Exophilin-5 regulates allergic airway inflammation by controlling IL-33-mediated Th2 responses.
Exophilin-5 通过控制 IL-33-介导的Th2 反应调节过敏性气道炎症。
- 作者列表："Okunishi K","Wang H","Suzukawa M","Ishizaki R","Kobayashi E","Kihara M","Abe T","Miyazaki JI","Horie M","Saito A","Saito H","Nakae S","Izumi T
:A common variant in the RAB27A gene in adults was recently found to be associated with the fractional exhaled nitric oxide level, a marker of eosinophilic airway inflammation. The small GTPase, Rab27, is known to regulate intracellular vesicle traffic, although its role in allergic responses is unclear. We demonstrated that exophilin-5, a Rab27 binding protein, was predominantly expressed in both the major IL-33 producers, lung epithelial cells, and the specialized IL-5 and IL-13 producers in CD44highCXCR3lowCD62Llow pathogenic T helper 2 (Th2) cell population in mice. Exophilin-5 deficiency increased stimulant-dependent damages and IL-33 secretion of lung epithelial cells. Moreover, it enhanced IL-5 and IL-13 production in response to TCR and IL-33 stimulation from a specific subset of pathogenic Th2 cells that expresses a high level of IL-33 receptor, which exacerbated allergic airway inflammation in a mouse model of asthma. Mechanistically, exophilin-5 regulates extracellular superoxide release, intracellular ROS production, and phosphoinositide 3-kinase activity by controlling intracellular traffic of Nox2-containing vesicles, which seems to prevent the overactivation of pathogenic Th2 cells mediated by IL-33. This is the first report to establish the significance of Rab27-related protein exophilin-5 in the development of allergic airway inflammation, and provides new insights into the pathophysiology of asthma.
: 最近发现成人 RAB27A 基因的一个常见变异与呼出气一氧化氮水平相关，这是嗜酸性粒细胞气道炎症的标志。已知小 gtp 酶 Rab27 调节细胞内囊泡交通，尽管其在过敏反应中的作用尚不清楚。我们证明了 exophilin-5，一种 Rab27 结合蛋白，主要表达于主要 IL-33 产物、肺上皮细胞以及 CD44highCXCR3lowCD62Llow 致病性 T 辅助细胞 2 (Th2) 中的专门 IL-5 和 IL-13 产物中小鼠细胞群。Exophilin-5 缺乏增加了兴奋剂依赖性损伤和肺上皮细胞分泌 IL-33。此外，它增强了 IL-5 和 IL-13 的生产响应 TCR 和 IL-33 的刺激从一个特定亚群的致病性 Th2 细胞表达高水平的 IL-33 受体,这加剧了哮喘小鼠模型的过敏性气道炎症。从机制上讲，exophilin-5 通过控制细胞内超氧化物小泡的流量来调节细胞外超氧化物释放、细胞内 ROS 产生和磷酸肌醇 3-激酶活性，这似乎可以防止 包含Nox2介导的致病性 Th2 细胞的过度激活。本文首次报道了 Rab27相关的蛋白 exophilin-5 在过敏性气道炎症发生发展中的意义，为哮喘的病理生理学研究提供了新的思路。
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.