Transcriptomic characterization of classical monocytes highlights the involvement of immuno-inflammation in bone erosion in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease associated with localized bone involvement characterized by the presence of bone erosions. Evidence-based data suggest that under inflammatory conditions, classical monocytes are the main source of osteoclasts and might be involved in bone erosion pathophysiology. Here, we analyze the transcriptomic profile of classical monocytes in erosive and non-erosive rheumatoid arthritis patients in order to better understand their contribution to bone erosion. Thirty-nine premenopausal RA patients and 20 healthy age-matched women were recruited for this study. Classical monocytes were isolated from peripheral blood through negative selection. Sequencing library was constructed using the Quant-seq® 30 mRNA-Seq Library Prep Kit (Lexogen®) and sequenced using an Illumina Seq 2500 platform (Illumina®). Differential expression analysis was performed between patients and control groups. Therefore, gene sets analysis was performed to identify the enriched biological pathways. Results suggested that alterations in pathways related to the inflammatory process and impairment of bone formation have an important role in the pathophysiology of bone erosions in patients with rheumatoid arthritis.