IL-1 generated subsequent to radiation-induced tissue injury contributes to the pathogenesis of radiodermatitis

Impacts of Radiation on Metabolism and Vascular Cell Senescence

Significance: This review investigates how radiation therapy (RT) increases the risk of delayed cardiovascular disease (CVD) in cancer survivors. Understanding the mechanisms underlying radiation-induced CVD is essential for developing targeted therapies to mitigate these effects and improve long-term outcomes for patients with cancer. Recent Advances: Recent studies have primarily focused on metabolic alterations induced by irradiation in various cancer cell types. However, there remains a significant knowledge gap regarding the role of chronic metabolic alterations in normal cells, particularly vascular cells, in the progression of CVD after RT. Critical Issues: This review centers on RT-induced metabolic alterations in vascular cells and their contribution to senescence accumulation and chronic inflammation across the vasculature post-RT. We discuss key metabolic pathways, including glycolysis, the tricarboxylic acid cycle, lipid metabolism, glutamine metabolism, and redox metabolism (nicotinamide adenine dinucleotide/Nicotinamide adenine dinucleotide (NADH) and nicotinamide adenine dinucleotide phosphate (NADP+)/NADPH). We further explore the roles of regulatory proteins such as p53, adenosine monophosphate-activated protein kinase, and mammalian target of rapamycin in driving these metabolic dysregulations. The review emphasizes the impact of immune-vascular crosstalk mediated by the senescence-associated secretory phenotype, which perpetuates metabolic dysfunction, enhances chronic inflammation, drives senescence accumulation, and causes vascular damage, ultimately contributing to cardiovascular pathogenesis. Future Directions: Future research should prioritize identifying therapeutic targets within these metabolic pathways or the immune-vascular interactions influenced by RT. Correcting metabolic dysfunction and reducing chronic inflammation through targeted therapies could significantly improve cardiovascular outcomes in cancer survivors. Antioxid. Redox Signal. 00, 000-000.

Skin Microbiome, Inflammation, and Skin Toxicities in Women With Breast Cancer Receiving Moderately Hypofractionated Radiation Therapy

PURPOSE

Up to 95% of women during and after radiation therapy (RT) for breast cancer have reported cutaneous toxicity. However, the biologic link between skin microbiome and skin toxicities from RT remains largely unknown. This study aimed to assess the associations of skin microbiome with clinician- and patient-reported skin toxicities and inflammatory markers in women with breast cancer receiving RT.

METHODS AND MATERIALS

A prospective, longitudinal study was conducted at a single institution. Thirty-two women with breast cancer undergoing moderately hypofractionated RT for 3 to 4 weeks after breast conserving surgery were enrolled and 30 of them were analyzed. A total of 240 swabs for skin microbiome and 120 plasma samples were collected pre-RT baseline (T1), week-1 of RT (T2), week-3 of RT (T3), and 3 months post-RT (T4), from the cancer-affected and contralateral healthy breasts. Skin microbiome specimens were processed using 16S V1-V3 sequencing.

RESULTS

Differences in skin microbiome of the treated breasts during RT (T2 and T3) were observed compared with the skin microbiome of pre-RT baseline breasts (T1) and contralateral, healthy breasts, with the affected breasts having an increased abundance of pathogenetic Finegoldia (P = .001), Dermacoccus (P = .01), and Variovorax (P = .003) during RT. Longitudinal analysis showed that decreased Variovorax but increased Staphylococcus were associated with increased clinician-reported grade 2 pruritus (P = .002) and dermatitis (P = .012), and increased patient-reported moderate or severe darkened skin (P = .002) and itchy skin (P = .012). Additionally, the plasma interferon gamma was associated with changes in skin microbiome in women with breast cancer undergoing RT.

CONCLUSIONS

This study shows changes in the skin microbiome during well-tolerated moderately hypofractionated breast RT. The skin microbiome return toward baseline appears to associate with improvement of clinician- and patient-reported skin toxicities post-treatment. Although there were few high-grade toxicities observed among frequently prescribed courses of hypofractionated whole breast RT, changes in skin microbiome may be of interest as further targets of symptomatic relief or intervention as ultrahypofractionated courses become more common.

Development of Machine Learning Models for Predicting Radiation Dermatitis in Breast Cancer Patients Using Clinical Risk Factors, Patient-Reported Outcomes, and Serum Cytokine Biomarkers

BACKGROUND

Radiation dermatitis (RD) is a significant side effect of radiotherapy experienced by breast cancer patients. Severe symptoms include desquamation or ulceration of irradiated skin, which impacts quality of life and increases healthcare costs. Early identification of patients at risk for severe RD can facilitate preventive management and reduce severe symptoms. This study evaluated the utility of subjective and objective factors, such as patient-reported outcomes (PROs) and serum cytokines, for predicting RD in breast cancer patients. The performance of machine learning (ML) and logistic regression-based models were compared.

PATIENTS AND METHODS

Data from 147 breast cancer patients who underwent radiotherapy was analyzed to develop prognostic models. ML algorithms, including neural networks, random forest, XGBoost, and logistic regression, were employed to predict clinically significant Grade 2+ RD. Clinical factors, PROs, and cytokine biomarkers were incorporated into the risk models. Model performance was evaluated using nested cross-validation with separate loops for hyperparameter tuning and calculating performance metrics.

RESULTS

Feature selection identified 18 predictors of Grade 2+ RD including smoking, radiotherapy boost, reduced motivation, and the cytokines interleukin-4, interleukin-17, interleukin-1RA, interferon-gamma, and stromal cell-derived factor-1a. Incorporating these predictors, the XGBoost model achieved the highest performance with an area under the curve (AUC) of 0.780 (95% CI: 0.701-0.854). This was not significantly improved over the logistic regression model, which demonstrated an AUC of 0.714 (95% CI: 0.629-0.798).

CONCLUSION

Clinical risk factors, PROs, and serum cytokine levels provide complementary prognostic information for predicting severe RD in breast cancer patients undergoing radiotherapy. ML and logistic regression models demonstrated comparable performance for predicting clinically significant RD with AUC>0.70.

Effect of ASC Injection in the Inflammatory Reaction in Silicone Implant Capsule: Animal Model

Background

Capsular contracture is a common complication affecting about 80% of patients who receive radiotherapy after breast reconstruction with silicone prostheses. This study examines the use of adipocyte stem cells (ASCs) to treat capsular contracture.

Methods

Thirty rats were operated on to implant a minisilicone prosthesis in the dorsal region. The rats were divided into three groups: control (saline solution injection), radiotherapy (RDT), and RDT + ASC. After 3 months, the capsules were collected and submitted to histological analysis for inflammatory cell presence, vascular density, and collagen fibers, and gene expression of Tnf, Il1rap, Il10, Cd68, Mmp3, and Mmp9 by qPCR.

Results

In macroscopic analysis, the RTGO score showed a two-point reduction in RDT + ASC compared with the RDT (P = 0.003). In histological analysis, ASC exhibited less than 50% of inflammatory cells compared with RDT (P = 0.004), which was similar to control. This study demonstrated that Il1rap gene expression was identical in both RDT and RTD + ASC. Compared with control, treatment with ASC reduced Il1rap expression by 30%. Cd68 and Mmp3 expression levels were similar in both the control and RTD + ASC.

Conclusion

This study suggests that ASC treatment decreases silicone prosthesis capsule inflammation.

Ergothioneine-Sodium Hyaluronate Dressing: A Promising Approach for Protecting against Radiation-Induced Skin Injury

Radiotherapy commonly causes damage to healthy tissues, particularly radiation-induced skin injury (RISI) that affects a significant majority of patients undergoing radiotherapy. Effective treatments for RISI are lacking. This study focuses on the pathogenesis of RISI, which primarily involves oxidative stress. Excessive reactive oxygen species (ROS) generation during radiation induces damage to biological macromolecules, triggering oxidative stress and inflammation. To address this, ergothioneine (EGT), a natural and biocompatibile thiol compound with excellent antioxidant activity, is explored as a potential radiation-protective agent. By utilizing its specific transport and absorption in the skin tissue, as well as its efficient and stable clearance of radiation-induced "ROS storm", EGT is combined with sodium hyaluronate (NaHA) to develop a novel radiation protective dressing suitable for the skin. This EGT-NaHA dressing demonstrates an effective ability to scavenge free radicals and reduce oxidative stress in vitro and in vivo, reducing cellular apoptosis and inflammation. These results demonstrate the protective properties of EGT against RISI, with far-reaching implications for research and development in the field of radioprotection.

Radiation injury and gut microbiota-based treatment

The exposure to either medical sources or accidental radiation can cause varying degrees of radiation injury (RI). RI is a common disease involving multiple human body parts and organs, yet effective treatments are currently limited. Accumulating evidence suggests gut microbiota are closely associated with the development and prevention of various RI. This article summarizes 10 common types of RI and their possible mechanisms. It also highlights the changes and potential microbiota-based treatments for RI, including probiotics, metabolites, and microbiota transplantation. Additionally, a 5P-Framework is proposed to provide a comprehensive strategy for managing RI.

An Experimental Model of Proton-Beam-Induced Radiation Dermatitis In Vivo

Radiation dermatitis (RD) is one of the most common side effects of radiation therapy. However, to date, there is a lack of both specific treatments for RD and validated experimental animal models with the use of various sources of ionizing radiation (IR) applied in clinical practice. The aim of this study was to develop and validate a model of acute RD induced using proton radiation in mice. Acute RD (Grade 2-4) was obtained with doses of 30, 40, and 50 Gy, either with or without depilation. The developed model of RD was characterized by typical histological changes in the skin after irradiation. Moreover, the depilation contributed to a skin histology alteration of the irradiated mice. The assessment of animal vital signs indicated that there was no effect of proton irradiation on the well-being or general condition of the animals. This model can be used to develop effective therapeutic agents and study the pathogenesis of radiation-induced skin toxicity, including that caused by proton irradiation.

Autologous i-PRF promotes healing of radiation-induced skin injury

Skin, as an exposed tissue, often suffers damage after exposure to radiotherapy and accidental events, which may lead to the formation of chronic refractory wounds. However, effective treatment options are usually limited for severe radiation-induced skin injury (RSI). Platelet-rich plasma (PRP) has been identified to promote wound healing, but whether a new generation of blood-derived biomaterial, injectable platelet-rich fibrin (i-PRF), is effective in repairing RSI remains unclear. In this study, blood was drawn from humans and Sprague-Dawley rats to prepare PRP and i-PRF, and the regenerative functions of PRP and i-PRF were investigated by exposing the dorsal skin of SD rats to local radiation (45 Gy) and exposing HDF-α cells and human umbilical vein endothelial cells (HUVECs) cells to X-rays (10 Gy). The healing effect of i-PRF on RSI was analysed by tube formation assay, cell migration and apoptosis assays, ROS assay, wound healing assay, histological characterisation and immunostaining. The results showed that exposure to high doses of radiation reduced cell viability, increased ROS levels and induced cell apoptosis, thereby causing dorsal trauma of rats. However, both PRP and i-PRF could resisted RSI, and they were capable of reducing inflammation and promoting angiogenesis and vascular regeneration. i-PRF has a higher concentration of platelets and platelet-derived growth factors, which has a more convenient preparation method and better repair effect and possesses a good application prospect for the repair of RSI.

Prediction of radiation-induced acute skin toxicity in breast cancer patients using data encapsulation screening and dose-gradient-based multi-region radiomics technique: A multicenter study

Purpose

Radiation-induced dermatitis is one of the most common side effects for breast cancer patients treated with radiation therapy (RT). Acute complications can have a considerable impact on tumor control and quality of life for breast cancer patients. In this study, we aimed to develop a novel quantitative high-accuracy machine learning tool for prediction of radiation-induced dermatitis (grade ≥ 2) (RD 2+) before RT by using data encapsulation screening and multi-region dose-gradient-based radiomics techniques, based on the pre-treatment planning computed tomography (CT) images, clinical and dosimetric information of breast cancer patients.

Methods and Materials

214 patients with breast cancer who underwent RT between 2018 and 2021 were retrospectively collected from 3 cancer centers in China. The CT images, as well as the clinical and dosimetric information of patients were retrieved from the medical records. 3 PTV dose related ROIs, including irradiation volume covered by 100%, 105%, and 108% of prescribed dose, combined with 3 skin dose-related ROIs, including irradiation volume covered by 20-Gy, 30-Gy, 40-Gy isodose lines within skin, were contoured for radiomics feature extraction. A total of 4280 radiomics features were extracted from all 6 ROIs. Meanwhile, 29 clinical and dosimetric characteristics were included in the data analysis. A data encapsulation screening algorithm was applied for data cleaning. Multiple-variable logistic regression and 5-fold-cross-validation gradient boosting decision tree (GBDT) were employed for modeling training and validation, which was evaluated by using receiver operating characteristic analysis.

Results

The best predictors for symptomatic RD 2+ were the combination of 20 radiomics features, 8 clinical and dosimetric variables, achieving an area under the curve (AUC) of 0.998 [95% CI: 0.996-1.0] and an AUC of 0.911 [95% CI: 0.838-0.983] in the training and validation dataset, respectively, in the 5-fold-cross-validation GBDT model. Meanwhile, the top 12 most important characteristics as well as their corresponding importance measures for RD 2+ prediction in the GBDT machine learning process were identified and calculated.

Conclusions

A novel multi-region dose-gradient-based GBDT machine learning framework with a random forest based data encapsulation screening method integrated can achieve a high-accuracy prediction of acute RD 2+ in breast cancer patients.

Effect of standard skin care treatments on skin barrier function in X-irradiated hairless mice

Objective

The effectiveness of skin care to radiation dermatitis (RD) on patients who received radiotherapy for cancer has not been clarified. The purpose of this study was to investigate the effect of moisturizers and skin washing on skin barrier function possibly leading to the development of RD using X-ray irradiated hairless mice.

Methods

Nine-week-old hairless mice were irradiated with 10 ​Gy of X-rays, and the skin care group had moisturizers applied or skin washing with soap from the day of irradiation during observations. The condition of the skin was observed to evaluate RD. Skin barrier function was evaluated by measuring skin temperature and transepidermal water loss (TEWL) once every two days until 25 days after X-ray irradiation.

Results

RD was not observed in all groups until 25 days after X-ray irradiation. Skin temperature tended to increase in all groups regardless of irradiation or skin care. However, unlike the control group, the measured value of TEWL in the no skin care group tended to increase in the days after the X-ray irradiation. On the other hand, TEWL was increased in the skin care group compared with the no skin care group a few days after X-ray irradiation. While TEWL was constant in the moisturizer group, the skin washing groups showed an increasing tendency of TEWL and it reached a peak at 13 days after X-ray irradiation.

Conclusions

These results suggested that the decrease in skin barrier function was caused by X-ray irradiation and also that skin washing could contribute to the deterioration of skin barrier function after X-ray irradiation.

Skin Microbiome and Treatment-Related Skin Toxicities in Patients With Cancer: A Mini-Review

The human skin hosts millions of bacteria, fungi, archaea, and viruses. These skin microbes play a crucial role in human immunological and physiological functions, as well as the development of skin diseases, including cancer when the balance between skin commensals and pathogens is interrupted. Due to the linkages between inflammation processes and skin microbes, and viral links to skin cancer, new theories have supported the role a dysbiotic skin microbiome plays in the development of cancer and cancer treatment-related skin toxicities. This review focuses on the skin microbiome and its role in cancer treatment-related skin toxicities, particularly from chemotherapy, radiation therapy, and immunotherapy. The current literature found changes in the diversity and abundance of the skin microbiome during cancer treatments such as radiation therapy, including lower diversity of the skin microbiome, an increased Proteobacteria/Firmicutes ratio, and a higher abundance of pathogenic Staphylococcus aureus. These changes may be associated with the development and severity of treatment-related skin toxicities, such as acute radiation dermatitis, hand-foot syndrome in chemotherapy, and immunotherapy-induced rash. Several clinical guidelines have issued potential interventions (e.g., use of topical corticosteroids, phototherapy, and non-pharmaceutical skin care products) to prevent and treat skin toxicities. The effectiveness of these promising interventions in alleviating treatment-related skin toxicities should be further tested among cancer patients.

Traditionally Used Natural Products in Preventing Ionizing Radiation-Induced Dermatitis: First Review on the Clinical Studies

In the treatment of cancer, the use of ionizing radiation is an important modality. However, on the downside, radiation, when used for curative purposes, causes acute dermatitis or radiodermatitis at the site of radiation in most individuals. From a clinical viewpoint, severe dermatitis causes a burning and itching sensation is very painful, and severely affects the quality of life of the individual undergoing treatment. In worse situations, acute radiation dermatitis can cause gaps or breaks in the planned treatment and this can adversely affect the treatment objective and outcome.

BACKGROUND

In various traditional and folk systems of medicine, plants and plant products have been used since time immemorial for treating various skin ailments. Further, many cosmeceutical creams formulated based on knowledge from ethnomedicinal use are marketed and used to treat various ailments. In the current review, an attempt is made at summarizing the beneficial effects of some plants and plant products in mitigating acute radiation dermatitis in humans undergoing curative radiotherapy. Additionally, the emphasis is also placed on the mechanism/s responsible for the beneficial effects.

OBJECTIVE

The objective of this review is to summarize the clinical observations on the prevention of radiodermatitis by plant products. In this review, the protective effects of Adlay (Coix lachryma-jobi L.) bran extract, Aloe vera, Calendula officinalis, Cucumis sativus, green tea constituent the epigallocatechin-3-gallate, honey, Achillea millefolium, Matricaria chamomilla, olive oil and some polyherbal creams are addressed by also addressing on the mechanism of action for the beneficial effects.

METHODS

Two authors' data mined for information in Google Scholar, PubMed, Embase and the Cochrane Library for publications in the field from 1901 up to July 2020. The focus was on acute radiation dermatitis, ionizing radiation, curative radiotherapy, human cancer. The articles were collected and analyzed.

RESULTS

For the first time, this review addresses the usefulness of natural products like adlay bran, Aloe vera, Calendula officinalis, Cucumis sativus, green tea constituent the epigallocatechin-3-gallate, honey, Achillea millefolium, Matricaria chamomilla, olive oil and some experimentally constituted and commercially available polyherbal creams as skincare agents against the deleterious effects of ionizing radiation on the skin. The protective effects are possibly due to the free radical scavenging, antioxidant, anti-inflammatory, wound healing and skin protective effects.

CONCLUSION

The authors suggest that these plants have been used since antiquity as medicinal agents and require in-depth investigation with both clinical and preclinical validated models of study. The results of these studies will be extremely useful to cancer patients requiring curative radiotherapy, the dermatology fraternity, agro-based and pharmaceutical sectors at large.

The Role of Reactive Oxygen Species and Nitric Oxide in the Inhibition of Trichophyton rubrum Growth by HaCaT Cells

Trichophyton rubrum (T. rubrum) is one of the most important agents of dermatophyte infection in humans. The aim of this experiment was to evaluate the effect of HaCaT cells on T. rubrum, investigate the responsible mechanism of action, and explore the role of reactive oxygen species (ROS) and nitric oxide (NO) in the inhibition of T. rubrum growth by HaCaT cells. The viability of fungi treated with HaCaT cells alone and with HaCaT cells combined with pretreatment with the NADPH oxidase inhibitor (DPI) or the nitric oxide synthase (NOS) inhibitor L-NMMA was determined by enumerating the colony-forming units. NOS, ROS, and NO levels were quantified using fluorescent probes. The levels of the NOS inhibitor asymmetric dimethylarginine (ADMA) were determined by enzyme-linked immunosorbent assay (ELISA). Micromorphology was observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, fungal keratinase activity was assessed by measuring dye release from keratin azure. In vitro fungal viability, keratinase activity, and ADMA content decreased after HaCaT cell intervention, whereas the levels of ROS, NO, and NOS increased. The micromorphology was abnormal. Fungi pretreated with DPI and L-NMMA exhibited opposite effects. HaCaT cells inhibited the growth and pathogenicity of T. rubrum in vitro. A suggested mechanism is that ROS and NO play an important role in the inhibition of T. rubrum growth by HaCaT cells.

Sub-acute Toxicity in Non-cancerous Tissue and Immune-Related Adverse Events of a Novel Combination Therapy for Cancer

Brain, lung, and colon tissue experience deleterious immune-related adverse events when immune-oncological agents or radiation are administered. However, there is a paucity of information regarding whether the addition of radiation to immuno-oncological regimens exacerbates the tissue inflammatory response. We used a murine model to evaluate sub-acute tissue damage and the systemic immune response in C57Bl/6 mice when administered systemic anti-programmed cell death protein 1 (αPD-1) immunotherapy alone or in combination with stereotactic fractionated 10 gray/5 X-ray radiation to normal brain, lung or colon tissue. The model indicated that combinatorial αPD-1 immunotherapy and radiation may alter normal colon cell proliferation and cerebral blood vasculature, and induce systemic thrombocytopenia, lymphopenia, immune suppression, and altered immune repertoire (including interleukin-1β). Therein our data supports close monitoring of hematological and immune-related adverse events in patients receiving combination therapy.

The circadian clock protects against ionizing radiation-induced cardiotoxicity

Radiation therapy (RT) is commonly used to treat solid tumors of the breast, lung, and esophagus; however, the heart is an unintentional target of ionizing radiation (IR). IR exposure to the heart results in chronic toxicities including heart failure. We hypothesize that the circadian system plays regulatory roles in minimizing the IR-induced cardiotoxicity. We treated mice in control (Day Shift), environmentally disrupted (Rotating Shift), and genetically disrupted (Per 1/2 mutant) circadian conditions with 18 Gy of IR to the heart. Compared to control mice, circadian clock disruption significantly exacerbated post-IR systolic dysfunction (by ultrasound echocardiography) and increased fibrosis in mice. At the cellular level, Bmal1 protein bound to Atm, Brca1, and Brca2 promoter regions and its expression level was inversely correlated with the DNA damage levels based on the state of the clock. Further studies with circadian synchronized cardiomyocytes revealed that Bmal1 depletion increased the IR-induced DNA damage and apoptosis. Collectively, these findings suggest that the circadian clock protects from IR-induced toxicity and potentially impacts RT treatment outcome in cancer patients through IR-induced DNA damage responses.

Wound healing complications in oncological patients: perspectives for cellular therapy

Various types of cancer are nowadays a serious medical and social problem and a great challenge for modern medicine. The majority of anticancer therapy is based on traditional chemotherapy and radiotherapy. Both of these highly non-specific types of treatment have a number of serious side effects including wound healing complications. Radiotherapy and chemotherapy mostly affect rapidly dividing skin cells (e.g. keratinocytes), as well as fibroblasts, melanocytes, endothelial and immune cells. Currently, there are many strategies to improve wound healing in oncological patients, including various types of dressings, biomaterials, growth factors, and cell therapies.

The ion channel, TRPM2, contributes to the pathogenesis of radiodermatitis

Radiodermatitis is a painful side effect for cancer patients undergoing radiotherapy. Irradiation of the skin causes inflammation and breakdown of the epidermis and can lead to significant morbidity and mortality in severe cases, as seen in exposure from accidents or weapons such as "dirty bombs" and ultimately leads to tissue fibrosis. However, the pathogenesis of radiodermatitis is not fully understood. Using a mouse model of radiodermatitis, we showed that the Transient Receptor Potential Melastatin 2 (TRPM2) ion channel plays a significant role in the development of dermatitis following exposure to ionizing radiation. Irradiated TRPM2-deficient mice developed less inflammation, fewer severe skin lesions and decreased fibrosis when compared to wild type mice. The TRPM2-deficient mice also showed a faster recovery period as seen by their increased weight gain post irradiation. Finally, TRPM2-deficient mice exhibited lower systemic inflammation with a reduction in inflammatory cytokines present in the serum. These findings suggest that TRPM2 may be a potential therapeutic target for reducing the severity of radiodermatitis.

Targeting Innate Immunity to Enhance the Efficacy of Radiation Therapy

Radiation continues to play a major role in the treatment of almost every cancer type. Traditional radiation studies focused on its ability to damage DNA, but recent evidence has demonstrated that a key mechanism driving the efficacy of radiation in vivo is the immune response triggered in irradiated tissue. Innate immune cells including macrophages, dendritic cells, and natural killer cells are key mediators of the radiation-induced immune response. They regulate the sensing of radiation-mediated damage and subsequent radiation-induced inflammation. Given the importance of innate immune cells as determinants of the post-radiation anti-tumor immune response, much research has been devoted to identify ways to both enhance the innate immune response and prevent their ability to suppress ongoing immune responses. In this review, we will discuss how the innate immune system shapes anti-tumor immunity following radiation and highlight key strategies directed at the innate immune response to enhance the efficacy of radiation.

Radiation-induced skin reactions: mechanism and treatment

Radiotherapy (RT) is a major treatment for malignant tumors. The latest data show that >70% of patients with malignant tumors need RT at different periods. Skin changes can be experienced by up to 95% of patients who underwent RT. Inflammation and oxidative stress (OS) have been shown to be generally associated with radiation-induced skin reactions (RISRs). Inflammatory response and OS interact and promote each other during RISRs. Severe skin reactions often have a great impact on the progress of RT. The treatment of RISRs is particularly critical because advanced RT technology can also lead to skin reactions. RISRs are classified into acute and chronic reactions. The treatment methods for acute RISRs include steroid treatment, creams, ointments, and hydrocolloid dressings, depending on the reaction grading. Chronic RISRs includes chronic ulcerations, telangiectasias, and fibrosis of the skin, and advanced treatments such as mesenchymal stem cells, hyperbaric oxygen therapy, superoxide dismutase, and low-intensity laser therapy can be considered. Here, we review and summarize the important mechanisms that cause RISRs as well as the standard and advanced treatments for RISRs.

Anthocyanins from black soybean seed coat prevent radiation-induced skin fibrosis by downregulating TGF-β and Smad3 expression

The aim of this study was to evaluate the protective effects of anthocyanins from the black soybean seed coat against radiation injury in dermal fibroblasts and mouse skin. Dermal fibroblasts treated with 50 and 100 µg/mL anthocyanins were irradiated with single doses of 20 Gy. Cell viability, intracellular reactive oxygen species (ROS) production, and mRNA expression were measured. A total of 60 mice were used for an in vivo study. A dose of 100 µg/mL anthocyanins was administered daily for 5 days before or after radiation therapy. Following irradiation (45 Gy), mice were inspected for gross pathology twice per wk for 8 weeks. At 4 and 8 weeks post-irradiation, dorsal skin was harvested for histopathologic examination and protein isolation. In dermal fibroblasts, treatment with 50 and 100 µg/mL anthocyanins significantly reduced radiation-induced apoptosis at 72 h and intracellular reactive oxygen species generation at 48 h. Furthermore, 100 µg/mL anthocyanins markedly decreased Smad3 mRNA expression and increased Smad7 mRNA expression at 72 h post-irradiation. In mice, treatment with 100 µg/mL anthocyanins resulted in a significant reduction in the level of skin injury, epidermal thickness, and collagen deposition after irradiation. Treatment with 100 µg/mL anthocyanins significantly decreased the number of α-SMA-, TGF-β-, and Smad3-positive cells after irradiation. Our study demonstrated that black soybean anthocyanins inhibited radiation-induced fibrosis by downregulating TGF-β and Smad3 expression. Therefore, anthocyanins may be a safe and effective candidate for the prevention of radiation-induced skin fibrosis.

Mechanisms of inflammatory responses to radiation and normal tissues toxicity: clinical implications

PURPOSE

Cancer treatment is one of the most challenging diseases in the present era. Among a few modalities for cancer therapy, radiotherapy plays a pivotal role in more than half of all treatments alone or combined with other cancer treatment modalities. Management of normal tissue toxicity induced by radiation is one of the most important limiting factors for an appropriate radiation treatment course. The evaluation of mechanisms of normal tissue toxicity has shown that immune responses especially inflammatory responses play a key role in both early and late side effects of exposure to ionizing radiation (IR). DNA damage and cell death, as well as damage to some organelles such as mitochondria initiate several signaling pathways that result in the response of immune cells. Massive cell damage which is a common phenomenon following exposure to a high dose of IR cause secretion of a lot of inflammatory mediators including cytokines and chemokines. These mediators initiate different changes in normal tissues that may continue for a long time after irradiation. In this study, we reviewed the mechanisms of inflammatory responses to IR that are involved in normal tissue toxicity and considered as the most important limiting factors in radiotherapy. Also, we introduced some agents that have been proposed for management of these responses.

CONCLUSIONS

The early inflammation during the radiation treatment is often a limiting factor in radiotherapy. In addition to the limiting factors, chronic inflammatory responses may increase the risk of second primary cancers through continuous free radical production, attenuation of tumor suppressor genes, and activation of oncogenes. Moreover, these effects may influence non-irradiated tissues through a mechanism named bystander effect.

Impaired Skin Barrier Due to Sebaceous Gland Atrophy in the Latent Stage of Radiation-Induced Skin Injury: Application of Non-Invasive Diagnostic Methods

Radiation-induced skin injury can take the form of serious cutaneous damage and have specific characteristics. Asymptomatic periods are classified as the latent stage. The skin barrier plays a critical role in the modulation of skin permeability and hydration and protects the body against a harsh external environment. However, an analysis on skin barrier dysfunction against radiation exposure in the latent stage has not been conducted. Thus, we investigated whether the skin barrier is impaired by irradiation in the latent stage and aimed to identify the molecules involved in skin barrier dysfunction. We analyzed skin barrier function and its components in SKH1 mice that received 20 and 40 Gy local irradiation. Increased transepidermal water loss and skin pH were observed in the latent stage of the irradiated skin. Skin barrier components, such as structural proteins and lipid synthesis enzymes in keratinocyte, increased in the irradiated group. Interestingly, we noted sebaceous gland atrophy and increased serine protease and inflammatory cytokines in the irradiated skin during the latent period. This finding indicates that the main factor of skin barrier dysfunction in the latent stage of radiation-induced skin injury is sebaceous gland deficiency, which could be an intervention target for skin barrier impairment.

Radiation induces proinflammatory dysbiosis: transmission of inflammatory susceptibility by host cytokine induction

OBJECTIVE

Radiation proctitis (RP) is a complication of pelvic radiotherapy which affects both the host and microbiota. Herein we assessed the radiation effect on microbiota and its relationship to tissue damage using a rectal radiation mouse model.

DESIGN

We evaluated luminal and mucosa-associated dysbiosis in irradiated and control mice at two postradiation time points and correlated it with clinical and immunological parameters. Epithelial cytokine response was evaluated using bacterial-epithelial co-cultures. Subsequently, germ-free (GF) mice were colonised with postradiation microbiota and controls and exposed to radiation, or dextran sulfate-sodium (DSS). Interleukin (IL)-1β correlated with tissue damage and was induced by dysbiosis. Therefore, we tested its direct role in radiation-induced damage by IL-1 receptor antagonist administration to irradiated mice.

RESULTS

A postradiation shift in microbiota was observed. A unique microbial signature correlated with histopathology. Increased colonic tumor necrosis factor (TNF)α, IL-1β and IL-6 expression was observed at two different time points. Adherent microbiota from RP differed from those in uninvolved segments and was associated with tissue damage. Using bacterial-epithelial co-cultures, postradiation microbiota enhanced IL-1β and TNFα expression compared with naïve microbiota. GF mice colonisation by irradiated microbiota versus controls predisposed mice to both radiation injury and DSS-induced colitis. IL-1 receptor antagonist administration ameliorated intestinal radiation injury.

CONCLUSIONS

The results demonstrate that rectal radiation induces dysbiosis, which transmits radiation and inflammatory susceptibility and provide evidence that microbial-induced radiation tissue damage is at least in part mediated by IL-1β. Environmental factors may affect the host via modifications of the microbiome and potentially allow for novel interventional approaches via its manipulation.

Radiation-Induced Dermatitis is Mediated by IL17-Expressing γδ T Cells

Radiation dermatitis is a serious cutaneous injury caused by radiation therapy or upon accidental nuclear exposure. However, the pathogenic immune mechanisms underlying this injury are still poorly understood. We seek to discover how the dysregulated immune response after irradiation orchestrates skin inflammation. The skin on the left flank of C57BL/6J wild-type and C57BL/6J Tcrd-/- mice, which are deficit in γδ T cells, was exposed to a single X-ray dose of 25 Gy, and the right-flank skin was used as a sham-irradiated control. At 4 weeks postirradiation, the wild-type skin exhibited signs of depilation, erythema and desquamation. Histological analysis showed hyperproliferation of keratinocytes and acanthosis. Dramatic elevation of IL17-expressing T cells was identified from the irradiated skin, which was mainly contributed by γδ T cells and innate lymphoid cells, rather than Th17 cells. Furthermore, protein levels of critical cytokines for IL17-expressing γδ T cell activation, IL1β and IL23 were found markedly upregulated. Lastly, radiation-induced dermatitis was significantly attenuated in γδ T cell knockout mice. In vitro, normal human epidermal keratinocytes (NHEKs) could be initiator cells of inflammation by providing a great number of pro-inflammatory mediators upon radiation, and as well as effector cells of epidermal hyperplasia in response to exogenous IL17 and/or IL22 treatment. Our findings implicate a novel role of IL17-expressing γδ T cells in mediating radiation-induced skin inflammation. This study reveals the innate immune response pathway as a potential therapeutic target for radiation skin injury.

Surgical Management of the Radiated Chest Wall and Its Complications

Radiation to the chest wall is common before resection of tumors. Osteoradionecrosis can occur after radiation treatment. Radical resection and reconstruction can be lifesaving. Soft tissue coverage using myocutaneous or omental flaps is determined by the quality of soft tissue available and the status of the vascular pedicle supplying available myocutaneous flaps. Radiation-induced sarcomas of the chest wall occur most commonly after radiation therapy for breast cancer. Although angiosarcomas are the most common radiation-induced sarcomas, osteosarcoma, myosarcomas, rhabdomyosarcoma, and undifferentiated sarcomas also occur. The most effective treatment is surgical resection. Inoperable tumors are treated with chemotherapy, with low response rates.

Inflammatory Skin Conditions Associated With Radiotherapy

Radiotherapy for cancer is used increasingly. Because skin cells undergo rapid turnover, the ionizing radiation of radiotherapy has collateral effects that are often expressed in inflammatory reactions. Some of these reactions-radiodermatitis and recall phenomenon, for example-are very familiar to dermatologists. Other, less common radiotherapy-associated skin conditions are often underdiagnosed but must also be recognized.

A Topical Mitochondria-Targeted Redox-Cycling Nitroxide Mitigates Oxidative Stress-Induced Skin Damage

Skin is the largest human organ, and it provides a first line of defense that includes physical, chemical, and immune mechanisms to combat environmental stress. Radiation is a prevalent environmental stressor. Radiation-induced skin damage ranges from photoaging and cutaneous carcinogenesis caused by UV exposure, to treatment-limiting radiation dermatitis associated with radiotherapy, to cutaneous radiation syndrome, a frequently fatal consequence of exposures from nuclear accidents. The major mechanism of skin injury common to these exposures is radiation-induced oxidative stress. Efforts to prevent or mitigate radiation damage have included development of antioxidants capable of reducing reactive oxygen species. Mitochondria are particularly susceptible to oxidative stress, and mitochondrial-dependent apoptosis plays a major role in radiation-induced tissue damage. We reasoned that targeting a redox cycling nitroxide to mitochondria could prevent reactive oxygen species accumulation, limiting downstream oxidative damage and preserving mitochondrial function. Here we show that in both mouse and human skin, topical application of a mitochondrially targeted antioxidant prevents and mitigates radiation-induced skin damage characterized by clinical dermatitis, loss of barrier function, inflammation, and fibrosis. Further, damage mitigation is associated with reduced apoptosis, preservation of the skin's antioxidant capacity, and reduction of irreversible DNA and protein oxidation associated with oxidative stress.

Role of Pro-inflammatory Cytokines in Radiation-Induced Genomic Instability in Human Bronchial Epithelial Cells

Inflammatory cytokines have been implicated in the regulation of radiation-induced genomic instability in the hematopoietic system and have also been shown to induce chronic DNA damage responses in radiation-induced senescence. We have previously shown that human bronchial epithelial cells (HBEC3-KT) have increased genomic instability and IL-8 production persisting at day 7 after exposure to high-LET (600 MeV/nucleon (56)Fe ions) compared to low-LET (320 keV X rays) radiation. Thus, we investigated whether IL-8 induction is part of a broader pro-inflammatory response produced by the epithelial cells in response to damage, which influences genomic instability measured by increased micronuclei and DNA repair foci frequencies. We found that exposure to radiation induced the release of multiple inflammatory cytokines into the media, including GM-CSF, GROα, IL-1α, IL-8 and the inflammation modulator, IL-1 receptor antagonist (IL-1RA). Our results suggest that this is an IL-1α-driven response, because an identical signature was induced by the addition of recombinant IL-1α to nonirradiated cells and functional interference with recombinant IL-1RA (Anakinra) or anti-IL-1α function-blocking antibody, decreased IL-8 production induced by radiation exposure. However, genomic instability was not influenced by this pathway as addition of recombinant IL-1α to naive or irradiated cells or the presence of IL-1 RA under the same conditions as those that interfered with the function of IL-8, did not affect micronuclei or DNA repair foci frequencies measured at day 7 after exposure. While dose-response studies revealed that genomic instability and IL-8 production are the consequences of targeted effects, experiments employing a co-culture transwell system revealed the propagation of pro-inflammatory responses but not genomic instability from irradiated to nonirradiated cells. Collectively, these results point to a cell-autonomous mechanism sustaining radiation-induced genomic instability in this model system and suggest that while molecules associated with these mechanisms could be markers for persisting damage, they reflect two different outcomes.

A Review of the Use of Topical Calendula in the Prevention and Treatment of Radiotherapy-Induced Skin Reactions

Calendula is a topical agent derived from a plant of the marigold family Calendula Officinalis. Containing numerous polyphenolic antioxidants, calendula has been studied in both the laboratory and clinical setting for the use in treating and preventing radiation induced skin toxicity. Despite strong evidence in the laboratory supporting calendula's mechanism of action in preventing radiation induced skin toxicity, clinical studies have demonstrated mixed results. In light of the controversy surrounding the efficacy of calendula in treating and preventing radiodermatitis, the topic warrants further discussion.

The differential role of human macrophage in triggering secondary bystander effects after either gamma-ray or carbon beam irradiation

The abscopal effect could be an underlying factor in evaluating prognosis of radiotherapy. This study established an in vitro system to examine whether tumor-generated bystander signals could be transmitted by macrophages to further trigger secondary cellular responses after different irradiations, where human lung cancer NCI-H446 cells were irradiated with either γ-rays or carbon ions and co-cultured with human macrophage U937 cells, then these U937 cells were used as a bystander signal transmitter and co-cultured with human bronchial epithelial cells BEAS-2B. Results showed that U937 cells were only activated by γ-irradiated NCI-H446 cells so that the secondary injuries in BEAS-2B cells under carbon ion irradiation were weaker than γ-rays. Both TNF-α and IL-1α were involved in the γ-irradiation induced secondary bystander effect but only TNF-α contributed to the carbon ion induced response. Further assay disclosed that IL-1α but not TNF-α was largely responsible for the activation of macrophages and the formation of micronucleus in BEAS-2B cells. These data suggest that macrophages could transfer secondary bystander signals and play a key role in the secondary bystander effect of photon irradiation, while carbon ion irradiation has conspicuous advantage due to its reduced secondary injury.

Endothelial perturbations and therapeutic strategies in normal tissue radiation damage

Most cancer patients are treated with radiotherapy, but the treatment can also damage the surrounding normal tissue. Radiotherapy side-effects diminish patients’ quality of life, yet effective biological interventions for normal tissue damage are lacking. Protecting microvascular endothelial cells from the effects of irradiation is emerging as a targeted damage-reduction strategy. We illustrate the concept of the microvasculature as a mediator of overall normal tissue radiation toxicity through cell death, vascular inflammation (hemodynamic and molecular changes) and a change in functional capacity. Endothelial cell targeted therapies that protect against such endothelial cell perturbations and the development of acute normal tissue damage are mostly under preclinical development. Since acute radiation toxicity is a common clinical problem in cutaneous, gastrointestinal and mucosal tissues, we also focus on damage in these tissues.

Factors modifying the risk for developing acute skin toxicity after whole-breast intensity modulated radiotherapy

Background

After breast-conserving radiation therapy most patients experience acute skin toxicity to some degree. This may impair patients’ quality of life, cause pain and discomfort. In this study, we investigated treatment and patient-related factors, including genetic polymorphisms, that can modify the risk for severe radiation-induced skin toxicity in breast cancer patients.

Methods

We studied 377 patients treated at Ghent University Hospital and at ST.-Elisabeth Clinic and Maternity in Namur, with adjuvant intensity modulated radiotherapy (IMRT) after breast-conserving surgery for breast cancer. Women were treated in a prone or supine position with normofractionated (25 × 2 Gy) or hypofractionated (15 × 2.67 Gy) IMRT alone or in combination with other adjuvant therapies. Patient- and treatment-related factors and genetic markers in regulatory regions of radioresponsive genes and in LIG3, MLH1 and XRCC3 genes were considered as variables. Acute dermatitis was scored using the CTCAEv3.0 scoring system. Desquamation was scored separately on a 3-point scale (0-none, 1-dry, 2-moist).

Results

Two-hundred and twenty patients (58%) developed G2+ dermatitis whereas moist desquamation occurred in 56 patients (15%). Normofractionation (both p < 0.001), high body mass index (BMI) (p = 0.003 and p < 0.001), bra cup size ≥ D (p = 0.001 and p = 0.043) and concurrent hormone therapy (p = 0.001 and p = 0.037) were significantly associated with occurrence of acute dermatitis and moist desquamation, respectively. Additional factors associated with an increased risk of acute dermatitis were the genetic variation in MLH1 rs1800734 (p=0.008), smoking during RT (p = 0.010) and supine IMRT (p = 0.004). Patients receiving trastuzumab showed decreased risk of acute dermatitis (p < 0.001).

Conclusions

The normofractionation schedule, supine IMRT, concomitant hormone treatment and patient related factors (high BMI, large breast, smoking during treatment and the genetic variation in MLH1 rs1800734) were associated with increased acute skin toxicity in patients receiving radiation therapy after breast-conserving surgery. Trastuzumab seemed to be protective.

Mechanisms of radiation-induced normal tissue toxicity and implications for future clinical trials

To summarize current knowledge regarding mechanisms of radiation-induced normal tissue injury and medical countermeasures available to reduce its severity. Advances in radiation delivery using megavoltage and intensity-modulated radiation therapy have permitted delivery of higher doses of radiation to well-defined tumor target tissues. Injury to critical normal tissues and organs, however, poses substantial risks in the curative treatment of cancers, especially when radiation is administered in combination with chemotherapy. The principal pathogenesis is initiated by depletion of tissue stem cells and progenitor cells and damage to vascular endothelial microvessels. Emerging concepts of radiation-induced normal tissue toxicity suggest that the recovery and repopulation of stromal stem cells remain chronically impaired by long-lived free radicals, reactive oxygen species, and pro-inflammatory cytokines/chemokines resulting in progressive damage after radiation exposure. Better understanding the mechanisms mediating interactions among excessive generation of reactive oxygen species, production of pro-inflammatory cytokines and activated macrophages, and role of bone marrow-derived progenitor and stem cells may provide novel insight on the pathogenesis of radiation-induced injury of tissues. Further understanding the molecular signaling pathways of cytokines and chemokines would reveal novel targets for protecting or mitigating radiation injury of tissues and organs.

Vasculotide, an Angiopoietin-1 mimetic, reduces acute skin ionizing radiation damage in a preclinical mouse model

Background

Most cancer patients are treated with radiotherapy, but the treatment can also damage the surrounding normal tissue. Acute skin damage from cancer radiotherapy diminishes patients’ quality of life, yet effective biological interventions for this damage are lacking. Protecting microvascular endothelial cells from irradiation-induced perturbations is emerging as a targeted damage-reduction strategy. Since Angiopoetin-1 signaling through the Tie2 receptor on endothelial cells opposes microvascular perturbations in other disease contexts, we used a preclinical Angiopoietin-1 mimic called Vasculotide to investigate its effect on skin radiation toxicity using a preclinical model.

Methods

Athymic mice were treated intraperitoneally with saline or Vasculotide and their flank skin was irradiated with a single large dose of ionizing radiation. Acute cutaneous damage and wound healing were evaluated by clinical skin grading, histology and immunostaining. Diffuse reflectance optical spectroscopy, myeloperoxidase-dependent bioluminescence imaging of neutrophils and a serum cytokine array were used to assess inflammation. Microvascular endothelial cell response to radiation was tested with in vitro clonogenic and Matrigel tubule formation assays. Tumour xenograft growth delay experiments were also performed. Appreciable differences between treatment groups were assessed mainly using parametric and non-parametric statistical tests comparing areas under curves, followed by post-hoc comparisons.

Results

In vivo, different schedules of Vasculotide treatment reduced the size of the irradiation-induced wound. Although skin damage scores remained similar on individual days, Vasculotide administered post irradiation resulted in less skin damage overall. Vasculotide alleviated irradiation-induced inflammation in the form of reduced levels of oxygenated hemoglobin, myeloperoxidase bioluminescence and chemokine MIP-2. Surprisingly, Vasculotide-treated animals also had higher microvascular endothelial cell density in wound granulation tissue. In vitro, Vasculotide enhanced the survival and function of irradiated endothelial cells.

Conclusions

Vasculotide administration reduces acute skin radiation damage in mice, and may do so by affecting several biological processes. This radiation protection approach may have clinical impact for cancer radiotherapy patients by reducing the severity of their acute skin radiation damage.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-614) contains supplementary material, which is available to authorized users.

Local and systemic pathogenesis and consequences of regimen-induced inflammatory responses in patients with head and neck cancer receiving chemoradiation

Treatment-related toxicities are common among patients with head and neck cancer, leading to poor clinical outcomes, reduced quality of life, and increased use of healthcare resources. Over the last decade, much has been learned about the pathogenesis of cancer regimen-related toxicities. Historically, toxicities were separated into those associated with tissue injury and those with behavioural or systemic changes. However, it is now clear that tissue-specific damage such as mucositis, dermatitis, or fibrosis is no longer the sole consequence of direct clonogenic cell death, and a relationship between toxicities that results in their presentation as symptom clusters has been documented and attributed to a common underlying pathobiology. In addition, the finding that patients commonly develop toxicities representing tissue injury outside radiation fields and side effects such as fatigue or cognitive dysfunction suggests the generation of systemic as well as local mediators. As a consequence, it might be appropriate to consider toxicity syndromes, rather than the traditional approach, in which each side effect was considered as an autonomous entity. In this paper, we propose a biologically based explanation which forms the basis for the diverse constellation of toxicities seen in response to current regimens used to treat cancers of the head and neck.

The use of antioxidants in radiotherapy-induced skin toxicity

Radiation-induced skin damage is one of the most common complications of radiotherapy. In order to combat these side effects, patients often turn to alternative therapies, which often include antioxidants. Antioxidants such as those in the polyphenol chemical class, xanthine derivatives, tocepherol, sucralfate, and ascorbate have been studied for their use in either preventing or treating radiotherapy-induced skin damage. Apart from their known role as free radical scavengers, some of these antioxidants appear to alter cytokine release affecting cutaneous and systemic changes. We review the role of antioxidants in treating and preventing radiation-induced skin damage as well as the possible complications of using such therapy.

3M Cavilon No-Sting Barrier Film or topical corticosteroid (mometasone furoate) for protection against radiation dermatitis: A clinical trial

BACKGROUND/PURPOSE

Evidence on the prevention of radiation dermatitis is lacking. The aim of this study was to investigate the effect of 3M Cavilon No Sting Barrier Film and topical corticosteroids on irradiated skin.

METHODS

Thirty-nine postoperative breast cancer patients were randomized into three groups for intraindividual comparison (skin to be irradiated was divided into 2 parts): (1) 3M No Sting Barrier Film versus no treatment; (2) corticosteroid versus no treatment; and (3) corticosteroid versus 3M No Sting Barrier Film. The primary end points monitored were the time to first occurrence of grade 1 pruritus, pain score of 3 and grade 2 radiation dermatitis. The secondary end points studied were the incidence of grade 3 radiation dermatitis and total pain scores. Data analysis was done using the SPSS software version 10.

RESULTS

Skin given the 3M barrier film experienced a later occurrence of pruritus compared to both corticosteroids and untreated, although this was statistically insignificant. Corticosteroids delayed the time to occurrence of grade 2 dermatitis compared to both untreated skin and 3M barrier film, (mean day of onset = corticosteroid: 52 vs. untreated: 43, p = 0.092; corticosteroid: 53.4 vs. 3M barrier film: 44.5, p = 0.002, t test). Skin given corticosteroids had the lowest incidence of grade 3 dermatitis among all three conditions, although the differences were statistically insignificant. No statistically significant differences were noted in total pain scores.

CONCLUSION

The 3M barrier film may be helpful against dermatitis associated pruritus. Corticosteroids may delay the time of onset of severe skin reactions and also reduce the incidence of severe radiation dermatitis.