The evolving role of the renin-angiotensin system in ARDS

Evaluation of angiotensin converting enzyme 2 (ACE2), angiotensin II (Ang II), miR-141-3p, and miR-421 levels in SARS-CoV-2 patients: a case-control study

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly contagious virus that uses angiotensin converting enzyme 2 (ACE2), a pivotal member of the renin-angiotensin system (RAS), as its cell-entry receptor. Another member of the RAS, angiotensin II (Ang II), is the major biologically active component in this system. There is growing evidence suggesting that serum miRNAs could serve as prognostic biomarkers for SARS-CoV-2 infection and regulate ACE2 expression. Therefore, the aim of this study is to evaluate the changes in the serum levels of sACE2 and Ang II, as well as the expression level of miR-141-3p and miR-421 in SARS-CoV-2 positive and negative subjects.

METHODS

In the present study, the serum levels of sACE2 and Ang II were measured in 94 SARS-CoV-2 positive patients and 94 SARS-CoV-2 negative subjects with some symptoms similar to those of SARS-CoV-2 positive patients using the ELISA method. In addition, the expression level of miR-141-3p and miR-421 as ACE2 regulators and biomarkers was evaluated using quantitative real-time PCR (qRT-PCR) method.

RESULTS

The mean serum sACE2 concentration in the SARS-CoV-2-positive group was 3.268 ± 0.410 ng/ml, whereas in the SARS-CoV-2 negative group, it was 3.564 ± 0.437 ng/ml. Additionally, the mean serum Ang II level in the SARS-CoV-2 positive and negative groups were 60.67 ± 6.192 ng/L and 67.97 ± 6.837 ng/L, respectively. However, there was no significant difference in the serum levels of sACE2 (P value: 0.516) and Ang II (P value: 0.134) between the SARS-CoV-2 positive and negative groups. Meanwhile, our findings indicated that the expression levels of miR-141-3p and miR-421 in SARS-CoV-2 positive group were significantly lower and higher than SARS-CoV-2 negative group, respectively (P value < 0.001).

CONCLUSIONS

Taken together, the results of this study showed that the serum levels of sACE2 and Ang II in SARS-CoV-2 positive and negative subjects were not significantly different, but the expression levels of miR-141-3p and miR-421 were altered in SARS-CoV-2 positive patients which need more investigation to be used as biomarkers for COVID-19 diagnosis.

Association between angiotensinogen (AGT), angiotensin-converting enzyme (ACE) and angiotensin-II receptor 1 (AGTR1) polymorphisms and COVID-19 infection in the southeast of Iran: a preliminary case-control study

BACKGROUND

The COVID-19 pandemic remains an emerging public health crisis with serious adverse effects. The disease is caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV--2) infection, targeting angiotensin-converting enzyme-2 (ACE2) receptor for cell entry. However, changes in the renin-angiotensin system (RAS) balance alter an individual's susceptibility to COVID-19 infection. We aimed to evaluate the association between AGT rs699 C > T, ACE rs4646994 I/D, and AGTR1 rs5186 C > A variants and the risk of COVID-19 infection and the severity in a sample of the southeast Iranian population.

METHODS

A total of 504 subjects, including 258 COVID-19 positives, and 246 healthy controls, were recruited. Genotyping of the ACE gene rs4646994, and AGT rs699, and AGTR1 rs5186 polymorphisms was performed by polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (PCR-RFLP), respectively.

RESULTS

Our results showed that the II genotype of ACE rs4646994 and the I allele decreased the risk of COVID-19 infection. Moreover, we found that the TC genotype and C allele of AGT rs699 increased the risk of COVID-19 infection. The AGTR1 rs5186 was not associated with COVID-19 infection. Also, we did not find any association between these polymorphisms and the severity of the disease. However, we found a significantly higher age and prevalence of diabetes and hypertension in patients with severe disease than a non-severe disease.

CONCLUSIONS

These findings suggest that ACE rs4646994 and AGT rs699 polymorphisms increase the risk of COVID-19 infection in a southeast Iranian population.

Renin angiotensin aldosterone system in pulmonary fibrosis: Pathogenesis to therapeutic possibilities

Pulmonary fibrosis is a devastating lung disease with multifactorial etiology characterized by alveolar injury, fibroblast proliferation and excessive deposition of extracellular matrix proteins, which progressively results in respiratory failure and death. Accumulating evidence from experimental and clinical studies supports a central role of the renin angiotensin aldosterone system (RAAS) in the pathogenesis and progression of idiopathic pulmonary fibrosis. Angiotensin II (Ang II), a key vasoactive peptide of the RAAS mediates pro-inflammatory and pro-fibrotic effects on the lungs, adversely affecting organ function. Recent years have witnessed seminal discoveries in the field of RAAS. Identification of new enzymes, peptides and receptors has led to the development of several novel concepts. Of particular interest is the establishment of a protective axis of the RAAS comprising of Angiotensin converting enzyme 2 (ACE2), Angiotensin-(1-7) [Ang-(1-7)], and the Mas receptor (the ACE2/Ang-(1-7)/Mas axis), and the discovery of a functional role for the Angiotensin type 2 (AT₂) receptor. Herein, we will review our current understanding of the role of RAAS in lung fibrogenesis, provide evidence on the anti-fibrotic actions of the newly recognized RAAS components (the ACE2/Ang-(1-7)/Mas axis and AT₂ receptor), discuss potential strategies and translational efforts to convert this new knowledge into effective therapeutics for PF.

Protective Role of Angiotensin II Type 1 Receptor Blocker on Short Time Effect of Oleic Acid Induced Lung and Kidney Injury

Backgrounds:

Acute respiratory distress syndrome (ARDS) causes high mortality rate in clinic, and the pathogenesis of this syndrome may interact with renin angiotensin system (RAS) components. The main objective of this study was to determine the protective role of AT1R antagonist (losartan) on oleic acid (OA) induced ARDS and kidney injury.

Methods:

The animal model of ARDS was performed by intravenous administration of 250 μl/kg oleic acid (OA). Male and female rats were subjected to received intravenously vehicle (saline, groups 1 and 4), OA (groups 2 and 5), or losartan (10 mg/kg) plus OA (groups 3 and 6), and six hour later, the measurements were performed.

Results:

Co-treatment of OA and losartan increased the serum levels of blood urea nitrogen significantly (P < 0.05) and creatinine insignificantly in both gender. However, the OA induced kidney damage was decreased by losartan significantly in male (P < 0.05) and insignificantly in female rats. In addition, co-treatment of OA and losartan decreased lung water content significantly in male rats (P < 0.05). Based on tissue staining, no significant difference in lung tissue damages were observed between the groups, however some exudate were observed in lung male rats treated with OA alone which were abolished by losartan.

Conclusions:

Losartan may protect the kidney and lung against OA induced tissue injury in male rats. This protective action is not certain in female rats.

Anti-inflammatory drugs and the renin-angiotensin-aldosterone system: Current knowledge and potential effects on early SARS-CoV-2 infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiologic agent of coronavirus disease 19 (COVID-19), and is genetically related to the 2003 SARS and Middle East respiratory syndrome (MERS-CoV) coronaviruses. Recent studies have reported that similar to SARS-CoV, this strain expresses a spike protein (S) with a receptor binding domain (RBD) that binds to angiotensin-converting enzyme 2 (ACE2) - an enzyme expressed mostly in the endothelium, kidneys, heart, gastrointestinal tract and lungs - to facilitate viral entry and intracellular replication. Incidentally, the renin-angiotensin-aldosterone system (RAAS) is integral to physiologic control of both ACE and ACE2 expression, and is an essential system utilized by SARS-CoV-2, albeit with varying schools of thought on how it can affect viral entry. In this paper, we will review current knowledge on the RAAS and how it can be affected by non-steroidal anti-inflammatory drugs (NSAIDs) and corticosteroid use at the organ and cellular levels. We will then discuss the relevance of these interactions on organ-specific ACE2 expression, and provide scientific insights on how this mechanism can potentially affect SARS-CoV-2 infection in the early phases of disease. From the standpoint of other known viruses, we will then aim to discuss the potential uses or restrictions of these drugs in viral infection, and provide an update on relevant studies about COVID-19.

COVID-19 and renin-angiotensin system inhibition: role of angiotensin converting enzyme 2 (ACE2) - Is there any scientific evidence for controversy?

Renin-angiotensin system (RAS) blockers are extensively used worldwide to treat many cardiovascular disorders, where they are effective in reducing both mortality and morbidity. These drugs are known to induce an increased expression of angiotensin-converting enzyme 2 (ACE2). ACE2 acts as receptor for the novel SARS coronavirus-2 (SARS-CoV-2) which raising the important issue of possible detrimental effects that RAS blockers could exert on the natural history and pathogenesis of the coronavirus disease-19 (COVID-19) and associated excessive inflammation, myocarditis and cardiac arrhythmias. We review the current knowledge on the interaction between SARS-CoV-2 infection and RAS blockers and suggest a scientific rationale for continuing RAS blockers therapy in patients with COVID-19 infection.

The hypercoagulable state in COVID-19: Incidence, pathophysiology, and management

The 2019 coronavirus disease (COVID-19) presents with a large variety of clinical manifestations ranging from asymptomatic carrier state to severe respiratory distress, multiple organ dysfunction and death. While it was initially considered primarily a respiratory illness, rapidly accumulating data suggests that COVID-19 results in a unique, profoundly prothrombotic milieu leading to both arterial and venous thrombosis. Consistently, elevated D-dimer level has emerged as an independent risk factor for poor outcomes, including death. Several other laboratory markers and blood counts have also been associated with poor prognosis, possibly due to their connection to thrombosis. At present, the pathophysiology underlying the hypercoagulable state is poorly understood. However, a growing body of data suggests that the initial events occur in the lung. A severe inflammatory response, originating in the alveoli, triggers a dysfunctional cascade of inflammatory thrombosis in the pulmonary vasculature, leading to a state of local coagulopathy. This is followed, in patients with more severe disease, by a generalized hypercoagulable state that results in macro- and microvascular thrombosis. Of concern, is the observation that anticoagulation may be inadequate in many circumstances, highlighting the need for alternative or additional therapies. Numerous ongoing studies investigating the pathophysiology of the COVID-19 associated coagulopathy may provide mechanistic insights that can direct appropriate interventional strategies.

Dissecting the interaction between COVID-19 and diabetes mellitus

Coronavirus disease 2019 (COVID-19) is a global pandemic that is caused by a novel coronavirus, severe acute respiratory syndrome coronavirus-2. Data from several countries have shown higher morbidity and mortality among individuals with chronic metabolic diseases, such as diabetes mellitus. In this review, we explore the contributing factors for poorer prognosis in these individuals. As a significant proportion of patients with COVID-19 also have diabetes mellitus, this adds another layer of complexity to their management. We explore potential interactions between antidiabetic medications and renin-angiotensin-aldosterone system inhibitors with COVID-19. Suggested recommendations for the use of antidiabetic medications for COVID-19 patients with diabetes mellitus are provided. We also review pertinent clinical considerations in the management of diabetic ketoacidosis in COVID-19 patients. In addition, we aim to increase clinicians' awareness of the metabolic effects of promising drug therapies for COVID-19. Finally, we highlight the importance of timely vaccinations for patients with diabetes mellitus.

Hyperinflammation and derangement of renin-angiotensin-aldosterone system in COVID-19: A novel hypothesis for clinically suspected hypercoagulopathy and microvascular immunothrombosis

Early clinical evidence suggests that severe cases of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are frequently characterized by hyperinflammation, imbalance of renin-angiotensin-aldosterone system, and a particular form of vasculopathy, thrombotic microangiopathy, and intravascular coagulopathy. In this paper, we present an immunothrombosis model of COVID-19. We discuss the underlying pathogenesis and the interaction between multiple systems, resulting in propagation of immunothrombosis, which through investigation in the coming weeks, may lead to both an improved understanding of COVID-19 pathophysiology and identification of innovative and efficient therapeutic targets to reverse the otherwise unfavorable clinical outcome of many of these patients.