Repurposed Fenoprofen Targeting SaeR Attenuates Staphylococcus aureus Virulence in Implant-Associated Infections.

Implant-associated infections (IAIs) caused by S. aureus can result in serious challenges after orthopedic surgery. Due to biofilm formation and antibiotic resistance, this refractory infection is highly prevalent, and finding drugs to attenuate bacterial virulence is becoming a rational alternative strategy. In S. aureus, the SaeRS two-component system (TCS) plays a key role in the production of over 20 virulence factors and the pathogenesis of the bacterium. Here, by conducting a structure-based virtual screening against SaeR, we identified that fenoprofen, a USA Food and Drug Administration (FDA)-approved nonsteroid anti-inflammatory drug (NSAID), had excellent inhibitory potency against the response regulator SaeR protein. We showed that fenoprofen attenuated the virulence of S. aureus without drug resistance. In addition, it was helpful in relieving osteolysis and restoring the walking ability of mice in vitro and in implant-associated infection models. More importantly, fenoprofen treatment suppressed biofilm formation and changed the biofilm structure, which caused S. aureus to form loose and porous biofilms that were more vulnerable to infiltration and elimination by leukocytes. Our results reveal that fenoprofen is a potent antivirulence agent with potential value in clinical applications and that SaeR is a drug target against S. aureus implant-associated infections.

A General Map of Transcriptional Expression of Virulence, Metabolism, and Biofilm Formation Adaptive Changes of Staphylococcus aureus When Exposed to Different Antimicrobials.

Biofilm formation of Staphylococcus aureus is the major cause of implant-associated infections (IAIs). Antimicrobial treatment is one of the most effective therapeutic options for S. aureus infections. However, it can also lead to adaptive transcriptomic changes due to extreme selective pressure, which may increase the risk of antimicrobial resistance. To study the transcriptional changes in S. aureus upon exposure to antimicrobial agents, we obtained expression profiles of S. aureus treated with six antimicrobials (flucloxacillin, vancomycin, ciprofloxacin, clindamycin, erythromycin, and linezolid, n = 6 for each group). We also included an untreated control group (n = 8) downloaded from the Gene Expression Omnibus (GEO) database (GSE70043, GSE56100) for integrated bioinformatic analyses. We identified 82 (44 up, 38 down) and 53 (17 up, 36 down) differentially expressed genes (DEGs) in logarithmic and stationary phases, respectively. When exposed to different antimicrobial agents, we found that manganese import system genes and immune response gene sbi (immunoglobulin G-binding protein Sbi) were upregulated in S. aureus at all stages. During the logarithmic phase, we observed adaptive transcriptomic changes in S. aureus mainly in the stability of protein synthesis, adhesion, and biofilm formation. In the stationary phase, we observed a downregulation in genes related to amino biosynthesis, ATP synthesis, and DNA replication. We verified these results by qPCR. Importantly, these results could help our understanding of the molecular mechanisms underlying the proliferation and antimicrobial resistance of S. aureus.

Synergistic Effects of Photobiomodulation Therapy with Combined Wavelength on Diabetic Wound Healing In Vitro and In Vivo.

Objective: The difficulty in chronic diabetic wound healing remains the focus of clinical research. Photobiomodulation therapy (PBMT) with different wavelengths could exert different effects on wound healing, but the effects of combined red and blue light (BL) remained unclear. Methods: Diabetic rat wound model and diabetic wounded endothelial cell model were established to observe possible effects of PBMT using combined wavelengths for wound healing. Cells and animals were separated into four groups exposed to red and/or BL. Cell viability, apoptosis, and migration, as well as the expression level of nitric oxide (NO), vascular endothelial growth factor, interleukin-6, and tumor necrosis factor-α were measured in vitro. Diabetic rats were evaluated for wound closure rates, collagen deposition, inflammation intensity, and density of neovascularization after light irradiation. Results: PBMT using combined wavelengths significantly sped up the healing process with increasing angiogenesis density, collagen deposition, and alleviating inflammation in vivo. Moreover, combined wavelength irradiation promoted cell proliferation and migration, and NO production, as well as reduced reactive oxygen species and inflammation in vitro. Conclusions: PBMT using combined wavelengths performed a synergistic effect for promoting diabetic wound healing and would be helpful to explore a more efficient pattern toward chronic wound healing.

Novel piston technique versus Ilizarov technique for the repair of bone defect after lower limb infection.

BACKGROUND: We aimed to compare the effectiveness and complications of a novel piston technique versus the Ilizarov technique for the repair of bone defects after lower limb infection. PATIENTS AND METHODS: We retrospectively reviewed 41 patients who had been treated at our department for lower extremity bone defects following osteomyelitis. There were 38 men and three women with a mean age of 43.41 (range, 12-69 years). The infected bone defects involved 36 tibias and five femurs. The piston technique (PT, group A) was used in 12 patients and the Ilizarov technique (IT, group B) in 29 patients. The mean follow-up period was 28.50 months (PT) and 29.90 months (IT). The modified Application of Methods of Illizarov (ASAMI) criteria was used to evaluate bone healing and functional recovery. RESULTS: Complete eradication of the infection and union of docking sites were accomplished in both groups. The mean external fixator index (EFI) was 42.32 days/cm in group A versus 58.85 days/cm in group B (p < 0.001). The bone outcomes were similar between groups A and B (p = 0.558) (excellent [9 vs. 19], good [3 vs.10]); group A showed better functional outcomes than group B (p < 0.05) (excellent [7 vs. 6], good [4 vs. 12], fair [0 vs. 10] and poor [1 vs. 1]). Pain was the most common complaint during follow-up, and group A had fewer cases of pin tract infection (1 vs. 6), adjacent joint stiffness (3 vs. 8), and delayed healing of the joint (0 vs. 3). CONCLUSIONS: Satisfactory bone healing can be achieved by using both PT and IT, although PT demonstrated better functional results, lower EFI, and allowed early removal of the external fixation. We found that this novel piston technique can improve the comfort of patients, reduce the incidence of complications, and provide rapid and convenient rehabilitation.

Thermonucleases Contribute to Staphylococcus aureus Biofilm Formation in Implant-Associated Infections-A Redundant and Complementary Story.

Biofilms formed by Staphylococcus aureus are one of the predominant causes of implant-associated infections (IAIs). Previous studies have found that S. aureus nucleases nuc1 and nuc2 modulate biofilm formation. In this study, we found low nuc1/nuc2 expression and high biofilm-forming ability among IAI isolates. Furthermore, in a mouse model of exogenous IAIs, Δnuc1/2 exhibited higher bacterial load on the surface of the implant than that exhibited by the other groups (WT, Δnuc1, and Δnuc2). Survival analysis of the hematogenous IAI mouse model indicated that nuc1 is a virulence factor related to mortality. We then detected the influence of nuc1 and nuc2 on biofilm formation and immune evasion in vitro. Observation of in vitro biofilm structures with scanning electron microscopy and evaluation of bacterial aggregation with flow cytometry revealed that both nuc1 and nuc2 are involved in biofilm structuring and bacterial aggregation. Unlike nuc1, which is reported to participate in immune evasion, nuc2 cannot degrade neutrophil extracellular traps. Moreover, we found that nuc1/nuc2 transcription is negatively correlated during S. aureus growth, and a possible complementary relationship has been proposed. In conclusion, nuc1/nuc2 are complementary genes involved in biofilm formation in exogenous IAIs. However, nuc2 contributes less to virulence and is not involved in immune evasion.

High-purity magnesium pin enhances bone consolidation in distraction osteogenesis via regulating Ptch protein activating Hedgehog-alternative Wnt signaling.

Magnesium alloys are promising biomaterials for orthopedic implants because of their degradability, osteogenic effects, and biocompatibility. Magnesium has been proven to promote distraction osteogenesis. However, its mechanism of promoting distraction osteogenesis is not thoroughly studied. In this work, a high-purity magnesium pin developed and applied in rat femur distraction osteogenesis. Mechanical test, radiological and histological analysis suggested that high-purity magnesium pin can promote distraction osteogenesis and shorten the consolidation time. Further RNA sequencing investigation found that alternative Wnt signaling was activated. In further bioinformatics analysis, it was found that the Hedgehog pathway is the upstream signaling pathway of the alternative Wnt pathway. We found that Ptch protein is a potential target of magnesium and verified by molecular dynamics that magnesium ions can bind to Ptch protein. In conclusion, HP Mg implants have the potential to enhance bone consolidation in the DO application, and this process might be via regulating Ptch protein activating Hedgehog-alternative Wnt signaling.