Biology subjects

Gross, N.

Publications and source records attributed to Gross, N..

11 recordsLinked to original sources

bioRxiv2025

ERK5 is required for neutrophil-mediated ROS release and essential in epidermolysis bullosa acquisita

Neutrophils are key effector cells in antibody-mediated autoimmune diseases, contributing to inflammation via the release of reactive oxygen species (ROS). Extracellular signal-regulated kinase 5 (ERK5), a member of the MAPK family, is expressed in neutrophils but its role in autoimmune disease pathogenesis remains unclear. We investigated the functional relevance of ERK5 in antibody-mediated autoimmune diseases by comparing neutrophil-dependent (epidermolysis bullosa acquisita, EBA; serum transfer arthritis, STA) and neutrophil-independent (immune thrombocytopenia, ITP) murine models using the small-molecule ERK5 inhibitor XMD8-92. In vitro, pharmacological ERK5 inhibition specifically reduced neutrophil ROS release and CD62L shedding without affecting adhesion, chemotaxis, or CD18 expression. No major effects on viability were observed. In vivo, ERK5 inhibition with XMD8-92 significantly ameliorated antibody transfer-induced EBA, supporting a critical role of neutrophil-derived ROS in disease pathogenesis. In STA and ITP, ERK5 inhibition did not affect clinical outcomes. Together, these findings highlight ERK5 as a regulator of neutrophil ROS release and a potential therapeutic target in ROS-driven autoimmune diseases such as EBA.

immunology↗

bioRxiv2025

CD19xCD3 bispecific T cell engager treatment induces remission in experimental pemphigoid disease

Pemphigoid diseases (PDs) are autoimmune disorders marked by autoantibodies (Aab) against skin and mucous membrane proteins, causing muco-cutaneous blistering in predominantly elderly patients. Since current therapeutics are often insufficient, PDs impose a significant morbidity and mortality burden. CD19xCD3 bispecific T cell engagers (TCEs) - originally developed for B cell malignancies - have shown promise in treatment-refractory autoimmune diseases like systemic sclerosis and rheumatoid arthritis. To explore their potential in PDs, we tested a murine CD19xCD3 TCE in a mouse model of epidermolysis bullosa acquisita (EBA), a prototypical PD. The TCE selectively depleted B cells in blood and bone marrow, but not spleen, of healthy mice. Mice with clinically manifest immunization-induced EBA were randomized to receive either the CD19xCD3 TCE or control treatment upon reaching a predefined disease severity. After 13 weeks, 45% of TCE-treated mice achieved remission, versus 23% of controls. This improvement correlated with reduced antigen-specific B cells, though total and antigen-specific IgG levels were unchanged. These findings suggest that CD19xCD3 TCE preferentially target autoreactive B cells and may be effective at lower doses than those used in oncology. Our data support the potential of CD19xCD3 bispecific T cell engagers as a therapeutic strategy for PDs. eTOC SynopsisGross, Jochimsen, Drager and colleagues demonstrate that CD19xCD3 bispecific T cell engagers, can selectively target autoreactive B cells and induce remission in a mouse model of pemphigoid disease, highlighting their potential as a novel therapeutic strategy for autoimmune blistering disorders.

immunology↗

bioRxiv2024

Characterization of antibiotic resistance development of E. coli in synthetic and real wastewater

Antimicrobial resistance (AMR) is a major threat to global health and resistant bacterial populations have been observed to develop and spread in and around wastewater. However, in vitro studies on AMR development are typically conducted in ideal media conditions which can differ in composition and nutrient density from wastewater. In this study, we compare the growth and AMR development of E. coli in standard LB broth to a synthetic wastewater recipe and autoclaved wastewater samples from the Massachusetts Water Resources Authority (MWRA). We found that synthetic wastewater and real wastewater samples both supported less bacterial growth compared to LB. Additionally, bacteria grown in synthetic wastewater and real wastewater samples had differing susceptibility to antibiotic pressure from Doxycycline, Ciprofloxacin, and Streptomycin. However, AMR development over time during continuous passaging under subinhibitory antibiotic pressure was similar in fold change across all media types. Thus, we find that while LB can act as a proxy for wastewater for AMR studies in E. coli, synthetic wastewater is a more accurate predictor of both E.coli growth and antibiotic resistance development. Moreover, we also show that antibiotic resistance can develop in real wastewater samples and components within wastewater likely have synergistic and antagonistic interactions with antibiotics. ImportanceAntimicrobial resistance (AMR) ranks among the leading global threats to public health and development. In 2019, bacterial AMR was estimated to have directly caused 1.27 million deaths worldwide and contributed to 4.95 million deaths overall (Murray, C. J., et al., (2022). Global burden of bacterial antimicrobial resistance in 2019: a systematic analysis. The Lancet, 399(10325), 629-655.). With estimations of AMR only getting worse, it is imperative that we understand the complex dimensionalities that drive the genesis of antimicrobial resistance to where it begins-the environment. The paper investigates bacterial growth and AMR in real wastewater samples and highlights the importance of using a media that closely mimics real wastewater in AMR studies, compared to standard lab media like LB broth. This is crucial for understanding how E. coli and other bacteria develop AMR in environments similar to actual wastewater, which can inform more effective strategies to combat AMR in natural and engineered settings.

microbiology↗

bioRxiv2024

Microplastics as a novel substrate for antimicrobial resistance: Effects of concentration, composition, and size on E. coli multidrug resistance

Microplastics (MPs) have emerged as a significant environmental pollutant with profound implications for public health, particularly as substrates to facilitate bacterial antimicrobial resistance (AMR). Recently, studies have shown that MPs may accommodate microbial communities, chemical contaminants and genetic material containing AMR genes. This study investigated the effects of MP concentration, composition, and size on the development of multidrug resistance in Escherichia coli. Specifically, we exposed E. coli to varying concentrations of different MP types, including polyethylene (PE), polystyrene (PS), and polypropylene (PP), across a range of sizes (3-10 {micro}m, 10-50 {micro}m, and 500 {micro}m). Results indicated a direct correlation between MP presence and elevated multidrug-resistant (MDR) in E. coli. Notably, MPs exhibited a higher propensity for facilitating resistance than control substrates such as glass, likely due to their hydrophobicity, greater adsorption capacities, and surface chemistries. Furthermore, we observed that co-culture with MPs resulted in biofilm formation. Notably, we found that the bacteria from passaged MPs formed stronger biofilms once the MPs were removed, associated with changes in motility. Thus, we find that MPs also select for cells that are better at forming biofilms, which can lead to recalcitrant infections in the environment and healthcare setting. Our study highlights the immediate need for comprehensive environmental management strategies to mitigate the risk posed by MPs. ImportanceAntimicrobial resistance is one of the worlds most pressing global health crises, with an estimated 10 million deaths per year forecasted by 2050. With the pipeline of antibiotics running dry, it is imperative that mitigation strategies understand the mechanisms that drive the genesis of antimicrobial resistance. One emerging dimension of antimicrobial resistance is the environment. This study highlights the relationship between a widespread environmental pollutant, (MPs), and the rise of drug-resistant bacteria. While it is known that MPs facilitate resistance through several modes (biofilm formation, plastic adsorption rates, etc.), this study fills the knowledge gap on how different types of MPs are contributing to antimicrobial resistance.

microbiology↗

bioRxiv2024

Lossless Single-Molecule Counting To Absolute QuantifyProteoforms

A novel immunoassay, termed Protein Interaction Coupling (PICO), is introduced to deliver unequivocal, reference-free quantification of proteoforms - absolute quantification. PICO employs a compartmentalized, homogeneous single-molecule assay with a lossless and highly sensitive signal generation, capable of detecting down to a few molecules per reaction. Additionally, it utilises a background-free, digital enumeration principle, known as the decouplexing. PICO is presented as exact mathematical theories, providing a theoretical comprehension of its chemistry. Consequently, PICO demonstrates absolute quantification, as exemplified with recombinant and non-recombinant ErbB2 and multi-tagged peptide rTRX targets, validating absolute quantification against internal and external references in both analytical and cellular matrices. Furthermore, PICO enables combinatorial multiplexing (cplex), a readout between any two antibodies, demonstrated by an 8-plex antibody, 12-cplex PICO, measuring functional changes of ErbB pathway upon mock and dactolisib treatment delivering absolute quantitative cellular stoichiometry. PICO possesses immense potential for versatile, standardized, and accurate protein measurements, offering insights into physiological and perturbed cellular processes.

molecular biology↗

bioRxiv2023

Impact of Zinc Pre-exposure on de novo Antibiotic Resistance Development

Antimicrobial resistance (AMR) is a global health crisis that is currently predicted to worsen. While the impact of improper antibiotics is an established driver, much less is known on the impacts of metal supplements. Here, we specifically probe the impact of zinc (Zn) on AMR. In conflict settings where diarrhea disease cases are high, Zn is both given as a supplement for treatment of these diseases prior to use of antibiotics such as ciprofloxacin and is associated with weapons of war. In this study, we find that the order with which E. coli is exposed to zinc impacts resistance development, with increasing pre-exposure time leading to accelerated ciprofloxacin resistance, while combined exposure of zinc with ciprofloxacin delays ciprofloxacin resistance. We did not find evidence that zinc pre-exposure leads to genetic changes or change in antibiotic tolerance, though it does increase both the lag phase and doubling time of E. coli, suggesting the mechanism may be due to changes in gene expression. While the zinc phenotype behavior is not permeant and would no longer be observed if ciprofloxacin exposure did not occur right after zinc pre-exposure, the elevated MIC phenotype resulting from the zinc pre-exposure was more stable than the zinc phenotype. These results are important as they highlight the need to reexamine the clinical role of zinc in treating diarrheal diseases and assess if changes in resistance development observed in vitro are also observed in vivo. ImportanceAntimicrobial resistance (AMR) is a global problem. According to a 2014 Review on Antimicrobial Resistance, it is projected to result in several million deaths by 2050 (Review on Antimicrobial Resistance, Tackling a Crisis for the Health and Wealth of Nations, 2014). While the improper usage of antibiotic treatments is an accepted driver of AMR, little work has focused on how non-antibiotic medication, such as supplements, might impact this when combined with antibiotics. One supplement of interest is the heavy metal zinc which is used in conjunction with ciprofloxacin to treat diarrheal diseases in children. We find that the order and duration of zinc exposure has significant impact on resistance development. More specifically, although the combined presence of zinc and ciprofloxacin delays the onset of resistance, when used successively as they often are in practice, zinc pre-exposure followed by ciprofloxacin exposure results in faster resistance development.

microbiology↗

bioRxiv2022

Remorin proteins serve as membrane topology scaffolds in plants

Organization of membrane topologies in plants has so far been mainly attributed to the cell wall and the cytoskeleton. Taking rhizobial infections of legume root cells, where plasma membranes undergo dynamic and large-scale topology changes, as an initial model, we challenged this paradigm and tested whether additional scaffolds such as plant-specific remorins that accumulate on highly curved and often wall-less plasma membrane domains, control local membrane dynamics. Indeed, loss-of-function mutants of the remorin protein SYMREM1 failed to develop stabilized membrane tubes as found in colonized cells in wild-type plants, but released empty membrane spheres instead. Expression of this and other remorins in wall-less protoplasts allowed engineering different membrane topologies ranging from membrane blebs to long membrane tubes. Reciprocally, mechanically induced membrane indentations were equally stabilized by SYMREM1. This function is likely supported by remorin oligomerization into antiparallel dimers and the formation of higher order membrane scaffolding structures. Taken together we describe an evolutionary confined mechanism that allows the stabilization of large-scale membrane conformations and curvatures in plants. One-sentence summaryThe remorin SYMREM1 evolved as structural membrane scaffold that stabilizes membrane tubulation and curvature during symbiotic intracellular infections.

plant biology↗

bioRxiv2021

Functional traits of carabid beetles reveal seasonal variation in community assembly in annual crops

O_LITrait-based community assembly studies have mostly been addressed along spatial gradients, and do not consider explicitly a fundamental dimension governing community assembly, the time. Nevertheless, such consideration seems particularly necessary in systems in which organisms have to face regular disturbances and rapid changes in vegetation phenology, such as in intensively managed farmlands. C_LIO_LIIn this study, we aimed at understanding how the functional diversity of carabid beetle communities varied across the growing season in response to crop type. We tested three alternative hypotheses on mechanisms underlying the community assembly. C_LIO_LIWe used data from a long-term monitoring conducted over nine years in an intensively-managed farmland in central western France, in a total of 625 fields. First, we measured morphological traits related to body size, dispersal mode, and resource acquisition on the 13 dominant carabid species (> 85 % of all trapped individuals) and identified three independent dimensions of functional specialization within our species pool along axes of a PCA and highlighted key traits for community assembly. Second, we evaluated the community assembly temporal dynamics and the impact of habitat filtering and niche differentiation in the different crop types with time, using linear mixed-effects models. C_LIO_LIWe showed that functional species assembly of carabid beetle communities occurring in crop fields varies importantly intra-annually, with strong variations in these dynamics depending on crop type and crop phenology. Each crop acted as a filter on carabid communities for body size and resource-acquisition traits, and functional differentiation between crops increased with time. We did not find any evidence of habitat filtering on traits related to dispersal mode. C_LIO_LIOur results emphasize the major role of crop phenology but also disturbances involved by agricultural practices such as crop harvesting on changes in community assembly, likely due to seasonal and inter-annual redistributions of species in agricultural landscapes in response to such changes. The temporal dimension cannot be ignored to understand the assembly of local carabid communities in farmlands. C_LI

ecology↗

bioRxiv2020

The time course of color constancy by achromatic adjustment in immersive illumination: What looks white under coloured lights?

Chromatic adaptation is a major contributory mechanism to constancy, yet its extent depends on many factors - spectral, spatial and temporal - which vary between studies and hence may contribute to differences in reported constancy indices. Here, we use the achromatic adjustment method to characterise the temporal progression of chromatic adaptation under a wide range of illuminations in an immersive environment. We control both the spectral properties of the illumination at the eye and the spatial context of the adjusted surface, to disentangle global adaptation from local contrast effects. We measure the timecourse of chromatic adaptation by assessing achromatic adjustments in 6 discrete time slots over 340 seconds. We find that the change over time of the adaptation state, proximally indicated by colour constancy indices (quantified by the relative closeness of the perceptual whitepoint to the test illumination chromaticity), (a) can be modelled by a proportional rate growth function, typically requiring more than 5 minutes to stabilise; (b) depends on the contrast between the test surface and its background, specifically increasing with decreasing test-background contrast; and (c) is generally similar in both extent and rate for different test illumination chromaticities. Adaptation progression does not differ significantly between illuminations on or off the daylight locus. Our results highlight the importance of considering exposure duration and stimulus configuration, as well as the distance between the pre-adaptation (reference) and test illumination chromaticities, when using achromatic adjustment as a measure of colour constancy.

neuroscience↗

bioRxiv2019

From plant populations to communities: using hierarchical trait environment relationships to reveal within ecosystem filtering

Explaining the existence of highly diverse plant communities under strong abiotic filtering is a long-standing challenge in ecology. Hierarchical aspects of abiotic and biotic filters are rarely taken into account and studies focus mainly on community-level aggregated patterns. Because variations in biotic conditions might take place in short abiotic gradient and within the tolerance of species in regional pool, it is likely that biotic filtering will select individuals within species and adjust population characteristics. To challenge this idea, we replicated a diversity gradient in four highly contrasted wetlands with an almost complete species turn-over, sampling individuals in communities irrespective of their taxonomic identities or status. Using hierarchical distributional modelling, we analyzed the variation of the mean and dispersion of functional trait space at the ecosystem, community and species level. We found that the abiotic differences between ecosystems filtered species contrasted in their growth/nutrient conservation trade-off, while within ecosystems community variation were mainly due to the partitioning of canopy and leaf adaptations to light conditions. We found strong species-specific functional and demographic responses of dominant species along the diversity gradient, especially for traits linked to biomass and space occupation. Two contrasted strategies emerged, with species using plasticity to maintain equally dense populations, while others used plasticity to become overwhelmingly abundant when in favorable conditions. Our results demonstrate that within ecosystems, variation in biotic conditions selects individuals within populations, revealing the importance of phenotypic variation for a species to be maintained in more or less diverse communities. Because phenotypic variations are related to demographic responses, it offers a way to link the study of species diversity and eco-evolutionary dynamics.

ecology↗

bioRxiv2017

Species-specific adaptations determine how aridity and biotic interactions drive the assembly of dryland plant communities

O_LIDespite being a core ecological question, disentangling individual and interacting effects of plant-plant interactions, abiotic factors and species-specific adaptations as drivers of community assembly is challenging. Studies addressing this issue are growing rapidly, but they generally lack empirical data regarding species interactions and local abundances, or cover a narrow range of environmental conditions.\nC_LIO_LIWe analysed species distribution models and local spatial patterns to isolate the relative importance of key abiotic (aridity) and biotic (facilitation and competition) drivers of plant community assembly in drylands worldwide. We examined the relative importance of these drivers along aridity gradients and used information derived from the niches of species to understand the role that species-specific adaptations to aridity play in modulating the importance of community assembly drivers.\nC_LIO_LIFacilitation, together with aridity, was the major driver of plant community assembly in global drylands. Due to community specialization, the importance of facilitation as an assembly driver decreased with aridity, and became non significant at the border between arid and semiarid climates. Under the most arid conditions, competition affected species abundances in communities dominated by specialist species. Due to community specialization, the importance of aridity in shaping dryland plant communities peaked at moderate aridity levels.\nC_LIO_LISynthesis: We showed that competition is an important driver of community assembly even under harsh environments, and that the effect of facilitation collapses as driver of species relative abundances under high aridity because of the specialization of the species pool to extremely dry conditions. Our findings pave the way to develop more robust species distribution models aiming to predict the consequences of ongoing climate change on community assembly in drylands, the largest biome on Earth.\nC_LI

ecology↗