Interestingly, interleukin-1 receptor antagonist protein (IL1RN) was upregulated in the septic arthritis joints compared to the experimentally induced non-septic synovitis (fold change 9.3, p < 0.01), and was upregulated in the synovial fluid with septic arthritis before the eradication of infection (PID1) compared to post eradication of infection (PID4), with the adjusted p-value being close to the significance cut-off used in this study (fold change 4.2; p = 0.014). The gene discussed is IL1RN; the disease is bacterial arthritis.