Psychoneuroimmune phenomena: Neuroimmune interactions

The belief that emotions and conflicts affect our health is profoundly engrained in our culture. Psychoneuroimmunology is the discipline that studies the modalities of interactions between the immune system and the central nervous system and their functional outcomes. Clinical and preclinical studies in this field have confirmed the sensitivity of the immune system to psychosocial stressors and deciphered the pathways of communication from the brain to the immune system, including innervation of the lymphoid organs. However, it has become apparent that influences of the brain on the immune system are part of a regulatory pathway that enables the whole organism to cope with infectious agents. The immune system functions as a sensory organ that is specialized in the detection of pathogens. This information is relayed to the brain via cytokines. In response to the peripheral immune message, innate immune cells in the brain produce cytokines that act on neuronal networks to reorganize priorities in which the immune system that is specialized in the monitoring of pathogens recruits the brain to help cope with infection. Alterations in these immune-to-brain communication pathways can lead to functional disorders such as fatigue, chronic pain, and depression, and precipitate structural alterations involved in neuropathology.