Sequential analysis of oxidative stress markers and vitamin C status in acute bacterial osteomyelitis

Impact of exogenous hydrogen peroxide on osteogenic differentiation of broiler chicken compact bones derived mesenchymal stem cells

The effects of hydrogen peroxide (H₂O₂) on the osteogenic differentiation of primary chicken mesenchymal stem cells (MSCs) were investigated. MSCs were subjected to an osteogenic program and exposed to various concentrations of H₂O₂ for 14 days. Results showed that high concentrations of H₂O₂ (200 and 400 nM) significantly increased pro-apoptotic marker CASP8 expression and impaired osteogenic differentiation, as indicated by decreased mRNA expression levels of osteogenesis-related genes and reduced in vitro mineralization. In contrast, long-term H₂O₂ exposure promoted basal expression of adipogenic markers at the expense of osteogenesis in MSCs during osteogenic differentiation, and increased intracellular reactive oxygen species (ROS) production, as well as altered antioxidant enzyme gene expression. These findings suggest that long-term H₂O₂-induced ROS production impairs osteogenic differentiation in chicken MSCs under an osteogenic program.

Osteomyelitis, Oxidative Stress and Related Biomarkers

Bone is a very dynamic tissue, subject to continuous renewal to maintain homeostasis through bone remodeling, a process promoted by two cell types: osteoblasts, of mesenchymal derivation, are responsible for the deposition of new material, and osteoclasts, which are hematopoietic cells, responsible for bone resorption. Osteomyelitis (OM) is an invasive infectious process, with several etiological agents, the most common being Staphylococcus aureus, affecting bone or bone marrow, and severely impairing bone homeostasis, resulting in osteolysis. One of the characteristic features of OM is a strong state of oxidative stress (OS) with severe consequences on the delicate balance between osteoblastogenesis and osteoclastogenesis. Here we describe this, analyzing the effects of OS in bone remodeling and discussing the need for new, easy-to-measure and widely available OS biomarkers that will provide valid support in the management of the disease.

The levels of oxidative DNA damage and some antioxidants in chronic osteomyelitis patients: A cross-sectional study

BACKGROUND

Osteomyelitis (OM) is a local or generalised infection of the bone and bone marrow which may be multifactorial in its causation. In this study, we aimed to determine oxidative DNA damage and antioxidant status of patients with chronic osteomyelitis.

MATERIAL METHOD

In this study, patients with chronic osteomyelitis and healthy controls were compared for descriptive characteristics (age and gender) and serum levels of malondialdehyde (MDA), 8-hydroxy-2-deoxy guanosine and antioxidant enzymes catalase, glutathione and superoxide dismutase.

RESULTS

This was a case-control study. About 5 mL of venous blood was collected for the estimation of biochemical parameters. This study comprised of 36 OM patients diagnosed, and 41 healthy ages (25-55 years) and sex-matched individuals. Antioxidant enzyme levels were significantly lower in patients with OM, whereas MDA and oxidative DNA damage levels were significantly higher.

CONCLUSION

The results obtained from this study have shown that the oxidant-antioxidant balance is impaired in patients with chronic osteomyelitis. It also supports that chronic osteomyelitis has associated with oxidative DNA damage.

Combination of kaempferol and azithromycin attenuates Staphylococcus aureus-induced osteomyelitis via anti-biofilm effects and by inhibiting the phosphorylation of ERK1/2 and SAPK

Osteomyelitis is bacterial infection of bone, commonly caused by Staphylococcus aureus. This work aims to study the potential of azithromycin and kaempferol against chronic osteomyelitis induced by azithromycin-resistant Staphylococcus aureus (ARSA). It was noticed that rats tolerated the treatments with no diarrhoea or weight loss; also, no deaths were observed in rats. The treatment by azithromycin alone failed to inhibit bacterial growth and also had no effect on the infection condition of bone, although the treatment decreased the levels of interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α), but did not improve the oxidative stress levels. Kaempferol monotherapy slightly inhibited bacterial growth and bone infection; the treatment also inhibited the levels of IL-6 and (TNF-α). The treatment also improved the antioxidant status. However, the combined treatment of azithromycin and kaempferol significantly suppressed bacterial growth and bone infection and modulated oxidative stress. In vitro, the combined treatment inhibited the levels of IL-6 and TNF-α, and also suppressed the phosphorylation of ERK1/2 and stress-activated protein kinase (SAPK). The combined treatment also showed anti-biofilm activity in ARSA. The combination attenuates ARSA-induced osteomyelitis in rats compared with their treatments alone by reducing oxidative stress, inhibiting the phosphorylation of ERK1/2 and SAPK and inhibiting biofilm formation.

KR-12-a5 Reverses Adverse Effects of Lipopolysaccharides on HBMSC Osteogenic Differentiation by Influencing BMP/Smad and P38 MAPK Signaling Pathways

KR-12-a5 is an analogue of the antimicrobial peptide KR-12. Both of these two agents can play key effects in the treatment of infections such as osteomyelitis. Our previous work demonstrated that the osteogenic differentiation of human bone marrow mesenchymal stem cells (HBMSCs) can be enhanced by KR-12. The present study investigated if KR-12-a5 could reverse the adverse effects of lipopolysaccharides (LPS) on HBMSC osteogenesis and the involved molecular mechanisms. We observed the proliferation, cell cycle, and apoptosis of HBMSCs in the presence of KR-12-a5 by a cell counting kit-8 assay and flow cytometry. The osteogenic differentiation of HBMSCs was studied by alkaline phosphatase, Alizarin Red staining, and quantitative assays. Osteogenic differentiation marker levels were detected using real-time quantitative PCR analysis, which demonstrated that KR-12-a5 treatment reversed the inhibition of osteogenesis. Western blot analysis indicated that LPS-activated P38 mitogen-activated protein kinase (MAPK) signaling was inhibited and BMP/Smad pathway was reactivated after KR-12-a5 treatment under induced osteogenic conditions. Furthermore, flow cytometry results demonstrated that KR-12-a5 relieved LPS-induced oxidative stress. Combining the LPS-treated mouse model results, we proved that KR-12-a5 reversed the adverse effects of LPS on HBMSC osteogenic differentiation by influencing the BMP/Smad and P38 MAPK signaling pathways.

Infected nonunion of tibia

Infected nonunions of tibia pose many challenges to the treating surgeon and the patient. Challenges include recalcitrant infection, complex deformities, sclerotic bone ends, large bone gaps, shortening, and joint stiffness. They are easy to diagnose and difficult to treat. The ASAMI classification helps decide treatment. The nonunion severity score proposed by Calori measures many parameters to give a prognosis. The infection severity score uses simple clinical signs to grade severity of infection. This determines number of surgeries and allows choice of hardware, either external or internal for definitive treatment. Co-morbid factors such as smoking, diabetes, nonsteroidal anti-inflammatory drug use, and hypovitaminosis D influence the choice and duration of treatment. Thorough debridement is the mainstay of treatment. Removal of all necrotic bone and soft tissue is needed. Care is exercised in shaping bone ends. Internal fixation can help achieve union if infection was mild. Severe infections need external fixation use in a second stage. Compression at nonunion site achieves union. It can be combined with a corticotomy lengthening at a distant site for equalization. Soft tissue deficit has to be covered by flaps, either local or microvascular. Bone gaps are best filled with the reliable technique of bone transport. Regenerate bone may be formed proximally, distally, or at both sites. Acute compression can fill bone gaps and may need a fibular resection. Gradual reduction of bone gap happens with bone transport, without need for fibulectomy. When bone ends dock, union may be achieved by vertical or horizontal compression. Biological stimulus from iliac crest bone grafts, bone marrow aspirate injections, and platelet concentrates hasten union. Bone graft substitutes add volume to graft and help fill defects. Addition of rh-BMP-7 may help in healing albeit at a much higher cost. Regeneration may need stimulation and augmentation. Induced membrane technique is an alternative to bone transport to fill gaps. It needs large amounts of bone graft from iliac crest or femoral canal. This is an expensive method physiologically and economically. Infection can resorb the graft and cause failure of treatment. It can be done in select cases after thorough eradication of infection. Patience and perseverance are needed for successful resolution of infection and achieving union.