Biology subjects

Doyle, B.

Publications and source records attributed to Doyle, B..

6 recordsLinked to original sources

bioRxiv2026

A microproteome screen identifies immunomodulatory bacterial microproteins encoded in expanded gene arrays in Leptotrichia

The human microbiome exerts broad influence in health and disease with associative studies implicating the microbiome in influencing immunity, cancer outcomes, and neurodegeneration. However, the molecular mediators of microbe-host communication remain poorly defined. Bacterial microproteins from the microbiome represent a largely uncharacterized class of potential regulators of host immunity. Here, we utilize functional genomics to interrogate 3,552 microproteins in order to identify novel microbial-immune interactions. We constructed a microproteome library from microbial metagenomic datasets, expressed it in macrophages and assayed for immunomodulatory activity. We identify several bacterial microproteins that drive macrophage M1 polarization. Among the strongest hits are a cluster of structurally related microproteins from Leptotrichia species, which are oral Gram-negative commensals associated with differential cancer outcomes. Genomic analysis reveals that Leptotrichia species encode these putative immunomodulatory microproteins in tandem arrays of up to 44 copies. These genes encode microproteins with varying sequences but conserved predicted structures. In an orthogonal approach, we demonstrate that bacterial expression of Leptotrichia microproteins influences macrophage cell state and function. As a whole, our findings identify novel microbial microproteins with immunomodulatory activity and provide a framework for future discovery of host-microbe interactions that influence human health.

microbiology↗

bioRxiv2026

Differential effects of two common GVHD prophylaxis regimens on the gut microbiome: Results from the BMT CTN 1801 study

Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative treatment for many hematological malignancies, but graft-versus-host disease (GVHD) is a common complication. Low gut microbiome diversity is associated with higher GVHD risk and shorter survival in multiple studies. Recently, the BMT CTN 1703 clinical trial demonstrated superiority of a GVHD-prophylaxis regimen including post-transplant cyclophosphamide (PTCy) compared to the standard prophylaxis (tacrolimus and methotrexate, Tac/MTX) in terms of GVHD-free, relapse-free survival at one year among reduced intensity conditioning allo-HCT recipients. However, the effect of PTCy on the gut microbiome and its association with clinical outcome have not been described. Here, we report on a companion randomized clinical controlled trial (BMT CTN 1801), which collected 2575 longitudinal stool samples from 304 study participants. Samples were obtained up to weekly up to day 84 post allo-HCT and at less frequent intervals thereafter, up to 2 years. Microbiome diversity and absolute microbial load were lower in the PTCy group compared to the Tac/MTX group on days 14-28 post-HCT. However, diversity at the timepoint closest to neutrophil engraftment was not significantly associated with non-relapse mortality after one year or other clinical outcomes, contrary to expectations from previous studies. Microbial domination events, when a single species exceeds 30% relative abundance, were comparable across treatment arms and reflected both pathogen blooms as well as less severe disruptions of the microbial community. Clostridium scindens and secondary bile acid metabolism pathways were less prevalent in the PTCy arm than in the Tac/MTX arm post-HCT, yet presence of secondary bile acid metabolism pathways was associated with a lower risk of chronic GVHD. Given that PTCy was associated with a greater disruption of the microbiome as measured by diversity, absolute microbial abundance, and bile acid metabolism capability, but better clinical outcomes overall, these data suggest that the importance of the microbiome in modulating the host immune systems after allo-HCT is specific to different types of GVHD prophylaxis.

microbiology↗

bioRxiv2025

Replicative selfish genetic elements are driving rapid pathogenic adaptation of Enterococcus faecium

Understanding how healthcare-associated pathogens adapt in clinical environments can inform strategies to reduce their burden. Here, we investigate the hypothesis that insertion sequences (IS), prokaryotic transposable elements, are a dominant mediator of rapid genomic evolution in healthcare-associated pathogens. Among 28,207 publicly available pathogen genomes, we find high copy numbers of the replicative ISL3 family in healthcare-associated Enterococcus faecium, Streptococcus pneumoniae and Staphylococcus aureus. In E. faecium, the ESKAPE pathogen with the highest IS density, we find that ISL3 proliferation has increased in the last 30 years. To enable better identification of structural variants, we long read-sequenced a new, single hospital collection of 282 Enterococcal infection isolates collected over three years. In these samples, we observed extensive, ongoing structural variation of the E. faecium genome, largely mediated by active replicative ISL3 elements. To determine if ISL3 is actively replicating in clinical timescales in its natural, gut microbiome reservoir, we long read-sequenced a collection of 28 longitudinal stool samples from patients undergoing hematopoietic cell transplantation, whose gut microbiomes were dominated by E. faecium. We found up to six structural variants of a given E. faecium strain within a single stool sample. Examining longitudinal samples from one individual in further detail, we find ISL3 elements can replicate and move to specific positions with profound regulatory effects on neighboring gene expression. In particular, we identify an ISL3 element that upon insertion replaces an imperfect -35 promoter sequence at a folT gene locus with a perfect -35 sequence, which leads to substantial upregulation of expression of folT, driving highly effective folate scavenging. As a known folate auxotroph, E. faecium depends on other members of the microbiota or diet to supply folate. Enhanced folate scavenging may enable E. faecium to thrive in the setting of microbiome collapse that is common in HCT and other critically ill patients. Together, ISL3 expansion has enabled E. faecium to rapidly evolve in healthcare settings, and this likely contributes to its metabolic fitness and may strongly influence its ongoing trajectory of genomic evolution.

microbiology↗

bioRxiv2022

Design, development, and preliminary assessment of a novel peripheral intravenous catheter aimed at reducing early failure rates

BackgroundPeripheral intravenous catheters (PIVCs) are the most commonly used invasive medical device, yet despite best efforts by end-users, PIVCs experience unacceptably high early failure rates. We aimed to design a new PIVC that reduces the early failure rate of in-dwelling PIVCs and we conducted preliminary tests to assess its efficacy and safety in a large animal model of intravenous access. MethodsWe used computer-aided design and simulation to create a PIVC with a ramped tip geometry, which directs the infused fluid away from the vein wall; we called the design the FloRamp. We created FloRamp prototypes (test device) and tested them against a market-leading device (BD Insyte; control device) in a highly-controlled setting with five insertion sites per device in four pigs. We measured resistance to infusion and visual infusion phlebitis (VIP) every six hours and terminated the experiment at 48 hours. Veins were harvested for histology and seven pathological markers were assessed. ResultsComputer simulations showed that the optimum FloRamp tip reduced maximum endothelial shear stress by 60%, from 12.7Pa to 5.1Pa, compared to a typical PIVC tip, and improved the infusion dynamics of saline in the blood stream. In the animal study, we found that 2/5 of the control devices were occluded after 24 hours, whereas all test devices remained patent and functional. The FloRamp created less resistance to infusion (0.73{+/-}0.81 vs 0.47{+/-}0.50, p=0.06) and lower VIP scores (0.60{+/-}0.93 vs 0.31{+/-}0.70, p=0.09) that the control device, although neither findings were significantly different. Histopathology revealed that 5/7 of the assessed markers were lower in veins with the FloRamp. ConclusionsAs PIVCs are used in almost every hospitalized patient, there is an urgent need to reduce failure rates. Herein we report preliminary assessment of a novel PIVC design, which could be advantageous in clinical settings through decreased device occlusion.

bioengineering↗

bioRxiv2022

Pyramidal neuron morphogenesis requires a septin network that stabilizes filopodia and suppresses lamellipodia during neurite initiation

Pyramidal neurons are the major cell type of the forebrain, consisting of a pyramidally shaped soma with axonal and apicobasal dendritic processes. It is poorly understood how the neuronal soma morphs from a sphere to pyramid, while generating neurites of the proper shape and orientation. Here, we discovered that the spherical somata of immature neurite-less neurons possess a circumferential wreath-like network of septin filaments, which promotes myosin II localization and suppresses Arp2/3 activity at the base of filopodial actin bundles. The septin network facilitates neurite formation by stabilizing nascent filopodia, which mature to neurites, and concomitantly maintains a consolidated soma by suppressing the extension of lamellipodia. We show that this septin function is critical for the morphogenesis and spatial orientation of pyramidal somata and their neurites in vitro and in vivo. Therefore, the somatic septin cytoskeleton provides a key morphogenetic mechanism for neuritogenesis and the development of pyramidal neurons. Highlights- A septin wreath-like network controls the shape of neuronal somata and nascent neurites - Septins promote and suppress filopodial and lamellipodial protrusions, respectively - Septins scaffold myosin II and exclude Arp2/3 at the base of filopodial actin - Development of pyramidally shaped neurons requires septins in vitro and in vivo eTOC SummaryRadler et al report a new morphogenetic mechanism in the development of pyramidal neurons, which is mediated by a septin wreath-like cytoskeleton in the soma of immature spherical neurons. The septin network stabilizes somatic filopodia and suppresses lamellipodia by differentially controlling the localization of myosin II and Arp2/3.

cell biology↗

bioRxiv2020

Inhibiting cough by silencing large pore-expressing airway sensory neurons with a charged sodium channel blocker

Although multiple diseases of the respiratory system cause cough, there are few effective treatments for this common condition. We previously developed a strategy to treat pain and itch via the long-lasting inhibition of nociceptor sensory neurons with QX-314, a cationic sodium channel blocker that selectively enters only into activated nociceptors by permeating through the endogenous TRPV1 and TRPA1 large pore ion channels they express. In this study we design and characterize BW-031, a novel cationic compound with [~]6-fold greater potency than QX-314 for inhibiting sodium channels when introduced inside cells and with minimal extracellular activity. We show that inhalation of aerosolized BW-031 effectively inhibits citric acid-induced cough in an allergic inflammation guinea pig cough model. These data support the use of charged sodium channel blockers for the selective inhibition of airway sensory neurons with activated large pore channels as a novel targeted therapy for treating cough.

neuroscience↗