Chemical coupling as a potent strategy for preparation of targeted bacteriophage-derived gene nanocarriers into eukaryotic cells

Improving the safety and efficacy of phage therapy from the perspective of phage-mammal interactions

Phage therapy has re-emerged as a promising solution for combating antimicrobial-resistant bacterial infections. Increasingly, studies have revealed that phages possess therapeutic potential beyond their antimicrobial properties, including regulating the gut microbiome and maintain intestinal homeostasis, as a novel nanocarrier for targeted drug delivery. However, the complexity and unpredictability of phage behavior during treatment pose a significant challenge in clinical practice. The intricate interactions established between phages, humans, and bacteria throughout their long coexistence in the natural ecosystem contribute to the complexity of phage behavior in therapy, raising concerns about their efficacy and safety as therapeutic agents. Revealing the mechanisms by which phages interact with the human body will provide a theoretical basis for increased application of promising phage therapy. In this review, we provide a comprehensive summary of phage-mammal interactions, including signaling pathways, adaptive immunity responses, and phage-mediated anti-inflammatory responses. Then, from the perspective of phage-mammalian immune system interactions, we present the first systematic overview of the factors affecting phage therapy, such as the mode of administration, the physiological status of the patient, and the biological properties of the phage, to offer new insights into phage therapy for various human diseases.

Construction of PEI-EGFR-PD-L1-siRNA dual functional nano-vaccine and therapeutic efficacy evaluation for lung cancer

BACKGROUND

PD-1/PD-L1 tumor immunotherapy shows effective anticancer in treatment of solid tumors, so PEI lipid nanoparticles (PEI-LNP)/siRNA complex (EPV-PEI-LNP-SiRNA) with the therapeutic function of PD-L1-siRNA and EGFR short peptide/PD-L1 double immune-enhancing function were constructed for the prevention and treatment of EGFR-positive lung cancer in this study.

METHOD

In this study, PEI lipid nanoparticles (PEI-LNP)/siRNA complex (EPV-PEI-LNP-siRNA) with the therapeutic function of PD-L1-siRNA and EGFR short peptide/PD-L1 double immune-enhancing function were constructed for the prevention and treatment of EGFR-positive lung cancer and functional evaluation was conducted.

RESULTS

On the basis of the construction of the composite nano-drug delivery system, the binding capacity, cytotoxicity, apoptosis and uptake capacity of siRNA and EPV-PEI-LNP were tested in vitro, and the downregulation effect of PD-L1 on A549 cancer cells and the cytokine levels of cocultured T cells were tested. Lipid nanoparticles delivered siRNA and EGFR short peptide vaccine to non-small cell lung cancer (NSCLC), increasing tumor invasion and activation of CD8 + T cells. Combination therapy is superior to single target therapy.

CONCLUSION

Our constructed lipid nanoparticles of tumor targeted therapy gene siRNA combination had the ability to target cells in vitro and downregulate the expression of PD-L1, realizing the tumor-specific expression of immune-stimulating cytokines, which is a highly efficient and safe targeted therapy nano-vaccine.

A Strategy to Select Macrocyclic Peptides Featuring Asymmetric Molecular Scaffolds as Cyclization Units by Phage Display

Macrocyclic peptides (MPs) have positioned themselves as a privileged class of compounds for the discovery of therapeutics and development of chemical probes. Aided by the development of powerful selection strategies, high-affinity binders against biomolecular targets can readily be elicited from massive, genetically encoded libraries by affinity selection. For example, in phage display, MPs are accessed on the surface of whole bacteriophages via disulfide formation, the use of (symmetric) crosslinkers, or the incorporation of non-canonical amino acids. To facilitate a straightforward cyclization of linear precursors with asymmetric molecular scaffolds, which are often found at the core of naturally occurring MPs, we report an efficient two-step strategy to access MPs via the programmed modification of a unique cysteine residue and an N-terminal amine. We demonstrate that this approach yields MPs featuring asymmetric cyclization units from both synthetic peptides and when linear precursors are appended onto a phage-coat protein. Finally, we showcase that our cyclization strategy is compatible with traditional phage-display protocols and enables the selection of MP binders against a model target protein from naïve libraries. By enabling the incorporation of non-peptidic moieties that (1) can serve as cyclization units, (2) provide interactions for binding, and/or (3) tailor pharmacological properties, our head-to-side-chain cyclization strategy provides access to a currently under-explored chemical space for the development of chemical probes and therapeutics.

Bacteriophages as Solid Tumor Theragnostic Agents

Cancer, especially the solid tumor sub-set, poses considerable challenges to modern medicine owing to the unique physiological characteristics and substantial variations in each tumor's microenvironmental niche fingerprints. Though there are many treatment methods available to treat solid tumors, still a considerable loss of life happens, due to the limitation of treatment options and the outcomes of ineffective treatments. Cancer cells evolve with chemo- or radiation-treatment strategies and later show adaptive behavior, leading to failed treatment. These challenges demand tailored and individually apt personalized treatment methods. Bacteriophages (or phages) and phage-based theragnostic vectors are gaining attention in the field of modern cancer medicine, beyond their bactericidal ability. With the invention of the latest techniques to fine-tune phages, such as in the field of genetic engineering, synthetic assembly methods, phage display, and chemical modifications, noteworthy progress in phage vector research for safe cancer application has been realized, including use in pre-clinical studies. Herein, we discuss the distinct fingerprints of solid tumor physiology and the potential for bacteriophage vectors to exploit specific tumor features for improvised tumor theragnostic applications.

Investigation of intestinal transportation of peptide-displaying bacteriophage particles using phage display method

To investigate whether peptide sequences with specific translocation across the gastrointestinal barrier can be identified as drug delivery vehicles, in vivo phage display was conducted. For this purpose, a random library of 12-mer peptides displayed on M13 bacteriophage was orally administered to mice followed by recovery of the phage particles from the blood samples after three consecutive biopanning rounds. The obtained peptide sequences were analyzed using bioinformatics tools and software. The results demonstrated that M13 bacteriophage bearing peptides translocate nonspecifically across the mice intestinal mucosal barrier deduced from random distribution of amino acids in different positions of the identified peptide sequences. The most probable reason for entering the phage particles into systemic circulation after oral administration of the peptide library can be related to the nanoscale nature of their structures which provides a satisfying platform for the purpose of designing nanocarriers in pharmaceutical applications.

Bacteriophages and phage-inspired nanocarriers for targeted delivery of therapeutic cargos

The main goal of drug delivery systems is to target therapeutic cargoes to desired cells and to ensure their efficient uptake. Recently a number of studies have focused on designing bio-inspired nanocarriers, such as bacteriophages, and synthetic carriers based on the bacteriophage structure. Bacteriophages are viruses that specifically recognize their bacterial hosts. They can replicate only inside their host cell and can act as natural gene carriers. Each type of phage has a particular shape, a different capacity for loading cargo, a specific production time, and their own mechanisms of supramolecular assembly, that have enabled them to act as tunable carriers. New phage-based technologies have led to the construction of different peptide libraries, and recognition abilities provided by novel targeting ligands. Phage hybridization with non-organic compounds introduces new properties to phages and could be a suitable strategy for construction of bio-inorganic carriers. In this review we try to cover the major phage species that have been used in drug and gene delivery systems, and the biological application of phages as novel targeting ligands and targeted therapeutics.

Phage Particles as Vaccine Delivery Vehicles: Concepts, Applications and Prospects

The development of new strategies for vaccine delivery for generating protective and long-lasting immune responses has become an expanding field of research. In the last years, it has been recognized that bacteriophages have several potential applications in the biotechnology and medical fields because of their intrinsic advantages, such as ease of manipulation and large-scale production. Over the past two decades, bacteriophages have gained special attention as vehicles for protein/peptide or DNA vaccine delivery. In fact, whole phage particles are used as vaccine delivery vehicles to achieve the aim of enhanced immunization. In this strategy, the carried vaccine is protected from environmental damage by phage particles. In this review, phage-based vaccine categories and their development are presented in detail, with discussion of the potential of phage-based vaccines for protection against microbial diseases and cancer treatment. Also reviewed are some recent advances in the field of phage- based vaccines.

Novel human anti-claudin 1 mAbs inhibit hepatitis C virus infection and may synergize with anti-SRB1 mAb

Hepatitis C virus (HCV) is a major cause of chronic hepatitis and liver carcinoma and new therapies based on novel targets are needed. The tight junction protein claudin 1 (CLDN-1) is essential for HCV cell entry and spread, and anti-CLDN-1 rat and mouse mAbs are safe and effective in preventing and treating HCV infection in a human liver chimeric mouse model. To accelerate translation of these observations into a novel approach to treat HCV infection and disease in humans, we screened a phage display library of human single-chain antibody fragments by using a panel of CLDN-1-positive and -negative cell lines and identified phage specifically binding to CLDN-1. The 12 clones showing the highest levels of binding were converted into human IgG4. Some of these mAbs displayed low-nanomolar affinity, and inhibited infection of human hepatoma Huh7.5 cells by different HCV isolates in a dose-dependent manner. Cross-competition experiments identified six inhibitory mAbs that recognized distinct epitopes. Combination of the human anti-SRB1 mAb C-1671 with these anti-CLDN-1 mAbs could either increase or reduce inhibition of cell culture-derived HCV infection in vitro. These novel human anti-CLDN-1 mAbs are potentially useful to develop a new strategy for anti-HCV therapy and lend support to the combined use of antibodies targeting the HCV receptors CLDN-1 and SRB1, but indicate that care must be taken in selecting the proper combination.

Nanoparticle ligand presentation for targeting solid tumors

Among the many scientific advances to come from the study of nanoscience, the development of ligand-targeted nanoparticles to eliminate solid tumors is predicted to have a major impact on human health. There are many reports describing novel designs and testing of targeted nanoparticles to treat cancer. While the principles of the technology are well demonstrated in controlled lab experiments, there are still many hurdles to overcome for the science to mature into truly efficacious targeted nanoparticles that join the arsenal of agents currently used to treat cancer in humans. One of these hurdles is overcoming unwanted biodistribution to the liver while maximizing delivery to the tumor. This almost certainly requires advances in both nanoparticle stealth technology and targeting. Currently, it continues to be a challenge to control the loading of ligands onto polyethylene glycol (PEG) to achieve maximal targeting. Nanoparticle cellular uptake and subcellular targeting of genes and siRNA also remain a challenge. This review examines the types of ligands that have been most often used to target nanoparticles to solid tumors. As the science matures over the coming decade, careful control over ligand presentation on nanoparticles of precise size, shape, and charge will likely play a major role in achieving success.

Bacteriophages as vehicles for gene delivery into mammalian cells: prospects and problems

INTRODUCTION

The identification of more efficient gene delivery vehicles (GDVs) is essential to fulfill the expectations of clinical gene therapy. Bacteriophages, due to their excellent safety profile, extreme stability under a variety of harsh environmental conditions and the capability for being genetically manipulated, have drawn a flurry of interest to be applied as a newly arisen category of gene delivery platforms.

AREAS COVERED

The incessant evolutionary interaction of bacteriophages with human cells has turned them into a part of our body's natural ecosystem. However, these carriers represent several barriers to gene transduction of mammalian cells. The lack of evolvement of specialized machinery for targeted cellular internalization, endosomal, lysosomal and proteasomal escape, cytoplasmic entry, nuclear localization and intranuclear transcription poses major challenges to the expression of the phage-carried gene. In this review, we describe pros and cons of bacteriophages as GDVs, provide an insight into numerous barriers that bacteriophages face for entry into and subsequent trafficking inside mammalian cells and elaborate on the strategies used to bypass these barriers.

EXPERT OPINION

Tremendous genetic flexibility of bacteriophages to undergo numerous surface modifications through phage display technology has proven to be a turning point in the uncompromising efforts to surmount the limitations of phage-mediated gene expression. The revelatory outcomes of the studies undertaken within the recent years have been promising for phage-mediated gene delivery to move from concept to reality.