Neuroimmunotoxicology: Modulation of neuroimmune networks by toxicants

For the past few decades, neuroimmunology research has delineated pathways and mechanisms on the reciprocal interactions that exist between the nervous and immune systems. While there also has been a substantial amount of data on the effects of toxicants on the immune system (immunotoxicity) and the nervous system (neurotoxicity), the effects of toxicants on the dysregulation of one organ system leading to malfunctions of another, present a major concern for health. Building on substantiated neuroimmunological research, the multidisciplinary field of neuroimmunotoxicology has emerged. This review briefly describes some presently known links between the nervous and immune systems, namely the hypothalamic–pituitary–adrenal (HPA) axis and the autonomic (sympathetic and parasympathetic) nervous system, followed by a discussion of some mechanisms by which exposure to the prototypic toxicants, lead, mercury, and PCB's, may directly or indirectly modulate neuroimmune networks. Additionally, the possible sequelae of such exposures have been highlighted in relation to the etiology or progression of diseases and treatments.