Innate Immune Memory and the Host Response to Infection

Area of Science:

• Immunology
• Cell Biology
• Epigenetics

Background:

• The adaptive immune system possesses memory, while the innate immune system was classically considered memory-less.
• Recent findings reveal innate immune cells can retain memory of prior infections, enhancing future responses.

Purpose of the Study:

• To explore the phenomenon of innate immune memory, also known as trained immunity.
• To understand the mechanisms underlying the induction and maintenance of innate immune memory.
• To investigate the dual role of innate immune memory in host defense and chronic disease pathogenesis.

Main Methods:

• Investigated the role of pattern recognition receptors and cytokines in inducing innate immune memory.
• Examined epigenetic modifications and metabolic reprogramming in hematopoietic stem cells and innate leukocytes.
• Assessed the impact of trained immunity on antimicrobial functions like leukocyte expansion, chemotaxis, and microbial killing.

Main Results:

• Innate myeloid and lymphoid cells demonstrate memory of prior pathogen exposure.
• Epigenetic reprogramming and metabolic changes sustain the trained innate immunity phenotype.
• Enhanced antimicrobial functions, including leukocyte expansion and improved microbial killing, were observed.

Conclusions:

• Innate immune memory is a functional property of the innate immune system, mediated by epigenetic and metabolic reprogramming.
• Trained immunity primes the host for augmented responses to subsequent infections.
• Innate immune memory may also play a role in the development of chronic inflammatory diseases such as atherosclerosis and Alzheimer's disease.