Synovial Fluid Metabolites Differentiate between Septic and Nonseptic Joint Pathologies

Abstract

Osteoarthritis (OA), osteochondrosis (OC), and synovial sepsis in horses cause loss of function and pain. Reliable biomarkers are required to achieve accurate and rapid diagnosis, with synovial fluid (SF) holding a unique source of biochemical information. Nuclear magnetic resonance (NMR) spectroscopy allows global metabolite analysis of a small volume of SF, with minimal sample preprocessing using a noninvasive and nondestructive method. Equine SF metabolic profiles from both nonseptic joints (OA and OC) and septic joints were analyzed using 1D 1H NMR spectroscopy. Univariate and multivariate statistical analyses were used to identify differential metabolite abundance between groups. Metabolites were annotated via 1H NMR using 1D NMR identification software Chenomx, with identities confirmed using 1D 1H and 2D 1H 13C NMR. Multivariate analysis identified separation between septic and nonseptic groups. Acetate, alanine, citrate, creatine phosphate, creatinine, glucose, glutamate, glutamine, glycine, phenylalanine, pyruvate, and valine were higher in the nonseptic group, while glycylproline was higher in sepsis. Multivariate separation was primarily driven by glucose; however, partial-least-squares discriminant analysis plots with glucose excluded demonstrated the remaining metabolites were still able to discriminate the groups. This study demonstrates that a panel of synovial metabolites can distinguish between septic and nonseptic equine SF, with glucose the principal discriminator.

Ex-VivoEquine Cartilage Explant Osteoarthritis Model - A Metabolomics and Proteomics Study

“…Additional MS based metabolomics analysis of the culture media within this study may be beneficial as NMR and MS are complementary techniques and would therefore expand the number of identified/quantified metabolites, additionally identifying potential lipid and carbohydrate profiles of interest 9,38,43,102 . In order to confirm the differentially abundant proteins within this study, validation using an orthologous technique e.g.…”

“…However, the underlying pathogenesis of OA is yet to be fully elucidated with no disease-modifying treatments currently available 7,8 . Whilst a number of putative biomarkers have been identified for OA diagnosis in the horse, none are currently used within clinical practice 9 . Presently, equine OA is predominantly diagnosed through diagnostic imaging and clinical examination.…”

“…1 H Nuclear magnetic resonance (NMR) metabolomics analysis provides a high level of technical reproducibility with a minimal level of sample preparation 38 . 1 H NMR analysis has previously been used to investigate OA in the SF of humans, horses, pigs and dogs 9,[39][40][41][42][43][44][45] . Synovial metabolites alanine, choline, creatine and glucose have been identified as differentially abundant in OA across multiple studies and species 9,39,[41][42][43][44] .…”

“…1 H NMR analysis has previously been used to investigate OA in the SF of humans, horses, pigs and dogs 9,[39][40][41][42][43][44][45] . Synovial metabolites alanine, choline, creatine and glucose have been identified as differentially abundant in OA across multiple studies and species 9,39,[41][42][43][44] . NMR techniques have also previously been used to characterise cartilage with high resolution magical angle spinning (HRMAS) NMR utilised to assess enzymatic degradation of bovine cartilage [46][47][48] .…”

Metabolomic analysis of synovial fluid from Thoroughbred racehorses diagnosed with palmar osteochondral disease using magnetic resonance imaging

“…It provides multi‐dimensional information on biochemical responses of complex systems to a range of intrinsic and environmental stimuli under specific circumstances , with the ultimate aim of serving as unique ‘fingerprints’ or disease biomarkers in named pathological states. Compared with other biochemical techniques, metabolomics requires minimal pretreatment and processing and has been used successfully in the rapid assessment of numerous systemic disease states in human and veterinary medicine . Metabolites within synovial fluid (SF) accurately represent activity of the surrounding synovial tissues, bones and cartilage and recent equine studies report successful differentiation of osteoarthritis , osteochondrosis and joint sepsis .…”