Biology subjects

Cunningham, C.

Publications and source records attributed to Cunningham, C..

At least 19 recordsLinked to original sources

bioRxiv2026

Glyphosate exposure minimally alters the Corbicula fluminea microbiome while associated bacteria exhibit high tolerance and degradation potentia

Glyphosate (GLY), the active ingredient in Roundup, is a broad-spectrum herbicide widely used in commercial agriculture and residential landscaping. Due to its extensive application and high water solubility, GLY is frequently introduced into freshwater ecosystems where it has been shown to negatively impact aquatic life and beneficial microorganisms. The freshwater clam Corbicula fluminea, a nonnative bivalve species widely distributed throughout the United States, is highly tolerant of many environmental stressors and may serve as a reservoir for microbial taxa capable of tolerating or degrading environmental pollutants. As efficient filter-feeders, these clams are continuously exposed to waterborne contaminants, potentially facilitating interactions between pollutants and host-associated microbial communities. In this study, we investigated how glyphosate impacts the structure and diversity of Corbicula fluminea microbiomes and characterized GLY tolerance and degradation potential in individual microbiome members. We found that microbiome taxonomic composition and abundance-based diversity metrics were minimally impacted by glyphosate, while presence/absence-based phylogenetic diversity shifted depending on treatment concentration. Furthermore, high GLY concentrations were linked to reduced Faith''s PD alpha diversity, while other alpha diversity metrics were not impacted. Additionally, we isolated and characterized glyphosate-tolerant bacterial strains from clam tissues and assessed their presence within the microbiome. Several isolates exhibited tolerance to very high GLY levels (up to 1600 mg/L), and several also utilized GLY as a sole phosphorus source and possessed the phnJ gene, suggesting potential degradation capabilities. While isolated bacteria were minority members of the microbiome, more abundant uncultured taxa were phylogenetically related to known glyphosate degraders. Collectively, these findings suggest that freshwater bivalves may harbor diverse microbial taxa capable of tolerating or degrading herbicides, which may contribute to host resilience in contaminated freshwater environments and potentially represent unexplored avenues for bioremediation research.

microbiology↗

bioRxiv2026

Clustered cytoneme interactions contribute to peripheral nervous system patterning in Drosophila

The formation of patterned adult tissues requires precise spatiotemporal communication between the cells that comprise the tissue during development. The dorsal thoracic sensory bristles of the peripheral nervous system (PNS) of the fruit fly Drosophila melanogaster relies on the activity of cell protrusions called cytonemes. Experimental studies have identified several of the mechanisms that govern individual cytoneme dynamics in the patterning PNS, and theoretical studies have considered the effects of their collective activity. However less is understood about how cytonemes in the developing PNS interact with each other to achieve wild type tissue patterning. Here, using in vivo and ex vivo imaging strategies combined with fly genetics, we show that cytonemes form clusters along the basal surface and that association with clusters promotes the dynamics of individual cytonemes. Clusters are dynamic and transient organizations of cytonemes, and we show that when their movement is perturbed ex vivo through locally aligned nanofibers wildtype PNS patterning is disrupted. We show evidence that cytoneme interactions via clusters is supported by the cell adhesion molecule E-cadherin, as reducing E-cadherin expression leads to changes in cluster dynamics, ability to promote cytoneme length, and overall patterning of the PNS. Taken together, our results support a model in which complex cytoneme interactions promote the dynamics of individual cytonemes. We propose that the enhanced dynamics and stability provided by increased cell-cell interactions may support both the range and strength of local signaling events.

developmental biology↗

bioRxiv2026

Spinal reflex modulation in the pelvic floor muscles through sensory stimulation from the lower limb

The pelvic floor muscles (PFM) are critical for maintaining continence and are a primary target of physiotherapy training to manage urinary incontinence. PFM training relies on voluntarily activating this muscle group, limiting its translation to neurological populations where recovery of bladder function is a priority. Indirect evidence suggests that sensory feedback from the lower limb can modulate PFM activity, which may provide alternative strategies for PFM training. Cutaneous reflexes have been used as a proxy to study how sensory inputs from the skin influence motoneuron excitability. To explore the feasibility of eliciting cutaneous reflexes in the PFM and their role in controlling PFM activity, this study examined: 1) the input-output relationship and 2) the nerve-specificity of PFM cutaneous reflex responses from tibial and superficial peroneal nerve stimulation. Twenty-one neurologically intact adults participated in this study. We recorded PFM and lower leg muscle electromyography while participants received cutaneous stimulation to the right distal tibial nerve, bilateral distal tibial nerve, or right superficial peroneal nerve in a standing position. We delivered stimulation at the intensity below motor threshold (MT), 1.2 x MT and 1.5 x MT and quantified tibial-PFM reflex amplitude over a 50-150 ms window after stimulation. PFM reflex responses were evoked from both nerves stimulation. Reflex amplitude increased with stimulus intensity with tibial nerve stimulation but not with superficial peroneal nerve stimulation. Bilateral tibial nerve stimulation evoked larger responses compared to unilateral stimulation. These findings support the existence of neural connections between lower limb afferents and the PFM, and open up possibilities for designing rehabilitation strategies to manage pelvic health conditions in people with neurological disorders. New & NoteworthyO_LICutaneous sensory feedback from the foot, specifically that related to limb loading, can evoke reflex responses in the pelvic floor muscles C_LIO_LINerve-specific modulation was observed. Reflex amplitudes in the pelvic floor muscles increased with tibial nerve stimulation intensity but not with superficial peroneal nerve stimulation. C_LI

neuroscience↗

bioRxiv2026

Ketone bodies mitigate against systemic inflammation-induced changes in brain energy metabolism and delirium-like deficits in aged mice

Acute systemic inflammation affects brain function, with detrimental consequences in aged individuals. These include delirium, an acute neuropsychiatric syndrome characterized by fluctuating disturbances in attention, perception and cognition. Delirium is associated with disrupted brain energy metabolism but our understanding of this during acute systemic inflammation is limited. Here we hypothesized that LPS-induced systemic inflammation would disrupt brain energy metabolism in aged C57BL6J mice and that the consequent functional impairments would be mitigated by ketone body utilization. We investigated ketone body effects in sickness behaviour, inflammation, energy metabolism and cognitive function. Real-time changes in utilisation of energy sources were quantified by indirect calorimetry and administration of radioisotope-labelled glucose and betahydroxybutyrate. Mass-spectrometry metabolomics was used to index severity of behavioural distrurbances to changes in hippocampal energy metabolism. LPS precipitated hypoglycemia and induced a whole-body switch from carbohydrate to lipid utilisation. Despite this, hippocampal insulin resistance and preserved brain glucose was observed while alternative carbohydrates, mannose and fructose, became depleted. Ketone ester treatment reversed insulin resistance, mitigated sickness behaviour and prevented delirium-like cognitive dysfunction without altering pro-inflammatory responses. Our results show that promoting ketone body usage mitigates systemic inflammation-induced brain energy disruption and prevents delirium-like cognitive deficits in aged mice.

neuroscience↗

bioRxiv2025

MICRO-TAG enzyme complementation enables quantification of cellular drug-target engagement in temperature series

Drug discovery for challenging drug targets necessitates the proteomic complexities of the cellular milieu for contextual target folding and function. Conventional biophysical methods for assessing drug interaction with a target are often not sufficiently suited for drug discovery as they impose acellular environment on the target and rely on recombinant purified protein material. In contrast, cell target engagement offers a powerful paradigm for drug discovery, through measurement of transitions in the thermodynamic state of a target protein, as it engages with drug molecules in the cell. Split-enzyme cell target engagement methods offer scaled utility during early drug discovery. Here, we describe a novel highly sensitive and scalable fluorescence-based cell target engagement method that leverages complementation of split-RNase S. This offers a unique combination of procedural and biophysical advantages, enabling its seamless integration with various instruments and applications designed for fluorescence detection. Most importantly, this new method allows for quantitation of cell target engagement in programmable temperature series format, consistent with conventional thermal shift assays, rather than at a single melting temperature. We demonstrate the sensitivity and versatility of this approach for drug discovery using targets MAPK1, KRAS, and UBE2N.

biochemistry↗

bioRxiv2025

Deep Evolutionary Fitness Inference for Variant Nomination from Directed Evolution

Iterative screening techniques, such as directed evolution, enable high-throughput affinity maturation to optimize binders to molecular interfaces. However, the decision problem of selecting variants from rich, evolved populations to enter low-throughput follow-up methods remains a significant bottleneck. Here, we present evolutionary fitness inference (EVFI) and DeepEVFI, two machine learning methods that model directed evolution from time-series sequencing data, and infer fitness, a variants ability to enrich under selection pressure. Our methods flexibly handle mutation mechanisms and starting populations that may be partially unknown - settings relevant to drug discovery - and achieve strong performance on a diverse set of experimental data. We conducted two experimental directed evolution campaigns, using antibodies and macrocyclic peptides libraries to identify and optimize binders to therapeutically relevant targets. EVFI and DeepEVFI identified tighter binders that were missed by human experts using conventional frequency-based approaches, including "rising stars" with low frequency. Beyond initial hit discovery, EVFI and Deep-EVFI enables labeling large-scale sequence-fitness datasets and identifying variants of initial binders with diverse properties.

bioinformatics↗

bioRxiv2024

An mRNA Display Approach for Covalent Targeting of a Staphylococcus aureus Virulence Factor

Staphylococcus aureus (S. aureus) is an opportunistic human pathogen that causes over one million deaths around the world each year. We recently identified a family of serine hydrolases termed fluorophosphonate binding hydrolases (Fphs) that play important roles in lipid metabolism and colonization of a host. Because many of these enzymes are only expressed in Staphylococcus bacteria, they are valuable targets for diagnostics and therapeutics. Here we developed and screened highly diverse cyclic peptide libraries using mRNA display with a genetically encoded oxadiazolone (Ox) electrophile that was previously shown to potently and covalently inhibit multiple Fph enzymes. By performing multiple rounds of counter selections with WT and catalytic dead FphB, we were able to tune the selectivity of the resulting selected cyclic peptides containing the Ox residue towards the desired target. From our mRNA display hits, we developed potent and selective fluorescent probes that label the active site of FphB at single digit nanomolar concentrations in live S. aureus bacteria. Taken together, this work demonstrates the potential of using direct genetically encoded electrophiles for mRNA display of covalent binding ligands and identifies potent new probes for FphB that have the potential to be used for diagnostic and therapeutic applications.

microbiology↗

bioRxiv2024

Integrating diverse statistical methods to analyse stage-discriminatory cell interactions in colorectal neoplasia

Spatial biology has the potential to unlock information about the disrupted cellular ecosystems that define human disease. Quantitative analysis of spatially-resolved cell interactions allows mapping of tissue self-organisation and assessment of why cells interact differently in physiological and pathological contexts. However, the complexity of mammalian tissues, that occur across a spectrum of length scales, presents significant challenges for spatial analysis, increasing the gap between our capacity to generate and biologically interpret these datasets. Here, we have adapted a range of mathematical tools to develop a suite of spatial descriptors, and deployed them to determine how cell interactions change as colorectal cancer progresses from benign precursors. We demonstrate that combining mathematical analyses permits insightful examination of tissue organisational structures and identifies variable cell-interaction pathways that underpin disease progression. Mathematical tool triangulation can cross-corroborate spatial biology findings, facilitating development of analysis pipelines that are robust to individual method limitations.

cancer biology↗

bioRxiv2023

Stress-induced Rab11a-exosomes induce AREG-mediated cetuximab resistance in colorectal cancer

Exosomes are secreted vesicles made intracellularly in the endosomal system. We have previously shown that exosomes are not only made in late endosomes, but also in recycling endosomes marked by the monomeric G-protein Rab11a. These vesicles, termed Rab11a-exosomes, are preferentially secreted under nutrient stress from several cancer cell types, including HCT116 colorectal cancer (CRC) cells. HCT116 Rab11a-exosomes have particularly potent signalling activities, some mediated by the Epidermal Growth Factor Receptor (EGFR) ligand, Amphiregulin (AREG). Mutant activating forms of KRAS, a downstream target of EGFR, are often found in advanced CRC. When absent, monoclonal antibodies, such as cetuximab, which target the EGFR and block the effects of EGFR ligands, such as AREG, can be administered. Patients, however, inevitably develop resistance to cetuximab, either by acquiring KRAS mutations or via non-genetic microenvironmental changes. Here we show that nutrient stress in several CRC cell lines causes the release of AREG-carrying Rab11a-exosomes. We demonstrate that while soluble AREG has no effect, much lower levels of AREG bound to Rab11a-exosomes from cetuximab-resistant KRAS-mutant HCT116 cells, can suppress the effects of cetuximab on KRAS-wild type Caco-2 CRC cells. Using neutralising anti-AREG antibodies and an intracellular EGFR kinase inhibitor, we show that this effect is mediated via AREG activation of EGFR, and not transfer of activated KRAS. Therefore, presentation of AREG on Rab11a-exosomes affects its ability to compete with cetuximab. We propose that this Rab11a-exosome-mediated mechanism contributes to the establishment of resistance in cetuximab-sensitive cells and may explain why in cetuximab-resistant tumours only some cells carry mutant KRAS. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=157 HEIGHT=200 SRC="FIGDIR/small/572341v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@18f47bborg.highwire.dtl.DTLVardef@1ae627corg.highwire.dtl.DTLVardef@1c3cb23org.highwire.dtl.DTLVardef@14da12e_HPS_FORMAT_FIGEXP M_FIG C_FIG This study highlights a clinically relevant mechanism in which stress-induced Rab11a-exosomes carrying the EGFR ligand, Amphiregulin (AREG) transfer drug resistance between genetically distinct colorectal cancer cells. Resistance to cetuximab, an anti-EGFR therapy, can be passed via Rab11a-exosomes from drug-resistant KRAS-mutant cells to previously drug-responsive KRAS-wild type cells. Unlike soluble AREG, Rab11a-exosome-associated AREG competes with cetuximab to activate EGFR signalling and promote EGFR-dependent outcomes, such as growth. This mechanism may support the co-operative evolution of clonal heterogeneity during tumour progression.

cancer biology↗

bioRxiv2023

Single cell transcriptional changes across the blood stages of artemisinin resistant K13C580Y mutant Plasmodium falciparum upon dihydroartemisinin exposure

Artemisinin-based therapies have been central to malaria control, but partial resistance in Plasmodium falciparum, driven by mutations in the Kelch13 (K13) protein, threatens these gains. To investigate the molecular basis of this resistance, we applied single-cell RNA sequencing to coisogenic parasite lines, K13 wild-type (K13C580) and the artemisinin-resistant mutant (K13580Y), following a 6 hour pulse of dihydroartemisinin (DHA). This approach enabled high-resolution profiling across intraerythrocytic stages. Both lines exhibited stage-specific transcriptional responses, with pronounced changes in ring and trophozoite stages. Using Manifold Enhancement of Latent Dimensions (MELD), a computational framework for quantifying transcriptional perturbation, DHA-treatment induces stage-specific differences in protein export and metabolic pathways in K13C580 and K13580Y parasites, relating to an altered metabolic stress response state. GARP, a potential therapeutic target, was highly differentially expressed in untreated ring stages of K13580Y and K13C580. Functional assays confirmed that anti-GARP antibodies retained efficacy against K13580Y, supporting its potential as a therapeutic target. These findings provide a comprehensive view of the cellular responses related to artemisinin resistance, identify molecular features of pathogenesis, and highlight surface proteins like GARP as promising intervention targets. This work underscores the power of single-cell approaches to dissect drug responses and guide strategies to overcome resistant parasites.

microbiology↗

bioRxiv2023

Dmnt1 and Wnt in the production of oocytes

The function of methylation in insects and the DNA methyltransferase (Dnmt) genes that influence methylation remains uncertain. We used RNAi to reduce the gene expression of Dnmt1 within the whitefly Bemisia tabaci, a hemipteran species that relies on Dnmt1 for proper gametogenesis. We then used RNA-seq to test an a priori hypothesis that meiosis related genetic pathways would be perturbed. We generally did not find an overall effect on meiosis related pathways. However, we found that genes in the Wnt pathway, genes associated with the entry into meiosis in vertebrates, were differentially expressed. Our results are consistent with Dnmt1 knockdown influencing specific pathways and not causing general transcriptional response. This is a finding that is also seen with other insect species. We also characterized the methylome of B. tabaci and assessed the influence of Dnmt1 knockdown on cytosine methylation. This species has methylome characteristics comparable to other hemipterans regarding overall level, enrichment within gene bodies, and bimodal distribution of methylated/non-methylated genes. Very little differential methylation was observed, and difference of methylation were not associated with differences of gene expression. The effect on Wnt presents an interesting new candidate pathway for future studies.

genomics↗

bioRxiv2023

Rat microbial biogeography and age-dependent lactic acid bacteria in healthy lungs

The laboratory rat emerges as a useful tool for studying the interaction between the host and its microbiome. To advance principles relevant to the human microbiome, we systematically investigated and defined a multi-tissue full lifespan microbial biogeography for healthy Fischer 344 rats. Microbial community profiling data was extracted and integrated with host transcriptomic data from the Sequencing Quality Control (SEQC) consortium. Unsupervised machine learning, Spearmans correlation, taxonomic diversity, and abundance analyses were performed to determine and characterize the rat microbial biogeography and the identification of four inter-tissue microbial heterogeneity patterns (P1-P4). The 11 body habitats harbor a greater diversity of microbes than previously suspected. Lactic acid bacteria (LAB) abundances progressively declined in lungs from breastfeed newborn to adolescence/adult and was below detectable levels in elderly rats. LABs presence and levels in lungs were further evaluated by PCR in the two validation datasets. The lung, testes, thymus, kidney, adrenal, and muscle niches were found to have age-dependent alterations in microbial abundance. P1 is dominated by lung samples. P2 contains the largest sample size and is enriched for environmental species. Liver and muscle samples were mostly classified into P3. Archaea species were exclusively enriched in P4. The 357 pattern-specific microbial signatures were positively correlated with host genes in cell migration and proliferation (P1), DNA damage repair and synaptic transmissions (P2), as well as DNA transcription and cell cycle in P3. Our study established a link between metabolic properties of LAB with lung microbiota maturation and development. Breastfeeding and environmental exposure influence microbiome composition and host health and longevity. The inferred rat microbial biogeography and pattern-specific microbial signatures would be useful for microbiome therapeutic approaches to human health and good quality of life. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=113 SRC="FIGDIR/small/541527v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@1387224org.highwire.dtl.DTLVardef@cdb7dborg.highwire.dtl.DTLVardef@1e1c7ccorg.highwire.dtl.DTLVardef@440ca_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2022

Hyperthermia elevates brain temperature and improves behavioural signs in animal models of Autism spectrum disorder.

Autism Spectrum Disorders (ASD) are predominantly developmental in nature and largely genetically determined. There are some human data supporting the idea that fever can improve symptoms in some individuals but the human data for this are limited and there are almost no data to support this from animal models. In the current study we used a whole body hyperthermia (WBH) protocol and systemic inflammation induced by bacterial endotoxin (LPS) to dissociate temperature and inflammatory elements of fever in order to examine the impact of these environmental stressors on behavioural signs in two animal models relevant to ASD: C58BL/6 and Shank3B- mice. While only LPS induced inflammatory signatures in the brain, WBH and LPS induced both overlapping and distinct neuronal cFos activation in several brain regions and modest effects on heat shock gene expression. In behavioural experiments LPS significantly suppressed most activities over 24-48 hours while WBH reduced repetitive behaviours and improved social interaction in C58BL/6 mice. In Shank3B- mice WBH significantly reduced compulsive grooming. The data are the first, to our knowledge, to demonstrate that elevated body temperature, in the absence of underpinning inflammation, can improve some behavioural signs in two distinct animal models of ASD. Given the developmental and genetic nature of ASD, evidence that symptoms may be ameliorated by environmental perturbations indicates that there are possibilities for improving function in these individuals.

neuroscience↗

bioRxiv2022

Oxytocin/vasopressin system of insects influences parental care in males but not females

AO_SCPLOWBSTRACTC_SCPLOWParental care is thought to evolve through modification of behavioral precursors, which predicts that the mechanistic changes occur in the genes underlying those traits. The duplicated gene system of oxytocin/vasopressin has been broadly co-opted across vertebrates to influence parenting, from a pre-duplication ancestral role in water balance. It remains unclear whether co-option of these genes for parenting is limited to vertebrates. Here, we experimentally tested for associations between inotocin gene expression and water balance, parental acceptance of offspring, and active parenting in the subsocial beetle Nicrophorus orbicollis, to test whether a single copy homologue, inotocin, has similarly been co-opted for parental care in a species with elaborate parenting. As expected, inotocin was associated with water balance in both sexes. Inotocin expression increased around sexual maturation in both males and females, although more clearly in males. Finally, we found that expression of inotocin was not associated with acceptance of larvae but was associated with a transition to male but not female parenting. Moreover, level of offspring provisioning behavior and gene expression were positively correlated in males but uncorrelated in females. Our results suggest a broad co-option of this system for parenting that may have existed prior to gene duplication, and that inotocin may be associated with flexibility in parenting behavior. IO_SCPLOWMPACTC_SCPLOW SO_SCPLOWUMMARYC_SCPLOWOxytocin/vasopressin are amongst the most studied neuropeptides in vertebrates, influencing water balance, mating interactions, and most notably, social bonding. This gene pair evolved from a duplication in the vertebrate lineage of an ancestral vasopressin-like gene. Are the multiple social effects in vertebrates due to this duplication, or are social influences also ancestral? Here, we demonstrate that, in a biparental social beetle with a single copy, inotocin is associated with social interactions between fathers and offspring as well as being associated with the ancestral role of water balance in both males and females. In vertebrates, both oxytocin and vasopressin have been shown to impact social interactions in both sexes, although often showing sex-specificity in their action within species. Our results suggest that this system may have been co-opted for parenting prior to gene duplication and may facilitate flexibility in caring behavior.

evolutionary biology↗

bioRxiv2022

Continuing decline of the eastern quoll in Tasmania

Like many other Australian mammals, the eastern quoll (Dasyurus viverrinus) was widespread on the Australian mainland but went extinct there during the 20th century. The species remained abundant in Tasmania until a rapid decline occurred from 2001 to 2003, coinciding with a period of unsuitable weather. We provide an updated analysis of eastern quoll population trends in Tasmania by analysing a Tasmania-wide time series of annual spotlight counts (1985-2019). Eastern quolls were widespread and abundant in Tasmania until the early 2000s. A distinct change occurred in the early 2000s in the east and northeast, which led to severe population reductions. However, we present new evidence of an earlier decline in the north (mid-1990s) and a more recent decline around 2009 in the south. Range-wide declines have continued unabated during the last decade, resulting in a [~]67% decline (since the late 1990s) in the area with high quoll abundance. Although the timing of the major decline in the early 2000s coincided with unfavourable weather, the continuing decline and more recent change points suggest other causes are also involved. We can no longer assume that the existence of eastern quolls in Tasmania ensures the species long-term survival, highlighting the urgent need to increase efforts to conserve the remaining populations in Tasmania.

ecology↗

bioRxiv2021

Cholinergic signalling in the forebrain controls microglial phenotype and responses to systemic inflammation

Abstract(250)Loss of basal forebrain cholinergic projections occurs in Alzheimers disease, frontotemporal dementia and in aging. Moreover, nicotinic stimulation is anti-inflammatory in macrophages and microglia but how loss of basal forebrain acetylcholine impacts on microglial phenotype is poorly understood. Here we hypothesized that endogenous ACh maintains homeostatic microglial phenotype and that neurodegeneration-evoked loss of ACh tone, triggers microglial activation. Using the specific immunotoxin, mu-p75NTR-saporin, we performed partial lesions of the basal forebrain cholinergic nuclei, medial septum and ventral diagonal band. We examined microglial phenotype in the hippocampus, the major projection area for these nuclei, using bulk RNA preparations, Flow cytometry-sorted microglial cells, immunohistochemistry and ELISA to examine responses to cholinergic withdrawal and acute responses to subsequent systemic inflammation with LPS. Basal forebrain cholinergic degeneration elicited lasting activation of microglia in the hippocampus, showing suppression of Sall1 and persistent elevation of Trem2, Clec7a, Itgax and complement genes proportionate to Chat loss. These primed microglia showed exaggerated IL-1{beta} responses to systemic LPS challenge. In normal animals LPS evoked acute increases in extracellular choline, a proxy for ACh release, and this response was lost in lesioned animals. Restoration of basal cholinergic signalling via serial treatments with the nicotinic agonist PNU282,987 resulted in reversion to the homeostatic microglial phenotype and prevented exaggerated responses to acute systemic inflammation. The data indicate that neurodegeneration-evoked loss of cholinergic tone, triggers microglial activation via impaired microglial nicotinic signalling and leaves these microglia more vulnerable to secondary inflammatory insults. The data have implications for neuroinflammation during aging and neurodegeneration and for responses to sepsis and systemic inflammation.

neuroscience↗

bioRxiv2021

Double stranded RNA drives innate immune responses, sickness behavior and cognitive impairment dependent on dsRNA length, IFNAR1 expression and age

Double stranded RNA is generated during viral replication. The synthetic analogue poly I:C is frequently used to mimic anti-viral innate immune responses in models of psychiatric and neurodegenerative disorders including schizophrenia, autism, Parkinsons disease and Alzheimers disease. Many studies perform limited analysis of innate immunity despite these responses potentially differing as a function of dsRNA molecular weight and age. Therefore fundamental questions relevant to impacts of systemic viral infection on brain function and integrity remain. Here, we studied innate immune-inducing properties of poly I:C preparations of different lengths and responses in adult and aged mice. High molecular weight (HMW) poly I:C (1-6kb, 12 mg/kg) produced more robust sickness behavior and more robust IL-6, IFN-I and TNF responses than poly I:C of <500 bases (low MW) preparations. This was partly overcome with higher doses of LMW (up to 80 mg/kg), but neither circulating IFN{beta} nor brain transcription of Irf7 were significantly induced by LMW poly I:C, despite brain Ifnb transcription, suggesting that brain IFN-dependent gene expression is predominantly triggered by circulating IFN{beta} binding of IFNAR1. In aged animals, poly I:C induced exaggerated IL-6, IL-1{beta} and IFN-I in the plasma and similar exaggerated brain cytokine responses. This was associated with acute working memory deficits selectively in aged mice. Thus, we demonstrate dsRNA length-, IFNAR1- and age-dependent effects on anti-viral inflammation and cognitive function. The data have implications for CNS symptoms of acute systemic viral infection such as those with SARS-CoV-2 and for models of maternal immune activation.

neuroscience↗

bioRxiv2020

Novel inhibitors of E. coli lipoprotein diacylglyceryl transferase are insensitive to resistance caused by lpp deletion

Lipoprotein diacylglyceryl transferase (Lgt) catalyzes the first step in the biogenesis of Gram-negative bacterial lipoproteins which play crucial roles in bacterial growth and pathogenesis. We demonstrate that Lgt depletion in a clinical uropathogenic Escherichia coli strain leads to permeabilization of the outer membrane and increased sensitivity to serum killing and antibiotics. Importantly, we identify the first ever described Lgt inhibitors that potently inhibit Lgt biochemical activity in vitro and are bactericidal against wild-type Acinetobacter baumannii and E. coli strains. Unlike inhibition of other steps in lipoprotein biosynthesis, deletion of the major outer membrane lipoprotein, lpp, is not sufficient to rescue growth after Lgt depletion or provide resistance to Lgt inhibitors. Our data validate Lgt as a novel druggable antibacterial target and suggest that inhibition of Lgt may not be sensitive to one of the most common resistance mechanisms that invalidate inhibitors of downstream steps of bacterial lipoprotein biosynthesis and transport.

microbiology↗