Exploring How Antibody Format Drives Clearance from the Brain.

Monoclonal antibodies (mAbs) have high binding specificity and affinity, making them attractive for treating brain diseases. However, their effectiveness is limited by poor blood-brain barrier (BBB) penetration and rapid central nervous system (CNS) clearance. Our group identified blood-brain barrier modulator (BBBM) peptides that improved mAb penetration across the BBB into the brain.

Selective Uptake of Macromolecules to the Brain in Microfluidics and Animal Models Using the HAVN1 Peptide as a Blood-Brain Barrier Modulator.

Monoclonal antibodies (mAbs) possess favorable pharmacokinetic properties, high binding specificity and affinity, and minimal off-target effects, making them promising therapeutic agents for central nervous system (CNS) disorders. However, their development as effective therapeutic and diagnostic agents for brain disorders is hindered by their limited ability to efficiently penetrate the blood-brain barrier (BBB). Therefore, it is crucial to develop efficient delivery methods that enhance the penetration of antibodies into the brain.

A Review of Protein- and Peptide-Based Chemical Conjugates: Past, Present, and Future.

Over the past few decades, the complexity of molecular entities being advanced for therapeutic purposes has continued to evolve. A main propellent fueling innovation is the perpetual mandate within the pharmaceutical industry to meet the needs of novel disease areas and/or delivery challenges. As new mechanisms of action are uncovered, and as our understanding of existing mechanisms grows, the properties that are required and/or leveraged to enable therapeutic development continue to expand.

Generation of a Porcine Antibody Fab Fragment Using Protein Engineering to Facilitate the Evaluation of Ocular Sustained Delivery Technology.

Treatment of age-related macular degeneration (AMD) with anti-vascular endothelial growth factor (VEGF) biologic agents has been shown to restore and maintain visual acuity for many patients afflicted with wet AMD. These agents are usually administered via intravitreal injection at a dosing interval of 4-8 weeks. Employment of long-acting delivery (LAD) technologies could improve the therapeutic outcome, ensure timely treatment, and reduce burden on patients, caregivers, and the health care system.

Protein conjugates and fusion proteins as ocular therapeutics.

Long-acting delivery (LAD) of ocular therapeutics has potential to improve the standard of care for ocular diseases, such as age-related macular degeneration (AMD), by increasing patient compliance and reducing overall treatment burden on patients and healthcare providers. Although relatively few ocular LAD technologies are currently on the market, a variety of emergent and novel protein engineering-based technologies are being investigated in both the laboratory and clinical settings. Here, we review some of the key indications and treatments that would benefit from the development of LAD for the treatment of ocular diseases and examine the current state of LAD technologies that leverage protein-engineering approaches as well as nascent technologies with potential for future impact.

Quantitative cumulative biodistribution of antibodies in mice: effect of modulating binding affinity to the neonatal Fc receptor.

The neonatal Fc receptor (FcRn) plays an important and well-known role in antibody recycling in endothelial and hematopoietic cells and thus it influences the systemic pharmacokinetics (PK) of immunoglobulin G (IgG). However, considerably less is known about FcRn's role in the metabolism of IgG within individual tissues after intravenous administration. To elucidate the organ distribution and gain insight into the metabolism of humanized IgG1 antibodies with different binding affinities FcRn, comparative biodistribution studies in normal CD-1 mice were conducted.

Minipig as a potential translatable model for monoclonal antibody pharmacokinetics after intravenous and subcutaneous administration.

Subcutaneous (SC) delivery is a common route of administration for therapeutic monoclonal antibodies (mAbs) with pharmacokinetic (PK)/pharmacodynamic (PD) properties requiring long-term or frequent drug administration. An ideal in vivo preclinical model for predicting human PK following SC administration may be one in which the skin and overall physiological characteristics are similar to that of humans. In this study, the PK properties of a series of therapeutic mAbs following intravenous (IV) and SC administration in Göttingen minipigs were compared with data obtained previously from humans.

Intracellular neutralization of viral infection in polarized epithelial cells by neonatal Fc receptor (FcRn)-mediated IgG transport.

IgG was traditionally thought to neutralize virions by blocking their attachment to or penetration into mucosal epithelial cells, a common site of exposure to viruses. However, we describe an intracellular neutralizing action for an influenza hemagglutinin-specific monoclonal antibody, Y8-10C2 (Y8), which has neutralizing activity only at an acidic pH. When Y8 was applied to the basolateral surface of Madin-Darby canine kidney cells expressing the rat neonatal Fc receptor for IgG (FcRn), it significantly reduced viral replication following apical exposure of the cell monolayer to influenza virus.

Effects of charge on antibody tissue distribution and pharmacokinetics.

Antibody pharmacokinetics and pharmacodynamics are often governed by biological processes such as binding to antigens and other cognate receptors. Emphasis must also be placed, however, on fundamental physicochemical properties that define antibodies as complex macromolecules, including shape, size, hydrophobicity, and charge. Electrostatic interactions between anionic cell membranes and the predominantly positive surface charge of most antibodies can influence blood concentration and tissue disposition kinetics in a manner that is independent of antigen recognition.

Comparison of FcRn- and pIgR-mediated transport in MDCK cells by fluorescence confocal microscopy.

Protein delivery across polarized epithelia is controlled by receptor-mediated transcytosis. Many studies have examined basolateral-to-apical trafficking of polymeric IgA (pIgA) by the polymeric immunoglobulin receptor (pIgR). Less is known about apical-to-basolateral transcytosis, the direction the neonatal Fc receptor (FcRn) transports maternal IgGs across intestinal epithelia.

An intracellular traffic jam: Fc receptor-mediated transport of immunoglobulin G.

Recent advances in imaging techniques along with more powerful in vitro and in vivo models of receptor-mediated ligand transport are facilitating advances in our understanding of how cells efficiently direct receptors and their cargo to target destinations within the cytoplasm and at the plasma membrane. Specifically, light and 3D electron microscopy studies examining the trafficking behavior of the neonatal Fc receptor (FcRn), a transport receptor for immunoglobulin G (IgG), have given us new insights into the dynamic interplay between the structural components of the cytosolic trafficking machinery, its protein regulators, and the receptors it directs to various locations within the cell. These studies build upon previous biochemical characterizations of FcRn transport and are allowing us to begin formulation of a more complete model for the intracellular trafficking of receptor-ligand complexes.

The chicken yolk sac IgY receptor, a mammalian mannose receptor family member, transcytoses IgY across polarized epithelial cells.

In mammals the transfer of passive immunity from mother to young is mediated by the MHC-related receptor FcRn, which transports maternal IgG across epithelial cell barriers. In birds, maternal IgY in egg yolk is transferred across the yolk sac to passively immunize chicks during gestation and early independent life. The chicken yolk sac IgY receptor (FcRY) is the ortholog of the mammalian phospholipase A2 receptor, a mannose receptor family member, rather than an FcRn or MHC homolog.

A freeze substitution fixation-based gold enlarging technique for EM studies of endocytosed Nanogold-labeled molecules.

We have developed methods to locate individual ligands that can be used for electron microscopy studies of dynamic events during endocytosis and subsequent intracellular trafficking. The methods are based on enlargement of 1.4 nm Nanogold attached to an endocytosed ligand.

Ligand valency affects transcytosis, recycling and intracellular trafficking mediated by the neonatal Fc receptor.

The neonatal Fc receptor (FcRn) transports IgG across epithelial cell barriers to provide maternal antibodies to offspring and serves as a protection receptor by rescuing endocytosed IgG and albumin from lysosomal degradation. Here we describe the generation of polarized Madin-Darby canine kidney (MDCK) cells expressing rat FcRn (rFcRn) to investigate the potential requirement for ligand bivalency in FcRn-mediated transport. The rFcRn-MDCK cells bind, internalize and bidirectionally transcytose the bivalent ligands IgG and Fc across polarized cell monolayers.