CXCL8 and fibromyalgia: For instance, T helper 2 (Th2) anti-inflammatory cytokines, including IL-4, IL-5 and IL-13, have been reported to decrease in fibromyalgia patients, whereas inflammatory cytokines IL-6 and IL-8 are found to elevate in fibromyalgia, indicating a potential role in the chronic pain of fibromyalgia (8, 9).