Institute of Pharmacology and Toxicology, University Hospital Aachen, RWTH Aachen University, Aachen, Germany.
PLoS One. 2010 Nov 16;5(11):e13889. doi: 10.1371/journal.pone.0013889.
Gram-positive and Gram-negative bacteria are main causes of pneumonia or acute lung injury. They are recognized by the innate immune system via toll-like receptor-2 (TLR2) or TLR4, respectively. Among all organs, the lungs have the highest expression of TLR2 receptors, but little is known about the pulmonary consequences of their activation. Here we studied the effects of the TLR2/6 agonist MALP-2, the TLR2/1 agonist Pam(3)Cys and the TLR4 agonist lipopolysaccharide (LPS) on pro-inflammatory responses in isolated lungs.
METHODOLOGY/PRINCIPAL FINDINGS: Isolated perfused mouse lungs were perfused for 60 min or 180 min with MALP-2 (25 ng/mL), Pam(3)Cys (160 ng/mL) or LPS (1 µg/mL). We studied mediator release by enzyme linked immunosorbent assay (ELISA), the activation of mitogen activated protein kinase (MAPK) and AKT/protein kinase B by immunoblotting, and gene induction by quantitative polymerase chain reaction. All agonists activated the MAPK ERK1/2 and p38, but neither JNK or AKT kinase. The TLR ligands upregulated the inflammation related genes Tnf, Il1β, Il6, Il10, Il12, Ifng, Cxcl2 (MIP-2α) and Ptgs2. MALP-2 was more potent than Pam(3)Cys in inducing Slpi, Cxcl10 (IP10) and Parg. Remarkable was the strong induction of Tnc by MALP2, which was not seen with Pam(3)Cys or LPS. The growth factor related genes Areg and Hbegf were not affected. In addition, all three TLR agonists stimulated the release of IL-6, TNF, CXCL2 and CXCL10 protein from the lungs.
CONCLUSIONS/SIGNIFICANCE: TLR2 and TLR4 activation leads to similar reactions in the lungs regarding MAPK activation, gene induction and mediator release. Several genes studied here have not yet been appreciated as targets of TLR2-activation in the lungs before, i.e., Slpi, tenascin C, Parg and Traf1. In addition, the MALP-2 dependent induction of Tnc may indicate the existence of TLR2/6-specific pathways.
革兰氏阳性和革兰氏阴性菌是肺炎或急性肺损伤的主要原因。它们分别通过 toll 样受体-2（TLR2）或 TLR4 被先天免疫系统识别。在所有器官中，肺部 TLR2 受体的表达最高，但对于其激活的肺部后果知之甚少。在这里，我们研究了 TLR2/6 激动剂 MALP-2、TLR2/1 激动剂 Pam(3)Cys 和 TLR4 激动剂脂多糖（LPS）对分离肺中促炎反应的影响。
方法/主要发现：用 MALP-2（25ng/mL）、Pam(3)Cys（160ng/mL）或 LPS（1μg/mL）灌流 60 分钟或 180 分钟，对离体灌注的小鼠肺进行灌流。通过酶联免疫吸附试验（ELISA）研究介质释放，通过免疫印迹法研究丝裂原活化蛋白激酶（MAPK）和 AKT/蛋白激酶 B 的激活，通过定量聚合酶链反应研究基因诱导。所有激动剂均激活 MAPK ERK1/2 和 p38，但不激活 JNK 或 AKT 激酶。TLR 配体上调炎症相关基因 Tnf、Il1β、Il6、Il10、Il12、Ifng、Cxcl2（MIP-2α）和 Ptgs2。MALP-2 比 Pam(3)Cys 更能诱导 Slpi、Cxcl10（IP10）和 Parg 的表达。值得注意的是，MALP2 强烈诱导 Tnc 的表达，而 Pam(3)Cys 或 LPS 则未见。生长因子相关基因 Areg 和 Hbegf 不受影响。此外，三种 TLR 激动剂均刺激 IL-6、TNF、CXCL2 和 CXCL10 蛋白从肺部释放。
结论/意义：TLR2 和 TLR4 的激活导致肺中 MAPK 激活、基因诱导和介质释放的类似反应。在此之前，一些研究中尚未被认为是 TLR2 激活肺部的靶点的基因，例如 Slpi、Tenascin C、Parg 和 Traf1。此外，MALP-2 依赖性 Tnc 的诱导可能表明存在 TLR2/6 特异性途径。
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