animal-model-of-implant-associated-infections-in-mice

Animal Model of Implant-Associated Infections in Mice

Implant-associated infections represent a significant clinical challenge, as they arise when pathogenic microorganisms infiltrate the site of medical ...

University of Science and Technology of China

Biofilms are colonies of bacteria embedded inside a complicated self-generating intercellular. The formation and scatter of a biofilm is an extremely complex and progressive process in constant cycles. Once formed, it can protect the inside bacteria to exist and reproduce under hostile conditions by establishing tolerance and resistance to antibiotics as well as immunological responses. In this article, we reviewed a series of innovative studies focused on inhibiting the development of biofilm and summarized a range of corresponding therapeutic methods for biological evolving stages of biofilm. Traditionally, there are four stages in the biofilm formation, while we systematize the therapeutic strategies into three main periods precisely:(i) period of preventing biofilm formation: interfering the colony effect, mass transport, chemical bonds and signaling pathway of plankton in the initial adhesion stage; (ii) period of curbing biofilm formation:targeting several pivotal molecules, for instance, polysaccharides, proteins, and extracellular DNA (eDNA)  polysaccharide hydrolases, proteases, and DNases respectively in the second stage before developing into irreversible biofilm; (iii) period of eliminating biofilm formation: applying novel multifunctional composite drugs or nanoparticle materials cooperated with ultrasonic (US), photodynamic, photothermal and even immune therapy, such as adaptive immune activated by stimulated dendritic cells (DCs), neutrophils and even immunological memory aroused by plasmocytes. The multitargeted or combinational therapies aim to prevent it from developing to the stage of maturation and dispersion and eliminate biofilms and planktonic bacteria simultaneously.

Strategies to prevent, curb and eliminate biofilm formation based on the characteristics of various periods in one biofilm life cycle.

Over the past decade, a proliferation of research has used nanoparticles to deliver gaseous signaling molecules for medical purposes. The discovery and revelation of the role of gaseous signaling molecules have been accompanied by nanoparticle therapies for their local delivery. While most of them have been applied in oncology, recent advances have demonstrated their considerable potential in diagnosing and treating orthopedic diseases. Three of the currently recognized gaseous signaling molecules, nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (HS), are highlighted in this review along with their distinctive biological functions and roles in orthopedic diseases. Moreover, this review summarizes the progress in therapeutic development over the past ten years with a deeper discussion of unresolved issues and potential clinical applications.

Local delivery of gaseous signaling molecules for orthopedic disease therapy.

The recurrence of biofilm-associated infections (BAIs) remains high after implant-associated surgery. Biofilms on the implant surface reportedly shelter bacteria from antibiotics and evade innate immune defenses. Moreover, little is currently known about eliminating residual bacteria that can induce biofilm reinfection. Herein, novel "interference-regulation strategy" based on bovine serum albumin-iridium oxide nanoparticles (BIONPs) as biofilm homeostasis interrupter and immunomodulator via singlet oxygen ( O )-sensitized mild hyperthermia for combating BAIs is reported. The catalase-like BIONPs convert abundant H O inside the biofilm-microenvironment (BME) to sufficient oxygen gas (O ), which can efficiently enhance the generation of  O under near-infrared irradiation. The  O -induced biofilm homeostasis disturbance (e.g., sigB, groEL, agr-A, icaD, eDNA) can disrupt the sophisticated defense system of biofilm, further enhancing the sensitivity of biofilms to mild hyperthermia. Moreover, the mild hyperthermia-induced bacterial membrane disintegration results in protein leakage and  O penetration to kill bacteria inside the biofilm. Subsequently, BIONPs-induced immunosuppressive microenvironment re-rousing successfully re-polarizes macrophages to pro-inflammatory M1 phenotype in vivo to devour residual biofilm and prevent biofilm reconstruction. Collectively, this  O -sensitized mild hyperthermia can yield great refractory BAIs treatment via biofilm homeostasis interference, mild-hyperthermia, and immunotherapy, providing a novel and effective anti-biofilm strategy.

Biofilm Homeostasis Interference Therapy via  O -Sensitized Hyperthermia and Immune Microenvironment Re-Rousing for Biofilm-Associated Infections Elimination.

Bacterial biofilm-associated infections (BAIs) are the leading cause of prosthetic implant failure. The dense biofilm structure prevents antibiotic penetration, while the highly acidic and H O -rich biofilm microenvironment (BME) dampens the immunological response of antimicrobial macrophages. Conventional treatments that fail to consistently suppress escaping planktonic bacteria from biofilm result in refractory recolonization, allowing BAIs to persist. Herein, a BME-responsive copper-doped polyoxometalate clusters (Cu-POM) combination with mild photothermal therapy (PTT) and macrophage immune re-rousing for BAI eradication at all stages is proposed. The self-assembly of Cu-POM in BME converts endogenous H O to toxic ·OH through chemodynamic therapy (CDT) and generates a mild PTT effect to induce bacterial metabolic exuberance, resulting in loosening the membrane structure of the bacteria, enhancing copper transporter activity and increasing intracellular Cu-POM flux. Metabolomics reveals that intracellular Cu-POM overload restricts the TCA cycle and peroxide accumulation, promoting bacterial cuproptosis-like death. CDT re-rousing macrophages scavenge planktonic bacteria escaping biofilm disintegration through enhanced chemotaxis and phagocytosis. Overall, BME-responsive Cu-POM promotes bacterial cuproptosis-like death via metabolic interference, while also re-rousing macrophage immune response for further planktonic bacteria elimination, resulting in all-stage BAI clearance and providing a new reference for future clinical application.

Biofilm Microenvironment-Responsive Self-Assembly Nanoreactors for All-Stage Biofilm Associated Infection through Bacterial Cuproptosis-like Death and Macrophage Re-Rousing.

Implant-associated infections (IAIs) pose a significant threat to orthopedic surgeries. Bacteria colonizing the surface of implants disrupt bone formation-related cells and interfere with the osteoimmune system, resulting in an impaired immune microenvironment and osteogenesis disorders. Inspired by nature, a zeolitic imidazolate framework (ZIF)-sealed smart drug delivery system on Ti substrates (ZSTG) was developed for the "natural-artificial dual-enzyme intervention (NADEI)" strategy to address these challenges. The subtle sealing design of ZIF-8 on the TiO nanotubes ensured glucose oxidase (GOx) activity and prevented its premature leakage. In the acidic infection microenvironment, the degradation of ZIF-8 triggered the rapid release of GOx, which converted glucose into HO for disinfection. The Zn released from degraded ZIF-8, as a DNase mimic, can hydrolyze extracellular DNA, which further enhances HO-induced disinfection and prevents biofilm formation. Importantly, Zn-mediated M2 macrophage polarization significantly improved the impaired osteoimmune microenvironment, accelerating bone repair. Transcriptomics revealed that ZSTG effectively suppressed the inflammatory cascade induced by lipopolysaccharide while promoting cell proliferation, homeostasis maintenance, and bone repair. In vitro and in vivo results confirmed the superior anti-infective, osteoimmunomodulatory, and osteointegrative capacities of the ZSTG-mediated NADEI strategy. Overall, this smart bionic platform has significant potential for future clinical applications to treat IAIs.

Honeycomb-inspired ZIF-sealed interface enhances osseointegration via anti-infection and osteoimmunomodulation.

There is an increasingly growing demand to balance tissue repair guidance and opportunistic infection (OI) inhibition in clinical implant surgery. Herein, we developed a nanoadjuvant for all-stage tissue repair guidance and biofilm-responsive OI eradication via in situ incorporating Cobaltiprotoporphyrin (CoPP) into Prussian blue (PB) to prepare PB-CoPP nanozymes (PCZs). Released CoPP possesses a pro-efferocytosis effect for eliminating apoptotic and progressing necrotic cells in tissue trauma, thus preventing secondary inflammation. Once OIs occur, PCZs with switchable nanocatalytic capacity can achieve bidirectional pyroptosis regulation. Once reaching the acidic biofilm microenvironment, PCZs possess peroxidase (POD)-like activity that can generate reactive oxygen species (ROS) to eradicate bacterial biofilms, especially when synergized with the photothermal effect. Furthermore, generated ROS can promote macrophage pyroptosis to secrete inflammatory cytokines and antimicrobial proteins for biofilm eradication in vivo. After eradicating the biofilm, PCZs possess catalase (CAT)-like activity in a neutral environment, which can scavenge ROS and inhibit macrophage pyroptosis, thereby improving the inflammatory microenvironment. Briefly, PCZs as nanoadjuvants feature the capability of all-stage tissue repair guidance and biofilm-responsive OI inhibition that can be routinely performed in all implant surgeries, providing a wide range of application prospects and commercial translational value.

Balancing Bioresponsive Biofilm Eradication and Guided Tissue Repair via Pro-Efferocytosis and Bidirectional Pyroptosis Regulation during Implant Surgery.

Inadequate osseointegration at the interface is a key factor in orthopedic implant failure. Mechanistically, traditional orthopedic implant interfaces fail to precisely match natural bone regeneration processes in vivo. In this study, a novel biomimetic coating on titanium substrates (DPA-Co/GFO) through a mussel adhesion-mediated ion coordination and molecular clicking strategy is engineered. In vivo and in vitro results confirm that the coating exhibits excellent biocompatibility and effectively promotes angiogenesis and osteogenesis. Crucially, the biomimetic coating targets the integrin α2β1 receptor to promote M2 macrophage polarization and achieves a synergistic effect between immunomodulation and vascularized bone regeneration, thereby maximizing osseointegration at the interface. Mechanical push-out tests reveal that the pull-out strength in the DPA-Co/GFO group is markedly greater than that in the control group (79.04 ± 3.20 N vs 31.47 ± 1.87 N, P < 0.01) and even surpasses that in the sham group (79.04 ± 3.20 N vs 63.09 ± 8.52 N, P < 0.01). In summary, the novel biomimetic coating developed in this study precisely matches the natural process of bone regeneration in vivo, enhancing interface-related osseointegration and showing considerable potential for clinical translation and applications.

Mussel-Derived and Bioclickable Peptide Mimic for Enhanced Interfacial Osseointegration via Synergistic Immunomodulation and Vascularized Bone Regeneration.

Pathogen-host competition for manganese and intricate immunostimulatory pathways severely attenuates the efficacy of antibacterial immunotherapy against biofilm infections associated with orthopaedic implants. Herein, we introduce a spatiotemporal sono-metalloimmunotherapy (SMIT) strategy aimed at efficient biofilm ablation by custom design of ingenious biomimetic metal-organic framework (PCN-224)-coated MnO-hydrangea nanoparticles (MnPM) as a metalloantibiotic. Upon reaching the acidic HO-enriched biofilm microenvironment, MnPM can convert abundant HO into oxygen, which is conducive to significantly enhancing the efficacy of ultrasound (US)-triggered sonodynamic therapy (SDT), thereby exposing bacteria-associated antigens (BAAs). Moreover, MnPM disrupts bacterial homeostasis, further killing more bacteria. Then, the Mn ions released from the degraded MnO can recharge immune cells to enhance the cGAS-STING signaling pathway sensing of BAAs, further boosting the immune response and suppressing biofilm growth via biofilm-specific T cell responses. Following US withdrawal, the sustained oxygenation promotes the survival and migration of fibroblasts, stimulates the expression of angiogenic growth factors and angiogenesis, and neutralizes excessive inflammation. Our findings highlight that MnPM may act as an immune costimulatory metalloantibiotic to regulate the cGAS-STING signaling pathway, presenting a promising alternative to antibiotics for orthopaedic biofilm infection treatment and pro-tissue repair.

Biodegradable oxygen-evolving metalloantibiotics for spatiotemporal sono-metalloimmunotherapy against orthopaedic biofilm infections.

Excessive inflammation caused by bacterial infection is the primary cause of implant failure. Antibiotic treatment often fails to prevent peri-implant infection and may induce unexpected drug resistance. Herein, a non-antibiotic strategy based on the synergy of silver ion release and macrophage reprogramming is proposed for preventing infection and bacteria-induced inflammation suppression by the organic-inorganic hybridization of silver nanoparticle (AgNP) and quercetin (Que) into a polydopamine (PDA)-based coating on the 3D framework of porous titanium (SQPdFT). Once the planktonic bacteria (, ) reach the surface of SQPdFT, released Que disrupts the bacterial membrane. Then, AgNP can penetrate the invading bacterium and kill them, which further inhibits the biofilm formation. Simultaneously, released Que can regulate macrophage polarization homeostasis via the peroxisome proliferators-activated receptors gamma (PPARγ)-mediated nuclear factor kappa-B (NF-κB) pathway, thereby terminating excessive inflammatory responses. These advantages facilitate the adhesion and osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs), concomitantly suppressing osteoclast maturation, and eventually conferring superior mechanical stability to SQPdFT within the medullary cavity. In summary, owing to its excellent antibacterial effect, immune remodeling function, and pro-osteointegration ability, SQPdFT is a promising protective coating for titanium-based implants used in orthopedic replacement surgery.

Silver-quercetin-loaded honeycomb-like Ti-based interface combats infection-triggered excessive inflammation via specific bactericidal and macrophage reprogramming.

Bacterial implant-associated infections predominantly contribute to the failure of prosthesis implantation. The local biofilm microenvironment (BME), characterized by its hyperacidic condition and high hydrogen peroxide (HO) level, inhibits the host's immune response, thereby facilitating recurrent infections. Here, a Janus PEGylated CuS nanoparticle (CuPen) armed engineered Lactobacillus casei (L. casei) denoted as LC@CuPen, is proposed to interfere with bacterial metabolism and arouse macrophage antibiofilm function. Once LC@CuPen reached the BME, NIR irradiation-activated mild heat damages L. casei and biofilm structure. Meanwhile, the BME-responsive LC@CuPen can catalyze local HO to produce toxic •OH, whereas in normal tissues, the effect of •OH production is greatly reduced due to the higher pH and lower HO concentration. The released bacteriocin from damaged L. casei can destroy the bacterial membrane to enhance the penetration of •OH into damaged biofilm. Excessive •OH interferes with normal bacterial metabolism, resulting in reduced resistance of bacteria to heat stress. Finally, under the action of mild heat treatment, the bacterial biofilm lysed and died. Furthermore, the pathogen-associated molecular patterns (PAMPs) in LC@CuPen can induce M1 polarization of macrophages through NF-κB pathway and promote the release of inflammatory factors. Inflammatory factors enhance the migration of macrophages to the site of infection and phagocytose bacteria, thereby inhibiting the recurrence of infection. Generally, this engineered L. casei program presents a novel perspective for the treatment of bacterial implant-associated infections and serves as a valuable reference for future clinical applications of engineered probiotics.

Janus PEGylated CuS-engineered Lactobacillus casei combats biofilm infections via metabolic interference and innate immunomodulation.

Severe tissue dysfunction in diabetic patients has been a challenging clinical problem. Both bacterial infections and chronic inflammation contribute to diabetic microenvironmental disorders and poor tissue regeneration. In this paper, a composite hydrogel (Gelma@Sr-ZIF-8) was prepared by incorporating a strontium (Sr)-doped metal-organic framework (Sr-ZIF-8) into Gelatin methacryloyl (Gelma) hydrogel, which could reverse diabetic microenvironmental disorders and promote tissue regeneration in diabetic wounds. The zinc ions released from this hydrogel directly killed invading planktonic bacteria and inhibited biofilm formation. Moreover, zinc ions can disrupt biofilm structure, penetrate bacteria and remove biofilm. In addition, strontium and zinc ions reversed the pro-inflammatory immune microenvironment by modulating redox balance, restored phagocytosis by macrophages, and killed bacteria released from mature biofilms. In addition, strontium ions promote the proliferation and differentiation of osteoblasts, inhibit the activity of osteoclasts, and promote the regeneration of blood vessels at the site of bone defects, ultimately promoting the regeneration of diabetic tissue. The synergistic effect of zinc and strontium ions gives Gelma@Sr-ZIF-8 excellent full-stage antibacterial and immunomodulatory properties. In vitro and in vivo studies have shown that Gelma@Sr-ZIF-8 can remodel the disturbed diabetic microenvironment, ultimately improving the efficacy of antimicrobial therapy and promoting diabetic tissue regeneration.

Article	Year
Strategies to prevent, curb and eliminate biofilm formation based on the characteristics of various periods in one biofilm life cycle. Frontiers in cellular and infection microbiology\| PubMed ID: 36211965	2022
Local delivery of gaseous signaling molecules for orthopedic disease therapy. Journal of nanobiotechnology\| PubMed ID: 36810201	2023
Biofilm Homeostasis Interference Therapy via O -Sensitized Hyperthermia and Immune Microenvironment Re-Rousing for Biofilm-Associated Infections Elimination. Small (Weinheim an der Bergstrasse, Germany)\| PubMed ID: 36850031	2023
Biofilm Microenvironment-Responsive Self-Assembly Nanoreactors for All-Stage Biofilm Associated Infection through Bacterial Cuproptosis-like Death and Macrophage Re-Rousing. Advanced materials (Deerfield Beach, Fla.)\| PubMed ID: 37262064	2023
Honeycomb-inspired ZIF-sealed interface enhances osseointegration via anti-infection and osteoimmunomodulation. Biomaterials\| PubMed ID: 38401481	2024
Balancing Bioresponsive Biofilm Eradication and Guided Tissue Repair via Pro-Efferocytosis and Bidirectional Pyroptosis Regulation during Implant Surgery. ACS nano\| PubMed ID: 38717096	2024
Mussel-Derived and Bioclickable Peptide Mimic for Enhanced Interfacial Osseointegration via Synergistic Immunomodulation and Vascularized Bone Regeneration. Advanced science (Weinheim, Baden-Wurttemberg, Germany)\| PubMed ID: 38922775	2024
Biodegradable oxygen-evolving metalloantibiotics for spatiotemporal sono-metalloimmunotherapy against orthopaedic biofilm infections. Nature communications\| PubMed ID: 39277594	2024
Silver-quercetin-loaded honeycomb-like Ti-based interface combats infection-triggered excessive inflammation via specific bactericidal and macrophage reprogramming. Bioactive materials\| PubMed ID: 39318638	2025
Janus PEGylated CuS-engineered Lactobacillus casei combats biofilm infections via metabolic interference and innate immunomodulation. Biomaterials\| PubMed ID: 39736219	2025
Sr-MOF-based hydrogel promotes diabetic tissue regeneration through simultaneous antimicrobial and antiinflammatory properties. Materials today. Bio\| PubMed ID: 40520547	2025

Xianli Hu

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