In mice, porphyran extracted from Pyropia yezoensis exerts anti-inflammatory effects and suppresses lipopolysaccharide (LPS)-induced immune activation and sepsis. Here, we investigated inhibition of LPS-induced activation of human immune cells by porphyran and the underlying mechanisms. We demonstrated that porphyran may inhibit LPS-induced proinflammatory cytokine production in peripheral blood mononuclear cells, monocyte-derived dendritic cells, and peripheral blood dendritic cells. We also observed that porphyran-mediated LPS-induced activation of DC suppressed syngeneic T cell proliferation, resulting in reduced production of interferon-γ. The mechanism of LPS-induced immune cell activation requires the activation of toll like receptor 4 following binding of LPS to myeloid differentiation factor 2 (MD2). Additionally, we show that porphyran competes with LPS for binding to MD2 and thereby suppresses immune cell activation. Porphyran may, therefore, be a promising therapeutic candidate for the treatment of endotoxin-mediated septic shock and inflammation in humans.

中文翻译：

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卟啉对脂多糖诱导的人类免疫细胞活化的抑制作用。

在小鼠中，从紫斑拟南芥中提取的卟啉具有抗炎作用，并抑制脂多糖（LPS）诱导的免疫活化和败血症。在这里，我们研究了卟啉对LPS诱导的人类免疫细胞激活的抑制作用及其潜在机制。我们证明了卟啉可能会抑制LPS诱导的外周血单核细胞，单核细胞衍生的树突状细胞和外周血树突状细胞中促炎性细胞因子的产生。我们还观察到，卟啉介导的LPS诱导的DC激活抑制了同基因T细胞增殖，从而降低了干扰素-γ的产生。LPS诱导的免疫细胞激活的机制需要在LPS与髓样分化因子2（MD2）结合后激活toll样受体4。此外，我们表明，卟啉与LPS竞争与MD2的结合，从而抑制了免疫细胞的活化。因此，卟啉可能是用于治疗人体内毒素介导的败血性休克和炎症的有前途的治疗候选物。