Substance P and Human Immunodeficiency Virus Infection: Psychoneuroimmunology

Effects on the immune system caused by changes in behavioral state or brain activity are mediated, at least in part, through neuroendocrine-immune pathways. Life stress and depression may be associated with altered blood levels of central nervous system-released neuropeptides, including substance P (SP). SP acts as a neuroregulator or neurotransmitter in the conduction of nociceptive stimuli, and is a modulator of neuroimmunoregulation. This review summarizes current knowledge regarding the role of the neuropeptide, SP, in psychoneuroimmunology, in particular as it relates to human immunodeficiency virus infection and acquired immunodeficiency disease syndrome. The association between depression, anxiety, and stress in HIV-disease progression suggests that neurobiologic and neurophysiologic factors play a role in modulating HIV infection and responses to antiretroviral therapy. Individuals with HIV or AIDS may experience stressful life circumstances that can result in increased symptoms of anxiety, stress, and/or depression. Furthermore, psychological and psychiatric symptoms, which occur in individuals with HIV and AIDS, may be related to the progression of AIDS disease. This review presents evidence from the literature, as well as findings from basic investigations conducted in the authors' laboratories, demonstrating that SP may play an important role in HIV pathophysiology. SP can impact the susceptibility of immune cells to HIV infection and modulate immune cell functions in ways that may affect the course of HIV in infected individuals. Moreover, modulation of SP activity and SP receptor is being explored for its potential as a novel therapeutic approach to the treatment of some psychological and psychiatric disorders and to the design of new anti-HIV therapy.