Immune priming in the insect gut: a dynamic response revealed by ultrastructural and transcriptomic changes

Area of Science:

• Invertebrate immunology
• Innate immune memory
• Evolutionary immunology

Background:

• Immune priming, an ancient process conferring pathogen protection, is observed across invertebrates.
• Mechanisms and evolution of immune priming remain poorly understood.
• Elicitation of immune priming by natural pathogens is unclear.

Purpose of the Study:

• Investigate dynamic processes during oral immune priming in Tribolium castaneum.
• Understand how pathogen-derived factors elicit immune priming.
• Elucidate mechanisms of innate immune memory in invertebrates.

Main Methods:

• Combined RNA sequencing and transmission electron microscopy.
• Utilized Tribolium castaneum and its natural pathogen Bacillus thuringiensis tenebrionis (Btt).
• Investigated gut responses to pathogen-derived virulence factors.

Main Results:

• Priming with pathogen factors induced gut damage and stress response in T. castaneum larvae.
• A distinct set of immune genes was upregulated during priming.
• Primed gut tissue showed enhanced upregulation of anti-virulence genes upon subsequent Btt exposure.

Conclusions:

• Pathogen-derived factors induce gut damage and stress, priming the tissue for improved defense.
• Findings deepen understanding of innate immune memory mechanisms.
• Immune memory likely evolved as an adaptive response to natural pathogens.