Angiotensin-Converting Enzyme 2 Expression and Severity of SARS-CoV-2 Infection

Angiotensin-converting enzyme 2 (ACE2), first discovered in 2000, serves as an important counterregulatory enzyme to the angiotensin II-mediated vasoconstrictive, pro-inflammatory, and pro-fibrotic actions of the renin–angiotensin system (RAS). Conversion of angiotensin II to the peptide angiotensin 1–7 (ANG 1–7) exerts protective vasodilatory, anti-inflammatory, and anti-fibrotic actions through interaction with the MasR receptor. There are many important considerations when noting the role of ACE2 in the pathogenesis and sequelae of COVID-19 infection. ACE2, in the role of COVID-19 infection, was recognized early in 2020 at the beginning of the pandemic as a cell membrane-bound and soluble binding site for the viral spike protein facilitating entering into tissue cells expressing ACE2, such as the lungs, heart, gut, and kidneys. Mechanisms exist that alter the magnitude of circulating and membrane-bound ACE2 (e.g., SARS-CoV-2 infection, viral variants, patient characteristics, chronic disease states, and the degree of cell surface expression of ACE2) and the influence these mechanisms have on the severity of disease and associated complications (e.g., respiratory failure, systemic inflammatory response syndrome, acute myocarditis, acute kidney injury). Several medications alter the ACE2 receptor expression, but whether these medications can influence the course of the disease and improve outcomes is unclear. In this review, we will discuss what is known about the interrelation of SARS-CoV-2, ACE2 and the factors that may contribute to the variability of its expression and potential contributors to the severity of COVID-19 infection

Identification of Differentially Expressed Transcripts and Pathways in Blood One Week and Six Months Following Implant of Left Ventricular Assist Devices

<div><p>Introduction</p><p>Continuous-flow left ventricular assist devices (LVADs) are an established therapy for patients with end-stage heart failure. The short- and long-term impact of these devices on peripheral blood gene expression has not been characterized, and may provide insight into the molecular pathways mediated in response to left ventricular remodeling and an improvement in overall systemic circulation. We performed RNA sequencing to identify genes and pathways influenced by these devices.</p> <p>Methods</p><p>RNA was extracted from blood of 9 heart failure patients (8 male) prior to LVAD implantation, and at 7 and 180 days postoperatively. Libraries were sequenced on an Illumina HiSeq2000 and sequences mapped to the human Ensembl GRCh37.67 genome assembly.</p> <p>Results</p><p>A specific set of genes involved in regulating cellular immune response, antigen presentation, and T cell activation and survival were down-regulated 7 days after LVAD placement. 6 months following LVAD placement, the expression levels of these genes were significantly increased; yet importantly, remained significantly lower than age and sex-matched samples from healthy controls.</p> <p>Conclusions</p><p>In summary, this genomic analysis identified a significant decrease in the expression of genes that promote a healthy immune response in patients with heart failure that was partially restored 6 months following LVAD implant.</p> </div

Relative expression (mean 2^{- ΔΔCt}) of select genes among six individuals without heart failure, four patients that underwent non-LVAD cardiac surgery (prior to and 7 days after surgery), and nine end-stage heart failure patients (prior to and 7 days after LVAD implant) as measured by RT-qPCR.

<p>Ŧ p < 0.05 compared to non-heart failure patients, * p < 0.05 compared to pre surgery (non-LVAD cardiac surgery or LVAD implant). </p

Temporal Improvements in COVID-19 Outcomes for Hospitalized Adults: A Post Hoc Observational Study of Remdesivir Group Participants in the Adaptive COVID-19 Treatment Trial

BackgroundThe COVID-19 standard of care (SOC) evolved rapidly during 2020 and 2021, but its cumulative effect over time is unclear.ObjectiveTo evaluate whether recovery and mortality improved as SOC evolved, using data from ACTT (Adaptive COVID-19 Treatment Trial).DesignACTT is a series of phase 3, randomized, double-blind, placebo-controlled trials that evaluated COVID-19 therapeutics from February 2020 through May 2021. ACTT-1 compared remdesivir plus SOC to placebo plus SOC, and in ACTT-2 and ACTT-3, remdesivir plus SOC was the control group. This post hoc analysis compared recovery and mortality between these comparable sequential cohorts of patients who received remdesivir plus SOC, adjusting for baseline characteristics with propensity score weighting. The analysis was repeated for participants in ACTT-3 and ACTT-4 who received remdesivir plus dexamethasone plus SOC. Trends in SOC that could explain outcome improvements were analyzed. (ClinicalTrials.gov: NCT04280705 [ACTT-1], NCT04401579 [ACTT-2], NCT04492475 [ACTT-3], and NCT04640168 [ACTT-4]).Setting94 hospitals in 10 countries (86% U.S. participants).ParticipantsAdults hospitalized with COVID-19.InterventionSOC.Measurements28-day mortality and recovery.ResultsAlthough outcomes were better in ACTT-2 than in ACTT-1, adjusted hazard ratios (HRs) were close to 1 (HR for recovery, 1.04 [95% CI, 0.92 to 1.17]; HR for mortality, 0.90 [CI, 0.56 to 1.40]). Comparable patients were less likely to be intubated in ACTT-2 than in ACTT-1 (odds ratio, 0.75 [CI, 0.53 to 0.97]), and hydroxychloroquine use decreased. Outcomes improved from ACTT-2 to ACTT-3 (HR for recovery, 1.43 [CI, 1.24 to 1.64]; HR for mortality, 0.45 [CI, 0.21 to 0.97]). Potential explanatory factors (SOC trends, case surges, and variant trends) were similar between ACTT-2 and ACTT-3, except for increased dexamethasone use (11% to 77%). Outcomes were similar in ACTT-3 and ACTT-4. Antibiotic use decreased gradually across all stages.LimitationUnmeasured confounding.ConclusionChanges in patient composition explained improved outcomes from ACTT-1 to ACTT-2 but not from ACTT-2 to ACTT-3, suggesting improved SOC. These results support excluding nonconcurrent controls from analysis of platform trials in rapidly changing therapeutic areas.Primary funding sourceNational Institute of Allergy and Infectious Diseases