Project Leader: Lori West, University of Alberta
For safe ABO-incompatible (ABOi) organ transplantation there is pressing clinical need for better characterization of ABO antibodies including accurate determination of isotypes and fine specificities. Pre- and post-transplant monitoring currently relies on century-old hemagglutination-based assays that provide limited, imprecise, and unstandardized information, and that cannot discriminate glycan subtype-specificities. These limitations result in missed opportunities to receive ABOi donor organs and unnecessary interventions for antibody removal. The ideal ABO antibody assay would utilize existing clinical laboratory expertise and equipment, allowing rapid high-throughput testing of serum samples. For HLA antibody detection, Luminex™ bead-based methods have become the ‘gold standard’ in transplant histocompatibility laboratories worldwide. Our team developed a Luminex™ single-antigen bead assay for detailed analysis of ABO antibodies. In an international multi-centre proficiency study we provided validation of our assay in healthy controls and demonstrated its potential suitability for clinical use. Here, we propose several studies using our assay to define ABOi transplant risk assessment.
Aim 1. Assess ABO antibodies from three large international ABOi kidney transplant cohorts (and controls) from whom serum samples, hemagglutination assay data, and clinical data have been acquired by our lab through established collaborations. Detection and characterization of IgG and IgM subtype-specific ABO antibodies using the bead-based assay will be compared to
hemagglutination titres and transplant outcomes.
Aim 2. Assess IgG subclass ABO antibodies in transplant patient samples and controls. We will perform assay refinement for discrimination of IgG subclasses, information expected to further improve clinical risk assessment.
Aim 3. Assess hitherto unknown ABH subtype-specificities of commonly available ABO monoclonal antibodies widely used clinically and in research.
Our ABOi transplant studies (Aim 1) will provide detailed characterization of ABO antibodies in direct comparison with hemagglutination data; together with clinical outcomes this will provide new data to inform risk assessment. Understanding when ABOi transplantation is predictably low-risk will offer a path to safe transplantation for patients who linger for years on transplant waitlists, or simply die prior to transplant due to insufficient availability of ABO-compatible donors. Additionally, accurate risk assessment will address the growing and increasingly challenging populations of highly HLA-sensitized patients for whom a low risk ABOi transplant would be lifesaving. The ability to detect various IgG subclasses (Aim 2) may elucidate relationships with clinical outcomes similar to those reported with HLA antibodies, providing additional information for risk assessment. Determination of the ABH glycan subtype-specificities of commercial ABO monoclonal antibodies (Aim 3) will allow appropriate selection for specific applications.
Implementation of bead-based assays for assessment of HLA antibodies has revolutionized organ transplantation globally, increasing our understanding of immune risk and leading to safer transplants, increased utilization of donor organs, and improved outcomes. We anticipate that further refinement and demonstration of the reliability and precision of a similar platform for characterization of ABO antibodies will likewise increase recognition of both risks and opportunities for continued expansion of transplantation to help more patients in need. Our ultimate goal, with assistance from industrial partners, is to develop the bead-based ABO antibody assay for implementation in transplant centres worldwide.
Project Leader: Matthew Macauley, University of Alberta
Alzheimer’s disease (AD) is the most common cause of dementia with no efficient treatment. There is a huge need for targeted research towards discovery and development of therapeutic approaches to protect the aging population against this neurodegenerative disorder. Mounting evidence suggests a critical role for brain-resident immune cells known as microglia in AD pathogenesis. Moreover, genome wide association studies (GWAS) concurrently point at significant connections between immunomodulatory receptors on the surface of microglia and AD susceptibility. One of these receptors connected to AD susceptibly is CD33. Human CD33 (hCD33) is a cell-surface immunoinhibitory receptor that acts as a ‘brake’ to suppress and fine tune other cellular processes. The common CD33 AD risk allele favors expression of the long isoform of human CD33 (hCD33), called hCD33M. The CD33 AD protective allele favors alternative splicing for the short isoform, called hCD33m, which lacks the N-terminal domain of the protein. Recently, our laboratory has made significant advancements in demonstrating that hCD33m is a gain-of-function protein. To fully capture the protective effects of hCD33m, we are studying CD33 splicing. Redirection of CD33 splicing to the short isoform, which is not normally generated in abundance within the majority of people, could be an effective means to both eliminate the detrimental hCD33M protein and upregulate expression of hCD33m. To advance this vision, we are: studying CD33 splicing; examining the function of hCD33m; and assessing CD33 splicing in the context of an AD mouse model. Overall, the goal is to leverage the AD-protective allele of CD33 that is well established based on population genetic studies.
Project Leader: Anthony Rullo, McMaster University
Project Leader: Julianne Gibbs, University of Alberta
With this Strategic Initiative grant, we aim to develop a new class of therapeutic artificial cells that have the ability to synthesize and release therapeutic compounds at targeted locations based on biorecognition events that occur outside the artificial cell. To this end, we combine advanced artificial cell technologies with dynamic DNA-carbohydrate hybrid constructs on the cell surface. These new DNA-carbohydrate decorated artificial cells will be utilized to target cancer cells using disaccharide-modified DNA constructs with tunable density and spacing of the disaccharides. Using these molecules in combination with aptamer constructs modified with monosaccharide activator molecules we will develop a DNA switchable system where biomarker recognition leads to the release of a signaling monosaccharide known to cross the artificial cell membrane and capable of activating protein expression. Success in this project would result in a generalizable platform for generating therapeutic artificial cells amenable to a variety of different sensing steps as well as to the synthesis of a variety of different therapeutic molecules. With this Strategic Initiative we will be poised to be at the forefront of this exciting new class of therapeutic/delivery agents that possess both the advantages of protein- or drug-based therapeutics while circumventing many of the challenges associated with off-target effects.
Project Leader: Ratmir Derda, University of Alberta
This proposal will translate technology termed “Liquid Glycan Array” (LiGA) to enable its commercial manufacturing and application by users in academia and pharmaceutical industry for discovery of glycan:protein interaction that enable development and delivery of therapeutics. This Proposal seeks funding to support distribution of LiGA to the early adopters, stakeholders in pharmaceutical and biotechnology companies to address the needs of the biotechnology industry in the area of delivery of therapeutic payloads to specific cells in living organisms.
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