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在肺部感染期间阻断 HXA 介导的中性粒细胞弹性蛋白酶释放可限制肺上皮屏障的破坏和菌血症。

Blocking HXA-mediated neutrophil elastase release during lung infection limits pulmonary epithelial barrier disruption and bacteremia.

机构信息

Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA.

Graduate Program in Immunology, Tufts Graduate School of Biomedical Sciences, Boston, Massachusetts, USA.

出版信息

mBio. 2024 Sep 11;15(9):e0185624. doi: 10.1128/mbio.01856-24. Epub 2024 Aug 9.

Abstract

(), a leading cause of community-acquired pneumonia, can spread from the lung into the bloodstream to cause septicemia and meningitis, with a concomitant threefold increase in mortality. Limitations in vaccine efficacy and a rise in antimicrobial resistance have spurred searches for host-directed therapies that target pathogenic immune processes. Polymorphonuclear leukocytes (PMNs) are essential for infection control but can also promote tissue damage and pathogen spread. The major virulence factor, pneumolysin, triggers acute inflammation by stimulating the 12-lipoxygenase (12-LOX) eicosanoid synthesis pathway in epithelial cells. This pathway is required for systemic spread in a mouse pneumonia model and produces a number of bioactive lipids, including hepoxilin A3 (HXA), a hydroxy epoxide PMN chemoattractant that has been hypothesized to facilitate breach of mucosal barriers. To understand how 12-LOX-dependent inflammation promotes dissemination during lung infection and dissemination, we utilized bronchial stem cell-derived air-liquid interface cultures that lack this enzyme to show that HXA methyl ester (HXA-ME) is sufficient to promote basolateral-to-apical PMN transmigration, monolayer disruption, and concomitant barrier breach. In contrast, PMN transmigration in response to the non-eicosanoid chemoattractant N-formyl-L-methionyl-L-leucyl-phenylalanine (fMLP) did not lead to epithelial disruption or bacterial translocation. Correspondingly, HXA-ME but not fMLP increased the release of neutrophil elastase (NE) from -infected PMNs. Pharmacologic blockade of NE secretion or activity diminished epithelial barrier disruption and bacteremia after pulmonary challenge of mice. Thus, HXA promotes barrier-disrupting PMN transmigration and NE release, pathological events that can be targeted to curtail systemic disease following pneumococcal pneumonia.IMPORTANCE (), a leading cause of pneumonia, can spread from the lung into the bloodstream to cause systemic disease. Limitations in vaccine efficacy and a rise in antimicrobial resistance have spurred searches for host-directed therapies that limit pathologic host immune responses to . Excessive polymorphonuclear leukocyte (PMN) infiltration into -infected airways promotes systemic disease. Using stem cell-derived respiratory cultures that reflect bona fide lung epithelium, we identified eicosanoid hepoxilin A3 as a critical pulmonary PMN chemoattractant that is sufficient to drive PMN-mediated epithelial damage by inducing the release of neutrophil elastase. Inhibition of the release or activity of this protease in mice limited epithelial barrier disruption and bacterial dissemination, suggesting a new host-directed treatment for lung infection.

摘要

肺炎链球菌()是社区获得性肺炎的主要病因之一,它可以从肺部扩散到血液中,引起败血症和脑膜炎,死亡率增加三倍。疫苗效力的限制和抗菌药物耐药性的增加促使人们寻找针对致病免疫过程的宿主定向治疗方法。多形核白细胞(PMN)对于控制感染至关重要,但也可以促进组织损伤和病原体传播。主要毒力因子肺炎球菌溶血素( pneumolysin)通过刺激上皮细胞中的 12-脂氧合酶(12-LOX)类二十烷酸合成途径引发急性炎症。该途径是在小鼠肺炎模型中进行系统传播所必需的,并产生多种生物活性脂质,包括羟庚醛 A3(HXA),一种羟基环氧化物PMN趋化因子,据推测它有助于突破粘膜屏障。为了了解 12-LOX 依赖性炎症如何促进肺部感染和传播期间的传播,我们利用缺乏这种酶的支气管干细胞衍生的气液界面培养物进行研究,结果表明 HXA 甲酯(HXA-ME)足以促进 PMN 基底外侧到顶端的迁移、单层破坏以及伴随的屏障破裂。相比之下,PMN 对非类二十烷酸趋化因子 N-甲酰基-L-甲硫氨酸-L-亮氨酸-苯丙氨酸(fMLP)的迁移不会导致上皮细胞破坏或细菌易位。相应地,HXA-ME 而不是 fMLP 增加了感染 PMN 释放中性粒细胞弹性蛋白酶(NE)。用 NE 分泌或活性的药物阻断减少了肺部挑战后小鼠的上皮屏障破坏和菌血症。因此,HXA 促进了破坏屏障的 PMN 迁移和 NE 释放,这些病理事件可以作为限制肺炎链球菌性肺炎后全身性疾病的靶点。

重要提示

肺炎链球菌()是肺炎的主要病因之一,它可以从肺部扩散到血液中,引起全身性疾病。疫苗效力的限制和抗菌药物耐药性的增加促使人们寻找宿主定向治疗方法,以限制对肺炎链球菌的病理性宿主免疫反应。过多的多形核白细胞(PMN)浸润到肺炎链球菌感染的气道中会导致全身性疾病。使用反映真正肺上皮的干细胞衍生呼吸培养物,我们确定了类二十烷酸 hepoxilin A3 作为一种关键的肺部 PMN 趋化因子,通过诱导中性粒细胞弹性蛋白酶的释放足以驱动 PMN 介导的上皮损伤。在小鼠中抑制这种蛋白酶的释放或活性可限制上皮屏障破坏和细菌传播,提示这是一种治疗肺炎链球菌肺部感染的新的宿主定向治疗方法。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/3e69/11389395/112458455431/mbio.01856-24.f001.jpg

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