Radiation and the lung: a reevaluation of the mechanisms mediating pulmonary injury

Predictive factors for severe radiation-induced lung injury in patients with lung cancer and coexisting interstitial lung disease

BACKGROUND AND PURPOSE

This study aimed to investigate the predictive factors of severe radiation-induced lung injury (RILI) in patients with lung cancer and coexisting interstitial lung disease (ILD) undergoing conventionally fractionated thoracic radiotherapy.

MATERIALS AND METHODS

The study includes consecutive patients treated with thoracic radiotherapy for lung cancer at two tertiary centers between 2010 and 2021. RILI severity was graded using the National Cancer Institute Common Terminology Criteria version 5.0, with severe RILI defined as toxicity grade ≥4, and symptomatic RILI as grade ≥2. The absolute neutrophil count (ANC), absolute lymphocyte count (ALC), and C-reactive protein were collected within 4 weeks before starting radiotherapy. Neutrophil-lymphocyte ratios (NLR) were calculated as ANC/ALC. The median follow-up was 9 (range, 6-114) months.

RESULTS

Among 54 patients, 22 (40.7 %) had severe RILI. On multivariate logistic regression analysis, high pretreatment ANC (p = 0.030, OR = 4.313), pretreatment NLR (p = 0.007, OR = 5.784), and ILD severity (p = 0.027, OR = 2.416) were significant predictors of severe RILI. Dosimetric factors were not associated with severe RP. Overall survival was significantly worse for patients with severe RILI than those without, with 1-year cumulative overall survival rates of 7.4 % and 62.8 %, respectively.

CONCLUSION

Pretreatment blood NLR, ANC, and ILD severity were associated with severe RILI. Overall survival was dismal for patients with severe RILI.

Cytokine, chemokine alterations and immune cell infiltration in Radiation-induced lung injury: Implications for prevention and management

Radiation therapy is one of the primary treatments for thoracic malignancies, with radiation-induced lung injury (RILI) emerging as its most prevalent complication. RILI encompasses early-stage radiation pneumonitis (RP) and the subsequent development of radiation pulmonary fibrosis (RPF). During radiation treatment, not only are tumor cells targeted, but normal tissue cells, including alveolar epithelial cells and vascular endothelial cells, also sustain damage. Within the lungs, ionizing radiation boosts the intracellular levels of reactive oxygen species across various cell types. This elevation precipitates the release of cytokines and chemokines, coupled with the infiltration of inflammatory cells, culminating in the onset of RP. This pulmonary inflammatory response can persist, spanning a duration from several months to years, ultimately progressing to RPF. This review aims to explore the alterations in cytokine and chemokine release and the influx of immune cells post-ionizing radiation exposure in the lungs, offering insights for the prevention and management of RILI.

Quantum Biology and the Potential Role of Entanglement and Tunneling in Non-Targeted Effects of Ionizing Radiation: A Review and Proposed Model

It is well established that cells, tissues, and organisms exposed to low doses of ionizing radiation can induce effects in non-irradiated neighbors (non-targeted effects or NTE), but the mechanisms remain unclear. This is especially true of the initial steps leading to the release of signaling molecules contained in exosomes. Voltage-gated ion channels, photon emissions, and calcium fluxes are all involved but the precise sequence of events is not yet known. We identified what may be a quantum entanglement type of effect and this prompted us to consider whether aspects of quantum biology such as tunneling and entanglement may underlie the initial events leading to NTE. We review the field where it may be relevant to ionizing radiation processes. These include NTE, low-dose hyper-radiosensitivity, hormesis, and the adaptive response. Finally, we present a possible quantum biological-based model for NTE.

Effect of angiotensin II on irradiation exacerbated decompression sickness

In some complicated situations, decompression sickness (DCS) combined with other injuries, such as irradiation, will seriously endanger life safety. However, it is still unclear whether irradiation will increase the incidence of DCS. This study was designed to investigate the damage effects of irradiation on decompression injury and the underlying mechanism. Sprague-Dawley rats were exposed to irradiation followed by hyperbaric decompressing and the mortality and decompression symptoms were observed. Lung tissue and bronchoalveolar lavage fluid were collected to detect the lung lesion, inflammation response, activity of the angiotensin system, oxidative stress, and relative signal pathway by multiple methods, including Q-PCR, western blot, and ELISA. As a result, pre-exposure to radiation significantly exacerbated disease outcomes and lung lesions of DCS. Mechanically, the up-regulation of angiotensin-converting enzyme expression and angiotensin II levels was responsible for the exacerbated DCS and lung lesions caused by predisposing irradiation exposure. Oxidative stress and PI3K/AKT signal pathway activation in pulmonary tissue were enhanced after irradiation plus decompression treatment. In conclusion, our results suggested that irradiation could exacerbate lung injury and the outcomes of DCS by activating the angiotensin system, which included eliciting oxidative stress and activation of the PI3K/AKT signal pathway.

An interactive murine single-cell atlas of the lung responses to radiation injury

Radiation Induced Lung Injury (RILI) is one of the main limiting factors of thorax irradiation, which can induce acute pneumonitis as well as pulmonary fibrosis, the latter being a life-threatening condition. The order of cellular and molecular events in the progression towards fibrosis is key to the physiopathogenesis of the disease, yet their coordination in space and time remains largely unexplored. Here, we present an interactive murine single cell atlas of the lung response to irradiation, generated from C57BL6/J female mice. This tool opens the door for exploration of the spatio-temporal dynamics of the mechanisms that lead to radiation-induced pulmonary fibrosis. It depicts with unprecedented detail cell type-specific radiation-induced responses associated with either lung regeneration or the failure thereof. A better understanding of the mechanisms leading to lung fibrosis will help finding new therapeutic options that could improve patients' quality of life.

Clinical Radiobiology for Radiation Oncology

This chapter is focused on radiobiological aspects at the molecular, cellular, and tissue level which are relevant for the clinical use of ionizing radiation (IR) in cancer therapy. For radiation oncology, it is critical to find a balance, i.e., the therapeutic window, between the probability of tumor control and the probability of side effects caused by radiation injury to the healthy tissues and organs. An overview is given about modern precision radiotherapy (RT) techniques, which allow optimal sparing of healthy tissues. Biological factors determining the width of the therapeutic window are explained. The role of the six typical radiobiological phenomena determining the response of both malignant and normal tissues in the clinic, the 6R’s, which are Reoxygenation, Redistribution, Repopulation, Repair, Radiosensitivity, and Reactivation of the immune system, is discussed. Information is provided on tumor characteristics, for example, tumor type, growth kinetics, hypoxia, aberrant molecular signaling pathways, cancer stem cells and their impact on the response to RT. The role of the tumor microenvironment and microbiota is described and the effects of radiation on the immune system including the abscopal effect phenomenon are outlined. A summary is given on tumor diagnosis, response prediction via biomarkers, genetics, and radiomics, and ways to selectively enhance the RT response in tumors. Furthermore, we describe acute and late normal tissue reactions following exposure to radiation: cellular aspects, tissue kinetics, latency periods, permanent or transient injury, and histopathology. Details are also given on the differential effect on tumor and late responding healthy tissues following fractionated and low dose rate irradiation as well as the effect of whole-body exposure.

Using inflammatory indexes and clinical parameters to predict radiation esophagitis in patients with small-cell lung cancer undergoing chemoradiotherapy

OBJECTIVE

Radiation esophagitis (RE) is a common adverse effect in small cell lung cancer (SCLC) patients undergoing thoracic radiotherapy. We aim to develop a novel nomogram to predict the acute severe RE (grade≥2) receiving chemoradiation in SCLC patients.

MATERIALS AND METHODS

the risk factors were analyzed by logistic regression, and a nomogram was constructed based on multivariate analysis results. The clinical value of the model was evaluated using the area under the receiver operating curve (ROC) curve (AUC), calibration curves, and decision curve analysis (DCA). The correlations of inflammation indexes were assessed using Spearman correlation analysis.

RESULTS

Eighty-four of 187 patients (44.9%) developed grade ≥2 RE. Univariate analysis indicated that concurrent chemoradiotherapy (CCRT, p < 0.001), chemotherapy cycle (p = 0.097), system inflammation response index (SIRI, p = 0.048), prognostic-nutrition index (PNI, p = 0.073), platelets-lymphocyte radio (PLR, p = 0.026), platelets-albumin ratio (PAR, p = 0.029) were potential predictors of RE. In multivariate analysis, CCRT [p < 0.001; OR, 3.380; 95% CI, 1.767-6.465], SIRI (p = 0.047; OR, 0.436; 95% CI, 0.192-0.989), and PAR (p = 0.036; OR, 2.907; 95% CI, 1.071-7.891) were independent predictors of grade ≥2 RE. The AUC of nomogram was 0.702 (95% CI, 0.626-0.778), which was greater than each independent predictor (CCRT: 0.645; SIRI: 0.558; PAR: 0.559). Calibration curves showed high coherence between the predicted and actual observation RE, and DCA displayed satisfactory clinical utility.

CONCLUSION

In this study, CCRT, SIRI, and PAR were independent predictors for RE (grade ≥2) in patients with SCLC receiving chemoradiotherapy. We developed and validated a predictive model through these factors. The developed nomogram with superior prediction ability can be used as a quantitative model to predict RE.

Alveolar type 2 epithelial cell senescence and radiation-induced pulmonary fibrosis

Radiation-induced pulmonary fibrosis (RIPF) is a chronic and progressive respiratory tract disease characterized by collagen deposition. The pathogenesis of RIPF is still unclear. Type 2 alveolar epithelial cells (AT2), the essential cells that maintain the structure and function of lung tissue, are crucial for developing pulmonary fibrosis. Recent studies indicate the critical role of AT2 cell senescence during the onset and progression of RIPF. In addition, clearance of senescent AT2 cells and treatment with senolytic drugs efficiently improve lung function and radiation-induced pulmonary fibrosis symptoms. These findings indicate that AT2 cell senescence has the potential to contribute significantly to the innovative treatment of fibrotic lung disorders. This review summarizes the current knowledge from basic and clinical research about the mechanism and functions of AT2 cell senescence in RIPF and points to the prospects for clinical treatment by targeting senescent AT2 cells.

Predictive role of circulatory levels of high-mobility group box 1 for radiation pneumonitis in patients with non-small cell lung cancer treated with definitive thoracic radiotherapy

BACKGROUND

High-mobility group box 1 (HMGB1) is a pro-inflammatory protein associated with the pathophysiology of lung injury and lung tumorigenesis. Here, we investigated the predictive potential of serum HMGB1 levels for radiation pneumonitis in patients with lung cancer.

METHODS

This was a retrospective biomarker study of 73 patients with non-small cell lung cancer treated with definitive thoracic radiotherapy between August 2007 and January 2021. We measured HMGB1 levels in serum stored before treatment, and analyzed its association with the development of grade ≥ 2 or grade ≥ 3 radiation pneumonitis. Additionally, baseline characteristics affecting HMGB1 levels were identified.

RESULTS

Of the 73 patients, 21 (28.8%) and 6 (8.2%) patients experienced grade 2 and ≥ 3 radiation pneumonitis, respectively. Univariate and multivariate logistic regression analyses revealed that higher baseline levels of serum HMGB1 were significantly associated with a higher risk of grade ≥ 3, but not grade ≥ 2, radiation pneumonitis. The incidence of grade ≥ 3 radiation pneumonitis was higher in patients with HMGB1 levels ≥ 6.2 ng/mL than in those with levels < 6.2 ng/mL (25.0% vs. 3.5%, p = 0.019). Baseline serum levels of HMGB1 were independently and positively associated with gross tumor volume.

CONCLUSIONS

Higher serum HMGB1 levels were significantly associated with the risk of grade ≥ 3 radiation pneumonitis in patients with lung cancer, and therefore, HMGB1 could be a potential blood biomarker for predicting severe radiation pneumonitis.

Mechanistic Understanding of Lung Inflammation: Recent Advances and Emerging Techniques

Acute respiratory distress syndrome (ARDS) is a life-threatening lung injury characterized by an acute inflammatory response in the lung parenchyma. Hence, it is considered as the most appropriate clinical syndrome to study pathogenic mechanisms of lung inflammation. ARDS is associated with increased morbidity and mortality in the intensive care unit (ICU), while no effective pharmacological treatment exists. It is very important therefore to fully characterize the underlying pathobiology and the related mechanisms, in order to develop novel therapeutic approaches. In vivo and in vitro models are important pre-clinical tools in biological and medical research in the mechanistic and pathological understanding of the majority of diseases. In this review, we will present data from selected experimental models of lung injury/acute lung inflammation, which have been based on clinical disorders that can lead to the development of ARDS and related inflammatory lung processes in humans, including ventilation-induced lung injury (VILI), sepsis, ischemia/reperfusion, smoke, acid aspiration, radiation, transfusion-related acute lung injury (TRALI), influenza, Streptococcus (S.) pneumoniae and coronaviruses infection. Data from the corresponding clinical conditions will also be presented. The mechanisms related to lung inflammation that will be covered are oxidative stress, neutrophil extracellular traps, mitogen-activated protein kinase (MAPK) pathways, surfactant, and water and ion channels. Finally, we will present a brief overview of emerging techniques in the field of omics research that have been applied to ARDS research, encompassing genomics, transcriptomics, proteomics, and metabolomics, which may recognize factors to help stratify ICU patients at risk, predict their prognosis, and possibly, serve as more specific therapeutic targets.

Induction of Accelerated Aging in a Mouse Model

With the global increase of the elderly population, the improvement of the treatment for various aging-related diseases and the extension of a healthy lifespan have become some of the most important current medical issues. In order to understand the developmental mechanisms of aging and aging-related disorders, animal models are essential to conduct relevant studies. Among them, mice have become one of the most prevalently used model animals for aging-related studies due to their high similarity to humans in terms of genetic background and physiological structure, as well as their short lifespan and ease of reproduction. This review will discuss some of the common and emerging mouse models of accelerated aging and related chronic diseases in recent years, with the aim of serving as a reference for future application in fundamental and translational research.

Quantitative Analysis of Radiation-Associated Parenchymal Lung Change

We present a novel classification system of the parenchymal features of radiation-induced lung damage (RILD). We developed a deep learning network to automate the delineation of five classes of parenchymal textures. We quantify the volumetric change in classes after radiotherapy in order to allow detailed, quantitative descriptions of the evolution of lung parenchyma up to 24 months after RT, and correlate these with radiotherapy dose and respiratory outcomes. Diagnostic CTs were available pre-RT, and at 3, 6, 12 and 24 months post-RT, for 46 subjects enrolled in a clinical trial of chemoradiotherapy for non-small cell lung cancer. All 230 CT scans were segmented using our network. The five parenchymal classes showed distinct temporal patterns. Moderate correlation was seen between change in tissue class volume and clinical and dosimetric parameters, e.g., the Pearson correlation coefficient was ≤0.49 between V30 and change in Class 2, and was 0.39 between change in Class 1 and decline in FVC. The effect of the local dose on tissue class revealed a strong dose-dependent relationship. Respiratory function measured by spirometry and MRC dyspnoea scores after radiotherapy correlated with the measured radiological RILD. We demonstrate the potential of using our approach to analyse and understand the morphological and functional evolution of RILD in greater detail than previously possible.

Prolonged Inhalation Exposure to Coal Dust on Irradiated Rats and Consequences

The purposes of this study were to research immune system changes and liver and lung tissues in irradiated rats after prolonged exposure to coal dust. A study was carried out on 30 male Wistar rats that were divided into 3 groups: group I, intact animals; group II, exposure to coal dust and 0.2 Gy γ-irradiation; and group III, combined exposure to 6 Gy γ-irradiation and coal dust. The combination of a low and sublethal dose of γ-irradiation with coal dust leads to a significant change in immunity at the remote period. Particularly, the increase in radioactivity at the combined effect causes weakening of phagocytosis, and reduction in T lymphocytes by a factor of 2, immunoglobulin imbalance, and cytokine dysfunction develop secondary immune failure. During prolonged inhalation with coal dust of irradiated animals with the dose of 0.2 Gy, fibrosis and perivascular sclerosis of the bronchial wall of the lungs are formed, and perivascular fibrosis is formed in the liver. The increase in exposure dose up to 6 Gy in combination with coal, in the distant period, caused pulmonary hypertension amid hypertrophy of light arterial vessels and fibrous changes in arteriole, and destructive changes and collection necrosis develop in liver parenchyma. In the case of dust radiation synergy, the increase in doses leads to a significant immune deficiency, which occurs according to the “dose effect” principle; increases damage to animal tissues; and leads to liver tissue necrosis, pulmonary fibrosis, and pulmonary hypertension.

Involvement of eNAMPT/TLR4 signaling in murine radiation pneumonitis: protection by eNAMPT neutralization

Therapeutic strategies to prevent or reduce the severity of radiation pneumonitis are a serious unmet need. We evaluated extracellular nicotinamide phosphoribosyltransferase (eNAMPT), a damage-associated molecular pattern protein (DAMP) and Toll-Like Receptor 4 (TLR4) ligand, as a therapeutic target in murine radiation pneumonitis. Radiation-induced murine and human NAMPT expression was assessed in vitro, in tissues (IHC, biochemistry, imaging), and in plasma. Wild type C57Bl6 mice (WT) and Nampt+/- heterozygous mice were exposed to 20Gy whole thoracic lung irradiation (WTLI) with or without weekly IP injection of IgG1 (control) or an eNAMPT-neutralizing polyclonal (pAb) or monoclonal antibody (mAb). BAL protein/cells and H&E staining were used to generate a WTLI severity score. Differentially-expressed genes (DEGs)/pathways were identified by RNA sequencing and bioinformatic analyses. Radiation exposure increases in vitro NAMPT expression in lung epithelium (NAMPT promoter activity) and NAMPT lung tissue expression in WTLI-exposed mice. Nampt+/- mice and eNAMPT pAb/mAb-treated mice exhibited significant histologic attenuation of WTLI-mediated lung injury with reduced levels of BAL protein and cells, and plasma levels of eNAMPT, IL-6,  and IL-1β. Genomic and biochemical studies from WTLI-exposed lung tissues highlighted dysregulation of NFkB/cytokine and MAP kinase signaling pathways which were rectified by eNAMPT mAb treatment. The eNAMPT/TLR4 pathway is essentially involved in radiation pathobiology with eNAMPT neutralization an effective therapeutic strategy to reduce the severity of radiation pneumonitis.

High-dose thoracic radiation therapy for non-small cell lung cancer: a novel grading scale of radiation-induced lung injury for symptomatic radiation pneumonitis

Background

Symptomatic radiation pneumonitis (RP) may be a serious complication after thoracic radiation therapy (RT) for non-small cell lung cancer (NSCLC). This prospective observational study sought to evaluate the utility of a novel radiation-induced lung injury (RILI) grading scale (RGS) for the prediction of RP.

Materials and methods

Data of 41 patients with NSCLC treated with thoracic RT of 60–66 Gy were analysed. CT scans were scheduled before RT, one month post-RT, and every three months thereafter for one year. Symptomatic RP was defined as Common Terminology Criteria for Adverse Events grade ≥ 2. RGS grading ranged from 0 to 3. The inter-observer variability of the RGS was assessed by four senior radiologists. CT scans performed 28 ± 10 days after RT were used to analyse the predictive value of the RGS. The change in the RGS severity was correlated to dosimetric parameters.

Results

The CT obtained one month post-RT showed RILI in 36 (88%) of patients (RGS grade 0 [5 patients], 1 [25 patients], 2 [6 patients], and 3 [5 patients]). The inter-observer agreement of the RGS grading was high (Kendall’s W coefficient of concordance = 0.80, p < 0.01). Patients with RGS grades 2–3 had a significantly higher risk for development of RP (relative risk (RR): 2.4, 95% CI 1.6–3.7, p < 0.01) and RP symptoms within 8 weeks after RT (RR: 4.8, 95% CI 1.3–17.6, p < 0.01) compared to RGS grades 0–1. The specificity and sensitivity of the RGS grades 2–3 in predicting symptomatic RP was 100% (95% CI 80.5–100%) and 45.4% (95% CI 24.4–67.8%), respectively. Increase in RGS severity correlated to mean lung dose and the percentage of the total lung volume receiving 5 Gy.

Conclusions

The RGS is a simple radiologic tool associated with symptomatic RP. A validation study is warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13014-021-01857-8.

A Likely Role for a Novel Cell Therapeutic Target of Transforming Growth Factor-β1 on Radiation Pneumonitis in Lung and Nasopharyngeal Cancer Patients

The association between the polymorphism of transforming growth factor (TGF)-β1 and risk of radiation pneumonitis has been extensively investigated; however, conclusive results were unavailable. Eligible studies were identified from the database of Medline, Web of Science, EMBASE, and CNKI (China Knowledge Resource Integrated Database) up to September 2019. The odds ratio (OR) and 95% confidence interval (95% CI) were used to assess the strength of the relationship. The results showed that there were associations between TGF 869 T/C (rs1982073) and risks of radiation pneumonitis. Subgroup analyses showed that TGF 869 T/C was associated with risk of radiation pneumonitis in Caucasians (OR [95% CI]: 0.45 [0.31 to 0.67] for C carriers vs. TT). In addition, subgroup analyses also suggested that the C allele was associated with decreased risks of radiation pneumonitis among hospital-based case–control studies (0.56 [0.39 to 0.82] for C carriers vs. TT). Meanwhile, C allele was also suggested to be associated with decreased risk of radiation pneumonitis among PCC (0.60 [0.38 to 0.96] for C carriers vs. TT). Especially, C allele was also found to be associated with decreased risk of radiation pneumonitis from the participants with lung cancer (0.57 [0.37 to 0.90] for C carriers vs. TT). Our meta-analysis shows that T allele in TGF 869 T/C is significantly associated with the increased risk of radiation pneumonitis, especially for Caucasians, and for the participants with lung cancer.

Risk factor of pneumonitis on dose-volume relationship for chemoradiotherapy with durvalumab: Multi-institutional research in Japan

Objectives

To estimate appropriate dose-volume parameters for avoidance of pneumonitis in use of chemoradiotherapy and durvalumab for treatment of lung cancer.

Materials and methods

Patients with non-small cell lung cancer treated with concurrent chemoradiotherapy followed by durvalumab at 9 centers were enrolled in the study. Three-dimensional radiotherapy, intensity modulated radiotherapy, and proton beam therapy were used. The frequency and severity of pneumonitis and the dose-volume relationship for normal lung were evaluated. Univariable and multivariable analyses were conducted to identify risk factors. A covariate adjusted hazard ratio was then estimated for the percentages of normal lung volume irradiated at ≥ X Gy (Vx) (X = 5-40) and lung volume non-irradiated at ≥ X Gy (X = 5-40), with the covariates selected in the variable selection. Cumulative incidence functions and covariate adjusted hazard ratios were also estimated for dichotomized variables, with estimated cut-off points.

Results

A total of 91 patients were enrolled in the study. The median time from the start of radiotherapy to development of pneumonitis was 4.1 months. Pneumonitis was observed in 80 patients (88%), including grade 2 or severe pneumonitis in 31 (34%) and ≥ grade 3 pneumonitis in 11 (12%). Pneumonitis was inside the irradiation field in 73 of the 80 patients (91%). The selected factors for ≥ grade 2 pneumonitis were V₂₀, and primary site (upper lobe) in multivariable analysis. The cut off value of V₂₀ was 18.99%, and there was a significant difference between V₂₀ of < 18.77 and ≥ 18.77.

Conclusion

Though there are some limitation of this study, the basic concept of concurrent chemoradiotherapy with an emphasis on V₂₀ remains unchanged in use of durvalumab. However, we recommend reduction of V₂₀ to as small a value as possible in use of this therapy.

Regional and organ-level responses to local lung irradiation in sheep

Lung is a dose-limiting organ in radiotherapy. This may limit tumour control when effort is made in planning to limit the likelihood of radiation-induced lung injury (RILI). Understanding the factors that dictate susceptibility to radiation-induced pulmonary fibrosis will aid in the prevention and management of RILI, and may lead to more effective personalized radiotherapy treatment. As the interaction of regional and organ-level responses may shape the chronic consequences of RILI, we sought to characterise both aspects of the response in an ovine model. A defined volume of left pulmonary parenchyma was prescribed 5 fractions of 6 Gy within 14 days while the contralateral lung dose was constrained. Radiographic changes via computed tomography (CT) were documented to define differences in radio-exposed lung relative to non-exposed lung at d21, d63 and d171 (n = 2), and at d21, d147 and d227 (n = 2). Gross and histologic lung changes were evaluated in samples derived at necropsy examination to define the chronic pulmonary response to radiation. Irradiated lung demonstrated reduced radio-density and increased homogeneity as evidenced from texture based radiomic feature analysis, relative to the control lung. At necropsy, the radiation field was readily defined by pallor on the pleural surface, which was also evident on the cut surface of fixed lung specimens. The degree and homogeneity of pallor reflected the sparse presence of erythrocytes in alveolar septal capillaries of radiation-exposed lung. These changes contrasted with dilated and congested microvasculature in the contralateral control lung. Referencing data to measurements made in control lung volumes of sheep experiencing acute RILI indicated that interstitial collagen continues to deposit in the radio-exposed lung field. Overall lung vascularity increased during the chronic response, as evidenced by increased expression of endothelial cell marker (CD31); however, vascularity was consistently decreased in irradiated lung and was negatively correlated with lung collagen. Other organ-level responses included increased expression of alpha smooth muscle actin (ASMA), increased numbers of proliferating cells (Ki67 positive), and cells expressing the dendritic cell-lysosomal associated membrane protein (DC-LAMP) antigen. The chronic response to RILI in this model is effected at both the whole organ and local lung level. Whilst the long-term consequences of exposure to radiation involved the continued deposition of collagen in the radiation field, organ-level responses also included increased vascularization and increased expression of ASMA, Ki67 and DC-LAMP. Interrupting the interplay between these aspects may influence susceptibility to pulmonary fibrosis after radiotherapy. We advocate for the importance of large animal model systems in pursuing these opportunities to target local, organ-level and systemic mechanisms in parallel within the same subject over time.

Risk factors for radiation pneumonitis in lung cancer patients with subclinical interstitial lung disease after thoracic radiation therapy

Background

Previous studies have found that patients with subclinical interstitial lung disease (ILD) are highly susceptible to developing radiation pneumonitis (RP) after thoracic radiation therapy. In the present study we aimed to evaluate the incidence of and risk factors for RP after thoracic intensity-modulated radiation therapy in lung cancer patients with subclinical ILD.

Methods

We retrospectively analyzed data from lung cancer patients with subclinical ILD who were treated with thoracic intensity-modulated radiation therapy with a prescribed dose of ≥ 50 Gy in our institution between January 2016 and December 2017.

Results

Eighty-seven consecutive lung cancer patients with subclinical ILD were selected for the study. The median follow-up period was 14.0 months. The cumulative incidence of grades ≥ 2 and ≥ 3 RP at one year was 51.0% and 20.9%, respectively. In the multivariate analysis, a mean lung dose ≥ 12 Gy was a significant risk factor for grade ≥ 2 RP (p = 0.049). Chemotherapy with gemcitabine in the past, V5 ≥ 50%, and subclinical ILD involving ≥ 25% of the lung volume were significantly associated with grade ≥ 3 RP (p = 0.046, p = 0.040, and p = 0.024, respectively).

Conclusion

Mean lung dose is a significant risk factor for grade ≥ 2 RP. Lung cancer patients who have received chemotherapy with gemcitabine in the past, V5 ≥ 50%, and those with subclinical ILD involving ≥ 25% of lung volume have an increased risk of grade ≥ 3 RP in lung cancer patients with subclinical ILD.

Biology of Radiation-Induced Lung Injury

Radiation-induced lung injury encompasses radiation-induced pneumonitis, inflammation of the lung which may manifest as a dose-limiting acute or subacute toxicity, and radiation-induced lung fibrosis, a late effect of lung exposure to radiation. This review aims to highlight developments in molecular radiation biology of radiation-induced lung injury and their implications in clinical practice.

Captopril reduces lung inflammation and accelerated senescence in response to thoracic radiation in mice

The lung is sensitive to radiation and exhibits several phases of injury, with an initial phase of radiation-induced pneumonitis followed by delayed and irreversible fibrosis. The angiotensin-converting enzyme inhibitor captopril has been demonstrated to mitigate radiation lung injury and to improve survival in animal models of thoracic irradiation, but the mechanism remains poorly understood. Here we investigated the effect of captopril on early inflammatory events in the lung in female CBA/J mice exposed to thoracic X-ray irradiation of 17-17.9 Gy (0.5-0.745 Gy min-1). For whole-body + thoracic irradiation, mice were exposed to 7.5 Gy (0.6 Gy min-1) total-body 60Co irradiation and 9.5 Gy thoracic irradiation. Captopril was administered orally (110 mg kg-1 day-1) in the drinking water, initiated 4 h through to150 days post-irradiation. Captopril treatment increased survival from thoracic irradiation to 75% at 150 days compared with 0% survival in vehicle-treated animals. Survival was characterized by a significant decrease in radiation-induced pneumonitis and fibrosis. Investigation of early inflammatory events showed that captopril significantly attenuated macrophage accumulation and decreased the synthesis of radiation-induced interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) pro-inflammatory cytokines in the lungs of irradiated mice. Suppression of IL-1β and TNF-α correlated with an increase of the anti-inflammatory cytokine IL-10 in the spleen with captopril treatment. We also found that captopril decreased markers for radiation-induced accelerated senescence in the lung tissue. Our data suggest that suppression of inflammation and senescence markers, combined with an increase of anti-inflammatory factors, are a part of the mechanism for captopril-induced survival in thoracic irradiated mice.

Scarred Lung. An Update on Radiation-Induced Pulmonary Fibrosis

Radiation-induced pulmonary fibrosis is a common severe long-time complication of radiation therapy for tumors of the thorax. Current therapeutic options used in the clinic include only supportive managements strategies, such as anti-inflammatory treatment using steroids, their efficacy, however, is far from being satisfactory. Recent studies have demonstrated that the development of lung fibrosis is a dynamic and complex process, involving the release of reactive oxygen species, activation of Toll-like receptors, recruitment of inflammatory cells, excessive production of nitric oxide and production of collagen by activated myofibroblasts. In this review we summarized the current state of knowledge on the pathophysiological processes leading to the development of lung fibrosis and we also discussed the possible treatment options.

Stereotactic body radiotherapy for early stage non-small cell lung cancer in patients with subclinical interstitial lung disease

Background

For lung cancer patients with subclinical (untreated and asymptomatic) interstitial lung disease (ILD), there is a lack of relatively safe and effective treatment. Stereotactic body radiation therapy (SBRT) can achieve a high level of tumor control with low toxicity in early-stage non-small cell lung cancer (NSCLC). This study aimed to evaluate the efficacy and toxicity of early stage NSCLC patients with subclinical ILD receiving SBRT.

Methods

A total of 109 early stage NSCLC patients receiving SBRT treatment between December 2011 and August 2016 were reviewed in our institutions; patients with clinical ILD were excluded. The median dose of SBRT was 50 Gy in 5 fractions. The median biologically effective dose (BED; α/β=10) was 100 Gy (range, 72–119 Gy). An experienced radiation oncologist and an experienced radiologist reviewed the presence of subclinical ILD in the CT findings before SBRT. The relationships among the efficacy, radiation-induced lung injury (RILI) and subclinical ILD were explored.

Results

In all, 38 (34.9%) of 109 patients were recognized with subclinical ILD before SBRT, 48 (44.0%) of 109 patients were recognized with grade 2–5 RILI after SBRT, and 18 (47.4%) of 38 patients with subclinical ILD were observed with grade 2–5 RILI. Subclinical ILD was not a significant factor of grade 2–5 RILI (P=0.608); however, 3 patients had extensive RILI, and they all suffered from subclinical ILD. Dosimetric factor of the lungs, such as mean lung dose (MLD) was significantly related with Grade 2–5 RILI in patients with subclinical ILD (P=0.042). The progression-free survival (PFS) rates at 3 years in the subclinical ILD patients and those without ILD were 61.6% and 66.8%, respectively (P=0.266).

Conclusions

Subclinical ILD was not a significant factor for RILI or PFS in early stage NSCLC patients receiving SBRT; however, patients with subclinical ILD receiving SBRT may experience uncommon extensive RILI.

The Predictive Value of MLR for Radiation Pneumonia During Radiotherapy of Thoracic Tumor Patients

Purpose

To evaluate the predictive value of blood lymphocyte, monocyte to lymphocyte ratio (MLR), and neutrophil to lymphocyte ratio (NLR) for radiation pneumonia (RP) in patients with thoracic tumors receiving radiotherapy.

Patients and Methods

The clinical data of 65 patients with thoracic tumor (esophageal cancer, lung cancer) treated by radiotherapy in our hospital were retrospectively analyzed. Patients were divided into the RP group and the non-RP group according to the Common Terminology Criteria for Adverse Events (CTCAE 5.0). Data on blood cell counts, including lymphocytes, monocytes, and neutrophils, were collected before (0 weeks) and after 1, 2, and 4 weeks of radiotherapy.

Results

Of the 65 patients enrolled, 27 developed radiation pneumonia and 38 did not. Patients’ clinical factors, including age, TNM stage, tumor type, underlying lung disease, and history of smoking, had no correlation with RP. ANOVA of repeated measurement data showed that the changes of MLR in the group with RP during radiotherapy were significantly different from those in the non-RP group (P<0.05). The RP prediction model based on the identified risk factors was established using receiver operator characteristic curves. The results showed that the area under the curve for the monocyte to lymphocyte ratio was 0.755 (95% CI, 0.63–0.87, P=0.000), and the best cutoff point for MLR was 0.426.

Conclusion

MLR could predict radiation pneumonia in patients with thoracic tumor radiotherapy and achieve early monitoring, early prevention, and treatment.

Bronchoalveolar lavage as a diagnostic procedure: a review of known cellular and molecular findings in various lung diseases

Bronchoalveolar lavage (BAL) is a commonly used procedure in the evaluation of lung disease as it allows for sampling of the lower respiratory tract. In many circumstances, BAL differential cell counts have been reported to be typical of specific lung disorders. In addition, more specific diagnostic tests including molecular assays such as polymerase chain reaction (PCR) or enzyme-linked immunosorbent assay, special cytopathologic stains, or particular microscopic findings have been described as part of BAL fluid analysis. This review focuses on common cellular and molecular findings of BAL in a wide range of lung diseases. Since the performance of the first lung irrigation in 1927, BAL has become a common and important diagnostic tool. While some pulmonary disorders have a highly characteristic signature of BAL findings, BAL results alone often lack specificity and require interpretation along with other clinical and radiographic details. Development of new diagnostic assays is certain to reinforce the utility of BAL in the future. Our review of the BAL literature is intended to serve as a resource to assist clinicians in the care of patients with lung disorders.

Immunotherapies and Combination Strategies for Immuno-Oncology

The advent of novel immunotherapies in the treatment of cancers has dramatically changed the landscape of the oncology field. Recent developments in checkpoint inhibition therapies, tumor-infiltrating lymphocyte therapies, chimeric antigen receptor T cell therapies, and cancer vaccines have shown immense promise for significant advancements in cancer treatments. Immunotherapies act on distinct steps of immune response to augment the body's natural ability to recognize, target, and destroy cancerous cells. Combination treatments with immunotherapies and other modalities intend to activate immune response, decrease immunosuppression, and target signaling and resistance pathways to offer a more durable, long-lasting treatment compared to traditional therapies and immunotherapies as monotherapies for cancers. This review aims to briefly describe the rationale, mechanisms of action, and clinical efficacy of common immunotherapies and highlight promising combination strategies currently approved or under clinical development. Additionally, we will discuss the benefits and limitations of these immunotherapy approaches as monotherapies as well as in combination with other treatments.

A Nomogram for the Prognosis of Nasopharyngeal Carcinoma with MR Imaging-Detected Tumor Residue at the End of Intensity-Modulated Radiotherapy

Objective

This study set out to institute an effective nomogram to predict the prognosis of nasopharyngeal carcinoma (NPC) using magnetic resonance imaging (MRI)-detected residual tumor at the end of intensity-modulated radiotherapy (IMRT).

Background

This study retrospectively analyzed the prognostic factors of NPC using MRI-detected residual tumor at the end of IMRT, in order to individualize the treatment of patients with poor prognosis as early as possible.

Methods

Overall, 162 NPC patients with local or regional residual tumor at the end of IMRT were retrospectively analyzed. Based on multivariate Cox regression analysis using the backward stepwise method, a nomogram was generated to predict the prognosis of these patients. Identification, calibration, clinical applicability and reproducibility were evaluated by C-index, time-dependent AUC, calibration curve and bootstrap verification. According to the best cut-off value of total score of prognoses calculated by X-tile software, all patients were separated into either low-risk or high-risk group.

Results

The nomogram identified age, chemotherapy, N stage, lymph nodes necrosis are significant predictors of prognosis. The AUC of the prediction model is 0.754, and the consistency index is 0.724 (95% confidence interval is 0.659–0.788). The model has good discrimination ability. Through bootstrapping test, the consistency index, corrected slope was 0.723, 0.861, respectively. The calibration slope of predicting 3-year and 5-year overall survival was 1.006 and 1.071, respectively. The calibration curve showed satisfactory calibration effect and good net benefit. The best cut-off value of total score of prognoses calculated by X-tile software was 149.1. Kaplan–Meier survival curve showed that OS and DMFS in the high-risk group were substantially reduced compared to those in the low-risk group.

Conclusion

We constructed and validated a new nomogram to help clinicians understand the prognosis of NPC patients with residue at the end of IMRT. With an estimate of the individual risk, clinicians can start treatment decisions as early as possible for high-risk patients with poor prognosis.

Early variations in lymphocytes and T lymphocyte subsets are associated with radiation pneumonitis in lung cancer patients and experimental mice received thoracic irradiation

There were no ideal markers to predict the development of radiation pneumonitis (RP). We want to investigate the value of variations of lymphocytes and T lymphocyte subsets in predicting RP after radiotherapy (RT) of lung cancer based on previous clinical findings. A total of 182 lung cancer patients who received RT were retrospectively analyzed. Circulating lymphocytes and T lymphocyte subsets were measured before, during, and after RT. Patients were evaluated from the start of RT to 6 months post‐RT. A mice model with acute radiation‐induced lung injury was established and circulating lymphocytes were measured weekly until 8 weeks after irradiation. Univariate and multivariate analyses were adopted to identify risk factors of RP. Lymphocyte levels significantly decreased (P < .001) in patients before RP symptoms developed that also was able to be seen in the mice model and the values recovered during remission of symptoms. The decrease in lymphocyte count reflected the severity of RP. Meanwhile, CD4⁺ T lymphocyte count was significantly lower during the occurrence of symptoms in patients with RP than in those without RP (P < .001), and it improved along with RP recovery. Levels of lymphocytes and CD4⁺ T lymphocyte subsets proved as independent predictors of RP. Here we showed that lower peripheral blood levels of lymphocytes and CD4⁺ T lymphocyte were associated with an increased risk of RP, which was validated by this mice model, and thus are associated with differences in radiation‐induced lung toxicity among individuals and help identify those who are susceptible to developing RP after RT.

Experimental Models of Pulmonary Fibrosis and their Translational Potential

Pulmonary fibrosis, represented mainly by idiopathic pulmonary fibrosis, develops chronic and progressive changes in lung parenchyma with high mortality and limited therapeutic options. The aim of this review was to summarize the most common experimental models used in the research of pulmonary fibrosis. Lung damage associated with development of pulmonary fibrosis can be caused by irradiation or by instillation of bleomycin, fluorescein isothiocyanate (FITC), silicon dioxide (silica), asbestos, etc. This article reviews the characteristics of the most frequently used animal models of fibrosis, including the limitations of their use. Although none of the used animal models resembles completely the changes in human pulmonary fibrosis, similarities between them allow preclinical testing of novel treatment approaches or their combinations in the laboratory conditions before their use in the clinical practice.

Radiation-Induced Lung Injury: Assessment and Management

Radiation-induced lung injury (RILI) encompasses any lung toxicity induced by radiation therapy (RT) and manifests acutely as radiation pneumonitis and chronically as radiation pulmonary fibrosis. Because most patients with thoracic and breast malignancies are expected to undergo RT in their lifetime, many with curative intent, the population at risk is significant. Furthermore, indications for thoracic RT are expanding given the advent of stereotactic body radiation therapy (SBRT) or stereotactic ablative radiotherapy (SABR) for early-stage lung cancer in nonsurgical candidates as well as oligometastatic pulmonary disease from any solid tumor. Fortunately, the incidence of serious pulmonary complications from RT has decreased secondary to advances in radiation delivery techniques. Understanding the temporal relationship between RT and injury as well as the patient, disease, and radiation factors that help distinguish RILI from other etiologies is necessary to prevent misdiagnosis. Although treatment of acute pneumonitis is dependent on clinical severity and typically responds completely to corticosteroids, accurately diagnosing and identifying patients who may progress to fibrosis is challenging. Current research advances include high-precision radiation techniques, an improved understanding of the molecular basis of RILI, the development of small and large animal models, and the identification of candidate drugs for prevention and treatment.

Inhibition of NF-κB improves sensitivity to irradiation and EGFR-TKIs and decreases irradiation-induced lung toxicity

Resistance to radiotherapy and to EGFR tyrosine kinase inhibitors (EGFR-TKIs), as well as therapy-related lung toxicity, are serious problems in the treatment of lung cancer. NF-κB has been reported to be associated with radioresistance. Therefore, we evaluated its effects on sensitivity to irradiation and to EGFR-TKIs; irradiation-induced lung toxicity; and the effects of irradiation on sensitivity to EGFR-TKIs. We used IKKβ inhibitor IMD 0354 or p65 depletion to explore their effects on sensitivity to irradiation and to EGFR-TKIs in vitro and in vivo. We evaluated the efficacy of IMD 0354 in a radiation-induced pulmonary-fibrosis mouse model. Irradiation enhanced activation and expression of MET and therefore suppressed the sensitivity of lung cancer cells to irradiation or EGFR-TKIs. Inhibition of NF-κB by IMD 0354 or by p65 depletion reversed irradiation-induced MET activation and increased the sensitivity of lung cancer cells to irradiation, to EGFR-TKIs and to the combination thereof in vitro and in vivo. In addition, IMD 0354 significantly reduced lung toxicity in a murine model of irradiation-induced pneumonia and lung fibrosis. These findings indicated that NF-κB inhibition can improve sensitivity to irradiation and to EGFR-TKIs and can decrease irradiation-induced lung toxicity in lung cancer.

Modeling radiation-induced lung injury: lessons learned from whole thorax irradiation

Models of thoracic irradiation have been developed as clinicians and scientists have attempted to decipher the events that led up to the pulmonary toxicity seen in human subjects following radiation treatment. The most common model is that of whole thorax irradiation (WTI), applied in a single dose. Mice, particularly the C57BL/6J strain, has been frequently used in these investigations, and has greatly informed our current understanding of the initiation and progression of radiation-induced lung injury (RILI). In this review, we highlight the sequential progression and dynamic nature of RILI, focusing primarily on the vast array of information that has been gleaned from the murine model. Ample evidence indicates a wide array of biological responses that can be seen following irradiation, including DNA damage, oxidative stress, cellular senescence and inflammation, all triggered by the initial exposure to ionizing radiation (IR) and heterogeneously maintained throughout the temporal progression of injury, which manifests as acute pneumonitis and later fibrosis. It appears that the early responses of specific cell types may promote further injury, disrupting the microenvironment and preventing a return to homeostasis, although the exact mechanisms driving these responses remains somewhat unclear. Attempts to either prevent or treat RILI in preclinical models have shown some success by targeting these disparate radiobiological processes. As our understanding of the dynamic cellular responses to radiation improves through the use of such models, so does the likelihood of preventing or treating RILI.

Fucoidan Inhibits Radiation-Induced Pneumonitis and Lung Fibrosis by Reducing Inflammatory Cytokine Expression in Lung Tissues

Purpose: Radiotherapy is a crucial treatment approach for many types of cancer. Radiation pneumonitis (RP) is one of the major complications in chest irradiation. Fucoidan is a sulfated polysaccharide found mainly in various species of brown seaweed. Recent studies have demonstrated the anti-inflammatory effects of fucoidan. However, no study has reported a well-established prophylactic agent for RP. Therefore, we investigated the effects of fucoidan on RP and radiotherapy (RT)-induced lung fibrosis. Materials and Methods: We compared RP and RT-induced fibrosis in lung tissue specimens obtained from irradiated (10 Gy/shot) C57BL/6 mice with or without fucoidan administration (200 mg/kg/day, oral gavage for 14 days). The expression patterns of cytokines in the pleural fluid were determined using a cytokine array and confirmed through enzyme immunoassays. Results: Fucoidan administration attenuated RP and RT-induced fibrosis in lung tissues. Decreased neutrophil and macrophage accumulation was observed in irradiated lung tissues, and radiation-induced lung fibrosis, as demonstrated by Masson trichrome staining, was attenuated. We investigated the expression patterns of inflammatory cytokines in the irradiated lung pleural fluid through the protein array; results revealed that fucoidan administration changed the expression patterns of inflammatory cytokines in irradiated lung tissues. Furthermore, the expression levels of TIMP-1, CXCL1, MCP-1, MIP-2, and interleukin-1Ra were substantially enhanced in the pleural fluid, but fucoidan administration significantly reduced their expression. Conclusions: Fucoidan changes the expression patterns of inflammatory cytokines, which may consequently attenuate RP and RT-induced lung fibrosis.

18F-FDG PET/CT in Patients with Parenchymal Changes Attributed to Radiation Pneumonitis

Objectives:

Radiation pneumonitis (RP) can be an adverse complication of radiotherapy (RT) and can limit the application of the already planned radiation dose. It is often associated with RT of lung carcinoma and is occasionally caused by radiation therapy of breast carcinoma and lymphomas located in the mediastinum. Positron emission tomography/computed tomography (PET/CT) emerges lately as a prospective modality for early diagnostics of RP. The aim of this study was to summarize the initial data from diagnostic application of PET/CT in patients suspicious of RP and to derive criteria, which can help differentiate RP from early recurrence of the disease and/or residual tumor.

Methods:

The current study included 23 patients who had metabolic (PET) and anatomical (CT) changes consistent with RP. We additionally defined metabolic activity (SUV_max) in the lung parenchyma of 20 patients without RT.

Results:

All patients had increased metabolic activity in the lung parenchyma involved in the irradiated area with a mean SUV_max 3.45 (ranging between 1 and 7.1). The control group had a physiological background metabolic activity-SUV_max 0.61 +/- 0.11.

Conclusion:

Metabolic changes in patients suspicious of RP involved diffusely increased metabolic activity coinciding with the anatomical changes in the irradiated area. Three out of 23 patients had a proven recurrence of the primary neoplastic process in the irradiated area. The metabolic changes in those patients involved an increase in metabolic activity at follow-up or lack of tendency towards normalization after chemotherapy, which implied the existence of viable tumor cells. Our initial experience in the diagnostic application of ¹⁸F-FDG PET/CT in patients suspicious of RP allows us to summarize the following: PET/CT is a reliable imaging modality in the diagnostics of RP. Through its sequential use, we can differentiate inflammatory changes related to RP from early recurrence of the primary neoplastic process.

The Role of the Mammalian Target of Rapamycin (mTOR) in Pulmonary Fibrosis

The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR)-dependent pathway is one of the most integral pathways linked to cell metabolism, proliferation, differentiation, and survival. This pathway is dysregulated in a variety of diseases, including neoplasia, immune-mediated diseases, and fibroproliferative diseases such as pulmonary fibrosis. The mTOR kinase is frequently referred to as the master regulator of this pathway. Alterations in mTOR signaling are closely associated with dysregulation of autophagy, inflammation, and cell growth and survival, leading to the development of lung fibrosis. Inhibitors of mTOR have been widely studied in cancer therapy, as they may sensitize cancer cells to radiation therapy. Studies also suggest that mTOR inhibitors are promising modulators of fibroproliferative diseases such as idiopathic pulmonary fibrosis (IPF) and radiation-induced pulmonary fibrosis (RIPF). Therefore, mTOR represents an attractive and unique therapeutic target in pulmonary fibrosis. In this review, we discuss the pathological role of mTOR kinase in pulmonary fibrosis and examine how mTOR inhibitors may mitigate fibrotic progression.

Clarithromycin mitigates radiation pneumonitis in patients with lung cancer treated with stereotactic body radiotherapy

Background

Radiation pneumonitis is a critical pulmonary toxicity after irradiation of the lung. Macrolides including clarithromycin (CAM) are antibiotics. They also have immunomodulatory properties and are used to treat respiratory inflammatory diseases. Radiation pneumonitis has similar pathology to them. Adverse reactions to macrolides are few and self-limited. We thus administered CAM to patients with high-risk factors for radiation pneumonitis, and retrospectively investigated whether CAM mitigated radiation pneumonitis following stereotactic body radiotherapy (SBRT).

Methods

Among consecutive patients treated with SBRT, we retrospectively examined lung cancer patients treated with a total dose of 40-60 Gy in 5-10 fractions and followed ≥6 months. Since January 2014, CAM has been administered in patients with pretreatment predictable radiation pneumonitis high-risk factors, including idiopathic interstitial pneumonias (IIPs), and elevated Krebs von den Lungen-6 (KL-6) and/or surfactant protein D (SP-D), and in patients developing early onset radiation pneumonitis.

Results

Five hundred and eighty eligible patients were identified and divided into 445 patients during the non-CAM-administration era (non-CAM-era) (before December 2013) and 136 patients during the CAM-administration era (CAM-era) (after January 2014). Median follow-up durations were 38.0 and 13.9 months, respectively. The rates of radiation pneumonitis ≥ grade 2 and ≥ grade 3 were significantly lower in CAM-era (grade ≥2, 16% vs. 9.6%, P=0.047; grade ≥3, 3.8% vs. 0.73%, P=0.037). For patients with the pretreatment predictable high-risk factors, the rate of radiation pneumonitis ≥ grade 3 was significantly lower, and that of grade ≥2 had a lower tendency (grade ≥3, 7.2% vs. 0%, P=0.011; grade ≥2, 21% vs. 9.6%, P=0.061). For patients developing early onset radiation pneumonitis, the rate of radiation pneumonitis ≥ grade 3 was also significantly lower (23% vs. 0%, P<0.05). Multivariate analysis revealed that dose-volumetric factor, the pretreatment predictable high-risk factors and non-CAM-administration era were significantly associated with or trended toward radiation pneumonitis ≥ grade 2 and ≥ grade 3.

Conclusions

CAM mitigated radiation pneumonitis following SBRT. The efficacy of CAM should be confirmed in prospective studies.

Radiation Mitigating Properties of Intranasally Administered KL4 Surfactant in a Murine Model of Radiation-Induced Lung Damage

The threat of exposure to ionizing radiation from a nuclear reactor accident or deliberate terrorist actions is a significant public health concern. The lung is particularly susceptible to radiation-induced injury from external sources or inhalation of radioactive particles from radioactive fallout. Radiation-induced lung disease can manifest with an acute radiation pneumonitis and/or delayed effects leading to pulmonary fibrosis. As prior warning of radiation exposure is unlikely, medical countermeasures (MCMs) to mitigate radiation-induced lung disease that can be given in mass-casualty situations many hours or days postirradiation are needed to prevent both early and late lung damage. In this study, KL₄ surfactant (lucinactant) was evaluated as a radiation mitigator in a well-characterized mouse model of targeted thoracic radiation exposure, for its effect on both early (several weeks) and late (18 weeks) lung damage. Here, 120 mg/kg total phospholipid of KL₄ surfactant was administered twice daily intranasally, (enabling intrapulmonary inhalation of drug) to C57BL/6 mice 24 h after a single 13.5 Gy dose of thoracic irradiation (LD₅₀ dose). Both early and chronic phase (2 and 4 weeks and 18 weeks postirradiation, respectively) assessments were performed. Mice were evaluated for evidence of reduced arterial blood oxygenation and early and chronic lung and systemic inflammation, lung fibrosis and oxidative stress. Analysis was done by performing lung function/respiration dynamics and measuring cellular protein content of bronchoalveolar lavage fluid (BALF), and levels of cytokines, 8-iso-prostaglandin F2α, hydroxyproline in lung and plasma, along with evaluating lung histology. The results of this study showed that intranasal delivery of KL₄ surfactant was able to preserve lung function as evidenced by adequate arterial oxygen saturation and reduced lung inflammation and oxidative stress; total white count and absolute neutrophil count was decreased in BALF, as were plasma pro-inflammatory cytokine levels and biomarker of oxidative stress. KL₄ surfactant is a promising MCM for mitigation of lung tissue damage after targeted, thoracic irradiation and has the potential to be developed as a broad-spectrum, multi-use MCM against chemical, biological, radiological or nuclear threat agents with potential to cause lung injury.

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

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

Azithromycin attenuates acute radiation-induced lung injury in mice

Radiation-induced lung injury (RILI) is a common and major obstacle in thoracic cancer radiotherapy, resulting in considerable morbidity and limiting the dose of radiation. However, an effective treatment option remains to be established. Therefore, the present study aimed to investigate the effects of azithromycin (AZM) in acute RILI with a mouse model. In the present study, C57BL/6 mice were given a single thoracic irradiation of 16 Gy and administered orally with AZM. The lung histopathological findings, the levels of malondialdehyde (MDA; an indicator of oxidative damage) and the concentration of pro-inflammatory and pro-fibrotic cytokines in plasma were assessed on 28 day following irradiation. In addition, the total cell counts in bronchoalveolar lavage fluid (BALF), the pro-inflammatory and pro-fibrotic cytokine gene expression in lung tissue were evaluated on day 7, 14 and 28 following irradiation. Administration with AZM markedly alleviated acute RILI as indicated by hematoxylin and eosin and Masson staining. The levels of MDA and total cell counts in BALF significantly reduced in AZM treated mice. AZM also down-regulated the concentration and mRNA expression of interleukin (IL)-1β, IL-6, tumor necrosis factor-α and transforming growth factor-β1. In addition, AZM attenuated the irradiation-induced increases in the mRNA expression of fibrotic markers (α-smooth muscle actin and α-1 type I collagen). AZM treatment mitigated the radiation-induced acute lung injury possibly by its anti-inflammatory and anti-fibrotic effects.

Modeling DNA damage-induced pneumopathy in mice: insight from danger signaling cascades

Radiation-induced pneumonitis and fibrosis represent severe and dose-limiting side effects in the radiotherapy of thorax-associated neoplasms leading to decreased quality of life or - as a consequence of treatment with suboptimal radiation doses - to fatal outcomes by local recurrence or metastatic disease. It is assumed that the initial radiation-induced damage to the resident cells triggers a multifaceted damage-signalling cascade in irradiated normal tissues including a multifactorial secretory program. The resulting pro-inflammatory and pro-angiogenic microenvironment triggers a cascade of events that can lead within weeks to a pronounced lung inflammation (pneumonitis) or after months to excessive deposition of extracellular matrix molecules and tissue scarring (pulmonary fibrosis).The use of preclinical in vivo models of DNA damage-induced pneumopathy in genetically modified mice has helped to substantially advance our understanding of molecular mechanisms and signalling molecules that participate in the pathogenesis of radiation-induced adverse late effects in the lung. Herein, murine models of whole thorax irradiation or hemithorax irradiation nicely reproduce the pathogenesis of the human disease with respect to the time course and the clinical symptoms. Alternatively, treatment with the radiomimetic DNA damaging chemotherapeutic drug Bleomycin (BLM) has frequently been used as a surrogate model of radiation-induced lung disease. The advantage of the BLM model is that the symptoms of pneumonitis and fibrosis develop within 1 month.Here we summarize and discuss published data about the role of danger signalling in the response of the lung tissue to DNA damage and its cross-talk with the innate and adaptive immune systems obtained in preclinical studies using immune-deficient inbred mouse strains and genetically modified mice. Interestingly we observed differences in the role of molecules involved in damage sensing (TOLL-like receptors), damage signalling (MyD88) and immune regulation (cytokines, CD73, lymphocytes) for the pathogenesis and progression of DNA damage-induced pneumopathy between the models of pneumopathy induced by whole thorax irradiation or treatment with the radiomimetic drug BLM. These findings underline the importance to pursue studies in the radiation model(s) if we are to unravel the mechanisms driving radiation-induced adverse late effects.A better understanding of the cross-talk of danger perception and signalling with immune activation and repair mechanisms may allow a modulation of these processes to prevent or treat radiation-induced adverse effects. Vice-versa an improved knowledge of the normal tissue response to injury is also particularly important in view of the increasing interest in combining radiotherapy with immune checkpoint blockade or immunotherapies to avoid exacerbation of radiation-induced normal tissue toxicity.

Optimizing tumor immune response through combination of radiation and immunotherapy

Radiation therapy and immunotherapy are two highly evolving modalities for the treatment of solid tumors. Immunotherapeutic drugs can either stimulate the immune system via immunogenic pathways or target co-inhibitory checkpoints. An augmented tumor cell recognition by host immune cells can be achieved post-irradiation, as irradiated tissues can release chemical signals which are sensed by the immune system resulting in its activation. Different strategies combining both treatment modalities were tested in order to achieve a better therapeutic response and longer tumor control. Both regimens act synergistically to one another with complimentary mechanisms. In this review, we explore the scientific basis behind such a combination, starting initially with a brief historical overview behind utilizing radiation and immunotherapies for solid tumors, followed by the different types of these two modalities, and the biological concept behind their synergistic effect. We also shed light on the common side effects and toxicities associated with radiation and immunotherapy. Finally, we discuss previous clinical trials tackling this multimodality combination and highlight future ongoing research.

Bilateral diffuse grade 5 radiation pneumonitis after intensity modulated radiation therapy for localized lung cancer

We are reporting a case of fatal radiation pneumonitis that developed six months following chemoradiation for limited stage small cell lung cancer. The patient was a 67-year-old man with a past medical history of Hashimoto’s thyroiditis and remote suspicion for CREST, neither of which were active in the years leading up to treatment. He received 6600 cGy delivered in 200 cGy daily fractions via intensity modulated radiation therapy with concurrent cisplatin/etoposide followed by additional chemotherapy with dose-reduced cisplatin/etoposide and carboplatin/etoposide and then received prophylactic cranial irradiation. The subsequent months were notable for progressively worsening episodes of respiratory compromise despite administration of prolonged steroids and he ultimately expired. Imaging demonstrated bilateral interstitial and airspace opacities. Autopsy findings were consistent with pneumonitis secondary to chemoradiation as well as lymphangitic spread of small cell carcinoma. The process was diffuse bilaterally although his radiation was delivered focally to the right lung and mediastinum.

Predicting risk factors for radiation pneumonitis after stereotactic body radiation therapy for primary or metastatic lung tumours

OBJECTIVE

To investigate risk factors for radiation-induced pneumonitis (RP) after hypofractionated stereotactic body radiotherapy (SBRT) in patients with lung tumours.

METHODS

From May 2004 to January 2016, 66 patients with 71 primary or metastatic lung tumours were treated with SBRT; these 71 cases were retrospectively analyzed for RP. To explore the risk factors for RP, the following factors were investigated: age, sex, performance status, operability, number of treatments, respiratory gating, pulmonary emphysema, tumour location and subclinical interstitial lung disease (ILD). Irradiated underlying lung volumes of more than 5 Gy, 10 Gy, 20 Gy and 30 Gy (Lung V5, V10, V20 and V30), mean lung dose and volumes of gross tumour volume (in cubic centimetre) and planning target volume were calculated for possible risk factors of RP.

RESULTS

The median follow-up period was 32 months. RP of Grade 2 or more, according to the Common Terminology Criteria for Adverse Events v. 4.0, was detected in 6 (8.4%) of the 71 cases. Grade 5 RP was identified in two cases. Of the risk factors of RP, subclinical ILD was the only factor significantly associated with the occurrence of RP of Grade 2 or more (p < 0.001). Both cases with Grade 5 RP had ILD with a honeycombing image.

CONCLUSION

Subclinical ILD was the only significant factor for Grade 2-5 RP. In addition, the cases with honeycombing had a high potential for fatality related to severe RP. Patients with subclinical ILD should be carefully monitored for the occurrence of severe RP after SBRT. Advances in knowledge: Hypofractionated SBRT for primary or metastatic lung tumours provides a high local control rate and safe treatment.

The Role of Lymphocytes in Radiotherapy-Induced Adverse Late Effects in the Lung

Radiation-induced pneumonitis and fibrosis are dose-limiting side effects of thoracic irradiation. Thoracic irradiation triggers acute and chronic environmental lung changes that are shaped by the damage response of resident cells, by the resulting reaction of the immune system, and by repair processes. Although considerable progress has been made during the last decade in defining involved effector cells and soluble mediators, the network of pathophysiological events and the cellular cross talk linking acute tissue damage to chronic inflammation and fibrosis still require further definition. Infiltration of cells from the innate and adaptive immune systems is a common response of normal tissues to ionizing radiation. Herein, lymphocytes represent a versatile and wide-ranged group of cells of the immune system that can react under specific conditions in various ways and participate in modulating the lung environment by adopting pro-inflammatory, anti-inflammatory, or even pro- or anti-fibrotic phenotypes. The present review provides an overview on published data about the role of lymphocytes in radiation-induced lung disease and related damage-associated pulmonary diseases with a focus on T lymphocytes and B lymphocytes. We also discuss the suspected dual role of specific lymphocyte subsets during the pneumonitic phase and fibrotic phase that is shaped by the environmental conditions as well as the interaction and the intercellular cross talk between cells from the innate and adaptive immune systems and (damaged) resident epithelial cells and stromal cells (e.g., endothelial cells, mesenchymal stem cells, and fibroblasts). Finally, we highlight potential therapeutic targets suited to counteract pathological lymphocyte responses to prevent or treat radiation-induced lung disease.

Sequential adjuvant chemoradiotherapy-induced diffuse alveolar haemorrhage in a patient with breast cancer successfully treated with corticosteroid plus recombinant human soluble thrombomodulin

The effective treatment for corticosteroid (CS)-refractory sequential chemoradiotherapy (CRT)-induced lung injury has not been established. We report a case of sequential CRT-induced diffuse alveolar haemorrhage (DAH) successfully treated with CS therapy plus recombinant human soluble thrombomodulin (rhTM). A 69-year-old woman was treated with sequential adjuvant CRT for early-stage breast cancer. After sequential CRT, she suffered from progressive dyspnoea. Chest CT scan showed consolidations in the irradiation field and diffuse ground-glass attenuations in the non-irradiation regions. We suspected sequential CRT-induced DAH because of increased haemosiderin-laden macrophages in bronchoalveolar lavage fluid. Her clinical conditions did not improve with high-dose CS therapy. Therefore, rhTM was added, and her disease and serum high-mobility group box-1 levels improved rapidly. Therefore, rhTM plus CS might be a safe and effective treatment for sequential CRT-induced lung injury, although further study is necessary to validate these findings.