Radiation-induced Lung Fibrosis Research Articles

Mitochondria Energy Metabolism Depression as Novel Adjuvant to Sensitize Radiotherapy and Inhibit Radiation Induced-Pulmonary Fibrosis.

Currently, the typical combination therapy of programmed death ligand-1 (PD-L1) antibodies with radiotherapy (RT) still exhibits impaired immunogenic antitumor response in clinical due to lessened DNA damage and acquired immune tolerance via the upregulation of some other immune checkpoint inhibitors. Apart from this, such combination therapy may raise the occurrence rate of radiation-induced lung fibrosis (RIPF) due to enhanced systemic inflammation, leading to the ultimate death of cancer patients (average survival time of about 3 years). Therefore, it is newly revealed that mitochondria energy metabolism regulation can be used as a novel effective PD-L1 and transforming growth factor-β (TGF-β) dual-downregulation method. Following this, IR-TAM is prepared by conjugating mitochondria-targeted heptamethine cyanine dye IR-68 with oxidative phosphorylation (OXPHOS) inhibitor Tamoxifen (TAM), which then self-assembled with albumin (Alb) to form IR-TAM@Alb nanoparticles. By doing this, tumor-targeting IR-TAM@Alb nanoparticle effectively reversed tumor hypoxia and depressed PD-L1 and TGF-β expression to sensitize RT. Meanwhile, due to the capacity of heptamethine cyanine dye in targeting RIPF and the function of TAM in depressing TGF-β, IR-TAM@Alb also ameliorated fibrosis development induced by RT.

The Sphingolipid-Modulating Drug Opaganib Protects against Radiation-Induced Lung Inflammation and Fibrosis: Potential Uses as a Medical Countermeasure and in Cancer Radiotherapy.

Fibrosis is a chronic pathology resulting from excessive deposition of extracellular matrix components that leads to the loss of tissue function. Pulmonary fibrosis can follow a variety of diverse insults including ischemia, respiratory infection, or exposure to ionizing radiation. Consequently, treatments that attenuate the development of debilitating fibrosis are in desperate need across a range of conditions. Sphingolipid metabolism is a critical regulator of cell proliferation, apoptosis, autophagy, and pathologic inflammation, processes that are all involved in fibrosis. Opaganib (formerly ABC294640) is the first-in-class investigational drug targeting sphingolipid metabolism for the treatment of cancer and inflammatory diseases. Opaganib inhibits key enzymes in sphingolipid metabolism, including sphingosine kinase-2 and dihydroceramide desaturase, thereby reducing inflammation and promoting autophagy. Herein, we demonstrate in mouse models of lung damage following exposure to ionizing radiation that opaganib significantly improved long-term survival associated with reduced lung fibrosis, suppression of granulocyte infiltration, and reduced expression of IL-6 and TNFα at 180 days after radiation. These data further demonstrate that sphingolipid metabolism is a critical regulator of fibrogenesis, and specifically show that opaganib suppresses radiation-induced pulmonary inflammation and fibrosis. Because opaganib has demonstrated an excellent safety profile during clinical testing in other diseases (cancer and COVID-19), the present studies support additional clinical trials with this drug in patients at risk for pulmonary fibrosis.

Mechanistic model of radiotherapy-induced lung fibrosis using coupled 3D agent-based and Monte Carlo simulations

BackgroundMechanistic modelling of normal tissue toxicities is unfolding as an alternative to the phenomenological normal tissue complication probability models. The latter, currently used in the clinics, rely exclusively on limited patient data and neglect spatial dose distribution information. Among the various approaches, agent-based models are appealing as they provide the means to include patient-specific parameters and simulate long-term effects in complex systems. However, Monte Carlo tools remain the state-of-the-art for modelling radiation transport and provide measurements of the delivered dose with unmatched precision.MethodsIn this work, we develop and characterize a coupled 3D agent-based – Monte Carlo model that mechanistically simulates the onset of the radiation-induced lung fibrosis in an alveolar segment. To the best of our knowledge, this is the first such model.ResultsOur model replicates extracellular matrix patterns, radiation-induced lung fibrosis severity indexes and functional subunits survivals that show qualitative agreement with experimental studies and are consistent with our past results. Moreover, in accordance with experimental results, higher functional subunits survival and lower radiation-induced lung fibrosis severity indexes are achieved when a 5-fractions treatment is simulated. Finally, the model shows increased sensitivity to more uniform protons dose distributions with respect to more heterogeneous ones from photon irradiation.ConclusionsThis study lays thus the groundwork for further investigating the effects of different radiotherapeutic treatments on the onset of radiation-induced lung fibrosis via mechanistic modelling.

Inhibition of TGFβ1 activation prevents radiation-induced lung fibrosis.

Radiotherapy is the main treatment modality for thoracic tumours, but it may induce pulmonary fibrosis. Currently, the pathogenesis of radiation-induced pulmonary fibrosis (RIPF) is unclear, and effective treatments are lacking. Transforming growth factor beta 1 (TGFβ1) plays a central role in RIPF. We found that activated TGFβ1 had better performance for radiation pneumonitis (RP) risk prediction by detecting activated and total TGFβ1 levels in patient serum. αv integrin plays key roles in TGFβ1 activation, but the role of αv integrin-mediated TGFβ1 activation in RIPF is unclear. Here, we investigated the role of αv integrin-mediated TGFβ1 activation in RIPF and the application of the integrin antagonist cilengitide to prevent RIPF. ItgavloxP/loxP ;Pdgfrb-Cre mice were generated by conditionally knocking out Itgav in myofibroblasts, and wild-type mice were treated with cilengitide or placebo. All mice received 16Gy of radiation or underwent a sham radiation procedure. Lung fibrosis was measured by a modified Ashcroft score and microcomputed tomography (CT). An enzyme-linked immunosorbent assay (ELISA) was used to measure the serum TGFβ1 concentration, and total Smad2/3 and p-Smad2/3 levels were determined via Western blotting. Conditional Itgav knockout significantly attenuated RIPF (p<.01). Hounsfield units (HUs) in the lungs were reduced in the knockout mice compared with the control mice (p<.001). Conditional Itgav knockout decreased active TGFβ1 secretion and inhibited fibroblast p-Smad2/3 expression. Exogenous active TGFβ1, but not latent TGFβ1, reversed these reductions. Furthermore, cilengitide treatment elicited similar results and prevented RIPF. The present study revealed that conditional Itgav knockout and cilengitide treatment both significantly attenuated RIPF in mice by inhibiting αv integrin-mediated TGFβ1 activation. Activated TGFβ1 has a superior capacity in predicting radiation pneumonitis (RP) risk and plays a vital role in the development of radiation-induced pulmonary fibrosis (RIPF). Conditional knock out Itgav in myofibroblasts prevented mice from developing RIPF. Cilengitide alleviated the development of RIPF by inhibiting αv integrin-mediated TGFβ1 activation and may be used in targeted approaches for preventing RIPF.

NXC736 Attenuates Radiation-Induced Lung Fibrosis via Regulating NLRP3/IL-1β Signaling Pathway.

Radiation-induced lung fibrosis (RILF) is a common complication of radiotherapy in lung cancer. However, to date no effective treatment has been developed for this condition. NXC736 is a novel small-molecule compound that inhibits NLRP3, but its effect on RILF is unknown. NLRP3 activation is an important trigger for the development of RILF. Thus, we aimed to evaluate the therapeutic effect of NXC736 on lung fibrosis inhibition using a RILF animal model and to elucidate its molecular signaling pathway. The left lungs of mice were irradiated with a single dose of 75 Gy. We observed that NXC736 treatment inhibited collagen deposition and inflammatory cell infiltration in irradiated mouse lung tissues. The damaged lung volume, evaluated by magnetic resonance imaging, was lower in NXC736-treated mice than in irradiated mice. NXC736-treated mice exhibited significant changes in lung function parameters. NXC736 inhibited inflammasome activation by interfering with the NLRP3-ASC-cleaved caspase-1 interaction, thereby reducing the expression of IL-1β and blocking the fibrotic pathway. In addition, NXC736 treatment reduced the expression of epithelial-mesenchymal transition markers such as α-SMA, vimentin, and twist by blocking the Smad 2,3,4 signaling pathway. These data suggested that NXC736 is a potent therapeutic agent against RILF.

Paracelsian ‘Bergsucht’ – lung cancer or radiation-induced fibrosis?

Purpose Assessment of absorbed doses on organs and tissues of miners during radon exposure in the Schneeberg mines in the sixteenth century and calculation of the probability of occurrence of radiation-induced lung cancer and lung fibrosis, considering the life expectancy characteristic and the absence of smoking. Materials and methods The expected radon concentration at the Schneeberg mines has been estimated using published data. Modeling of the accumulation of radon in the working tunnels of mine workings was carried out using the RESRAD-Build 4.0, based on the radium concentration in soil and geometric parameters of the mining tunnel from the engravings in Agricola’s book. The dynamics of radionuclides in the human body were performed using the WinAct software in accordance with data from ICRP Publications 130 and 137. The values of absorbed doses on the tissues of the respiratory tract were obtained using the IDAC 2.1 program. Several models based on the epidemiology of uranium miners have been used to calculate radiation risks from radon exposure. The probability of male survival at birth and the age-specific frequency of spontaneous lung cancer not associated with radiation for miners of the sixteenth century (nonsmoking men aged 20–40 years) were estimated to properly calculate the radiation risks. Results The expected radon concentration in the Schneeberg mines was assessed in the range of 75–100 kBq m−3. The average value of the equilibrium factor was estimated as 0.49 ± 0.03. The annual exposure of miners to radon decay products was assessed as 125–165 WLM year−1. The annual values of absorbed doses to different sections of the respiratory tract were calculated, the maximum absorbed doses of α-radiation are formed on the bronchial and bronchiolar regions of the lungs (2.23 Gy year−1). The deterministic effects as radiation fibrosis of the lungs with 10 years of experience in the mines of Schneeberg have a probability of occurrence from 60 to 100%. All the models used for radiation risk assessments showed that the lifetime risk of developing lung cancer for nonsmoking Schneeberg miners is many times lower than the risk of developing deterministic radiation effects. In contrast, for the smoking cohort of miners in the nineteenth century lung cancer become the dominant cause of death. Conclusions The deterministic radiation effects of Schneeberg miners in sixteenth century, exposed to extremely high levels of radon, such as radiation pneumosclerosis or pulmonary fibrosis, are more likely than the development of radiation-induced lung cancer.

DTPA clearance test: a sensitive method for detecting radiation-induced lung fibrosis in lung cancer patients.

The aim of this study is to analyze the frequency of lung injury and the sensitivity of the diethylenetriamine penta-acetic acid (DTPA) clearance test in detecting lung injury in patients undergoing radiotherapy (RT) to the thorax. Twenty individuals scheduled for RT for lung cancer were included as the patient group. The healthy control group consisted of 20 age and gender-matched individuals who were nonsmokers with no history of comorbidities. We conducted follow-up with patients at 0-1-6 months, performing carbon monoxide diffusion test (DLCO), DTPA clearance test (excluding the first month), and high-resolution computed tomography of the thorax. The control group was followed up with DLCO between the baseline and 6th months. Ninety percent of the patient group was male, and the median age was 62 years. Seventy percent of the patients had squamous cell carcinoma and adenocarcinoma. Pneumonitis was detected in the patient group in the first month (100%) and fibrosis in the sixth month (%100) Both at the beginning and in the sixth month, the DLCO values of patients who received RT were lower than those of the control group ( P = 0.001 and P < 0.001, respectively). While DTPA clearance was similar between irradiated and non-radiated lungs at the beginning, there was a substantial decrease in the irradiated lung in the sixth month( P = 0.001). There was no significant correlation between malignancy type, RT dose, and tumor size( P > 0.05). The DTPA clearance test could be an alternative method for demonstrating radiation injury in patients receiving RT.

Cover Image

The cover image is based on the Research Article Cryptotanshinone alleviates radiation-induced lung fibrosis via modulation of gut microbiota and bile acid metabolism by Zhanhong Li et al., https://doi.org/10.1002/ptr.7926.image

Multi-Parametric Chest Magnetic Resonance Imaging for Assessment of Local Recurrence of Non-Small Cell Lung Cancer after Stereotactic Body Radiation Therapy

Radiation induced lung fibrosis after lung SBRT include dense consolidation that may be dynamic over time and thus difficult to discern from local recurrence. We intended to evaluate the use of multi-parametric MRI to distinguish stereotactic Body Radiation Therapy (SBRT)- induced pulmonary fibrosis from local recurrence (LR). In this prospective study we included SBRT treated non-small cell lung cancer (NSCLC) patients, with suspected of local recurrence by conventional imaging. The patients were consented, and underwent MR imaging: T2 weighted, diffusion weighted imaging (DWI) dynamic contrast enhancement (DCE) and 5-minute delayed T1 weighted imaging after contrast injection. On the date of the MRI the LR status was unknown. LR status was defined as recurrence within high dose-radiation field, and confirmed by biopsy and/or subsequent growth on follow-up imaging following the next 12 months. The study included 18 patients with 20 irradiated lesions. MRI was conducted at a median of 23.5 months (range 6-55 months) from SBRT. Six lesions had MRI features suspicious for local recurrence that were confirmed by either biopsy (N = 3) or by follow-up imaging (N = 3) in the 12 months following the MRI. None of the lesions thought to be benign on MRI were shown to be malignant by biopsy (N = 1) or follow-up imaging (N = 13). All confirmed recurrences showed heterogeneous enhancement and had washout curves in the suspected focus which differed from the washout of the surrounding fibrosis. Enhancement of benign lesions was either homogenous or heterogeneous, but washout curves were similar in all regions. Apparent diffusion coefficient (ADC) mean values within the recurrence lesions was 1.21 10-3mm/s2 (range 0.98-1.7) which overlapped with the ADC range of fibrotic changes (mean 1.73 10-3mm/s2, range 0.98-2.6). In this pilot prospective study of NSCLS patients treated with lung SBRT, multi-parametric chest MRI was able to correctly support suspicion of LR and correctly minimize suspicion in the benign changes. Confirmed recurrences showed heterogeneous enhancement and had washout curves in the suspected focus which differed from the washout of the surrounding fibrosis. Still, we could not identify one parameter that would be diagnostic by itself. Although lower apparent diffusion coefficient values were seen in the recurrent lesions, no absolute cut-off value could differentiate recurrent tumor from fibrosis.

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.

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.

Downregulation of β-Catenin Contributes to type II Alveolar Epithelial Stem Cell Resistance to Epithelial-Mesenchymal Transition by Lowing Lin28/let-7 Ratios in Fibrosis-Resistant Mice after Thoracic Irradiation.

Transdifferentiation of type II alveolar cells (AECII) is a major cause for radiation-induced lung fibrosis (RILF). Cell differentiation phenotype is determined by Lin28 (undifferentiated marker) and let-7 (differentiated marker) in a see-saw-pattern. Therefore, differentiation phenotype can be extrapolated based on Lin28/let-7 ratio. Lin28 is activated by β-catenin. To the best of our knowledge this study was the first to use the single primary AECII freshly isolated from irradiated lungs of fibrosis-resistant C3H/HeNHsd strain to further confirm RILF mechanism by comparing its differences in AECII phenotype status/state and cell differentiation regulators to fibrosis-prone C57BL/6j mice. Results showed that radiation pneumonitis and fibrotic lesions were seen in C3H/HeNHsd and C57BL/6j mouse strains, respectively. mRNAs of E-cadherin, EpCAM, HOPX and proSP-C (epithelial phenotype biomarkers) were significantly downregulated in single primary AECII isolated from irradiated lungs of both strains. Unlike C57BL/6j, α-SMA and Vimentin (mesenchymal phenotype biomarkers) were not upregulated in single AECII from irradiated C3H/HeNHsd. Profibrotic molecules, TGF-β1 mRNA was upregulated and β-catenin was significantly downregulated in AECII after irradiation (both P < 0.01). In contrast, transcriptions for GSK-3β, TGF-β1 and β-catenin were enhanced in isolated single AECII from irradiated C57BL/6j (P < 0.01-P < 0.001). The Lin28/let-7 ratios were much lower in single primary AECII from C3H/HeNHsd after irradiation vs. C57BL/6j. In conclusion, AECII from irradiated C3H/HeNHsd did not undergo epithelial-mesenchymal transition (EMT) and lower ratios of Lin28/let-7 contributed to AECII relatively higher differentiated status, leading to increased susceptibility to radiation stress and a failure in transdifferentiation in the absence of β-catenin. Reducing β-catenin expression and the ratios of Lin28/let-7 may be a promising strategy to prevent radiation fibrosis.

Exhaled breath condensate identifies metabolic dysregulation in patients with radiation-induced lung injury.

Radiation-induced lung injury (RILI) is a consequence of therapeutic thoracic irradiation (TR) for many cancers, and there are no FDA-approved curative strategies. Studies report that 80% of patients who undergo TR will have CT-detectable interstitial lung abnormalities, and strategies to limit the risk of RILI may make radiotherapy less effective at treating cancer. Our lab and others have reported that lung tissue from patients with idiopathic pulmonary fibrosis (IPF) exhibits metabolic defects including increased glycolysis and lactate production. In this pilot study, we hypothesized that patients with radiation-induced lung damage will exhibit distinct changes in lung metabolism that may be associated with the incidence of fibrosis. Using liquid chromatography/tandem mass spectrometry to identify metabolic compounds, we analyzed exhaled breath condensate (EBC) in subjects with CT-confirmed lung lesions after TR for lung cancer, compared with healthy subjects, smokers, and cancer patients who had not yet received TR. The lung metabolomic profile of the irradiated group was significantly different from the three nonirradiated control groups, highlighted by increased levels of lactate. Pathway enrichment analysis revealed that EBC from the case patients exhibited concurrent alterations in lipid, amino acid, and carbohydrate energy metabolism associated with the energy-producing tricarboxylic acid (TCA) cycle. Radiation-induced glycolysis and diversion of lactate to the extracellular space suggests that pyruvate, a precursor metabolite, converts to lactate rather than acetyl-CoA, which contributes to the TCA cycle. This TCA cycle deficiency may be compensated by these alternate energy sources to meet the metabolic demands of chronic wound repair. Using an "omics" approach to probe lung disease in a noninvasive manner could inform future mechanistic investigations and the development of novel therapeutic targets.NEW & NOTEWORTHY We report that exhaled breath condensate (EBC) identifies cellular metabolic dysregulation in patients with radiation-induced lung injury. In this pilot study, untargeted metabolomics revealed a striking metabolic signature in EBC from patients with radiation-induced lung fibrosis compared to patients with lung cancer, at-risk smokers, and healthy volunteers. Patients with radiation-induced fibrosis exhibit specific changes in tricarboxylic acid (TCA) cycle energy metabolism that may be required to support the increased energy demands of fibroproliferation.

Lactobacillus rhamnosus GG ameliorates radiation-induced lung fibrosis via lncRNASNHG17/PTBP1/NICD axis modulation

Radiation-induced pulmonary fibrosis (RIPF) is a major side effect experienced for patients with thoracic cancers after radiotherapy. RIPF is poor prognosis and limited therapeutic options available in clinic. Lactobacillus rhamnosus GG (LGG) is advantaged and widely used for health promotion. However. Whether LGG is applicable for prevention of RIPF and relative underlying mechanism is poorly understood. Here, we reported a unique comprehensive analysis of the impact of LGG and its’ derived lncRNA SNHG17 on radiation-induced epithelial–mesenchymal transition (EMT) in vitro and RIPF in vivo. As revealed by high-throughput sequencing, SNHG17 expression was decreased by LGG treatment in A549 cells post radiation and markedly attenuated the radiation-induced EMT progression (p < 0.01). SNHG17 overexpression correlated with poor overall survival in patients with lung cancer. Mechanistically, SNHG17 can stabilize PTBP1 expression through binding to its 3′UTR, whereas the activated PTBP1 can bind with the NICD part of Notch1 to upregulate Notch1 expression and aggravated EMT and lung fibrosis post radiation. However, SNHG17 knockdown inhibited PTBP1 and Notch1 expression and produced the opposite results. Notably, A549 cells treated with LGG also promoted cell apoptosis and increased cell G2/M arrest post radiation. Mice of RIPF treated with LGG decreased SNHG17 expression and attenuated lung fibrosis. Altogether, these data reveal that modulation of radiation-induced EMT and lung fibrosis by treatment with LGG associates with a decrease in SNHG17 expression and the inhibition of SNHG17/PTBP1/Nothch1 axis. Collectively, our results indicate that LGG exerts protective effects in RIPF and SNHG17 holds a potential marker of RIPF recovery in patients with thoracic cancers.

An Agent-Based Model of Radiation-Induced Lung Fibrosis.

Early- and late-phase radiation-induced lung injuries, namely pneumonitis and lung fibrosis (RILF), severely constrain the maximum dose and irradiated volume in thoracic radiotherapy. As the most radiosensitive targets, epithelial cells respond to radiation either by undergoing apoptosis or switching to a senescent phenotype that triggers the immune system and damages surrounding healthy cells. Unresolved inflammation stimulates mesenchymal cells' proliferation and extracellular matrix (ECM) secretion, which irreversibly stiffens the alveolar walls and leads to respiratory failure. Although a thorough understanding is lacking, RILF and idiopathic pulmonary fibrosis share multiple pathways and would mutually benefit from further insights into disease progression. Furthermore, current normal tissue complication probability (NTCP) models rely on clinical experience to set tolerance doses for organs at risk and leave aside mechanistic interpretations of the undergoing processes. To these aims, we implemented a 3D agent-based model (ABM) of an alveolar duct that simulates cell dynamics and substance diffusion following radiation injury. Emphasis was placed on cell repopulation, senescent clearance, and intra/inter-alveolar bystander senescence while tracking ECM deposition. Our ABM successfully replicates early and late fibrotic response patterns reported in the literature along with the ECM sigmoidal dose-response curve. Moreover, surrogate measures of RILF severity via a custom indicator show qualitative agreement with published fibrosis indices. Finally, our ABM provides a fully mechanistic alveolar survival curve highlighting the need to include bystander damage in lung NTCP models.

Multi-Omics Classifier of Tumor Recurrence vs. Radiation-Induced Lung Fibrosis in NSCLC Patients Treated with SBRT

<h3>Purpose/Objective(s)</h3> Differentiation between radiation-induced lung fibrosis (RILF) and tumor local recurrence (LR) remains challenging in SBRT treated NSCLC patients. We aimed to integrate spatially and time-resolved 4D radiomics with dosiomics biomarkers to develop a novel robust multi-omics classifier of LR vs RILF. <h3>Materials/Methods</h3> 210 NSCLC patients (101/48% T1-2N0M0, 109/52% T1-3N1/xM0/x) treated with SBRT (median dose 60 Gy/8 fractions) between 2009 and 2019 were identified. Image-based quantitative features were extracted from the SBRT planning and follow-up (FU) CTs at the time point of diagnosis of LR/RILF or a matched time point for CTs without LR/RILF (radiomics) and from dose distributions (dosiomics). The region of interest was the planning target volume plus a 10mm margin (PTV_+10mm). Time-dependent alterations of the radiomics features in FU CTs were integrated (delta-radiomics). To identify relevant features associated with RILF or LR, resampling (iterations = 1000) of feature selection methods were applied. An ensemble classifier comprising random forests, neural networks, and logistic regression was then trained. The area under the ROC curve (AUC) with a 70%/30% training/testing split and a 5-fold cross-validated AUC on the entire cohort were calculated for performance assessment at CT FU. <h3>Results</h3> Out of the 210, 36 patients (17%) were reported with LR and 44 (21%) with RILF. The median FU time was 19 months (range, 5-87). 20 LR and 23 RILF FU CTs, both with median time after SBRT of 15 months, were identified. 53 patients with matching clinical characteristics without LR/RILF (none), at matched FU time points (median time after SBRT: 17 months), were additionally selected, resulting in a cohort of 96 patients (20/21% LR, 23/24% RILF, 53/55% none). Discrimination of RILF versus LC using 4D radiomics features was achieved with a testing and 5-fold AUC of 0.82 [95%CI 0.79 0.86] and 0.85 [0.83 0.88]. The addition of a dosiomics feature improved performance to 0.85 [0.82 0.87] and 0.88 [0.85 0.91]. The PTV_+10mm-based classifier includes 4 textural features (2 delta-radiomics, 1 radiomics from the FU CT and 1 dosiomics). A non-significant correlation was found between the significant features and tumor volume before RT (Spearman's r <0.1, p<0.05). <h3>Conclusion</h3> Our data indicate that integrative omics by combining radiotherapy volume and dose constraints with spatially and time-resolved radiomics may provide a novel mean for better discrimination of tumor recurrence vs RILF after SBRT.

Near-infrared Nrf2 activator IR-61 dye alleviates radiation-induced lung injury

Oxidative stress injury and subsequent inflammatory response are considered to play critical roles in radiation-induced lung injury (RILI). Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor that regulates oxidative stress response and represses inflammation, but its therapeutic value in RILI remains elusive. Our previous studies have shown that the near-infrared (NIR) IR-61 dye evokes intracellular antioxidant defense by enhancing Nrf2 signaling and promoting anti-inflammatory effects. We established a model of RILI in mice exposed to whole-thoracic irradiation. The results showed that IR-61 treatment notably improved pulmonary functions by decreasing lung density and diminishing airway resistance. In addition, IR-61 significantly ameliorated radiation-induced inflammatory cell infiltration and proinflammatory cytokine (IL-1β, IL-6, and TNF-α) release, thereby mitigating inflammatory response. Furthermore, IR-61 mitigated radiation-induced lung fibrosis by decreasing the collagen deposition and the levels of fibrogenesis-related factors (collagen I, collagen III, α-SMA, and fibronectin). More importantly, IR-61 was found to accumulate in the mitochondria of macrophages in irradiated lung tissues. Therefore, the functions of IR-61 in macrophages were further studied in irradiated macrophage cell lines, MH-s and RAW 264.7 in vitro. The results indicated that IR-61 upregulated the expression of Nrf2 and heme oxygenase-1 (HO-1) and decreased the levels of reactive oxygen species (ROS) and pro-inflammatory cytokines (IL-1β and IL-6) in macrophages after radiation. In summary, our study suggests that IR-61 effectively mitigates RILI by activating Nrf2 signaling in irradiated lung tissues. In particular, Nrf2-mediated anti-inflammatory and antioxidant effects in irradiated lung tissue macrophages play critical roles in protecting against RILI.

Inhibiting the Cytosolic Phospholipase A2–Arachidonic Acid Pathway With Arachidonyl Trifluoromethyl Ketone Attenuates Radiation-Induced Lung Fibrosis

Radiation-induced lung fibrosis (RILF) is a serious late complication of thoracic radiation therapy. Inflammation is crucial in fibroblast activation and RILF, and arachidonic acid (AA) is an important inflammatory mediator released by cytosolic phospholipase A2 (cPLA2) and reduced by arachidonyl trifluoromethyl ketone (ATK)-targeting of cPLA2. Here, we aimed to investigate the roles of the cPLA2/AA pathway in RILF and assess the potential of targeting cPLA2 to prevent RILF. A computed tomography scan was used to obtain the mean lung density, and hematoxylin-eosin, Masson's trichrome, and Sirius Red staining were used to assess the histopathologic conditions in mouse models. AA levels in mouse serum and cell supernatants were tested by enzyme-linked immunosorbent assay. Fibroblast phenotype alterations were examined by a Cell Counting Kit-8, manual cell counting, and a Transwell system. The protein levels were evaluated via Western blotting, immunofluorescence, and immunohistochemistry. AA protected fibroblasts against radiation-induced growth inhibition and promoted fibroblast activation, which was characterized by enhanced α-smooth muscle actin expression and migration capacity. Radiation could activate fibroblasts by upregulating cPLA2 expression and AA production, which could be reversed by ATK. Moreover, inhibiting cPLA2 with ATK significantly attenuated collagen deposition and radiation-induced pulmonary fibrosis in mouse models. We further identified extracellular-signal regulated protein kinase (ERK) as the downstream target of the radiation-AA regulatory axis. Radiation-induced AA increased phosphorylated-ERK levels, promoting cyclinD1, cyclin-dependent kinase 6, and α-smooth muscle actin expression and contributing to fibroblast activation. Inhibiting P-ERK impaired radiation- and AA-induced fibroblast activation. The related molecular mechanisms were verified using specimens from animal models. Our findings uncover the role of the cPLA2/AA-ERK regulatory axis in response to radiation in pulmonary fibroblast activation and recognize cPLA2 as the key regulatory molecule during RILF for the first time. Targeting cPLA2 may be a promising protective strategy against RILF.

Mouse mesenchymal stem cell-derived exosomal miR-466f-3p reverses EMT process through inhibiting AKT/GSK3\u03b2 pathway via c-MET in radiation-induced lung injury

BackgroundRadiation-induced lung fibrosis (RILF) is a common complication of thoracic radiotherapy. Alveolar epithelial cells play a crucial role in lung fibrosis via epithelial-mesenchymal transition (EMT). Exosomes derived from mesenchymal stem cells own the beneficial properties to repair and regeneration of damaged tissues, however the underlying mechanisms remain poorly understood.MethodsMouse mesenchymal stem cells-derived exosomes (mMSCs-Exo) were isolated by differential centrifugation, and their protective effects were assessed in vivo and in vitro, respectively. EMT-associated proteins were measured via western blot assay and/or immunofluorescence staining. The miRNA expression was measured by microarray assay and qPCR. Furthermore, bioinformatics prediction with KEGG analysis, luciferase assay, and rescue experiments were performed to explore the molecular mechanism underlying miR-466f-3p.ResultsmMSCs-Exos were efficiently isolated ranging from 90-150 nm with high expression of exosomal markers (CD63, TSG101, and CD9). mMSCs-Exos administration efficiently relieved radiation-induced lung injury with less collagen deposition and lower levels of IL-1β and IL-6. Meanwhile, in vitro results showed mMSCs-Exos treatment obviously reversed EMT process induced by radiation. Among enriched miRNA cargo in exosomes, miR-466f-3p was primarily responsible for the protective effects via inhibition of AKT/GSK3β pathway. Our mechanistic study further demonstrated that c-MET was the direct target of miR-466f-3p, whose restoration partially abrogated mMSCs-Exo-mediated inhibition in both EMT process and AKT/GSK3β signaling activity induced by radiation.ConclusionsOur findings indicated that exosomal miR-466f-3p derived from mMSCs may possess anti-fibrotic properties and prevent radiation-induced EMT through inhibition of AKT/GSK3β via c-MET, providing a promising therapeutic modality for radiation-induced lung fibrosis.

Radiation-induced lung injury - what do we know in the era of modern radiotherapy?

Radiation-induced lung injury (RILI) that is usually divided into an early radiation-induced pneumonitis (RIP) and late chronic radiation-induced lung fibrosis (RILF) remains a clinically significant toxicity in radiation oncology. Thus, a thorough understanding of underlying molecular mechanisms and risk factors is crucial. This review, focused on patients treated with modern radiotherapy (RT) techniques, describes the different clinical presentations of RIP, with most typical imaging findings and usefulness of pulmonary function tests and laboratory assessment in differential diagnosis. The most critical patient- and treatment-related predictors are summarized and discussed — age and sex, comorbidities, tumour characteristics, concomitant treatment, and RT-plan parameters. The conventional grading scales and contemporary approach to quantitative assessment (radiomics, CT density changes) is described as well as treatment methods.