Identification of ferroptosis hub gene cDKN1A relating to immune microenvironment in rheumatoid arthritis via bioinformatic analysis and experimental verification

INTRODUCTION: Rheumatoid arthritis (RA) is a chronic immune-mediated inflammatory disease in which ferroptosis appears to be implicated. This study aimed to identify ferroptosis-related therapeutic targets for RA via a series of bioinformatic analyses and experimental verification. MATERIALS AND METHODS: In the present study, the GSE12021 and GSE55235 datasets were enrolled for subsequent analysis. Ferroptosis-related differentially expressed genes (FRDEGs) in RA were first identified, followed by random forest (RF), support vector machine (SVM), and Weighted Gene Co-Expression Network Analysis (WGCNA). Immune infiltration was analyzed, the hub genes expression was verified via in vitro experiments. Subsequently, the roles of hub genes in ferroptosis and macrophage polarization were determined through cell function experiments. RESULTS: A total of 24 FRDEGs were screened in RA, and the hub gene CDKN1A was identified. CDKN1A was associated with a variety of immune cells, such as Macrophage. In the synovial tissues and cells of RA patients, CDKN1A was downregulated, concomitant with ferroptosis activation. In normal synovial fibroblasts, knockdown of CDKN1A activated ferroptosis and induced macrophage M1 polarization, which was alleviated by ferroptosis inhibitor Fer-1. Conversely, in MH7A cells (a rheumatoid arthritis synovial fibroblast cell line), overexpression of CDKN1A significantly attenuated ferroptosis, accompanied by decreased M1 polarization. CONCLUSION: The ferroptosis-induced by CDKN1A low expression in synovial cells mediates the activation of macrophages. CDKN1A represents a novel potential molecular marker for RA immunotherapy. Key Points • Ferroptosis is a key phenotype of rheumatoid synovial cells. • CDKN1A-mediated ferroptosis is closely related to the synovial immune microenvironment in rheumatoid arthritis.