Salidroside Ameliorated Intermittent Hypoxia-Aggravated Endothelial Barrier Disruption and Atherosclerosis via the cAMP/PKA/RhoA Signaling Pathway

Abstract

Background: Endothelial barrier dysfunction plays a key role in atherosclerosis progression. The primary pathology of obstructive sleep apnea-hypopnea syndrome is chronic intermittent hypoxia (IH), which induces reactive oxygen species (ROS) overproduction, endothelial barrier injury, and atherosclerosis. Salidroside, a typical pharmacological constituent of Rhodiola genus, has documented antioxidative, and cardiovascular protective effects. However, whether salidroside can improve IH-aggravated endothelial barrier dysfunction and atherosclerosis has not been elucidated.Methods and results: In normal chow diet-fed ApoE−/− mice, salidroside (100 mg/kg/d, p. o.) significantly ameliorated the formation of atherosclerotic lesions and barrier injury aggravated by 7-weeks IH (21%–5%–21%, 120 s/cycle). In human umbilical vein endothelial cells (HUVECs), exposure to IH (21%–5%–21%, 40 min/cycle, 72 cycles) decreased transendothelial electrical resistance and protein expression of vascular endothelial cadherin (VE-cadherin) and zonula occludens 1. In addition, IH promoted ROS production and activated ras homolog gene family member A (RhoA)/Rho-associated protein kinase (ROCK) pathway. All of these effects of IH were reversed by salidroside. Similar to salidroside, ROCK-selective inhibitors Y26732, and Fasudil protected HUVECs from IH-induced ROS overproduction and endothelial barrier disruption. Furthermore, salidroside increased intracellular cAMP levels, while the PKA-selective inhibitor H-89 attenuated the effects of salidroside on IH-induced RhoA/ROCK suppression, ROS scavenging, and barrier protection.Conclusion: Our findings demonstrate that salidroside effectively ameliorated IH-aggravated endothelial barrier injury and atherosclerosis, largely through the cAMP/PKA/RhoA signaling pathway.

Inhibition of Vascular Endothelial Cadherin Cleavage Prevents Elastic Fiber Alterations and Atherosclerosis Induced by Intermittent Hypoxia in the Mouse Aorta

“…Our results are consistent with previous studies, out of the IH context, which demonstrated that the inhibition of VE-cadherin cleavage [37], tyrosine-kinases [37,38], src-kinases [39,40] and HIF-1 [41,42] protects against atherosclerosis in ApoE-/-mice. However, we could not exclude the contribution of other pathways activated by IH, such as cAMP/PKA/RhoA [19], inflammation [10,43], NF-kB/TNFα pathways [16,27], cysteinyl-leukotriene pathway [44] and cyclooxygenase pathway [45].…”

“…The depletion of VE-cadherin from endothelial cell membranes is responsible for increased endothelial permeability [19,22,23], which could facilitate the infiltration of pro-atherogenic molecules or cells into the vascular wall. Supporting this hypothesis, we demonstrated, in vitro through an endothelial monolayer, an IH-induced increase in LDL passage (+37%) and monocyte migration (+78%), both being atherogenic mediators.…”

“…Actually, endothelial hyperpermeability, a crucial and early step in atherogenesis, could facilitate lipid flux and inflammatory molecule/cell migration across the endothelium [17]. However, the disruption of endothelial integrity and increase in endothelium permeability has only been sparsely studied in OSAS patients and experimental models of IH, such as in rodents [18,19] and cell cultures [14,[19][20][21], and the contribution of hyperpermeability to early atherogenesis induced by IH is not well described. We therefore hypothesized that IH could increase in vivo endothelial permeability through its favoring action on HIF-1/VEGFR/Src-mediated VE-cadherin cleavage, thereby enhancing transendothelium flux of proatherogenic molecules/cells and leading to early arterial wall alterations, including elastic fiber degradation and atherosclerotic lesions.…”

Intermittent hypoxia inhibits epinephrine-induced transcriptional changes in human aortic endothelial cells

“…In contrast to Polotsky et al, IH-induced changes were found to be HIFdependent. Other studies using HUVECs 31 and HAECs 32 showed increased permeability evidenced by decreased transendothelial electrical resistance and increased expression of vascular endothelial cadherin (VE-cadherin). IH-induced increased permeability in HAECs was both HIF and oxidant dependent 32 .…”

“…Since EC activation or dysfunction may precede the development of cardiovascular disease, there has been significant interest into determining mechanisms by which OSA affects EC function. Studies evaluating the effects of IH on ECs have shown increased production of pro-inflammatory cytokines, and adhesion molecules consistent with EC activation [28][29][30][31][32][33] . Using gene array, Polotsky et al found that short-term (8 h) exposure to human aortic endothelial cells (HAECs) led to increased expression of pro-inflammatory cytokines particularly IL-8 and NRF2 target genes; however, IH changed neither hypoxia-inducible factor-1α (HIF1A) nor HIF target gene expression 28 .…”