Kanekiyo Masako, Itoh Norio, Kawasaki Atsuko, Matsuyama Akiko, Matsuda Kimihiro, Nakanishi Tsuyoshi, Tanaka Keiichi
Department of Toxicology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan.
Biochem J. 2002 Jan 15;361(Pt 2):363-9. doi: 10.1042/0264-6021:3610363.
Metallothionein (MT) is a low-molecular-mass, cysteine-rich metal binding protein thought to be involved in the detoxification of heavy metals and scavenging of free radicals. MT is directly induced not only by heavy metals, but also by hormones and cytokines. The present study, which uses mice with genetic deletions of the MT proteins (MT(-/-) mice), was designed to evaluate the effects of MT on the expression of pro-inflammatory cytokines in macrophages. We found that the production of tumour necrosis factor (TNF) induced by lipopolysaccharide (LPS) in peritoneal macrophages is up-regulated by MT via the modulation of nuclear factor kappaB (NF-kappaB) activity. This conclusion is supported by the following observations: (1) LPS stimulated the secretion of less TNF activity from MT(-/-) peritoneal exudate macrophages (PEMs) than from wild-type controls (MT(+/+) mice) without a difference in the pattern of kinetics; (2) LPS-stimulated expression of TNF-alpha mRNA was decreased in MT(-/-) PEMs; (3) LPS-stimulated activation of NF-kappaB was decreased in MT(-/-) PEMs; and (4) production of TNF in PEMs of MT(-/-) mice after LPS treatment in vivo was decreased (compared with MT(+/+) PEMs). Expression of other inflammatory cytokines, interleukin (IL)-1alpha and IL-6 mRNA, which were modulated by NF-kappaB, were also down-regulated in MT(-/-) PEMs. Thus MT plays a key role in the LPS-induced activation of PEMs via the modulation of NF-kappaB activity.
金属硫蛋白（MT）是一种低分子量、富含半胱氨酸的金属结合蛋白，被认为参与重金属解毒和自由基清除。MT不仅直接由重金属诱导，还可由激素和细胞因子诱导。本研究使用MT蛋白基因缺失的小鼠（MT(-/-)小鼠），旨在评估MT对巨噬细胞中促炎细胞因子表达的影响。我们发现，MT通过调节核因子κB（NF-κB）活性，上调了脂多糖（LPS）诱导的腹膜巨噬细胞中肿瘤坏死因子（TNF）的产生。以下观察结果支持这一结论：（1）LPS刺激后，MT(-/-)腹膜渗出巨噬细胞（PEMs）分泌的TNF活性低于野生型对照（MT(+/+)小鼠），动力学模式无差异；（2）MT(-/-) PEMs中LPS刺激的TNF-α mRNA表达降低；（3）MT(-/-) PEMs中LPS刺激的NF-κB活化降低；（4）体内LPS处理后，MT(-/-)小鼠PEMs中TNF的产生减少（与MT(+/+) PEMs相比）。其他受NF-κB调节的炎性细胞因子白细胞介素（IL）-1α和IL-6 mRNA的表达在MT(-/-) PEMs中也下调。因此，MT通过调节NF-κB活性，在LPS诱导的PEMs活化中起关键作用。
