Anti-PEG antibodies enriched in the protein corona of PEGylated nanocarriers impact the cell uptake

Poly(2-ethyl-2-oxazoline) (POx) as Poly(ethylene glycol) (PEG)-Lipid Substitute for Lipid Nanoparticle Formulations

Polyoxazolines have long been considered as promising alternatives to poly(ethylene glycol) (PEG) due to their comparable properties, in particular regarding their stealth effect toward the immune system. Lipid nanoparticles (LNPs), as utilized, e.g., in the COVID-19 vaccines, contain PEG-lipids. However, alternatives are required because of the "PEG dilemma" recognized by an increase in anti-PEG antibodies in the human population. In this study, poly(2-ethyl-2-oxazoline) (PEtOx)-based lipids with different degrees of polymerization are synthesized and subsequently used to formulate mRNA-loaded LNPs. The effect of polymer chain length on the size, immunoreaction, and transfection efficiency is investigated in detail. In addition, in-depth transfection studies are performed using super-resolution microscopy (SRM) to investigate the uptake mechanism of PEtOx-based LNPs in comparison to PEG-LNPs. These combined approaches are utilized to identify the best performing LNP, being superior to the commercial PEG-lipid used in the Comirnaty formulation.

Strategies for extending the half-life of biotherapeutics: successes and complications

INTRODUCTION

Engineering of the drug half-life in vivo has become an integral part of modern biopharmaceutical development due to the fact that many proteins/peptides with therapeutic potential are quickly cleared by kidney filtration after injection and, thus, circulate only a few hours in humans (or just minutes in mice).

AREAS COVERED

Looking at the growing list of clinically approved biologics that have been modified for prolonged activity, and also the plethora of such drugs under preclinical and clinical development, it is evident that not one solution fits all needs, owing to the vastly different structural features and functional properties of the pharmacologically active entities. This article provides an overview of established half-life extension strategies, as well as of emerging novel concepts for extending the in vivo stability of biologicals, and their pros and cons.

EXPERT OPINION

Beyond the classical and still dominating technologies for improving drug pharmacokinetics and bioavailability, Fc fusion and PEGylation, various innovative approaches that offer advantages in different respects have entered the clinical stage. While the Fc fusion partner may be gradually superseded by engineered albumin-binding domains, chemical PEGylation may be replaced by biodegradable recombinant amino-acid polymers like PASylation, thus also offering a purely biotechnological manufacturing route.

Impact of Pre-existing Anti-polyethylene Glycol Antibodies on the Pharmacokinetics and Efficacy of a COVID-19 mRNA Vaccine (Comirnaty) In Vivo

The presence of anti-polyethylene glycol (anti-PEG) antibodies can hinder the therapeutic efficacy of PEGylated drugs. With the widespread use of a PEGylated coronavirus disease 2019 (COVID-19) messenger RNA vaccine (Comirnaty), the impact of pre-existing anti-PEG antibodies on vaccine potency has become a point of debate. To investigate this, we established mouse models with pre-existing anti-PEG antibodies and divided them into 3 groups: group 1 with anti-PEG immunoglobulin G + immunoglobulin M concentrations of 0.76 to 27.41 μg/ml, group 2 with concentrations of 31.27 to 99.52 μg/ml, and a naïve group with no detectable anti-PEG antibodies. Results indicated that anti-spike antibody concentrations significantly decreased in group 1 and group 2 after the 2nd vaccine dose compared to those in the naïve group. Spearman's rank correlation analysis demonstrated a negative relationship between anti-spike antibody production and anti-PEG antibody levels at both the 2nd and 3rd doses (2nd dose: ρ = -0.5296, P = 0.0031; 3rd dose: ρ = -0.387, P = 0.0381). Additionally, spike protein concentrations were 31.4-fold and 46.6-fold lower in group 1 and group 2, respectively, compared to those in the naïve group at 8 h postvaccination. The concentration of complement C3a in group 2 was significantly higher than that in the naïve group after the 3rd dose. These findings confirm that pre-existing anti-PEG antibodies diminish vaccine efficacy, alter pharmacokinetics, and elevate complement activation. Therefore, detecting pre-existing anti-PEG antibodies is crucial for optimizing vaccine efficacy, ensuring patient safety, and developing improved therapeutic strategies.

Polyoxazolines with Cholesterol Lipid Anchor for Fast Intracellular Delivery

Due to the increasing challenges posed by the growing immunity to poly(ethylene glycol) (PEG), there is growing interest in innovative polymer-based materials as viable alternatives. In this study, the advantages of lipids and polymers are combined to allow efficient and rapid cytoplasmic drug delivery. Specifically, poly(2-methyl-2-oxazoline) is modified with a cholesteryl hemisuccinate group as a lipid anchor (CHEMSPOx). The CHEMSPOx is additionally functionalized with a coumarin group (CHEMSPOx-coumarin). Both polymers self-assembled in water into vesicles of ≈100 nm and are successfully loaded with a hydrophobic model drug. The loaded vesicles reveal high cellular internalization across variant cell lines within 1 h at 37 °C as well as 4 °C, albeit to a lesser extent. A kinetic study confirms the fast internalization within 5 min after the sample's addition. Therefore, different internalization pathways are involved, e.g., active uptake but also nonenergy dependent mechanisms. CHEMSPOx and CHEMSPOx-coumarin further demonstrate excellent cyto-, hemo-, and membrane compatibility, as well as a membrane-protecting effect, which underlines their good safety profile for potential biological intravenous application. Overall, CHEMSPOx, as a lipopolyoxazoline, holds great potential for versatile biological applications such as fast and direct intracellular delivery or cellular lysis protection.

Microparticle and nanoparticle-based influenza vaccines

Influenza infections are a health public problem worldwide every year with the potential to become the next pandemic. Vaccination is the most effective strategy to prevent future influenza outbreaks, however, influenza vaccines need to be reformulated each year to provide protection due to viral antigenic drift and shift. As more efficient influenza vaccines are needed, it is relevant to recapitulate strategies to improve the immunogenicity and broad reactivity of the current vaccines. Here, we review the current approved vaccines in the U.S. market and the platform used for their production. We discuss the different approaches to develop a broadly reactive vaccine as well as reviewing the adjuvant systems that are under study for being potentially included in future influenza vaccine formulations. The main components of the immune system involved in achieving a protective immune response are reviewed and how they participate in the trafficking of particles systemically and in the mucosa. Finally, we describe and classify, according to their physicochemical properties, some of the potential micro and nano-particulate platforms that can be used as delivery systems for parenteral and mucosal vaccinations.

Ethylene oxide graft copolymers reduce the immunogenicity of lipid nanoparticles

Lipid nanoparticle (LNP)/mRNA complexes have great therapeutic potential but their PEG chains can induce the production of anti-PEG antibodies. New LNPs that do not contain PEG are greatly needed. We demonstrate here that poly-glutamic acid-ethylene oxide graft copolymers can replace the PEG on LNPs and outperform PEG-LNPs after chronic administration.

Polyethylene glycol and immunology: aspects of allergic reactions and their mechanisms, as well as ways to prevent them in clinical practice

In modern medical practice, where polyethylene glycol is widely used as a component of various drugs, such as vaccines, chemotherapy drugs, and antibiotics, including vaccines, the issue of allergic reactions to this substance is becoming increasingly important. The purpose of this study is to review and systematise data on various aspects of allergic reactions to polyethylene glycol with the aim of better understanding their pathogenesis, clinical manifestations, diagnostic methods, and possible treatment approaches. The study analysed literature data in modern databases, such as MEDLINE, PubMed, and Scopus, on allergic reactions to polyethylene glycol, using the keywords: "PEG", "polyethylene glycol", "allergy", "side effect". The main aspects of allergy to this substance were highlighted, including mechanisms of development, diagnostic methods, and possible treatment strategies. The analysis found that allergic reactions to polyethylene glycol can manifest in a variety of ways, including anaphylaxis and systemic reactions. A possible role for the immune response has been identified, including the production of IgE and IgM antibodies, complement activation, and accelerated clearance in response to polyethylene glycol, in blood plasma. Data are also provided on how to diagnose an increased risk of an allergic reaction in patients who have previously received drugs with this type of drug transporter and in patients receiving high molecular weight types of polyethylene glycol. The results of this review contribute to a better understanding of allergic reactions to polyethylene glycol and provide information for the development of more effective diagnostic and treatment methods.

Advances in biodistribution of gold nanoparticles: the influence of size, surface charge, and route of administration

To improve the translational and clinical applications of gold nanoparticles (GNPs) in medicine there is a need for better understanding of physicochemical properties of the nanoparticles in relation to the systemic parameters andin-vivoperformance. This review presents the influence of physicochemical properties (surface charges and size) and route of administration on the biodistribution of GNPs. The role of protein corona (PC) (a unique biological identifier) as a barrier to biodistribution of GNPs, and the advances in engineered GNPs towards improving biodistribution are presented. Proteins can easily adsorb on charged (anionic and cationic) functionalized GNPs in circulation and shape the dynamics of their biodistribution. Non-ionic coatings such as PEG experience accelerated blood clearance (ABC) due to immunogenic response. While zwitterionic coatings provide stealth effects to formation of PC on the GNPs. GNPs with sizes less than 50 nm were found to circulate to several organs while the route of administration of the GNPs determines the serum protein that adsorbs on the nanoparticles.

Optimized Enzyme-Linked Immunosorbent Assay for Anti-PEG Antibody Detection in Healthy Donors and Patients Treated with PEGylated Liposomal Doxorubicin

There is considerable interest in quantifying anti-PEG antibodies, given their potential involvement in accelerated clearance, complement activation, neutralization, and acute reactions associated with drug delivery systems. Published and commercially available anti-PEG enzyme-linked immunosorbent assays (ELISAs) differ significantly in terms of reagents and conditions, which could be confusing to users who want to perform in-house measurements. Here, we optimize the ELISA protocol for specific detection of anti-PEG IgG and IgM in sera from healthy donors and in plasma from cancer patients administered with PEGylated liposomal doxorubicin. The criterion of specificity is the ability of free PEG or PEGylated liposomes to inhibit the ELISA signals. We found that coating high-binding plates with monoamine methoxy-PEG5000, as opposed to bovine serum albumin-PEG20000, and blocking with 1% milk, as opposed to albumin or lysozyme, significantly improve the specificity, with over 95% of the signal being blocked by competition. Despite inherent between-assay variability, setting the cutoff value of the optical density at the 80th percentile consistently identified the same subjects. Using the optimized assay, we longitudinally measured levels of anti-PEG IgG/IgM in cancer patients before and after the PEGylated liposomal doxorubicin chemotherapy cycle (1 month apart, three cycles total). Antibody titers did not show any increase but rather a decrease between treatment cycles, and up to 90% of antibodies was bound to the infused drug. This report is a step toward harmonizing anti-PEG assays in human subjects, emphasizing the cost-effectiveness and optimized specificity.

Mass-Spectrometric Identification of Proteins and Pathways Responsible for Fouling on Poly(ethylene glycol) Methacrylate Polymer Brushes

Prevention of fouling from proteins in blood plasma attracts significant efforts, and great progress is made in identifying surface coatings that display antifouling properties. In particular, poly(ethylene glycol) (PEG) is widely used and dense PEG-like cylindrical brushes of poly[oligo(ethylene glycol) methacrylate] (poly(OEGMA)) can drastically reduce blood plasma fouling. Herein, a comprehensive study of the variation of blood plasma fouling on this surface, including the analysis of the composition of protein deposits on poly(OEGMA) coatings after contact with blood plasma from many different donors, is reported. Correlation between the plasma fouling behavior and protein deposit composition points to the activation of the complement system as the main culprit of dramatically increased and accelerated deposition of blood plasma proteins on this type of antifouling coating, specifically through the classical pathway. These findings are consistent with observations on PEGylated drug carriers and highlight the importance of understanding the potential interactions between antifouling coatings and their environment.

T Cell and Natural Killer Cell Membrane-Camouflaged Nanoparticles for Cancer and Viral Therapies

Extensive research has been conducted on the application of nanoparticles in the treatment of cancer and infectious diseases. Due to their exceptional characteristics and flexible structure, they are classified as highly efficient drug delivery systems, ensuring both safety and targeted delivery. Nevertheless, nanoparticles still encounter obstacles, such as biological instability, absence of selectivity, recognition as unfamiliar elements, and quick elimination, which restrict their remedial capacity. To surmount these drawbacks, biomimetic nanotechnology has been developed that utilizes T cell and natural killer (NK) cell membrane-encased nanoparticles as sophisticated methods of administering drugs. These nanoparticles can extend the duration of drug circulation and avoid immune system clearance. During the membrane extraction and coating procedure, the surface proteins of immunological cells are transferred to the biomimetic nanoparticles. Such proteins present on the surface of cells confer several benefits to nanoparticles, including prolonged circulation, enhanced targeting, controlled release, specific cellular contact, and reduced in vivo toxicity. This review focuses on biomimetic nanosystems that are derived from the membranes of T cells and NK cells and their comprehensive extraction procedure, manufacture, and applications in cancer treatment and viral infections. Furthermore, potential applications, prospects, and existing challenges in their medical implementation are highlighted.

Exploring Residue-Level Interactions between the Biofilm-Driving R2ab Protein and Polystyrene Nanoparticles

In biological systems, proteins can bind to nanoparticles to form a "corona" of adsorbed molecules. The nanoparticle corona is of significant interest because it impacts an organism's response to a nanomaterial. Understanding the corona requires knowledge of protein structure, orientation, and dynamics at the surface. A residue-level mapping of protein behavior on nanoparticle surfaces is needed, but this mapping is difficult to obtain with traditional approaches. Here, we have investigated the interaction between R2ab and polystyrene nanoparticles (PSNPs) at the level of individual residues. R2ab is a bacterial surface protein from Staphylococcus epidermidis and is known to interact strongly with polystyrene, leading to biofilm formation. We have used mass spectrometry after lysine methylation and hydrogen-deuterium exchange (HDX) NMR spectroscopy to understand how the R2ab protein interacts with PSNPs of different sizes. Lysine methylation experiments reveal subtle but statistically significant changes in methylation patterns in the presence of PSNPs, indicating altered protein surface accessibility. HDX rates become slower overall in the presence of PSNPs. However, some regions of the R2ab protein exhibit faster than average exchange rates in the presence of PSNPs, while others are slower than the average behavior, suggesting conformational changes upon binding. HDX rates and methylation ratios support a recently proposed "adsorbotope" model for PSNPs, wherein adsorbed proteins consist of unfolded anchor points interspersed with partially structured regions. Our data also highlight the challenges of characterizing complex protein-nanoparticle interactions using these techniques, such as fast exchange rates. While providing insights into how R2ab adsorbs onto PSNP surfaces, this research emphasizes the need for advanced methods to comprehend residue-level interactions in the nanoparticle corona.