ABSTRACT
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 509 Interactions among the Nervous, Endocrine, and Immune Systems . . . . . . . 510
Stress and Immune Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511 Stress-Associated Dysregulation of Cytokine Production . . . . . . . . . . . . . . 511 Stress-Related Susceptibility to Viral Infections . . . . . . . . . . . . . . . . . . . . . . 511 Effect of Stress on Reactivation of Latent Herpesviruses . . . . . . . . . . . . . . . 512 Stress-Related Effects on Immune Responses to Vaccinations . . . . . . . . . . . 514 Stress and Tumorigenesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517
Rodent Models and the Elucidation of the Role of Stress on the Exacerbation of Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 519 Discussion and Directions for Future Research . . . . . . . . . . . . . . . . . . . . . . . . . . . 519 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 520
Stress has been defi ned as a condition arising from events or environmental demands that exceed an individual’s perceived ability to cope.1,2 Pioneering work by Selye and others suggests that stress is associated with increases in the occurrence of various diseases in humans, including infectious diseases and cancer.3,4 These studies led to the formation of the interdisciplinary fi eld of psychoneuroimmunology (PNI) that focuses on the infl uence of the stress response on the interactions among the central nervous system (CNS), the endocrine system, and the immune system, and its impact on health. Several types of stressors in humans and rodent models have been utilized to show the diversity of effects that the various stressors can have on the immune system.5-9 Studies have shown that although chronic stress (persisting for weeks, months, or years) generally has a negative effect on the immune system, acute stress (lasting from minutes to hours) can result in the up-regulation of some immune parameters thereby exacerbating clinical symptoms such as skin allergies and asthma. Studies have shown
that psychological stress can dysregulate immune responses by modulating the bi-directional communication between the nervous, endocrine, and immune systems, within this complex network.10-12 This chapter provides a review of human studies and animal models that focuses on stress and its effects on the immune response against infectious agents, emphasizing the implications of these effects on resistance to disease.
