Staphylococcal protein A, Panton-Valentine leukocidin and coagulase aggravate the bone loss and bone destruction in osteomyelitis.
OBJECTIVE
Osteomyelitis is a debilitating infectious disease of the bone which is predominantly caused by Staphylococcus aureus (S. aureus). The purpose of this study was to investigate the role of the S. aureus virulence factors, i.e. protein A (SpA), Panton-Valentine leukocidin (PVL) and coagulase (Coa) on osteomyelitis.


METHODS
The effect of SpA, PVL and Coa on osteoblasts was studied through the following aspects including osteoblast proliferation, apoptosis, bone formation, bone mineralization and RANK-L expression. S. aureus overexpressing PVL, SpA or Coa was constructed and used to study the role of PVL, SpA and Coa, respectively. S. aureus silencing PVL, SpA or Coa was also constructed and used for reversing verification. Osteoblast proliferation was detected by MTT tetrazolium dye reduction assay. Apoptosis was determined by Annexin V-FITC staining. The levels of pro-caspase 3, cleaved-caspase 3, pro-caspase 9 and cleaved-caspase 9 were detected by western blot. Bone formation markers including collagen I, osteopontin and osteocalcin were detected by real time RT-PCR. Alkaline phosphatase activity was measured by adding p-nitrophenyl phosphate as a phosphatase substrate. Von kossa stain and alizarin red stain were applied for determining phosphate and calcium deposition, respectively. The RANK-L expression was tested by ELISA.


RESULTS
PVL, SpA and Coa inhibited osteoblast proliferation, induced osteoblast apotosis, prohibited bone formation and mineralization and upregulated RANK-L expression.


CONCLUSIONS
PVL, SpA and Coa play a critical role on bone loss and bone destruction of osteomyelitis.
The Third Military Medical University, Chongqing, 400038, PR China.
Tao
T
Jin
Yue Liang
YL
Zhu
Jun
J
Li
Jian
J
Shi
Xiao Qing
XQ
He
Jing
J
Ding
Yong Qing
YQ
Xu
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001427:Bacterial Toxins / Q000633:toxicity*; D001862:Bone Resorption / Q000503:physiopathology; D002113:Calcification, Physiologic / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003030:Coagulase / Q000633:toxicity*; D005098:Exotoxins / Q000633:toxicity*; D005786:Gene Expression Regulation / Q000187:drug effects; D007956:Leukocidins / Q000633:toxicity*; D051379:Mice; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects*; D010019:Osteomyelitis / Q000503:physiopathology*; D013205:Staphylococcal Protein A / Q000633:toxicity*
D001427:Bacterial Toxins; D003030:Coagulase; D005098:Exotoxins; D007956:Leukocidins; C078284:Panton-Valentine leukocidin; D013205:Staphylococcal Protein A