PROJECT SUMMARY
Allergies are the 6th most common cause of chronic illness in the US, but effective treatment options
remain limited. Recently discovered, cell-specific, inhibitory immune receptors, such as sialic acid-binding
immunoglobulin-type lectin (Siglec) receptors, are promising therapeutic targets to suppress these unwanted
immune responses, but have been difficult to target because they specifically bind sialic-acid containing
carbohydrates, or glycans. Using two newly developed tools: a bacterial glycan-building platform for
constructing modifiable Siglec receptor glycan ligands and a glycan-displaying nanogel capable of varying
glycan density, we aim to generate optimized Siglec receptor ligands towards the development of therapeutic
candidates for the treatment of allergy and prevention of anaphylaxis. We will use Siglec 3 (CD33) as a model
to validate this approach since it is expressed on both mast cells and basophils, two cell types implicated in
allergy and anaphylaxis. In the first aim, we will generate a library of chemically modified glycan variants that
are candidate Siglec receptor ligands to assess for high affinity interactions with ELISA. We will then load high
affinity glycan ligands on nanogels at varying densities, apply to sensitized primary human skin-derived mast
cells, and assess metrics of mast cell activity including release of granule components, surface markers, and
cytokine release. In the second aim, we will supplement the field with a new tool for the characterization of
Siglec receptors. Genomic incorporation of glycosylation machinery in engineered Escherichia coli will yield a
stable strain for generating modifiable sialoglycoproteins that are candidate Siglec ligands. Ultimately, using
bacterial glycoengineering, we will develop a customizable platform for generating Siglec receptor ligands that
can be readily ported to other labs and broadly applied for the characterization of other lectins. Once complete,
the proposed aims will not only yield therapeutic candidates capable of high affinity Siglec 3 (CD33) binding,
but also a new approach and tool that can be applied to identify therapeutic candidates for other Siglec
receptors and lectins. This project spans glycobiology, cell biology, nanomaterials, and using allergy models of
disease. As such, it will provide a rich training experience bolstered by research mentors with synergistic
expertise and ample support from Northwestern University, the Center for Synthetic Biology, the Medical
Scientist Training Program, and the Interdisciplinary Biological Sciences Graduate Program. In addition to
providing a robust training experience, this will work will also advance the therapeutic potential of targeting
Siglec receptors for the treatment of allergy and prevention of anaphylaxis, among other relevant diseases.
