Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0212, USA.
Eur J Pharmacol. 2010 Mar 10;629(1-3):140-6. doi: 10.1016/j.ejphar.2009.12.002. Epub 2009 Dec 16.
In response to evolutionary selective pressure, prokaryotes have developed a rich array of secondary metabolites, some of which may be inhibitory to the innate immune system and the inflammatory response in vertebrates. We utilized the RAW264.7 macrophage cell line stimulated with LPS in a nitric oxide (NO) assay to screen for compounds with immunomodulatory activities from a library of marine natural products, and found that the malyngamide structure class, found commonly in the marine cyanobacterium Lyngbya majuscula, has potent activity. Several of the malyngamides were found to possess IC50 values of 5.4-18microM. Malyngamide F acetate exhibited strong concentration-dependent anti-inflammatory activity in the NO assay with an IC50 of 7.1microM and with no cytotoxicity at the concentrations tested. Subsequent real-time PCR of selected genes revealed a unique cytokine profile after LPS stimulation (TLR4) with decreased expression of iNOS, IL-1beta, IL-6, and IL-10, but increased TNF-alpha expression. Additional experiments utilizing CpG and Poly I:C stimulation to selectively activate the MyD88-dependent and -independent pathways via TLR9 and TLR3 substantiated the finding that malyngamide F acetate selectively inhibits the MyD88-dependent pathway. To our knowledge, this is the first report of a natural product inhibiting the MyD88-dependent pathway.
为了应对进化选择压力，原核生物产生了丰富多样的次生代谢产物，其中一些可能对脊椎动物的固有免疫系统和炎症反应具有抑制作用。我们利用脂多糖（LPS）刺激的 RAW264.7 巨噬细胞系在一氧化氮（NO）测定中筛选具有免疫调节活性的化合物文库，发现海洋蓝藻 Lyngbya majuscula 中常见的马良酰胺结构类化合物具有很强的活性。几种马良酰胺的 IC50 值为 5.4-18μM。马良酰胺 F 乙酸酯在 NO 测定中表现出强烈的浓度依赖性抗炎活性，IC50 为 7.1μM，在测试浓度下无细胞毒性。随后对选定基因进行实时 PCR 分析显示，LPS 刺激后细胞因子谱发生了独特的变化（TLR4），iNOS、IL-1β、IL-6 和 IL-10 的表达降低，但 TNF-α的表达增加。利用 CpG 和 Poly I:C 刺激进行的额外实验，通过 TLR9 和 TLR3 选择性激活 MyD88 依赖性和非依赖性途径，证实了马良酰胺 F 乙酸酯选择性抑制 MyD88 依赖性途径。据我们所知，这是第一个报道天然产物抑制 MyD88 依赖性途径的报告。
