Trained immunity: implications for vaccination. (August 2022) - Geckin, Büsranur
Abstract : The concept that only adaptive immunity can build immunological memory has been challenged in the past decade. Live attenuated vaccines such as the Bacillus Calmette–Guérin, measles-containing vaccines, and the oral polio vaccine have been shown to reduce overall mortality beyond their effects attributable to the targeted diseases. After an encounter with a primary stimulus, epigenetic and metabolic reprogramming of bone marrow progenitor cells and functional changes of tissue immune cell populations result in augmented immune responses against a secondary challenge. This process has been termed trained immunity. This review describes the mechanisms leading to trained immunity and summarizes the most important developments from the past few years. Highlights: Trained immunity is induced in a variety of innate immune cell types. Central and peripheral trained immunity underlies the long-term effects of innate immunity. Metabolic and epigenetic reprogramming underpins the generation of trained immunity. Trained immunity can explain epidemiological evidence on live vaccines' beneficial heterologous effects.