Biology subjects

Izquierdo, E.

Publications and source records attributed to Izquierdo, E..

11 recordsLinked to original sources

bioRxiv2026

Cooperativity through Allee Effects drives growth of diffuse midline gliomas impacting the optimal scheduling of therapeutic interventions

Diffuse midline gliomas are a group of tumours for which no effective therapies exist. These tumours have substantial intratumoural heterogeneity and harbour beneficial subclonal interactions. Therapeutic failure due to resistance is a major concern in these tumours. We demonstrate how distinct subpopulations derived from the same tumour can interact with one another to alleviate the impacts of therapeutic intervention. This is achieved through the establishment of a mathematical extension to the Lotka-Volterra competition model, where interactions perturbing the Allee effect were demonstrated to exist. These interactions had substantial downstream consequences as they were determined to be perturbed by therapeutic interventions and strikingly, when simulating a two-drug paradigm, the interactions were demonstrated to substantially later the outcomes of treatment scheduling.

cancer biology↗

bioRxiv2026

Coumarins link rhizobacteria perception in roots to systemic resistance in leaves

Induced systemic resistance (ISR) is activated in leaves upon root colonization by beneficial microbes, yet the signals linking rhizosphere perception to shoot immunity remain unknown. In the Arabidopsis thaliana-Pseudomonas simiae WCS417 model interaction, the root-specific transcription factor MYB72 and its target gene BGLU42 regulate ISR and the production, activation, and root secretion of coumarins, specialized metabolites involved in plant iron (Fe) acquisition and rhizosphere microbiome assembly. Overexpression of BGLU42 confers constitutive ISR in leaves, suggesting a link between coumarin metabolism and systemic immunity. Here, two-photon multispectral imaging and targeted metabolite profiling revealed that, under Fe-sufficient conditions, WCS417 induces a distinct spatial pattern of F6H1-dependent coumarin accumulation along the root system. These WCS417-induced coumarin signatures differed from those observed under Fe deficiency, indicating activation of a microbiota-specific coumarin metabolic program. Increased coumarin accumulation in roots was followed by a rise in coumarin levels in shoots. Time-resolved transcriptome profiling supported this metabolic reprogramming, showing rapid activation of Fe acquisition and coumarin biosynthesis genes in roots, including F6H1, MYB72, and BGLU42, followed by delayed but similar transcriptional responses in shoots. Functional analyses demonstrated that coumarin biosynthesis is required for WCS417-ISR: the f6h1 mutant failed to mount systemic resistance, whereas F6H1 overexpression conferred constitutive resistance to bacterial and fungal pathogens. In addition, WCS417-mediated coumarin accumulation systemically modulated flg22-triggered reactive oxygen species production in leaves in an F6H1-dependent manner. Together, our results identify coumarins as key mediators linking rhizobacterial perception in roots to systemic immune signaling and resistance in leaves.

plant biology↗

bioRxiv2024

L-Phenylalanine is a metabolic checkpoint of human Th2 cells

After the primary response, circulating memory CD4+T effector and T regulatory cells (Treg) regulate recall responses, which are impaired in allergy. Using mass spectrometry, we discovered distinct metabolomes of these cells in humans and their unique enrichment in amino acids. By assessing energy metabolism in in vitro and ex vivo single-cell analyses, we determined that increased intracellular L-phenylalanine boosts glycolysis while limiting OXPHOS in CD4+T, memory CD4+T and Th2, but not in Treg cells. L-phenylalanine also restrains memory CD4+T proliferation in an IL4I1-dependent manner and inhibits Th2 cell proliferation and differentiation. RNA-sequencing, metabolomics, flow cytometry and proteomics, validated in vitro and across patients cohorts, revealed an impairment in LAT1-dependent transport of L-phenylalanine into Th2 cells in allergy with an increase in its intracellular processing, accompanied by an expansion of pathogenic Th2 cells. Thus, our study identifies L-phenylalanine as a checkpoint in the development, energy metabolism and function of Th2 cells.

immunology↗

bioRxiv2024

Autoregulation of cluster root and nodule development by white lupin CCR1 receptor-like kinase

Root development is controlled by local and systemic regulatory mechanisms that optimize mineral nutrient uptake and carbon allocation. The Autoregulation of Nodulation (AoN) pathway defines a negative regulation of nodule development in Legumes as a way to regulate the costly production of nitrogen-fixing organs. This pathway is defined as a response to symbiotic interaction and has been shown to also control root formation to some extent. However, it remains unclear if root and nodule development are under coordinated genetic regulation. Here, we identified mutants with altered root development in white lupin, constitutively producing specialized lateral roots called cluster roots. We showed that the CCR1 receptor-kinase negatively regulates cluster root and nodule development and targets common molecular modules such as NIN/LBD16-NFYA, defining a novel pathway that we named Autoregulation of Development (AoDev). AoDev defines a negative systemic pathway controlling several types of root organ development, independently of symbiotic partners and nutrient availability.

plant biology↗

bioRxiv2023

Pentose Phosphate Pathway Inhibition activates Macrophages towards phagocytic Lymphoma Cell Clearance

Macrophages in the B-cell lymphoma microenvironment represent a functional node in progression and therapeutic response. We assessed metabolic regulation of macrophages in the context of therapeutic antibody-mediated phagocytosis. Pentose phosphate pathway (PPP) inhibition by specific compounds and shRNA targeting induced increased phagocytic lymphoma cell clearance. Moreover, macrophages provided decreased support for survival of lymphoma cells. PPP inhibition induced metabolic activation, cytoskeletal re-modelling and pro-inflammatory polarization of macrophages. A link between PPP and immune regulation was identified as mechanism of macrophage repolarization. Inhibition of the PPP causes suppression of glycogen synthesis and subsequent modulation of the immune modulatory UDPG-Stat1-Irg1-Itaconate axis. PPP inhibition rewired macrophage maturation and activation in vivo. Addition of the PPP inhibitor S3 to antibody therapy achieved significantly prolonged overall survival in an aggressive B-cell lymphoma mouse model. We hypothesize the PPP as key regulator and targetable modulator of macrophage activity in lymphoma to improve efficacy of immunotherapies. HighlightsO_LIMacrophage-mediated lymphoma cell phagocytosis is increased by pentose phosphate pathway (PPP) inhibition as an immune regulatory switch for macrophage function and polarization C_LIO_LIPPP inhibition is linked to decreased glycogen synthesis and subsequent modulation of the UDPG-Stat1-Irg1-Itaconate axis C_LIO_LIPPP inhibition is tolerable in vivo and facilitates therapeutic targeting of B-cell lymphoma C_LI

cancer biology↗

bioRxiv2020

Drug screening linked to molecular profiling identifies novel dependencies in patient-derived primary cultures of paediatric high grade glioma and DIPG

Paediatric high grade glioma and diffuse midline glioma (including DIPG) are comprised of multiple biological and clinical subgroups, the majority of which urgently require novel therapies. Patient-derived in vitro primary cell cultures represent potentially useful tools for mechanistic and preclinical investigation based upon their retention of key features of tumour subgroups under experimental conditions amenable to high-throughput approaches. We present 17 novel primary cultures derived from patients in London, Dublin and Belfast, and together with cultures established or shared from Barcelona, Brisbane, Rome and Stanford, assembled a panel of 52 models under 2D (laminin matrix) and/or 3D (neurospheres) conditions, fully credentialed by phenotypic and molecular comparison to the original tumour sample (methylation BeadArray, panel/exome sequencing, RNAseq). In screening a subset of these against a panel of ~400 approved chemotherapeutics and small molecules, we identified specific dependencies associated with tumour subgroups and/or specific molecular markers. These included MYCN-amplified cells and ATM/DNA-PK inhibitors, and DIPGs with PPM1D activating truncating mutations and inhibitors of MDM2 or PARP1. Specific mutations in PDGFRA were found to confer sensitivity to a range of RTK inhibitors, though not all such mutations conferred sensitivity to targeted agents. Notably, dual PDGFRA/FGFR and downstream pathway MEK inhibitors showed profound effects against both PDGFRA-sensitising mutant and FGFR1-dependent non-brainstem pHGG and DIPG. In total, 85% cells were found to have at least one drug screening hit in short term assays linked to the underlying biology of the patients tumour, providing a rational approach for individualised clinical translation.

cancer biology↗

bioRxiv2020

Loss of TP53 mediates suppression of Macrophage Effector Function via Extracellular Vesicles and PDL1 towards Resistance against Chemoimmunotherapy in B-cell malignancies

Chemoimmunotherapy (CIT) is the standard of care in B-cell malignancies. It is relying on synergistic effects of alkylating chemotherapy and monoclonal antibodies via secretory crosstalk with effector macrophages. Here, we observed that loss of p53 function mediates resistance to CIT by suppressing macrophage phagocytic function. Loss of p53 leads to an upregulation of PDL1 and an increased formation of extracellular vesicles (EVs). EVs directly inhibit macrophage phagocytosis by PDL1 surface expression. Suppression of phagocytic function by lymphoma cell-derived EVs could be abrogated by pre-incubation of EVs with anti-PDL1 antibodies, CRISPR-KO of PDL1 and abrogation of EV formation by RAB27A-KO in lymphoma cells. Immune checkpoint inhibition represents a viable strategy to overcome EV-mediated resistance to chemoimmunotherapy in lymphoma. SignificanceLoss of TP53 mediates cell autonomous resistance to genotoxic chemotherapy, moreover non-cell autonomous effects may cause therapy resistance mediated by the tumor microenvironment. We identify a TP53-dependent mechanism that mediates resistance to synergistic chemoimmunotherapy by increasing formation of EVs and expression of the PDL1 immune checkpoint. PDL1 on EVs is directly responsible for macrophage suppression, preventing the exertion of the essential effector function of antibody-dependent cellular phagocytosis. This novel mechanism of resistance is in turn targetable by PDL1 checkpoint inhibition. Enhanced EV-release and immune checkpoint expression in lymphoma are novel mechanisms of macrophage modulation in the lymphoma microenvironment. We provide a novel principle of resistance to chemoimmunotherapy (CIT) representing of immediate relevance to treatment of refractory B-cell lymphoma. HighlightsO_LILoss of TP53 in B-cell lymphoma induces resistance towards chemoimmunotherapy (CIT) by inhibition of macrophage effector function through PDL1 upregulation C_LIO_LILoss of TP53 increases formation of extracellular vesicles (EVs) carrying PDL1 C_LIO_LIEVs inhibit antibody-mediated cellular phagocytosis (ADCP), a key macrophage effector function in CIT C_LIO_LITargeting PDL1 on EVs with immune checkpoint inhibitors overcomes TP53-mediated resistance to CIT C_LI

cell biology↗

bioRxiv2020

Macrophage-mediated antibody dependent effector function in aggressive B-cell lymphoma treatment is enhanced by Ibrutinib via inhibition of JAK2

Targeted inhibition of Brutons Tyrosine Kinase (BTK) with ibrutinib and other agents has become important treatment options in chronic lymphocytic leukemia, Waldenstroms Macroglobulinemia, Mantle cell lymphoma and non-GCB DLBCL. Clinical trials combining small molecule inhibitors with monoclonal antibodies have been initiated at rapid pace, with the biological understanding between their synergistic interactions lagging behind. Here, we have evaluated the synergy between BTK inhibitors and monoclonal antibody therapy via macrophage mediated antibody dependent cellular phagocytosis (ADCP). Initially, we observed increased ADCP with ibrutinib, whilst second generation BTK inhibitors failed to synergistically interact with monoclonal antibody treatment. Kinase activity profiling under BTK inhibition identified significant loss of Janus Kinase 2 (JAK2) only under ibrutinib treatment. We validated this potential off-target effect via JAK inhibition in vitro as well as with CRISPR/Cas9 JAK2-/- experiments in vivo, showing increased ADCP and prolonged survival, respectively. This data supports inhibition of the JAK-STAT signaling pathway in B-cell malignancies in combination with monoclonal antibody therapy to increase macrophage mediated immune responses.

cancer biology↗

bioRxiv2019

A neuromechanical model of multiple network oscillators for forward locomotion in C. elegans

Multiple mechanisms contribute to the generation, propagation, and coordination of the rhythmic patterns necessary for locomotion in Caenorhabditis elegans. Current experiments have focused on two possibilities: pacemaker neurons and stretch-receptor feedback. Here, we focus on whether it is possible that a chain of multiple network rhythmic pattern generators in the ventral nerve cord also contribute to locomotion. We use a simulation model to search for parameters of the anatomically constrained ventral nerve cord circuit that, when embodied and situated, can drive forward locomotion on agar, in the absence of pacemaker neurons or stretch-receptor feedback. Systematic exploration of the space of possible solutions reveals that there are multiple configurations that result in locomotion that is consistent with certain aspects of the kinematics of worm locomotion on agar. Analysis of the best solutions reveals that gap junctions between different classes of motorneurons in the ventral nerve cord can play key roles in coordinating the multiple rhythmic pattern generators.

neuroscience↗

bioRxiv2019

5-HT2B serotonin receptor agonist BW723C86 shapes the macrophage gene profile via AhR and impairs monocyte-to-osteoclast differentiation

Peripheral serotonin (5-HT) exacerbates or limits inflammatory pathologies through interaction with seven types of 5-HT receptors (5-HT1-7). As central regulators of inflammation, macrophages are critical targets of 5-HT, which promotes their anti-inflammatory and pro-fibrotic polarization primarily via the 5-HT7-Protein Kinase A (PKA) axis. However, anti-inflammatory human macrophages are also characterized by the expression of 5-HT2B, an off-target of anesthetics, anti-parkinsonian drugs and Selective Serotonin Reuptake Inhibitors (SSRI) that contributes to 5-HT-mediated pathologies. Since 5-HT2B prevents mononuclear phagocyte degeneration in amyotrophic lateral sclerosis and modulates motility of murine microglial processes, we sought to determine the functional and transcriptional consequences of 5-HT2B activation in human macrophages. Ligation of 5-HT2B by the 5-HT2B-specific agonist BW723C86, which exhibits antidepressant- and anxiolytic-like effects in animal models, significantly modified the cytokine profile and the transcriptional signature in macrophages. Importantly, 5-HT2B agonist-induced transcriptional changes were partly mediated through activation of the Aryl hydrocarbon Receptor (AhR), a ligand-dependent transcription factor that regulates immune responses and the biological responses to xenobiotics. Besides, BW723C86 triggered transcriptional effects that could not be abrogated by 5-HT2B antagonists and impaired monocyte-to-osteoclast differentiation by affecting the expression of negative (IRF8) and positive (PRDM1) regulators of osteoclastogenesis. Therefore, our results demonstrate the existence of a functional 5-HT2B-AhR axis in human macrophages and indicate that the commonly used 5-HT2B agonist BW723C86 exhibits 5-HT2B-independent effects. The 5-HT2B-AhR link extends the range of signaling pathways initiated upon 5-HT receptor engagement and identifies a point of convergence for endogenous and exogenous agents with ability to modulate inflammatory responses.\n\nKEY POINTS- The serotonin receptor 5-HT2B modifies the human macrophage transcriptome through activation of the Aryl Hydrocarbon Receptor.\n- BW723C86, an agonist used for 5-HT2B activation in vivo, exerts 5-HT2B-independent effects and limits monocyte osteoclastogenic potential.

immunology↗

bioRxiv2017

Development of a targeted sequencing approach to identify prognostic, predictive and diagnostic markers in paediatric solid tumours

The implementation of personalised medicine in childhood cancers has been limited by a lack of clinically validated multi-target sequencing approaches specific for paediatric solid tumours. In order to support innovative clinical trials in high-risk patients with unmet need, we have developed a clinically relevant targeted sequencing panel spanning 311 kb and comprising 78 genes involved in childhood cancers. A total of 132 samples were used for the validation of the panel, including Horizon Discovery cell blends (n=4), cell lines (n=15), formalin-fixed paraffin embedded (FFPE, n=83) and fresh frozen tissue (FF, n=30) patient samples. Cell blends containing known single nucleotide variants (SNVs, n=528) and small insertion-deletions (indels n=108) were used to define panel sensitivities of [≥]98% for SNVs and [≥]83% for indels [95% CI] and panel specificity of [≥]98% [95% CI] for SNVs. FFPE samples performed comparably to FF samples (n=15 paired). Of 95 well-characterised genetic abnormalities in 33 clinical specimens and 13 cell lines (including SNVs, indels, amplifications, rearrangements and chromosome losses), 94 (98.9%) were detected by our approach. We have validated a robust and practical methodology to guide clinical management of children with solid tumours based on their molecular profiles. Our work demonstrates the value of targeted gene sequencing in the development of precision medicine strategies in paediatric oncology.

genomics↗