New "programmers" in tissue macrophage activation.

Tissue macrophages and monocyte-derived macrophages are under continuous influence from environmental signals that define their activation status. Along these lines, macrophages integrate tissue and stress signals and are specifically programmed by these signals towards a spectrum of functions necessary to fulfill their duty within their particular microenvironment, be it homeostatic tissue function, response to inflammatory pathophysiology, or even resolution of an inflammation. Recent years have seen tremendous progress in our understanding how macrophages at different sites are transcriptionally and epigenetically programmed to execute their diverse tasks throughout the body. The identification of transcription factors guiding these reprogramming activities is currently a major topic in macrophage research. We summarize the most recent findings within the last 18 months concerning the identification of novel transcription factors associated with particular macrophage location or function. Furthermore, we extend the view of cellular programming of macrophages to additional levels of regulation, for example, by long non-coding RNAs. Clearly, in addition to transcription factors, there are many more "programmers" shaping the versatile functionality of these exciting innate immune cells.