sperm samples were obtained from healthy volunteers (35 men; 31.50 ± 7.34 years old). There were 4 experimental groups: 1) control group (CG), 2) group exposed to maximal radiation dose 67.88 mGy (RMAX), 3) low-dose radiation (minimal) 22.62 mGy (RMIN), and 4) group treated with radiation (67.88 mGy) and EACA (dose 50 ng/ml). Sperm motility, viability, and DNA damage were assessed.

RESULTS

We observed a significant decrease in total sperm motility of the RMAX group compared to CG (p < 0.05). Sperm viability in the RMAX group was also reduced in comparison to the control (p < 0.05). A significant increase in DNA fragmentation was detected in the RMAX group. The results demonstrated that the treatment of sperm with EACA led to a decrease in the fragmentation of the sperm DNA (compared to the RMAX group) (p < 0.05).

CONCLUSION

The results indicate that EACA effectively protects human spermatozoa from DNA damage induced by ionizing radiation. Treatment of spermatozoa with EACA led to the preservation of cell motility, viability, and DNA integrity upon radiation exposure.

Impact of High-Dose Irradiation on Human iPSC-Derived Cardiomyocytes Using Multi-Electrode Arrays: Implications for the Antiarrhythmic Effects of Cardiac Radioablation

Cardiac radioablation is emerging as an alternative option for refractory ventricular arrhythmias. However, the immediate acute effect of high-dose irradiation on human cardiomyocytes remains poorly known. We measured the electrical activities of human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) upon irradiation with 0, 20, 25, 30, 40, and 50 Gy using a multi-electrode array, and cardiomyocyte function gene levels were evaluated. iPSC-CMs showed to recover their electrophysiological activities (total active electrode, spike amplitude and slope, and corrected field potential duration) within 3–6 h from the acute effects of high-dose irradiation. The beat rate immediately increased until 3 h after irradiation, but it steadily decreased afterward. Conduction velocity slowed in cells irradiated with ≥25 Gy until 6–12 h and recovered within 24 h; notably, 20 and 25 Gy-treated groups showed subsequent continuous increase. At day 7 post-irradiation, except for cTnT, cardiomyocyte function gene levels increased with increasing irradiation dose, but uniquely peaked at 25–30 Gy. Altogether, high-dose irradiation immediately and reversibly modifies the electrical conduction of cardiomyocytes. Thus, compensatory mechanisms at the cellular level may be activated after the high-dose irradiation acute effects, thereby, contributing to the immediate antiarrhythmic outcome of cardiac radioablation for refractory ventricular arrhythmias.

Cardiac inflammation and fibrosis following chemo/radiation therapy: mechanisms and therapeutic agents

The incidence of cardiovascular disorders is one of the most concerns among people who underwent cancer therapy. The heart side effects of cancer therapy may occur during treatment to some years after the end of treatment. Some epidemiological studies confirm that heart diseases are one of the most common reasons for mortality among patients that were received treatment for cancer. Experimental studies and also clinical investigations indicate that inflammatory changes such as pericarditis, myocarditis, and also fibrosis are key mechanisms of cardiac diseases following chemotherapy/radiotherapy. It seems that chronic oxidative stress, massive cell death, and chronic overproduction of pro-inflammatory and pro-fibrosis cytokines are the key mechanisms of cardiovascular diseases following cancer therapy. Furthermore, infiltration of inflammatory cells and upregulation of some enzymes such as NADPH Oxidases are a hallmark of heart diseases after cancer therapy. In the current review, we aim to explain how radiation or chemotherapy can induce inflammatory and fibrosis-related diseases in the heart. We will explain the cellular and molecular mechanisms of cardiac inflammation and fibrosis following chemo/radiation therapy, and then review some adjuvants to reduce the risk of inflammation and fibrosis in the heart.

PARK7 promotes repair in early steroid-induced osteonecrosis of the femoral head by enhancing resistance to stress-induced apoptosis in bone marrow mesenchymal stem cells via regulation of the Nrf2 signaling pathway

Novel therapies for the treatment of early steroid-induced osteonecrosis of the femoral head (SONFH) are urgently needed in orthopedics. Transplantation of bone marrow mesenchymal stem cells (BMSCs) provides new strategies for treating this condition at the early stage. However, stress-induced apoptosis of BMSCs transplanted into the femoral head necrotic area limits the efficacy of BMSC transplantation. Inhibiting BMSC apoptosis is key to improving the efficacy of this procedure. In our previous studies, we confirmed that Parkinson disease protein 7 (PARK7) is active in antioxidant defense and can clear reactive oxygen species (ROS), protect the mitochondria, and impart resistance to stress-induced apoptosis in BMSCs. In this study, we investigated the mechanism driving this PARK7-mediated resistance to apoptosis in BMSCs. Our results indicate that PARK7 promoted the disintegration of nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/Kelch-like echinacoside-associated protein 1 (Keap1) complex. The free Nrf2 then entered the nucleus and activated the genetic expression of manganese superoxide dismutase (MnSOD), catalase (CAT), glutathione peroxidase (GPx), and other antioxidant enzymes that clear excessive ROS, thereby protecting BMSCs from stress-induced apoptosis. To further explore whether PARK7-mediated resistance to stress-induced apoptosis could improve the efficacy of BMSC transplantation in early-stage SONFH, we transplanted BMSCs-overexpressing PARK7 into rats with early-stage SONFH. We then evaluated the survival of transplanted BMSCs and bone regeneration in the femoral head necrotic area of these rats. The results indicated that PARK7 promoted the survival of BMSCs in the osteonecrotic area and improved the transplantation efficacy of BMSCs on early-stage SONFH. This study provides new ideas and methods for resisting the stress-induced apoptosis of BMSCs and improving the transplantation effect of BMSCs on early-stage SONFH.

Radiation‑induced dysfunction of energy metabolism in the heart results in the fibrosis of cardiac tissues

Thoracic radiotherapy increases the risk of radiation‑induced heart damage (RIHD); however, the molecular mechanisms underlying these changes are not fully understood. The aim of the present study was to investigate the effects of radiation on the mouse heart using high‑throughput proteomics. Male C57BL/6J mice were used to establish a model of RIHD by exposing the entire heart to 16 Gy high‑energy X‑rays, and cardiac injuries were verified using a cardiac echocardiogram, as well as by measuring serum brain natriuretic peptide levels and conducting H&E and Masson staining 5 months after irradiation. Proteomics experiments were performed using the heart apex of 5‑month irradiated mice and control mice that underwent sham‑irradiation. The most significantly differentially expressed proteins were enriched in 'cardiac fibrosis' and 'energy metabolism'. Next, the cardiac fibrosis and changes to energy metabolism were confirmed using immunohistochemistry staining and western blotting. Extracellular matrix proteins, such as collagen type 1 α 1 chain, collagen type III α 1 chain, vimentin and CCCTC‑binding factor, along with metabolism‑related proteins, such as fatty acid synthase and solute carrier family 25 member 1, exhibited upregulated expression following exposure to ionizing radiation. Additionally, the myocardial mitochondria inner membranes were injured, along with a decrease in ATP levels and the accumulation of lactic acid in the irradiated heart tissues. These results suggest that the high doses of ionizing radiation used lead to structural remodeling, functional injury and fibrotic alterations in the mouse heart. Radiation‑induced mitochondrial damage and metabolic alterations of the cardiac tissue may thus be a pathogenic mechanism of RIHD.

Analysis of lncRNA-miRNA-mRNA expression pattern in heart tissue after total body radiation in a mouse model

Background

Radiation therapy is integral to effective thoracic cancer treatments, but its application is limited by sensitivity of critical organs such as the heart. The impacts of acute radiation-induced damage and its chronic effects on normal heart cells are highly relevant in radiotherapy with increasing lifespans of patients. Biomarkers for normal tissue damage after radiation exposure, whether accidental or therapeutic, are being studied as indicators of both acute and delayed effects. Recent research has highlighted the potential importance of RNAs, including messenger RNAs (mRNAs), microRNAs (miRNAs), and long non-coding RNAs (lncRNAs) as biomarkers to assess radiation damage. Understanding changes in mRNA and non-coding RNA expression will elucidate biological pathway changes after radiation.

Methods

To identify significant expression changes in mRNAs, lncRNAs, and miRNAs, we performed whole transcriptome microarray analysis of mouse heart tissue at 48 h after whole-body irradiation with 1, 2, 4, 8, and 12 Gray (Gy). We also validated changes in specific lncRNAs through RT-qPCR. Ingenuity Pathway Analysis (IPA) was used to identify pathways associated with gene expression changes.

Results

We observed sustained increases in lncRNAs and mRNAs, across all doses of radiation. Alas2, Aplnr, and Cxc3r1 were the most significantly downregulated mRNAs across all doses. Among the significantly upregulated mRNAs were cell-cycle arrest biomarkers Gdf15, Cdkn1a, and Ckap2. Additionally, IPA identified significant changes in gene expression relevant to senescence, apoptosis, hemoglobin synthesis, inflammation, and metabolism. LncRNAs Abhd11os, Pvt1, Trp53cor1, and Dino showed increased expression with increasing doses of radiation. We did not observe any miRNAs with sustained up- or downregulation across all doses, but miR-149-3p, miR-6538, miR-8101, miR-7118-5p, miR-211-3p, and miR-3960 were significantly upregulated after 12 Gy.

Conclusions

Radiation-induced RNA expression changes may be predictive of normal tissue toxicities and may indicate targetable pathways for radiation countermeasure development and improved radiotherapy treatment plans.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-02998-w.

The cardiac toxicity of radiotherapy - a review of characteristics, mechanisms, diagnosis, and prevention

PURPOSE

Radiation-induced heart disease (RIHD) is one of the most serious complications of radiotherapy. The purpose of this paper is to review recent researches about cardiac toxicity of radiotherapy in clinical characteristics, mechanisms, diagnosis, and prevention.

CONCLUSIONS

Powered by the rapid development of medicine, the overall survival (OS) of cancer has been improved significantly. Surgery, chemotherapy, and radiotherapy (RT) are three critical ways in the comprehensive treatments of cancer. There is a consensus that early diagnosis and interventions for the prevention of RIHD are crucial. This review concludes recent clinical and experimental studies on RIHD. RIHD, a heterogeneous and serious disease, is a spectrum of heart disease including myocardial disease, pericarditis, coronary artery disease, valvular heart disease, and conduction system dysfunction. Mean heart dose, biomarkers, and detecting techniques are important components in detecting heart injury. Improvements in radiotherapy regimens remain the primary goal of prevention. Further investigation is needed beyond the observation period of most of these studies.

Mitigation of Radiation-Induced Lung and Heart Injuries in Mice by Oral Sepiapterin after Irradiation

After radiation exposure, endothelium-dependent vasorelaxation is impaired due to impaired nitric oxide production. Endothelial dysfunction is characterized by uncoupled endothelial nitric oxide synthase activity, oxidation of the reduced cofactor tetrahydrobiopterin to dihydrobiopterin as one well recognized mechanism. Oral treatment with sepiapterin, a tetrahydrobiopterin precursor, decreased infiltrating inflammatory cells and cytokine levels in mice with colitis. We therefore tested whether a synthetic sepiapterin, PTC923, might mitigate radiation-induced cardiac and pulmonary injuries. C57L/J wild-type 6-8-week-old mice of both sexes received 5 Gy total-body irradiation (TBI), followed by a top-up dose of 6.5 Gy to the thorax (total thoracic dose of 11.5 Gy). Starting from 24 h postirradiation, mice were treated once daily with 1 mg/kg PTC923 for six days by oral gavage. Assessment of lung injury by breathing rate was measured every other week and echocardiography to assess heart function was performed at different time points (8, 30, 60, 90 and 180 days). Plasma proteins (fibrinogen, neutrophil elastase, C-reactive protein, and IL-6) were assessed as well. TBI induced a reduction in cardiac contractile reserve and an impairment in diastolic function restored by daily oral PTC923. Postirradiation lung injury was significantly delayed by PTC923. TBI mice treated with PTC923 experienced a longer survival compared to nonirradiated mice (71% vs. 40% of mice alive after 180 days). PTC923-treated mice showed a reduction in inflammatory mediators, especially IL-6 and IL-1b. In conclusion, these findings support the proposal that PTC923 is a potential mitigator of cardiac and lung injury caused by TBI.

New progress in elucidating the relationship between cancer therapy and cardiovascular toxicity

Onco-cardiology is an emerging field linking cancer with cardiovascular injury. Understanding the mechanism of cardiac injury helps improve the quality of life of cancer survivors. A series of studies on adverse reactions to cancer or oncological treatments has indicated that adverse cardiovascular events related to cancer treatments may occur over a longer period of survival, and even years after therapy has concluded. Current cancer therapies, including chemotherapy, radiotherapy, targeted therapy, and immunotherapy, have been found to have latent cardiovascular toxicity. These toxic effects are often progressive and irreversible and ultimately lead to cardiovascular events such as heart failure, hypertension, coronary heart diseases, arrhythmia, and thromboembolism. Therefore, more emphasis should be placed on revealing the mechanism of cancer treatment-related cardiovascular toxicity. This would help to guide prevention, diagnosis, and treatment of CVDs in cancer survivors.

Mesenchymal stem cell-derived extracellular vesicles as probable triggers of radiation-induced heart disease

BACKGROUND

Radiation-induced heart disease has been reported, but the underlying mechanisms remain unclear. Mesenchymal stem cells (MSCs), also residing in the heart, are highly susceptible to radiation. We examined the hypothesis that the altered secretion of extracellular vesicles (EVs) from MSCs is the trigger of radiation-induced heart disease.

METHODS

By exposing human placental tissue-derived MSCs to 5 Gy γ-rays, we then isolated EVs from the culture medium 48 h later and evaluated the changes in quantity and quality of EVs from MSCs after radiation exposure. The biological effects of EVs from irradiated MSCs on HUVECs and H9c2 cells were also examined.

RESULTS

Although the amount and size distribution of EVs did not differ between the nonirradiated and irradiated MSCs, miRNA sequences indicated many upregulated or downregulated miRNAs in irradiated MSCs EVs. In vitro experiments using HUVEC and H9c2 cells showed that irradiated MSC-EVs decreased cell proliferation (P < 0.01), but increased cell apoptosis and DNA damage. Moreover, irradiated MSC-EVs impaired the HUVEC tube formation and induced calcium overload in H9c2 cells.

CONCLUSIONS

EVs released from irradiated MSCs show altered miRNA profiles and harmful effects on heart cells, which provides new insight into the mechanism of radiation-related heart disease risks.

The Role of MIF in Hepatic Function, Oxidative Stress, and Inflammation in Thioacetamide-induced Liver Injury in Mice: Protective Effects of Betaine

BACKGROUND

Macrophage migration inhibitory factor (MIF) is a multipotent cytokine that contributes to the inflammatory response to chemical liver injury. This cytokine exhibits pro- and anti-inflammatory effects depending on the etiology and stage of liver disease.

OBJECTIVE

Our study aimed to investigate the role of MIF in oxidative stress and inflammation in the liver, and modulatory effects of betaine on MIF in thioacetamide (TAA)-induced chronic hepatic damage in mice.

METHODS

The experiment was performed on wild type and knockout MIF-/- C57BL/6 mice. They were divided into the following groups: control; Bet-group that received betaine (2% wt/v dissolved in drinking water); MIF-/- mice group; MIF-/-+Bet; TAA-group that received TAA (200 mg/kg b.w.), intraperitoneally, 3x/week/8 weeks); TAA+Bet; MIF-/-+TAA, and MIF-/-+TAA+Bet. In TAA- and Bet-treated groups, animals received the same doses. After eight weeks of treatment, blood samples were collected for biochemical analysis, and liver specimens were prepared for the assessment of parameters of oxidative stress and inflammation.

RESULTS

In MIF-/-mice, TAA reduced transaminases, γ-glutamyltranspeptidase, bilirubin, malondialdehyde (MDA), oxidative protein products (AOPP), total oxidant status (TOS), C-reactive protein (CRP), IL-6, IFN-γ, and increased thiols and total antioxidant status (TAS). Betaine attenuated the mechanism of MIF and mediated effects in TAA-induced liver injury, reducing transaminases, γ-glutamyltranspeptidase, bilirubin, MDA, AOPP, TOS, CRP, IL-6, IFN-g, and increasing thiols.

CONCLUSION

MIF is a mediator in hepatotoxic, pro-oxidative, and proinflammatoryeffects of TAA-induced liver injury. MIF-targeted therapy can potentially mitigate oxidative stress and inflammation in the liver, but the exact mechanism of its action requires further investigation. Betaine increases anti-oxidative defense and attenuates hepatotoxic effects of MIF, suggesting that betaine can be used for the prevention and treatment of liver damage.

Redox interactions-induced cardiac toxicity in cancer therapy

Cancer patients undergoing radiotherapy, chemotherapy, or targeted cancer therapy are exposed to the risk of several side effects because of the heavy production of ROS by ionizing radiation or some chemotherapy drugs. Damages to DNA, mitochondria, membrane and other organelles within normal tissue cells such as cardiomyocytes and endothelial cells lead to the release of some toxins which are associated with triggering inflammatory cells to release several types of cytokines, chemokines, ROS, and RNS. The release of some molecules following radiotherapy or chemotherapy stimulates reduction/oxidation (redox) reactions. Redox reactions cause remarkable changes in the level of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Excessive production of ROS and RNS or suppression of antioxidant defense enzymes leads to damage to critical macromolecules, which may continue for long times. Increased levels of some cytokines and oxidative injury are hallmarks of heart injury following cancer therapy. Redox reactions may be involved in several heart disorders such as fibrosis, cardiomyopathy, and endothelium injury. In the current review, we explain the cellular and molecular mechanisms of redox interactions following radiotherapy, chemotherapy, and targeted cancer therapy. Afterward, we explain the evidence of the involvement of redox reactions in heart diseases.

Asparaginyl endopeptidase (AEP) regulates myocardial apoptosis in response to radiation exposure via alterations in NRF2 activation

Radiation-induced heart disease (RIHD) leads to myocardial dysfunction and metabolic abnormalities in patients treated with thoracic irradiation which restricts the long-term survival benefits of radiotherapy. There is no specific or effective manner of intervention currently available. Asparaginyl endopeptidase (AEP) plays a pivotal role in the maintenance of cellular functions through regulating proteolytic cleavage as peptidase enzyme. We aimed to investigate the role of unique cardiac AEP in cardiac function by modulating key signaling elements in the myocardium. The murine heart was exposed to a single dose of 14 Gy radiation. Cellular signaling and apoptosis was analyzed in human and rat cardiomyocytes treated with various doses of radiation, we observed expression of AEP was increased by immunohistochemical staining in murine heart exposed to radiation. The AEP production along with its increased level of mRNA expression was associated with increased doses of radiation (0, 2, 5, 10 Gy) in cardiomyocytes. The myocardial cells transfected with AEP overexpression showed overall cellular viability enhancement, DNA damage inhibition, the foci formation of γ-H2AX suppressed and DNA repair enhancement significantly after radiation exposure. Small interfering RNA-mediated AEP knockdown was with reduced cardiomyocyte viability, elevated apoptotic rate, increased γ-H2AX foci formation and inhibited DNA repair as well after irradiation. After radiation exposure of 10 Gy, the expression of AEP increased in P53 overexpressing cardiomyocytes and decreased in the P53 knockdown cells, indicates that radiation-induced expression of AEP might be regulated by P53. Moreover, treatments with either AEP overexpression or knockdown showed enhanced NRF2 activity in the nuclear or suppressed NRF2 expression in the cytoplasm of myocardial cells after irradiation, respectively, defined a possible regulatory effect of AEP associated with diminished NRF2 translocation and activation by radiation exposure, including impair myocardium and myocardial apoptosis. These findings suggest that increased levels of AEP in failing myocardium after irradiation is mediated by P53 and regulate a novel pathway that involves NRF2 activation. AEP is essential for maintaining cellular redox homeostasis of cardiac function.

Genetic Variability of Antioxidative Mechanisms and Cardiotoxicity after Adjuvant Radiotherapy in HER2-Positive Breast Cancer Patients

Background

Breast cancer treatment is associated with the occurrence of various cardiac adverse events. One of the mechanisms associated with cardiotoxicity is oxidative stress, against which cells are protected by antioxidative enzymes. Genetic variability of antioxidative enzymes can affect enzyme activity or expression, which modifies the ability of cells to defend themselves against oxidative stress and could consequently contribute to the occurrence of treatment-related cardiotoxicity. Our aim was to evaluate the association of common polymorphisms in antioxidative genes with cardiotoxicity after adjuvant radiotherapy (RT) in HER2-positive breast cancer patients.

Methods

Our retrospective study included 101 HER2-positive early breast cancer patients who received trastuzumab and adjuvant RT. We isolated DNA from buccal swabs and used competitive allele-specific PCR for genotyping of PON1 rs854560 and rs662, GSTP1 rs1138272 and rs1695, SOD2 rs4880, CAT rs1001179, and HIF1 rs1154965 polymorphisms. N-terminal pro B-type natriuretic peptide (NT-proBNP), left ventricular ejection fraction, and NYHA class were used as markers of cardiotoxicity. We used logistic regression to evaluate the association of genetic factors with markers of cardiotoxicity.

Results

Carriers of at least one polymorphic PON1 rs854560 allele were less likely to have increased NT-proBNP (OR = 0.34; 95% CI = 0.15-0.79; P = 0.012), even after adjustment for age (OR = 0.35; 95% CI = 0.15-0.83; P = 0.017). Carriers of at least one polymorphic PON1 rs662 allele were more likely to have increased NT-proBNP (OR = 4.44; 95% CI = 1.85-10.66; P = 0.001), even after adjustment for age (OR = 5.41; 95% CI = 2.12-13.78; P < 0.001). GSTP1 rs1695 was also associated with decreased NT-proBNP in the multivariable analysis (P = 0.026), while CAT rs1001179 was associated with NYHA class in the univariable (P = 0.012) and multivariable analysis (P = 0.023).

Conclusion

In our study, polymorphisms PON1 rs662 and rs854560, CAT rs1001179, and GSTP1 rs1695 were significantly associated with the occurrence of cardiac adverse events after adjuvant RT and could serve as biomarkers contributing to treatment personalization.

Dexrazoxane ameliorates radiation-induced heart disease in a rat model

Treatment of thoracic tumors with radiotherapy can lead to severe cardiac injury. We investigated the effects of dexrazoxane, a USFDA-approved cardioprotective drug administered with chemotherapy, on radiation-induced heart disease (RIHD) in a rat model. Male Sprague-Dawley rats were irradiated with a single dose of 20 Gy to the heart and treated with dexrazoxane at the time of irradiation and for 12 subsequent weeks. Dexrazoxane suppressed radiation-induced myocardial apoptosis and significantly reversed changes in serum cardiac troponin I levels and histopathological characteristics six months post-radiation. Treatment with dexrazoxane did not alter the radiosensitivity of thoracic tumors in a tumor formation experiment using male nude Balb/C mice with tumors generated by H292 cells. Dexrazoxane reduced the accumulation of reactive oxygen species in rat cardiac tissues, but not in tumors in nude mice. Transcriptome sequencing showed that IKBKE, MAP3K8, NFKBIA, and TLR5, which are involved in Toll-like receptor signaling, may be associated with the anti-RIHD effects of dexrazoxane. Immunohistochemistry revealed that dexrazoxane significantly decreased NF-κB p65 expression in cardiomyocytes. These findings suggest dexrazoxane may protect against RIHD by suppressing apoptosis and oxidative stress in cardiomyocytes.

Characterization of Cardiac, Vascular, and Metabolic Changes in Young Childhood Cancer Survivors

Background: Childhood cancer survivors (CCS) are at an increased risk for cardiovascular diseases (CVD). It was the primary aim of this study to determine different measures of cardiac, carotid, lipid, and apolipoprotein status in young adult CCS and in healthy controls. Methods: Cardiac and common carotid artery (CCA) structure and function were measured by ultrasonography. Lipids and apolipoproteins were measured in the blood. Peripheral arterial endothelial vasomotor function was assessed by measuring digital reactive hyperemia index (PAT-RHI) using the Endo-PAT 2000. Results: Fifty-three CCS (20-30 years, 35 men) and 53 sex-matched controls were studied. The CCS cohort was divided by the median dose of anthracyclines into a low anthracycline dose (LAD) group (50-197 mg/m², n = 26) and a high anthracycline dose (HAD) group (200-486 mg/m², n = 27). Carotid distensibility index (DI) and endothelial function determined by PAT-RHI were both lower in the CCS groups compared with controls (p < 0.05 and p = 0.02). There was no difference in carotid intima media thickness. Atherogenic apolipoprotein-B (Apo-B) and the ratio between Apo-B and Apoliprotein-A1 (Apo-A1) were higher in the HAD group compared with controls (p < 0.01). Apo-B/Apo-A1-ratio was over reference limit in 29.6% of the HAD group, in 15.4% of LAD group, and in 7.5% of controls (p = 0.03). Measured lipid markers (low density lipoprotein and total cholesterol and triglycerides) were higher in both CCS groups compared with controls (p < 0.05). Systolic and diastolic function were measurably decreased in the HAD group, as evidenced by lower EF (p < 0.001) and lower é-wave (p < 0.005) compared with controls. CCA DI correlated with Apo-B/Apo-A1-ratio and Apo-A1. Follow-up time after treatment correlated with decreased left ventricular ejection fraction (p = 0.001). Conclusion: Young asymptomatic CCS exhibit cardiac, vascular, lipid, and apolipoprotein changes that could account for increased risk for CVD later in life. These findings emphasize the importance of cardiometabolic monitoring even in young CCS.

Radiation-induced H3K9 tri-methylation in E-cadherin promoter during lung EMT: in vitro and in vivo approaches using vanillin

Radiotherapy is an important treatment regime for lung cancer, worldwide. However, radiation-induced pneumonitis and fibrosis are the treatment-limiting toxicities among patients who have undergone radiotherapy. The epithelial cells via epithelial to mesenchymal transition [EMT] acquires mesenchymal phenotype, which ultimately leads to fibrosis. Many investigations are focussed on understanding the signalling pathways mediating in EMT, however, the role of histone methylation is less understood in radiation-induced lung EMT. In the present study, we analysed the effect of vanillin, an antioxidant, on histone methylation during radiation-induced EMT. The thoracic region of Wistar rats was irradiated with a fractionated dose of X-ray (3 Gy/day) for two weeks (total of 30 Gy). The irradiated animals were sacrificed at the 8th and 16th weeks and tissues were used for analyses. Our data showed that radiation decreased the level of antioxidant enzymes such as SOD, catalase and reduced glutathione that would ultimately enhance oxidative stress in the tissues. Histopathological analysis revealed that radiation increased the infiltration of inflammatory cells to the tissue injury site. Total global histone methylation was increased upon irradiation, which was effectively prevented by vanillin administration. Vanillin enhanced E-cadherin expression and decreased the mesenchymal markers N-cadherin and vimentin in the irradiated lung tissue. The ChIP-qPCR analysis suggested that snail expression in the nucleus might involve in the enrichment of suppressive marker H3K9me3 on the E-cadherin promoter. Finally, we suggested that vanillin administration decreased radiation-induced oxidative stress and EMT expression. Additionally, irradiation increased the H3K9 methylation status with nuclear translocation of snail during lung EMT.

Caffeine Targets SIRT3 to Enhance SOD2 Activity in Mitochondria

Caffeine is chemically stable and not readily oxidized under normal physiological conditions but also has antioxidant effects, although the underlying molecular mechanism is not well understood. Superoxide dismutase (SOD) 2 is a manganese-containing enzyme located in mitochondria that protects cells against oxidative stress by scavenging reactive oxygen species (ROS). SOD2 activity is inhibited through acetylation under conditions of stress such as exposure to ultraviolet (UV) radiation. Sirtuin 3 (SIRT3) is the major mitochondrial nicotinamide adenine dinucleotide (NAD⁺)-dependent deacetylase, which deacetylates two critical lysine residues (lysine 68 and lysine 122) on SOD2 and promotes its antioxidative activity. In this study, we investigated whether the antioxidant effect of caffeine involves modulation of SOD2 by SIRT3 using in vitro and in vivo models. The results show that caffeine interacts with SIRT3 and promotes direct binding of SIRT3 with its substrate, thereby enhancing its enzymatic activity. Mechanistically, caffeine bound to SIRT3 with high affinity (K_D = 6.858 × 10^–7 M); the binding affinity between SIRT3 and its substrate acetylated p53 was also 9.03 (without NAD⁺) or 6.87 (with NAD⁺) times higher in the presence of caffeine. Caffeine effectively protected skin cells from UV irradiation-induced oxidative stress. More importantly, caffeine enhanced SIRT3 activity and reduced SOD2 acetylation, thereby leading to increased SOD2 activity, which could be reversed by treatment with the SIRT3 inhibitor 3-(1H-1,2,3-triazol-4-yl) pyridine (3-TYP) in vitro and in vivo. Taken together, our results show that caffeine targets SIRT3 to enhance SOD2 activity and protect skin cells from UV irradiation-induced oxidative stress. Thus, caffeine, as a small-molecule SIRT3 activator, could be a potential agent to protect human skin against UV radiation.

Radiation-induced myocardial fibrosis: Mechanisms underlying its pathogenesis and therapeutic strategies

Radiation-induced myocardial fibrosis (RIMF) is a potentially lethal clinical complication of chest radiotherapy (RT) and a final stage of radiation-induced heart disease (RIHD). RIMF is characterized by decreased ventricular elasticity and distensibility, which can result in decreased ejection fraction, heart failure and even sudden cardiac death. Together, these conditions impair the long-term health of post-RT survivors and limit the dose and intensity of RT required to effectively kill tumour cells. Although the exact mechanisms involving in RIMF are unclear, increasing evidence indicates that the occurrence of RIMF is related to various cells, regulatory molecules and cytokines. However, accurately diagnosing and identifying patients who may progress to RIMF has been challenging. Despite the urgent need for an effective treatment, there is currently no medical therapy for RIMF approved for routine clinical application. In this review, we investigated the underlying pathophysiology involved in the initiation and progression of RIMF before outlining potential preventative and therapeutic strategies to counter this toxicity.