Transcription factor FOS promotes ferroptosis and inflammation in S. aureus- infected osteomyelitis via EIF5A

Osteomyelitis (OM) is a bone disease that can leave people disabled. Eukaryotic translation initiation factor (EIF5A) is involved in cell proliferation, apoptosis, differentiation, and inflammation, but the role of EIF5A in staphylococcus aureus (S. aureus)-infected OM remains unclear.

The mRNA and proteins were detected by qRT-PCR and western blot. Cell viability was examined by CCK8 assay. The reactive oxygen species (ROS), malondialdehyde (MDA), ferrous iron (Fe²⁺), and glutathione (GSH) levels were analyzed using the ROS, MDA, GSH, and Fe²⁺ detection kits. The levels of tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and Interleukin-6 (IL-6) were examined using Enzyme-linked immunosorbent (ELISA) kits. The binding between FOS and promoter of EIF5A was detected by chromatin immunoprecipitation (CHIP) assay. The interaction between EIF5A and Fos proto-oncogene (FOS) was detected by dual-luciferase reporter assay. The diagnostic values of EIF5A and FOS were analyzed with blood of S. aureus-infected OM patients and healthy volunteers by ROC curve.

The EIF5A was up-regulated in S. aureus-infected OM. EIF5A knockdown promoted cell viability in S. aureus-infected MG-63 cells and reduced ROS, MDA, and Fe²⁺ levels, and increased GSH levels. Meanwhile, silencing EIF5A could increase expression of glutathione peroxidase 4 (GPX4), and ferritin heavy chain1 (FTH1) and reduce acyl-CoA synthetase long-chain family member 4 (ACSL4) expression, and silencing EIF5A could reduce immune factors (TNF-α, IL-1β, and IL-6) levels. FOS could bind to EIF5A. Silencing FOS promoted cell viability, and increased GSH levels in S. aureus-infected MG-63 cells, but reduced ROS, MDA, and Fe²⁺ levels. Meanwhile, promoted GPX4 and FTH1 expression, inhibited ACSL4 expression, and reduced immune factor levels in S. aureus-infected MG-63 cells. Interestingly, EIF5A overexpression could weaken the actions. FOS promotes ferroptosis and inflammation via EIF5A in S. aureus-infected MG-63 cells. Besides, the EIF5A and FOS might be potential molecular diagnostic markers in the progression of OM.

FOS promotes ferroptosis and inflammation via EIF5A in S. aureus-infected OM. This study is first to report the role of FOS and EIF5A in S. aureus-infected OM, but we found that there are still some limitations in our work, such as not covering all possible types of infection, which is the focus of future research.