Page - (000137) - in Biomedical Chemistry: Current Trends and Developments

Stress affects many central and peripheral systems in the body, and the immune system is critical for the promotion of survival; therefore, it has key roles during the stress response and immune functions can be enhanced or suppressed by stressors. Endocrine and cytokine mediators modulate the immune function during short-term acute stress, which can modulate immune responsiveness encompassing humoral and cellular aspects of both innate and adaptive immune responses. The humoral changes related to stress response to psychological stressors, such as the Trier Social Stress Test, include significant increases in the concentration of cytokines, including interleukin-6 (IL- 6) and IL-1ß (Altemus, 2001; Aschbacher, 2012; Pace, 2006; Prather, 2013; Puterman, 2014; Steptoe, 2007). Cytokines are small proteins released by the immune system, typically under inflammatory situations. These increased circulating cytokine levels may enhance the immune system during acute stress, contribute to survival, and are also related to emotional states. Peripheral IL-6 levels during stress reaction are related to the experience of anger; it is likely that an angry individual will engage in an aggressive confrontation and sustain injuries and an enhanced immune response will help promote wound healing (Puterman, 2014). It is now understood that peripheral cytokines modulate brain functions during physiological conditions, where they can regulate neuronal processes, including stress, inflammatory challenges, sickness behaviour, feeding, sleep, learning and memory (Vitkovic, 2000a; 2000b), and that the communication between the brain and the immune system is bidirectional. Our lab has contributed to the understanding of many of the central aspects of cytokine response. We described the expression of cytokines and immunomediators in the brain during baseline and after inflammatory challenges (Licinio, 1991, 1992; Wong, 1997; 1996; Wong & Licinio, 1994); during systemic inflammation, there is a high expression of central IL-1ß. Contrary to the potent systemic counter regulatory anti-inflammatory response, in the brain the expression of counter regulatory cytokines, such as IL-1 receptor antagonist and IL-10, is much lower, which supports that differential regulation of anti-inflammatory cytokines in the CNS and periphery (Wong, 1997).