Citations

ABSTRACT Periprosthetic joint infection (PJI) is a devastating complication of total joint arthroplasty that can be challenging to diagnose and treat. Neutrophils are a prominent feature in PJI, with neutrophil extracellular traps (NETs) known to be present; little is known, however, about the physiology of PJI-associated NETs. Here, the proteomes of PJI and non-infectious arthroplasty failure (NIAF), analyzed using liquid chromatography tandem mass-spectrometry (LC-MS/MS) and proximity extension assay (PEA)-based profiling of fluids derived from sonication of arthroplasty components removed from patients who had undergone revision arthroplasty, were compared, with a focus on NET formation. In addition, in vitro effects of synovial fluid components on Staphylococcus aureus- induced NET formation were characterized. LC-MS/MS (PJI n = 85, NIAF n = 26) and PEA (PJI n = 95, NIAF n = 39) showed NET formation and neutrophil degranulation to be associated with PJI, with the complement cascade and platelet activation pathways identified as potential contributors. In vitro studies showed delayed NET formation in artificial synovial fluid compared to standard cell culture media conventionally used to evaluate NETs. Together, these results demonstrate the presence of NETs in PJI, identify potential pathways involved in PJI-associated NETosis, and point to an influence of synovial components on NET formation during PJI. IMPORTANCE Periprosthetic joint infection (PJI) is a major complication of joint replacement, placing a significant burden on patients and the healthcare system. Our research reveals that neutrophils and their antimicrobial “traps” are dominant features of the immune response at the infection joint site. Importantly, we found that the unique environment of the joint delays the formation of these traps, potentially contributing to the pathogenesis of PJI. By establishing a new experimental platform tailored for the infected joint, this work provides a foundational platform for probing these mechanisms and supports the development of improved diagnostic and therapeutic strategies.

Introduction Infection following extensor mechanism reconstruction with Marlex mesh is a devastating and limb threatening complication. The purpose of this study was to evaluate whether vancomycin-loaded mesh reduced staphylococcal infection in a murine extensor mechanism reconstruction model with Marlex mesh. Methods Mouse-sized, eight-layer Marlex mesh constructs were fabricated to simulate clinical reconstruction and soaked in a vancomycin solution (50 mg/mL) for in vitro and in vivo testing. Three methicillin-resistant clinical isolates from human periprosthetic knee infections were evaluated: Staphylococcus aureus, Staphylococcus epidermidis , and Staphylococcus lugdunensis. In vitro testing assessed vancomycin loading, mechanical properties, antibacterial activity, and early biofilm inhibition. For in vivo experiments, plain or vancomycin-loaded Marlex meshes were implanted into the murine extensor mechanism and inoculated intraoperatively (5 per group per isolate). Meshes and surrounding tissues were harvested on postoperative day 9 for quantitative culture. Results For all three isolates, vancomycin-loaded Marlex mesh exhibited sustained antibacterial activity for up to 3 days in vitro based on zone of inhibition testing (days 1–3, p < 0.0001 for each isolate). In vitro testing of biofilm inhibition demonstrated significant reduction in biofilm-associated colony-forming units at 6 hours after inoculation and remained low thereafter (p<0.05 for each isolate). In vivo , vancomycin-loaded Marlex mesh reduced bacterial burden on meshes and surrounding tissues by > 3 log₁₀ compared with plain mesh for all three isolates (p<0.01 for both mesh and tissue for all isolates). Conclusion Vancomycin-loaded Marlex mesh provided sustained local antibacterial activity and significantly reduced staphylococcal infection without compromising mechanical properties in a murine extensor mechanism reconstruction model. This approach may represent a promising adjunct to reduce infection risk in extensor mechanism reconstructions with Marlex mesh after total knee arthroplasty.

Background: Infection following extensor mechanism reconstruction (EMR) with Marlex mesh (C.R. Bard) is devastating and limb-threatening. The purpose of this study was to evaluate whether vancomycin-loaded mesh reduces staphylococcal infection in a murine EMR model. Methods: Mouse-sized, 8-layer mesh constructs were fabricated to simulate clinical reconstruction and soaked in a vancomycin solution (50 mg/mL) for in vitro and in vivo testing. Three methicillin-resistant clinical isolates from human periprosthetic Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus lugdunensis knee infections were evaluated. In vitro testing assessed vancomycin loading capacity, mechanical properties, antibacterial activity, and inhibition of biofilm formation. For in vivo experiments, plain or vancomycin-loaded mesh was implanted into C57BL/6 mouse extensor mechanisms, which were intraoperatively contaminated with 1 of the 3 study isolates (5 per group). Mesh and surrounding tissue were harvested for quantitative culture on postoperative day 9. Results: For all 3 isolates, vancomycin-loaded mesh produced zones of inhibition and exhibited antibacterial activity through at least 3 days in vitro (p < 0.0001). Mechanical testing revealed that loading mesh with vancomycin did not negatively impact tensile strength, hysteresis, or suture pull-through properties. In vitro testing of inhibition of biofilm formation demonstrated reduced colony-forming units 6 hours after inoculation, which remained low throughout the 9-day experimental period (p < 0.05 for all isolates). In vivo, vancomycin-loaded mesh reduced bacterial burden on mesh and in surrounding tissue by >3 log 10 compared with plain mesh for all 3 isolates (p < 0.01 for both mesh and tissue). Conclusions: Vancomycin-loaded mesh provided in vitro antibacterial activity without compromising mesh mechanical properties and reduced staphylococcal infection in a murine EMR model. Further work is needed to evaluate translational potential and safety before clinical application. Clinical Relevance: Mesh-associated infection after EMR is devastating and difficult to treat. These preclinical findings suggest that local vancomycin delivery may serve as an adjunct to systemic prophylaxis, warranting further study before clinical use.

Background Staphylococcus aureus causes a multiplicity of human diseases acquired in community and healthcare settings alike around the globe. While most studies focus on coding changes to assess genome evolution and study genetic adaptation, interrogation of silent mutations in the form of synonymous codon usage bias is less well-studied. As such, understanding of patterns in codon bias at the gene and genome levels, and how codon bias impacts protein expression in S. aureus remains incomplete. Methods The codon bias of 2,565 protein encoding genes from NCTC 8325 was queried against all publicly available closed S. aureus genomes. Using public BioSample data, genomes were sorted by disease state, submitting institution, and collection site. Codon bias was assessed at the level of gene and genome using the codon adaptation index (CAI), calculated using 30S and 50S ribosomal genes. Gene set enrichment analysis was applied to determine associations between physiological functions, CAI gene scores, and interquartile ranges. CAI scores were also compared to an in vitro S. aureus proteomics database to correlate codon bias and protein expression. Results CAI scores varied within and between isolates at the gene and genome levels. Genes with ribosome-associated functions were most enriched among high CAI genes, and had low CAI interquartile ranges (IQR), suggesting selective pressure to maintain high expression of these genes across all S. aureus isolates. Genome sequences submitted by Aga Khan University Hospital, Nairobi, Kenya were most different from others. For the LAC USA 300 strain, CAI and protein expression were moderately positively correlated (cor = 0.534, p < 2.2e-16). Conclusions Codon bias in S. aureus was shown to vary between gene, and to be a source of genetic variation between isolates; CAI and in vitro protein expression were positively correlated.

Background: Staphylococcus aureus causes bloodstream and skin infections in humans. The prevalence of multidrug-resistant S. aureus strains means new antibiotics are needed. A novel antimicrobial drug named SK-03-92, a synthetic aromatic organic stilbenoid compound, kills S. aureus cells within 30 min, but an increase in both biofilm formation and persister cells occurs. SK-03-92 treatment downregulates transcription of the biofilm regulating protein regulator (brpR) gene and biofilm regulating protein sensor (brpS) gene in S. aureus. BrpR/BrpS system may be a LytTR regulatory system tied to biofilm formation, creation of persister cells, and late-stage competence in S. aureus. The aim of this study was to determine what biofilm, late-stage competence, and persister-associated genes were regulated in a brpR mutant compared to wild-type strains. Methods: In this study, involvement of BrpR in regulating other genes was assessed by comparing transcriptional changes in a brpR mutant strain to the S. aureus parent strain via RNA sequencing (RNA-Seq). Bioinformatic analysis was then performed on the RNA-Seq data to assess what biochemical pathways might be involved. Results: From these analyses, 440 genes were identified that had significant differences in transcript abundance when comparing the brpR mutant to wild-type strains. Quantitative reverse transcription polymerase chain reaction analysis confirmed bacA, icd, metE, and pdhA transcript levels were lower, whereas alr and mraY were higher in the brpR mutant versus wild-type strain. Furthermore, an enzymatic assay targeting NADH production from the pyruvate dehydrogenase complex showed lower levels in the mutant compared to wild-type strain. Conclusions: Overall, the study demonstrated several biosynthetic pathways tied to biofilm formation and late-stage competency may be regulated by BrpR and some potential leads for the mechanism of action of the SK-03-92 drug were uncovered.

Aims Extensor mechanism disruption is a major complication following total knee arthroplasty, with treatment often consisting of extensor mechanism reconstruction utilizing monofilament polypropylene mesh (Marlex mesh, C. R. Bard, Inc). Infection following this procedure is devastating, often resulting in revision surgery and mesh removal, with permanent limb dysfunction. This study evaluated the in vitro ability of vancomycin-loaded polypropylene mesh to inhibit growth of isolates of three Staphylococcus species from patients with periprosthetic joint infection. Methods The mesh was prepared in two configurations – single-layer and eight-layer – and soaked for ten minutes in either sterile water (control) or vancomycin solution (50 mg/ml), after which the mesh was placed on tryptic soy agar plates inoculated with staphylococci and incubated at 37°C for 18 to 24 hours. Zones of inhibition were measured daily over seven days, with mesh transferred to freshly inoculated plates daily. Testing was performed in triplicate, with experiments repeated three times for each bacterial isolate. A total of 30 clinical isolates were tested (five methicillin-susceptible Staphylococcus epidermidis , five methicillin-resistant S. epidermidis , ten methicillin-resistant Staphylococcus aureus , and ten Staphylococcus lugdunensis ). Results Across all species, the eight-layer vancomycin-loaded mesh produced statistically significantly larger median zones of inhibition than the single-layer mesh. The antibacterial activity of the eight-layer mesh persisted through to day 7, while the single-layer mesh showed reduced activity by days 4 to 5. Conclusion Compared with single-layer vancomycin-loaded mesh, multilayer vancomycin-loaded mesh, which mimics clinical application, provides enhanced and sustained antibacterial activity in vitro. Cite this article: Bone Joint Res 2026;15(8):998–1004.

Background : Hepatocellular carcinoma (HCC) remains a major cause of cancer-related mortality. Optimal treatment decisions are challenging, and existing treatment allocation frameworks may not fully reflect the evolving therapeutic landscape or contemporary clinical practices in North America. Methods : Using a modified Delphi process, a multidisciplinary panel of 20 North American experts in hepatology, medical oncology, surgery, radiology, and radiation oncology developed a consensus-based treatment framework for HCC, termed the BEACON-HCC system. The framework was informed by current evidence and expert opinion through iterative discussion and voting. In a pilot study using 29 real-world patient cases, we assessed concordance between external expert recommendations and BEACON-HCC recommendations and Barcelona Clinic Liver Cancer (BCLC) 2025 treatment recommendations. Results : The BEACON-HCC treatment allocation framework diverges from prior frameworks by incorporating nuanced clinical features such as degree of intrahepatic tumor burden and vascular invasion, and adverse tumor prognostic markers, to align treatment allocation with tumor biology and therapeutic potential. Key innovations include the incorporation of emerging modalities such as external beam radiation therapy (EBRT), transarterial radioembolization (TARE), and systemic-locoregional combination therapies. In the pilot exercise, expert treatment decisions showed 96.6% concordance with BEACON-HCC recommendations and 72.4% concordance with BCLC recommendations. Conclusions : BEACON-HCC is a consensus-based framework for treatment allocation that incorporates the expanding range of therapeutic options available to patients in the North American HCC population. Expert treatment decisions showed a high concordance with the BEACON-HCC system; further validation using empiric clinical data is planned through the HCC-Live Consortium.

TRAIL is a TNF family ligand that trimerizes TRAIL-R1 (DR4) or TRAIL-R2 (DR5) to induce apoptosis, necroptosis, and/or NF-κB activation in receptor-bearing cells. We previously identified TRAILshort as a splice variant of TRAIL that lacks cysteine 230, cannot trimerize, and acts as a dominant-negative ligand that blocks TRAIL-mediated apoptosis. TRAILshort is expressed on cell surfaces and within extracellular vesicles, enabling it to confer TRAIL resistance to both producing and bystander cells. In this study, we showed that elevated TRAILshort levels were associated with chronic viral infections, cancer, and autoimmune diseases, suggesting a link to impaired immune regulation. Using unbiased phosphoproteomics and mechanistic studies, we demonstrated that TRAILshort binding to DR5 recruited and activated the phosphatase Src homology region 2 domain–containing phosphatase 1 (SHP-1), leading to zeta-chain-associated protein kinase 70 (ZAP-70) dephosphorylation, disruption of ZAP-70–CD3ζ interactions, and impaired T cell receptor signaling, thereby reducing T cell activation, proliferation, and cytokine production in response to antigen or CD3/CD28 ligation. Genetic or pharmacologic SHP-1 inhibition reverses these effects. In humanized mouse models, TRAILshort promoted the persistence of transformed mouse embryonic fibroblasts (MEFs) and L428 and antagonized CD19-directed CAR T cell activity, revealing TRAILshort as an immunomodulator of T cell function with therapeutic implications, including blocking TRAILshort to restore T cell immunity or delivering TRAILshort to enforce tolerance. TRAILshort, a variant of TRAIL, suppresses T cell function and immune responses in cancer and infectious diseases, highlighting its potential as a therapeutic target.

Importance Elevated low-density lipoprotein cholesterol (LDL-C) is a modifiable risk factor for cardiovascular disease, the leading cause of premature death worldwide. Assessing the LDL-C–related burden is critical for guiding prevention and treatment strategies. Objectives To estimate the global, regional, and national burden of ischemic heart disease and ischemic stroke attributable to elevated LDL-C (relative to 35-54 mg/dL) from 1990 to 2023 and to quantify the contributions of population growth, aging, risk-deleted burden, and exposure changes to burden trends. Design, Setting, and Population This comparative risk assessment, part of the Global Burden of Disease Study 2023, estimated population-level LDL-C exposure and associated health loss in 204 countries and territories. Mean LDL-C levels were estimated using spatiotemporal gaussian process regression based on 806 studies across 161 countries. Relative risks were derived from meta-analyses of 38 randomized clinical trials. Population-attributable fractions for deaths and disability-adjusted life-years (DALYs) were estimated by age and sex for adults aged 25 years or older from 1990 to 2023, with 95% uncertainty intervals. Exposure Population-level LDL-C concentrations. Main Outcomes and Measures Population-attributable fractions, counts, and rates (all ages and age standardized per 100 000) of LDL-C–attributable deaths and DALYs from ischemic heart disease and ischemic stroke, with uncertainty intervals. Results In 2023, elevated LDL-C accounted for 3.6 million deaths (95% uncertainty interval, 2.2-5.4 million; 6.0% of global mortality) and 90.7 million DALYs (95% uncertainty interval, 58.9-123.3 million; 3.2% of DALYs). Although global all-ages rates remained stable, age-standardized death and DALY rates decreased by 45.6% and 39.5%, respectively, since 1990. In 2023, age-standardized LDL-C–attributable DALY rates were highest in Eastern Europe and lowest in high-income Asia-Pacific. One-third of the global LDL-C burden occurred in India and China. Population growth and aging drove the increasing burden, with notable regional disparities in LDL-C exposure and risk-deleted DALY rates shifting toward middle-sociodemographic settings. Conclusions and Relevance Despite declining age-standardized rates, the absolute LDL-C burden has increased since 1990 due to demographic changes and has shifted toward middle-sociodemographic countries. Measurement and surveillance gaps persist. Strengthened prevention, diagnosis, and treatment access strategies are essential to mitigate the health burden of LDL-C.