Porphyromonas gingivalis produces five classes of serine/glycine lipids that are recovered in lipid extracts from periodontitis-afflicted teeth and diseased gingival tissues, particularly at sites of periodontitis. Because these lipids are recovered in diseased gingival tissues, the purpose of the present study was to evaluate the capacity of cultured human gingival fibroblasts (HGF), keratinocytes, and macrophages to hydrolyze these lipids. We hypothesize that one or more of these cell types will hydrolyze the serine/glycine lipids. The primary aim was to treat these cell types for increasing time in culture with individual highly enriched serine/glycine lipid preparations. At specified times, cells and culture media samples were harvested and extracted for hydrolysis products. The serine/glycine lipids and hydrolysis products were quantified using liquid chromatography–mass spectrometry (LC–MS) and free fatty acids were quantified using gas chromatograph–mass spectrometer. LC–MS analysis used two different mass spectrometric methods. This study revealed that treatment of HGF or macrophage (THP1) cells with lipid (L) 654 resulted in breakdown to L342 and subsequent release into culture medium. However, L654 was converted only to L567 in gingival keratinocytes. By contrast, L1256 was converted to L654 by fibroblasts and macrophages but no further hydrolysis or release into medium was observed. Gingival keratinocytes showed no hydrolysis of L1256 to smaller lipid products but because L1256 was not recovered in these cells, it is not clear what hydrolysis products are produced from L1256. Although primary cultures of gingival fibroblasts and macrophages are capable of hydrolyzing specific serine/glycine lipids, prior analysis of lipid extracts from diseased gingival tissues revealed significantly elevated levels of L1256 in diseased tissues. These results suggest that the hydrolysis of bacterial lipids in gingival tissues may reduce the levels of specific lipids, but the hydrolysis of L1256 is not sufficiently rapid to prevent significant accumulation at periodontal disease sites.

中文翻译：

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培养物中人牙龈细胞丝氨酸/甘氨酸脂质的代谢

牙龈卟啉单胞菌产生五类丝氨酸/甘氨酸脂质，这些脂质可从患有牙周炎的牙齿和患病牙龈组织（特别是牙周炎部位）的脂质提取物中回收。由于这些脂质是在患病牙龈组织中回收的，因此本研究的目的是评估培养的人牙龈成纤维细胞 (HGF)、角质形成细胞和巨噬细胞水解这些脂质的能力。我们假设这些细胞类型中的一种或多种将水解丝氨酸/甘氨酸脂质。主要目的是用单独的高度富集的丝氨酸/甘氨酸脂质制剂处理这些细胞类型以增加培养时间。在指定的时间，收获细胞和培养基样品并提取水解产物。使用液相色谱-质谱仪（LC-MS）对丝氨酸/甘氨酸脂质和水解产物进行定量，并使用气相色谱-质谱仪对游离脂肪酸进行定量。LC-MS 分析使用两种不同的质谱方法。这项研究表明，用脂质 (L) 654 处理 HGF 或巨噬细胞 (THP1) 细胞会导致其分解为 L342，并随后释放到培养基中。然而，L654 在牙龈角质形成细胞中仅转化为 L567。相比之下，L1256被成纤维细胞和巨噬细胞转化为L654，但没有观察到进一步水解或释放到培养基中。牙龈角质形成细胞未显示 L1256 水解成较小的脂质产物，但由于在这些细胞中未回收 L1256，因此尚不清楚 L1256 产生什么水解产物。尽管牙龈成纤维细胞和巨噬细胞的原代培养物能够水解特定的丝氨酸/甘氨酸脂质，但对患病牙龈组织的脂质提取物的先前分析显示，患病组织中 L1256 的水平显着升高。这些结果表明，牙龈组织中细菌脂质的水解可能会降低特定脂质的水平，但 L1256 的水解速度不够快，不足以防止牙周病部位的显着积累。