Chwastek_2025_Biomed.Pharmacother_186_118040

Human fibroblast-like synoviocytes (HFLS) are the predominant cellular component of the joint synovium. Their inflammation, known as synovitis, may contribute to the development of osteoarthritis (OA). HFLS secrete signaling factors that regulate joint function in response to mechanical trauma or OA progression. Among these factors, prostaglandin E2 (PGE(2)) is a key pro-inflammatory mediator, whereas prostamides, such as prostamide E2 (PME(2)), are synthesized from anandamide (AEA) by the same enzymes that produce PGE(2). HFLS were isolated from both control subjects and OA patients (HFLS-OA) and stimulated with lipopolysaccharide (LPS, 10 ng/mL). Liquid chromatography-tandem mass spectrometry (LC-MS) was used to analyze PGE(2) and PME(2) secretion. Additionally, transcriptome and miRNA sequencing were conducted to identify changes in gene expression between HFLS and HFLS-OA cells. Five endocannabinoid-related genes were further validated by qPCR. Baseline PGE(2) secretion differed between HFLS and HFLS-OA, with OA-related cells showing increased levels, while control cells primarily produced PME(2). Upon pro-inflammatory stimulation, both cell types secreted PGE(2). Changes in endocannabinoid levels and expression of endocannabinoid-related genes were observed in HFLS-OA following stimulation. miRNA sequencing revealed significant differences in miRNA expression between HFLS and HFLS-OA. Notably, HFLS-OA exhibited upregulation of Diacylglycerol lipase B (DAGLB) and downregulation of Fatty Acid-Binding Protein 4 and 5 (FABP4 and FABP5) gene expression compared to controls. The study suggests a reorganization of the endocannabinoid system in HFLS from OA patients, leading to altered cellular responses to pro-inflammatory stimuli. The molecular changes observed may drive or regulate the inflammatory response in OA synoviocytes, highlighting potential therapeutic targets. These findings provide insights into the potential mechanisms underlying OA pathogenesis and support the hypothesis of altered endocannabinoid system reactivity in HFLS in the context of inflammation.