Angiotensin-converting Enzyme Protein Expression Research Articles

O-142 COVID19-free endometrium: Undetectable viral RNA in endometrial biopsies from positive symptomatic SARS-CoV-2 women

Abstract Study question Does SARS-CoV-2 infect the endometrial tissue in women with coronavirus disease 2019 (COVID-19)? Summary answer Symptomatic women with COVID-19 report no presence, in the short term, of viral RNA from SARS-CoV-2 in the endometrium. What is known already The recent emergence of COVID-19, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has not allowed yet to establish putative relations between this disorder and other existing pathologies. It is the case with fertility problems and the reproductive organs, including a possible endometrial disorder caused by the virus. Thus, an important step is to elucidate the viral presence in different human tissues to improve diagnostics, prevention and/or treatment. The hypothesis of the possible infection of the endometrial tissue comes from the described expression of ACE2 protein in the human endometrium, mainly in stromal cells during the secretory phase. Study design, size, duration 15 endometrial biopsies from symptomatic and hospitalized women with COVID-19 were collected. Endometrial samples were obtained from August to November 2020 at the Hospital Universitari i Politècnic La Fe (Valencia, Spain); the project received the approval of the hospital’s medical ethics committee (registration number: 2020-268-1). The main objective was to study by real-time PCR (RT-PCR) the presence of viral RNA from SARS-CoV-2 as well as the expression of ACE2 receptor on the endometrial tissue. Participants/materials, setting, methods 15 women in the reproductive age (24-46 years) accepted to participate in the study and signed the informed consent. All these patients tested positive for SARS-CoV-2 by RT-PCR of nasopharyngeal swabs (1-17 days before the biopsy collection) and were hospitalized due to health complications (pneumonia) derived from COVID-19. Endometrial biopsies were taken by aspiration and preserved in RNA-later until -80ºC cryopreservation in a biobank; RNA was extracted for RT-PCR for N1, N2, and ACE2 genes. Main results and the role of chance The 15 recruited patients represented the different phases of the menstrual cycle: proliferative (n = 3) and secretory (n = 10); 2 patients had amenorrhea. The viral RNA for SARS-CoV-2, measured by the detection of N1 and N2 gene targets (fragments of N gene, from the viral nucleocapsid) by RT-PCR methodology, was undetectable in all the endometrial biopsies analyzed (n = 15). In all the cases the housekeeping gene RPP30 was used as positive control and to check RNA integrity. To correlate the presence or absence of SARS-CoV-2 with the organ-specific expression of ACE2 (angiotensin-converting enzyme 2), the main postulated entry receptor of SARS-CoV-2, the endometrial RNA was also analyzed by RT-PCR for the ACE2 receptor gene. This gene was only detectable in 10 of the 15 biopsies, and the levels ranged from 28.65 to 36.19 Ct values, revealing a very low expression of ACE2 in the tissue. Moreover, ACE2 results did not report any correlation with the phase of the menstrual cycle. Limitations, reasons for caution These results imply endometrium is safe from SARS-CoV-2 infection, at least in the short term. All the endometrial samples were taken at maximum of 17 days after a positive test by RT-PCR of nasopharyngeal swabs (to note that all were hospitalized during the early stages of the disease). Wider implications of the findings In conclusion, the SARS-CoV-2 RNA is not present in the human endometrial tissue of positive patients. This hypothesis was reinforced by the low ACE2 receptor levels. However, an in-depth genetic analysis comparing to a negative control group could elucidate a systemic affectation of the endometrium, despite the negative RT-PCR results. Trial registration number not applicable

ACE2 protein expression within isogenic cell lines is heterogeneous and associated with distinct transcriptomes

The membrane protein angiotensin-converting enzyme 2 (ACE2) is a physiologic regulator of the renin-angiotensin system and the cellular receptor for the SARS-CoV-2 virus. Prior studies of ACE2 expression have primarily focused on mRNA abundance, with investigation at the protein level limited by uncertain specificity of commercial ACE2 antibodies. Here, we report our development of a sensitive and specific flow cytometry-based assay for cellular ACE2 protein abundance. Application of this approach to multiple cell lines revealed an unexpected degree of cellular heterogeneity, with detectable ACE2 protein in only a subset of cells in each isogenic population. This heterogeneity was mediated at the mRNA level by transcripts predominantly initiated from the ACE2 proximal promoter. ACE2 expression was heritable but not fixed over multiple generations of daughter cells, with gradual drift toward the original heterogeneous background. RNA-seq profiling identified distinct transcriptomes of ACE2-expressing relative cells to non-expressing cells, with enrichment in functionally related genes and transcription factor target sets. Our findings provide a validated approach for the specific detection of ACE2 protein at the surface of single cells, support an epigenetic mechanism of ACE2 gene regulation, and identify specific pathways associated with ACE2 expression in HuH7 cells.

Intersubject Variation in ACE2 Protein Expression in Human Airway Epithelia and Its Relationship to Severe Acute Respiratory Syndrome Coronavirus 2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 ) initiates entry into airway epithelia by binding its receptor, angiotensin-converting enzyme 2 (ACE2). To explore whether interindividual variation in ACE2 abundance contributes to variability in coronavirus disease 2019 (COVID-19) outcomes, we measured ACE2 protein abundance in primary airway epithelial cultures derived from 58 human donor lungs. We found no evidence for sex- or age-dependent differences in ACE2 protein expression. Furthermore, we found that variations in ACE2 abundance had minimal effects on viral replication and induction of the interferon response in airway epithelia infected with SARS-CoV-2. Our results highlight the relative importance of additional host factors, beyond viral receptor expression, in determining COVID-19 lung disease outcomes.

Food Enrichment with Glycyrrhiza glabra Extract Suppresses ACE2 mRNA and Protein Expression in Rats-Possible Implications for COVID-19.

Angiotensin converting enzyme 2 (ACE2) is a key entry point of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus known to induce Coronavirus disease 2019 (COVID-19). We have recently outlined a concept to reduce ACE2 expression by the administration of glycyrrhizin, a component of Glycyrrhiza glabra extract, via its inhibitory activity on 11beta hydroxysteroid dehydrogenase type 2 (11betaHSD2) and resulting activation of mineralocorticoid receptor (MR). We hypothesized that in organs such as the ileum, which co-express 11betaHSD2, MR and ACE2, the expression of ACE2 would be suppressed. We studied organ tissues from an experiment originally designed to address the effects of Glycyrrhiza glabra extract on stress response. Male Sprague Dawley rats were left undisturbed or exposed to chronic mild stress for five weeks. For the last two weeks, animals continued with a placebo diet or received a diet containing extract of Glycyrrhiza glabra root at a dose of 150 mg/kg of body weight/day. Quantitative PCR measurements showed a significant decrease in gene expression of ACE2 in the small intestine of rats fed with diet containing Glycyrrhiza glabra extract. This effect was independent of the stress condition and failed to be observed in non-target tissues, namely the heart and the brain cortex. In the small intestine we also confirmed the reduction of ACE2 at the protein level. Present findings provide evidence to support the hypothesis that Glycyrrhiza glabra extract may reduce an entry point of SARS-CoV-2. Whether this phenomenon, when confirmed in additional studies, is linked to the susceptibility of cells to the virus requires further studies.

Expression of ACE2 in the Intact and Acutely Injured Kidney.

The actions of angiotensin-converting enzyme 2 (ACE2) oppose those of the renin-angiotensin-aldosterone system. ACE2 may be a cytoprotectant in some tissues. This study examined ACE2 expression in models of AKI. ACE2 mRNA and protein expression and ACE2 activity were assessed in murine ischemic AKI. Renal ACE2 mRNA expression was evaluated in LPS-induced AKI in wild-type (C57BL/6J) mice, in heme oxygenase-1+/+ and heme oxygenase-1-/- mice, and after unilateral ureteral obstruction (UUO) in wild-type mice. The effect of sex and age on renal ACE2 protein expression was also assessed. In ischemic AKI, ACE2 mRNA and protein expression and ACE2 activity were reduced as compared with such indices in the intact kidney. In ischemic AKI, ACE2, which, in health, is prominently expressed in the tubular epithelium, especially proximal tubules, is decreased in expression in these segments. Decreased ACE2 expression in AKI did not reflect reduced GFR, because ACE2 mRNA expression was unaltered after UUO. LPS induced renal ACE2 mRNA expression in wild-type mice, but this effect did not occur in heme oxygenase-1-deficient mice. In ischemic and LPS-induced AKI, renal expression of the Mas receptor was increased. In the intact kidney, renal ACE2 protein expression decreased in female mice as compared with male mice, but was unaltered with age. We conclude that renal ACE2 expression is decreased in ischemic AKI, characterized by decreased GFR and abundant cell death, but is upregulated in LPS-induced AKI, an effect requiring heme oxygenase-1. Determining the significance of ACE2 expression in experimental AKI merits further study. We suggest that understanding the mechanism underlying ACE2 downregulation in AKI may offer insights relevant to COVID-19: ACE2 expression is downregulated after ACE2 mediates SARS-CoV-2 cellular entry; such downregulation is proinflammatory; and AKI commonly occurs and determines outcomes in COVID-19.

Increased colonic expression of ACE2 associates with poor prognosis in Crohn\u2019s disease

The host receptor for SARS-CoV-2, angiotensin-converting enzyme 2 (ACE2), is highly expressed in small intestine. Our aim was to study colonic ACE2 expression in Crohn's disease (CD) and non-inflammatory bowel disease (non-IBD) controls. We hypothesized that the colonic expression levels of ACE2 impacts CD course. We examined the expression of colonic ACE2 in 67 adult CD and 14 NIBD control patients using RNA-seq and quantitative (q) RT-PCR. We validated ACE2 protein expression and localization in formalin-fixed, paraffin-embedded matched colon and ileal tissues using immunohistochemistry. The impact of increased ACE2 expression in CD for the risk of surgery was evaluated by a multivariate regression analysis and a Kaplan–Meier estimator. To provide critical support for the generality of our findings, we analyzed previously published RNA-seq data from two large independent cohorts of CD patients. Colonic ACE2 expression was significantly higher in a subset of adult CD patients which was defined as the ACE2-high CD subset. IHC in a sampling of ACE2-high CD patients confirmed high ACE2 protein expression in the colon and ileum compared to ACE2-low CD and NIBD patients. Notably, we found that ACE2-high CD patients are significantly more likely to undergo surgery within 5 years of CD diagnosis, and a Cox regression analysis found that high ACE2 levels is an independent risk factor for surgery (OR 2.17; 95% CI, 1.10–4.26; p = 0.025). Increased intestinal expression of ACE2 is associated with deteriorated clinical outcomes in CD patients. These data point to the need for molecular stratification that can impact CD disease-related outcomes.

SARS-CoV-2 Host Receptor ACE2 Protein Expression Atlas in Human Gastrointestinal Tract.

BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects host cells through interactions with its receptor, Angiotensin-converting enzyme 2 (ACE2), causing severe acute respiratory syndrome and death in a considerable proportion of people. Patients infected with SARS-CoV-2 experience digestive symptoms. However, the precise protein expression atlas of ACE2 in the gastrointestinal tract remains unclear. In this study, we aimed to explore the ACE2 protein expression pattern and the underlying function of ACE2 in the gastrointestinal tract, including the colon, stomach, liver, and pancreas.MethodsWe measured the protein expression of ACE2 in the gastrointestinal tract using immunohistochemical (IHC) staining with an ACE2-specific antibody of paraffin-embedded colon, stomach, liver, and pancreatic tissues. The correlation between the protein expression of ACE2 and the prognosis of patients with gastrointestinal cancers was analyzed by the log-rank (Mantel–Cox) test. The influence of ACE2 on colon, stomach, liver, and pancreatic tumor cell line proliferation was tested using a Cell Counting Kit 8 (CCK-8) assay.ResultsACE2 presented heterogeneous expression patterns in the gastrointestinal tract, and it showed a punctate distribution in hepatic cells. Compared to that in parallel adjacent non-tumor tissues, the protein expression of ACE2 was significantly increased in colon cancer, stomach cancer, and pancreatic cancer tissues but dramatically decreased in liver cancer tissues. However, the expression level of the ACE2 protein was not correlated with the survival of patients with gastrointestinal cancers. Consistently, ACE2 did not affect the proliferation of gastrointestinal cancer cells in vitro.ConclusionThe ACE2 protein is widely expressed in the gastrointestinal tract, and its expression is significantly altered in gastrointestinal tumor tissues. ACE2 is not an independent prognostic marker of gastrointestinal cancers.

Human cell receptors: potential drug targets to combat COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the coronavirus disease 2019 (COVID-19). The World Health Organization (WHO) has announced that COVID-19 is a pandemic having a higher spread rate rather than the mortality. Identification of a potential approach or therapy against COVID-19 is still under consideration. Therefore, it is essential to have an insight into SARS-CoV-2, its interacting partner, and domains for an effective treatment. The present study is divided into three main categories, including SARS-CoV-2 prominent receptor and its expression levels, other interacting partners, and their binding domains. The first section focuses primarily on coronaviruses' general aspects (SARS-CoV-2, SARS-CoV, and the Middle East Respiratory Syndrome Coronaviruses (MERS-CoV)) their structures, similarities, and mode of infections. The second section discusses the host receptors which includes the human targets of coronaviruses like dipeptidyl peptidase 4 (DPP4), CD147, CD209L, Angiotensin-Converting Enzyme 2 (ACE2), and other miscellaneous targets (type-II transmembrane serine proteases (TTSPs), furin, trypsin, cathepsins, thermolysin, elastase, phosphatidylinositol 3-phosphate 5-kinase, two-pore segment channel, and epithelium sodium channel C-α subunit). The human cell receptor, ACE2 plays an essential role in the Renin-Angiotensin system (RAS) pathway and COVID-19. Thus, this section also discusses the ACE2 expression and risk of COVID-19 infectivity in various organs and tissues such as the liver, lungs, intestine, heart, and reproductive system in the human body. Absence of ACE2 protein expression in immune cells could be used for limiting the SARS-CoV-2 infection. The third section covers the current available approaches for COVID-19 treatment. Overall, this review focuses on the critical role of human cell receptors involved in coronavirus pathogenesis, which would likely be used in designing target-specific drugs to combat COVID-19.

High‐Fat High‐Sucrose Diet Increases ACE2 Receptor Expression in Lung and Pancreatic Islets in SIV‐Infected Rhesus Macaques: Implications for Increased Risk for SARS‐CoV‐2 Infection

People with pre‐existing conditions including obesity, diabetes, and kidney disease are at greater risk for complications of COVID‐19, the disease caused by SARS‐CoV‐2 infection. Predisposing risk factors could include poor dietary quality and at‐risk alcohol use. Increased survival and aging of people living with HIV (PLWH) on antiretroviral therapy (ART) is complicated by comorbidities including at‐risk alcohol use, metabolic dysregulation, diabetes, and chronic renal disease, with obesity and metabolic syndrome highest in southern states. We hypothesize that poor dietary quality in combination with at‐risk alcohol use may increase risk factors for SARS‐CoV‐2 infection in PLWH. To test this hypothesis, biospecimen obtained from a longitudinal study in female rhesus macaques (macaca mulatta) were used to determine whether high‐fat high‐sucrose diet (HFD; protein/fat/carbohydrates 16/42/42% of total kcal and 27% sucrose by weight) and chronic binge alcohol administration (CBA) increased expression of the machinery required for SARS‐CoV‐2 cell entry. Female macaques (n=10) were assigned to HFD or standard chow diet (SD; protein/fat/carbohydrates 29/14/57% of total kcal) and CBA (50‐60 mM peak blood alcohol, 5 days/week) or isovolumetric water (VEH) beginning 3 months before SIVmac251 infection. ART was initiated at 2.5 months of SIV infection. Tissue samples including lung, pancreas, and kidney were collected at study endpoint (~12 months post‐SIV infection). Immunohistochemistry was performed on formalin‐fixed, paraffin embedded samples to determine protein expression of angiotensin converting enzyme 2 (ACE2) receptor and transmembrane serine protease 2 (TMPRSS2). Images were obtained at 20x magnification and fluorescence intensity was used for quantification. RNA was extracted from frozen samples and mRNA expression of ACE2 and TMPRSS2 was measured by qPCR and quantified relative to ribosomal protein S13. Normality of data was verified and outliers identified using Grubbs test. Data were then analyzed using a 2 (alcohol) × 2 (diet) ANOVA. Protein expression of ACE2 in the lung (p<0.01, η2=0.59), whole pancreas (p<0.05, η2=0.64), and pancreatic islets (p<0.05, η2=0.44) was greater in HFD‐ than SD‐fed macaques and was not significantly altered by CBA. No alcohol‐ or diet‐mediated differences in ACE2 protein expression were observed for whole kidney or proximal tubules. No alcohol‐ or diet‐mediated differences in protein expression of TMPRSS2 or relative mRNA expression of ACE2 or TMPRSS2 were observed. Results indicate that a high‐fat, high‐sucrose diet increases expression of the ACE2 receptor in SIV‐infected female macaques. Because the ACE2 receptor is required for SARS‐CoV‐2 cell entry, this diet‐mediated increase in expression may increase risk for greater vulnerability to COVID‐19 disease and associated complications. These data provide direct evidence for a link between dietary quality and risk for SARS‐CoV‐2 infection in the context of SIV/HIV infection, urging diet counseling and increased access to higher‐quality foods in this population.

The Impact of Angiotensin Converting Enzyme Inhibition and/or Angiotensin Receptor Blockade on Tissue Expression of the SARS‐CoV‐2 Receptor ACE2 in Mice

The angiotensin‐converting enzyme 2 (ACE2) is an established receptor and entry point for the novel SARS‐CoV‐2 coronavirus, as the spike protein on the viral envelope binds the ACE2 receptor. Published histological profiling revealed ACE2 to be highly expressed on human lung alveolar epithelial cells and on enterocytes of the small intestine, as well as on arterial and venous endothelial cells. Given the widespread abundance of ACE2 across tissues, there has been much speculation regarding whether ACE inhibitors (ACEi) and/or Angiotensin Receptor Blockers (ARB) might alter tissue ACE2 expression and thereby change the risk of transmission or development of severe complications. Therefore, the aim of this ongoing study is to measure the impact of ACEi and ARB singly and in combination versus placebo control on tissue distribution of ACE2 in male and female mice.A factorial design was employed with the following exposures: ACEi (lisinopril, 10 mg/kg/day), ARB (losartan, 10 mg/kg/day), both drugs, or water control. Drugs were delivered via drinking water. C57BL/6J Mice were 8 weeks of age at the start of the experiment. After 21 days of treatment, four mice (two males and two females) from each treatment group were euthanized, followed by perfusion and tissue collection. 12 more untreated mice were combined with the placebo group to increase the sample size of this reference group to 16 (8 males, 8 females). ACE2 protein abundance in brain, kidney, liver, lung, and small intestine was measured by ELISA (Abcam) and normalized to BCA‐measured total protein. Two‐way ANOVA was performed to test for differences in ACE2 levels by organ or sex among untreated mice; Mann‐Whitney tests were performed to compare each drug treatment group to the control group.Among untreated mice, ACE2 levels differed by organ (p < 0.01), but there were no differences between males and females for a given organ (p = 0.20). Males and females were combined for subsequent analyses. After 21 days of treatment, ACEi, ARB, and the combination therapy lowered ACE2 tissue abundance compared to untreated mice in the brain (ACEi p = 0.04; ARB p = 0.04; ACEi+ARB p = 0.01), kidney (ACEi p = 0.03; ARB p = 0.02; ACEi+ARB p = 0.02), and lung (ACEi p = 0.01; ARB p = 0.01; ACEi+ARB p = 0.01). ACEi, but not ARB or combination therapy, lowered ACE2 tissue abundance in the liver (p = 0.02). None of the treatments changed ACE2 tissue abundance in the small intestine.These results indicate that ACEi, ARB, or combination therapy reduces levels of ACE2, the SARS‐CoV‐2 receptor, in key tissues affected by the virus, including lung, kidney, and brain. An ongoing validation study will evaluate ACE2 protein and gene expression at earlier time points, as well as after discontinuation of treatment. These results will provide valuable insight into the risk or potential benefit of starting or stopping ACEi, ARB, or combination therapy during the COVID‐19 pandemic.

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.

Expression of the SARS-CoV-2 receptorACE2 in human heart is associated with uncontrolled diabetes, obesity, and activation of the renin angiotensin system

BackgroundDiabetic and obese patients are at higher risk of severe disease and cardiac injury in corona virus 2 (SARS-CoV-2) infections. Cellular entry of SARS-CoV-2 is mainly via the angiotensin-converting enzyme 2 (ACE2) receptor, which is highly expressed in normal hearts. There is a disagreement regarding the effect of factors such as obesity and diabetes on ACE2 expression in the human heart and whether treatment with renin–angiotensin system inhibitors or anti-diabetic medications increases ACE2 expression and subsequently the susceptibility to infection. We designed this study to elucidate factors that control ACE2 expression in human serum, human heart biopsies, and mice.MethodsRight atrial appendage biopsies were collected from 79 patients that underwent coronary artery bypass graft (CABG) surgery. We investigated the alteration in ACE2 mRNA and protein expression in heart tissue and serum. ACE2 expression was compared with clinical risk factors: diabetes, obesity and different anti-hypertensive or anti-diabetic therapies. WT or db/db mice were infused with Angiotensin II (ATII), treated with different anti-diabetic drugs (Metformin, GLP1A and SGLT2i) were also tested.ResultsACE2 gene expression was increased in diabetic hearts compared to non-diabetic hearts and was positively correlated with glycosylated hemoglobin (HbA1c), body mass index (BMI), and activation of the renin angiotensin system (RAS), and negatively correlated with ejection fraction. ACE2 was not differentially expressed in patients who were on angiotensin converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARBs) prior to the operation. We found no correlation between plasma free ACE2 and cardiac tissue ACE2 expression. Transmembrane serine protease 2 (TMPRSS2), metalloprotease ADAM10 and ADAM17 that facilitate viral-ACE2 complex entry and degradation were increased in diabetic hearts. ACE2 expression in mice was increased with ATII infusion and attenuated following anti-diabetic drugs treatment.ConclusionPatients with uncontrolled diabetes or obesity with RAS activation have higher ACE2 expressions therefore are at higher risk for severe infection. Since ACEi or ARBs show no effect on ACE2 expression in the heart further support their safety.

Electronic Cigarette Aerosol Is Cytotoxic and Increases ACE2 Expression on Human Airway Epithelial Cells: Implications for SARS-CoV-2 (COVID-19).

Tobacco smoking has emerged as a risk factor for increasing the susceptibility to infection from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) via increased expression of angiotensin-converting enzyme-2 (ACE2) in the lung, linked to coronavirus disease 2019 (COVID-19) development. Given the modifiable nature of electronic cigarettes and the delivery of high concentrations of nicotine, we investigate whether electronic cigarette vaping has the potential to increase susceptibility to SARS-CoV-2 infection. We exposed BEAS-2B cells (bronchial epithelium transformed with Ad12-SV40 2B) and primary small airway epithelial cells (SAECs) to electronic cigarette aerosol condensates produced from propylene glycol/vegetable glycerin or commercially bought e-liquid (±added nicotine) and cigarette smoke extract to investigate if electronic cigarette exposure, like cigarette smoke, increases the expression of ACE2 in lung epithelial cells. In BEAS-2B cells, cytotoxicity (CCK-8), membrane integrity (LDH), and ACE2 protein expression (immunofluorescence) were measured for both 4- and 24 h treatments in BEAS-2B cells and 4 h in SAECs; ACE2 gene expression was measured using quantitative polymerase chain reaction (qPCR) for 4 h treatment in BEAS-2B cells. Nicotine-free condensates and higher concentrations of nicotine-containing condensates were cytotoxic to BEAS-2B cells. Higher LDH release and reduced membrane integrity were seen in BEAS-2B cells treated for 24 h with higher concentrations of nicotine-containing condensates. ACE2 protein expression was observably increased in all treatments compared to cell controls, particularly for 24 h exposures. ACE2 gene expression was significantly increased in cells exposed to the locally bought e-liquid condensate with high nicotine concentration and cigarette smoke extract compared with cell controls. Our study suggests that vaping alone and smoking alone can result in an increase in lung ACE2 expression. Vaping and smoking are avoidable risk factors for COVID-19, which, if avoided, could help reduce the number of COVID-19 cases and the severity of the disease. This is the first study to utilize electronic cigarette aerosol condensates, novel and developed in our laboratory, for investigating ACE2 expression in human airway epithelial cells.

Acidic preconditioning reduces lipopolysaccharide-induced acute lung injury by upregulating the expression of angiotensin-converting enzyme 2.

Acid preconditioning (APC) through carbon dioxide inhalation can exert protective effects during acute lung injury (ALI) triggered by ischemia-reperfusion. Angiotensin-converting enzyme 2 (ACE2) has been identified as a receptor for severe acute respiratory syndrome coronavirus and the novel coronavirus disease-19. Downregulation of ACE2 plays an important role in the pathogenesis of severe lung failure after viral or bacterial infections. The aim of the present study was to examine the anti-inflammatory mechanism through which APC alleviates lipopolysaccharide (LPS)-induced ALI in vivo and in vitro. The present results demonstrated that LPS significantly downregulated the expression of ACE2, while APC significantly reduced LPS-induced ALI and provided beneficial effects. In addition, bioinformatics analysis indicated that microRNA (miR)-200c-3p directly targeted the 3'untranslated region of ACE2 and regulated the expression of ACE2 protein. LPS exposure inhibited the expression of ACE2 protein in A549 cells by upregulating the levels of miR-200c-3p. However, APC inhibited the upregulation of miR-200c-3p induced by LPS, as well as the downregulation of ACE2 protein, through the NF-κB pathway. In conclusion, although LPS can inhibit the expression of ACE2 by upregulating the levels of miR-200c-3p through the NF-κB pathway, APC inhibited this effect, thus reducing inflammation during LPS-induced ALI.

Comparative analysis of ACE2 protein expression in rodent, non-human primate, and human respiratory tract at baseline and after injury: A conundrum for COVID-19 pathogenesis.

Angiotensin converting enzyme 2 (ACE2) is the putative functional receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Current literature on the abundance and distribution of ACE2 protein in the human respiratory tract is controversial. We examined the effect of age and lung injury on ACE2 protein expression in rodent and non-human primate (NHP) models. We also examined ACE2 expression in human tissues with and without coronavirus disease 19 (COVID-19). ACE2 expression was detected at very low levels in preterm, but was absent in full-term and adult NHP lung homogenates. This pattern of ACE2 expression contrasted with that of transmembrane protease serine type 2 (TMPRSS2), which was significantly increased in full-term newborn and adult NHP lungs compared to preterm NHP lungs. ACE2 expression was not detected in NHP lungs with cigarette smoke-induced airway disease or bronchopulmonary dysplasia. Murine lungs lacked basal ACE2 immunoreactivity, but responded to hyperoxia, bacterial infection, and allergen exposure with new ACE2 expression in bronchial epithelial cells. In human specimens, robust ACE2 immunoreactivity was detected in ciliated epithelial cells in paranasal sinus specimens, while ACE2 expression was detected only in rare type 2 alveolar epithelial cells in control lungs. In autopsy specimens from patients with COVID-19 pneumonia, ACE2 was detected in rare ciliated epithelial and endothelial cells in the trachea, but not in the lung. There was robust expression of ACE2 expression in F344/N rat nasal mucosa and lung specimens, which authentically recapitulated the ACE2 expression pattern in human paranasal sinus specimens. Thus, ACE2 protein expression demonstrates a significant gradient between upper and lower respiratory tract in humans and is scarce in the lung. This pattern of ACE2 expression supports the notion of sinonasal epithelium being the main entry site for SARS-CoV-2 but raises further questions on the pathogenesis and cellular targets of SARS-CoV-2 in COVID-19 pneumonia.

Revealing Tissue-Specific SARS-CoV-2 Infection and Host Responses using Human Stem Cell-Derived Lung and Cerebral Organoids.

SummaryCOVID-19 is a transmissible respiratory disease caused by a novel coronavirus, SARS-CoV-2, and has become a global health emergency. There is an urgent need for robust and practical in vitro model systems to investigate viral pathogenesis. Here, we generated human induced pluripotent stem cell (iPSC)-derived lung organoids (LORGs), cerebral organoids (CORGs), neural progenitor cells (NPCs), neurons, and astrocytes. LORGs containing epithelial cells, alveolar types 1 and 2, highly express ACE2 and TMPRSS2 and are permissive to SARS-CoV-2 infection. SARS-CoV-2 infection induces interferons, cytokines, and chemokines and activates critical inflammasome pathway genes. Spike protein inhibitor, EK1 peptide, and TMPRSS2 inhibitors (camostat/nafamostat) block viral entry in LORGs. Conversely, CORGs, NPCs, astrocytes, and neurons express low levels of ACE2 and TMPRSS2 and correspondingly are not highly permissive to SARS-CoV-2 infection. Infection in neuronal cells activates TLR3/7, OAS2, complement system, and apoptotic genes. These findings will aid in understanding COVID-19 pathogenesis and facilitate drug discovery.

Protein Expression of Angiotensin-Converting Enzyme 2 (ACE2) is Upregulated in Brains with Alzheimer's Disease.

Alzheimer’s disease is a chronic neurodegenerative disorder and represents the main cause of dementia globally. Currently, the world is suffering from the coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a virus that uses angiotensin-converting enzyme 2 (ACE2) as a receptor to enter the host cells. In COVID-19, neurological manifestations have been reported to occur. The present study demonstrates that the protein expression level of ACE2 is upregulated in the brain of patients with Alzheimer’s disease. The increased ACE2 expression is not age-dependent, suggesting the direct relationship between Alzheimer’s disease and ACE2 expression. Oxidative stress has been implicated in the pathogenesis of Alzheimer’s disease, and brains with the disease examined in this study also exhibited higher carbonylated proteins, as well as an increased thiol oxidation state of peroxiredoxin 6 (Prx6). A moderate positive correlation was found between the increased ACE2 protein expression and oxidative stress in brains with Alzheimer’s disease. In summary, the present study reveals the relationships between Alzheimer’s disease and ACE2, the receptor for SARS-CoV-2. These results suggest the importance of carefully monitoring patients with both Alzheimer’s disease and COVID-19 in order to identify higher viral loads in the brain and long-term adverse neurological consequences.

Protein expression of angiotensin-converting enzyme 2, a SARS-CoV-2-specific receptor, in fetal and placental tissues throughout gestation: new insight for perinatal counseling.

ABSTRACTObjectivePregnant women can be infected by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), yet the incidence of perinatal infection is low. We hypothesized that this could be related to low expression of the membrane receptor for SARS‐CoV‐2, angiotensin‐converting enzyme 2 (ACE2), in the fetoplacental unit. We evaluated protein expression of ACE2 at various gestational ages in both placentae and fetal organs from pregnancies not infected with SARS‐CoV‐2.MethodsIn May 2020, using samples from a registered biobank, we performed immunohistochemical analysis for ACE2 in tissue samples from fetal organs and placentae from five cases of second‐ or third‐trimester medical termination of pregnancy in healthy women (performed between 15 and 38 weeks' gestation), as well as a further two placentae, one from a 7‐week spontaneous miscarriage in a non‐infected woman and one from a symptomatic pregnant woman positive for SARS‐CoV‐2 delivered by Cesarean section at 34 weeks. Samples were paraffin‐embedded and organ tissues included kidney, brain, lung, intestinal tract, heart and testis. Matching tissues (kidney, intestinal tract, lung and testis) from autopsies of four 8‐year‐old children were tested as controls. Tissue sections were incubated with rabbit monoclonal anti‐ACE2, and protein expression of ACE2 was detected by immunohistochemistry.ResultsACE2 expression was detected in fetal kidney, rectum and ileum samples from 15 weeks onwards and in the pediatric controls. It was barely detectable in fetal lung samples at 15 + 5 weeks' gestation and not detectable thereafter, and, in the pediatric controls, ACE2 was detectable only in type‐2 pneumocytes. No ACE2 expression was found in the cerebral ependymal or parenchymal tissues or in cardiac tissues. ACE2 was expressed in placental syncytiotrophoblast and cytotrophoblast samples, but not in the amnion, from 7 weeks onwards. The intensity and distribution of ACE2 staining in the placenta from the symptomatic SARS‐CoV‐2 woman was similar to that in the non‐infected placentae.ConclusionsMarked placental expression of ACE2 provides a rationale for vertical transmission at the cellular level. Absence of ACE2 expression in the fetal brain and heart is reassuring regarding the risk of congenital malformation. Clinical follow‐up of infected pregnant women and their children is needed to validate these observations. © 2020 International Society of Ultrasound in Obstetrics and Gynecology

Expression of Endogenous Angiotensin-Converting Enzyme 2 in Human Induced Pluripotent Stem Cell-Derived Retinal Organoids.

Angiotensin-converting enzyme 2 (ACE2) was identified as the main host cell receptor for the entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its subsequent infection. In some coronavirus disease 2019 (COVID-19) patients, it has been reported that the nervous tissues and the eyes were also affected. However, evidence supporting that the retina is a target tissue for SARS-CoV-2 infection is still lacking. This present study aimed to investigate whether ACE2 expression plays a role in human retinal neurons during SARS-CoV-2 infection. Human induced pluripotent stem cell (hiPSC)-derived retinal organoids and monolayer cultures derived from dissociated retinal organoids were generated. To validate the potential entry of SARS-CoV-2 infection in the retina, we showed that hiPSC-derived retinal organoids and monolayer cultures endogenously express ACE2 and transmembrane serine protease 2 (TMPRSS2) on the mRNA level. Immunofluorescence staining confirmed the protein expression of ACE2 and TMPRSS2 in retinal organoids and monolayer cultures. Furthermore, using the SARS-CoV-2 pseudovirus spike protein with GFP expression system, we found that retinal organoids and monolayer cultures can potentially be infected by the SARS-CoV-2 pseudovirus. Collectively, our findings highlighted the potential of iPSC-derived retinal organoids as the models for ACE2 receptor-based SARS-CoV-2 infection.

ACE2 gene transfer ameliorates vasoreparative dysfunction in CD34+ cells derived from diabetic older adults.

Diabetes increases the risk for ischemic vascular diseases, which is further elevated in older adults. Bone marrow-derived hematopoietic CD34+ stem/progenitor cells have the potential of revascularization; however, diabetes attenuates vasoreparative functions. Angiotensin-converting enzyme 2 (ACE2) is the vasoprotective enzyme of renin–angiotensin system in contrast with the canonical angiotensin-converting enzyme (ACE). The present study tested the hypothesis that diabetic dysfunction is associated with ACE2/ACE imbalance in hematopoietic stem/progenitor cells (HSPCs) and that increasing ACE2 expression would restore reparative functions. Blood samples from male and female diabetic (n=71) or nondiabetic (n=62) individuals were obtained and CD34+ cells were enumerated by flow cytometry. ACE and ACE2 enzyme activities were determined in cell lysates. Lentiviral (LV) approach was used to increase the expression of soluble ACE2 protein. Cells from diabetic older adults (DB) or nondiabetic individuals (Control) were evaluated for their ability to stimulate revascularization in a mouse model of hindlimb ischemia (HLI). DB cells attenuated the recovery of blood flow to ischemic areas in nondiabetic mice compared with that observed with Control cells. Administration of DB cells modified with LV-ACE2 resulted in complete restoration of blood flow. HLI in diabetic mice resulted in poor recovery with amputations, which was not reversed by either Control or DB cells. LV-ACE2 modification of Control or DB cells resulted in blood flow recovery in diabetic mice. In vitro treatment with Ang-(1-7) modified paracrine profile in diabetic CD34+ cells. The present study suggests that vasoreparative dysfunction in CD34+ cells from diabetic older adults is associated with ACE2/ACE imbalance and that increased ACE2 expression enhances the revascularization potential.