Illustration from Sioud article on the cover of "Journal of Molecular Biology"
On the cover of the latest issue (15 December) of the well reputed "Journal of Molecular Biology" (impact factor 5,23, ranked no. 1 in the field) is a figure selected from an article by Mouldy Sioud et al. from the Department of Immunology at the Institute for Cancer Research, entitled " Signaling through Toll-like receptor 7/8 induces the differentiation of human bone marrow CD34+ progenitor cells along the myeloid lineage". The study demonstrate for the first time that TLR signalling can influence hematopoietic fate decisions in humans.
Notably, hematopoietic progenitor cells generate both the innate and adaptive immune cells such as macrophages, dendritic cells, T cells and B cells. Normally, the process of hematopoiesis takes place in specialized bone marrow microenvironments known as stem cell niches, where the interaction between hematopoietic stem cells and stroma cells plays a crucial role. Also, cell fate decisions are regulated by various signaling pathways, including cytokines and their receptors.
The figure shows differentiated progenitor cells stained with May-Grünwald Giemsa (click to enlarge).
In this study, Sioud and coworkers demonstrate that the activation of Toll-like receptor (TLR)-7and TLR-8 in human CD34+ progenitor cells with either immmunostimulatory siRNAs or synthetic ligands can induce their differentiation along the myeloid lineage without the addition of any exogenous factors such as cytokines. Thus, TLR signaling can influence hematopoietic fate decisions in humans, a novel finding that deserves some attention.
Sioud M, Floisand Y, Forfang L, Lund-Johansen F.
Signaling through Toll-like Receptor 7/8 Induces the Differentiation of Human Bone Marrow CD34+ Progenitor Cells along the Myeloid Lineage. (link to PubMed)
Journal of Molecular Biology Volume 364, Issue 5, 15 December 2006, Pages 945-954
The home page of Mouldy Sioud's group (radium.no/sioud)
Department of Immunology
Institute for Cancer Research