Biology subjects

Lau, L.

Publications and source records attributed to Lau, L..

14 recordsLinked to original sources

bioRxiv2026

Medical-Grade Manuka Honey and Manuka Honey Extract Inhibit Mast Cell Degranulation through inhibition of MRGPRX2 expression: Potential Intravesical Agent for the Management of Interstitial Cystitis/Bladder Pain Syndrome?

RationaleNeurogenic inflammation is recognised as an important contributor to the pathophysiology of Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS). Substance P (Sub P), a neuropeptide released from sensory nerves, is a potent inducer of mast cell degranulation through the Mas-related G protein-coupled receptor member X2 (MRGPRX2), resulting in the release of pro-inflammatory mediators that perpetuate chronic bladder inflammation. Medihoney, a medical-grade M[a]nuka honey, possesses well-established antimicrobial and anti-inflammatory properties, and we have recently demonstrated its ability to stabilise mast cells through inhibition of histamine release. However, its effects on Sub P-induced mast cell activation and MRGPRX2-mediated neurogenic inflammation have not previously been investigated. Aim of the studyWe aimed to investigate the inhibitory effects of Medihoney and a sugar-free M[a]nuka honey extract on Substance P-induced mast cell degranulation and MRGPRX2 activation as potential therapeutic approaches for chronic neurogenic inflammation associated with IC/BPS. In addition, we examined the expression of MRGPRX2 in bladder biopsies from patients with IC/BPS. Materials and methodsHuman LAD2 mast cells were stimulated with Substance P (1 M) for 40 minutes following 20-minute pre-incubation with Medihoney or a sugar-free M[a]nuka honey extract. Mast cell degranulation was quantified by measuring {beta}-hexosaminidase release. MRGPRX2 activation was assessed by intracellular calcium imaging using Fluo-4 in MRGPRX2-expressing HEK-293 cells. Bladder biopsies obtained from patients with IC/BPS and healthy controls were immunostained for mast cell tryptase, chymase and MRGPRX2. ResultsMedihoney at 2% and 4% markedly inhibited Substance P-induced mast cell degranulation in LAD2 cells by approximately 90%, an effect that was similarly observed with the sugar-free M[a]nuka honey extract. Both preparations produced a dose-dependent inhibition of Substance P-induced intracellular signalling in MRGPRX2-expressing HEK-293 cells, demonstrating suppression of MRGPRX2 activation. Furthermore, immunohistochemical analysis of bladder biopsies revealed that approximately 66% of tryptase-positive mast cells expressed MRGPRX2 in patients with IC/BPS, which was significantly higher than that observed in healthy control tissues (25%). ConclusionThe present study demonstrates that mast cells within IC/BPS bladder tissue express increased levels of MRGPRX2, suggesting enhanced responsiveness to Substance P and supporting a role for neurogenic inflammation in the pathophysiology of IC/BPS. Medihoney and the sugar-free M[a]nuka honey extract significantly inhibit Substance P-induced mast cell degranulation through modulation of MRGPRX2-mediated intracellular signalling, highlighting their potential as novel therapeutic agents for reducing neurogenic bladder inflammation associated with IC/BPS. ImpactThis study provides evidence that MRGPRX2-mediated neurogenic mast cell activation is enhanced in IC/BPS and demonstrates, for the first time, that Medihoney and a sugar-free M[a]nuka honey extract effectively inhibit Substance P-induced mast cell degranulation through modulation of MRGPRX2 signalling. These findings provide new mechanistic insight into the anti-inflammatory actions of M[a]nuka honey-derived preparations and identify MRGPRX2 as a potential therapeutic target in IC/BPS. The observed inhibition of neurogenic mast cell activation suggests that these naturally derived preparations may offer a novel strategy for limiting chronic bladder inflammation. Overall, this work provides a foundation for future preclinical and clinical studies evaluating the safety and therapeutic efficacy of Medihoney and M[a]nuka honey-derived compounds in patients with IC/BPS.

immunology↗

bioRxiv2026

Medical Grade Manuka Honey Inhibits A23187 Induced Mast Cell Degranulation and Cytokine Release via Downregulation of the ERK Signalling Pathways

RationaleMast degranulation is a driver of several pathologies. Several endogenous peptides have been established as stimulators of mast cell degranulation. Compounds that stabilise mast cells have in part demonstrated inhibitory effect on the inflammatory cascade. Manuka honey has been widely used for the treatments of various inflammatory diseases. However, its effect on A23187 (Calcium ionophore) stimulated mast cell degranulation, cytokine release and cellular signalling pathways has not yet been investigated. Aim of the studyWe aim to investigate the effect of Medical Grade Manuka Honey (MGMH) on A23187 induced mast cell degranulation, cytokine release and downstream signalling pathways in a human mast cell lines LAD2 model. Materials and methodsThe cytotoxic effect of MGMH on LAD2 cells was assessed using LDH assay. LAD2 cells were pre-incubated with MGMH and challenged with A23187.Mast cell degranulation was measured by {beta}-hexosaminidase release whilst histamine and cytokines released were measured by ELISA. The effect of MGMH on downstream signalling of Mitogen Activated Protein Kinase (MAPK) pathways was determined and quantified by SDS-PAGE western blotting. ResultsMGMH at 2% and 4% was well tolerated by LAD2 cells. MGMH at all concentrations tested significantly inhibited the A23187 triggered release of {beta}-hexosaminidase but failed to inhibit the release of histamine. MGMH 4% significantly inhibited the release of GM-CSF and IL-8. MGMH (2% and 4%) significantly down regulated the expression of both ERK I and ERK II. However, MGMH at all the doses tested had no effect on the expressions of JNK and p38. On the contrary, an increase expression of these p38 and JNK were noted with MGMH pre-incubation. ConclusionOur present study provides evidence that MGMH inhibition of A23187 stimulated degranulation of mast cells and cytokine release through down regulation of ERK I and II signalling. The results suggest potential use as a mast cell stabiliser and effective treatments of mast cell mediated inflammatory diseases. ImpactThis study provides the first evidence that Medical Grade Manuka Honey (MGMH) can attenuate A23187-induced mast cell activation and pro-inflammatory cytokine release in human LAD2 mast cells through modulation of ERK1/2 signalling pathways. The findings advance our understanding of the cellular and molecular mechanisms underlying the anti-inflammatory properties of Manuka honey. The demonstration that MGMH inhibits {beta}-hexosaminidase release suggests a mast cell-stabilising effect, highlighting its potential as a novel natural therapeutic agent for mast cell-mediated disorders, including allergic diseases, interstitial cystitis, asthma, chronic inflammatory skin conditions, and mast cell activation syndromes. The observed reduction in GM-CSF and IL-8 production further indicates that MGMH may help limit the amplification and persistence of inflammatory responses. Mechanistically, the selective downregulation of ERK1/2 signalling provides new insight into how MGMH exerts its biological effects and identifies a potential molecular target through which its anti-inflammatory activity is mediated. These findings contribute to the growing evidence base supporting the therapeutic value of Manuka honey beyond its established antimicrobial and wound-healing properties. Overall, this work lays the foundation for future preclinical and clinical studies investigating MGMH as a safe, naturally derived mast cell stabiliser and anti-inflammatory intervention, with potential applications across a broad spectrum of allergic and inflammatory diseases.

immunology↗

bioRxiv2026

Integration of human and mouse single-cell transcriptomes of the developing cerebellum nominates cells-of-origin for Group 3 and 4 medulloblastoma

The cerebellar rhombic lip neurogenic niche is critical for glutamatergic neurogenesis, and dysregulated differentiation of rhombic lip lineage cells is hypothesized to cause medulloblastoma (MB), a malignant pediatric cancer lacking targeted therapies. Humans have an expanded rhombic lip subventricular zone compartment not seen in mice or macaques, and the common Group 4 subtype of MB is hypothesized to arise by dysregulation of the EOMES+ unipolar brush cells (UBC) generated by this compartment. However, it is unknown whether humans have unique UBC populations not seen in the mouse and, if so, whether Group 4 MB tumour cells resemble these UBC populations. We integrated 336,598 human and mouse single-cell transcriptomes of the developing cerebellum (9-21 post-conception weeks in humans and E10-P14 in mice) and identified two subpopulations of UBC that are enriched in the human samples, relative to mice. One of these populations, which we term UBC 1, predominates at 11 post-conception weeks, shows upregulation of the Eyes Shut Homolog (EYS) transcript, is predicted to be driven by OTX2, SOX4, and SOX11, and is enriched for axonogenesis and neurodifferentiation pathways. We analyzed 27,735 single-cell transcriptomes from eight MB tumours and recapitulated the observation that Group 4 MB cells best resemble UBC. We then found that two-thirds of Group 3 and Group 4 MB UBC-like cells best resemble human-enriched UBC 1 cells. Gene regulatory network analysis revealed that top regulators of Group 4 MB tumour cells include EOMES, SOX4, and SOX11. Our work provides initial evidence for human-enriched UBC states, and suggests that SOX4 and SOX11 may drive neurogenesis in UBC and gene expression in a subset of Group 4 MB tumour cells. Our findings shed light on genetic determinants of human cerebellar expansion and suggest that human models may be needed to recapitulate the oncogenesis of Group 3 and 4 MB.

genomics↗

bioRxiv2025

BRCA1 is a molecular correlate of cell proliferation in human brain development and in Group 3 and 4 medulloblastoma

The role of the BRCA1-mediated DNA damage repair pathway in regulating human brain development remains unknown, although it has been studied in mouse development. We report evidence for breast cancer type 1 susceptibility protein (BRCA1) being a molecular correlate of proliferation in human neural progenitor cells and in medulloblastoma (MB), a malignant pediatric hindbrain cancer whose cells resemble undifferentiated neural stem cells. In a computational search for molecules potentially keeping Group 3 (G3) and Group 4 (G4) MB tumour cells in a state of stalled differentiation, BRCA1 emerged as a leading candidate gene. We surveyed four independent transcriptomic datasets collectively spanning 142 human developing brain samples, multiple brain regions, and over 1.7 million single cells, and found that BRCA1 transcription is consistently enriched in human neural stem and progenitor cells, relative to differentiating or mature neurons. Across the human lifespan, BRCA1 expression is enriched in the brain during early development, particularly the first trimester of gestation. By analyzing 714 tumours, the largest transcriptomic survey of MB tumours to date, we found that BRCA1 expression is increased in carriers of isochromosome 17q (i17q) aberrations and in G4 MB tumours. Increased BRCA1 expression is associated with worse prognosis in G3 and G4 MB. In the developing cerebellum as well as in the cancer context, BRCA1 expression is correlated with transcription of the cell cycle and DNA damage repair pathways. When considered with previous mouse studies, our work is consistent with a model in which BRCA1 promotes genome surveillance in neural progenitors during human brain development and in G3 and G4 MB tumour growth, thus supporting proliferation.

genomics↗

bioRxiv2025

KDM5 demethylases suppress R-loop-mediated viral mimicry and DNA damage in breast cancer cells

Tumors with low expression of Interferon-Stimulated Genes (ISG) and Antigen Presentation (AP) genes respond relatively poorly to current immunotherapies. One of the early hallmarks of cancer is DNA hypomethylation in genomic repeat regions, resulting in the expression of normally silenced endogenous "viral" elements. Such epigenetic changes have the potential to augment anti-tumor immune responses as well as reduce tumor cell fitness through the generation of aberrant nucleic acid species (NAS) and consequent activation of NAS-sensing pathways. Therefore, tumor evolution should favor additional selective events that suppress NAS generation, possibly yielding specific therapeutic vulnerabilities. Here, we show that the Lysine Demethylase 5 (KDM5) family of epigenetic regulatory enzymes suppress R-loop formation in genomic repeat regions in cancer cells. We find that KDM5 inhibition in luminal breast cancer cells results in R-loop-mediated DNA damage, reduced cell fitness and an increase in ISG and AP signatures as well as cell surface Major Histocompatibility Complex (MHC) class I, mediated by RNA:DNA hybrid activation of the CGAS/STING pathway. KDM5 inhibition does not result in DNA damage or activation of the CGAS/STING pathway in normal breast epithelial cells, suggesting that KDM5 inhibitors may enable a wide therapeutic window in this setting, as compared to STING agonists or Type I Interferons. These findings provide new insights into the interplay between epigenetic regulation of genomic repeats, R-loop formation, innate immunity, and cell fitness in the context of cancer evolution and therapeutic vulnerability.

cancer biology↗

bioRxiv2024

Engineered paediatric tumours retain patient tumour genotype and phenotype for precision medicine.

Precision medicine for paediatric and adult cancers that includes drug sensitivity profiling, can identify effective therapies for individual patients. However, obtaining adequate biopsy samples for high-throughput (HTP) screening remains challenging, with tumours needing to be expanded in culture or patient-derived xenografts - this is time-consuming and often unsuccessful. Herein, we have developed paediatric patient-derived tumour models using an engineered extracellular matrix (ECM) tissue mimic hydrogel system and HTP 3D bioprinting. Gene expression analysis from neuroblastoma and sarcoma patients identified key components of the ECM in these tumour types. Engineered hydrogels with ECM-mimic peptides were used to create patient-specific tumour organoids, modelling tumour growth conditions. Expanded tumour organoids recapitulated the genetic and phenotypic characteristics of the original tumours and retained tumourgenicity. Screening of these models identified individualised drug sensitivities. Our approach offers a timely and clinically relevant technology platform for precision medicine in paediatric cancers, potentially transforming preclinical testing across cancer types.

cancer biology↗

bioRxiv2024

Downregulation of PIK3IP1/TrIP on T cells is controlled by TCR signal strength, PKC, and metalloprotease-mediated cleavage

The protein known as PI3K-interacting protein (PIK3IP1), or transmembrane inhibitor of PI3K (TrIP), is highly expressed by T cells and can modulate PI3K activity in these cells. Several studies have also revealed that TrIP is rapidly downregulated following T cell activation. However, it is unclear as to how this downregulation is controlled. Using a novel monoclonal antibody that robustly stains cell-surface TrIP, we demonstrate that TrIP is lost from the surface of activated T cells in a manner dependent on the strength of signaling through the T cell receptor (TCR) and specific downstream signaling pathways, in particular classical PKC isoforms. TrIP expression returns by 24 hours after stimulation, suggesting that it may play a role in resetting TCR signaling at later time points. We also provide evidence that ADAM family proteases are required for both constitutive and stimulation-induced downregulation of TrIP in T cells. Finally, by expressing truncated forms of TrIP in cells, we identify the region in the extracellular stalk domain of TrIP that is targeted for proteolytic cleavage.

cell biology↗

bioRxiv2023

Temporal dynamics and genomic programming of plasma cell fates

Affinity-matured plasma cells (PCs) of varying lifespans are generated through a germinal center (GC) response. The developmental dynamics and genomic programs of antigen-specific PC precursors remain to be elucidated. Using a model antigen, we demonstrate biphasic generation of PC precursors, with those generating long-lived bone marrow PCs preferentially produced in the late phase of GC response. Clonal tracing using scRNA-seq+BCR-seq in spleen and bone marrow compartments, coupled with adoptive transfer experiments, reveal a novel PC transition state that gives rise to functionally competent PC precursors. The latter undergo clonal expansion, dependent on inducible expression of TIGIT. We propose a model for the proliferation and programming of precursors of long-lived PCs, based on extended antigen encounters followed by reduced antigen availability.

immunology↗

bioRxiv2022

Lipocalin 2 upregulation mediates the detrimental effects of therapy-induced senescence in breast cancer cells.

The acquisition of novel detrimental cellular properties following exposure to cytotoxic drugs leads to aggressive and metastatic tumors that often translates into an incurable disease. While the bulk of the primary tumor is eliminated upon exposure to chemotherapeutic treatment, residual cancer cells and non-transformed cells within the host can engage a stable cell cycle exit program named senescence. Senescent cells secrete a distinct set of pro-inflammatory factors, collectively termed the senescence-associated secretory phenotype (SASP). Upon exposure to the SASP, cancer cells undergo cellular plasticity resulting in increased proliferation, migration and epithelial-to-mesenchymal transition. The molecular mechanisms by which the SASP regulates these pro-tumorigenic features are poorly understood. Here, we report that breast cancer cells exposed to the SASP strongly upregulate Lipocalin 2 (LCN2). Furthermore, we demonstrate that LCN2 is critical for SASP-induced increased migration in breast cancer cells, and its inactivation potentiates the response to chemotherapeutic treatment in mouse models of breast cancer. Finally, we show that neoadjuvant chemotherapy treatment leads to LCN2 upregulation in residual human breast tumors, and correlates with worse overall survival. These findings provide the foundation for targeting LCN2 as an adjuvant therapeutic approach to prevent the emergence of aggressive tumors following chemotherapy.

cancer biology↗

bioRxiv2021

Physiological activation of the nephron central command drives endogenous kidney tissue regeneration

Tissue regeneration is limited in several organs including the kidney, contributing to the high prevalence of kidney disease globally. However, evolutionary and physiological adaptive responses and the presence of renal progenitor cells suggest existing remodeling capacity. This study uncovered a novel endogenous tissue remodeling mechanism in the kidney that is activated by the loss of body fluid and salt and involves a unique niche of chief cells called macula densa (MD) that control resident progenitor cells via secreted angiogenic, growth and extracellular matrix remodeling factors, cytokines and chemokines. Serial intravital imaging, MD Wnt mouse models and transcriptome analysis provide functional and molecular characterization of this newly identified MD program for kidney regeneration complemented with human and therapeutic translation. The concept that chief cells responding to organ-specific physiological inputs control local progenitors and direct them to remodel or repair tissues may be applicable to other organs and diverse tissue regenerative therapeutic strategies.

physiology↗

bioRxiv2021

Restoration of BDNF-TrkB signaling rescues deficits in a mouse model of SCA6

Spinocerebellar ataxia type 6 (SCA6) is a neurodegenerative disease resulting in motor coordination deficits and cerebellar pathology. Expression of brain-derived neurotrophic factor (BDNF) is reduced in several neurodegenerative diseases, including in post-mortem tissue from SCA6 patients. Here, we show that cerebellar BDNF levels are reduced at an early disease stage in a mouse model of SCA6 (SCA684Q/84Q). One month of voluntary exercise was sufficient to elevate BDNF expression, as well as rescue both motor coordination and cerebellar Purkinje cell firing rate deficits. A BDNF mimetic, 7,8-dihydroxyflavone (7,8-DHF) likewise improved motor coordination and reversed Purkinje cell firing rate deficits, suggesting that exercise acts via BDNF-TrkB signaling. Prolonged chronic 7,8-DHF administration rescued ataxia when treatment commenced near disease onset, but was ineffective when treatment was started late. These data suggest that 7,8-DHF, which is orally bioavailable and crosses the blood-brain barrier, is a promising therapeutic for SCA6 and argue for the importance of early intervention for SCA6.

neuroscience↗

bioRxiv2020

Shear flow-driven actin re-organization induces ICAM-1 nanoclustering on endothelial cells that impact T-cell migration

The leukocyte specific {beta}2-integrin LFA-1, and its ligand ICAM-1 expressed on endothelial cells (ECs), are involved in the arrest, adhesion and transendothelial migration of leukocytes. Although the role of mechanical forces on LFA-1 activation is well established, the impact of forces on its major ligand ICAM-1, has received less attention. Using a parallel-plate flow chamber combined with confocal and super-resolution microscopy, we show that prolonged shear-flow induces a global translocation of ICAM-1 on ECs upstream of flow direction. Interestingly, shear-forces promoted ICAM-1 nanoclustering prior to LFA-1 engagement. This spatial nanoscale organization was driven by actin cytoskeleton re-arrangements induced by shear-force. We further assessed the impact of prolonged shear-stress EC stimulation on T cell migration. T cells adhered to mechanically pre-stimulated ECs developed a more pro-migratory phenotype, migrated faster and exhibited shorter EC interactions than when adhered to non-mechanically stimulated ECs. Together, our results indicate that shear-forces increase the number of ICAM-1/LFA-1 bonds due to ICAM-1 nanoclustering, strengthening adhesion and thereby reducing actin retrograde flow of T-cells, leading to their increased migration speed. Our data also underscores the importance of mechanical forces regulating the spatial organization of cell membrane receptors and their contribution to adhesion regulation, regardless of integrin activation. Summary statementWe show that shear forces promote ICAM-1 spatial re-arrangement and actin-dependent nanoclustering on ECs prior to integrin engagement. This mechanism might be important for firm leukocyte adhesion and migration during the immune response.

cell biology↗

bioRxiv2019

NAD+ repletion rescues female fertility during reproductive ageing

Female infertility is a common and devastating condition with life-long health, emotional and social consequences. There is currently no pharmacological therapy for preserving oocyte quality during aging, which is the strongest risk factor for infertility. This leads to an age dependent decline in natural conception and IVF success rates (1). Here, we show that this is due in part to declining levels of the metabolic cofactor nicotinamide adenine dinucleotide (NAD+), and that restoring NAD+ levels with its metabolic precursor nicotinamide mononucleotide (NMN) rejuvenates oocyte quality and quantity in aged animals, leading to improved fertility. These benefits extend to the developing embryo, where NMN supplementation in embryo culture media following IVF enhances blastocyst formation in older mice. The NAD+ dependent deacylase SIRT2 is sufficient, but not essential, to recapitulate the benefits of in vivo NMN treatment, and transgenic overexpression of SIRT2 maintains oocyte spindle assembly, accurate chromosome segregation, decreased oxidative stress and overall fertility with ageing. Pharmacological elevation of NAD+ may be an effective, non-invasive strategy for restoring and maintaining female fertility during ageing, and for improving the success of IVF.

developmental biology↗

bioRxiv2018

Proteomic Analysis of NRROS Interactome Reveals the Presence of Chaperones and Mediators of the ERAD Pathway

Negative regulator of reactive oxygen species (NRROS, previously called LRRC33) is a leucine-rich repeat (LRR) domain containing, ER-resident transmembrane protein expressed primarily in lymphoid organs, especially in myeloid cells. We have previously demonstrated that NRROS regulates reactive oxygen species production by phagocytic cells by mediating degradation of NOX2 (gp91phox), a component of NOX2 complex responsible for the oxidative burst in these cells. Since LRR is the only functional domain in NRROS, it is likely to interact with other proteins for its biological functions. Here, by performing immunoprecipitation of NRROS and mass spectrometric analysis, we describe the NRROS interactome in macrophages and demonstrate that NRROS interacts with molecular chaperones/co-chaperones and mediators of the endoplasmic reticulum associated degradation (ERAD) pathway such as calnexin, suggesting a broader role for NRROS in protein biosynthesis and the ER quality control machinery.

biochemistry↗