Participants
Disease group: Subjects were assessed by BDD-YBOCS (Yale - Brown Obsessive - Compulsive Scale Modified for Body Dysmorphic Disorder), and patients with a score of 20 and above were included in this group. Finally, 8 patients with depression caused by appearance were selected as the disease group.
Normal group: Subjects with a score of 20 and above diagnosed by BDD-YBOCS. No history of other psychiatric diseases, no clinical physical diseases, no history of drug abuse or allergy, no history of alcoholism, no special eating habits, and no abnormality in routine physical examination. Age 20–75 years old, no gender restriction. Eight healthy people were selected as the normal group.
The study was approved by the Institutional Research Ethics Committee of the Affiliated Hospital of Nanjing University of Chinese Medicine. Each volunteer was informed about the basic information of the study and obtained consent, and signed the informed consent form.
Collect Serum Samples
All volunteers took blood on an empty stomach in the morning (8:00–10:00). 3mL of fresh venous blood was drawn from each patient through the middle cubital vein and placed in a BD blood collection tube coated with a coagulant. The serum was separated by centrifugation at 3000rpm/min for 15min, and 65µL of the supernatant was dispensed into 200µL centrifuge tubes. Make a record and store in a -80℃ refrigerator for later use.
Lc-ms Analysis
Take out the sample from − 80℃ refrigerator, dissolve on ice, take 50µL sample, add 1mL extract solution (methanol:acetonitrile = 3:1, -4℃ pre-cooling), vortex for 5min, sonicate for 15min, stand at 4℃ for 2h. Centrifuge at 12000rpm, 4℃ for 15 min, take the supernatant, and concentrate the dry powder in vacuo. Add 100 µL of 50% methanol in water to reconstitute. 2000rpm, 4℃, vortex for 3min, 12000rpm, 4℃, centrifuge for 15min, take the supernatant for injection analysis.
The samples were placed in an 8℃ autosampler and separated using a HSS T3 column. The injection volume was 2µL, the column temperature was 40℃, and the flow rate was 0.3mL/min. Chromatographic mobile phase(A: 0.1% formic acid in water, B: 0.1% formic acid in methanol, C: 0.05% acetic acid in water, D: 0.05% acetic acid in methanol). The chromatographic gradient elution program is as follows: Positive ion: 0-0.5min, B: 2%; 0.5-6min, B: 2–50%; 6-10min, B: 50–98%; 10-14min, B: 98%; 14-16min, B: 98 − 2%; 16-21min, B: 2%. Negative ion: 0-0.5min, D: 2%; 0.5-6min, D: 2–50%; 6-10min, D: 50–98%; 10-14min, D: 98%; 14-16min, D: 98 − 2%; 16-21min, D: 2%. QC standards are inserted into the samples to monitor and evaluate the stability of the system and the reliability of the experimental data.
The samples were detected by ESI (electrospray ionization) in positive and negative ion modes, respectively. The samples were separated by UHPLC and analyzed by mass spectrometry using a Thermo QE HF-X mass spectrometer. Mass spectrometry conditions: ionization source: ESI ion source, sheath gas flow rate: 30; auxiliary gas: 10; spray voltage: 2.5KV(+)/2.5KV(-); S-Lens RF: 50; capillary temperature: 325℃; Gas temperature: 300°C; secondary collision energy (NCE): 30; isolation window 1.5m/z, Top N = 8. Scanning range: 70-1050m/z, scanning mode: positive and negative ion scanning respectively. Analysis was performed using Xcalibur 4.1.
Data Preprocessing
Raw data were subjected to Compound Discovery for peak alignment, retention time correction, and extraction of peak areas. Metabolite structure identification was performed using Compound Discovery by accurate mass matching (< 10ppm) and secondary spectral matching to search databases for comparison. Multidimensional statistical analysis, including PCA analysis, PLS-DA and OPLS-DA, was performed using the R statistical software ropls tool.