Synthetic Approaches to Modulate Immune Responses: Development of Bifunctional Molecules that Target HIV and Related Studies

Chapter 1: This is an introductory chapter that provides a general overview of the immune system and expands into a discussion of synthetic immunology. A focus of this field has been the development of bifunctional small-molecule constructs, called antibody-recruiting molecules (ARMs), which are capable of enhancing antibody binding to disease-relevant cells or viruses, leading to their immune-mediated clearance. This chapter provides conceptual overview of these molecules as well as a discussion of contributions in this area by the Spiegel lab and others.;Chapter 2: Approximately 30 years after its discovery, HIV continues to wreak havoc on a global scale with greater than 25 million deaths, approximately 35 million people worldwide currently infected, roughly 6500 new infections occurring each day, and nearly 1 billion dollars spent on HIV/AIDS research annually. Currently, all HIV therapeutics strategies aim to prevent and control infection, however, no treatment exists which has the capacity to eradicate infection. Immune-mediated clearance and attempts towards therapeutic eradication are thwarted by HIV's manifold evasive measures. In this chapter, we discuss the design, synthesis and biological evaluation of our first generation antibody-recruiting small molecule that targets HIV gp120 (ARM-H), which is designed to aide immune recognition of HIV and template the immune-mediated clearance of infection. ARM-H has the capacity to (1) prevent viral infection by directly inhibiting the CD4-gp120 interaction, and (2) mediate the formation of a ternary complex between HIV-1 gp120 expressing cells and anti-DNP antibodies, resulting in their immune-mediated destruction.;Chapter 3: With the development of our first generation ARM-H, we sought to improve its overall activity by increasing its affinity to gp120. This chapter discusses the use of bifunctional ARM-H's, coupled to rigorous molecular modeling, to elucidate the binding mode of gp120 ligands. In this work, it was discovered that ligands could interact with an accessory binding pocket beneath CD4-binding F43 site through multiple binding orientations. These studies resulted in an ARM-H with a ∼1000-fold increase in anti-HIV activity compared to our first generation ARM-H discussed in Chapter 2. This chapter also discusses preliminary pharmacokinetic studies of ARM-H's.;Chapter 4: Given the success of our antibody recruiting molecules targeting HIV (ARM-Hs), we next sought to expand the general utility of ARM-Hs (and ARMs in general) towards complementary applications. This chapter discusses the development of a scaffold that enables the investigation of the functional relevancy various small molecule antigens. In addition, this chapter reports on our initial explorations of using bifunctional molecules to direct other serological immunomodulators (e.g., C-reactive protein) to HIV gp120 expressing cells. Lastly, this chapter discusses our preliminary investigations toward the use of our gp120-targeting scaffold (i.e. TBT) for other novel strategies; in particular, the delivery of cytotoxic molecules to HIV-infected cells.;Chapter 5: The cell-surface plays a central role in all biological systems, as interactions occurring at cell surfaces mediate tissue formation, enable cell-to-cell or environment-tocell signal transduction, and also contributes to disease pathogenesis. In addition, it is estimated that roughly 20% of the entire human genome codes for proteins that are located on the cell surface. Given these quintessential roles and ubiquity, it is not surprising that the characterization of diseased cell surfaces, and discovery of ligands that recognize them, is of significant therapeutic interest. This chapter discusses preliminary investigations towards a cell-surface profiling, or "cell-fingerprinting" platform that can enable the rapid identification of ligands that bind specifically to the surfaces of diseased over healthy cells. We developed a model system in which RFID-encoded chips covalently labeled with peptidic ligands can differently recognize "diseased cells" over "non-diseased" cells using flow reader technology.