Guarding versus self-guarding in innate immunity

Area of Science:

• Innate immunity and host-pathogen interactions.
• Evolutionary dynamics of immune receptor systems.

Background:

• Hosts detect pathogens directly via pathogen-associated molecular patterns (PAMPs) or indirectly through 'guarding' immune receptors.
• Guarding involves immune receptors monitoring pathogen effects on host targets ('guardees'), posing evolutionary challenges for pathogens.
• Self-guarding, where a host target acts as both guard and guardee, presents a novel immune detection mechanism.

Purpose of the Study:

• To mathematically model and compare the dynamics of traditional guarding versus self-guarding immune architectures.
• To investigate the evolutionary advantages and disadvantages of self-guarding in host-pathogen interactions.
• To explore why self-guarding, despite its apparent effectiveness, has only recently been discovered.

Main Methods:

• Development and analysis of mathematical models simulating within-host pathogen and immune dynamics.
• Comparative analysis of guarding and self-guarding immune receptor systems under simulated pathogen pressure.
• Evaluation of immune response speed, pathogen suppression efficiency, and potential for false-positive activation.

Main Results:

• Self-guarding architectures trigger more rapid immune responses and achieve faster pathogen suppression compared to traditional guarding.
• Self-guarding systems exhibit a higher propensity for false-positive immune responses, potentially leading to autoimmunity.
• The increased risk of autoimmunity associated with self-guarding may impose significant costs on the host.

Conclusions:

• Self-guarding represents a potent innate immune strategy for rapid pathogen control but carries a substantial risk of autoimmune side effects.
• The potential for costly false-positive immune activation may limit the evolutionary conditions under which self-guarding can successfully emerge and persist.
• Further research is needed to fully understand the evolutionary trajectory and regulatory mechanisms of self-guarding in diverse host-pathogen systems.