Biology subjects

Osborn, M.

Publications and source records attributed to Osborn, M..

3 recordsLinked to original sources

bioRxiv2023

Integrated histopathology, spatial and single cell transcriptomics resolve cellular drivers of early and late alveolar damage in COVID-19

The most common cause of death due to COVID-19 remains respiratory failure. Yet, our understanding of the precise cellular and molecular changes underlying lung alveolar damage is limited. Here, we integrate single cell transcriptomic data of COVID-19 donor lungs with spatial transcriptomic data stratifying histopathological stages of diffuse alveolar damage (DAD). We identify changes in cellular composition across progressive DAD, including waves of molecularly distinct macrophages and depleted epithelial and endothelial populations throughout different types of tissue damage. Predicted markers of pathological states identify immunoregulatory signatures, including IFN-alpha and metallothionein signatures in early DAD, and fibrosis-related collagens in organised DAD. Furthermore, we predict a fibrinolytic shutdown via endothelial upregulation of SERPINE1/PAI-1. Cell-cell interaction analysis revealed macrophage-derived SPP1/osteopontin signalling as a key regulator during early DAD. These results provide the first comprehensive, spatially resolved atlas of DAD stages, highlighting the cellular mechanisms underlying pro-inflammatory and pro-fibrotic pathways across alveolar damage progression.

pathology↗

bioRxiv2020

The furin cleavage site of SARS-CoV-2 spike protein is a key determinant for transmission due to enhanced replication in airway cells.

SARS-CoV-2 enters cells via its spike glycoprotein which must be cleaved sequentially at the S1/S2, then the S2 cleavage sites (CS) to mediate membrane fusion. SARS-CoV-2 has a unique polybasic insertion at the S1/S2 CS, which we demonstrate can be cleaved by furin. Using lentiviral pseudotypes and a cell-culture adapted SARS-CoV-2 virus with a S1/S2 deletion, we show that the polybasic insertion is selected for in lung cells and primary human airway epithelial cultures but selected against in Vero E6, a cell line used for passaging SARS-CoV-2. We find this selective advantage depends on expression of the cell surface protease, TMPRSS2, that allows virus entry independent of endosomes thus avoiding antiviral IFITM proteins. SARS-CoV-2 virus lacking the S1/S2 furin CS was shed to lower titres from infected ferrets and was not transmitted to cohoused sentinel animals. Thus, the polybasic CS is a key determinant for efficient SARS-CoV-2 transmission.

microbiology↗

bioRxiv2018

Diverse lipid conjugates for functional extra-hepatic siRNA delivery in vivo

RNAi-based therapeutics show promising clinical data for treatment of liver-associated disorders. However, siRNA delivery into extra-hepatic tissues remains an obstacle, limiting the use of siRNA-based therapies. Here we report on a first example of chemical engineering of lipophilic conjugates to enable extra-hepatic delivery. We synthesized a panel of fifteen lipophilic siRNA and evaluated the impact of their chemical configuration on siRNA tissue distribution profile. Generally, lipophilic conjugates allow siRNA distribution to a wide range of tissues, where the degree of lipophilicity defines the ratio of liver/spleen to kidney distribution. In addition to primary clearance tissues, several conjugates achieve significant siRNA distribution to lung, heart, adrenal glands, fat, muscle. siRNA tissue accumulation leads to productive silencing, shown with two independent targets. siRNA concentrations necessary for productive silencing are tissue and conjugate dependent, varying significantly from 5 to 200 ng/mg. The collection of conjugated siRNA described here enables functional gene modulation in vivo in lung, muscle, fat, heart, adrenal glands opening these tissues for future therapeutic intervention.

biochemistry↗