Biology subjects

Gilbert, R.

Publications and source records attributed to Gilbert, R..

8 recordsLinked to original sources

bioRxiv2026

Epidural Thin Film Implants of Polymerized Curcumin Downregulate Inflammatory Markers and Improve Functional Recovery After Spinal Cord Injury in Mice

Spinal cord injury (SCI) is a notoriously intractable medical problem for which there is no neuroprotective pharmacotherapy, despite four decades of clinical trials on systemically administered small molecules that target plausible injury mechanisms. The shared failure mode of those trials is delivery: oxidative and inflammatory injury evolves locally at the lesion site over days to weeks, a timescale that far exceeds the half-life of systemically administered drugs. Furthermore, systemically administered drugs often cannot be dosed at high enough levels to achieve efficacious concentrations locally at the lesion site, without off-target effects. In this study, we show the first example of a locally implantable drug depot that exerts long-lasting activity at the lesion site. We demonstrate in vivo efficacy of a poly(pro-drug) thin film deployed locally, to address delivery problem in SCI. The films are composed of a copolyester in which curcumin, a potent natural antioxidant, is incorporated as a backbone repeat unit alongside poly(ethylene glycol) sebacate segments. The soft, thin film ([~]100 {micro}m) is employed as an epidural implant that quenches reactive oxygen species on-contact and can sustain activity for over two months, which is orders of magnitude longer than free curcumin (half-life of [~]10 min in buffer). A single epidural P50 film, placed on the exposed dura immediately after a moderate-to-severe T9 contusion in mice, produced a statistically significant improvement in Basso Mouse Scale locomotor recovery at 14 days post-injury, relative to a non-antioxidant control polymer of same architecture. The film preserved myelinated white matter, attenuated reactive gliosis (GFAP, Iba1), and produced coherent downregulation of neuroinflammatory gene-expression programs. These effects were spatially restricted to tissue rostral to the lesion, consistent with on-contact, locally confined polymer activity. Because curcumin is covalently enchained within the polymer itself, rather than blended as a payload in a carrier matrix, release is governed by backbone hydrolysis and the architecture can generalize to other phenolic bioactives, potentially establishing epidural poly(pro-drug) thin films as a mechanistically grounded, surgical platform for sustained local pharmacotherapy of CNS injury.

bioengineering↗

bioRxiv2023

BCG administration promotes the long-term protection afforded by a single-dose intranasal adenovirus-based SARS-CoV-2 vaccine

Despite medical interventions and several approved vaccines, the COVID-19 pandemic is continuing into its third year. Recent publications have explored single-dose intranasal (i.n.) adenovirus-based vaccines as an effective strategy for curbing SARS-CoV-2 in naive animal models. However, the effects of prior immunizations and infections have yet to be considered within these models. Here, we investigate the immunomodulatory effects of Mycobacterium bovis BCG pre-immunization on a subsequent S-protein expressing i.n. Ad vaccination, termed Ad(Spike). We found that Ad(Spike) alone conferred long-term protection from severe SARS-CoV-2 pathology within a mouse model, yet it was unable to limit initial infection 6 months post-vaccination. While i.n. Ad(Spike) retains some protective effect after 6 months, a single administration of BCG-Danish prior to Ad(Spike) vaccination potentiates its ability to control viral replication of the B.1.351 SARS-CoV-2 variant within the respiratory tract. Though BCG-Danish had no effect on the ability of Ad(Spike) to generate and maintain humoral immunity, it promoted the generation of cytotoxic and Th1 responses over suppressive FoxP3+ TREG cells in the lungs of infected mice. These data demonstrate a novel vaccination strategy that may prove useful in limiting future viral pandemics by potentiating the long-term efficacy of next generation mucosal vaccines within the context of the safe and widely distributed BCG vaccine. One sentence summaryBCG enhances anti-SARS-CoV-2 immunity and protection afforded by a novel adenovirus-vectored vaccine.

immunology↗

bioRxiv2022

The role of Staphylococcus agnetis and Staphylococcus hyicus in the pathogenesis of buffalo fly skin lesions in cattle

Buffalo flies (Haematobia irritans exigua) are hematophagous ectoparasites of cattle causing production and welfare impacts in northern Australian herds. Skin lesions associated with buffalo fly infestation and Stephanofilaria nematode infection are manifested as focal dermatitis or ulcerated areas most commonly on the medial canthus of the eye, along the lateral and ventral neck and on the abdomen of cattle. For closely related horn flies (Haematobia irritans irritans), Staphylococcus aureus have been suggested as a contributing factor in the development of lesions. To investigate the potential role of bacterial infection in the pathogenesis of buffalo fly lesions, swabs were taken from lesions and normal skin, and bacteria were also isolated from surface washings of buffalo flies and surface-sterilised homogenized flies. Bacterial identification was conducted by MALDI-TOF, strain typing by rep-PCR and DNA sequencing to determine species similarity and virulence factors. Of 49 bacterial isolates collected from lesions, 37 were identified as Staphylococcus agnetis and 12 as Staphylococcus hyicus, whereas from normal skin four isolates were S. hyicus and one was Staphylococcus sciuri. Of the Staphylococcus isolates isolated from buffalo flies, five were identified as S. agnetis and three as S. hyicus. Fifty percent of the buffalo fly isolates had rep-PCR genotypic patterns identical to the lesion isolates. Genome sequencing of 16 S. agnetis and four S. hyicus isolates revealed closely similar virulence factor profiles, with all isolates possessing exfoliative toxin A and C genes. The findings from this study suggest the involvement of S. agnetis and S. hyicus in buffalo fly lesion pathogenesis. This should be taken into account in the development of effective treatment and control strategies for lesions.

microbiology↗

bioRxiv2021

Structural, functional and computational studies of membrane recognition by Plasmodium Perforin-Like Proteins 1 and 2.

Perforin-like proteins (PLPs) play key roles in the mechanisms associated with parasitic disease caused by apicomplexans such as Plasmodium (malaria) and Toxoplasma. The T. gondii PLP1 (TgPLP1) mediates tachyzoite egress from cells, while the five Plasmodium PLPs carry out various roles in the life cycle of the parasite and with respect to the molecular basis of disease. Here we focus on Plasmodium vivax PLP1 and PLP2 (PvPLP1 and PvPLP2) compared to TgPLP1; PvPLP1 is important for invasion of mammalian hosts by the parasite and establishment of a chronic infection, PvPLP2 is important during the symptomatic blood stage of the parasite life cycle. Determination of the crystal structure of the membrane-binding APC{beta} domain of PvPLP1 reveals notable differences with that of TgPLP1, which are reflected in its inability to bind lipid bilayers in the way that TgPLP1 and PvPLP2 can be shown to. Molecular dynamics simulations combined with site-directed mutagenesis and functional assays allow a dissection of the binding interactions of TgPLP1 and PvPLP2 on lipid bilayers, and reveal a similar tropism for lipids found enriched in the inner leaflet of the mammalian plasma membrane. In addition to this shared mode of membrane binding PvPLP2 displays a secondary synergistic interaction side-on from its principal bilayer interface. This study underlines the substantial differences between the biophysical properties of the APC{beta} domains of Apicomplexan PLPs, which reflect their significant sequence diversity. Such differences will be important factors in determining the cell targeting and membrane-binding activity of the different proteins, in their different developmental roles within parasite life cycles.

biophysics↗

bioRxiv2021

Single-molecule imaging of cholesterol-dependent cytolysin assembly

We exploit single-molecule tracking and optical single channel recording in droplet interface bilayers to resolve the assembly pathway and pore-formation of the archetypical cholesterol-dependent cytolysin nanopore, Perfringolysin O. We follow the stoichiometry and diffusion of Perfringolysin O complexes during assembly with 60 millisecond temporal resolution and 20 nanometre spatial precision. Our results suggest individual nascent complexes can insert into the lipid membrane where they continue active assembly. Overall, these data support a model of stepwise irreversible assembly dominated by monomer addition, but with infrequent assembly from larger partial complexes.

biophysics↗

bioRxiv2020

NASA GeneLab RNA-Seq Consensus Pipeline: Standardized Processing of Short-Read RNA-Seq Data

With the development of transcriptomic technologies, we are able to quantify precise changes in gene expression profiles from astronauts and other organisms exposed to spaceflight. Members of NASA GeneLab and GeneLab-associated analysis working groups (AWGs) have developed a consensus pipeline for analyzing short-read RNA-sequencing data from spaceflight-associated experiments. The pipeline includes quality control, read trimming, mapping, and gene quantification steps, culminating in the detection of differentially expressed genes. This data analysis pipeline and the results of its execution using data submitted to GeneLab are now all publicly available through the GeneLab database. We present here the full details and rationale for the construction of this pipeline in order to promote transparency, reproducibility and reusability of pipeline data, to provide a template for data processing of future spaceflight-relevant datasets, and to encourage cross-analysis of data from other databases with the data available in GeneLab.

bioinformatics↗

bioRxiv2020

Fine Molecular Tuning of Chimeric Antigen Receptors through Hinge Length Optimization

BackgroundChimeric antigen receptor (CAR) technology has revolutionized the treatment of B-cell malignancies and steady progress is being made towards CAR-immunotherapies for solid tumours. Epidermal growth factor family receptors EGFR or HER2 are commonly overexpressed in cancer and represent proven targets for CAR-T therapy; given their expression in healthy tissues it is imperative that any targeting strategy consider the potential for on-target off-tumour toxicity. MethodsHerein, we utilize high-throughput CAR screening to identify novel camelid single-domain antibody CARs (sdCARs) with high EGFR-specific CAR-T response. To optimize antigenic sensitivity of this EGFR-sdCAR, we performed progressive N-terminal truncation of the human CD8 hinge domain used as a spacer in many CAR constructs. Hinge truncation resulted in decreased CAR sensitivity to EGFR and improved selectivity for EGFR-overexpressing cells over EGFR-low target cells or healthy donor derived EGFR-positive fibroblasts. To investigate the molecular mechanism of hinge truncation, we test hinge-truncated scFv-based CARs targeting membrane proximal or membrane distal domains of EGFR-family proteins, HER2 and EGFRvIII. Finally, we proceed to test hinge variant EGFR-sdCAR functionality through in vitro and in vivo assessments in primary T cells derived from multiple donors. ResultsFor CARs targeting membrane-proximal epitopes, hinge truncation by even a single amino acid provided fine control of the antigenic sensitivity, whereas CARs targeting membrane distal domains were not sensitive to even complete hinge domain removal. Hinge-modified EGFR-sdCARs showed consistent and predictable responses in Jurkat-CAR cells and primary human CAR-T cells in vitro and in vivo. ConclusionsOverall, these results indicate that membrane-proximal epitope targeting CARs can be modified through hinge length tuning for programmable antigenic sensitivity and improved tumour selectivity. O_FIG O_LINKSMALLFIG WIDTH=196 HEIGHT=200 SRC="FIGDIR/small/360925v2_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@1f0db64org.highwire.dtl.DTLVardef@1d3ac43org.highwire.dtl.DTLVardef@1d270faorg.highwire.dtl.DTLVardef@f7614f_HPS_FORMAT_FIGEXP M_FIG C_FIG O_LISingle amino acid truncations of CD8-hinge domain provide precise control of CAR antigen sensitivity C_LIO_LITruncated hinge CARs show enhanced selectivity for antigen overexpressing tumour cells and decreased activity towards healthy antigen-expressing cells C_LIO_LIEpitope location is a critical factor in determining hinge sensitivity for a CAR C_LIO_LIHinge tuning can modulate CAR-T antigenic sensivity in vitro and in vivo C_LI

immunology↗

bioRxiv2018

Glucocerebrosidase rescues alpha-synuclein from amyloid formation

Aggregation of the protein -synuclein (Syn) Into amyloid fibrils is associated with Parkinsons disease (PD), a process accelerated by lipids. Recently, the lysosomal protein glucocerebrosidase (GCase) has been identified as a major risk factor in both genetic and sporadic PD. Here, we use solution state NMR to reveal that GCase directly inhibits lipid induced Syn amyloidogenesis. Structurally, we show that the mechanism for this requires competition between lipids and GCase for Syn, binding the N and C termini respectively. The affinity of GCase for the C-terminus of Syn is such that not only does it inhibit lipid induced amyloid formation, but also it destabilizes mature Syn amyloid fibrils. These results reveal a competitive molecular \"tug-of-war\" for Syn termini by GCase and lipid, providing a mechanistic link between the clinically observed links between changes in GCase abundance and Parkinsons disease.

biophysics↗