Table 1.
Characteristics of synovial fluid donors.
Figure 1.
Postmortem stability of lipids extracted from human synovial fluid of healthy knee joints used as controls.
Lipids were determined by electrospray ionization tandem mass spectrometry (ESI-MS/MS) or liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) as outlined in Material and Methods. Values are displayed as a scatterplot of the concentration of each lipid class and species by postmortem time. (A): Lipid classes, (B): Lipid species. SM-sphingomyelin, Cer-ceramide, HexCer-hexosylceramide (most likely glucosylceramide), Hex2Cer-dihexosylceramide (most likely lactosylceramide), PA-phospatidic acid, LPA-lysophosphatidic acid, PG-phosphatidylglycerol, LPG-lysophosphatidylglycerol.
Figure 2.
Concentrations of sphingomyelin species in human knee synovial fluid.
Synovial fluid was obtained from donors serving as controls and from patients with early osteoarthritis (eOA), late OA (lOA), and rheumatoid arthritis (RA). SM species were determined by electrospray ionization tandem mass spectrometry as outlined in Material and Methods. Species annotation is based on the notion that 2 hydroxyl groups are linked to a sphingoid base. Values are presented as median and interquartile range. Significance was considered in the following way: a: p≤0.05: control vs eOA; b: p≤0.05: control vs lOA; c: p≤0.05: control vs RA; d: p≤0.05: eOA vs lOA; and e: p≤0.05: eOA vs RA. SM- sphingomyelin.
Figure 3.
Concentrations of ceramide species in human knee synovial fluid.
Synovial fluid was obtained from donors serving as controls and from patients with early osteoarthritis (eOA), late OA (lOA), and rheumatoid arthritis (RA). Cer species were determined by electrospray ionization tandem mass spectrometry as outlined in Material and Methods. Values are presented as median and interquartile range. Significance was considered in the following way: a: p≤0.05: control vs eOA; b: p≤0.05: control vs lOA; c: p≤0.05: control vs RA; d: p≤0.05: eOA vs lOA; and e: p≤0.05: eOA vs RA. (A): Cer species, (B): HexCer and Hex2Cer species. Cer- ceramide, HexCer- hexosylceramide (most likely glucosylceramide), Hex2Cer- dihexosylceramide (most likely lactosylceramide).
Figure 4.
Relative distribution of HexCer and Hex2Cer, PA, LPA, PG and LPG species in in human knee synovial fluid.
Synovial fluid was obtained from donors serving as controls and from patients with early osteoarthritis (eOA), late OA (lOA), and rheumatoid arthritis (RA). The data show the percentage of the lipid species from the total corresponding lipid class ( = 100%). Values are presented as median and interquartile range. (A): HexCer and Hex2Cer species, (B): PA and LPA species, (C): PG and LPG species. HexCer- hexosylceramide (most likely glucosylceramide), Hex2Cer- dihexosylceramide (most likely lactosylceramide), PA- phosphatidic acid, LPA- lysophosphatidic acid, PG- phosphatidylglycerol, LPG- lysophosphatidylglycerol.
Table 2.
Concentrations of bis(monoacylglycero)phosphate (BMP) species.
Figure 5.
Concentrations of phosphatidic acid (PA) and lysophosphatidic acid (LPA) species in human knee synovial fluid.
Synovial fluid was obtained from donors serving as controls and from patients with early osteoarthritis (eOA), late OA (lOA), and rheumatoid arthritis (RA). PA and LPA species were determined liquid chromatography coupled with tandem mass spectrometry as outlined in Material and Methods. Species annotation is based on the notion that only ester bonds are present. Values are presented as median and interquartile range. Significance was considered in the following way: a: p≤0.05: control vs eOA; b: p≤0.05: control vs lOA; and c: p≤0.05: control vs RA. (A): PA species, (B): LPA species. PA- phosphatidic acid, LPA- lysophosphatidic acid.
Figure 6.
Concentrations of phosphatidylglycerol (PG) and lysophosphatidylglycerol (LPG) species in human knee synovial fluid.
Synovial fluid was obtained from donors serving as controls and from patients with early osteoarthritis (eOA), late OA (lOA), and rheumatoid arthritis (RA). PG and LPG species were determined by liquid chromatography coupled with tandem mass spectrometry as outlined in Material and Methods. Species annotation is based on the notion that only ester bonds are present. Values are presented as median and interquartile range. Significance was considered in the following way: a: p≤0.05: control vs eOA; b: p≤0.05: control vs lOA; c: p≤0.05: control vs RA; d: p≤0.05: eOA vs lOA; e: p≤0.05: eOA vs RA; and f: p≤0.05: lOA vs RA. PG- phosphatidylglycerol, LPG- lysophosphatidylglycerol.
Figure 7.
Concentrations of lipids in human synovial fluid as a function of the age of patients with late stage osteoarthritis.
Lipids were determined by electrospray ionization tandem mass spectrometry (ESI-MS/MS) or liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) as outlined in Material and Methods. Values are displayed as a scatterplot of the concentration of each lipid class and species by age of donors. (A): Lipid classes, (B): Lipid species. SM-sphingomyelin, Cer-ceramide, HexCer-hexosylceramide (most likely glucosylceramide), Hex2Cer-dihexosylceramide (most likely lactosylceramide), PA-phospatidic acid, LPA-lysophosphatidic acid, PG-phosphatidylglycerol, LPG-lysophosphatidylglycerol.
Table 3.
Impact of dilution factor on the concentrations of lipid classes.