Biological Band-Aids: Design and Application of a Glycosaminoglycan-Peptide Conjugate to Regulate Cell-Cell Interactions During Acute Inflammation
- Dehghani, Tima
- Advisor(s): Panitch, Alyssa
After an acute inflammatory event such as a heart attack, stroke, or organ transplant, blood vessels and circulating immune cells take on a complex phenotype that, if dysregulated, can perpetuate disease. Adverse changes in endothelial phenotype, including glycocalyx shedding and upregulation of immune cell adhesion molecules (i.e., selectins), facilitate the recruitment and adhesion of circulating leukocytes (i.e., neutrophils) and platelets to the vessel walls. In some cases, this otherwise restorative physiological response devolves into a proinflammatory feedback loop; this process is shared among organ systems, enabling disease-agnostic drug discovery. Selectins are an attractive therapeutic target to inhibit the proinflammatory feedback loop; however, their low affinity for monovalent binding ligands and pivotal role in restorative inflammatory mechanisms has created a barrier to drug development. In addition, glycosaminoglycans such as dermatan sulfate (DS) have inherent anti-inflammatory properties that, if localized to a pro-inflammatory environment, can indirectly regulate immune cell adhesion by creating a steric, band-aid-like surface along inflamed endothelial cells. Through the chapters of this dissertation, we introduce a novel selectin-binding glycosaminoglycan-peptide conjugate (DS-IkL) as a molecular “band-aid” to address multiple elements of endothelial dysfunction, including: selectin upregulation, glycocalyx shedding, and aberrant immune cell adhesion and influx. We show that DS-IkL localizes to inflamed vasculature, interferes with selectin-mediated cell complexing, reduces neutrophil extravasation into tissue, and has short- and long-term cardioprotective effects following an acute myocardial infarction. This work details the (i) discovery of a novel selectin-targeting peptide comprised of both L- and D-amino acids and its tunable conjugation to a DS polymer; (ii) functional characterization of DS-IkL’s capacity to curb neutrophil binding, platelet activation, and fibrotic remodeling in in vitro and in vivo models; and (iii) preliminary exploration of the molecule’s ability to interfere with the formation of platelet-neutrophil and platelet-neutrophil-endothelial cell aggregates. Overall, this work serves as a proof-of-concept demonstrating the potential of DS-IkL as a multifunctional anti-inflammatory therapeutic.