Inflammatory modulation of HSCs: viewing the HSC as a foundation for the immune response

Abstract
Haematopoietic progenitors proliferate during infections, even in the absence of peripheral cytopenia. Haematopoietic stem cells (HSCs) respond to both direct and indirect signals during infection. Direct signalling to HSCs during infection may occur via pattern recognition receptors, such as Toll-like receptors. Indirect signalling to HSCs during infection is mediated by pro-inflammatory cytokines, the most extensively characterized of which are the interferons. Baseline interferon signalling and tight regulation of this signalling are imperative to maintain HSC and peripheral cell populations. Cytokine-mediated activation of HSCs impairs their self-renewal capacity.