Endothelial dysfunction in COVID-19: an overview of evidence, biomarkers, mechanisms and potential therapies.

The fight against coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 infection is still raging. However, the pathophysiology of acute and post-acute manifestations of COVID-19 (long COVID-19) is understudied. Endothelial cells are sentinels lining the innermost layer of blood vessel that gatekeep micro- and macro-vascular health by sensing pathogen/danger signals and secreting vasoactive molecules. SARS-CoV-2 infection primarily affects the pulmonary system, but accumulating evidence suggests that it also affects the pan-vasculature in the extrapulmonary systems by directly (via virus infection) or indirectly (via cytokine storm), causing endothelial dysfunction (endotheliitis, endothelialitis and endotheliopathy) and multi-organ injury. Mounting evidence suggests that SARS-CoV-2 infection leads to multiple instances of endothelial dysfunction, including reduced nitric oxide (NO) bioavailability, oxidative stress, endothelial injury, glycocalyx/barrier disruption, hyperpermeability, inflammation/leukocyte adhesion, senescence, endothelial-to-mesenchymal transition (EndoMT), hypercoagulability, thrombosis and many others. Thus, COVID-19 is deemed as a (micro)vascular and endothelial disease. Of translational relevance, several candidate drugs which are endothelial protective have been shown to improve clinical manifestations of COVID-19 patients. The purpose of this review is to provide a latest summary of biomarkers associated with endothelial cell activation in COVID-19 and offer mechanistic insights into the molecular basis of endothelial activation/dysfunction in macro- and micro-vasculature of COVID-19 patients. We envisage further development of cellular models and suitable animal models mimicking endothelial dysfunction aspect of COVID-19 being able to accelerate the discovery of new drugs targeting endothelial dysfunction in pan-vasculature from COVID-19 patients.

COVID-19 symptoms and compliance: The mediating role of fundamental social motives.

Background: Understanding the compliance of infected individuals and the psychological process underlying compliance during pandemics is important for preventing and controlling the spread of pathogens. Our study investigated whether fundamental social motives mediate the relationship between having infectious disease and compliance. Methods: An online survey was conducted in March 2020, during the severe phase of the COVID-19 outbreak in China to collect data from 15,758 participants. The survey comprised self-report questionnaires with items pertaining to current symptoms (COVID-19 symptoms, other symptoms or no symptoms), the Fundamental Social Motive Inventory, and measures of compliance. Correlation analysis, linear regression analysis, and structural equation model were used for data analysis. Results: The participants with COVID-19 symptoms had lower levels of compliance than those without symptoms, and their lower compliance was caused by a decrease in disease avoidance (indirect effect = -0.058, 95% CI = [-0.061, -0.056]) and familial motives (indirect effect = -0.113, 95% CI = [-0.116, -0.062]). Whereas exclusion concern (indirect effect = 0.014, 95% CI = [0.011, 0.017]) suppressed the effects of COVID-19 symptoms on compliance, the effect disappeared in the multiple mediation model, while those of disease avoidance and familial motives remained. Conclusion: Our findings emphasize the critical role of disease avoidance and familial motives in promoting compliance with public health norms during pandemics and suggest that enhancing these motives may serve as an effective intervention strategy to mitigate noncompliance among potentially infected individuals.

Endothelial Cells as a Key Cell Type for Innate Immunity: A Focused Review on RIG-I Signaling Pathway.

The vascular endothelium consists of a highly heterogeneous monolayer of endothelial cells (ECs) which are the primary target for bacterial and viral infections due to EC's constant and close contact with the bloodstream. Emerging evidence has shown that ECs are a key cell type for innate immunity. Like macrophages, ECs serve as sentinels when sensing invading pathogens or microbial infection caused by viruses and bacteria. It remains elusive how ECs senses danger signals, transduce the signal and fulfil immune functions. Retinoic acid-inducible gene-I (RIG-I, gene name also known as DDX58) is an important member of RIG-I-like receptor (RLR) family that functions as an important pathogen recognition receptor (PRR) to execute immune surveillance and confer host antiviral response. Recent studies have demonstrated that virus infection, dsRNA, dsDNA, interferons, LPS, and 25-hydroxycholesterol (25-HC) can increase RIG-1 expression in ECs and propagate anti-viral response. Of translational significance, RIG-I activation can be inhibited by Panax notoginseng saponins, endogenous PPARγ ligand 15-PGJ2, tryptanthrin and 2-animopurine. Considering the pivotal role of inflammation and innate immunity in regulating endothelial dysfunction and atherosclerosis, here we provided a concise review of the role of RIG-I in endothelial cell function and highlight future direction to elucidate the potential role of RIG-I in regulating cardiovascular diseases as well as virus infectious disease, including COVID-19. Furthered understanding of RIG-I-mediated signaling pathways is important to control disorders associated with altered immunity and inflammation in ECs.

Endothelial Cells as a Key Cell Type for Innate Immunity: A Focused Review on RIG-I Signaling Pathway

The vascular endothelium consists of a highly heterogeneous monolayer of endothelial cells (ECs) which are the primary target for bacterial and viral infections due to EC’s constant and close contact with the bloodstream. Emerging evidence has shown that ECs are a key cell type for innate immunity. Like macrophages, ECs serve as sentinels when sensing invading pathogens or microbial infection caused by viruses and bacteria. It remains elusive how ECs senses danger signals, transduce the signal and fulfil immune functions. Retinoic acid-inducible gene-I (RIG-I, gene name also known as DDX58) is an important member of RIG-I-like receptor (RLR) family that functions as an important pathogen recognition receptor (PRR) to execute immune surveillance and confer host antiviral response. Recent studies have demonstrated that virus infection, dsRNA, dsDNA, interferons, LPS, and 25-hydroxycholesterol (25-HC) can increase RIG-1 expression in ECs and propagate anti-viral response. Of translational significance, RIG-I activation can be inhibited by Panax notoginseng saponins, endogenous PPARγ ligand 15-PGJ2, tryptanthrin and 2-animopurine. Considering the pivotal role of inflammation and innate immunity in regulating endothelial dysfunction and atherosclerosis, here we provided a concise review of the role of RIG-I in endothelial cell function and highlight future direction to elucidate the potential role of RIG-I in regulating cardiovascular diseases as well as virus infectious disease, including COVID-19. Furthered understanding of RIG-I-mediated signaling pathways is important to control disorders associated with altered immunity and inflammation in ECs.

Therapeutic potential of colchicine in cardiovascular medicine: a pharmacological review.

Colchicine is an ancient herbal drug derived from Colchicum autumnale. It was first used to treat familial Mediterranean fever and gout. Based on its unique efficacy as an anti-inflammatory agent, colchicine has been used in the therapy of cardiovascular diseases including coronary artery disease, atherosclerosis, recurrent pericarditis, vascular restenosis, heart failure, and myocardial infarction. More recently, colchicine has also shown therapeutic efficacy in alleviating cardiovascular complications of COVID-19. COLCOT and LoDoCo2 are two milestone clinical trials that confirm the curative effect of long-term administration of colchicine in reducing the incidence of cardiovascular events in patients with coronary artery disease. There is growing interest in studying the anti-inflammatory mechanisms of colchicine. The anti-inflammatory action of colchicine is mediated mainly through inhibiting the assembly of microtubules. At the cellular level, colchicine inhibits the following: (1) endothelial cell dysfunction and inflammation; (2) smooth muscle cell proliferation and migration; (3) macrophage chemotaxis, migration, and adhesion; (4) platelet activation. At the molecular level, colchicine reduces proinflammatory cytokine release and inhibits NF-κB signaling and NLRP3 inflammasome activation. In this review, we summarize the current clinical trials with proven curative effect of colchicine in treating cardiovascular diseases. We also systematically discuss the mechanisms of colchicine action in cardiovascular therapeutics. Altogether, colchicine, a bioactive constituent from an ancient medicinal herb, exerts unique anti-inflammatory effects and prominent cardiovascular actions, and will charter a new page in cardiovascular medicine.

A global assessment of the impact of school closure in reducing COVID-19 spread.

Prolonged school closure has been adopted worldwide to control COVID-19. Indeed, UN Educational, Scientific and Cultural Organization figures show that two-thirds of an academic year was lost on average worldwide due to COVID-19 school closures. Such pre-emptive implementation was predicated on the premise that school children are a core group for COVID-19 transmission. Using surveillance data from the Chinese cities of Shenzhen and Anqing together, we inferred that compared with the elderly aged 60 and over, children aged 18 and under and adults aged 19-59 were 75% and 32% less susceptible to infection, respectively. Using transmission models parametrized with synthetic contact matrices for 177 jurisdictions around the world, we showed that the lower susceptibility of school children substantially limited the effectiveness of school closure in reducing COVID-19 transmissibility. Our results, together with recent findings that clinical severity of COVID-19 in children is lower, suggest that school closure may not be ideal as a sustained, primary intervention for controlling COVID-19. This article is part of the theme issue 'Data science approach to infectious disease surveillance'.

Endothelial Dysfunction in Atherosclerotic Cardiovascular Diseases and Beyond: From Mechanism to Pharmacotherapies.

The endothelium, a cellular monolayer lining the blood vessel wall, plays a critical role in maintaining multiorgan health and homeostasis. Endothelial functions in health include dynamic maintenance of vascular tone, angiogenesis, hemostasis, and the provision of an antioxidant, anti-inflammatory, and antithrombotic interface. Dysfunction of the vascular endothelium presents with impaired endothelium-dependent vasodilation, heightened oxidative stress, chronic inflammation, leukocyte adhesion and hyperpermeability, and endothelial cell senescence. Recent studies have implicated altered endothelial cell metabolism and endothelial-to-mesenchymal transition as new features of endothelial dysfunction. Endothelial dysfunction is regarded as a hallmark of many diverse human panvascular diseases, including atherosclerosis, hypertension, and diabetes. Endothelial dysfunction has also been implicated in severe coronavirus disease 2019. Many clinically used pharmacotherapies, ranging from traditional lipid-lowering drugs, antihypertensive drugs, and antidiabetic drugs to proprotein convertase subtilisin/kexin type 9 inhibitors and interleukin 1ß monoclonal antibodies, counter endothelial dysfunction as part of their clinical benefits. The regulation of endothelial dysfunction by noncoding RNAs has provided novel insights into these newly described regulators of endothelial dysfunction, thus yielding potential new therapeutic approaches. Altogether, a better understanding of the versatile (dys)functions of endothelial cells will not only deepen our comprehension of human diseases but also accelerate effective therapeutic drug discovery. In this review, we provide a timely overview of the multiple layers of endothelial function, describe the consequences and mechanisms of endothelial dysfunction, and identify pathways to effective targeted therapies. SIGNIFICANCE STATEMENT: The endothelium was initially considered to be a semipermeable biomechanical barrier and gatekeeper of vascular health. In recent decades, a deepened understanding of the biological functions of the endothelium has led to its recognition as a ubiquitous tissue regulating vascular tone, cell behavior, innate immunity, cell-cell interactions, and cell metabolism in the vessel wall. Endothelial dysfunction is the hallmark of cardiovascular, metabolic, and emerging infectious diseases. Pharmacotherapies targeting endothelial dysfunction have potential for treatment of cardiovascular and many other diseases.

Pulling-Force Spinning Top for Serum Separation Combined with Paper-Based Microfluidic Devices in COVID-19 ELISA Diagnosis.

The spread of Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2), resulting in a global pandemic with around four million deaths. Although there are a variety of nucleic acid-based tests for detecting SARS-CoV-2, these methods have a relatively high cost and require expensive supporting equipment. To overcome these limitations and improve the efficiency of SARS-CoV-2 diagnosis, we developed a microfluidic platform that collected serum by a pulling-force spinning top and paper-based microfluidic enzyme-linked immunosorbent assay (ELISA) for quantitative IgA/IgM/IgG measurements in an instrument-free way. We further validated the paper-based microfluidic ELISA analysis of SARS-CoV-2 receptor-binding domain (RBD)-specific IgA/IgM/IgG antibodies from human blood samples as a good measurement with higher sensitivity compared with traditional IgM/IgG detection (99.7% vs 95.6%) for early illness onset patients. In conclusion, we provide an alternative solution for the diagnosis of SARS-CoV-2 in a portable manner by this smart integration of pulling-force spinning top and paper-based microfluidic immunoassay.

The zinc finger transcription factor, KLF2, protects against COVID-19 associated endothelial dysfunction.

Coronavirus disease 2019 (COVID-19) is regarded as an endothelial disease (endothelialitis) with its patho-mechanism being incompletely understood. Emerging evidence has demonstrated that endothelial dysfunction precipitates COVID-19 and its accompanying multi-organ injuries. Thus, pharmacotherapies targeting endothelial dysfunction have potential to ameliorate COVID-19 and its cardiovascular complications. The objective of the present study is to evaluate whether kruppel-like factor 2 (KLF2), a master regulator of vascular homeostasis, represents a therapeutic target for COVID-19-induced endothelial dysfunction. Here, we demonstrate that the expression of KLF2 was reduced and monocyte adhesion was increased in endothelial cells treated with COVID-19 patient serum due to elevated levels of pro-adhesive molecules, ICAM1 and VCAM1. IL-1ß and TNF-α, two cytokines elevated in cytokine release syndrome in COVID-19 patients, decreased KLF2 gene expression. Pharmacologic (atorvastatin and tannic acid) and genetic (adenoviral overexpression) approaches to augment KLF2 levels attenuated COVID-19-serum-induced increase in endothelial inflammation and monocyte adhesion. Next-generation RNA-sequencing data showed that atorvastatin treatment leads to a cardiovascular protective transcriptome associated with improved endothelial function (vasodilation, anti-inflammation, antioxidant status, anti-thrombosis/-coagulation, anti-fibrosis, and reduced angiogenesis). Finally, knockdown of KLF2 partially reversed the ameliorative effect of atorvastatin on COVID-19-serum-induced endothelial inflammation and monocyte adhesion. Collectively, the present study implicates loss of KLF2 as an important molecular event in the development of COVID-19-induced vascular disease and suggests that efforts to augment KLF2 levels may be therapeutically beneficial.

Analysis of the intestinal microbiota in COVID-19 patients and its correlation with the inflammatory factor IL-18.

The ongoing global pandemic of COVID-19 disease, which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), mainly infect lung epithelial cells, and spread mainly through respiratory droplets. However, recent studies showed potential intestinal infection of SARS-CoV-2, implicated the possibility that the intestinal infection of SARS-CoV-2 may correlate with the dysbiosis of gut microbiota, as well as the severity of COVID-19 symptoms. Here, we investigated the alteration of the gut microbiota in COVID-19 patients, as well as analyzed the correlation between the altered microbes and the levels of intestinal inflammatory cytokine IL-18, which was reported to be elevated in the serum of in COVID-19 patients. Comparing with healthy controls or seasonal flu patients, the gut microbiota showed significantly reduced diversity, with increased opportunistic pathogens in COVID-19 patients. Also, IL-18 level was higher in the fecal samples of COVID-19 patients than in those of either healthy controls or seasonal flu patients. Moreover, the IL-18 levels were even higher in the fecal supernatants obtained from COVID-19 patients that tested positive for SARS-CoV-2 RNA than those that tested negative in fecal samples. These results indicate that changes in gut microbiota composition might contribute to SARS-CoV-2-induced production of inflammatory cytokines in the intestine and potentially also to the onset of a cytokine storm.

Semen parameters in men recovered from COVID-19.

The novel coronavirus disease (COVID-19) pandemic is emerging as a global health threat and shows a higher risk for men than women. Thus far, the studies on andrological consequences of COVID-19 are limited. To ascertain the consequences of COVID-19 on sperm parameters after recovery, we recruited 41 reproductive-aged male patients who had recovered from COVID-19, and analyzed their semen parameters and serum sex hormones at a median time of 56 days after hospital discharge. For longitudinal analysis, a second sampling was obtained from 22 of the 41 patients after a median time interval of 29 days from first sampling. Compared with controls who had not suffered from COVID-19, the total sperm count, sperm concentration, and percentages of motile and progressively motile spermatozoa in the patients were significantly lower at first sampling, while sperm vitality and morphology were not affected. The total sperm count, sperm concentration, and number of motile spermatozoa per ejaculate were significantly increased and the percentage of morphologically abnormal sperm was reduced at the second sampling compared with those at first in the 22 patients examined. Though there were higher prolactin and lower progesterone levels in patients at first sampling than those in controls, no significant alterations were detected for any sex hormones examined over time following COVID-19 recovery in the 22 patients. Although it should be interpreted carefully, these findings indicate an adverse but potentially reversible consequence of COVID-19 on sperm quality.

Effects of Shuanghuanglian oral liquids on patients with COVID-19: a randomized, open-label, parallel-controlled, multicenter clinical trial.

We conducted a randomized, open-label, parallel-controlled, multicenter trial on the use of Shuanghuanglian (SHL), a traditional Chinese patent medicine, in treating cases of COVID-19. A total of 176 patients received SHL by three doses (56 in low dose, 61 in middle dose, and 59 in high dose) in addition to standard care. The control group was composed of 59 patients who received standard therapy alone. Treatment with SHL was not associated with a difference from standard care in the time to disease recovery. Patients with 14-day SHL treatment had significantly higher rate in negative conversion of SARS-CoV-2 in nucleic acid swab tests than the patients from the control group (93.4% vs. 73.9%, P = 0.006). Analysis of chest computed tomography images showed that treatment with high-dose SHL significantly promoted absorption of inflammatory focus of pneumonia, which was evaluated by density reduction of inflammatory focus from baseline, at day 7 (mean difference (95% CI), -46.39 (-86.83 to -5.94) HU; P = 0.025) and day 14 (mean difference (95% CI), -74.21 (-133.35 to -15.08) HU; P = 0.014). No serious adverse events occurred in the SHL groups. This study illustrated that SHL in combination with standard care was safe and partially effective for the treatment of COVID-19.

Three-month outcomes of recovered COVID-19 patients: prospective observational study.

AIMS: A novel coronavirus SARS-CoV-2 has resulted in an ongoing global pandemic of Coronavirus disease 2019 (COVID-19). However, the outcomes of recovered patients have not been well defined. METHODS: This is a prospective observational follow-up study of survivors with COVID-19 from a designated tertiary center in Hefei, China. We examined chest computed tomography (CT) scanning, pulmonary function, 6-min walk distance (6MWD), and 36 item Short Form General Health Survey (SF-36). RESULTS: Among 81 enrolled patients, 62 (77%) patients and 61 (75%) patients, respectively, completed 1-month and 3-month follow-ups. Abnormal CT findings were still present in 73% of patients at 1 month and 54% at 3 months, whereas chest CT scan scores improved progressively at 1-month (5.0 ± 5.1) and 3-month follow up (3.0 ± 4.5) compared with that during hospitalization (11 ± 6.8). Mild restrictive pulmonary impairment was detected in 11% and 10% of patients at 1-month and 3-month follow up, respectively. The 6MWD was 523 ± 77 m in male patients and 484 ± 58 m in female patients, which was significantly lower than in healthy controls (606 ± 68 m, 568 ± 78 m, p < 0.001). SF-36 scores were significantly impaired in the domains of role physical (RP), role emotional (RE), and social functioning (SF) compared with the normal age-matched population. RP was improved at 3-month compared with 1-month follow up in the 41-64 years group (p < 0.01). Multivariable analysis showed that older age (over 40 years) and steroid administration during hospitalization were independently associated with worse chest CT scores at 3-month follow up. CONCLUSIONS: At 3 months, chest CT abnormalities were present in one half of COVID-19 survivors and worse chest CT scores were independently associated with older age and steroid administration during hospitalization. Residual pulmonary function impairments were modest, whereas exercise capacity and SF-36 scores were significantly lower than the general population. Support program and further follow-up evaluations may be needed.The reviews of this paper are available via the supplemental material section.

Asymptomatic patients and asymptomatic phases of Coronavirus Disease 2019 (COVID-19): a population-based surveillance study.

In this population-based study, we identified 307 confirmed COVID-19 cases from massive surveillance, including 129 551 individuals screened at fever clinics or returning from Hubei and 3710 close contacts of confirmed COVID-19 patients. Among them, 17 patients were asymptomatic at initial clinical assessment. These asymptomatic patients on admission accounted for a small proportion of all patients (5.54%) with relatively weak transmissibility, and the detection rate was 0.35 per 100 close contacts. Moreover, the dynamics of symptoms of the 307 patients showed that the interval from symptom remission to the final negativity of viral nucleic acid was 5.0 days (interquartile range 2.0 to 11.0 days), with 14 patients (4.56%) having re-detectable viral RNA after discharge. Overall, our findings suggested asymptomatic carriers and presymptomatic patients only accounted for a small proportion of COVID-19 patients. Also, the asymptomatic phase during recovery from COVID-19 implied that negativity in viral RNA is necessary as a de-isolation criterion and follow-up is recommended.

Clinical outcomes of different therapeutic options for COVID-19 in two Chinese case cohorts: A propensity-score analysis.

BACKGROUND: The timing of administration of agents and use of combination treatments in COVID-19 remain unclear. We assessed the effectiveness of therapeutics in cohorts in Hong Kong SAR and Anhui, China. METHODS: We conducted propensity-score analysis of 4771 symptomatic patients from Hong Kong between 21st January and 6th December 2020, and 648 symptomatic patients from Anhui between 1st January and 27th February 2020. We censored all observations as at 13st December 2020. Time from hospital admission to discharge, and composite outcome of death, invasive mechanical ventilation or intensive care unit admission across 1) all therapeutic options including lopinavir-ritonavir, ribavirin, umifenovir, interferon-alpha-2b, interferon-beta-1b, corticosteroids, antibiotics, and Chinese medicines, and 2) four interferon-beta-1b combination treatment groups were investigated. FINDINGS: Interferon-beta-1b was associated with an improved composite outcome (OR=0.55, 95%CI 0.38, 0.80) and earlier discharge (-8.8 days, 95%CI -9.7, -7.9) compared to those not administered interferon-beta-1b. Oral ribavirin initiated within 7 days from onset was associated with lower risk of the composite outcome in Hong Kong (OR=0.51, 95%CI 0.29, 0.90). Lopinavir-ritonavir, intravenous ribavirin, umifenovir, corticosteroids, interferon-alpha-2b, antibiotics or Chinese medicines failed to show consistent clinical benefit. Interferon-beta-1b co-administered with ribavirin was associated with improved composite outcome (OR=0.50, 95%CI 0.32, 0.78) and earlier discharge (-2.35 days, 95%CI -3.65, -1.06) compared to interferon-beta-1b monotherapy. INTERPRETATION: Our findings support the early administration of interferon-beta-1b alone or in combination with oral ribavirin for COVID-19 patients. FUNDING: Hong Kong Health and Medical Research Fund; Hong Kong Innovation and Technology Commission; Chinese Fundamental Research Funds for the Central Universities.