气道上皮连接减弱和中性粒细胞弹性蛋白酶释放增加导致肺炎球菌肺炎后与年龄相关的菌血症风险。
Weakened Airway Epithelial Junctions and Enhanced Neutrophil Elastase Release Contribute to Age-Dependent Bacteremia Risk Following Pneumococcal Pneumonia.
作者信息
Xu Shuying, Zhu Tianmou, Mou Hongmei, Tan Shumin, Leong John M
机构信息
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA.
Graduate Program in Immunology, Tufts Graduate School of Biomedical Sciences, Boston, MA, USA.
出版信息
Aging Cell. 2025 May;24(5):e14474. doi: 10.1111/acel.14474. Epub 2025 Jan 8.
Streptococcus pneumoniae (Sp; pneumococcus), the most common agent of community-acquired pneumonia, can spread systemically, particularly in the elderly, highlighting the need for adjunctive therapies. The airway epithelial barrier defends against bacteremia and is dependent upon apical junctional complex (AJC) proteins such as E-cadherin. After mouse lung challenge, pneumolysin (PLY), a key Sp virulence factor, stimulates epithelial secretion of an inflammatory eicosanoid, triggering the infiltration of polymorphonuclear leukocytes (PMNs) that secrete high levels of neutrophil elastase (NE), thus promoting epithelial damage and systemic infection. Here, pulmonary E-cadherin staining of intratracheally (i.t.) inoculated mice revealed PLY-mediated disruption of AJC independently of PMNs. Apical infection of air-liquid interface (ALI) respiratory epithelial monolayers similarly showed that PLY disrupts AJCs. This epithelial damage promoted PMN transmigration and bacterial apical-to-basolateral translocation, and pharmacologically fortifying epithelial barrier function diminished both barrier breach in vitro and bacteremia in vivo. E-cadherin staining after Sp i.t. inoculation of > 20-month-old mice, or apical infection of ALI monolayers derived from these mice, revealed an age-associated vulnerability to PLY-mediated AJC disruption, which in turn enhanced PMN migration and bacteremia. In addition, we found that PMNs from aged mice secrete increased levels of tissue-damaging NE. Simultaneous pharmacological inhibition of tissue-destructive NE and fortification of pulmonary epithelial barrier function was required to reduce the level of Sp bacteremia in aged mice to that of young mice. This work underscores the importance of fully characterizing the multifactorial sources of age-associated susceptibility in devising adjunctive therapies to mitigate invasive pneumococcal disease in the elderly.
肺炎链球菌(Sp;肺炎球菌)是社区获得性肺炎最常见的病原体,可发生全身播散,在老年人中尤为如此,这凸显了辅助治疗的必要性。气道上皮屏障可抵御菌血症,其依赖于诸如E-钙黏蛋白等顶端连接复合体(AJC)蛋白。在用小鼠进行肺部攻击后,肺炎球菌溶血素(PLY)作为Sp的一种关键毒力因子,可刺激上皮细胞分泌一种炎性类二十烷酸,引发分泌高水平中性粒细胞弹性蛋白酶(NE)的多形核白细胞(PMN)浸润,从而促进上皮损伤和全身感染。在此,对经气管内(i.t.)接种小鼠的肺部E-钙黏蛋白染色显示,PLY介导的AJC破坏独立于PMN。气液界面(ALI)呼吸道上皮单层的顶端感染同样显示PLY会破坏AJC。这种上皮损伤促进了PMN迁移和细菌从顶端向基底外侧的易位,而通过药物增强上皮屏障功能可减少体外屏障破坏和体内菌血症。对20月龄以上小鼠进行Sp i.t.接种后,或对源自这些小鼠的ALI单层进行顶端感染后的E-钙黏蛋白染色显示,存在与年龄相关的对PLY介导的AJC破坏的易感性,这反过来又增强了PMN迁移和菌血症。此外,我们发现老年小鼠的PMN分泌的组织损伤性NE水平升高。要将老年小鼠的Sp菌血症水平降低到年轻小鼠的水平,需要同时对组织破坏性NE进行药理抑制并增强肺上皮屏障功能。这项工作强调了在设计辅助疗法以减轻老年人侵袭性肺炎球菌疾病时,全面表征与年龄相关易感性的多因素来源的重要性。
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