Biology subjects

Greenwood, D.

Publications and source records attributed to Greenwood, D..

5 recordsLinked to original sources

bioRxiv2026

GPNMB enables lysosomal adaptation required for myelin clearance and nerve regeneration after peripheral nerve injury

Recovery from peripheral nerve injury involves coordinated axonal and immune repair programs that promote tissue regeneration. However, the mechanisms regulating immune-mediated repair remain incompletely understood. Here, we demonstrate that glycoprotein non-metastatic melanoma protein B (GPNMB) is a key regulator of repair processes following peripheral nerve injury. In a mouse sciatic nerve crush model, loss of Gpnmb impaired functional recovery after injury. MRI and histological analyses revealed persistent myelin debris accumulation, defective debris clearance, and impaired macrophage lysosomal function within injured nerves. Mechanistic studies showed that GPNMB-deficient human iPSC-derived macrophages exhibited impaired lysosomal adaptation, reduced lysosomal fitness, and defective processing of myelin-associated cargo, resulting in inefficient degradation of injury-associated material. These defects were accompanied by impaired acquisition of repair-associated cellular programs. Together, our findings identify GPNMB as a critical regulator of lysosome-dependent repair programs during nerve regeneration and demonstrate that efficient GPNMB-dependent myelin processing is required for functional recovery following peripheral nerve injury.

neuroscience↗

bioRxiv2024

Accurate evaluation of live-virus microneutralisation for SARS-CoV-2 variant JN.1

Emerging SARS-CoV-2 variants require rapid assessments of pathogenicity and evasion of existing immunity to inform policy. A crucial component of these assessments is accurate estimation of serum neutralising antibody titres using cultured live virus isolates. Here, we report our updated culture methods for Omicron sub-variant JN.1 using Caco-2 cells and the subsequent evaluation of neutralising antibody titres (nAbTs) in recipients of BNT162b2-XBB.1.5 monovalent and the Ancestral/BA.5 containing bivalent vaccines. We compared culture of JN.1 in either Vero V1 cells or Caco-2 cells, finding culture in Vero V1 either resulted in low-titre stocks or induced crucial mutations at the Spike furin cleavage site. Using the sequence-clean culture stocks generated in Caco-2 cells, we assessed serum samples from 71 healthy adults eligible for a COVID-19 vaccination given as a 5th dose booster: all participants had detectable nAbs against JN.1 prior to vaccination, with baseline/pre-existing nAbTs between both vaccine groups comparable (p = 0.240). However, nAbTs against JN.1 post-vaccination were 2.6-fold higher for recipients of the monovalent XBB1.5 vaccine than the BA.4/5 bivalent vaccine (p<0.001). Regular re-appraisal of methods involved in the evaluation of new variants is required to ensure robust data are used to underpin crucial severity assessments as variants arise and vaccine strain selection decisions.

microbiology↗

bioRxiv2020

Intracellular localisation of Mycobacterium tuberculosis affects antibiotic efficacy

To be effective, chemotherapy against tuberculosis (TB) must kill the intracellular population of Mycobacterium tuberculosis (Mtb). However, how host cell environments affect antibiotic accumulation and efficacy remains elusive. Pyrazinamide (PZA) is a key antibiotic against TB, yet its behaviour is not fully understood. Here, by using correlative light, electron, and ion microscopy to image PZA at the subcellular level, we investigated how human macrophage environments affect PZA activity. We discovered that PZA accumulates heterogeneously between individual bacteria in multiple host cell environments. Crucially, Mtb phagosomal localisation and acidification increase PZA accumulation and efficacy. By imaging two antibiotics commonly used in combined TB therapy, we showed that bedaquiline (BDQ) significantly enhances PZA accumulation by a host cell mediated mechanism. Thus, intracellular localisation and specific microenvironments affect PZA accumulation and efficacy; explaining the potent in vivo efficacy compared to its modest in vitro activity and the critical contribution to TB combination chemotherapy.

microbiology↗

bioRxiv2020

Correlative Light Electron Ion Microscopy reveal in vivo localisation of bedaquiline in Mycobacterium tuberculosis infected lungs

Correlative light, electron and ion microscopy (CLEIM) offers huge potential to track the intracellular fate of antibiotics, with organelle-level resolution. However, a correlative approach that enables subcellular antibiotic visualisation in pathogen-infected tissue is lacking. Here, we developed CLEIM in tissue (CLEIMiT), and used it to identify the cell-type specific accumulation of an antibiotic in lung lesions of mice infected with Mycobacterium tuberculosis. Using CLEIMiT, we found that the anti-TB drug bedaquiline is localised not only in foamy macrophages in the lungs during infection but also accumulate in polymorphonuclear (PMN) cells.

microbiology↗

bioRxiv2019

Induction of microbial oxidative stress as a new strategy to enhance the enzymatic degradation of organic micropollutants in wastewater

Organic micropollutants (OMPs) are pervasive anthropogenic contaminants of fresh and marine waters with known potential to adversely affect aquatic life (e.g. endocrine disruption). Their ubiquitous environmental occurrence is primarily attributed to wastewater treatment plant discharges following their incomplete removal by common biological treatment processes. This study assesses a new strategy for promoting the degradation of six model OMPs (i.e. sulfamethoxazole, carbamazepine, tylosin, atrazine, naproxen and ibuprofen) by stimulating microbial oxidoreductase production to counter the effects of oxidative stress caused by oxygen perturbation. Microbial cultures from dairy farm wastewater were exposed to a cyclical ON-OFF perturbations of oxygen supply, ranging from 0.16 to 2 cycles per hour (i.e. 2, 1, 0.5, 0.25 and 0.16 cycles/hour), in laboratory bioreactors. The activity and relative abundances of microbial oxidoreductases (such as peroxidases, cytochromes P450) were upregulated by oxygen perturbation. In comparison to controls subjected to constant oxygen levels, OMP concentrations in perturbed cultures decreased by 70{+/-}9% (mean {+/-} SD). A distance-based linear model confirmed strong positive correlations between the relative abundance of the bacterial families, Rhodocyclaceae, Syntrophaceae and Syntrophobacteraceae, and oxygen perturbations. Our results confirm that intentional perturbation of oxygen supply to induce microbial oxidative stress can improve OMP removal efficiencies in wastewater treatment bioreactors.

bioengineering↗