Background/Purpose: We recently discovered that lysophosphotidylcholines (lysoPCs) to phosphotidylcholines (PCs) ratio was associated with knee osteoarthritis (OA), suggesting that the conversion of PCs to lysoPCs catalyzed by phospholipases A2 (PLA2) was over activated. The aim of the study was to examine the gene expression levels of multiple PLA2 enzymes in human cartilage and identify the specific one that is important in OA.

Methods: Human cartilage samples were collected from patients undergoing total hip/knee joint replacement surgery due to primary OA or hip fractures as controls. RNA was extracted from the cartilage tissues. mRNA levels of three PLA2 enzymes, namely PLA2IIa, IVa, and V, and three cytokines, namely IL-6, IL-1β, and TNF-α were measured by real-time quantitative PCR (qPCR). Expression levels in each sample were calculated as fold changes in relation to the calibrator using Livak method.

Results: A total of 33 OA cases (24 hip OA and 9 knee OA) and 21 healthy controls were included. We found that PLA2V expression level was substantially increased by 445% in OA-affected cartilage compared to OA-free cartilage (p=0.003), but not PLA2IIa and PLA2IVa (p>0.05). Similarly, the expression level of TNF-α was significantly increased by 193% in OA-affected cartilage compared to the OA-free cartilage (p=0.007), but not IL-6 and IL-1β. Further, the expression level of PLA2V was highly correlated with TNF-α expression with a correlation coefficient of 0.71 (p<0.0001).

Conclusion: Our data indicated that inflammatory process was involved in OA and resulted in substantial over expression of PLA2V and excessive conversion of PCs to lysoPCs, suggesting PLA2V could be a novel therapeutic target for OA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/phospholipase-a2-group-5-is-a-potential-therapeutic-target-for-osteoarthritis-treatment/