Biology subjects

White, M.

Publications and source records attributed to White, M..

At least 37 records · Page 2Linked to original sources

bioRxiv2024

Systematic bias in malaria parasite relatedness estimation

Genetic studies of malaria parasites increasingly feature estimates of relatedness. However, various aspects of malaria parasite relatedness estimation are not fully understood. For example, estimates of relatedness based on whole-genome-sequence (WGS) data often exceed those based on more sparse data types. We explore systematic bias in relatedness estimation using theoretical, numerical and empirical approaches. Specifically, we use a non-ancestral model of pairwise relatedness to derive theoretical results; a simulation model of ancestry to independently verify and expand our theoretical results; and data on parasites sampled from Guyana to explore how theoretical and numerical results translate empirically. We show that allele frequencies encode, locus-by-locus, relatedness averaged over the set of sampled parasites used to compute them. These sample allele frequencies are typically plugged into the models used to estimate pairwise relatedness. Consequently, models of pairwise relatedness are misspecified and pairwise relatedness values are systematically underestimated. However, systematic underestimation can be viewed as population-relatedness calibration, i.e., a way of generating measures of relative relatedness. Systematic underestimation is unavoidable when relatedness is estimated assuming independence between genetic markers. It is mitigated when estimated using WGS data under a hidden Markov model (HMM), which exploits linkage between proximal markers. Estimates of absolute relatedness generated under a HMM using relatively sparse data should be treated with caution because the extent to which underestimation is mitigated is unknowable. That said, analyses dependent on absolute values and high relatedness thresholds are relatively robust. In summary, practitioners have two options: resolve to use relative relatedness estimated under independence or try to estimate absolute relatedness under a HMM. We propose various practical tools to help practitioners evaluate their situation on a case-by-case basis. Author summaryMalaria genomic epidemiology is increasingly recognised as a tool for public health. Relatedness, which captures likeness derived from common ancestry, is a useful concept for malaria parasites. Analyses of malaria parasite relatedness are important for generating results on spatiotemporal scales relevant to disease control. Since shared ancestry is unobservable, relatedness must be estimated under a statistical model. However, not all aspects of malaria parasite estimation are fully understood, including the effects of different data types. In this work, we characterise systematic biases in estimates of malaria parasite relatedness. Our analysis is three-fold: we mathematically interrogate a non-ancestral model of relatedness to derive theoretical results; simulate parasite ancestries from first principles to yield numerical results; and perform an empirical case study of parasites sampled from Guyana. We show that bias may be particularly pronounced when using sparse marker data from inbred parasite populations, which are often found in pre-elimination settings. We chart out a practical roadmap to enable practitioners to assess epidemiological settings on a case-by-case basis. Our findings are relevant to applications in malaria genomic epidemiology that use relatedness directly or indirectly, including molecular surveillance and the genetic-based classification of treatment failure.

genetics↗

bioRxiv2024

Focused ultrasound increases gene delivery to deep brain structure following the administration of a recombinant adeno-associated virus in the cerebrospinal fluid

Gene delivery via adeno-associated viral vectors can provide lasting clinical benefits following a one-time treatment. Delivery throughout the brain is needed for the treatment of neurological disorders with widespread pathology, including Alzheimer and Parkinson diseases, and amyotrophic lateral sclerosis. Most gene vectors have poor diffusion in the brain tissue. Furthermore, it is only at high intravenous doses that gene vectors can overcome the blood-brain barrier. In contrast, relatively lower doses of gene vectors injected in the cerebrospinal fluid enable significant transduction of superficial brain regions. The remaining challenge and unmet need of gene therapy is to deliver gene vectors to deep brain structures using a minimally invasive strategy. Here, we demonstrate that non-invasive focused ultrasound blood-brain barrier modulation can increase the delivery of recombinant adeno-associated virus by 5-fold to deep brain structures following injection in the cisterna magna. Delivery of adeno-associated viral vectors to the central nervous system, via administration in the cerebrospinal fluid, is being evaluated in several clinical trials for treating beta-galactosidase-1 deficiency, Batten disease, Alzheimer disease, Parkinson disease, amyotrophic lateral sclerosis, and spinal muscular atrophy. Our findings suggest that the efficacy of gene therapies delivered in the cerebrospinal fluid can be enhanced by targeting brain areas of interest with focused ultrasound. Significance statementAdministration of viral vectors in the cerebrospinal fluid through the cisterna magna is being evaluated in patients with neurological disorders. Focused ultrasound combined with intravenous microbubbles safely increases the permeability of the blood-brain barrier in humans and enables delivery of intravenous adeno-associated virus in non-human primates. Here, we demonstrate that combining these two clinically relevant gene delivery methods, intracisterna magna administration and focused ultrasound with microbubbles, can facilitate gene delivery to superficial and deep brain structures. Our findings have the potential to increase the efficacy of gene therapies, particularly for disorders with brain regions that have remained difficult to reach.

neuroscience↗

bioRxiv2023

Metabolic and imaging phenotypes associated with RB1 loss in castrate resistant prostate cancer

Advanced prostate cancer is treated with androgen receptor (AR) signaling inhibitors, which are initially effective, but most patients eventually develop resistance and progress to castrate-resistant prostate cancer (CRPC). Loss of RB1 in CRPC tumors is correlated with rapid progression and poor patient survival and, in combination with TP53 loss, predisposes patients to the development of transitional neuroendocrine prostate cancer (NEPC). Although progressive CRPC is clinically associated with higher 18FDG-PET SUVmax values, it is unknown whether inactivation of RB1 and/or TP53 is a driver of increased glucose import. Using a cohort of patient-derived xenograft (PDX)-derived CRPC organoids, we found that NEPC could not be conclusively distinguished from adenocarcinoma by 18FDG uptake alone, and PSMA protein levels did not correlate with cancer phenotype or 18FDG uptake. Castration-resistant models showed higher 18FDG uptake, but lower pyruvate-to-lactate conversion compared to their castration-sensitive counterparts. In parallel studies using castration-sensitive prostate cancer models, RB1/TP53 knockdown did not affect 18FDG uptake, but increased basal respiration and glycolytic activity, with combined depletion leading to glucose diversion into glycogenesis. These metabolic changes were reflected in increased lactate dehydrogenase flux detected by 13C-hyperpolarized magnetic resonance spectroscopy upon RB1 loss, but not in 18FDG uptake. The metabolic heterogeneity revealed here suggests that a multimodal molecular imaging approach can improve tumor characterization, potentially leading to a better prognosis in cancer treatment.

cancer biology↗

bioRxiv2023

Single cell analysis of dup15q syndrome reveals developmental and postnatal molecular changes in autism

Duplication 15q (dup15q) syndrome is the most common genetic cause of autism spectrum disorder (ASD). Due to a higher genetic and phenotypic homogeneity compared to idiopathic autism, dup15q syndrome provides a well-defined setting to investigate ASD mechanisms. Previous bulk gene expression studies identified shared molecular changes in ASD. However, how cell type specific changes compare across different autism subtypes and how they change during development is largely unknown. In this study, we used single cell and single nucleus mRNA sequencing of dup15q cortical organoids from patient iPSCs, as well as post-mortem patient brain samples. We find cell-type specific dysregulated programs that underlie dup15q pathogenesis, which we validate by spatial resolved transcriptomics using brain tissue samples. We find degraded identity and vulnerability of deep-layer neurons in fetal stage organoids and highlight increased molecular burden of postmortem upper-layer neurons implicated in synaptic signaling, a finding shared between idiopathic ASD and dup15q syndrome. Gene co-expression network analysis of organoid and postmortem excitatory neurons uncovers modules enriched with autism risk genes. Organoid developmental modules were involved in transcription regulation via chromatin remodeling, while postmortem modules were associated with synaptic transmission and plasticity. The findings reveal a shifting landscape of ASD cellular vulnerability during brain development.

neuroscience↗

bioRxiv2023

Characterising neutrophil subtypes in cancer using human and murine single-cell RNA sequencing datasets

Neutrophils are a highly heterogenous cellular population. However, a thorough examination of the different transcriptional neutrophil states, between health and malignancy, has not been performed. We utilised single-cell RNA-sequencing of human and murine datasets, both publicly available and independently generated, to identify neutrophil transcriptomic subtypes and their developmental lineages in health and malignancy. Datasets of lung, breast and colorectal cancer (CRC) were integrated to establish and validate the reproducibility of neutrophil gene-signatures. Pseudo-time analysis was used to identify genes driving neutrophil development from health to cancer. Finally, ligand-receptor interactions and signalling pathways between neutrophils and other immune cell populations in primary CRC and metastatic CRC were investigated. We define two main neutrophil subtypes in primary tumours: an activated subtype sharing the transcriptomic signatures of healthy neutrophils; and a tumour-specific subtype. This signature is conserved in murine and human cancer, across different tumour types. In CRC metastases, neutrophils are more heterogenous, exhibiting additional transcriptomic subtypes. Pseudo-time analysis implicates an IL1B/CXCL8/CXCR2 axis in the progression of neutrophils from health to cancer and metastasis, with effects on T-cell effector function. Assessment of global communication signalling identified CD4+ T-cells and macrophages as dominant regulators of the immunosuppressive, metastatic niche, whereas CD8+ T-cells are receivers of signals from other immune cells. We propose that the emergence of metastatic-specific neutrophil subtypes is driven by an IL1/CXCL8/CXCR2 axis, with the evolution of different transcriptomic signals that impair T-cell function at the metastatic site. Thus, a better understanding of the neutrophil transcriptomic programming could optimise immunotherapeutic interventions into early and late interventions, targeting different neutrophil subtypes.

bioinformatics↗

bioRxiv2023

Identification of small molecule inhibitors of G3BP-driven stress granule formation

Stress granule formation is triggered by the release of mRNAs from polysomes and is promoted by the action of the paralogs G3BP1 and G3BP2. G3BP1/2 proteins bind mRNAs and thereby promote the condensation of mRNPs into stress granules. Stress granules have been implicated in several disease states, including cancer and neurodegeneration. Consequently, compounds that limit stress granule formation or promote their dissolution have potential as both experimental tools and novel therapeutics. Herein, we describe two small molecules, referred to as G3BP inhibitor a and b (G3Ia and G3Ib), designed to bind to a specific pocket in G3BP1/2 that is known to be targeted by viral inhibitors of G3BP1/2 function. In addition to disrupting co-condensation of RNA, G3BP1, and caprin 1 in vitro, these compounds inhibit stress granule formation in cells treated prior to or concurrent with stress, and dissolve pre-existing stress granules when added to cells after stress granule formation. These effects are consistent across multiple cell types and a variety of initiating stressors. Thus, these compounds represent ideal tools to probe the biology of stress granules and hold promise for therapeutic interventions designed to modulate stress granule formation.

cell biology↗

bioRxiv2023

The AusTraits Plant Dictionary

Traits with intuitive names, a clear scope and explicit description are essential for all trait databases. Reanalysis of data from a single database, or analyses that integrate data across multiple databases, can only occur if researchers are confident the trait concepts are consistent within and across sources. The lack of a unified, comprehensive resource for plant trait definitions has previously limited the utility of trait databases. Here we describe the AusTraits Plant Dictionary (APD), which extends the trait definitions included in the new trait database AusTraits. The development process of the APD included three steps: review and formalisation of the scope of each trait and the accompanying trait description; addition of trait meta-data; and publication in both human and machine-readable forms. Trait definitions include keywords, references and links to related trait concepts in other databases, and the traits are grouped into a hierarchy for easy searching. As well as improving the usability of AusTraits, the Dictionary will foster the integration of trait data across global and regional plant trait databases.

ecology↗

bioRxiv2022

Structure of the Saccharolobus solfataricus type III-D CRISPR effector

CRISPR-Cas is a prokaryotic adaptive immune system, classified into six different types, each characterised by a signature protein. Type III systems, classified based on the presence of a Cas10 subunit, are rather diverse multi-subunit assemblies with a range of enzymatic activities and downstream ancillary effectors. The broad array of current biotechnological CRISPR applications is mainly based on proteins classified as Type II, however recent developments established the feasibility and efficacy of multi-protein Type III CRISPR-Cas effector complexes as RNA-targeting tools in eukaryotes. The crenarchaeon Saccharolobus solfataricus has two type III system subtypes (III-B and III-D). Here, we report the cryo-EM structure of the Csm Type III-D complex from S. solfataricus (SsoCsm), which uses CRISPR RNA to bind target RNA molecules, activating the Cas10 subunit for antiviral defence. The structure reveals the complex organisation, subunit/subunit connectivity and protein/guide RNA interactions of the SsoCsm complex, one of the largest CRISPR effectors known.

microbiology↗

bioRxiv2022

Dog Size and Patterns of Disease History Across the Canine Age Spectrum: Results from the Dog Aging Project

Age in dogs is associated with the risk of many diseases, and canine size is a major factor in that risk. However, the size effect is not as simple as the age effect. While small size dogs tend to live longer, some diseases are more prevalent among small dogs. Utilizing owner-reported data on disease history from a substantial number of companion dogs, we investigate how body size, as measured by weight, associates with the prevalence of a reported condition and its pattern across age for various disease categories. We found significant positive associations between weight and prevalence of skin, bone/orthopedic, gastrointestinal, ear/nose/throat, cancer/tumor, brain/neurologic, endocrine, and infectious diseases. Similarly, weight was negatively associated with the prevalence of eye, cardiac, liver/pancreas, and respiratory disease categories. Kidney/urinary disease prevalence did not vary by weight. We also found that the association between age and disease prevalence varied by dog size for many conditions including eye, cardiac, orthopedic, ear/nose/throat, and cancer. Controlling for sex, purebred/mixed breed, and geographic region made little difference in all disease categories we studied. Our results align with the reduced lifespan in larger dogs for most of the disease categories but suggest potential avenues for further examination.

physiology↗

bioRxiv2021

Naturally acquired antibody kinetics against Plasmodium vivax antigens in people from a low malaria transmission region in western Thailand

Plasmodium vivax is the dominant Plasmodium spp. causing the disease malaria in low-transmission regions outside of Africa. These regions often feature high proportions of asymptomatic patients with sub-microscopic parasitaemia and relapses. Naturally acquired antibody responses are induced after Plasmodium infection, providing partial protection against high parasitaemia and clinical episodes. However, previous work has failed to address the presence and maintenance of such antibody responses to P. vivax particularly in low-transmission regions. We followed 34 patients in western Thailand after symptomatic P. vivax infections to monitor antibody kinetics over 9 months, during which no recurrent infections occurred. We assessed total IgG, IgG subclass and IgM levels to up to 52 P. vivax proteins every 2-4 weeks using a multiplexed Luminex(R) assay, and identified protein-specific variation in antibody longevity. Generally, an increase in antibody level was observed within 1-week post symptomatic infection, followed by an exponential decay of different rates. We observed mostly IgG1 dominance and IgG3 sub-dominance in this population. IgM responses followed similar kinetic patterns to IgG, with some proteins unexpectedly inducing long-lived IgM responses. We also monitored antibody responses against 27 IgG-immunogenic antigens in 30 asymptomatic individuals from a similar region. Our results demonstrate that most antigens induced robust and long-lived total IgG responses following asymptomatic infections in the absence of (detected) boosting infections. Our work provides new insights into the development and maintenance of naturally acquired immunity to P. vivax and will guide the potential use of serology to indicate immune status and/or identify populations at risk.

microbiology↗

bioRxiv2021

Microenvironmental correlates of immune checkpoint inhibitor response in human melanoma brain metastases revealed by T cell receptor and single-cell RNA sequencing

Melanoma-derived brain metastases (MBM) represent an unmet clinical need due to central nervous system (CNS) progression as a frequent, end-stage site of disease. Immune checkpoint inhibition (ICI) represents a clinical opportunity against MBM; however, the MBM tumor microenvironment (TME) has not been fully elucidated in the context of ICI. To dissect unique MBM-TME elements and correlates of MBM-ICI response, we collected 32 fresh MBM and performed single cell RNA sequencing of the MBM-TME and T cell receptor clonotyping on T cells from MBM and matched blood and extracranial lesions. We observed myeloid phenotypic heterogeneity, most notably multiple distinct neutrophil states including an IL-8 expressing population that correlated with malignant cell epithelial-to-mesenchymal transition. Additionally, we observe significant relationships between intracranial T cell phenotypes and the distribution of T cell clonotypes intracranially and peripherally. We found that the phenotype, clonotype, and overall number of MBM-infiltrating T cells were associated with response to ICI, suggesting that ICI-responsive MBMs interact with peripheral blood in a manner similar to extracranial lesions. These data demonstrate unique features of the MBM-TME, which may represent potential targets to improve clinical outcomes for patients with MBM.

cancer biology↗

bioRxiv2021

Complex feline disease mapping using a dense genotyping array

The current feline genotyping array of 63k single nucleotide polymorphisms has proven its utility within breeds, and its use has led to the identification of variants associated with Mendelian traits in purebred cats. However, compared to single gene disorders, association studies of complex diseases, especially with the inclusion of random bred cats with relatively low linkage disequilibrium, require a denser genotyping array and an increased sample size to provide statistically significant associations. Here, we undertook a multi-breed study of 1,122 cats, most of which were admitted and phenotyped for nine common complex feline diseases at the Cornell University Hospital for Animals. Using a proprietary 340k single nucleotide polymorphism mapping array, we identified significant genome-wide associations with hyperthyroidism, diabetes mellitus, and eosinophilic keratoconjunctivitis. These results provide genomic locations for variant discovery and candidate gene screening for these important complex feline diseases, which are relevant not only to feline health, but also to the development of disease models for comparative studies.

genetics↗

bioRxiv2021

Quantitative characterisation of low abundant yeast mitochondrial proteins reveals compensation for haplo-insufficiency in different environments

Quantification of low abundant membrane-binding proteins such as transcriptional factors and chaperones has been proved difficult even with the most sophisticated analytical technologies. Here we exploit and optimise the non-invasive Fluorescence Correlation Spectroscopy (FCS) for quantitation of low abundance proteins and as proof of principle we choose two interacting proteins involved in fission of mitochondria in yeast, Fis1p and Mdv1p. In Saccharomyces cerevisiae the recruitment of Fis1p and Mdv1p to mitochondria is essential for the scission of the organelles and the retention of functional mitochondrial structures in the cell. We used FCS in single, GFP-labelled live yeast cells to quantify the protein abundance in homozygote and heterozygote cells, and to investigate the impact of the environments on protein copy number, bound/unbound protein state and mobility kinetics. Both proteins were observed to localise predominantly at mitochondrial structures with the Mdv1p bound state increasing significantly in a strictly respiratory environment. Moreover, a compensatory mechanism which controls Fis1p abundance upon deletion of one allele was observed in Fis1p but not in Mdv1p, suggesting differential regulation of Fis1p and Mdv1p protein expression.

biochemistry↗

bioRxiv2021

Peripheral neuropathy linked mRNA export factor GANP reshapes gene regulation in human motor neurons

Loss-of-function of the mRNA export protein GANP (MCM3AP gene) cause early-onset sensorimotor neuropathy, characterised by axonal degeneration in long peripheral nerves. GANP functions as a scaffold at nuclear pore complexes, contributing to selective nuclear export of mRNAs. Here, we aimed to identify motor neuron specific transcripts that are regulated by GANP and may be limiting for local protein synthesis in motor neuron axons. We compared motor neurons with a gene edited mutation in the Sac3 mRNA binding domain of GANP to isogenic controls. We also examined patient-derived motor neurons. RNA sequencing of motor neurons as well as nuclear and axonal subcompartments showed that mutant GANP had a profound effect on motor neuron transcriptomes, with alterations in nearly 40 percent of all expressed genes and broad changes in splicing. Expression changes in multiple genes critical for neuronal functions, combined with compensatory upregulation of protein synthesis and early-stage metabolic stress genes, indicated that RNA metabolism was abnormal in GANP-deficient motor neurons. Surprisingly, limited evidence was found for large-scale nuclear retention of mRNA. This first study of neuropathy-linked GANP defects in human motor neurons shows that GANP has a wide gene regulatory role in a disease-relevant cell type that requires long-distance mRNA transport.

neuroscience↗

bioRxiv2020

Deep Learning Identification of Stiffness Markers in Breast Cancer

While essential to our understanding of solid tumor progression, the study of cell and tissue mechanics has yet to find traction in the clinic. Determining tissue stiffness, a mechanical property known to promote a malignant phenotype in vitro and in vivo, is not part of the standard algorithm for the diagnosis and treatment of breast cancer. Instead, clinicians routinely use mammograms to identify malignant lesions and radiographically dense breast tissue is associated with an increased risk of developing cancer. Whether breast density is related to tumor tissue stiffness, and what cellular and non-cellular components of the tumor contribute the most to its stiffness are not well understood. Through training of a deep learning network and mechanical measurements of fresh patient tissue, we create a bridge in understanding between clinical and mechanical markers. The automatic identification of cellular and extracellular features from hematoxylin and eosin (H&E)-stained slides reveals that global and local breast tissue stiffness best correlate with the percentage of straight collagen. Global breast tissue mechanics correlate weakly with the percentage of blood vessels and fibrotic tissue, and non-significantly with the percentage of fat, ducts, tumor cells, and wavy collagen in tissue. Importantly, the percentage of dense breast tissue does not directly correlate with tissue stiffness or straight collagen content.

cancer biology↗

bioRxiv2020

Biochemical and Biophysical Characterization of the dsDNA packaging motor from the Lactococcus lactis bacteriophage asccphi28

Double-stranded DNA viruses package their genomes into pre-assembled protein procapsids. This process is driven by macromolecular motors that transiently assemble at a unique vertex of the procapsid and utilize homomeric ring ATPases to couple genome encapsidation to ATP hydrolysis. Here we describe biochemical and biophysical characterization of the packaging ATPase from Lactococcus lactis phage ascc{varphi}28. Size-exclusion chromatography, analytical ultracentrifugation, small angle x-ray scattering, and negative stain TEM indicate that the ~45 kDa protein formed a 443 kDa cylindrical assembly with a maximum dimension of ~155 [A] and radius of gyration of ~54 [A]. Together with the dimensions of the crystallographic asymmetric unit from preliminary X-ray diffraction experiments, these results indicate that gp11 forms a decameric D5-symmetric complex consisting of two pentameric rings related by 2-fold symmetry. Additional kinetic analysis shows that recombinantly expressed gp11 has ATPase activity comparable to that of functional ATPase rings assembled on procapsids in other genome packaging systems. Hence, gp11 forms rings in solution that likely reflect the fully assembled ATPases in active virus-bound motor complexes. Whereas ATPase functionality in other dsDNA phage packaging systems requires assembly on viral capsids, the ability to form functional rings in solution imparts gp11 with significant advantages for high resolution structural studies and rigorous biophysical/biochemical analysis.

biophysics↗

bioRxiv2020

Quantifying the acquisition and retention of lumpy skin disease virus by haematophagus insects and the implications for transmission and control.

Lumpy skin disease virus (LSDV), a poxvirus that causes severe disease in cattle, has in the last few years rapidly extended its distribution from Africa and the Middle East into Europe, Russia, and across Asia. LSDV is believed to be primarily spread mechanically by blood-feeding arthropods, however the exact mode of arthropod transmission, the relative ability of different arthropod species to acquire and retain the virus, as well as their comparative importance for LSDV transmission, remain poorly characterised. Since the vector-borne nature of LSDV transmission is believed to have enabled the rapid geographic expansion of this virus, the lack of quantitative evidence on LSDV transmission has impeded effective control of the disease during the current epidemic. Obtaining high quality data on virus transmission by arthropods is challenging, and practical limitations often result in inadequate arthropod numbers or model hosts, limiting the transferability of experimental findings to the natural transmission scenario. We have addressed these limitations in this study. Using a highly representative bovine experimental model of lumpy skin disease we allowed four representative vector species (Aedes aegypti, Culex quinquefasciatus, Stomoxys calcitrans and Culicoides nubeculosus) to blood-feed on LSDV-inoculated cattle in order to examine the acquisition and retention of LSDV by these species in unprecedented detail. We found the probability of LSDV transmission from clinical cattle to vector correlated with disease severity. Subclinical disease was more common than clinical disease in the inoculated cattle, however the probability of vectors acquiring LSDV from subclinical animals was very low. All four potential vector species studied had a similar rate of acquisition of LSDV after feeding on the host, but Aedes aegypti and Stomoxys calcitrans retained the virus for a longer time, up to 8 days. There was no evidence of virus replication in the vector, consistent with mechanical rather than biological transmission. The parameters obtained in the in-vivo transmission experiments subsequently enabled enhanced modelling approaches to determine the basic reproduction number of LSDV in cattle mediated by each of the insect species. This was highest for Stomoxys calcitrans (19.1), C. nubeculosus (7.4), and Ae. aegypti (2.4), surprisingly indicating these three species are all potentially efficient transmitters of LSDV. These results reveal that currently applied LSDV control measures such as stamping out of all cattle on affected premises or insect control measures targeting single species need to be urgently reconsidered. Overall our studies have highlighted that the combination of highly relevant in-vivo experiments and mathematical modelling can be directly applied to devise evidence-based proportionate and targeted control programmes.

microbiology↗

bioRxiv2020

MRI-guided histology of TDP-43 knock-in mice implicates parvalbumin interneuron loss, impaired neurogenesis and aberrant neurodevelopment in ALS-FTD

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are overlapping neurodegenerative diseases that are increasingly understood to have long prodromal periods. Investigation of these early stages promises to yield valuable biomarkers of disease and will be key to understanding mechanisms underlying the genesis of ALS-FTD. Here, we use in vivo magnetic resonance imaging (MRI), histology and computed tomography to identify structural and cellular readouts of early stage disease in the TDP-43Q331K knock-in mouse model of ALS-FTD. Adult mutant mice demonstrated parenchymal volume reductions affecting the frontal lobe and entorhinal cortex in a manner reminiscent of ALS-FTD. Subcortical, cerebellar and brain stem regions were also affected in line with observations in presymptomatic carriers of mutations in C9orf72, the commonest genetic cause of both ALS and FTD. Volume loss, as measured by MRI, was also observed in the dentate gyrus (DG) of the hippocampus, along with ventricular enlargement. Guided by these imaging findings, detailed post-mortem brain tissue analysis revealed reduced parvalbumin-positive (PV+) interneurons as a potential cellular correlate of MRI changes in mutant mice. By contrast, microglia were in a disease activated state even in the absence of brain volume loss. A reduction in immature neurons was found in the DG, indicative of impaired adult neurogenesis, while a paucity of PV+ interneurons in juvenile mutant mice (P14) suggests that TDP-43Q331K disrupts neurodevelopment. Computerised tomography imaging also showed altered skull morphology in mutants, further suggesting a role for TDP-43Q331K in development. Finally, analysis of human post-mortem prefrontal cortices confirmed a paucity of PV+ interneurons in the prefrontal cortex in cases with both sporadic ALS and ALS linked to C9orf72 mutations. This study suggests an important role for PV+ interneurons in regional brain vulnerability associated with ALS-FTD, and identifies novel MRI and histological biomarkers that will be of value in assessing the efficacy of putative therapeutics in TDP-43Q331K knock-in mice.

neuroscience↗