Date of Award
3-6-2025
Degree Name
Doctor of Philosophy (PhD)
Degree Type
Dissertation
Abstract
Immune processes are central to aspects of human health ranging from wound healing to pathogen recognition, yet even within the field of drug delivery, immunomodulatory therapeutics remain relatively niche. In this work we apply nanoscale peptide, lipid and polymer engineering principles to address present challenges in immunomodulatory therapeutics delivery, particularly in the treatment of non-healing wounds and vaccination against flaviviruses and other pathogens that exhibit antibody dependent enhancement. In both cases, nanoengineered delivery systems allowed us to overcome challenges associated with immune hyperactivation using targeted immune stimuli rather than nonspecific signals. A frequent driver of non-healing wounds is failure of local macrophages to “turn over” from a pro-inflammatory to a pro-proliferative phenotype. Although alginate based wound dressings have many favorable properties for wound healing, they are canonically crosslinked by Ca2+ ions, which can be potently pro-inflammatory if they leach into the extracellular wound environment. By developing two alginate sols, each composed of alginate polymer conjugated to several peptides of one member of a heterodimeric coiled coil pair, we were able to synthesize a self-supporting, self-healing hydrogel by mixing those sols. This coiled coil crosslinked gelinduced significantly lower macrophage driven inflammation than Ca2+ crosslinked alginate gels both in ex vivo culture of mouse peritoneal macrophages and after in vivo intraperitoneal implantation. Flaviviruses and other diseases that exhibit antibody-dependent enhancement are difficult to vaccinate against because immunization with the whole inactivated or attenuated pathogen can generate cross reactive and non-neutralizing antibodies to other pathogens which can make infections with those other pathogens far more lethal. To avoid this outcome, vaccines for such pathogens must contain only specific, highly-immunodominant, poorly-conserved epitopes so as to avoid antibody cross-reactivity. This presents difficulties with adjuvation as isolated peptides or epitopes have generally poor intrinsic immunogenicity. To address this concern, we developed nanocarriers that can localize specifically to plasmacytoid dendritic cells (pDCs), a cell population specialized in production of type-I interferons. To do this we capitalized on the homogenously high expression of CD71, a ubiquitous endocytosing iron transporter, by pDCs. By synthesizing nanoscale liposomes surface coated with poly(ethyleneglycol) and either gambogic acid or T7 as small molecule or peptide noncompetitive CD71 ligands respectively we were able to selectively deliver liposomes to pDCs over other leukocytes both ex vivo and in vivo. Further, we demonstrated that these liposomes effectively home to secondary lymphoid organs after subcutaneous administration and elicit type-I interferon stimulation through and IRF-7 dependent pathway when used to deliver ODN 2216 as a TLR9 agonist. Collectively, these developments contribute to a growing corpus of nanoengineered constructs for immunomodulation and may pave the way for enhanced wound healing technology, treatments for autoimmune disorders, vaccine and drug delivery and treatments for cancer.
Language
English (en)
Chair
Jai Rudra
Committee Members
Deborah Lenschow; Marina Cella; Michael Vahey; Srikanth Singamaneni