Ddb1-Cullin4-Associated-Factor 1 in Macrophages Restricts the Staphylococcus aureus -Induced Osteomyelitis.

Introduction: Ddb1-cullin4-associated-factor 1 (DCAF1) is known to regulate protein ubiquitination, while the roles of DCAF1 in osteomyelitis remain unknown. This study aims to investigate the effects of DCAF1 deficiency in macrophages on osteomyelitis and elucidate the molecular mechanism.

Methods: Staphylococcus aureus -induced mouse model of osteomyelitis was established on the DCAF1fl/fl Lyz2cre/+ and DCAF1fl/fl Lyz2+/+ (control) mice. Flow cytometry was conducted to analyze the populations of adaptive and innate immune cells. Lipopolysaccharides (LPS)-induced bone marrow-derived macrophages (BMDMs) were established. qRT-PCR and immunoblot analysis were used to determine the levels of inflammation-related biomarkers. ELISA was used to determine the release of inflammatory cytokines including IL-1β, IL-6, and TNF.

Results: The populations of immune cells in the bone marrow and spleen were not affected due to DCAF1 deficiency in macrophages. DCAF1 suppressed inflammatory cytokines in LPS-induced BMDMs. Additionally, DCAF1 deficiency in macrophages induced severe symptoms including less bacterial load in the femur, cortical bone loss, and reactive bone formation. Mechanistic study revealed that DCAF1 deficiency induced p38 hyperactivation.

Discussion: DCAF1 in macrophages suppressed the Staphylococcus aureus -induced mouse model of osteomyelitis.