Nuclear magnetic resonance spectroscopy reveals metabolic changes in living cardiomyocytes after low doses of ionizing radiation

Radiation-Induced Macrovessel/Microvessel Disease

Radiation therapy (RT) is a cornerstone in cancer treatment (used in 50% of cases), yet challenges persist because damage to normal tissue through direct impact of radiation or bystander effects is inevitable. Injury of macrovessels by RT manifests as obstructive disease, which is akin to atherosclerotic disease. Historically observed in coronary arteries of patients treated for breast cancer and lymphoma, it also affects patients receiving contemporary therapy for lung and chest cancers. Moreover, radiation at various sites can lead to peripheral vascular disease. An aspect of radiation-induced injury that has received little attention is microvascular injury, which typically results from damage to the endothelium and is considered the primary driver of RT-induced toxicity in the skin, kidney, and brain. This review delves into the clinical manifestations of RT-induced vascular disease, signaling pathways, cellular targets affected by radiation injury, and preclinical models of RT-induced vascular injury. The goal is to inspire the development of innovative strategies to prevent RT-related cardiovascular disease.

Mechanistic Insights and Knowledge Gaps in the Effects of Radiation Therapy on Cardiac Arrhythmias

Stereotactic body radiation therapy (SBRT) is an innovative modality for the treatment of refractory ventricular arrhythmias (VAs). Phase 1/2 clinical trials have demonstrated the remarkable efficacy of SBRT at reducing VA burden (by >85%) in patients with good short-term safety. SBRT as an option for VA treatment delivered in an ambulatory nonsedated patient in a single fraction during an outpatient session of 15 to 30 minutes, without added risks of anesthetic or surgery, is clinically relevant. However, the underlying mechanism remains unclear. Currently, the clinical dosing of SBRT has been derived from preclinical studies aimed at inducing transmural fibrosis in the atria. The propitious clinical effects of SBRT appear earlier than the time course for fibrosis. This review addresses the plausible mechanisms by which radiation alters the electrophysiological properties of myocytes and myocardial conduction to impart an antiarrhythmic effect, elucidate clinical observations, and point the direction for further research in this promising area.

Late Effects of Ionizing Radiation on the Ultrastructure of Hepatocytes and Activity of Lysosomal Enzymes in Mouse Liver Irradiated In Vivo

The study aimed to investigate late radiation-induced changes in the histology, ultrastructure, and activity of lysosomal enzymes in mouse liver exposed to ionizing radiation. The experiment was conducted on C57BL/6J male mice whose distal part of the liver was exposed occasionally to single doses of radiation (6 MV photons) during targeted heart irradiation; estimated doses delivered to analyzed tissue were 0.025 Gy, 0.25 Gy, 1 Gy, and 2 Gy. Tissues were collected 40 weeks after irradiation. We have observed that late effects of radiation have an adaptive nature and their intensity was dose-dependent. Morphological changes in hepatocytes included an increased number of primary lysosomes and autophagic vacuoles, which were visible in tissues irradiated with 0.25 Gy and higher doses. On the other hand, a significant increase in the activity of lysosomal hydrolases was observed only in tissues exposed to 2 Gy. The etiology of these changes may be multifactorial and result, among others, from unintentional irradiation of the distal part of the liver and/or functional interaction of the liver with an irradiated heart. In conclusion, we confirmed the presence of late dose-dependent ultrastructural and biochemical changes in mouse hepatocytes after liver irradiation in vivo.

High-resolution magic angle spinning NMR for intact biological specimen analysis: Initial discovery, recent developments, and future directions

High-resolution magic angle spinning (HRMAS) NMR, an approach for intact biological material analysis discovered more than 25 years ago, has been advanced by many technical developments and applied to many biomedical uses. This article provides a history of its discovery, first by explaining the key scientific advances that paved the way for HRMAS NMR's invention, and then by turning to recent developments that have profited from applying and advancing the technique during the last 5 years. Developments aimed at directly impacting healthcare include HRMAS NMR metabolomics applications within studies of human disease states such as cancers, brain diseases, metabolic diseases, transplantation medicine, and adiposity. Here, the discussion describes recent HRMAS NMR metabolomics studies of breast cancer and prostate cancer, as well as of matching tissues with biofluids, multimodality studies, and mechanistic investigations, all conducted to better understand disease metabolic characteristics for diagnosis, opportune windows for treatment, and prognostication. In addition, HRMAS NMR metabolomics studies of plants, foods, and cell structures, along with longitudinal cell studies, are reviewed and discussed. Finally, inspired by the technique's history of discoveries and recent successes, future biomedical arenas that stand to benefit from HRMAS NMR-initiated scientific investigations are presented.

Application of radiation omics in the development of adverse outcome pathway networks: an example of radiation-induced cardiovascular disease

BACKGROUND

Epidemiological studies have indicated that exposure of the heart to doses of ionizing radiation as low as 0.5 Gy increases the risk of cardiac morbidity and mortality with a latency period of decades. The damaging effects of radiation to myocardial and endothelial structures and functions have been confirmed radiobiologically at high dose, but much less is known at low dose. Integration of radiation biology and epidemiology data is a recommended approach to improve the radiation risk assessment process. The adverse outcome pathway (AOP) framework offers a comprehensive tool to compile and translate mechanistic information into pathological endpoints which may be relevant for risk assessment at the different levels of a biological system. Omics technologies enable the generation of large volumes of biological data at various levels of complexity, from molecular pathways to functional organisms. Given the quality and quantity of available data across levels of biology, omics data can be attractive sources of information for use within the AOP framework. It is anticipated that radiation omics studies could improve our understanding of the molecular mechanisms behind the adverse effects of radiation on the cardiovascular system. In this review, we explored the available omics studies on radiation-induced cardiovascular disease (CVD) and their applicability to the proposed AOP for CVD.

RESULTS

The results of 80 omics studies published on radiation-induced CVD over the past 20 years have been discussed in the context of the AOP of CVD proposed by Chauhan et al. Most of the available omics data on radiation-induced CVD are from proteomics, transcriptomics, and metabolomics, whereas few datasets were available from epigenomics and multi-omics. The omics data presented here show great promise in providing information for several key events of the proposed AOP of CVD, particularly oxidative stress, alterations of energy metabolism, extracellular matrix and vascular remodeling.

CONCLUSIONS

The omics data presented here shows promise to inform the various levels of the proposed AOP of CVD. However, the data highlight the urgent need of designing omics studies to address the knowledge gap concerning different radiation scenarios, time after exposure and experimental models. This review presents the evidence to build a qualitative omics-informed AOP and provides views on the potential benefits and challenges in using omics data to assess risk-related outcomes.

The Radioprotective Activity of Resveratrol—Metabolomic Point of View

Resveratrol, a plant-derived polyphenol, is an intensively studied compound with widely documented positive effects on health. Antioxidant activity is the property most often mentioned as responsible for its beneficial effects. Therefore, since the adverse effect of ionizing radiation is primarily related to the induction of oxidative stress, the question arises of whether the use of resveratrol could have a radioprotective effect. This paper summarizes the data on the cytoprotective activity of resveratrol and pieces of evidence for the potential interplay between response to radiation and resveratrol activity. The paper focuses on changes in the metabolic profile of cells and organisms induced by ionizing radiation and exposure to resveratrol. The comparison of metabolic changes induced by both factors provides a rationale for the potential mechanism of the radioprotective effects of resveratrol.

Differential Actions of Muscarinic Receptor Subtypes in Gastric, Pancreatic, and Colon Cancer

Cancers arising from gastrointestinal epithelial cells are common, aggressive, and difficult to treat. Progress in this area resulted from recognizing that the biological behavior of these cancers is highly dependent on bioactive molecules released by neurocrine, paracrine, and autocrine mechanisms within the tumor microenvironment. For many decades after its discovery as a neurotransmitter, acetylcholine was thought to be synthesized and released uniquely from neurons and considered the sole physiological ligand for muscarinic receptor subtypes, which were believed to have similar or redundant actions. In the intervening years, we learned this former dogma is not tenable. (1) Acetylcholine is not produced and released only by neurons. The cellular machinery required to synthesize and release acetylcholine is present in immune, cancer, and other cells, as well as in lower organisms (e.g., bacteria) that inhabit the gut. (2) Acetylcholine is not the sole physiological activator of muscarinic receptors. For example, selected bile acids can modulate muscarinic receptor function. (3) Muscarinic receptor subtypes anticipated to have overlapping functions based on similar G protein coupling and downstream signaling may have unexpectedly diverse actions. Here, we review the relevant research findings supporting these conclusions and discuss how the complexity of muscarinic receptor biology impacts health and disease, focusing on their role in the initiation and progression of gastric, pancreatic, and colon cancers.

Radiotherapy-induced alterations in vitreous humor: A new potential critical structure

Vitreous humor (VH) is not considered as a critical structure in the radiotherapy planning process. In the present study, an experimental animal model was performed to examine the effects of radiotherapy on VH. The right eyes of twelve New Zealand rabbits were irradiated to 60 Gy in 3 fractions in accordance with the scheme used in the treatment of uveal melanoma in our clinic, and contralateral (left) eyes were considered as control. Weekly ophthalmologic examination was performed after irradiation, for three months. At the end of the third month, enucleation and vitreous collection were conducted. The vitreous samples were subjected to metabolomic analyses, ELISA analyses, viscosity measurements, and electron microscopic examination. In control and experimental vitreous samples, 275 different metabolites were identified, and 34 were found to differ significantly between groups. In multivariate analyzes, a clear distinction was observed between control and irradiated vitreous samples. Pathway analysis revealed that nine pathways were affected, and these pathways were mainly related to amino acid metabolism. A significant decrease was observed in the expressions of type II, V, and XI collagens in protein level in the ELISA. There was a non-significant decrease in type IX collagen and viscosity. Electron microscopic examination revealed disrupted collagen fibrillar ultra-structure and dispersed collagen fragments in the experimental vitreous. An intact vitreous is essential for a healthy eye. In this study, we observed that radiation causes changes in the vitreous that may have long-term consequences.

Glutamine metabolism: from proliferating cells to cardiomyocytes

Glutamine is a major energy source for rapidly dividing cells, such as hematopoietic stem cells and cancer cells. Reliance on glutamine is therefore regarded as a metabolic hallmark of proliferating cells. Moreover, reprogramming glutamine metabolism by various factors, including tissue type, microenvironment, pro-oncogenes, and tumor suppressor genes, can facilitate stem cell fate decisions, tumor recurrence, and drug resistance. However, the significance of glutamine metabolism in cardiomyocytes, an end-differentiated cell type, is not fully understood. Existing evidence suggests important roles of glutamine metabolism in the development of cardiovascular diseases. In this review, we have focused on glutaminolysis and its regulatory network in proliferating cells. We have summarized current findings about the role of glutamine utilization in cardiomyocytes and have discussed possibilities of targeting glutamine metabolism for the treatment of cardiovascular diseases.

The Effect of Functional and Intra-Coronary Imaging Techniques on Fluoroscopy Time, Radiation Dose and Contrast Volume during Coronary Angiography

The aim was to analyze the effect of fractional flow reserve (FFR), intravascular ultrasound (IVUS) and optical coherence tomography (OCT) on fluoroscopy time (FT), radiation dose (RD) and contrast volume (CV) in patients undergoing coronary angiography. This case-control study included consecutive patients above the age of 18, who underwent coronary angiography. FT, RD, and CV after each procedure were retrospectively recorded. Multivariate models were used to demonstrate the effect of these complementary studies and other factors, on radiation and contrast exposure. A total of 1047 patients were included, 74.5% were men and the mean (SD) age was 62.4 (12.1) years. Complementary studies performed were: IVUS (n = 237), FFR (n = 56) and OCT (n = 37). FFR and IVUS had a small effect on FT (η = 0.008 B = 2.2, p < 0.001; η = 0.009, B = 2.5, p < 0.001), while OCT had no effect (η = 0.002 B = 2.9, p < 0.183). IVUS, FFR and OCT had no effect on the RD. IVUS did not affect contrast volume (η = 0.002 B = 9.4, p < 0.163) while OCT and FFR had a small effect on CV (η = 0.006 B = 39, p < 0.01; η = 0.008 B = 37, p < 0.003). The number of placed stents had a significant effect on FT (η = 0.192, Β = 4.2, p < 0.001), RD (η = 0.129, Β = 511.8, p < 0.001) and CV (η = 0.177, Β = 40.5, p < 0.001). The use of complementary studies in hemodynamics did not modify the received RD and had a minor effect on FT and the CV used.

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.

Metabolomic Perspectives in Antiblastic Cardiotoxicity and Cardioprotection

Despite advances in supportive and protective therapy for myocardial function, cardiovascular diseases due to antineoplastic therapy-primarily cardiomyopathy associated with contractile dysfunction-remain a major cause of morbidity and mortality. Because of the limitations associated with current therapies, investigators are searching for alternative strategies that can timely recognise cardiovascular damage-thus permitting a quick therapeutic approach-or prevent the development of the disease. Damage to the heart can result from both traditional chemotherapeutic agents, such as anthracyclines, and new targeted therapies, such as tyrosine kinase inhibitors. In recent years, metabolomics has proved to be a practical tool to highlight fundamental changes in the metabolic state in several pathological conditions. In this article, we present the state-of-the-art technology with regard to the metabolic mechanisms underlying cardiotoxicity and cardioprotection.