IL1B and juvenile idiopathic arthritis: Interestingly, we demonstrated that SF-FLS stimulation with the pro-inflammatory stimulus, TNF-α, which is present in the joint inflammatory environment in JIA patients and involved in disease pathogenesis [29], induced significantly increased expression of IL-8, MCP-1, IL-1β, CCL-5, IL-6, and CXCL5-coding mRNA levels without affecting expression of MMPs.