Ionizing radiation and heart risks

Elucidating the mechanism of action of Radix Angelica sinensis (Oliv.) Diels and Radix Astragalus mongholicus Bunge ultrafiltration extract on radiation-induced myocardial fibrosis based on network pharmacology and experimental research

Myocardial fibrosis can induce cardiac dysfunction and remodeling. Great attention has been paid to traditional chinese medicine (TCM) 's effectiveness in treating MF. Radix Angelica sinensis (Oliv.) Diels and Radix Astragalus mongholicus Bunge ultrafiltration extract (RAS-RA), which is a key TCM compound preparation, have high efficacy in regulating inflammation. However, studies on its therapeutic effect on radiation-induced myocardial fibrosis (RIMF) are rare. In this study, RAS-RA had therapeutic efficacy in RIMF and elucidated its mechanism of action. First, we formulated the prediction network that described the relation of RAS-RA with RIMF according to data obtained in different databases. Then, we conducted functional enrichment to investigate the functions and pathways associated with potential RIMF targets for RAS-RA. In vivo experiments were also performed to verify these functions and pathways. Second, small animal ultrasound examinations, H&E staining, Masson staining, transmission electron microscopy, Enzyme-linked immunosorbent assay (ELISA), Western-blotting, Immunohistochemical method and biochemical assays were conducted to investigate the possible key anti-RIMF pathway in RAS-RA. In total, 440 targets were detected in those 21 effective components of RAS-RA; meanwhile, 1,646 RIMF-related disease targets were also discovered. After that, PPI network analysis was conducted to identify 20 key targets based on 215 overlap gene targets. As indicated by the gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG) analysis results, inflammation and PI3K/AKT/mTOR pathways might have important effects on the therapeutic effects on RIMF. Molecular docking analysis revealed high binding of effective components to targets (affinity < -6 kcal/mol). Based on experimental verification results, RAS-RA greatly mitigated myocardial fibrosis while recovering the cardiac activity of rats caused by X-rays. According to relevant protein expression profiles, the PI3K/AKT/mTOR pathway was important for anti-fibrosis effect of RAS-RA. Experimental studies showed that RAS-RA improved cardiac function, decreased pathological damage and collagen fiber deposition in cardiac tissues, and improved the mitochondrial structure of the heart of rats. RAS-RA also downregulated TNF-α, IL-6, and IL-1β levels. Additionally, RAS-RA improved the liver and kidney functions and pathological injury of rat kidney and liver tissues, enhanced liver and kidney functions, and protected the liver and kidneys. RAS-RA also increased PI3K, AKT and mTOR protein levels within cardiac tissues and downregulated α-SMA, Collagen I, and Collagen III. The findings of this study suggested that RAS-RA decreased RIMF by suppressing collagen deposition and inflammatory response by inhibiting the PI3K/AKT/mTOR pathway. Thus, RAS-RA was the potential therapeutic agent used to alleviate RIMF.

Reparative effects after low-dose radiation exposure: Inhibition of atherosclerosis by reducing NETs release

OBJECTIVE

The cardiovascular system effects of environmental low-dose radiation exposure on radiation practitioners remain uncertain and require further investigation. The aim of this study was to initially investigate and explore the mechanisms by which low-dose radiation may contribute to atherosclerosis through a multi-omics joint comprehensive basic experiment.

METHODS

We used WGCNA and differential analyses to identify shared genes and potential pathways between radiation injury and atherosclerosis sequencing datasets, as well as tissue transcriptome immune infiltration level extrapolation and single-cell transcriptome data correction using the CIBERSORT deconvolution algorithm. Animal models were constructed by combining a high-fat diet with 5 Gy γ-ray whole-body low-dose ionizing radiation. The detection of NETs release was validated by enzyme-linked immunosorbent assay.

RESULTS

Analysis reveals shared genes in both datasets of post-irradiation and atherosclerosis, suggesting that immune system neutrophils may be a key node connecting radiation to atherosclerosis. NETs released by neutrophil death can influence the development of atherosclerosis. Animal experiments showed that the number of neutrophils decreased (P < 0.05) and the concentration of NETs reduced after low-dose radiation compared with the control group, and the concentration of NETs significantly increased (P < 0.05) in the HF group. Endothelial plaques were significantly increased in the high-fat feed group and significantly decreased in the low-dose radiation group compared with the control group.

CONCLUSIONS

Long-term low-dose ionizing radiation exposure stimulates neutrophils and inhibits their production of NETs, resulting in inhibition of atherosclerosis.

Doses to the right coronary artery and the left anterior descending coronary artery and death from ischemic heart disease after breast cancer radiotherapy: a case-control study in a population-based cohort

BACKGROUND AND PURPOSE

Doses to the coronary arteries in breast cancer (BC) radiotherapy (RT) have been suggested to be a risk predictor of long-term cardiac toxicity after BC treatment. We investigated the dose-risk relationships between near maximum doses (Dmax) to the right coronary artery (RCA) and left anterior descending coronary artery (LAD) and ischemic heart disease (IHD) mortality after BC RT.

PATIENTS AND METHODS

In a cohort of 2,813 women diagnosed with BC between 1958 and 1992 with a follow-up of at least 10 years, we identified 134 cases of death due to IHD 10-19 years after BC diagnosis. For each case, one control was selected within the cohort matched for age at diagnosis. 3D-volume and 3D-dose reconstructions were obtained from individual RT charts. We estimated the Dmax to the RCA and the LAD and the mean heart dose (MHD). We performed conditional logistic regression analysis comparing piecewise spline transformation and simple linear modeling for best fit.

RESULTS

There was a linear dose-risk relationship for both the Dmax to the RCA (odds ratio [OR]/Gray [Gy] 1.03 [1.01-1.05]) and the LAD (OR/Gy 1.04 [1.02-1.06]) in a multivariable model. For MHD there was a linear dose-risk relationship (1,14 OR/Gy [1.08-1.19]. For all relationships, simple linear modelling was superior to spline transformations.

INTERPRETATION

Doses to both the RCA and LAD are independent risk predictors of long-term cardiotoxicity after RT for BC In addition to the LAD, the RCA should be regarded as an organ at risk in RT planning.

Mortality After Major Cardiovascular Events in Survivors of Childhood Cancer

BACKGROUND

Adult survivors of childhood cancer are at risk for cardiovascular events.

OBJECTIVES

In this study, we sought to determine the risk for mortality after a major cardiovascular event among childhood cancer survivors compared with noncancer populations.

METHODS

All-cause and cardiovascular cause-specific mortality risks after heart failure (HF), coronary artery disease (CAD), or stroke were compared among survivors and siblings in the Childhood Cancer Survivor Study (CCSS) and participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Cox proportional hazard regression models were used to estimate HRs and 95% CIs between groups, adjusted for demographic and clinical factors.

RESULTS

Among 25,658 childhood cancer survivors (median age at diagnosis 7 years, median age at follow-up or death 38 years) and 5,051 siblings, 1,780 survivors and 91 siblings had a cardiovascular event. After HF, CAD, and stroke, 10-year all-cause mortalities were 30% (95% CI: 26%-33%), 36% (95% CI: 31%-40%), and 29% (95% CI: 24%-33%), respectively, among survivors vs 14% (95% CI: 0%-25%), 14% (95% CI: 2%-25%), and 4% (95% CI: 0%-11%) among siblings. All-cause mortality risks among childhood cancer survivors were increased after HF (HR: 7.32; 95% CI: 2.56-20.89), CAD (HR: 5.54; 95% CI: 2.37-12.93), and stroke (HR: 3.57; 95% CI: 1.12-11.37). CAD-specific mortality risk was increased (HR: 3.70; 95% CI: 1.05-13.02). Among 5,114 CARDIA participants, 345 had a major event. Although CARDIA participants were on average decades older at events (median age 57 years vs 31 years), mortality risks were similar, except that all-cause mortality after CAD was significantly increased among childhood cancer survivors (HR: 1.85; 95% CI: 1.16-2.95).

CONCLUSIONS

Survivors of childhood cancer represent a population at high risk for mortality after major cardiovascular events.

Therapeutic strategies based on non-ionizing radiation to prevent venous neointimal hyperplasia: the relevance for stenosed arteriovenous fistula, and the role of vascular compliance

We have reviewed the development and current status of therapies based on exposure to non-ionizing radiation (with a photon energy less than 10 eV) aimed at suppressing the venous neointimal hyperplasia, and consequentially at avoiding stenosis in arteriovenous grafts. Due to the drawbacks associated with the medical use of ionizing radiation, prominently the radiation-induced cardiovascular disease, the availability of procedures using non-ionizing radiation is becoming a noteworthy objective for the current research. Further, the focus of the review was the use of such procedures for improving the vascular access function and assuring the clinical success of arteriovenous fistulae in hemodialysis patients. Following a brief discussion of the physical principles underlying radiotherapy, the current methods based on non-ionizing radiation, either in use or under development, were described in detail. There are currently five such techniques, including photodynamic therapy (PDT), far-infrared therapy, photochemical tissue passivation (PTP), Alucent vascular scaffolding, and adventitial photocrosslinking. The last three are contingent on the mechanical stiffening achievable by the exogenous photochemical crosslinking of tissular collagen, a process that leads to the decrease of venous compliance. As there are conflicting opinions on the role of compliance mismatch between arterial and venous conduits in a graft, this aspect was also considered in our review.

A Review: Multi-Omics Approach to Studying the Association between Ionizing Radiation Effects on Biological Aging

Multi-omics studies have emerged as powerful tools for tailoring individualized responses to various conditions, capitalizing on genome sequencing technologies' increasing affordability and efficiency. This paper delves into the potential of multi-omics in deepening our understanding of biological age, examining the techniques available in light of evolving technology and computational models. The primary objective is to review the relationship between ionizing radiation and biological age, exploring a wide array of functional, physiological, and psychological parameters. This comprehensive review draws upon an extensive range of sources, including peer-reviewed journal articles, government documents, and reputable websites. The literature review spans from fundamental insights into radiation effects to the latest developments in aging research. Ionizing radiation exerts its influence through direct mechanisms, notably single- and double-strand DNA breaks and cross links, along with other critical cellular events. The cumulative impact of DNA damage forms the foundation for the intricate process of natural aging, intersecting with numerous diseases and pivotal biomarkers. Furthermore, there is a resurgence of interest in ionizing radiation research from various organizations and countries, reinvigorating its importance as a key contributor to the study of biological age. Biological age serves as a vital reference point for the monitoring and mitigation of the effects of various stressors, including ionizing radiation. Ionizing radiation emerges as a potent candidate for modeling the separation of biological age from chronological age, offering a promising avenue for tailoring protocols across diverse fields, including the rigorous demands of space exploration.

Cardiac substructures dosimetric predicts cardiac toxicity and prognosis in esophageal squamous cell cancer treated by radiotherapy

PURPOSE

To look into the relationship between cardiac substructures (CS) dosimetric parameters and cardiac events (CE) or overall survival (OS) in patients undergoing radiation therapy (RT) for esophageal squamous cell carcinoma (ESCC).

METHODS AND MATERIALS

A retrospective study included 350 patients with ESCC receiving definitive chemoradiotherapy or radiotherapy (d-CRT/d-RT) or neoadjuvant chemoradiotherapy (NCRT) from March 2013 to May 2022. Our study examined the adverse cardiac events of any grade or G3+, as defined by the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Competing risk analysis and Cox regression analysis were used to assess the relationship between CS doses and CEs or OS.

RESULTS

201 (57.4 %) patients received any grade CEs over a median follow-up time of 22.50 months (IQR, 12.40-45.60), and 24 (6.86 %) patients suffered G3+ CEs. On landmark analysis, patients with any grade CEs had significantly lower OS (P = 0.003). Multivariable analysis revealed that any grade CEs were predicted by the dose of CSs in all populations. In addition, for G3+ cardiac events, arrhythmic and small probability of cardiac events, LAD V20 ((HR: 1.02, 95 % CI: 1.00-1.03, P = 0.012; HR: 1.01, 95 % CI: 1.00-1.02, P = 0.005; HR; 1.01, 95 % CI: 1.00-1.02, P = 0.012) was also an independent predictive factor. LAD V50 (HR: 1.07, 95 % CI: 1.03-1.10, P <0.001) predicted pericardium effusion events. Moreover, the multivariable analysis revealed that OS was predicted by LAD V30 (HR: 1.03; 95 % CI, 1.01-1.05, P = 0.015).

CONCLUSIONS

In the population of ESCC patients receiving RT, we showed that the CS factors had a substantial predictive value for the various types and grades of CEs. The elevated radiation dose of LAD was a significant contributor to a higher rate of cardiac events and a worse prognosis.

Low-Dose Occupational Exposure to Ionizing Radiation and Cardiovascular Effects: A Narrative Review

Historically, non-cancer diseases have not been considered a health risk following low-dose exposure to ionizing radiation. However, it is now well known that high-dose ionizing radiation causes cardiovascular disease, and emerging epidemiological evidence suggests an excess risk of non-cancer diseases even following exposure to lower doses of ionizing radiation than previously thought. In fact, the evidence is strongest for cardiovascular disease (CVD). The aim of this review was to report the most representative studies and data on the risk of CVD from low-dose radiation in people with occupational exposure. We reported the results of 27 articles selected from a database search of 1151 studies. The results show a complex evidence landscape on the relationship between radiation exposure and cardiovascular disease. In general, published papers show a positive association between ionizing radiation exposure and dermal microcirculation damage, ischemic heart disease, and cerebrovascular disease. Overall, they highlight the need for comprehensive and detailed research to clarify this relationship. Due to limited statistical power, the dose-risk relationship below 0.5 Gy is inconclusive, but if this relationship is found to have no threshold, it could have a significant impact on current estimates of health risks at low doses.

Tissue Reactions and Mechanism in Cardiovascular Diseases Induced by Radiation

The long-term survival rate of cancer patients has been increasing as a result of advances in treatments and precise medical management. The evidence has accumulated that the incidence and mortality of non-cancer diseases have increased along with the increase in survival time and long-term survival rate of cancer patients after radiotherapy. The risk of cardiovascular disease as a radiation late effect of tissue damage reactions is becoming a critical challenge and attracts great concern. Epidemiological research and clinical trials have clearly shown the close association between the development of cardiovascular disease in long-term cancer survivors and radiation exposure. Experimental biological data also strongly supports the above statement. Cardiovascular diseases can occur decades post-irradiation, and from initiation and development to illness, there is a complicated process, including direct and indirect damage of endothelial cells by radiation, acute vasculitis with neutrophil invasion, endothelial dysfunction, altered permeability, tissue reactions, capillary-like network loss, and activation of coagulator mechanisms, fibrosis, and atherosclerosis. We summarize the most recent literature on the tissue reactions and mechanisms that contribute to the development of radiation-induced cardiovascular diseases (RICVD) and provide biological knowledge for building preventative strategies.

Effect of low-dose radiation on thyroid function and the gut microbiota

BACKGROUND

The thyroid-gut axis has a great influence on the maintenance of human health; however, we know very little about the effects of low-dose ionizing radiation (LDR) on thyroid hormone levels and gut microbiota composition.

AIM

To investigate the potential effects of low-dose X-ray radiation to male C57BL/6J mice.

METHODS

Peripheral blood was collected for enzyme-linked immunosorbent assay (ELISA), and stool samples were taken for 16S ribosomal RNA (rRNA) gene sequencing after irradiation.

RESULTS

We found that LDR caused changes in thyroid stimulating hormone (TSH) levels in the irradiated mice, suggesting a dose-dependent response in thyroid function to ionizing radiation. No changes in the diversity and richness of the gut microbiota were observed in the LDR-exposed group in comparison to the controls. The abundance of Moraxellaceae and Enterobacteriaceae decreased in the LDR-exposed groups compared with the controls, and the Lachnospiraceae abundance increased in a dose-dependent manner in the radiated groups. And the abundances of uncultured_bacterium_g_Acinetobacter, uncultured_bacterium_ o_Mollicutes_RF39, uncultured_bacterium_g_Citrobacter, and uncultured_ bacterium_g_Lactococcus decreased in the radiated groups at the genus level, which showed a correlation with radiation exposure and diagnostic efficacy. Analysis of functional metabolic pathways revealed that biological metabolism was predicted to have an effect on functional activities, such as nucleotide metabolism, carbohydrate metabolism, and glycan biosynthesis and metabolism. Furthermore, Kyoto Encyclopedia of Genes and Genomes pathway annotation also suggested that changes in the gut microbiota were related to processing functions, including translation, replication and repair.

CONCLUSION

LDR can change thyroid function and the gut microbiota, and changes in the abundances of bacteria are correlated with the radiation dose.

Preclinical models of radiation-induced cardiac toxicity: Potential mechanisms and biomarkers

Radiation therapy (RT) is an important modality in cancer treatment with >50% of cancer patients undergoing RT for curative or palliative intent. In patients with breast, lung, and esophageal cancer, as well as mediastinal malignancies, incidental RT dose to heart or vascular structures has been linked to the development of Radiation-Induced Heart Disease (RIHD) which manifests as ischemic heart disease, cardiomyopathy, cardiac dysfunction, and heart failure. Despite the remarkable progress in the delivery of radiotherapy treatment, off-target cardiac toxicities are unavoidable. One of the best-studied pathological consequences of incidental exposure of the heart to RT is collagen deposition and fibrosis, leading to the development of radiation-induced myocardial fibrosis (RIMF). However, the pathogenesis of RIMF is still largely unknown. Moreover, there are no available clinical approaches to reverse RIMF once it occurs and it continues to impair the quality of life of long-term cancer survivors. Hence, there is an increasing need for more clinically relevant preclinical models to elucidate the molecular and cellular mechanisms involved in the development of RIMF. This review offers an insight into the existing preclinical models to study RIHD and the suggested mechanisms of RIMF, as well as available multi-modality treatments and outcomes. Moreover, we summarize the valuable detection methods of RIHD/RIMF, and the clinical use of sensitive radiographic and circulating biomarkers.

Puerarin Reduces Radiation-Induced Vascular Endothelial Cell Damage Via miR-34a/Placental Growth Factor

The aim is to explore the protective effects of Puerarin on radiation-induced vascular endothelial cell damage and its underlying mechanism. The apoptosis and DNA damage of Human umbilical vascular endothelial cells (HUVECs) exposed to radiation alone or in combination with glucose in the exposed group were significantly elevated (P < .05) compared with those in the control group. The Puerarin-treated HUVECs showed significant reduction in the radiation-induced apoptosis and DNA damage (P < .05). Furthermore, X-ray irradiation significantly increased the expression of miR-34a, which was reversed by pre-treatment with Puerarin. Placental Growth Factor (PLGF) was a target gene of miR-34a. The expression of PLGF in the peripheral blood of patients receiving radiotherapy significantly increased with an increase in the cumulative dose of radiation (P < .05), after which it began to decrease at the fourth week (P < .05) and then remained at a low level until the end of radiotherapy. Puerarin exerts a radioprotective effect by decreasing DNA damage and apoptosis through miR-34a-targeted PLGF.

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.

Exercise Enhanced Cardiac Function in Mice With Radiation-Induced Heart Disease via the FNDC5/Irisin-Dependent Mitochondrial Turnover Pathway

Background: Despite the development of radiation therapy (RT) techniques, concern regarding the serious and irreversible heart injury induced by RT has grown due to the lack of early intervention measures. Although exercise can act as an effective and economic nonpharmacologic strategy to combat fatigue and improve quality of life for cancer survivors, limited data on its application in radiation-induced heart disease (RIHD) and the underlying molecular mechanism are available.

Methods: Fifteen young adult male mice were enrolled in this study and divided into 3 groups (including exercised RIHD group, sedentary RIHD group, and controls; n =5 samples/group). While the mice in the control group were kept in cages without irradiation, those in the exercised RIHD group underwent 3weeks of aerobic exercise on the treadmill after radiotherapy. At the end of the 3rd week following RT, FNDC5/irisin expression, cardiac function, aerobic fitness, cardiomyocyte apoptosis, mitochondrial function, and mitochondrial turnover in the myocardium were assessed to identify the protective role of exercise in RIHD and investigate the potential mechanism.

Results: While sedentary RIHD group had impaired cardiac function and aerobic fitness than controls, the exercised RIHD mice had improved cardiac function and aerobic fitness, elevated ATP production and the mitochondrial protein content, decreased mitochondrial length, and increased formation of mitophagosomes compared with sedentary RIHD mice. These changes were accompanied by the elevated expression of FNDC5/irisin, a fission marker (DRP1) and mitophagy markers (PINK1 and LC3B) in exercised RIHD group than that of sedentary RIHD group, but the expression of biogenesis (TFAM) and fusion (MFN2) markers was not significantly changed.

Conclusion: Exercise could enhance cardiac function and aerobic fitness in RIHD mice partly through an autocrine mechanism via FNDC5/irisin, in which autophagy was selectively activated, suggesting that FNDC5/irisin may act as an intervening target to prevent the development of RIHD.

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.

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.

Myocardial Disease and Long-Distance Space Travel: Solving the Radiation Problem

Radiation-induced cardiovascular disease is a well-known complication of radiation exposure. Over the last few years, planning for deep space missions has increased interest in the effects of space radiation on the cardiovascular system, as an increasing number of astronauts will be exposed to space radiation for longer periods of time. Research has shown that exposure to different types of particles found in space radiation can lead to the development of diverse cardiovascular disease via fibrotic myocardial remodeling, accelerated atherosclerosis and microvascular damage. Several underlying mechanisms for radiation-induced cardiovascular disease have been identified, but many aspects of the pathophysiology remain unclear. Existing pharmacological compounds have been evaluated to protect the cardiovascular system from space radiation-induced damage, but currently no radioprotective compounds have been approved. This review critically analyzes the effects of space radiation on the cardiovascular system, the underlying mechanisms and potential countermeasures to space radiation-induced cardiovascular disease.

Radon Gas in the City of Alicante. High Risk of Low Indoor Air Quality in Poorly Ventilated Buildings

In December 2019, Spain considered for the first time the presence of radon to the Technical Building Code (Basic Document HS 6: Radon Exposure Protection), although it only mentions minimum presences and the need for ventilation. This research shows that in buried structures or in places with little ventilation, even in soils with a low probability of granite, a high content of radon gas can be found. The city of Alicante has been used as a measurement location for different architectural sites; here, the level of 100 Bq/m³ is the first threshold where the gas must be monitored, and the level of 300 Bq/m³ is the maximum threshold above which corrective ventilation measures must be taken. The research conducted during the years 2015 and 2016 shows that it is necessary to account for also the areas considered to be “low presence of radon gas” to achieve healthy constructions. The renewal of air in the different places will be tested for the presence of radon, i.e., the greater the accumulation is, the less ventilation and the greater the risk of accumulation of radon gas. This study is located in the city of Alicante, where the seven civil constructions are located: two Civil War shelters, the Santa Barbara Castle, the Ereta Powder Keg, the Luceros-Marq and Serra Grossa railway tunnels and the Británica underground deposits. Radon gas is currently a concern for major health and medical agencies because it is considered to be a chemical element that is very harmful to people. The World Health Organization is one of the organisations that has the objective of studying and researching this element, to develop solutions. Radon gas is normally found in a gaseous state and is highly radioactive. It is present in many terrains and it is mostly found in those with granite; although the presence of this element is very low, there is always a minimum presence. In the past, in nongranite soils, the dose of radon was considered to be so low that it was insignificant. Therefore, in this research, the aim is to consider the high presence of radon gas in nongranite soils as long as the conditions for its accumulation are present.

Effect of radiation on endothelial functions in workers exposed to radiation

OBJECTIVE Our aim is to determine whether radiation affects the endothelial function of hospital staff working in the radiation unit for diagnostic and therapeutic purposes. We have evaluated endothelial function with vascular imaging parameters such as flow-mediated dilatation (FMD) and aortic stiffness index (ASI). METHODS A total of 75 employees, 35 of whom are exposed to radiation due to their profession and 40 as the control group, were included in our single-centered study. Demographic data, FMD, aortic stiffness, and echocardiographic findings of the two groups were compared. RESULTS There were no significant differences in demographic data. Median FMD values tended to be lower in the radiation exposure group [7.89 (2.17-21.88) vs. 11.69 (5.13-27.27) p=0.09]. The FMD value was significantly lower in the catheter laboratory group than in the radiation-exposed (p=0.034) and control (p=0.012) groups. However, there was no statistically significant difference between the non-catheter lab radiation exposed group and the control group (p=0.804). In addition, there was no statistically significant difference in the ASI value between the groups (p=0.201). CONCLUSION We have found that FMD is decreased among hospital staff working in radiation-associated areas. This may be an early marker for radiation-induced endothelial dysfunction.

Childhood cancer survivors: The integral role of the cardiologist and cardiovascular imaging

IMPORTANCE

With 80% of childhood cancer survivors (CCS) alive 30 years after diagnosis, preventable causes of death, such as cardiovascular disease resulting from initial cancer therapy, becomes an important metric. This leads to a more pronounced role for cardiologists in the care of CCS.

OBSERVATIONS

While routine cardiovascular screening has been traditionally performed by the hematologist/oncologist or primary care provider, our understanding of cardiovascular disease in CCS has advanced. The measurement of left ventricular ejection fraction (LVEF) can now be complemented with additional assessments of strain, LV mass, right ventricular function, diastolic function, valve function, the pericardium, coronary perfusion, and biomarkers. Risk factor modification, prophylaxis, and timing of treatment are also critical.

CONCLUSIONS AND RELEVANCE

Early cardiovascular screening and treatment in asymptomatic CCS can be nuanced and complex. As a result, there is a renewed opportunity for the cardiologist to play an integral role in the care of CCS.

KEY POINTS

Question/Purpose: Review cardiovascular disease and the role of the cardiologist in the care of asymptomatic childhood cancer survivors (CCS).

FINDINGS

Cardiovascular care in CCS benefits from a multi-faceted approach that does not overly rely on LVEF. Meaning: Adequate screening and treatment of cardiovascular disease in asymptomatic CCS may often be optimized by the involvement of a cardiologist.

The effect of chronic low-dose environmental radiation on organ mass of bank voles in the Chernobyl exclusion zone

PURPOSE

Animals are exposed to environmental ionizing radiation (IR) externally through proximity to contaminated soil and internally through ingestion and inhalation of radionuclides. Internal organs can respond to radioactive contamination through physiological stress. Chronic stress can compromise the size of physiologically active organs, but studies on wild mammal populations are scarce. The effects of environmental IR contamination on organ masses were studied by using a wild rodent inhabiting the Chernobyl exclusion zone (CEZ).

MATERIAL AND METHODS

The masses of brain, heart, kidney, spleen, liver and lung were assessed from bank voles (Myodes glareolus) captured from areas across radioactive contamination gradient within the CEZ. Relative organ masses were used to correct for the body mass of an individual.

RESULTS

Results showed a significant negative correlation between IR level in the environment and relative brain and kidney mass. A significant positive correlation between IR and relative heart mass was also found. Principal component analysis (PCA) also suggested positive relationship between IR and relative spleen mass; however, this relationship was not significant when spleen was analyzed separately. There was no apparent relationship between IR and relative liver or lung mass.

CONCLUSIONS

Results suggest that in the wild populations even low but chronic doses of IR can lead to changes in relative organ mass. The novelty of these result is showing that exposure to low doses can affect the organ masses in similar fashion as previously shown on high, acute, radiation doses. These data support the hypothesis that wildlife might be more sensitive to IR than animals used in laboratory studies. However, more research is needed to rule out the other indirect effects such as radiosensitivity of the food sources or possible combined stress effects from e.g. infections.

Sodium tanshinone IIA sulfonate prevents radiation-induced damage in primary rat cardiac fibroblasts

This study investigated the effects of X-ray irradiation on primary rat cardiac fibroblasts (CFs) and its potential mechanism, as well as whether sodium tanshinone IIA sulfonate (STS) has protective effect on CFs and its possible mechanism. Our data demonstrated that X-rays inhibited cell growth and increased oxidative stress in CFs, and STS mitigated X-ray-induced injury. Enzyme-linked immuno-sorbent assay showed that X-rays increased the levels of secreted angiotensin II (Ang II) and brain natriuretic peptide (BNP). STS inhibited the X-ray-induced increases in Ang II and BNP release. Apoptosis and cell cycle of CFs were analyzed using flow cytometry. X-rays induced apoptosis in CFs, whereas STS inhibited apoptosis in CFs after X-ray irradiation. X-rays induced S-phase cell cycle arrest in CFs, which could be reversed by STS. X-rays increased the expression of phosphorylated-P38/P38, cleaved caspase-3 and caspase-3 as well as decreased the expression of phosphorylated extracellular signal-regulated kinase 1/2 (ERK 1/2)/ERK 1/2 and B cell lymphoma 2 (Bcl-2)/Bcl-2 associated X protein (BAX) in CFs, as shown by Western blotting. STS mitigated the X-ray radiation-induced expression changes of these proteins. In conclusion, our results demonstrated that STS may potentially be developed as a medical countermeasure to mitigate radiation-induced cardiac damage.

Rosiglitazone Protects Endothelial Cells From Irradiation-Induced Mitochondrial Dysfunction

Background and Purpose

Up to 50–60% of all cancer patients receive radiotherapy as part of their treatment strategy. However, the mechanisms accounting for increased vascular risks after irradiation are not completely understood. Mitochondrial dysfunction has been identified as a potential cause of radiation-induced atherosclerosis.

Materials and Methods

Assays for apoptosis, cellular metabolism, mitochondrial DNA content, functionality and morphology were used to compare the response of endothelial cells to a single 2 Gy dose of X-rays under basal conditions or after pharmacological treatments that either reduced (EtBr) or increased (rosiglitazone) mitochondrial content.

Results

Exposure to ionizing radiation caused a persistent reduction in mitochondrial content of endothelial cells. Pharmacological reduction of mitochondrial DNA content rendered endothelial cells more vulnerable to radiation-induced apoptosis, whereas rosiglitazone treatment increased oxidative metabolism and redox state and decreased the levels of apoptosis after irradiation.

Conclusion

Pre-existing mitochondrial damage sensitizes endothelial cells to ionizing radiation-induced mitochondrial dysfunction. Rosiglitazone protects endothelial cells from the detrimental effects of radiation exposure on mitochondrial metabolism and oxidative stress. Thus, our findings indicate that rosiglitazone may have potential value as prophylactic for radiation-induced atherosclerosis.

Oxidative Stress in Radiation-Induced Cardiotoxicity

There is a distinct increase in the risk of heart disease in people exposed to ionizing radiation (IR). Radiation-induced heart disease (RIHD) is one of the adverse side effects when people are exposed to ionizing radiation. IR may come from various forms, such as diagnostic imaging, radiotherapy for cancer treatment, nuclear disasters, and accidents. However, RIHD was mainly observed after radiotherapy for chest malignant tumors, especially left breast cancer. Radiation therapy (RT) has become one of the main ways to treat all kinds of cancer, which is used to reduce the recurrence of cancer and improve the survival rate of patients. The potential cause of radiation-induced cardiotoxicity is unclear, but it may be relevant to oxidative stress. Oxidative stress, an accumulation of reactive oxygen species (ROS), disrupts intracellular homeostasis through chemical modification and damages proteins, lipids, and DNA; therefore, it results in a series of related pathophysiological changes. The purpose of this review was to summarise the studies of oxidative stress in radiotherapy-induced cardiotoxicity and provide prevention and treatment methods to reduce cardiac damage.

Radiation metabolomics in the quest of cardiotoxicity biomarkers: the review

Purpose: Ionizing radiation is a risk factor to the whole organism, including the heart. Cardiac damage is considered to be a late effect of radiation exposure. While the acute cardiotoxicity of high doses is well characterized, the knowledge about nature and magnitude of the cardiac risk following lower doses exposure is incomplete. It has been shown that the cardiotoxic effects of radiation are source-, dose- and time-dependent. This paper provides an overview on these dependencies with regard to the molecular responses at the cellular and tissue levels. Main focus is put on the Nuclear Magnetic Resonance (NMR)-based and Mass Spectrometry (MS)-based metabolomic approaches in search of toxicity markers of relatively small doses of radiation.Conclusions: Available literature indicates that radiation exposure affects metabolites associated with: energy production, degradation of proteins and cell membranes, expression of proteins and stress response. Such effects are common for both animal and human studies. However, the specific metabolic response depends on several factors, including the examined organ. Radiation metabolomics can be used to explain the mechanisms of development of radiation-induced heart disease and to find an organ-specific biomarker of radiation exposure. The main aim of this review was to collect the information on the human cardiotoxicity biomarkers. In addition it also summarizes results of the studies on the metabolic responses to ionizing radiation for other organs, as well as the comparative data concerning animal studies.

Ventilation as an Indispensable Tool for Healthy Constructions: Comparison of Alicante’s Urban Railway Tunnels

The majority of scientific agencies in the field of medicine and health, including the World Health Organization, consider radon gas a very harmful element for humans. This element, in its gaseous state, is radioactive and is present in almost all land in which buildings are implanted, especially in granitic soils, which present higher levels of radon gas. Nongranitic soils have traditionally been considered to have low radon levels. In addition to the contributions made by this article, it is very relevant that there are many countries, including Spain, in which the technical codes for their construction regulations do not include the maximum radon dose that a building can hold so that it is not harmful to humans nor do they hold the measures necessary to remedy excessive accumulation. The main objective of this research is to demonstrate the need for ventilation in buried works. To do this, a comparison is made between two railway tunnels in the urban fabric of the city of Alicante: one of them is in operation (Benacantil Mount) and the other is in the excavation phase (Serra Grossa). When underground railway installations are planned, they are equipped with large air ventilation systems due to the pollutants generated by ground exposure. These mechanical systems consist of suction turbines that expel the air to the outside. Research shows that radon gas is an indicator of an area’s air quality. In addition, ventilation in railway tunnels (mechanical and natural) allows for air renewal and improves the air quality.

Radon Gas as an Indicator for Air Quality Control in Buried Industrial Architecture: Rehabilitation of the Old Británica Warehouses in Alicante for a Tourist Site

The infrastructure of the Británica warehouses in Alicante is a very important industrial architectural element in the history of Spain, although it is unknown to almost all of the inhabitants of the city. The former fuel refinery is located in the Serra Grossa Mountains and served much of the country until 1966. This research is based on the plans of the city of Alicante to convert a historical element, the Británica warehouses, into a unique tourist site. Currently, the network of storage domes in this facility, which has an approximate footprint of 20,000 m 2 and domes approximately 20 m high, is in a state of neglect, and there are neighborhood initiatives for its rehabilitation to become a cultural or tourist site. Therefore, it is necessary to take into account the quality of the indoor air. Radon gas is analyzed as a control element for future refurbishment of the facility. Alicante is a nongranite area and therefore is not very susceptible to generation of radon gas indoors, but the conditions of a buried and poorly ventilated space make the site appropriate for analysis. Most scientific agencies in the field of medicine and health, including the World Health Organization, consider radon gas to be very harmful to humans. This element in its gaseous state is radioactive and is present in almost all the land in which the buildings are implanted, with granitic type soils presenting higher levels of radon gas. Nongranitic soils have traditionally been considered to have low radon levels. The city of Alicante, where the installation is located, is a nongranitic area and therefore is not very susceptible to generating radon gas in buildings, but the conditions of buried and poorly ventilated places make the site appropriate for analysis to support air quality control and decision-making.

Radiation-induced heart disease: a review of classification, mechanism and prevention

With the increasing incidence of thoracic tumors, radiation therapy (RT) has become an important component of comprehensive treatment. RT improves survival in many cancers, but it involves some inevitable complications. Radiation-induced heart disease (RIHD) is one of the most serious complications. RIHD comprises a spectrum of heart disease including cardiomyopathy, pericarditis, coronary artery disease, valvular heart disease and conduction system abnormalities. There are numerous clinical manifestations of RIHD, such as chest pain, palpitation, and dyspnea, even without obvious symptoms. Based on previous studies, the pathogenesis of RIHD is related to the production and effects of various cytokines caused by endothelial injury, inflammatory response, and oxidative stress (OS). Therefore, it is of great importance for clinicians to identify the mechanism and propose interventions for the prevention of RIHD.

Cardiovascular complications after radiotherapy

Over the past decades, effective cancer therapies have resulted in a significant improvement in the survival rates for a number of cancers and an increase in the number of cancer survivors. Radiation therapy is widely used in the treatment of cancer, and it can induce various cardiotoxicities that differ considerably from chemotherapy-induced cardiotoxicity. They occur primarily as late radiation-induced complications, several years from the end of anticancer treatment and present as coronary artery disease, heart failure, pericardial disease, valvular heart disease and arrhythmias. Patients who recovered from cancer disease suffer from cardiac complications of anticancer treatment, it affects the quality of their lives and life expectancy, especially if the diagnosis is delayed. These patients may present distinct symptoms of cardiac injury, resulting from radiation-induced neurotoxicity and altered pain perception, which makes diagnosis difficult. This review highlights the need for a screening programme for patients who have undergone radiation therapy and which will subsequently have a potentially profound impact on morbidity and mortality.

Acute Coronary Syndrome in Cancer Patients

Cardiologists are seeing an increasing number of oncology patients every day, and acute coronary syndrome (ACS) is one of the problems patients encounter during follow-up. Cardio-oncology is the care of patients with cancer and cardiovascular disease, whether overt or occult, already established or acquired during treatment. Cardiovascular complications can occur acutely during or shortly after treatment and persist as long-term effects for months to years after treatment. As a delayed effect of cancer treatment, cardiovascular damage can occur months to years after the initial treatment. Vasospasm, thrombosis, and radiation-induced cardiovascular diseases can all cause ACS. Careful surveillance of ACS symptoms and regular screening during follow-up of patients with malignancy are suggested. In this review, we summarize the ACS we usually encounter during a range of cancer treatments or post cancer survival by providing illustrative case examples.

Radiation Matters of the Heart: A Mini Review

Radiation Therapy (RT) has been critical in cancer treatment regimens to date. However, it has been shown that ionizing radiation is also associated with increased risk of damage to healthy tissues. At high radiation doses, varied effects including inactivation of cells in treated tissue and associated functional impairment are seen. These range from direct damage to the heart; particularly, diffuse fibrosis of the pericardium and myocardium, adhesion of the pericardium, injury to the blood vessels and stenosis. Cardiac damage is mostly a late responding end-point, occurring anywhere between 1 and 10 years after radiation procedures. Cardiovascular disease following radiotherapy was more common with radiation treatments used before the late 1980s. Modern RT regimens with more focused radiation beams, allow tumors to be targeted more precisely and shield the heart and other healthy tissues for minimizing the radiation damage to normal cells. In this review, we discuss radiation therapeutic doses used and post-radiation damage to the heart muscle from published studies. We also emphasize the need for early detection of cardiotoxicity and the need for more cardio-protection approaches where feasible.

Cardiac radiation dose distribution, cardiac events and mortality in early-stage lung cancer treated with stereotactic body radiation therapy (SBRT)

Background

The impact of radiation dose to the heart in early-stage lung cancer patients treated with definitive stereotactic body radiation therapy (SBRT) is not well known. We, therefore, analyzed whether higher radiation dose to the heart would lead to an increase in cardiac toxicity and overall mortality.

Methods

Seventy-four patients with 75 tumors treated definitively with SBRT for early-stage non-small cell lung cancer (NSCLC) and two cases of limited-stage small cell lung cancer (SCLC) with an average follow-up of 35 months (range, 1-130 months) were retrospectively analyzed. The whole heart and cardiac substructures including atria, ventricles, heart valves, atrioventricular (AV) node and four major coronary artery branches were contoured using commercial treatment planning software. For each structure, multiple dose-volume parameters were recorded. The relation between radiation doses to the heart, tumor location, and preexisting medical conditions with the development of cardiac events and mortality was assessed.

Results

Overall, there was large variability in dose to cardiac substructures: mean heart dose (MHD) averaged 1.90 Gy (range, 0.04-11.00 Gy) equivalent 2 Gy dose (EQD2) and average max dose to the left anterior descending artery (LAD) was 5.67 Gy (range, 0.04-48.60 Gy) EQD2. Patients with tumor location in the upper lobes received higher cardiac radiation dose compared to other lobes (P<0.0001). There was no difference in MHD between central and peripheral tumor locations. The distance between heart and tumor was negatively associated with MHD (r=-0.61, P<0.0001). Eighteen patients developed cardiac complications including the need for defibrillator placement, arrhythmia development and worsening heart failure. Preexisting cardiac disease was associated with an increased number of cardiac events after radiotherapy (P=0.039). However, neither radiation dose to the whole heart or the cardiac substructures, nor comorbidities such as diabetes, hypercholesterolemia, hypertension or COPD were associated with the number of cardiac events or overall mortality.

Conclusions

Radiation doses to the heart and its substructures show large variability. Cardiac events occurred more frequently in patients with a history of heart problems. At present, the effect of radiation dose on cardiac toxicity is unclear in patients undergoing SBRT for early-stage lung cancer. Longer follow-up and a larger cohort are needed to assess for late cardiac sequelae.

Radiation-Induced Cardiovascular Toxicity: Mechanisms, Prevention, and Treatment

PURPOSE OF REVIEW

Ionizing radiation is a highly effective treatment for a wide range of malignancies, yet the cardiovascular (CV) toxicity that can result from chest radiotherapy impairs the long-term health of cancer survivors and can be a limiting factor for its use. Despite over 100 years of successful clinical use, the mechanisms by which high-energy photons damage critical components within cells of the heart's myocardium, pericardium, vasculature, and valves remain unclear.

RECENT FINDINGS

Recent studies exploring the acute and chronic effects of radiation therapy on cardiac and vascular tissue have provided new insights into the development and progression of heart disease, including the identification and understanding of age- and complication-associated risk factors. However, key questions relating to the connection from upstream signaling to fibrotic changes remain. In addition, advances in the delivery of chest radiotherapy have helped to limit heart exposure and damage, but additional refinements to delivery techniques and cardioprotective therapeutics are absolutely necessary to reduce patient mortality and morbidity. Radiation therapy (RT)-driven CV toxicity remains a major issue for cancer survivors and more research is needed to define the precise mechanisms of toxicity. However, recent findings provide meaningful insights that may help improve patient outcomes.

Standing up to the cardiometabolic consequences of hematological cancers

Hematological cancer survivors are highly vulnerable to cardiometabolic complications impacting long-term health status, quality of life and survival. Elevated risk of diabetes and cardiovascular disease arises not only from the effects of the cancers themselves, but also from the toxic effects of cancer therapies, and deconditioning arising from reduced physical activity levels. Regular physical activity can circumvent or reverse adverse effects on the heart, skeletal muscle, vasculature and blood cells, through a combination of systemic and molecular mechanisms. We review the link between hematological cancers and cardiometabolic risk with a focus on adult survivors, including the contributing mechanisms and discuss the potential for physical activity interventions, which may act to oppose the negative effects of both physical deconditioning and therapies (conventional and targeted) on metabolic and growth signaling (kinase) pathways in the heart and beyond. In this context, we focus particularly on strategies targeting reducing and breaking up sedentary time and provide recommendations for future research.

Radiation-Induced Coronary Artery Disease in Young Patients

Exposure to radiotherapy has been shown to accelerate myocardial damage or injury to the cardiac vasculature. Accelerated coronary artery disease (CAD) is one of the main manifestations of cardiac disease in patients who undergo mediastinal radiation therapy. We present the cases of three young patients who developed severe CAD secondary to remote mediastinal radiotherapy.

Constrictive Pericarditis 5 Months after Radiation Therapy in a 62-Year-Old Woman with Esophageal Cancer

Most pericardial changes appear within a few weeks in patients who have undergone radiation therapy for thoracic neoplasms. Chronic pericardial constriction typically occurs decades later, consequent to fibrosis. Early constrictive pericarditis after chest irradiation is quite rare. We report the case of a 62-year-old woman who underwent radiation therapy for esophageal cancer and presented with constrictive pericarditis 5 months later. We searched the English-language medical literature from January 1986 through December 2015 for reports of early constrictive pericarditis after irradiation for thoracic malignancies. We defined "early" as a diagnosis within one year after radiation therapy. Five cases fit our criteria, and we summarize the findings here. To our knowledge, ours is the first definitive report of a patient with esophageal cancer to present with early radiation-induced constrictive pericarditis. We conclude that constrictive pericarditis can occur early after radiation for thoracic malignancies, albeit rarely. When planning care for cancer patients, awareness of this sequela is helpful.

Heart in space: effect of the extraterrestrial environment on the cardiovascular system

National space agencies and private corporations aim at an extended presence of humans in space in the medium to long term. Together with currently suboptimal technology, microgravity and cosmic rays raise health concerns about deep-space exploration missions. Both of these physical factors affect the cardiovascular system, whose gravity-dependence is pronounced. Heart and vascular function are, therefore, susceptible to substantial changes in weightlessness. The altered cardiovascular function in space causes physiological problems in the postflight period. A compromised cardiovascular system can be excessively vulnerable to space radiation, synergistically resulting in increased damage. The space radiation dose is significantly lower than in patients undergoing radiotherapy, in whom cardiac damage is well-documented following cancer therapy in the thoracic region. Nevertheless, epidemiological findings suggest an increased risk of late cardiovascular disease even with low doses of radiation. Moreover, the peculiar biological effectiveness of heavy ions in cosmic rays might increase this risk substantially. However, whether radiation-induced cardiovascular effects have a threshold at low doses is still unclear. The main countermeasures to mitigate the effect of the space environment on cardiac function are physical exercise, antioxidants, nutraceuticals, and radiation shielding.

Radiation-Induced Cardiovascular Disease

PURPOSE OF REVIEW

Thoracic radiation therapy is an effective treatment for several malignancies, such as Hodgkin's lymphoma and breast cancer. Over the years, however, the incidence of cardiovascular events has increased in these patients, notably in younger survivors who do not have traditional risk factors. This review summarizes the pathology, incidence, clinical presentation, and management of cardiac events after radiation therapy.

RECENT FINDINGS

Mediastinal radiation therapy accelerates the atherosclerosis process, resulting in early onset coronary artery disease. Valvular disease due to radiation therapy typically affects the left-sided valves, with aortic regurgitation being the most common. Rarely, it may lead to aortic stenosis requiring surgical interventions. Pericardial involvement includes acute and chronic pericardial disease and pericardial effusion. New studies are investigating the prevalence and pathogenesis of autonomic dysfunction in cancer survivors who have undergone mediastinal and neck radiation. Radiation therapy itself causes vascular endothelial dysfunction, resulting in clinical cardiovascular events, manifesting many years after completion of therapy. There remains little guidance regarding screening and therapies to prevent cardiovascular events in this population.

Repurposing DNA repair factors to eradicate tumor cells upon radiotherapy

Cancer is the leading cause of death worldwide. Almost 50% of all cancer patients undergo radiation therapy (RT) during treatment, with varying success. The main goal of RT is to kill tumor cells by damaging their DNA irreversibly while sparing the surrounding normal tissue. The outcome of RT is often determined by how tumors recognize and repair their damaged DNA. A growing body of evidence suggests that tumors often show abnormal expression of DNA double-strand break (DSB) repair genes that are absent from normal cells. Defects in a specific DNA repair pathway make tumor cells overly dependent on alternative or backup pathways to repair their damaged DNA. These tumor cell-specific abnormalities in the DNA damage response (DDR) machinery can potentially be used as biomarkers for treatment outcomes or as targets for sensitization to ionizing radiation (IR). An improved understanding of genetic or epigenetic alterations in the DNA repair pathways specific to cancer cells has paved the way for new treatments that combine pharmacological exploitation of tumor-specific molecular vulnerabilities with IR. Inhibiting DNA repair pathways has the potential to greatly enhance the therapeutic ratio of RT. In this review, we will discuss DNA repair pathways in active cells and how these pathways are deregulated in tumors. We will also describe the impact of targeting cancer-specific aberrations in the DDR as a treatment strategy to improve the efficacy of RT. Finally, we will address the current roadblocks and future prospects of these approaches.

Functional Gene Analysis Reveals Cell Cycle Changes and Inflammation in Endothelial Cells Irradiated with a Single X-ray Dose

Background and Purpose: Epidemiological data suggests an excess risk of cardiovascular disease (CVD) at low doses (0.05 and 0.1 Gy) of ionizing radiation (IR). Furthermore, the underlying biological and molecular mechanisms of radiation-induced CVD are still unclear. Because damage to the endothelium could be critical in IR-related CVD, this study aimed to identify the effects of radiation on immortalized endothelial cells in the context of atherosclerosis.

Material and Methods: Microarrays and RT-qPCR were used to compare the response of endothelial cells irradiated with a single X-ray dose (0.05, 0.1, 0.5, 2 Gy) measured after various post-irradiation (repair) times (1 day, 7 days, 14 days). To consolidate and mechanistically support the endothelial cell response to X-ray exposure identified via microarray analysis, DNA repair signaling (γH2AX/TP53BP1-foci quantification), cell cycle progression (BrdU/7AAD flow cytometric analysis), cellular senescence (β-galactosidase assay with CPRG and IGFBP7 quantification) and pro-inflammatory status (IL6 and CCL2) was assessed.

Results: Microarray results indicated persistent changes in cell cycle progression and inflammation. Cells underwent G1 arrest in a dose-dependent manner after high doses (0.5 and 2 Gy), which was compensated by increased proliferation after 1 week and almost normalized after 2 weeks. However, at this point irradiated cells showed an increased β-Gal activity and IGFBP7 secretion, indicative of premature senescence. The production of pro-inflammatory cytokines IL6 and CCL2 was increased at early time points.

Conclusions: IR induces pro-atherosclerotic processes in endothelial cells in a dose-dependent manner. These findings give an incentive for further research on the shape of the dose-response curve, as we show that even low doses of IR can induce premature endothelial senescence at later time points. Furthermore, our findings on the time- and dose-dependent response regarding differentially expressed genes, cell cycle progression, inflammation and senescence bring novel insights into the underlying molecular mechanisms of the endothelial response to X-ray radiation. This may in turn lead to the development of risk-reducing strategies to prevent IR-induced CVD, such as the use of cell cycle modulators and anti-inflammatory drugs as radioprotectors and/or radiation mitigators.

Toward biotechnology in space: High-throughput instruments for in situ biological research beyond Earth

Space biotechnology is a nascent field aimed at applying tools of modern biology to advance our goals in space exploration. These advances rely on our ability to exploit in situ high throughput techniques for amplification and sequencing DNA, and measuring levels of RNA transcripts, proteins and metabolites in a cell. These techniques, collectively known as "omics" techniques have already revolutionized terrestrial biology. A number of on-going efforts are aimed at developing instruments to carry out "omics" research in space, in particular on board the International Space Station and small satellites. For space applications these instruments require substantial and creative reengineering that includes automation, miniaturization and ensuring that the device is resistant to conditions in space and works independently of the direction of the gravity vector. Different paths taken to meet these requirements for different "omics" instruments are the subjects of this review. The advantages and disadvantages of these instruments and technological solutions and their level of readiness for deployment in space are discussed. Considering that effects of space environments on terrestrial organisms appear to be global, it is argued that high throughput instruments are essential to advance (1) biomedical and physiological studies to control and reduce space-related stressors on living systems, (2) application of biology to life support and in situ resource utilization, (3) planetary protection, and (4) basic research about the limits on life in space. It is also argued that carrying out measurements in situ provides considerable advantages over the traditional space biology paradigm that relies on post-flight data analysis.

13N-Ammonia PET/CT Detection of Myocardial Perfusion Abnormalities in Beagle Dogs After Local Heart Irradiation

Our objective was to determine the potential value of ¹³N-ammonia PET/CT myocardial perfusion imaging (MPI) for early detection of myocardial perfusion changes induced by radiation damage. Methods: Thirty-six Beagle dogs were randomly divided into a control group (n = 18) or an irradiation group (n = 18). The latter underwent local irradiation to the left ventricular anterior cardiac wall with a single dose of 20 Gy, whereas the former received sham irradiation. All dogs underwent ¹³N-ammonia PET/CT MPI 1 wk before irradiation and at 3, 6, and 12 mo after sham or local irradiation. One week after undergoing ¹³N-ammonia PET/CT MPI, the irradiation group underwent coronary angiography. Six randomly selected dogs from each group were sacrificed and used to detect pathologic cardiac injury at 3, 6, and 12 mo after irradiation. Results: Compared with the control group and baseline, the irradiation group showed significantly increased perfusion in the irradiated area of the heart at 3 mo after irradiation, perfusion reduction at 6 mo after irradiation, and a perfusion defect at 12 mo after irradiation. There was no significant difference in the left ventricular ejection fraction between the control and irradiation groups at baseline or at 3 mo after irradiation. The irradiation group showed a reduction of left ventricular ejection fraction compared with the control group at 6 mo (50.0% ± 8.1% vs. 59.3% ± 4.1%, P = 0.016) and 12 mo (47.2% ± 6.7% vs. 57.4% ± 3.3%, P = 0.002) after irradiation. No coronary stenosis was observed in the irradiation group. Regional wall motion abnormalities appeared in the irradiated area at 6 mo after irradiation, and its extent was enlarged at 12 mo after irradiation. Pathologic changes were observed; radiation-induced myocardial tissue damage and microvascular fibrosis in the irradiated area progressively increased over time. Conclusion:¹³N-ammonia PET/CT MPI can dynamically detect myocardial perfusion changes together with global and regional left ventricular dysfunction induced by irradiation and may be a valuable method for monitoring radiation-induced heart disease.