Chronic inflammatory stress.

A major mechanism involved in maintaining homeostasis in response to chronic inflammation is the hypothalamo-pituitary-adrenal (HPA) axis, resulting in the release of anti-inflammatory glucocorticoids from the adrenal cortex. An inadequate HPA axis response may result in the development of a pathology or an increase in susceptibility and/or severity of disease. Other neuroendocrine systems are also implicated. Increasingly considered important are circadian rhythms, not only of hormones, but also of components of the immune system. Recent evidence concerning changes in hypothalamic control of the HPA axis following development of disease, the implication of these for the response to stress and the use of the HPA axis as a predictor of susceptibility to disease will also be considered. Finally, the influence of stress on autoimmune disease will be discussed. This chapter will concentrate principally on rheumatoid arthritis, although other autoimmune diseases and animal models will be discussed.