A recent publication by the EGIS members Sebastian Weis and Michael Bauer reveals a new facet of the recently described long-term memory of innate immune cells, termed trained immunity and its role in sepsis. The authors can show that the course of sepsis is altered when the infected organism had previously been exposed to the host-derived molecule heme, an alarmin that is relased upon tissue damage. Heme application did not only affect macrophage function in vivo upon secondary stimulation. It also imposed persisting modifications in the chromatin structure and was associated with the appearance of a specific myeloid progenitor cell underlying a time-dependent protective or deleterious effect in sepsis. The study underlines the importance of sequential stress phenomena in infection biology.
The study was performed in close collaboration with the groups of Hendrik Stunnenberg and several other national and international partners.
Elisa Jentho, Cristian Ruiz-Moreno, Boris Novakovic, et al. (2021). Trained innate immunity, long-lasting epigenetic modulation, and skewed myelopoiesis by heme. PNAS October 19, 2021 118 (42) e2102698118