Improving STING Agonist Delivery for Cancer Immunotherapy Using Biodegradable Mesoporous Silica Nanoparticles

Stimulator of interferon genes (STING) activation by intratumoral STING agonist treatment has been recently shown to eradicate tumors in preclinical models of cancer immunotherapy, generating intense research interest and leading to multiple clinical trials. However, there are many challenges associated with STING agonist‐based cancer immunotherapy, including low cellular uptake of STING agonists. Here, biodegradable mesoporous silica nanoparticles (bMSN) with an average size of 80 nm are developed for efficient cellular delivery of STING agonists. STING agonists delivered via bMSN potently activate innate and adaptive immune cells, leading to strong antitumor efficacy and prolonged animal survival in murine models of melanoma. Delivery of immunotherapeutic agents via biodegradable bMSN is a promising approach for improving cancer immunotherapy.Biodegradable mesoporous silica nanoparticles enhance cellular delivery of stimulator of interferon genes (STING) agonists and achieve greater antitumor therapeutic efficacy than free STING agonists in murine models of melanoma. Biodegradable mesoporous silica nanoparticles are a promising platform for cancer immunotherapy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163388/3/adtp202000130_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163388/2/adtp202000130.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163388/1/adtp202000130-sup-0001-SuppMat.pd

Antimicrobial Microwebs of DNA–Histone Inspired from Neutrophil Extracellular Traps

Neutrophil extracellular traps (NETs) are decondensed chromatin networks released by neutrophils that can trap and kill pathogens but can also paradoxically promote biofilms. The mechanism of NET functions remains ambiguous, at least in part, due to their complex and variable compositions. To unravel the antimicrobial performance of NETs, a minimalistic NET‐like synthetic structure, termed “microwebs,” is produced by the sonochemical complexation of DNA and histone. The prepared microwebs have structural similarity to NETs at the nanometer to micrometer dimensions but with well‐defined molecular compositions. Microwebs prepared with different DNA to histone ratios show that microwebs trap pathogenic Escherichia coli in a manner similar to NETs when the zeta potential of the microwebs is positive. The DNA nanofiber networks and the bactericidal histone constituting the microwebs inhibit the growth of E. coli. Moreover, microwebs work synergistically with colistin sulfate, a common and a last‐resort antibiotic, by targeting the cell envelope of pathogenic bacteria. The synthesis of microwebs enables mechanistic studies not possible with NETs, and it opens new possibilities for constructing biomimetic bacterial microenvironments to better understand and predict physiological pathogen responses.Microwebs with bacteria trapping and killing functions are designed to mimic neutrophil extracellular traps—an immune defense weapon to fight against invading pathogens. The composition–structure–function relationship of the synthetic structure is discussed, and the collaborative action between microwebs and antibiotics allows better elimination of pathogenic bacteria, Escherichia coli.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149216/1/adma201807436-sup-0001-S1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149216/2/adma201807436_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149216/3/adma201807436.pd

In Vitro Platforms for the Study and Manipulation of Neutrophil Extracellular Traps

Though only recently discovered, neutrophil extracellular traps (NETs) have rapidly attracted scientific and clinical interest as a potent weapon in the arsenal of innate immunity. These structures, fibers of decondensed nuclear material on which neutrophils localize their vast antimicrobial and proinflammatory stores, are released into sites of inflammation or injury with the presumed aim of constraining and clearing bacteria. It has also been shown, however, that NETs cause substantial harm, contributing to the pathogeneses of autoimmune diseases, cancers, and thrombotic disorders as well as inciting non-specific inflammation and collateral host damage. Thus, NETs as currently understood represent a paradox in which protection seems to be outweighed by detriment. In this light, fundamental questions have arisen surrounding the identity, function, and utility of NETs in vivo. This work describes two novel platforms rationally designed to assist in understanding and contextualizing this paradox. In the first approach, aimed at better understanding NET identity and function, a reductionist in vitro assay framework was iteratively developed to study NETs from the bottom up, beginning first with their DNA-histone fibrous substructure. Precise control of DNA-histone complexation yielded a robust, reproducible, and scalable structure that stood in stark contrast to low-yield and heterogeneous NET preparations. These structures, termed DNA-histone mesostructures (DHMs), mirrored both NET morphology and, to an extent, function. In doing so, DHMs provided a novel assay platform which elucidated the significant role of the isolated NET backbone in common NET-associated phenomena, such as bacterial trapping and immune activation. In addition, it permitted the confirmation and quantification of the role of the peptide LL-37 in altering NET degradation behavior. Beyond these structural studies, DHMs also yielded novel cell-based assays, including efforts to characterize the interaction between NET components and the immune system. Such studies elucidated the key role of DNA-histone synergism in NET-mediated immunostimulation, particularly amplified by the structural inclusion of non-methylated DNA. Additionally, they highlighted the importance of cell-structure proximity and contact in immune cell uptake and activation. In the second approach, aimed at addressing the perceived pathophysiological imbalance mediated by NETs, a nanoparticulate platform was leveraged to modify cell-derived NETs in vitro with the aim of ultimately modifying them in situ. The chosen nanoparticles, hollow nanocapsules composed of polysaccharide, were internalized into neutrophils but avoided immediate NET induction; instead, they primed neutrophils for enhanced NET production only after classical stimulation. NETs produced by nanocapsule-loaded neutrophils displayed colocalization between particles and NET fibers, thereby indicating successful modification of NETs and promise for future therapeutic engineering of these structures. Though distinct in motivation and design, these two platforms demonstrate novel approaches to understanding NETs and have revealed substantial insights about NET identity, function, and utility as described in this work. For both, the simultaneous youth and breadth of the NET field provide a profoundly large and diverse application base. Further studies leveraging both NET-mimicking in vitro assay platforms and NET-modifying nanoparticles will therefore continue to assist in the determination of both foundational and therapeutic NET biology.PHDBiomedical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/153522/1/clouttit_1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/153522/2/clouttit_2.pdfDescription of clouttit_1.pdf : Restricted to UM users only.Description of clouttit_2.pdf : Restricted to UM users only

Biomimetics: Antimicrobial Microwebs of DNA–Histone Inspired from Neutrophil Extracellular Traps (Adv. Mater. 14/2019)

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149239/1/adma201970097.pd

Biomimetics: Antimicrobial Microwebs of DNA–Histone Inspired from Neutrophil Extracellular Traps (Adv. Mater. 14/2019)

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149239/1/adma201970097.pd

Extracellular Trap‐Mimicking DNA‐Histone Mesostructures Synergistically Activate Dendritic Cells

Extracellular traps (ETs), such as neutrophil extracellular traps, are a physical mesh deployed by immune cells to entrap and constrain pathogens. ETs are immunogenic structures composed of DNA, histones, and an array of variable protein and peptide components. While much attention has been paid to the multifaceted function of these structures, mechanistic studies of ETs remain challenging due to their heterogeneity and complexity. Here, a novel DNA‐histone mesostructure (DHM) formed by complexation of DNA and histones into a fibrous mesh is reported. DHMs mirror the DNA‐histone structural frame of ETs and offer a facile platform for cell culture studies. It is shown that DHMs are potent activators of dendritic cells and identify both the methylation state of DHMs and physical interaction between dendritic cells and DHMs as key tuning switches for immune stimulation. Overall, the DHM platform provides a new opportunity to study the role of ETs in immune activation and pathophysiology.A novel DNA‐histone mesostructure (DHM) platform is reported, which mirrors the morphology of extracellular traps (ETs). This platform enables bottom‐up cell‐based assays to determine the role of the DNA‐histone substructure in ET‐associated phenomena. Here, DHMs are used to investigate ET‐mediated immunostimulation.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152974/1/adhm201900926.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152974/2/adhm201900926_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152974/3/adhm201900926-sup-0001-SuppMat.pd