Publications by authors named "Jacob T Martin"

11 Publications

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Targeting HIV Env immunogens to B cell follicles in nonhuman primates through immune complex or protein nanoparticle formulations.

NPJ Vaccines 2020 Aug 5;5(1):72. Epub 2020 Aug 5.

Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.

Following immunization, high-affinity antibody responses develop within germinal centers (GCs), specialized sites within follicles of the lymph node (LN) where B cells proliferate and undergo somatic hypermutation. Antigen availability within GCs is important, as B cells must acquire and present antigen to follicular helper T cells to drive this process. However, recombinant protein immunogens such as soluble human immunodeficiency virus (HIV) envelope (Env) trimers do not efficiently accumulate in follicles following traditional immunization. Here, we demonstrate two strategies to concentrate HIV Env immunogens in follicles, via the formation of immune complexes (ICs) or by employing self-assembling protein nanoparticles for multivalent display of Env antigens. Using rhesus macaques, we show that within a few days following immunization, free trimers were present in a diffuse pattern in draining LNs, while trimer ICs and Env nanoparticles accumulated in B cell follicles. Whole LN imaging strikingly revealed that ICs and trimer nanoparticles concentrated in as many as 500 follicles in a single LN within two days after immunization. Imaging of LNs collected seven days postimmunization showed that Env nanoparticles persisted on follicular dendritic cells in the light zone of nascent GCs. These findings suggest that the form of antigen administered in vaccination can dramatically impact localization in lymphoid tissues and provides a new rationale for the enhanced immune responses observed following immunization with ICs or nanoparticles.
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http://dx.doi.org/10.1038/s41541-020-00223-1DOI Listing
August 2020

Targeting HIV Env immunogens to B cell follicles in nonhuman primates through immune complex or protein nanoparticle formulations.

NPJ Vaccines 2020 5;5:72. Epub 2020 Aug 5.

Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139 USA.

Following immunization, high-affinity antibody responses develop within germinal centers (GCs), specialized sites within follicles of the lymph node (LN) where B cells proliferate and undergo somatic hypermutation. Antigen availability within GCs is important, as B cells must acquire and present antigen to follicular helper T cells to drive this process. However, recombinant protein immunogens such as soluble human immunodeficiency virus (HIV) envelope (Env) trimers do not efficiently accumulate in follicles following traditional immunization. Here, we demonstrate two strategies to concentrate HIV Env immunogens in follicles, via the formation of immune complexes (ICs) or by employing self-assembling protein nanoparticles for multivalent display of Env antigens. Using rhesus macaques, we show that within a few days following immunization, free trimers were present in a diffuse pattern in draining LNs, while trimer ICs and Env nanoparticles accumulated in B cell follicles. Whole LN imaging strikingly revealed that ICs and trimer nanoparticles concentrated in as many as 500 follicles in a single LN within two days after immunization. Imaging of LNs collected seven days postimmunization showed that Env nanoparticles persisted on follicular dendritic cells in the light zone of nascent GCs. These findings suggest that the form of antigen administered in vaccination can dramatically impact localization in lymphoid tissues and provides a new rationale for the enhanced immune responses observed following immunization with ICs or nanoparticles.
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http://dx.doi.org/10.1038/s41541-020-00223-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7406516PMC
August 2020

Calcium-triggered fusion of lipid membranes is enabled by amphiphilic nanoparticles.

Proc Natl Acad Sci U S A 2020 08 20;117(31):18470-18476. Epub 2020 Jul 20.

Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142;

Lipid membrane fusion is an essential process for a number of critical biological functions. The overall process is thermodynamically favorable but faces multiple kinetic barriers along the way. Inspired by nature's engineered proteins such as SNAP receptor [soluble N-ethylmale-imide-sensitive factor-attachment protein receptor (SNARE)] complexes or viral fusogenic proteins that actively promote the development of membrane proximity, nucleation of a stalk, and triggered expansion of the fusion pore, here we introduce a synthetic fusogen that can modulate membrane fusion and equivalently prime lipid membranes for calcium-triggered fusion. Our fusogen consists of a gold nanoparticle functionalized with an amphiphilic monolayer of alkanethiol ligands that had previously been shown to fuse with lipid bilayers. While previous efforts to develop synthetic fusogens have only replicated the initial steps of the fusion cascade, we use molecular simulations and complementary experimental techniques to demonstrate that these nanoparticles can induce the formation of a lipid stalk and also drive its expansion into a fusion pore upon the addition of excess calcium. These results have important implications in general understanding of stimuli-triggered fusion and the development of synthetic fusogens for biomedical applications.
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http://dx.doi.org/10.1073/pnas.1902597117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7414053PMC
August 2020

Enhancing humoral immunity via sustained-release implantable microneedle patch vaccination.

Proc Natl Acad Sci U S A 2019 08 29;116(33):16473-16478. Epub 2019 Jul 29.

Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139;

Sustained exposure of lymphoid tissues to vaccine antigens promotes humoral immunity, but traditional bolus immunizations lead to rapid antigen clearance. We describe a technology to tailor vaccine kinetics in a needle-free platform translatable to human immunization. Solid pyramidal microneedle (MN) arrays were fabricated with silk fibroin protein tips encapsulating a stabilized HIV envelope trimer immunogen and adjuvant, supported on a dissolving polymer base. Upon brief skin application, vaccine-loaded silk tips are implanted in the epidermis/upper dermis where they release vaccine over a time period determined by the crystallinity of the silk matrix. Following MN immunization in mice, Env trimer was released over 2 wk in the skin, correlating with increased germinal center (GC) B cell responses, a ∼1,300-fold increase in serum IgG titers and a 16-fold increase in bone marrow (BM) plasma cells compared with bolus immunization. Thus, implantable MNs provide a practical means to substantially enhance humoral immunity to subunit vaccines.
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http://dx.doi.org/10.1073/pnas.1902179116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6697788PMC
August 2019

Slow Delivery Immunization Enhances HIV Neutralizing Antibody and Germinal Center Responses via Modulation of Immunodominance.

Cell 2019 05 9;177(5):1153-1171.e28. Epub 2019 May 9.

Division of Vaccine Discovery, La Jolla Institute for Immunology (LJI), La Jolla, CA 92037, USA; Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery (Scripps CHAVI-ID), The Scripps Research Institute, La Jolla, CA 92037, USA; Department of Medicine, University of California, San Diego, La Jolla, CA 92037, USA. Electronic address:

Conventional immunization strategies will likely be insufficient for the development of a broadly neutralizing antibody (bnAb) vaccine for HIV or other difficult pathogens because of the immunological hurdles posed, including B cell immunodominance and germinal center (GC) quantity and quality. We found that two independent methods of slow delivery immunization of rhesus monkeys (RMs) resulted in more robust T follicular helper (T) cell responses and GC B cells with improved Env-binding, tracked by longitudinal fine needle aspirates. Improved GCs correlated with the development of >20-fold higher titers of autologous nAbs. Using a new RM genomic immunoglobulin locus reference, we identified differential IgV gene use between immunization modalities. Ab mapping demonstrated targeting of immunodominant non-neutralizing epitopes by conventional bolus-immunized animals, whereas slow delivery-immunized animals targeted a more diverse set of epitopes. Thus, alternative immunization strategies can enhance nAb development by altering GCs and modulating the immunodominance of non-neutralizing epitopes.
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http://dx.doi.org/10.1016/j.cell.2019.04.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6619430PMC
May 2019

Synthesis of multivalent polymer-aptamer conjugates with enhanced inhibitory potency.

Int J Nanomedicine 2018 7;13:5249-5253. Epub 2018 Sep 7.

School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA,

Purpose: We are interested in designing a modular strategy for creating potent multivalent ligands, which frequently can be used as effective inhibitors of undesired biomolecular interactions. For example, such inhibitors might prevent the self-assembly of bacterial toxins or the attachment of a virus to its host cell receptors.

Methods: We used a biocompatible polyamino acid polymer as a scaffold for grafting multiple copies of an oligonucleotide aptamer (OA). Specifically, the carboxylates on the side chains of polyglutamic acid (PGA) were modified with a thiol-reactive linker, -aminoethyl maleimide (AEM), and thiol-functionalized OAs were attached to the maleimide moieties. The resulting conjugates were tested for their ability to compete with and inhibit the binding of unconjugated monovalent OAs to the target cell receptor.

Results: Multivalent PGA-OA conjugates with low, medium, and high valency were successfully prepared. The varying valency and successful purification to remove unconjugated OAs were confirmed by polyacrylamide gel electrophoresis. The resulting purified conjugates inhibited the binding of unconjugated monovalent OAs, and the measured half maximal inhibitory concentration (IC) values corresponded to a 38-88-fold enhancement of potency on a per-aptamer basis, relative to OA alone.

Conclusion: Multivalent conjugation of OA ligands has potential as a generally useful way to improve the potency of the interaction between the ligand and its target receptor. We have demonstrated this principle with a known OA as a proof of concept as well a synthetic strategy that can be used to synthesize multivalent conjugates of other OAs.
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http://dx.doi.org/10.2147/IJN.S174673DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6136935PMC
October 2018

Potential effect of ultrasound on carbohydrates.

Carbohydr Res 2015 Jun 3;410:15-35. Epub 2015 Apr 3.

School of Chemical Sciences, Central University of Gujarat, Gandhinagar, 382030, India.

The use of ultrasound has emerged as one of the most useful alternative energy sources for the synthesis of carbohydrate-derived biologically and pharmaceutically potential compounds. Spectacular advances have been made in the field of sonication-assisted organic reactions, which are known for producing superior yields, enhanced reactivity of the reactant, improved stereoselectivity, and shortened reaction times. Orthogonal protection-deprotection reactions and/or modification and manipulation of functional groups in carbohydrates are common synthetic steps in carbohydrate chemistry. These reaction steps can be driven by the ultrasonic energy generated by acoustic cavitation via the formation and subsequent collapse of ultrasound-induced bubbles. The ultrasound-assisted synthesis of differently functionalised monosaccharides is useful in a wide variety of applications of carbohydrate chemistry such as the glycosylation of oligosaccharides, one pot domino reactions, thioglycoside syntheses, azidoglycoside syntheses, 1,3-dipolar cycloaddition reactions, and syntheses of natural products. This review article covers ultrasound-mediated reactions on carbohydrates that have been described in the literature since 2000.
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http://dx.doi.org/10.1016/j.carres.2015.02.008DOI Listing
June 2015

Recent advances in engineering polyvalent biological interactions.

Biomacromolecules 2015 Jan 26;16(1):43-55. Epub 2014 Nov 26.

The Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute , Troy, New York 12180, United States.

Polyvalent interactions, where multiple ligands and receptors interact simultaneously, are ubiquitous in nature. Synthetic polyvalent molecules, therefore, have the ability to affect biological processes ranging from protein-ligand binding to cellular signaling. In this review, we discuss recent advances in polyvalent scaffold design and applications. First, we will describe recent developments in the engineering of polyvalent scaffolds based on biomolecules and novel materials. Then, we will illustrate how polyvalent molecules are finding applications as toxin and pathogen inhibitors, targeting molecules, immune response modulators, and cellular effectors.
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http://dx.doi.org/10.1021/bm5014469DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4294584PMC
January 2015

Design of monodisperse and well-defined polypeptide-based polyvalent inhibitors of anthrax toxin.

Angew Chem Int Ed Engl 2014 Jul 6;53(31):8037-40. Epub 2014 Apr 6.

Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (USA).

The design of polyvalent molecules, presenting multiple copies of a specific ligand, represents a promising strategy to inhibit pathogens and toxins. The ability to control independently the valency and the spacing between ligands would be valuable for elucidating structure-activity relationships and for designing potent polyvalent molecules. To that end, we designed monodisperse polypeptide-based polyvalent inhibitors of anthrax toxin in which multiple copies of an inhibitory toxin-binding peptide were separated by flexible peptide linkers. By tuning the valency and linker length, we designed polyvalent inhibitors that were over four orders of magnitude more potent than the corresponding monovalent ligands. This strategy for the rational design of monodisperse polyvalent molecules may not only be broadly applicable for the inhibition of toxins and pathogens, but also for controlling the nanoscale organization of cellular receptors to regulate signaling and the fate of stem cells.
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http://dx.doi.org/10.1002/anie.201400870DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4116455PMC
July 2014

Structure-based design of a heptavalent anthrax toxin inhibitor.

Biomacromolecules 2011 Mar 8;12(3):791-6. Epub 2011 Feb 8.

The Howard P. Isermann Department of Chemical and Biological Engineering, Troy, New York 12180, USA.

The design of polyvalent molecules, consisting of multiple copies of a biospecific ligand attached to a suitable scaffold, represents a promising approach to inhibit pathogens and oligomeric microbial toxins. Despite the increasing interest in structure-based drug design, few polyvalent inhibitors based on this approach have shown efficacy in vivo. Here we demonstrate the structure-based design of potent biospecific heptavalent inhibitors of anthrax lethal toxin. Specifically, we illustrate the ability to design potent polyvalent ligands by matching the pattern of binding sites on the biological target. We used a combination of experimental studies based on mutagenesis and computational docking studies to identify the binding site for an inhibitory peptide on the heptameric subunit of anthrax toxin. We developed an approach based on copper-catalyzed azide-alkyne cycloaddition (click-chemistry) to facilitate the attachment of seven copies of the inhibitory peptide to a β-cyclodextrin core via a polyethylene glycol linker of an appropriate length. The resulting heptavalent inhibitors neutralized anthrax lethal toxin both in vitro and in vivo and showed appreciable stability in serum. Given the inherent biocompatibility of cyclodextrin and polyethylene glycol, these potent well-defined heptavalent inhibitors show considerable promise as anthrax antitoxins.
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http://dx.doi.org/10.1021/bm101396uDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3095510PMC
March 2011