Biology subjects

Murphy, L. A.

Publications and source records attributed to Murphy, L. A..

6 recordsLinked to original sources

bioRxiv2026

Mechano-activation of synovial fibroblasts and macrophages during OA progression in the dynamically stiffening synovial microenvironment

ObjectiveDuring osteoarthritis (OA) progression, the synovial membrane undergoes profound structural and compositional remodeling and fibrosis. We sought to elucidate how evolving synovial microenvironmental mechanics during fibrotic remodeling influence cell behavior and drive the progression of synovial pathology. MethodsSkeletally-mature male C57BL/6J mice were subjected to destabilization of the medial meniscus (DMM). To control for surgical confounders, both sham-operated and unoperated mice were included, with evaluation at 4- and 8-weeks. Synovial micromechanics were quantified via atomic force microscopy (AFM). Single-cell RNA sequencing (scRNA-seq), RNA fluorescence in situ hybridization (FISH), and flow cytometry were employed to investigate cellular heterogeneity, spatial organization, and crosstalk within fibrotic and non-fibrotic synovial niches. ResultsProgressive fibrotic remodeling and marked matrix stiffening were observed in DMM-operated synovium but absent in sham- and un-operated controls. While both sham and DMM joints mounted an acute stromal and immune response to surgery, these changes resolved over time in sham conditions but persisted in DMM synovium. During disease progression, distinct functional subsets of synovial fibroblasts and immune cells emerged, with mechanosignalling pathways and distinct immune cell-fibroblast crosstalk robustly activated within DMM-induced fibrotic microenvironments. ConclusionThis study demonstrates the complex cellular dynamics and crosstalk that differentiate the evolution of the pathological synovial response in the fibrotic DMM condition relative to surgical sham controls. Our findings highlight mechanotransduction as a central mechanism driving OA synovial pathogenesis and underscore the utility of the DMM model as a platform to dissect the molecular underpinnings of synovial fibrosis.

bioengineering↗

bioRxiv2026

CD14-deficiency protects against osteoarthritic subchondral bone sclerosis via enhanced osteoclastogenesis following joint injury

Aberrant bone remodeling is a hallmark of osteoarthritis, the most common arthritis affecting over 27 million US adults. Subchondral bone sclerosis, one sign of aberrant bone remodeling observable by routine x-rays, occurs as the trabeculae thicken, leading to increased bone volume. Toll-like receptors, pattern-recognition receptors of the innate immune system, have been implicated in OA pathogenesis, with TLR ligands, receptors, and co-receptors shown to mediate the severity and progression of OA. We have previously shown that CD14-deficiency protects mice against post-traumatic OA, and specifically reduces subchondral sclerosis post-injury. We hypothesized that depletion of CD14 protects against TLR4-dependent inhibition of osteoclastogenesis and therefore increases OC density in the SCB after injury, mitigating aberrant bone deposition in a murine model of OA. To determine how cellular changes correlate with bone structure derangements post-DMM, we performed MicroCT, Tartrate-resistant acid phosphatase staining, and alkaline phosphatase staining. To establish mechanistic changes in cellular signaling, we isolated WT and CD14-deficient osteoclast precursors and subjected them to LPS, an osteoarthritis-relevant TLR ligand, during differentiation. CD14-deficient mice, as well as WT mice treated with an anti-CD14 monoclonal antibody, show protection from post-injury increases in both bone volume fraction and bone mineral density. CD14-deficient mice had an increased osteoclast presence in the SCB two weeks post-injury, potentially protecting them from increases in bone volume and density. In vitro, CD14-deficient OCPs differentiated faster than WT OCPs, due to reduced Type I Interferon (IFN-I) signaling. In the presence of an LPS challenge, CD14-deficient OCPs were protected against LPS and TLR4-mediated inhibition, likely due to decreased MyD88-dependent TLR4 signaling. This work opens up new potential pathways to therapeutically target aberrant bone remodeling in the setting of joint injury and PTOA. Lay SummaryOsteoarthritis is one of the leading causes of disability worldwide. One of the hallmarks is subchondral sclerosis, or thickening of the bone in and around the joint. In this work, we used a mouse model of osteoarthritis to show that decreasing inflammatory signaling, through removal of CD14, protects against subchondral sclerosis, due to an increased presence of osteoclasts, cells that combat bone thickening. Osteoclasts without CD14 differentiate faster than osteoclasts with CD14, due to decreased Type I Interferon, an inflammatory cytokine. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=194 SRC="FIGDIR/small/705094v1_ufig1.gif" ALT="Figure 1"> View larger version (58K): org.highwire.dtl.DTLVardef@176bdd5org.highwire.dtl.DTLVardef@a914bborg.highwire.dtl.DTLVardef@902748org.highwire.dtl.DTLVardef@2f9b2_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2025

CD14 plays a critical role in pain and inflammation across multiple models of post-traumatic osteoarthritis

Inflammation is a primary driver of osteoarthritis (OA), and no therapies exist to halt or delay disease progression or substantially ameliorate the chronic pain, inflammation and disability that are characteristic of disease. Soluble CD14 (sCD14), a co-factor that enhances inflammatory toll-like receptor signaling, is present in synovial fluid in patients with OA and positively associates with joint space narrowing, synovial macrophage content, and pain. In this study, we show that increased sCD14 within human synovial fluid correlates with joint effusion volume and increased knee hyperalgesia. Next, we evaluated CD14 as a potential therapeutic target in three pre-clinical models of post traumatic OA (PTOA), using both genetic deficiency and pharmacologic blockade to modulate its activity. We demonstrate that deficiency or blockade of CD14 results in significant protection from increased evoked pain behaviors and from OA driven mobility impairments (i.e. decreased cage activity) across models that differ in severity, and across male and female cohorts. Using flow cytometry, single cell transcriptomics, and spatial proteomics, we further show that CD14-deficiency drastically influences the local synovial inflammatory landscape post-injury, reducing monocyte and macrophage populations and modulating local fibroblast populations. Targeting CD14 via genetic deficiency or therapeutic blockade revealed no substantial protection, but no worsening, of cartilage degeneration. Ultimately, our results provide strong support that targeting synovial inflammation through blockade of CD14 can safely ameliorate OA pain and disability after a pre-disposing injury. One Sentence SummaryThe study demonstrates the key role of CD14 in pain, mobility loss, and inflammation in PTOA, and demonstrates the therapeutic potential of CD14 blockade for OA pain relief.

immunology↗

bioRxiv2024

Discovery of a novel bandavirus using metagenomic sequencing in a retrospective analysis of an unresolved 2020 mortality event involving black vultures in the northeastern United States.

Investigations of wildlife diseases and mortality events can sometimes lead to inconclusive results due to limitations in diagnostics combined with an ever-increasing number of emerging viruses. The use of tools such as unbiased metagenomic next generation sequencing (mNGS) can facilitate the identification of causative agents where conventional investigation methods fail. We performed a retrospective mNGS analysis on RNA isolated from postmortem samples collected during a black vulture (Coragyps atratus, family: Cathartidae) mortality event that occurred in eastern Pennsylvania and western New Jersey in 2020. We describe the discovery and identification of a novel species of bandavirus (Phenuiviridae family) in case specimens from this die-off, as well as some of the associated pathological findings. The Bandavirus genus comprises tickborne viral species that have been reported across five continents and implicated in outbreaks in a variety of mammalian hosts, including humans, and in avian species making them important potential sources of zoonotic spillover events. Genomic and phylogenetic analysis of the bandavirus detected in this study indicate its closest relative corresponds to Hunter Island virus, a bandavirus previously implicated in albatross mortality events off the coast of Tasmania, Australia. Follow-up PCR testing of samples from additional vultures from the same cohort confirmed that this new bandavirus is the likely cause of death.

genomics↗

bioRxiv2023

Metagenomics for pathogen detection during a wildlife mortality event in songbirds

Mass mortality events in wildlife can be indications of an emerging infectious disease. During the spring and summer of 2021, hundreds of dead passerines were reported across the eastern US. Birds exhibited a range of clinical signs including swollen conjunctiva, ocular discharge, ataxia, and nystagmus. As part of the diagnostic investigation, high-throughput metagenomic next-generation sequencing was performed across three molecular laboratories on samples from affected birds. Many potentially pathogenic microbes were detected, with bacteria comprising the largest proportion; however, no singular agent was consistently identified, with many of the detected microbes also found in unaffected (control) birds, and thus considered to be subclinical infections. Congruent results across laboratories have helped drive further investigation into alternative causes including environmental contaminants and nutritional deficiencies. This work highlights the utility of metagenomic approaches in investigations of emerging diseases and provides a framework for future wildlife mortality events. Article Summary LineThe causative agent of a mass mortality event in passerines remains inconclusive after metagenomic high-throughput sequencing with results prompting further investigation into non-pathogenic causes.

genomics↗

bioRxiv2020

Environmental DNA metabarcoding provides enhanced detection of the European eel Anguilla anguilla and fish community structure in pumped river catchments

The European eel Anguilla anguilla (eel hereafter) is critically endangered and has a catadromous lifecycle, which means adult eels that live in pumped catchments must pass through pumps during their downstream spawning migration. We are currently lacking detailed site-by-site eel distribution information in order to estimate the overall impact of individual pumping stations on eel escapement, and as such lack the data to enable informed prioritisation of pumping station management and targeted mitigation. In this study, we investigated whether environmental DNA (eDNA) metabarcoding can provide increased detection sensitivity for eel and fish community structure in highly regulated pumped catchments, when compared directly to current standard practice fish survey protocols (seine netting/electric fishing). Eels were detected in 14/17 sites (82.4%) using eDNA metabarcoding in contrast to 3/17 (17.6%) using traditional catch methods. Additionally, when using eDNA monitoring species richness was higher in 16/17 sites (94.1%) and site occupancy [≥] traditional methods for 23/26 of the fish species detected (88.5%). While eDNA methods presented significantly higher average species richness and species site occupancy overall, eDNA and Catch methods were positively correlated in terms of species richness and site occupancy. We therefore found that eDNA metabarcoding was a high sensitivity method for detecting eels in pumped catchments, while also increasing the detection of overall fish community structure compared to traditional catch methods. In addition, we highlight how eDNA monitoring is especially suited to increased detection of particular species, with traditional methods sufficient for others. This high sensitivity, coupled with the ability to sample multiple sites in a short time frame suggests eDNA metabarcoding could be an invaluable tool when prioritising pumping station management.

ecology↗