P120 catenin attenuates the angiotensin II-induced apoptosis of human umbilical vein endothelial cells by suppressing the mitochondrial pathway

Catecholamine induces endothelial dysfunction via Angiotensin II and intermediate conductance calcium activated potassium channel

Endothelial dysfunction contributes to the pathogenesis of Takotsubo syndrome (TTS). However, the exact mechanism underlying endothelial dysfunction in the setting of TTS has not been completely clarified. This study aims to investigate the roles of angiotensin II (Ang II) and intermediate-conductance Ca2+-activated K+ (SK4) channels in catecholamine-induced endothelial dysfunction. Human cardiac microvascular endothelial cells (HCMECs) were exposed to 100 µM epinephrine (Epi), mimicking the setting of TTS. Epi treatment increased the ET-1 concentration and reduced NO levels in HCMECs. Importantly, the effects of Epi were found to be mitigated in the presence of Ang II receptor blockers. Furthermore, Ang II mimicked Epi effects on ET-1 and NO production. Additionally, Ang II inhibited tube formation and increased cell apoptosis. The effects of Ang II could be reversed by an SK4 activator NS309 and mimicked by an SK4 channel blocker TRAM-34. Ang II also inhibited the SK4 channel current (ISK4) without affecting its expression level. Ang II could depolarize the cell membrane potential. Ang II promoted ROS release and reduced protein kinase A (PKA) expression. A ROS blocker prevented Ang II effect on ISK4. The PKA activator Sp-8-Br-cAMPS increased SK4 channel currents. Epinephrine enhanced the activity of ACE by activating the α1 receptor/Gq/PKC signal pathway, thereby promoting the secretion of Ang II. The study suggested that high-level catecholamine can increase Ang II release from endothelial cells by α1 receptors/Gq/PKC signal pathway. Ang II can inhibit SK4 channel current by increasing ROS generation and reducing PKA expression, thereby contributing to endothelial dysfunction.

Does an apple a day keep away diseases? Evidence and mechanism of action

Apples and their products exemplify the recently reemphasized link between dietary fruit intake and the alleviation of human disease. Their consumption does indeed improve human health due to their high phytochemical content. To identify potentially relevant articles from clinical trials, some epidemiological studies and meta-analyses, and in vitro and in vivo studies (cell cultures and animal models), PubMed was searched from January 1, 2012, to May 15, 2022. This review summarized the potential effects of apple and apple products (juices, puree, pomace, dried apples, extracts rich in apple bioactives and single apple bioactives) on health. Apples and apple products have protective effects against cardiovascular diseases, cancer, as well as mild cognitive impairment and promote hair growth, healing of burn wounds, improve the oral environment, prevent niacin-induced skin flushing, promote the relief of UV-induced skin pigmentation, and improve the symptoms of atopic dermatitis as well as cedar hay fever among others. These effects are associated with various mechanisms, such as vascular endothelial protection, blood lipids lowering, anti-inflammatory, antioxidant, antiapoptotic, anti-invasion, and antimetastatic effects. Meanwhile, it has provided an important reference for the application and development of medicine, nutrition, and other fields.

Inflammation and hypertension: Underlying mechanisms and emerging understandings

Hypertension remains a major contributor to cardiovascular disease (CVD), a leading cause of global death. One of the major insults that drive increased blood pressure is inflammation. While it is the body's defensive response against some homeostatic imbalances, inflammation, when dysregulated, can be very deleterious. In this review, we highlight and discuss the causative relationship between inflammation and hypertension. We critically discuss how the interplay between inflammation and reactive oxygen species evokes endothelial damage and dysfunction, ultimately leading to narrowing and stiffness of blood vessels. This, along with phenotypic switching of the vascular smooth muscle cells and the abnormal increase in extracellular matrix deposition further exacerbates arterial stiffness and noncompliance. We also discuss how hyperhomocysteinemia and microRNA act as links between inflammation and hypertension. The premises we discuss suggest that the blue-sky scenarios for targeting the underlying mechanisms of hypertension necessitate further research.

Role of angiotensin II in aging

Aging is an inevitable progressive decline in physiological organ function that increases the chance of disease and death. The renin-angiotensin system (RAS) is involved in the regulation of vasoconstriction, fluid homeostasis, cell growth, fibrosis, inflammation, and oxidative stress. In recent years, unprecedented advancement has been made in the RAS study, particularly with the observation that angiotensin II (Ang II), the central product of the RAS, plays a significant role in aging and chronic disease burden with aging. Binding to its receptors (Ang II type 1 receptor - AT1R in particular), Ang II acts as a mediator in the aging process by increasing free radical production and, consequently, mitochondrial dysfunction and telomere attrition. In this review, we examine the physiological function of the RAS and reactive oxygen species (ROS) sources in detail, highlighting how Ang II amplifies or drives mitochondrial dysfunction and telomere attrition underlying each hallmark of aging and contributes to the development of aging and age-linked diseases. Accordingly, the Ang II/AT1R pathway opens a new preventive and therapeutic direction for delaying aging and reducing the incidence of age-related diseases in the future.

Upregulation of microRNA-34a enhances myocardial ischemia-reperfusion injury via the mitochondrial apoptotic pathway

Mitochondrial oxidative injury can result in many cardiovascular diseases including cardiac ischemia-reperfusion (I/R) injury. This study was designed to investigate whether microRNA-34a (miR-34a) influences cardiac I/R or hypoxia/reoxygenation (H/R) injury by regulating the mitochondrial apoptotic pathway from oxidative injury.In vivo, myocardial infarction size was examined by Evan blue/TTC staining. Apoptosis was assessed by TUNEL assay. Heart function was measured by echocardiography. Lactate dehydrogenase (LDH) and creatine kinase (CK) were evaluated. In vitro, H9c2 cardiomyocytes were exposed to H/R stimulation. Cell viability was assessed by the CCK-8 assay and apoptosis was detected by Annexin V/PI staining. Mitochondrial superoxide, mitochondrial membrane potential (MMP) and ATP production was evaluated by detection kits, and related proteins were detected by western blotting analysis. We observed that the level of miR-34a was significantly upregulated in I/R rats compared to the sham group. Injection of adenovirus inhibiting miR-34a into the left ventricular anterior wall improved heart function and decreased I/R injury. H9c2 cardiomyocytes exposed to H/R stimulation displayed an obvious increase in miR-34a expression. In addition, miR-34a inhibitor alleviated, whereas miR-34a mimic aggravated H/R-induced mitochondrial injury. Bcl-2 was identified as a target gene of miR-34a by dual-luciferase reporter gene detection. Knockdown of Bcl-2 abolished the cardioprotection of the miR-34a inhibitor in H9c2 cells. In summary,our study demonstrates that inhibition of miR-34a exhibits therapeutic potential in treatment of myocardial I/R injury by restraining mitochondrial apoptosis.

Protective effect of recombinant Lactobacillus plantarum against H2O2-induced oxidative stress in HUVEC cells

This study probed the protective effect of recombinant Lactobacillus plantarum against hydrogen peroxide (H₂O₂)-induced oxidative stress in human umbilical vein endothelial cells (HUVECs). We constructed a new functional L. plantarum (NC8-pSIP409-alr-angiotensin-converting enzyme inhibitory peptide (ACEIP)) with a double-gene-labeled non-resistant screen as an expression vector. A 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) colorimetric assay was carried out to determine the cell viability of HUVEC cells following pretreatment with NC8-pSIP409-alr-ACEIP. Flow cytometry (FCM) was used to determine the apoptosis rate of HUVEC cells. Cysteinyl aspartate specific proteinase (caspase)-3/8/9 activity was also assayed and western blotting was used to determine protein expression of B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), inducible nitric oxide synthase (iNOS), nicotinamide adenine dinucleotide phosphate oxidase 2 (gp91phox), angiotensin II (AngII), and angiotensin-converting enzyme 2 (ACE2), as well as corresponding indicators of oxidative stress, such as reactive oxygen species (ROS), mitochondrial membrane potential (MMP), malondialdehyde (MDA), and superoxide dismutase (SOD). NC8-pSIP409-alr-ACEIP attenuated H₂O₂-induced cell death, as determined by the MTT assay. NC8-pSIP409-alr-ACEIP reduced apoptosis of HUVEC cells by FCM. In addition, compared to the positive control, the oxidative stress index of the H₂O₂-induced HUVEC (Hy-HUVEC), which was pretreated by NC8-pSIP409-alr-ACEIP, iNOS, gp91phox, MDA, and ROS, was decreased obviously; SOD expression level was increased; caspase-3 or -9 was decreased, but caspase-8 did not change; Bcl-2/Bax ratio was increased; permeability changes of mitochondria were inhibited; and loss of transmembrane potential was prevented. Expression of the hypertension-related protein (AngII protein) in HUVEC cells protected by NC8-pSIP409-alr-ACEIP decreased and expression of ACE2 protein increased. These plantarum results suggested that NC8-pSIP409-alr-ACEIP protects against H₂O₂-induced injury in HUVEC cells. The mechanism for this effect is related to enhancement of antioxidant capacity and apoptosis.

Qiliqiangxin alleviates Ang II-induced CMECs apoptosis by downregulating autophagy via the ErbB2-AKT-FoxO3a axis

Our previous work revealed the protective effect of Qiliqiangxin (QLQX) on cardiac microvascular endothelial cells (CMECs), but the underlying mechanisms remain unclear. We aimed to investigate whether QLQX exerts its protective effect against high-concentration angiotensin II (Ang II)-induced CMEC apoptosis through the autophagy machinery. CMECs were cultured in high-concentration Ang II (1 μM) medium in the presence or absence of QLQX for 48 h. We found that QLQX obviously inhibited Ang II-triggered autophagosome synthesis and apoptosis in cultured CMECs. QLQX-mediated protection against Ang II-induced CMEC apoptosis was reversed by the autophagy activator rapamycin. Specifically, deletion of ATG7 in cultured CMECs indicated a detrimental role of autophagy in Ang II-induced CMEC apoptosis. QLQX reversed Ang II-mediated ErbB2 phosphorylation impairment. Furthermore, inhibition of ErbB2 phosphorylation with lapatinib in CMECs revealed that QLQX-induced downregulation of Ang II-activated autophagy and apoptosis was ErbB2 phosphorylation-dependent via the AKT-FoxO3a axis. Activation of ErbB2 phosphorylation by Neuregulin-1β achieved a similar CMEC-protective effect as QLQX in high-concentration Ang II medium, and this effect was also abolished by autophagy activation. These results show that the CMEC-protective effect of QLQX under high-concentration Ang II conditions could be partly attributable to QLQX-mediated ErbB2 phosphorylation-dependent downregulation of autophagy via the AKT-FoxO3a axis.

Exosome-Mediated Transfer of ACE2 (Angiotensin-Converting Enzyme 2) from Endothelial Progenitor Cells Promotes Survival and Function of Endothelial Cell

Angiotensin-converting enzyme 2 (ACE2) is an emerging cardiovascular protective target that mediates the metabolism of angiotensin (Ang) II into Ang (1–7). Our group has demonstrated that ACE2 overexpression enhances the function of endothelial progenitor cells (EPCs). Here, we investigated whether ACE2-primed EPCs (ACE2-EPCs) can protect cerebral microvascular endothelial cells (ECs) against injury and dysfunction in an in vitro model, with focusing on their exosomal and cytokine paracrine effects on endothelial mitochondria. Human EPCs were transfected with lentivirus containing null or human ACE2 cDNA (denoted as Null-EPCs and ACE2-EPCs, respectively). Their conditioned culture media, w/wo depletion of exosomes (ACE2-EPC-CM^EX-, Null-EPC-CM^EX-, ACE2-EPC-CM, and Null-EPC-CM), were used for coculture experiments. EC injury and dysfunction model was induced by Ang II before coculture. Apoptosis, angiogenic ability, mitochondrion functions (ROS production, membrane potential, fragmentation), and gene expressions (ACE2, Nox2, and Nox4) of ECs were analyzed. The supernatant was collected for measuring the levels of ACE2, Ang II/Ang-(1–7), and growth factors (VEGF and IGF). Our results showed that (1) ACE2-EPC-CM had higher levels of ACE2, Ang (1–7), VEGF, and IGF than that of Null-EPC-CM. (2) Ang II-injured ECs displayed an increase of apoptotic rate and reduction in tube formation and migration abilities, which were associated with ACE2 downregulation, Ang II/Ang (1–7) imbalance, Nox2/Nox4 upregulation, ROS overproduction, an increase of mitochondrion fragmentation, and a decrease of membrane potential. (3) ACE2-EPC-CM had better protective effects than Null-EPC-CM on Ang II-injured ECs, which were associated with the improvements on ACE2 expression, Ang II/Ang (1–7) balance, and mitochondrial functions. (4) ACE2-EPC-CM^EX- and Null-EPC-CM^EX- showed reduced effects as compared to ACE2-EPCs-CM and Null-EPCs-CM. In conclusion, our data demonstrate that ACE2 overexpression can enhance the protective effects of EPCs on ECs injury, majorly through the exosomal effects on mitochondrial function.

Angiotensin-converting enzyme 2 regulates mitochondrial function in pancreatic β-cells

Mitochondrial metabolism plays an essential role in the regulation of insulin release and glucose homeostasis. Evidence demonstrated that the angiotensin-converting enzyme 2 (ACE2) participates in the regulation of glucose metabolism, however, its role in mitochondrial metabolism remains unclear. The purpose of our study was to determine if ACE2 can regulate mitochondrial function in pancreatic β-cells. We found that ACE2 over-expression restored glucose-stimulated insulin secretion (GSIS) and mitochondrial membrane potential (MMP) in the presence of H₂O₂ in INS-1 cells. PCR array demonstrated that ACE2 over-expression up-regulated 67 mitochondria-related genes in INS-1 cells. In pancreatic islets, ACE2 ablation attenuated intracellular calcium influx with a decrease in GSIS. Ace2^-/y mice islets exhibited impaired mitochondrial respiration and lower production of ATP, along with decreased expression of genes involved in mitochondrial oxidation. In islets from db/db mice, ACE2 over-expression increased intracellular calcium influx and restored impaired mitochondrial oxidation, potentially causing an increase in GSIS. These results shed light on the potential roles of ACE2 in mitochondrial metabolism, moreover, may improve our understanding of diabetes.

TDB protects vascular endothelial cells against oxygen-glucose deprivation/reperfusion-induced injury by targeting miR-34a to increase Bcl-2 expression

Prolonged ischemia can result in apoptotic death of vascular endothelial cells and lead to ischemic vascular diseases including vascular dementia, arteriosclerosis and brain oedema. Finding protective strategies to prevent this is therefore an urgent mission. Recent studies have shown that dysregulation of microRNAs (miRNAs) can lead to imbalance of Bcl-2 family proteins and mitochondrial dysfunction, leading to further damage of vascular cells under ischemic conditions. However, whether miRNAs can be used as a drug target for treating vascular diseases is not fully understood. In this study, we observed that the natural product 2,4,5-trihydroxybenzaldehyde (TDB) could effectively inhibit vascular cell apoptosis following oxygen-glucose deprivation/reperfusion (OGD/R) by maintaining mitochondrial membrane potential (MMP) and suppressing activation of the mitochondria-dependent caspase-9/3 apoptosis pathway. Furthermore, we identified miR-34a, a crucial negative regulator of Bcl-2, as a target for the protective effect of TDB on vascular cells. TDB-induced suppression of miR-34a resulted in a significant upregulation of Bcl-2 protein, MMP maintenance, and the survival of vascular cells following OGD/R. Our findings suggest that targeting miR-34a with the natural product TDB may provide a novel strategy for the treatment of ischemic vascular injuries, and demonstrate the therapeutic potential in targeting miRNAs using appropriate small molecules.

Toll-like receptor 4 mutation suppresses hyperhomocysteinemia-induced hypertension

Hyperhomocysteinemia (HHcy) has been observed to promote hypertension, but the mechanisms are unclear. Toll-like receptor 4 (TLR-4) is a cellular membrane protein that is ubiquitously expressed in all cell types of the vasculature. TLR-4 activation has been known to promote inflammation that has been associated with the pathogenesis of hypertension. In this study we hypothesize that HHcy induces hypertension by TLR-4 activation, which promotes inflammatory cytokine (IL-1β, IL-6, and TNF-α) upregulation and initiation of mitochondria-dependent apoptosis, leading to cell death and chronic vascular inflammation. To test this hypothesis, we used C57BL/6J (WT) mice, cystathionine β-synthase (CBS)-deficient (CBS^+/-) mice with genetic mild HHcy, C3H/HeJ (C3H) mice with TLR-4 mutation, and mice with combined genetic HHcy and TLR-4 mutation (CBS^+/-/C3H). Ultrasonography of the superior mesenteric artery (SMA) detected an increase in wall-to-lumen ratio, resistive index (RI), and pulsatility index (PI). Tail cuff blood pressure (BP) measurement revealed elevated BP in CBS^+/- mice. RI, PI, and wall-to-lumen ratio of the SMA in CBS^+/-/C3H mice were similar to the control group, and BP was significantly alleviated. TLR-4, IL-1β, IL-6, and TNF-α expression were upregulated in the SMA of CBS^+/- mice and reduced in the SMA of CBS^+/-/C3H mice. Molecules involved in the mitochondria-mediated cell death pathway (BAX, caspase-9, and caspase-3) were upregulated in CBS^+/- mice and attenuated in CBS^+/-/C3H mice. We conclude that HHcy promotes TLR-4-driven chronic vascular inflammation and mitochondria-mediated cell death, inducing hypertension. TLR-4 mutation attenuates vascular inflammation and cell death, which suppress hypertension.