A drug development study for a periodontal disease : Biological properties of synthetic lipid A of Porphyromonas gingivalis lipopolysaccharide

化学合成了从牙龈假单胞菌脂蛋白A中分离得到的五酰二磷基脂A分子(J细菌1995：177：2098)，并对其性质进行了评价，以证实其具有低内毒素活性和对内毒素反应不敏感的C3H/HeJ小鼠细胞的活性。合成的牙龈假单胞菌类脂A(人工合成的PG-LA)在所有的脂多糖反应小鼠和细胞试验中显示出几乎与大肠杆菌类型的合成类脂A(化合物506)相当的活性。牙龈假单胞菌的脂多糖和天然类脂A具有总的内毒素活性，但与合成的类似物相比，其效力有所降低。在用C3H/HeJ小鼠细胞进行的检测中，内毒素和天然脂质A显著刺激脾细胞产生有丝分裂，并刺激巨噬细胞产生肿瘤坏死因子-D和白介素6。然而，合成的PG-LA和化合物506对内毒素无反应的细胞没有活性。用几种I-…进行抑制试验更多的抑制剂，包括抗人TLR2和TLR4/MD-2复合单抗表明，合成的PG-LA的生物活性仅通过TLR4信号通路介导，TLR2可能与CD14一起与TLR4信号通路有关，TLR4信号通路可能与TLR4信号通路有关。这些结果表明，牙龈假单胞菌和天然脂A生物活性的调节和降低，包括TLR2介导的对C3H/HeJ小鼠细胞的活性，可能是由具有多个类脂A基团的天然制剂中存在的生物活性污染物或低酰化分子介导的。为了阐明这些问题，我们现在正试图使用每一种化学合成的类似物来评估具有牙龈假单胞菌天然脂A中主要分子的四酰化单磷酸化或二磷酸化物种的生物学特性。较少

A pentaacyl and diphosphoryl lipid A molecule (J Bacteriol 1995: 177: 2098) found in the lipid A isolated from P. gingivalis LPS was chemically synthesized, and its characteristics were evaluated to reconfirm its interesting bioactivities including low endotoxicity and activity against LPS-unresponsive C3H/HeJ mouse cells. The synthesized P. gingivalis lipid A (synthetic Pg-LA) exhibited strong activities almost equivalent to those of Escherichia coli-type synthetic lipid A (compound 506) in all assays on LPS-responsive mice, and cells. LPS and native lipid A of P. gingivalis displayed overall endotoxic activities, but its potency was reduced in comparison to the synthetic analogs. In the assays using C3H/HeJ mouse cells, the LPS and native lipid A significantly stimulated splenocytes to cause mitosis, and peritoneal macrophages to induce TNF-D and IL-6 production. However, synthetic Pg-LA and compound 506 showed no activity on the LPS-unresponsive cells. Inhibition assays using some i … More nhibitors including anti-human TLR 2 and TLR4/MD-2 complex monoclonal antibodies showed that the biological activity of synthetic Pg-LA was mediated only through the TLR4 signaling pathway that might act as a receptor for LPS, whereas TLR2, possibly together with CD14, was associated with the signaling cascade for LPS and native lipid A of P. gingivalis, in addition to the TLR4 pathway. These results suggested that the moderated and reduced biological activity of P. gingivalis LPS and native lipid A, including the activity on C3H/HeJ mouse cells by TLR2-mediated pathway, may be mediated by bioactive contaminants or low acylated molecules present in the native preparations having multiple lipid A moieties.In conclusion, these findings suggested that the moderated and reduced biological activity of P. gingivalis LPS and native lipid A, including the activity on C3H/HeJ mouse cells by TLR2-mediated pathway, may be mediated by bioactive contaminants or low acylated molecules present in the native preparations having high heterogeneity in lipid A moiety. To elucidate these problems, we are now attempting to evaluate the biological characterizations of tetra-acylated monophosphorylated or diphosphorylated species with the predominant molecules found in P. gingivalis native lipid A, using each chemically synthesized analog. Less