Simvastatin mitigates increases in risk factors for and the occurrence of cardiac disease following 10 Gy total body irradiation

Advances in injectable hydrogels for radiation-induced heart disease

Radiological heart damage (RIHD) is damage caused by unavoidable irradiation of the heart during chest radiotherapy, with a long latency period and a progressively increasing proportion of delayed cardiac damage due to conventional doses of chest radiotherapy. There is a risk of inducing diseases such as acute/chronic pericarditis, myocarditis, delayed myocardial fibrosis and damage to the cardiac conduction system in humans, which can lead to myocardial infarction or even death in severe cases. This paper details the pathogenesis of RIHD and gives potential targets for treatment at the molecular and cellular level, avoiding the drawbacks of high invasiveness and immune rejection due to drug therapy, medical device implantation and heart transplantation. Injectable hydrogel therapy has emerged as a minimally invasive tissue engineering therapy to provide necessary mechanical support to the infarcted myocardium and to act as a carrier for various bioactive factors and cells to improve the cellular microenvironment in the infarcted area and induce myocardial tissue regeneration. Therefore, this paper combines bioactive factors and cellular therapeutic mechanisms with injectable hydrogels, presents recent advances in the treatment of cardiac injury after RIHD with different injectable gels, and summarizes the therapeutic potential of various types of injectable hydrogels as a potential solution.

A multimodality assessment of the protective capacity of statin therapy in a mouse model of radiation cardiotoxicity

PURPOSE

Despite technological advances in radiotherapy (RT), cardiotoxicity remains a common complication in patients with lung, oesophageal and breast cancers. Statin therapy has been shown to have pleiotropic properties beyond its lipid-lowering effects. Previous murine models have shown statin therapy can reduce short-term functional effects of whole-heart irradiation. In this study, we assessed the efficacy of atorvastatin in protecting against the late effects of radiation exposure on systolic function, cardiac conduction, and atrial natriuretic peptide (ANP) following a clinically relevant partial-heart radiation exposure.

MATERIALS AND METHODS

Female, 12-week old, C57BL/6j mice received an image-guided 16 Gy X-ray field to the base of the heart using a small animal radiotherapy research platform (SARRP), with or without atorvastatin from 1 week prior to irradiation until the end of the experiment. The animals were followed for 50 weeks with longitudinal transthoracic echocardiography (TTE) and electrocardiography (ECG) every 10 weeks, and plasma ANP every 20 weeks.

RESULTS

At 30-50 weeks, mild left ventricular systolic function impairment observed in the RT control group was less apparent in animals receiving atorvastatin. ECG analysis demonstrated prolongation of components of cardiac conduction related to the heart base at 10 and 30 weeks in the RT control group but not in animals treated with atorvastatin. In contrast to systolic function, conduction disturbances resolved at later time-points with radiation alone. ANP reductions were lower in irradiated animals receiving atorvastatin at 30 and 50 weeks.

CONCLUSIONS

Atorvastatin prevents left ventricular systolic dysfunction, and the perturbation of cardiac conduction following partial heart irradiation. If confirmed in clinical studies, these data would support the use of statin therapy for cardioprotection during thoracic radiotherapy.

BRD2 protects the rat H9C2 cardiomyocytes from hypoxia‑reoxygenation injury by targeting Nrf2/HO‑1 signaling pathway

Myocardial ischemia-reperfusion (I/R) injury is a common complication of acute myocardial infarction following percutaneous coronary intervention, but there are currently no effective pharmacological targets for adjuvant therapy due to a lack of knowledge of I/R injury mechanisms in cardiomyocytes. To evaluate the effects of hypoxia-reoxygenation on the plasma proteome of cardiomyocytes and prospective therapeutic targets, five sets of H9C2 cardiomyocytes from rats were cultured under various hypoxic circumstances. Using Cell Counting Kit-8 (CCK8) and lactose dehydrogenase (LDH) release assays, the cell viability and LDH release of H9C2 cells were analyzed. Proteome sequencing was then performed on cardiomyocytes to show the quantitative protein changes during the I/R injury process. After hypoxia/reoxygenation, bromodomain-containing protein 2 (BRD2) expression was evaluated. After administering the BRD2 inhibitor dBET1, the expression of nuclear factor erythroid 2-related factor 2/haem oxygenase-1 (Nrf2/HO-1) was identified. The results showed that in the group exposed to 4 h of hypoxia followed by 4 h of reoxygenation (H/R4), the cell survival rate was dramatically reduced, although the apoptotic rate and LDH were much higher than in the normal oxygen group. In addition, the expressions of 2,325 proteins differed considerably between these two groups, with 128 upregulated and 122 downregulated proteins being discovered in the H/R4 group. After 4 h of reoxygenation, the BRD2 expression was increased. Following the addition of dBET1 to suppress BRD2, the expression of Nrf2/HO-1 was reduced, but the rate of apoptosis increased. In conclusion, through the Nrf2/HO-1 signaling pathway, BRD2 protects cardiomyocytes from damage caused by hypoxia/reoxygenation. This may have implications for novel treatment targets to minimize I/R damage to the myocardium.

Association between statin therapy dose intensity and radiation cardiotoxicity in non-small cell lung cancer: Results from the NI-HEART study

INTRODUCTION

Radiation cardiotoxicity is a dose-limiting toxicity and major survivorship issue for patients with non-small cell lung cancer (NSCLC) completing curative-intent radiotherapy, however patients' cardiovascular baseline is not routinely optimised prior to treatment. In this study we examined the impact of statin therapy on overall survival and post-radiotherapy cardiac events.

METHODS

Patients treated between 2015-2020 at a regional center were identified. Clinical notes were interrogated for baseline patient, tumor and cardiac details, and both follow-up cancer control and cardiac events. Three cardiologists verified cardiac events. Radiotherapy planning scans were retrieved for application of validated deep learning-based autosegmentation. Pre-specified Cox regression analyses were generated with varying degrees of adjustment for overall survival. Fine and Gray regression for the risk of cardiac events, accounting for the competing risk of death and cardiac covariables was undertaken.

RESULTS

Statin therapy was prescribed to 59% of the 478 included patients. The majority (88%) of patients not prescribed a statin had at least one indication for statin therapy according to cardiovascular guidelines. In total, 340 patients (71%) died and 79 patients (17%) experienced a cardiac event. High-intensity (HR 0.68, 95%CI 0.50-0.91, p = 0.012) and medium-intensity (HR 0.70, 95%CI 0.51-0.97, p = 0.033) statin therapy were associated with improved overall survival after adjustment for patient, cancer, treatment, response and cardiovascular clinical factors. There were no consistent differences in the rate or grade of cardiac events according to statin intensity.

CONCLUSIONS

Statin therapy is associated with improved overall survival in patients receiving curative-intent radiotherapy for NSCLC, and there is evidence of a dose-response relationship. This study highlights the importance of a pre-treatment cardiovascular risk assessment in this cohort. Further studies are needed to examine if statin therapy is cardioprotective in patients undergoing treatment for NSCLC with considerable incidental cardiac radiation dose and a low baseline cardiac risk.

Making connections: the scientific impact and mentoring legacy of Dr. John E. Moulder

PURPOSE

The intent of this mini review is to pay homage to Dr. John E. Moulder's long and successful career in radiation science with the Medical College of Wisconsin. This effort will be done from the perspective of his history of U.S. Government funding for research into the biological pathways involved in radiation-induced normal tissue injuries, especially damage to the kidneys and heart, and pharmacological interventions. In addition, the impact of his steady guidance and leadership in the mentoring of junior scientists, and the development of meaningful collaborations with other researchers will be highlighted.

CONCLUSION

Dr. John E. Moulder's contributions to the field of radiation research, through his strong character and reputation, his consistent and dedicated commitment to his colleagues and students, and his significant scientific advances, have been critical to moving the science forward, and will not be forgotten by those who knew him personally or through publications documenting his important work.

Murine models of radiation cardiotoxicity: A systematic review and recommendations for future studies

BACKGROUND AND PURPOSE

The effects of radiation on the heart are dependent on dose, fractionation, overall treatment time, and pre-existing cardiovascular pathology. Murine models have played a central role in improving our understanding of the radiation response of the heart yet a wide range of exposure parameters have been used. We evaluated the study design of published murine cardiac irradiation experiments to assess gaps in the literature and to suggest guidance for the harmonisation of future study reporting.

METHODS AND MATERIALS

A systematic review of mouse/rat studies published 1981-2021 that examined the effect of radiation on the heart was performed. The protocol was published on PROSPERO (CRD42021238921) and the findings were reported in accordance with the PRISMA guidance. Risk of bias was assessed using the SYRCLE checklist.

RESULTS

159 relevant full-text original articles were reviewed. The heart only was the target volume in 67% of the studies and simulation details were unavailable for 44% studies. Dosimetry methods were reported in 31% studies. The pulmonary effects of whole and partial heart irradiation were reported in 13% studies. Seventy-eight unique dose-fractionation schedules were evaluated. Large heterogeneity was observed in the endpoints measured, and the reporting standards were highly variable.

CONCLUSIONS

Current murine models of radiation cardiotoxicity cover a wide range of irradiation configurations and latency periods. There is a lack of evidence describing clinically relevant dose-fractionations, circulating biomarkers and radioprotectants. Recommendations for the consistent reporting of methods and results of in vivo cardiac irradiation studies are made to increase their suitability for informing the design of clinical studies.

Myocardial Ischemia Related to Common Cancer Therapy-Prevention Insights

Modern antineoplastic therapy improves survival and quality of life in cancer patients, but its indisputable benefits are accompanied by multiple and major side effects, such as cardiovascular ones. Endothelial dysfunction, arterial spasm, intravascular thrombosis, and accelerated atherosclerosis affect the coronary arteries, leading to acute and chronic coronary syndromes that negatively interfere with the oncologic treatment. The cardiac toxicity of antineoplastic agents may be mitigated by using adequate prophylactic measures. In the absence of dedicated guidelines, our work provides the most comprehensive, systematized, structured, and up-to-date analyses of the available literature focusing on measures aiming to protect the coronary arteries from the toxicity of cancer therapy. Our work facilitates the implementation of these measures in daily practice. The ultimate goal is to offer clinicians the necessary data for a personalized therapeutic approach for cancer patients receiving evidence-based oncology treatments with potential cardiovascular toxicity.

Communicating cardiovascular risk to high-risk cancer survivors: a mixed-methods pilot study of a statin risk communication tool

PURPOSE

Childhood, adolescent, and young adult cancer survivors treated with radiation therapy (RT) may be unaware of their high cardiovascular disease (CVD) risk or how to mitigate it. Tools are needed to improve understanding. We developed and pilot-tested a risk communication tool for shared decision-making with survivors regarding CVD risk reduction with statin therapy. We included quantitative and qualitative arms to further tool development and testing.

METHODS

The statin risk communication tool was adapted from a previously validated tool. Patients were at increased risk for CVD due to history of chest RT and recruited to usual care and intervention arms. The post-visit survey included Likert-like scales to explore acceptability of the tool, knowledge questions, and a decisional conflict scale. This pilot study used descriptive statistics and was not powered for significance. Semi-structured interviews with intervention arm participants explored shared decision-making processes.

RESULTS

Median participant (n = 46) age was 45. Most intervention patients (22/24, 92%) and 50% (11/22) of controls found statin information acceptable while 31% (7/22) of the control arm selected "not applicable" regarding information acceptability. Most participants were unaware of their personal CVD risk or potential statin side effects. In semi-structured interviews, participants found the tool is helpful to visualize risk and aid conversations.

CONCLUSIONS

The risk communication tool was acceptable. Qualitative data suggested the tool improved decisional clarity and comfort.

IMPLICATIONS FOR CANCER SURVIVORS

Poor knowledge of CVD and statins and poor recall of CVD risk conversation suggest a need to continue to optimize conversations regarding cardiovascular risk and statin therapy.

Radiotherapy-induced heart disease: a review of the literature

Radiotherapy as one of the four pillars of cancer therapy plays a critical role in the multimodal treatment of thoracic cancers. Due to significant improvements in overall cancer survival, radiotherapy-induced heart disease (RIHD) has become an increasingly recognized adverse reaction which contributes to major radiation-associated toxicities including non-malignant death. This is especially relevant for patients suffering from diseases with excellent prognosis such as breast cancer or Hodgkin’s lymphoma, since RIHD may occur decades after radiotherapy. Preclinical studies have enriched our knowledge of many potential mechanisms by which thoracic radiotherapy induces heart injury. Epidemiological findings in humans reveal that irradiation might increase the risk of cardiac disease at even lower doses than previously assumed. Recent preclinical studies have identified non-invasive methods for evaluation of RIHD. Furthermore, potential options preventing or at least attenuating RIHD have been developed. Ongoing research may enrich our limited knowledge about biological mechanisms of RIHD, identify non-invasive early detection biomarkers and investigate potential treatment options that might attenuate or prevent these unwanted side effects. Here, we present a comprehensive review about the published literature regarding clinical manifestation and pathological alterations in RIHD. Biological mechanisms and treatment options are outlined, and challenges in RIHD treatment are summarized.

Simvastatin Alleviates Intestinal Ischemia/Reperfusion Injury by Modulating Omi/HtrA2 Signaling Pathways

PURPOSE

The objective of this research was to survey the therapeutic action of simvastatin (Sim) on intestinal ischemia/reperfusion injury (II/RI) by modulating Omi/HtrA2 signaling pathways.

METHODS

Sprague Dawley rats were pretreated with 40 mg/kg Sim and then subjected to 1 hour of ischemia and 3 hours of reperfusion. The blood and intestinal tissues were collected, pathologic injury was observed, the contents of serum tumor necrosis factor-α and interleukin-6 (IL-6) were estimated, and superoxide dismutase, methane dicarboxylic aldehyde, and cysteinyl aspartate specific proteinase-3 (caspase-3) levels, as well as the expressions of Omi/HtrA2 and caspase-3, were measured in the intestinal tissues.

RESULTS

Sim preconditioning mitigated the damnification of intestinal tissues by decreasing oxidative stress, inflammatory damage, and apoptosis and downregulating the expression of Omi/HtrA2 compared to the ischemia/reperfusion group, while Sim+Ucf-101 significantly augmented this effect.

CONCLUSION

These results suggest that Sim may alleviate intestinal ischemia/reperfusion injury by modulating Omi/HtrA2 signaling pathways.

Age at Exposure to Radiation Determines Severity of Renal and Cardiac Disease in Rats

Radiotherapy with sparsely ionizing photons is a cornerstone of successful cancer treatment. Age at time of exposure to radiation is known to influence biological outcomes for many end points. The effect of dose and age at exposure upon the occurrence of radiogenic cardiovascular disease is poorly understood. The goal of this work was to determine the response of maleWAG/RijCmcr rats at 6 months of age to gamma rays, and at 6 months or 6 weeks of age to X rays, using clinically relevant biomarkers of cardiovascular disease and kidney injury. Overall, there were significant radiation-induced effects on the levels of bicarbonate (P=0.0016), creatinine (P=0.0002), calcium (P = 0.0009), triglycerides (P = 0.0269) and blood urea nitrogen, albumin, protein, AST, alkaline phosphatase, total cholesterol and HDL (all P < 0.0001). Of those variables with a significant radiation-dose effect, there were significant modifications by age at time of exposure for bicarbonate (P = 0.0033), creatinine (P = 0.0015), AST (P = 0.0040), total cholesterol (P = 0.0006) and blood urea nitrogen, calcium, albumin, protein, alkaline phosphatase and HDL (all P < 0.0001). Cardiac perivascular collagen content was significantly increased in rats that were 8.0 Gy X-ray irradiated at 6 weeks of age (P < 0.047) but not at 6 months of age. While systemic blood pressure was elevated in both cohorts after 8.0 Gy X-ray irradiation (compared to agematched sham-irradiated controls), the magnitude of the increase above baseline was greater in the younger rats (P < 0.05). These findings indicate that dose and age at time of irradiation determine the timeline and severity of cardiac and renal injury.

The effects of Radix Angelica Sinensis and Radix Hedysari ultrafiltration extract on X-irradiation-induced myocardial fibrosis in rats

Radix Angelica Sinensis and Radix Hedysari are traditional Chinese medicines that are used for preventing and treating various diseases. This study aimed to investigate the effect and possible underlying mechanisms of Radix Angelica Sinensis and Radix Hedysari ultrafiltration extract (RAS-RH) on X-irradiation-induced cardiac fibrosis in rats. Our data demonstrated that (a) a single dose of total body irradiation (TBI) at 8 Gy resulted in cardiac fibrosis, whereas the control hearts exhibited less collagen and fibrosis. RAS-RH mitigated these morphological injuries. (b) TBI resulted in an increase in the serum levels of transforming growth factor β1 (TGF-β1) and troponin-I (TnI). RAS-RH inhibited the release of TBI-induced serum TGF-β1 and the TnI levels. (c) TBI inhibited the apoptosis of primary rat cardiac fibroblasts, whereas RAS-RH induced the apoptosis of primary rat cardiac fibroblasts after X- irradiation. (d) TBI resulted in an increase in the expression of osteopontin (OPN), c-fos, c-jun, miRNA-21 and collagen1α (COL1α) in primary rat cardiac fibroblasts, and RAS-RH mitigated the TBI-induced increased expression of OPN, c-jun, miRNA-21 and COL1α. In conclusion, these results demonstrate that RAS-RH exerts antifibrotic effects possibly through inducing the apoptosis of fibroblasts, inhibiting the release of serum TGF-β1, reducing the levels of serum TnI and reducing the expression of OPN, c-jun, miRNA-21 and COL1α. Therefore, RAS-RH may potentially be developed as a medical countermeasure for the mitigation of radiation-induced myocardial fibrosis.

Bone marrow mesenchymal stem cell transplantation improves radiation-induced heart injury through DNA damage repair in rat model

Radiotherapy is an effective form of therapy for most thoracic malignant tumors. However, myocardial injury resulting from the high doses of radiation is a severe complication. Here we aimed to study the possibility of reducing radiation-induced myocardial injury with mesenchymal stem cell (MSC) transplantation. We used MSCs extracted from bone marrow (BMSCs) to transplant via the tail vein into a radiation-induced heart injury (RIHI) rat model. The rats were divided into six groups: a Sham group, an IRR (irradiation) group, and four IRR + BMSCs transplantation groups obtained at different time points. After irradiation, BMSC transplantation significantly enhanced the cardiac function in rats. By analyzing the expression of PPAR-α, PPAR-γ, TGF-β, IL-6, and IL-8, we found that BMSC transplantation alleviated radiation-induced myocardial fibrosis and decreased the inflammatory reaction. Furthermore, we found that expression of γ-H2AX, XRCC4, DNA ligase4, and TP53BP1, which are associated with DNA repair, was up-regulated, along with increased secretion of growth factors SDF-1, CXCR4, VEGF, and IGF in rat myocardium in the IRR + BMSCs transplantation groups compared with the IRR group. Thus, BMSC transplantation has the potential to improve RIHI via DNA repair and be a new therapeutic approach for patients with myocardial injury.

Effects of ionizing radiation on the heart

This article provides an overview of studies addressing effects of ionizing radiation on the heart. Clinical studies have identified early and late manifestations of radiation-induced heart disease, a side effect of radiation therapy to tumors in the chest when all or part of the heart is situated in the radiation field. Studies in preclinical animal models have contributed to our understanding of the mechanisms by which radiation may injure the heart. More recent observations in human subjects suggest that ionizing radiation may have cardiovascular effects at lower doses than was previously thought. This has led to examinations of low-dose photons and low-dose charged particle irradiation in animal models. Lastly, studies have started to identify non-invasive methods for detection of cardiac radiation injury and interventions that may prevent or mitigate these adverse effects. Altogether, this ongoing research should increase our knowledge of biological mechanisms of cardiovascular radiation injury, identify non-invasive biomarkers for early detection, and potential interventions that may prevent or mitigate these adverse effects.