Croasdell Amanda, Lacy Shannon H, Thatcher Thomas H, Sime Patricia J, Phipps Richard P
Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642; Lung Biology and Disease Program, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642; and.
Lung Biology and Disease Program, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642; and Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642.
J Immunol. 2016 Mar 15;196(6):2742-52. doi: 10.4049/jimmunol.1502331. Epub 2016 Feb 3.
Nontypeable Haemophilus influenzae (NTHi) is a Gram-negative, opportunistic pathogen that frequently causes ear infections, bronchitis, pneumonia, and exacerbations in patients with underlying inflammatory diseases, such as chronic obstructive pulmonary disease. In mice, NTHi is rapidly cleared, but a strong inflammatory response persists, underscoring the concept that NTHi induces dysregulation of normal inflammatory responses and causes a failure to resolve. Lipid-derived specialized proresolving mediators (SPMs) play a critical role in the active resolution of inflammation by both suppressing proinflammatory actions and promoting resolution pathways. Importantly, SPMs lack the immunosuppressive properties of classical anti-inflammatory therapies. On the basis of these characteristics, we hypothesized that aspirin-triggered resolvin D1 (AT-RvD1) would dampen NTHi-induced inflammation while still enhancing bacterial clearance. C57BL/6 mice were treated with AT-RvD1 and infected with live NTHi. AT-RvD1-treated mice had lower total cell counts and neutrophils in bronchoalveolar lavage fluid, and had earlier influx of macrophages. In addition, AT-RvD1-treated mice showed changes in temporal regulation of inflammatory cytokines and enzymes, with decreased KC at 6 h and decreased IL-6, TNF-α, and cyclooxygenase-2 expression at 24 h post infection. Despite reduced inflammation, AT-RvD1-treated mice had reduced NTHi bacterial load, mediated by enhanced clearance by macrophages and a skewing toward an M2 phenotype. Finally, AT-RvD1 protected NTHi-infected mice from weight loss, hypothermia, hypoxemia, and respiratory compromise. This research highlights the beneficial role of SPMs in pulmonary bacterial infections and provides the groundwork for further investigation into SPMs as alternatives to immunosuppressive therapies like steroids.
不可分型流感嗜血杆菌(NTHi)是一种革兰氏阴性机会致病菌,常引发耳部感染、支气管炎、肺炎,还会使患有潜在炎症性疾病(如慢性阻塞性肺疾病)的患者病情加重。在小鼠体内,NTHi能被迅速清除,但强烈的炎症反应会持续存在,这凸显了NTHi会导致正常炎症反应失调并致使炎症无法消退的概念。脂质衍生的特异性促消退介质(SPM)通过抑制促炎作用和促进消退途径,在炎症的主动消退中发挥关键作用。重要的是,SPM缺乏传统抗炎疗法的免疫抑制特性。基于这些特性,我们推测阿司匹林触发的消退素D1(AT-RvD1)会减轻NTHi诱导的炎症,同时仍能增强细菌清除能力。用AT-RvD1处理C57BL/6小鼠,然后使其感染活的NTHi。经AT-RvD1处理的小鼠支气管肺泡灌洗液中的总细胞计数和中性粒细胞数量较低,巨噬细胞的流入也更早。此外,经AT-RvD1处理的小鼠在炎症细胞因子和酶的时间调节上出现变化,感染后6小时KC降低,24小时白细胞介素-6、肿瘤坏死因子-α和环氧化酶-2的表达降低。尽管炎症减轻,但经AT-RvD1处理的小鼠NTHi细菌载量降低,这是由巨噬细胞清除能力增强以及向M2表型转变介导的。最后,AT-RvD1保护NTHi感染的小鼠免于体重减轻、体温过低、低氧血症和呼吸功能不全。这项研究突出了SPM在肺部细菌感染中的有益作用,并为进一步研究将SPM作为类固醇等免疫抑制疗法的替代方案奠定了基础。