Novel ceramides recovered from Porphyromonas gingivalis: relationship to adult periodontitis.

The primary purpose of this study was to characterize the major structural features of ceramides recovered from Porphyromonas gingivalis, a suspected periodontal pathogen. Complex lipids extracted from P. gingivalis were treated with N, O-bis(trimethylsilyl)-trifluoroacetamide and analyzed using gas chromatography-mass spectrometry. Mass spectra of lipid derivatives revealed cleavage products consistent with structures of four major ceramides. Two of the major ceramides are proposed to contain long chain bases of either 2-amino-1,3-octadecanediol or 2-amino-1, 3-nonadecanediol in amide linkage to 3-hydroxy isobranched C17:0. The remaining major ceramides are proposed to contain either 2-amino-1,3-octadecanediol or 2-amino-1,3-nonadecanediol in amide linkage to C17:1. Alkaline hydrolysis of P. gingivalis lipids and subsequent formation of suitable derivatives revealed 3-hydroxy isobranched C17:0, C17:1, 2-amino-1,3-octadecanediol, and 2-amino-1, 3-nonadecanediol as hydrolysis products. Therefore, the constitutive fatty acids and long chain bases recovered in alkaline hydrolysis products of P. gingivalis lipids are consistent with the proposed ceramide structures. The next goal of this study was to investigate whether these bacterial ceramides exist in lipid extracts of human teeth and gingival tissue at sites of severe adult periodontitis. Using selected ion monitoring of characteristic ions and retention times for each ceramide described above, lipids from teeth and gingival tissue were shown to contain primarily the ceramides containing C17:1. It is concluded that P. gingivalis synthesizes at least four major ceramides and two of these ceramides are selectively adsorbed to diseased tooth surfaces and may penetrate into diseased gingival tissue.