Application of autoantibody markers based on phage display immunoprecipitation sequencing technology in the diagnosis of periprosthetic joint infections.

BACKGROUND: Accurate diagnosis of periprosthetic joint infection (PJI) is critical yet challenging. The role of autoantibodies in PJI remains largely unexplored. In this study, we employed phage display immunoprecipitation sequencing (PhIP-Seq) to profile PJI-associated autoantibodies and assess their diagnostic utility in PJI.

METHODS: We collected plasma samples from a cohort of 45 patients, including 25 with PJI, 9 with aseptic loosening, and 11 post-primary arthroplasty without complications. Initially, PhIP-Seq screening was performed on 10 samples (five PJI and five post-primary arthroplasty) to identify significantly differentially expressed autoantibodies. Subsequently, the immunoglobulin G (IgG) levels of these specific autoantibodies were quantified in the plasma of all participants via ELISA, and statistical analysis was performed to evaluate their diagnostic performance in PJI.

RESULTS: PhIP-Seq identified IFT80 and VPS54 as PJI-associated autoantigens. ELISA confirmed significantly elevated levels of corresponding IgG antibodies in PJI patients compared to those with aseptic loosening or post-primary arthroplasty (p < 0.01). Both autoantibodies demonstrated preliminary diagnostic performance: IFT80 achieved an area under the curve (AUC) of 0.797 (sensitivity = 56.0%, specificity = 95.0%), while VPS54 yielded an AUC of 0.776 (sensitivity = 72.0%, specificity = 75.0%). A combined diagnostic model integrating both biomarkers further enhanced the diagnostic performance (AUC = 0.810, sensitivity = 68.0%, specificity = 80.0%).

CONCLUSION: This study establishes IFT80 and VPS54 as novel autoantibodies in PJI. Their corresponding autoantibodies exhibit robust diagnostic potential, offering support for the development of serological assays to improve PJI diagnosis.