Innate Immune Memory in Macrophages

Abstract

Macrophages have been recognized as the primary mediators of innate immunity starting from embryonic/fetal development. Macrophagemediated defenses may not be as antigen-specific as adaptive immunity, but increasing information suggests that these responses do strengthen with repeated immunological triggers. The concept of innate memory in macrophages has been described as "trained immunity" or "innate immune memory (IIM). " As currently understood, this cellular memory is rooted in epigenetic and metabolic reprogramming. The recognition of IIM may be particularly important in the fetus and the young neonate who are yet to develop protective levels of adaptive immunity, and could even be of preventive/therapeutic importance in many disorders. There may also be a possibility of therapeutic enhancement with targeted vaccination. This article presents a review of the properties, mechanisms, and possible clinical significance of macrophage-mediated IIM.

Effects of N‐acetyl‐L‐cysteine polysulfides on periodontitis in a mouse model

“…TLR family members are crucial in identifying infiltrating microbiota and in reprogramming innate immunity 20,21 . LPS is the main component of the Gram‐negative bacteria cell wall, which could be recognized by TLR4 expressed on various cell types to activate inflammatory cytokine expression 22,23 . The signaling transduction of LPS‐TLR4 is mediated through the Myd88 pathway, and this transduction finally results in inflammatory cytokine expression 24,25 .…”

“… 20 , 21 LPS is the main component of the Gram‐negative bacteria cell wall, which could be recognized by TLR4 expressed on various cell types to activate inflammatory cytokine expression. 22 , 23 The signaling transduction of LPS‐TLR4 is mediated through the Myd88 pathway, and this transduction finally results in inflammatory cytokine expression. 24 , 25 Zhang and colleagues report that in LPS‐stimulated RAW264.7 cells, NAC‐S2 treatment significantly suppresses TNF‐α and IFN‐γ production.…”

Editorial

“…Evaluation of candidate vaccines is still in an early phase. 56 There are two extensive reviews focused on macrophages 57 and mitochondria, 58 respectively. In fetuses, neonates, and young infants, macrophages serve a very important role in immune defenses.…”

Prolonged Inhibition of the MEK1/2-ERK Signaling Axis Primes Interleukin-1 Beta Expression through Histone 3 Lysine 9 Demethylation in Murine Macrophages

“…To date, extensive studies have revealed various epigenetic modifications, such as histone modifications, DNA methylation, and non-coding RNA expression, that determine macrophage states [10,13]. Among them, histone modifications, particularly in H3K4 mono-or tri-methylation (H3K4me1/3) and H3K27 acetylation (H3K27ac), are transactivating markers that are involved in training/priming, whereas H3K9 di/tri-methylations (H3K9me2/3) are repressive markers of tolerated genes [14][15][16].…”