The synovial fluid proteome differentiates between septic and nonseptic articular pathologies

Area of Science:

• Equine medicine
• Proteomics
• Veterinary diagnostics

Background:

• Articular conditions like osteoarthritis, osteochondrosis, and synovial sepsis are prevalent in horses, causing pain and loss of function.
• Accurate diagnosis, monitoring, and prognostication of these equine joint diseases remain challenging for veterinarians.
• Synovial fluid analysis offers potential for understanding and diagnosing joint pathologies.

Purpose of the Study:

• To identify specific protein biomarkers in equine synovial fluid for osteoarthritis, osteochondrosis, and synovial sepsis.
• To differentiate protein expression patterns associated with healthy joints versus arthropathic conditions.
• To explore the potential of identified proteins for improving clinical diagnosis and prognosis in horses.

Main Methods:

• Synovial fluid from horses with various joint conditions was analyzed using liquid chromatography-tandem mass spectrometry after protein enrichment.
• Label-free quantification was employed to analyze changes in protein abundance.
• Enzyme-linked immunosorbent assay (ELISA) was used for validation of key protein markers.

Main Results:

• Distinct proteomic profiles were observed in synovial fluid differentiating between healthy joints, osteoarthritis, osteochondrosis, and synovial sepsis.
• Elevated lactotransferrin (LTF) and decreased insulin-like growth factor-binding protein 6 (IGFBP6) levels were significantly associated with synovial sepsis.
• Pathway analysis revealed complement system upregulation in sepsis and downregulation of translation initiation and mTOR signaling in osteoarthritis and osteochondrosis.

Conclusions:

• The equine synovial fluid proteome exhibits unique changes related to specific joint pathologies.
• Lactotransferrin and insulin-like growth factor-binding protein 6 show promise as biomarkers for early and reliable diagnosis of equine synovial sepsis.
• These findings contribute to a better understanding of the pathogenesis of equine articular diseases and may inform future diagnostic strategies.