Hydrogen therapy promotes macrophage polarization to the M2 subtype in radiation lung injury by inhibiting the NF-κB signalling pathway.

Background: Radiotherapy has become a standard treatment for chest tumors, but a common complication of radiotherapy is radiation lung injury. Currently, there is still a lack of effective treatment for radiation lung injury. Methods: A mouse model of radioactive lung injury (RILI) was constructed and then treated with different cycles of hydrogen inhalation. Lung function tests were performed to detect changes in lung function.HE staining was used to detect pathological changes in lung tissue. Immunofluorescence staining was used to detect the polarization of macrophages in lung tissue. Immunohistochemistry was used to detect changes in cytokine expression in lung tissues. Western Blot was used to detect the expression of proteins related to the NF-κB signalling pathway. Results: Lung function test results showed that lung function decreased in the model group and improved in the treatment group.HE staining showed that inflammatory response was evident in the model group and decreased in the treatment group. Immunohistochemistry results showed that the expression of pro-inflammatory factors was significantly higher in the model group, and the expression of pro-inflammatory factors was significantly higher in the treatment group. The expression of pro-inflammatory factors in the treatment group was significantly lower than that in the model group, and the expression of anti-inflammatory factors in the treatment group was higher than that in the model group. Immunofluorescence showed that the expression of M1 subtype macrophages was up-regulated in the model group and down-regulated in the treatment group. The expression of M2 subtype macrophages was up-regulated in the treatment group relative to the model group. Western Blot showed that P-NF-κB p65/NF-κB p65 was significantly increased in the model group, and P-NF-κB p65/NF-κB p65 was decreased in the treatment group. Conclusion: Hydrogen therapy promotes macrophage polarization from M1 to M2 subtypes by inhibiting the NF-κB signalling pathway, thereby attenuating the inflammatory response to radiation lung injury.

UCHL1 Regulates Radiation Lung Injury via Sphingosine Kinase-1.

GADD45a is a gene we previously reported as a mediator of responses to acute lung injury. GADD45a-/- mice express decreased Akt and increased Akt ubiquitination due to the reduced expression of UCHL1 (ubiquitin c-terminal hydrolase L1), a deubiquitinating enzyme, while GADD45a-/- mice have increased their susceptibility to radiation-induced lung injury (RILI). Separately, we have reported a role for sphingolipids in RILI, evidenced by the increased RILI susceptibility of SphK1-/- (sphingosine kinase 1) mice. A mechanistic link between UCHL1 and sphingolipid signaling in RILI is suggested by the known polyubiquitination of SphK1. Thus, we hypothesized that the regulation of SphK1 ubiquitination by UCHL1 mediates RILI. Initially, human lung endothelial cells (EC) subjected to radiation demonstrated a significant upregulation of UCHL1 and SphK1. The ubiquitination of EC SphK1 after radiation was confirmed via the immunoprecipitation of SphK1 and Western blotting for ubiquitin. Further, EC transfected with siRNA specifically for UCHL1 or pretreated with LDN-5744, as a UCHL1 inhibitor, prior to radiation were noted to have decreased ubiquitinated SphK1 in both conditions. Further, the inhibition of UCHL1 attenuated sphingolipid-mediated EC barrier enhancement was measured by transendothelial electrical resistance. Finally, LDN pretreatment significantly augmented murine RILI severity. Our data support the fact that the regulation of SphK1 expression after radiation is mediated by UCHL1. The modulation of UCHL1 affecting sphingolipid signaling may represent a novel RILI therapeutic strategy.

Prophylactic Vitamin C Attenuates Radiation-induced Lung Injury by Modulating Macrophage Polarization and Alveolar Epithelial Cell Apoptosis / 中国生物化学与分子生物学报

With the ongoing epidemic of the Coronavirus disease in China and the widespread development of radiotherapy, radiation-induced lung injury has gradually become a clinical problem that has attracted much attention. The pathogenesis of radiation-induced lung injury is complex, involving an imbalance in the polarization state of alveolar macrophages and an upregulation of alveolar epithelial cell apoptosis. Previous studies have shown that vitamin C is an important antioxidant substance, and preventive use of vitamin C can effectively treat acute lung injury. However, whether prophylactic use of vitamin C can effectively prevent or treat lung injury caused by radioactive substances, and its specific molecular mechanism remains to be studied. The purpose of this study is to investigate whether the prophylactic use of vitamin C to treat the alveolar macrophage cell line RAW 264. 7 and human lung epithelial cells BEAS-2B can effectively control the abnormal polarization of macrophages and the abnormal apoptosis of lung epithelial cells. This study found that after 4 weeks and 8 weeks of radioactive X-ray irradiation, the expression of macrophage M1 polarization state markers such as iNOS was significantly up-regulated (P< 0. 05), and preventive use of vitamin C to treat macrophages and lung epithelial cells can alleviate the polarization state disorder of macrophages and the apoptosis of alveolar epithelial cells caused by external radiation exposure, which is manifested in the down-regulation of the expression of Cleaved Caspase3. In addition, the preventive application of vitamin C treatment can inhibit the MAPK signaling pathway activated by external radiation exposure. Further experimental results showed that the inhibition of the MAPK pathway is the key to inhibiting the M1 polarization of macrophages and the apoptosis of lung epithelial cells. In summary, our findings suggest that vitamin C may play a protective role in acute radiation-induced lung injury by inhibiting macrophage M1 polarization/ promoting macrophage M2 polarization and alleviating alveolar epithelial cell apoptosis. This study will help to better understand the process and mechanism of the preventive effect of vitamin C, a common vitamin, on radiation-induced lung injury.

Prevention effect of low dose pre-irradiation on irradiation induced lung injury in mice and its possible mechanism / 中华放射医学与防护杂志

Objective:To evaluate the prevention effect of low dose pre-irradiation on irradiation-induced lung injury and its possible mechanism.Methods:Totally 320 6-week-old female C57BL/6j mice were divided into control (0 Gy), low-dose (0.5 Gy), high-dose (20 Gy) and low-dose pre-radiation(0.5 Gy+ 20 Gy)groups by the random number method, with 80 mice in each group. The mice in the low-dose and low-dose pre-irradiation groups were placed in the immobilization device under full consciousness and subjected to 0.5 Gy X-ray whole-body irradiation. 2 weeks later, the 0.5 Gy pre-irradiated mice were anesthetized and subjected to 20 Gy X-rays on chest, as the pre-radiation plus high dose radiation group. The mice in the control group were irradiated with mock irradiation (0 Gy). All mice were terminated at designed time points (24 h, 1 month, 3 months and 5 months) after completion of the irradiation schedule, with 20 mice/group at each time point. Then, lung tissues were taken from mice, and pathological changes were observed by hematoxylin-eosin (HE) staining and Masson′s trichrome staining. RT-qPCR and Western blot were used to detect the expressions of mRNAs and proteins of pulmonary fibrosis-related factors.Results:Pathological changes were observed in the lung tissues 1 month after a single high-dose 20 Gy irradiation, mainly including radiation pneumonitis and a small amount of collagen accumulation, which was more serious than low-dose pre-irradiation group, and these pathological changes became more severe when the time after irradiation increased. Meanwhile, the mRNA and protein levels of proSP-C and HOPX in the low-dose pre-irradiation group were higher than those in the high-dose group, except for proSP-C protein expression at 3 and 5 months post-irradiation. A more significant change was that the mRNA level of TGF-β1 in the high-dose group was 5.8-13.6 times higher than that in the other groups at 5 months after irradiation, as well as β-catenin mRNA ( t=4.22, 5.11, P<0.05). At the same time, in the early period (24 h and 1 month) post-irradiation, the level of vimentin protein in the low-dose pre-irradiation group was significantly higher than that in the high-dose group ( t=6.54, 4.28, P<0.05). Conclusions:When the mice were pre-irradiated with 0.5 Gy X-rays, an adaptive protective response was induced in lung tissues, resulting in the tolerance to subsequent high dose irradiation.

Sphingolipids as a Novel Therapeutic Target in Radiation-Induced Lung Injury.

Radiation-induced lung injury (RILI) is a potential complication of thoracic radiotherapy that can result in pneumonitis or pulmonary fibrosis and is associated with significant morbidity and mortality. The pathobiology of RILI is complex and includes the generation of free radicals and DNA damage that precipitate oxidative stress, endothelial cell (EC), and epithelial cell injury and inflammation. While the cellular events involved continue to be elucidated and characterized, targeted and effective therapies for RILI remain elusive. Sphingolipids are known to mediate EC function including many of the cell signaling events associated with the elaboration of RILI. Sphingosine-1-phosphate (S1P) and S1P analogs enhance EC barrier function in vitro and have demonstrated significant protective effects in vivo in a variety of acute lung injury models including RILI. Similarly, statin drugs that have pleiotropic effects that include upregulation of EC S1P receptor 1 (S1PR1) have been found to be strongly protective in a small animal RILI model. Thus, targeting of EC sphingosine signaling, either directly or indirectly, to augment EC function and thereby attenuate EC permeability and inflammatory responses, represents a novel and promising therapeutic strategy for the prevention or treatment of RILI.

A radiation ulcer that required partial lung resection and recurred in a small residual area of ectopic calcification.

INTRODUCTION AND IMPORTANCE: Surgery for chest radiation ulcers must involve appropriate wide margins, but it is not usually possible to remove all radiation-damaged tissue. Therefore, it is difficult to determine how extensive such surgery should be. There have not been any reports about the recurrence of such ulcers years after surgery. In addition, how ectopic calcification should be treated and the need for partial lung resection in such cases have not been fully elucidated. We report the case of a patient who had a large severe radiation ulcer. CASE PRESENTATION: A 46-year-old patient underwent cancer resection and received postoperative radiotherapy. Seventeen years later, a chest ulcer developed. Computed tomography showed a depression of the lung parenchyma, which exhibited old radiation pneumonitis, and pathological fractures of the ribs around the ulcer. We excised a region of skin that exhibited a clear change in color together with an additional 1 cm around this area including 4 ribs and grossly calcified area. The lung was partially resected because of strong adhesion, and the chest wall was reconstructed. Two small calcifications remained and which required additional surgery several years later. CLINICAL DISCUSSION: Since multiple surgeries were required, we consider that more generous resection margins were necessary from the beginning. CONCLUSION: In such cases, it might be necessary to perform more extensive surgery that includes asymptomatic calcified areas.

Study of the value of SPECT lung perfusion imaging in optimizing lung cancer radiotherapy plan for lung function protection / 中华放射肿瘤学杂志

Objective:To evaluate the application value of SPECT lung perfusion imaging in guiding radiotherapy path, optimizing the radiotherapy plan for lung cancer and protecting lung function during radiotherapy for locally advanced non-small cell lung cancer.Methods:In this study, 84 patients with stage Ⅲ non-resectable non-small cell lung cancer were randomly divided into the control group ( n=44) and observation group ( n=40). In the control group, radiotherapy plan based on conventional CT images was delivered, and two plans based on the lung function information suggested by conventional CT and SPECT lung perfusion imaging: P1 and P2 were given in the observation group. All patients in the observation group were finally treated according to the P2 plan. The incidence of radiation pneumonitis, and changes in lung function before and after radiotherapy were statistically compared between two groups. The dose-volume parameters of P1 and P2 were statistically compared. Results:After the plan was optimized, the incidence of radiation pneumonitis in the observation group was significantly reduced and the decline of lung function was significantly improved (both P≤0.001). The functional dose parameters were significantly improved in the P2 plans (both P<0.05), whereas the irradiation dose of organs at risk did not significantly change ( P>0.05). Conclusion:SPECT lung perfusion imaging optimizes the intensity-modulated radiotherapy plan, which can reduce the functional lung dose and increase the tumor radiotherapy dose without increasing the irradiation dose of other organs at risk.

Hypo-CpG methylation controls PTEN expression and cell apoptosis in irradiated lung.

PURPOSE: The current study was designed to address our hypothesis that oxidative stress secondary to the ionizing event upregulates phosphatase and tensin homolog (PTEN) mRNA and protein in the lungs of C57BL/6J mice through oxidative DNA damage resulting in CpG hypomethylation in the PTEN promoter. METHODS: Fibrosis-prone C57BL/6J mice were exposed to 0 or 15 Gy of 320 kVp X-rays to the whole thorax. Lung tissue was serially harvested at time points between one day and six months postirradiation. Tissue levels of PTEN mRNA, total protein, and phosphorylated PTEN, as well as CpG methylation of the PTEN promoter, expression of DNA methyltransferases 1 (Dnmt1) and 3a (Dnmt3a), NADPH oxidase 4 (Nox4) protein expression, and DNA damage levels were measured. The induction of DNA damage and global methylation changes were also examined in hydrogen peroxide (H2O2)-treated human umbilical vein endothelial cells (HUVECs) and human bronchial epithelial cells in vitro. RESULTS: These experiments demonstrate that PTEN mRNA and protein, Nox4 protein, and DNA damage levels increase continuously from one day to six months following radiation exposure. Elevated PTEN transcription and translation are likely the result of the observed decrease in CpG methylation of the PTEN promoter region. This finding is not consistent with the observed increase in Dnmt1 and Dnmt3a protein expression, implicating an alternative mechanism as the driving force behind hypomethylation. In vitro results provide evidence that H2O2 can induce DNA damage and affect DNA methylation status. The Mn porphyrin-based superoxide dismutase (SOD) mimic MnTnHEx-2-PyP(5+ )exhibited partial rescue from radiation-induced hypomethylation. CONCLUSIONS: Taken together, these data suggest that reactive oxygen species (ROS)-induced DNA damage results in hypomethylation of the PTEN promoter, upregulation of PTEN mRNA and protein, and a subsequent increase in apoptosis in irradiated lung tissue.

Expression of Interleukin-6 in Radiation Induced Lung Damage / 대한산업의학회지

Ionizing radiation has proved to be most valuable in clinical diagnosis and radiotherapy. And also it is used very common in industries especially such as industrial radiography, atomic energy plant, inspectoring by gamma-ray, etc. However, inadvertent exposure to relatively high doses of ionizing radiation is capable of injuring and killing cells. The lungs, because of their rich vascularization, are vulnerable to radiation injury. It is now known that IL-6 is a pleiotrophic cytokine produced by various cells that regulates the immune reponses, acute phage reactions. We performed the immunohistochemical staining of IL-6 on radiation induced lung injury by duration, to clarify the role of IL-6 in tissue damage. IL-6 was strongly expressed in early phase of radiation from alveolar macrophages and damaged endothelial cells. These findings not only have important implications for increasing our understanding of mechanisms of radiation lung injury but they also have an impact on strategies for diagnosis and therapy of radiation damage.