Biology subjects

McHugh, K.

Publications and source records attributed to McHugh, K..

8 recordsLinked to original sources

bioRxiv2025

First evidence for widespread sharing of stereotyped non-signature whistle types by wild dolphins

We have built a unique library of sounds produced by known individual common bottlenose dolphins (Tursiops truncatus), by recording them non-invasively with suction cup hydrophones during brief catch and release health assessments and with digital acoustic tags (DTAGs). We have catalogued the name-like signature whistles (SWs) of most animals in this resident community of 170 dolphins, which has enabled us to begin studying little known "non-signature whistles" (NSW). We have so far identified 22 shared NSW types, of which two, NSWA and NSWB, are known to have been produced by at least 25 and 35 different dolphins respectively. We are studying the functions of shared NSWs with playback experiments to free-swimming dolphins. We provide background on past playback studies and how they have informed our current research; in particular, received level (RL) of playbacks was found to significantly influence strength of response. Varied responses to playbacks reflect the complexity of dolphin communication, and highlight the need for larger sample sizes to be able to correctly interpret NSW functions. However, results so far have provided support for both the referential nature of SW and the affiliative nature of SW copies (SWCs), because a majority of control playbacks of a dolphins own signature whistle (self playbacks) elicited positive responses. NSWA elicited a majority of negative responses, suggesting an alarm-type function, and NSWB elicited varying responses, supporting our suggested function of this whistle type as a "query," produced when something unexpected or unfamiliar is heard. Given that SW and SWC are known to be learned and appear to be referential signals, it is likely that shared, stereotyped NSW are both learned and referential as well, an idea that is supported by the fact that dolphins are flexible, life-long vocal production learners, unlike most other non-human mammals. Our study provides the first evidence in dolphins for a wider repertoire of shared, context-specific signals, which could form the basis for a language-like communication system.

animal behavior and cognition↗

bioRxiv2025

Localized delivery of corticosteroids via in situ modification of gut commensals using a synthetic stem peptide prodrug

Oral colonic drug delivery systems (CDDSs) are oftentimes associated with a short duration of action and poor tissue specificity. To address these challenges, we engineered an oral prodrug that leverages the engraftment and semi-permanence of gut commensals to create a long-acting colonic drug depot. We show that two synthetic stem peptide probes can be stereoselectively incorporated onto the surface of gut bacteria in C57BL/6 mice following oral administration. We then show that a prodrug consisting of budesonide, a corticosteroid with otherwise limiting side effects used to treat ulcerative colitis (UC), conjugated to one of these probes via a hydrolyzable ester is significantly less bioactive and is cleaved over a period of days to weeks in simulated physiological fluids. This prodrug can be integrated into the bacterial peptidoglycan in vitro and be cleaved into free budesonide over time, thereby improving drug localization and potentially rendering it safer for longer-term use. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/632432v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@2fa797org.highwire.dtl.DTLVardef@a3b5e2org.highwire.dtl.DTLVardef@1fa11fdorg.highwire.dtl.DTLVardef@b316c7_HPS_FORMAT_FIGEXP M_FIG C_FIG SIGNIFICANCECorticosteroids are highly effective anti-inflammatory drugs used in the treatment of a variety of conditions. Unfortunately, long-term corticosteroid ingestion can lead to a host of dangerous and undesirable side effects including osteoporosis, glaucoma, and a higher risk of infection, among others. Topical corticosteroids delivered via inhalation (chiefly, budesonide and fluticasone) are the primary long-term treatment modality for chronic asthma symptoms. In contrast to oral corticosteroids, they are considered safer for long-term use when given in moderation because they are directly applied to the airways and exhibit low systemic bioavailability. We sought to apply this successful paradigm to another autoimmune-related disease, ulcerative colitis (UC). We developed a drug delivery system that combines the weakly targeting method of ingestion with a highly specific parameter, microbe prevalence along the gastrointestinal tract, to help improve the specificity and colonic retention of the corticosteroid budesonide, which is currently limited to being used as a short-term treatment for moderate-to-severe UC. Our approach utilizes a largely inert prodrug that can be incorporated into the peptidoglycan of commensal bacteria found at high densities in the colon. After tethering to the bacterial surface via a synthetic stem peptide, the prodrug passively hydrolyzes (cleaves) to release the active, unadulterated form of the drug into the local area, whereas prodrug that traffics elsewhere has a higher chance of being cleared from the body before cleavage. In this manner, we can achieve targeted immunosuppression and sustained release, rendering corticosteroids, and potentially other small molecules, safer for longer term use in treating patients with UC.

bioengineering↗

bioRxiv2024

Novel approaches to label the surface of S. aureus with DBCO for click chemistry-mediated deposition of sensitive cargo

The strain-promoted alkyne-azide cycloaddition (SPAAC) reaction can be used to modify the surface of bacteria for a variety of applications, including drug delivery, biosensing, and imaging. This is usually accomplished by first installing a small azide group within the peptidoglycan and then delivering exogenous cargo (e.g., a protein or nanoparticle) modified with a cyclooctyne group, such as dibenzocyclooctyne (DBCO), for in situ conjugation. However, DBCO is comparatively bulky and hydrophobic, increasing the propensity for some payloads to aggregate. In this study, we sought to invert this paradigm by exploring two novel strategies for incorporating DBCO into the peptidoglycan of Staphylococcus aureus and compared them to an established approach using DBCO-vancomycin. We demonstrate that DBCO-modified small molecules belonging to all three classes - a sortase peptide substrate (LPETG), two D-alanine derivatives, and vancomycin - can selectively label the S. aureus surface to varying degrees. In contrast to DBCO-vancomycin, the DBCO-D-alanine variants do not adversely affect the growth of S. aureus or lead to off-target labeling or toxicity in HEK293T cells, even at high concentrations. Finally, we show that, unlike IgG3-Fc labeled with DBCO groups, IgG3-Fc labeled with azide groups is stable (i.e., remains water-soluble) under normal storage conditions, retains its ability to bind the immune receptor CD64, and can be successfully attached to the surface of DBCO-modified S. aureus. We believe the labeling strategies explored herein will expand the paradigm of specific, nontoxic SPAAC-mediated labeling of the surface of S. aureus and other gram-positive bacteria, opening the door for new applications using azido-modified cargo. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=108 SRC="FIGDIR/small/629304v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@16c7d1corg.highwire.dtl.DTLVardef@189bd12org.highwire.dtl.DTLVardef@1dc1bcborg.highwire.dtl.DTLVardef@1a4e1b2_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2024

Covalent Stabilization of Collagen Mimetic Triple Helices and Assemblies by Dopa Crosslinking

Creating thermally stable collagen mimetic peptides (CMPs) is a persistent challenge. Nature leverages covalent crosslinkings to stabilize collagens signature triple helical tertiary structure and higher-order assemblies. Herein, we demonstrate that crosslinkings between levodopa (Dopa) and lysine, amino acids present in native collagen, can covalently stabilize the triple helix in collagen mimetic peptides. Since alkaline conditions catalyze the oxidation of the catechol on Dopa to a benzoquinone, while being in proximity to the nucleophilic lysine, we hypothesized that this reaction could be a facile method to covalently capture the supramolecular structure of CMPs by simply increasing the pH of the aqueous solvent with the addition of sodium hydroxide. This covalent capture strategy successfully stabilizes CMP homotrimers and a de novo designed ABC-type heterotrimer demonstrating that the Lysine-Dopa covalent bond is best templated by a supramolecular, axial cation-{pi} pairwise interaction. In nature, collagen can hierarchically assemble into fibers. This behavior can be mimicked with the self-assembly of CMPs, but the resulting nanofibers typically exhibit thermal stability below body temperature. In a final application, we demonstrate that Dopa-Lysine covalent capture also enhances the thermal stability of CMP nanofibers well above 37 {degrees}C. This biomimetic covalent capture strategy can stabilize a wide variety of CMP systems and potentially enable the biomedical application of these materials.

biochemistry↗

bioRxiv2024

Development of an improved blood-stage malaria vaccine targeting the essential RH5-CyRPA-RIPR invasion complex

In recent years, reticulocyte-binding protein homologue 5 (RH5) has emerged as a leading blood-stage Plasmodium falciparum malaria vaccine antigen. The most advanced blood-stage vaccine candidate in a Phase 2b clinical trial, RH5.1/Matrix-M, is based on a full-length soluble protein-with-adjuvant formulation. RH5 interacts with cysteine-rich protective antigen (CyRPA) and RH5- interacting protein (RIPR) to form an essential heterotrimeric "RCR-complex". Here, we investigated whether a vaccine candidate based on the ternary RCR-complex could substantially improve upon the leading clinical candidate RH5.1/Matrix-M in preclinical studies. Using a panel of monoclonal antibodies (mAbs) we confirm that parasite growth-inhibitory epitopes on each antigen are exposed on the surface of the RCR-complex and that mAb pairs binding to different antigens can function additively or synergistically to mediate parasite growth inhibition activity (GIA) in vitro. However, immunisation of rats with the RCR-complex consistently fails to outperform RH5.1 alone. We show this is due to immuno-dominance of RIPR coupled with the inferior potency of anti-full length RIPR polyclonal IgG antibodies as compared to the anti-RH5 and anti-CyRPA response. To address this, we identified the growth-inhibitory antibody epitopes of RIPR are clustered within C-terminal EGF-like domains of RIPR. A fusion of these EGF domains to CyRPA, called "R78C", combined with RH5.1, provided a new vaccination strategy that improves upon the levels of in vitro GIA seen with RH5.1 alone. Superiority of the combination antigen vaccine candidate was achieved by the induction of a quantitatively higher, but qualitatively similar, polyclonal antibody response that demonstrated additive GIA across the three antigen targets. These preclinical data justified the advancement of the RH5.1+R78C/Matrix-M combination vaccine to a Phase 1 clinical trial.

immunology↗

bioRxiv2024

Preclinical Development of a Stabilized RH5 Virus-Like Particle Vaccine that Induces Improved Anti-Malarial Antibodies

The development of a highly effective vaccine against the pathogenic blood-stage infection of human malaria will require a delivery platform that can induce an antibody response of both maximal quantity and functional quality. One strategy to achieve this includes presenting antigens to the immune system on virus-like particles (VLPs). Here we sought to improve the design and delivery of the blood-stage Plasmodium falciparum reticulocyte-binding protein homolog 5 (RH5) antigen, which is currently in a Phase 2 clinical trial as a full-length soluble protein-in-adjuvant vaccine candidate called RH5.1/Matrix-M. We identify disordered regions of the full-length RH5 molecule induce non-growth inhibitory antibodies in human vaccinees, and a re-engineered and stabilized immunogen that includes just the alpha-helical core of RH5 induces a qualitatively superior growth-inhibitory antibody response in rats vaccinated with this protein formulated in Matrix-M adjuvant. In parallel, bioconjugation of this new immunogen, termed "RH5.2", to hepatitis B surface antigen VLPs using the "plug-and-display" SpyTag-SpyCatcher platform technology also enabled superior quantitative antibody immunogenicity over soluble antigen/adjuvant in vaccinated mice and rats. These studies identify a new blood-stage malaria vaccine candidate that may improve upon the current leading soluble protein vaccine candidate RH5.1/Matrix-M. The RH5.2-VLP/Matrix-M vaccine candidate is now under evaluation in Phase 1a/b clinical trials.

immunology↗

bioRxiv2023

Natural malaria infection elicits rare but potent neutralizing antibodies to the blood-stage antigen RH5

Plasmodium falciparum RH5 is the most advanced blood-stage malaria vaccine candidate and is under evaluation for efficacy in endemic regions, emphasizing the need to study the underlying antibody response to RH5 during natural infection. Here, we found that RH5-reactive B cells were rare in malaria-exposed individuals despite repeated infections over multiple years. RH5-specific monoclonal antibodies isolated from these individuals were extensively mutated but mostly targeted non-neutralizing epitopes, in contrast to antibodies from RH5-vaccinated, malaria-naive individuals. However, infection-derived MAD8-151 and MAD8-502 were among the most potent neutralizers out of 186 antibodies isolated from both cohorts and target the same epitopes as the most effective vaccine-induced antibodies. Binding to basigin receptor-proximal epitopes was the primary factor governing the potency of RH5-specific antibodies from both natural infection and vaccination, followed by the strength of binding. These results indicate a clear strategy for the development of next-generation RH5 vaccines for use in malaria-endemic regions.

immunology↗

bioRxiv2023

Analysis of the Diverse Antigenic Landscape of the Malaria Invasion Protein RH5 Identifies a Potent Vaccine-Induced Human Public Antibody Clonotype

The highly conserved and essential Plasmodium falciparum reticulocyte-binding protein homolog 5 (PfRH5) has emerged as the leading target for vaccines that seek to protect against the disease-causing blood-stage of malaria. However, the features of the human vaccine-induced antibody response that confer highly potent inhibition of malaria parasite invasion into red blood cells are not well defined. Here we characterize over 200 human IgG monoclonal antibodies induced by the most advanced PfRH5 vaccine. We define the antigenic landscape of this molecule, and establish epitope specificity, antibody association rate and intra-PfRH5 antibody interactions are key determinants of functional anti-parasitic potency. In addition, we identify a germline gene combination that results in an exceptionally potent class of antibody and demonstrate its prophylactic potential to protect against P. falciparum parasite challenge in vivo. This comprehensive dataset provides a framework to guide rational design of next-generation vaccines and prophylactic antibodies to protect against blood-stage malaria.

immunology↗