Purpose: The purpose of this study was to understand the impact of Demodex infection in the lipid component of meibum in patients.
Methods: The meibum samples were collected from four groups of subjects: (1) Demodex-negative with non-MGD (D-M-; n = 10); (2) Demodex-positive with non-MGD (D+M-; n = 10); (3) Demodex-negative with MGD (D-M+; n = 10); and (4) Demodex-positive with MGD (D+M+; n = 10). A liquid chromatography-mass spectrometry (LC-MS) system consisting of ultra-performance liquid chromatography and a Q Exactive high-resolution mass spectrometer was used for lipids separation and detection.
Results: Compared with the D-M- group, the D+M- group had lower levels of phosphatidylcholines (PCs) and lysophosphatidylcholines (LPCs) and higher levels of phosphatidylethanolamines (PEs). Compared with the D-M+ group, the levels of sphingomyelins (SMs) and PCs in the D+M+ group were decreased, whereas the levels of (O-acyl)-ω-hydroxy fatty acids (OAHFAs), ceramides (CERs), LPCs, and diacylglycerols (DGs) were significantly increased. Triacylglycerols (TGs), DGs, CERs, and OAHFAs were decreased in D-M+ group, whereas levels of PEs, phosphatidylinositols, and phosphatidylglycerols were increased in meibum obtained from the D-M+ group compared with those in the D-M- group. TGs, SMs, CERs, and PEs were decreased in the D+M+ group, whereas levels of LPCs, LPEs, PCs, and PEs were increased in meibum from the D-M+ group compared with those in the D+M- group.
Conclusions: To the best of our knowledge, this is the first study to assess the changes in meibum from patients with ocular Demodex infestation. The significant increase of OAHFAs in the Demodex-positive group suggest that OAHFAs may be associated with the progress of ocular Demodex infections.
Translational relevance: OAHFAs could be a potential new therapeutic target for ocular Demodex infestation.