TNF and fibromyalgia: Fibromyalgia is characterized by heightened sensitivity to pain in the central nervous system and may influence the pathogenesis of asthma through mechanisms involving proinflammatory cytokines (e.g. IL-6, TNF-α), neuropeptides (e.g. substance P), and hypothalamic-pituitary-adrenal (HPA) axis dysfunction [7,8].