Identification of Ferroptosis-Related Biomarkers for Diagnosis and Molecular Classification of Staphylococcus aureus-Induced Osteomyelitis

Abstract

Objective

Staphylococcus aureus (SA)-induced osteomyelitis (OM) is one of the most common refractory diseases in orthopedics. Early diagnosis is beneficial to improve the prognosis of patients. Ferroptosis plays a key role in inflammation and immune response, while the mechanism of ferroptosis-related genes (FRGs) in SA-induced OM is still unclear. The purpose of this study was to determine the role of ferroptosis-related genes in the diagnosis, molecular classification and immune infiltration of SA-induced OM by bioinformatics.

Methods

Datasets related to SA-induced OM and ferroptosis were collected from the Gene Expression Omnibus (GEO) and ferroptosis databases, respectively. The least absolute shrinkage and selection operator (LASSO) and support vector machine-recursive feature elimination (SVM-RFE) algorithms were combined to screen out differentially expressed-FRGs (DE-FRGs) with diagnostic characteristics, and gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA) were used to explore specific biological functions and pathways. Based on these key DE-FRGs, a diagnostic model was established, and molecular subtypes were divided to explore the changes in the immune microenvironment between molecular subtypes.

Results

A total of 41 DE-FRGs were identified. After screening and intersecting with LASSO and SVM-RFE algorithms, 8 key DE-FRGs with diagnostic characteristics were obtained, which may regulate the pathogenesis of OM through the immune response and amino acid metabolism. The ROC curve indicated that the 8 DE-FRGs had excellent diagnostic ability for SA-induced OM (AUC=0.993). Two different molecular subtypes (subtype 1 and subtype 2) were identified by unsupervised cluster analysis. The CIBERSORT analysis revealed that the subtype 1 OM had higher immune cell infiltration rates, mainly in T cells CD4 memory resting, macrophages M0, macrophages M2, dendritic cells resting, and dendritic cells activated.

Conclusion

We developed a diagnostic model related to ferroptosis and molecular subtypes significantly related to immune infiltration, which may provide a novel insight for exploring the pathogenesis and immunotherapy of SA-induced OM.

Keywords:

• osteomyelitis
• ferroptosis
• molecular subtype
• immune infiltration
• biomarker

Abbreviations

OM, Osteomyelitis; SA, Staphylococcus aureus; GEO, Gene Expression Omnibus; LASSO, Least absolute shrinkage and selection operator; SVM-RFE, Support vector machine-recursive feature elimination; GSEA, Gene set enrichment analysis; GSVA, Gene set variation analysis; DEGs, Differentially expressed genes; GO, Gene Ontology; KEGG, Kyoto Encyclopedia of Genes and Genomes; BP, Biological processes; CC, Cellular components; MF, Molecular functions; ROC, Receiver operating characteristic; AUC, Area under the curve; DCA, Decision curve analysis; CIBERSORT, Cell Type Identification by Estimating Relative Subsets of RNA Transcripts; CDF, Cumulative distribution function; PCA, Principal component analysis; RT-qPCR, Reverse transcription quantitative PCR.

Data Sharing Statement

All the results are presented in the article and Supplementary Material. Further inquiries can be directed to the corresponding authors.

Ethics Statement

All experimental procedures were approved by the 920th Hospital of Joint Logistics Support Force Committee on Ethics for the care and use of laboratory animals (2022-075-01) and conducted in accordance with the Guide for the Care and Use of Laboratory Animals (National Institutes of Health, USA).

Acknowledgments

We are grateful to the authors who gave the GEO public dataset.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

All the authors declare that they have no competing interests in this work.

Additional information

Funding

This study was funded by National Natural Science Foundation of China (Grant No.81772367, 82072392); the Yunnan Traumatology and Orthopedics Clinical Medical Center (Grant No. ZX20191001); the Grants from Yunnan Orthopedics and Sports Rehabilitation Clinical Medicine Research Center (Grant No. 202102AA310068).