Design and generation of new absorption-enabling peptides for oral delivery of biologics

The project aligns with BBSRC's strategic research priority 3, 'Bioscience for Health' (Biotechnology for Health challenge) as it aims to develop basic bioscience underpinning the formulation and validation of biologics that benefit the maintenance and promotion of health. Building on applicants' prior work and benefiting from synergy, multidisciplinarity and Proxima's technologies, the project will develop a new generation of materials for oral delivery of biologics.

Biologics have transformed therapeutics (7 out of 8 top selling drugs in 2014). Their administration is limited to injection due to negligible intestinal absorption. These are less accepted by patients (painful/potential side effects), and expensive to manufacture and administer. Several barriers limit systemic absorption of biologics, but the intestinal epithelium is the most formidable and challenging to overcome. Current approaches to improve oral biologics absorption typically employ 'absorption enhancers' that non-selectively disrupt and increase intestinal permeability, but safety concerns (eg. many surfactants) have hindered clinical translation. Therefore, there is an unmet need in safe and effective technologies for oral delivery of biologics.

Key to safe and effective oral delivery of biologics are materials that 'smuggle' drugs selectively across the intestinal mucosa without disrupting this physiologically important barrier. These can be conjugated to the drug or drug delivery systems (e.g. nanoparticle). This project aims to develop novel transcytosis-enabling materials that promote oral absorption of biologics without disrupting the epithelium. These are peptide-based, designed taking inspiration from a natural macromolecular ligand that readily crosses the intestinal mucosa by transcytosis via its receptor, namely IgG and neonatal Fc receptor (FcRn). Preparation of transcytosis-enabling compounds will be informed by the receptor and ligand binding epitopes of IgG and FcRn.

Vllasaliu previously demonstrated that FcRn shuttles IgG Fc-coated nanoparticles transepithelially. Proxima's discovery platforms will be used to prepare transcytosis-enabling peptide constructs. In Mozaic, prototype peptides are created from micellar nanoparticles bearing combinations of amino acids (AA) on surface. A screening library is constructed and after cell culture testing, most effective combination selected for peptide synthesis. AA choice is informed by sequences in IgG receptor-binding domains. In parallel, Almanac (algorithms derived from data of structural analyses of protein-protein interactions) will be used to infer the structure of ligand-binding peptides based on receptor binding domain sequence. Developing FcRn-binding ligands using two complementary approaches reduces the risk of failure.

Project stages
Yr 1: Student training in project relevant techniques and study of IgG-FcRn sequences
Yr 1&2: Formulation of Mozaic screening libraries and peptides with a suitable fluorophore for quantitation. Purification (HPLC) and characterisation by MS
Yr 3&4: Testing compounds alone and conjugated to a model protein (albumin) for cell uptake and absorption across Caco-2 monolayers (intestinal model). Competition assays testing an FcRn receptor-mediated effect. Uptake mechanisms determined by siRNA inhibition of specific pathways and confocal microscopy (co-localisation studies)
Yr 4: Testing most successful compounds' absorption ex vivo in excised rat intestine