Biology subjects

Georgiou, C.

Publications and source records attributed to Georgiou, C..

10 recordsLinked to original sources

bioRxiv2026

A combined program of induced stemness and differentiation in response to interferon gamma drives acute myeloid leukaemia growth

How inflammation shapes acute myeloid leukaemia (AML) has come under scrutiny, as it may explain the disease resistance to immunotherapy approaches. IFNg has emerged as a key cytokine with paradoxical roles in suppressing and supporting AML growth, and the fundamental question of how leukemic stem cells (LSCs) respond to IFNg and whether IFNg signaling influences LSC quiescence and their capacity to regenerate disease over the long term remains unanswered. Here, we study primary human AML cells and murine models and combine bioinformatics analyses and functional assays to show that AML hierarchical heterogeneity is responsive to IFNg challenge. We uncover that IFNg triggers parallel stemness and differentiation programs; HSC/MPP-like cells enter deeper stemness, associated with quiescence and high leukaemia regeneration potential, while the surviving pool of progenitor-like cells divides faster but produces progeny that is quickly lost. Finally, with murine models we show that exposure to inflammation in vivo results in only transient impairment of leukaemia propagating capacity. This mechanism is driven by a previously unrecognised intraclonal fate bifurcation, relevant for the development of more effective therapeutic approaches.

cancer biology↗

bioRxiv2025

Single-cell and cell-type-level insights into stress-driven immune regulation relevant to disease

Environmental stress contributes to several disease conditions - including cardiovascular disease, mental illness, and autoimmune disorders - through immune dysregulation. Stress operates through the hypothalamic-pituitary-adrenal and sympathoadrenal axes, leading to peripheral secretion of cortisol and norepinephrine, respectively. While stress profoundly influences immune function, the underlying single-cell and cell-type-specific mechanisms remain poorly understood. To address this knowledge gap, we employed an ex vivo model investigating the transcriptomic responses of primary peripheral blood mononuclear cells and neutrophils to physiological stress levels (i.e., levels reached during in vivo stress) of cortisol and norepinephrine at single-cell resolution. We identified novel stress-hormone-dependent and cell-type-specific transcriptomic changes, including uniquely regulated genes and inflammation-related signatures within distinct innate (e.g., CD163+ monocytes/macrophages, neutrophils) and other immune cell types. The single-cell-derived signatures, applied to two independent human cohorts, effectively distinguished stress-related diseases. Our findings provide cell-type-level insights into how stress hormones modulate immune function relevant to stress-related conditions.

immunology↗

bioRxiv2025

A subset of Haematopoietic Stem Cells resists Plasmodium infection-induced stress by uncoupling interferon sensing and metabolic activation

Hematopoietic stem cells (HSCs) sustain lifelong haematopoiesis as their progeny differentiate into all blood cell lineages. Homeostatic HSCs are mostly quiescent and only rarely divide, however their proliferation and differentiation rates can be modulated by external factors. Acute and chronic infections from a wide range of pathogens are known to challenge HSCs at the population level, being forced to respond to inflammation-mediated organismal demand to replenish the myeloid cell pool. However, less is known about the degree of heterogeneity in the HSCs response to inflammation at the single cell level. Here, using a natural murine malaria model and an NHS-ester biotin dilution assay we identify two subsets of HSCs, BiotinLo and BiotinHi, with distinct proliferation kinetics. Using combined functional, single-cell transcriptomics and phenotypic analyses, we uncover that BiotinHi HSCs remain highly functional despite expressing strong interferon response signatures. These infection-resistant HSCs express high levels of MHC II and are metabolically distinct from the remaining HSCs as they maintain less active mitochondria. These findings demonstrate that a likely reserve pool of HSCs remains highly functional during Plasmodium infection not because cells are shielded, but because they maintain a stemness associated metabolic profile despite effectively sensing inflammation.

cell biology↗

bioRxiv2024

Differential responses and recovery dynamics of HSPC populations following Plasmodium chabaudi infection.

Severe infections such as malaria are on the rise worldwide, driven by both climate change and increasing drug-resistance. It is therefore paramount that we better understand how the hosts organism responds to severe infection. Hematopoiesis is particularly of interest in this context because hematopoietic stem and progenitor cells (HSPCs) maintain the turnover of all blood cells, including all immune cells. Severe infections have been widely acknowledged to affecting HSPCs, however this disruption has been mainly studied during the acute phase, and the process and level of HSPC recovery remains understudied. Using a self-resolving model of natural rodent malaria, infection by Plasmodium chabaudi, here we systematically assess HSPCs acute response and recovery upon pathogen clearance. We demonstrate that during the acute phase of infection the most quiescent and functional stem cells are depleted, multipotent progenitor compartments are drastically enlarged, and oligopotent progenitors virtually disappear, underpinned by dramatic, population-specific and sometimes unexpected changes in proliferation rates. HSPC populations return to homeostatic size and proliferation rate again through specific patterns of recovery. Overall, our data demonstrate that HSPC populations adopt different responses to cope with severe infection and suggest that the ability to adjust proliferative capacity becomes more restricted as differentiation progresses.

developmental biology↗

bioRxiv2024

SIRPalpha+ PD-L1+ bone marrow macrophages aid AML growth by modulating T cell function

Acute myeloid leukemia (AML) continues to have a poor prognosis due to its ability to relapse following initial response to chemotherapy. While immunotherapies hold the promise to revolutionize cancer treatment, AML has been particularly challenging to target. It is therefore important to better understand the relationship between AML cells and immune cells within the bone marrow (BM) microenvironment, where this disease grows. Here we focus on non-malignant BM macrophages, and using a combination of intravital microscopy, flow cytometry, transcriptomics and functional analyses we identify a subpopulation of immunomodulatory BM macrophages (IMMs) with a unique profile and function during AML progression. While the majority of macrophages are already being lost at early infiltration, IMMs are locally enriched. They are capable of efferocytosis and support AML growth through inhibition of T cells. Enrichment of IMMs in the BM of patients developing early relapse indicates that future development of interventions that target IMMs development and function may improve AML patients outcome.

cancer biology↗

bioRxiv2023

Mechanism of action of Vitamin D (1,25-(OH)2-D3) on ovarian follicle growth: implications for women with Vitamin D deficiency and PCOS

Numerous observational and interventional studies have investigated the link between Vitamin D (VD) deficiency and reproductive outcomes, with contradictory results. VD is known to regulate steroidogenic enzymes crucial for human granulosa and cumulus cell function and genes that play a critical role in folliculogenesis have a vitamin D response element (VDRE) on their promoters. This study investigated whether deficient levels of 1,25-(OH)2-D3 altered ovarian cell function; and if the ovary could obtain bioactive 1,25-(OH)2-D3 via local enzymatic expression of CYP27B1, to counteract systemic deficiency. A variety of cells and tissues were used for the in vitro experiments as practicable. We have shown for the first time an increase in VDR expression in theca of larger compared to smaller follicles, which along with the ability of 1,25-(OH)2-D3 to decrease Anti-Mullerian hormone (AMH) expression, supports a role for 1,25-(OH)2-D3 in theca and granulosa cell function. Conversely, we have shown that very levels of 1,25-(OH)2-D3 equivalent to hypovitaminosis, inhibited thecal production of androstenedione and cAMP-driven E2 production. Human thecal and unluteinised GC are incredibly hard to obtain for research purposes, highlighting the uniqueness of our data set. For the first time we have demonstrated that deficient levels of 1,25-(OH)2-D3 also down-regulated insulin receptor expression, potentially reducing insulin sensitivity. We have shown that the ovary expresses CYP27B1 allowing it to make local bioactive 1,25-(OH)2-D3 which along with the upregulation in VDR expression in all ovarian cellular compartments, could be protective locally in counteracting systemic VD deficiency. To conclude a severely deficient VD environment (<2nM or <1ng/ml) could contribute to impaired ovarian cell function and hence potentially affect folliculogenesis/ovulation, but levels associated with mild deficiency may have less impact, apart from in the presence of hyperinsulinemia and insulin resistance.

physiology↗

bioRxiv2020

Dynamic regulation of hierarchical heterogeneity in Acute Myeloid Leukemia serves as a tumor immunoevasion mechanism

Acute Myeloid Leukemia, a hematological malignancy with poor clinical outcome, is composed of hierarchically heterogeneous cells. We examine the contribution of this heterogeneity to disease progression in the context of anti-tumor immune responses and investigate whether these responses regulate the balance between stemness and differentiation in AML. Combining phenotypic analysis with proliferation dynamics and fate-mapping of AML cells in a murine AML model, we demonstrate the presence of a terminally differentiated, chemoresistant population expressing high levels of PDL1. We show that PDL1 upregulation in AML cells, following exposure to IFN{gamma} from activated T cells, is coupled with AML differentiation and the dynamic balance between proliferation, versus differentiation and immunosuppression, facilitates disease progression in the presence of immune responses. This microenvironment-responsive hierarchical heterogeneity in AML may be key in facilitating disease growth at the population level at multiple stages of disease, including following bone marrow transplantation and immunotherapy.

cancer biology↗

bioRxiv2019

Stretchable Composite Acoustic Transducer for Wearable Monitoring of Vital Signs

We report a highly flexible, stretchable, and mechanically robust low-cost soft composite consisting of silicone polymers and water (or hydrogels). When combined with conventional acoustic transducers, the materials reported enable high performance real-time monitoring of heart and respiratory patterns over layers of clothing (or furry skin of animals) without the need for direct contact with the skin. Our approach enables an entirely new method of fabrication that involves encapsulation of water and hydrogels with silicones and exploits the ability of sound waves to travel through the body. The system proposed outperforms commercial, metal-based stethoscopes for the auscultation of the heart when worn over clothing and is less susceptible to motion artefacts. We have tested the system both with human and furry animal subjects (i.e. dogs), primarily focusing on monitoring the heart, however, we also present initial results on monitoring breathing. Our work is especially important because it is the first demonstration of a stretchable sensor that is suitable for use with furry animals and do not require shaving of the animal for data acquisition.

bioengineering↗

bioRxiv2018

Atomic Level Characterisation of Millisecond-Time Scale Protein Motions through a Combined Molecular Simulations and NMR Approach

Proteins need to interconvert between many conformations in order to function, many of which are formed transiently, and sparsely populated. Particularly when the lifetimes of these states approach the millisecond timescale, identifying the relevant structures and the mechanism by which they inter-convert remains a tremendous challenge. Here we introduce a novel combination of accelerated MD (aMD) simulations and Markov State modelling (MSM) to explore these excited conformational states. Applying this to the highly dynamic protein CypA, a protein involved in immune response and associated with HIV infection, we identify five principally populated conformational states and the atomistic mechanism by which they interconvert. A rational design strategy predicted that the mutant D66A should stabilise the minor conformations and substantially alter the dynamics whereas the similar mutant H70A should leave the landscape broadly unchanged. These predictions are confirmed using CPMG and R1{rho} solution state NMR measurements. By accurately and reliably exploring functionally relevant, but sparsely populated conformations with milli-second lifetimes in silico, our aMD/MSM method has tremendous promise for the design of dynamic protein free energy landscapes for both protein engineering and drug discovery.

biophysics↗

bioRxiv2017

Pushing The Limits Of Detection Of Weak Binding Using Fragment Based Drug Discovery: Identification Of New Cyclophilin Binders

Fragment Based Drug Discovery (FBDD) is an increasingly popular method to identify novel small-molecule drug candidates. One of the limitations of the approach is the difficulty of accurately characterizing weak binding events. This work reports a combination of X-ray diffraction, surface plasmon resonance (SPR) experiments and molecular dynamics (MD) simulations, for the characterisation of binders to different isoforms of the cyclophilin (Cyp) protein family. Although several Cyp inhibitors have been reported in the literature, it has proven challenging to achieve high binding selectivity for different isoforms of this protein family. The present studies have led to the identification of several structurally novel fragments that bind to diverse Cyp isoforms in distinct pockets with low millimolar dissociation constants. A detailed comparison of the merits and drawbacks of the experimental and computational techniques is presented, and emerging strategies for designing ligands with enhanced isoform specificity are described.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=92 SRC=\"FIGDIR/small/136101_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (18K):\norg.highwire.dtl.DTLVardef@5d2d48org.highwire.dtl.DTLVardef@147f922org.highwire.dtl.DTLVardef@356562org.highwire.dtl.DTLVardef@1933853_HPS_FORMAT_FIGEXP M_FIG C_FIG Research Highlights O_LIFBDD is a popular method but weak binding is difficult to detect\nC_LIO_LIThere is a need for pushing the limits of weak binding detection\nC_LIO_LICombination of X-ray, SPR and MD methodologies increases successful characterization of weak binding events\nC_LIO_LISeveral novel Cyclophilin fragment binders were identified\nC_LI

biophysics↗