Alzheimer's disease and COVID-19

In elderly patients with COVID-19 cognitive functions decline;it has been suggested that SARS-CoV-2 infection may lead to the development of Alzheimer's disease (AD) and other long-term neurological consequences. We review several parallels between AD and COVID-19 in terms of pathogenetic mechanisms and risk factors. Possible mechanisms through which COVID-19 can initiate AD are discussed. These include systemic inflammation, hyperactivation of the renin-angiotensin system, innate immune activation, oxidative stress, and direct viral damage. It has been shown that increased expression of angiotensin-renin receptors (ACE2) may be a risk factor for COVID-19 in patients with AD. When entering the central nervous system, the SARS-CoV-2 virus can directly activate glial cell-mediated immune responses, which in turn can lead to the accumulation of beta-amyloid and the subsequent onset or progression of current AD. The involvement of inflammatory biomarkers, including interleukins (IL): IL6, IL1, as well as galectin-3, as a link between COVID-19 and AD is discussed. The rationale for the use of memantine (akatinol memantine) in patients with COVID-19 in order to prevent the development of cognitive deficits is discussed. Memantine has been shown to have a positive effect on neuroinflammatory processes in the onset or exacerbation of cognitive deficits, in reducing cerebral vasospasm and endothelial dysfunction in viral infections. Memantine therapy may improve everyday activity and reduce the risk of severe SARS-CoV-2 infection.Copyright © 2022 Ima-Press Publishing House. All rights reserved.

ACE and ACE2 catalytic activity in the fecal content along the gut.

BACKGROUND: Angiotensin-converting enzyme (ACE) and ACE2 are two major enzymes of the renin-angiotensin-aldosterone system (RAAS), which control the formation/degradation of angiotensin (Ang) II and Ang1-7, regulating their opposite effects. We aimed at evaluating the catalytic activity of ACE and ACE2 in the intestinal content and corresponding intestinal tissue along the gut of Wistar Han rats. METHODS: Portions of the ileum, cecum, proximal colon, and distal colon, and the corresponding intestinal content were collected from Wistar Han rats. Enzyme activity was evaluated by fluorometric assays using different substrates: Hippuryl-His-Leu for ACE-C-domain, Z-Phe-His-Leu for ACE-N-domain, and Mca-APK(Dnp) for ACE2. ACE and ACE2 concentration was assessed by ELISA. Ratios concerning concentrations and activities were calculated to evaluate the balance of the RAAS. Statistical analysis was performed using Friedman test followed by Dunn's multiple comparisons test or Wilcoxon matched-pairs test whenever needed. KEY RESULTS: ACE and ACE2 are catalytically active in the intestinal content along the rat gut. The ACE N-domain shows higher activity than the C-domain both in the intestinal content and in the intestinal tissue. ACE and ACE2 are globally more active in the intestinal content than in the corresponding intestinal tissue. There was a distal-to-proximal prevalence of ACE2 over ACE in the intestinal tissue. CONCLUSIONS & INFERENCES: This work is the first to report the presence of catalytically active ACE and ACE2 in the rat intestinal content, supporting future research on the regulatory role of the intestinal RAAS on gut function and a putative link to the microbiome.

Amiodarone for the Treatment of Arrhythmias in COVID-19 Patients Does Not Increase the Risk of Pulmonary Fibrosis: A Retrospective Cohort Study.

Amiodarone is a class III antiarrhythmic medication used to treat atrial and ventricular tachyarrhythmias. Pulmonary fibrosis from amiodarone use is a well-documented side effect. Pre-COVID-19 pandemic studies have shown that amiodarone-induced pulmonary fibrosis occurs in 1%-5% of patients and usually occurs between 12 to 60 months after initiation. The risk factors associated with amiodarone-induced pulmonary fibrosis include a high total cumulative dose (treatment longer than two months) and high maintenance dose (>400 mg/day). COVID-19 infection is also a known risk factor for developing pulmonary fibrosis and occurs in approximately 2%-6% of patients after a moderate illness. This study aims to assess the incidence of amiodarone in COVID-19 pulmonary fibrosis (ACPF). This is a retrospective cohort study with 420 patients with COVID-19 diagnoses between March 2020 and March 2022, comparing two populations, COVID-19 patients with exposure to amiodarone (N=210) and COVID-19 patients without amiodarone exposure (N=210). In our study, pulmonary fibrosis occurred in 12.9% of patients in the amiodarone exposure group compared to 10.5% of patients in the COVID-19 control group (p=0.543). In multivariate logistic analysis, which controlled for clinical covariates, amiodarone use in COVID-19 patients did not increase the odds of developing pulmonary fibrosis (odds ratio (OR): 1.02, 95% confidence interval (CI): 0.52-2.00). The clinical factors associated with the development of pulmonary fibrosis in both groups included a history of preexisting interstitial lung disease (ILD) (p=0.001), exposure to prior radiation therapy (p=0.021), and higher severity of COVID-19 illness (p<0.001). In conclusion, our study found no evidence that amiodarone use in COVID-19 patients increased the odds of developing pulmonary fibrosis at six-month follow-up. However, long-term amiodarone usage in the COVID-19 population should be based on the physician's discretion.

Primary Aldosteronism and COVID-19-related Management, Disease Severity, and Outcomes: A Retrospective Cohort Study.

Context: The SARS-CoV-2 virus is dependent on components of the renin-angiotensin-aldosterone system for infectivity. Primary aldosteronism (PA) is a form of secondary hypertension mediated by autonomous aldosterone production. The intersection of COVID-19 and PA, both which may involve components of the renin-angiotensin-aldosterone system, remains unknown. Methods: We assessed PA as a risk factor for COVID-19 infection and compared management, severity of disease, and outcomes during COVID-19 with a matched population of patients with essential hypertension (EH) by conducting a retrospective observational cohort study. Results: Of the patients with PA, 81 had a negative PCR test for COVID-19, whereas 43 had a documented positive PCR test for COVID-19. Those patients with PA who tested positive for COVID-19 tended to be female (P = .08) and the majority of those with COVID-19 infection identified as non-White race (P = .02) and Hispanic ethnicity (P = .02). In a subanalysis, 24-hour urine aldosterone on initial PA diagnosis tended to be higher those in the PA group who developed COVID-19 compared with those in the PA group who did not develop COVID-19 [median (interquartile range): 36.5 (16.9, 54.3) vs 22.0 (15.8, 26.8) mcg, P = .049] and was an independent predictor of COVID-19 infection controlling for sex, race, and ethnicity. Angiotensin-converting enzyme inhibitor, angiotensin II receptor blocker, and mineralocorticoid receptor antagonist use did not differ between those patients with PA who did and did not have COVID-19 infection. Comparing those patients with PA and matched patients with EH (n = 286) who were COVID-19 PCR positive, there was a significantly higher incidence of cardiovascular complications (12 vs 2%, P = .004) in the PA vs EH group. Conclusion: These data begin to inform us as to whether PA should be a newly identified subpopulation at risk for COVID-19-related cardiovascular disease sequelae.

Beauty and the beast: host microRNA-155 versus SARS-CoV-2.

Severe acute respiratory coronavirus 2 (SARS-CoV-2) infection in the young and healthy usually results in an asymptomatic or mild viral syndrome, possibly through an erythropoietin (EPO)-dependent, protective evolutionary landscape. In the old and in the presence of co-morbidities, however, a potentially lethal coronavirus disease 2019 (COVID-19) cytokine storm, through unrestrained renin-angiotensin aldosterone system (RAAS) hyperactivity, has been described. Multifunctional microRNA-155 (miR-155) elevation in malaria, dengue virus (DENV), the thalassemias, and SARS-CoV-1/2, plays critical antiviral and cardiovascular roles through its targeted translational repression of over 140 genes. In the present review, we propose a plausible miR-155-dependent mechanism whereby the translational repression of AGRT1, Arginase-2 and Ets-1, reshapes RAAS towards Angiotensin II (Ang II) type 2 (AT2R)-mediated balanced, tolerable, and SARS-CoV-2-protective cardiovascular phenotypes. In addition, it enhances EPO secretion and endothelial nitric oxide synthase activation and substrate availability, and negates proinflammatory Ang II effects. Disrupted miR-155 repression of AT1R + 1166C-allele, significantly associated with adverse cardiovascular and COVID-19 outcomes, manifests its decisive role in RAAS modulation. BACH1 and SOCS1 repression creates an anti-inflammatory and cytoprotective milieu, robustly inducing antiviral interferons. MiR-155 dysregulation in the elderly, and in comorbidities, allows unimpeded RAAS hyperactivity to progress towards a particularly aggressive COVID-19 course. Elevated miR-155 in thalassemia plausibly engenders a favorable cardiovascular profile and protection against malaria, DENV, and SARS-CoV-2. MiR-155 modulating pharmaceutical approaches could offer novel therapeutic options in COVID-19.

Renin-Angiotensin-Aldosterone Inhibitors and COVID-19 Infection.

PURPOSE OF REVIEW: This review summarises the literature data and provides an overview of the role and impact of the use of renin-angiotensin-aldosterone system (RAAS) inhibitors in patients with coronavirus disease 2019 (COVID-19) infection. RECENT FINDINGS: The angiotensin-converting enzyme 2 (ACE2) has a key role in the regulation of the RAAS pathway, downregulating angiotensin II and attenuating inflammation, vasoconstriction and oxidative stress. Additionally, it plays an instrumental part in COVID-19 infection as it facilitates the cell entry of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and enables its replication. The use and role of RAAS inhibitors therefore during the COVID-19 pandemic have been intensively investigated. Although it was initially assumed that RAAS inhibitors may relate to worse clinical outcomes and severe disease, data from large studies and meta-analyses demonstrated that they do not have an adverse impact on clinical outcomes or prognosis. On the contrary, some experimental and retrospective observational cohort studies showed a potential protective mechanism, although this effect remains to be seen in large clinical trials.

Molecular and cellular mechanisms involved in tissue-specific metabolic modulation by SARS-CoV-2.

Coronavirus disease 2019 (COVID-19) is triggered by the SARS-CoV-2, which is able to infect and cause dysfunction not only in lungs, but also in multiple organs, including central nervous system, skeletal muscle, kidneys, heart, liver, and intestine. Several metabolic disturbances are associated with cell damage or tissue injury, but the mechanisms involved are not yet fully elucidated. Some potential mechanisms involved in the COVID-19-induced tissue dysfunction are proposed, such as: (a) High expression and levels of proinflammatory cytokines, including TNF-α IL-6, IL-1ß, INF-α and INF-ß, increasing the systemic and tissue inflammatory state; (b) Induction of oxidative stress due to redox imbalance, resulting in cell injury or death induced by elevated production of reactive oxygen species; and (c) Deregulation of the renin-angiotensin-aldosterone system, exacerbating the inflammatory and oxidative stress responses. In this review, we discuss the main metabolic disturbances observed in different target tissues of SARS-CoV-2 and the potential mechanisms involved in these changes associated with the tissue dysfunction.