Stress and immunity, from the traditional and classic, to long-term effects

Abstract

In ensuring the primary goal of preservation, the brain and the immune system operate coordinately. The former monitors the social environment all the time, to interpret the signals arising from there, and hence to assess the extent to which the environment is safe or threatening. The second one plays an essential role in the distinction between self and non-self to consequently protect the host from damage. Beyond the type of threat, we react from the neuro-immuno-endocrine interface within the context of an adaptive strategy aimed at safeguarding the welfare state against injuries. Broadly speaking, stress results in a series of complex responses that mainly involve the hypothalamic-pituitary-adrenal axis and the autonomic nervous system. They represent the hormonal and neural components, respectively, which can promote short and long-term changes in behavior, cardiovascular, endocrine, metabolic functions, and the defensive machinery, which ultimately lead us to “fight or flight” when having to cope with stressors from different nature. On occasions where potentially stressful processes become recurrent, perpetuated, or arise during the early maturation stages, the possibility of long-term negative health consequences becomes likely. Many studies indicate that factors such as abuse, abandonment, distressing family situations, wars, or natural disasters during childhood are related to a series of alterations in adult life reflected in an unequal responsive mode to subsequent stress, presence of bad habits (smoking, alcoholism, drug addiction and promiscuous behaviors), psychiatric diseases, as well as different degrees of organ dysfunction, particularly in the gastrointestinal and cardiovascular systems; and additional disorders of the immune system. The role of epigenetics, particularly changes in DNA and histones, along with their known impact on the regulation of gene transcription, appears to be a relevant underlying mechanism in this regard.