Knockout of the Staphylococcus aureus virulence gene sdrC promotes Myh7 expression to inhibit the progression of osteomyelitis

Abstract

The incidence of osteomyelitis has been increasing annually, but the specific molecular pathogenesis of Staphylococcus aureus-induced osteomyelitis is unclear. The SdrC protein facilitates Staphylococcus aureus adhesion and colonization, thereby promoting subsequent biofilm accumulation and contributing to the progression of osteomyelitis. The role of SdrC, an important protein in S. aureus, in the progression of S. aureus-induced osteomyelitis requires further elucidation. Thus, we aimed to determine whether targeting SdrC is a novel strategy for treating S. aureus-induced osteomyelitis. The sdrC sequence of S. aureus was knocked out, and rat models with wild-type and sdrC knockout (KO) S. aureus-induced osteomyelitis were established. Enzyme-linked immunosorbent assays (ELISAs) were used to identify differences in the levels of the inflammatory factors IL-6 and TNF-α, and qPCR and Western blotting were used to identify changes in the levels of osteogenic indicators, such as ALP, OST and Runx2; these experiments analyzed the role of SdrC in the progression of S. aureus-induced osteomyelitis. Transcriptomic sequencing was used to explore the mechanism by which SdrC promotes the development of S. aureus-induced osteomyelitis at the molecular level. After the SdrC protein of S. aureus was knocked out, biofilm formation significantly decreased. Compared with the control group, The sdrC-KO osteomyelitis group showed milder bone tissue inflammation compared to the control group, and the expression of the inflammatory factors IL-6 and TNF-α decreased significantly (p < 0.05), whereas the expression of the osteogenic indicators ALP, OST, and Runx2 increased significantly, as shown by qPCR and Western blotting (p < 0.05). Alkaline phosphatase and alizarin red staining showed that knocking out SdrC increased ossification in rats and improved their prognosis. Transcriptomic sequencing revealed that Myh7 was significantly overexpressed in the sdrC-KO rats with osteomyelitis (p < 0.05). Knocking out Myh7 significantly reduced the mRNA and protein levels of osteogenic markers Runx2, ALP, Osterix (OSX), and osteocalcin (p < 0.05), suggesting that Myh7 inhibits the function of the S. aureus SdrC protein. The SdrC protein in S. aureus promotes the malignant progression of osteomyelitis and exacerbates the development of osteomyelitis by promoting S. aureus biofilms. Moreover, Myh7 hinders the ability of SdrC to promote biofilm formation, reducing the progression of osteomyelitis; these findings suggest that targeting SdrC or enhancing Myh7 expression could serve as a novel therapeutic strategyjbr osteomyelitis treatment.

Keywords: Staphylococcus aureus; Myh7; Osteomyelitis; SdrC protein.