The role of the hypothalamic-pituitary-adrenal axis in rheumatoid arthritis.

It has become clear that there is a bidirectional communication between the neuroendocrine and the immune system and that both systems influence each other and interact under physiological conditions and in response to inflammatory stimuli. The hypothalamic-pituitary axis plays an important role in regulating and controlling immune responses and dysfunction of the axis has been implicated in the pathogenesis of rheumatoid arthritis (RA). Corticotrophin-releasing hormone (CRH), one of the main hormones of the axis, is also released extra-hypothalamically, peripherally at the site of inflammation and may modulate inflammatory responses locally. In this chapter we will discuss the role of the hypothalamic-pituitary-adrenal (HPA) axis and peripheral CRH, its influences on immune function and what is known about the possible pathogenetic role of the HPA axis and peripheral CRH in RA.