Poly(ferrocenylsilane)-Based Redox-Active Artificial Organelles for Biomimetic Cascade Reactions.

Artificial organelles serve as functional counterparts to natural organelles, which are primarily employed to artificially replicate, restore, or enhance cellular functions. While most artificial organelles exhibit basic functions, we diverge from this norm by utilizing poly(ferrocenylmethylethylthiocarboxypropylsilane) microcapsules (PFC MCs) to construct multifunctional artificial organelles through water/oil interfacial self-assembly. Within these PFC MCs, enzymatic cascades are induced through active molecular exchange across the membrane to mimic the functions of enzymes in mitochondria. We harness the inherent redox properties of the PFC polymer, which forms the membrane, to facilitate in-situ redox reactions similar to those supported by the inner membrane of natural mitochondria. Subsequent studies have demonstrated the interaction between PFC MCs and living cell including extended lifespans within various cell types. We anticipate that functional PFC MCs have the potential to serve as innovative platforms for organelle mimics capable of executing specific cellular functions.

Effects and mechanisms of Salmonella plasmid virulence gene spv on host-regulated cell death.

Salmonella is responsible for the majority of food poisoning outbreaks around the world. Pathogenic Salmonella mostly carries a virulence plasmid that contains the Salmonella plasmid virulence gene (spv), a highly conserved sequence encoding effector proteins that can manipulate host cells. Intestinal epithelial cells are crucial components of the innate immune system, acting as the first barrier of defense against infection. When the barrier is breached, Salmonella encounters the underlying macrophages in lamina propria, triggering inflammation and engaging in combat with immune cells recruited by inflammatory factors. Host regulated cell death (RCD) provides a variety of means to fight against or favour Salmonella infection. However, Salmonella releases effector proteins to regulate RCD, evading host immune killing and neutralizing host antimicrobial effects. This review provides an overview of pathogen-host interactions in terms of (1) pathogenicity of Salmonella spv on intestinal epithelial cells and macrophages, (2) mechanisms of host RCD to limit or promote pathogenic Salmonella expansion, and (3) effects and mechanisms of Salmonella spv gene on host RCD.

Surface demineralized freeze-dried bone allograft followed by reimplantation in a failed mandibular dental implant.

The removal of a failed implant with high torque causes significant damage to the surrounding tissue, compromising bone regeneration and subsequent osseointegration in the defect area. Here, we report a case of carrier screw fracture followed by immediate implant removal, bone grafting and delayed reimplantation. A dental implant with a fractured central carrier screw was removed using the bur-forceps technique. The resulting three-wall bone defect was filled with granular surface demineralized freeze-dried bone allograft (SD-FDBA). Cone-beam computerized tomography was performed at 1 week, 6 months and 15 months postoperatively and standardized for quantitative evaluation. The alveolar bone width and height at 15 months post-surgery were about 91% of the original values, with a slightly lower bone density, calculated using the gray value ratio. The graft site was reopened and was found to be completely healed with dense and vascularized bone along with some residual bone graft. Reimplantation followed by restoration was performed 8 months later. The quality of regenerated bone following SD-FDBA grafting was adequate for osseointegration and long-term implant success. The excellent osteogenic properties of SD-FDBA are attributed to its human origin, cortical bone-like structure, partly demineralized surfaces and bone morphogenetic protein-2-containing nature. Further investigation with more cases and longer follow-up was required to confirm the final clinical effect.

Salmonella spvC gene suppresses macrophage/neutrophil antibacterial defense mediated by gasdermin D.

OBJECTIVE: Salmonella enterica serovar Typhimurium (S. Typhimurium) is a representative model organism for investigating host-pathogen interactions. It was reported that S. Typhimurium spvC gene alleviated intestinal inflammation to aggravate systemic infection, while the precise mechanisms remain unclear. In this study, the influence of spvC on the antibacterial defense of macrophage/neutrophil mediated by gasdermin D (GSDMD) was investigated. METHODS: Mouse macrophage-like cell lines J774A.1 and RAW264.7, neutrophil-like cells derived from HL-60 cells (human promyletic leukemia cell lines) were infected with S. Typhimurium wild type, spvC deletion and complemented strains. Cell death was evaluated by LDH release and Annexin V-FITC/PI staining. Macrophage pyroptosis and neutrophil NETosis were detected by western blotting, live cell imaging and ELISA. Flow cytometry was used to assess the impact of spvC on macrophage-neutrophil cooperation in macrophage (dTHP-1)-neutrophil (dHL-60) co-culture model pretreated with GSDMD inhibitor disulfiram. Wild-type and Gsdmd-/- C57BL/6J mice were utilized for in vivo assay. The degree of phagocytes infiltration and inflammation were analyzed by immunofluorescence and transmission electron microscopy. RESULTS: Here we find that spvC inhibits pyroptosis in macrophages via Caspase-1/Caspase-11 dependent canonical and non-canonical pathways, and restrains neutrophil extracellular traps extrusion in GSDMD-dependent manner. Moreover, spvC could ameliorate macrophages/neutrophils infiltration and cooperation in the inflammatory response mediated by GSDMD to combat Salmonella infection. CONCLUSIONS: Our findings highlight the antibacterial activity of GSDMD in phagocytes and reveal a novel pathogenic mechanism employed by spvC to counteract this host defense, which may shed new light on designing effective therapeutics to control S. Typhimurium infection.

Enhanced Anti-inflammatory Capacity of the Conditioned Medium Derived from Periodontal Ligament Stem Cells Modified with an Iron-Based Nanodrug.

Cell-free therapy using conditioned medium (CM) from mesenchymal stem cells takes full advantage of the bioactive factors secreted by the cells while avoiding disadvantages such as immune rejection and tumor formation due to cell transplantation. In this study, human periodontal ligament stem cells (PDLSCs) are modified with the superparamagnetic iron oxide nanoparticle (SPION)-based nanodrug ferumoxytol (PDLSC-SPION). Compared with PDLSCs, PDLSC-SPION showed good cell viability and better osteogenic differentiation ability. Cell-free CM is collected and the anti-inflammatory capacity of PDLSC CM and PDLSC-SPION CM is assessed by treatment of lipopolysaccharide-stimulated macrophages and IL-17-stimulated human gingival fibroblasts. Both CMs inhibited the expression of proinflammatory cytokines in cells, and the therapeutic effect is more distinct for PDLSC-SPION CM than PDLSC CM, which may be due to their different proteomic compositions. Therefore, modification of PDLSCs with ferumoxytol enhances the anti-inflammatory capacity of its CM, making it more potentially useful for the treatment of inflammatory diseases such as periodontitis.

Salmonella effector SopF regulates PANoptosis of intestinal epithelial cells to aggravate systemic infection.

SopF, a newly discovered effector secreted by Salmonella pathogenicity island-1 type III secretion system (T3SS1), was reported to target phosphoinositide on host cell membrane and aggravate systemic infection, while its functional relevance and underlying mechanisms have yet to be elucidated. PANoptosis (pyroptosis, apoptosis, and necroptosis) of intestinal epithelial cells (IECs) has been characterized as a pivotal host defense to limit the dissemination of foodborne pathogens, whereas the effect of SopF on IECs PANoptosis induced by Salmonella is rather limited. Here, we show that SopF can attenuate intestinal inflammation and suppress IECs expulsion to promote bacterial dissemination in mice infected with Salmonella enterica serovar Typhimurium (S. Typhimurium). We revealed that SopF could activate phosphoinositide-dependent protein kinase-1 (PDK1) to phosphorylate p90 ribosomal S6 kinase (RSK) which down-regulated Caspase-8 activation. Caspase-8 inactivated by SopF resulted in inhibition of pyroptosis and apoptosis, but promotion of necroptosis. The administration of both AR-12 (PDK1 inhibitor) and BI-D1870 (RSK inhibitor) potentially overcame Caspase-8 blockade and subverted PANoptosis challenged by SopF. Collectively, these findings demonstrate that this virulence strategy elicited by SopF aggregates systemic infection via modulating IEC PANoptosis through PDK1-RSK signaling, which throws light on novel functions of bacterial effectors, as well as a mechanism employed by pathogens to counteract host immune defense.

Multidimensional Quantitative Measurement of Cancer Chemoresistance through Differential ZIF-8 Nanoparticle Cellular Retention.

Chemoresistance of cancer cells is conventionally quantified by half-maximal inhibitory concentration (IC50) or multidrug resistance gene 1 (MDR1) values, but these metrics can only reflect the overall drug resistance level of a cancer cell line. Meanwhile, the multidimensional evaluation of both the heterogeneity in a cell line and the drug resistance degree of each cell still presents a daunting challenge. We report here that the cellular heterogeneity, cellular cross contamination, and the proportion of chemoresistant cancer cells can be visualized via flow cytometry through the differential cellular retention of fluorescent ZIF-8 nanoparticles. In addition, we show that the degree of drug resistance exhibited by each cell subpopulation can be quantified by differing fluorescence of the drug-resistant and drug-sensitive cells in the corresponding flow cytometry profile, and the quantified metric S is highly consistent with the MDR1 expression results. Importantly, this novel strategy is applicable to various cancer cell lines, thus demonstrating a universal diagnosis platform for multidimensional, quantitative, and highly efficient diagnosis of cancer chemoresistance.

A novel phosphodiesterase 9A inhibitor LW33 protects against ischemic stroke through the cGMP/PKG/CREB pathway.

BACKGROUND: Ischemic stroke is one of the leading causes of mortality worldwide. The available treatments are not effective. Phosphodiesterase 9A (PDE9A) is an intracellular cyclic guanosine monophosphate (cGMP) hydrolase considered to be a promising therapeutic target for brain diseases. This study explored neuroprotective effects and the underlying mechanism of LW33, a novel PDE9A inhibitor, on ischemic stroke in vitro and in vivo. METHODS: A middle cerebral artery occlusion (MCAO) model was established in adult male Sprague-Dawley rats and an oxygen-glucose deprivation/reoxygenation (OGD/R) model was established in human SH-SY5Y cells to mimic ischemia-reperfusion injury in vitro. RESULTS: LW33 increased cell viability, reduced lactate dehydrogenase activity, and OGD/R-induced apoptosis of SH-SY5Y cells. The protective effects of LW33 against stroke occurred in the recovery phase. LW33 administration significantly reduced cerebral infarction volume in MCAO rats, without causing significant deformation or necrosis of neurons in the cortex. LW33 also improved learning and cognitive dysfunction and reduced other pathological changes in MCAO rats in the recovery period. Moreover, LW33 stimulated the cGMP/PKG/CREB pathway and up-regulated the expression of the apoptosis-related proteins, and this effect was reversed by KT5823 treatment. CONCLUSION: LW33 inhibited cell apoptosis and promoted neuronal repair to alleviate OGD/R and MCAO induced pathological alterations via the cGMP/PKG/CREB pathway, indicating that LW33 may be a promising therapeutic target for ischemic stroke.

In Situ Preparation of Composite Redox-Active Micelles Bearing Pd Nanoparticles for the Reduction of 4-Nitrophenol.

Owing to the redox activity of the poly(ferrocenylsilane)-based polymer, several noble metal nanoparticles can be successfully prepared. As reported herein, the in situ preparation of Pd nanoparticles was performed using a redox-active platform of poly(ferrocenylmethylethylthiocarboxylpropylsilane) (PFC) micelles. PFC/Pd nanocomposites (NCs) with Pd nanoparticles uniformly dispersed at the surface of PFC nanospheres were obtained. The morphology of PFC/Pd NCs was further confirmed via high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. Taking advantage of Pd nanoparticles, the PFC/Pd NCs showed significant catalytic activity during the reduction process of 4-nitrophenol by sodium borohydride. Although PFC micelles themselves showed no catalytic activity, they promoted the catalytic behavior of Pd nanoparticles obviously by anchoring the Pd nanoparticles at their surface to avoid the aggregation and leaching of Pd nanoparticles. In all, PFC/Pd NCs exhibited great potential as a composite nanocatalyst. Moreover, the PFC micelle was found to be a desired platform for nanocatalysts.

Redox-Active Micelle-Based Reaction Platforms for In Situ Preparation of Noble Metal Nanocomposites with Photothermal Conversion Capability.

Polyferrocenylsilane (PFS)-based polymers are an attractive family of organometallic polymers with unique redox-active properties. Herein, we report a novel amphiphilic redox-active PFS-based homopolymer, poly(ferrocenylmethylethylthiocarboxypropylsilane) (PFC), with a hydrophobic backbone chain and hydrophilic carboxylic acid side groups in each repeating unit. Self-assembly was induced by addition of water to a molecularly dispersed solution of PFC in DMSO. Spherical PFC micelles with controllable hydrodynamic diameters (60-180 nm) were obtained under various conditions. These PFC micelles could be readily endocytosed by A549 cells and HUVEC cells and show no significant cytotoxicity toward them at the concentration of 200 µg/mL. On this basis, Au nanoparticles (AuNPs) were prepared through in situ reduction of HAuCl4 by PFC micelles as nanoreactors without requiring any other reductants. The PFC/Au nanocomposites (NCs) were found to exhibit significant photothermal behavior. Moreover, PFC micelles could also act as nanoreactors for other noble metals such as Ag, Pd, and Pt. By taking advantage of properties of the nanostructures and noble metal nanoparticles comprising these materials, the PFC micelles and PFC/noble metal NCs may have great potential in biomedical or catalytic applications.

High-Order Assembly toward Polysaccharide-Based Complex Coacervate Nanodroplets Capable of Targeting Cancer Cells.

High-order assembly plays a significant role in the formation of living organisms containing a large number of biomacromolecules and, thus, enlightens the construction of nanomaterials that can load macromolecular payloads at a high efficiency. Herein, by choosing anionic hyaluronic acid (HA) as a model payload, we demonstrated how the electrostatic-interaction-induced high-order assembly can be used to load efficiently biomacromolecules into complex coacervate nanodroplets. The resultant assemblies were primarily composed of HA and cationic chitosan oligosaccharide/dextran (COS/Dex) nanogels and had a controllable structure while also exhibiting biological functionality. HA in the assemblies is capable of targeting CD44-overexpressed tumor cells through CD44-mediated endocytic pathways, which are elucidated herein. Therefore, this study provides a reliable approach for the efficient loading of macromolecular payloads into complex coacervate nanodroplets via electrostatic-attraction-induced high-order assembly.

Bio-inspired gene carriers with low cytotoxicity constructed via the assembly of dextran nanogels and nano-coacervates.

Aim: To achieve safe and biocompatible gene carriers. Materials & methods: A core/shell-structured hierarchical carrier with an internal peptide/gene coacervate 'core' and a dextran nanogel 'shell' on the surface has been designed. Results: The dextran nanogels shield coacervate (DNSC) can effectively condense genes and release them in reducing environments. The dextran nanogel-based 'shell' can effectively shield the positive charge of the peptide/gene coacervate 'core', thus reducing the side effects of cationic gene carriers. In contrast with the common nonviral gene carriers that had high cytotoxicities, the DNSC showed a high transfection efficiency while maintaining a low cytotoxicity. Conclusion: The DNSC provides an effective environmentally responsive gene carrier with potential applications in the fields of gene therapy and gene carrier development.

Self-immobilized biomixture with pellets of Aspergillus niger Y3 and Arthrobacter. sp ZXY-2 to remove atrazine in water: A bio-functions integration system.

The microorganism Arthrobacter. ZXY-2 exhibits excellent degradation efficiency for atrazine in free cells. However, its poor fixability makes it hard to be kept and recycled in water. To conquer the problem, this work employed mycelial pellets of Aspergillus niger Y3 to immobilize ZXY-2, which formed a self-immobilized biomixture (SIB) to remove atrazine. SIB could completely degrade 57.3 mg/L atrazine within 10 h. The SIB exhibited the highest degradation efficiency at pH = 7 and 40 °C. Degradation of atrazine with initial concentrations of 57.3 mg/L and 17.5 mg/L was described well by zero and first-order reaction kinetics, respectively. The recycling experiments demonstrated that SIB could be recycled for 5 batches. The results of SEM, FT-IR, and zeta potential analysis showed that porous structure, functional groups, and electronegativity of SIB all contributed to its stable formation. Therefore, this study demonstrates that SIB could be formed stably and could remove atrazine efficiently.

Scalable and cleavable polysaccharide nanocarriers for the delivery of chemotherapy drugs.

While polysaccharide-based nanocarriers have been recognized for their crucial roles in tumor theranostics, the industrial-scale production of nanotherapeutics still remains a significant challenge. Most current approaches adopt a postpolymerization self-assembly strategy that follows a separate synthetic step and thus suffers from subgram scale yields and a limited range of application. In this study, we demonstrate the kilogram-scale formation of polysaccharide-polyacrylate nanocarriers at concentrations of up to 5 wt% through a one-pot approach - starting from various acrylate monomers and polysaccharides - that combines aspects of hydrophobicity-induced self-assembly with the free radical graft copolymerization of acrylate monomers from polysaccharide backbones into a single process that is thus denoted as a graft copolymerization induced self-assembly. We also demonstrate that this novel approach is applicable to a broad range of polysaccharides and acrylates. Notably, by choosing a crosslinker that bears a disulfide group and two vinyl capping groups to structurally lock the nanocarriers, the products are rendered cleavable in the reducing environments encountered at tumor sites and thus provide ideal candidates for the construction of anticancer nanotherapeutic systems. In vitro and in vivo studies demonstrated that the use of this nanocarrier for the delivery of doxorubicin hydrochloride (DOX) significantly decreased the side effects of DOX and improved the bio-safety of the chemotherapy accordingly. STATEMENT OF SIGNIFICANCE: While polysaccharide-based nanocarriers have been recognized for their crucial roles in tumor theranostics, the industrial-scale production of these nanotherapeutics still remains a significant challenge. Most current approaches adopt a post-polymerization self-assembly strategy which that follows a separate synthetic step, and thus suffers from sub-gram scale yields and a limited range of application. In this study, the hydrophobic effect was combined with free radical polymerization to facilitate the graft copolymerization-induced self-assembly (GISA) of acrylate monomers with various hydrophobicities to construct cleavable polysaccharide-polyacrylate nanocarriers at a high efficiency with excellent potential for industrial-scale production. We envision that these nanocarriers will contribute to the development of tumor nanotheranostics that combine the biological functionalities of polysaccharides with the unmatched application-specific flexibility of nanocarriers.