Samavati Lobelia, Rastogi Ruchi, Du Wenjin, Hüttemann Maik, Fite Alemu, Franchi Luigi
Department of Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Mol Immunol. 2009 May;46(8-9):1867-77. doi: 10.1016/j.molimm.2009.02.018. Epub 2009 Mar 18.
Both interleukin 1 beta (IL-1beta) and interleukin-6 (IL-6) are pro-inflammatory cytokines that play a major role in inflammatory diseases as well as cancer. In this work we investigated the signaling pathway involving lipopolysaccharide (LPS)-mediated IL-1beta and IL-6 production in murine macrophage cell lines and primary macrophages. We show that in response to LPS, the JAK/STAT pathway is activated, leading to tyrosine phosphorylation at residue 705 on STAT3 and at residue 701 on STAT1, respectively. A newly developed STAT3 specific inhibitor (stattic) blocked LPS-mediated STAT3 tyrosine phosphorylation and led to inhibition of LPS-mediated IL-1beta and IL-6 production but not TNF-alpha production. Knockdown of STAT3 expression via small interfering RNA (siRNA) decreased the level of STAT3 expression in Raw 264.7 cells and decreased STAT3 tyrosine phosphorylation in response to LPS treatment. Quantitative real time PCR and Western analysis of cells treated with inhibitor or STAT3 siRNA after LPS treatment showed a significant reduction of IL-1beta and IL-6 mRNA and protein compared to cells treated with LPS alone. Moreover stattic abrogated IL-1beta formation in response to extracellular bacteria Staphylococcus aureus and Escherichia coli in murine peritoneal macrophages. This inhibition did not affect caspase-1 activation. These results highlight the complex role of STAT3 in cytokine production and the key role of STAT3 tyrosine phosphorylation in IL-1beta and IL-6 production in response to inflammation.
白细胞介素1β（IL-1β）和白细胞介素-6（IL-6）都是促炎细胞因子，在炎症性疾病和癌症中发挥着重要作用。在这项研究中，我们调查了小鼠巨噬细胞系和原代巨噬细胞中涉及脂多糖（LPS）介导的IL-1β和IL-6产生的信号通路。我们发现，在LPS刺激下，JAK/STAT通路被激活，分别导致STAT3第705位残基和STAT1第701位残基的酪氨酸磷酸化。一种新开发的STAT3特异性抑制剂（stattic）可阻断LPS介导的STAT3酪氨酸磷酸化，并抑制LPS介导的IL-1β和IL-6产生，但不影响TNF-α的产生。通过小干扰RNA（siRNA）敲低STAT3表达可降低Raw 264.7细胞中STAT3的表达水平，并减少LPS处理后STAT3的酪氨酸磷酸化。对LPS处理后用抑制剂或STAT3 siRNA处理的细胞进行定量实时PCR和蛋白质印迹分析表明，与单独用LPS处理的细胞相比，IL-1β和IL-6的mRNA和蛋白质水平显著降低。此外，stattic可消除小鼠腹膜巨噬细胞对细胞外细菌金黄色葡萄球菌和大肠杆菌产生的IL-1β。这种抑制作用不影响caspase-1的激活。这些结果突出了STAT3在细胞因子产生中的复杂作用，以及STAT3酪氨酸磷酸化在炎症反应中IL-1β和IL-6产生中的关键作用。
