The pivotal role of the oncostatin M (OSM) protein in hematopoiesis in humans is underscored by a recent study published in the Journal of Clinical Investigation. Researchers investigated three affected individuals from a consanguineous family with a bone marrow failure syndrome characterized by severe anemia, thrombocytopenia and neutropenia, identifying a causative homozygous variant in OSM that leads to a deficiency of the protein.

OSM is a cytokine within the interleukin-6 protein family, produced by activated leukocytes. It binds to LIFR and OSMR receptors and, together with IL31RA, also forms the interleukin-31 receptor complex, thereby acting in an intricate network and various biological processes including hematopoiesis, inflammation, neurogenesis and growth of cancer cell lines. However, the precise in vivo implications of OSM deficiency in humans have yet to be elucidated. Heterozygous loss-of-function mutations in OSMR, the gene encoding the OSMR-beta receptor, lead to an autosomal dominant chronic skin condition known as familial primary localized cutaneous amyloidosis.

In their experiments, the researchers observed that OSM-deficient hematopoietic stem and progenitor cells differentiated into erythroblasts and megakaryocytes in vitro. They speculated that in humans, the loss of OSM function modifies the bone marrow microenvironment in a way that compromises the production of erythrocytes, thrombocytes, and neutrophils.