Synovial Fluid Fatty Acid Profiles Are Differently Altered by Inflammatory Joint Pathologies in the Shoulder and Knee Joints.

Anne-Mari Mustonen,Reijo Käkelä,Sanna P Sihvo,Heikki Kröger,Antti Joukainen,Tommi Kääriäinen,Antti Jaroma,Tommi Paakkonen,Petri Lehenkari,Petteri Nieminen

doi:10.3390/biology10050401

Abstract

Simple SummaryAnomalies of fatty acid metabolism characterize osteoarthritis and rheumatoid arthritis in the knee joint. No previous study has investigated the synovial fluid fatty acid manifestations in these aging-related inflammatory diseases in the shoulder. The present experiment compared the fatty acid alterations between the shoulder and knee joints in trauma controls and in patients with end-stage osteoarthritis or end-stage rheumatoid arthritis. The fatty acid signatures in the synovial fluid of trauma controls were mostly uniform in both anatomical locations. Shoulders with rheumatoid arthritis were characterized by elevated percentages of arachidonic acid and docosahexaenoic acid and with reduced proportions of oleic acid. The fatty acid profiles of knees with osteoarthritis or rheumatoid arthritis were relatively uniform and displayed lower proportions of linoleic acid, docosahexaenoic acid and total n-6 polyunsaturated fatty acids. The results indicate location- and disease-dependent differences in the synovial fluid fatty acid composition. These alterations may affect joint lubrication, synovial inflammation and pannus formation as well as cartilage and bone degradation and contribute to the pathogeneses of inflammatory joint diseases.Anomalies of fatty acid (FA) metabolism characterize osteoarthritis (OA) and rheumatoid arthritis (RA) in the knee joint. No previous study has investigated the synovial fluid (SF) FA manifestations in these aging-related inflammatory diseases in the shoulder. The present experiment compared the FA alterations between the shoulder and knee joints in patients with end-stage OA or end-stage RA. SF samples were collected during glenohumeral or knee joint surgery from trauma controls and from OA and RA patients (n = 42). The FA composition of SF total lipids was analyzed by gas chromatography with flame ionization and mass spectrometric detection and compared across cohorts. The FA signatures of trauma controls were mostly uniform in both anatomical locations. RA shoulders were characterized by elevated percentages of 20:4n-6 and 22:6n-3 and with reduced proportions of 18:1n-9. The FA profiles of OA and RA knees were relatively uniform and displayed lower proportions of 18:2n-6, 22:6n-3 and total n-6 polyunsaturated FAs (PUFAs). The results indicate location- and disease-dependent differences in the SF FA composition. These alterations in FA profiles and their potential implications for the production of PUFA-derived lipid mediators may affect joint lubrication, synovial inflammation and pannus formation as well as cartilage and bone degradation and contribute to the pathogeneses of inflammatory joint diseases.

Highlights

Free fatty acids (FAs) are potential mediators of inflammation and cartilage and bone destruction in aging-related joint diseases such as osteoarthritis (OA) and rheumatoid arthritis (RA) [1,2]; the latter is autoimmune-driven and characterized by a higher inflammatory load [3]
The joints were categorized as trauma controls without a history of arthritis (n = 16), end-stage OA (n = 17) and end-stage
polyunsaturated FAs (PUFAs) such as give rise to numerous lipid mediators with a diverse joint health [3,12]. This is the pivotal issue that makes the interpretation of FA profiles potential to affect health [3,12]

Summary

Introduction

Free fatty acids (FAs) are potential mediators of inflammation and cartilage and bone destruction in aging-related joint diseases such as osteoarthritis (OA) and rheumatoid arthritis (RA) [1,2]; the latter is autoimmune-driven and characterized by a higher inflammatory load [3]. A recognized risk factor for OA due to altered joint loading and chronic low-grade systemic inflammation [4], is associated with elevated levels of circulating free FAs [5] and ratios of n-6 to n-3 polyunsaturated FAs (PUFAs) [6]. Saturated FAs (SFAs), palmitic and stearic acid (16:0, 18:0), have a mostly deleterious influence on joint tissues as they can induce endoplasmic reticulum stress, the production of cytokines and cartilage-degrading proteinases and chondrocyte apoptosis [14,15,16]. Long-chain n-3 PUFAs, especially eicosapentaenoic acid (20:5n-3, EPA), can have positive effects on synovium, cartilage and bone health [17,18,19]

Methods

Discussion

Conclusion