9 research outputs found
Arterioscler Thromb Vasc Biol
Evidences accumulated within the past decades identified hedgehog signaling as a new regulator of endothelium integrity. More specifically, we recently identified Dhh (desert hedgehog) as a downstream effector of Klf2 (Kruppel-like factor 2) in endothelial cells (ECs). The purpose of this study is to investigate whether hedgehog coreceptors Gas1 (growth arrest-specific 1) and Cdon (cell adhesion molecule-related/downregulated by oncogenes) may be used as therapeutic targets to modulate Dhh signaling in ECs. Approach and Results: We demonstrated that both Gas1 and Cdon are expressed in adult ECs and relied on either siRNAs- or EC-specific conditional knockout mice to investigate their role. We found that Gas1 deficiency mainly phenocopies Dhh deficiency especially by inducing VCAM-1 (vascular cell adhesion molecule 1) and ICAM-1 (intercellular adhesion molecule 1) overexpression while Cdon deficiency has opposite effects by promoting endothelial junction integrity. At a molecular level, Cdon prevents Dhh binding to Ptch1 (patched-1) and thus acts as a decoy receptor for Dhh, while Gas1 promotes Dhh binding to Smo (smoothened) and as a result potentiates Dhh effects. Since Cdon is upregulated in ECs treated by inflammatory cytokines, including TNF (tumor necrosis factor)-α and Il (interleukin)-1ÎČ, we then tested whether Cdon inhibition would promote endothelium integrity in acute inflammatory conditions and found that both fibrinogen and IgG extravasation were decreased in association with an increased Cdh5 (cadherin-5) expression in the brain cortex of EC-specific Cdon knockout mice administered locally with Il-1ÎČ. Altogether, these results demonstrate that Gas1 is a positive regulator of Dhh in ECs while Cdon is a negative regulator. Interestingly, Cdon blocking molecules may then be used to promote endothelium integrity, at least in inflammatory conditions
PLoS Biol
Inflammation of the central nervous system (CNS) induces endothelial blood-brain barrier (BBB) opening as well as the formation of a tight junction barrier between reactive astrocytes at the Glia Limitans. We hypothesized that the CNS parenchyma may acquire protection from the reactive astrocytic Glia Limitans not only during neuroinflammation but also when BBB integrity is compromised in the resting state. Previous studies found that astrocyte-derived Sonic hedgehog (SHH) stabilizes the BBB during CNS inflammatory disease, while endothelial-derived desert hedgehog (DHH) is expressed at the BBB under resting conditions. Here, we investigated the effects of endothelial Dhh on the integrity of the BBB and Glia Limitans. We first characterized DHH expression within endothelial cells at the BBB, then demonstrated that DHH is down-regulated during experimental autoimmune encephalomyelitis (EAE). Using a mouse model in which endothelial Dhh is inducibly deleted, we found that endothelial Dhh both opens the BBB via the modulation of forkhead box O1 (FoxO1) transcriptional activity and induces a tight junctional barrier at the Glia Limitans. We confirmed the relevance of this glial barrier system in human multiple sclerosis active lesions. These results provide evidence for the novel concept of "chronic neuroinflammatory tolerance" in which BBB opening in the resting state is sufficient to stimulate a protective barrier at the Glia Limitans that limits the severity of subsequent neuroinflammatory disease. In summary, genetic disruption of the BBB generates endothelial signals that drive the formation under resting conditions of a secondary barrier at the Glia Limitans with protective effects against subsequent CNS inflammation. The concept of a reciprocally regulated CNS double barrier system has implications for treatment strategies in both the acute and chronic phases of multiple sclerosis pathophysiology
RÎle des péricytes et des cellules endothéliales dans l'insuffisance cardiaque
Heart failure (HF) is a major public health issue affecting between 1 to 2% of the general population. Patients with HF with preserved ejection fraction (HFpEF) represent approximately 50% of patients with HF and are often older, female, and frequently have hypertension. The high prevalence of these comorbidities suggests that they play a role in the development of the disease. There is currently no specific treatment for HFpEF, because its pathophysiology remains poorly understood and requires further investigations in order to find new therapeutic targets. Microvascular dysfunction is currently proposed as compromising the perfusion of the heart and participating in the development of diastolic dysfunction. But the role of endothelial dysfunction in the pathophysiology of HFpEF remains to be clarified.Our objective was to better understand the role of vascular cells, pericytes and endothelial cells, in the pathophysiology of HFpEF. More specifically, this thesis aimed (1) to measure the impact of pericyte degeneration on cardiac microvascular integrity and cardiac function, (2) to test whether endothelial dysfunction participates in the development of diastolic dysfunction in a mouse model of HFpEF, and (3) to assess the sexual dimorphism associated with ICFEp.To investigate the role of pericytes in the heart, we have developed a mouse model lacking pericytes, Pdgfrb-Cre/ERT2; Rosa-DTA mice. We demonstrated that cardiac pericytes are required for cardiac microvascular integrity and cardiac function by regulating cardiomyocyte contractility and relaxation. These results suggest that changes in the pericyte phenotype may participate in the pathophysiology of cardiovascular diseases.To test the role of endothelial dysfunction in the pathophysiology of HFpEF, we created a mouse model in which diastolic dysfunction is induced by a high-fat diet (HFD) and by L-NAME, a NO synthase inhibitor. Firstly, we characterized the phenotype of the coronary vasculature in this model in males, females and ovariectomized females to highlight a possible sexual dimorphism. We have demonstrated that diastolic dysfunction was associated with endothelial dysfunction only in ovariectomized females. Secondly, we tested the role of endothelial dysfunction in these mice using a mouse model with preserved endothelial function under stress conditions (CdonECKO mice). This experiment proved that preventing endothelial dysfunction does not prevent diastolic dysfunction induced by an HFD+L-NAME treatment.All of these results demonstrate that the role of endothelial dysfunction in the development of HFpEF remains to be proved.Lâinsuffisance cardiaque (IC) est un problĂšme de santĂ© publique majeur touchant entre 1 et 2 % de la population gĂ©nĂ©rale. Les patients atteints dâIC Ă fraction dâĂ©jection prĂ©servĂ©e (ICFEp) reprĂ©sentent environ 50 % des patients ayant une IC et sont souvent plus ĂągĂ©s, de sexe fĂ©minin, et prĂ©sentent frĂ©quemment une HTA. La prĂ©valence Ă©levĂ©e de ces comorbiditĂ©s suggĂšre quâelles jouent un rĂŽle dans le dĂ©veloppement de la maladie. Il nâexiste Ă lâheure actuelle aucun traitement spĂ©cifique de lâICFEp, car sa physiopathologie reste mal comprise et nĂ©cessite dâĂȘtre approfondie afin de trouver de nouvelles cibles thĂ©rapeutiques. La dysfonction microvasculaire est actuellement proposĂ©e comme compromettant la perfusion du coeur et participant ainsi au dĂ©veloppement de la dysfonction diastolique. Mais lâimplication de la dysfonction endothĂ©liale dans la physiopathologie de lâICFEp reste Ă dĂ©montrer. Lâobjectif de cette thĂšse Ă©tait donc de mieux comprendre le rĂŽle des cellules vasculaires, pĂ©ricytes et cellules endothĂ©liales, dans la physiopathologie de lâICFEp. Plus prĂ©cisĂ©ment, cette thĂšse a eu pour but (1) de mesurer lâimpact de la dĂ©gĂ©nĂ©rescence des pĂ©ricytes sur lâintĂ©gritĂ© microvasculaire cardiaque et sur la fonction cardiaque, (2) de tester si la dysfonction endothĂ©liale participe au dĂ©veloppement de la dysfonction diastolique dans un modĂšle murin dâICFEp, et (3) dâĂ©valuer le dimorphisme sexuel associĂ© Ă lâICFEp.Pour Ă©tudier le rĂŽle des pĂ©ricytes sur le coeur, nous avons dĂ©veloppĂ© un modĂšle de souris dĂ©pourvues de pĂ©ricytes, les souris Pdgfrb-Cre/ERT2 ; Rosa-DTA. Nous avons dĂ©montrĂ© que les pĂ©ricytes cardiaques sont nĂ©cessaires Ă lâintĂ©gritĂ© microvasculaire cardiaque et Ă la fonction cardiaque en rĂ©gulant la contractilitĂ© et la relaxation des cardiomyocytes. Ces rĂ©sultats suggĂšrent que des modifications du phĂ©notype des pĂ©ricytes pourraient participer Ă la physiopathologie de maladies cardiovasculaires. Pour tester le rĂŽle de la dysfonction endothĂ©liale dans la physiopathologie de lâICFEp, nous avons dâabord mis en place un modĂšle murin, chez lequel une dysfonction diastolique est induite par un rĂ©gime riche en lipides (HFD) et par le L-NAME, un inhibiteur de NO synthase. Dans un premier temps, nous avons caractĂ©risĂ© le phĂ©notype de la vasculature coronaire dans ce modĂšle chez les mĂąles, les femelles et les femelles ovariectomisĂ©es pour mettre en Ă©vidence un Ă©ventuel dimorphisme sexuel. Nous avons, en effet, mis en Ă©vidence que la dysfonction diastolique Ă©tait associĂ©e Ă une dysfonction endothĂ©liale uniquement chez les femelles ovariectomisĂ©es. Dans un second temps, nous avons testĂ© le rĂŽle de la dysfonction endothĂ©liale chez ces souris Ă lâaide dâun modĂšle murin prĂ©sentant une fonction endothĂ©liale prĂ©servĂ©e dans des conditions de stress (les souris CdonECKO). Cette expĂ©rience nous a rĂ©vĂ©lĂ© que prĂ©venir la dysfonction endothĂ©liale ne permet pas de prĂ©venir la dysfonction diastolique induite par le traitement HFD+L-NAME.Lâensemble de ces rĂ©sultats dĂ©montrent que le rĂŽle de la dysfonction endothĂ©liale dans le dĂ©veloppement de lâICFEp reste Ă prouver
Role of pericytes and endothelial cells in the heart failure
Lâinsuffisance cardiaque (IC) est un problĂšme de santĂ© publique majeur touchant entre 1 et 2 % de la population gĂ©nĂ©rale. Les patients atteints dâIC Ă fraction dâĂ©jection prĂ©servĂ©e (ICFEp) reprĂ©sentent environ 50 % des patients ayant une IC et sont souvent plus ĂągĂ©s, de sexe fĂ©minin, et prĂ©sentent frĂ©quemment une HTA. La prĂ©valence Ă©levĂ©e de ces comorbiditĂ©s suggĂšre quâelles jouent un rĂŽle dans le dĂ©veloppement de la maladie. Il nâexiste Ă lâheure actuelle aucun traitement spĂ©cifique de lâICFEp, car sa physiopathologie reste mal comprise et nĂ©cessite dâĂȘtre approfondie afin de trouver de nouvelles cibles thĂ©rapeutiques. La dysfonction microvasculaire est actuellement proposĂ©e comme compromettant la perfusion du coeur et participant ainsi au dĂ©veloppement de la dysfonction diastolique. Mais lâimplication de la dysfonction endothĂ©liale dans la physiopathologie de lâICFEp reste Ă dĂ©montrer. Lâobjectif de cette thĂšse Ă©tait donc de mieux comprendre le rĂŽle des cellules vasculaires, pĂ©ricytes et cellules endothĂ©liales, dans la physiopathologie de lâICFEp. Plus prĂ©cisĂ©ment, cette thĂšse a eu pour but (1) de mesurer lâimpact de la dĂ©gĂ©nĂ©rescence des pĂ©ricytes sur lâintĂ©gritĂ© microvasculaire cardiaque et sur la fonction cardiaque, (2) de tester si la dysfonction endothĂ©liale participe au dĂ©veloppement de la dysfonction diastolique dans un modĂšle murin dâICFEp, et (3) dâĂ©valuer le dimorphisme sexuel associĂ© Ă lâICFEp.Pour Ă©tudier le rĂŽle des pĂ©ricytes sur le coeur, nous avons dĂ©veloppĂ© un modĂšle de souris dĂ©pourvues de pĂ©ricytes, les souris Pdgfrb-Cre/ERT2 ; Rosa-DTA. Nous avons dĂ©montrĂ© que les pĂ©ricytes cardiaques sont nĂ©cessaires Ă lâintĂ©gritĂ© microvasculaire cardiaque et Ă la fonction cardiaque en rĂ©gulant la contractilitĂ© et la relaxation des cardiomyocytes. Ces rĂ©sultats suggĂšrent que des modifications du phĂ©notype des pĂ©ricytes pourraient participer Ă la physiopathologie de maladies cardiovasculaires. Pour tester le rĂŽle de la dysfonction endothĂ©liale dans la physiopathologie de lâICFEp, nous avons dâabord mis en place un modĂšle murin, chez lequel une dysfonction diastolique est induite par un rĂ©gime riche en lipides (HFD) et par le L-NAME, un inhibiteur de NO synthase. Dans un premier temps, nous avons caractĂ©risĂ© le phĂ©notype de la vasculature coronaire dans ce modĂšle chez les mĂąles, les femelles et les femelles ovariectomisĂ©es pour mettre en Ă©vidence un Ă©ventuel dimorphisme sexuel. Nous avons, en effet, mis en Ă©vidence que la dysfonction diastolique Ă©tait associĂ©e Ă une dysfonction endothĂ©liale uniquement chez les femelles ovariectomisĂ©es. Dans un second temps, nous avons testĂ© le rĂŽle de la dysfonction endothĂ©liale chez ces souris Ă lâaide dâun modĂšle murin prĂ©sentant une fonction endothĂ©liale prĂ©servĂ©e dans des conditions de stress (les souris CdonECKO). Cette expĂ©rience nous a rĂ©vĂ©lĂ© que prĂ©venir la dysfonction endothĂ©liale ne permet pas de prĂ©venir la dysfonction diastolique induite par le traitement HFD+L-NAME.Lâensemble de ces rĂ©sultats dĂ©montrent que le rĂŽle de la dysfonction endothĂ©liale dans le dĂ©veloppement de lâICFEp reste Ă prouver.Heart failure (HF) is a major public health issue affecting between 1 to 2% of the general population. Patients with HF with preserved ejection fraction (HFpEF) represent approximately 50% of patients with HF and are often older, female, and frequently have hypertension. The high prevalence of these comorbidities suggests that they play a role in the development of the disease. There is currently no specific treatment for HFpEF, because its pathophysiology remains poorly understood and requires further investigations in order to find new therapeutic targets. Microvascular dysfunction is currently proposed as compromising the perfusion of the heart and participating in the development of diastolic dysfunction. But the role of endothelial dysfunction in the pathophysiology of HFpEF remains to be clarified.Our objective was to better understand the role of vascular cells, pericytes and endothelial cells, in the pathophysiology of HFpEF. More specifically, this thesis aimed (1) to measure the impact of pericyte degeneration on cardiac microvascular integrity and cardiac function, (2) to test whether endothelial dysfunction participates in the development of diastolic dysfunction in a mouse model of HFpEF, and (3) to assess the sexual dimorphism associated with ICFEp.To investigate the role of pericytes in the heart, we have developed a mouse model lacking pericytes, Pdgfrb-Cre/ERT2; Rosa-DTA mice. We demonstrated that cardiac pericytes are required for cardiac microvascular integrity and cardiac function by regulating cardiomyocyte contractility and relaxation. These results suggest that changes in the pericyte phenotype may participate in the pathophysiology of cardiovascular diseases.To test the role of endothelial dysfunction in the pathophysiology of HFpEF, we created a mouse model in which diastolic dysfunction is induced by a high-fat diet (HFD) and by L-NAME, a NO synthase inhibitor. Firstly, we characterized the phenotype of the coronary vasculature in this model in males, females and ovariectomized females to highlight a possible sexual dimorphism. We have demonstrated that diastolic dysfunction was associated with endothelial dysfunction only in ovariectomized females. Secondly, we tested the role of endothelial dysfunction in these mice using a mouse model with preserved endothelial function under stress conditions (CdonECKO mice). This experiment proved that preventing endothelial dysfunction does not prevent diastolic dysfunction induced by an HFD+L-NAME treatment.All of these results demonstrate that the role of endothelial dysfunction in the development of HFpEF remains to be proved
RÎle des péricytes et des cellules endothéliales dans l'insuffisance cardiaque
Heart failure (HF) is a major public health issue affecting between 1 to 2% of the general population. Patients with HF with preserved ejection fraction (HFpEF) represent approximately 50% of patients with HF and are often older, female, and frequently have hypertension. The high prevalence of these comorbidities suggests that they play a role in the development of the disease. There is currently no specific treatment for HFpEF, because its pathophysiology remains poorly understood and requires further investigations in order to find new therapeutic targets. Microvascular dysfunction is currently proposed as compromising the perfusion of the heart and participating in the development of diastolic dysfunction. But the role of endothelial dysfunction in the pathophysiology of HFpEF remains to be clarified.Our objective was to better understand the role of vascular cells, pericytes and endothelial cells, in the pathophysiology of HFpEF. More specifically, this thesis aimed (1) to measure the impact of pericyte degeneration on cardiac microvascular integrity and cardiac function, (2) to test whether endothelial dysfunction participates in the development of diastolic dysfunction in a mouse model of HFpEF, and (3) to assess the sexual dimorphism associated with ICFEp.To investigate the role of pericytes in the heart, we have developed a mouse model lacking pericytes, Pdgfrb-Cre/ERT2; Rosa-DTA mice. We demonstrated that cardiac pericytes are required for cardiac microvascular integrity and cardiac function by regulating cardiomyocyte contractility and relaxation. These results suggest that changes in the pericyte phenotype may participate in the pathophysiology of cardiovascular diseases.To test the role of endothelial dysfunction in the pathophysiology of HFpEF, we created a mouse model in which diastolic dysfunction is induced by a high-fat diet (HFD) and by L-NAME, a NO synthase inhibitor. Firstly, we characterized the phenotype of the coronary vasculature in this model in males, females and ovariectomized females to highlight a possible sexual dimorphism. We have demonstrated that diastolic dysfunction was associated with endothelial dysfunction only in ovariectomized females. Secondly, we tested the role of endothelial dysfunction in these mice using a mouse model with preserved endothelial function under stress conditions (CdonECKO mice). This experiment proved that preventing endothelial dysfunction does not prevent diastolic dysfunction induced by an HFD+L-NAME treatment.All of these results demonstrate that the role of endothelial dysfunction in the development of HFpEF remains to be proved.Lâinsuffisance cardiaque (IC) est un problĂšme de santĂ© publique majeur touchant entre 1 et 2 % de la population gĂ©nĂ©rale. Les patients atteints dâIC Ă fraction dâĂ©jection prĂ©servĂ©e (ICFEp) reprĂ©sentent environ 50 % des patients ayant une IC et sont souvent plus ĂągĂ©s, de sexe fĂ©minin, et prĂ©sentent frĂ©quemment une HTA. La prĂ©valence Ă©levĂ©e de ces comorbiditĂ©s suggĂšre quâelles jouent un rĂŽle dans le dĂ©veloppement de la maladie. Il nâexiste Ă lâheure actuelle aucun traitement spĂ©cifique de lâICFEp, car sa physiopathologie reste mal comprise et nĂ©cessite dâĂȘtre approfondie afin de trouver de nouvelles cibles thĂ©rapeutiques. La dysfonction microvasculaire est actuellement proposĂ©e comme compromettant la perfusion du coeur et participant ainsi au dĂ©veloppement de la dysfonction diastolique. Mais lâimplication de la dysfonction endothĂ©liale dans la physiopathologie de lâICFEp reste Ă dĂ©montrer. Lâobjectif de cette thĂšse Ă©tait donc de mieux comprendre le rĂŽle des cellules vasculaires, pĂ©ricytes et cellules endothĂ©liales, dans la physiopathologie de lâICFEp. Plus prĂ©cisĂ©ment, cette thĂšse a eu pour but (1) de mesurer lâimpact de la dĂ©gĂ©nĂ©rescence des pĂ©ricytes sur lâintĂ©gritĂ© microvasculaire cardiaque et sur la fonction cardiaque, (2) de tester si la dysfonction endothĂ©liale participe au dĂ©veloppement de la dysfonction diastolique dans un modĂšle murin dâICFEp, et (3) dâĂ©valuer le dimorphisme sexuel associĂ© Ă lâICFEp.Pour Ă©tudier le rĂŽle des pĂ©ricytes sur le coeur, nous avons dĂ©veloppĂ© un modĂšle de souris dĂ©pourvues de pĂ©ricytes, les souris Pdgfrb-Cre/ERT2 ; Rosa-DTA. Nous avons dĂ©montrĂ© que les pĂ©ricytes cardiaques sont nĂ©cessaires Ă lâintĂ©gritĂ© microvasculaire cardiaque et Ă la fonction cardiaque en rĂ©gulant la contractilitĂ© et la relaxation des cardiomyocytes. Ces rĂ©sultats suggĂšrent que des modifications du phĂ©notype des pĂ©ricytes pourraient participer Ă la physiopathologie de maladies cardiovasculaires. Pour tester le rĂŽle de la dysfonction endothĂ©liale dans la physiopathologie de lâICFEp, nous avons dâabord mis en place un modĂšle murin, chez lequel une dysfonction diastolique est induite par un rĂ©gime riche en lipides (HFD) et par le L-NAME, un inhibiteur de NO synthase. Dans un premier temps, nous avons caractĂ©risĂ© le phĂ©notype de la vasculature coronaire dans ce modĂšle chez les mĂąles, les femelles et les femelles ovariectomisĂ©es pour mettre en Ă©vidence un Ă©ventuel dimorphisme sexuel. Nous avons, en effet, mis en Ă©vidence que la dysfonction diastolique Ă©tait associĂ©e Ă une dysfonction endothĂ©liale uniquement chez les femelles ovariectomisĂ©es. Dans un second temps, nous avons testĂ© le rĂŽle de la dysfonction endothĂ©liale chez ces souris Ă lâaide dâun modĂšle murin prĂ©sentant une fonction endothĂ©liale prĂ©servĂ©e dans des conditions de stress (les souris CdonECKO). Cette expĂ©rience nous a rĂ©vĂ©lĂ© que prĂ©venir la dysfonction endothĂ©liale ne permet pas de prĂ©venir la dysfonction diastolique induite par le traitement HFD+L-NAME.Lâensemble de ces rĂ©sultats dĂ©montrent que le rĂŽle de la dysfonction endothĂ©liale dans le dĂ©veloppement de lâICFEp reste Ă prouver
Endothelial Dysfunction in Heart Failure With Preserved Ejection Fraction: What are the Experimental Proofs?
Heart failure with preserved ejection fraction (HFpEF) has been recognized as the greatest single unmet need in cardiovascular medicine. Indeed, the morbi-mortality of HFpEF is high and as the population ages and the comorbidities increase, so considerably does the prevalence of HFpEF. However, HFpEF pathophysiology is still poorly understood and therapeutic targets are missing. An unifying, but untested, theory of the pathophysiology of HFpEF, proposed in 2013, suggests that cardiovascular risk factors lead to a systemic inflammation, which triggers endothelial cells (EC) and coronary microvascular dysfunction. This cardiac small vessel disease is proposed to be responsible for cardiac wall stiffening and diastolic dysfunction. This paradigm is based on the fact that microvascular dysfunction is highly prevalent in HFpEF patients. More specifically, HFpEF patients have been shown to have decreased cardiac microvascular density, systemic endothelial dysfunction and a lower mean coronary flow reserve. Importantly, impaired coronary microvascular function has been associated with the severity of HF. This review discusses evidence supporting the causal role of endothelial dysfunction in the pathophysiology of HFpEF in human and experimental models
Cardiovasc Res
The therapeutic potential of Hedgehog (Hh) signalling agonists for vascular diseases is of growing interest. However, molecular and cellular mechanisms underlying the role of the Hh signalling in vascular biology remain poorly understood. The purpose of the present paper is to clarify some conflicting literature data. : With this goal we have demonstrated that, unexpectedly, ectopically administered N-terminal Sonic Hedgehog (N-Shh) and endogenous endothelial-derived Desert Hedgehog (Dhh) induce opposite effects in endothelial cells (ECs). Notably, endothelial Dhh acts under its full-length soluble form (FL-Dhh) and activates Smoothened in ECs, while N-Shh inhibits it. At molecular level, N-Shh prevents FL-Dhh binding to Patched-1 demonstrating that N-Shh acts as competitive antagonist to FL-Dhh. Besides, we found that even though FL-Hh ligands and N-Hh ligands all bind Patched-1, they induce distinct Patched-1 localization. Finally, we confirmed that in a pathophysiological setting i.e. brain inflammation, astrocyte-derived N-Shh act as a FL-Dhh antagonist. The present study highlights for the first time that FL-Dhh and N-Hh ligands have antagonistic properties especially in ECs. As a consequence, Hh ligands or forms of Hh ligands cannot be used instead of another for therapeutic purposes
Partial Mural Cell Ablation Disrupts Coronary Vasculature Integrity and Induces Systolic Dysfunction
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 (â60%) in the heart of adult mice. Methods and Results To deplete pericytes in adult mice, we used plateletâderived growth factor receptor ÎČâCre/ERT2; RosaDTA mice and compared their phenotype with that of control mice (RosaDTA) chosen among their littermates. Cardiac function was assessed via echocardiography and left ventricular catheterization 1âmonth after the first tamoxifen injection. We found mice depleted with pericytes had a reduced left ventricular ejection fraction and an increased endâdiastolic 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/dtmin). 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