Biology subjects

Marambaud, P.

Publications and source records attributed to Marambaud, P..

13 recordsLinked to original sources

bioRxiv2026

Cholinergic impairment in the dorsal motor nucleus of the vagus during experimental Alzheimer's disease

Cholinergic neurons in the dorsal motor nucleus of the vagus (DMN) in the brainstem are a key source of efferent vagus nerve fibers that regulate vital functions, including heart rate and inflammation. Whether the integrity of DMN cholinergic neurons is affected during Alzheimer's disease (AD) remains unknown. Here, in female and male mice with experimental AD (5xFAD), which exhibit age-dependent memory impairment, basal forebrain cholinergic neurodegeneration, and microglial alterations, we observe a reduction in cholinergic neuron density in the DMN at 6 and 10 months of age. Furthermore, while an important physiological function of DMN cholinergic signaling, such as suppression of heart rate, is preserved in control mice upon electrical DMN stimulation, the extent of suppression diminishes with age in both female and male 5xFAD mice. In addition, while electrical DMN stimulation lowers pro-inflammatory cytokine levels in control mice subjected to endotoxemia, this anti-inflammatory effect is diminished with age in 5xFAD mice, with females showing earlier dysfunction at 6 months. These results reveal previously unrecognized age-dependent cholinergic deficits in the DMN and disrupted brain - to - periphery vagus nerve circuits in experimental AD. These findings advance our understanding of AD mechanisms and are of interest for the development of conceptually novel therapies.

physiology↗

bioRxiv2026

Extracellular CIRP induces neurotoxic astrocytes via TREM-1 in Alzheimer's disease

Extracellular cold-inducible RNA-binding protein (eCIRP) is a crucial neuroinflammatory mediator in ischemic stroke and alcohol-induced memory impairment. We have recently discovered that amyloid{beta} causes microglia to release eCIRP, prompting us to investigate its role in Alzheimer's disease (AD). We found that eCIRP levels were significantly elevated in the cerebrospinal fluid (CSF) and plasma of AD patients compared with age-matched non-AD subjects, as well as in hTau.P301S mice (a model of AD tauopathy) compared with wildtype control mice. Plasma eCIRP strongly correlated with astrocyte activation marker glial fibrillary acidic protein (GFAP) in AD patients. eCIRP induced neurotoxic astrocyte-specific genes and astrocyte release of proinflammatory and neurotoxic factors in C8-D1a cells, primary murine astrocytes and intracerebroventricular eCIRP-injected C57BL/6 mice brains. In particular, eCIRP increased Complement 3, an astrocytic marker involved in neuroinflammation-associated neurodegeneration. Primary astrocytes from TREM-1 knockout mice were resistant to eCIRP induction of neurotoxic astrocytes. eCIRP increased TREM-1 expression and activation in astrocytes. Blocking CIRP/TREM-1 interaction using peptide M3, effectively attenuated eCIRP's induction of neurotoxic astrocytes. Thus, eCIRP strongly correlates with astrocyte reactivity in AD patients, and eCIRP induces neurotoxic astrocytes via TREM-1, which is attenuated by M3, suggesting a novel therapeutic opportunity to target neurotoxic astrocytes in AD.

neuroscience↗

bioRxiv2026

Nitazoxanide activates BMP9-ALK1-SMAD signaling cascade and improves HHT vascular pathology

ObjectiveHereditary hemorrhagic telangiectasia (HHT) is a vascular genetic disorder caused by endothelial cell dysfunction and characterized by telangiectasias and arteriovenous malformations (AVMs). HHT results primarily from loss-of-function mutations affecting components of the BMP9-ALK1-ENG-SMAD signaling cascade, a pathway essential for endothelial quiescence and vascular homeostasis, and currently lacks a cure. Here, we investigated whether nitazoxanide, an orally bioavailable drug with extensive clinical use, can modulate endothelial signaling relevant to HHT. Approach and ResultsNitazoxanide treatment activated SMAD1/5/8 signaling and increased expression of the downstream target ID1 in endothelial cells, while concurrently inhibiting mTOR signaling, indicating a dual modulatory effect on pathways implicated in HHT pathogenesis. In vivo, nitazoxanide activated SMAD signaling in BMP9/10-immunoblocked mice and significantly reduced AVM formation and hypervascularization. Importantly, nitazoxanide restored SMAD1/5/8 activation and ID1 expression in patient-derived blood outgrowth endothelial cells harboring loss-of-function mutations in ALK1 or SMAD4, which exhibit impaired BMP signaling. ConclusionThese findings identify nitazoxanide as a pharmacological modulator capable of activating BMP-SMAD signaling while restraining mTOR activity, thereby overcoming key signaling defects in HHT endothelial cells. Collectively, our results highlight nitazoxanide as a promising therapeutic candidate to target endothelial dysfunction in HHT.

cell biology↗

bioRxiv2025

An angiopoietin-2 vaccine improves arteriovenous malformation pathology in hereditary hemorrhagic telangiectasia mice

Hereditary hemorrhagic telangiectasia (HHT) is a genetic vascular disorder that causes systemic arteriovenous malformations (AVMs) associated with severe complications. Angiopoietin (ANG)-2 has been identified as a consistently upregulated secreted protein across various HHT models, and neutralizing ANG2 reduces AVMs in mice. ANG2 has thus emerged as a potential target for HHT treatment. Here, we report the development of a peptide vaccine (ANG2-P3:CRM197) that selectively targets ANG2 over ANG1 and tested its effectiveness in decreasing retinal AVMs in neonatal mice injected with BMP9/10 blocking antibodies, a model of HHT. Litter groups from female C57BL/6 mice immunized with ANG2-P3:CRM197 received injections of anti-BMP9/10 antibodies, and their retinas were examined for vascular pathology. The potential toxicity of the vaccine was evaluated in females 12 months post-immunization through echocardiography, basic metabolic panels, and lipid profiles. Circulating anti-ANG2 antibodies were detected in nursing neonates of vaccinated females, with antibody levels comparable between litters and their dams, indicating effective antibody transfer from the dams. A significant decrease in AVM number and size was observed in the retinas of pups exposed to ANG2-P3:CRM197 antibodies compared to unexposed pups. Arterial and venous diameters were normalized in the vaccinated pups retinas. The vaccinated females showed no abnormalities in cardiac, liver, or kidney functions. A vaccine strategy targeting ANG2 appears safe and improves AVM pathology in HHT mice. These findings further support the potential of inhibiting ANG2 as a viable approach for treating AVMs in HHT. KEY POINTSO_LIA peptide vaccine that targets ANG2 reduced AVM number and size, and normalized arterial and venous diameters in a mouse model of HHT. C_LIO_LIThe vaccine did not cause any abnormalities in cardiac, liver, or kidney functions, and thus appeared safe. C_LI

cell biology↗

bioRxiv2025

ALK1-BMPRII agonism by clustering bispecific antibodies treats hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is characterized by arteriovenous malformations (AVMs) and severe bleeding caused by loss-of-function mutations in the ALK1 receptor pathway. We developed clustering agonist bispecific antibodies (BsAbs) targeting ALK1 and its activating partner, the Ser/Thr receptor kinase BMPRII. These BsAbs induced ALK1-BMPRII proximity association, stimulated the downstream Smad1/5/8 signaling cascade, and treated HHT pathologies in various mouse models. BsAb treatment reduced AVM burden by up to 95% in HHT mice, preventing anemia, cardiomegaly, and premature death. The BsAbs also enhanced Smad1/5/8 signaling in endothelial cells derived from HHT patients with ALK1 mutations and prevented retinal AVMs in a newly developed knock-in mouse carrying an HHT-causing ALK1 mutation. These findings establish ALK1-BMPRII agonism as a promising therapeutic strategy for HHT.

cell biology↗

bioRxiv2025

AAV-mediated peripheral single chain variable fragments administration to reduce cerebral tau in adult P301S transgenic mice: mono- vs combination therapy

Tau is a primary target for immunotherapy in Alzheimers disease. Recent studies have shown the potential of anti-tau fragment antibodies in lowering pathological tau levels in vitro and in vivo. Here, we compared the effects of single-chain variable fragments (scFv) derived from the well-characterized monoclonal antibodies PHF1 and MC1. We used adeno-associated virus 1 (AAV1) to deliver scFvs to skeletal muscle cells in eight-week-old P301S tau transgenic mice. We evaluated motor and behavioral functions at 16 and 23 weeks of age and measured misfolded, soluble, oligomeric and insoluble brain tau species. Monotherapy with scFv-MC1 improved motor and behavioral functions more effectively than scFv-PHF1 or combination therapy. Brain glucose metabolism also benefited from scFv-MC1 treatment. Surprisingly, combining scFvs targeting early (MC1) and late (PHF1) tau modifications did not produce additive or synergistic effects. These results confirm that intramuscular AAV1-mediated scFv-MC1 gene therapy holds promise as a potential treatment for Alzheimers disease. Our findings also suggest that combining scFvs targeting different tau epitopes may not necessarily enhance efficacy if administered together in a prevention paradigm. Further research is needed to explore whether other antibodies combinations and/or administration schedules could improve the efficacy of scFv-MC1 alone. Graphical abstract/eTOC synopsisKatel and colleagues show that peripheral vectorized scFvMC1 (in monotherapy) reduces pathological tau species in tau transgenic mice more efficiently than in combination with scFv-PHF1. The authors observed improved motor and behavioral functions together with increased brain glucose metabolism in scFv-MC1-treated mice. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=136 SRC="FIGDIR/small/638144v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@7edcccorg.highwire.dtl.DTLVardef@d1fc50org.highwire.dtl.DTLVardef@bf6f8org.highwire.dtl.DTLVardef@1832331_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2023

CDK6-mediated endothelial cell cycle acceleration drives arteriovenous malformations in hereditary hemorrhagic telangiectasia

Increased endothelial cell (EC) proliferation is a hallmark of arteriovenous malformations (AVMs) in hereditary hemorrhagic telangiectasia (HHT). The underlying mechanism and disease relevance of this abnormal cell proliferative state of the ECs remain unknown. Here, we report the identification of a CDK6-driven mechanism of cell cycle progression deregulation directly involved in EC proliferation and HHT vascular pathology. Specifically, HHT mouse liver ECs exhibited defects in their cell cycle control characterized by a G1/S checkpoint bypass and acceleration of cell cycle speed. Phosphorylated retinoblastoma (p-RB1)--a marker of G1/S transition through the restriction point--significantly accumulated in ECs of HHT mouse retinal AVMs and HHT patient skin telangiectasias. Mechanistically, ALK1 loss of function increased the expression of key restriction point mediators, and treatment with palbociclib or ribociclib, two CDK4/6 inhibitors, blocked p-RB1 increase and retinal AVMs in HHT mice. Palbociclib also improved vascular pathology in the brain and slowed down endothelial cell cycle speed and EC proliferation. Specific deletion of Cdk6 in ECs was sufficient to protect HHT mice from AVM pathology. Thus, CDK6-mediated endothelial cell cycle acceleration controls EC proliferation in AVMs and is a central determinant of HHT pathogenesis. We propose that clinically approved CDK4/6 inhibitors have repurposing potential in HHT.

cell biology↗

bioRxiv2022

Oxidative stress-induced MMP- and γ-secretase-dependent VE-cadherin processing is modulated by the proteasome and BMP9/10

Classical cadherins, including vascular endothelial (VE)-cadherin, are targeted by matrix metalloproteinases (MMPs) and {gamma}-secretase during adherens junction (AJ) disassembly, a mechanism that might have relevance for endothelial cell (EC) integrity and vascular homeostasis. Here, we show that oxidative stress triggered by H2O2 exposure induced efficient VE-cadherin proteolysis by MMPs and {gamma}-secretase in human umbilical endothelial cells (HUVECs). The cytoplasmic domain of VE-cadherin produced by {gamma}-secretase, VE-Cad/CTF2 - a fragment that has eluded identification so far - could readily be detected after H2O2 treatment. VE-Cad/CTF2, released into the cytosol, was tightly regulated by proteasomal degradation and was sequentially produced from an ADAM10/17-generated C-terminal fragment, VE-Cad/CTF1. Interestingly, BMP9 and BMP10, two circulating ligands critically involved in vascular maintenance, significantly reduced VE-Cad/CTF2 levels during H2O2 challenge, as well as mitigated H2O2-mediated actin cytoskeleton disassembly during VE-cadherin processing. Notably, BMP9/10 pretreatments efficiently reduced apoptosis induced by H2O2, favoring endothelial cell recovery. Thus, oxidative stress is a trigger of MMP- and {gamma}-secretase-mediated endoproteolysis of VE-cadherin and AJ disassembly from the cytoskeleton in ECs, a mechanism that is negatively controlled by the EC quiescence factors, BMP9 and BMP10.

cell biology↗

bioRxiv2022

Limb Specific Failure of Proliferation and Translation in the Mesenchyme Leads to Skeletal Defects in Diamond Blackfan Anemia

AbstractRibosomopathies are a class of disorders caused by defects in the structure or function of the ribosome and characterized by tissue-specific abnormalities. Diamond Blackfan anemia (DBA) arises from different mutations, predominantly in genes encoding ribosomal proteins (RPs). Apart from the anemia, skeletal defects are among the most common anomalies observed in patients with DBA, but they are virtually restricted to radial ray and other upper limb defects. What leads to these site-specific skeletal defects in DBA remains a mystery. Using a novel mouse model for RP haploinsufficiency, we observed specific, differential defects of the limbs. Using complementary in vitro and in vivo approaches, we demonstrate that reduced WNT signaling and subsequent increased {beta}-catenin degradation in concert with increased expression of p53 contribute to mesenchymal lineage failure. We observed differential defects in the proliferation and differentiation of mesenchymal stem cells (MSCs) from the forelimb versus the hind limbs of the RP haploinsufficient mice that persisted after birth and were partially rescued by allelic reduction of Trp53. These defects are associated with a global decrease in protein translation in RP haploinsufficient MSCs, with the effect more pronounced in cells isolated from the forelimbs. Together these results demonstrate translational differences inherent to the MSC, explaining the site-specific skeletal defects observed in DBA.

cell biology↗

bioRxiv2019

Sirolimus plus nintedanib treats vascular pathology in HHT mouse models

Hereditary hemorrhagic telangiectasia (HHT), a genetic bleeding disorder leading to systemic arteriovenous malformations (AVMs), is caused by loss-of-function mutations in the ALK1-ENG-Smad1/5/8 pathway. Evidence suggests that HHT pathogenesis strongly relies on overactivated PI3K-Akt-mTOR and VEGFR2 pathways in endothelial cells (ECs). In the BMP9/10-immunoblocked (BMP9/10ib) neonatal mouse model of HHT, we report here that the mTOR inhibitor, sirolimus, and the receptor tyrosine-kinase inhibitor, nintedanib, could synergistically fully block, but also reversed, retinal AVMs to avert retinal bleeding and anemia. Sirolimus plus nintedanib prevented vascular pathology in the oral mucosa, lungs, and liver of the BMP9/10ib mice, as well as significantly reduced gastrointestinal bleeding and anemia in inducible ALK1-deficient adult mice. Mechanistically, in vivo in BMP9/10ib mouse ECs, sirolimus and nintedanib blocked the overactivation of mTOR and VEGFR2, respectively. Furthermore, we found that sirolimus activated ALK2-mediated Smad1/5/8 signaling in primary ECs--including in HHT patient blood outgrowth ECs--and partially rescued Smad1/5/8 activity in vivo in BMP9/10ib mouse ECs. These data demonstrate that the combined correction of endothelial Smad1/5/8, mTOR, and VEGFR2 pathways opposes HHT pathogenesis. Repurposing of sirolimus plus nintedanib might provide therapeutic benefit in HHT patients.

cell biology↗

bioRxiv2017

Tacrolimus Rescues Endothelial ALK1 Loss-Of-Function Signaling And Improves HHT Vascular Pathology

Hereditary hemorrhagic telangiectasia (HHT) is a genetic vascular disorder arising from endothelial cell (EC) proliferation and hypervascularization, for which no cure exists. Because HHT is caused by loss-of-function mutations in BMP9-ALK1-Smad1/5/8 signaling, interventions aimed at activating this pathway are of therapeutic value. By screening FDA-approved drug libraries, we identified tacrolimus (FK-506) as a potent activator of Smad1/5/8 in BMP9-challenged reporter cells. In primary ECs, tacrolimus activated Smad1/5/8 to oppose the pro-angiogenic gene expression signature associated with ALK1 loss-of-function, by notably reducing Dll4 expression. In these cells, tacrolimus also inhibited Akt and p38 stimulation by VEGF. In the BMP9/10-immunodepleted postnatal retina--a mouse model of HHT vascular pathology--tacrolimus activated endothelial Smad1/5/8 and prevented the Dll4 overexpression and hypervascularization associated with this model. Finally, tacrolimus stimulated Smad1/5/8 in cells transfected with BMP9-unresponsive ALK1 HHT mutants and in HHT patient blood outgrowth ECs. We propose that tacrolimus repurposing has therapeutic potential in HHT.

cell biology↗

bioRxiv2016

A modification-specific peptide-based immunization approach using CRM197 carrier protein: Development of a selective vaccine against pyroglutamate Aβ peptides

Strategies aimed at reducing cerebral accumulation of the amyloid-{beta} (A{beta}) peptides have therapeutic potential in Alzheimers disease (AD). A{beta} immunization has proven to be effective at promoting A{beta} clearance in animal models but adverse effects have hampered its clinical evaluation. The first anti-A{beta} immunization clinical trial, which assessed a full-length A{beta}1-42 vaccine, increased the risk of encephalitis most likely because of autoimmune pro-inflammatory T helper 1 (Th1) response against all forms of A{beta}. Immunization against less abundant but potentially more pathologically relevant A{beta} products, such as N-terminally-truncated pyroglutamate-3 A{beta} (A{beta}pE3), could provide efficacy and improve tolerability in A{beta} immunotherapy. Here, we describe a selective vaccine against A{beta}pE3 using the diphtheria toxin mutant CRM197 as carrier protein for epitope presentation. CRM197 is currently used in licensed vaccines and has demonstrated excellent immunogenicity and safety in humans. In mice, our A{beta}pE3:CRM197 vaccine triggered the production of specific anti-A{beta}pE3 antibodies that did not cross-react with A{beta}1-42, non-cyclized A{beta}E3, or N-terminally-truncated pyroglutamate-11 A{beta} (A{beta}pE11). A{beta}pE3:CRM197 antiserum strongly labeled A{beta}pE3 in insoluble protein extracts and decorated cortical amyloid plaques in human AD brains. Anti-A{beta}pE3 antibodies were almost exclusively of the IgG1 isotype, suggesting an anti-inflammatory Th2 response bias to the A{beta}pE3:CRM197 vaccine. To the best of our knowledge, this study shows for the first time that CRM197 has potential as a safe and suitable vaccine carrier for active and selective immunization against specific protein sequence modifications or conformations, such as A{beta}pE3.

neuroscience↗

bioRxiv2016

A mouse model of hereditary hemorrhagic telangiectasia generated by transmammary-delivered immunoblocking of BMP9 and BMP10

Hereditary hemorrhagic telangiectasia (HHT) is a potentially life-threatening genetic vascular disorder caused by loss-of-function mutations in the genes encoding activin receptor-like kinase 1 (ALK1), endoglin, Smad4, and bone morphogenetic protein 9 (BMP9). Injections of mouse neonates with BMP9/10 blocking antibodies lead to HHT-like vascular defects in the postnatal retinal angiogenesis model. Mothers and newborns share the same immunity through the transfer of maternal antibodies during breastfeeding. Here, we investigated whether the transmammary delivery route could improve the ease and consistency of administering anti-BMP9/10 antibodies in the postnatal retinal angiogenesis model. We found that anti-BMP9/10 antibodies, when intraperitoneally injected into lactating dams, are efficiently transferred into the circulation of breastfed neonatal pups. Strikingly, pups receiving anti-BMP9/10 antibodies via breastfeeding displayed consistent and robust vascular pathology in the retina, which included hypervascularization and defects in arteriovenous specification, as well as the presence of multiple and massive arteriovenous malformations. Furthermore, RNA-Seq analyses of neonatal retinas identified an increase in the key pro-angiogenic factor, angiopoietin-2, as the most significant change in gene expression triggered by the transmammary delivery of anti-BMP9/10 antibodies. Transmammary-delivered BMP9/10 immunoblocking in the mouse neonatal retina is therefore a practical, noninvasive, reliable, and robust model of HHT vascular pathology.

cell biology↗