Stress, hypoxia, and immune responses

Abstract

Humans subjected to hostile environments are more prone and vulnerable to infections due to the complex interaction of various stressors. Besides other mechanisms known to induce immune imbalance and suppression as described in this book, this chapter focuses on the still very little known role of hypoxia-triggered immunosuppressive mechanisms in astronauts/cosmonauts e.g. during long-duration space missions. Such hypoxia signaling-dependent pathways might act additionally to those stimulated by neurohumoral mediators of the stress response even in the absence of hypoxia i.e. under normoxia. Altogether, hypoxic and normoxic pathways of the neurohumoral stress response may synergistically result in immune dysfunctional states, also pending on the duration of exposition. The role of hypoxia is of emerging interest to spaceflight, since hypobaric living conditions and hypoxemic tissue perfusion are not unlikely to occur in the future of human space exploration as due to technical and operational needs.