Prevention And Treatment Of Bone And Joint Infections Related Complications With Multifunctional Antibacterial Drugs

OBJECTIVE Infectious diseases of bones and joints may cause complications such as local osteogenesis,excessive osteoclastogenesis,and excessive activation of local inflammatory reactions,which are difficult to solve by traditional surgery and drug treatment.Studies have found that some antibacterial drugs also have the function of stimulating osteogenic differentiation,inhibiting inflammation and antiosteoclastogenesis,hoping to play roles in the prevention and treatment of complications of bone and joint infection.This study focused on several drugs with exact antibacterial effects,and explored their role in promoting osteogenic differentiation and its therapeutic effect on osteogenic inhibition in inflammatory environments.In addition,this study also used antibiotics with the function of antiosteoclastogenesis to construct new metal implants to prevent the occurrence of infection-related complications around the prosthesis.METHODS1.The effects of bacitracin on proliferation,cell cycle and apoptosis of HBMSCs were observed.The effect of bacitracin on osteogenic differentiation of HBMSCs was observed.The role of the BMP/Smad classical osteogenic pathway in the promotion of osteogenic differentiation by bacitracin was explored.2.The effects of antibacterial peptide KR-12 on proliferation,cell cycle and apoptosis of HBMSCs were observed.The effects of KR-12 on osteogenic differentiation of HBMSCs were investigated.Potential molecular mechanisms by which KR-12 played a role in osteogenic differentiation were identified.3.The effects of antibacterial peptide KR-12-a5 on proliferation,cell cycle and apoptosis of HBMSCs were observed.To observe the therapeutic effect of KR-12-a5,a model of osteogenic inhibition under inflammatory conditions induced by LPS was established.The molecular mechanism of the therapeutic effect was explored.LPSinduced osteolysis model of mice was established,and the therapeutic effects of KR-12-a5 were further evaluated in vivo.4.The surface of the titanium metal was anodized to form a nanotube structure.Enoxacin was loaded into the lumen.The extracellular matrix components,type I collagen(Col)and hyaluronic acid,were further assembled.The biocompatibility,osteogenesis and anti-osteoclastogenesis properties of the materials were investigated.An animal model of osteoporosis rats was constructed,and the osseointegration effect of the implant in vivo was further investigated.RESULTS1.Bacitracin did not cause cytotoxicity and apoptosis to HBMSCs at the concentration under 100 μM.Bacitracin promoted osteogenic differentiation of HBMSCs in a dosedependent manner under the concentration of 10 μM.The degree of osteogenic differentiation decreased at a concentration of 100 μM.Bacitracin can activate the phosphorylation level of Smad1/5 in HBMSCs.2.KR-12 did not cause cytotoxicity and apoptosis to HBMSCs in the concentration range of 0-1000 μg/ml,and promoted osteogenic differentiation of HBMSCs in a dosedependent manner.The BMP/Smad signaling pathway could be activated by KR-12,and the degree of activation was positively correlated with its concentration.3.KR-12-a5 did not cause cytotoxicity and apoptosis at the concentration of 0-50 μg/ml.KR-12-a5 reversed the osteogenic differentiation potential of HBMSCs in vitro and LPS-induced inflammatory bone erosion in vivo.These effects were accomplished by suppressing the p38 MAPK and reactivating the BMP/Smad signaling pathways.4.The titanium nanotubes with a diameter of 80 nm could be successfully prepared;enoxacin can be successfully loaded into the nanotubes;the Col/Hy A multi-layer could be fixed on the surface of the nanotube,and could delay the release of drug.The surface modified material could promote the spreading,adhesion and proliferation of RBMSCs.The osteogenic differentiation potential of RBMSCs in vitro could be enhanced by modified materials.The extract of modified material could inhibit the formation of osteoclasts.The surface modified implant exhibited optimal osseointegration effects in ovariectomized rats.CONCLUSIONS1.Bacitracin promotes osteogenic differentiation of HBMSCs within a safe dose range,which may be mediated through the BMP/Smad signaling pathway.2.KR-12 can effectively promote osteogenic differentiation of HBMSCs in its safe and effective antimicrobial concentration range,and BMP/Smad signaling pathway may play an important role in this process.3.KR-12-a5 has significant therapeutic effects on LPS-induced osteogenic inhibition in its safe and effective antimicrobial concentration range.The p38 MAPK and BMP/Smad signaling pathway may be the potential molecular mechanisms.4.Titanium nanotubes loaded with enoxacin and fixed Col/Hy A multi-molecular layer can significantly improve the biocompatibility of the implants,and promote osteogenic differentiation and inhibit osteoclastogenesis.