TNF and ankylosing spondylitis: Based on TNF-α-blocking studies, it has been concluded that in rheumatoid arthritis (RA) and other chronic inflammatory diseases, such as ankylosing spondylitis, psoriasis, and Crohn disease, increased concentrations of TNF-α are associated with neuroendocrine changes, including dysfunctional hypothalamic-pituitary-adrenal (HPA), hypothalamic-pituitary-gonadal (HPG), hypothalamus-pituitary-liver-muscle, and hypothalamic-autonomic nerve system (HANS) axes (reviewed in [16]).