Angiotensin-converting enzyme 2 activation suppresses pulmonary vascular remodeling by inducing apoptosis through the Hippo signaling pathway in rats with pulmonary arterial hypertension

EGCG oxidation-derived polymers induce apoptosis in digestive tract cancer cells via regulating the renin-angiotensin system

Green tea polyphenol (-)-Epigallocatechin-3-gallate (EGCG) has been well studied for its biological activities in the prevention of chronic diseases. However, the biological activities of EGCG oxidation-derived polymers remain unclear. Previously, we found that these polymers accumulated in intraperitoneal tissues after intraperitoneal injection and gained an advantage over native EGCG in increasing insulin sensitivity via regulating the renin-angiotensin system (RAS) in type 2 diabetic mice. The present study determined the pro-apoptosis activities and anticancer mechanisms of the EGCG oxidation-derived polymer preparation (the >10 kDa EGCG polymers) in digestive tract cancer cells. Upon incubation of the >10 kDa EGCG polymers with CaCo2 colon cancer cells, these polymers coated the cell surface and regulated multiple components of the RAS in favor of cancer inhibition, including the downregulation of angiotensin-converting enzyme (ACE), angiotensin-II (AngII) and AngII receptor type 1 (AT1R) in the pro-tumor axis, as well as the upregulation of angiotensin-converting enzyme 2 (ACE2) and angiotensin1-7 (Ang(1-7)) in the anti-tumor axis. The treatment also markedly increased angiotensinogen (AGT), which is the precursor of the angiotensin peptides. The regulation of these RAS components occurred prior to apoptosis. Similar pro-apoptotic mechanisms of the >10 kDa EGCG polymers, were also observed in TCA8113 oral cancer cells. The >10 kDa EGCG polymers exhibited compromised activities in scavenging or initiating reactive oxygen species compared to EGCG, but gained a higher reactivity toward sulfhydryl groups, including protein cysteine thiols. We propose that the polymers bind onto the cell surface and regulate multiple RAS components by reacting with the sulfhydryl groups on the ectodomains of transmembrane proteins.

Angiotensin-Converting Enzyme 2 (ACE2) Signaling in Pulmonary Arterial Hypertension: Underpinning Mechanisms and Potential Targeting Strategies

Pulmonary arterial hypertension (PAH) is a debilitating progressive disease characterized by excessive pulmonary vasoconstriction and abnormal vascular remodeling processes that lead to right-ventricular heart failure and, ultimately, death. Although our understanding of its pathophysiology has advanced and several treatment modalities are currently available for the management of PAH patients, none are curative and the prognosis remains poor. Therefore, further research is required to decipher the molecular mechanisms associated with PAH. Angiotensin-converting enzyme 2 (ACE2) plays an important role through its vasoprotective functions in cardiopulmonary homeostasis, and accumulating preclinical and clinical evidence shows that the upregulation of the ACE2/Angiotensin-(1-7)/MAS1 proto-oncogene, G protein-coupled receptor (Mas 1 receptor) signaling axis is implicated in the pathophysiology of PAH. Herein, we highlight the molecular mechanisms of ACE2 signaling in PAH and discuss its potential as a therapeutic target.

A role of TRIM59 in pulmonary hypertension: modulating the protein ubiquitylation modification

BACKGROUND

Pulmonary hypertension (PH), an infrequent disease, is characterized by excessive pulmonary vascular remodeling and proliferation of pulmonary artery smooth muscle cells (PASMCs). However, its underlying molecular mechanisms remain unclear. Uncovering its molecular mechanisms will be beneficial to the treatment of PH.

METHODS

Differently expressed genes (DEGs) in the lung tissues of PH patients were analyzed with a GEO dataset GSE113439. From these DEGs, we focused on TRIM59 which was highly expressed in PH patients. Subsequently, the expression of TRIM59 in the pulmonary arteries of PH patients, lung tissues of PH rat model and PASMCs cultured in a hypoxic condition was verified by quantitative real-time PCR (qPCR), western blot and immunohistochemistry. Furthermore, the role of TRIM59 in PAMSC proliferation and pathological changes in PH rats was assessed via gain-of-function and loss-of-function experiments. In addition, the transcriptional regulation of YAP1/TEAD4 on TRIM59 was confirmed by qPCR, western blot, luciferase reporter assay, ChIP and DNA pull-down. In order to uncover the underlying mechanisms of TRIM59, a protein ubiquitomics and a CoIP- HPLC-MS/MS were companied to identify the direct targets of TRIM59.

RESULTS

TRIM59 was highly expressed in the pulmonary arteries of PH patients and lung tissues of PH rats. Over-expression of TRIM59 accelerated the proliferation of PASMCs, while TRIM59 silencing resulted in the opposite results. Moreover, TRIM59 silencing mitigated the injuries in heart and lung and attenuated pulmonary vascular remodeling during PH. In addition, its transcription was positively regulated by YAP1/TEAD4. Then we further explored the underlying mechanisms of TRIM59 and found that TRIM59 overexpression resulted in an altered ubiquitylation of proteins. Accompanied with the results of CoIP- HPLC-MS/MS, 34 proteins were identified as the direct targets of TRIM59.

CONCLUSION

TRIM59 was highly expressed in PH patients and promoted the proliferation of PASMCs and pulmonary vascular remodeling, thus contributing to the pathogenesis of PH. It is indicated that TRIM59 may become a potential target for PH treatment.

ACE2 gene polymorphisms are associated with elevated pulmonary artery pressure in congenital heart diseases

BACKGROUNDS

Angiotensin converting enzyme 2 (ACE2) polymorphisms are related to the occurrence and prognosis of cardiovascular disease. However, whether ACE2 polymorphisms also affect pulmonary circulation in congenital heart disease (CHD) remains unclear. Thus, we investigated the relationship between ACE2 single nucleotide polymorphism (SNPs) and pulmonary circulation in CHD patients of Chinese Han ethnicity.

METHODS

Enrolled CHD patients (n = 367) underwent gene sequencing of ACE2 SNPs rs2074192, rs2285666, and rs2106809. Patients with pulmonary hypertension were further examined for detailed hemodynamics.

RESULTS

Female heterozygous patients had worse pulmonary circulation hemodynamic parameters compared to those of homozygotes. Female CHD patients with the CCA (OR = 0.53, 95% CI: 0.32-0.88) or CCG (OR = 0.59, 95% CI: 0.35-0.99) haplotype had a lower risk of elevated pulmonary artery pressure.

CONCLUSION

In female CHD patients, ACE2 SNPs are related to pulmonary circulation hemodynamics. Female CHD patients with the CCA and CCG haplotype had a lower risk of pulmonary hypertension.

Salt-inducible kinase 1 deficiency promotes vascular remodeling in pulmonary arterial hypertension via enhancement of yes-associated protein-mediated proliferation

Pulmonary arterial remodeling at an early stage, including excessive proliferation and migration of smooth muscle cells, is a hallmark of pulmonary arterial hypertension (PAH). Salt-inducible kinases (SIKs) have been increasingly reported to play a key role in smooth muscle cell proliferation and phenotype switching, which may be associated with arterial remodeling. However, the potential effects of SIK1 in PAH and the underlying mechanisms have not been explored. The aim of this study was to determine whether reduced expression or inactivation of SIK1 is associated with pulmonary arterial remodeling in PAH and to elucidate whether it is related to the Hippo/Yes-associated protein (YAP) pathway. Using mouse models of PAH and hypoxia-stimulated hPASMCs, we observed that SIK1 expression was robustly reduced in lung tissues of PAH mice and hPASMCs cultured under hypoxia. In hypoxia-induced PAH mice, pharmacological SIK inhibition or AAV9-mediated specific smooth muscle SIK1 knockdown strongly aggravated pathological changes caused by hypoxia, including right ventricular hypertrophy and small pulmonary arterial remodeling. Meanwhile, in hypoxia-stimulated hPASMCs, SIK1 knockdown or inhibition promoted proliferation and migration under hypoxia, accompanied by decreased phosphorylation and increased nuclear accumulation of YAP, while SIK1 overexpression inhibited hypoxia-induced proliferation, migration and nuclear translocation of YAP in hPASMCs. YAP knockdown attenuated the increase in cell proliferation induced by HG-9-91-01 treatment or SIK1 siRNA transfection under hypoxia in hPASMCs. Here, we identified SIK1 as an antiproliferative factor in hypoxia-induced pulmonary arterial remodeling via YAP-mediated mechanisms. These results show that targeting SIK1 may be a promising therapeutic strategy for the treatment of PAH.

Lycopene Ameliorates Hypoxic Pulmonary Hypertension via Suppression of Oxidative Stress

Hypoxic pulmonary hypertension (HPH) is a progressive cardiopulmonary system disease characterized by pulmonary vascular remodeling. Its occurrence and progression are closely related to oxidative stress. Lycopene, extracted from red vegetables and fruits, exhibits a particularly high antioxidant capacity that is beneficial for cardiovascular diseases. Nevertheless, the role and mechanism of lycopene in HPH remain unknown. Here, we found that lycopene reversed the elevated right ventricular systolic pressure (RVSP), right ventricular hypertrophy, and pulmonary vascular remodeling induced by hypoxia in rats. In vitro, lycopene caused lower proliferation and migration of PASMCs, with higher apoptosis. Consistent with the antiproliferative result of lycopene on hypoxic PASMCs, the hippo signaling pathway associated with cell growth was activated. Furthermore, lycopene reduced malondialdehyde (MDA) levels and enhanced superoxide dismutase (SOD) activity in the lungs and serum of rats under hypoxia conditions. The expression of NOX4 in the lungs was also significantly decreased. Hypoxic PASMCs subjected to lycopene showed decreased reactive oxygen species (ROS) production and NOX4 expression. Importantly, lycopene repressed HIF-1α expression both in the lungs and PASMCs in response to hypoxia in the absence of a significant change of HIF-1α mRNA. Compared with 2ME2 (a HIF-1α inhibitor) alone treatment, lycopene treatment did not significantly change PASMC proliferation, NOX4 expression, and ROS production after 2ME2 blocked HIF-1α, suggesting the inhibitory effect of lycopene on HIF-1α-NOX4-ROS axis and the targeted effect on HIF-1α. After CHX blocked protein synthesis, lycopene promoted the protein degradation of HIF-1α. MG-132, a proteasome inhibitor, notably reversed the decrease in HIF-1α protein level induced by lycopene in response to hypoxia. Therefore, lycopene suppressed hypoxia-induced oxidative stress through HIF-1α-NOX4-ROS axis, thereby alleviating HPH. Our findings will provide a new research direction for clinical HPH therapies.

Research Progress on Pulmonary Arterial Hypertension and the Role of the Angiotensin Converting Enzyme 2-Angiotensin-(1-7)-Mas Axis in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease with a complex aetiology and high mortality. Functional and structural changes in the small pulmonary arteries lead to elevated pulmonary arterial pressure, resulting in right heart failure. The pathobiology of PAH is not fully understood, and novel treatment targets in PAH are desperately needed. The renin-angiotensin system is critical for maintaining homeostasis of the cardiovascular system. The system consists of the angiotensin converting enzyme (ACE)-angiotensin (Ang) II-angiotensin type 1 receptor (AT₁R) axis and the ACE2-Ang-(1-7)-Mas receptor axis. The former, the ACE-Ang II-AT₁R axis, is involved in vasoconstrictive and hypertensive actions along with cardiac and vascular remodelling. The latter, the ACE2-Ang-(1-7)-Mas axis, generally mediates counterbalancing effects against those mediated by the ACE-Ang II-AT₁R axis. Based on established functions, the ACE2-Ang-(1-7)-Mas axis may represent a novel target for the treatment of PAH. This review focuses on recent advances in pulmonary circulation science and the role of the ACE2-Ang-(1-7)-Mas axis in PAH.

Alternative RAS in Various Hypoxic Conditions: From Myocardial Infarction to COVID-19

Alternative branches of the classical renin–angiotensin–aldosterone system (RAS) represent an important cascade in which angiotensin 2 (AngII) undergoes cleavage via the action of the angiotensin-converting enzyme 2 (ACE2) with subsequent production of Ang(1-7) and other related metabolites eliciting its effects via Mas receptor activation. Generally, this branch of the RAS system is described as its non-canonical alternative arm with counterbalancing actions to the classical RAS, conveying vasodilation, anti-inflammatory, anti-remodeling and anti-proliferative effects. The implication of this branch was proposed for many different diseases, ranging from acute cardiovascular conditions, through chronic respiratory diseases to cancer, nonetheless, hypoxia is one of the most prominent common factors discussed in conjugation with the changes in the activity of alternative RAS branches. The aim of this review is to bring complex insights into the mechanisms behind the various forms of hypoxic insults on the activity of alternative RAS branches based on the different duration of stimuli and causes (acute vs. intermittent vs. chronic), localization and tissue (heart vs. vessels vs. lungs) and clinical relevance of studied phenomenon (experimental vs. clinical condition). Moreover, we provide novel insights into the future strategies utilizing the alternative RAS as a diagnostic tool as well as a promising pharmacological target in serious hypoxia-associated cardiovascular and cardiopulmonary diseases.

Elabela prevents angiotensin II-induced apoptosis and inflammation in rat aortic adventitial fibroblasts via the activation of FGF21-ACE2 signaling

Apoptosis, inflammation, and fibrosis contribute to vascular remodeling and injury. Elabela (ELA) serves as a crucial regulator to maintain vascular function and has been implicated in the pathogenesis of hypertensive vascular remodeling. This study aims to explore regulatory roles and underlying mechanisms of ELA in rat aortic adventitial fibroblasts (AFs) in response to angiotensin II (ATII). In cultured AFs, exposure to ATII resulted in marked decreases in mRNA and protein levels of ELA, fibroblast growth factor 21 (FGF21), and angiotensin-converting enzyme 2 (ACE2) as well as increases in apoptosis, inflammation, oxidative stress, and cellular migration, which were partially blocked by the exogenous replenishment of ELA and recombinant FGF21, respectively. Moreover, treatment with ELA strikingly reversed ATII-mediated the loss of FGF21 and ACE2 levels in rat aortic AFs. FGF21 knockdown with small interfering RNA (siRNA) significantly counterbalanced protective effects of ELA on ATII-mediated the promotion of cell migration, apoptosis, inflammatory, and oxidative injury in rat aortic AFs. More importantly, pretreatment with recombinant FGF21 strikingly inhibited ATII-mediated the loss of ACE2 and the augmentation of cell apoptosis, oxidative stress, and inflammatory injury in rat aortic AFs, which were partially prevented by the knockdown of ACE2 with siRNA. In summary, ELA exerts its anti-apoptotic, anti-inflammatory, and anti-oxidant effects in rat aortic AFs via activation of the FGF21-ACE2 signaling. ELA may represent a potential candidate to predict vascular damage and targeting the FGF21-ACE2 signaling may be a promising therapeutic intervention for vascular adventitial remodeling and related disorders.

AT1R Regulates Macrophage Polarization Through YAP and Regulates Aortic Dissection Incidence

Aortic dissection (AD) is one of the most fatal cardiovascular emergency. At the anatomical level, AD occurs due to the formation of intimal tears. However, the molecular mechanism underlying this phenomenon remains unknown. Angiotensin II (Ang II) is a important effector in the development of cardiovascular disease that acts through binding to angiotensin type 1 receptor (AT1R). Yes-associated protein (YAP) was recently recognized as a key protein in macrophage activation. To determine whether AT1R and YAP are involved in macrophage-induced endothelial cell (EC) inflammation and AD incidence, we co-cultured THP-1 cells and HAECs in transwell chambers under different culture conditions and apply different conditions to the AD mice model. The results showed that Ang II promoted macrophage M1 polarization and adhesion, upregulated YAP phosphorylation, and induced EC injury that was related to increased levels of multiple pro-inflammatory chemokines. Blocking AT1R function pharmacologically or by transfection with AT1R siRNA can reduce the pro-inflammatory effect induced by Ang II. In addition, siRNA knock down of YAP expression further aggravated the pro-inflammatory effects of Ang II. Treatment with ARB effectively alleviated these pro-inflammatory effects. In the mice AD model, ARB effectively reduced the incidence of AD in mice, decreased M1 macrophages infiltration and AT1R content in the aortic wall and increased the tissue content of YAP. We found that AT1R induces YAP phosphorylation through binding to Ang II, and further promotes macrophage M1 polarization and adhesion to ECs. ARB reduces the incidence of AD in mice and affect macrophage polarization in mice aorta.

The role of the Hippo pathway in heart disease

Heart disease, including coronary artery disease, myocardial infarction, heart failure, cardiac hypertrophy, and cardiomyopathies, is the leading causes of death worldwide. The Hippo pathway is a central controller for organ size and tissue growth, which plays a pivotal role in determining cardiomyocytes and nonmyocytes proliferation, regeneration, differentiation, and apoptosis. In this review, we summarize the effects of the Hippo pathway on heart disease and propose potential intervention targets. Especially, we discuss the molecular mechanisms of the Hippo pathway involved in maintaining cardiac homeostasis by regulating cardiomyocytes and nonmyocytes function in the heart. Based on this, we conclude that the Hippo pathway is a promising therapeutic target for cardiovascular therapy, which will bring new perspectives for their treatments.

The alveolar epithelial cells are involved in pulmonary vascular remodeling and constriction of hypoxic pulmonary hypertension

BACKGROUND

Hypoxic pulmonary hypertension (HPH) is a common type of pulmonary hypertension and characterized by pulmonary vascular remodeling and constriction. Alveolar epithelial cells (AECs) primarily sense alveolar hypoxia, but the role of AECs in HPH remains unclear. In this study, we explored whether AECs are involved in pulmonary vascular remodeling and constriction.

METHODS

In the constructed rat HPH model, hemodynamic and morphological characteristics were measured. By treating AECs with hypoxia, we further detected the levels of superoxide dismutase 2 (SOD2), catalase (CAT), reactive oxygen species (ROS) and hydrogen peroxide (H2O2), respectively. To detect the effects of AECs on pulmonary vascular remodeling and constriction, AECs and pulmonary artery smooth cells (PASMCs) were co-cultured under hypoxia, and PASMCs and isolated pulmonary artery (PA) were treated with AECs hypoxic culture medium. In addition, to explore the mechanism of AECs on pulmonary vascular remodeling and constriction, ROS inhibitor N-acetylcysteine (NAC) was used.

RESULTS

Hypoxia caused pulmonary vascular remodeling and increased pulmonary artery pressure, but had little effect on non-pulmonary vessels in vivo. Meanwhile, in vitro, hypoxia promoted the imbalance of SOD2 and CAT in AECs, leading to increased ROS and hydrogen peroxide (H2O2) production in the AECs culture medium. In addition, AECs caused the proliferation of co-cultured PASMCs under hypoxia, and the hypoxic culture medium of AECs enhanced the constriction of isolated PA. However, treatment with ROS inhibitor NAC effectively alleviated the above effects.

CONCLUSION

The findings of present study demonstrated that AECs were involved in pulmonary vascular remodeling and constriction under hypoxia by paracrine H2O2 into the pulmonary vascular microenvironment.

Activation of AMPK inhibits Galectin-3-induced pulmonary artery smooth muscle cells proliferation by upregulating hippo signaling effector YAP

Galectin-3(Gal-3) is an effective regulator in the pathological process of pulmonary arterial hypertension (PAH). However, the detailed mechanisms underlying Gal-3 contribution to PAH are not yet entirely clear. The aim of the present study was to explore these issues. Proliferation of rat pulmonary arterial smooth muscle cells (PASMCs) was determined using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Small interfering RNA (siRNA) was applied to silence the expression of yes-associated protein (YAP) and Forkhead box M1 (FOXM1). The protein expression and phosphorylation were measured by immunoblotting. The subcellular location of YAP was determined using immunoblotting and immunofluorescence. Gal-3-stimulated PASMCs proliferation in a time- and dose-dependent manner, this was accompanied with, YAP upregulation, dephosphorylation, and nucleus translocation. Gal-3 further increased FOXM1 and cyclinD1 expression via YAP activation. Interfering YAP/FOXM1 axis suppressed Gal-3-induced PASMCs proliferation. Activation of AMPK also inhibited Gal-3-triggered cells proliferation by targeting YAP/FOXM1/cyclinD1 pathway. Gal-3 induced PASMCs proliferation by regulating YAP/FOXM1/cyclinD1 signaling cascade, and activation of AMPK targeted on this axis and suppressed Gal-3-stimulated PASMCs proliferation. Our study provides novel therapeutic targets for prevention and treatment of PAH.

Multifunctional angiotensin converting enzyme 2, the SARS-CoV-2 entry receptor, and critical appraisal of its role in acute lung injury

The recent emergence of coronavirus disease-2019 (COVID-19) as a pandemic affecting millions of individuals has raised great concern throughout the world, and the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was identified as the causative agent for COVID-19. The multifunctional protein angiotensin converting enzyme 2 (ACE2) is accepted as its primary target for entry into host cells. In its enzymatic function, ACE2, like its homologue ACE, regulates the renin-angiotensin system (RAS) critical for cardiovascular and renal homeostasis in mammals. Unlike ACE, however, ACE2 drives an alternative RAS pathway by degrading Ang-II and thus operates to balance RAS homeostasis in the context of hypertension, heart failure, and cardiovascular as well as renal complications of diabetes. Outside the RAS, ACE2 hydrolyzes key peptides, such as amyloid-β, apelin, and [des-Arg9]-bradykinin. In addition to its enzymatic functions, ACE2 is found to regulate intestinal amino acid homeostasis and the gut microbiome. Although the non-enzymatic function of ACE2 as the entry receptor for SARS-CoV-2 has been well established, the contribution of enzymatic functions of ACE2 to the pathogenesis of COVID-19-related lung injury has been a matter of debate. A complete understanding of this central enzyme may begin to explain the various symptoms and pathologies seen in SARS-CoV-2 infected individuals, and may aid in the development of novel treatments for COVID-19.

ACE2 as therapeutic agent

The angiotensin-converting enzyme 2 (ACE2) has emerged as a critical regulator of the renin-angiotensin system (RAS), which plays important roles in cardiovascular homeostasis by regulating vascular tone, fluid and electrolyte balance. ACE2 functions as a carboxymonopeptidase hydrolyzing the cleavage of a single C-terminal residue from Angiotensin-II (Ang-II), the key peptide hormone of RAS, to form Angiotensin-(1-7) (Ang-(1-7)), which binds to the G-protein-coupled Mas receptor and activates signaling pathways that counteract the pathways activated by Ang-II. ACE2 is expressed in a variety of tissues and overwhelming evidence substantiates the beneficial effects of enhancing ACE2/Ang-(1-7)/Mas axis under many pathological conditions in these tissues in experimental models. This review will provide a succinct overview on current strategies to enhance ACE2 as therapeutic agent, and discuss limitations and future challenges. ACE2 also has other functions, such as acting as a co-factor for amino acid transport and being exploited by the severe acute respiratory syndrome coronaviruses (SARS-CoVs) as cellular entry receptor, the implications of these functions in development of ACE2-based therapeutics will also be discussed.

Downregulation of Membrane-bound Angiotensin Converting Enzyme 2 (ACE2) Receptor has a Pivotal Role in COVID-19 Immunopathology

BACKGROUND

The Coronavirus Disease 2019 (COVID-19) is becoming the major health issue in recent human history with thousands of deaths and millions of cases worldwide. Newer research and old experience with other coronaviruses highlighted a probable underlying mechanism of disturbance of the renin-angiotensin system (RAS) that is associated with the intrinsic effects of SARS-CoV-2 infection.

OBJECTIVE

In this review, we aimed to describe the intimate connections between the RAS components, the immune system and COVID-19 pathophysiology.

METHODS

This non-systematic review article summarizes recent evidence on the relationship between COVID-19 and the RAS.

RESULTS

Several studies have indicated that the downregulation of membrane-bound ACE2 may exert a key role for the impairment of immune functions and for COVID-19 patients' outcomes. The downregulation may occur by distinct mechanisms, particularly: (1) the shedding process induced by the SARS-CoV-2 fusion pathway, which reduces the amount of membrane-bound ACE2, stimulating more shedding by the high levels of Angiotensin II; (2) the endocytosis of ACE2 receptor with the virus itself and (3) by the interferon inhibition caused by SARS-CoV-2 effects on the immune system, which leads to a reduction of ACE2 receptor expression.

CONCLUSION

Recent research provides evidence of a reduction of the components of the alternative RAS axis, including ACE2 and Angiotensin-(1-7). In contrast, increased levels of Angiotensin II can activate the AT1 receptor in several organs. Consequently, increased inflammation, thrombosis and angiogenesis occur in patients infected with SARS-COV-2. Attention should be paid to the interactions of the RAS and COVID-19, mainly in the context of novel vaccines and proposed medications.

Impact of sex and gender on COVID-19 outcomes in Europe

BACKGROUND

Emerging evidence from China suggests that coronavirus disease 2019 (COVID-19) is deadlier for infected men than women with a 2.8% fatality rate being reported in Chinese men versus 1.7% in women. Further, sex-disaggregated data for COVID-19 in several European countries show a similar number of cases between the sexes, but more severe outcomes in aged men. Case fatality is highest in men with pre-existing cardiovascular conditions. The mechanisms accounting for the reduced case fatality rate in women are currently unclear but may offer potential to develop novel risk stratification tools and therapeutic options for women and men.

CONTENT

The present review summarizes latest clinical and epidemiological evidence for gender and sex differences in COVID-19 from Europe and China. We discuss potential sex-specific mechanisms modulating the course of disease, such as hormone-regulated expression of genes encoding for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) entry receptors angiotensin converting enzyme (ACE) 2 receptor and TMPRSS2 as well as sex hormone-driven innate and adaptive immune responses and immunoaging. Finally, we elucidate the impact of gender-specific lifestyle, health behavior, psychological stress, and socioeconomic conditions on COVID-19 and discuss sex specific aspects of antiviral therapies.

CONCLUSION

The sex and gender disparities observed in COVID-19 vulnerability emphasize the need to better understand the impact of sex and gender on incidence and case fatality of the disease and to tailor treatment according to sex and gender. The ongoing and planned prophylactic and therapeutic treatment studies must include prospective sex- and gender-sensitive analyses.

Cancer and pulmonary hypertension: Learning lessons and real-life interplay

This article reviews the scientific reasons that support the intriguing vision of pulmonary hypertension (PH) as a disease with a cancer-like nature and to understand whether this point of view may have fruitful consequences for the overall management of PH. This review compares cancer and PH in view of Hanahan and Weinberg’s principles (i.e., hallmarks of cancer) with an emphasis on hyperproliferative, metabolic, and immune/inflammatory aspects of the disease. In addition, this review provides a perspective on the role of transcription factors and chromatin and epigenetic aberrations, besides genetics, as “common driving mechanisms” of PH hallmarks and the foreseeable use of transcription factor/epigenome targeting as multitarget approach against the hallmarks of PH. Thus, recognition of the widespread applicability and analogy of these concepts will increasingly affect the development of new means of PH treatment.

The beneficial effects of angiotensin-converting enzyme II (ACE2) activator in pulmonary hypertension secondary to left ventricular dysfunction

Pulmonary hypertension (PH) is a lethal and rapidly progressing disorder if left untreated, but there is still no definitive therapy. An imbalance between vasoconstriction and vasodilation has been proposed as the mechanism underlying PH. Among the vasomediators of the pulmonary circulation is the renin-angiotensin system (RAS), the involvement of which in the development of PH has been proposed. Within the RAS, angiotensin-converting enzyme 2 (ACE2), which converts angiotensin (Ang) II into Ang-(1-7), is an important regulator of blood pressure, and has been implicated in cardiovascular disease and PH. In this study, we investigated the effects of the ACE2 activator diminazene aceturate (DIZE) on the development of PH secondary to left ventricular dysfunction. A model of PH secondary to left ventricular dysfunction was established in 6-week-old Wistar rats by ascending aortic banding for 42 days. The hemodynamics and pulmonary expression of ACE, Ang II, ACE2, Ang-(1-7), and the Ang-(1-7) MAS receptor were investigated in the early treatment group, which was administered DIZE (15 mg/kg/day) from days 1 to 42, and in the late treatment group, administered DIZE (15 mg/kg/day) from days 29 to 42. Sham-operated rats served as controls. DIZE ameliorated mean pulmonary artery pressure, pulmonary arteriolar remodeling, and plasma brain natriuretic peptide levels, in addition to reversing the overexpression of ACE and up-regulation of both Ang-(1-7) and MAS, in the early and late treatment groups. DIZE has therapeutic potential for preventing the development of PH secondary to left ventricular dysfunction through ACEII activation and the positive feedback of ANG-(1-7) on the MAS receptor. A translational study in humans is needed to substantiate these findings.

Angiotensin type 1 receptor regulates yes-associated protein in vascular endothelial cells

Aortic dissection (AD) is one of the most lethal cardiovascular diseases. Endothelial cell (EC) dysfunction serves an important role in AD progression. Angiotensin II (Ang II) is a key effector in cardiovascular disease development that acts through binding to angiotensin type 1 receptor (AT1R). Yes-associated protein (YAP) is well-known as a key mediator of cell proliferation and apoptosis. To determine whether AT1R and YAP influence EC proliferation or injury, human aortic endothelial cells were cultured under different culture conditions. Using CCK-8 assay, ELISA, western blotting, immunocytochemistry and siRNA transfection, the present study found that Ang II activity reduced EC proliferation, upregulate YAP phosphorylation and result in EC injury that was associated with elevated levels of multiple proinflammatory chemokines. The inhibition of AT1R function, pharmaceutically or via transfection with an AT1R small interfering RNA, alleviated the effects induced by Ang II. Furthermore, AT1R induced YAP phosphorylation via binding to Ang II, and further promoted the inflammation of ECs, along with inhibiting their proliferation.