Biology subjects

Francis, S. E.

Publications and source records attributed to Francis, S. E..

6 recordsLinked to original sources

bioRxiv2026

Fisetin-mediated MYC restoration improves age-associated decline in macrophage function

Immune decline in older adults is associated with increased susceptibility to infection and chronic inflammatory diseases. Macrophages are critical innate immune cells that show reduced capacity for phagocytosis and migration with age. Our previous work shows that reduced levels of MYC and USF1 transcription factors are drivers of macrophage age-related functional decline. Here we show that macrophage-specific Myc overexpression improves macrophage migration and, more importantly, is able to improve physical performance at older age in Drosophila, while lifespan remains unaffected. Treatment of human primary macrophages from older individuals with the geroprotective supplement fisetin reverses the decline in MYC expression and improves phagocytosis of pathogens and cell migration functions towards levels seen in younger individuals. Mechanistically, fisetin acts via MYC, by restoring expression levels of MYC targets in human macrophages that are altered with age. Finally, fisetin feeding in older mice improves motor activity and reduces frailty, as well as restoring primary macrophage function and Myc expression in vitro. These findings reveal that restoration of MYC in macrophage ageing is responsible, at least in part, for improvement in physical performance with age and identify this pathway as a rational target to reverse age-related immune decline. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=185 SRC="FIGDIR/small/731325v1_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@1ab6731org.highwire.dtl.DTLVardef@3d85dorg.highwire.dtl.DTLVardef@71c2b3org.highwire.dtl.DTLVardef@a59bf3_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2025

TWIST1 drives endothelial-to-mesenchymal-transition to stabilize atherosclerotic plaques

Atherosclerosis progresses from fatty streaks to complex plaques, with rupture leading to life-threatening complications. Endothelial-to-mesenchymal transition (EndMT) is associated with advanced atherosclerotic plaques, but its role in plaque progression remains unclear. To investigate this, we analyzed the role of TWIST1, a key EndMT-driving transcription factor, in plaque development. Using single-cell RNA sequencing of atherosclerotic plaques from hypercholesterolemic mice with inducible deletion of Twist1 from endothelial cells (Twist1ECKO ApoE-/-) we demonstrate that Twist1 regulates endothelial cell heterogeneity by promoting cell states expressing EndMT markers. Cell tracking confirmed that Twist1 induces EndMT in advanced plaques. Mechanistically, we found that TWIST1 contributes to EndMT by promoting endothelial migration and proliferation through the transcriptional coactivator PELP1. Additionally, TWIST1 induces AEBP1 transcription, which upregulates COL4A1 to drive endothelial proliferation. Analyses of murine brachiocephalic plaques show that endothelial Twist1 promotes plaque growth, collagen deposition, and ACTA2-positive cell accumulation, hallmarks of plaque stability, while reducing necrosis and macrophage infiltration, features of plaque instability. Moreover, TWIST1 expression was associated with asymptomatic human carotid atherosclerosis and predicts favourable clinical outcomes. These findings challenge the prevailing view that EndMT destabilizes plaques, by suggesting that TWIST1-driven EndMT can promote plaque stability, offering new insights into atherosclerosis pathophysiology and therapeutic potential.

pathology↗

bioRxiv2020

Loss of PKCα increases arterial medial calcification in a uremic mouse model of chronic kidney disease

Arterial medial calcification is an independent risk factor for mortality in chronic kidney disease. We previously reported that knock-down of PKC expression increases high phosphate-induced mineral deposition by vascular smooth muscle cells in vitro. This new study tests the hypothesis that PKC regulates uremia-induced medial calcification in vivo. Female wild-type and PKC-/- mice underwent a two-stage subtotal nephrectomy and were fed a high phosphate diet for 8 weeks. X-ray micro computed tomography demonstrated that uremia-induced medial calcification was increased in the abdominal aorta and aortic arch of PKC-/- mice compared to wild-types. Blood urea nitrogen was also increased in PKC-/- mice compared to wild-types; there was no correlation between blood urea nitrogen and calcification in PKC-/- mice. Phosphorylated SMAD2 immunostaining was detected in calcified aortic arches from uremic PKC-/- mice; the osteogenic marker Runx2 was also detected in these areas. No phosphorylated SMAD2 staining were detected in calcified arches from uremic wild-types. PKC knock-down increased TGF-{beta}1-induced SMAD2 phosphorylation in vascular smooth muscle cells in vitro, whereas the PKC activator prostratin decreased SMAD2 phosphorylation. In conclusion, loss of PKC increases uremia-induced medial calcification. The PKC/TGF-{beta} signaling axis could therefore represent a new therapeutic target for arterial medial calcification in chronic kidney disease.

cell biology↗

bioRxiv2020

Neurovascular Function in a Novel Model of Experimental Atherosclerosis

ObjectiveAtherosclerosis is a major risk factor for dementia. The aims of this study were to determine if experimental atherosclerosis leads to altered neurovascular function and causes neurovascular damage. Approach and ResultsWe analysed cerebral blood volume in male C57BL6/J mice injected with an adeno-associated virus (AAV) vector for mutated proprotein convertase subtilisin/kexin type 9 (PCSK9D377Y) fed a Western diet for 35 weeks to induce atherosclerosis (ATH) and 9-12m male wild-type (WT) C57BL/6J. We imaged blood volume responses to sensory stimulation and vascular reactivity gas challenges in the cortex of the brain through a thinned cranial window using 2D-optical imaging spectroscopy (2D-OIS). Neural activity was also recorded with multi-channel electrodes. Stimulation-evoked cortical haemodynamics, in terms of cerebral blood volume, were significantly reduced in ATH mice compared to WT and evoked neural activity was also significantly lower. However, vascular reactivity as assessed by 10% hypercapnia, remained intact in ATH mice. Immunohistochemistry in ATH mice revealed a reduced number of cortical neurons and pericytes in the cortex, but increased astrogliosis. qRT-PCR revealed significantly enhanced TNF & IL1{beta} in ATH mice compared to WT as well as significant upregulation of eNOS. ConclusionSystemic atherosclerosis causes significant neurovascular decline by 9m in atherosclerotic mice characterised by reduced neural activity, associated with loss of neurons and subsequent reduced cortical haemodynamics in response to physiological stimulations. The altered neurovascular function in ATH mice is chiefly mediated by TNF. HighlightsO_LISystemic atherosclerosis leads to significantly reduced stimulus-evoked hemodynamic responses in the cortex by 9m of age in the rAAV8-mPCSK9-D377Y mouse model of atherosclerosis compared to wild-type controls. C_LIO_LIReduced cerebral haemodynamics are related to reduced neural activity in the cortex that could be due to a loss of cortical neurons potentially caused by significant TNFa-mediated neuroinflammation. C_LI

neuroscience↗

bioRxiv2019

Transforming growth factor-beta signaling via ALK1 and ALK5 regulates distinct functional pathways in vein graft intimal hyperplasia

RationaleTransforming growth factor-beta (TGF{beta}) is tightly regulated at multiple levels, with regulation at the receptor level now recognized as a key determinant of the cellular response to this pleiotropic cytokine. TGF{beta} promotes saphenous vein graft neointima formation after coronary artery bypass graft (CABG) surgery, inducing smooth muscle cell (SMC) hyperplasia and fibrosis by signaling via activin receptor-like kinase 5(ALK5). However, the role of the alternate TGF{beta} receptor ALK1 remains completely unknown. ObjectiveTo define the receptor pathways activated by TGF{beta} in SMCs and their mechanistic importance during CABG neointima formation. Methods and resultsRadioligand co-IP assays revealed direct interactions between TGF{beta}, ALK5 and ALK1 in primary saphenous vein graft SMC (HSVSMC) from patients undergoing CABG. Knockdown and pharmacological inhibition of ALK5 or ALK1 in HSVSMC significantly attenuated TGF{beta}-induced phosphorylation of receptor-regulated (R)-Smads 2/3 and 1/5, respectively. Microarray profiling followed by qRT-PCR validation showed that TGF{beta} induced distinct transcriptional networks downstream of ALK5 or ALK1, associated with HSVSMC contractility and migration, respectively and confirmed using migration assays as well as qRT-PCR and western blot assays of contractile SMC markers. scRNAseq analysis of TGF{beta}-treated HSVSMC identified distinct subgroups of cells showing ALK5 or ALK1 transcriptional responses, while RNA velocity analyses indicated divergence in differentiation towards ALK5 or ALK1-dominant lineages. ALK1, ALK5 and their downstream effectors pSmad1/5 and pSmad2/3 were localized to SMA+ neointimal SMCs in remodelled mouse vein grafts. Pharmacological inhibition or genetic ablation of Smad1/5 substantially reducing neointima formation following acute vascular injury. Notably, expression and activation of ALK1, ALK5 and their respective downstream R-Smads was already evident in hyperplastic saphenous veins prior to grafting. ConclusionsWhilst canonical TGF{beta} signaling via ALK5 promotes a contractile HSVSMC phenotype, transactivation of ALK1 by TGF{beta} induces neointima formation by driving cell migration. Restoring the balance between ALK1 and ALK5 in HSVSMC may represent a novel therapeutic strategy for vein graft failure.

cell biology↗

bioRxiv2019

Enhanced Cerebral Blood Volume under Normobaric Hyperoxia in the J20-hAPP Mouse Model of Alzheimer's Disease

Early impairments to neurovascular coupling have been proposed to be a key pathogenic factor in the onset and progression of Alzheimers disease (AD). Studies have shown impaired neurovascular function in several mouse models of AD, including the J20-hAPP mouse. In this study, we aimed to investigate early neurovascular changes using wild-type (WT) controls and J20-hAPP mice at 6-9 months of age, by measuring cerebral haemodynamics and neural activity to physiological sensory stimulations. A thinned cranial window was prepared to allow access to cortical vasculature and imaged using 2D-optical imaging spectroscopy (2D-OIS). After chronic imaging sessions where the skull was intact, a terminal acute imaging session was performed where an electrode was inserted into the brain to record simultaneous neural activity. We found that cerebral haemodynamic changes were significantly enhanced in J20-hAPP mice compared with controls in response to physiological stimulations, potentially due to the significantly higher neural activity (hyperexcitability) seen in the J20-hAPP mice. Thus, neurovascular coupling remained preserved under a chronic imaging preparation. Further, under hyperoxia, the baseline blood volume and saturation of all vascular compartments in the brains of J20-hAPP mice were substantially enhanced compared to WT controls, but this effect disappeared under normoxic conditions. This study highlights novel findings not previously seen in the J20-hAPP mouse model, and may point towards a potential therapeutic strategy by driving an increased baseline blood flow to the brain, thereby potentially enhancing the clearance of beta-amyloid.

neuroscience↗