Biology subjects

Vande Velde, G.

Publications and source records attributed to Vande Velde, G..

13 recordsLinked to original sources

bioRxiv2026

Selected clinical strains of Mycobacterium avium unlock in vivo models for NTM drug discovery programs

Mycobacterium avium pulmonary disease is an emerging global health challenge for which drug development remains limited by preclinical models that rely on laboratory strains and invasive endpoint analyses. Here, we compared recent clinical M. avium isolates with the reference strain ATCC 700898 across macrophage, Galleria mellonella, and murine infection models and evaluated longitudinal micro-computed tomography ({micro}CT) as a non-invasive tool to monitor disease progression and treatment response. While extracellular growth rates were comparable, clinical isolates demonstrated enhanced host-associated fitness and induced higher bacterial burdens and more severe pulmonary pathology in mice than the reference strain. These strain-dependent differences were detected by quantitative {micro}CT imaging. Using the hypervirulent isolate MYC_0069, we further show that clarithromycin monotherapy and standard-of-care triple therapy significantly reduced bacterial burden and lung pathology. Together, these findings establish a clinically relevant chronic M. avium model that combines clinical isolates with longitudinal imaging to enable preclinical anti-mycobacterial drug evaluation in vivo.

microbiology↗

bioRxiv2024

Increased dosage of wild-type KRAS protein drives KRAS-mutant lung tumorigenesis and drug resistance

Almost 30% of lung adenocarcinomas are driven by activating KRAS mutations. The heterogeneous clinical behavior observed in these cancers could be due to the imbalance of wild-type and oncogenic KRAS alleles. However, the role of RAS dysregulation at the protein level needs to be further explored. A genome-wide global protein stability screen identified the CUL3 ubiquitin ligase adaptor LZTR1, as a major proteostatic regulator of wild-type but not mutant KRAS. In KRAS-mutant lung adenocarcinoma, shallow deletion of LZTR1 is observed in up to 50% of patients and is associated with hypoxic signatures and poorer progression-free disease survival. In a Kras-mutant lung cancer mouse model, heterozygous loss of Lztr1 promoted tumor growth, led to peritumoral vascular remodeling, and limited the response to the KRAS-G12D inhibitor MRTX1133. The vascular alteration in LZTR1-depleted lung cancer was mediated by increased wild-type KRAS protein dosage, which promoted mTOR pathway activation and a subsequent increase in VEGFA secretion. The inhibition of the PI3K/mTOR pathway using dactolisib normalized tumor vasculature, improved drug delivery, and overcame resistance to KRAS-G12D inhibitors. In summary, the dysregulation of RAS proteostasis contributes to lung tumorigenesis, and targeting wild-type KRAS signaling is crucial to overcome intrinsic resistance to inhibitors of mutant KRAS. SignificanceOur study highlights the impact of RAS proteostasis on lung cancer development and progression. Vascular normalization achieved by suppressing wild-type KRAS signaling improved the delivery and response to MRTX1133 in KRAS-mutant lung cancer with shallow LZTR1 deletion.

cancer biology↗

bioRxiv2023

Pleiotropic effects of trisomy and pharmacologic modulation on structural, functional, molecular, and genetic systems in a Down syndrome mouse model

Down syndrome (DS) is characterized by skeletal and brain structural malformations, cognitive impairment, altered hippocampal metabolite concentration and gene expression imbalance. These alterations were usually investigated separately, and the potential rescuing effects of green tea extracts enriched in epigallocatechin-3-gallate (GTE-EGCG) provided disparate results due to different experimental conditions. We overcame these limitations by conducting the first longitudinal controlled experiment evaluating genotype and GTE-EGCG prenatal chronic treatment effects before and after treatment discontinuation. Our findings revealed that the Ts65Dn mouse model reflected the pleiotropic nature of DS, exhibiting brachycephalic skull, ventriculomegaly, neurodevelopmental delay, hyperactivity, and impaired memory robustness with altered hippocampal metabolite concentration and gene expression. GTE-EGCG treatment modulated most systems simultaneously but did not rescue DS phenotypes. On the contrary, the treatment exacerbated trisomic phenotypes including body weight, tibia microarchitecture, neurodevelopment, adult cognition, and metabolite concentration, not supporting the therapeutic use of GTE-EGCG as a prenatal chronic treatment. Our results highlight the importance of longitudinal experiments assessing the co-modulation of multiple systems throughout development when characterizing preclinical models in complex disorders and evaluating the pleiotropic effects and general safety of pharmacological treatments.

systems biology↗

bioRxiv2023

Cardiopulmonary structural, functional and immune-alterations in a Down syndrome mouse model and upon modulation of EGCG

In individuals with Down syndrome (DS), cardiovascular and pulmonary diseases are the most common health problem and result in increased mortality and morbidity. Although these clinical comorbidities are well described, no preclinical models for DS are fully characterized for cardiopulmonary alterations, preventing research to understanding the development and pharmacological modulation of lungs, heart and immune system. Our objective is to characterize the cardiopulmonary and immunological phenotype in Ts65Dn mice and investigate the modulatory effects green tea extract enriched in epigallocatechin 3 gallate (GTE-EGCG). GTE-EGCG administration started at embryonic day 9 and was discontinued at postnatal day (PD) 180. Newborns were longitudinally monitored until PD210 using micro-computed tomography. At endpoint, we characterized the structural, functional and immunological alterations and persistent effects of GTE-EGCG administration. This study revealed normal lung development in the Ts65Dn mice and highlighted RV hypertrophy and immunological alterations. GTE-EGCG administration resulted in genotype-specific and genotype-independent alterations resulting in lung immaturation and airway hyperreactivity. Our results highlight the cardiovascular and immunological phenotype of Ts65Dn mice and potential use for safety studies of therapeutic agents in a DS-specific context. Summary statementThis study longitudinally follows respiratory and cardiac alterations in the Ts65Dn mouse model and describes the impact of prenatal EGCG modulation on the euploid and trisomic phenotype

systems biology↗

bioRxiv2022

CSF1R inhibition by PLX5622 reduces pulmonary fungal infection by depleting MHCIIhi interstitial lung macrophages

PLX5622 is a small molecular inhibitor of the CSF1 receptor (CSF1R) and is widely used to deplete macrophages within the central nervous system (CNS). However, recent reports have indicated that PLX5622 may affect myeloid cells in other organs including the bone marrow and spleen. We investigated the impact of PLX5622 treatment in wild-type C57BL/6 mice and discovered that one-week treatment with PLX5622 was sufficient to deplete interstitial macrophages in the lung and brain-infiltrating Ly6Clow patrolling monocytes, in addition to CNS-resident macrophages. These cell types were previously indicated to act as infection reservoirs for the pathogenic fungus Cryptococcus neoformans. We therefore took advantage of PLX5622-mediated depletion of these myeloid cell subsets to examine their functional role in C. neoformans lung infection and extrapulmonary dissemination. We found that PLX5622-treated mice had significantly reduced fungal lung infection and reduced extrapulmonary dissemination to the CNS but not to the spleen or liver. Fungal lung infection mapped to MHCIIhi interstitial lung macrophages, which underwent significant expansion during infection following monocyte replenishment and not local division. Although PLX5622 depleted CNS infiltrating patrolling monocytes, these cells did not accumulate in the fungal-infected CNS following pulmonary infection. In addition, Nr4a1-deficient mice, which lack patrolling monocytes, had similar control and dissemination of C. neoformans infection to wild-type controls. Our data demonstrate that PLX5622 may have a beneficial effect in the control of intracellular replicating pathogenic fungi that utilise CSF1R-dependent myeloid cells as infection reservoirs.

immunology↗

bioRxiv2022

Microglia protect fungi against copper starvation and promote brain infection

Microglia provide protection against a range of brain infections, but how these glial cells respond to fungi is poorly understood. We investigated the role of microglia in the context of cryptococcal meningitis, the most common cause of fungal brain infections in humans. Using a series of transgenic- and chemical-based microglia depletion methods we found that, contrary to their protective role during other infections, microglia supported cryptococcal fungal brain infection. We show that microglia become hosts for intracellular fungal growth and are a site in which the fungus accesses the restricted micronutrient copper. We developed a reporter fungal strain to track copper starvation responses by the fungus and found that yeast were protected from copper starvation within microglia. Lastly, we show that stimulation of microglia with IFN{gamma} causes restriction of phagosomal copper to intracellular fungi. These data provide a mechanistic explanation for why microglia depletion has a therapeutic effect in the context of this life-threatening fungal infection and is one of the few examples of microglia acting to promote infection. Our data demonstrate how tissue-resident phagocytes can support cryptococcal infections by acting as intracellular reservoirs and sites of microbial nutrient acquisition, and how these mechanisms may be blocked by IFN{gamma} immunotherapy.

immunology↗

bioRxiv2022

A bioluminescence-based ex vivo burn wound model for real-time assessment of novel antibacterial compounds

The silent pandemic of antibiotic resistance is thriving, prompting the urgent need for the development of new antibacterial drugs. However, within the preclinical pipeline, in vitro screening conditions can differ significantly from the final in vivo settings. To bridge the gap between in vitro and in vivo assays, we developed a pig skin-based bioluminescent ex vivo burn wound infection model, enabling real-time assessment of antibacterials in a longitudinal, non-destructive manner. We provide a proof-of-concept for A. baumannii NCTC13423, a multidrug-resistant clinical isolate, which was equipped with the luxCDABE operon as a reporter using a Tn7-based tagging system. This bioluminescence model provided a linear correlation between the number of bacteria and a broad dynamic range (104 to 109 CFU). This longitudinal model was subsequently validated using a fast-acting enzybiotic as an antibacterial. Since this model combines a realistic, clinically relevant yet strictly controlled environment with real-time measurement of bacterial burden, we put forward this ex vivo model as a valuable tool to assess the preclinical potential of novel antibacterial compounds. Summary statementHere, we demonstrate the potential of a bioluminescence-based ex vivo model for the longitudinal assessment of antibacterials. Moreover, we also provide a proof-of-concept with an engineered lysin.

molecular biology↗

bioRxiv2021

Drug development of an affinity enhanced, broadly neutralizing heavy chain only antibody that restricts SARS-CoV-2 in hamsters

We have identified camelid single-domain antibodies (VHHs) that cross-neutralize SARS-CoV-1 and -2, such as VHH72, which binds to a unique highly conserved epitope in the viral receptor-binding domain (RBD) that is difficult to access for human antibodies. Here, we establish a protein engineering path for how a stable, long-acting drug candidate can be generated out of such a VHH building block. When fused to human IgG1-Fc, the prototype VHH72 molecule prophylactically protects hamsters from SARS-CoV-2. In addition, we demonstrate that both systemic and intranasal application protects hACE-2-transgenic mice from SARS-CoV-2 induced lethal disease progression. To boost potency of the lead, we used structure-guided molecular modeling combined with rapid yeast-based Fc-fusion prototyping, resulting in the affinity-matured VHH72_S56A-Fc, with subnanomolar SARS-CoV-1 and -2 neutralizing potency. Upon humanization, VHH72_S56A was fused to a human IgG1 Fc with optimized manufacturing homogeneity and silenced effector functions for enhanced safety, and its stability as well as lack of off-target binding was extensively characterized. Therapeutic systemic administration of a low dose of VHH72_S56A-Fc antibodies strongly restricted replication of both original and D614G mutant variants of SARS-CoV-2 virus in hamsters, and minimized the development of lung damage. This work led to the selection of XVR011 for clinical development, a highly stable anti-COVID-19 biologic with excellent manufacturability. Additionally, we show that XVR011 is unaffected in its neutralizing capacity of currently rapidly spreading SARS-CoV-2 variants, and demonstrate its unique, wide scope of binding across the Sarbecovirus clades.

molecular biology↗

bioRxiv2021

Comparative infectivity and pathogenesis of emerging SARS-CoV-2 variants in Syrian hamsters

Within one year after its emergence, more than 108 million people contracted SARS-CoV-2 and almost 2.4 million succumbed to COVID-19. New SARS-CoV-2 variants of concern (VoC) are emerging all over the world, with the threat of being more readily transmitted, being more virulent, or escaping naturally acquired and vaccine-induced immunity. At least three major prototypic VoC have been identified, i.e. the UK (B.1.1.7), South African (B.1.351) and Brazilian (B.1.1.28.1), variants. These are replacing formerly dominant strains and sparking new COVID-19 epidemics and new spikes in excess mortality. We studied the effect of infection with prototypic VoC from both B.1.1.7 and B.1.351 lineages in Syrian golden hamsters to assess their relative infectivity and pathogenicity in direct comparison to two basal SARS-CoV-2 strains isolated in early 2020. A very efficient infection of the lower respiratory tract of hamsters by these VoC is observed. In line with clinical evidence from patients infected with these VoC, no major differences in disease outcome were observed as compared to the original strains as was quantified by (i) histological scoring, (ii) micro-computed tomography, and (iii) analysis of the expression profiles of selected antiviral and pro-inflammatory cytokine genes. Noteworthy however, in hamsters infected with VoC B.1.1.7, a particularly strong elevation of proinflammatory cytokines was detected. Overall, we established relevant preclinical infection models that will be pivotal to assess the efficacy of current and future vaccine(s) (candidates) as well as therapeutics (small molecules and antibodies) against two important SARS-CoV-2 VoC.

microbiology↗

bioRxiv2020

Antiviral treatment of SARS-CoV-2-infected hamsters reveals a weak effect of favipiravir and a complete lack of effect for hydroxychloroquine

SARS-CoV-2 rapidly spread around the globe after its emergence in Wuhan in December 2019. With no specific therapeutic and prophylactic options available, the virus was able to infect millions of people. To date, close to half a million patients succumbed to the viral disease, COVID-19. The high need for treatment options, together with the lack of small animal models of infection has led to clinical trials with repurposed drugs before any preclinical in vivo evidence attesting their efficacy was available. We used Syrian hamsters to establish a model to evaluate antiviral activity of small molecules in both an infection and a transmission setting. Upon intranasal infection, the animals developed high titers of SARS-CoV-2 in the lungs and pathology similar to that observed in mild COVID-19 patients. Treatment of SARS-CoV-2-infected hamsters with favipiravir or hydroxychloroquine (with and without azithromycin) resulted in respectively a mild or no reduction in viral RNA and infectious virus. Micro-CT scan analysis of the lungs showed no improvement compared to non-treated animals, which was confirmed by histopathology. In addition, both compounds did not prevent virus transmission through direct contact and thus failed as prophylactic treatments. By modelling the PK profile of hydroxychloroquine based on the trough plasma concentrations, we show that the total lung exposure to the drug was not the limiting factor. In conclusion, we here characterized a hamster infection and transmission model to be a robust model for studying in vivo efficacy of antiviral compounds. The information acquired using hydroxychloroquine and favipiravir in this model is of critical value to those designing (current and) future clinical trials. At this point, the data here presented on hydroxychloroquine either alone or combined with azithromycin (together with previously reported in vivo data in macaques and ferrets) provide no scientific basis for further use of the drug in humans.

microbiology↗

bioRxiv2020

STAT2 signaling as double-edged sword restricting viral dissemination but driving severe pneumonia in SARS-CoV-2 infected hamsters

Introductory paragraphSince the emergence of SARS-CoV-2 causing COVID-19, the world is being shaken to its core with numerous hospitalizations and hundreds of thousands of deaths. In search for key targets of effective therapeutics, robust animal models mimicking COVID-19 in humans are urgently needed. Here, we show that productive SARS-CoV-2 infection in the lungs of mice is limited and restricted by early type I interferon responses. In contrast, we show that Syrian hamsters are highly permissive to SARS- CoV-2 and develop bronchopneumonia and a strong inflammatory response in the lungs with neutrophil infiltration and edema. Moreover, we identify an exuberant innate immune response as a key player in pathogenesis, in which STAT2 signaling plays a dual role, driving severe lung injury on the one hand, yet restricting systemic virus dissemination on the other. Finally, we assess SARS-CoV- 2-induced lung pathology in hamsters by micro-CT alike used in clinical practice. Our results reveal the importance of STAT2-dependent interferon responses in the pathogenesis and virus control during SARS-CoV-2 infection and may help rationalizing new strategies for the treatment of COVID-19 patients.

microbiology↗

bioRxiv2019

Radiosafe micro-computed tomography for longitudinal evaluation of murine disease models

Implementation of in vivo high-resolution micro-computed tomography (CT), a powerful tool for longitudinal analysis of murine lung disease models, is hampered by the lack of data on cumulative low-dose radiation effects on the investigated disease models. We aimed to measure radiation doses and effects of repeated CT scans, to establish cumulative radiation levels and scan protocols without relevant toxicity. Lung metastasis, inflammation and fibrosis models and healthy mice were weekly scanned over one-month with CT using high-resolution respiratory-gated 4D and expiration-weighted 3D protocols, comparing 5-times weekly scanned animals with controls. Radiation dose was measured by ionization chamber, optical fiberradioluminescence probe and thermoluminescent detectors in a mouse phantom. Dose effects were evaluated by in vivo CT and bioluminescence imaging read-outs, gold standard endpoint evaluation and blood cell counts. Weekly exposure to 4D CT, dose of 540-699 mGy/scan, did not alter lung metastatic load nor affected healthy mice. We found a disease-independent decrease in circulating blood platelets and lymphocytes after repeated 4D CT. This effect was eliminated by optimizing a 3D protocol, reducing dose to 180-233 mGy/scan while maintaining equally high-quality images. We established CT safety limits and protocols for weekly repeated whole-body acquisitions with proven safety for the overall health status, lung, disease process and host responses under investigation, including the radiosensitive blood cell compartment.

physiology↗

bioRxiv2018

Epigallocatechin-3-Gallate Improves Facial Dysmorphology Associated with Down Syndrome

In Down syndrome (DS), the overall genetic imbalance caused by trisomy of chromosome 21 leads to a complex pleiotropic phenotype that involves a recognizable set of facial traits. Several studies have shown the potential of epigallocatechin-3-gallate (EGCG), a green tea flavanol, as a therapeutic tool for alleviating different developmental alterations associated with DS, such as cognitive impairment, skull dysmorphologies, and skeletal deficiencies. Here we provide for the first time experimental and clinical evidence of the potential benefits of EGCG treatment to facial morphology. Our results showed that mouse models treated with low dose of EGCG during pre- and postnatal development improved facial dysmorphology. However, the same treatment at high dose produced disparate facial morphology changes with an extremely wide and abnormal range of variation. Our observational study in humans revealed that EGCG treatment since early in development is associated with intermediate facial phenotypes and significant facial improvement scores. Overall, our findings suggest a potential beneficial effect of ECGC on facial development, which requires further research to pinpoint the optimal dosages of EGCG that reliably improve DS phenotypes. Current evidence warns against the non-prescribed intake of this supplement as a health-promoting measure.

pathology↗