Hypoxia inducible factor 1alpha signaling in fractionated radiation-induced lung injury: role of oxidative stress and tissue hypoxia

Oxidative Stress: An Intersection Between Radiation and Sulfur Mustard Lung Injury

Nuclear and chemical weapons of mass destruction share both a tragic and beneficial legacy in mankind's history and health. The horrific health effects of ionizing radiation and mustard gas exposures unleashed during disasters, wars, and conflicts have been harnessed to treat human health maladies. Both agents of destruction have been transformed into therapies to treat a wide range of cancers. The discovery of therapeutic uses of radiation and sulfur mustard was largely due to observations by clinicians treating victims of radiation and sulfur mustard gas exposures. Clinicians identified vulnerability of leukocytes to these agents and repurposed their use in the treatment of leukemias and lymphomas. Given the overlap in therapeutic modalities, it goes to reason that there may be common mechanisms to target as protective strategies against their damaging effects. This commentary will highlight oxidative stress as a common mechanism shared by both radiation and sulfur mustard gas exposures and discuss potential therapies targeting oxidative stress as medical countermeasures against the devastating lung diseases wrought by these agents.

The clinical manifestations and molecular pathogenesis of radiation fibrosis

Advances in radiation techniques have enabled the precise delivery of higher doses of radiotherapy to tumours, while sparing surrounding healthy tissues. Consequently, the incidence of radiation toxicities has declined, and will likely continue to improve as radiotherapy further evolves. Nonetheless, ionizing radiation elicits tissue-specific toxicities that gradually develop into radiation-induced fibrosis, a common long-term side-effect of radiotherapy. Radiation fibrosis is characterized by an aberrant wound repair process, which promotes the deposition of extensive scar tissue, clinically manifesting as a loss of elasticity, tissue thickening, and organ-specific functional consequences. In addition to improving the existing technologies and guidelines directing the administration of radiotherapy, understanding the pathogenesis underlying radiation fibrosis is essential for the success of cancer treatments. This review integrates the principles for radiotherapy dosimetry to minimize off-target effects, the tissue-specific clinical manifestations, the key cellular and molecular drivers of radiation fibrosis, and emerging therapeutic opportunities for both prevention and treatment.

Adipose-derived stem cells repair radiation-induced chronic lung injury via inhibiting TGF-β1/Smad 3 signaling pathway

To investigate the effect of adipose-derived stem cells (ASCs) transplantation on radiation-induced lung injury (RILI), Sprague-Dawley rats were divided into phosphate-buffered saline (PBS) group, ASCs group, Radiation + PBS group, and Radiation + ASCs group. Radiation + PBS and Radiation + ASCs groups received single dose of 30 Gy X-ray radiation to the right chest. The Radiation + PBS group received 1 mL PBS suspension and Radiation + ASCs group received 1 mL PBS suspension containing 1 × 107 CM-Dil-labeled ASCs. The right lung tissue was collected on Days 30, 90, and 180 after radiation. Hematoxylin-eosin and Masson staining were performed to observe the pathological changes and collagen fiber content in the lung tissue. Immunohistochemistry (IHC) and western blot (WB) were used to detect levels of fibrotic markers collagen I (Collal), fibronectin (FN), as well as transforming growth factor-β1 (TGF-β1), p-Smad 3, and Smad 3. Compared with the non-radiation groups, the radiation groups showed lymphocyte infiltration on Day 30 after irradiation and thickened incomplete alveolar walls, collagen deposition, and fibroplasia on Days 90 and 180. ASCs relieved these changes on Day 180 (Masson staining, P = 0.0022). Compared with Radiation + PBS group, on Day 180 after irradiation, the Radiation + ASCs group showed that ASCs could significantly decrease the expressions of fibrosis markers Collal (IHC: P = 0.0022; WB: P = 0.0087) and FN (IHC: P = 0.0152; WB: P = 0.026) and inhibit the expressions of TGF-β1 (IHC: P = 0.026; WB: P = 0.0152) and p-Smad 3 (IHC: P = 0.0043; WB: P = 0.0087) in radiation-induced injured lung tissue. These indicated that ASCs could relieve RILI by inhibiting TGF-β1/Smad 3 signaling pathway.

Review of Osteoradionecrosis of the Jaw: Radiotherapy Modality, Technique, and Dose as Risk Factors

Radiotherapy (RT) or concurrent chemoradiotherapy (CCRT) is the cornerstone of organ-sparing or adjuvant therapy for nearly all head and neck cancers. Unfortunately, aggressive RT or CCRT can result in severe late toxicities, such as osteoradionecrosis of the jaws (ORNJ). The incidence of ORNJ is currently less than 5-6% due to advances in dental preventive care programs, RT planning systems, and RT techniques. Although numerous patient-, tumor-, and treatment-related factors may influence the incidence rates of ORNJ, RT modality (equipment), technique, and dose-volume-related factors are three of the most influential factors. This is mainly because different RT equipment and techniques have different levels of success at delivering the prescribed dose to the focal volume of the treatment while keeping the "organ at risk" safe. ORNJ risk is ultimately determined by mandibular dose, despite the RT technique and method being known predictors. Regardless of the photon delivery method, the radiobiological effects will be identical if the total dose, dose per fraction, and dose distribution within the tissue remain constant. Therefore, contemporary RT procedures mitigate this risk by reducing mandibular dosages rather than altering the ionizing radiation behavior in irradiated tissues. In light of the paucity of studies that have examined the impact of RT modality, technique, and dose-volume-related parameters, as well as their radiobiological bases, the present review aims to provide a comprehensive overview of the published literature on these specific issues to establish a common language among related disciplines and provide a more reliable comparison of research results.

Single Cell Transcriptomics of Fibrotic Lungs Unveils Aging-associated Alterations in Endothelial and Epithelial Cell Regeneration

Lung regeneration deteriorates with aging leading to increased susceptibility to pathologic conditions, including fibrosis. Here, we investigated bleomycin-induced lung injury responses in young and aged mice at single-cell resolution to gain insights into the cellular and molecular contributions of aging to fibrosis. Analysis of 52,542 cells in young (8 weeks) and aged (72 weeks) mice identified 15 cellular clusters, many of which exhibited distinct injury responses that associated with age. We identified Pdgfra + alveolar fibroblasts as a major source of collagen expression following bleomycin challenge, with those from aged lungs exhibiting a more persistent activation compared to young ones. We also observed age-associated transcriptional abnormalities affecting lung progenitor cells, including ATII pneumocytes and general capillary (gCap) endothelial cells (ECs). Transcriptional analysis combined with lineage tracing identified a sub-population of gCap ECs marked by the expression of Tropomyosin Receptor Kinase B (TrkB) that appeared in bleomycin-injured lungs and accumulated with aging. This newly emerged TrkB + EC population expressed common gCap EC markers but also exhibited a distinct gene expression signature associated with aberrant YAP/TAZ signaling, mitochondrial dysfunction, and hypoxia. Finally, we defined ACKR1 + venous ECs that exclusively emerged in injured lungs of aged animals and were closely associated with areas of collagen deposition and inflammation. Immunostaining and FACS analysis of human IPF lungs demonstrated that ACKR1 + venous ECs were dominant cells within the fibrotic regions and accumulated in areas of myofibroblast aggregation. Together, these data provide high-resolution insights into the impact of aging on lung cell adaptability to injury responses.

The clinical effect of radiotherapy on pulpal microvasculature: a systematic review

Introduction/objectives Radiotherapy (RT) has a detrimental effect on the histomorphology of oral tissues. Patients undergoing RT are at risk of developing macrovascular and microvascular changes, which can lead to significant clinical consequences. Despite advances in RT delivery systems, radiation injury remains a modern-day clinical problem. The aim of this systematic review is to investigate the available evidence regarding the impact of RT to the dental pulp and the clinical manifestations of these effects.Data and sources A multi-database search (PubMed, Medline, Embase and CINAHL) was performed to identify related papers published from inception until November 2021. An additional manual search was performed to identify further articles. The data extracted from relevant papers were analysed according to the outcomes selected in this review.Study selection The search generated seven articles eligible for analysis with a total of 2,709 teeth included. RT dose exposure ranged from 30-71.2 Gray with a common finding that RT decreases the number of teeth responding to pulp sensibility testing.Conclusions Knowledge related to the impact of RT on dental pulp is limited and based on weak evidence and a low-level quality of studies. Future studies should incorporate exact RT doses to the teeth and use replicable pulpal testing methods. Understanding the pulpal status post-RT remains an important consideration as dental extractions should be avoided in this cohort due to the risk of osteoradionecrosis.

Lung Pneumonitis and Fibrosis in Cancer Therapy: A Review on Cellular and Molecular Mechanisms

Fibrosis and pneumonitis are the most important side effects of lung tissue following cancer therapy. Radiotherapy and chemotherapy by some drugs, such as bleomycin, can induce pneumonitis and fibrosis. Targeted therapy and immunotherapy also may induce pneumonitis and fibrosis to a lesser extent compared to chemotherapy and radiotherapy. Activation of lymphocytes by immunotherapy or infiltration of inflammatory cells such as macrophages, lymphocytes, neutrophils, and mast cells following chemo/radiation therapy can induce pneumonitis. Furthermore, the polarization of macrophages toward M2 cells and the release of anti-inflammatory cytokines stimulate fibrosis. Lung fibrosis and pneumonitis may also be potentiated by some other changes such as epithelial-mesenchymal transition (EMT), oxidative stress, reduction/oxidation (redox) responses, renin-angiotensin system, and the upregulation of some inflammatory mediators such as a nuclear factor of kappa B (NF-κB), inflammasome, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS). Damages to the lung vascular system and the induction of hypoxia also can induce pulmonary injury following chemo/radiation therapy. This review explains various mechanisms of the induction of pneumonitis and lung fibrosis following cancer therapy. Furthermore, the targets and promising agents to mitigate lung fibrosis and pneumonitis will be discussed.

Adaptive Responses to Hypoxia and/or Hyperoxia in Humans

Significance: Oxygen is indispensable for aerobic life, but its utilization exposes cells and tissues to oxidative stress; thus, tight regulation of cellular, tissue, and systemic oxygen concentrations is crucial. Here, we review the current understanding of how the human organism (mal-)adapts to low (hypoxia) and high (hyperoxia) oxygen levels and how these adaptations may be harnessed as therapeutic or performance enhancing strategies at the systemic level. Recent Advances: Hyperbaric oxygen therapy is already a cornerstone of modern medicine, and the application of mild hypoxia, that is, hypoxia conditioning (HC), to strengthen the resilience of organs or the whole body to severe hypoxic insults is an important preparation for high-altitude sojourns or to protect the cardiovascular system from hypoxic/ischemic damage. Many other applications of adaptations to hypo- and/or hyperoxia are only just emerging. HC-sometimes in combination with hyperoxic interventions-is gaining traction for the treatment of chronic diseases, including numerous neurological disorders, and for performance enhancement. Critical Issues: The dose- and intensity-dependent effects of varying oxygen concentrations render hypoxia- and/or hyperoxia-based interventions potentially highly beneficial, yet hazardous, although the risks versus benefits are as yet ill-defined. Future Directions: The field of low and high oxygen conditioning is expanding rapidly, and novel applications are increasingly recognized, for example, the modulation of aging processes, mood disorders, or metabolic diseases. To advance hypoxia/hyperoxia conditioning to clinical applications, more research on the effects of the intensity, duration, and frequency of altered oxygen concentrations, as well as on individual vulnerabilities to such interventions, is paramount. Antioxid. Redox Signal. 37, 887-912.

Redox Interactions in Chemo/Radiation Therapy-induced Lung Toxicity; Mechanisms and Therapy Perspectives

Lung toxicity is a key limiting factor for cancer therapy, especially lung, breast, and esophageal malignancies. Radiotherapy for chest and breast malignancies can cause lung injury. However, systemic cancer therapy with chemotherapy may also induce lung pneumonitis and fibrosis. Radiotherapy produces reactive oxygen species (ROS) directly via interacting with water molecules within cells. However, radiation and other therapy modalities may induce the endogenous generation of ROS and nitric oxide (NO) by immune cells and some nonimmune cells such as fibroblasts and endothelial cells. There are several ROS generating enzymes within lung tissue. NADPH Oxidase enzymes, cyclooxygenase-2 (COX-2), dual oxidases (DUOX1 and DUOX2), and the cellular respiratory system in the mitochondria are the main sources of ROS production following exposure of the lung to anticancer agents. Furthermore, inducible nitric oxide synthase (iNOS) has a key role in the generation of NO following radiotherapy or chemotherapy. Continuous generation of ROS and NO by endothelial cells, fibroblasts, macrophages, and lymphocytes causes apoptosis, necrosis, and senescence, which lead to the release of inflammatory and pro-fibrosis cytokines. This review discusses the cellular and molecular mechanisms of redox-induced lung injury following cancer therapy and proposes some targets and perspectives to alleviate lung toxicity.

Hypoxic Cell-Derived Extracellular Vesicles Aggravate Rectal Injury Following Radiotherapy via MiR-122-5p

Radiation-induced rectal injury is a common side effect of radiotherapy. Hypoxia often occurs after radiotherapy. This study aimed to explore the bystander effect of hypoxia on radiation-induced rectal injury. In vivo, apoptosis increased nearby the highly hypoxic area in the rectal tissues in the mouse models of radiation-induced rectal injury, indicating the potential involvement of hypoxia. In vitro, flow cytometry and Western blotting showed that both hypoxia and hypoxic human intestinal epithelial crypt (HIEC) cell supernatant promoted apoptosis in normoxic HIEC cells. The pro-apoptotic effect of extracellular vesicles (EVs) derived from hypoxic HIEC cell to normoxic HIEC cells was then determined. MiR-122-5p was chosen for further studies through a microRNA (miRNA) microarray assay and apoptosis was alleviated in cells receiving miR-122-5p inhibiting hypoxic EVs. Together, our study demonstrated that the miR-122-5p containing-EVs derived from hypoxic HIEC cells promoted apoptosis in normoxic HIEC cells. Hypoxic EV-derived miR-122-5p plays a critical pathologic role in radiation-induced rectal injury and may be a potential therapeutic target.

Identifying Active Substances and the Pharmacological Mechanism of Houttuynia cordata Thunb. in Treating Radiation-Induced Lung Injury Based on Network Pharmacology and Molecular Docking Verification

Background

Houttuynia cordata Thunb. is a traditional Chinese herb widely used mainly because of the pharmacological effects related to heat clearance and detoxification. Emerging clinical evidence indicates that the efficacy of Houttuynia cordata Thunb. on RILI is upstanding. Nevertheless, its underlying therapeutic mechanism remains unclear and warrants further elucidation.

Methods

The major active components and corresponding targets of Houttuynia cordata Thunb. were retrieved from the traditional Chinese medicine system pharmacology database (TCMSP) and literature review. The related targets of RILI were retrieved from the GeneCards database. Common targets among the active compounds and diseases were identified through Venn diagram analysis. Cytoscape was employed to construct and visualize the network relationship among the drug, active compounds, targets, and disease. The protein interaction network (PPI) was constructed by STRING. The reliability (the binding affinity) of the core targets and active compounds was verified by molecular docking.

Results

A search of the TCMSP database and related literature revealed 12 active compounds of Houttuynia cordata Thunb. against RILI. The core active compounds included quercetin, kaempferol, hyperoside, and rutin. Hub nodes including TP53, VEGFA, JUN, TNF, and IL-6 were identified in the PPI network. The GO categories were classified into three functional categories: 112 biological processes, 9 molecular functions, and 32 cellular components of the active compounds of Houttuynia cordata Thunb. The KEGG pathway enrichment analysis demonstrated the enrichment of target genes in several key cancer-related signaling pathways, including the cancer pathways, TNF signaling pathway, PI3K-Akt signaling pathway, and HIF-1 signaling pathway. Molecular docking analysis validated the effective binding capacity of the main active compounds with the core targets.

Conclusion

The main active components of Houttuynia cordata Thunb. have a potential pharmacological effect against RILI via the cancer pathways, TNF signaling pathway, and PI3K-Akt signaling pathway.

Feasibility study for inducing the skeletal muscle fibrosis via irradiation using two mouse strains

PURPOSE

Although the mechanism of onset and progression of radiation-induced fibrosis (RIF) has been studied, most studies to date have focused on pulmonary fibrosis. There are few studies on murine RIF in the skeletal muscle, and the pathogenic mechanism remains unclear. This pilot study aimed to evaluate the feasibility to create a murine model of RIF in the skeletal muscle and analyze strain differences in fibrosis sensitivity.

MATERIALS AND METHODS

Two mouse strains, C57BL/6 and C3H/He, were used. Their right hind limbs were irradiated at a dose of 25 Gy once a week for three fractions. Gastrocnemius muscles were collected at day 4, and weeks 2, 4, 8, 12, and 24 after the third irradiation and subjected to histopathological examination and immunoblotting.

RESULTS

In C57BL/6 mice, chronic inflammation and an increased expression of transforming growth factor-β (TGF-β) and fibronectin were observed 2 weeks after irradiation. A significant increase in fibrosis was detected after 8 weeks. However, in C3H/He mice, the expression of TGF-β and fibronectin increased 8 weeks after irradiation, and fibrosis significantly increased after 12 weeks. Moreover, the degrees of inflammation and fibrosis were more remarkable in C57BL/6 mice than in C3H/He mice.

CONCLUSION

The onset and degree of fibrosis may be associated with the expression of TGF-β and fibronectin, and inflammation, in a strain-specific manner. Therefore, a murine model of RIF in the skeletal muscle could be created using the indicated method, suggesting that the C57BL/6 strain is more sensitive to fibrosis in the skeletal muscle, as well as the lung, than the C3H/He strain. Radiation-induced fibrosis in the skeletal muscle could be detected in C57BL/6 and C3H/He mice, with C57BL/6 mice being more sensitive to fibrosis in the skeletal muscle than C3H/He mice.

TMIGD1 Inhibited Abdominal Adhesion Formation by Alleviating Oxidative Stress in the Mitochondria of Peritoneal Mesothelial Cells

Background

Postoperative abdominal adhesion remains one of the frequent complications after abdominal surgery and lacks effective intervention. Peritoneal mesothelial cell injury and healing play crucial roles in the process of adhesion formation, and identifying this mechanism might provide new insight into possible new therapeutic strategies for this disease. Transmembrane and immunoglobulin domain-containing 1 (TMIGD1) has been proven to protect renal epithelial cells from injury induced by oxidative stress and has also been identified as a novel adhesion molecule. Here, we investigated the role of TMIGD1 and its possible mechanism in adhesion formation.

Materials and Methods

Immunohistochemistry (IHC), qPCR, and immunofluorescence (IHF) were used to detect the expression of TMIGD1. The grade and tenacity score of adhesion were used to evaluate the adhesion formation conditions. A TMIGD1-overexpressing HMrSV5 cell line was established. MTT assay, Western blotting, Annexin V apoptosis analysis, and CK19 staining were used to measure mesothelial cell viability, apoptosis, and completeness. ROS and MDA detection were used to measure mesothelial cell oxidative stress levels. JC-1 staining, IHF, and transmission electron microscopy were performed to assess mitochondrial function. Scratch-wound and adhesion assays were used to evaluate the adhesion ability of mesothelial cells.

Results

First, we showed that TMIGD1 was decreased in mouse abdominal adhesion tissue and peritoneal mesothelial cells. Second, TMIGD1 overexpression inhibited adhesion formation. Third, TMIGD1 overexpression protected mesothelial cells from hydrogen peroxide- (H₂O₂-) induced oxidative stress injury. Fourth, TMIGD1 overexpression alleviated oxidative stress by protecting the mitochondrial function of mesothelial cells. In addition, TMIGD1 overexpression enhanced mesothelial cell adhesion.

Conclusion

Our findings suggest that TMIGD1 protects mesothelial cells from oxidative stress injury by protecting their mitochondrial function, which is decreased in regular abdominal adhesion tissue. In addition, TMIGD1 enhances peritoneal mesothelial cell adhesion to promote healing.

Low dose ionizing radiation effects on the immune system

Ionizing radiation interacts with the immune system in many ways with a multiplicity that mirrors the complexity of the immune system itself: namely the need to maintain a delicate balance between different compartments, cells and soluble factors that work collectively to protect, maintain, and restore tissue function in the face of severe challenges including radiation damage. The cytotoxic effects of high dose radiation are less relevant after low dose exposure, where subtle quantitative and functional effects predominate that may go unnoticed until late after exposure or after a second challenge reveals or exacerbates the effects. For example, low doses may permanently alter immune fitness and therefore accelerate immune senescence and pave the way for a wide spectrum of possible pathophysiological events, including early-onset of age-related degenerative disorders and cancer. By contrast, the so called low dose radiation therapy displays beneficial, anti-inflammatory and pain relieving properties in chronic inflammatory and degenerative diseases. In this review, epidemiological, clinical and experimental data regarding the effects of low-dose radiation on the homeostasis and functional integrity of immune cells will be discussed, as will be the role of immune-mediated mechanisms in the systemic manifestation of localized exposures such as inflammatory reactions. The central conclusion is that ionizing radiation fundamentally and durably reshapes the immune system. Further, the importance of discovery of immunological pathways for modifying radiation resilience amongst other research directions in this field is implied.

A Clinical Study Determining Pulp Vitality in Oropharyngeal Cancer Patients Undergoing Radiotherapy Using Diagnostic Tool-Pulse Oximetry

Pulse oximetry is an equipment that evaluates pulp vitality for concrete endodontic diagnosis and treatment plan. One of the treatment methods of oropharyngeal cancer is radiotherapy. Radiotherapy has some harmful effects on dental pulp that affects pulp vitality. The objective of study was to assess pulp vitality before, at the end of radiotherapy and six months after radiotherapy (RT) in oropharyngeal cancer patients undergoing radiotherapy. 25 patients who were diagnosed with oropharyngeal cancer having asymptomatic intact crowns were selected for the study. Pulp vitality was checked before the commencement of radiotherapy (PV1), immediately after radiotherapy (PV 2) and six months post radiotherapy (PV 3). Pulp vitality of first posterior tooth was selected of each patient and was checked with pulse oximetry. Paired t-test was used as statistical analysis. Statistically significant difference was observed when PV 1 and PV 2, PV 1 and PV 3 and PV 2 and PV 3 were compared amongst each other. There was reduction noted in mean SpO2 value when groups PV 2 and PV1 were compared. This was statistically significant. Statistically significant increase in mean SpO2 value was observed six months post radiotherapy (PV 3). Thus, it can be concluded that statistically significant reduction in mean SpO2 level post radiotherapy recovers after six months.

[18F]FMISO PET/CT imaging of hypoxia as a non-invasive biomarker of disease progression and therapy efficacy in a preclinical model of pulmonary fibrosis: comparison with the [18F]FDG PET/CT approach

Purpose

Idiopathic pulmonary fibrosis (IPF) is a progressive disease with poor outcome and limited therapeutic options. Imaging of IPF is limited to high-resolution computed tomography (HRCT) which is often not sufficient for a definite diagnosis and has a limited impact on therapeutic decision and patient management. Hypoxia of the lung is a significant feature of IPF but its role on disease progression remains elusive. Thus, the aim of our study was to evaluate hypoxia imaging with [¹⁸F]FMISO as a predictive biomarker of disease progression and therapy efficacy in preclinical models of lung fibrosis in comparison with [¹⁸F]FDG.

Methods

Eight-week-old C57/BL6 mice received an intratracheal administration of bleomycin (BLM) at day (D) 0 to initiate lung fibrosis. Mice received pirfenidone (300 mg/kg) or nintedanib (60 mg/kg) by daily gavage from D9 to D23. Mice underwent successive PET/CT imaging at several stages of the disease (baseline, D8/D9, D15/D16, D22/D23) with [¹⁸F]FDG and [¹⁸F]FMISO. Histological determination of the lung expression of HIF-1α and GLUT-1 was performed at D23.

Results

We demonstrate that mean lung density on CT as well as [¹⁸F]FDG and [¹⁸F]FMISO uptakes are upregulated in established lung fibrosis (1.4-, 2.6- and 3.2-fold increase respectively). At early stages, lung areas with [¹⁸F]FMISO uptake are still appearing normal on CT scans and correspond to areas which will deteriorate towards fibrotic lesions at later timepoints. Nintedanib and pirfenidone dramatically and rapidly decreased mean lung density on CT as well as [¹⁸F]FDG and [¹⁸F]FMISO lung uptakes (pirfenidone: 1.2-, 2.9- and 2.6-fold decrease; nintedanib: 1.2-, 2.3- and 2.5-fold decrease respectively). Early [¹⁸F]FMISO lung uptake was correlated with aggressive disease progression and better nintedanib efficacy.

Conclusion

[¹⁸F]FMISO PET imaging is a promising tool to early detect and monitor lung fibrosis progression and therapy efficacy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-021-05209-2.

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

Background

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

Methods

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

Results

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

Conclusion

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

Investigating Ketone Bodies as Immunometabolic Countermeasures against Respiratory Viral Infections

Respiratory viral infections remain a scourge, with seasonal influenza infecting millions and killing many thousands annually and viral pandemics, such as COVID-19, recurring every decade. Age, cardiovascular disease, and diabetes mellitus are risk factors for severe disease and death from viral infection. Immunometabolic therapies for these populations hold promise to reduce the risks of death and disability. Such interventions have pleiotropic effects that might not only target the virus itself but also enhance supportive care to reduce cardiopulmonary complications, improve cognitive resilience, and facilitate functional recovery. Ketone bodies are endogenous metabolites that maintain cellular energy but also feature drug-like signaling activities that affect immune activity, metabolism, and epigenetics. Here, we provide an overview of ketone body biology relevant to respiratory viral infection, focusing on influenza A and severe acute respiratory syndrome (SARS)-CoV-2, and discuss the opportunities, risks, and research gaps in the study of exogenous ketone bodies as novel immunometabolic interventions in these diseases.

Evaluation of HIF-1α and VEGF-A expression in radiation-induced cystitis: A case-control study

The standard treatment for locally advanced cervical cancer (CC) is chemoradiotherapy. Once the bladder receives part of the radiation, a typical inflammatory condition that configures radiation-induced cystitis may develop. Chronic radiation-induced cystitis is commonly characterized by the bladder new submucosal vascularization, which is typically fragile and favors hematuria. The current study aims to investigate if Hypoxia-Induced Factor (HIF-1α) and its transcriptional target Vascular Endothelial Growth Factor A (VEGF-A) could be a primary pathway leading to increased submucosal vascularization. HIF-1α and VEGF-A mRNA levels in bladder core biopsies from CC patients treated with radiotherapy versus untreated (non-irradiated) patients were analyzed using a droplet digital polymerase chain reaction technology. Gene expression results showed that HIF-1α and VEGF-A had no significant differences between bladder samples from patients previously irradiated and untreated patient samples. However, a direct relationship between the degree of late morbidity and the expression of HIF-1α and VEGF-A has been demonstrated. Despite the lack of statistical significance precludes a definitive conclusion, the data presented herein suggests that further studies investigating the role of HIF-1α in bladder neovascularization in radiation-induced cystitis are highly recommended.

Ameliorative effect of 2-methoxyestradiol on radiation-induced lung injury

AIMS

Radiation-induced lung injury (RILI) is a serious complication of radiation therapy. Development of an effective drug that selectively protects normal lung tissues and sensitizes tumor cells to radiotherapy is an unmet need. 2-Methoxyestradiol (2ME2) possesses polypharmacological properties, which qualifies it as an effective radioprotector. Our aim is to explore the potential protective effects of 2ME2 against early and late stages of RILI and the underlying mechanisms.

MAIN METHODS

BALB/c mice were either treated with 2ME2 (50 mg/kg/day i.p., for 4 weeks); or received a single dose of 10 Gy ionizing radiation (IR) delivered to the lungs; or 10 Gy IR and 2ME2. Animal survival and pulmonary functions were evaluated. Immune-phenotyping of alveolar macrophages (AM) in the broncho-alveolar lavage fluids (BALF) was determined by flow cytometry. ELISA was used to evaluate the expression levels of TNF-α, TGF-β; and IL-10 in BALF. Lung tissues were used for histopathological examination or immunofluorescence staining for CD68 (pan-macrophage marker), Arginase-1 (Arg1, M2-specific marker), inducible nitric oxide synthase (iNOS, M1-specific marker) and HIF-1α. VEGF and γH2AX expression in lung tissues were detected by western blot.

KEY FINDINGS

The results demonstrated that 2ME2 improved the survival, lung functions and histopathological parameters of irradiated mice. Additionally, it attenuated the radiation-induced AM polarization and reduced the pneumonitis and fibrosis markers in lung tissues. Significant reduction of TNF-α and TGF-β with concomitant increase in IL-10 concentrations were observed. Moreover, the expression of HIF-1α, VEGF and γH2AX declined.

SIGNIFICANCE

2ME2 is a promising radioprotectant with fewer anticipated side effects.

Targets for protection and mitigation of radiation injury

Protection of normal tissues against toxic effects of ionizing radiation is a critical issue in clinical and environmental radiobiology. Investigations in recent decades have suggested potential targets that are involved in the protection against radiation-induced damages to normal tissues and can be proposed for mitigation of radiation injury. Emerging evidences have been shown to be in contrast to an old dogma in radiation biology; a major amount of reactive oxygen species (ROS) production and cell toxicity occur during some hours to years after exposure to ionizing radiation. This can be attributed to upregulation of inflammatory and fibrosis mediators, epigenetic changes and disruption of the normal metabolism of oxygen. In the current review, we explain the cellular and molecular changes following exposure of normal tissues to ionizing radiation. Furthermore, we review potential targets that can be proposed for protection and mitigation of radiation toxicity.

Radiation of the urinary bladder attenuates the development of lipopolysaccharide-induced cystitis

In the present study we assessed how ionizing radiation affects TLR4-stimulated immune activation in lipopolysaccharide (LPS)-induced cystitis. LPS or saline was administered intravesically to female rats followed by urinary bladder irradiation (20 Gy) 24 h later or sham treatment. Presence in the urinary bladder of inflammatory cells (mast cells, CD3+, ionized calcium-binding adapter molecule 1 (Iba-1)+, CD68+, CD40+, CD80+, CD11c + and CD206 + cells) and expression of oxidative stress (8-OHdG), hypoxia (HIF1α) and anti-oxidative responses (NRF2, HO-1, SOD1, SOD2, catalase) were assessed 14 days later with western blot, qPCR and/or immunohistochemistry. LPS stimulation resulted in a decrease of Iba-1 + cells in the urothelium, an increase in mast cells in the submucosa and a decrease in the bladder protein expression of HO-1, while no changes in the bladder expression of 8-OHdG, NRF2, SOD1, SOD2, catalase and HIF1α were observed. Bladder irradiation inhibited the LPS-driven increase in mast cells and the decrease in Iba1 + cells. Combining LPS and radiation increased the expression of 8-OHdG and number of CD3-positive cells in the urothelium and led to a decrease in NRF2α gene expression in the urinary bladder. In conclusion, irradiation may attenuate LPS-induced immune responses in the urinary bladder but potentiates LPS-induced oxidative stress, which as a consequence may have an impact on the urinary bladder immune sensing of pathogens and danger signals.

Molecular Profiling for Predictors of Radiosensitivity in Patients with Breast or Head-and-Neck Cancer

Nearly half of all cancers are treated with radiotherapy alone or in combination with other treatments, where damage to normal tissues is a limiting factor for the treatment. Radiotherapy-induced adverse health effects, mostly of importance for cancer patients with long-term survival, may appear during or long time after finishing radiotherapy and depend on the patient’s radiosensitivity. Currently, there is no assay available that can reliably predict the individual’s response to radiotherapy. We profiled two study sets from breast (n = 29) and head-and-neck cancer patients (n = 74) that included radiosensitive patients and matched radioresistant controls.. We studied 55 single nucleotide polymorphisms (SNPs) in 33 genes by DNA genotyping and 130 circulating proteins by affinity-based plasma proteomics. In both study sets, we discovered several plasma proteins with the predictive power to find radiosensitive patients (adjusted p < 0.05) and validated the two most predictive proteins (THPO and STIM1) by sandwich immunoassays. By integrating genotypic and proteomic data into an analysis model, it was found that the proteins CHIT1, PDGFB, PNKD, RP2, SERPINC1, SLC4A, STIM1, and THPO, as well as the VEGFA gene variant rs69947, predicted radiosensitivity of our breast cancer (AUC = 0.76) and head-and-neck cancer (AUC = 0.89) patients. In conclusion, circulating proteins and a SNP variant of VEGFA suggest that processes such as vascular growth capacity, immune response, DNA repair and oxidative stress/hypoxia may be involved in an individual’s risk of experiencing radiation-induced toxicity.

Lung Stereotactic Arc Therapy in Mice: Development of Radiation Pneumopathy and Influence of HIF-1α Endothelial Deletion

PURPOSE

Stereotactic body radiation therapy offers good lung local tumor control by the administration of a high dose per fraction in small volumes. Stereotactic body radiation therapy preclinical modeling is now possible, and our aim was to develop a model of focal irradiation of the mouse lung and to investigate the impact of conditional hypoxia-inducible factor 1α (HIF-1α) deletion in the endothelium on radiation-induced tissue damage.

METHODS AND MATERIALS

The Small Animal Radiation Research Platform was used to create a mouse model of focal irradiation of the lung using arc therapy. HIF-1α conditional deletion was obtained by crossing mice expressing Cre recombinase under the endothelial promoter VE-cadherin (VECad-Cre^+/+ mice) with HIF-1α floxed mice.

RESULTS

Lung stereotactic arc therapy allows thoracic wall sparing and long-term studies. However, isodose curves showed that neighboring organs received significant doses of radiation, as revealed by ipsilateral lung acute red hepatization and major gene expression level modifications. Conditional HIF-1α deletion reduced acute lung edema and tended to diminish neutrophil infiltrate, but it had no impact on long-term global tissue damage.

CONCLUSIONS

Arc therapy for focal high-dose irradiation of mouse lung is an efficient model for long-term studies. However, irradiation may have a strong impact on the structure and function of neighboring organs, which must be considered. HIF-1α conditional deletion has no beneficial impact on lung damage in this irradiation schedule.

Mechanisms of Normal Tissue Injury From Irradiation

Normal tissue injury from irradiation is an unfortunate consequence of radiotherapy. Technologic improvements have reduced the risk of normal tissue injury; however, toxicity causing treatment breaks or long-term side effects continues to occur in a subset of patients. The molecular events that lead to normal tissue injury are complex and span a variety of biologic processes, including oxidative stress, inflammation, depletion of injured cells, senescence, and elaboration of proinflammatory and profibrogenic cytokines. This article describes selected recent advances in normal tissue radiobiology.

Nanomedicines and gene therapy for the delivery of growth factors to improve perfusion and oxygenation in wound healing

Oxygen plays a key role in wound healing, and hypoxia is a major cause of wound healing impairment; therefore, treatments to improve hemodynamics and increase wound oxygenation are of particular interest for the treatment of chronic wounds. This article describes the roles of oxygen and angiogenesis in wound healing as well as the tools used to evaluate tissue oxygenation and perfusion and then presents a review of nanomedicines and gene therapies designed to improve perfusion and oxygenation and accelerate wound healing.

Free Radical Production and Oxidative Stress in Lung Tissue of Patients Exposed to Sulfur Mustard: An Overview of Cellular and Molecular Mechanisms

Sulfur mustard (SM) is a chemical alkylating compound that primary targets lung tissue. It causes a wide variety of pathological effects in respiratory system such as chronic bronchitis, bronchiolitis obliterans, necrosis of the mucosa and inflammation, chronic obstructive pulmonary disease (COPD), and pulmonary fibrosis. However, molecular and cellular mechanisms for these pathologies are still unclear. Oxidative stress (OS) induced by reactive oxygen species (ROS) is likely a significant mechanism by which SM leads to cell death and tissues injury. SM can trigger various molecular and cellular pathways that are linked to ROS generation, OS, and inflammation. Hypoxia-induced oxidative stress, reduced activity of enzymatic antioxidants, depletion of intercellular glutathione (GSH), decreased productivity of GSH-dependent antioxidants, mitochondrial dysfunction, accumulation of leukocytes and proinflammatory cytokines, and increased expression of ROS producing-related enzymes and inflammatory mediators are the major events in which SM leads to massive production of ROS and OS in pulmonary system. Therefore, understanding of these molecules and signaling pathways gives us valuable information about toxicological effects of SM on injured tissues and the way for developing a suitable clinical treatment. In this review, we aim to discuss the possible mechanisms by which SM induces excessive production of ROS, OS, and antioxidants depletion in lung tissue of exposed patients.

Increased hemoglobin-oxygen affinity ameliorates bleomycin-induced hypoxemia and pulmonary fibrosis

Although exertional dyspnea and worsening hypoxia are hallmark clinical features of idiopathic pulmonary fibrosis (IPF), no drug currently available could treat them. GBT1118 is a novel orally bioavailable small molecule that binds to hemoglobin and produces a concentration‐dependent left shift of the oxygen–hemoglobin dissociation curve with subsequent increase in hemoglobin–oxygen affinity and arterial oxygen loading. To assess whether pharmacological modification of hemoglobin–oxygen affinity could ameliorate hypoxemia associated with lung fibrosis, we evaluated GBT1118 in a bleomycin‐induced mouse model of hypoxemia and fibrosis. After pulmonary fibrosis and hypoxemia were induced, GBT1118 was administered for eight consecutive days. Hypoxemia was determined by monitoring arterial oxygen saturation, while the severity of pulmonary fibrosis was assessed by histopathological evaluation and determination of collagen and leukocyte levels in bronchoalveolar lavage fluid. We found that hemoglobin modification by GBT1118 had strong antihypoxemic therapeutic effects with improved arterial oxygen saturation to near normal level. Moreover, GBT1118 treatment significantly attenuated bleomycin‐induced lung fibrosis, collagen accumulation, body weight loss, and leukocyte infiltration. This study is the first to suggest the beneficial effects of hemoglobin modification in fibrotic lungs and offers a promising and novel therapeutic strategy for the treatment of hypoxemia associated with chronic fibrotic lung disorders in human, including IPF.

Lipidomic dysregulation within the lung parenchyma following whole-thorax lung irradiation: Markers of injury, inflammation and fibrosis detected by MALDI-MSI

Radiation-induced lung injury (RILI) is a delayed effect of acute radiation exposure that can limit curative cancer treatment therapies and cause lethality following high-dose whole-thorax lung irradiation (WTLI). To date, the exact mechanisms of injury development following insult remain ill-defined and there are no FDA approved pharmaceutical agents or medical countermeasures. Traditionally, RILI development is considered as three phases, the clinically latent period, the intermediate acute pneumonitis phase and the later fibrotic stage. Utilizing matrix-assisted laser desorption ionization mass spectrometry imaging, we identified a number of lipids that were reflective of disease state or injury. Lipids play central roles in metabolism and cell signaling, and thus reflect the phenotype of the tissue environment, making these molecules pivotal biomarkers in many disease processes. We detected decreases in specific surfactant lipids irrespective of the different pathologies that presented within each sample at 180 days post whole-thorax lung irradiation. We also detected regional increases in ether-linked phospholipids that are the precursors of PAF, and global decreases in lipids that were reflective of severe fibrosis. Taken together our results provide panels of lipids that can differentiate between naïve and irradiated samples, as well as providing potential markers of inflammation and fibrosis.

The Lactate Dehydrogenase Inhibitor Gossypol Inhibits Radiation-Induced Pulmonary Fibrosis

Exposure of the lung to ionizing radiation that occurs in radiotherapy, as well as after accidental or intentional mass casualty incident can result in pulmonary fibrosis, which has few treatment options. Pulmonary fibrosis is characterized by an accumulation of extracellular matrix proteins that create scar tissue. Although the mechanisms leading to radiation-induced pulmonary fibrosis remain poorly understood, one frequent observation is the activation of the profibrotic cytokine transforming growth factor-beta (TGF-β). Our laboratory has shown that the metabolite lactate activates latent TGF-β by a reduction in extracellular pH. We recently demonstrated that lactate dehydrogenase-A (LDHA), the enzyme that produces lactate, is upregulated in patients with radiation-induced pulmonary fibrosis. Furthermore, genetic silencing of LDHA or pharmacologic inhibition using the LDHA inhibitor gossypol prevented radiation-induced extracellular matrix secretion in vitro through inhibition of TGF-β activation. In the current study, we hypothesized that LDHA inhibition in vivo prevents radiation-induced pulmonary fibrosis. To test this hypothesis, C57BL/6 mice received 5 Gy total-body irradiation plus 10 Gy thoracic irradiation from a ¹³⁷Cs source to induce pulmonary fibrosis. Starting at 4 weeks postirradiation, mice were treated with 5 mg/kg of the LDHA inhibitor gossypol or vehicle daily until sacrifice at 26 weeks postirradiation. Exposure to radiation resulted in pulmonary fibrosis, characterized by an increase in collagen content, fibrosis area, extracellular matrix gene expression and TGF-β activation. Irradiated mice treated with gossypol had significantly reduced fibrosis outcomes, including reduced collagen content in the lungs, reduced expression of active TGF-β, LDHA and the transcription factor hypoxia-inducible factor-1 alpha (HIF-1α). These findings suggest that inhibition of LDHA protects against radiation-induced pulmonary fibrosis, and may be a novel therapeutic strategy for radiation-induced pulmonary fibrosis.

Effects of 17β-estradiol and 2-methoxyestradiol on the oxidative stress-hypoxia inducible factor-1 pathway in hypoxic pulmonary hypertensive rats

The present study aimed to investigate the effects of 17β-estradiol (E2) and 2-methoxyestradiol (2ME) on the oxidative stress-hypoxia inducible factor-1 (OS-HIF-1) pathway in hypoxic pulmonary hypertensive rats. Female Sprague-Dawley rats were divided randomly into 4 groups, as follows: i) Control (Group A); ii) ovariectomy (OVX) + hypoxia (Group B); iii) OVX + hypoxia + E2 injection (Group C); and iv) 2ME injection (Group D). The rats were maintained under hypoxic conditions for 8 weeks, and mean pulmonary artery pressure (mPAP) and pulmonary arteriole morphology were measured. The reactive oxygen species, superoxide dismutase (SOD), manganese superoxide dismutase (MnSOD), and copper-zinc superoxide dismutase (Cu/ZnSOD) levels in serum were also measured. MnSOD and HIF-1α expression levels in lung tissue were determined by western blotting and reverse transcription-quantitative polymerase chain reaction. The mPAP and arterial remodeling index were significantly elevated following chronic hypoxia exposure; however, experimental data revealed a reduced response in E2 and 2ME intervention rats. Compared with Group A, Group B had significantly elevated oxidative stress levels, as illustrated by increased serum ROS levels, decreased serum SOD and MnSOD levels and decreased MnSOD mRNA and protein expression levels in lung tissue. Furthermore, HIF-1α mRNA and protein expression in Group B was significantly elevated compared with Group A. E2 and 2ME intervention significantly attenuated the aforementioned parameter changes, suggesting that E2 and 2ME partially ameliorate hypoxic pulmonary hypertension. The underlying mechanism of this may be associated with the increase in MnSOD activity and expression and reduction in ROS level, which reduces the levels of transcription and translation of HIF-1α.

Ockham's razor for the MET-driven invasive growth linking idiopathic pulmonary fibrosis and cancer

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) identifies a specific lung disorder characterized by chronic, progressive fibrosing interstitial pneumonia of unknown etiology, which lacks effective treatment. According to the current pathogenic perspective, the aberrant proliferative events in IPF resemble those occurring during malignant transformation.

MAIN BODY

Receptor tyrosine kinases (RTK) are known to be key players in cancer onset and progression. It has been demonstrated that RTK expression is sometimes also altered and even druggable in IPF. One example of an RTK-the MET proto-oncogene-is a key regulator of invasive growth. This physiological genetic program supports embryonic development and post-natal organ regeneration, as well as cooperating in the evolution of cancer metastasis when aberrantly activated. Growing evidence sustains that MET activation may collaborate in maintaining tissue plasticity and the regenerative potential that characterizes IPF.

CONCLUSION

The present work aims to elucidate-by applying the logic of simplicity-the bio-molecular mechanisms involved in MET activation in IPF. This clarification is crucial to accurately design MET blockade strategies within a fully personalized approach to IPF.

Late Effects of Head and Neck Radiotherapy on Pulp Vitality Assessed by Pulse Oximetry

INTRODUCTION

Radiation therapy (RT) of malignant tumors in the head and neck area may have damaging effects on surrounding tissues. The aim of this investigation was to evaluate the long-term effects of ionizing radiation on pulp vitality by measuring pulp oxygenation levels (%SpO2) in patients with history of RT of intraoral and oropharyngeal tumors 4-6 years after treatment.

METHODS

In an experimental group RT (n = 90, history of RT) and a control group CON (n = 90, no history of RT), pulp vitality was assessed by measuring %SpO2 by using pulse oximetry and pulp sensitivity by cold thermal testing. All anterior teeth without history of endodontic therapy of the participants in group RT were measured (n = 693), regardless of the quadrant and the irradiated area. An equal number of anterior teeth were tested in group CON.

RESULTS

There was no significant difference between the %SpO2 levels in group RT (92.7%; standard deviation, ± 1.83) and group CON (92.6%; standard deviation, ± 1.80). All teeth in RT and CON groups showed a positive response to the thermal test. All tested teeth were considered vital.

CONCLUSIONS

Pulp %SpO2 was found to be within normal limits 4-6 years after RT. This suggests that RT may not have a long-term influence on pulp vitality, and reported short-term changes in pulpal microcirculation because of RT may be temporary.

A MALDI-MSI Approach to the Characterization of Radiation-Induced Lung Injury and Medical Countermeasure Development

Radiation-induced lung injury is highly complex and characterized by multiple pathologies, which occur over time and sporadically throughout the lung. This complexity makes biomarker investigations and medical countermeasure screenings challenging. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) has the ability to resolve differences spatially in molecular profiles within the lung following radiation exposure and can aid in biomarker identification and pharmaceutical efficacy investigations. MALDI-MSI was applied to the investigation of a whole-thorax lung irradiation model in non-human primates (NHP) for lipidomic analysis and medical countermeasure distribution.

Dose Optimization Study of AEOL 10150 as a Mitigator of Radiation-Induced Lung Injury in CBA/J Mice

AEOL 10150 is a catalytic metalloporphyrin superoxide dismutase mimic being developed as a medical countermeasure for radiation-induced lung injury (RILI). The efficacy of AEOL 10150 against RILI through a reduction of oxidative stress, hypoxia and pro-apoptotic signals has been previously reported. The goal of this study was to determine the most effective dose of AEOL 10150 (daily subcutaneous injections, day 1-28) in improving 180-day survival in CBA/J mice after whole-thorax lung irradiation (WTLI) to a dose of 14.6 Gy. Functional and histopathological assessments were performed as secondary end points. Estimated 180-day survival improved from 10% in WTLI alone to 40% with WTLI-AEOL 10150 at 25 mg/kg (P = 0.065) and to 30% at 40 mg/kg (P = 0.023). No significant improvement was seen at doses of 5 and 10 mg/kg or at doses between 25 and 40 mg/kg. AEOL 10150 treatment at 25 mg/kg lowered the respiratory function parameter of enhanced pause (Penh) significantly, especially at week 16 and 18 (P = 0.044 and P = 0.025, respectively) compared to vehicle and other doses. Pulmonary edema/congestion were also significantly reduced at the time of necropsy among mice treated with 25 and 40 mg/kg AEOL 10150 compared to WTLI alone (P < 0.02). In conclusion, treatment with AEOL 10150 at a dose of 25 mg/kg/day for a total of 28 days starting 24 h after WTLI in CBA/J mice was found to be the optimal dose with improvement in survival and lung function. Future studies will be required to determine the optimal duration and therapeutic window for drug delivery at this dose.

Subcutaneous administration of bovine superoxide dismutase protects lungs from radiation-induced lung injury

BACKGROUND

The objective of the present study was to determine whether single administration of the antioxidant enzyme bovine superoxide dismutase (bSOD) after radiation therapy (RT) mitigates development of pulmonary toxicity in rats.

METHODS

Female F344 rats (n = 60) were divided among six experimental groups: (1) RT, single dose of 21 Gy to the right hemithorax; (2) RT + 5 mg/kg bSOD; (3) RT + 15 mg/kg bSOD; (4) No RT; (5) sham RT + 5 mg/kg bSOD; and (6) sham RT + 15 mg/kg bSOD. A single subcutaneous injection of bSOD (5 or 15 mg/kg) was administered 24 h post-radiation. The effects of bSOD on radiation-induced lung injury were assessed by measurement of body weight, breathing frequency, and histopathological changes. Immunohistochemistry was used to evaluate oxidative stress (8-OHdG(+), NOX4(+), nitrotyrosine(+), and 4HNE(+) cells), macrophage activation (ED1(+)), and expression of profibrotic transforming growth factor-β or TGF-β in irradiated tissue.

RESULTS

Radiation led to an increase in all the evaluated parameters. Treatment with 15 mg/kg bSOD significantly decreased levels of all the evaluated parameters including tissue damage and breathing frequency starting 6 weeks post-radiation. Animals treated with 5 mg/kg bSOD trended toward a suppression of radiation-induced lung damage but did not reach statistical significance.

CONCLUSIONS

The single application of bSOD (15 mg/kg) ameliorates radiation-induced lung injury through suppression of reactive oxygen species/reactive nitrogen species or ROS/RNS-dependent tissue damage.

Therapeutic effects of C-28 methyl ester of 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO-Me; bardoxolone methyl) on radiation-induced lung inflammation and fibrosis in mice

The C-28 methyl ester of 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO-Me), one of the synthetic triterpenoids, has been found to have potent anti-inflammatory and anticancer properties in vitro and in vivo. However, its usefulness in mitigating radiation-induced lung injury (RILI), including radiation-induced lung inflammation and fibrosis, has not been tested. The aim of this study was to explore the therapeutic effect of CDDO-Me on RILI in mice and the underlying mechanisms. Herein, we found that administration of CDDO-Me improved the histopathological score, reduced the number of inflammatory cells and concentrations of total protein in bronchoalveolar lavage fluid, suppressed secretion and expression of proinflammatory cytokines, including transforming growth factor-β and interleukin-6, elevated expression of the anti-inflammatory cytokine interleukin-10, and downregulated the mRNA level of profibrotic genes, including for fibronectin, α-smooth muscle actin, and collagen I. CDDO-Me attenuated radiation-induced lung inflammation. CDDO-Me also decreased the Masson's trichrome stain score, hydroxyproline content, and mRNA level of profibrotic genes, and blocked radiation-induced collagen accumulation and fibrosis. Collectively, these findings suggest that CDDO-Me ameliorates radiation-induced lung inflammation and fibrosis, and this synthetic triterpenoid is a promising novel therapeutic agent for RILI. Further mechanistic, efficacy, and safety studies are warranted to elucidate the role of CDDO-Me in the management of RILI.

miR-210 promotes IPF fibroblast proliferation in response to hypoxia

Idiopathic pulmonary fibrosis (IPF) is characterized by the relentless spread of fibroblasts from scarred alveoli into adjacent alveolar units, resulting in progressive hypoxia and death by asphyxiation. Although hypoxia is a prominent clinical feature of IPF, the role of hypoxia as a driver of the progressive fibrotic nature of the disease has not been explored. Here, we demonstrate that hypoxia robustly stimulates the proliferation of IPF fibroblasts. We found that miR-210 expression markedly increases in IPF fibroblasts in response to hypoxia and that knockdown of miR-210 decreases hypoxia-induced IPF fibroblast proliferation. Silencing hypoxia-inducible factor (HIF)-2α inhibits the hypoxia-mediated increase in miR-210 expression and blocks IPF fibroblast proliferation, indicating that HIF-2α is upstream of miR-210. We demonstrate that the miR-210 downstream target MNT is repressed in hypoxic IPF fibroblasts and that knockdown of miR-210 increases MNT expression. Overexpression of MNT inhibits hypoxia-induced IPF fibroblast proliferation. Together, these data indicate that hypoxia potently stimulates miR-210 expression via HIF-2α, and high miR-210 expression drives fibroblast proliferation by repressing the c-myc inhibitor, MNT. In situ analysis of IPF lung tissue demonstrates miR-210 expression in a similar distribution with HIF-2α and the hypoxic marker carbonic anhydrase-IX in cells within the IPF fibrotic reticulum. Our results raise the possibility that a pathological feed-forward loop exists in the IPF lung, in which hypoxia promotes IPF fibroblast proliferation via stimulation of miR-210 expression, which in turn worsens hypoxia.

The effect of radiation on acellular dermal matrix and capsule formation in breast reconstruction: clinical outcomes and histologic analysis

BACKGROUND

The authors compared clinical outcomes to determine whether acellular dermal matrix altered the capsular tissue architecture in irradiated and nonirradiated breasts following matrix-assisted expander reconstruction.

METHODS

Part I included all 27 patients who underwent bilateral tissue expander reconstruction with acellular dermal matrix between 2007 and 2012 and subsequent unilateral radiation therapy. Part II included a subset of patients with capsular biopsy specimens taken at the time of implant exchange for histologic analysis. Specimens included irradiated and nonirradiated acellular dermal matrix and irradiated and nonirradiated native capsule. Clinical outcomes were analyzed in relation to capsule architecture and acellular dermal matrix performance.

RESULTS

In part I, mean follow-up was 28 months. Grade III/IV contractures were identified in nine patients (all on the irradiated side), and 12 developed noncontracture complications (75 percent on the irradiated side). Nine patients were unable to continue with implant reconstruction and required salvage with autologous tissue. In part II, postirradiation biopsy specimens were taken of the peri-implant capsule in six patients at the time of secondary surgery. Elastin content and the total cellular infiltrate were significantly greater in the irradiated versus nonirradiated native capsules (p = 0.0015). Conversely, the irradiated matrix capsule was composed of similar amounts of cellular infiltrate and collagen as the nonirradiated matrix capsules and nonirradiated native capsules. Irradiated acellular dermal matrix showed the least amount of alpha-smooth actin staining but a similar number of blood vessels.

CONCLUSION

Acellular dermal matrix appears to limit the elastosis and chronic inflammation seen in irradiated implant reconstructions and is potentially beneficial in these patients.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

An Experimental Study of Radiation Effect on Normal Tissue: Analysis of HIF-1α, VEGF, eIF2, TIA-1, and TSP-1 Expression

Objective:

This study investigated whether or not the stress and hypoxia, which are the effects of radiation on normal vascular endothelium, leading to the release of HIF-1α, VEGF, eIF2, TIA-1, and TSP-1 were related and the possibility of them stimulating angiogenesis.


Materials and Methods:

Twenty-four male Swiss Albino mice were separated into 4 groups. The first group was the control group (Group 1), and the second, third, and fourth groups were euthanized after 24 h (Group 2), 48 h (Group 3), and 7 days (Group 4), respectively. A single-fractioned 10 Gy of ionizing radiation was applied to all mice’s pelvic zone with Co-60. Bladders were removed completely from the pelvic region. Immunohistochemistry and light microscopy were used to investigate whether there would be an increase or not in the angiogenesis pathway by using the HIF-1α, VEGF, eIF2, TIA-1, and TSP-1 antibodies.

Results:

The HIF-1α antibody showed strong staining in Group 3, while the staining intensity was less in other groups. VEGF showed weak staining in Groups 1 and 4, while moderate staining in Group 2 and strong staining in Group 3 was observed. eIF2 showed strong staining in Groups 1 and 4. Groups 2 and 3 were stained weakly. In the present study, staining with TSP-1 was very strong in the samples belonging to Group 1, while other groups showed very weak staining.

Conclusion:

When normal tissue was exposed to radiation, the positively effective factors (HIF-1, VEGF, eIF2, and TIA-1) on the angiogenesis pathway were increased while the negative factor (TSP-1) was decreased. Radiation may initiate physiological angiogenesis in the normal tissue and accelerate healing in the damaged normal tissue.

Molecular mechanisms and treatment of radiation-induced lung fibrosis

Radiation-induced lung fibrosis (RILF) is a severe side effect of radiotherapy in lung cancer patients that presents as a progressive pulmonary injury combined with chronic inflammation and exaggerated organ repair. RILF is a major barrier to improving the cure rate and well-being of lung cancer patients because it limits the radiation dose that is required to effectively kill tumor cells and diminishes normal lung function. Although the exact mechanism is unclear, accumulating evidence suggests that various cells, cytokines and regulatory molecules are involved in the tissue reorganization and immune response modulation that occur in RILF. In this review, we will summarize the general symptoms, diagnostics, and current understanding of the cells and molecular factors that are linked to the signaling networks implicated in RILF. Potential approaches for the treatment of RILF will also be discussed. Elucidating the key molecular mediators that initiate and control the extent of RILF in response to therapeutic radiation may reveal additional targets for RILF treatment to significantly improve the efficacy of radiotherapy for lung cancer patients.

Whole brain radiation-induced vascular cognitive impairment: mechanisms and implications

Mild cognitive impairment is a well-documented consequence of whole brain radiation therapy (WBRT) that affects 40-50% of long-term brain tumor survivors. The exact mechanisms for the decline in cognitive function after WBRT remain elusive and no treatment or preventative measures are available for use in the clinic. Here, we review recent findings indicating how changes in the neurovascular unit may contribute to the impairments in learning and memory. In addition to affecting neuronal development, WBRT induces profound capillary rarefaction within the hippocampus - a region of the brain important for learning and memory. Therapeutic strategies such as hypoxia, which restore the capillary density, result in the rescue of cognitive function. In addition to decreasing vascular density, WBRT impairs vasculogenesis and/or angiogenesis, which may also contribute to radiation-induced cognitive decline. Further studies aimed at uncovering the specific mechanisms underlying these WBRT-induced changes in the cerebrovasculature are essential for developing therapies to mitigate the deleterious effects of WBRT on cognitive function.

Cellular and molecular mechanisms in the hypoxic tissue: role of HIF-1 and ROS

Reactive oxygen species such as superoxide anion radicals (O2 (-) ) and hydrogen peroxide (H2 O2 ) have for long time been recognized as undesirable by-products of the oxidative mitochondrial generation of adenosine triphosphate (ATP). Recently, these highly reactive species have been associated to important signaling pathways in diverse physiological conditions such as those activated in hypoxic microenvironments. The molecular response to hypoxia requires fast-acting mechanisms acting within a wide range of partial pressures of oxygen (O2 ). Intracellular O2 sensing is an evolutionary preserved feature, and the best characterized molecular responses to hypoxia are mediated through transcriptional activation. The transcription factor, hypoxia-inducible factor 1 (HIF-1), is a critical mediator of these adaptive responses, and its activation by hypoxia involves O2 -dependent posttranslational modifications and nuclear translocation. Through the induction of the expression of its target genes, HIF-1 coordinately regulates tissue O2 supply and energetic metabolism. Other transcription factors such as nuclear factor κB are also redox sensitive and are activated in pro-oxidant and hypoxic conditions. The purpose of this review is to summarize new developments in HIF-mediated O2 sensing mechanisms and their interactions with reactive oxygen species-generating pathways in normal and abnormal physiology.

Temporal expression of hypoxia-regulated genes is associated with early changes in redox status in irradiated lung

The development of normal lung tissue toxicity after radiation exposure results from multiple changes in cell signaling and communication initiated at the time of the ionizing event. The onset of gross pulmonary injury is preceded by tissue hypoxia and chronic oxidative stress. We have previously shown that development of debilitating lung injury can be mitigated or prevented by administration of AEOL10150, a potent catalytic antioxidant, 24h after radiation. This suggests that hypoxia-mediated signaling pathways may play a role in late radiation injury, but the exact mechanism remains unclear. The purpose of this study was to evaluate changes in the temporal expression of hypoxia-associated genes in irradiated mouse lung and determine whether AEOL10150 alters expression of these genes. A focused oligo array was used to establish a hypoxia-associated gene expression signature for lung tissue from sham-irradiated or irradiated mice treated with or without AEOL10150. Results were further verified by RT-PCR. Forty-four genes associated with metabolism, cell growth, apoptosis, inflammation, oxidative stress, and extracellular matrix synthesis were upregulated after radiation. Elevated expression of 31 of these genes was attenuated in animals treated with AEOL10150, suggesting that expression of a number of hypoxia-associated genes is regulated by early development of oxidative stress after radiation. Genes identified herein could provide insight into the role of hypoxic signaling in radiation lung injury, suggesting novel therapeutic targets, as well as clues to the mechanism by which AEOL10150 confers pulmonary radioprotection.

Gene expression analysis in chronic postradiation proctopathy

PURPOSE

Radiotherapy is one of the important treatment modalities for tumors of pelvic organs. The fixed location of the rectum and its anatomic relationship with other pelvic organs makes it prone to radiation injury resulting in chronic radiation proctopathy in 5% to 20% of patients. Endothelial dysfunction has been associated with a number of pathophysiological processes. Endothelial cells synthesize and release various factors that regulate angiogenesis, inflammatory responses, hemostasis, as well as vascular tone and permeability.

METHODS

Rectum tissue samples from 20 patients with established chronic radiation proctopathy were analysed for the expression of genes related to oxidative stress, tissue hypoxia, angiogenesis, and inflammation [endoglin (ENG), activin receptor-like kinase 1 (ALK1), platelet endothelial cell adhesion molecule 1 (PECAM), vascular endothelial growth factor (VEGF), fibroblast growth factor 2 (FGF2), hypoxia-inducible factor 1 (HIF-1), and interleukin-1 beta (IL-1β)].

RESULTS

Overexpression of HIF-1, VEGF, FGF2, and IL-1β was detected in affected tissue. For the first time, a significant suppression of activin receptor-like kinase 1 and ENG could be revealed.

CONCLUSION

The data provided here allow further insight into the pathogenesis of radiation-induced rectum injury. Radiation-induced damage is not confined to a single event but involves complex signaling between different pathways, enhancing and maintaining the processes that lead to mucosal damage. The results indicate that postradiation tissue hypoxia is critical for fibrosis, which involves changes in the expression of profibrotic and angiogenic factors in rectal tissue.