Long-term reprogramming of the innate immune system.

Area of Science:

• Immunology
• Cellular Biology
• Epigenetics

Background:

• Immunological memory was traditionally linked solely to lymphocytes.
• Emerging evidence indicates innate immune cells also exhibit long-term functional alterations after inflammatory stimuli.
• This phenomenon, known as trained immunity, involves reprogramming of innate immune cells.

Purpose of the Study:

• To review the concept of innate immune memory (trained immunity).
• To explore the mechanisms underlying long-term functional reprogramming of innate immune cells.
• To discuss the clinical relevance of trained immunity in various diseases.

Main Methods:

• Review of existing scientific literature on innate immunity and trained immunity.
• Analysis of studies investigating functional and epigenetic changes in innate immune cells.
• Synthesis of evidence linking innate immune memory to clinical conditions.

Main Results:

• Innate immune cells (monocytes, macrophages, dendritic cells, NK cells) undergo functional reprogramming after inflammatory insults.
• This reprogramming involves metabolic rewiring and epigenetic modifications.
• Trained immunity leads to altered responses to subsequent challenges, distinct from adaptive immunity.

Conclusions:

• Innate immune cells possess a form of memory, termed trained immunity.
• Metabolic and epigenetic changes are crucial for inducing and maintaining innate immune memory.
• Trained immunity plays a significant role in vaccination, atherosclerosis, sepsis, and cancer.