Trained Immunity: Long-Term Adaptation in Innate Immune Responses

Area of Science:

• Immunology
• Cellular Biology
• Infectious Disease

Background:

• Adaptive immunity features antigen specificity and long-term immunologic memory.
• Innate immune cells can also develop memory, a process known as trained immunity.
• Trained immunity involves a persistent hyperresponsive phenotype in innate immune cells following brief stimulation.

Purpose of the Study:

• To explore the concept of trained immunity in innate immune cells.
• To understand the mechanisms and implications of trained immunity.
• To investigate the potential of trained immunity in disease treatment and vaccination.

Main Methods:

• Review of recent scientific literature on trained immunity.
• Analysis of stimuli that induce trained immunity in monocytes and macrophages.
• Examination of epigenetic and metabolic mechanisms underlying trained immunity.

Main Results:

• Pathogenic stimuli and endogenous molecules can induce trained immunity.
• Trained immunity provides cross-protection against infections but can exacerbate chronic inflammation (e.g., atherosclerosis).
• Trained immunity is maintained by epigenetic and metabolic reprogramming, persisting for months due to myeloid progenitor cell changes.

Conclusions:

• Trained immunity involves epigenetic and metabolic reprogramming, affecting myeloid progenitor cells.
• This phenomenon can be beneficial for infectious disease protection but detrimental in chronic inflammatory conditions.
• Trained immunity offers a novel framework for developing new vaccines and therapeutic targets for inflammatory diseases.