ACE-2/ANG1-7 ameliorates ER stress-induced apoptosis in seawater aspiration-induced acute lung injury

UNVEILING THE PROTECTIVE MECHANISMS OF PUERARIN AGAINST ACUTE LUNG INJURY: A COMPREHENSIVE EXPLORATION OF THE ROLES AND MECHANISMS OF MST1/ERS SIGNALING

ABSTRACT

Objectives: Puerarin, the principal active constituent extracted from Pueraria, is believed to confer protection against sepsis-induced lung injury. The study aimed to elucidate the role and mechanism of Mst1/ERS in puerarin-mediated protection against acute lung injury (ALI). Methods: Monolayer vascular endothelial cell permeability was assessed by gauging the paracellular flow of FITC-dextran 40,000 (FD40). ELISA was employed for the quantification of inflammatory cytokines. Identification of target proteins was conducted through western blotting. Histological alterations and apoptosis were scrutinized using hematoxylin-eosin staining and TUNEL staining, respectively. The ultrastructure of the endoplasmic reticulum was observed via transmission electron microscopy. Results: Puerarin significantly protected mice from LPS-induced ALI, reducing lung interstitial width, neutrophil and lymphocyte infiltration, pulmonary interstitial and alveolar edema, and lung apoptosis. Puerarin treatment also markedly attenuated levels of TNF-α and IL-1β in both alveolar lavage fluid and serum. Furthermore, puerarin significantly attenuated LPS-induced increases in Mst1, GRP78, CHOP, and Caspase12 protein expression and blunted LPS-induced decrease in ZO-1 protein expression in lung tissues. Puerarin obviously reduced endoplasmic reticulum expansion and vesiculation. Similarly, puerarin significantly mitigated the LPS-induced reduction in HUVEC cell viability and ZO-1 expression. Puerarin also attenuated LPS-induced increase in apoptosis, TNF-α and IL-1β, FD40 flux, and Mst1, GRP78, CHOP, and Caspase12 expression in HUVEC cells. Nevertheless, the inhibitory impact of puerarin on vascular endothelial cell injury, lung injury, and endoplasmic reticulum stress (ERS) was diminished by Mst1 overexpression. Conclusion: These findings demonstrated that the Mst1/ERS signaling pathway played a pivotal role in the development of LPS-induced vascular endothelial cell dysfunction and ALI. Puerarin exhibited the ability to attenuate LPS-induced vascular endothelial cell dysfunction and ALI by inhibiting the Mst1/ERS signaling pathway.

Angiotensin-(1-7) plays an important role in regulating spermatogenesis in Trachemys scripta elegans under salinity stress

Elevation in water salinity can threaten the spermatogenesis and fertility of freshwater animals. The role of the renin-angiotensin system (RAS) in regulating spermatogenesis has attracted considerable attention. Our previous study found that red-eared sliders (Trachemys scripta elegans), could survive in 10 PSU water for over 1 year. To understand the chronic impact of salinity on testicular spermatogenesis and underlying mechanisms, male T. s. elegans were subjected to treatment with water of 5 PSU and 10 PSU for a year, and spermatogenesis and regulation of the RAS signal pathway was assessed. Results showed induced inflammation in the testes of T. s. elegans in the 10 PSU group, as evidenced by a decrease in the number of testicular germ cells from 1586 to 943. Compared with the control group, the levels of proinflammatory genes, including TNF-α, IL-12A and IL-6 were elevated 3.1, 0.3, and 1.4 times, respectively, in animals exposed to 10 PSU water. Testicular antiapoptotic processes of T. s. elegans might involve the vasoactive peptide angiotensin-(1-7) in the RAS, as its level was significantly increased from 220.2 ng ml-1 in controls to 419.2 ng ml-1 in the 10 PSU group. As expected, specific inhibitor (A-779) for the Ang-(1-7) acceptor effectively prevented the salinity-induced upregulation of genes encoding anti-inflammatory and antiapoptotic factors (TGF-β1, Bcl-6) in the testis of the 10 PSU animals, whereas it promoted the upregulation of proinflammatory and proapoptotic factors (TNF-α, IL-12A, IL-6, Bax and caspase-3). Our data indicated that Ang-(1-7) attenuates the effect of salinity on inflammation and apoptosis of the testis in T. s. elegans. A new perspective to prevent salinity-induced testis dysfunction is provided.

MicroRNA‑200c‑3p regulates seawater‑induced acute lung injury via ANGII and ACE2/ANG1‑7 pathways

Apoptosis is a main characteristic of seawater aspiration-induced acute lung injury (ALI). The local angiotensin (ANG) system angiotensin converting enzyme (ACE)-2/ANG1-7/Mas axis and ANGII/angiotensin II receptor type 1 (AT1) play an important role in apoptosis. MicroRNA (miR)-200c-3p is involved in the regulation of the ACE-2 pathway, but its role and mechanism in seawater-induced ALI remain to be elucidated. In the present study, seawater-ALI lung tissue and cell model was established and apoptosis-related proteins, ACE2, ANGII, ANG1-7 were detected by western blotting following downregulation of miR-200c-3p. In addition, miR-200c-3p was detected by reverse transcription-quantitative PCR. The target relationship between miR-200c-3p and ACE2 was confirmed by dual-luciferase reporter assay. Seawater stimulation increased the expression of miR-200c-3p, ANGII and decreased ACE-2/ANG1-7 expression and induced changes of apoptosis-related protein expression. Apoptosis can be inhibited by AT1 blocker and abrogated by addition of ANG1-7 following seawater stimulation. In addition, inhibition of miR-200c-3p suppressed apoptosis and decreased the expression of ANGII, but increased the ACE-2/ANG1-7 expression. These results suggested that increased expression of miR-200c-3p was an important cause in seawater-induced ALI and this phenomenon was through inhibition of ACE2/ANG1-7 pathway.

Anti-Oxidant and Pro-Oxidant Effects of Peroxiredoxin 6: A Potential Target in Respiratory Diseases

Peroxiredoxin 6 (PRDX6) is widely distributed in several organs, especially the lungs. The role of PRDX6 in oxidative stress is controversial and even contradictory, as indicated by research conducted over the past 20 years. PRDX6 has anti-oxidant or pro-oxidant effects on oxidative stress in different diseases. It can even exhibit both anti-oxidant and pro-oxidant effects in the same disease. These findings are attributed to the fact that PRDX6 is a multifunctional enzyme. The peroxidase and phospholipase A2 activity of PRDX6 is closely related to its anti-oxidant and pro-oxidant effects, which leads to the conflicting regulatory effects of PRDX6 on oxidative stress in respiratory diseases. Moreover, PRDX6 interacts with multiple redox signaling pathways to interfere with cell proliferation and apoptosis. PRDX6 has become a new target in respiratory disease research due to its important regulatory role in oxidative stress. In this paper, the role of PRDX6 in oxidative stress in respiratory diseases and the research progress in targeting PRDX6 are reviewed.

Angiotensin(1-7) attenuates visceral adipose tissue expansion and lipogenesis by suppression of endoplasmic reticulum stress via Mas receptor

BACKGROUND

White adipose tissue can be classified based on its location as subcutaneous and visceral fat, and the latter accumulation is reported to be more detrimental to metabolism. Endoplasmic reticulum (ER) stress has been demonstrated to regulate lipogenesis. The peptide angiotensin(1-7) [Ang(1-7)], which can be produced from angiotensin II (AngII) by angiotensin-converting enzyme 2 (ACE2), plays its role through Mas receptor, also participates in the regulation of lipid metabolism in adipose tissue, however, whether ER stress is involved in the mechanism remains unclear. Therefore, we aimed to explore the role of Ang(1-7) pathway in regulating visceral adipose tissue expansion and ER stress.

METHODS

ACE2 knockout (KO), Mas KO and C57BL/6 J mice were fed with high fat diet. Db/db mice were treated with either normal saline, Ang(1-7) or Ang(1-7) combined with Mas receptor inhibitor A779 using mini osmotic pumps. Fat mass was weighted, fat distribution was evaluated by MRI, and lipid profile and adipokines in epididymal adipose tissue were measured by ELISA kits, and histology of epididymal adipose tissue was also analyzed in multiple animal models. Additionally, differentiated 3T3-L1 cells were pre-loaded with palmitic acid to induce ER stress, then treated with drugs as those administrated to db/db mice. ER stress and lipogenesis related proteins in mice adipose and differentiated 3T3L-1 cells were analyzed by Western blot.

RESULTS

ACE2 or Mas KO mice exhibited increased visceral adipose tissue, adipocyte size and protein expression of lipogenesis and ER stress related markers in epididymal adipose tissue compared to wild-type mice. Db/db mice treated with Ang(1-7) displayed decreased visceral fat mass, adipocyte size and protein expression of lipogenesis and ER stress markers in epididymal adipose tissue compared to those treated with normal saline, while A779 partly attenuated these effects. Additionally, Ang(1-7) improved ER stress and lipogenesis markers in differentiated 3T3-L1 cells pre-loaded with palmitic acid.

CONCLUSIONS

Our findings indicated that Ang(1-7) attenuated visceral adipose tissue expansion and lipogenesis by suppression of ER stress via Mas receptor. The present study provides a potential perspective for Ang(1-7) for the therapeutics of obesity and related disorders.

Fraxinol attenuates LPS-induced acute lung injury by equilibrating ACE-Ang II-AT1R and ACE2-Ang (1-7)-Mas and inhibiting NLRP3

CONTEXT

Acute lung injury (ALI) is a serious heterogenous pulmonary disorder. Fraxinol was selected for this study since it is a simple coumarin compound, not previously investigated in ALI.

OBJECTIVES

This study investigates the ALI therapeutic effect and mechanisms of fraxinol.

MATERIALS AND METHODS

Male BALB/c mice were treated with fraxinol (20, 40, and 80 mg/kg) following intranasal injection of lipopolysaccharide (LPS; 10 μg in 50 μL). The mice in control group were intratracheally injected with 50 μL phosphate buffered saline (PBS). Raw264.7 cells were treated with fraxinol by 100 ng/mL LPS for 6 h, then treated by different concentrations of fraxinol (5, 10, and 25 μM) for 48 h. Cells in control group were treated with PBS.

RESULTS

Fraxinol with doses of 20, 40, and 80 mg/kg significantly attenuated LPS-induced lung injury in mice (lung injury score, 10.4, 31.2, 50.3%). Fraxinol attenuated the apoptosis and nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing-3 (NLRP3) activation induced by LPS (apoptosis, 18.3, 30.2, 55.6%; NLRP3, 30.0, 47.7, 63.6%). The anti-apoptosis and anti-inflammation effects of fraxinol were also confirmed in Raw264.7 cells (apoptosis, 38.8, 55.3, 68.9%; NLRP3, 20.6, 55.7, 73.9%).

DISCUSSION AND CONCLUSION

The anti-ALI effects of fraxinol maybe by equilibrating ACE-Ang II-AT1R and ACE2-Ang (1-7)-Mas axis and inhibiting NLRP3 inflammasome. Our research provides a candidate drug in the treatment of ALI.

Pinelliae rhizoma alleviated acute lung injury induced by lipopolysaccharide via suppressing endoplasmic reticulum stress-mediated NLRP3 inflammasome

Pinelliae rhizoma (PR), one kind of commonly-used Chinese herbs, is generally prescribed to treat various respiratory diseases, including acute lung injury (ALI). However, the accurate bioactive ingredients of PR and the underlying pharmacological mechanism have both not been fully elucidated. Therefore, this study aimed to identify the bioactive ingredients that could alleviate lipopolysaccharide (LPS)-induced ALI and explore the possible mechanism involved. Our results confirmed that LPS infection indeed caused acute inflammatory damage in mice lung, accompanying with the enhancement of IL-1β contents and the activation of the NLRP3 inflammasome in lung tissue and macrophagocyte, all of which were remarkably ameliorated by PR treatment. Next, mechanistically, LPS was found to trigger endoplasmic reticulum (ER) stress and downstream cellular calcium ions (Ca²⁺) release via activating Bip/ATF4/CHOP signaling pathway. Like PR, 4-PBA (a specific inhibitor of ER stress) not only obviously reversed Bip/ATF4/CHOP-mediated ER stress, but also significantly attenuated LPS-induced activation of the NLRP3 inflammasome. Furthermore, the bioactive ingredients of PR, which generated the anti-inflammatory effects, were screened by metabolomics and network pharmacology. In vitro experiments showed that chrysin, dihydrocapsaicin, and 7,8-dihydroxyflavone (7,8-DHF) notably suppressed LPS-induced ER stress and following NLRP3 inflammasome activation. In conclusion, our findings suggested that PR alleviated LPS-induced ALI by inhibiting ER stress-mediated NLRP3 inflammasome activation, which is mainly relevant with these three bioactive ingredients. This study provided a theoretical basis for the clinical application of PR to treat ALI, and these bioactive ingredients of PR would be promising therapeutic drugs for the treatment of ALI.

Severe Acute Respiratory Syndrome Coronavirus 2 Infection in Pregnancy. A Non-systematic Review of Clinical Presentation, Potential Effects of Physiological Adaptations in Pregnancy, and Placental Vascular Alterations

In December 2019, the novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) rapidly spread to become a pandemic. To date, increasing evidence has described the potential negative impact of SARS-CoV-2 infection on pregnant women. Although the pathophysiology of coronavirus disease 2019 (COVID-19) is not entirely understood, there is emerging evidence that it causes a severe systemic inflammatory response associated with vascular alterations that could be of special interest considering some physiological changes in pregnancy. Additionally, these alterations may affect the physiology of the placenta and are associated with pregnancy complications and abnormal histologic findings. On the other hand, data about the vaccine against SARS-CoV-2 are limited, but the risks of administering COVID-19 vaccines during pregnancy appear to be minimal. This review summarizes the current literature on SARSCoV2 virus infection, the development of COVID-19 and its relationship with physiological changes, and angiotensin-converting enzyme 2 (ACE2) function during pregnancy. We have particularly emphasized evidence coming from Latin American countries.

Mechanisms contributing to adverse outcomes of COVID-19 in obesity

A growing amount of epidemiological data from multiple countries indicate an increased prevalence of obesity, more importantly central obesity, among hospitalized subjects with COVID-19. This suggests that obesity is a major factor contributing to adverse outcome of the disease. As it is a metabolic disorder with dysregulated immune and endocrine function, it is logical that dysfunctional metabolism contributes to the mechanisms behind obesity being a risk factor for adverse outcome in COVID-19. Emerging data suggest that in obese subjects, (a) the molecular mechanisms of viral entry and spread mediated through ACE2 receptor, a multifunctional host cell protein which links to cellular homeostasis mechanisms, are affected. This includes perturbation of the physiological renin-angiotensin system pathway causing pro-inflammatory and pro-thrombotic challenges (b) existent metabolic overload and ER stress-induced UPR pathway make obese subjects vulnerable to severe COVID-19, (c) host cell response is altered involving reprogramming of metabolism and epigenetic mechanisms involving microRNAs in line with changes in obesity, and (d) adiposopathy with altered endocrine, adipokine, and cytokine profile contributes to altered immune cell metabolism, systemic inflammation, and vascular endothelial dysfunction, exacerbating COVID-19 pathology. In this review, we have examined the available literature on the underlying mechanisms contributing to obesity being a risk for adverse outcome in COVID-19.

Angiotensin-Converting Enzyme 2 (ACE2) in the Context of Respiratory Diseases and Its Importance in Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection

Angiotensin-Converting Enzyme 2 (ACE2) is an 805 amino acid protein encoded by the ACE2 gene expressed in various human cells, especially in those located in the epithelia. The primary function of ACE2 is to produce angiotensin (1–7) from angiotensin II (Ang II). The current research has described the importance of ACE2 and Ang (1–7) in alternative routes of the renin-angiotensin system (RAS) that promote the downregulation of fibrosis, inflammation, and oxidative stress processes in a great variety of diseases, such as hypertension, acute lung injury, liver cirrhosis, and kidney abnormalities. Investigations into the recent outbreak of the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have revealed the importance of ACE2 during infection and its role in recognizing viral binding proteins through interactions with specific amino acids of this enzyme. Additionally, the ACE2 expression in several organs has allowed us to understand the clinical picture related to the infection caused by SARS-CoV-2. This review aims to provide context for the functions and importance of ACE2 with regards to SARS-CoV-2 in the general clinical aspect and its impact on other diseases, especially respiratory diseases.

Angiotensin-Converting Enzyme 2 (ACE2) as a Potential Diagnostic and Prognostic Biomarker for Chronic Inflammatory Lung Diseases

Chronic inflammatory lung diseases are characterized by uncontrolled immune response in the airways as their main pathophysiological manifestation. The lack of specific diagnostic and therapeutic biomarkers for many pulmonary diseases represents a major challenge for pulmonologists. The majority of the currently approved therapeutic approaches are focused on achieving disease remission, although there is no guarantee of complete recovery. It is known that angiotensin-converting enzyme 2 (ACE2), an important counter-regulatory component of the renin–angiotensin–aldosterone system (RAAS), is expressed in the airways. It has been shown that ACE2 plays a role in systemic regulation of the cardiovascular and renal systems, lungs and liver by acting on blood pressure, electrolyte balance control mechanisms and inflammation. Its protective role in the lungs has also been presented, but the exact pathophysiological mechanism of action is still elusive. The aim of this study is to review and discuss recent findings about ACE2, including its potential role in the pathophysiology of chronic inflammatory lung diseases:, i.e., chronic obstructive pulmonary disease, asthma, and pulmonary hypertension. Additionally, in the light of the coronavirus 2019 disease (COVID-19), we will discuss the role of ACE2 in the pathophysiology of this disease, mainly represented by different grades of pulmonary problems. We believe that these insights will open up new perspectives for the future use of ACE2 as a potential biomarker for early diagnosis and monitoring of chronic inflammatory lung diseases.

Selective inhibition of JNK mitochondrial location is protective against seawater inhalation‑induced ALI/ARDS

Localization of phosphorylated (p)‑JNK to the mitochondria can lead to functional mitochondrial disorder, resulting in a decrease in energy supply and membrane potential, as well as an increase in reactive oxygen species production and apoptosis. JNK is involved in the occurrence of acute lung injury (ALI), and activation of the JNK pathway is one of the crucial factors resulting in injury. The aim of the present study was to investigate whether the JNK‑mitochondria (mitoJNK) location participated in the occurrence of ALI and acute respiratory distress syndrome (ALI/ARDS). The present study examined the activation of the JNK pathway, the content of JNK located on the mitochondria and the treatment effects of a cell‑permeable peptide Tat‑SabKIM1, which can selectively inhibit the location of JNK on mitochondria. The expression levels of proteins were detected by western blot analysis. Lung injuries were evaluated by histological examination, wet‑to‑dry weight ratios, and H2O2 and malondialdehyde concentrations in the lung tissues. Lung cells apoptosis was evaluated using TUNEL assay. The results demonstrated that JNK was phosphorylated and activated during seawater inhalation‑induced ALI/ARDS, not only in the routine JNK pathway but also in the mitoJNK pathway. It was also found that Tat‑SabKIM1 could specifically inhibit JNK localization to mitochondria and the activation of mitoJNK signaling. Furthermore, Tat‑SabKIM1 could inhibit Bcl‑2‑regulated autophagy and mitochondria‑mediated apoptosis. In conclusion, mitoJNK localization disrupted the normal physiological functions of the mitochondria during ALI/ARDS, and selective inhibition of JNK and mitochondrial SH3BP5 (also known as Sab) binding with Tat‑SabKIM1 can block deterioration from ALI/ARDS.

Ursolic acid alleviates heat stress-induced lung injury by regulating endoplasmic reticulum stress signaling in mice

Acute lung injury has been reported to be associated with heat stress in various animals. Ursolic acid is a natural pentacyclic triterpenoid compound with multiple bioactivities. However, it remains unknown whether ursolic acid supplementation alleviates heat stress-induced lung injury. In the present study, male Institute of Cancer Research mice were left untreated under a normal temperature condition (23±1°C), receiving orally administrated with vehicle (phosphate buffered saline) or ursolic acid (40 mg/kg BW-1·d-1 for 2 d), and then were subjected to high temperature (41±1°C) for 2 h. Histological alterations, activities of antioxidative enzymes, apoptosis, generation of reactive oxygen species, abundance of inflammatory cytokines, and endoplasmic reticulum stress-related proteins were analyzed. Compared with the controls, heat stress treatment led to enhanced apoptosis, increased H2O2 production, and upregulated protein levels of inflammatory cytokines in the serum, including tumor necrosis factor alpha, interleukin-6, and interleukin-1 beta. Activities of malondialdehyde, lactate dehydrogenase, and myeloperoxidase were increased, while the activities for superoxide dismutase and catalase were reduced in lung tissues of mice. All these alterations were significantly prevented by ursolic acid administration. Further study showed that heat stress led to activation of protein kinase-like ER kinase eukaryotic initiation factor 2 alpha -the transcription factor CCAAT-enhancer-binding protein homologous protein (CHOP) signaling, which was attenuated by ursolic acid supplementation. These findings indicated that ursolic acid pretreatment protected lung tissues against heat stress-induced injury by regulating inflammatory cytokines and unfolded protein response in mice. Ursolic acid supplementation might be a therapeutic strategy to alleviate high temperature-induced lung injury in humans and animals.

Controversial Roles of the Renin Angiotensin System and Its Modulators During the COVID-19 Pandemic

Since December 2019, the coronavirus 2019 (COVID-19) pandemic has rapidly spread and overwhelmed healthcare systems worldwide, urging physicians to understand how to manage this novel infection. Early in the pandemic, more severe forms of COVID-19 have been observed in patients with cardiovascular comorbidities, who are often treated with renin-angiotensin aldosterone system (RAAS)-blockers, such as angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs), but whether these are indeed independent risk factors is unknown. The cellular receptor for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the membrane-bound angiotensin converting enzyme 2 (ACE2), as for SARS-CoV(-1). Experimental data suggest that expression of ACE2 may be increased by RAAS-blockers, raising concerns that these drugs may facilitate viral cell entry. On the other hand, ACE2 is a key counter-regulator of the RAAS, by degrading angiotensin II into angiotensin (1-7), and may thereby mediate beneficial effects in COVID-19. These considerations have raised concerns about the management of these drugs, and early comments shed vivid controversy among physicians. This review will describe the homeostatic balance between ACE-angiotensin II and ACE2-angiotensin (1-7) and summarize the pathophysiological rationale underlying the debated role of the RAAS and its modulators in the context of the pandemic. In addition, we will review available evidence investigating the impact of RAAS blockers on the course and prognosis of COVID-19 and discuss why retrospective observational studies should be interpreted with caution. These considerations highlight the importance of solid evidence-based data in order to guide physicians in the management of RAAS-interfering drugs in the general population as well as in patients with more or less severe forms of SARS-CoV-2 infection.

Immune response to COVID-19 infection: a double-edged sword

COVID-19 global pandemic has not ceased to spread worldwide since December 2019. Today, scientists and healthcare workers are urgently working to stop this viral invasion and protect the world community. Deciphering the specific cellular and molecular immune response to the new coronavirus 2019 is an essential step in order to develop effective treatment and vaccine. Recovery from COVID-19 infection was linked to appropriate immune responses. However, disease severity was correlated to impaired immune reactions. This review summarized the latest research findings on the role of immune system in fighting and also in the pathogenesis of COVID-19. In addition, it highlighted the immunological basis for the new coronavirus 2019 prevention, therapy and diagnosis.

Association of Cigarette Smoking, COPD, and Lung Cancer With Expression of SARS-CoV-2 Entry Genes in Human Airway Epithelial Cells

SARS-CoV-2 enters into human airway epithelial cells via membrane fusion or endocytosis, and this process is dependent on ACE2, TMPRSS2, and cathepsin L. In this study, we examined the expression profiles of the three SARS-CoV-2 entry genes in primary human airway epithelial cells isolated from smokers, non-smokers, patients with chronic obstructive pulmonary disease or lung cancer. An exhaustive search of the GEO database was performed to identify eligible data on 1st June 2020. In total, 46 GEO datasets comprising transcriptomic data of 3,053 samples were identified as eligible data for further analysis. All meta-analysis were performed using RStudio. Standardized mean difference was utilized to assess the effect size of a factor on the expression of targeted genes and 95% confidence intervals (CIs) were calculated. This study revealed that (i) cigarette smoking is associated with an increased expression of ACE2 and TMPRSS2 and a decreased expression of cathepsin L; (ii) significant alternations in expression of ACE2, TMPRSS2, and cathepsin L were observed between current smokers and former smokers, but not between former smokers and never smokers; (iii) when compared with healthy controls with identical smoking status, patients with COPD or lung cancer showed negligible changes in expression of ACE2, TMPRSS2, and cathepsin L. Therefore, this study implicates cigarette smoking might contribute to the development of COVID-19 by affecting the expression of SARS-CoV-2 entry genes, while smoking cessation could be effective to reduce the potential risk.

The Role of Molecular Chaperones in Virus Infection and Implications for Understanding and Treating COVID-19

The COVID-19 pandemic made imperative the search for means to end it, which requires a knowledge of the mechanisms underpinning the multiplication and spread of its cause, the coronavirus SARS-CoV-2. Many viruses use members of the hosts’ chaperoning system to infect the target cells, replicate, and spread, and here we present illustrative examples. Unfortunately, the role of chaperones in the SARS-CoV-2 cycle is still poorly understood. In this review, we examine the interactions of various coronaviruses during their infectious cycle with chaperones in search of information useful for future research on SARS-CoV-2. We also call attention to the possible role of molecular mimicry in the development of autoimmunity and its widespread pathogenic impact in COVID-19 patients. Viral proteins share highly antigenic epitopes with human chaperones, eliciting anti-viral antibodies that crossreact with the chaperones. Both, the critical functions of chaperones in the infectious cycle of viruses and the possible role of these molecules in COVID-19 autoimmune phenomena, make clear that molecular chaperones are promising candidates for the development of antiviral strategies. These could consist of inhibiting-blocking those chaperones that are necessary for the infectious viral cycle, or those that act as autoantigens in the autoimmune reactions causing generalized destructive effects on human tissues.

Role of Renin-Angiotensin System in Acute Lung Injury Caused by Viral Infection

The renin-angiotensin system (RAS) is the most important regulatory system of electrolyte homeostasis and blood pressure and acts through angiotensin-converting enzyme (ACE)/angiotensin II (Ang II)/Ang II type 1 (AT1) receptor axis and angiotensin-converting enzyme 2 (ACE2)/angiotensin (1-7)/MAS receptor axis. RAS dysfunction is related to the occurrence and development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) and causes a serious prognosis and even death. ALI/ARDS can be induced by various ways, one of which is viral infections, such as SARS-CoV, SARS-CoV-2, H5N1, H7N9, and EV71. This article reviews the specific mechanism on how RAS dysfunction affects ALI/ARDs caused by viral infections. SARS-CoV and SARS-CoV-2 enter the host cells by binding with ACE2. H5N1 and H7N9 avian influenza viruses reduce the ACE2 level in the body, and EV71 increases Ang II concentration. Treatment with angiotensin-converting enzyme inhibitor and angiotensin AT1 receptor blocker can alleviate ALI/ARDS symptoms. This review provides suggestions for the treatment of lung injury caused by viral infections.

The interaction of RAAS inhibitors with COVID-19: Current progress, perspective and future

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is currently defined as the worst pandemic disease. SARS-CoV-2 infects human cells via the binding of its S protein to the receptor angiotensin-converting enzyme (ACE2). The use of ACEIs/ARBs (RAAS inhibitors) regulates the renin-angiotensin-aldosterone system (RAAS) and may increase ACE2 expression. Considering the large use of ACEIs/ARBs in hypertensive patients, some professional groups are concerned about whether the use of RAAS inhibitors affects the risk of SARS-CoV-2 infection or the risk of severe illness and mortality in COVID-19 patients. In this review, we summarize preclinical and clinical studies to investigate whether the use of ACEIs/ARBs increases ACE2 expression in animals or patients. We also analyzed whether the use of these drugs affects the risk of SARS-CoV-2 infection, severe illness or mortality based on recent studies. Finally, the review suggests that current evidence does not support the concerns.

COVID-19 infection, a potential threat to surgical patients and staff? A retrospective cohort study

Background

This study aimed to describe the epidemiologic and clinical characteristics of coronavirus disease 2019 (COVID-19) in surgical patients and medical staff.

Methods

A single-center case series of 1586 consecutive surgical patients was selected at our hospital from January 13 to March 12, 2020. The epidemiological and clinical characteristics of COVID-19 were analyzed and followed up to May 20, 2020. The transmission of COVID-19 between the surgical patients and medical staff was also recorded.

Results

Seventeen (1.07%) surgical patients were diagnosed with COVID-19, with a high incidence in the thoracic department (9.37%), and the median age was 58 years (IQR, 53–73). The median time from hospital admission to COVID-19 diagnosis was 9.0 days (7.0–12.0) and was 6.0 days (4.0–7.0) from the day of surgery to COVID-19 diagnosis. Eleven (64.70%) patients suffered from pulmonary infection before surgery. When COVID-19 was diagnosed, common symptoms were fever (82.35%) and cough (94.12%), and most (82.35%) neutrophil/lymphocyte ratios were high (>3.5). Chest computed tomography (CT) (82.35%) showed bilateral dense shadows. Surgical patients with COVID-19 stayed in the hospital for approximately 35.0 days (25.5–43.0), with a mortality rate of 11.76%. Sixteen medical staff were infected with COVID-19 in the early stage.

Conclusions

In this series of 1586 surgical patients, the COVID-19 infection rate was 1.07%, with an especially high incidence among patients with thoracic diseases. Middle-aged and elderly patients with preoperative pulmonary infection were more susceptible to COVID-19 infection after surgery. Medical staff were infected with COVID-19 and should take protective measures to protect themselves.

Pathological Aspects of COVID-19 as a Conformational Disease and the Use of Pharmacological Chaperones as a Potential Therapeutic Strategy

Coronavirus disease 2019 (COVID-19), the seventh human coronavirus infectious disease, was first reported in Wuhan, China, in December 2019, followed by its rapid spread globally (251,059 deaths, on May 5, 2020, by Johns Hopkins University). An early clinical report showed that fever, cough, fatigue, sputum production, and myalgia were initial symptoms, with the development of pneumonia as the disease progressed. Increases in the level of serum liver enzymes, D-dimer, cardiac troponin I, and creatinine have been observed in severely ill patients, indicating that multiple organ failure had occurred in these cases. Lymphopenia and an increase in interleukin-6 (IL-6) were also observed. Although COVID-19 patients are administered glucocorticoid therapy to treat the excessive immune response to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection, the efficacy of this form of therapy is unclear. Viremia is observed in severe cases, suggesting that in addition to type II alveolar epithelial cells, many cell types, such as vascular endothelial cells, cardiomyocytes, renal tubular cells, neuronal cells, and lymphocytes, may be damaged. The improvement of survival rates requires elucidation of the mechanism by which cellular damage occurs during viral infection. Cellular therapy, along with organ support systems such as oxygen therapy, artificial ventilation, extra corporeal membrane oxygenation and dialysis, as well as antiviral therapy, are required. Viral replication in infected host cells may perturb protein folding in the endoplasmic reticulum (ER), causing ER stress. Although an adaptive cellular response, i.e. the unfolded protein response, can compensate for the misfolded protein burden to some extent, continued viral proliferation may induce inflammation and cell death. Therefore, we propose that proteostasis dysfunction may cause conformational disorders in COVID-19. The application of pharmacological chaperone therapy to treat COVID-19 patients is additionally discussed.

Renin-angiotensin-system, a potential pharmacological candidate, in acute respiratory distress syndrome during mechanical ventilation

While effective treatments for acute respiratory distress syndrome (ARDS) are lacking, mechanical lung ventilation can sustain adequate gas exchange in critically ill patients with respiratory failure due to ARDS. However, as a result of the phenomenon of ventilator-induced lung injury (VILI), there is an increasing need to seek beneficial pharmacological therapies for ARDS. Recent studies have suggested the renin-angiotensin system (RAS), which consists of the ACE/Ang-II/AT1R axis and ACE2/Ang-(1-7)/MasR axis, plays a dual role in the pathogenesis of ARDS and VILI. This review highlights the deleterious action of ACE/Ang-II/AT1R axis and the beneficial role of ACE2/Ang-(1-7)/MasR axis, as well as AT2R, in VILI and ARDS, and also discusses the possibility of targeting RAS components with pharmacological interventions to improve outcomes in ARDS.