Biology subjects

Ballister, E. R.

Publications and source records attributed to Ballister, E. R..

5 recordsLinked to original sources

bioRxiv2026

NanoPro - a Framework for Probiotically-Guided Nanovector Therapy

The 'antigen problem', i.e. the disconnect between the broad spectrum of therapeutic modes enabled by the range of viral and synthetic nanoparticles for which workable receptor-targeting architectures exist and the relative dearth of addressable target receptors on most tumors, is a long-standing challenge in targeted tumor nanotherapy. Here we provide in vitro-proof-of-principle for NanoPro, a platform for guiding nanoscale therapeutics to otherwise antigenically indistinct tumors via probiotically-released tumor cell-binding tags, ProTags. These consist of an orthogonal antigen (GFP or ALFA) fused to the heparin-binding domain of placenta growth factor-2 and serve as attachment receptors for ProTag-targeted nanovectors. ProTag release from Escherichia coli Nissle 1917 was facilitated by deletion of the membrane-tethering lpp gene, which increased ProTag supernatant concentrations 16.5-fold compared to the parental strain without impacting viability. HBD-dependent decoration with ProTag in bacterial supernatant followed by treatment with receptor-targeted aGFP- or aALFA-lentiviral vectors resulted in majority transduction of MC-38 and MDA-MB-468 tumor cell lines with antigen specificities of 96.5% and 98.5%, respectively, depending on the choice of nanobody. This ProTag-mediated interaction was notably robust, with selective transduction still observed at 625-fold supernatant dilution, warranting further exploration of the utility of the NanoPro system for tumor-restricted delivery of nanotherapeutics.

synthetic biology↗

bioRxiv2024

Tumor-selective treatment of metastatic pancreatic cancer with an engineered, probiotic living drug

Pancreatic ductal adenocarcinoma (PDAC) poses significant challenges for effective treatment, with systemic chemotherapy often proving inadequate due to poor drug delivery and the tumors immunosuppressive microenvironment. Engineered bacteria present a novel approach to target PDAC, leveraging their ability to colonize tumors and deliver therapeutic payloads. Here, we engineered probiotic Escherichia coli Nissle 1917 (EcN) to produce the pore-forming Theta toxin (Nis-Theta) and evaluated its efficacy in a preclinical model of PDAC. Probiotic administration resulted in selective colonization of tumor tissue, leading to improved overall survival compared to standard chemotherapy. Moreover, this strain exhibited cytotoxic effects on both primary and distant tumor lesions while sparing normal tissues. Importantly, treatment also modulated the tumor microenvironment by increasing anti-tumor immune cell populations and reducing immunosuppressive markers. These findings demonstrate the potential of engineered probiotic bacteria as a safe and effective therapeutic approach for PDAC, offering promise for improved patient outcomes.

cancer biology↗

bioRxiv2023

Probiotic neoantigen delivery vectors for precision cancer immunotherapy

Microbial systems have been synthetically engineered to deploy therapeutic payloads in vivo1-4. With emerging evidence that bacteria naturally home to tumors5-7 and modulate anti-tumor immunity8,9, one promising application is the development of bacterial vectors as precision cancer vaccines10-12. In this study, we engineered probiotic E. coli Nissle 1917 (EcN) as an anti-tumor vaccination platform optimized for enhanced production and cytosolic delivery of neoepitope-containing peptide arrays, with increased susceptibility to blood clearance and phagocytosis. These features enhance both safety and immunogenicity, achieving a system which drives potent and specific T cell-mediated anti-cancer immunity that effectively controls or eliminates tumor growth and extends survival in advanced murine primary and metastatic solid tumors. We demonstrate that the elicited anti-tumor immune response involves extensive priming and activation of neoantigen-specific CD4+ and CD8+ T cells, broader activation of both T and NK cells, and a reduction of tumor-infiltrating immunosuppressive myeloid and regulatory T and B cell populations. Taken together, this work leverages the advantages of living medicines to deliver arrays of tumor-specific neoantigen-derived epitopes within the optimal context to induce specific, effective, and durable systemic anti-tumor immunity.

synthetic biology↗

bioRxiv2020

Using a bistable animal opsin for switchable and scalable optogenetic inhibition of neurons

There is no consensus on the best optogenetic tool for neuronal inhibition. Lamprey parapinopsin ( Lamplight) is a Gi/o-coupled bistable animal opsin that can be activated and deactivated by short and long wavelength light, respectively. Since native mechanisms of neuronal inhibition frequently employ Gi/o signalling, we asked here whether Lamplight could be used for optogenetic silencing. We show that short (405nm) and long (525nm) wavelength pulses repeatedly switch Lamplight between stable signalling active and inactive states, and that combining these wavelengths can be used to achieve intermediate levels of activity. We demonstrate that these properties can be applied to produce switchable and scalable neuronal hyperpolarisation, and suppression of spontaneous spike firing in the mouse hypothalamic suprachiasmatic nucleus. We show that expressing Lamplight in (predominantly) ON bipolar cells can photosensitise retinas following advanced photoreceptor degeneration, and that 405 and 525nm stimuli can produce responses of opposite sign in output neurons of the retina. Lamplight-driven responses to both activating (405nm) and deactivating (525nm) light can occur within 500ms and be elicited by intensities at least 10x below threshold for available inhibitory optogenetic tools. We conclude that Lamplight can co-opt endogenous signalling mechanisms to allow optogenetic inhibition that is scalable, sustained and rapidly reversible.

neuroscience↗

bioRxiv2019

Extraocular, rod-like photoreceptors in a flatworm express xenopsin photopigment

Animals detect light using opsin photopigments. One recently classified opsin clade, the xenopsins, found in lophotrochozoans, challenges our views on opsin and photoreceptor evolution. Originally thought to belong to the Gi-coupled ciliary opsins, xenopsins are now understood to have diverged from ciliary opsins in pre-bilaterian times, but little is known about the cells that deploy these proteins, or if they form a photopigment and drive phototransduction. We characterized xenopsin in a flatworm, Maritigrella crozieri, and found that it is expressed in a larval eyespot, and in an abundant extraocular cell type around the adult brain. These distinct cells house hundreds of cilia in an intra-cellular vacuole (a phaosome). Cellular assays show Mc xenopsin forms a photopigment and couples to Gi/o in response to light. These findings reveal a novel photoreceptor cell type and opsin/G-protein couple, and highlight the convergent enclosure of photosensitive cilia in flatworm phaosomes and jawed vertebrate rods.

zoology↗