Publications by authors named "D A C Stapels"

14 Publications

Toward Antibacterial Coatings for Personalized Implants.

ACS Biomater Sci Eng 2020 10 10;6(10):5486-5492. Epub 2020 Sep 10.

Department of Orthopedics, University Medical Center Utrecht, Utrecht 3584 CX, The Netherlands.

The complex reconstructive surgeries for which patient-specific orthopedic, maxillofacial, or dental implants are used often necessitate wounds that are open for a considerable amount of time. Unsurprisingly, this allows bacteria to establish implant-associated infection, despite the scrupulous sterilization efforts made during surgery. Here, we developed a prophylactic bactericidal coating via electrophoretic deposition technology for two 3D-printed porous titanium implant designs. The surface characteristics, antibiotic release behavior, antibacterial properties, and impact on osteoblast cell proliferation of the optimized coatings were investigated. The results unequivocally confirmed the biofunctionality of the implants in vitro. This study reveals a new avenue for future antibacterial patient-specific implants.
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http://dx.doi.org/10.1021/acsbiomaterials.0c00683DOI Listing
October 2020

Bactericidal coating to prevent early and delayed implant-related infections.

J Control Release 2020 10 21;326:38-52. Epub 2020 Jun 21.

Department of Orthopedics, University Medical Center Utrecht, Utrecht, the Netherlands. Electronic address:

The occurrence of an implant-associated infection (IAI) with the formation of a persisting bacterial biofilm remains a major risk following orthopedic biomaterial implantation. Yet, progress in the fabrication of tunable and durable implant coatings with sufficient bactericidal activity to prevent IAI has been limited. Here, an electrospun composite coating was optimized for the combinatorial and sustained delivery of antibiotics. Antibiotics-laden poly(ε-caprolactone) (PCL) and poly`1q`(lactic-co glycolic acid) (PLGA) nanofibers were electrospun onto lattice structured titanium (Ti) implants. In order to achieve tunable and independent delivery of vancomycin (Van) and rifampicin (Rif), we investigated the influence of the specific drug-polymer interaction and the nanofiber coating composition on the drug release profile and durability of the polymer-Ti interface. We found that a bi-layered nanofiber structure, produced by electrospinning of an inner layer of [PCL/Van] and an outer layer of [PLGA/Rif], yielded the optimal combinatorial drug release profile. This resulted in markedly enhanced bactericidal activity against planktonic and adherent Staphylococcus aureus for 6 weeks as compared to single drug delivery. Moreover, after 6 weeks, synergistic bacterial killing was observed as a result of sustained Van and Rif release. The application of a nanofiber-filled lattice structure successfully prevented the delamination of the multi-layer coating after press-fit cadaveric bone implantation. This new lattice design, in conjunction with the multi-layer nanofiber structure, can be applied to develop tunable and durable coatings for various metallic implantable devices. This is particularly appealing to tune the release of multiple antimicrobial agents over a period of weeks to prevent early and delayed onset IAI.
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http://dx.doi.org/10.1016/j.jconrel.2020.06.014DOI Listing
October 2020

Local structural plasticity of the evasion protein EapH1 enables engagement with multiple neutrophil serine proteases.

J Biol Chem 2020 05 17;295(22):7753-7762. Epub 2020 Apr 17.

Department of Biochemistry & Molecular Biophysics, Kansas State University, Manhattan, Kansas 66506

Members of the EAP family of immune evasion proteins potently inhibit the neutrophil serine proteases (NSPs) neutrophil elastase, cathepsin-G, and proteinase-3. Previously, we determined a 1.8 Å resolution crystal structure of the EAP family member EapH1 bound to neutrophil elastase. This structure revealed that EapH1 blocks access to the enzyme's active site by forming a noncovalent complex with this host protease. To determine how EapH1 inhibits other NSPs, we studied here the effects of EapH1 on cathepsin-G. We found that EapH1 inhibits cathepsin-G with a of 9.8 ± 4.7 nm Although this value is ∼466-fold weaker than the for EapH1 inhibition of neutrophil elastase, the time dependence of inhibition was maintained. To define the physical basis for EapH1's inhibition of cathepsin-G, we crystallized EapH1 bound to this protease, solved the structure at 1.6 Å resolution, and refined the model to and values of 17.4% and 20.9%, respectively. This structure revealed a protease-binding mode for EapH1 with cathepsin-G that was globally similar to that seen in the previously determined EapH1-neutrophil elastase structure. The nature of the intermolecular interactions formed by EapH1 with cathepsin-G differed considerably from that with neutrophil elastase, however, with far greater contributions from the inhibitor backbone in the cathepsin-G-bound form. Together, these results reveal that EapH1's ability to form high-affinity interactions with multiple NSP targets is due to its remarkable level of local structural plasticity.
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http://dx.doi.org/10.1074/jbc.RA120.013601DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7261791PMC
May 2020

Salmonella Effector SteE Converts the Mammalian Serine/Threonine Kinase GSK3 into a Tyrosine Kinase to Direct Macrophage Polarization.

Cell Host Microbe 2020 01 17;27(1):41-53.e6. Epub 2019 Dec 17.

MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK. Electronic address:

Many Gram-negative bacterial pathogens antagonize anti-bacterial immunity through translocated effector proteins that inhibit pro-inflammatory signaling. In addition, the intracellular pathogen Salmonella enterica serovar Typhimurium initiates an anti-inflammatory transcriptional response in macrophages through its effector protein SteE. However, the target(s) and molecular mechanism of SteE remain unknown. Here, we demonstrate that SteE converts both the amino acid and substrate specificity of the host pleiotropic serine/threonine kinase GSK3. SteE itself is a substrate of GSK3, and phosphorylation of SteE is required for its activity. Remarkably, phosphorylated SteE then forces GSK3 to phosphorylate the non-canonical substrate signal transducer and activator of transcription 3 (STAT3) on tyrosine-705. This results in STAT3 activation, which along with GSK3 is required for SteE-mediated upregulation of the anti-inflammatory M2 macrophage marker interleukin-4Rα (IL-4Rα). Overall, the conversion of GSK3 to a tyrosine-directed kinase represents a tightly regulated event that enables a bacterial virulence protein to reprogram innate immune signaling and establish an anti-inflammatory environment.
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http://dx.doi.org/10.1016/j.chom.2019.11.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6953433PMC
January 2020

persisters undermine host immune defenses during antibiotic treatment.

Science 2018 12;362(6419):1156-1160

MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK.

Many bacterial infections are hard to treat and tend to relapse, possibly due to the presence of antibiotic-tolerant persisters. In vitro, persister cells appear to be dormant. After uptake of species by macrophages, nongrowing persisters also occur, but their physiological state is poorly understood. In this work, we show that persisters arising during macrophage infection maintain a metabolically active state. Persisters reprogram macrophages by means of effectors secreted by the pathogenicity island 2 type 3 secretion system. These effectors dampened proinflammatory innate immune responses and induced anti-inflammatory macrophage polarization. Such reprogramming allowed nongrowing cells to survive for extended periods in their host. Persisters undermining host immune defenses might confer an advantage to the pathogen during relapse once antibiotic pressure is relieved.
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http://dx.doi.org/10.1126/science.aat7148DOI Listing
December 2018