Intraarticular and systemic inflammatory profiles may identify patients with osteoarthritis

To determine whether cytokine/chemokine profiles from synovial fluid and sera discriminate mild/moderate osteoarthritis (OA) from normal and severe OA cohorts.

Multiplex technology was used to quantify expression levels for 42 cytokines in the synovial fluid of patients diagnosed with severe OA (n = 20) and mild/moderate OA (n = 12), as well as normal controls (n = 34). The same 42 cytokines were examined in serum samples of patients with severe OA (n = 26) and mild/moderate OA (n = 74) and normal individuals (n = 100). Treatment group comparisons followed by principal component analysis (PCA) and K-means clustering of the significantly different cytokines/chemokines revealed groupings of patients by physician diagnosis.

Differences in cytokine/chemokine levels were found between control, mild/moderate OA, and severe OA synovial fluid samples, as well as between normal and mild/moderate OA serum samples, and between control and severe OA serum samples. No differences were observed between mild/moderate and severe OA serum samples. Visual groupings based on PCA were validated by K-means analysis, with the best results obtained from the comparison of normal and mild/moderate OA serum samples with 96% of normal and 93% of mild/moderate OA samples accurately identified.

Our study suggests that comparing the expression levels of cytokines/chemokines in synovial fluid and/or serum of patients with OA may have promise as a diagnostic platform to identify patients early in their disease course. This high-throughput low-cost assay may be able to provide clinicians with a diagnostic test to complement existing clinical and imaging modalities currently used to diagnose OA.