LPS induced inflammatory responses in human peripheral blood mononuclear cells is mediated through NOX4 and Giα dependent PI-3kinase signalling.
LPS induced inflammatory responses in human peripheral blood mononuclear cells is mediated through NOX4 and Giα dependent PI-3kinase signalling.
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DOI：
10.1186/1476-9255-9-1
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发表时间：
2012-01-12
期刊：
影响因子：
--
通讯作者：
Kirkham PA
中科院分区：
文献类型：
--
作者：
Ngkelo A;Meja K;Yeadon M;Adcock I;Kirkham PA
慢性阻塞性肺病是一种先天免疫疾病，细菌感染是导致晚期疾病恶化的主要原因，导致健康状况不佳和死亡率高。病原体相关分子模式（PAMP）脂多糖（LPS）通过toll样受体4 （TLR4）的激活被免疫细胞感知。这导致NADPH氧化酶（NOX）和NF-κB的激活，它们共同驱动COPD炎症。在这项研究中，我们发现在人PBMCs中，LPS刺激的促炎细胞因子释放（CXCL8和IL6）被广泛特异性磷脂酰肌醇3-激酶（PI3K）抑制剂wortmannin抑制了约50%。我们的研究结果还表明，LPS刺激后PI3K的激活是由NOX4依赖机制介导的，该机制释放内源性H2O2，因为NOX4抑制剂apocynin阻断了LPS诱导的AKT磷酸化。此外，抗氧化剂n -乙酰半胱氨酸对lps诱导的PI3K激活呈浓度依赖性抑制（IC50 ~100 μM）。此外，我们的数据表明，通过百日咳毒素预处理抑制小G蛋白，可以抑制lps诱导的AKT磷酸化。此外，g蛋白抑制剂百日咳毒素和乳突白蛋白均能抑制lps诱导的CXCL8和IL-6释放约50%。总之，这些数据表明，在人类pbmc中存在一种机制，即LPS激活TLR4通过NOX4和PI3K途径导致ROS生成。这种作用显然是通过促进促炎细胞因子释放的小G蛋白介导的。
COPD is a disease of innate immunity and bacterial infections are a dominant cause of exacerbations in the later stages resulting in poor health and high mortality. The pathogen-associated molecular pattern (PAMP) lipopolysaccharide (LPS) is sensed by immune cells through activation of the toll-like receptor 4 (TLR4). This leads to the activation of NADPH oxidase (NOX) and NF-κB which together drive COPD inflammation. In this study we show in human PBMCs that LPS stimulated proinflammatory cytokine release (CXCL8 and IL6) was inhibited by approximately 50% by the broad specificity phosphatidylinositol 3-kinase (PI3K) inhibitor, wortmannin. Our results also demonstrate that activation of PI3K following LPS stimulation is mediated by a NOX4 dependent mechanism releasing endogenous H2O2, as the NOX4 inhibitor apocynin blocked LPS induced AKT phosphorylation. Moreover, LPS-induced PI3K activation was inhibited by the anti-oxidant N-acetylcysteine in a concentration dependent manner (IC50 ~100 μM). In addition, our data demonstrated that inhibition of small G proteins, by pre-treatment with pertussis toxin, inhibited LPS-induced AKT phosphorylation. Furthermore, the G-protein inhibitors pertussis toxin and mastoparan both inhibited LPS-induced CXCL8 and IL-6 release by approximately 50%. Together, these data indicate there is a mechanism in human PBMCs where TLR4 activation by LPS leads to ROS generation through NOX4 and activation of the PI3K pathway. This effect is apparently mediated through small G proteins facilitating the release of pro-inflammatory cytokines.
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