Abstract / Summary
The cytokine response is well documented in serum and synovial fluid during prosthetic joint infection (PJI), the leading complication following total knee arthroplasty. However, the temporal profile of cytokines in infected tissue at the joint remains unresolved. Therefore, the role of cytokine signaling during PJI progression and the potential use of cytokines as markers for surgical debridement are not yet established. The objective of this study was to quantify infection development and tissue-level cytokine concentrations across time to provide insights relevant to the interplay between localized cytokines and PJI. Tissues from Sprague-Dawley rats were collected at 1, 7, 10, and 21 days following Kirschner wire (K-wire) implantation and inoculation with Staphylococcus aureus ( S. aureus ). Bacterial burden reached a maximum by 7 to 10 days for both bone and muscle tissue. This time course was comparable to that of the immunofluorescent-labeled S. aureus on K-wires, characteristic of biofilm formation. Concentrations for eight of the cytokines (IL-4, IL-5, IL-6, IL-10, IL-12, IL-13, TNFα, and IFNγ) were most pronounced at day 1, while IL-1α and IL-1β levels were elevated in the subsequent postoperative days. The results demonstrate initial inflammatory signaling to clear infection, followed by a cytokine profile consistent with cytokine-mediated immune suppression in the presence of S. aureus , thereby allowing infection to persist. This study demonstrates a nuanced role of cytokines in the setting of biofilm formation during chronic PJI and insights for developing these markers in guiding tissue debridement.