Pericytes may facilitate SARS-CoV-2 entry into the nervous system

Objective: Although the neurological and olfactory symptoms of coronavirus disease 2019 have been identified, the neurotropic properties of the causative virus, severe acute respiratory syndrome-associated coronavirus 2 (SARS-CoV-2), remain unknown. We sought to identify the susceptible cell types and potential routes of SARS-CoV-2 entry into the central nervous system, olfactory system, and respiratory system. Method(s): We collected single-cell RNA data from normal brain and nasal epithelium specimens, along with bronchial, tracheal, and lung specimens in public datasets. The susceptible cell types that express SARS-CoV-2 entry genes were identified using single-cell RNA sequencing and the expression of the key genes at protein levels was verified by immunohistochemistry. We compared the coexpression patterns of the entry receptor angiotensin-converting enzyme 2 (ACE2) and the spike protein priming enzyme transmembrane serine protease (TMPRSS)/cathepsin L among the specimens. Result(s): The SARS-CoV-2 entry receptor ACE2 and the spike protein priming enzyme TMPRSS/cathepsin L were coexpressed by pericytes in brain tissue;this coexpression was confirmed by immunohistochemistry. In the nasal epithelium, ciliated cells and sustentacular cells exhibited strong coexpression of ACE2 and TMPRSS. Neurons and glia in the brain and nasal epithelium did not exhibit coexpression of ACE2 and TMPRSS. However, coexpression was present in ciliated cells, vascular smooth muscle cells, and fibroblasts in tracheal tissue;ciliated cells and goblet cells in bronchial tissue;and alveolar epithelium type 1 cells, AT2 cells, and ciliated cells in lung tissue. Conclusion(s): Neurological symptoms in patients with coronavirus disease 2019 could be associated with SARS-CoV-2 invasion across the blood-brain barrier via pericytes. Additionally, SARS-CoV-2-induced olfactory disorders could be the result of localized cell damage in the nasal epithelium.Copyright © Wolters Kluwer Health, Inc. All rights reserved.

Esophageal Mucosal Calcinosis: A Rare Site of Calcium Deposition in End-Stage Renal Disease

Introduction: Calciphylaxis, otherwise known as calcium uremic arteriolopathy, is defined as calcium deposition around blood vessels in skin and fat tissue which occurs in 1-4% of patients with end-stage renal disease (ESRD). Calcium deposition in the esophagus is extremely rare;to date, there have been only 4 cases reported worldwide. We report the fifth case of esophageal mucosal calcinosis occurring in a young male with ESRD. Case Description/Methods: A 37-year-old Thai man with ESRD on peritoneal dialysis since 2005 presented with generalized weakness and odynophagia due to oral ulcers, resulting in poor PO intake. He denied drinking alcohol, illicit drug use, or smoking. On exam his abdomen was soft, non-distended, non-tender, without any guarding. Past medical history included hypertension and COVID-19 in January 2022. Laboratory tests revealed neutropenia and pancytopenia, hyperphosphatemia, and hypocalcemia. EGD revealed distal esophageal esophagitis and hemorrhagic erosive gastropathy. Biopsy showed ulcerative esophagitis with dystrophic calcification, consistent with esophageal mucosal calcinosis .No intestinal metaplasia was noted. Immunohistochemistry was negative for CMV, HSV1, and HSV2. The patient was treated with pantoprazole 40mg IV every 12 hours, Magic Mouthwash 5ml qid, and Carafate 10mg qid. He was transferred to a cancer center where he had a bone marrow biopsy formed which was negative. His symptoms resolved and the patient was discharged to home (Figure). Discussion(s): Esophageal mucosal calcinosis is extremely rare. It is due to a combination of factors involving acidosis and the phenotypic differentiation (and apoptosis) of vascular smooth muscle cells (VSMC) into chondrocytes or osteoblast-like cells. These changes, along with the passive accumulation of calcium and phosphate, induce calcification. Acidosis is well-known to promote inflammation of the arterial walls, releasing cytokines that induce vascular calcification. The benefits of treatment with sodium thiosulfate remain unclear. An ample collection of cases should help devise standardized treatment options and establish management guidelines for this condition.

An Unexpected Enzyme in Vascular Smooth Muscle Cells: Angiotensin II Upregulates Cholesterol-25-Hydroxylase Gene Expression.

Angiotensin II (AngII) is a vasoactive peptide hormone, which, under pathological conditions, contributes to the development of cardiovascular diseases. Oxysterols, including 25-hydroxycholesterol (25-HC), the product of cholesterol-25-hydroxylase (CH25H), also have detrimental effects on vascular health by affecting vascular smooth muscle cells (VSMCs). We investigated AngII-induced gene expression changes in VSMCs to explore whether AngII stimulus and 25-HC production have a connection in the vasculature. RNA-sequencing revealed that Ch25h is significantly upregulated in response to AngII stimulus. The Ch25h mRNA levels were elevated robustly (~50-fold) 1 h after AngII (100 nM) stimulation compared to baseline levels. Using inhibitors, we specified that the AngII-induced Ch25h upregulation is type 1 angiotensin II receptor- and Gq/11 activity-dependent. Furthermore, p38 MAPK has a crucial role in the upregulation of Ch25h. We performed LC-MS/MS to identify 25-HC in the supernatant of AngII-stimulated VSMCs. In the supernatants, 25-HC concentration peaked 4 h after AngII stimulation. Our findings provide insight into the pathways mediating AngII-induced Ch25h upregulation. Our study elucidates a connection between AngII stimulus and 25-HC production in primary rat VSMCs. These results potentially lead to the identification and understanding of new mechanisms in the pathogenesis of vascular impairments.

Uptake of severe acute respiratory syndrome coronavirus 2 spike protein mediated by angiotensin converting enzyme 2 and ganglioside in human cerebrovascular cells.

Introduction: There is clinical evidence of neurological manifestations in coronavirus disease-19 (COVID-19). However, it is unclear whether differences in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)/spike protein (SP) uptake by cells of the cerebrovasculature contribute to significant viral uptake to cause these symptoms. Methods: Since the initial step in viral invasion is binding/uptake, we used fluorescently labeled wild type and mutant SARS-CoV-2/SP to study this process. Three cerebrovascular cell types were used (endothelial cells, pericytes, and vascular smooth muscle cells), in vitro. Results: There was differential SARS-CoV-2/SP uptake by these cell types. Endothelial cells had the least uptake, which may limit SARS-CoV-2 uptake into brain from blood. Uptake was time and concentration dependent, and mediated by angiotensin converting enzyme 2 receptor (ACE2), and ganglioside (mono-sialotetrahexasylganglioside, GM1) that is predominantly expressed in the central nervous system and the cerebrovasculature. SARS-CoV-2/SPs with mutation sites, N501Y, E484K, and D614G, as seen in variants of interest, were also differentially taken up by these cell types. There was greater uptake compared to that of the wild type SARS-CoV-2/SP, but neutralization with anti-ACE2 or anti-GM1 antibodies was less effective. Conclusion: The data suggested that in addition to ACE2, gangliosides are also an important entry point of SARS-CoV-2/SP into these cells. Since SARS-CoV-2/SP binding/uptake is the initial step in the viral penetration into cells, a longer exposure and higher titer are required for significant uptake into the normal brain. Gangliosides, including GM1, could be an additional potential SARS-CoV-2 and therapeutic target at the cerebrovasculature.

CircRNAs: Key molecules in the prevention and treatment of ischemic stroke.

Ischemic stroke is a prevalent disease that seriously threatens human health. It is characterized by high morbidity, mortality, disability, and recurrence rates, causing a significant economic burden on individuals and society. Circular RNA, a novel non-coding RNA, not only serves as the sponge for microRNAs and proteins but also promotes transcription of their parental genes and translates into peptides. In recent years, circRNAs have emerged as key regulators in ischemic stroke. This article aims to provide new ideas about the pathogenesis and progression of ischemic stroke by reviewing the roles of circRNAs in cerebral ischemic injury and summarizing the association between circRNAs and risk factors for ischemic stroke.

Baby Blues: A Rare Case of Transient Pulmonary Arteriovenous Malformation During Pregnancy

Unexplained hypoxia in a pregnant patient is an alarming finding for patient and provider. The differential for hypoxia is broad, and many imaging techniques and procedures are contraindicated in pregnancy. Transient pulmonary arteriovenous malformations (AVMs) are a rare and relatively poorly studied cause of hypoxia in pregnancy. Our patient is a 27-year-old G1P0 female with a remote history of asthma who presented to clinic with slowly progressive exertional dyspnea, exertional tachycardia, and paroxysmal nocturnal dyspnea. She reported use of a home oximeter which read in the high 80s% during exertion. Prior to presentation, the patient was evaluated in the Emergency Department and noted to have an oxygen saturation of 86% on room air. A transthoracic echocardiogram, computed tomography angiography of chest, and basic laboratories including B-type natriuretic peptide, troponin, COVID-19, and hemoglobin were unremarkable. Her clinical timeline is presented in Figure 1. Further testing was obtained, including pulmonary function testing, bubble echocardiogram, nocturnal oximetry, and shunt study. Work-up revealed a 15-20% shunt, depending on calculation, and insignificant desaturations during nocturnal oximetry. Her symptoms progressed, and repeat nocturnal oximetry showed marked overnight desaturations requiring supplemental oxygen for the remainder of her pregnancy. She delivered a healthy baby girl via cesarean section without serious complication. Repeat testing in the post-partum period showed resolution of nocturnal desaturations and decreased shunt, and her exertional dyspnea and desaturations resolved spontaneously. This case illustrates the challenging diagnosis of transient pulmonary AVM in pregnancy. Case reports of this phenomenon have been published, but as in our case, no definitive diagnosis was made secondary to testing limitations in pregnancy and quick resolution of symptoms in the post-partum period. Some reports describe pre-existing pulmonary AVM becoming worse during pregnancy causing hemothorax, fetal demise and even death. While the mechanism is not known, theories include the vasodilatory effects of progesterone on vascular smooth muscle as well as other physiologic changes in pregnancy such as increased plasma volume. These AVM are thought to be like those seen in hepatopulmonary syndrome. Similar to our case, increasing positional hypoxia has been reported as the pregnancy progresses. Further research dedicated to early and accurate detection of pulmonary AVMs in pregnancy is necessary. (Figure Presented).

The endothelial glycocalyx in critical illness: A pediatric perspective.

The vascular endothelium is the interface between circulating blood and end organs and thus has a critical role in preserving organ function. The endothelium is lined by a glycan-rich glycocalyx that uniquely contributes to endothelial function through its regulation of leukocyte and platelet interactions with the vessel wall, vascular permeability, coagulation, and vasoreactivity. Degradation of the endothelial glycocalyx can thus promote vascular dysfunction, inflammation propagation, and organ injury. The endothelial glycocalyx and its role in vascular pathophysiology has gained increasing attention over the last decade. While studies characterizing vascular glycocalyx injury and its downstream consequences in a host of adult human diseases and in animal models has burgeoned, studies evaluating glycocalyx damage in pediatric diseases are relatively few. As children have unique physiology that differs from adults, significant knowledge gaps remain in our understanding of the causes and effects of endothelial glycocalyx disintegrity in pediatric critical illness. In this narrative literature overview, we offer a unique perspective on the role of the endothelial glycocalyx in pediatric critical illness, drawing from adult and preclinical data in addition to pediatric clinical experience to elucidate how marked derangement of the endothelial surface layer may contribute to aberrant vascular biology in children. By calling attention to this nascent field, we hope to increase research efforts to address important knowledge gaps in pediatric vascular biology that may inform the development of novel therapeutic strategies.

Late-Breaking Basic Science Abstracts From the American Heart Association's Scientific Sessions 2021

The proceedings contain 34 papers. The topics discussed include: combinatorial maturation of patient stem cell-derived atrial cardiomyocytes unmasks mechanism of atrial fibrillation induced by NPPA gene mutation;the pathogenesis of Covid-19 myocardial injury: an immunohistochemical study of postmortem biopsies;mitochondrial optogenetic-mediated preconditioning protects cardiomyocytes from stress-induced injury;the aldose reductase inhibitor At-001 improves cardiac efficiency and decreases diastolic dysfunction in an animal model of diabetic cardiomyopathy: comparative and add-on studies versus SGLT-2 inhibition;cardiomyocyte specific deletion Of Trpv4 offers cardio-protection independent of cardiac fibrosis following pressure overload-induced hypertrophy;and sacubitril-valsartan protects against aortic aneurysm progression via regulating neprilysin-induced vascular smooth muscle cell apoptosis.

Endolysosomal Ca2+ signaling in cardiovascular health and disease.

An increase in intracellular Ca2+ concentration ([Ca2+]i) regulates a plethora of functions in the cardiovascular (CV) system, including contraction in cardiomyocytes and vascular smooth muscle cells (VSMCs), and angiogenesis in vascular endothelial cells and endothelial colony forming cells. The sarco/endoplasmic reticulum (SR/ER) represents the largest endogenous Ca2+ store, which releases Ca2+ through ryanodine receptors (RyRs) and/or inositol-1,4,5-trisphosphate receptors (InsP3Rs) upon extracellular stimulation. The acidic vesicles of the endolysosomal (EL) compartment represent an additional endogenous Ca2+ store, which is targeted by several second messengers, including nicotinic acid adenine dinucleotide phosphate (NAADP) and phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2], and may release intraluminal Ca2+ through multiple Ca2+ permeable channels, including two-pore channels 1 and 2 (TPC1-2) and Transient Receptor Potential Mucolipin 1 (TRPML1). Herein, we discuss the emerging, pathophysiological role of EL Ca2+ signaling in the CV system. We describe the role of cardiac TPCs in ß-adrenoceptor stimulation, arrhythmia, hypertrophy, and ischemia-reperfusion injury. We then illustrate the role of EL Ca2+ signaling in VSMCs, where TPCs promote vasoconstriction and contribute to pulmonary artery hypertension and atherosclerosis, whereas TRPML1 sustains vasodilation and is also involved in atherosclerosis. Subsequently, we describe the mechanisms whereby endothelial TPCs promote vasodilation, contribute to neurovascular coupling in the brain and stimulate angiogenesis and vasculogenesis. Finally, we discuss about the possibility to target TPCs, which are likely to mediate CV cell infection by the Severe Acute Respiratory Disease-Coronavirus-2, with Food and Drug Administration-approved drugs to alleviate the detrimental effects of Coronavirus Disease-19 on the CV system.

ACE2/Ang-(1-7)/Mas1 axis and the vascular system: vasoprotection to COVID-19-associated vascular disease.

The two axes of the renin-angiotensin system include the classical ACE/Ang II/AT1 axis and the counter-regulatory ACE2/Ang-(1-7)/Mas1 axis. ACE2 is a multifunctional monocarboxypeptidase responsible for generating Ang-(1-7) from Ang II. ACE2 is important in the vascular system where it is found in arterial and venous endothelial cells and arterial smooth muscle cells in many vascular beds. Among the best characterized functions of ACE2 is its role in regulating vascular tone. ACE2 through its effector peptide Ang-(1-7) and receptor Mas1 induces vasodilation and attenuates Ang II-induced vasoconstriction. In endothelial cells activation of the ACE2/Ang-(1-7)/Mas1 axis increases production of the vasodilator's nitric oxide and prostacyclin's and in vascular smooth muscle cells it inhibits pro-contractile and pro-inflammatory signaling. Endothelial ACE2 is cleaved by proteases, shed into the circulation and measured as soluble ACE2. Plasma ACE2 activity is increased in cardiovascular disease and may have prognostic significance in disease severity. In addition to its enzymatic function, ACE2 is the receptor for severe acute respiratory syndrome (SARS)-coronavirus (CoV) and SARS-Cov-2, which cause SARS and coronavirus disease-19 (COVID-19) respectively. ACE-2 is thus a double-edged sword: it promotes cardiovascular health while also facilitating the devastations caused by coronaviruses. COVID-19 is associated with cardiovascular disease as a risk factor and as a complication. Mechanisms linking COVID-19 and cardiovascular disease are unclear, but vascular ACE2 may be important. This review focuses on the vascular biology and (patho)physiology of ACE2 in cardiovascular health and disease and briefly discusses the role of vascular ACE2 as a potential mediator of vascular injury in COVID-19.