Navigating the marrow sea towards erythromyeloblastic islands under normal and inflammatory conditions

Abstract

Purpose of reviewTerminal erythroid differentiation occurs in specialized niches called erythroblastic islands. Since their discovery in 1958, these niches have been described as a central macrophage surrounded by differentiating erythroblasts. Here, we review the recent advances made in the characterization of these islands and the role they could play in anaemia of inflammation.Recent findingsThe utilization of multispectral imaging flow cytometry (flow cytometry with microscopy) has enabled for a more precise characterization of the niche that revealed the presence of maturing granulocytes in close contact with the central macrophage. These erythromyeloblastic islands (EMBIs) can adapt depending on the peripheral needs. Indeed, during inflammation wherein inflammatory cytokines limit erythropoiesis and promote granulopoiesis, EMBIs present altered structures with increased maturing granulocytes and decreased erythroid precursors.SummaryRegulation of the structure and function of the EMBI in the bone marrow emerges as a potential player in the pathophysiology of acute and chronic inflammation and its associated anaemia.

Crosstalk between terminal erythropoiesis and granulopoiesis within their common niche: the erythromyeloblastic island

“…Red cell disorders affect more than a billion people worldwide and are a significant cause of morbidity and mortality. Most of these diseases including thalassemias, congenital dyserythropoietic anemias, MDS, polycythemia vera, as well as the widespread AoI arise or have significant contributing pathology in the final stages of erythropoiesis [14,15,16,17,18 ▪▪ ,28,46,47], when erythroblasts mature around the central Mϕ within EBIs and EMBIs [2,12 ▪▪ ]. AoI occurs in patients with chronic or acute immune activation, due to infectious, malignant, or autoimmune diseases, and affects the quality of life of millions of people worldwide [46].…”