Disequilibrium between the classic renin-angiotensin system and its opposing arm in SARS-CoV-2-related lung injury

Serum angiotensin type-1 receptor autoantibodies and neurofilament light chain as markers of neuroaxonal damage in post-COVID patients

Introduction

Dysregulation of autoimmune responses and the presence of autoantibodies (AA), particularly those related to the renin-angiotensin system (RAS), have been implicated in the acute phase of COVID-19, and persistent dysregulation of brain RAS by RAS-related autoantibodies may also contribute to neurological symptoms of post-COVID.

Methods

We analyzed levels of serum and CSF RAS AA in post-COVID patients with neurological symptoms, individuals who have fully recovered from COVID-19 (after-COVID controls), and uninfected individuals, and their possible correlations with the serum marker of neuroaxonal damage neurofilament light chain (NfL) and the degrees of cognitive deficit.

Results

Both in serum and CSF, levels of AA agonists of the pro-inflammatory angiotensin II type 1 receptors (AT1-AA) were significantly elevated in this cohort of neurological post-COVID patients compared to both uninfected and after-COVID controls and correlated with serum levels of NfL. Changes in serum and CSF levels of AA promoting the RAS anti-inflammatory axis (upregulation of AA agonists of AT2 and Mas receptors, downregulation of AA antagonists of ACE2) suggest upregulation of the RAS compensatory response in this cohort of neurological post-COVID patients. Post-COVID patients with more pronounced cognitive impairment exhibited significantly higher CSF levels of MasR-AA and a trend toward elevated AT2-AA. Persistent brain RAS dysregulation, particularly persistent increase in AT1-AA, and its correlation with neuroaxonal damage markers and cognitive impairment, may play a significant role in neurological symptoms associated with post-COVID. Serum levels of NfL and AT1-AA may be interesting biomarkers for the early identification of CNS involvement in patients with neurological symptoms and a history of COVID-19. However, post-COVID is a highly heterogeneous entity and may result from various underlying mechanisms. The present study includes a cohort, which may differ from other cohorts with different clinical profiles, which may show different results on NfLs and CSF RAS autoantibodies, particularly AT1-AA.

Conclusion

These findings highlight the potential of targeting AT1 receptors as a therapeutic strategy for mitigating cognitive deficits in post-COVID patients showing upregulated AT1-AA levels.

Pharmacological mechanisms of traditional Chinese medicine against acute lung injury: From active ingredients to herbal formulae

BACKGROUND

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are the leading causes of acute respiratory failure in many critical diseases and are among the main respiratory diseases with high clinical mortality. The global outbreak of coronavirus disease 2019 (COVID-19) can cause severe ARDS, resulting in a steep rise in the number of patient deaths. Therefore, it is important to explore the pathogenesis of ALI and find effective therapeutic agents. In recent years, thanks to modern biomedical tools, some progress has been made in the application of traditional Chinese medicine (TCM) treatment principles based on syndromic differentiation and holistic concepts in clinical and experimental studies of ALI. More and more TCM effective components and formulae have been verified to have significant curative effects, which have a certain guiding significance for clinical practice.

PURPOSE

It is hoped to provide reference for the clinical research of ALI/ARDS and provide theoretical basis and technical support for the scientific application of TCM in respiratory related diseases.

METHODS

We performed a literature survey using traditional books of Chinese medicine and online scientific databases including PubMed, Web of Science, Google Scholar, ScienceDirect, China National Knowledge Infrastructure (CNKI), and others up to January 2023.

RESULTS

In recent years, thanks to modern biomedical tools, some progress has been made in the application of TCM treatment principles based on syndromic differentiation and holistic concepts in clinical and experimental studies of ALI. This paper mainly reviews the research progress of ALI/ARDS mechanism, the understanding of its etiology and pathogenesis by TCM, and the therapeutic effects of TCM formulae and active ingredients of Chinese medicine. A large number of studies have shown that the effective components and formulae of TCM can prevent or treat ALI/ARDS in vivo and in vitro experiments.

CONCLUSION

TCM effective components and formulae play an important role in the prevention and treatment of ALI/ARDS through multiple approaches and multiple targets, and provide necessary theoretical support for the further development and utilization of TCM resources.

Clinical significance and potential mechanism of hsa_circ_0006892 in acute respiratory distress syndrome complicated with pulmonary fibrosis

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a serious acute lung injury, and can develop into pulmonary fibrosis (PLF). Circular RNAs (circRNAs) regulatory network in ARDS is important. The study explored the role of hsa_circ_0006892 in the occurrence of ARDS and the development of PLF.

METHODS

Hsa_circ_0006892 levels were verified in serum samples of 203 ARDS patients with or without PLF, and the diagnostic value was evaluated through ROC. Cox regression analysis was performed to identify PLF-related factors. The downstream target genes were predicted online. The function and pathway of key genes were annotated through GO and KEGG pathway analysis. Protein-protein interaction (PPI) analysis was performed for the examination of protein interactions.

RESULTS

qRT-PCR determined the downregulation of hsa_circ_0006892 in the serum of both ARDS and PLF patients. Hsa_circ_0006892 can differentiate ARDS from controls, and independently related to the development of PLF. Nine targeted related miRNAs were integrated with dysregulated miRNAs from GSE27430 dataset. Clinically, miR-486-3p was the only miRNA that was significantly different in both ARDS and PLF groups, and was determined to be the target of hsa_circ_0006892. 180 target genes of miR-486-3p were predicted, which were integrated with ARDS and PLF-related GSE84439 and GSE38958 datasets. Go and KEGG pathway analysis identified Ras signaling pathway as the most commonly enriched pathway in the overlapped genes.

CONCLUSIONS

The present results identified the differentially expressed hsa_circ_0006892 in ARDS and PLF, and suggested a possible molecular mechanism of hsa_circ_0006892/miR-486-3p axis.

Unveiling the Interplay-Vitamin D and ACE-2 Molecular Interactions in Mitigating Complications and Deaths from SARS-CoV-2

The interaction of the SARS-CoV-2 spike protein with membrane-bound angiotensin-converting enzyme-2 (ACE-2) receptors in epithelial cells facilitates viral entry into human cells. Despite this, ACE-2 exerts significant protective effects against coronaviruses by neutralizing viruses in circulation and mitigating inflammation. While SARS-CoV-2 reduces ACE-2 expression, vitamin D increases it, counteracting the virus's harmful effects. Vitamin D's beneficial actions are mediated through complex molecular mechanisms involving innate and adaptive immune systems. Meanwhile, vitamin D status [25(OH)D concentration] is inversely correlated with severity, complications, and mortality rates from COVID-19. This study explores mechanisms through which vitamin D inhibits SARS-CoV-2 replication, including the suppression of transcription enzymes, reduced inflammation and oxidative stress, and increased expression of neutralizing antibodies and antimicrobial peptides. Both hypovitaminosis D and SARS-CoV-2 elevate renin levels, the rate-limiting step in the renin-angiotensin-aldosterone system (RAS); it increases ACE-1 but reduces ACE-2 expression. This imbalance leads to elevated levels of the pro-inflammatory, pro-coagulatory, and vasoconstricting peptide angiotensin-II (Ang-II), leading to widespread inflammation. It also causes increased membrane permeability, allowing fluid and viruses to infiltrate soft tissues, lungs, and the vascular system. In contrast, sufficient vitamin D levels suppress renin expression, reducing RAS activity, lowering ACE-1, and increasing ACE-2 levels. ACE-2 cleaves Ang-II to generate Ang(1-7), a vasodilatory, anti-inflammatory, and anti-thrombotic peptide that mitigates oxidative stress and counteracts the harmful effects of SARS-CoV-2. Excess ACE-2 molecules spill into the bloodstream as soluble receptors, neutralizing and facilitating the destruction of the virus. These combined mechanisms reduce viral replication, load, and spread. Hence, vitamin D facilitates rapid recovery and minimizes transmission to others. Overall, vitamin D enhances the immune response and counteracts the pathological effects of SARS-CoV-2. Additionally, data suggests that widely used anti-hypertensive agents-angiotensin receptor blockers and ACE inhibitors-may lessen the adverse impacts of SARS-CoV-2, although they are less potent than vitamin D.

Vitamin D supplementation and calcium: Many-faced gods or nobody in fighting against Corona Virus Disease 2019

In December 2019, Corona Virus Disease 2019 (COVID-19) was first identified and designated as a pandemic in March 2020 due to rapid spread of the virus globally. At the beginning of the pandemic, only a few treatment options, mainly focused on supportive care and repurposing medications, were available. Due to its effects on immune system, vitamin D was a topic of interest during the pandemic, and researchers investigated its potential impact on COVID-19 outcomes. However, the results of studies about the impact of vitamin D on the disease are inconclusive. In the present narrative review, different roles of vitamin D regarding the COVID-19 have been discussed to show that vitamin D supplementation should be recommended carefully.

MiR-145-5p reduced ANG II-induced ACE2 shedding and the inflammatory response in alveolar epithelial cells by targeting ADAM17 and inhibiting the AT1R/ADAM17 pathway

The excessive elevation of angiotensin II (ANG II) is closely associated with the occurrence and development of aortic dissection (AD)-related acute lung injury (ALI), through its binding to angiotensin II receptor type I (AT1R). MiR-145-5p is a noncoding RNA that can be involved in a variety of cellular physiopathological processes. Transfection with miR-145-5p was found to downregulated the expression of A disintegrin and metalloprotease 17 (ADAM17) and reduced the levels of angiotensin-converting enzyme 2 (ACE2) in lung tissue, while concurrently increasing plasma ACE2 levels in the AD combined with ALI mice. ADAM17 was proved to be a target of miR-145-5p. Transfection with miR-145-5p decreased the shedding of ACE2 and alleviated the inflammatory response induced by ANG II through targeting ADAM17 and inhibiting the AT1R/ADAM17 pathway in A549 cells. In conclusion, our present study demonstrates the role and mechanism of miR-145-5p in alleviating ANG II-induced acute lung injury, providing a new insight into miRNA therapy for reducing lung injury in patients with aortic dissection.

Hyperoxia-induced airflow restriction and Renin-Angiotensin System expression in a bronchopulmonary dysplasia mouse model

Mechanisms underlying hyperoxia-induced airflow restriction in the pediatric lung disease Bronchopulmonary dysplasia (BPD) are unclear. We hypothesized a role for Renin-Angiotensin System (RAS) activity in BPD. RAS is comprised of a pro-developmental pathway consisting of angiotensin converting enzyme-2 (ACE2) and angiotensin II receptor type 2 (AT2), and a pro-fibrotic pathway mediated by angiotensin II receptor type 1 (AT1). We investigated associations between neonatal hyperoxia, airflow restriction, and RAS activity in a BPD mouse model. C57 mouse pups were randomized to normoxic (FiO2  = 0.21) or hyperoxic (FiO2  = 0.75) conditions for 15 days (P1-P15). At P15, P20, and P30, we measured airflow restriction using plethysmography and ACE2, AT1, and AT2 mRNA and protein expression via polymerase chain reaction and Western Blot. Hyperoxia increased airflow restriction P15 and P20, decreased ACE2 and AT2 mRNA, decreased AT2 protein, and increased AT1 protein expression. ACE2 mRNA and protein remained suppressed at P20. By P30, airflow restriction and RAS expression did not differ between groups. Hyperoxia caused high airflow restriction, increased pulmonary expression of the pro-fibrotic RAS pathway, and decreased expression of the pro-developmental in our BPD mouse model. These associated findings may point to a causal role for RAS in hyperoxia-induced airflow restriction.

Angiotensin II type 2 receptor agonist attenuates LPS-induced acute lung injury through modulating THP-1-derived macrophage reprogramming

Acute respiratory distress syndrome (ARDS) is a devastating respiratory disorder, characterized by overwhelming inflammation in the alveoli without effective pharmacological treatment. We aimed to investigate the effect and mechanism of angiotensin II type 2 receptor (AT2R) agonist, Compound 21 (C21), on the lipopolysaccharide (LPS)-induced acute lung injury (ALI) model. The protective effect of C21 was evaluated via enzyme-linked immunosorbent assay (ELISA), Western blot (WB), real-time PCR, and fluorescence microscopy in LPS-challenged THP1-derived macrophages. Besides, the in vivo efficacy of C21 was assessed using cell counting, ELISA, protein quantification, hematoxylin-eosin (H&E) staining, and WB in an LPS-induced ALI mouse model. The results showed that C21 significantly inhibited the secretion of pro-inflammatory cytokines (CCL-2, IL-6), overproduction of intracellular ROS, and activation of inflammatory pathways (NF-κB/NLRP3, p38/MAPK) in THP-1 cell-derived macrophages stimulated by LPS. In in vivo study, intraperitoneal injection of C21 could reduce airway leukocytes accumulation and chemokine/cytokine (keratinocyte chemoattractant (KC), IL-6) generation, as well as alleviate diffuse alveolar damage induced by LPS. Conclusively, the AT2R agonist C21 significantly inhibited LPS-stimulated excess inflammatory responses and oxidative stress in macrophages. Meanwhile, C21 could effectively alleviate acute inflammation and tissue damage in the lungs of ALI mice challenged by LPS. The results of this study bring new hope for the early treatment of ALI/ARDS.

Angiotensin-converting enzyme 2 in human plasma and lung tissue

PURPOSE

We investigated plasma angiotensin-converting enzyme 2 (ACE2) concentration in a population sample and the ACE2 expression quantitated with the diaminobenzidine mean intensity in the lung tissue in patients who underwent lung surgery.

MATERIALS AND METHODS

The study participants were recruited from a residential area in the suburb of Shanghai for the plasma ACE2 concentration study (n = 503) and the lung tissue samples were randomly selected from the storage in Ruijin Hospital (80 men and 78 age-matched women).

RESULTS

In analyses adjusted for covariables, men had a significantly higher plasma ACE2 concentration (1.21 vs. 0.98 ng/mL, p = 0.027) and the mean intensity of ACE2 in the lung tissue (55.1 vs. 53.9 a.u., p = 0.037) than women. With age increasing, plasma ACE2 concentration decreased (p = 0.001), while the mean intensity of ACE2 in the lung tissue tended to increase (p = 0.087). Plasma ACE2 concentration was higher in hypertension than normotension, especially treated hypertension (1.23 vs. 0.98 ng/mL, p = 0.029 vs. normotension), with no significant difference between users of RAS inhibitors and other classes of antihypertensive drugs (p = 0.64). There was no significance of the mean intensity of ACE2 in the lung tissue between patients taking and those not taking RAS inhibitors (p = 0.14). Neither plasma ACE2 concentration nor the mean intensity of ACE2 in the lung tissue differed between normoglycemia and diabetes (p ≥ 0.20).

CONCLUSION

ACE2 in the plasma and lung tissue showed divergent changes according to several major characteristics of patients.Plain language summary What is the context? • The primary physiological function of ACE2 is the degradation of angiotensin I and II to angiotensin 1-9 and 1-7, respectively. • ACE2 was found to behave as a mediator of the severe acute respiratory syndrome coronavirus (SARS) infection. • There is little research on ACE2 in humans, especially in the lung tissue. • In the present report, we investigated plasma ACE2 concentration and the ACE2 expression quantitated with the diaminobenzidine mean intensity in the lung tissue respectively in two study populations. What is new? • Our study investigated both circulating and tissue ACE2 in human subjects. The main findings were: • In men as well as women, plasma ACE2 concentration was higher in younger than older participants, whereas the mean intensity of ACE2 in the lung tissue increase with age increasing. • Compared with normotension, hypertensive patients had higher plasma ACE2 concentration but similar mean intensity of ACE2 in the lung tissue. • Neither plasma ACE2 concentration nor lung tissue ACE2 expression significantly differed between users of RAS inhibitors and other classes of antihypertensive drugs. What is the impact? • ACE2 in the plasma and lung tissue showed divergent changes according to several major characteristics, such as sex, age, and treated and untreated hypertension. • A major implication is that plasma ACE2 concentration might not be an appropriate surrogate for the ACE2 expression in the lung tissue, and hence not a good predictor of SARS-COV-2 infection or fatality.

Effect of Angiotensin-Converting Enzyme Inhibitors/Angiotensin Receptor Blockers on In-Hospital Outcomes Based on Renal Function Among Critically Ill Patients: Findings From the Medical Information Mart for Intensive Care IV Database

Renal dysfunction is associated with increased mortality and length of hospital stay in critically ill patients. However, it remains unclear whether the early administration of an angiotensin-converting enzyme inhibitor (ACEI)/angiotensin receptor blocker (ARB) for intensive care unit patients with renal dysfunction is associated with reduced in-hospital mortality. We conducted a retrospective analysis of critically ill patients who received early administration of an ACEI/ARB within 72 hours after being hospitalized. Patients were selected from the Medical Information Mart for Intensive Care IV database. We included 18,986 critically ill patients in our analysis. After propensity score matching, our final study cohort of 4974 patients consisted of patients who received early administration of an ACEI/ARB (n = 2487) and nonusers (n = 2487). Results of logistic regression showed that early administration of an ACEI/ARB was associated with reduced risk of in-hospital mortality (odds ratio, 0.64; 95% confidence interval, 0.53-0.77; P < .001) and intensive care unit death (odds ratio, 0.56; 95% confidence interval, 0.45-0.70; P < .001) when compared to nonusers. There was no meaningful interaction for early administration of an ACEI/ARB versus nonusers across estimated glomerular filtration rate in outcomes. Sensitivity analysis showed there was no difference in the outcomes between early administration of ACEI and that of ARB. In this study, we found that early administration of an ACEI/ARB was associated with a reduced risk of in-hospital adverse outcomes based on renal function among critically ill patients. There was no interaction between early administration of an ACEI/ARB and in-hospital adverse outcomes across estimated glomerular filtration rate.

Radiological lung sequelae, functional status and symptoms in older patients 3 and 6 months after hospitalization for COVID-19 pneumonia

The aim of our study was to assess the lung sequelae and clinical consequences 3 and 6 months after hospitalization for COVID-19 pneumonia in older patients. An observational study was conducted on 55 patients aged 65 years and older. Activities of daily living (ADL) and clinical frailty scale (CFS) were assessed at baseline and after 3 months. Both quantitative assessment at chest high-resolution computed tomography (CT) and semi-quantitative severity score (CTSS) were performed at baseline and after 3 and 6 months. Mean age: 82.3 ± 7.1 years. Male prevalence: 56.4%. After 6 months, ground-glass opacities (GGO) were still detectable in 22% of subjects, while consolidations were no longer appreciable. During follow-up, CTSS reached an overall median score of zero after 6 months. Fibrotic-like changes were found in 40% of subjects with an overall median score of 0 (0-5) points, being more prevalent in males. Patients reporting worsening ADL and CFS were 10.9% and 45.5%, respectively. They were associated with the burden of comorbidities, especially history of heart failure and chronic obstructive pulmonary disease at baseline. Amnesic disorders, exertional dyspnea, and fatigue were the most relevant symptoms reported. No association emerged between persistent or new-onset symptoms and evidence of fibrotic-like changes. The typical chest CT abnormalities of the COVID-19 pneumonia acute phase resolved in most of our older patients. Mild fibrotic-like changes persisted in less than half of the patients, especially males, without significantly affecting the functional status and frailty condition, which instead were more likely associated with pre-existing comorbidities.

Potential use of renin-angiotensin-aldosterone system inhibitors to reduce COVID-19 severity

SARS-CoV-2 infection and its clinical manifestations (COVID-19) quickly evolved to a pandemic and a global public health emergency. The limited effectivity of available treatments aimed at reducing virus replication and the lessons learned from other coronavirus infections (SARS-CoV-1 or NL63) that share the internalization process of SARS-CoV-2, led us to revisit the COVID-19 pathogenesis and potential treatments. Virus protein S binds to the angiotensin-converting enzyme 2 (ACE2) initiating the internalization process. Endosome formation removes ACE2 from the cellular membrane preventing its counter-regulative effect mediated by the metabolism of angiotensin II to angiotensin (1-7). Internalized virus-ACE2 complexes have been identified for these coronaviruses. SARS-CoV-2 presents the highest affinity for ACE2 and produces the most severe symptoms. Assuming ACE2 internalization is the trigger for COVID-19 pathogenesis, accumulation of angiotensin II can be viewed as the potential cause of symptoms. Angiotensin II is a strong vasoconstrictor, but has also important roles in hypertrophy, inflammation, remodeling, and apoptosis. Higher levels of ACE2 in the lungs explain the acute respiratory distress syndrome as primary symptoms. Most of the described findings and clinical manifestations of COVID-19, including increased interleukin levels, endothelial inflammation, hypercoagulability, myocarditis, dysgeusia, inflammatory neuropathies, epileptic seizures and memory disorders can be explained by excessive angiotensin II levels. Several meta-analyses have demonstrated that previous use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers were associated with better prognosis for COVID-19. Therefore, pragmatic trials to assess the potential therapeutic benefits of renin-angiotensin-aldosterone system inhibitors should be urgently promoted by health authorities to widen the therapeutic options for COVID-19.

Regulation of Epithelial Sodium Transport by SARS-CoV-2 Is Closely Related with Fibrinolytic System-Associated Proteins

Dyspnea and progressive hypoxemia are the main clinical features of patients with coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Pulmonary pathology shows diffuse alveolar damage with edema, hemorrhage, and the deposition of fibrinogens in the alveolar space, which are consistent with the Berlin Acute Respiratory Distress Syndrome Criteria. The epithelial sodium channel (ENaC) is a key channel protein in alveolar ion transport and the rate-limiting step for pulmonary edema fluid clearance, the dysregulation of which is associated with acute lung injury/acute respiratory distress syndrome. The main protein of the fibrinolysis system, plasmin, can bind to the furin site of γ-ENaC and induce it to an activation state, facilitating pulmonary fluid reabsorption. Intriguingly, the unique feature of SARS-CoV-2 from other β-coronaviruses is that the spike protein of the former has the same furin site (RRAR) with ENaC, suggesting that a potential competition exists between SARS-CoV-2 and ENaC for the cleavage by plasmin. Extensive pulmonary microthrombosis caused by disorders of the coagulation and fibrinolysis system has also been seen in COVID-19 patients. To some extent, high plasmin (ogen) is a common risk factor for SARS-CoV-2 infection since an increased cleavage by plasmin accelerates virus invasion. This review elaborates on the closely related relationship between SARS-CoV-2 and ENaC for fibrinolysis system-related proteins, aiming to clarify the regulation of ENaC under SARS-CoV-2 infection and provide a novel reference for the treatment of COVID-19 from the view of sodium transport regulation in the lung epithelium.

Development of a Risk Score for AKI onset in COVID-19 Patients: COV-AKI Score

PURPOSE

Acute Kidney Injury (AKI) in COVID-19 patients is associated with increased morbidity and mortality. In the present study, we aimed to develop a prognostic score to predict AKI development in these patients.

MATERIALS AND METHODS

This was a retrospective observational study of 2334 COVID 19 patients admitted to 23 different hospitals in Brazil, between January 10th and August 30rd, 2020. The primary outcome of AKI was defined as any increase in serum creatinine (SCr) by 0.3 mg/dL within 48 h or a change in SCr by ≥ 1.5 times of baseline within 1 week, based on Kidney Disease Improving Global Outcomes (KDIGO) guidelines. All patients aged ≥ 18 y/o admitted with confirmed SARS-COV-2 infection were included. Discrimination of variables was calculated by the Receiver Operator Characteristic Curve (ROC curve) utilizing area under curve. Some continuous variables were categorized through ROC curve. The cutoff points were calculated using the value with the best sensitivity and specificity.

RESULTS

A total of 1131 patients with COVID-19 admitted to the ICU were included. Patients mean age was 52 ± 15,8 y/o., with a prevalence of males 60% (n = 678). The risk of AKI was 33% (n = 376), 78% (n = 293) of which did not require dialysis. Overall mortality was 11% (n = 127), while for AKI patients, mortality rate was 21% (n = 80). Variables selected for the logistic regression model and inclusion in the final prognostic score were the following: age, diabetes, ACEis, ARBs, chronic kidney disease and hypertension.

CONCLUSION

AKI development in COVID 19 patients is accurately predicted by common clinical variables, allowing early interventions to attenuate the impact of AKI in these patients.

Hypertension and mortality in SARS-COV-2 infection: A meta-analysis of observational studies after 2 years of pandemic

BACKGROUND

The worldwide pandemic SARS-CoV-2 infection is associated with clinical course including a very broad spectrum of clinical manifestations, including death. Several studies and meta-analyses have evaluated the role of hypertension on prognosis, but with important limitations and conflicting results. Therefore, we decided to perform a new meta-analysis of the observational studies that explored the relationship between pre-existing hypertension and mortality risk in patients with SARS-CoV-2 infection, using more stringent inclusion criteria to overcome the limitations inherent previous meta-analyses.

METHODS

A systematic search of the on-line databases available up to 31 March 2022 was conducted, including peer-reviewed original articles, involving the adult population, where the role of hypertension on mortality due to SARS-CoV-2 infection was determined by Cox-proportional hazard models. Pooled hazard ratio (HR) was calculated by a random effect model. Sensitivity, heterogeneity, publication bias, subgroup and meta-regression analyses were performed.

RESULTS

Twenty-six studies (222,083 participants) met the pre-defined inclusion criteria. In the pooled analysis, pre-existing hypertension was significantly associated with mortality due to SARS-CoV-2 infection, both in unadjusted and adjusted models (HR: 1.55; 95% CI: 1.22 to 1.97). However, in separate analyses including results adjusted for crucial and strong predictors of mortality during SARS-CoV-2 infection (e.g. body weight), the association disappeared.

CONCLUSIONS

The results of this meta-analysis indicate that pre-existing hypertension is not an independent predictor of mortality during SARS-CoV-2 infection. Further studies should nevertheless be carried out worldwide to evaluate this role, independent of, or in interaction with, other confounders that may affect the mortality risk.

Sacubitril/valsartan alleviates sepsis-induced acute lung injury via inhibiting GSDMD-dependent macrophage pyroptosis in mice

Sepsis-induced acute lung injury (ALI) is a life-threatening disorder with intricate pathogenesis. Macrophage pyroptosis reportedly plays a vital role in ALI. Although it has been established that angiotensin receptor blockers (ARBs) can reduce sepsis-induced organ injury, the efficacy of sacubitril/valsartan (SV) for sepsis has been largely understudied. Here, we aimed to investigate the role of SV in sepsis-induced ALI. Caecal ligation and puncture (CLP) were used to induce polymicrobial sepsis and related ALI. The therapeutic effects of SV in CLP mice were subsequently assessed. Gasdermin D (GSDMD)^-/- mice were used to validate the signalling pathways affected by SV. In vitro, mouse bone marrow-derived macrophages (BMDMs) and Raw264.7 cells were treated with SV following exposure to lipopolysaccharide and adenosine triphosphate. Finally, the serum obtained from 42 septic patients was used for biochemical analysis. Compared to the other ARBs, SV yielded more pronounced anti-inflammatory effects on macrophages. In vivo, SV decreased mortality rates, significantly reduced lung damage and prevented the inflammatory response in CLP mice. In addition, SV suppressed GSDMD-mediated macrophage pyroptosis in mice. In BMDMs and Raw264.7 cells, the anti-inflammatory and anti-pyroptosis properties of SV were verified. SV treatment effectively inhibited NLRP3 inflammasome activation and prevented macrophage pyroptosis in a GSDMD-dependent manner. Furthermore, we found that septic individuals had considerably higher serum angiotensin II levels. Overall, we found that SV might prevent ALI in CLP mice by inhibiting GSDMD-mediated pyroptosis of macrophages. Thus, SV might be a viable drug for sepsis-induced ALI.

Diet-Induced Obesity and NASH Impair Disease Recovery in SARS-CoV-2-Infected Golden Hamsters

Obese patients with non-alcoholic steatohepatitis (NASH) are prone to severe forms of COVID-19. There is an urgent need for new treatments that lower the severity of COVID-19 in this vulnerable population. To better replicate the human context, we set up a diet-induced model of obesity associated with dyslipidemia and NASH in the golden hamster (known to be a relevant preclinical model of COVID-19). A 20-week, free-choice diet induces obesity, dyslipidemia, and NASH (liver inflammation and fibrosis) in golden hamsters. Obese NASH hamsters have higher blood and pulmonary levels of inflammatory cytokines. In the early stages of a SARS-CoV-2 infection, the lung viral load and inflammation levels were similar in lean hamsters and obese NASH hamsters. However, obese NASH hamsters showed worse recovery (i.e., less resolution of lung inflammation 10 days post-infection (dpi) and lower body weight recovery on dpi 25). Obese NASH hamsters also exhibited higher levels of pulmonary fibrosis on dpi 25. Unlike lean animals, obese NASH hamsters infected with SARS-CoV-2 presented long-lasting dyslipidemia and systemic inflammation. Relative to lean controls, obese NASH hamsters had lower serum levels of angiotensin-converting enzyme 2 activity and higher serum levels of angiotensin II—a component known to favor inflammation and fibrosis. Even though the SARS-CoV-2 infection resulted in early weight loss and incomplete body weight recovery, obese NASH hamsters showed sustained liver steatosis, inflammation, hepatocyte ballooning, and marked liver fibrosis on dpi 25. We conclude that diet-induced obesity and NASH impair disease recovery in SARS-CoV-2-infected hamsters. This model might be of value for characterizing the pathophysiologic mechanisms of COVID-19 and evaluating the efficacy of treatments for the severe forms of COVID-19 observed in obese patients with NASH.

Exploring extracellular vesicles as mediators of clinical disease and vehicles for viral therapeutics: Insights from the COVID-19 pandemic

The COVID-19 pandemic has challenged researchers to rapidly understand the capabilities of the SARS-CoV-2 virus and investigate potential therapeutics for SARS-CoV-2 infection. COVID-19 has been associated with devastating lung and cardiac injury, profound inflammation, and a heightened coagulopathic state, which may, in part, be driven by cellular crosstalk facilitated by extracellular vesicles (EVs). In recent years, EVs have emerged as important biomarkers of disease, and while extracellular vesicles may contribute to the spread of COVID-19 infection from one cell to the next, they also may be engineered to play a protective or therapeutic role as decoys or "delivery drivers" for therapeutic agents. This review explores these roles and areas for future study.

Discontinuing vs continuing ACEIs and ARBs in hospitalized patients with COVID-19 according to disease severity: Insights from the BRACE CORONA trial

BACKGROUND

We explored the effect of discontinuing versus continuing angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) on clinical outcomes in patients with COVID-19 according to baseline disease severity.

METHODS

We randomized 659 patients with a confirmed diagnosis of COVID-19 and classified them as having mild or moderate COVID-19 disease severity at hospital presentation using blood oxygen saturation and lung imaging. The primary outcome was the mean ratio of number of days alive and out of the hospital at 30 days according to disease severity.

RESULTS

At presentation, 376 patients (57.1%) had mild and 283 (42.9%) had moderate COVID-19. In patients with mild disease, there was no significant difference in the number of days alive and out of the hospital between ACEI/ARB discontinuation (mean 23.5 [SD 6.3] days) and continuation (mean 23.8 [SD 6.5] days), with a mean ratio of 0.98 (95% CI 0.92-1.04). However, in patients with moderate disease, there were fewer days alive and out of the hospital with ACEI/ARB discontinuation (mean 19.6 [SD 9.5] days) than continuation (mean 21.6 [SD 7.6] days), with a mean ratio of 0.90 (95% CI 0.81-1.00; P-interaction = .01). The impact of discontinuing versus continuing ACEIs/ARBs on days alive and out of hospital through 30 days differed according to baseline COVID-19 disease severity.

CONCLUSIONS

Unlike patients with mild disease, patients with moderate disease who continued ACEIs/ARBs had more days alive and out of hospital through 30 days than those who discontinued ACEIs/ARBs. This suggests that ACEIs/ARBs should be continued for patients with moderate COVID-19 disease severity.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov (NCT04364893).

Inhibition of the postsynaptic density protein 95 on the protective effect of Ang-(1-7)-Mas on cerebral ischaemia injury

BACKGROUND

Postsynaptic density protein-95 (PSD95) plays an important role in cerebral ischaemia injury, but its mechanism needs further research. This study aimed to explore the role of PSD95 in (Ang-(1-7))-Mas-mediated cerebral ischaemia protection and its regulatory mechanism.

METHODS

Oxygen-glucose deprivation (OGD) neuron and rat middle cerebral artery occlusion (MCAO) models were used as in vitro and in vivo models, respectively. TAT-MAS9C was used to disrupt the interaction between PSD95 and Mas. The recombinant PSD95 adenovirus (Ad-PSD95) was used to overexpress PSD95 in neurons.

RESULTS

Results showed that in OGD neurons, Ang-(1-7) could promote cell viability; reduce cell apoptosis; reduce the cell membrane localisation of Mas; upregulate the expression levels of pAKT, bcl-2 and I-κB; and downregulate the expression levels of Bax, pI-κB, tumour necrosis factor alpha and interleukin-1β. TAT-MAS9C could enhance the aforementioned effects of Ang-(1-7). However, the PSD95 overexpression inhibited the aforementioned effects of Ang-(1-7). In the MCAO rat model, the 2,3,5-triphenyltetrazolium chloride (TTC) staining showed that Ang-(1-7) reduced the infarct volume. The Morris water maze test showed that the number of crossings over the platform area in the Ang-(1-7) group was significantly increased. TAT-MAS9C could promote the protective effect of Ang-(1-7).

CONCLUSIONS

Results suggested that PSD95 alleviated the activation of AKT and the inhibition of nuclear factor kappa B signalling pathway mediated by the Ang-(1-7)-Mas complex, thereby reducing neuronal activity, increasing apoptosis and inhibiting the Ang-(1-7)-Mas-mediated cerebral ischaemia protection.

Extracellular Vesicles and Their Associated miRNAs as Potential Biomarkers in Intracranial Aneurysm

Intracranial aneurysms (IA) are abnormal expansions of the intracranial arteries. Once it ruptures, the mortality and disability rate are high. The cost of imaging examinations is high, and rupture risk cannot be predicted, making it difficult for high-risk groups to be screened and prevented. Thus, clinically effective biomarkers are required to screen high-risk groups, estimate the risk of rupture, and determine the appropriate early intervention step. This article introduces the current research and application of exosome-derived microRNA (miRNA) as biomarkers of intracranial aneurysms and their limitations, which can give researchers a general overview of the research in this field. It can also serve as a reference point for selecting related research directions.

Renin-Angiotensin-System Inhibitors Are Associated With Lower In-hospital Mortality in COVID-19 Patients Aged 80 and Older

Background

Older adults are at higher risk of morbidity and mortality for coronavirus disease 2019 (COVID-19). Renin-angiotensin-system inhibitors (RASi) were found to have a neutral or protective effect against mortality in COVID-19 adult patients.

Aims

We investigated whether this association was confirmed also in COVID-19 older patients.

Methods

This is a prospective observational study on 337 hospitalized older adults (aged 80 years and older). We classified the study population according to usage of RASi before and during hospitalization. A propensity score analysis was also performed to confirm the findings.

Results

The mean age was 87.4 ± 6.1 years. Patients taking RASi at home were 147 (43.6%). During hospitalization, 38 patients (11.3% of the entire study population) discontinued RASi, while 57 patients (16.9% of the entire study population) started RASi. In-hospital mortality was 43.9%. Patients taking RASi during hospitalization (patients who maintained their home RASi therapy + patients who started RASi during hospitalization) had a significantly lower in-hospital mortality than untreated patients [HR 0.48 (95% CI: 0.34–0.67)], even after adjustment for required respiratory support, functional status, albumin, inflammation, and cardiac biomarkers. The analysis of the groups derived from the “propensity score matching” (58 patients in each group) confirmed these results [HR 0.46 (95% CI: 0.23–0.91)].

Discussion

Despite the high risk of death in older COVID-19 patients, RASi therapy during hospitalization was associated with a clinically relevant lower in-hospital mortality, likely due to the benefit of RAS modulation on the cardiopulmonary system during the acute phase of the disease.

Conclusion

Our findings confirm the protective role of RASi even in COVID-19 patients aged 80 years and older.

Angiotensin-converting enzyme 2 (ACE2): Two decades of revelations and re-evaluation

Angiotensin-converting enzyme-2, or ACE2, is primarily a zinc-dependent peptidase and ectoenzyme expressed in numerous cell types and functioning as a counterbalance to ACE in the renin-angiotensin system. It was discovered 21 years ago more than 40 years after the discovery of ACE itself. Its primary physiological activity is believed to be in the conversion of angiotensin II to the vasodilatory angiotensin-(1-7) acting through the Mas receptor. As such it has been implicated in numerous pathological conditions, largely in a protective mode which has led to the search for ACE2 activatory mechanisms. ACE2 has a diverse substrate specificity allowing its participation in multiple peptide pathways. It also regulates aspects of amino acid transport through its homology with a membrane protein, collectrin. It also serves as a viral receptor for the SARS virus, and subsequently SARS-CoV2, driving the current COVID-19 pandemic. ACE2 therefore provides a therapeutic target for the treatment of COVID and understanding the biological events following viral binding can provide insight into the multiple pathologies caused by the virus, particularly inflammatory and vascular. In part this may relate to the ability of ACE2, like ACE, to be shed from the cell membrane. The shed form of ACE2 (sACE2) may be a factor in determining susceptibility to certain COVID pathologies. Hence, for just over 20 years, ACE2 has provided numerous surprises in the field of vasoactive peptides with, no doubt, more to come but it is its central role in COVID pathology that is producing the current intense interest in its biology.

Differential impact of the angiotensin‑converting enzyme‑2 (ACE2 rs4343 G>A) and miR‑196a2 rs11614913 C>T gene alterations in COVID‑19 disease severity and mortality

The recent coronavirus outbreak from Wuhan China in late 2019 caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) resulted in a global pandemic of coronavirus-19 disease (COVID-19). Understating the underlying mechanism of the pathogenesis of coronavirus infection is important not only because it will help in accurate diagnosis and treatment of the infection but also in the production of effective vaccines. The infection begins when SARS-CoV-2 enters the cells through binding of its envelope glycoprotein to angiotensin-converting enzyme2 (ACE2). Gene variations of ACE2 and microRNA (miR)-196 are associated with viral infection and other diseases. The present study investigated the association of the ACE2 rs4343 G>A and miR-196a2 rs11614913 C>T gene polymorphisms with severity and mortality of COVID-19 using amplification refractory mutation system PCR in 117 COVID-19 patients and 103 healthy controls from three regions of Saudi Arabia. The results showed that ACE2 rs4343 GA genotype was associated with severity of COVID-19 (OR=2.10, P-value 0.0028) and ACE2 rs4343 GA was associated with increased mortality with OR=3.44, P-value 0.0028. A strong correlation between the ACE2 rs4343 G>A genotype distribution among COVID-19 patients was reported with respect to their comorbid conditions including sex (P<0.023), coronary artery disease (P<0.0001), oxygen saturation <60 mm Hg (P<0.0009) and antiviral therapy (0.003). The results also showed that the CT genotype and T allele of the miR-196a2 rs11614913 C>T were associated with decreased risk to COVID-19 with OR=0.76, P=0.006 and OR=0.54, P=0.005, respectively. These results need to be validated with future molecular genetic studies in a larger sample size and different populations.

Possible harm from glucocorticoid drugs misuse in the early phase of SARS-CoV-2 infection: a narrative review of the evidence

Since the publication of the RECOVERY trial, the use of glucocorticoid drugs (GC) has spread for the treatment of severe COVID-19 worldwide. However, the benefit of dexamethasone was largest in patients who received mechanical ventilation or supplemental oxygen therapy, while no benefit was found among patients without hypoxemia. In addition, a positive outcome was found in patients who received dexamethasone after several days of symptoms, while possible harm could exist if administered early. The right time interval for GC administration is still a matter of debate. Previous studies showed that an early GC use during the first phase of the disease, when viral replication peaks, may negatively affect the innate immune response through several mechanisms, such as the inhibition of pro-inflammatory and antiviral cytokine production and signaling pathway, including type I interferon, that is fundamental to counteract the virus and that was found to be impaired in several patients with life-threatening COVID-19. The GC misuse can lead to a more severe disease even in patients who do not have the established risk factors, such as obesity and cardiovascular diseases. In our focused review, we describe the role of immune response in viral infections, especially SARS-CoV-2, and discuss the potential harms of GC misuse in COVID-19.

COVID-19 pathophysiology and ultrasound imaging: A multiorgan review

COVID-19 is a dynamic disease and may affect different tissues and organs as it progresses. Therefore, the impact generated by the disease in all its stages and organs requires a functional and versatile imaging technique able to detect particularities or artifacts dynamically. Ultrasonography fulfills all these requirements and exhibit several advantages relative to other imaging modalities, including portability, lower cost and biosafety. Throughout the COVID-19 pandemic, ultrasonography displayed a crucial role in the triage, monitoring, indicating organ damages and enabling individualized therapeutical decisions in COVID-19 patients. This review is dedicated to highlight the main pathological effects correlated with ultrasound changes caused by COVID-19 in the lungs, heart and liver.

Molecular and Physiological Aspects of SARS-CoV-2 Infection in Women and Pregnancy

Whilst scientific knowledge about SARS-CoV-2 and COVID-19 is rapidly increasing, much of the effects on pregnant women is still unknown. To accommodate pregnancy, the human endometrium must undergo a physiological transformation called decidualization. These changes encompass the remodeling of endometrial immune cells leading to immunotolerance of the semi-allogenic conceptus as well as defense against pathogens. The angiotensin converting enzyme 2 (ACE2) plays an important regulatory role in the renin-angiotensin-system (RAS) and has been shown to be protective against comorbidities known to worsen COVID-19 outcomes. Furthermore, ACE2 is also crucial for decidualization and thus for early gestation. An astounding gender difference has been found in COVID-19 with male patients presenting with more severe cases and higher mortality rates. This could be attributed to differences in sex chromosomes, hormone levels and behavior patterns. Despite profound changes in the female body during pregnancy, expectant mothers do not face worse outcomes compared with non-pregnant women. Whereas mother-to-child transmission through respiratory droplets during labor or in the postnatal period is known, another question of in utero transmission remains unanswered. Evidence of placental SARS-CoV-2 infection and expression of viral entry receptors at the maternal-fetal interface suggests the possibility of in utero transmission. SARS-CoV-2 can cause further harm through placental damage, maternal systemic inflammation, and hindered access to health care during the pandemic. More research on the effects of COVID-19 during early pregnancy as well as vaccination and treatment options for gravid patients is urgently needed.

Drugs Modulating Renin-Angiotensin System in COVID-19 Treatment

A massive worldwide vaccination campaign constitutes the main tool against the COVID-19 pandemic. However, drug treatments are also necessary. Antivirals are the most frequently considered treatments. However, strategies targeting mechanisms involved in disease aggravation may also be effective. A major role of the tissue renin-angiotensin system (RAS) in the pathophysiology and severity of COVID-19 has been suggested. The main link between RAS and COVID-19 is angiotensin-converting enzyme 2 (ACE2), a central RAS component and the primary binding site for SARS-CoV-2 that facilitates the virus entry into host cells. An initial suggestion that the susceptibility to infection and disease severity may be enhanced by angiotensin type-1 receptor blockers (ARBs) and ACE inhibitors (ACEIs) because they increase ACE2 levels, led to the consideration of discontinuing treatments in thousands of patients. More recent experimental and clinical data indicate that ACEIs and, particularly, ARBs can be beneficial for COVID-19 outcome, both by reducing inflammatory responses and by triggering mechanisms (such as ADAM17 inhibition) counteracting viral entry. Strategies directly activating RAS anti-inflammatory components such as soluble ACE2, Angiotensin 1-7 analogues, and Mas or AT2 receptor agonists may also be beneficial. However, while ACEIs and ARBs are cheap and widely used, the second type of strategies are currently under study.

Angiotensin Type-1 Receptor Inhibition Reduces NLRP3 Inflammasome Upregulation Induced by Aging and Neurodegeneration in the Substantia Nigra of Male Rodents and Primary Mesencephalic Cultures

The tissue renin–angiotensin system (RAS) has been shown to be involved in prooxidative and proinflammatory changes observed in aging and aging-related diseases such as dopaminergic degeneration in Parkinson’s disease (PD). We studied the activation of the NLRP3 inflammasome in the substantia nigra with aging and early stages of dopaminergic degeneration in PD models and, particularly, if the brain RAS, via its prooxidative proinflammatory angiotensin II (AngII) type 1 (AT1) receptors, mediates the inflammasome activation. Nigras from aged rats and mice and 6-hydroxydopamine PD models showed upregulation in transcription of inflammasome-related components (NLRP3, pro-IL1β and pro-IL18) and IL1β and IL18 protein levels, which was inhibited by the AT1 receptor antagonist candesartan. The role of the AngII/AT1 axis in inflammasome activation was further confirmed in rats intraventricularly injected with AngII, and in primary mesencephalic cultures treated with 6-hydroxydopamine, which showed inflammasome activation that was blocked by candesartan. Observations in the nigra of young and aged AT1 and AT2 knockout mice confirmed the major role of AT1 receptors in nigral inflammasome activation. In conclusion, the inflammasome is upregulated by aging and dopaminergic degeneration in the substantia nigra, possibly related with a decrease in dopamine levels, and it is mediated by the AngII/AT1 axis.

Sex differences in the lung ACE/ACE2 balance in hypertensive rats

The angiotensin-converting enzyme (ACE)/Angiotensin II (Ang II) and angiotensin-converting enzyme 2 (ACE2)/angiotensin-(1-7) (Ang-(1-7)) pathways are coexpressed in most tissues. The balance between these pathways determines, at least in part, whether tissue damage will occur in response to pathological stimuli. The present study tested the hypothesis that male sex and high blood pressure are associated with ACE/ACE2 imbalance in the lungs. Experiments were conducted in male and female Wistar rats and spontaneously hypertensive rats (SHRs). Lung ACE and ACE2 gene expression was also evaluated in normotensive and hypertensive humans using the Genotype-Tissue Expression (GTEx) project. Compared with Wistar rats and female SHRs, male SHRs displayed reduced lung ACE2 mRNA, ACE2 protein abundance and ACE2 activity, and increased Ang II concentration. Lung ACE mRNA levels were higher in male SHRs than in Wistar rats, whereas lung ACE protein abundance and activity were similar among the four groups of rats. Lung Ang-(1-7) concentration was higher in female than in male SHRs (89 ± 17 vs. 43 ± 2 pg/g, P<0.05). Lung ACE to ACE2 mRNA expression in hypertensive patients was significantly higher than that in normotensive subjects. Taken together, these results demonstrate that male hypertensive rats display imbalance between the ACE/Ang II and ACE2/Ang-(1-7) pathways in the lungs mainly attributable to ACE2 down-regulation. Further studies should be conducted to investigate whether this imbalance between ACE/ACE2 may promote and accelerate lung injury in respiratory infections, including coronavirus disease 2019 (COVID-19).

The Identikit of Patient at Risk for Severe COVID-19 and Death: The Dysregulation of Renin-Angiotensin System as the Common Theme

Since the first months of the coronavirus disease 2019 (COVID-19) pandemic, several specific physiologic traits, such as male sex and older age, or health conditions, such as overweight/obesity, arterial hypertension, metabolic syndrome, and type 2 diabetes mellitus, have been found to be highly prevalent and associated with increased risk of adverse outcomes in hospitalized patients. All these cardiovascular morbidities are widespread in the population and often coexist, thus identifying a common patient phenotype, characterized by a hyper-activation of the "classic" renin-angiotensin system (RAS) and mediated by the binding of angiotensin II (Ang II) to the type 1-receptor. At the same time, the RAS imbalance was proved to be crucial in the genesis of lung injury after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, where angiotensin-converting-enzyme-2 (ACE2) is not only the receptor for SARS-CoV-2, but its down-regulation through internalization and shedding, caused by the virus binding, leads to a further dysregulation of RAS by reducing angiotensin 1-7 (Ang 1-7) production. This focused narrative review will discuss the main available evidence on the role played by cardiovascular and metabolic conditions in severe COVID-19, providing a possible pathophysiological link based on the disequilibrium between the two opposite arms of RAS.

Presenting Characteristics, Comorbidities, and Outcomes Among Patients With COVID-19 Hospitalized in Pakistan: Retrospective Observational Study

BACKGROUND

COVID-19 became a pandemic rapidly after its emergence in December 2019. It belongs to the coronavirus family of viruses, which have struck a few times before in history. Data based on previous research regarding etiology and epidemiology of other viruses from this family helped played a vital role in formulating prevention and precaution strategies during the initial stages of this pandemic. Data related to COVID-19 in Pakistan were not initially documented on a large scale. In addition, due to a weak health care system and low economic conditions, Pakistan's population, in general, already suffers from many comorbidities, which can severely affect the outcome of patients infected with COVID-19.

OBJECTIVE

COVID-19 infections are coupled with a manifestation of various notable outcomes that can be documented and characterized clinically. The aim of this study was to examine these clinical manifestations, which can serve as indicators for early detection as well as severity prognosis for COVID-19 infections, especially in high-risk groups.

METHODS

A retrospective observational study involving abstraction of demographic features, presenting symptoms, and adverse clinical outcomes for 1812 patients with COVID-19 was conducted. Patients were admitted to the four major hospitals in the Rawalpindi-Islamabad region of Pakistan, and the study was conducted from February to August 2020. Multivariate regression analysis was carried out to identify significant indicators of COVID-19 severity, intensive care unit (ICU) admission, ventilator aid, and mortality. The study not only relates COVID-19 infection with comorbidities, but also examines other related factors, such as age and gender.

RESULTS

This study identified fever (1592/1812, 87.9%), cough (1433/1812, 79.1%), and shortness of breath (998/1812, 55.1%) at the time of hospital admission as the most prevalent symptoms for patients with COVID-19. These symptoms were common but not conclusive of the outcome of infection. Out of 1812 patients, 24.4% (n=443) required ICU admission and 21.5% (n=390) required ventilator aid at some point of disease progression during their stay at the hospital; 25.9% (n=469) of the patients died. Further analysis revealed the relationship of the presented symptoms and comorbidities with the progression of disease severity in these patients. Older adult patients with comorbidities, such as hypertension, diabetes, chronic kidney disease, and asthma, were significantly affected in higher proportions, resulting in requirement of ICU admission and ventilator aid in some cases and, in many cases, even mortality.

CONCLUSIONS

Older adult patients with comorbidities, such as hypertension, diabetes, asthma, chronic obstructive pulmonary disorder, and chronic kidney disease, are at increased risk of developing severe COVID-19 infections, with an increased likelihood of adverse clinical outcomes.

Cirrhosis-Associated RAS-Inflammation-Coagulation Axis Anomalies: Parallels to Severe COVID-19

(1) Background: Cirrhotic patients have an increased risk for severe COVID-19. We investigated the renin-angiotensin-aldosterone system (RAS), parameters of endothelial dysfunction, inflammation, and coagulation/fibrinolysis in cirrhotic patients and in COVID-19 patients. (2) Methods: 127 prospectively characterized cirrhotic patients (CIRR), along with nine patients with mild COVID-19 (mild-COVID), 11 patients with COVID-19 acute respiratory distress syndrome (ARDS; ARDS-COVID), and 10 healthy subjects (HS) were included in the study. Portal hypertension (PH) in cirrhotic patients was characterized by hepatic venous pressure gradient (HVPG). (3) Results: With increased liver disease severity (Child−Pugh stage A vs. B vs. C) and compared to HS, CIRR patients exhibited higher RAS activity (angiotensin-converting enzyme (ACE), renin, aldosterone), endothelial dysfunction (von Willebrand-factor (VWF) antigen), inflammation (C-reactive protein (CRP), interleukin-6 (IL-6)), and a disturbed coagulation/fibrinolysis profile (prothrombin fragment F1,2, D-dimer, plasminogen activity, antiplasmin activity). Increased RAS activity (renin), endothelial dysfunction (vWF), coagulation parameters (D-dimer, prothrombin fragment F1,2) and inflammation (CRP, IL-6) were significantly altered in COVID patients and followed similar trends from mild-COVID to ARDS-COVID. In CIRR patients, ACE activity was linked to IL-6 (ρ = 0.26; p = 0.003), independently correlated with VWF antigen (aB: 0.10; p = 0.001), and was inversely associated with prothrombin fragment F1,2 (aB: −0.03; p = 0.023) and antiplasmin activity (aB: −0.58; p = 0.006), after adjusting for liver disease severity. (4) Conclusions: The considerable upregulation of the RAS in Child−Pugh B/C cirrhosis is linked to systemic inflammation, endothelial dysfunction, and abnormal coagulation profile. The cirrhosis-associated abnormalities of ACE, IL-6, VWF antigen, and antiplasmin parallel those observed in severe COVID-19.

Upregulated miR-200c is associated with downregulation of the functional receptor for severe acute respiratory syndrome coronavirus 2 ACE2 in individuals with obesity

Obesity is a risk factor for coronavirus disease 2019 (COVID-19) infection, with studies demonstrating the prevalence of individuals with obesity admitted with COVID-19 ranging between 30 and 60%. We determined whether early changes in microRNAs (miRNAs) are associated with dysregulation of angiotensin-converting enzyme 2 (ACE2), the specific functional receptor for severe acute respiratory syndrome coronavirus 2. ACE2 is a membrane-bound enzyme that catalyzes the conversion of angiotensin II to angiotensin 1–7 the latter having cardioprotective and vasorelaxation effects. Quantitative real-time PCR analysis of plasma samples for circulating miRNAs showed upregulation of miR-200c and miR-let-7b in otherwise healthy individuals with obesity. This was associated with significant downregulation of ACE2, a direct target for both miRNAs, in individuals with obesity. Correlation analysis confirmed a significant negative correlation between ACE2 and both the miRNAs. Studies showed that despite being the functional receptor, inhibition/downregulation of ACE2 did not reduce the severity of COVID-19 infection. In contrast, increased angiotensin II following inhibition of ACE2 may increase the severity of the disease. Taken together, our novel results identify that upregulation of miR-200c may increase the susceptibility of individuals with obesity to COVID-19. Considering miRNA are the earliest molecular regulators, the level of circulating miR-200c could be a potential biomarker in the early identification of those at the risk of severe COVID-19.

SARS-CoV-2 infection: Understanding the immune system abnormalities to get an adequate diagnosis

COVID-19 is the current pandemic caused by the novel coronavirus, SARS-CoV-2, that emerged from China at the end of December 2019. The scientific community is making extraordinary efforts to understand the virus structure and the pathophysiology and immunological processes activated in the host, in order to identify biomarkers, diagnostic tools, treatments, and vaccines to decrease COVID-19 incidence and mortality. Various abnormalities have been noted during SARS-CoV-2 infection both in lymphoid and myeloid cells. Such abnormalities may disturb the immune system function and cause a massive inflammatory response that impairs tissue function. This review discusses the close relationship between the immune system abnormalities and the broad spectrum of clinical manifestations, including fibrosis, in the context of COVID-19 disease. Moreover, we described the current strategies for COVID-19 diagnosis, and we provide a summary of the most useful clinical laboratory parameters to identify severe COVID-19 patients.

NADPH-Oxidase, Rho-Kinase and Autophagy Mediate the (Pro)renin-Induced Pro-Inflammatory Microglial Response and Enhancement of Dopaminergic Neuron Death

Dysregulation of the tissue renin–angiotensin system (RAS) is involved in tissue oxidative and inflammatory responses. Among RAS components, renin, its precursor (pro)renin and its specific receptor (PRR) have been less investigated, particularly in the brain. We previously showed the presence of PRR in neurons and glial cells in the nigrostriatal system of rodents and primates, including humans. Now, we used rat and mouse models and cultures of BV2 and primary microglial cells to study the role of PRR in microglial pro-inflammatory responses. PRR was upregulated in the nigral region, particularly in microglia during the neuroinflammatory response. In the presence of the angiotensin type-1 receptor blocker losartan, to exclude angiotensin-related effects, treatment of microglial cells with (pro)renin induces the expression of microglial pro-inflammatory markers, which is mediated by upregulation of NADPH-oxidase and Rho-kinase activities, downregulation of autophagy and upregulation of inflammasome activity. Conditioned medium from (pro)renin-treated microglia increased dopaminergic cell death relative to medium from non-treated microglia. However, these effects were blocked by pre-treatment of microglia with the Rho-kinase inhibitor fasudil. Activation of microglial PRR enhances the microglial pro-inflammatory response and deleterious effects of microglia on dopaminergic cells, and microglial NADPH-oxidase, Rho-Kinase and autophagy are involved in this process.

Classical and Counter-Regulatory Renin-Angiotensin System: Potential Key Roles in COVID-19 Pathophysiology

In the current COVID-19 pandemic, severe acute respiratory syndrome coronavirus 2 uses angiotensin-converting enzyme-2 (ACE-2) receptors for cell entry, leading to ACE-2 dysfunction and downregulation, which disturb the balance between the classical and counter-regulatory renin-angiotensin system (RAS) in favor of the classical RAS. RAS dysregulation is one of the major characteristics of several cardiovascular diseases; thus, adjustment of this system is the main therapeutic target. RAS inhibitors-particularly angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II type 1 receptor blockers (ARBs)-are commonly used for treatment of hypertension and cardiovascular disease. Patients with cardiovascular diseases are the group most commonly seen among those with COVID-19 comorbidity. At the beginning of this pandemic, a dilemma occurred regarding the use of ACEIs and ARBs, potentially aggravating cardiovascular and pulmonary dysfunction in COVID-19 patients. Urgent clinical trials from different countries and hospitals reported that there is no association between RAS inhibitor treatment and COVID-19 infection or comorbidity complication. Nevertheless, the disturbance of the RAS that is associated with COVID-19 infection and the potential treatment targeting this area have yet to be resolved. In this review, the link between the dysregulation of classical RAS and counter-regulatory RAS activities in COVID-19 patients with cardiovascular metabolic diseases is investigated. In addition, the latest findings based on ACEI and ARB administration and ACE-2 availability in relation to COVID-19, which may provide a better understanding of the RAS contribution to COVID-19 pathology, are discussed, as they are of the utmost importance amid the current pandemic.

Expression of SARS-CoV-2 Entry Factors in Human Alveolar Type II Cells in Aging and Emphysema

Alveolar type II (ATII) cells proliferate and restore the injured epithelium. It has been described that SARS-CoV-2 infection causes diffuse alveolar damage in the lungs. However, host factors facilitating virus infection in ATII cells are not well known. We determined the SARS-CoV-2-related genes and protein expression using RT-PCR and Western blotting, respectively, in ATII cells isolated from young and elderly non-smokers, smokers, and ex-smokers. Cells were also obtained from lung transplants of emphysema patients. ACE2 has been identified as the receptor for SARS-CoV-2, and we found significantly increased levels in young and elderly smokers and emphysema patients. The viral entry depends on TMPRSS2 protease activity, and a higher expression was detected in elderly smokers and ex-smokers and emphysema patients. Both ACE2 and TMPRSS2 mRNA levels were higher in this disease in comparison with non-smokers. CD209L serves as a receptor for SARS-CoV-2, and we found increased levels in ATII cells obtained from smokers and in emphysema patients. Also, our data suggest CD209L regulation by miR142. Endoplasmic reticulum stress was detected in ATII cells in this disease. Our results suggest that upregulation of SARS-CoV-2 entry factors in ATII cells in aging, smokers, and emphysema patients may facilitate infection.

The Number of Pills, Rather Than the Type of Renin-Angiotensin System Inhibitor, Predicts Ambulatory Blood Pressure Control in Essential Hypertensives on Triple Therapy: A Real-Life Cross-Sectional Study

Introduction

We evaluated the prevalence and predictors of ambulatory blood pressure (BP) control in patients taking a triple antihypertensive therapy (renin–angiotensin system inhibitor + calcium channel blocker + thiazide/thiazide-like diuretic, in either free or fixed-dose combinations) containing an angiotensin-converting enzyme inhibitor (ACEi) or an angiotensin receptor blocker (ARB).

Methods

We performed an observational cross-sectional study on 520 consecutive patients with essential hypertension taking a stable triple therapy in whom 24-h ambulatory BP was evaluated. Both number of pills and antihypertensive treatment intensity (ATI), as possible pharmacological predictors of ambulatory BP control, were taken into account.

Results

A total of 189 (36.3%) patients were taking triple therapy with ACEi and 331 (63.7%) patients were taking triple therapy with ARB. Mean age was 62.7 ± 12.2 years. Patients on triple therapy with ACEi had a significantly lower ATI and took fewer antihypertensive pills than patients on triple therapy with ARB (22.2% of patients took a single-pill triple fixed-dose combination). Patients taking triple therapy with ACEi had higher prevalence of both 24-h (54.8% vs 44.0%; p = 0.019) and daytime BP control (61.8% vs 49.2%; p = 0.006) than patients taking triple therapy with ARB, even after adjusting for age, sex, body mass index, smoking habit, type 2 diabetes mellitus, estimated glomerular filtration rate, and ATI [OR 1.5 (95% CI 1.1–2.2) and OR 1.6 (95% CI 1.1–2.4), respectively]. However, these independent associations with ambulatory BP control were lost when the number of antihypertensive pills was included in the model.

Conclusion

The higher prevalence of ambulatory BP control found in patients taking a triple therapy with ACEi was affected by the lower number of antihypertensive pills taken, which was also the key predictor of ambulatory BP control in our study. This confirms the importance of fixed-dose combinations in the management of essential hypertension.

The effect of estrogen in coronavirus disease 2019

The outcomes of coronavirus disease 2019 (COVID-19) vary between men and women. Some statistical reports have shown that men have a higher risk of developing COVID-19 and suffer from worse outcomes than females. Although there are many factors that can explain the high prevalence of COVID-19 in men, such as lifestyle habits and the different profile of comorbidities among sexes, the distinctions between male and female immune systems cannot be ignored. It has been sufficiently shown that sex differences have a critical influence on the shaping of immune response, which then leads to different pathogenesis in infectious diseases. Compared with males, females typically have a more effective innate and adaptive immune response to viral infections in COVID-19. What's more, there is a growing body of evidence showing that estrogen exerts an effect on the regulation of immune response. This article examines the effect and mechanism of estrogen on COVID-19.

ACE2 Down-Regulation May Act as a Transient Molecular Disease Causing RAAS Dysregulation and Tissue Damage in the Microcirculatory Environment Among COVID-19 Patients

Severe acute respiratory syndrome coronavirus 2, the etiologic agent of coronavirus disease 2019 (COVID-19) and the cause of the current pandemic, produces multiform manifestations throughout the body, causing indiscriminate damage to multiple organ systems, particularly the lungs, heart, brain, kidney, and vasculature. The aim of this review is to provide a new assessment of the data already available for COVID-19, exploring it as a transient molecular disease that causes negative regulation of angiotensin-converting enzyme 2, and consequently, deregulates the renin-angiotensin-aldosterone system, promoting important changes in the microcirculatory environment. Another goal of the article is to show how these microcirculatory changes may be responsible for the wide variety of injury mechanisms observed in different organs in this disease. The new concept of COVID-19 provides a unifying pathophysiological picture of this infection and offers fresh insights for a rational treatment strategy to combat this ongoing pandemic.

Discontinuation of Antihypertensive Medications on the Outcome of Hospitalized Patients With Severe Acute Respiratory Syndrome-Coronavirus 2

Supplemental Digital Content is available in the text.

RAASi (renin-angiotensin-aldosterone system inhibitors) are suggested as possible treatment option in the early phase of severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) infection. A meta-analysis investigating the possible detrimental effects of RAASi on the severity of (SARS-CoV-2) infection showed that ambulatory use of RAASi, by hospitalized patients, has a neutral effect. It is, however, conceivable that this observation is biased by the fact that antihypertensive medications, are often discontinued at or during admission in hospitalized patients with SARS-CoV-2. We, therefore, investigated the effect of discontinuation of antihypertensive medications, in hospitalized patients with SARS-CoV-2. We performed a retrospective observational study on 1584 hospitalized patients with SARS-CoV-2 from 10 participating hospitals in the Netherlands. Differences in the outcome (severity of disease or death) between the groups in which medications were either continued or discontinued during the course of hospitalization were assessed using logistic regression models. Discontinuation of angiotensin receptor blockers, ACE (angiotensin-converting enzyme) inhibitors and β-blockers, even when corrected for sex, age, and severity of symptoms during admission, resulted in a 2 to 4× higher risk of dying from SARS-CoV-2 infection (odds ratio [95% CI]); angiotensin receptor blockers 2.65 [1.17–6.04], ACE inhibitor (2.28 [1.15–4.54]), and β-blocker (3.60 [1.10–10.27]). In conclusion, discontinuation of at-home ACE inhibitor, angiotensin receptor blockers, or β-blocker in patients hospitalized for a SARS-CoV-2 infection was associated with an increased risk of dying, whereas discontinuation of calcium channel blockers and diuretics was not.

Hypertension delays viral clearance and exacerbates airway hyperinflammation in patients with COVID-19

In coronavirus disease 2019 (COVID-19), hypertension and cardiovascular diseases are major risk factors for critical disease progression. However, the underlying causes and the effects of the main anti-hypertensive therapies-angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs)-remain unclear. Combining clinical data (n = 144) and single-cell sequencing data of airway samples (n = 48) with in vitro experiments, we observed a distinct inflammatory predisposition of immune cells in patients with hypertension that correlated with critical COVID-19 progression. ACEI treatment was associated with dampened COVID-19-related hyperinflammation and with increased cell intrinsic antiviral responses, whereas ARB treatment related to enhanced epithelial-immune cell interactions. Macrophages and neutrophils of patients with hypertension, in particular under ARB treatment, exhibited higher expression of the pro-inflammatory cytokines CCL3 and CCL4 and the chemokine receptor CCR1. Although the limited size of our cohort does not allow us to establish clinical efficacy, our data suggest that the clinical benefits of ACEI treatment in patients with COVID-19 who have hypertension warrant further investigation.

Hepatocrinology

Hepatocrinology is defined as a bidirectional, complex relationship between hepatic physiology and endocrine function, hepatic disease and endocrine dysfunction, hepatotropic drugs and endocrine function, and endocrine drugs and hepatic health. The scope of hepatocrinology includes conditions of varied etiology (metabolic, infectious, autoimmune, and invasive) that we term as hepato-endocrine syndromes. This perspective shares the definition, concept, and scope of hepatocrinology and shares insight related to this aspect of medicine. It is hoped that this communication will encourage further attention and research in this critical field.

Angiotensin Receptor Blockers Are Not Just for Hypertension Anymore

Beyond blood pressure control, angiotensin receptor blockers reduce common injury mechanisms, decreasing excessive inflammation and protecting endothelial and mitochondrial function, insulin sensitivity, the coagulation cascade, immune responses, cerebrovascular flow, and cognition, properties useful to treat inflammatory, age-related, neurodegenerative, and metabolic disorders of many organs including brain and lung.

Acute and chronic exposure to air pollution in relation with incidence, prevalence, severity and mortality of COVID-19: a rapid systematic review

BACKGROUND

Air pollution is one of the world's leading mortality risk factors contributing to seven million deaths annually. COVID-19 pandemic has claimed about one million deaths in less than a year. However, it is unclear whether exposure to acute and chronic air pollution influences the COVID-19 epidemiologic curve.

METHODS

We searched for relevant studies listed in six electronic databases between December 2019 and September 2020. We applied no language or publication status limits. Studies presented as original articles, studies that assessed risk, incidence, prevalence, or lethality of COVID-19 in relation with exposure to either short-term or long-term exposure to ambient air pollution were included. All patients regardless of age, sex and location diagnosed as having COVID-19 of any severity were taken into consideration. We synthesised results using harvest plots based on effect direction.

RESULTS

Included studies were cross-sectional (n = 10), retrospective cohorts (n = 9), ecological (n = 6 of which two were time-series) and hypothesis (n = 1). Of these studies, 52 and 48% assessed the effect of short-term and long-term pollutant exposure, respectively and one evaluated both. Pollutants mostly studied were PM2.5 (64%), NO2 (50%), PM10 (43%) and O3 (29%) for acute effects and PM2.5 (85%), NO2 (39%) and O3 (23%) then PM10 (15%) for chronic effects. Most assessed COVID-19 outcomes were incidence and mortality rate. Acutely, pollutants independently associated with COVID-19 incidence and mortality were first PM2.5 then PM10, NO2 and O3 (only for incident cases). Chronically, similar relationships were found for PM2.5 and NO2. High overall risk of bias judgments (86 and 39% in short-term and long-term exposure studies, respectively) was predominantly due to a failure to adjust aggregated data for important confounders, and to a lesser extent because of a lack of comparative analysis.

CONCLUSION

The body of evidence indicates that both acute and chronic exposure to air pollution can affect COVID-19 epidemiology. The evidence is unclear for acute exposure due to a higher level of bias in existing studies as compared to moderate evidence with chronic exposure. Public health interventions that help minimize anthropogenic pollutant source and socio-economic injustice/disparities may reduce the planetary threat posed by both COVID-19 and air pollution pandemics.

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.

Mechanisms and Potential Roles of Glucose-Lowering Agents in COVID-19: A Review

OBJECTIVE

To explore mechanistic benefits of glucose-lowering agents that extend beyond glycemic control with the potential to mitigate coronavirus disease 2019 (COVID-19) complications.

DATA SOURCES

The following PubMed literature search terms were used from July 2020 to January 2, 2021: diabetes, COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), glucose-lowering agents, and pharmacology.

STUDY SELECTION AND DATA EXTRACTION

English-language studies reporting on the association between diabetes, COVID-19 adverse outcomes, and the potential roles of glucose-lowering agents were reviewed.

DATA SYNTHESIS

Selected glucose-lowering agents have benefits beyond glycemic control, with the potential to reduce the risks of severe complications during SARS-CoV-2 infection. Key benefits include anti-inflammatory, anticoagulant, immune modulating, and enzyme/receptor effects.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review summarizes the current knowledge of glucose-lowering agents and their potential roles in COVID-19 outcomes. Considering beneficial mechanisms on COVID-19 outcomes that extend beyond glycemic control as well as safety profiles, current data suggest that dipeptidyl peptidase-IV (DPP-IV) inhibitors and metformin may have the most promise and warrant further investigation.

CONCLUSIONS

Certain glucose-lowering agents may offer additional benefits beyond glucose control-namely, by modulating the mechanisms contributing to adverse outcomes related to COVID-19 in patients with diabetes. DPP-IV inhibitors and metformin appear to have the most promise. However, current published literature on diabetes medications and COVID-19 should be interpreted with caution. Most published studies are retrospective and consist of convenience samples, and some lack adequate analytical approaches with confounding biases. Ongoing trials aim to evaluate the effects of glucose-lowering agents in reducing the severity of COVID-19 outcomes.