Investigations into the role of inflammation in normal tissue response to irradiation

Molecular biological mechanisms of radiotherapy-induced skin injury occurrence and treatment

Radiotherapy-Induced Skin Injury (RISI) is radiation damage to normal skin tissue that primarily occurs during tumor Radiotherapy and occupational exposure. The risk of RISI is high due to the fact that the skin is not only the first body organ that ionizing radiation comes into contact with, but it is also highly sensitive to it, especially the basal cell layer and capillaries. Typical clinical manifestations of RISI include erythema, dry desquamation, moist desquamation, and ulcers, which have been established to significantly impact patient care and cancer treatment. Notably, our current understanding of RISI's pathological mechanisms and signaling pathways is inadequate, and no standard treatments have been established. Radiation-induced oxidative stress, inflammatory responses, fibrosis, apoptosis, and cellular senescence are among the known mechanisms that interact and promote disease progression. Additionally, radiation can damage all cellular components and induce genetic and epigenetic changes, which play a crucial role in the occurrence and progression of skin injury. A deeper understanding of these mechanisms and pathways is crucial for exploring the potential therapeutic targets for RISI. Therefore, in this review, we summarize the key mechanisms and potential treatment methods for RISI, offering a reference for future research and development of treatment strategies.

Cancer treatments as paradoxical catalysts of tumor awakening in the lung

Much of the fatality of tumors is linked to the growth of metastases, which can emerge months to years after apparently successful treatment of primary tumors. Metastases arise from disseminated tumor cells (DTCs), which disperse through the body in a dormant state to seed distant sites. While some DTCs lodge in pre-metastatic niches (PMNs) and rapidly develop into metastases, other DTCs settle in distinct microenvironments that maintain them in a dormant state. Subsequent awakening, induced by changes in the microenvironment of the DTC, causes outgrowth of metastases. Hence, there has been extensive investigation of the factors causing survival and subsequent awakening of DTCs, with the goal of disrupting these processes to decrease cancer lethality. We here provide a detailed overview of recent developments in understanding of the factors controlling dormancy and awakening in the lung, a common site of metastasis for many solid tumors. These factors include dynamic interactions between DTCs and diverse epithelial, mesenchymal, and immune cell populations resident in the lung. Paradoxically, among key triggers for metastatic outgrowth, lung tissue remodeling arising from damage induced by the treatment of primary tumors play a significant role. In addition, growing evidence emphasizes roles for inflammation and aging in opposing the factors that maintain dormancy. Finally, we discuss strategies being developed or employed to reduce the risk of metastatic recurrence.

Targeting Tumor Necrosis Factor Alpha to Mitigate Lung Injury Induced by Mustard Vesicants and Radiation

Pulmonary injury induced by mustard vesicants and radiation is characterized by DNA damage, oxidative stress, and inflammation. This is associated with increases in levels of inflammatory mediators, including tumor necrosis factor (TNF)α in the lung and upregulation of its receptor TNFR1. Dysregulated production of TNFα and TNFα signaling has been implicated in lung injury, oxidative and nitrosative stress, apoptosis, and necrosis, which contribute to tissue damage, chronic inflammation, airway hyperresponsiveness, and tissue remodeling. These findings suggest that targeting production of TNFα or TNFα activity may represent an efficacious approach to mitigating lung toxicity induced by both mustards and radiation. This review summarizes current knowledge on the role of TNFα in pathologies associated with exposure to mustard vesicants and radiation, with a focus on the therapeutic potential of TNFα-targeting agents in reducing acute injury and chronic disease pathogenesis.

Complication Rates in Therapeutic Versus Prophylactic Bilateral Mastectomies: Insights From a National Database

BACKGROUND

The "Jolie effect" and other media focus on prophylactic treatments have resulted in unilateral breast cancer patients increasingly undergoing contralateral prophylactic mastectomy. Little is known, however, regarding outcomes following therapeutic versus prophylactic mastectomy. In this study, we compared complication rates of unilateral breast cancer patients undergoing contralateral prophylactic mastectomy (BM-TP) to patients undergoing bilateral prophylactic mastectomy (BM-P).

METHODS

The BM-TP and BM-P patients from 2015 to 2019 were identified in Optum Clinformatics DataMart. Six-month outcomes were assessed and included wound complications, infection, hematoma/seroma, breast pain, fat necrosis, flap failure, implant failure/removal, other flap/implant complications, and other complications. Multivariable regression models adjusted for age, residence, insurance, race, and Charlson Comorbidity Index score.

RESULTS

Of 9319 women, 7114 (76.3%) underwent BM-TP, and 2205 (23.7%) underwent BM-P. In multivariable analysis, BM-TP had higher odds of overall complications (adjusted odds ratio [aOR], 1.35; P < 0.0001), but no difference was observed among patients who had autologous ( P = 0.1448) or no breast reconstruction ( P = 0.1530). Higher odds of overall complications persisted even after controlling for radiation therapy (aOR, 1.25; P = 0.0048) and chemotherapy (aOR, 1.28; P = 0.0047), but not after controlling for lymph node surgery ( P = 0.7765).

CONCLUSION

The BM-TP (vs BM-P) patients face higher odds of overall complications but without any difference in certain reconstructive modalities or after controlling for lymph node surgery.

STING signaling activation modulates macrophage polarization via CCL2 in radiation-induced lung injury

BACKGROUND

Radiation-induced lung injury (RILI) is a prevalent complication of thoracic radiotherapy in cancer patients. A comprehensive understanding of the underlying mechanisms of RILI is essential for the development of effective prevention and treatment strategies.

METHODS

To investigate RILI, we utilized a mouse model that received 12.5 Gy whole-thoracic irradiation. The evaluation of RILI was performed using a combination of quantitative real-time polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA), histology, western blot, immunohistochemistry, RNA sequencing, and flow cytometry. Additionally, we established a co-culture system consisting of macrophages, lung epithelial cells, and fibroblasts for in vitro studies. In this system, lung epithelial cells were irradiated with a dose of 4 Gy, and we employed STING knockout macrophages. Translational examinations were conducted to explore the relationship between STING expression in pre-radiotherapy lung tissues, dynamic changes in circulating CCL2, and the development of RILI.

RESULTS

Our findings revealed significant activation of the cGAS-STING pathway and M1 polarization of macrophages in the lungs of irradiated mice. In vitro studies demonstrated that the deficiency of cGAS-STING signaling led to impaired macrophage polarization and RILI. Through RNA sequencing, cytokine profiling, and rescue experiments using a CCL2 inhibitor called Bindarit, we identified the involvement of CCL2 in the regulation of macrophage polarization and the development of RILI. Moreover, translational investigations using patient samples collected before and after thoracic radiotherapy provided additional evidence supporting the association between cGAS-STING signaling activity, CCL2 upregulation, and the development of radiation pneumonitis.

CONCLUSIONS

The cGAS-STING signaling pathway plays a crucial role in regulating the recruitment and polarization of macrophages, partly through CCL2, during the pathogenesis of RILI.

Methods to assess radiation-induced fibrosis in mice

Therapeutic radiation is used to treat a variety of cancers in organs and tissues throughout the body. Exposure of benign normal tissue to radiation can result in late injury in a subset of patients. Radiation induced fibrosis is one chronic, progressive late toxicity of radiation exposure that can occur in many organs and tissues, including skin and lung. Radiation fibrosis has few effective treatments. The process of radiation fibrosis is known to involve many mitogenic and immunomodulatory cytokines, inflammatory programs, and processes such as stem cell senescence. Murine models of radiation fibrosis can be used to evaluate agents that may prevent, mitigate, or treat this injury. Here, we provide a detailed protocol for the development of radiation induced dermal and pulmonary fibrosis in mice and describe protocols for the measurement of this injury in treated tissue.

CT patterns and serial CT Changes in lung Cancer patients post stereotactic body radiotherapy (SBRT)

Background

To evaluate computed tomography (CT) patterns of post-SBRT lung injury in lung cancer and identify time points of serial CT changes.

Materials and methods

One hundred eighty-three tumors in 170 patients were evaluated on sequential CTs within 29 months (median). Frequencies of post-SBRT CT patterns and time points of initiation and duration were assessed. Duration of increase of primary lesion or surrounding injury without evidence of local recurrence and time to stabilization or local recurrence were evaluated.

Results

Post-SBRT CT patterns could overlap in the same patient and were nodule-like pattern (69%), consolidation with ground glass opacity (GGO) (41%), modified conventional pattern (39%), peribronchial/patchy consolidation (42%), patchy GGO (24%), diffuse consolidation (16%), “orbit sign” (21%), mass-like pattern (19%), scar-like pattern (15%) and diffuse GGO (3%). Patchy GGO started at 4 months post-SBRT. Peribronchial/patchy consolidation and consolidation with GGO started at 4 and 5 months respectively. Diffuse consolidation, diffuse GGO and orbit sign started at 5, 6 and 8 months respectively. Mass-like, modified conventional and scar-like pattern started at 8, 12 and 12 months respectively. Primary lesion (n = 11) or surrounding injury (n = 85) increased up to 13 months. Primary lesion (n = 119) or surrounding injury (n = 115) started to decrease at 4 and 9 months respectively. Time to stabilization was 20 months. The most common CT pattern at stabilization was modified conventional pattern (49%), scar-like pattern (23%) and mass-like pattern (12%). Local recurrence (n = 15) occurred at a median time of 18 months.

Conclusion

Different CT patterns of lung injury post-SBRT appear in predictable time points and have variable but predictable duration. Familiarity with these patterns and timeframes of appearance helps differentiate them from local recurrence.

Biological Pathways Associated With the Development of Pulmonary Toxicities in Mesothelioma Patients Treated With Radical Hemithoracic Radiation Therapy: A Preliminary Study

Radical hemithoracic radiotherapy (RHR), after lung-sparing surgery, has recently become a concrete therapeutic option for malignant pleural mesothelioma (MPM), an asbestos-related, highly aggressive tumor with increasing incidence and poor prognosis. Although the toxicity associated to this treatment has been reduced, it is still not negligible and must be considered when treating patients. Genetic factors appear to play a role determining radiotherapy toxicity. The aim of this study is the identification of biological pathways, retrieved through whole exome sequencing (WES), possibly associated to the development of lung adverse effects in MPM patients treated with RHR. The study included individuals with MPM, treated with lung-sparing surgery and chemotherapy, followed by RHR with curative intent, and followed up prospectively for development of pulmonary toxicity. Due to the strong impact of grade 3 pulmonary toxicities on the quality of life, compared with less serious adverse events, for genetic analyses, patients were divided into a none or tolerable pulmonary toxicity (NoSTox) group (grade ≤2) and a severe pulmonary toxicity (STox) group (grade = 3). Variant enrichment analysis allowed us to identify different pathway signatures characterizing NoSTox and Stox patients, allowing to formulate hypotheses on the protection from side effects derived from radiotherapy as well as factors predisposing to a worst response to the treatment. Our findings, being aware of the small number of patients analyzed, could be considered a starting point for the definition of a panel of pathways, possibly helpful in the management of MPM patients.

Comparing Outcomes of Flap-Based Salvage Reconstructions in the Radiated Breast

INTRODUCTION

Chest wall irradiation significantly decreases the strength and quality of breast tissue supporting prostheses, increasing the risk of skin breakdown and implant or tissue expander extrusion. Autologous tissue, including the latissimus dorsi (LD) or abdominal-based flaps, including the muscle-sparing transverse rectus abdominis myocutaneous or deep inferior epigastric perforator flaps, may be used to salvage reconstructions. However, data comparing outcomes of the two flap options remains limited. We compare postoperative outcomes from both flap types after autologous salvage reconstruction in irradiated breasts.

METHODS

Charts were retrospectively reviewed from patients who underwent either chest wall radiation or postmastectomy radiation therapy followed by salvage autologous reconstruction with either a LD and an implant or an abdominal-based flap (muscle-sparing transverse rectus abdominis myocutaneous or deep inferior epigastric perforator flaps). Patients with a history of tissue expander or implant failure requiring autologous salvage as part of 2-staged or delayed-immediate breast reconstruction that were operated on between January 2005 and November 2015 were included. Basic demographics, comorbidities, and recipient site complications (infection, wound dehiscence, seroma, hematoma, fat necrosis, and flap failure) were collected.

RESULTS

A total of 72 patients met the inclusion criteria which included 72 flaps; 35 LD and 37 abdominally based flaps. Demographics and comorbidities did not vary significantly between patient groups. Mean follow-up was 767.6 weeks, and all reconstructions were unilateral. Nineteen (26.4%) patients had at least one complication, most commonly minor infections (9.7%). Overall complication rates were not significantly different between flap groups (P = 0.083). Wound dehiscence was significantly higher in the abdominal group (P = 0.045), and fat necrosis also trended higher in this group (P = 0.085). Major infection trended higher in the latissimus group (P = 0.069).

CONCLUSIONS

When comparing outcomes of salvage flap-based reconstruction in radiated breast tissue, overall complication rates were similar when comparing postoperative outcomes between the LD- and abdominal-based flaps. Wound dehiscence was significantly higher when salvage reconstruction used an abdominal flap. Understanding the complications after salvage procedures can help inform decision making and optimize patient care to improve outcomes after breast reconstruction in the radiated breast.

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.

Involvement of Klotho, TNF‑&alpha; and ADAMs in radiation‑induced senescence of renal epithelial cells

While radiation nephropathy is a major problem associated with radiotherapy, the exact mechanisms underlying its pathogenesis and the mediators involved in kidney deterioration remain to be elucidated. In view of the finding that senescence is typically increased post‑irradiation, the present study examined whether ionizing radiation may cause kidney injury by enhancing premature senescence. The present study explored the relevance of the aging suppressor, Klotho, which has anti‑aging activity and is highly expressed in murine renal cells/kidney tissues, under irradiation conditions. Firstly, the effects of radiation on mouse inner medullary collecting duct‑3 (mIMCD‑3) cells and kidney tissues of mice were assessed. Subsequently, the mRNA expression levels of Klotho, TNF‑α and ADAM metallopeptidase domain (ADAM)9/10/17 were analyzed by reverse transcription‑quantitative PCR following exposure to radiation. In addition, the levels of these proteins were measured by western blotting or ELISA. The results revealed that irradiation of mIMCD‑3 cells clearly triggered cellular senescence. Notably, Klotho gene expression was considerably decreased in radiation‑exposed mIMCD‑3 cells and in the kidney tissues of irradiated BALB/c mice, and the corresponding translated protein was consistently expressed following radiation exposure. Moreover, expression of TNF‑α, a negative regulator of Klotho, was significantly increased, whereas ADAM9/10/17, an ectodomain shedding enzyme of Klotho, was decreased in irradiated mIMCD‑3 cells and in the kidney tissues of BALB/c mice. Collectively, these data suggested that TNF‑α‑mediated inhibition of Klotho expression and blockage of soluble Klotho formation via decreased ADAM expression following irradiation may contribute to the development of renal dysfunction through acceleration of radiation‑induced cellular senescence.

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.

Potency and Selectivity of SMAC/DIABLO Mimetics in Solid Tumor Therapy

Aiming to promote cancer cell apoptosis is a mainstream strategy of cancer therapy. The second mitochondria-derived activator of caspase (SMAC)/direct inhibitor of apoptosis protein (IAP)-binding protein with low pI (DIABLO) protein is an essential and endogenous antagonist of inhibitor of apoptosis proteins (IAPs). SMAC mimetics (SMs) are a series of synthetically chemical compounds. Via database analysis and literature searching, we summarize the potential mechanisms of endogenous SMAC inefficiency, degradation, mutation, releasing blockage, and depression. We review the development of SMs, as well as preclinical and clinical outcomes of SMs in solid tumor treatment, and we analyze their strengths, weaknesses, opportunities, and threats from our point of view. We also highlight several questions in need of further investigation.

Validation study of the association between genetic variant of IL4 and severe radiation pneumonitis in lung cancer patients treated with radiation therapy

BACKGROUND AND PURPOSE

Recent researches demonstrated that single nucleotide polymorphisms (SNPs) of genes involving inflammation, DNA repair, etc. were associated with risk of radiation pneumonitis (RP). However, these studies were single-centered, from single ethnic origin, without validation from independent cohort studies from other populations. In order to identify clinical valuable SNPs for RP, in this study we selected 19 RP-related SNPs candidates previously published before 2016 for validation in our cohort.

MATERIAL AND METHODS

359 lung cancer patients with radiotherapy were included in our prospective study (NCT02490319). Peripheral blood samples from these patients were genotyped by MassArray and Sanger Sequence method. Multivariate Cox hazard and other analyses were applied to estimate the hazard ratio (HR) and 95% confidence intervals (CIs) of all factors possibly related to the risk of RP.

RESULTS

Patients with elder age, MLD ≥15 Gy, V₂₀ ≥24% had higher risk of RP ≥grade 3 compared with their counterparts (HR = 2.020, 95% CI: 1.045-3.906, P = 0.037; HR = 2.502, 95% CI: 1.346-4.652, P = 0.004; HR = 2.256, 95% CI: 1.191-4.272, P = 0.013, respectively). Moreover, patients receiving IMRT were associated with decreased incidence of RP (HR = 0.520, 95% CI: 0.280-0.963, P = 0.037). Importantly, CT + TT genotype of IL4: rs2243250 was strongly related to decreased risk of RP ≥grade 3 (HR = 0.195, 95% CI: 0.090-0.424, P = 0.000037, P_c = 0.0006).

CONCLUSION

IL4: rs2243250 was validated to be significantly related to RP of grade ≥3 in our cohort. Our results further emphasized the prevalence and clinical value of IL4: rs2243250 on RP, and may thus be one of the important predictors of severe RP before radiotherapy.

Targeting interleukin-1: implications for long-term cardiovascular management following radiotherapy

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Preclinical models of radiation-induced lung damage: challenges and opportunities for small animal radiotherapy

Despite a major paradigm shift in radiotherapy planning and delivery over the past three decades with continuing refinements, radiation-induced lung damage (RILD) remains a major dose limiting toxicity in patients receiving thoracic irradiations. Our current understanding of the biological processes involved in RILD which includes DNA damage, inflammation, senescence and fibrosis, is based on clinical observations and experimental studies in mouse models using conventional radiation exposures. Whilst these studies have provided vital information on the pulmonary radiation response, the current implementation of small animal irradiators is enabling refinements in the precision and accuracy of dose delivery to mice which can be applied to studies of RILD. This review presents the current landscape of preclinical studies in RILD using small animal irradiators and highlights the challenges and opportunities for the further development of this emerging technology in the study of normal tissue damage in the lung.

Soy Isoflavones Protect Normal Tissues While Enhancing Radiation Responses

Soy isoflavones have demonstrated chemopreventive and anticancer properties in epidemiology and biological studies, in addition to their function as antioxidants in prevention of cardiovascular disease. We have explored the potential of soy isoflavones, as a safe biological approach, to enhance the efficacy of radiotherapy for local tumor control and limit normal tissue damage in solid tumors. This review presents studies investigating the interaction between soy isoflavones and radiation in different malignancies, including prostate cancer, renal cell carcinoma, and nonsmall cell lung cancer. Soy isoflavones were found to be potent sensitizers of cancer cells to radiation causing increased cell killing in vitro in human tumor cell lines and greater tumor inhibition in vivo in preclinical orthotopic murine tumor models. In the course of these studies, radioprotection of normal tissues and organs in the field of radiation was observed both in a clinical trial for prostate cancer and in preclinical models. The mechanisms of radiosensitization and radioprotection mediated by soy isoflavones are discussed and emphasize the role of soy isoflavones in increasing radiation effect on tumor and mitigating inflammatory responses induced by radiation in normal tissues. Soy isoflavones could be used as a safe, nontoxic complementary strategy that simultaneously increases radiation effectiveness on the malignancy while reducing damage in normal tissues in the field of radiation.

18β-Glycyrrhetinic acid mitigates radiation-induced skin damage via NADPH oxidase/ROS/p38MAPK and NF-κB pathways

Radiation-induced inflammation plays an important role in radiation-induced tissue injury. 18β-glycyrrhetinic acid (18β-GA) has shown an anti-inflammatory activity. This study aimed to assess the activity of 18β-GA against radiation-induced skin damage, and explore the underlying mechanisms. In vitro assay revealed 18β-GA treatment decreased the production of IL-1β, IL-6, PGE2 and decreased p38MAPK phosphorylation, DNA-binding activity of AP-1, and NF-κB activation in irradiated RAW264.7 macrophages. Additionally, 18β-GA suppressed NF-κB activation by inhibiting NF-κB/p65 and IκB-α phosphorylation and alleviated ROS overproduction in irradiated RAW264.7 macrophages. In vivo assay showed 18β-GA alleviated severity of radiation-induced skin damage, reduced inflammatory cell infiltration and TNF-α, IL-1β and IL-6 levels in cutaneous tissues. Our findings demonstrate that 18β-GA exhibits anti-inflammatory actions against radiation-induced skin damage probably by inhibiting NADPH oxidase activity, ROS production, activation of p38MAPK and NF-κB signaling, and the DNA binding activities of NF-κB and AP-1, consequently suppressing pro-inflammatory cytokine production.

Mechanisms of Normal Tissue Injury From Irradiation

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

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.

Combing NLR, V20 and mean lung dose to predict radiation induced lung injury in patients with lung cancer treated with intensity modulated radiation therapy and chemotherapy

The purpose was to evaluate the predictive value of baseline neutrophil to lymphocyte ratio (NLR) level in the incidence of grade 3 or higher radiation induced lung injury (RILI) for lung cancer patients. A retrospectively analysis with 166 lung cancer patients was performed. All of the enrolled patients received chemoradiotherapy at our hospital between April 2014 and May 2016. The Cox proportional hazard model was used to identify the potential risk factors for RILI. In this cohort, the incidence of grade 3 or higher RILI was 23.8%. Univariate analysis showed that radiation dose, volume at least received 20Gy (V20), mean lung dose and NLR were significantly associated with the incidence of grade 3 or higher RILI (P = 0.012, 0.008, 0.012, and 0.039, respectively). Multivariate analysis revealed that total dose ≥ 60 Gy, V20 ≥ 20%, mean lung dose ≥ 12 Gy, and NLR ≥ 2.2 were still independent predictive factors for RILI (P = 0.010, 0.043, 0.028, and 0.015, respectively). A predictive model of RILI based on the identified risk factors was established using receiver operator characteristic curves. The results demonstrated that the combination analysis of V20, mean lung dose and NLR was superior to either of the variables alone. Additionally, we found that the constraint of V20 and mean lung dose were meaningful for patients with higher baseline NLR level. If the value of V20 and mean lung dose lower than the threshold value, the incidence of grade 3 or higher RILI for the high NLR level patients could be decreased from 63.3% to 8.7%. Our study showed that radiation dose, V20, mean lung dose and NLR were independent predictors for RILI. Combination analysis of V20, mean lung dose and NLR may provide a more accurate model for RILI prediction.

Innate Immune Pathways Associated with Lung Radioprotection by Soy Isoflavones

Introduction

Radiation therapy for lung cancer causes pneumonitis and fibrosis. Soy isoflavones protect against radiation-induced lung injury, but the mediators of radioprotection remain unclear. We investigated the effect of radiation on myeloid-derived suppressor cells (MDSCs) in the lung and their modulation by soy isoflavones for a potential role in protection from radiation-induced lung injury.

Methods

BALB/c mice (5–6 weeks old) received a single 10 Gy dose of thoracic irradiation and soy isoflavones were orally administrated daily before and after radiation at 1 mg/day. Arginase-1 (Arg-1) and nuclear factor κB (NF-κB) p65 were detected in lung tissue by western blot analysis and immunohistochemistry. Lung MDSC subsets and their Arg-1 expression were analyzed by flow cytometry. Cytokine levels in the lungs were measured by ELISA.

Results

At 1 week after radiation, CD11b⁺ cells expressing Arg-1 were decreased by radiation in lung tissue yet maintained in the lungs treated with radiation and soy isoflavones. Arg-1 was predominantly expressed by CD11b⁺Ly6C^lowLy6G⁺ granulocytic MDSCs (gr-MDSCs). Arg-1 expression in gr-MDSCs was reduced by radiation and preserved by supplementation with soy isoflavones. A persistent increase in Arg-1⁺ cells was observed in lung tissue treated with combined radiation and soy isoflavones at early and late time points, compared to radiation alone. The increase in Arg-1 expression mediated by soy isoflavones could be associated with the inhibition of radiation-induced activation of NF-κB and the control of pro-inflammatory cytokine production demonstrated in this study.

Conclusion

A radioprotective mechanism of soy isoflavones may involve the promotion of Arg-1-expressing gr-MDSCs that could play a role in downregulation of inflammation and lung radioprotection.

Effects of CpG oligodeoxynucleotide 1826 on acute radiation-induced lung injury in mice

Background

The radiation-induced lung injury is a common complication from radiotherapy in lung cancer. CpG ODN is TLR9 activator with potential immune modulatory effects and sensitization of radiotherapy in lung cancer. This study aimed to examine the effect of CpG ODN on acute radiation-induced lung injury in mice.

Methods and results

The mouse model of radiation-induced lung injury was established by a single dose of 20 Gy X-rays exposure to the left lung. The results showed that the pneumonia score was lower in RT+CpG group than in RT group on 15th and 30th days. Compared with RT group, CpG ODN reduced the serum concentrations of MDA (P < 0.05) and increased the serum concentrations of SOD, GSH (P < 0.05). The serum concentration of TNF-α in RT+CpG group was lower on 15th and 30th days post-irradiation (P < 0.05).

Conclusion

The study demonstrated that CpG ODN has preventive effects of acute radiation-induced lung injury in mice. Lung inflammatory reaction and oxidative stress are promoted in the initiation of radiation-induced pneumonia. CpG ODN may reduce the injury of reactive oxygen species and adjust the serum TNF-α concentration in the mice after irradiation, which reduces the generation of the inflammatory cytokines.

Soy Isoflavones Promote Radioprotection of Normal Lung Tissue by Inhibition of Radiation-Induced Activation of Macrophages and Neutrophils

INTRODUCTION

Radiation therapy for lung cancer is limited by toxicity to normal lung tissue that results from an inflammatory process, leading to pneumonitis and fibrosis. Soy isoflavones mitigate inflammatory infiltrates and radiation-induced lung injury, but the cellular immune mediators involved in the radioprotective effect are unknown.

METHODS

Mice received a single dose of 10 Gy radiation delivered to the lungs and daily oral treatment of soy isoflavones. At different time points, mice were either processed to harvest bronchoalveolar lavage fluid for differential cell counting and lungs for flow cytometry or immunohistochemistry studies.

RESULTS

Combined soy and radiation led to a reduction in infiltration and activation of alveolar macrophages and neutrophils in both the bronchoalveolar and lung parenchyma compartments. Soy treatment protected F4/80CD11c interstitial macrophages, which are known to play an immunoregulatory role and are decreased by radiation. Furthermore, soy isoflavones reduced the levels of nitric oxide synthase 2 expression while increasing arginase-1 expression after radiation, suggesting a switch from proinflammatory M1 macrophage to an anti-inflammatory M2 macrophage phenotype. Soy also prevented the influx of activated neutrophils in lung caused by radiation.

CONCLUSIONS

Soy isoflavones inhibit the infiltration and activation of macrophages and neutrophils induced by radiation in lungs. Soy isoflavones-mediated modulation of macrophage and neutrophil responses to radiation may contribute to a mechanism of resolution of radiation-induced chronic inflammation leading to radioprotection of lung tissue.

Radiation-induced impairment in lung lymphatic vasculature

BACKGROUND

The lymphatic vasculature has been shown to play important roles in lung injury and repair, particularly in lung fibrosis. The effects of ionizing radiation on lung lymphatic vasculature have not been previously reported.

METHODS AND RESULTS

C57Bl/6 mice were immobilized in a lead shield exposing only the thoracic cavity, and were irradiated with a single dose of 14 Gy. Animals were sacrificed and lungs collected at different time points (1, 4, 8, and 16 weeks) following radiation. To identify lymphatic vessels in lung tissue sections, we used antibodies that are specific for lymphatic vessel endothelial receptor 1 (LYVE-1), a marker of lymphatic endothelial cells (LEC). To evaluate LEC cell death and oxidative damage, lung tissue sections were stained for LYVE-1 and with TUNEL staining, or 8-oxo-dG respectively. Images were imported into ImageJ v1.36b and analyzed. Compared to a non-irradiated control group, we observed a durable and progressive decrease in the density, perimeter, and area of lymphatic vessels over the study period. The decline in the density of lymphatic vessels was observed in both subpleural and interstitial lymphatics. Histopathologically discernible pulmonary fibrosis was not apparent until 16 weeks after irradiation. Furthermore, there was significantly increased LEC apoptosis and oxidative damage at one week post-irradiation that persisted at 16 weeks.

CONCLUSIONS

There is impairment of lymphatic vasculature after a single dose of ionizing radiation that precedes architectural distortion and fibrosis, suggesting important roles for the lymphatic circulation in the pathogenesis of the radiation-induced lung injury.

A prospective phase II trial of EGCG in treatment of acute radiation-induced esophagitis for stage III lung cancer

BACKGROUND

Acute radiation-induced esophagitis (ARIE) is one of main toxicities complicated by thoracic radiotherapy, influencing patients' quality of life and radiotherapy proceeding seriously. It is difficult to be cured rapidly so far. Our phase I trial preliminarily showed that EGCG may be a promising strategy in the treatment of ARIE.

MATERIALS AND METHODS

We prospectively enrolled patients with stage III lung cancer from the Shandong Tumor Hospital & Institute in China from January 2013 to September 2014. All patients received concurrent or sequential chemo-radiotherapy, or radiotherapy only. EGCG was administrated once ARIE appeared. EGCG was given with the concentration of 440μmol/L during radiotherapy and additionally two weeks after radiotherapy. RTOG score, dysphagia and pain related to esophagitis were recorded every week.

RESULTS

Thirty-seven patients with stage IIIA and IIIB lung cancer were enrolled in this trial. In comparison to the original, the RTOG score in the 1st, 2nd, 3rd, 4th, 5th week after EGCG prescription and the 1st, 2nd week after radiotherapy decreased significantly (P=0.002, 0.000, 0.000, 0.001, 0.102, 0.000, 0.000, respectively). The pain score of each week was significantly lower than the baseline (P=0.000, 0.000, 0.000, 0.000, 0.006, 0.000, 0.000, respectively).

CONCLUSION

This trial confirmed that the oral administration of EGCG is an effective and safe method to deal with ARIE. A phase III randomized controlled trial is expected to further corroborate the consequence of EGCG in ARIE treatment.

Endothelial perturbations and therapeutic strategies in normal tissue radiation damage

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

Anatomical, functional and metabolic imaging of radiation-induced lung injury using hyperpolarized MRI

MRI of hyperpolarized (129)Xe gas and (13)C-enriched substrates (e.g. pyruvate) presents an unprecedented opportunity to map anatomical, functional and metabolic changes associated with lung injury. In particular, inhaled hyperpolarized (129)Xe gas is exquisitely sensitive to changes in alveolar microanatomy and function accompanying lung inflammation through decreases in the apparent diffusion coefficient (ADC) of alveolar gas and increases in the transfer time (T(tr)) of xenon exchange from the gas and into the dissolved phase in the lung. Furthermore, metabolic changes associated with hypoxia arising from lung injury may be reflected by increases in lactate-to-pyruvate signal ratio obtained by magnetic resonance spectroscopic imaging following injection of hyperpolarized [1-(13)C]pyruvate. In this work, the application of hyperpolarized (129)Xe and (13)C MRI to radiation-induced lung injury (RILI) is reviewed and results of ADC, T(tr) and lactate-to-pyruvate signal ratio changes in a rat model of RILI are summarized. These results are consistent with conventional functional (i.e. blood gases) and histological (i.e. tissue density) changes, and correlate significantly with inflammatory cell counts (i.e. macrophages). Hyperpolarized MRI may provide an earlier indication of lung injury associated with radiotherapy of thoracic tumors, potentially allowing adjustment of treatment before the onset of severe complications and irreversible fibrosis.

Model development and use of ACE inhibitors for preclinical mitigation of radiation-induced injury to multiple organs

The NIH/NIAID initiated a countermeasure program to develop mitigators for radiation-induced injuries from a radiological attack or nuclear accident. We have previously characterized and demonstrated mitigation of single organ injuries, such as radiation pneumonitis, pulmonary fibrosis or nephropathy by angiotensin converting enzyme (ACE) inhibitors. Our current work extends this research to examine the potential for mitigating multiple organ dysfunctions occurring in the same irradiated rats. Using total body irradiation (TBI) followed by bone marrow transplant, we tested four doses of X radiation (11, 11.25, 11.5 and 12 Gy) to develop lethal late effects. We identified three of these doses (11, 11.25 and 11.5 Gy TBI) that were lethal to all irradiated rats by 160 days to test mitigation by ACE inhibitors of injury to the lungs and kidneys. In this study we tested three ACE inhibitors at doses: captopril (88 and 176 mg/m(2)/day), enalapril (18, 24 and 36 mg/m(2)/day) and fosinopril (60 mg/m(2)/day) for mitigation. Our primary end point was survival or criteria for euthanization of morbid animals. Secondary end points included breathing intervals, other assays for lung structure and function and blood urea nitrogen (BUN) to assess renal damage. We found that captopril at 176 mg/m(2)/day increased survival after 11 or 11.5 Gy TBI. Enalapril at 18-36 mg/m(2)/day improved survival at all three doses (TBI). Fosinopril at 60 mg/m(2)/day enhanced survival at a dose of 11 Gy, although no improvement was observed for pneumonitis. These results demonstrate the use of a single countermeasure to mitigate the lethal late effects in the same animal after TBI.

Effects of ionizing radiation on biological molecules--mechanisms of damage and emerging methods of detection

SIGNIFICANCE

The detrimental effects of ionizing radiation (IR) involve a highly orchestrated series of events that are amplified by endogenous signaling and culminating in oxidative damage to DNA, lipids, proteins, and many metabolites. Despite the global impact of IR, the molecular mechanisms underlying tissue damage reveal that many biomolecules are chemoselectively modified by IR.

RECENT ADVANCES

The development of high-throughput "omics" technologies for mapping DNA and protein modifications have revolutionized the study of IR effects on biological systems. Studies in cells, tissues, and biological fluids are used to identify molecular features or biomarkers of IR exposure and response and the molecular mechanisms that regulate their expression or synthesis.

CRITICAL ISSUES

In this review, chemical mechanisms are described for IR-induced modifications of biomolecules along with methods for their detection. Included with the detection methods are crucial experimental considerations and caveats for their use. Additional factors critical to the cellular response to radiation, including alterations in protein expression, metabolomics, and epigenetic factors, are also discussed.

FUTURE DIRECTIONS

Throughout the review, the synergy of combined "omics" technologies such as genomics and epigenomics, proteomics, and metabolomics is highlighted. These are anticipated to lead to new hypotheses to understand IR effects on biological systems and improve IR-based therapies.

SOD therapeutics: latest insights into their structure-activity relationships and impact on the cellular redox-based signaling pathways

SIGNIFICANCE

Superoxide dismutase (SOD) enzymes are indispensable and ubiquitous antioxidant defenses maintaining the steady-state levels of O2·(-); no wonder, thus, that their mimics are remarkably efficacious in essentially any animal model of oxidative stress injuries thus far explored.

RECENT ADVANCES

Structure-activity relationship (half-wave reduction potential [E1/2] versus log kcat), originally reported for Mn porphyrins (MnPs), is valid for any other class of SOD mimics, as it is dominated by the superoxide reduction and oxidation potential. The biocompatible E1/2 of ∼+300 mV versus normal hydrogen electrode (NHE) allows powerful SOD mimics as mild oxidants and antioxidants (alike O2·(-)) to readily traffic electrons among reactive species and signaling proteins, serving as fine mediators of redox-based signaling pathways. Based on similar thermodynamics, both SOD enzymes and their mimics undergo similar reactions, however, due to vastly different sterics, with different rate constants.

CRITICAL ISSUES

Although log kcat(O2·(-)) is a good measure of therapeutic potential of SOD mimics, discussions of their in vivo mechanisms of actions remain mostly of speculative character. Most recently, the therapeutic and mechanistic relevance of oxidation of ascorbate and glutathionylation and oxidation of protein thiols by MnP-based SOD mimics and subsequent inactivation of nuclear factor κB has been substantiated in rescuing normal and killing cancer cells. Interaction of MnPs with thiols seems to be, at least in part, involved in up-regulation of endogenous antioxidative defenses, leading to the healing of diseased cells.

FUTURE DIRECTIONS

Mechanistic explorations of single and combined therapeutic strategies, along with studies of bioavailability and translational aspects, will comprise future work in optimizing redox-active drugs.

A phase I study of concurrent chemotherapy and thoracic radiotherapy with oral epigallocatechin-3-gallate protection in patients with locally advanced stage III non-small-cell lung cancer

BACKGROUND AND PURPOSE

Patients with unresectable stage III non-small-cell lung cancer receiving concurrent chemoradiotherapy often develop esophagitis that may lead to unplanned treatment interruptions, which may severely reduce rates of locoregional tumor control and survival. No effectivetreatment that would reduce the incidence and severity of this complication has been identified up to now. Although acceleration of normal tissue protection using epigallocatechin-3-gallate (EGCG) has been reported, its actual clinical practicability remains obscure.

METHODS AND MATERIALS

This is a phase I study of EGCG in combination with standard chemoradiation in surgically unresectable stage III non-small-cell lung cancer. Chemotherapy (cisplatin and etoposide) was given concurrently with radiation. EGCG solution was swallowed three times a day after the occurrence of grade 2 esophagitis at six concentration levels and dose escalation followed a standard phase I design. Esophageal toxicity and patient-reported pain was recorded weekly.

RESULTS

Twenty-four patients with AJCC stage IIIA (six) and IIIB (eighteen) completed the course of therapy. Twelve had squamous histology, ten adenocarcinoma, and two not specified. Patients were treated in six cohorts at six dose levels of EGCG. RT was not interrupted with a median dose of 64 Gy. There were no dose-limiting toxicities reported in all EGCG dosing tiers. Dramatic regression of esophagitis to grade 0/1 was observed in 22 of 24 patients, whereas grade 2 esophagitis persisted in 2 of 24 patients at the end of radiotherapy. The pain score was also reduced from a mean of 4.58 (N=24), 1.29 (N=24), 1.42 (N=24), 0.96 (N=23) to 1.13 (N=16) every week in turn.

CONCLUSION

We conclude that the oral administration of EGCG is feasible, safe and effective. The phase II recommended concentration is 440 μmol/L.

Mapping metabolic changes associated with early Radiation Induced Lung Injury post conformal radiotherapy using hyperpolarized ¹³C-pyruvate Magnetic Resonance Spectroscopic Imaging

PURPOSE

Radiation Pneumonitis (RP) limits radiotherapy. Detection of early metabolic changes in the lungs associated with RP may provide an opportunity to adjust treatment before substantial toxicities occur. In this work, regional lactate-to-pyruvate signal ratio (lac/pyr) was quantified in rat lungs and heart following administration of hyperpolarized (13)C-pyruvate magnetic resonance imaging (MRI) at day 5, 10, 15 and 25-post conformal radiotherapy. These results were also compared to histology and blood analyses.

METHODS

The lower right lungs of 12 Sprague Dawley rats were irradiated in 2 fractions with a total dose of 18.5 Gy using a modified micro-CT system. Regional lactate and pyruvate data were acquired from three irradiated and three age-matched healthy rats at each time point on days 5, 10, 15 and 25-post radiotherapy. Arterial blood was collected from each animal prior to the (13)C-pyruvate injection and was analyzed for blood lactate concentration and arterial oxygen concentration (paO₂). Macrophage count was computed from the histology of all rat lungs.

RESULTS

A significant increase in lac/pyr was observed in both right and left lungs of the irradiated cohort compared to the healthy cohort for all time points. No increase in lac/pyr was observed in the hearts of the irradiated cohort compared to the hearts of the healthy cohorts. Blood lactate concentration and paO2 did not show a significant change between the irradiated and the healthy cohorts. Macrophage count in both right and left lungs was elevated for the irradiated cohort compared to the healthy cohort.

CONCLUSIONS

Metabolic changes associated with RP may be mapped as early as five days post conformal radiotherapy. Over the small sample size in each cohort, elevated macrophage count, consistent with early phase of inflammation was highly correlated to increases in lac/pyr in both the irradiated and unirradiated lungs. Further experiments with larger sample size may improve the confidence of this finding.

Radioprotection of lung tissue by soy isoflavones

INTRODUCTION

Radiation-induced pneumonitis and fibrosis have restricted radiotherapy for lung cancer. In a preclinical lung tumor model, soy isoflavones showed the potential to enhance radiation damage in tumor nodules and simultaneously protect normal lung from radiation injury. We have further dissected the role of soy isoflavones in the radioprotection of lung tissue.

METHODS

Naive Balb/c mice were treated with oral soy isoflavones for 3 days before and up to 4 months after radiation. Radiation was administered to the left lung at 12 Gy. Mice were monitored for toxicity and breathing rates at 2, 3, and 4 months after radiation. Lung tissues were processed for histology for in situ evaluation of response.

RESULTS

Radiation caused damage to normal hair follicles, leading to hair loss in the irradiated left thoracic area. Supplementation with soy isoflavones protected mice against radiation-induced skin injury and hair loss. Lung irradiation also caused an increase in mouse breathing rate that was more pronounced by 4 months after radiation, probably because of the late effects of radiation-induced injury to normal lung tissue. However, this effect was mitigated by soy isoflavones. Histological examination of irradiated lungs revealed a chronic inflammatory infiltration involving alveoli and bronchioles and a progressive increase in fibrosis. These adverse effects of radiation were alleviated by soy isoflavones.

CONCLUSION

Soy isoflavones given pre- and postradiation protected the lungs against adverse effects of radiation including skin injury, hair loss, increased breathing rates, inflammation, pneumonitis and fibrosis, providing evidence for a radioprotective effect of soy.

Differential effect of soy isoflavones in enhancing high intensity radiotherapy and protecting lung tissue in a pre-clinical model of lung carcinoma

BACKGROUND

Radiotherapy of locally-advanced non-small cell lung cancer is limited by radiation-induced pneumonitis and fibrosis. We have further investigated the role of soy isoflavones to improve the effect of a high intensity radiation and reduce lung damage in a pre-clinical lung tumor model.

METHODS

Human A549 NSCLC cells were injected i.v. in nude mice to generate a large tumor burden in the lungs. Mice were treated with lung irradiation at 10 Gy and with oral soy. The therapy effect on the tumor cells and surrounding lung tissue was analyzed on lung sections stained with H&E, Ki-67 and Masson's Trichrome. Pneumonitis and vascular damage were evaluated by measurements of alveolar septa and immunofluorescent staining of vessel walls.

RESULTS

Combined soy and radiation caused a significantly stronger inhibition of tumor progression compared to each modality alone in contrast to large invasive tumor nodules seen in control mice. At the same time, soy reduced radiation injury in lung tissue by decreasing pneumonitis, fibrosis and protecting alveolar septa, bronchioles and vessels.

CONCLUSIONS

These studies demonstrate a differential effect of soy isoflavones on augmenting tumor destruction induced by radiation while radioprotecting the normal lung tissue and support using soy to alleviate radiotoxicity in lung cancer.

Development of radiation pneumopathy and generalised radiological changes after radiotherapy are independent negative prognostic factors for survival in non-small cell lung cancer patients

BACKGROUND AND PURPOSE

To investigate the risk factors for radiation pneumopathy (RP) and survival rate of non-small cell lung cancer patients with RP and generalised interstitial lung changes (gen-ILC).

MATERIAL AND METHODS

A total of 147 consecutive patients receiving curative radiotherapy were analysed. RP was graded according to Common Terminology Criteria for Adverse Events v. 3. Computed tomography images were assessed for the presence of gen-ILC after radiotherapy. Univariate and multivariate analyses were performed to identify significant factors.

RESULTS

Median follow-up was 16.2 months (range 1.4-58.6). Radiological changes after radiotherapy were confined to high dose irradiation volume in 111 patients, while 31 patients developed gen-ILC. Dosimetric parameters and level of C-reactive protein before radiotherapy were significantly associated with severe RP. Development of gen-ILC (p=0.008), as well as severe RP (p=0.03) had significant negative impact on patients' survival. These two factors remained significant in the multivariate analysis.

CONCLUSIONS

Severe radiation pneumopathy and generalised radiographic changes were significant independent prognostic factors for survival. More studies on pathophysiology of radiation induced damage are necessary to fully understand the mechanisms behind it.

Effects of lipopolysaccharide on the response of C57BL/6J mice to whole thorax irradiation

BACKGROUND AND PURPOSE

Inflammatory and fibrogenic processes play a crucial role in the radiation-induced injury in the lung. The aim of the present study was to examine whether additive LPS exposure in the lung (to simulate respiratory infection) would affect pneumonitis or fibrosis associated with lung irradiation.

MATERIAL AND METHODS

Wildtype C57Bl/6J (WT-C57) and TNFα, TNFR1 and TNFR2 knockout ((-/-)) mice, in C57Bl/6J background, were given whole thorax irradiation (10 Gy) with or without post-irradiation intratracheal administration of LPS (50μg/mice). Functional deficit was examined by measuring breathing rate at various times after treatment. Real-time Reverse Transcription-Polymerase Chain Reaction (RT-PCR) and immunohistochemistry were used to analyze the protein expression and m-RNA of Interleukin-1 alpha (IL-1α), Interleukin-1 beta (IL-1β), Interleukin-6 (IL-6), Tumour Necrosis Factor alpha (TNFα) and Transforming Growth Factor beta (TGFβ) in the lung at various times after treatment. Inflammatory cells were detected by Mac-3 (macrophages) and Toluidine Blue (mast cells) staining. Collagen content was estimated by hydroxyproline (total collagen) and Sircol assay (soluble collagen). Levels of oxidative damage were assessed by 8-hydroxy-2-deoxyguanosine (8-OHdG) staining.

RESULTS

LPS exposure significantly attenuated the breathing rate increases following irradiation of WT-C57, TNFR1(-/-) and TNFR2(-/-)mice and to a lesser extent in TNFα(-/-) mice. Collagen content was significantly reduced after LPS treatment in WT-C57, TNFR1(-/-) and TNFα(-/-) mice and there was a trend in TNFR2(-/-) mice. Similarly there were lower levels of inflammatory cells and cytokines in the LPS treated mice.

CONCLUSIONS

This study reveals a mitigating effect of early exposure to LPS on injury caused by irradiation on lungs of C57Bl mice. The results suggest that immediate infection post irradiation may not impact lung response negatively in radiation-accident victims, however, further studies are required in different animal models, and with specific infectious agents, to confirm and extend our findings.

Oxidative stress in apoptosis and cancer: an update

The oxygen paradox tells us that oxygen is both necessary for aerobic life and toxic to all life forms. Reactive oxygen species (ROS) touch every biological and medical discipline, especially those involving proliferative status, supporting the idea that active oxygen may be increased in tumor cells. In fact, metabolism of oxygen and the resulting toxic byproducts can cause cancer and death. Efforts to counteract the damage caused by ROS are gaining acceptance as a basis for novel therapeutic approaches, and the field of prevention of cancer is experiencing an upsurge of interest in medically useful antioxidants. Apoptosis is an important means of regulating cell numbers in the developing cell system, but it is so important that it must be controlled. Normal cell death in homeostasis of multicellular organisms is mediated through tightly regulated apoptotic pathways that involve oxidative stress regulation. Defective signaling through these pathways can contribute to both unbalance in apoptosis and development of cancer. Finally, in this review, we discuss new knowledge about recent tools that provide powerful antioxidant strategies, and designing methods to deliver to target cells, in the prevention and treatment of cancer.

Normal tissue protection for improving radiotherapy: Where are the Gaps?

Any tumor could be controlled by radiation therapy if sufficient dose were delivered to all tumor cells. Although technological advances in physical treatment delivery have been developed to allow more radiation dose conformity, normal tissues are invariably included in any radiation field within the tumor volume and also as part of the exit and entrance doses relevant for particle therapy. Mechanisms of normal tissue injury and related biomarkers are now being investigated, facilitating the discovery and development of a next generation of radiation protectors and mitigators. Bringing recent research advances stimulated by development of radiation countermeasures for mass casualties, to clinical cancer care requires understanding the impact of protectors and mitigators on tumor response. These may include treatments that modify cellular damage and death processes, inflammation, alteration of normal flora, wound healing, tissue regeneration and others, specifically to counter cancer site-specific adverse effects to improve outcome of radiation therapy. Such advances in knowledge of tissue and organ biology, mechanisms of injury, development of predictive biomarkers and mechanisms of radioprotection have re-energized the field of normal tissue protection and mitigation. Since various factors, including organ sensitivity to radiation, cellular turnover rate, and differences in mechanisms of injury manifestation and damage response vary among tissues, successful development of radioprotectors/mitigators/treatments may require multiple approaches to address cancer site specific needs. In this review, we discuss examples of important adverse effects of radiotherapy (acute and intermediate to late occurring, when it is delivered either alone or in conjunction with chemotherapy, and important limitations in the current approaches of using radioprotectors and/or mitigators for improving radiation therapy. Also, we are providing general concepts for drug development for improving radiation therapy.

Mitigation of lung injury after accidental exposure to radiation

There is a serious need to develop effective mitigators against accidental radiation exposures. In radiation accidents, many people may receive nonuniform whole-body or partial-body irradiation. The lung is one of the more radiosensitive organs, demonstrating pneumonitis and fibrosis that are believed to develop at least partially because of radiation-induced chronic inflammation. Here we addressed the crucial questions of how damage to the lung can be mitigated and whether the response is affected by irradiation to the rest of the body. We examined the widely used dietary supplement genistein given at two dietary levels (750 or 3750 mg/kg) to Fischer rats irradiated with 12 Gy to the lung or 8 Gy to the lung + 4 Gy to the whole body excluding the head and tail (whole torso). We found that genistein had promising mitigating effects on oxidative damage, pneumonitis and fibrosis even at late times (36 weeks) when drug treatment was initiated 1 week after irradiation and stopped at 28 weeks postirradiation. The higher dose of genistein showed no greater beneficial effect. Combined lung and whole-torso irradiation caused more lung-related severe morbidity resulting in euthanasia of the animals than lung irradiation alone.