Intercellular communication between alveolar epithelial cells and macrophages.
- 作者列表："Beckmann A","Grissmer A","Meier C","Tschernig T
BACKGROUND:The alveolus in the lung tissue is an extremely vulnerable site. Alveolar macrophages control this micro-environment both in states of health and illnesssuch as acute lung injury and infection. It has been reported in mice in vivo that intercellular communication between alveolar macrophages and alveolar epithelial cells is mediated by gap junctions. However, little is known about thismicro-environment in human cells. METHODS:Since this gap junctional intercellular communication is hard to investigate in human tissues, a co-culture model of two human cell lines, one of epithelial and one of macrophage origin, was used. Immunoblot analysis, freeze fracture replica immunolabeling and electron microscopy were performed. RESULTS:Connexin (Cx) 43 protein expression as well as ultrastructurally defined Cx43 gap junctions were detected in co-cultures, yielding evidence of intercellular gap junctions between human alveolar cells of two distinct entities. CONCLUSION:Alveolar macrophages possibly have direct access to the alveolar epithelium via gap junctions in humans, enabling the orchestration of the microenvironment in physiology and disease states.
背景: 肺组织中的肺泡是一个极其脆弱的部位。肺泡巨噬细胞控制这种微环境，无论是在健康状态还是在疾病状态下，如急性肺损伤和感染。在小鼠体内已有报道肺泡巨噬细胞与肺泡上皮细胞间的细胞间通讯是由缝隙连接介导的。然而，人们对人体细胞中的这种微环境知之甚少。 方法: 由于这种缝隙连接细胞间通讯在人体组织中很难研究，采用上皮细胞和巨噬细胞来源的两种人类细胞系的共培养模型。进行免疫印迹分析、冷冻断裂复制免疫标记和电子显微镜检查。 结果: 在共培养中检测到连接蛋白 (Cx) 43 蛋白表达以及超微结构定义的 Cx43 间隙连接，产生了两种不同实体的人肺泡细胞之间细胞间间隙连接的证据。 结论: 肺泡巨噬细胞可能通过缝隙连接直接进入肺泡上皮，在生理和疾病状态下实现微环境的协调。
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.