PDE4 inhibition reduces neointima formation and inhibits VCAM-1 expression and histone methylation in an Epac-dependent manner

Robichaux

et al. 2016

Sci Rep

Vascular smooth muscle cell (VSMC) activation in response to injury plays an important role in the development of vascular proliferative diseases, including restenosis and atherosclerosis. The aims of this study were to ascertain the physiological functions of exchange proteins directly activated by cAMP isoform 1 (Epac1) in VSMC and to evaluate the potential of Epac1 as therapeutic targets for neointima formation during vascular remodeling. In a mouse carotid artery ligation model, genetic knockdown of the Epac1 gene led to a significant reduction in neointima obstruction in response to vascular injury. Pharmacologic inhibition of Epac1 with an Epac specific inhibitor, ESI-09, phenocopied the effects of Epac1 null by suppressing neointima formation and proliferative VSMC accumulation in neointima area. Mechanistically, Epac1 deficient VSMCs exhibited lower level of PI3K/AKT signaling and dampened response to PDGF-induced mitochondrial fission and reactive oxygen species levels. Our studies indicate that Epac1 plays important roles in promoting VSMC proliferation and phenotypic switch in response to vascular injury, therefore, representing a therapeutic target for vascular proliferative diseases.

mentioning

confidence: 68%

Section: Discussionmentioning

confidence: 89%

Inhibition of Epac1 suppresses mitochondrial fission and reduces neointima formation induced by vascular injury

Robichaux

et al. 2016

Sci Rep

Journal of Thrombosis and Haemostasis

“…This hypothesis is further strengthened by the observation that treatment with roflumilast reduces neointima formation following endovascular injury of the femoral artery in mice in vivo .…”

Section: Discussionmentioning

confidence: 95%

Roflumilast inhibits leukocyte–platelet interactions and prevents the prothrombotic functions of polymorphonuclear leukocytes and monocytes

Totani

Amore

Santo

et al. 2016

Essentials• Thrombosis is a major comorbidity in patients with chronic obstructive pulmonary disease (COPD).• Roflumilast is a selective phosphodiesterase type-4 (PDE4)inhibitor approved for treatment of severe COPD.• PDE4 blockade by roflumilast inhibits prothrombotic functions of neutrophils and monocytes.• PDE4 inhibitors may reduce thrombotic risk in COPD as well as in other vascular diseases.Summary. Background Roflumilast, an oral selective phosphodiesterase type 4 inhibitor, is approved for the treatment of severe chronic obstructive pulmonary disease (COPD). A recent meta-analysis of trials on COPD revealed that treatment with roflumilast was associated with a significant reduction in the rate of major cardiovascular events. The mechanisms of this effect remain unknown. Objectives We tested the hypothesis that roflumilast N-oxide (RNO), the active metabolite of roflumilast, curbs the molecular mechanisms required for leukocyteplatelet (PLT) interactions and prevents the prothrombotic functions of polymorphonuclear leukocytes (PMNs) and monocytes (MNs). Methods Using well-characterized in vitro models, we analysed the effects of RNO on: (i) PMN adhesiveness; (ii) the release of neutrophil extracellular traps (NETs); and (iii) tissue factor expression in MNs.Key biochemical events underlying the inhibitory effects of RNO were defined. Results and Conclusions In PMNs, RNO prevented phosphoinositide 3-kinase (PI3K)-dependent phosphorylation of Akt on Ser473, and Src family kinase (SFK)-mediated Pyk2 phosphorylation on Tyr579-580, while inducing protein kinase A-mediated phosphorylation of C-terminal Src kinase, the major negative regulator of SFKs. Modulation of these signaling pathways by RNO resulted in a significant impairment of PMN adhesion to activated PLTs or human umbilical vein endothelial cells, mainly mediated by inhibition of the adhesive function of Mac-1. Moreover RNO curbed SFK/PI3K-mediated NET release by PMNs adherent on fibrinogencoated surfaces. In MNs interacting with activated PLTs, RNO curbed PI3K-mediated expression of tissue factor. The efficacy of RNO was significantly potentiated by formoterol, a long acting b-adrenergic receptor agonist. This study reveals novel antithrombotic activities by which roflumilast may exert protective effects against cardiovascular comorbodities in COPD.

“…A recent study reported that EPAC1 mediates the inhibitory effect of the PDE4D inhibitor, roflumilast on vascular cell adhesion molecule 1 expression in tumor necrosis factor-α-activated VSMCs through histone methylation. 98 These data identify PDE4 inhibition and EPAC activation as a promising mechanism to target vascular inflammation occurring in atherosclerosis and stent restenosis. In addition, EPAC (likely EPAC1) exerts an anti-inflammatory role in cigarette smoke extract stimulated secretion of IL-8.…”

Section: Regulation Of Vascular Inflammationmentioning

confidence: 95%

Cyclic AMP Sensor EPAC Proteins and Their Role in Cardiovascular Function and Disease

Lezoualc’h

Fazal

Laudette

et al. 2016

Circulation Research

145

143

C yclic adenosine 3′,5′-monophosphate (cAMP) is one of the most studied signaling molecules that plays a critical role in cellular responses to extracellular stimuli in the cardiovascular system. It controls a wide range of biological effects, including cell proliferation, differentiation, and apoptosis. 1 cAMP is produced from ATP by transmembrane adenylyl cyclase on activation of Gs-coupled G protein-coupled receptors. 2In addition, soluble adenylyl cyclase is a second intracellular source of cAMP and can be activated by divalent cations in various subcellular compartments.3 The intracellular level of cAMP depends not only on its production by adenylyl cyclase but also its degradation by a large family of cAMP phosphodiesterases (PDEs), which catalyze the hydrolysis of cAMP into 5′-AMP. 4 PDEs are key actors in limiting the spread of cAMP and seem critical for the formation of dynamic microdomains that confer specific response to various hormones. 4 Besides specialized membrane structures that may also limit cAMP diffusion, A-kinase anchoring proteins function to tether cAMP effectors and PDEs enzymes into defined cellular compartments and, therefore, maintain localized pools of cAMP to control the cellular actions of the second messenger. 5Until recently, the intracellular effects of cAMP were attributed to the activation of protein kinase A (PKA) and cyclic nucleotide-gated ion channels. In 1998, a family of novel cAMP effector proteins named exchange proteins directly activated by cAMP (EPACs) was discovered. 6,7 The EPAC protein family is composed of EPAC1 and EPAC2, which act as guanine-nucleotide exchange factors (GEFs) for the small G proteins, Rap1 and Rap2, and function in a PKA-independent manner. 6,7 On binding to cAMP, EPAC promotes the exchange of GDP for GTP, thereby inducing the activation of the small G protein Rap.8 In contrast, Rap-GTPase-activating proteins enhance the intrinsic GTP hydrolysis activity of Rap leading to GTPase inactivation. 9The cycling of Rap between its inactive and active states provides a mechanism to regulate the binding to effector proteins.The discovery of EPAC proteins has broken the dogma surrounding cAMP and PKA, and uncovered new perspectives for the understanding of cAMP signaling in the cardiovascular system. The functions of these cAMP-sensitive GEFs in various subcellular compartments and cellular contexts are currently being unraveled, but given the availability of EPAC-specific ligands and engineered mouse models, a large body of evidence indicates that EPAC proteins are involved in multiple biological actions of cAMP, such as cardiac hypertrophy and vascular inflammation. In this review, after a description of EPAC protein structures and mechanism of activation, we discuss recent advances in the discovery of novel pharmacological modulators of EPAC (Figure 1). We provide an overview of the roles of EPAC proteins, their signalosome and compartmentation in cardiovascular function and diseases. We also discuss the therapeutic potential of EPAC ligands in the t...