血清淀粉样蛋白 A 与脂氧素 A4 对抗,介导慢性阻塞性肺疾病中糖皮质激素抵抗性肺炎症。
Serum amyloid A opposes lipoxin A₄ to mediate glucocorticoid refractory lung inflammation in chronic obstructive pulmonary disease.
机构信息
Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia 3010.
出版信息
Proc Natl Acad Sci U S A. 2012 Jan 17;109(3):935-40. doi: 10.1073/pnas.1109382109. Epub 2012 Jan 3.
Chronic obstructive pulmonary disease (COPD) will soon be the third most common cause of death globally. Despite smoking cessation, neutrophilic mucosal inflammation persistently damages the airways and fails to protect from recurrent infections. This maladaptive and excess inflammation is also refractory to glucocorticosteroids (GC). Here, we identify serum amyloid A (SAA) as a candidate mediator of GC refractory inflammation in COPD. Extrahepatic SAA was detected locally in COPD bronchoalveolar lavage fluid, which correlated with IL-8 and neutrophil elastase, consistent with neutrophil recruitment and activation. Immunohistochemistry detected SAA was in close proximity to airway epithelium, and in vitro SAA triggered release of IL-8 and other proinflammatory mediators by airway epithelial cells in an ALX/FPR2 (formyl peptide receptor 2) receptor-dependent manner. Lipoxin A(4) (LXA(4)) can also interact with ALX/FPR2 receptors and lead to allosteric inhibition of SAA-initiated epithelial responses (pA(2) 13 nM). During acute exacerbation, peripheral blood SAA levels increased dramatically and were disproportionately increased relative to LXA(4). Human lung macrophages (CD68(+)) colocalized with SAA and GCs markedly increased SAA in vitro (THP-1, pEC(50) 43 nM). To determine its direct actions, SAA was administered into murine lung, leading to induction of CXC chemokine ligand 1/2 and a neutrophilic response that was inhibited by 15-epi-LXA(4) but not dexamethasone. Taken together, these findings identify SAA as a therapeutic target for inhibition and implicate SAA as a mediator of GC-resistant lung inflammation that can overwhelm organ protective signaling by lipoxins at ALX/FPR2 receptors.
慢性阻塞性肺疾病(COPD)很快将成为全球第三大常见死因。尽管已经戒烟,但中性粒细胞黏膜炎症仍持续损害气道,并不能防止反复感染。这种适应性和过度炎症也对糖皮质激素(GC)不敏感。在这里,我们确定血清淀粉样蛋白 A(SAA)为 COPD 中 GC 难治性炎症的候选介质。在 COPD 支气管肺泡灌洗液中局部检测到肝外 SAA,与 IL-8 和中性粒细胞弹性蛋白酶相关,与中性粒细胞募集和激活一致。免疫组织化学检测到 SAA 与气道上皮细胞紧密相邻,体外 SAA 通过气道上皮细胞中的 ALX/FPR2(甲酰肽受体 2)受体以依赖方式触发 IL-8 和其他促炎介质的释放。脂氧素 A(4)(LXA(4))也可以与 ALX/FPR2 受体相互作用,并导致 SAA 引发的上皮反应的变构抑制(pA(2) 13 nM)。在急性加重期间,外周血 SAA 水平急剧增加,与 LXA(4)相比不成比例地增加。人肺巨噬细胞(CD68(+))与 SAA 共定位,GC 显著增加了体外 SAA(THP-1,pEC(50) 43 nM)。为了确定其直接作用,将 SAA 给予小鼠肺中,导致 CXC 趋化因子配体 1/2 的诱导和中性粒细胞反应,该反应被 15-epi-LXA(4)抑制,但不受地塞米松抑制。综上所述,这些发现确定了 SAA 作为抑制的治疗靶标,并暗示 SAA 作为 GC 抵抗性肺炎症的介质,该介质可以通过 ALX/FPR2 受体上的脂氧素来压倒器官保护性信号。