Age-dependent inflammatory response is altered in an ex vivo model of bacterial pneumonia

IF 4.7 2区医学 Q1 RESPIRATORY SYSTEM

Respiratory Research Pub Date : 2024-01-04 DOI:10.1186/s12931-023-02609-w

Charline Sommer, Stella Marie Reamon-Buettner, Monika Niehof, Christina Beatrix Hildebrand, Armin Braun, Katherina Sewald, Susann Dehmel, Christina Brandenberger

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Abstract

Aging is associated with an increased incidence and mortality of Pseudomonas aeruginosa-induced pneumonias. This might be partly due to age-dependent increases in inflammatory mediators, referred to as inflamm-aging and a decline in immune functions, known as immunosenescence. Still, the impact of dysregulated immune responses on lung infection during aging is poorly understood. Here, we aimed to mimic inflamm-aging using ex vivo precision-cut lung slices (PCLS) and neutrophils – as important effector cells of innate immunity – from young and old mice and investigated the influence of aging on inflammation upon infection with P. aeruginosa bacteria. Murine PCLS were infected with the P. aeruginosa standard lab strain PAO1 and a clinical P. aeruginosa isolate D61. After infection, whole-transcriptome analysis of the tissue as well as cytokine expression in supernatants and tissue lysates were performed. Responses of isolated neutrophils towards the bacteria were investigated by quantifying neutrophil extracellular trap (NET) formation, cytokine secretion, and analyzing expression of surface activation markers using flow cytometry. Inflamm-aging was observed by transcriptome analysis, showing an enrichment of biological processes related to inflammation, innate immune response, and chemotaxis in uninfected PCLS of old compared with young mice. Upon P. aeruginosa infection, the age-dependent pro-inflammatory response was even further promoted as shown by increased production of cytokines and chemokines such as IL-1β, IL-6, CXCL1, TNF-α, and IL-17A. In neutrophil cultures, aging did not influence NET formation or cytokine secretion during P. aeruginosa infection. However, expression of receptors associated with inflammatory responses such as complement, adhesion, phagocytosis, and degranulation was lower in neutrophils stimulated with bacteria from old mice as compared to young animals. By using PCLS and neutrophils from young and old mice as immunocompetent ex vivo test systems, we could mimic dysregulated immune responses upon aging on levels of gene expression, cytokine production, and receptor expression. The results furthermore reflect the exacerbation of inflammation upon P. aeruginosa lung infection as a result of inflamm-aging in old age.

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细菌性肺炎体内外模型的炎症反应随年龄而改变

衰老与铜绿假单胞菌引起的肺炎发病率和死亡率增加有关。其部分原因可能是炎症介质随年龄增长而增加（称为炎性衰老），以及免疫功能下降（称为免疫衰老）。然而，人们对衰老过程中失调的免疫反应对肺部感染的影响还知之甚少。在这里，我们利用体内外精确切割肺切片（PCLS）和中性粒细胞（先天性免疫的重要效应细胞）来模拟炎症衰老，并研究了衰老对铜绿假单胞菌感染时炎症的影响。小鼠 PCLS 感染了铜绿假单胞菌标准实验室菌株 PAO1 和临床铜绿假单胞菌分离株 D61。感染后，对组织以及上清液和组织裂解液中细胞因子的表达进行了全转录组分析。通过量化中性粒细胞胞外捕获物（NET）的形成、细胞因子的分泌以及使用流式细胞术分析表面活化标记物的表达，研究了分离的中性粒细胞对细菌的反应。通过转录组分析观察了炎症老化，结果显示与年轻小鼠相比，未感染的老龄小鼠 PCLS 中与炎症、先天性免疫反应和趋化有关的生物过程更加丰富。感染铜绿假单胞菌后，细胞因子和趋化因子（如 IL-1β、IL-6、CXCL1、TNF-α 和 IL-17A）的产生增加，进一步促进了年龄依赖性促炎反应。在中性粒细胞培养物中，衰老并不影响铜绿假单胞菌感染过程中 NET 的形成或细胞因子的分泌。然而，与年轻动物相比，与炎症反应（如补体、粘附、吞噬和脱颗粒）相关的受体在受到细菌刺激的老年小鼠中性粒细胞中的表达较低。通过使用 PCLS 和来自年轻和年老小鼠的中性粒细胞作为免疫能力体内外测试系统，我们可以模拟衰老时在基因表达、细胞因子产生和受体表达水平上失调的免疫反应。结果进一步反映了老年炎症老化导致铜绿假单胞菌肺部感染时炎症加剧。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Respiratory Research 医学-呼吸系统

自引率

1.70%

发文量

314

期刊介绍： Respiratory Research publishes high-quality clinical and basic research, review and commentary articles on all aspects of respiratory medicine and related diseases. As the leading fully open access journal in the field, Respiratory Research provides an essential resource for pulmonologists, allergists, immunologists and other physicians, researchers, healthcare workers and medical students with worldwide dissemination of articles resulting in high visibility and generating international discussion. Topics of specific interest include asthma, chronic obstructive pulmonary disease, cystic fibrosis, genetics, infectious diseases, interstitial lung diseases, lung development, lung tumors, occupational and environmental factors, pulmonary circulation, pulmonary pharmacology and therapeutics, respiratory immunology, respiratory physiology, and sleep-related respiratory problems.