Department of Biochemistry, Zhongshan Medical School, Sun Yat-sen University, Guangzhou 510080, Guangdong Province, China.
J Cell Biochem. 2013 May;114(5):1020-8. doi: 10.1002/jcb.24441.
Kallikrein-binding protein (KBP) was previously identified as a serpin family member with specific inhibitory effect on tissue kallikrein and angiogenesis, while there is little knowledge about the effects on inflammation. The aim of this study is to investigate whether KBP can suppress LPS-induced inflammatory process. Our results showed that both recombinant KBP and KBP overexpression inhibited LPS-stimulated TNF-α transcription and translation in macrophage cell line RAW264.7 and primary macrophages. Furthermore, KBP treatment protected mice from endotoxin shock and repressed serum TNF-α production, increasing survival rate of mice from 10% to 50% when compared to LPS alone. Moreover, qPCR and Western blot analysis demonstrated that both suppressor of cytokine signaling 3 (SOCS3) transcription and translation were induced by KBP treatment in the present of LPS. RNA interference assay and luciferase assay showed that SOCS3 was responsible for the down-regulation of TNF-α by KBP, rather than NF-κB subunit p65 and β-catenin. Therefore, we demonstrated that KBP suppressed LPS-induced TNF-α production via upregulating SOCS3 expression. These results present the protective effects of KBP on LPS-induced inflammation and provide novel information for the anti-inflammation mechanism.
激肽释放酶结合蛋白（KBP）先前被鉴定为丝氨酸蛋白酶抑制剂家族的成员，对组织激肽释放酶和血管生成具有特异性抑制作用，而对炎症的影响知之甚少。本研究旨在探讨 KBP 是否能抑制 LPS 诱导的炎症过程。我们的结果表明，重组 KBP 和 KBP 过表达均能抑制巨噬细胞系 RAW264.7 和原代巨噬细胞中 LPS 刺激的 TNF-α 转录和翻译。此外，KBP 处理可保护小鼠免受内毒素休克的影响，并抑制血清 TNF-α 的产生，与单独 LPS 相比，小鼠的存活率从 10%增加到 50%。此外，qPCR 和 Western blot 分析表明，在 LPS 存在的情况下，KBP 处理诱导了细胞因子信号转导抑制因子 3（SOCS3）的转录和翻译。RNA 干扰实验和荧光素酶报告基因实验表明，SOCS3 是 KBP 下调 TNF-α 的原因，而不是 NF-κB 亚基 p65 和β-连环蛋白。因此，我们证明了 KBP 通过上调 SOCS3 的表达来抑制 LPS 诱导的 TNF-α 产生。这些结果表明 KBP 对 LPS 诱导的炎症具有保护作用，并为抗炎机制提供了新的信息。
