Abstract
Objective: To investigate the interaction of infrapatellar fat pad/cartilage and related mechanisms in knee osteoarthritis (OA) using the metabolomics method.Method: Fat-conditioned media (FCM) of the infrapatellar fat pad from patients with OA were used to treat human OA chondrocytes. The extracellular metabolites of human OA chondrocytes were detected by nontargeted metabolic footprint analysis based on liquid chromatography and mass spectrometry (LC-MS). Then, the different metabolites were found, and the main metabolic pathways were explored, combined with bioinformatics methods.Results: After treatment with FCM for 48 h, the proliferation of human OA chondrocytes was slowed down, indicating that FCM had a certain inhibitory effect on the proliferation of human OA chondrocytes (P = 0.023). On the pattern diagram of principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA), after FCM treatment, the data sample areas were obviously separated, indicating that FCM can significantly affect the metabolic footprint of human OA chondrocytes. Through metabonomic identification, 131 different metabolites were screened after FCM treatment compared with before treatment. For 4 pathways in total, significantly different activity levels were discovered in pairwise comparisons: alanine, aspartate, and glutamate metabolism; citrate cycle (TCA cycle); arginine and proline metabolism; and phenylalanine metabolism.Conclusion: The infrapatellar fat pad aggravates OA chondrocyte injury and is involved in OA by disturbing the chondrocyte TCA cycle, amino acid metabolism, and glutamine metabolism, among others.