Fasudil improves endothelial dysfunction in rats exposed to chronic intermittent hypoxia through RhoA/ROCK/NFATc3 pathway

Effect of aortic smooth muscle BK channels on mediating chronic intermittent hypoxia-induced vascular dysfunction

Chronic intermittent hypoxia (CIH) can lead to vascular dysfunction and increase the risk of cardiovascular diseases, cerebrovascular diseases, and arterial diseases. Nevertheless, mechanisms underlying CIH-induced vascular dysfunction remain unclear. Herein, this study analyzed the role of aortic smooth muscle calciumactivated potassium (BK) channels in CIH-induced vascular dysfunction. CIH models were established in rats and rat aortic smooth muscle cells (RASMCs). Hemodynamic parameters such as mean blood pressure (MBP), diastolic blood pressure (DBP), and systolic blood pressure (SBP) were measured in rats, along with an assessment of vascular tone. NO and ET-1 levels were detected in rat serum, and the levels of ET-1, NO, eNOS, p-eNOS, oxidative stress markers (ROS and MDA), and inflammatory factors (IL-6 and TNF-α) were tested in aortic tissues. The Ca2+ concentration in RASMCs was investigated. The activity of BK channels (BKα and BKβ) was evaluated in aortic tissues and RASMCs. SBP, DBP, and MBP were elevated in CIH-treated rats, along with endothelial dysfunction, cellular edema and partial detachment of endothelial cells. BK channel activity was decreased in CIH-treated rats and RASMCs. BK channel activation increased eNOS, p-eNOS, and NO levels while lowering ET-1, ROS, MDA, IL-6, and TNF-α levels in CIH-treated rats. Ca2+ concentration increased in RASMCs following CIH modeling, which was reversed by BK channel activation. BK channel inhibitor (Iberiotoxin) exacerbated CIH-induced vascular disorders and endothelial dysfunction. BK channel activation promoted vasorelaxation while suppressing vascular endothelial dysfunction, inflammation, and oxidative stress, thereby indirectly improving CIH-induced vascular dysfunction.

Intermittent hypoxia increased the expression of ESM1 and ICAM-1 in vascular endothelial cells via the downregulation of microRNA-181a1

Sleep apnea syndrome (SAS) exposes cells throughout the body to intermittent hypoxia (IH). Intermittent hypoxia is a risk factor not only for hypertension and insulin resistance but also for vascular dysfunction. We have reported correlations between IH, insulin resistance and hypertension. However, the details of why IH leads to vascular dysfunction remain unclear. In this study, we investigated inflammation-related transcripts in vascular endothelial cells (human HUEhT-1 and mouse UV2) exposed to IH by real-time RT-PCR and found that intercellular adhesion molecule-1 (ICAM-1) and endothelial cell-specific molecule-1 (ESM1) mRNAs were significantly increased. ELISA confirmed that, in the UV2 cell medium, ICAM-1 and ESM1 were significantly increased by IH. However, the promoter activities of ICAM-1 and ESM1 were not upregulated. On the other hand, IH treatment significantly decreased microRNA (miR)-181a1 in IH-treated cells. The introduction of miR-181a1 mimic but not miR-181a1 mimic NC abolished the IH-induced upregulation of Ican-1 and ESM1. These results indicated that ICAM-1 and ESM1 were upregulated by IH via the IH-induced downregulation of miR-181a1 in vascular endothelial cells and suggested that SAS patients developed atherosclerosis via the IH-induced upregulation of ICAM-1 and ESM1.

New Insights into lncRNAs in Aβ Cascade Hypothesis of Alzheimer's Disease

Alzheimer's disease (AD) is the most common type of dementia, but its pathogenesis is not fully understood, and effective drugs to treat or reverse the progression of the disease are lacking. Long noncoding RNAs (lncRNAs) are abnormally expressed and deregulated in AD and are closely related to the occurrence and development of AD. In addition, the high tissue specificity and spatiotemporal specificity make lncRNAs particularly attractive as diagnostic biomarkers and specific therapeutic targets. Therefore, an in-depth understanding of the regulatory mechanisms of lncRNAs in AD is essential for developing new treatment strategies. In this review, we discuss the unique regulatory functions of lncRNAs in AD, ranging from Aβ production to clearance, with a focus on their interaction with critical molecules. Additionally, we highlight the advantages and challenges of using lncRNAs as biomarkers for diagnosis or therapeutic targets in AD and present future perspectives in clinical practice.

TARBP2-stablized SNHG7 regulates blood-brain barrier permeability by acting as a competing endogenous RNA to miR-17-5p/NFATC3 in Aβ-microenvironment

Breakdown of blood-brain barrier (BBB) is recognized as serious pathological marker of Alzheimer's disease development. Studies confirmed that β-amyloid (Aβ) deposition induced high BBB permeability by disrupting tight junction (TJ) proteins formed from endothelial cells (ECs). Here, we found TARBP2, SNHG7 and NFATC3 in expressions were increased and miR-17-5p expression was decreased in Aβ(1-42)-incubated ECs. Overexpression of TARBP2, SNHG7 and NFATC3 elevated BBB permeability and knockdown of them had converse results. Agomir-17-5p decreased BBB permeability and antagomir-17-5p increased BBB permeability. TARBP2 as a RNA-binding protein (RBP) bound to SNHG7 and resulted in longer half-life of SNHG7. The decreased expression of miR-17-5p had a negative post-transcriptional regulation to NFATC3, leading to the increased expression of NFATC3. In addition, SNHG7 regulated NFATC3 expression by acting as a molecule sponge targeting to miR-17-5p. NFATC3 inhibited TJ proteins expression by functioning as a transcription factor. TARBP2/SNHG7/miR-17-5p/NFATC3 pathway implied a potential mechanism in studies of BBB changes in AD pathological progression.

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

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.

O‑GlcNAcylation contributes to intermittent hypoxia‑associated vascular dysfunction via modulation of MAPKs but not CaMKII pathways

Intermittent hypoxia (IH) leads to vascular dysfunction, and O-linked-β-N-acetylglucosamine (O-GlcNAc)ylation may regulate vascular reactivity through the modulation of intracellular signaling. The present study hypothesized that O-GlcNAc modifications contributed to the vascular effects of acute IH (AIH) and chronic IH (CIH) through the MAPK and Ca²⁺/calmodulin-dependent kinase II (CaMKII) pathways. Rat aortic and mesenteric segments were incubated with DMSO, O-GlcNAcase (OGA) or O-GlcNAc transferase (OGT) inhibitor under either normoxic or AIH conditions for 3 h, and arterial function was then assessed. Meanwhile, arteries isolated from control and CIH rats were exposed to 3 h of incubation under normoxic conditions using DMSO, OGA or OGT as an inhibitor, before assessing arterial reactivity. CIH was found to increase the expression of vascular O-GlcNAc protein and OGT, phosphorylate p38 MAPK and ERK1/2, and decrease OGA levels, but it had no effects on phosphorylated CaMKII levels. OGA inhibition increased global O-GlcNAcylation and the phosphorylation of p38 MAPK, ERK1/2 and CaMKII, whereas OGT blockade had the opposite effects. OGA inhibition preserved acetylcholine-induced relaxation in AIH arteries, whereas OGT blockade attenuated the relaxation responses of arteries under normoxic conditions or undergoing AIH treatments. However, the impairment of acetylcholine dilation in CIH mesenteric arteries was improved. CIH artery contraction was increased following angiotensin II (Ang II) exposure. Blockade of p38 MAPK and ERK1/2, but not CaMKII, attenuated Ang II-induced contractile responses in CIH arteries isolated from the non-OGT inhibitor-treated groups. OGT inhibition significantly blocked contractile responses to Ang II and abolished the inhibitory effects of MAPK inhibitors. These findings indicated that O-GlcNAcylation regulates IH-induced vascular dysfunction, at least partly by modulating MAPK, but not CaMKII, signaling pathways.

ROCK Inhibition as Potential Target for Treatment of Pulmonary Hypertension

Pulmonary hypertension (PH) is a cardiovascular disease caused by extensive vascular remodeling in the lungs, which ultimately leads to death in consequence of right ventricle (RV) failure. While current drugs for PH therapy address the sustained vasoconstriction, no agent effectively targets vascular cell proliferation and tissue inflammation. Rho-associated protein kinases (ROCKs) emerged in the last few decades as promising targets for PH therapy, since ROCK inhibitors demonstrated significant anti-remodeling and anti-inflammatory effects. In this review, current aspects of ROCK inhibition therapy are discussed in relation to the treatment of PH and RV dysfunction, from cell biology to preclinical and clinical studies.

Intermittent hypoxia-induced autophagy via AMPK/mTOR signaling pathway attenuates endothelial apoptosis and dysfunction in vitro

PURPOSE

The aim of this study was to examine whether or not intermittent hypoxia (IH) upregulated autophagy and the contributions of autophagy to endothelial apoptosis and dysfunction in human umbilical vein endothelial cells (HUVECs).

METHOD

HUVECs were incubated under normoxia and IH conditions. After 3-, 6-, 12-, and 24-h exposure, the autophagic vacuoles and autophagosomes were observed by transmission electron microscopy and monodansylcadaverine staining. The protein levels of autophagy-related biomarkers and AMPK/mTOR pathway were measured by Western blot. The apoptosis-related proteins and the percentage of apoptotic cells were evaluated by Western blot and flow cytometry, respectively, while the levels of endothelial function biomarkers were assessed by ELISA.

RESULTS

IH induced autophagy, as determined by the increased numbers of the autophagic vacuoles, autophagosomes, and by the elevated levels of Beclin-1 protein, the LC3II/LC3I ratio, and p62 degradation. IH-induced autophagic flux peaked at 12-h duration and weakened at 24 h. IH increased the ratio of p-AMPK/AMPK and decreased the ratio of p-mTOR/mTOR, while compound C restored the alteration. A significant decrease in the Bcl-2 level and the Bcl-2/Bax ratio and a significant increase in the protein expression levels of Bax and cleaved caspase 3 and in the percentage of apoptosis were observed under IH exposure. Moreover, the NO level was reduced, while the ET-1 and VEGF levels were raised under IH condition. These alterations were suppressed by the pretreatment of 3-methyladenine.

CONCLUSIONS

IH upregulates autophagy through AMPK/mTOR pathway in HUVECs in vitro, which might be protective against endothelial apoptosis and dysfunction caused by IH.

Obstructive sleep apnoea and cardiovascular disease: a literature review

As obesity becomes more common worldwide, the prevalence of obstructive sleep apnoea (OSA) continues to rise. Obstructive sleep apnoea is a well-known disorder that causes chronic intermittent hypoxia (CIH), which is considered a risk factor for atherosclerosis directly and indirectly. Ischaemic heart disease remains the leading cause of death. Most risk factors for atherosclerosis are well understood. However, other factors such as CIH are less well understood. Several studies have investigated the pathophysiology of CIH, attempting to uncover its link to atherosclerosis and to determine whether OSA treatment can be a therapeutic modality to modify the risk for atherosclerosis. In this article, we will review the pathophysiology of OSA as an independent risk factor for cardiovascular disease and discuss the most common markers that have been studied. We will also examine the potential impact of OSA management as a risk factor modifier on the reversibility of atherosclerosis.

Pharmacological Effects of Fasudil on Flap Survival in a Rodent Model

BACKGROUND

Necrosis of the perforator flap is a critical problem. Fasudil, an inhibitor of Rho-associated coiled-coil containing kinase, has antiapoptosis activity and attenuates oxidative stress in many diseases. We characterized the effects of fasudil through intraperitoneal injection on perforator flap survival and identified its possible mechanism.

METHODS AND MATERIALS

Rats were divided into a control group (without surgery), a flap group (only surgery), and a fasudil group (surgery plus fasudil). Perforator flaps were made on the backs of the rats. The expression of vascular endothelial growth factor, the protein kinase B (PKB/Akt), endothelial nitric oxide synthase, Bax, Bcl-2, Beclin-1, P62, and LC3 II/LC3 I was determined by Western blot at day 3 after surgery. Nitric oxide (NO) components, superoxide dismutase, and malondialdehyde were also measured at day 3. The survival rate and laser Doppler perfusion imaging were performed at day 7 after surgery.

RESULT

The group with fasudil treatment exhibited the higher survival rates and angiogenesis levels. Fasudil also induced the activation of Akt/eNOS/NO pathway detected by the Western blot and NO expression kit. Furthermore, Western blot results showed fasudil-attenuated apoptosis through a raised Bcl-2/Bax rate and enhanced autophagy levels through raised beclin-1, decreased p62, and the elevated rate of LC3 II/LC3 I. Finally, fasudil increased superoxide dismutase and decreased malondialdehyde.

CONCLUSIONS

In conclusion, fasudil treatment decreased necrosis of perforator flaps possibly by affecting the Akt/eNOS/NO pathway, attenuating apoptosis and activating autophagy.