Angiotensin-converting enzyme 2 (ACE2), SARS-CoV-2 and the pathophysiology of coronavirus disease 2019 (COVID-19)

Pathogenesis of taste impairment and salivary dysfunction in COVID-19 patients

Coronavirus disease 2019 (COVID-19) is a highly transmissible pandemic disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The characteristics of the disease include a broad range of symptoms from mild to serious to death, with mild pneumonia to acute respiratory distress syndrome and complications in extrapulmonary organs. Taste impairment and salivary dysfunction are common early symptoms in COVID-19 patients. The mouth is a significant entry route for SARS-COV-2, similar to the nose and eyes. The cells of the oral epithelium, taste buds, and minor and major salivary glands express cell entry factors for SARS-COV-2, such as ACE2, TMPRSS2, and Furin. We describe the occurrence of taste impairment and salivary dysfunction in COVID-19 patients and show immunohistochemical findings regarding the cell entry factors in the oral tissue. We review and describe the pathogeneses of taste impairment and salivary dysfunction. Treatment for the oral disease is also described. Recently, it was reported that some people experience persistent and prolonged taste impairment and salivary dysfunction, described as post-COVID-19 syndrome or long COVID-19, after the acute illness of the infection has healed. To resolve these problems, it is important to understand the pathogenesis of oral complications. Recently, important advances have been reported in the understanding of gustatory impairment and salivary dysfunction. Although some progress has been made, considerable effort is still required for in-depth elucidation of the pathogenesis.

Retinal Microcirculation as a Correlate of a Systemic Capillary Impairment After Severe Acute Respiratory Syndrome Coronavirus 2 Infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), affects the pulmonary systems via angiotensin-converting enzyme-2 (ACE-2) receptor, being an entry to systemic infection. As COVID-19 disease features ACE-2 deficiency, a link to microcirculation is proposed. Optical coherence tomography angiography (OCT-A) enables non-invasive analysis of retinal microvasculature. Thus, an impaired systemic microcirculation might be mapped on retinal capillary system. As recent OCT-A studies, analyzing microcirculation in two subdivided layers, yielded contrary results, an increased subdivision of retinal microvasculature might offer an even more fine analysis. The aim of the study was to investigate retinal microcirculation by OCT-A after COVID-19 infection in three subdivided layers (I). In addition, short-term retinal affections were monitored during COVID-19 disease (II). Considering (I), a prospective study (33 patients_post-COVID and 28 controls) was done. Macula and peripapillary vessel density (VD) were scanned with the Spectralis II. Macula VD was measured in three layers: superficial vascular plexus (SVP), intermediate capillary plexus (ICP), and deep capillary plexus (DCP). Analysis was done by the EA-Tool, including an Anatomical Positioning System and an analysis of peripapillary VD by implementing Bruch's membrane opening (BMO) landmarks. Overall, circular (c₁, c₂, and c₃) and sectorial VD (s₁-s₁₂) was analyzed. Considering (II), in a retrospective study, 29 patients with severe complications of COVID-19 infection, hospitalized at the intensive care unit, were monitored for retinal findings at bedside during hospitalization. (I) Overall (p = 0.0133) and circular (c₁, p = 0.00257; c₂, p = 0.0067; and c₃, p = 0.0345). VD of the ICP was significantly reduced between patients_post-COVID and controls, respectively. Overall (p = 0.0179) and circular (c₁, p = 0.0189) peripapillary VD was significantly reduced between both groups. Subgroup analysis of hospitalized vs. non-hospitalized patients_post-COVID yielded a significantly reduced VD of adjacent layers (DCP and SVP) with increased severity of COVID-19 disease. Clinical severity parameters showed a negative correlation with VD (ICP) and peripapillary VD. (II) Funduscopy yielded retinal hemorrhages and cotton wool spots in 17% of patients during SARS-CoV-2 infection. As VD of the ICP and peripapillary regions was significantly reduced after COVID-19 disease and showed a link to clinical severity markers, we assume that the severity of capillary impairment after COVID-19 infection is mapped on retinal microcirculation, visualized by non-invasive OCT-A.

Modulation of Host Immune Response Is an Alternative Strategy to Combat SARS-CoV-2 Pathogenesis

The novel SARS-CoV-2virus that caused the disease COVID-19 is currently a pandemic worldwide. The virus requires an alveolar type-2 pneumocyte in the host to initiate its life cycle. The viral S1 spike protein helps in the attachment of the virus on toACE-2 receptors present on type-2 pneumocytes, and the S2 spike protein helps in the fusion of the viral membrane with the host membrane. Fusion of the SARS-CoV-2virus and host membrane is followed by entry of viral RNA into the host cells which is directly translated into the replicase-transcriptase complex (RTC) following viral RNA and structural protein syntheses. As the virus replicates within type-2 pneumocytes, the host immune system is activated and alveolar macrophages start secreting cytokines and chemokines, acting as an inflammatory mediator, and chemotactic neutrophils, monocytes, natural NK cells, and CD8+ T cells initiate the local phagocytosis of infected cells. It is not the virus that kills COVID-19 patients; instead, the aberrant host immune response kills them. Modifying the response from the host immune system could reduce the high mortality due to SARS-CoV-2 infection. The present study examines the viral life cycle intype-2 pneumocytes and resultant host immune response along with possible therapeutic targets.

Predictors of mortality in patients with coronavirus disease 2019: a systematic review and meta-analysis

BACKGROUND

Coronavirus disease 2019 (COVID-19) is associated with a high mortality rate, especially in patients with severe illness. We conducted a systematic review and meta-analysis to assess the potential predictors of mortality in patients with COVID-19.

METHODS

PubMed, EMBASE, the Cochrane Library, and three electronic Chinese databases were searched from December 1, 2019 to April 29, 2020. Eligible studies reporting potential predictors of mortality in patients with COVID-19 were identified. Unadjusted prognostic effect estimates were pooled using the random-effects model if data from at least two studies were available. Adjusted prognostic effect estimates were presented by qualitative analysis.

RESULTS

Thirty-six observational studies were identified, of which 27 were included in the meta-analysis. A total of 106 potential risk factors were tested, and the following important predictors were associated with mortality: advanced age, male sex, current smoking status, preexisting comorbidities (especially chronic kidney, respiratory, and cardio-cerebrovascular diseases), symptoms of dyspnea, complications during hospitalization, corticosteroid therapy and a severe condition. Additionally, a series of abnormal laboratory biomarkers of hematologic parameters, hepatorenal function, inflammation, coagulation, and cardiovascular injury were also associated with fatal outcome.

CONCLUSION

We identified predictors of mortality in patients with COVID-19. These findings could help healthcare providers take appropriate measures and improve clinical outcomes in such patients.

SD-OCT assessment of macular and optic nerve alterations in patients recovered from COVID-19

OBJECTIVE

To quantify microstructutal alterations in the macula and peripapillary retinal nerve fibre layer (RNFL) in patients recovered from coronavirus disease 2019 (COVID-19) using spectral domain optic coherence tomography (SD-OCT).

DESIGN

Retrospective, observational.

PARTICIPANTS

This comparative, cross-sectional study included patients who recovered from COVID-19 (Group 1) and age- and sex-matched normal controls (Group 2).

METHODS

A comprehensive ophthalmic examination, including best-corrected visual acuity and biomicroscopic anterior and posterior segment examination was performed. SD-OCT analysis of the macula and peripapillary RNFL was obtained for each participant. In addition, patient demographics and comorbidities were recorded.

RESULTS

238 eyes of 122 subjects (Group 1: n = 63; Group 2: n = 59) were included. The incidence of coexisting comorbidity was higher in Group 1 (n = 26/63, 41.3%) compared with Group 2 (n = 12/59, 20.3%) (p = 0.013). The central foveal thickness (CFT) was significantly higher in Group 1 (271.0±26.8 µm) than Group 2 (263.2±22.0 µm) (p = 0.015). The average outer nuclear layer (ONL) thickness at central fovea in Group 1 (85.4±13.3 µm) was significantly thicker than that in Group 2 (81.4±15.2 µm) (p = 0.035). The mean peripapillary RNFL thickness of Group 1 (102.6±8.8 µm) and Group 2 (100.9±8.3 µm) were similar (p = 0.145). The mean choroidal thickness of groups at the fovea and at 1500 µm nasal and temporal to the fovea were not significantly different (p > 0.05 for all).

CONCLUSION

Significant thickness alterations in individual retinal layers and CFT was detected in post-COVID-19 patients. The increase in CFT and ONL thickness might be attributed to direct infection or viral-induced inflammatory response of retina.

Endothelium Activation Markers in Severe Hospitalized COVID-19 Patients: Role in Mortality Risk Prediction

Introduction  Endothelial damage and hypercoagulability are major players behind the hemostatic derangement of SARS-CoV-2 infection.

Aim  In this prospective study we assessed endothelial and inflammatory biomarkers in a cohort of COVID-19 patients, aiming to identify predictive factors of in-hospital mortality.

Methods  COVID-19 patients hospitalized in intensive care (ICU) and non-ICU units at 2 Bergamo (Italy) hospitals from March 23 to May 30, 2020, were enrolled. Markers of endothelium activation including von-Willebrand factor (vWF), soluble thrombomodulin (sTM), and fibrinolytic proteins (t-PA and PAI-1) were measured. Additionally, D-dimer, Fibrinogen, FVIII, nucleosomes, C reactive protein (CRP) and procalcitonin were assessed.

Results  Sixty-three (45 ICU, and 18 non-ICU) patients, with a median age of 62 years were analyzed. Increased plasma levels of D-dimer, FVIII, fibrinogen, nucleosomes, CRP, and procalcitonin were observed in the whole cohort. Extremely elevated vWF levels characterized all patients (highest values in ICU-subjects). After a median time of 30 days, death occurred in 13 (21%) patients. By multivariable analysis, vWF-activity, neutrophil-count and PaO2/FiO2 were significantly associated with death. Using these variables, a linear score with 3-risk groups was generated that provided a cumulative incidence of death of 0% in the low-, 32% in the intermediate-, and 78% in the high-risk group.

Conclusions  COVID-19-induced hemostatic abnormalities are exacerbated by the severity of the disease and strongly correlate with the inflammatory status, underlying the link between coagulation, endothelial activation, and inflammation. Our study provides evidence for a role of vWF, together with neutrophils and PaO2/FiO2, as a significant predictor of in-hospital mortality by SARSCoV-2 infection.

Neutrophil Extracellular Traps Affecting Cardiovascular Health in Infectious and Inflammatory Diseases

Neutrophil extracellular traps (NETs) are web-like structures of decondensed extracellular chromatin fibers and neutrophil granule proteins released by neutrophils. NETs participate in host immune defense by entrapping pathogens. They are pro-inflammatory in function, and they act as an initiator of vascular coagulopathies by providing a platform for the attachment of various coagulatory proteins. NETs are diverse in their ability to alter physiological and pathological processes including infection and inflammation. In this review, we will summarize recent findings on the role of NETs in bacterial/viral infections associated with vascular inflammation, thrombosis, atherosclerosis and autoimmune disorders. Understanding the complex role of NETs in bridging infection and chronic inflammation as well as discussing important questions related to their contribution to pathologies outlined above may pave the way for future research on therapeutic targeting of NETs applicable to specific infections and inflammatory disorders.

The interaction of the bioflavonoids with five SARS-CoV-2 proteins targets: An in silico study

Flavonoids have been shown to have antioxidant, anti-inflammatory, anti-proliferative, antibacterial and antiviral efficacy. Therefore, in this study, we choose 85 flavonoid compounds and screened them to determine their in-silico interaction with protein targets crucial for SARS-CoV-2 infection. The five important targets chosen were the main protease (Mpro), Spike receptor binding domain (Spike-RBD), RNA - dependent RNA polymerase (RdRp or Nsp12), non-structural protein 15 (Nsp15) of SARS-CoV-2 and the host angiotensin converting enzyme-2 (ACE-2) spike-RBD binding domain. The compounds were initially docked at the selected sites and further evaluated for binding free energy, using the molecular mechanics/generalized Born surface area (MMGBSA) method. The three compounds with the best binding scores were subjected to molecular dynamics (MD) simulations. The compound, tribuloside, had a high average binding free energy of -86.99 and -88.98 kcal/mol for Mpro and Nsp12, respectively. The compound, legalon, had an average binding free energy of -59.02 kcal/mol at the ACE2 spike-RBD binding site. The compound, isosilybin, had an average free binding energy of -63.06 kcal/mol for the Spike-RBD protein. Overall, our results suggest that tribuloside, legalon and isosilybin should be evaluated in future studies to determine their efficacy to inhibit SARS-CoV-2 infectivity.

Exploring the utility of extracellular vesicles in ameliorating viral infection-associated inflammation, cytokine storm and tissue damage

Extracellular vesicles (EVs) have emerged as potential mediators of intercellular communication. EVs are nano-sized, lipid membrane-bound vesicles that contains biological information in the form of proteins, metabolites and/or nucleic acids. EVs are key regulators of tissue repair mechanisms, such as in the context of lung injuries. Recent studies suggest that EVs have the ability to repair COVID19-associated acute lung damage. EVs hold great promise for therapeutic treatments, particularly in treating a potentially fatal autoimmune response and attenuate inflammation. They are known to boost lung immunity and are involved in the pathogenesis of various lung diseases, including viral infection. EV-based immunization technology has been proven to elicit robust immune responses in many models of infectious disease, including COVID-19. The field of EV research has tremendous potential in advancing our understanding about viral infection pathogenesis, and can be translated into anti-viral therapeutic strategies.

Seroprevalence of SARS-CoV-2 antibodies in children: a prospective multicentre cohort study

BACKGROUND

Studies based on molecular testing of oral/nasal swabs underestimate SARS-CoV-2 infection due to issues with test sensitivity, test timing and selection bias. The objective of this study was to report the presence of SARS-CoV-2 antibodies, consistent with previous infection.

DESIGN

This multicentre observational cohort study, conducted between 16 April to 3 July 2020 at 5 UK sites, recruited children of healthcare workers, aged 2-15 years. Participants provided blood samples for SARS-CoV-2 antibody testing and data were gathered regarding unwell contacts and symptoms.

RESULTS

1007 participants were enrolled, and 992 were included in the final analysis. The median age of participants was 10·1 years. There were 68 (6.9%) participants with positive SARS-CoV-2 antibody tests indicative of previous SARS-CoV-2 infection. Of these, 34/68 (50%) reported no symptoms prior to testing. The presence of antibodies and the mean antibody titre was not influenced by age. Following multivariable analysis four independent variables were identified as significantly associated with SARS-CoV-2 seropositivity: known infected household contact OR=10.9 (95% CI 6.1 to 19.6); fatigue OR=16.8 (95% CI 5.5 to 51.9); gastrointestinal symptoms OR=6.6 (95% CI 3.0 to 13.8); and changes in sense of smell or taste OR=10.0 (95% CI 2.4 to 11.4).

DISCUSSION

Children demonstrated similar antibody titres in response to SARS-CoV-2 irrespective of age. Fatigue, gastrointestinal symptoms and changes in sense of smell or taste were the symptoms most strongly associated with SARS-CoV-2 antibody positivity.

TRIAL REGISTRATION NUMBER

NCT0434740.

Current status of the COVID-19 and male reproduction: A review of the literature

BACKGROUND

Coronavirus disease 2019 (COVID-19), which causes serious respiratory illnesses such as pneumonia and lung failure, was first reported in mid-December 2019 in China and has spread around the world. In addition to causing serious respiratory illnesses such as pneumonia and lung failure, there have been conflicting reports about the presence of SARS-CoV-2 in the semen of patients who were previously diagnosed with COVID-19 and possible implications for the male reproductive tract.

OBJECTIVE

The goal for the present study was to review the current status of the literature concerning COVID-19 and male reproduction.

MATERIAL AND METHODS

An electronic literature search was done by using PubMed and Google Scholar databases. Relevant papers, concerning SARS-COV-2 and COVID-19 and male reproduction, published between January 2020 and December 2020 were selected, analyzed and eventually included in the present literature review.

RESULTS

SARS-CoV-2 may infect any cell type expressing angiotensin-converting enzyme 2 (ACE2), including reproductive cells. Besides the presence of the SARS-CoV-2 receptor, the expression of host proteases, such as transmembrane serine protease 2 (TMPRSS2), is needed to cleave the viral S protein, allowing permanent fusion of the viral and host cell membranes. Here, we aimed to review the current status of the literature concerning COVID-19 and male reproduction. The lack of co-expression of ACE2 and TMPRSS2 in the testis suggests that sperm cells may not be at increased risk of viral entry and spread. However, the presence of orchitis in COVID-19-confirmed patients and compromised sex-related hormonal balance among these patients intrigues reproductive medicine.

DISCUSSION

SARS-CoV-2 may use alternate receptors to enter certain cell types, or the expression of ACE2 and TMPRSS2 may not be detected in healthy individuals.

CONCLUSION

COVID-19 challenges all medical areas, including reproductive medicine. It is not yet clear what effects, if any, the COVID-19 pandemic will have on male reproduction. Further research is needed to understand the long-term impact of SARS-CoV-2 on male reproductive function.

Could Dapagliflozin Attenuate COVID-19 Progression in High-Risk Patients With or Without Diabetes? Behind DARE-19 Concept

ABSTRACT

Epidemiological studies indicate that diabetes is the second most common comorbidity in COVID-19 (coronavirus disease 2019). Dapagliflozin, a sodium-glucose co-transporter 2 inhibitor, exerts direct cardioprotective and nephroprotective effects. DARE-19 (Dapagliflozin in Respiratory Failure in Patients With COVID-19), an ongoing clinical trial, is designed to investigate the impact of dapagliflozin on COVID-19 progression. This article discusses the potential favorable impact of dapagliflozin on COVID-19 and its complications.

Efficacy and safety of remdesivir in hospitalized Covid-19 patients: Systematic review and meta-analysis including network meta-analysis

Remdesivir is an antiviral agent that has shown broad-spectrum activity, including against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Clinical trials investigating the role of remdesivir in coronavirus disease 2019 (Covid-19) reported conflicting results. This study aimed to systematically review the best available evidence and synthesize the results. Several electronic databases were searched for candidate studies up to 12 October 2020. Studies eligible for meta-analysis were selected based on the inclusion criteria. Primary outcomes are the recovery and mortality rates, while secondary outcomes are the safety profile of remdesivir. The main effective measures are the rate ratio (RR) and rate difference (RD). Four clinical trials and one observational study were included. Remdesivir treatment for 10 days increased the recovery rate on day 14 by 50% among severe Covid-19 patients (RR = 1.5, 95%CI = 1.33-1.7), while on day 28 it was increased by 14% among moderate and severe Covid-19 patients (RR = 1.14, 95%CI = 1.06-1.22). Additionally, remdesivir decreased the mortality rate on day 14 by 36% among all patients (RR = 0.64, 95%CI = 0.45-0.92) but not on day 28 (RR = 1.05, 95%CI = 0.56-1.97). Nonmechanically ventilated Covid-19 patients showed better response to remdesivir in the recovery (RR = 0.3, 95%CI = 0.13-0.7) and mortality (RR = 2.33, 95%CI = 1.24-4.4) rates on day 14. Remdesivir reduced serious adverse effects by absolute 6% and no significant Grade 3 or 4 adverse effects were reported. At this early stage of the pandemic, there is evidence that remdesivir can be safely administered for hospitalized Covid-19 patients. It improves the recovery rate in both moderate and severe patients but, the optimal effect is achieved for those who are severely affected but not mechanically ventilated.

Corilagin prevents SARS-CoV-2 infection by targeting RBD-ACE2 binding

BACKGROUND

The outbreak of coronavirus (SARS-CoV-2) disease caused more than 100,000,000 people get infected and over 2,200,000 people being killed worldwide. However, the current developed vaccines or drugs may be not effective in preventing the pandemic of COVID-19 due to the mutations of coronavirus and the severe side effects of the newly developed vaccines. Chinese herbal medicines and their active components play important antiviral activities. Corilagin exhibited antiviral effect on human immunodeficiency virus (HIV), hepatitis C virus (HCV) and Epstein-Barr virus (EBV). However, whether it blocks the interaction between SARS-CoV-2 RBD and hACE2 has not been elucidated.

PURPOSE

To characterize an active compound, corilagin derived from Phyllanthus urinaria as potential SARS-CoV-2 entry inhibitors for its possible preventive application in daily anti-virus hygienic products.

METHODS

Computational docking coupled with bio-layer interferometry, BLI were adopted to screen more than 1800 natural compounds for the identification of SARS-CoV-2 spike-RBD inhibitors. Corilagin was confirmed to have a strong binding affinity with SARS-CoV-2-RBD or human ACE2 (hACE2) protein by the BLI, ELISA and immunocytochemistry (ICC) assay. Furthermore, the inhibitory effect of viral infection of corilagin was assessed by in vitro pseudovirus system. Finally, the toxicity of corilagin was examined by using MTT assay and maximal tolerated dose (MTD) studies in C57BL/6 mice.

RESULTS

Corilagin preferentially binds to a pocket that contains residues Cys 336 to Phe 374 of spike-RBD with a relatively low binding energy of -9.4 kcal/mol. BLI assay further confirmed that corilagin exhibits a relatively strong binding affinity to SARS-CoV-2-RBD and hACE2 protein. In addition, corilagin dose-dependently blocks SARS-CoV-2-RBD binding and abolishes the infectious property of RBD-pseudotyped lentivirus in hACE2 overexpressing HEK293 cells, which mimicked the entry of SARS-CoV-2 virus in human host cells. Finally, in vivo studies revealed that up to 300 mg/kg/day of corilagin was safe in C57BL/6 mice. Our findings suggest that corilagin could be a safe and potential antiviral agent against the COVID-19 acting through the blockade of the fusion of SARS-CoV-2 spike-RBD to hACE2 receptors.

CONCLUSION

Corilagin could be considered as a safe and environmental friendly anti-SARS-CoV-2 agent for its potential preventive application in daily anti-virus hygienic products.

Evaluation of pathophysiological relationships between renin-angiotensin and ACE-ACE2 systems in cardiovascular disorders: from theory to routine clinical practice in patients with heart failure

Despite the progressive improvements in diagnosis and therapy during the first 20 years of this century, the morbidity and mortality of patients with heart failure (HF) remain high, resulting in an enormous health and economic burden. Only a further improvement in understanding the pathophysiological mechanisms related to the development of cardiac injury and dysfunction can allow more innovative and personalized approaches to HF management. The renin-angiotensin system (RAS) has a critical role in cardiovascular physiology by regulating blood pressure and electrolyte balance. The RAS is mainly regulated by both angiotensin converting enzyme (ACE) and type 2 angiotensin converting enzyme (ACE2). However, the balance between the various peptides and peptidases constituting the RAS/ACE pathway remains in great part unraveled in patients with HF. This review summarizes the role of the RAS/ACE axis in cardiac physiology and HF pathophysiology as well as some analytical issues relevant to the clinical and laboratory assessment of inter-relationships between these two systems. There is evidence that RAS peptides represent a dynamic network of peptides, which are altered in different HF states and influenced by medical therapy. However, the mechanisms of signal transduction have not been fully elucidated under physiological and pathophysiological conditions. Further investigations are necessary to explore novel molecular mechanisms related to the RAS, which will provide alternative therapeutic agents. Moreover, monitoring the circulating levels of active RAS peptides in HF patients may enable a personalized approach by facilitating assessment of the pathophysiological status of several cardiovascular diseases and thus better selection of therapies for HF patients.

Obesity and its impact on COVID-19

The severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) pandemic has proven a challenge to healthcare systems since its first appearance in late 2019. The global spread and devastating effects of coronavirus disease 2019 (COVID-19) on patients have resulted in countless studies on risk factors and disease progression. Overweight and obesity emerged as one of the major risk factors for developing severe COVID-19. Here we review the biology of coronavirus infections in relation to obesity. In particular, we review literature about the impact of adiposity-related systemic inflammation on the COVID-19 disease severity, involving cytokine, chemokine, leptin, and growth hormone signaling, and we discuss the involvement of hyperactivation of the renin-angiotensin-aldosterone system (RAAS). Due to the sheer number of publications on COVID-19, we cannot be completed, and therefore, we apologize for all the publications that we do not cite.

Understanding COVID-19-associated coagulopathy: From PIC to SIC or DIC

Coagulopathy, characterized by a high D-dimer level, is a common pathological occurrence in coronavirus disease 2019 (COVID-19) and is associated with poor prognosis. Severe cases with COVID-19 is associated with a significantly higher risk of deep vein thrombosis and acute pulmonary embolism. Pulmonary intravascular coagulopathy is the characteristic coagulopathy in COVID-19. Unlike sepsis-induced coagulopathy and disseminated intravascular coagulation, which are manifestations of systemic coagulopathy, pulmonary intravascular coagulopathy is a manifestation of a local coagulation disorder in the lung. The progression from pulmonary intravascular coagulopathy to sepsis-induced coagulopathy or disseminated intravascular coagulation in the context of COVID-19 may indicate that the patient's coagulation dysfunction has progressed from local to systemic. Exploring the associated coagulation disease will aid in the understanding of the pathophysiological mechanisms underlying severe 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.

Pharmacokinetics and tissue distribution of remdesivir and its metabolites nucleotide monophosphate, nucleotide triphosphate, and nucleoside in mice

Remdesivir (RDV) exerts anti-severe acute respiratory coronavirus 2 activity following metabolic activation in the target tissues. However, the pharmacokinetics and tissue distributions of the parent drug and its active metabolites have been poorly characterized to date. Blood and tissue levels were evaluated in the current study. After intravenous administration of 20 mg/kg RDV in mice, the concentrations of the parent drug, nucleotide monophosphate (RMP) and triphosphate (RTP), as well as nucleoside (RN), in the blood, heart, liver, lung, kidney, testis, and small intestine were quantified. In blood, RDV was rapidly and completely metabolized and was barely detected at 0.5 h, similar to RTP, while its metabolites RMP and RN exhibited higher blood levels with increased residence times. The area under the concentration versus time curve up to the last measured point in time (AUC_0-t) values of RMP and RN were 4558 and 136,572 h∙nM, respectively. The maximum plasma concentration (C_max) values of RMP and RN were 2896 nM and 35,819 nM, respectively. Moreover, RDV presented an extensive distribution, and the lung, liver and kidney showed high levels of the parent drug and metabolites. The metabolic stabilities of RDV and RMP were also evaluated using lung, liver, and kidney microsomes. RDV showed higher clearances in the liver and kidney than in the lung, with intrinsic clearance (CL_int) values of 1740, 1253, and 127 mL/(min∙g microsomal protein), respectively.

COVID-19: immunopathology, pathophysiological mechanisms, and treatment options

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues to spread globally despite the worldwide implementation of preventive measures to combat the disease. Although most COVID-19 cases are characterised by a mild, self-limiting disease course, a considerable subset of patients develop a more severe condition, varying from pneumonia and acute respiratory distress syndrome (ARDS) to multi-organ failure (MOF). Progression of COVID-19 is thought to occur as a result of a complex interplay between multiple pathophysiological mechanisms, all of which may orchestrate SARS-CoV-2 infection and contribute to organ-specific tissue damage. In this respect, dissecting currently available knowledge of COVID-19 immunopathogenesis is crucially important, not only to improve our understanding of its pathophysiology but also to fuel the rationale of both novel and repurposed treatment modalities. Various immune-mediated pathways during SARS-CoV-2 infection are relevant in this context, which relate to innate immunity, adaptive immunity, and autoimmunity. Pathological findings in tissue specimens of patients with COVID-19 provide valuable information with regard to our understanding of pathophysiology as well as the development of evidence-based treatment regimens. This review provides an updated overview of the main pathological changes observed in COVID-19 within the most commonly affected organ systems, with special emphasis on immunopathology. Current management strategies for COVID-19 include supportive care and the use of repurposed or symptomatic drugs, such as dexamethasone, remdesivir, and anticoagulants. Ultimately, prevention is key to combat COVID-19, and this requires appropriate measures to attenuate its spread and, above all, the development and implementation of effective vaccines. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Cardiovascular, cerebrovascular, and renal co-morbidities in COVID-19 patients: A systematic-review and meta-analysis

BACKGROUND

COVID-19 has infected over 35 million people worldwide and led to over 1 million deaths. Several risk factors that increase COVID-19 severity have emerged, including age and a history of cardiovascular disease, hypertension, or kidney disease. However, a number of outstanding questions persist, including whether the above comorbidities correlate with increased mortality from COVID-19 or whether age is a significant confounding variable that accounts for the observed relationship between COVID-19 severity and other comorbidities.

METHODS AND FINDINGS

We conducted a systematic review and meta-analysis of studies documenting COVID-19 patients with hypertension, cardiovascular disease, cerebrovascular disease, or chronic kidney disease. We classified COVID-19 cases into severe/non-severe or deceased/surviving and calculated the odds ratio (OR) for each of the four comorbidities in these cohorts. 36 studies, comprising 22,573 patients, are included in our meta-analysis. We found that hypertension is the most prevalent comorbidity in deceased COVID-19 patients (55.4%; CI: 49.4-61.3%), followed by cardiovascular disease (30.7%; CI: 22.6-38.8%), cerebrovascular disease (13.4%; CI: 9.12-19.2%), then chronic kidney disease (9.05%; CI: 5.57-15.0%). The risk of death is also significantly higher for patients with these comorbidities, with the greatest risk factor being chronic kidney disease (OR: 8.86; CI: 5.27-14.89), followed by cardiovascular disease (OR: 6.87; CI: 5.56-8.50), hypertension (OR: 4.87; CI: 4.19-5.66), and cerebrovascular disease (OR: 4.28; CI: 2.86-6.41). These risks are significantly higher than previously reported, while correlations between comorbidities and COVID-19 severity are similar to previously reported figures. Using meta-regression analysis with age as a moderating variable, we observed that age contributes to the observed risks but does not explain them fully.

CONCLUSIONS

In this meta-analysis, we observed that cardiovascular, cerebrovascular, and kidney-related comorbidities in COVID-19 significantly contributes to greater risk of mortality and increased disease severity. We also demonstrated that age may not be a confounder to these associations.

Longdan Xiegan Tang attenuates liver injury and hepatic insulin resistance by regulating the angiotensin-converting enzyme 2/Ang (1-7)/Mas axis-mediated anti-inflammatory pathway in rats

ETHNOPHARMACOLOGICAL RELEVANCE

The ancient Chinese herbal formula Longdan Xiegan Tang (LXT, also called Gentiana Longdancao Decoction to Drain the Liver) treats insulin resistance- and inflammation-associated liver injuries in clinical practice.

AIM OF THE STUDY

To investigate the molecular mechanisms underlying LXT-elicited improvement of the liver injuries.

MATERIALS AND METHODS

Male rats were co-treated with olanzapine (5 mg/kg) and LXT extract (50 and 500 mg/kg) for eight weeks. Blood parameters were determined enzymatically or by ELISA. Gene/protein expression was analyzed by Real-Time PCR, Western blot and/or immunohistochemistry.

RESULTS

LXT attenuated olanzapine-induced liver injury manifested by hyperactivities of plasma alanine aminotransferase and aspartate aminostransferase, hyperbilirubinemia and hypoalbuminemia. Furthermore, LXT improved hepatic insulin resistance that was indicated by hyperinsulinemia, the increased HOMA-IR index, and hepatic over-phosphorylation of Ser307 in insulin receptor substrate (IRS)1, Ser731 in IRS2, Tyr607 in phosphoinositide 3-kinase p85α and Ser473 in AKT at baseline. Mechanistically, LXT inhibited olanzapine-triggered hepatic over-phosphorylation of both IκB kinase (IKK)α/β and nuclear factor (NF)κB p65 proteins, and mRNA overexpression of tumor necrosis factor α, interleukin 6, interleukin 1β and CD68. More importantly, LXT restored the decreases in angiotensin-converting enzyme 2 (ACE2) protein level, and its downstream targets Ang (1-7) content and Mas receptor expression.

CONCLUSIONS

The present results demonstrate that LXT attenuates liver injury and hepatic insulin resistance by regulating the ACE2/Ang (1-7)/Mas axis-mediated anti-inflammatory pathway in rats. Our findings provide a better understanding of LXT for treatment of insulin resistance- and inflammation-associated liver injuries.

Acute pancreatitis and COVID-19: A literature review

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the ongoing pandemic of coronavirus disease 2019 (COVID-19), and has caused more than 80 million infections and 1.7 million deaths worldwide. Although it is primarily a respiratory virus, SARS-CoV-2 also has extra-pulmonary effects. Pancreatic injury and cases of acute pancreatitis (AP) have been recognized and attributed to SARS-CoV-2, but the mechanisms of pancreatic injury are still a subject of debate. There is also controversy on whether SARS-CoV-2 can cause AP or if it is an epiphenomenon.

AIM

To review and to explore the relationship between SARS-CoV-2 infection and AP, and to provide an overview of the existing literature on possible mechanisms of SARS-CoV-2-induced pancreatic lesion.

METHODS

A systematic review was conducted in accordance with PRISMA guidelines for papers on SARS-CoV-2 infection and AP. A narrative review on possible mechanisms of SARS-CoV-2-induced pancreatic lesion was also performed.

RESULTS

A literature review revealed a growing body of evidence on SARS-CoV-2-induced pancreatic lesions including the mechanisms of direct virus-mediated injury, systemic inflammatory response and circulating pro-inflammatory interleukins, virus-induced lipotoxicity, and drug-induced injury. A systematic review of the literature revealed 22 cases of AP in COVID-19 patients. However, limitations of the reported cases make it difficult to establish a causal relationship between SARS-CoV-2 infection and AP. All of the studies agreed on special monitoring and surveillance of this subset of patients due to the still unknown clinical progression, therapeutic implications, and prognosis.

CONCLUSION

AP should be considered in COVID-19 patients, especially in those exhibiting abdominal pain and systematic, and complete reporting of these cases should be general practice. However, there is still insufficient evidence showing that COVID-19 can cause AP or negatively impact prognosis. Additional studies are needed to clarify the relationship between these two entities and their theragnostic significance.

COVID-19 is getting on our nerves: sympathetic neural activity and haemodynamics in young adults recovering from SARS-CoV-2

Key points

The impact of SARS‐CoV‐2 infection on autonomic and cardiovascular function in otherwise healthy individuals is unknown.

For the first time it is shown that young adults recovering from SARS‐CoV‐2 have elevated resting sympathetic activity, but similar heart rate and blood pressure, compared with control subjects.

Survivors of SARS‐CoV‐2 also exhibit similar sympathetic nerve activity and haemodynamics, but decreased pain perception, during a cold pressor test compared with healthy controls.

Further, these individuals display higher sympathetic nerve activity throughout an orthostatic challenge, as well as an exaggerated heart rate response to orthostasis.

If similar autonomic dysregulation, like that found here in young individuals, is present in older adults following SARS‐CoV‐2 infection, there may be substantial adverse implications for cardiovascular health.

Abstract

The novel severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) can elicit systemic adverse physiological effects. However, the impact of SARS‐CoV‐2 on autonomic and cardiovascular function in otherwise healthy individuals remains unclear. Young adults who tested positive for SARS‐CoV‐2 (COV+; n = 16, 8 F) visited the laboratory 35 ± 16 days following diagnosis. Muscle sympathetic nerve activity (MSNA), systolic (SBP) and diastolic (DBP) blood pressure, and heart rate (HR) were measured in participants at rest and during a 2 min cold pressor test (CPT) and 5 min each at 30° and 60° head‐up tilt (HUT). Data were compared with age‐matched healthy controls (CON; n = 14, 9 F). COV+ participants (18.2 ± 6.6 bursts min⁻¹) had higher resting MSNA burst frequency compared with CON (12.7 ± 3.4 bursts min⁻¹) (P = 0.020), as well as higher MSNA burst incidence and total activity. Resting HR, SBP and DBP were not different. During CPT, there were no differences in MSNA, HR, SBP or DBP between groups. COV+ participants reported less pain during the CPT compared with CON (5.7 ± 1.8 vs. 7.2 ± 1.9 a.u., P = 0.036). MSNA was higher in COV+ compared with CON during HUT. There was a group‐by‐position interaction in MSNA burst incidence, as well as HR, in response to HUT. These results indicate resting sympathetic activity, but not HR or BP, may be elevated following SARS‐CoV‐2 infection. Further, cardiovascular and perceptual responses to physiological stress may be altered, including both exaggerated (orthostasis) and suppressed (pain perception) responses, compared with healthy young adults.

The impact of SARS‐CoV‐2 infection on autonomic and cardiovascular function in otherwise healthy individuals is unknown.

For the first time it is shown that young adults recovering from SARS‐CoV‐2 have elevated resting sympathetic activity, but similar heart rate and blood pressure, compared with control subjects.

Survivors of SARS‐CoV‐2 also exhibit similar sympathetic nerve activity and haemodynamics, but decreased pain perception, during a cold pressor test compared with healthy controls.

Further, these individuals display higher sympathetic nerve activity throughout an orthostatic challenge, as well as an exaggerated heart rate response to orthostasis.

If similar autonomic dysregulation, like that found here in young individuals, is present in older adults following SARS‐CoV‐2 infection, there may be substantial adverse implications for cardiovascular health.

Asthma in the era of SARS CoV-2 virus

OBJECTIVES

It is well established in international literature that respiratory viruses can trigger asthma exacerbations. However, not all viruses affect patients in the same manner and extent. The pandemic of the SARS CoV-2 virus has brought interest to study the association of this novel virus on patients with mild-moderate and severe asthma in terms of susceptibility, severity and treatment.

DATA SOURCES – STUDY SELECTION

We performed an extensive search of current literature in the databases PubMed, Scopus and Google Scholar for original articles. We decided to include all types of articles, except for case studies, published until the end of February 2021 focusing on the effects of COVID-19 on the respiratory system and the main treatment recommendations up to date for patients with bronchial asthma.

RESULTS

Until now there is no clear evidence that asthmatics have a higher risk of experiencing exacerbations when infected, nor higher mortality rates than the general population. Nevertheless, our knowledge on molecular pathways behind asthma phenotypes in the past decades is growing, and it underlines the need to predict the unique response each patient may have to infection from the novel coronavirus. It is not clear yet if certain sub-populations of asthmatics are at higher risk than others.

CONCLUSION

Despite the lack of evidence for higher susceptibility and/or mortality in relation to COVID-19, all asthmatic patients, whether treated with inhaled bronchodilators/corticosteroids or even biologics, should maintain their controller therapy without making any alterations.

Love in the time of COVID-19: a scoping review on male sexual health

The coronavirus disease 2019 (COVID-19) outbreak constitutes an unparalleled socioeconomic burden on the global scale. In critically ill COVID-19 patients, the disease manifests as a state of hyper inflammation causing the 'cytokine storm', which leads to various pulmonary, cardiovascular, and spurious manifestations. One such reported sequelae of COVID-19 is sexual dysfunction in males even after recovery from the disease. Various mechanisms have been proposed regarding the erectile dysfunction a patient suffers after COVID-19. Most important is the hypothesis of endothelial dysregulation, subclinical hypogonadism, psychosocial misery, and pulmonary impairment contributing to erectile dysfunction. Assessment of testicular function and hormonal axis is needed to assess the novel association of COVID-19 with sexual and reproductive health issues in males.

Recent Advances in Pathology: the 2021 Annual Review Issue of The Journal of Pathology

The 2021 Annual Review Issue of The Journal of Pathology contains 14 invited reviews on current research areas of particular importance in pathology. The subjects included here reflect the broad range of interests covered by the journal, including both basic and applied research fields but always with the aim of improving our understanding of human disease. This year, our reviews encompass the huge impact of the COVID-19 pandemic, the development and application of biomarkers for immune checkpoint inhibitors, recent advances in multiplexing antigen/nucleic acid detection in situ, the use of genomics to aid drug discovery, organoid methodologies in research, the microbiome in cancer, the role of macrophage-stroma interactions in fibrosis, and TGF-β as a driver of fibrosis in multiple pathologies. Other reviews revisit the p53 field and its lack of clinical impact to date, dissect the genetics of mitochondrial diseases, summarise the cells of origin and genetics of sarcomagenesis, provide new data on the role of TRIM28 in tumour predisposition, review our current understanding of cancer stem cell niches, and the function and regulation of p63. The reviews are authored by experts in their field from academia and industry, and provide comprehensive updates of the chosen areas, in which there has been considerable recent progress. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Is carbonic anhydrase inhibition useful as a complementary therapy of Covid-19 infection?

The ongoing Covid-19 is a contagious disease, and it is characterised by different symptoms such as fever, cough, and shortness of breath. Rising concerns about Covid-19 have severely affected the healthcare system in all countries as the Covid-19 outbreak has developed at a rapid rate all around the globe. Intriguing, a clinically used drug, acetazolamide (a specific inhibitor of carbonic anhydrase, CA, EC 4.2.1.1), is used to treat high-altitude pulmonary oedema (HAPE), showing a high degree of clinical similarities with the pulmonary disease caused by Covid-19. In this context, this preliminary study aims to provide insights into some factors affecting the Covid-19 patients, such as hypoxaemia, hypoxia as well as the blood CA activity. We hypothesise that patients with Covid-19 problems could show a dysregulated acid–base status influenced by CA activity. These preliminary results suggest that the use of CA inhibitors as a pharmacological treatment for Covid-19 may be beneficial.

Multisystem Inflammatory Syndrome in Children and COVID-19 Infections

The arrival of SARS-Co-V-2 (severe acute respiratory syndrome coronavirus 2) has brought not only the COVID-19 (coronavirus disease 2019) pandemic but also the development of a cluster of symptoms known as multisystem inflammatory syndrome in children (MIS-C). Information regarding the long-term implications of COVID-19 infections in children, as well as MIS-C, is scarce and is emerging on an almost daily basis. The purpose of this article is to provide an overview of the recent literature regarding COVID-19 and MIS-C, a Kawasaki-like inflammatory syndrome that developed in children around the same time the COVID-19 pandemic began. Because the school nurse monitors children across a variety of developmental domains, they are in a unique position to identify changes and notice long-term trends related to the health and development of children who contract both COVID-19 and MIS-C.

Sex and kidney ACE2 expression in primary focal segmental glomerulosclerosis: A NEPTUNE study

Background

Angiotensin-converting enzyme 2 (ACE2) has been implicated in the pathogenesis of experimental kidney disease. ACE2 is on the X chromosome, and in mice, deletion of ACE2 leads to the development of focal segmental glomerulosclerosis (FSGS). The relationship between sex and renal ACE2 expression in humans with kidney disease is a gap in current knowledge.

Methods

We studied renal tubulointerstitial microarray data and clinical variables from subjects with FSGS enrolled in the Nephrotic Syndrome Study Network (NEPTUNE) study. We compared relationships between ACE2 expression and age, estimated glomerular filtration rate (eGFR), urinary albumin to creatinine ratio (UACR), interstitial fibrosis, tubular atrophy, and genes implicated in inflammation and fibrosis in male and female subjects.

Results

ACE2 mRNA expression was lower in the tubulointerstitium of males compared to females (P = 0.0026). Multiple linear regression analysis showed that ACE2 expression was related to sex and eGFR but not to age or treatment with renin angiotensin system blockade. ACE2 expression is also related to interstitial fibrosis, and tubular atrophy, in males but not in females. Genes involved in inflammation (CCL2 and TNF) correlated with ACE2 expression in males (TNF: r = -0.65, P < 0.0001; CCL2: r = -0.60, P < 0.0001) but not in females. TGFB1, a gene implicated in fibrosis correlated with ACE2 in both sexes.

Conclusions

Sex is an important determinant of ACE2 expression in the tubulointerstitium of the kidney in FSGS. Sex also influences the relationships between ACE2, kidney fibrosis, and expression of genes involved in kidney inflammation.

Comparison of renin-angiotensin-aldosterone system inhibitors with other antihypertensives in association with coronavirus disease-19 clinical outcomes

BACKGROUND

Reports on the effects of renin-angiotensin-aldosterone system (RAAS) inhibitors on the clinical outcomes of coronavirus disease-19 (COVID-19) have been conflicting. We performed this meta-analysis to find conclusive evidence.

METHODS

We searched published articles through PubMed, EMBASE and medRxiv from 5 January 2020 to 3 August 2020. Studies that reported clinical outcomes of patients with COVID-19, stratified by the class of antihypertensives, were included. Random and fixed-effects models were used to estimate pooled odds ratio (OR).

RESULTS

A total 36 studies involving 30,795 patients with COVID-19 were included. The overall risk of poor patient outcomes (severe COVID-19 or death) was lower in patients taking RAAS inhibitors (OR = 0.79, 95% CI: [0.67, 0.95]) compared with those receiving non-RAAS inhibitor antihypertensives. However, further sub-meta-analysis showed that specific RAAS inhibitors did not show a reduction of poor COVID-19 outcomes when compared with any class of antihypertensive except beta-blockers (BBs). For example, compared to calcium channel blockers (CCBs), neither angiotensin-I-converting enzyme inhibitors (ACEIs) (OR = 0.91, 95% CI: [0.67, 1.23]) nor angiotensin-II receptor blockers (ARBs) (OR = 0.90, 95% CI: [0.62, 1.33]) showed a reduction of poor COVID-19 outcomes. When compared with BBs, however, both ACEIs (OR = 0.85, 95% CI: [0.73, 0.99) and ARBs (OR = 0.72, 95% CI: [0.55, 0.94]) showed an apparent decrease in poor COVID-19 outcomes.

CONCLUSIONS

RAAS inhibitors did not increase the risk of mortality or severity of COVID-19. Differences in COVID-19 clinical outcomes between different class of antihypertensive drugs were likely due to the underlying comorbidities for which the antihypertensive drugs were prescribed, although adverse effects of drugs such as BBs could not be excluded.

Extracellular Vesicles and Citrullinated Histone H3 in Coronavirus Disease 2019 Patients

OBJECTIVES

 Pulmonary thrombus formation is a hallmark of coronavirus disease 2019 (COVID-19). A dysregulated immune response culminating in thromboinflammation has been described, but the pathomechanisms remain unclear.

METHODS

 We studied 41 adult COVID-19 patients with positive results on reverse-transcriptase polymerase-chain-reaction assays and 37 sex- and age-matched healthy controls. Number and surface characteristics of extracellular vesicles (EVs) and citrullinated histone H3 levels were determined in plasma upon inclusion by flow cytometry and immunoassay.

RESULTS

 In total, 20 patients had severe and 21 nonsevere disease. The number of EV (median [25th, 75th percentile]) was significantly higher in patients compared with controls (658.8 [353.2, 876.6] vs. 435.5 [332.5, 585.3], geometric mean ratio [95% confidence intervals]: 2.6 [1.9, 3.6]; p < 0.001). Patients exhibited significantly higher numbers of EVs derived from platelets, endothelial cells, leukocytes, or neutrophils than controls. EVs from alveolar-macrophages and alveolar-epithelial cells were detectable in plasma and were significantly higher in patients. Intercellular adhesion molecule-1-positive EV levels were higher in patients, while no difference between tissue factor-positive and angiotensin-converting enzyme-positive EV was seen between both groups. Levels of EV did not differ between patients with severe and nonsevere COVID-19. Citrullinated histone H3 levels (ng/mL, median [25th, 75th percentile]) were higher in patients than in controls (1.42 [0.6, 3.4] vs. 0.31 [0.1, 0.6], geometric mean ratio: 4.44 [2.6, 7.7]; p < 0.001), and were significantly lower in patients with nonsevere disease compared with those with severe disease.

CONCLUSION

 EV and citrullinated histone H3 are associated with COVID-19 and could provide information regarding pathophysiology of the disease.

Cytokine storm modulation in COVID-19: a proposed role for vitamin D and DPP-4 inhibitor combination therapy (VIDPP-4i)

A dysregulated immune response characterized by the hyperproduction of several pro-inflammatory cytokines (a.k.a. 'cytokine storm') plays a central role in the pathophysiology of severe coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this Perspective article we discuss the evidence for synergistic anti-inflammatory and immunomodulatory properties exerted by vitamin D and dipeptidyl peptidase-4 (DPP-4) inhibitors, the latter being a class of antihyperglycemic agents used for the treatment of Type 2 diabetes, which have also been reported as immunomodulators. Then, we provide the rationale for investigation of vitamin D and DPP-4 inhibitor combination therapy (VIDPP-4i) as an immunomodulation strategy to ratchet down the virulence of SARS-CoV-2, prevent disease progression and modulate the cytokine storm in COVID-19.

Novel pyrimidine-benzimidazole hybrids with antibacterial and antifungal properties and potential inhibition of SARS-CoV-2 main protease and spike glycoprotein

Objective

The study aimed to synthesize and characterize pyrimidine-linked benzimidazole hybrids, define their antimicrobial and antifungal activities in vitro, and determine their ability to inhibit the main protease and spike glycoprotein of SARS-CoV-2.

Methods

The ability of the synthesized compounds to inhibit the main protease and spike glycoprotein inhibitory of SARS-CoV-2 was investigated by assessing their mode of binding to the allosteric site of the enzyme using molecular docking. The structures of pyrimidine-linked benzimidazole derivatives synthesized with microwave assistance were confirmed by spectral analysis. Antibacterial and antifungal activities were determined by broth dilution.

Results

Gram-negative bateria (Escherichia coli and Pseudomonas aeruginosa) were more sensitive than gram-positive bateria (Staphylococcus aureus and Streptococcus pyogenes) to the derivatives. Candida albicans was sensitive to the derivatives at a minimal inhibitory concentration (MIC) of 250 μg/mL. The novel derivatives had better binding affinity (kcal/mol) than nelfinavir, lopinavir, ivermectin, remdesivir, and favipiravir, which are under investigation as treatment for SARS-CoV-2 infection. Compounds 2c, 2e, and 2g formed four hydrogen bonds with the active cavity of the main protease. Many derivatives had good binding affinity for the RBD of the of SARS-CoV-2 spike glycoprotein with the formation of up to four hydrogen bonds.

Conclusion

We synthesized novel pyrimidine-linked benzi-midazole derivatives that were potent antimicrobial agents with ability to inhibit the SARS-CoV-2 spike glycoprotein. Understanding the pharmacophore features of the main protease and spike glycoprotein offers much scope for the development of more potent agents. We plan to optimize the properties of the derivatives using models in vivo and in vitro so that they will serve as more effective therapeutic options against bacterial and SARS-CoV-2 infections.

Stem cell therapy in coronavirus disease 2019: current evidence and future potential

The end of 2019 saw the beginning of the coronavirus disease 2019 (COVID-19) pandemic that soared in 2020, affecting 215 countries worldwide, with no signs of abating. In an effort to contain the spread of the disease and treat the infected, researchers are racing against several odds to find an effective solution. The unavailability of timely and affordable or definitive treatment has caused significant morbidity and mortality. Acute respiratory distress syndrome (ARDS) caused by an unregulated host inflammatory response toward the viral infection, followed by multi-organ dysfunction or failure, is one of the primary causes of death in severe cases of COVID-19 infection. Currently, empirical management of respiratory and hematological manifestations along with anti-viral agents is being used to treat the infection. The quest is on for both a vaccine and a more definitive management protocol to curtail the spread. Researchers and clinicians are also exploring the possibility of using cell therapy for severe cases of COVID-19 with ARDS. Mesenchymal stromal cells are known to have immunomodulatory properties and have previously been used to treat viral infections. This review explores the potential of mesenchymal stromal cells as cell therapy for ARDS.

Atopic endotypes as a modulating factor for SARS-CoV-2 infection: mechanisms and implications

PURPOSE OF REVIEW

Asthma patients are typically at increased risk for severe outcomes from viral respiratory infections. However, asthma and atopy do not appear to be overrepresented comorbidities in COVID-19 patients, and hypotheses attempt to explain this observation. As COVID-19 continues to spread globally, it is imperative to understand how disease outcomes may be influenced in this population to guide patient care.

RECENT FINDINGS

Angiotensin converting enzyme 2 (ACE2) is the principal host cell receptor for SARS-CoV-2 entry and Transmembrane Protease Serine 2 (TMRSS2) is the main priming protease. Models have linked atopic endotypes to reductions in ACE2 and increases in TMRSS2 on respiratory epithelia. Epidemiologic and experimental findings imply alterations in ACE2 expression correlate with clinical COVID-19 disease, but limitations restrict the ability to draw direct conclusions.

SUMMARY

There is reasonable evidence to assert atopic endotypes modulate COVID-19 susceptibility, but it remains premature to classify this association as protective or deleterious. Asthma is a heterogeneous disease and epidemiologic studies should focus on investigating COVID-19 outcomes by underlying endotype. Direct experimental and clinical evidence is needed to draw definitive conclusions on how the complex interplay of ACE2 and TMRSS2 affect viral entry.

VIDEO ABSTRACT

https://www.dropbox.com/sh/9sfwqhz2h78sio3/AAB0JYd4MFzM5JjDFcYwz4CXa?dl=0.

COVID-19 in patients with systemic lupus erythematosus: lessons learned from the inflammatory disease

As the world navigates the coronavirus disease 2019 (COVID-19) pandemic, there is a growing need to assess its impact in patients with autoimmune rheumatic diseases, such as systemic lupus erythematosus (SLE). Patients with SLE are a unique population when considering the risk of contracting COVID-19 and infection outcomes. The use of systemic glucocorticoids and immunosuppressants, and underlying organ damage from SLE are potential susceptibility factors. Most patients with SLE have evidence of high type I interferon activity, which may theoretically act as an antiviral line of defense or contribute to the development of a deleterious hyperinflammatory response in COVID-19. Other immunopathogenic mechanisms of SLE may overlap with those described in COVID-19, thus, studies in SLE could provide some insight into immune responses occurring in severe cases of the viral infection. We reviewed the literature to date on COVID-19 in patients with SLE and provide an in-depth review of current research in the area, including immune pathway activation, epidemiology, clinical features, outcomes, and the psychosocial impact of the pandemic in those with autoimmune disease.

Coronavirus Disease 2019 in Children

Since its appearance in Wuhan in mid-December 2019, acute respiratory syndrome coronavirus 2 (SARS-CoV-2) related 19 coronavirus disease (COVID-19) has spread dramatically worldwide. It soon became apparent that the incidence of pediatric COVID-19 was much lower than the adult form. Morbidity in children is characterized by a variable clinical presentation and course. Symptoms are similar to those of other acute respiratory viral infections, the upper airways being more affected than the lower airways. Thus far, over 90% of children who tested positive for the virus presented mild or moderate symptoms and signs. Most children were asymptomatic, and only a few cases were severe, unlike in the adult population. Deaths have been rare and occurred mainly in children with underlying morbidity. Factors as reduced angiotensin-converting enzyme receptor expression, increased activation of the interferon-related innate immune response, and trained immunity have been implicated in the relative resistance to COVID-19 in children, however the underlying pathogenesis and mechanism of action remain to be established. While at the pandemic outbreak, mild respiratory manifestations were the most frequently described symptoms in children, subsequent reports suggested that the clinical course of COVID-19 is more complex than initially thought. Thanks to the experience acquired in adults, the diagnosis of pediatric SARS-CoV-2 infection has improved with time. Data on the treatment of children are sparse, however, several antiviral trials are ongoing. The purpose of this narrative review is to summarize current understanding of pediatric SARS-CoV-2 infection and provide more accurate information for healthcare workers and improve the care of patients.

The Notch Pathway: A Link Between COVID-19 Pathophysiology and Its Cardiovascular Complications

COVID-19 is associated with a large number of cardiovascular sequelae, including dysrhythmias, myocardial injury, myocarditis and thrombosis. The Notch pathway is one likely culprit leading to these complications due to its direct role in viral entry, inflammation and coagulation processes, all shown to be key parts of COVID-19 pathogenesis. This review highlights links between the pathophysiology of SARS-CoV2 and the Notch signaling pathway that serve as primary drivers of the cardiovascular complications seen in COVID-19 patients.

Novel human neutralizing mAbs specific for Spike-RBD of SARS-CoV-2

Among the therapies against the pandemic SARS-CoV-2 virus, monoclonal Antibodies (mAbs) targeting the Spike glycoprotein represent good candidates to interfere in the Spike/ACE2 interaction, preventing virus cell entry. Since anti-spike mAbs, used individually, might be unable to block the virus entry in the case of resistant mutations, we designed an innovative strategy for the isolation of multiple novel human scFvs specific for the binding domain (RBD) of Spike. By panning a large phage display antibody library on immobilized RBD, we obtained specific binders by eluting with ACE2 in order to identify those scFvs recognizing the epitope of Spike interacting with its receptor. We converted the novel scFvs into full size IgG4, differently from the previously isolated IgG1 mAbs, to avoid unwanted potential side effects of IgG1 potent effector functions on immune system. The novel antibodies specifically bind to RBD in a nanomolar range and interfere in the interaction of Spike with ACE2 receptor, either used as purified protein or when expressed on cells in its native conformation. Furthermore, some of them have neutralizing activity for virus infection in cell cultures by using two different SARS-CoV-2 isolates including the highly contagious VOC 202012/01 variant and could become useful therapeutic tools to fight against the SARS-CoV-2 virus.

Lower Gene Expression of Angiotensin Converting Enzyme 2 Receptor in Lung Tissues of Smokers with COVID-19 Pneumonia

Angiotensin-converting enzyme 2 (ACE-2) is the main cell entry receptor for severe acute respiratory syndrome-Coronavirus-2 (SARS-CoV-2), thus playing a critical role in causing Coronavirus disease 2019 (COVID-19). The role of smoking habit in the susceptibility to infection is still controversial. In this study we correlated lung ACE-2 gene expression with several clinical/pathological data to explore susceptibility to infection. This is a retrospective observational study on 29 consecutive COVID-19 autopsies. SARS-CoV-2 genome and ACE-2 mRNA expression were evaluated by real-time polymerase chain reaction in lung tissue samples and correlated with several data with focus on smoking habit. Smoking was less frequent in high than low ACE-2 expressors (p = 0.014). A Bayesian regression also including age, gender, hypertension, and virus quantity confirmed that smoking was the most probable risk factor associated with low ACE-2 expression in the model. A direct relation was found between viral quantity and ACE-2 expression (p = 0.028). Finally, high ACE-2 expressors more frequently showed a prevalent pattern of vascular injury than low expressors (p = 0.049). In conclusion, ACE-2 levels were decreased in the lung tissue of smokers with severe COVID-19 pneumonia. These results point out complex biological interactions between SARS-CoV-2 and ACE-2 particularly concerning the aspect of smoking habit and need larger prospective case series and translational studies.

COVID-19 combined with liver injury: Current challenges and management

Coronavirus disease 2019 (COVID-19) combined with liver injury has become a very prominent clinical problem. Due to the lack of a clear definition of liver injury in patients with COVID-19, the different selection of evaluation parameters and statistical time points, there are the conflicting conclusions about the incidence rate in different studies. The mechanism of COVID-19 combined with liver injury is complicated, including the direct injury of liver cells caused by severe acute respiratory syndrome coronavirus 2 replication and liver injury caused by cytokines, ischemia and hypoxia, and drugs. In addition, underlying diseases, especially chronic liver disease, can aggravate COVID-19 liver injury. In the treatment of COVID-19 combined with liver injury, the primary and basic treatment is to treat the etiology and pathogenesis, followed by support, liver protection, and symptomatic treatment according to the clinical classification and severity of liver injury. This article evaluates the incidence, pathogenesis and prevention and treatment of COVID-19 combined with liver injury, and aims to provide countermeasures for the prevention and treatment of COVID-19 combined with liver injury.

Role of phytoconstituents in the management of COVID-19

BACKGROUND

COVID-19, a severe global pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has emerged as one of the most threatening transmissible disease. As a great threat to global public health, the development of treatment options has become vital, and a rush to find a cure has mobilized researchers globally from all areas.

SCOPE AND APPROACH

This review focuses on deciphering the potential of different secondary metabolites from medicinal plants as therapeutic options either as inhibitors of therapeutic targets of SARS-CoV-2 or as blockers of viral particles entry through host cell receptors. The use of medicinal plants containing specific phytomoieties could be seen in providing a safer and long-term solution for the population with lesser side effects. Key Findings and Conclusions: Considering the high cost and time-consuming drug discovery process, therapeutic repositioning of existing drugs was explored as treatment option in COVID-19, however several molecules have been retracted as therapeutics either due to no positive outcomes or the severe side effects. These effects call for exploring the alternate treatment options which are therapeutically effective as well as safe. Keeping this in mind, phytopharmaceuticals derived from medicinal plants could be explored as important resources in the development of COVID-19 treatment, as their role in the past for treatment of viral diseases like HIV, MERS-CoV, and influenza has been well reported. Considering this fact, different phytoconstituents such as flavonoids, alkaloids, tannins and glycosides etc. Possessing antiviral properties against coronaviruses and possessing potential against SARS-CoV-2 have been reviewed in the present work.

COVID-19-Associated Pneumonia: Radiobiological Insights

The evolution of SARS-CoV-2 pneumonia to acute respiratory distress syndrome is linked to a virus-induced “cytokine storm”, associated with systemic inflammation, coagulopathies, endothelial damage, thrombo-inflammation, immune system deregulation and disruption of angiotensin converting enzyme signaling pathways. To date, the most promising therapeutic approaches in COVID-19 pandemic are linked to the development of vaccines. However, the fight against COVID-19 pandemic in the short and mid-term cannot only rely on vaccines strategies, in particular given the growing proportion of more contagious and more lethal variants among exposed population (the English, South African and Brazilian variants). As long as collective immunity is still not acquired, some patients will have severe forms of the disease. Therapeutic perspectives also rely on the implementation of strategies for the prevention of secondary complications resulting from vascular endothelial damage and from immune system deregulation, which contributes to acute respiratory distress and potentially to long term irreversible tissue damage. While the anti-inflammatory effects of low dose irradiation have been exploited for a long time in the clinics, few recent physiopathological and experimental data suggested the possibility to modulate the inflammatory storm related to COVID-19 pulmonary infection by exposing patients to ionizing radiation at very low doses. Despite level of evidence is only preliminary, these preclinical findings open therapeutic perspectives and are discussed in this article.

Dolosigranulum pigrum Modulates Immunity against SARS-CoV-2 in Respiratory Epithelial Cells

In a previous work, we demonstrated that nasally administered Dolosigranulum pigrum 040417 beneficially modulated the respiratory innate immune response triggered by the activation of Toll-like receptor 3 (TLR3) and improved protection against Respiratory Syncytial Virus (RSV) in mice. In this work, we aimed to evaluate the immunomodulatory effects of D. pigrum 040417 in human respiratory epithelial cells and the potential ability of this immunobiotic bacterium to increase the protection against Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The respiratory commensal bacterium D. pigrum 040417 differentially modulated the production of IFN-β, IL-6, CXCL8, CCL5 and CXCL10 in the culture supernatants of Calu-3 cells stimulated with poly(I:C) or challenged with SARS-CoV-2. The differential cytokine profile induced by the 040417 strain was associated with a significant reduction in viral replication and cellular damage after coronavirus infection. Of note, D. pigrum 030918 was not able to modify the resistance of Calu-3 cells to SARS-CoV-2 infection, indicating a strain-specific immunomodulatory effect for respiratory commensal bacteria. The findings of this work improve our understanding of the immunological mechanisms involved in the modulation of respiratory immunity induced by respiratory commensal bacteria, by demonstrating their specific effect on respiratory epithelial cells. In addition, the results suggest that particular strains such as D. pigrum 040417 could be used as a promising alternative for combating SARS-CoV-2 and reducing the severity of COVID-19.

Evaluation of SARS-CoV-2 Spike S1 Protein Response on PI3K-Mediated IL-8 Release

A novel coronavirus related to a condition known as a severe acute respiratory syndrome (SARS) was termed as SARS Coronavirus-19 (SARS-CoV-2 or COVID-19), which has caused an unprecedented global pandemic. Extensive efforts have been dedicated worldwide towards determining the mechanisms of COVID-19 associated pathogenesis with the goals of devising potential therapeutic approaches to mitigate or overcome comorbidities and mortalities. While the mode of SARS-CoV-2 infection, its structural configuration, and mechanisms of action, including the critical roles of the Spike protein have been substantially explored, elucidation of signaling pathways regulating its cellular responses is yet to be fully determined. Notably, phosphoinositide 3-kinases (PI3K) and its downstream pathway have been exploited among potential therapeutic targets for SARS-CoV-2, and its activation modulates the release of cytokines such as IL-8. To that end, the current studies were sought to determine the response of the SARS-CoV-2 Spike S1 protein on PI3K-mediated IL-8 release using relevant and widely used cellular models. Overall, these studies indicate that PI3K signaling does not directly mediate Spike S1 protein-induced IL-8 release in these cellular models.

SARS-CoV-2 and Pre-existing Vascular Diseases: Guilt by Association?

Severe Acute Respiratory Syndrome coronavirus-2 has rapidly spread and emerged as a pandemic. Although evidence on its pathophysiology is growing, there are still issues that should be taken into consideration, including its effects on pre-existing peripheral vascular disease. The aim of this review is to describe the thrombotic and endothelial dysfunctions caused by SARS-CoV-2, assess if cardiovascular comorbidities render an individual susceptible to the infection and determine the course of pre-existing vascular diseases in infected individuals. A search through MEDLINE, PubMed and EMBASE was conducted and more than 260 articles were identified and 97 of them were reviewed; the rest were excluded because they were not related to the aim of this study. Hypertension, cardiovascular disease, diabetes mellitus and cerebrovascular diseases comprised 24.30% ± 16.23%, 13.29% ± 12.88%, 14.82% ± 7.57% and 10.82% ± 11.64% of the cohorts reviewed, respectively. Arterial and venous thrombotic complications rocketed up to 31% in severely infected individuals in some studies. We suggest that hypertension, cardiovascular diseases, diabetes and cerebrovascular diseases may render an individual susceptible to severe COVID-19 infection. Pre-existing vascular diseases are expected to deteriorate with SARS-CoV-2 infection as a consequence of its increased thrombotic burden and the development of endothelial dysfunction. COVID-19 has emerged only a few months ago and it is premature to predict the long-term effects to the vascular system. Its disturbances of the coagulation mechanisms and effects on vascular endothelium will likely provoke a surge of vascular complications in the coming months.

Immunological Aspects of SARS-CoV-2 Infection and the Putative Beneficial Role of Vitamin-D

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is still an ongoing global health crisis. Immediately after the inhalation of SARS-CoV-2 viral particles, alveolar type II epithelial cells harbor and initiate local innate immunity. These particles can infect circulating macrophages, which then present the coronavirus antigens to T cells. Subsequently, the activation and differentiation of various types of T cells, as well as uncontrollable cytokine release (also known as cytokine storms), result in tissue destruction and amplification of the immune response. Vitamin D enhances the innate immunity required for combating COVID-19 by activating toll-like receptor 2. It also enhances antimicrobial peptide synthesis, such as through the promotion of the expression and secretion of cathelicidin and β-defensin; promotes autophagy through autophagosome formation; and increases the synthesis of lysosomal degradation enzymes within macrophages. Regarding adaptive immunity, vitamin D enhances CD4+ T cells, suppresses T helper 17 cells, and promotes the production of virus-specific antibodies by activating T cell-dependent B cells. Moreover, vitamin D attenuates the release of pro-inflammatory cytokines by CD4+ T cells through nuclear factor κB signaling, thereby inhibiting the development of a cytokine storm. SARS-CoV-2 enters cells after its spike proteins are bound to angiotensin-converting enzyme 2 (ACE2) receptors. Vitamin D increases the bioavailability and expression of ACE2, which may be responsible for trapping and inactivating the virus. Activation of the renin-angiotensin-aldosterone system (RAS) is responsible for tissue destruction, inflammation, and organ failure related to SARS-CoV-2. Vitamin D inhibits renin expression and serves as a negative RAS regulator. In conclusion, vitamin D defends the body against SARS-CoV-2 through a novel complex mechanism that operates through interactions between the activation of both innate and adaptive immunity, ACE2 expression, and inhibition of the RAS system. Multiple observation studies have shown that serum concentrations of 25 hydroxyvitamin D are inversely correlated with the incidence or severity of COVID-19. The evidence gathered thus far, generally meets Hill's causality criteria in a biological system, although experimental verification is not sufficient. We speculated that adequate vitamin D supplementation may be essential for mitigating the progression and severity of COVID-19. Future studies are warranted to determine the dosage and effectiveness of vitamin D supplementation among different populations of individuals with COVID-19.