Antisense Oligonucleotides Selectively Enter Human-Derived Antibiotic-Resistant Bacteria through Bacterial-Specific ATP-Binding Cassette Sugar Transporter

Advances in locally administered nucleic acid therapeutics

Nucleic acid drugs represent the latest generation of precision therapeutics, holding significant promise for the treatment of a wide range of intractable diseases. Delivery technology is crucial for the clinical application of nucleic acid drugs. However, extrahepatic delivery of nucleic acid drugs remains a significant challenge. Systemic administration often fails to achieve sufficient drug enrichment in target tissues. Localized administration has emerged as the predominant approach to facilitate extrahepatic delivery. While localized administration can significantly enhance drug accumulation at the injection sites, nucleic acid drugs still face biological barriers in reaching the target lesions. This review focuses on non-viral nucleic acid drug delivery techniques utilized in local administration for the treatment of extrahepatic diseases. First, the classification of nucleic acid drugs is described. Second, the current major non-viral delivery technologies for nucleic acid drugs are discussed. Third, the bio-barriers, administration approaches, and recent research advances in the local delivery of nucleic acid drugs for treating lung, brain, eye, skin, joint, and heart-related diseases are highlighted. Finally, the challenges associated with the localized therapeutic application of nucleic acid drugs are addressed.

The α-Helical Antibacterial Peptides Derived from Mastoparan with Broad-Spectrum Activity against Multidrug-Resistant Pathogens

The overuse and misuse of antibiotics resulted in the emergence of multidrug-resistant bacteria. As a promising solution, antimicrobial peptides have attracted much attention. In this research, a series of peptides derived from MP9 through the substitution of tryptophan for alanine and the rearrangement of amino acid residues were designed and synthesized. MP9-10 displayed the highest anti-multidrug-resistant bacterial activity and the lowest cytotoxicity as well as hemolysis among all the derivates. Membrane disruption was the main mechanism for MP9-10 to kill bacteria. The in vivo results on mice also demonstrated that MP9-10 had the capacity to treat infections caused by Staphylococcus aureus bacteria. In summary, MP9-10 is a promising candidate for the treatment of multidrug-resistant bacterial infections.

RNA toehold switch-based reporter assay to assess bacterial uptake of antisense oligomers

Antisense oligomers (ASOs) hold promise as antibiotics for the selective targeting of bacterial pathogens and as tools for the modulation of gene expression in microbes that are not amenable to genetic engineering. However, their efficient delivery across the complex bacterial envelope remains a major challenge. There are few methods to assess the efficiency of carrier-mediated ASO uptake by bacteria. Here, we have developed a "switch-on" reporter assay to measure ASO uptake efficiency in a semi-quantitative manner. The assay uses a synthetic RNA toehold switch fused to the mRNA of a fluorescent reporter protein, which is activated in vivo by a peptide nucleic acid (PNA)-based ASO upon delivery into the bacterial cytosol. We have used this assay to screen different cell-penetrating peptides (CPPs) as ASO carriers in Escherichia coli and Salmonella enterica and observed up to 60-fold activation, depending on the CPP and bacterial strain used. Our assay shows high dynamic range and sensitivity, which should enable high-throughput screens for bacterial ASO carriers. We also show that the reporter can be used to study routes of PNA uptake, as demonstrated by reduced reporter activity in the absence of the inner membrane protein SbmA. In summary, we present a tool for the discovery of species-specific and efficient ASO carriers that will also be useful for a broader investigation of cellular uptake mechanisms of antibacterial ASOs.IMPORTANCEThe rise of antimicrobial resistance presents a major global health challenge. If not addressed, the death toll from resistant infections is expected to rise dramatically in the coming years. As a result, it is essential to explore alternative antimicrobial therapies. One promising approach is to target bacterial mRNAs using antisense oligomers (ASOs) to silence genes involved in essential functions, virulence, or resistance. However, delivering ASOs across bacterial membranes remains a major challenge and effective methods to monitor their uptake are limited. In this study, we develop a reporter assay to facilitate the high-throughput discovery of bacterial ASO carriers. This research paves the way for developing novel precision antisense-based antibacterial therapies.

Insights into the Antimicrobial Mechanisms of a Scorpion Defensin on Staphylococcus aureus Using Transcriptomic and Proteomic Analyses

Defensins constitute a family of cationic antimicrobial peptides that act against different bacteria; however, global information regarding their antibacterial mechanisms from omics-based analyses is highly limited. In this study, transcriptomics and proteomics were used to explore the antibacterial mechanisms of defensin (BmKDfsin4) originally isolated from a scorpion on a common Gram-positive bacterium. Staphylococcus aureus (AB94004) was treated with BmKDfsin4 for 15, 30, or 45 min based on its ability to moderately inhibit bacterial growth for one hour. Compared with those in the control group, more than 1000 genes and nearly 500 proteins in S. aureus were significantly differentially expressed after BmKDfsin4 treatment. In-depth analysis revealed that BmKDfsin4 significantly upregulated bacterial ribosome-related pathways and ribosomal components. In contrast, BmKDfsin4 also significantly downregulated the synthesis and metabolism pathways of bacterial amino acids. Moreover, BmKDfsin4 inhibited the synthesis pathways of teichoic acid and peptidoglycan, which are the key components of the cell wall in S. aureus. Furthermore, glycolysis and other metabolic processes in S. aureus were markedly reduced by BmKDfsin4. Overall, the global information detected from S. aureus revealed the multiple antibacterial mechanisms of BmKDfsin4, which could encourage the exploration of global bacterial information from the defensin family with high degrees of sequence variability and accelerate the research and development of defensins as new antibacterial agents.

Ascorbate-loaded MgFe layered double hydroxide for osteomyelitis treatment

Bacterial infections evoke considerable apprehension in orthopedics. Traditional antibiotic treatments exhibit cytotoxic effects and foster bacterial resistance, thereby presenting an ongoing and formidable obstacle in the realm of therapeutic interventions. Achieving bacterial eradication and osteogenesis are critical requirements for bone infection treatment. Herein, we design and fabricate a nanoenzyme-mimicking drug through the co-precipitation process, integrating MgFe layered double hydroxide with ascorbic acid (AA@LDH), to facilitate the simultaneous presence of these two unique functionalities. Within a bacterial acidic milieu, the degradation of the AA@LDH nanosystem prompts ascorbic acid to undergo a pro-oxidative transformation, generating an abundance of reactive oxygen species (ROS). These ROS overwhelm bacterial cellular processes, including nucleic acid replication, cell wall construction, virulence factor production, biosynthetic pathways, and energy generation. This disruption culminates in substantial bacterial mortality, as substantiated by RNA sequencing data. Hence, the AA@LDH nano system exhibits an in vitro antibacterial rate of approximately 100 % and 99 %, against S.aureus and E. coli, respectivaly. Additionally, the AA@LDH could directly accelerate osteogenic differentiation in vitro, evidenced by a 50 % increase in alkaline phosphatase activity and a 270 % improvement in extracellular matrix mineralization capability. Moreover, it enhances osteointegration process in vivo by favorably reshaping the osteogenic immune microenvironment. This innovative nanosystem for delivery offers new strategies that concurrently combat bacterial infections, mitigate inflammation, and induce tissue regeneration, marking a significant advancement in the realm of advanced materials and its applications.

The Guardian of Vision: Intelligent Bacteriophage-Based Eyedrops for Clinical Multidrug-Resistant Ocular Surface Infections

Clinical multidrug-resistant Pseudomonas aeruginosa (MDR-PA) is the leading cause of refractory bacterial keratitis (BK). However, the reported BK treatment methods lack biosecurity and bioavailability, which usually causes irreversible visual impairment and even blindness. Herein, for BK caused by clinically isolated MDR-PA infection, armed phages are modularized with the type I photosensitizer (PS) ACR-DMT, and an intelligent phage eyedrop is developed for combined phagotherapy and photodynamic therapy (PDT). These eyedrops maximize the advantages of bacteriophages and ACR-DMT, enabling more robust and specific targeting killing of MDR-PA under low oxygen-dependence, penetrating and disrupting biofilms, and efficiently preventing biofilm reformation. Altering the biofilm and immune microenvironments alleviates inflammation noninvasively, promotes corneal healing without scar formation, protects ocular tissues, restores visual function, and prevents long-term discomfort and pain. This strategy exhibits strong scalability, enables at-home treatment of ocular surface infections with great patient compliance and a favorable prognosis, and has significant potential for clinical application.

Harnessing and Mimicking Bacterial Features to Combat Cancer: From Living Entities to Artificial Mimicking Systems

Bacterial-derived micro-/nanomedicine has garnered considerable attention in anticancer therapy, owing to the unique natural features of bacteria, including specific targeting ability, immunogenic benefits, physicochemical modifiability, and biotechnological editability. Besides, bacterial components have also been explored as promising drug delivery vehicles. Harnessing these bacterial features, cutting-edge physicochemical and biotechnologies have been applied to attenuated tumor-targeting bacteria with unique properties or functions for potent and effective cancer treatment, including strategies of gene-editing and genetic circuits. Further, the advent of bacteria-inspired micro-/nanorobots and mimicking artificial systems has furnished fresh perspectives for formulating strategies for developing highly efficient drug delivery systems. Focusing on the unique natural features and advantages of bacteria, this review delves into advances in bacteria-derived drug delivery systems for anticancer treatment in recent years, which has experienced a process from living entities to artificial mimicking systems. Meanwhile, a summary of relative clinical trials is provided and primary challenges impeding their clinical application are discussed. Furthermore, future directions are suggested for bacteria-derived systems to combat cancer.

Cell Wall Binding Strategies Based on Cu3SbS3 Nanoparticles for Selective Bacterial Elimination and Promotion of Infected Wound Healing

Utilizing nanomaterials as an alternative to antibiotics, with a focus on maintaining high biosafety, has emerged as a promising strategy to combat antibiotic resistance. Nevertheless, the challenge lies in the indiscriminate attack of nanomaterials on both bacterial and mammalian cells, which limits their practicality. Herein, Cu3SbS3 nanoparticles (NPs) capable of generating reactive oxygen species (ROS) are discovered to selectively adsorb and eliminate bacteria without causing obvious harm to mammalian cells, thanks to the interaction between O of N-acetylmuramic acid in bacterial cell walls and Cu of the NPs. Coupled with the short diffusion distance of ROS in the surrounding medium, a selective antibacterial effect is achieved. Additionally, the antibacterial mechanism is then identified: Cu3SbS3 NPs catalyze the generation of O2•-, which has subsequently been conversed by superoxide dismutase to H2O2. The latter is secondary catalyzed by the NPs to form •OH and 1O2, initiating an in situ attack on bacteria. This process depletes bacterial glutathione in conjunction with the disruption of the antioxidant defense system of bacteria. Notably, Cu3SbS3 NPs are demonstrated to efficiently impede biofilm formation; thus, a healing of MRSA-infected wounds was promoted. The bacterial cell wall-binding nanoantibacterial agents can be widely expanded through diversified design.

Photoactivated Gas-Generating Nanocontrast Agents for Long-Term Ultrasonic Imaging-Guided Combined Therapy of Tumors

To date, long-term and continuous ultrasonic imaging for guiding the puncture biopsy remains a challenge. In order to address this issue, a multimodality imaging and therapeutic method was developed in the present study to facilitate long-term ultrasonic and fluorescence imaging-guided precision diagnosis and combined therapy of tumors. In this regard, certain types of photoactivated gas-generating nanocontrast agents (PGNAs), capable of exhibiting both ultrasonic and fluorescence imaging ability along with photothermal and sonodynamic function, were designed and fabricated. The advantages of these fabricated PGNAs were then utilized against tumors in vivo, and high therapeutic efficacy was achieved through long-term ultrasonic imaging-guided treatment. In particular, the as-prepared multifunctional PGNAs were applied successfully for the fluorescence-based determination of patient tumor samples collected through puncture biopsy in clinics, and superior performance was observed compared to the clinically used SonoVue contrast agents that are incapable of specifically distinguishing the tumor in ex vivo tissues.

Coordination-Driven Self-Assembly of Metal Ion-Antisense Oligonucleotide Nanohybrids for Chronic Bacterial Infection Therapy

Bacterial infection poses a significant challenge to wound healing and skin regeneration, leading to substantial economic burdens on patients and society. Therefore, it is crucial to promptly explore and develop effective methodologies for bacterial infections. Herein, we propose a novel approach for synthesizing nanostructures based on antisense oligonucleotides (ASOs) through the coordination-driven self-assembly of Zn2+ with ASO molecules. This approach aims to provide effective synergistic therapy for chronic wound infections caused by Staphylococcus aureus (S. aureus). The resulting hybrid nanoparticles successfully preserve the structural integrity and biological functionalities of ASOs, demonstrating excellent ASO encapsulation efficiency and bioaccessibility. In vitro antibacterial experiments reveal that Zn-ASO NPs exhibit antimicrobial properties against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis. This antibacterial ability is attributed to the high concentration of metal zinc ions and the generation of high levels of reactive oxygen species. Additionally, the ftsZ-ASO effectively inhibits the expression of the ftsZ gene, further enhancing the antimicrobial effect. In vivo antibacterial assays demonstrate that the Zn-ASO NPs promote optimal skin wound healing and exhibit favorable biocompatibility against S. aureus infections, resulting in a residual infected area of less than 8%. This combined antibacterial strategy, which integrates antisense gene therapy and metal-coordination-directed self-assembly, not only achieves synergistic and augmented antibacterial outcomes but also expands the horizons of ASO coordination chemistry. Moreover, it addresses the gap in the antimicrobial application of metal-coordination ASO self-assembly, thereby advancing the field of ASO-based therapeutic approaches.

A multifunctional ionic liquid coating on 3D-Printed prostheses: Combating infection, promoting osseointegration

Periprosthetic infection and mechanical loosening are two leading causes of implant failure in orthopedic surgery that have devastating consequences for patients both physically and financially. Hence, advanced prostheses to simultaneously prevent periprosthetic infection and promote osseointegration are highly desired to achieve long-term success in orthopedics. In this study, we proposed a multifunctional three-dimensional printed porous titanium alloy prosthesis coated with imidazolium ionic liquid. The imidazolium ionic liquid coating exhibited excellent bacterial recruitment property and near-infrared (NIR) triggered photothermal bactericidal activity, enabling the prosthesis to effectively trap bacteria in its vicinity and kill them remotely via tissue-penetrating NIR irradiation. In vivo anti-infection and osseointegration investigations in infected animal models confirmed that our antibacterial prosthesis could provide long-term and sustainable prevention against periprosthetic infection, while promoting osseointegration simultaneously. It is expected to accelerate the development of next-generation prostheses and improve patient outcomes after prosthesis implantation.

Controllable Assembly of Cu2+ and Chlorin E6 for H2 S-Activatable Recognition of Bacterial Infection and Enhanced Antibacterial Therapy

Antibacterial photodynamic therapy (APDT) has emerged as one of the intriguing strategies to combat bacterial resistance. However, the antibacterial efficacy of APDT is found to be severely impacted by the hydrogen sulfide (H2 S)-overproduced bacterial infection microenvironment. Herein, a multifunctional APDT platform is developed by assembling Cu2+ and chlorin e6 (Ce6), which exhibits unique H2 S-activatable fluorescence (FL) and antibacterial features. Noteworthily, the assembly conditions are crucial for achievement of Cu-Ce6 nanoassemblies (NAs) with the on-demand responsive properties. The quenched FL and photosensitization of Cu-Ce6 NAs can be selectively activated by the overexpressed H2 S in infected area, enabling specific recognition of bacterial infection and localized antibacterial therapy with minimized side effects. Significantly, amplified oxidative stress is achieved owning to the effective consumption of H2 S by Cu2+ in the NAs, leading to an enhanced APDT. The antibacterial mechanisms including broad-spectrum APDT activity of released Ce6, inherent sterilization effects of produced copper polysulfides and the accompanying disturbance of bacterial sulphide metabolism are further identified. This study may pave a new avenue for the rational design of intelligent APDT platform using minimalist biological building units and thus facilitating the clinical translation of nano-antibacterial agents.

Subtractive modification of bacterial consortium using antisense peptide nucleic acids

Microbiome engineering is an emerging research field that aims to design an artificial microbiome and modulate its function. In particular, subtractive modification of the microbiome allows us to create an artificial microbiome without the microorganism of interest and to evaluate its functions and interactions with other constituent bacteria. However, few techniques that can specifically remove only a single species from a large number of microorganisms and can be applied universally to a variety of microorganisms have been developed. Antisense peptide nucleic acid (PNA) is a potent designable antimicrobial agent that can be delivered into microbial cells by conjugating with a cell-penetrating peptide (CPP). Here, we tested the efficacy of the conjugate of CPP and PNA (CPP-PNA) as microbiome modifiers. The addition of CPP-PNA specifically inhibited the growth of Escherichia coli and Pseudomonas putida in an artificial bacterial consortium comprising E. coli, P. putida, Pseudomonas fluorescens, and Lactiplantibacillus plantarum. Moreover, the growth inhibition of P. putida promoted the growth of P. fluorescens and inhibited the growth of L. plantarum. These results indicate that CPP-PNA can be used not only for precise microbiome engineering but also for analyzing the growth relationships among constituent microorganisms in the microbiome.

Bacteria-Based Living Probes: Preparation and the Applications in Bioimaging and Diagnosis

Bacteria can colonize a variety of in vivo biointerfaces, particularly the skin, nasal, and oral mucosa, the gastrointestinal tract, and the reproductive tract, but also target specific lesion sites, such as tumor and wound. By virtue of their prominent characteristics in motility, editability, and targeting ability, bacteria carrying imageable agents are widely developed as living probes for bioimaging and diagnosis of different diseases. This review first introduces the strategies used for preparing bacteria-based living probes, including biological engineering, chemical modification, intracellular loading, and optical manipulation. It then summarizes the recent progress of these living probes for fluorescence imaging, near-infrared imaging, ultrasonic imaging, photoacoustic imaging, magnetic resonance imaging, and positron emission tomography imaging. The biomedical applications of bacteria-based living probes are also reviewed particularly in the bioimaging and diagnosis of bacterial infections, cancers, and intestine-associated diseases. In addition, the advantages and challenges of bacteria-based living probes are discussed and future perspectives are also proposed. This review provides an updated overview of bacteria-based living probes, highlighting their great potential as a unique yet versatile platform for developing next-generation imageable agents for intelligent bioimaging, diagnosis, and even therapy.