Stereotactic lung irradiation in mice promotes long-term senescence and lung injury.
- 作者列表："Soysouvanh F","Benadjaoud MA","Santos MD","Mondini M","Lavigne J","Bertho A","Buard V","Tarlet G","Adnot S","Deutsch E","Guipaud O","Paget V","François A","Milliat F
PURPOSE:Lung cancer will be treated more and more using Stereotactic Body Radiation Therapy (SBRT) and preclinical research to model long-term toxicity of ablative doses of radiation is crucial. Stereotactic lung irradiation of a small volume can induce radiation pneumonitis and fibrosis in normal tissues. METHODS AND MATERIALS:Senescence has been reported to contribute to lung fibrosis and we investigated in vivo the effects of ablative doses of ionising radiation on senescence-associated processes. The left lung of p16INK4a-LUC knock-in mice was exposed to a single dose or fractionated radiation doses in a millimetric volume using a small animal radiation research platform. RESULTS:Single or fractionated ablative radiation induces acute and very long-term p16INK4a activation in the irradiated lung target volume associated with lung injury. We observed a panel of heterogeneous senescent cells including pneumocytes, macrophages and endothelial cells that accumulated around the radiation-induced lung focal lesion suggesting that different senescent cell types may contribute to radiation injury. CONCLUSION:This work provides important information on the long-term effects of ablative radiation doses in the normal lung and strongly suggests that stress-induced senescence is involved in SBRT-induced late fibrosis.
目的: 立体定向放射治疗 (SBRT) 将越来越多地用于肺癌的治疗，消融剂量放射的长期毒性模型的临床前研究至关重要。小体积立体定向肺照射可诱发放射性肺炎和正常组织纤维化。 方法和材料: 据报道，衰老可促进肺纤维化，我们在体内研究了消融剂量的电离辐射对衰老相关过程的影响。使用小动物辐射研究平台，将 p16INK4a-LUC 敲入小鼠的左肺暴露于单剂量或分次辐射剂量 (毫单位)。 结果: 单次或分次消融辐射诱导照射肺靶体积中急性和非常长期的 p16INK4a 激活与肺损伤相关。我们观察到一组异质性衰老细胞，包括肺细胞、巨噬细胞和内皮细胞，聚集在辐射诱导的肺局灶性病变周围，提示不同的衰老细胞类型可能有助于辐射损伤。 结论: 这项工作提供了正常肺消融辐射剂量的长期影响的重要信息，并强烈提示应激诱导的衰老参与 SBRT 诱导的晚期纤维化。
METHODS:BACKGROUND AND PURPOSE:A critical role for sphingosine kinase/sphingosine-1-phosphate (S1P) pathway in the control of airway function has been demonstrated in respiratory diseases. Here, we address S1P contribution in a mouse model of mild chronic obstructive pulmonary disease (COPD). EXPERIMENTAL APPROACH:C57BL/6J mice have been exposed to room air or cigarette smoke up to 11 months and killed at different time points. Functional and molecular studies have been performed. KEY RESULTS:Cigarette smoke caused emphysematous changes throughout the lung parenchyma coupled to a progressive collagen deposition in both peribronchiolar and peribronchial areas. The high and low airways showed an increased reactivity to cholinergic stimulation and α-smooth muscle actin overexpression. Similarly, an increase in airway reactivity and lung resistances following S1P challenge occurred in smoking mice. A high expression of S1P, Sph-K2 , and S1P receptors (S1P2 and S1P3 ) has been detected in the lung of smoking mice. Sphingosine kinases inhibition reversed the increased cholinergic response in airways of smoking mice. CONCLUSIONS AND IMPLICATIONS:S1P signalling up-regulation follows the disease progression in smoking mice and is involved in the development of airway hyperresponsiveness. Our study defines a therapeutic potential for S1P inhibitors in management of airways hyperresponsiveness associated to emphysema in smokers with both asthma and COPD.
METHODS::The interim results from this 90-day multi-dose, inhalation toxicology study with life-time post-exposure observation has shown an important fundamental difference in persistence and pathological response in the lung between brake dust derived from brake-pads manufactured with chrysotile, TiO2 or chrysotile alone in comparison to the amphiboles, crocidolite and amosite asbestos. In the brake dust exposure groups no significant pathological response was observed at any time. Slight macrophage accumulation of particles was noted. Wagner-scores, were from 1 to 2 (1 = air-control group) and were similar to the TiO2 group. Chrysotile being biodegradable, shows a weakening of its matrix and breaking into short fibers & particles that can be cleared by alveolar macrophages and continued dissolution. In the chrysotile exposure groups, particle laden macrophage accumulation was noted leading to a slight interstitial inflammatory response (Wagner-score 1-3). There was no peribronchiolar inflammation and occasional very slight interstitial fibrosis. The histopathology and the confocal analyses clearly differentiate the pathological response from amphibole asbestos, crocidolite and amosite, compared to that from the brake dust and chrysotile. Both crocidolite and amosite induced persistent inflammation, microgranulomas, and fibrosis (Wagner-scores 4), which persisted through the post exposure period. The confocal microscopy of the lung and snap-frozen chestwalls quantified the extensive inflammatory response and collagen development in the lung and on the visceral and parietal surfaces. The interim results reported here, provide a clear basis for differentiating the effects from brake dust exposure from those following amphibole asbestos exposure. The subsequent results through life-time post-exposure will follow.
METHODS::The respiratory tract is lined by a pseudo-stratified epithelium from the nose to terminal bronchioles. This first line of defense of the lung against external stress includes five main cell types: basal, suprabasal, club, goblet and multiciliated cells, as well as rare cells such as ionocytes, neuroendocrine and tuft/brush cells. At homeostasis, this epithelium self-renews at low rate but is able of fast regeneration upon damage. Airway epithelial cell lineages during regeneration have been investigated in the mouse by genetic labeling, mainly after injuring the epithelium with noxious agents. From these approaches, basal cells have been identified as progenitors of club, goblet and multiciliated cells, but also of ionocytes and neuroendocrine cells. Single-cell RNA sequencing, coupled to lineage inference algorithms, has independently allowed the establishment of comprehensive pictures of cell lineage relationships in both mouse and human. In line with genetic tracing experiments in mouse trachea, studies using single-cell RNA sequencing (RNAseq) have shown that basal cells first differentiate into club cells, which in turn mature into goblet cells or differentiate into multiciliated cells. In the human airway epithelium, single-cell RNAseq has identified novel intermediate populations such as deuterosomal cells, 'hybrid' mucous-multiciliated cells and progenitors of rare cells. Novel differentiation dynamics, such as a transition from goblet to multiciliated cells have also been discovered. The future of cell lineage relationships in the respiratory tract now resides in the combination of genetic labeling approaches with single-cell RNAseq to establish, in a definitive manner, the hallmarks of cellular lineages in normal and pathological situations.