Molecular mechanism of osteoclast differentiation of PBMC in patients with rheumatoid arthritis.

Objective: Rheumatoid arthritis (RA) is an autoimmune condition that causes severe joint deformities and impaired functionality, affecting the well-being and daily life of individuals. Consequently, there is a pressing demand for identifying viable therapeutic targets for treating RA. This study aimed to explore the molecular mechanisms of osteoclast differentiation in PBMC from patients with RA through transcriptome sequencing and bioinformatics analysis.

Methods: Blood samples were collected from 20 patients with RA, including 15 females and 5 males. Peripheral blood mononuclear cells (PBMCs) were isolated by density gradient centrifugation. Osteoclast differentiation was induced using a medium containing RANKL and M-CSF for 14 days, with medium changes every 2 days. After 14 days, osteoclasts were identified by TRAP staining, and multinucleated TRAP-positive cells were counted as osteoclasts. Subsequently, transcriptome sequencing was performed using the Illumina Novaseq 6000 platform, and differential expression analysis was conducted using the DESeq2 package in R. Differentially expressed genes were selected with a significance threshold of p < 0.05 and a fold change ≥ 2 (|Log2FC|≥ 1). Bioinformatics analysis was performed using R, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses.

Results: TRAP staining showed successful induction of PBMCs into osteoclasts. Transcriptome sequencing revealed a significant number of differentially expressed genes (DEGs) in the induced groups compared with the control group. GO analysis showed that these DEGs were predominantly associated with biological processes related to the transmission of chemokine signals, reactions to living organisms, and bolstering neutrophil-driven defense mechanisms. KEGG analysis showed that these DEGs were enriched by primary signaling pathways, including interactions between cytokines and their receptors, chemokine signaling pathway, cell cycle regulation, neutrophil extracellular trap formation, and TNF signaling pathway.

Conclusions: Osteoclast differentiation of PBMC from patients with RA involves various gene alterations, multiple biological processes, and signaling pathways, providing insight into the potential mechanism of PBMC osteoclast differentiation in RA. Key Points • A total of 1841 DEGs were obtained between the induced group and the normal group. • These DEGs were involved in multiple biological processes and signaling pathways.