Lipopolysaccharide-induced cytokine expression in alveolar epithelial cells: Role of PKCζ-mediated p47phox phosphorylation
Lipopolysaccharide-induced cytokine expression in alveolar epithelial cells: Role of PKCζ-mediated p47phox phosphorylation
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DOI：
10.1016/j.cbi.2010.09.026
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发表时间：
2011-01-15
影响因子：
5.1
通讯作者：
Sampath, Venkatesh
中科院分区：
文献类型：
--
作者：
Leverence, Jeremy T.;Medhora, Meetha;Sampath, Venkatesh
早产儿囊状肺内细菌引起的慢性炎症是支气管肺发育不良（BPD）的发病机制之一。LPS介导的II型肺泡上皮细胞（AEC）损伤诱导促炎细胞因子的表达，这些促炎细胞因子触发肺中性粒细胞内流、肺泡基质降解和肺重塑。我们假设NADPH氧化酶（Nox）依赖性机制介导LPS诱导的AEC细胞因子表达。我们研究了p47 phox在介导LPS依赖性炎症细胞因子表达的A549细胞（表现出II型AEC的表型特征）中的作用，并阐明了LPS激活Nox的近端信号事件。LPS诱导的ICAM-1和IL-8表达与AEC中超氧化物形成增加相关。脂多糖介导的氧化应激和细胞因子的表达被夹竹桃素抑制，PMA增强，表明NOX依赖的氧化还原信号调节AEC中脂多糖依赖的促炎信号。在LPS处理的细胞中，p47 phox从细胞质易位到核周区域，并与gp 91 phox共定位。LPS还诱导AEC中p47 phox丝氨酸304磷酸化的时间增加。虽然用钙磷蛋白和rottlerin抑制经典PKC和新型PKC并不抑制ICAM-1或IL-8的表达，但肉豆蔻酰化的PKC zeta假底物肽（PKC zeta的特异性抑制剂）抑制AEC中LPS诱导的细胞因子表达。PKC zeta的抑制也减弱LPS介导的p47 phox磷酸化和AEC的核周易位。与这些数据相一致，LPS激活AEC中的PKC ζ，如通过增加的苏氨酸410磷酸化所证明的。我们的结论是PKC zeta介导的p47 phox激活调节AEC中LPS依赖性细胞因子的表达。选择性抑制PKCzeta或p47 phox可能减轻BPD中LPS介导的炎症和肺泡重塑。(C)2010爱思唯尔爱尔兰有限公司版权所有。
Chronic inflammation incited by bacteria in the saccular lung of premature infants contributes to the pathogenesis of bronchopulmonary dysplasia (BPD). LPS-mediated type II alveolar epithelial cell (AEC) injury induces the expression of pro-inflammatory cytokines that trigger pulmonary neutrophil influx, alveolar matrix degradation and lung remodeling. We hypothesized that NADPH oxidase (Nox)-dependent mechanisms mediate LPS-induced cytokine expression in AEC. We examined the role of p47phox in mediating LPS-dependent inflammatory cytokine expression in A549 cells (which exhibit phenotypic features characteristic of type II AEC) and elucidated the proximal signaling events by which Nox is activated by LPS. LPS-induced ICAM-1 and IL-8 expression was associated with increased superoxide formation in AEC. LPS-mediated oxidative stress and cytokine expression was inhibited by apocynin and augmented by PMA demonstrating that Nox-dependent redox signaling regulates LPS-dependent pro-inflammatory signaling in AEC. In LPS-treated cells, p47phox translocated from the cytoplasm to the perinuclear region and co-localized with gp91phox. LPS also induced a temporal increase in p47phox serine304 phosphorylation in AEC. While inhibition of classical PKC and novel PKC with calphostin and rottlerin did not inhibit ICAM-1 or IL-8 expression, the myristolyated PKC zeta pseudosubstrate peptide (a specific inhibitor of PKC zeta) inhibited LPS-induced cytokine expression in AEC. Inhibition of PKC zeta also attenuated LPS-mediated p47phox phosphorylation and perinuclear translocation in AEC. Consistent with these data, LPS activated PKC zeta in AEC as evidenced by increased threonine410 phophorylation. We conclude that PKC zeta-mediated p47phox activation regulates LPS-dependent cytokine expression in AEC. Selective inhibition of PKC zeta or p47phox might attenuate LPS-mediated inflammation and alveolar remodeling in BPD. (C) 2010 Elsevier Ireland Ltd. All rights reserved.