Cooperativity between Stenotrophomonas maltophilia and Pseudomonas aeruginosa during polymicrobial airway infections.
- 作者列表："McDaniel MS","Schoeb T","Swords WE
:Stenotrophomonas maltophilia is a Gram-negative bacterium found ubiquitously in the environment that has historically been regarded as nonpathogenic. S. maltophilia is increasingly observed in patient sputa in cystic fibrosis (CF), and while existing epidemiology indicates that patients with S. maltophilia have poorer diagnoses, its clinical significance remains unclear. Moreover, as multidrug resistance is common among S. maltophilia isolates, treatment options for these infections may be limited. Here we investigated the pathogenicity of S. maltophilia alone and during polymicrobial infection with Pseudomonas aeruginosa. Colonization, persistence, and virulence of S. maltophilia were assessed in experimental respiratory infections of mice. The results of this study indicate that S. maltophilia transiently colonizes the lung accompanied by significant weight loss and immune cell infiltration, and the expression of early inflammatory markers including IL-6, IL-1α, and TNF-α. Importantly, polymicrobial infection with P. aeruginosa elicited significantly higher S. maltophilia counts in bronchoalveolar lavages and lung tissue homogenates. This increase in bacterial load was directly correlated with the density of the P. aeruginosa population, and required viable P. aeruginosa bacteria. Microscopic analysis of biofilms formed in vitro revealed that S. maltophilia formed well-integrated biofilms with P. aeruginosa, and these organisms colocalize in the lung during dual species infection. Based on these results, we conclude that active cellular processes by P. aeruginosa afford significant benefit to S. maltophilia during polymicrobial infections. Further, these results indicate that S. maltophilia may have clinical significance in respiratory infections.
: 嗜麦芽窄食单胞菌是一种广泛存在于环境中的革兰氏阴性细菌，历来被认为是非致病性的。在囊性纤维化 (CF) 患者痰液中越来越多地观察到嗜麦芽窄食单胞菌，虽然现有流行病学学表明嗜麦芽窄食单胞菌患者的诊断较差，但其临床意义仍不清楚。此外，由于多重耐药在嗜麦芽窄食单胞菌分离株中很常见，这些感染的治疗选择可能有限。在这里，我们调查了嗜麦芽窄食单胞菌和铜绿假单胞菌多微生物感染期间的致病性。在小鼠实验性呼吸道感染中评估嗜麦芽窄食单胞菌的定植、持久性和毒力。本研究结果表明 S.嗜麦芽窄食单胞菌短暂定植于肺内，伴有明显的体重减轻和免疫细胞浸润，早期炎症标志物包括 IL-6 、 il-1 α 和 TNF-α 的表达。重要的是，铜绿假单胞菌多微生物感染在支气管肺泡灌洗和肺组织匀浆中引起显著较高的嗜麦芽窄食单胞菌计数。细菌负荷的增加与铜绿假单胞菌种群的密度直接相关，需要活的铜绿假单胞菌。对体外形成的生物膜进行显微分析发现，嗜麦芽窄食单胞菌与铜绿假单胞菌形成了整合良好的生物膜，这些生物在双种属感染期间在肺内共定位。基于这些结果，我们得出结论，铜绿假单胞菌的活性细胞过程在多微生物感染期间对嗜麦芽窄食单胞菌有显著的益处。此外，这些结果表明嗜麦芽窄食单胞菌可能在呼吸道感染中具有临床意义。
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.