Chronic alcohol consumption enhances the differentiation capacity of hematopoietic stem and progenitor cells into osteoclast precursors.

Abstract

Chronic alcohol consumption (CAC) is associated with an enhanced risk of bone fracture, reduced bone density, and osteoporosis. Previous studies, using a rhesus macaque model of voluntary ethanol consumption, have shown that CAC induces functional, transcriptomic, and epigenomic changes in hematopoietic stem and progenitor cells (HSPCs) and their resultant monocytes/macrophages, skewing them toward a hyper-inflammatory response. Here, those studies were extended to investigate alterations in osteoclasts development, which, in postnatal life, differentiate from HSPCs and play a critical role in maintaining bone homeostasis. Analysis using spectral flow cytometry revealed a skewing of HSPCs towards granulocyte-monocyte progenitors (GMPs) within the CAC group, concordant with an increased number of colony-forming unit-granulocyte/macrophage (CFU-GM) colonies. Additionally, HSPCs from animals in the CAC group incubated with M-CSF (macrophage colony-stimulating factor) and RANKL (Receptor Activator of Nuclear factor-κB Ligand) were more likely to differentiate into osteoclasts, as evidenced by increased Tartrate-Resistant Acid Phosphatase (TRAP) staining and bone resorption activity. Moreover, single-cell RNA sequencing (scRNA-seq) of differentiated HSPCs identified osteoclast-related clusters in the CAC group with enhanced gene expression in pathways associated with cellular response to stimuli, membrane trafficking, and vesicle-mediated transport. Collectively, these data show that CAC enhances the capacity of HSPCs to differentiate into osteoclast precursors. These findings provide critical insights into the mechanisms by which alcohol consumption contributes to reduced bone density.