Radiation-induced Fibrosis Research Articles

A Phase II, Randomized, Double Blind, Placebo Controlled Study of the Safety and Efficacy of a Caffeine-Based Antifibrosis Cream in Patients with Breast Cancer Undergoing Radiation Therapy

Radiation induced fibrosis (RIF) is a common long term adverse event in patients undergoing post-mastectomy radiation therapy (PMRT) which can cause capsular contracture, implant loss, and reconstruction complications in women with implant-based breast reconstruction. At a molecular level, adenosine is a driver of RIF. Preclinical data have shown that pharmacologic blockade of the adenosine A2A Receptor (A2AR) in mice as well as an A2AR knockout mouse model prevented skin fibrosis associated with radiation injury. Caffeine is an A2AR antagonist which has been shown to block the development of hepatic fibrosis in liver disease patients. We present a phase II placebo controlled clinical trial to evaluate whether a caffeine-based cream can prevent RIF and thus reduce the rates of reconstructive complications in patients with tissue expander-based reconstruction requiring PMRT. Women ≥ 18 years old with breast carcinoma stage 0-III status post mastectomy with tissue expander-based reconstruction who require PMRT to the chest wall +/- the regional nodes are being enrolled. The target accrual is 60 patients. Boost field to the chest wall, scar and/or nodal region is allowed. Patients with inflammatory breast cancer or those requiring skin bolus are excluded. Prior to starting radiation, patients will be randomized to placebo vs. caffeine cream and they will be instructed to apply the cream twice a day starting on the first day of radiation treatment and continuing daily for the duration of radiation until the removal of tissue expanders. The primary study endpoint is reconstructive complications requiring rehospitalization or reoperation by 2 years post radiation including reconstructive failure with or without reconstruction. A safety endpoint of grade ≥ 2 acute radiation dermatitis will also serve as a co-primary endpoint. Secondary endpoints are wound infection/cellulitis, hematoma, seroma, threatened exposure, wound dehiscence, implant leakage, rupture, and or deflation, and capsular contracture that do not meet criteria for the primary endpoint. Clinician rated cosmesis, local recurrence, regional recurrence, distant metastasis and survival up to 4 years are additional secondary endpoints. Exploratory endpoint includes the use of shear wave elastography (SWE) as a potential tool to quantitatively measure post irradiation fibrosis. Correlative aims include assessing epidermal thickness and fat layer thickness from tissue obtained at time of implant exchange for association with the development of fibrosis. The primary efficacy endpoint will be estimated using Kaplan Meier methods from date of randomization. Treatment comparisons will be based on a 2-sided log rank chi-square test and the hazard ratio will be estimated with 95% confidence intervals. The study started accruing in 12/2019 and is estimated to end by 04/2024. As of January 2023, 67% (40/60 patients) of the planned patients have been enrolled. To be determined. To be determined.

The Early and Late Effects of High-Dose Irradiation on Cardiac Injury in a Rat Model

Radiation-induced heart disease is a critical concern after radiotherapy (RT) for thoracic and chest wall tumors; however, the biological effects and mechanisms are still unknown. In this study, we investigated dose-responsive functional and pathological changes in rat hearts at 1, 3, and 5 months after high-dose irradiation. Then, we sought to elucidate the underlying mechanisms of myocardial changes induced by high-dose irradiation. Whole hearts of rats (N = 72) were irradiated with a single fraction of 0 (control), 10, 20, or 30 Gy and allocated into three groups according to the follow-up period after RT: baseline, one, three, and five months. During follow-up periods, rats underwent functional evaluation by electrocardiogram and echocardiography at 4-week intervals. If a rat's body weight decreased by 20% or more, it was considered premature death, and the heart was explanted immediately. Otherwise, all hearts were explanted when each group's follow-up period was completed. Pathological changes of cardiac structures were evaluated using a light microscope after staining with hematoxylin-eosin, Masson's trichrome, α-smooth muscle actin, desmin, and connexin-43. All rats irradiated with 0 or 10 Gy completed their follow-up periods with continuously increasing body weight. However, among rats irradiated with 20 or 30 Gy, half of the rats died prematurely at 8-10 weeks after RT, and the remainder survived until 20 weeks. In echocardiography, increased wall thickness and E/E' ratio, and decreased end-diastolic volume were observed in 20-30 Gy groups compared to 0-10 Gy groups from 8 weeks after RT. Ejection fraction was preserved in all groups. In pathological review, 20-30 Gy groups demonstrated diffuse inflammation and vacuolization at 4 weeks. Then, at 8 weeks, prominent fibrotic changes and intercalated disc disruptions were observed. Notably, fibrotic changes were somewhat resolved at 20 weeks, but intercalated disc disruptions were not repaired until 20 weeks. The 0 and 10 Gy groups showed no significant changes in both functional and pathological analyses. Rats irradiated with 20 or 30 Gy showed diastolic dysfunction in functional analysis and time-dependent myocardial changes in pathological analysis. Radiation-induced fibrosis might be a "reactive" fibrosis, which could proceed to either a profibrotic course (progressive fibrosis) or an anti-fibrotic course (recovery phase). Further studies are needed to identify whether high-dose irradiation-induced cardiac fibrosis could be reversible.

Differential Oxidative Stress Responses in Type II Airway Epithelial Cells Impact Premature Senescence and Lung Fibrosis Susceptibility

Radiation-Induced Pulmonary Fibrosis (RIPF) is a late toxicity characterized by premature senescence in Type II airway epithelial cells (AECII) and accumulation of alternatively activated (M2) macrophages. Differential susceptibility to RIPF is observed across mouse strains. Based on our prior study of the effects of macrophage variation on RIPF, we hypothesized that intrinsic differences in AECII oxidative stress response across mouse strains also impact susceptibility to RIPF. Ten-week-old female mice from C57L, C57BL6 and C3H/HeN strains were exposed to thoracic irradiation (5x6 Gy, n>5 per group). Fifteen weeks after radiation, lung tissue was collected and examined with Masson-Trichrome staining (histologic changes) and β-galactosidase activity assay (senescence). AECII prepared from mice of each strain were exposed to irradiation. To assess differential gene expression, total RNA was extracted and assessed with a multiplex analysis platform and quantitative PCR. Senescence was assessed by β-galactosidase activity assay in primary AECII after irradiation or after co-culture with M2 macrophages polarized with IL13. Susceptibility to radiation-induced lung injury, survival, and premature AECII senescence vary by mouse strain: C57L (fibrosis-prone), C57BL6J (-intermediate) and C3H/HeN (-resistant). Enriched AECII from each strain exhibited differential expression of genes related to inflammatory responses including SASP production after irradiation. Minimal increased expression of Il1r1 was observed in irradiated and unirradiated AECII from C3H/HeN, however Il1rn levels were markedly elevated in response to irradiation. The expression of Thioredoxin (Txn) and Thioredoxin reductase 1 (Txnrd1) in AECII from C3H/HeN was significantly higher than those observed in other strains. In Vivo, C3H/HeN mouse lungs exhibited the least premature senescence in AECII after irradiation. Premature senescence in AECII irradiated In Vitro or co-cultured with superoxide anion-producing M2 macrophages was substantially less in AECII from C3H/HeN compared to other strains. A comparison of primary AECII from three different mouse strains identified intrinsic differences in expression of major inflammatory signaling (IL1R and IL1RN) and redox homeostasis status (TXN and TXNDR1) molecules. This study is the first to demonstrate that intrinsic differences in AECII impacts susceptibility to premature senescence and lung fibrosis after irradiation.

Emetine dihydrochloride alleviated radiation-induced lung injury through inhibiting EMT.

Radiation-induced lung injury (RILI), divided into early radiation pneumonia (RP) and late radiation-induced pulmonary fibrosis (RIPF), is a common serious disease after clinical chest radiotherapy or nuclear accident, which seriously threatens the life safety of patients. There has been no effective prevention or treatment strategy till now. Epithelial-mesenchymal transition (EMT) is a key step in the occurrence and development of RILI. In this study, we demonstrated that emetine dihydrochloride (EDD) alleviated RILI through inhibiting EMT. We found that EDD significantly attenuated EMT-related markers, reduced Smad3 phosphorylation expression after radiation. Then, for the first time, we observed EDD alleviated lung hyperaemia and reduced collagen deposit induced by irradiation, providing protection against RILI. Finally, it was found that EDD inhibited radiation-induced EMT in lung tissues. Our study suggested that EDD alleviated RILI through inhibiting EMT by blocking Smad3 signalling pathways. In summary, our results indicated that EDD is a novel potential radioprotector for RILI.

Pre-Existing Interstitial Lung Abnormalities in Patients with Head and Neck Squamous Cell Carcinoma and Their Follow Up after Therapy.

Interstitial lung abnormalities (ILAs) are incidentally found nondependent parenchymal abnormalities affecting more than 5% of any lung zone and are potentially related to interstitial lung disease and worsening post-treatment outcomes in malignancies and infectious diseases. The aim of this study was to determine the prevalence and type of ILA changes in patients with head and neck squamous cell carcinoma (HNSCC) and their change in the follow-up period. This retrospective single-center study included 113 patients with newly diagnosed HNSCC who underwent lung MSCT prior to treatment. ILAs were reported in 13.3% of patients on pretreatment MSCT. Patients with ILAs were significantly older (median 75 vs. 67 years). ILAs were most prevalent in lower zones (73.3%) (p = 0.0045). The most reported ILA subtype was subpleural non-fibrotic (60%) (p = 0.0354). Reticulations were the most frequently described pattern (93.3%) (p < 0.0001). Progression of ILAs was reported in almost 30% of patients after receiving therapy. Patients with pre-existing ILAs were more likely to develop radiation-induced lung fibrosis after adjuvant radiotherapy (p = 0.0464). In conclusion, ILA's incidence, distribution and presentation were similar to previous research conducted in other special cohorts. Our research suggests a possible association of more frequent radiation pneumonitis with ILA changes in patients with HNSCC, which should be further investigated.

Activation of Nrf2/ARE pathway by Anisodamine (654-2) for Inhibition of cellular aging and alleviation of Radiation-Induced lung injury

BackgroundRadiation-induced lung injury (RILI) is a common side effect of thoracic tumor radiotherapy, including early-stage radiation-induced lung injury (RP) and late-stage radiation-induced pulmonary fibrosis (RIPF). Currently, it is urgently needed to clarify the pathogenesis of RILI and find safe and effective RILI treatment methods. Irradiation causes DNA damage and oxidative stress in tissues and cells, induces cellular senescence, and promotes the occurrence and development of RILI. In recent years, Anisodamine (654-2) has shown potential therapeutic value in acute lung injury, acute kidney injury, chlamydial pneumonia, and COVID-19. However, there is currently no research on the mechanism of 654-2-mediated cellular senescence and its preventive and therapeutic effects on RILI. PurposeThis study aimed to investigate the protective effect and mechanism of 654-2 on X-ray-induced RILI. MethodsIn vivo experiments involved a mouse RILI model with 18 Gy X-ray irradiation. Mice were divided into control, model, medication (control + 654-2), and treatment (model + 654-2) groups. And mice in medication and treatment groups were intraperitoneal injection of 5 mg/kg 654-2 every other day until being sacrificed at week 6. In vitro experiments used MLE-12 cells irradiated with 16 Gy and divided into control, model, and model + 654-2（2 μM and 10 μM） groups. Various assays were performed to evaluate lung tissue morphology, fibrosis, apoptosis, cytokine expression, cellular senescence, protein expression, and antioxidant capacity. Results654-2 mitigated pulmonary pathological damage, inflammation, DNA damage, cellular senescence, and apoptosis in RILI mice and MLE-12 cells. It restored epithelial cell proliferation ability and enhanced antioxidant capacity. Additionally, 654-2 activated the Nrf2/ARE pathway, increased Nrf2 phosphorylation, and upregulated antioxidant gene expression. Inhibition of Nrf2 reversed the effects of 654-2 on ROS production, antioxidant capacity, and cell senescence. Conclusion654-2 can activate the Nrf2/ARE pathway, enhance cellular antioxidant capacity, and inhibit cellular senescence, thereby exerting a protective effect against RILI.

1142 Using Lipofilling to Improve Skin Quality Following Severe Radiation Necrosis to Enable Successful Joint Replacement – a Case Report and Literature Review

Abstract Case A 74-year-old female patient presented with severe osteoarthritis and pathological fracture of the left knee, following treatment with radiotherapy of osteosarcoma over a decade ago. Surgical management of the fracture was initially not possible, due to radiation-induced fibrosis of the skin. She was referred to the plastic surgery department where she underwent a total of three sessions of fat grafting over nine months. The rigotomy approach was applied to the large area of irradiated skin. As a result, her skin quality improved such that a successful total knee replacement was possible. The outcome of this was better mobility and improved quality of life. Conclusions Skin quality after radiotherapy can limit surgical options, even decades after treatment. Fat grafting, also known as lipofilling, is a commonly utilised reconstructive and cosmetic adjunct. However, recent reports of its effect on skin quality are gaining popularity. We present a case of successful use of fat transfer to improve irradiated skin quality prior to successful joint replacement; this is a novel use case which we believe to be the first published.

Oncostatin M/Oncostatin M Receptor Signal Induces Radiation-Induced Heart Fibrosis by Regulating SMAD4 in Fibroblast

Radiation-induced heart fibrosis (RIHF) is a severe consequence of radiation-induced heart damage (RIHD) leading to impaired cardiac function. The involvement of oncostatin M (OSM) and its receptor (OSMR) in RIHD remains unclear. This study aimed to investigate the specific mechanism of OSM/OSMR in RIHF/RIHD. RNA sequencing was performed on heart tissues from a RIHD mouse model. OSM levels were assessed in serum samples obtained from patients receiving thoracic radiation therapy (RT), as well as in RIHF mouse heart tissues and serum using enzyme-linked immunosorbent assay. Fiber activation was evaluated through costimulation of primary cardiac fibroblasts and NIH3T3 cells with RT and OSM, using Western blotting, immunofluorescence, and quantitative Polymerase Chain Reaction (qPCR). Adeno-associated virus serotype 9-mediated overexpression or silencing of OSM specifically in the heart was performed in vivo to assess cardiac fibrosis levels by transthoracic echocardiography and pathologic examination. The regulatory mechanism of OSM on the transcription level of SMAD4 was further explored in vitro using mass spectrometric analysis, chromatin immunoprecipitation-qPCR, and DNA pull-down. OSM levels were elevated in the serum of patients after thoracic RT as well as in RIHF mouse cardiac endothelial cells and mouse serum. The OSM rate (post-RT/pre-RT) and the heart exposure dose in RT patients showed a positive correlation. Silencing OSMR in RIHF mice reduced fibrosis, while OSMR overexpression increased fibrotic responses. Furthermore, increased OSM promoted histone acetylation (H3K27ac) in the SMAD4 promoter region, influencing SMAD4 transcription and subsequently enhancing fibrotic response. The findings demonstrated that OSM/OSMR signaling promotes SMAD4 transcription in cardiac fibroblasts through H3K27 hyperacetylation, thereby promoting radiation-induced cardiac fibrosis and manifestations of RIHD.

Human adipose ECM alleviates radiation-induced skin fibrosis via endothelial cell-mediated M2 macrophage polarization

Radiation therapy can lead to late radiation-induced skin fibrosis (RISF), causing movement restriction, pain, and organ dysfunction. This study evaluated adipose-derived extracellular matrix (Ad-ECM) as a mitigator of RISF. Female C57BL/6J mice that were irradiated developed fibrosis, which was mitigated by a single local Ad-ECM injection, improving limb movement and reducing epithelium thickness and collagen deposition. Ad-ECM treatment resulted in decreased expression of pro-inflammatory and fibrotic genes, and upregulation of anti-inflammatory cytokines, promoting M2 macrophage polarization. Co-culture of irradiated human fibroblasts with Ad-ECM down-modulated fibrotic gene expression and enhanced bone marrow cell migration. Ad-ECM treatment also increased interleukin (IL)-4, IL-5, and IL-15 expression in endothelial cells, stimulating M2 macrophage polarization and alleviating RISF. Prophylactic use of Ad-ECM showed effectiveness in mitigation. This study suggests Ad-ECM's potential in treating chronic-stage fibrosis.

Glycyrrhetinic Acid Mitigates Radiation-Induced Pulmonary Fibrosis via Inhibiting the Secretion of TGF-β1 by Treg Cells

Radiation-induced pulmonary fibrosis (RIPF) is a common side effect of radiation therapy for thoracic tumors without effective prevention and treatment methods at present. The aim of this study was to explore whether glycyrrhetinic acid (GA) has a protective effect on RIPF and the underlying mechanism. A RIPF mouse model administered GA was used to determine the effect of GA on RIPF. The cocultivation of regulatory T (Treg) cells with mouse lung epithelial-12 cells or mouse embryonic fibroblasts and intervention with GA or transforming growth factor-β1 (TGF-β1) inhibitor to block TGF-β1 was conducted to study the mechanism by which GA alleviates RIPF. Furthermore, injection of Treg cells into GA-treated RIPF mice to upregulate TGF-β1 levels was performed to verify the roles of TGF-β1 and Treg cells. GA intervention improved the damage to lung tissue structure and collagen deposition and inhibited Treg cell infiltration, TGF-β1 levels, epithelial mesenchymal transition (EMT), and myofibroblast (MFB) transformation in mice after irradiation. Treg cell-induced EMT and MFB transformation in vitro were prevented by GA, as well as a TGF-β1 inhibitor, by decreasing TGF-β1. Furthermore, reinfusion of Treg cells upregulated TGF-β1 levels and exacerbated RIPF in GA-treated RIPF mice. GA can improve RIPF in mice, and the corresponding mechanisms may be related to the inhibition of TGF-β1 secreted by Treg cells to induce EMT and MFB transformation. Therefore, GA may be a promising therapeutic candidate for the clinical treatment of RIPF.

Radiomic analysis for early differentiation of lung cancer recurrence from fibrosis in patients treated with lung stereotactic ablative radiotherapy.

The development of radiation-induced fibrosis after SABR can obscure follow-up images and delay detection of a local recurrence in early-stage lung cancer patients. The objective of this study was to develop a radiomics model for computer-assisted detection of local recurrence and fibrosis for an earlier timepoint (<1 year) after the SABR treatment.&#xD;&#xD;This retrospective clinical study included CT images (n=107) of 66 patients treated with SABR. A z-score normalization technique was used for radiomic feature standardization across scanner protocols. The training set for the radiomics model consisted of CT images (66 patients; 22 recurrences and 44 fibrosis) obtained at 24 months (median) follow-up. The test set included CT-images of 41 patients acquired at 5-12 months follow-up. Combinations of four widely used machine learning techniques (support vector machines (SVMs), gradient boosting, random forests (RF), and logistic regression (LR)) and feature selection methods (Relief feature scoring, maximum relevance minimum redundancy (MRMR), mutual information maximization (MIM), forward feature selection, and LASSO) were investigated. Pyradiomics was used to extract 106 radiomic features from the CT-images for feature selection and classification. &#xD;&#xD;An RF + LASSO model scored the highest in terms of AUC (0.87) and obtained a sensitivity of 75% and a specificity of 88% in identifying a local recurrence in the test set. In the training set, 86% accuracy was achieved using five-fold cross-validation. Delong's test indicated that AUC achieved by the RF+LASSO is significantly better than 11 other machine learning models presented here. The top three radiomic features: Interquartile Range (first order), Cluster Prominence (GLCM), and Autocorrelation (GLCM), were revealed as differentiating a recurrence from fibrosis with this model.&#xD;&#xD;The radiomics model selected, out of multiple machine learning and feature selection algorithms, was able to differentiate a recurrence from fibrosis in earlier follow-up CT-images with a high specificity rate and satisfactory sensitivity performance. &#xD.

Inhibition of tyrosine kinase Fgr prevents radiation-induced pulmonary fibrosis (RIPF)

Cellular senescence is involved in the development of pulmonary fibrosis as well as in lung tissue repair and regeneration. Therefore, a strategy of removal of senescent cells by senolytic drugs may not produce the desired therapeutic result. Previously we reported that tyrosine kinase Fgr is upregulated in ionizing irradiation-induced senescent cells. Inhibition of Fgr reduces the production of profibrotic proteins by radiation-induced senescent cells in vitro; however, a mechanistic relationship between senescent cells and radiation-induced pulmonary fibrosis (RIPF) has not been established. We now report that senescent cells from the lungs of mice with RIPF, release profibrotic proteins for target cells and secrete chemotactic proteins for marrow cells. The Fgr inhibitor TL02-59, reduces this release of profibrotic chemokines from the lungs of RIPF mice, without reducing numbers of senescent cells. In vitro studies demonstrated that TL02-59 abrogates the upregulation of profibrotic genes in target cells in transwell cultures. Also, protein arrays using lung fibroblasts demonstrated that TL02-59 inhibits the production of chemokines involved in the migration of macrophages to the lung. In thoracic-irradiated mice, TL02-59 prevents RIPF, significantly reduces levels of expression of fibrotic gene products, and significantly reduces the recruitment of CD11b+ macrophages to the lungs. Bronchoalveolar lavage (BAL) cells from RIPF mice show increased Fgr and other senescent cell markers including p16. In human idiopathic pulmonary fibrosis (IPF) and in RIPF, Fgr, and other senescent cell biomarkers are increased. In both mouse and human RIPF, there is an accumulation of Fgr-positive proinflammatory CD11b+ macrophages in the lungs. Thus, elevated levels of Fgr in lung senescent cells upregulate profibrotic gene products, and chemokines that might be responsible for macrophage infiltration into lungs. The detection of Fgr in senescent cells that are obtained from BAL during the development of RIPF may help predict the onset and facilitate the delivery of medical countermeasures.

Cryptotanshinone alleviates radiation-induced lung fibrosis via modulation of gut microbiota and bile acid metabolism.

Cryptotanshinone (CPT), a major biological active ingredient extracted from root of Salvia miltiorrhiza (Danshen), has shown several pharmacological activities. However, the effect of CPT on radiation-induced lung fibrosis (RILF) is unknown. In this study, we explored the protective effects of CPT on RILF from gut-lung axis angle, specifically focusing on the bile acid (BA)-gut microbiota axis. We found that CPT could inhibit the process of epithelial mesenchymal transformation (EMT) and suppress inflammation to reduce the deposition of extracellular matrix in lung fibrosis in mice induced by radiation. In addition, 16S rDNA gene sequencing and BAs-targeted metabolomics analysis demonstrated that CPT could improve the dysbiosis of gut microbiota and BA metabolites in RILF mice. CPT significantly enriched the proportion of the beneficial genera Enterorhabdus and Akkermansia, and depleted that of Erysipelatoclostridium, which were correlated with increased intestinal levels of several farnesoid X receptor (FXR) natural agonists, such as deoxycholic acid and lithocholic acid, activating the FXR pathway. Taken together, these results suggested that CPT can regulate radiation-induced disruption of gut microbiota and BAs metabolism of mice, and reduce the radiation-induced lung inflammation and fibrosis. Thus, CPT may be a promising drug candidate for treating RILF.

Fluorescent Pirfenidone-Cerium(III) nanocomplexes protect against radiation-induced pulmonary fibrosis and inhibit tumor cell growth

Radiation-induced pulmonary fibrosis (RIPF) is a common adverse effect of thoracic radiation therapy. Although pirfenidone is approved for treating pulmonary fibrosis, its utility is limited by its short half-life and ability to scavenge reactive oxygen species (ROS). Thus, a nanoscale complexes of cerium(III), 10-carboxyl-pirfenidone, and 1,10-phenanthroline (NPs Ce(phen)Pirf3) was developed to prevent RIPF in a mouse model. NPs Ce(phen)Pirf3 was successfully prepared using a simple moderate solvothermal method and characterized using FTIR, electrospray ionization MS, 1H nuclear magnetic NMR, and transmission electron microscopy. The cerium(III) nanocomplexes exhibited a near-spherical shape and dissolved in water with a diameter of ∼125.2 nm, as characterized by dynamic light scattering. Compared with pirfenidone, NPs Ce(phen)Pirf3 with blue fluorescence exhibited prolonged retention times with thoracic-specific accumulation in vivo. Mice received 15 Gy gamma-ray treatment on the thorax with or without NPs Ce(phen)Pirf3 or pirfenidone administration. NPs Ce(phen)Pirf3 improved lung function, alleviated radiation-induced pathological changes in the lung tissues, and reduced collagen deposition 16 weeks after radiation. Our results from in vivo and in vitro experiments demonstrated that NPs Ce(phen)Pirf3 increased the ROS-scavenging ability. Additionally, NPs Ce(phen)Pirf3 regulated epithelial-mesenchymal transition (EMT)-related proteins, including up-regulate E-cadherin and down-regulate N-cadherin, α-SMA, and TGF-β1 in RLE-6TN cells, which suggested NPs Ce(phen)Pirf3 may alleviate RIPF by inhibiting EMT. Finally, NPs Ce(phen)Pirf3 also inhibited the growth of thoracic tumor cells in mice. NPs Ce(phen)Pirf3 had a protective role against RIPF and antitumor effects, suggesting that they are a promising therapy for thoracic radiation-induced RIPF.

Effect of AR gene-specific knockout on the process of radiation-induced pulmonary fibrosis and its mechanism.

Numerous studies have proved that epithelial-mesenchymal transition (EMT) of lung epithelial cells is one of the important causes of radiation-induced pulmonary fibrosis (RIPF). Aldose reductase (AR) is a monomer enzyme in the polyglycolic metabolic pathway and belongs to the aldo-keno reductase protein superfamily. Our previous studies have found that AR as one of the most significantly up-regulated genes was associated with the development of bleomycin-induced PF in rats. It is not clear whether aldose reductase is related to the regulation of radiation-induced EMT and mediates RIPF. AR-knockout mice, wild-type mice and lung epithelial cells were induced by radiation to establish a RIPF animal model and EMT system, to explore whether AR is mediation to RIPF through the EMT pathway. In vivo, AR deficiency significantly alleviated radiation-induced histopathological changes, reduced collagen deposition and inhibited collagen I, matrix metalloproteinase 2 (MMP2) and Twist1 expression. In addition, AR knockout up-regulated E-cadherin expression and up-regulated α-SMA and Vimentin expression. In vitro, AR, collagen I and MMP2 expression were increased in lung epithelial cells after radiation, which was accompanied by Twist1 expression up-regulation and EMT changes evidenced by decreased E-cadherin expression and increased α-SMA and Vimentin expression. Knockdown or inhibition of AR inhibited the expressions of Twist1, MMP2 and collagen I, and reduced cell migration and reversed radiation-induced EMT. These results indicated that aldose reductase may be related to radiation-induced lung epithelial cells EMT, and that inhibition of aldose reductase might be a promising treatment for RIPF.

Autophagy gene Atg7 regulates the development of radiation-induced skin injury and fibrosis of skin.

Radiation-induced skin injury, which may progress to fibrosis, is a severe side effect of radiotherapy in patients with cancer. However, currently, there is a lack of preventive or curative treatments for this injury. Meanwhile, the mechanisms underlying this injury remain poorly understood. Here, we elucidated whether autophagy is essential for the development of radiation-induced skin injury and the potential molecular pathways and mechanisms involved. We used the myofibroblast-specific Atg7 knockout (namely, conditional Atg7 knockout) mice irradiated with a single electron beam irradiation dose of 30Gy. Vaseline-based 0.2% rapamycin ointment was topically applied once daily from the day of irradiation for 30days. On day 30 post irradiation, skin tissues were harvested for further analysis. In vitro, human foreskin fibroblast cells were treated with rapamycin (100nM) for 24h and pretreated with 3-MA (5mM) for 12h. Macroscopic skin manifestations, histological changes, and fibrosis markers at the mRNA and protein expression levels were measured. Post irradiation, the myofibroblast-specific autophagy-deficient (Atg7Flox/Flox Cre+ ) mice had increased fibrosis marker (COL1A1, CTGF, TGF-β1, and α-SMA) levels in the irradiated area and had more severe macroscopic skin manifestations than the control group (Atg7Flox/Flox Cre- ) mice. Treatment with an autophagy agonist rapamycin attenuated macroscopic skin injury scores and skin fibrosis marker levels with decreased epidermal thickness and dermal collagen deposition in Atg7Flox/Flox Cre+ mice compared with the vehicle control. Moreover, in vitro experiment results were consistent with the in vivo results. Together with studies at the molecular level, we found that these changes involved the Akt/mTOR pathway. In addition, this phenomenon might also relate to Nrf2-autophagy signaling pathway under oxidative stress conditions. In conclusion, Atg7 and autophagy-related mechanisms confer radioprotection, and reactivation of the autophagy process can be a novel therapeutic strategy to reduce and prevent the occurrence of radiodermatitis, particularly skin fibrosis, in patients with cancer.

Bone marrow mesenchymal stem cell transplantation alleviates radiation-induced myocardial fibrosis through inhibition of the TGF-β1/Smad2/3 signaling pathway in rabbit model

Backgroundand purpose: Radiotherapy (RT) is an effective treatment for most malignant chest tumors. However, radiation-induced myocardial fibrosis (RIMF) is a serious side effect of RT. Currently, due to the mechanism of RIMF has not been fully elucidated, there is a lack of effective therapeutic approach. In this study, we aimed to investigate the role and possible mechanisms of bone marrow mesenchymal stem cells (BMSCs) in the therapy of RIMF. Materials and methodsTwenty-four New Zealand white rabbits were allotted into four groups (n = 6). Rabbits in the Control group received neither irradiation nor treatment. A single dose of 20 Gy heart X-irradiation was applied to the RT group, RT + PBS group and RT + BMSCs group. Rabbits in the RT + PBS group and RT + BMSCs group were injected with 200 μL PBS or 2 × 106 cells via pericardium puncture 24 h following irradiation, respectively. Echocardiography was used to test the cardiac function; Then the heart samples were collected, and processed for histopathological, Western blot and immunohistochemistry investigations. ResultsIt was observed that BMSCs have therapeutic effect on RIMF. Compared with the Control group, inflammatory mediators, oxidative stress and apoptosis were significantly increased, meanwhile, cardiac function was remarkably decreased in the RT group and RT + PBS group. However, in the BMSCs group, BMSCs significantly improved cardiac function, decreased inflammatory mediators, oxidative stress and apoptosis. Furthermore, BMSCs remarkably reduced the expression level of TGF-β1 and the phosphorylated-Smad2/3. ConclusionsIn conclusion, our research indicates BMSCs have the potential to alleviate RIMF through TGF-β1/Smad2/3 and would be a new therapeutic approach for patients with myocardial fibrosis.

Characteristics of recurrent ventricular tachycardias after stereotactic body radiotherapy

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): Grant project AZV NU20-02-00244 from the Ministry of Health of the Czech Republic and European Union's Horizon 2020 research and innovation program under grant agreement No 945119. Introduction Stereotactic body radiotherapy (SBRT) is a novel treatment for otherwise resistant ventricular tachycardias (VTs). Different mechanisms of SBRT for VT suppression were proposed that include radiation-induced fibrosis but also SBRT-triggered increase in myocardial conduction velocities without significant fibrotic changes. Purpose The study compared the morphologies and cycle lengths (CLs) of inducible VTs during re-do catheter ablation after SBRT with VTs before SBRT. Methods We investigated patients that underwent SBRT (a single session of 25 Gy) for refractory VT and subsequent electrophysiology study / reablation for recurrences of VTs. All inducible VTs were analysed concerning morphology and CL. Results A total of 9 patients (2 women, aged 60 ± 13 years) were included. Two patients had ischemic heart disease, six patients had nonischemic cardiomyopathy, and one had a cardiac fibroma. All patients were on chronic amiodarone treatment. The mean ejection fraction of the left ventricle was 35 ± 12%. The mean planning target volume for SBRT was 39 ± 21 ml. Electrophysiology study/reablation was performed at a mean interval of 8 months (interquartile range: 2-10months) after SBRT. A total of 23 and 27 distinct VT morphologies were inducible before and after SBRT, respectively. Twelve pairs of VTs (44%) were identified that had identical morphology before and after SBRT. The mean CL of these VT pairs decreased from 399 ± 98 ms to 472 ± 74 ms (P = 0.01) after SBRT. Overall, 15/27 of all VT morphologies induced after SBRT originated from the irradiated region. Conclusions Recurrent VTs after SBRT had commonly origin in the irradiated region. In pairwise comparison, the CL of VTs has prolonged after the SBRT. This suggests that SBRT results in radiation-induced fibrosis rather than an increase in conduction velocity.

16. Single-cell RNA Sequencing in Mice Identifies Downregulation of Fra2-jun Signaling in Treatment of Radiation-induced Fibrosis by Fat Grafting

16. Single-cell RNA Sequencing in Mice Identifies Downregulation of Fra2-jun Signaling in Treatment of Radiation-induced Fibrosis by Fat Grafting

SP13. Early-Onset Metformin Regimen Inhibits Radiation-induced Fibrosis in Mice Model

SP13. Early-Onset Metformin Regimen Inhibits Radiation-induced Fibrosis in Mice Model