Lögters et al. demonstrated that (i) synovial kynurenine values and ratio of kynurenine/tryptophan in septic arthritis patients were significantly increased compared to patients with non-infectious inflammatory arthropathy or OA (30), and there is a significant positive correlation between kynurenine values and synovial interleukin-1β and interleukin-6 in synovial fluid, indicating that the activation of kynurenic pathway is a consequence of inflammation (89). This evidence concerns the gene IL6 and bacterial arthritis.