Enhanced Bacterial Cuproptosis-Like Death via Reversal of Hypoxia Microenvironment for Biofilm Infection Treatment.

A recently emerging cell death pathway, known as copper-induced cell death, has demonstrated significant potential for treating infections. Existing research suggests that cells utilizing aerobic respiration, as opposed to those reliant on glycolysis, exhibit greater sensitivity to copper-induced death. Herein, a MnO2-loaded copper metal-organic frameworks platform is developed denoted as MCM, to enhance bacterial cuproptosis-like death via the remodeling of bacterial respiratory metabolism. The reversal of hypoxic microenvironments induced a cascade of responses, encompassing the reactivation of suppressed immune responses and the promotion of osteogenesis and angiogenesis. Initially, MCM catalyzed O2 production, alleviating hypoxia within the biofilm and inducing a transition in bacterial respiration mode from glycolysis to aerobic respiration. Subsequently, the sensitized bacteria, characterized by enhanced tricarboxylic acid cycle activity, underwent cuproptosis-like death owing to increased copper concentrations and aggregated intracellular dihydrolipoamide S-acetyltransferase (DLAT). The disruption of hypoxia also stimulated suppressed dendritic cells and macrophages, thereby strengthening their antimicrobial activity through chemotaxis and phagocytosis. Moreover, the nutritional effects of copper elements, coupled with hypoxia alleviation, synergistically facilitated the regeneration of bones and blood vessels. Overall, reshaping the infection microenvironment to enhance cuproptosis-like cell death presents a promising avenue for eradicating biofilms.

Mechanochemically Reprogrammed Interface Orchestrates Neutrophil Bactericidal Activity and Apoptosis for Preventing Implant-Associated Infection.

The onset of implant-associated infection (IAI) triggers a cascade of immune responses, which are initially dominated by neutrophils. Bacterial aggregate formation and hypoxic microenvironment, which occur shortly after implantation, may be two major risk factors that impair neutrophil function and lead to IAI. Here, the implant surface with phytic acid-Zn2+ coordinated TiO2 nanopillar arrays (PA-Zn@TiNPs) and oxygen self-supporting CaO2 nanoparticles, named as CPZTs, is mechanochemically reprogrammed. The engineered CPZTs interface integrates multiple properties to inhibit the formation of nascent biofilm, encompassing antibacterial adhesion, mechanobactericidal effect, and chemobiocidal effect. Meanwhile, continuous oxygenation fuels the neutrophils with reactive oxygen species (ROS) for efficient bacterial elimination on the implant surface and inside the neutrophils. Furthermore, this surface modulation strategy accelerates neutrophil apoptosis and promotes M2 macrophage-mediated osteogenesis both in vitro and in a rat model of IAI. In conclusion, targeting neutrophils for immunomodulation is a practical and effective strategy to prevent IAI and promote bone-implant integration.

Quorum Sensing Interference Assisted Therapy-Based Magnetic Hyperthermia Amplifier for Synergistic Biofilm Treatment.

Biofilms offer bacteria a physical and metabolic barrier, enhancing their tolerance to external stress. Consequently, these biofilms limit the effectiveness of conventional antimicrobial treatment. Recently, quorum sensing (QS) has been linked to biofilm's stress response to thermal, oxidative, and osmotic stress. Herein, a multiple synergistic therapeutic strategy that couples quorum sensing interference assisted therapy (QSIAT)-mediated enhanced thermal therapy with bacteria-triggered immunomodulation in a single nanoplatform, is presented. First, as magnetic hyperthermia amplifier, hyaluronic acid-coated ferrite (HA@MnFe2 O4 ) attenuates the stress response of biofilm by down-regulating QS-related genes, including agrA, agrC, and hld. Next, the sensitized bacteria are eliminated with magnetic heat. QS interference and heat also destruct the biofilm, and provide channels for further penetration of nanoparticles. Moreover, triggered by bacterial hyaluronidase, the wrapped hyaluronic acid (HA) decomposes into disaccharides at the site of infection and exerts healing effect. Thus, by reversing the bacterial tissue invasion mechanism for antimicrobial purpose, tissue regeneration following pathogen invasion and thermal therapy is successfully attained. RNA-sequencing demonstrates the QS-mediated stress response impairment. In vitro and in vivo experiments reveal the excellent antibiofilm and anti-inflammatory effects of HA@MnFe2 O4 . Overall, QSIAT provides a universal enhancement strategy for amplifying the bactericidal effects of conventional therapy via stress response interference.

Nonanatomic healing of the greater tuberosity after plating in proximal humeral fractures: a case control study.

BACKGROUND: Open reduction and plate internal fixation (ORIF) is one of the most common treatment methods for proximal humeral fractures. Complications associated with the greater tuberosity (GT) are rarely reported, therefore, the purpose of this study was to analyze the complications associated with the GT and the risk factors after locked-plate internal fixation. METHODS: We retrospectively analyzed the medical and radiographic data of patients with proximal humeral fractures involving the GT treated with locking plates between January 2016 and July 2019. We divided all patients into two groups, the anatomic GT healing group and the nonanatomic GT healing group, depending on the radiographic outcomes of the GT. Clinical outcome was assessed by the Constant scoring system. Potential risk factors included preoperative and intraoperative factors. Preoperative factors included sex, age, body mass index, fracture type, fracture-dislocation, proximal humeral bone mineral density, humeral head extension, hinge integrity, comminuted GT, volume and surface area of the main GT fragment, and displacement of the main GT fragment. Intraoperative factors were adequate medial support, residual head-shaft displacement, head-shaft angle and residual GT displacement. Univariate logistic regression and multivariate logistic regression were used to identify risk factors. RESULTS: There were 207 patients (130 women and 77 men; mean age, 55 years). GT anatomic healing was observed in 139 (67.1%) patients and nonanatomic healing in 68 (32.9%). Patients with GT nonanatomic healing had significantly inferior Constant scores than those with GT anatomic healing (75.0 ± 13.9 vs. 83.9 ± 11.8, P < 0.001). Patients with high GT malposition had worse Constant scores than patients with low GT malposition (73.3 ± 12.7 vs. 81.1 ± 11.4, P = 0.039). The multivariate logistic model showed that GT fracture characteristics were not risk factors for nonanatomic GT healing, while residual GT displacement was. CONCLUSIONS: Nonanatomic healing of the GT is a high-rate complication of proximal humeral fractures, resulting in inferior clinical outcomes, especially for high GT malposition. Fracture characteristics of the GT are not risk factors for GT nonanatomic healing and GT comminution should not be regarded as a contraindication to ORIF for proximal humeral fractures.

Effect of Fibular Allograft Augmentation in Medial Column Comminuted Proximal Humeral Fractures: A Randomized Controlled Trial.

BACKGROUND: Previous observational studies and meta-analyses have recommended augmentation with a fibular allograft (FA) during the treatment of proximal humeral fractures with locking plates (LPs). However, to our knowledge, randomized controlled trials comparing open reduction and internal fixation (ORIF) with and without FA have not been performed to date. METHODS: This was a randomized controlled trial in which adults with a medial column comminuted proximal humeral fracture were randomly allocated to undergo ORIF with an LP (the LP group) or with an LP augmented with an FA (the FA group). Patients were followed for 24 months. The primary outcome was the Disabilities of the Arm, Shoulder and Hand (DASH) score at 12 months after the surgical procedure. The secondary outcomes included the DASH score at other time points, shoulder function, pain score, satisfaction, complications, and changes in neck-shaft angle and humeral head height. RESULTS: From October 20, 2016, to December 24, 2019, 80 patients were randomized. There were 52 women (65%), and the mean patient age (and standard deviation) was 65 ± 14 years. Of the 80 patients, 39 were allocated to the FA group and 41 were allocated to the LP group. At the primary time point (12 months), the unadjusted mean between-group difference in DASH score was -1.2 (95% confidence interval [CI], -7.3 to 5.0; p = 0.71) favoring the FA group, and, with adjustment for smoking, alcohol drinking, and diabetes, the between-group difference was -1.4 (95% CI, -7.7 to 5.0; p = 0.67) favoring FA. No significant differences between the 2 groups were found among the secondary outcomes. CONCLUSIONS: No additional benefit was found for FA augmentation in treating medial column comminuted proximal humeral fractures. LEVEL OF EVIDENCE: Therapeutic Level II . See Instructions for Authors for a complete description of levels of evidence.

Gold nanoclusters-loaded hydrogel formed by dimeric hydrogen bonds crosslinking: A novel strategy for multidrug-resistant bacteria-infected wound healing.

Restoring skin integrity after wound infection remains a tougher health challenge due to the uncontrolled antibiotic-resistant pathogens caused by antibiotic abuse. Herein, an injectable hydrogel with dual antibacterial and anti-inflammatory activities composed of gold nanoclusters (GNCs) and carbomer (CBM) is developed for wound dressing to overcome multidrug-resistant infection. Firstly, both experimental investigations and molecular dynamics simulation validate the protonation state of 6-mercaptohexanoic acid (MHA) ligands play an important role in its antibacterial action of GNCs. The self-organizing GNCs-CBM composite hydrogel is then spontaneously cross-linked by the dimeric hydrogen bonds (H-bonds) between the MHA ligands and the acrylic acid groups of CBM. Benefitting from the dimeric H-bonds, the hydrogel becomes thickening enough as an ideal wound dressing and the GNCs exist in the hydrogel with a high protonation level that contributes to the enhanced bactericidal function. In all, by combining bactericidal and immunomodulatory actions, the GNCs-CBM hydrogel demonstrated excellent synergy in accelerating wound healing in animal infection models. Hence, the dimeric H-bonds strengthening strategy makes the GNCs-CBM hydrogel hold great potential as a safe and effective dressing for treating infected wounds.

Erythrocyte membrane-enveloped molybdenum disulfide nanodots for biofilm elimination on implants via toxin neutralization and immune modulation.

Implant-related infections (IRIs) caused by bacterial biofilms remain a prevalent but tricky clinical issue, and are characterized by drug resistance, toxin impairment and immunosuppression. Recently, reactive oxygen species (ROS)- and hyperthermia-based antimicrobial therapies have been developed to effectively destroy biofilms. However, almost all of them have failed to simultaneously focus on the immunosuppressive biofilm microenvironment and bacterial toxin-induced tissue damage. Herein, we proposed a one-arrow-three-hawks strategy to orchestrate hyperthermia/ROS antibiofilm therapy, toxin neutralization and immunomodulatory therapy through engineering a bioinspired erythrocyte membrane-enveloped molybdenum disulfide nanodot (EM@MoS2) nanoplatform. In the biofilm microenvironment, pore-forming toxins actively attack the erythrocyte membranes on the nanodots and are detained, thus staying away from their targets and mitigating tissue damage. Under near-infrared (NIR) laser irradiation, MoS2 nanodots, with superb photothermal and peroxidase (POD)-like properties, exert a powerful synergistic antibiofilm effect. More intriguingly, we initially identified that they possessed the ability to reverse the immunosuppressive microenvironment by skewing the macrophages from an anti-inflammatory phenotype to a proinflammatory phenotype, which would promote the elimination of biofilm debris and prevent infection relapse. Systematic in vitro and in vivo evaluations have demonstrated that EM@MoS2 achieves a remarkable antibiofilm effect. The current study integrated the functions of hyperthermia/ROS therapy, virulence clearance and immune regulation, which could provide an effective paradigm for IRIs therapy.

GPR35 regulates osteogenesis via the Wnt/GSK3ß/ß-catenin signaling pathway.

It is well known that osteoporosis is a significant chronic disease with the increase of the aging population. Here, we report that expression of G protein-coupled receptor 35 (GPR35) in bone marrow mesenchymal stem cells (BMSCs) is suppressed in diagnosed osteoporosis patients and osteoporotic mice. The expression of GPR35 on BMSCs is enhanced during osteogenic differentiation. GPR35 knockout suppresses the proliferation and osteogenesis of BMSCs and deteriorates bone mass in both sham-treated and ovariectomized mice. Moreover, GPR35 deficiency reduces ß-catenin activity in BMSCs. In contrast, the overexpression of GPR35 contributes to these processes in BMSCs. Finally, using zaprinast, a synthetic GPR35 agonist, we show that zaprinast rescues OVX-induced bone loss and promotes bone generation in mice. Thus, GPR35 may as a new target and its agonist zaprinast may serve as a novel treatment for osteoporosis.