Alain-Pierre Gadeau | Inserm - Academia.edu (original) (raw)

Papers by Alain-Pierre Gadeau

Nature, Jun 21, 2023

tdTomato, TOP-GAL, Nude and SCID. Tissue-specific mouse models were produced by crossing either C... more tdTomato, TOP-GAL, Nude and SCID. Tissue-specific mouse models were produced by crossing either Cre-carrying or CreER-carrying animals with flox-ed gene carrying animals, or rtTA-carrying animals with tetO-carrying animals. All animal experiments followed all relevant guidelines and regulations and were approved by the Institutional Animal Care and Use Committee at China Agricultural University (to Z.Y.

The FASEB Journal, Apr 1, 2013

Increased osteopontin (OPN; matricellular protein) expression associates with myocyte apoptosis a... more Increased osteopontin (OPN; matricellular protein) expression associates with myocyte apoptosis and myocardial dysfunction. The objective of this study was to identify OPN receptor, and understand the mechanism by which OPN induces myocyte apoptosis. Adult rat ventricular myocytes (ARVM) and transgenic mice expressing OPN in a myocyte‐specific manner were used for in vitro and in vivo studies. Treatment with purified OPN (20 nM) protein or adenoviral‐mediated OPN expression induced apoptosis in ARVM. OPN co‐immunoprecipitated with CD44 receptor. Neutralizing anti‐CD44 antibodies inhibited OPN‐stimulated apoptosis. OPN activated JNKs, and increased expression of Bax and levels of cytosolic cytochrome c suggesting involvement of mitochondrial death pathway. OPN increased endoplasmic reticulum (ER) stress, as evidenced by increased expression of Gadd153 and activation of caspase‐12. Inhibition of JNKs using SP600125 or ER stress using salubrinal or caspase‐12 inhibitor significantly reduced OPN‐stimulated apoptosis. Expression of OPN in adult mouse heart associated with increased myocyte apoptosis and LV dysfunction. In the heart, OPN expression increased JNKs and caspase‐12 activities, and expression of Bax and Gadd153. OPN, acting via CD44 receptors, induces apoptosis in myocytes via the involvement of ER stress and mitochondrial death pathway.

International Organization of Citrus Virologists Conference proceedings, 1984

As a preliminary to the determination of the functions of S. citri plasmids, two such plasmids, p... more As a preliminary to the determination of the functions of S. citri plasmids, two such plasmids, pMH1 (7 Kbp) and pM41 (8 Kbp), have been purified from two S. citri strains, M H and M4 respectively. The plasmids were mapped by restriction endonucleases. Using in vitro recombinant DNA technology, the linearized S. citri plasmid pMHl could be introduced into the Hind I11 site of E. eoli plasmid pBR328. The recombinant molecule was able to transform E. coli strain HBlOl and replicate in the bacterial host. Cloning of a spiroplasma plasmid in a bacterial cell has thus been achieved. Using a 32P-labeled probe of pM41, we have shown by DNA-DNA hybridization that a plasmid identical to pM41 or a closely related plasmid, is present in several, but not all, S. citri strains and also in three other spiroplasmas not belonging to the S. citri species. Hence, the same plasmid can be shared by different spiroplasmas. Similarly, a radioactive probe specific for plasmid pMHl allowed us to detect related DNA sequences among various other spiroplasmas.

International journal of systematic bacteriology, Apr 1, 1987

TABLE 1. Summary of periwinkles naturally infected with S. cifri or S. phoeniceum in 1983 and 198... more TABLE 1. Summary of periwinkles naturally infected with S. cifri or S. phoeniceum in 1983 and 1984 in Syria Location Periwinkle designation Period of exposure Infecting agent(s) Wizan El Annadeh project Nursery 111 Sweet orange mother tree plot El Annadeh government nursery El Annadeh, Fidio

Molecular Biology Reports, 2022

Numerous studies demonstrate parallels between CVD, type 2 diabetes mellitus (T2DM) and COVID-19 ... more Numerous studies demonstrate parallels between CVD, type 2 diabetes mellitus (T2DM) and COVID-19 pathology, which accentuate pre-existing complications in patients infected with COVID-19 and potentially exacerbate the infection course. Antidiabetic drugs such as sodium-glucose transporter-2 (SGLT-2) inhibitors have garnered substantial attention recently due to their efficacy in reducing the severity of cardiorenal disease. The effect of SGLT-2 inhibitors in patients with COVID-19 remains unclear particularly since SGLT-2 inhibitors contribute to altering the RAAS cascade activity, which includes ACE-2, the major cell entry receptor for SARS-CoV2. A study, DARE-19, was carried out to unveil the effects of SGLT-2 inhibitor treatment on comorbid disease complications and concomitant COVID-19 outcomes and demonstrated no statistical significance. However, the need for further studies is essential to provide conclusive clinical findings.

Although the accelerative effect of 17ß-estradiol (E2) on endothelial regrowth has been clearly d... more Although the accelerative effect of 17ß-estradiol (E2) on endothelial regrowth has been clearly demonstrated, the local cellular events accounting for this beneficial vascular action are still uncertain. In the present work, we compared the kinetics of endothelial healing of mouse carotid arteries after endovascular and perivascular injury. Both basal reendothelialization as well as the accelerative effect of E2 were similar in the two models. Three days after endothelial denudation, a "regenerative area" was observed in both models, characterized by similar changes in gene expression after injury, visualized by "en face" confocal microscopy (EFCM). A precise definition of the injury limits was only possible with the perivascular model, since it causes a complete and lasting decellularization of the media. Using this model, we demonstrated that migration of uninjured endothelial cells precedes proliferation (BrdU incorporation) and that these events occur at earlier time points with E2 treatment. We have also identified an uninjured retrograde zone as an intimate component of the endothelial regeneration process. Thus, in the perivascular model the "regenerative area" can be subdivided into a retrograde zone and a reendothelialized area. Importantly, both areas are significantly enlarged by E2.. In conclusion, the combination of the electric perivascular injury model and EFCM is well adapted to the visualization of the endothelial monolayer and to investigate cellular events involved in reendothelialization. This process is accelerated by E2 as a consequence of the retrograde commitment of an uninjured endothelial zone to migrate and proliferate contributing to an enlargement of the "regenerative area".

European Journal of Pharmacology, 2020

Previous studies have established the role of Na + /H + exchanger isoform-1 (NHE1) and cathepsin ... more Previous studies have established the role of Na + /H + exchanger isoform-1 (NHE1) and cathepsin B (Cat B) in the development of cardiomyocyte hypertrophy (CH). Both NHE1 and Cat B are activated under acidic conditions suggesting that their activities might be interrelated. The inhibition of NHE1 has been demonstrated to reduce cardiac hypertrophy but the mechanism that contributes to the anti-hypertrophic effect of NHE1 inhibition still remains unclear. H9c2 cardiomyoblasts were stimulated with Angiotensin (Ang) II in the presence and absence of N-[2-methyl-4,5-bis(methylsulphonyl)-benzoyl]-guanidine, hydrochloride (EMD, EMD 87580), an NHE1 inhibitor or CA-074Me, a Cat B inhibitor, and various cardiac hypertrophic parameters, namely cell surface area, protein content and atrial natriuretic peptide (ANP) mRNA were analyzed. EMD significantly suppressed markers of cardiomyocyte hypertrophy and inhibited Ang II stimulated Cat B protein and gene expression. Cat B is located within the acidic environment of lysosomes. Cat B proteases are released into the cytoplasm upon disintegration of the lysosomes. EMD or CA-074Me prevented the dispersal of the lysosomes induced by Ang II and reduced the ratio of LC3-II to LC3-I, a marker of autophagy. Moreover, Cat B protein expression and MMP-9 activity in the extracellular space were significantly attenuated in the presence of EMD or CA-074Me. Our study demonstrates a novel mechanism for attenuation of the hypertrophic phenotype by NHE1 inhibition that is mediated by a regression in Cat B. The inhibition of Cat B via EMD or CA-074Me attenuates the autosomal-lysosomal pathway and MMP-9 activation.

PLOS ONE, Apr 17, 2015

Enhanced expression and activity of the Na + /H + exchanger isoform 1 (NHE1) has been implicated ... more Enhanced expression and activity of the Na + /H + exchanger isoform 1 (NHE1) has been implicated in cardiomyocyte hypertrophy in various experimental models. The upregulation of NHE1 was correlated with an increase in osteopontin (OPN) expression in models of cardiac hypertrophy (CH), and the mechanism for this remains to be delineated. To determine whether the expression of active NHE1-induces OPN and contributes to the hypertrophic response in vitro, cardiomyocytes were infected with the active form of the NHE1 adenovirus or transfected with OPN silencing RNA (siRNA-OPN) and characterized for cardiomyocyte hypertrophy. Expression of NHE1 in cardiomyocytes resulted in a significant increase in cardiomyocyte hypertrophy markers: cell surface area, protein content, ANP mRNA and expression of phosphorylated-GATA4. NHE1 activity was also significantly increased in cardiomyocytes expressing active NHE1. Interestingly, transfection of cardiomyocytes with siRNA-OPN significantly abolished the NHE1-induced cardiomyocyte hypertrophy. siRNA-OPN also significantly reduced the activity of NHE1 in cardiomyocytes expressing NHE1 (68.5±0.24%; P<0.05), confirming the role of OPN in the NHE1-induced hypertrophic response. The hypertrophic response facilitated by NHE1-induced OPN occurred independent of the extracellular-signal-regulated kinases and Akt, but required p90-ribosomal S6 kinase (RSK). The ability of OPN to facilitate the NHE1-induced hypertrophic response identifies OPN as a potential therapeutic target to reverse the hypertrophic effect induced by the expression of active NHE1.

Proceedings of The Physiological Society, 2016

bioRxiv (Cold Spring Harbor Laboratory), Feb 8, 2023

Coronary microvascular disease has been proposed to be responsible for heart failure with preserv... more Coronary microvascular disease has been proposed to be responsible for heart failure with preserved ejection fraction (HFpEF) about 10 years ago. However, to date the role and phenotype of the coronary microvasculature has still been poorly considered and investigated in animal models of HFpEF. Objective: To determine whether endothelial dysfunction participates in the development of diastolic dysfunction in mice fed with a high fat diet (HDF) and treated with L-NAME. Approach and Results: At first, we thoroughly phenotyped the coronary microvasculature in this model in male, female and ovariectomized (OVX) female considering the sexual dimorphism associated with this disease. We found that both OVX and non OVX females but not males display increased endothelial activation, leakage, and arteriole constriction upon the HFD + L-NAME regimen while both male and OVX females but not non OVX females develop diastolic dysfunction. With the aim to investigate the role of endothelial dysfunction in the pathophysiology of diastolic dysfunction in OVX female mice, we used Cdon deficient mice. Indeed, we previously demonstrated that endothelium integrity, upon inflammatory conditions, is preserved in these mice. Both OVX Cdh5-Cre/ERT2-Cdon Flox/Flox (Cdon ECKO) and Cdon Flox/Flox (Ctrl) female mice were fed with the HFD + L-NAME regimen to induced diastolic dysfunction. As expected, Cdon ECKO mice displayed improved endothelium integrity i.e. decreased endothelium permeability, decreased ICAM-1 expression and decreased infiltration of CD45+ leukocytes in comparison to control mice. However, Cdon ECKO mice displayed cardiac hypertrophy, cardiac fibrosis and increased end diastolic pressure just like control mice. Moreover, we found that cardiac inflammation does not participate in the pathophysiology of HFpEF either by treating OVX female mice with colchicine. Conclusion: Altogether, the data presented in this paper demonstrate that neither endothelium permeability nor endothelial activation or inflammation do participate in the pathophysiology of diastolic dysfunction in mice exposed to HFD+L-NAME.

Archives of Cardiovascular Diseases Supplements, Apr 1, 2019

Results sVE was significantly elevated in healthy volunteers submitted to IH and in OSAS patient ... more Results sVE was significantly elevated in healthy volunteers submitted to IH and in OSAS patient sera before treatment, but decreased in OSAS patients after 6 months of CPAP therapy. We found a significant positive correlation between sVE and OSAS severity and between sVE and serum VEGF. In HAEC supernatants, TEER decreased by 37.5% and sVE increased by 39% after cell exposure to IH. These effects were reversed by all the pharmacological inhibitors tested. Conclusion we suggest that, in OSAS, IH increases endothelial permeability by inducing VECad cleavage via the ROS, HIF1, VEGF and tyrosine kinase pathways. Future studies will determine whether sVE could be a potential biomarker to evaluate early endothelial alterations in OSAS. Disclosure of interest The authors declare that they have no competing interest.

Journal of the American Heart Association, Jun 22, 2023

Background Although the critical role of pericytes in maintaining vascular integrity has been ext... more Background Although the critical role of pericytes in maintaining vascular integrity has been extensively demonstrated in the brain and the retina, little is known about their role in the heart. We aim to investigate structural and functional consequences of partial pericyte depletion (≈60%) in the heart of adult mice. Methods and Results To deplete pericytes in adult mice, we used platelet‐derived growth factor receptor β–Cre/ERT2; Rosa DTA mice and compared their phenotype with that of control mice (Rosa DTA ) chosen among their littermates. Cardiac function was assessed via echocardiography and left ventricular catheterization 1 month after the first tamoxifen injection. We found mice depleted with pericytes had a reduced left ventricular ejection fraction and an increased end‐diastolic pressure, demonstrating both systolic and diastolic dysfunction. Consistently, mice depleted with pericytes presented a decreased left ventricular contractility and an increased left ventricular relaxation time (dP/dt min ). At the tissue level, mice depleted of pericytes displayed increased coronary endothelium leakage and activation, which was associated with increased CD45 + cell infiltration. Consistent with systolic dysfunction, pericyte depletion was associated with an increased expression of myosin heavy chain 7 and decreased expression of ATPase sarcoplasmic/endoplasmic reticulum Ca2 + transporting 2 and connexin 43. More important, coculture assays demonstrated, for the first time, that the decreased expression of connexin 43 is likely attributable to a direct effect of pericytes on cardiomyocytes. Besides, this study reveals that cardiac pericytes may undergo strong remodeling on injury. Conclusions Cardiac pericyte depletion induces both systolic and diastolic dysfunction, suggesting that pericyte dysfunction may contribute to the occurrence of cardiac diseases.

Archives of Cardiovascular Diseases Supplements, May 1, 2023

bioRxiv (Cold Spring Harbor Laboratory), Sep 1, 2022

Introduction: While the critical role of pericytes in maintaining vascular integrity has been ext... more Introduction: While the critical role of pericytes in maintaining vascular integrity has been extensively demonstrated in the brain and in the retina, very little is known about their role in the heart. Objective: We aim to investigate structural and functional consequences of partial pericyte depletion (about 60%) in the heart of adult mice. Methods: To deplete pericyte in adult mice, we used Pdgfrb-Cre/ERT2; Rosa-DTA mice and compared their phenotype to the one of control mice (Rosa-DTA) chosen among their littermates. Cardiac function was assessed via echocardiography and left ventricle (LV) catheterization one month after the first tamoxifen injection. Results: Mice depleted with pericytes displayed increased coronary endothelium leakage and activation which was associated with increased CD45 + cell infiltration in the heart. Pericyte depletion also modified the phenotype of cardiomyocytes with an increased expression of Myosin Heavy Chain 7, a decreased expression of ATPase Sarcoplasmic/Endoplasmic Reticulum Ca2+ Transporting 2, Connexin 43 and a decreased phosphorylation of Phospholamban suggesting cardiomyocyte dedifferentiation and impaired contractility. As a consequence, mice depleted with pericytes had a reduced LV ejection fraction and an increased end-diastolic pressure demonstrating both systolic and diastolic dysfunction. Accordingly, mice depleted with pericytes presented a decreased LV contractility and an increased LV relaxation time (dP/dt min). Besides this study reveals that cardiac pericytes may undergo strong remodeling upon injury. Conclusion: Cardiac pericyte depletion induces both systolic and diastolic dysfunction suggesting that pericyte dysfunction may contribute to the occurrence of cardiac diseases.

Archives of Cardiovascular Diseases Supplements, Apr 1, 2017

Background Transdermal iontophoresis is widely used to assess the reactivity of the cutaneous mic... more Background Transdermal iontophoresis is widely used to assess the reactivity of the cutaneous microcirculation. However, due to a lack of consensus in the literature, many studies use protocols at high-risk of inducing non-specific vasodilatory effects; thus, publishing data that may not reflect the true change in microvascular function throughout the pathogenesis of cardiometabolic or cardiovascular disease. Purpose To examine published protocols of transdermal iontophoresis for evidence of non-specific vasodilatory effects. Methods Twelve healthy participants completed 10 protocols of transdermal iontophoresis that delivered varying totals of iontophoretic charge density to administer acetylcholine (ACh) 1-2% (1.95-9.09 mC/cm 2), sodium nitroprusside (SNP) 1% (1.95-23.38 mC/cm 2) and insulin 100U/mL (7.79-31.17 mC/cm 2) to the microcirculation. Both ACh and SNP were diluted in sodium chloride 0.9% or deionized water; and insulin was administered in a sterile insulin-specific diluent. Laser speckle contrast imaging measured changes in microvascular blood flux at two electrodes. To detect non-specific vasodilatory effects, one electrode contained the vasoactive substance in its diluent, whilst the other electrode (control) contained the diluent alone. Increases in blood flux at the control electrode indicated non-specific vasodilatory effects. Results There were no significant non-specific vasodilatory effects detected in response to any protocol for transdermal iontophoresis of ACh. In contrast, there were significant increases in blood flux at the control electrode in both insulin protocols and where SNP was diluted with deionized water. Indeed, SNP or ACh in sodium choloride 0.9% (0,02mA for 400 and 200 s, respectively) and ACh in deionized water (0,1mA for 30s) mediated the least nonspecific vasodilatory effects. Conclusion This study provides new guidelines for future research using transdermal iontophoresis to examine cutaneous microvascular function.

Archives of Cardiovascular Diseases Supplements

The FASEB Journal, 2019

The microcirculatory physiology critically depends on a highly structured network of vessels arra... more The microcirculatory physiology critically depends on a highly structured network of vessels arranged to deliver oxygen to the tissues in a optimized way. In turn, oxygen is also a critical regulatory element of these functions, not only acting locally, influencing resistance, but also controlled by other local and systemic (homeostatic) regulators. Using oxygen as a challenger we detected an interesting regional perfusion dynamics taking place in the mouse, after an hindlimb ischemia procedure, where the contralateral non operated limb contributed to recover the equivalent circulatory steady state in both limbs. A similar cooperation perfusion event, involving both limbs, has only been referred as a long‐term vascular adaptation to ischemia in patients with peripheral arterial occlusive disease, but never, to our knowledge, experimentally pursued.More recently the impact of postural vasoconstriction in the human foot perfusion, the veno‐arterial reflex (VAR), measured with photople...