Exploring Pathogenic Genes in Frozen Shoulder through weighted gene co-expression network analysis and Mendelian Randomization

Abstract Background Frozen shoulder (FS) is characterized by the thickening and fibrosis of the joint capsule. The precise etiology responsible for these pathological changes remains elusive. Consequently, the primary aim of this study was to explore the potential involvement of pathogenic genes in FS. Methods Differential expression analysis and WGCNA were employed to investigate the co-expressed genes. GO and KEGG were conducted to elucidate the potential roles of these co-expressed genes. Subsequently, Mendelian randomization (MR) analysis was performed using expression quantitative trait loci datasets for these co-expressed genes, combined with the genome-wide association study of FS. The identified hub genes were further validated through reverse transcription-quantitative PCR (RT-qPCR). In addition, a nomogram model and receiver operating characteristic (ROC) curves were established to assess the diagnostic value of the hub genes. Furthermore, the infiltration of immune cells was evaluated using the CIBERSORT algorithm and the relationship between hub genes and immune infiltrating cells was subsequently analyzed. Result The gene co-expression network was constructed using WGCNA and the top two most correlated modules were identified. These modules were then intersected with differentially expressed genes, yielding a set of 295 overlapping co-expressed genes. Utilizing MR analysis, four hub genes, namely ADAMTS1, NR4A2, PARD6G, and SMKR1 were found to exhibit positive causal relationships with FS, which were subsequently validated through RT-qPCR analysis. Moreover, the diagnostic value of the four hub genes was demonstrated through the development of a nomogram model and the construction of ROC curves. Notably, a causal relationship between ADAMTS1 and immune cell infiltration in frozen shoulder was observed. Conclusion Our study suggested a potential association between the upregulated expression of ADAMTS1, NR4A2, PARD6G, and SMKR1 and an increased susceptibility to FS. Further investigations elucidating the functional roles of these genes will enhance our understanding of the pathogenesis of FS.