Ellingsen Espen, Morath Siegfried, Flo Trude, Schromm Andra, Hartung Thomas, Thiemermann Christoph, Espevik Terje, Golenbock Douglas, Foster Daniel, Solberg Rigmor, Aasen Ansgar, Wang Jacob
Institute for Surgical Research, Rikshospitalet - National Hospital, N-0027 Oslo, Norway.
Med Sci Monit. 2002 May;8(5):BR149-56.
The pro-inflammatory potential of lipoteichoic acid (LTA) from Staphylococcus aureus is controversial. The present study was undertaken to examine the ability of highly purified and characterized S. aureus LTA to stimulate the production of pro-inflammatory cytokines in human leukocytes at both mRNA and protein level, and to study the involvement of Toll-like receptors (TLRs) and CD14 in this response.
MATERIAL/METHODS: Purified LTA was administered to whole human blood ex-vivo (or primary adherent monocytes) and the cytokine response assessed in plasma by EIA. Cytokine mRNA was measured by RT-PCR on leukocyte subsets isolated following stimulation. To study the involvement of specific receptors for LTA signaling, CHO cells transfected with CD14 and/or TLR2, TLR4 were used, as well as antibodies directed against these receptors.
Addition of highly purified LTA to human whole blood or primary adherent human monocytes elicited a time and concentration dependent release of tumor necrosis factor alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), IL-6 and IL-8. Messenger RNA encoding TNF-alpha, IL-1 beta and IL-6 seemed to be accumulated in monocytes and T cells, but not in granulocytes and B cells. Expression of TLR2, but not TLR4, in chinese hamster ovary cells conferred responsiveness to LTA. However, antibodies directed towards TLR2 (clone TL2.1) or TLR4 (clone HTA125) failed to inhibit TNF-a release induced by LTA in both the whole blood model and in adherent monocytes. In contrast, blockade of the CD14 receptor with MAb18D11 strongly attenuated the LTA induced release of TNF-alpha in both models.
We propose that (i) LTA from S. aureus triggers the release of cytokines during staphylococcal infections, and (ii) both monocytes and T cells contribute to cytokine production induced by LTA. TLR2 may mediate cellular activation by LTA, but the functional significance of this receptor during staphylococcal infections remains elusive.
金黄色葡萄球菌脂磷壁酸（LTA）的促炎潜力存在争议。本研究旨在检测高度纯化且特性明确的金黄色葡萄球菌LTA在mRNA和蛋白质水平上刺激人白细胞产生促炎细胞因子的能力，并研究Toll样受体（TLR）和CD14在此反应中的作用。
材料/方法：将纯化的LTA体外给予全血（或原代贴壁单核细胞），并通过酶免疫分析（EIA）评估血浆中的细胞因子反应。刺激后分离的白细胞亚群通过逆转录聚合酶链反应（RT-PCR）检测细胞因子mRNA。为研究LTA信号传导特异性受体的作用，使用转染了CD14和/或TLR2、TLR4的中国仓鼠卵巢（CHO）细胞，以及针对这些受体的抗体。
向人全血或原代贴壁人单核细胞中添加高度纯化的LTA会引起肿瘤坏死因子α（TNF-α）、白细胞介素-1β（IL-1β）、IL-6和IL-8的时间和浓度依赖性释放。编码TNF-α、IL-1β和IL-6的信使RNA似乎在单核细胞和T细胞中积累，但在粒细胞和B细胞中未积累。中国仓鼠卵巢细胞中TLR2而非TLR4的表达赋予了对LTA的反应性。然而，针对TLR2（克隆TL2.1）或TLR4（克隆HTA125）的抗体未能在全血模型和贴壁单核细胞中抑制LTA诱导的TNF-α释放。相比之下，用单克隆抗体18D11阻断CD14受体在两种模型中均强烈减弱了LTA诱导的TNF-α释放。
我们提出（i）金黄色葡萄球菌的LTA在葡萄球菌感染期间触发细胞因子释放，（ii）单核细胞和T细胞均有助于LTA诱导的细胞因子产生。TLR2可能介导LTA诱导的细胞活化，但该受体在葡萄球菌感染期间的功能意义仍不明确。
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