Synergy of local, regional, and systemic non-specific stressors for host defense against pathogens.

ABSTRACT

The immune brinksmanship conceptual model postulates that many of the non-specific stressful components of the acute-phase response (e.g. fever, loss of appetite, iron and zinc sequestration) are host-derived systemic stressors used with the "hope" that pathogens will be harmed relatively more than the host. The concept proposes that pathogens, needing to grow and replicate in order to invade their host, should be relatively more vulnerable to non-specific systemic stress than the host and its cells. However, the conceptual model acknowledges the risk to the host in that the gamble to induce systemic self-harming stress to harm pathogens may not pay off in the end. We developed an agent-based model of a simplified host having a local infection to evaluate the utility of non-specific stress, harming host and pathogen alike, for host defense. With our model, we explore the benefits and risks of self-harming strategies and confirm the immune brinksmanship concept of the potential of systemic stressors to be an effective but costly host defense. Further, we extend the concept by including in our model the effects of local and regional non-specific stressors at sites of infection as additional defenses. These include the locally hostile inflammatory environment and the stress of reduced perfusion in the infected region due to coagulation and vascular leakage. In our model, we found that completely non-specific stressors at the local, regional, and systemic levels can act synergistically in host defense.