Psychoneuroimmunology

Psychoneuroimmunology aims to understand the mechanisms of bidirectional interactions between the immune system and the nervous system, with an emphasis on the influence of stress and psychosocial factors on immunity and, reciprocally, immune influences on brain structure and function. On the side of the immune system, its major advances are the discovery of the expression of hormones and neuropeptides by immune cells and the innervation of lymphoid organs by the sympathetic nervous system. On the side of the nervous system, the brain cannot be considered any longer as an immune-privileged organ. It contains innate immune cells and is drained by meningeal lymphatic vessels that maintain immune surveillance. In addition, immune mediators and their receptors expressed by brain cells regulate synaptic function and brain response to peripheral inflammation. These neuroimmune interactions intervene in health and disease.