COVID-19 and the endothelium

Characteristics of the radial peripapillary capillary network in patients with COVID-19 based on optical coherence tomography angiography: a literature review

PURPOSE

This review aimed to evaluate the significance of assessing radial peripheral capillary (RPC) network parameters by optical coherence tomography angiography (OCTA) in patients with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection confirmed by polymerase chain reaction.

METHODS

A literature search was conducted in the PubMed database to select high-quality reviews and original articles on the use of OCTA for visualizing the RPC network and calculating RPC parameters.

RESULTS

The study revealed that systemic hypoxia, hypercoagulable state, and inflammation affect the RPC network in patients with coronavirus disease 2019 (COVID-19). Reduced RPC parameters were observed early in the course of SARS-CoV-2 infection and after several months of follow-up. Additionally, there was a correlation between reduced RPC parameters and subsequent thinning of the retinal nerve fiber layer.

CONCLUSIONS

The OCTA examination of the retina and optic disc should be considered in patients with a history of COVID-19 to assess the impact of systemic hypoxia and inflammation on ocular function. Follow-up assessment of these patients is also necessary to understand the potential consequences of ischemia affecting the optic nerve, retina, and choroid.

Morphology and Function of Red Blood Cells in COVID-19 Patients: Current Overview 2023

In severe cases, SARS-CoV-2 infection leads to severe respiratory failure. Although angiotensin-converting enzyme 2 (ACE2) receptors are not expressed in red blood cells, SARS-CoV-2 can interact with red blood cells (RBCs) via several receptors or auxiliary membrane proteins. Recent data show that viral infection causes significant damage to the RBCs, altering their morphology, deformability, and aggregability. Loss of RBC deformability and/or increased aggregability favors the development of thrombotic processes in the microcirculation, as has been described to occur in COVID-19 patients. In addition, many patients also develop systemic endotheliitis associated with generalized coagulopathy. This manifests itself clinically as obstructive microthrombi in the area of the medium and smallest vessels, which can affect all internal organs. It is thought that such changes in the RBCs may contribute to the microangiopathy/microthrombosis associated with COVID-19 and may result in impaired capillary blood flow and tissue oxygenation.

COVID-19 plasma induces subcellular remodelling within the pulmonary microvascular endothelium

BACKGROUND

COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can affect multiple organ systems, including the pulmonary vasculature. Endothelial cells (ECs) are thought to play a key role in the propagation of COVID-19, however, our understanding of the exact scale of dysregulation sustained by the pulmonary microvasculature (pMV) remains incomplete. Here we aim to identify transcriptional, phenotypic, and functional changes within the pMV induced by COVID-19.

METHODS AND RESULTS

Human pulmonary microvascular endothelial cells (HPMVEC) treated with plasma acquired from patients hospitalised with severe COVID-19 were compared to HPMVEC treated with plasma from patients hospitalised without COVID-19 but with other severe illnesses. Exposure to COVID-19 plasma caused a significant functional decline in HPMVECs as seen by a decrease in both cell viability via the WST-1 cell-proliferation assay and cell-to-cell barrier function as measured by electric cell-substrate impedance sensing. High-content imaging using a Cell Painting image-based assay further quantified morphological variations within sub-cellular organelles to show phenotypic changes in the whole endothelial cell, nucleus, mitochondria, plasma membrane and nucleolus morphology. RNA-sequencing of HPMVECs treated with COVID-19 plasma suggests the observed phenotype may, in part, be regulated by genes such as SMAD7, BCOR, SFMBT1, IFIT5 and ZNF566 which are involved in transcriptional regulation, protein monoubiquitination and TGF-β signalling.

CONCLUSION AND IMPACT

During COVID-19, the pMV undergoes significant remodelling, which is evident based on the functional, phenotypic, and transcriptional changes seen following exposure to COVID-19 plasma. The observed morphological variation may be responsible for downstream complications, such as a decline in overall cellular function and cell-to-cell barrier integrity. Moreover, genes identified through bulk RNA sequencing may contribute to our understanding of the observed phenotype and assist in developing strategies that can inform the rescue of the dysregulated endothelium.

Association between COVID-19 and sexual health: an umbrella review

PURPOSE

We conducted this umbrella review to review the current evidence on the relationship between COVID-19 and sexual health in both men and women.

METHODS

We conducted searches in Pubmed, Embase, and the Cochrane dataset for meta-analyses that met our pre-set inclusion criteria. We included studies with detailed information investigating the link between COVID-19 and sexual health in men/women. We did not limit the language.

RESULTS

The results of the included studies frequently relied on the Female Sexual Function Index to assess sexual health in women. For men, the International Index of Male Function and hospital diagnoses were commonly used to assess sexual health. Currently, there is conflicting evidence regarding the impact of COVID-19 on sexual health. However, since most studies were observational in nature, additional study designs are necessary to draw definitive conclusions across different contexts.

CONCLUSION

Our findings highlight the importance of sexual health among COVID-19 patients and people affected due to COVID-19. Further critical studies should investigate the mechanism underlying the association between COVID-19 and sexual health.

The role of the endothelium in severe acute respiratory syndrome coronavirus 2 infection and pathogenesis

Endothelial cell (EC) dysfunction is a characteristic complication of coronavirus-19 (COVID-19). This review discusses the role of the endothelium during the pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with a focus on different vascular beds, possible routes of infectivity and the impact of EC dysfunction across multiple organ systems. It is now known that COVID-19 disease elicits a distinct transcriptomic and molecular profile that is different to other viral infections, such as Influenza A (H1N1). Interestingly, there is also a suggested interplay between the heart and lungs that promotes the amplification of inflammatory cascades, leading to an exacerbation in disease severity. Multiomic studies have informed common pathways that may be responsible for endothelial activation while also highlighting key differences in COVID-19 pathogenesis between organ systems. At a pathological level, endothelialitis is an endpoint result regardless of either a direct viral infection or via indirect effects independent of infection. Understanding if ECs are directly targeted by SARS-CoV-2 or are collaterally damaged amid a cytokine storm originating from other cells and organs can provide novel insights into disease progression and may highlight possible new therapeutic opportunities targeted at the damaged endothelium.

JAK-STAT inhibition reduces endothelial prothrombotic activation and leukocyte-endothelial proadhesive interactions

BACKGROUND

Vascular activation is characterized by increased proinflammatory, pro thrombotic, and proadhesive signaling. Several chronic and acute conditions, including Bcr-abl-negative myeloproliferative neoplasms (MPNs), graft-vs-host disease, and COVID-19 have been noted to have increased activation of the janus kinase (JAK)-signal transducer and downstream activator of transcription (STAT) pathways. Two notable inhibitors of the JAK-STAT pathway are ruxolitinib (JAK1/2 inhibitor) and fedratinib (JAK2 inhibitor), which are currently used to treat MPN patients. However, in some conditions, it has been noted that JAK inhibitors can increase the risk of thromboembolic complications.

OBJECTIVES

We sought to define the anti-inflammatory and antithrombotic effects of JAK-STAT inhibitors in vascular endothelial cells.

METHODS

We assessed endothelial activation in the presence or absence of ruxolitinib or fedratinib by using immunoblots, immunofluorescence, qRT-PCR, and function coagulation assays. Finally, we used endothelialized microfluidics perfused with blood from normal and JAK2V617F+ individuals to evaluate whether ruxolitinib and fedratinib changed cell adhesion.

RESULTS

We found that both ruxolitinib and fedratinib reduced endothelial cell phospho-STAT1 and STAT3 signaling and attenuated nuclear phospho-NK-κB and phospho-c-Jun localization. JAK-STAT inhibition also limited secretion of proadhesive and procoagulant P-selectin and von Willebrand factor and proinflammatory IL-6. Likewise, we found that JAK-STAT inhibition reduced endothelial tissue factor and urokinase plasminogen activator expression and activity.

CONCLUSIONS

By using endothelialized microfluidics perfused with whole blood samples, we demonstrated that endothelial treatment with JAK-STAT inhibitors prevented rolling of both healthy control and JAK2V617F MPN leukocytes. Together, these findings demonstrate that JAK-STAT inhibitors reduce the upregulation of critical prothrombotic pathways and prevent increased leukocyte-endothelial adhesion.

Assessment of Blood Microcirculation Changes after COVID-19 Using Wearable Laser Doppler Flowmetry

The present work is focused on the study of changes in microcirculation parameters in patients who have undergone COVID-19 by means of wearable laser Doppler flowmetry (LDF) devices. The microcirculatory system is known to play a key role in the pathogenesis of COVID-19, and its disorders manifest themselves long after the patient has recovered. In the present work, microcirculatory changes were studied in dynamics on one patient for 10 days before his disease and 26 days after his recovery, and data from the group of patients undergoing rehabilitation after COVID-19 were compared with the data from a control group. A system consisting of several wearable laser Doppler flowmetry analysers was used for the studies. The patients were found to have reduced cutaneous perfusion and changes in the amplitude-frequency pattern of the LDF signal. The obtained data confirm that microcirculatory bed dysfunction is present in patients for a long period after the recovery from COVID-19.

Predictive value of inflammatory and coagulation biomarkers for venous thromboembolism in Covid-19 patients

BACKGROUND

The predictive value of coagulation markers for venous thromboembolism (VTE) in Covid-19 patients has been investigated with conflicting results.

OBJECTIVE

Our aim was to investigate the correlation between biomarkers and VTE and the predictive value of D-dimer for VTE in hospitalized Covid-19 patients.

METHODS

Complete blood count, inflammatory and coagulation biomarkers at admission were collected. VTE was defined as diagnosed pulmonary embolism or deep vein thrombosis. Events were defined as in-hospital death or ICU admission. Predictors of VTE were identified with Pearson prediction models. A ROC curve was constructed to assess the predictive value of D-dimer.

RESULTS

1651 participants were included, 111 VTE were identified. Events incidence was higher in the VTE group (49.5% vs 28.2%, p <  0.001). Neutrophil-lymphocyte ratio (NLR, 0.001; 95% CI 0.000-0.002; p 0.019) and D-dimer (0.00005; 95% CI 0.00002-0.00008; p <  0.001), Geneva score (0.026; 95% CI 0.012-0.040; p <  0.001) and Wells score (0.047; 95% CI 0.033-0.061; p <  0.001) were associated with VTE. D-dimer had a goor predictive value for VTE (ROC area 0.85, 95% CI 0.816-0.893), with an optimal cut-off value of 2677μg/L (Youden index of 0,602).

CONCLUSIONS

Among coagulation biomarkers D-dimer had the best predictive value for VTE, but higher cut-off values should be used in Covid-19.

Associations of anemia and blood transfusions with mortality in old, critically ill COVID-19 patients - Results from the prospective COVIP Study

AIMS

Anemia is common in the old and often observed in critically ill patients. Increased age is associated with higher mortality following a COVID-19 infection, making old patients prone to poor outcomes. We investigated whether anemia at admission to the ICU or the need for blood transfusion was associated with 90-day mortality in older, critically ill COVID-19 patients.

METHODS

In this prospective multicenter study, the 90-day mortality of COVID-19 patients≥70 years treated in 138 intensive care units (ICU) was analyzed. Associations between anemia (WHO definition) at admission and discharge from ICU and the use of red blood cell (RBC) transfusions with mortality were assessed. Hemoglobin thresholds of RBC transfusions in old, critically ill COVID-19 patients were recorded.

RESULTS

In 493 patients (350 anemic, 143 non-anemic), anemia (WHO definition) at the time of ICU admission was not associated with impaired overall survival. Transfusion and severe anemia (hemoglobin≤10 g/dL) at ICU discharge were independently associated with a higher risk of 90-day mortality.

CONCLUSION

The need for red blood cell transfusions and severe anemia at ICU discharge, but not at the timepoint of admission, were independently associated with 90-day mortality in critically-ill old COVID-19 patients.

Cholinergic deficiency in the cholinergic system as a pathogenetic link in the formation of various syndromes in COVID-19

According to recent data, several mechanisms of viral invasion of the central nervous system (CNS) have been proposed, one of which is both direct penetration of the virus through afferent nerve fibers and damage to the endothelium of cerebral vessels. It has been proven that the SARS-CoV-2 virus affects pathologically not only the human cardiorespiratory system but is also associated with a wide range of neurological diseases, cerebrovascular accidents, and neuromuscular pathologies. However, the observed post-COVID symptom complex in patients, manifested in the form of headache, "fog in the head," high temperature, muscle weakness, lowering blood pressure, does it make us think about the pathophysiological mechanisms that contribute to the development of this clinical picture? One possible explanation is a disruption in the signaling of the acetylcholine system (AChS) in the body. Viral invasions, and in particular COVID-19, can negatively affect the work of the AChS, disrupting its coordination activities. Therefore, the main goal of this literature review is to analyze the information and substantiate the possible mechanisms for the occurrence of post-COVID syndrome in people who have had COVID-19 from the standpoint of AChS dysfunctions.

COVID-19 hemodynamic and thrombotic effect on the eye microcirculation after hospitalization: A quantitative case-control study

BACKGROUND & OBJECTIVE

To quantify the hemodynamic and thrombotic effect of COVID-19 on the eye microcirculation of patients with thromboprophylaxis, shortly after hospital discharge.

METHODS

This case-control study included 17 COVID-19 survivors (named "COVID-19 Group") and 17 healthy volunteers (named "Control Group"). Axial blood velocity (Vax) and percentage of occluded vessels (POV) were quantified by Conjunctival Video Capillaroscopy (CVC). Microvessels were identified and classified as "capillaries" (CAP), "postcapillary venules of size 1" (PC1), and "postcapillary venules of size 2" (PC2).

RESULTS

The COVID-19 Group did not differ significantly in basic demographics from the Control Group. In the COVID-19 Group, there was a statistically significant (p < 0.001) reduction of Vax (39%, 49% and 47%, for CAP, PC1, and PC2, respectively) in comparison to the Control Group and a sizeable (p < 0.001) increase of POV (600%) in comparison to the Control Group.

CONCLUSIONS

COVID-19 not only reduces significantly axial blood velocity in the capillaries and postcapillary venules of the eye but has also a devastating effect on microthrombosis (POV) despite thromboprophylaxis treatment. This gives a possible explanation for long COVID and a hint about the existence of a possibly unknown coagulation factor.

Multimodal ultrasound imaging with conventional B-mode, elastography, and parametric analysis of contrast-enhanced ultrasound (CEUS): A novel approach to assess small bowel manifestation in severe COVID-19 disease

The aim was to describe the small bowel morphology with conventional B-mode and elastography and additionally to evaluate dynamic effects of COVID-19 associated small bowel microvascularization using CEUS with color coded perfusion parameters.Thirteen patients with severe COVID-19 acute respiratory distress syndrome (ARDS) were investigated. 13 patients required intensive care treatment with mechanical ventilation. Five patients required extracorporeal membrane oxygenation (ECMO). Contrast-enhanced ultrasound (CEUS) was performed by an experienced investigator as a bolus injection of up to 2.4 ml sulfur hexafluoride microbubbles via a central venous catheter. In the parametric analysis of CEUS, the flare of microbubbles over time is visualized with colors. This is the first work using parametric analysis of CEUS to detect perfusion differences in the small bowel.Parametric analysis of CEUS in the intestinal phase was carried out, using DICOM loops for 20 seconds. In 5 patients, parametric analysis revealed intraindividual differences in contrast agent behavior in the small bowel region. Analogous to the computed tomography (CT) images parametric analysis showed regions of simultaneous hyper- and hypoperfusion of the small intestine in a subgroup of patients. In 5 patients, the parametric image of transmural global contrast enhancement was visualized.Our results using CEUS to investigate small bowel affection in COVID-19 suggest that in severe COVID-19 ARDS systemic inflammation and concomitant micro embolisms may lead to disruption of the epithelial barrier of the small intestine.This is the first study using parametric analysis of CEUS to evaluate the extent of small bowel involvement in severe COVID-19 disease and to detect microemboli. In summary, we show that in COVID-19 the small bowel may also be an important interaction site. This is in line with the fact that enterocytes have been shown to a plenitude of angiotensin converting enzyme (ACE)-2 receptors as entry sites of the virus.

Emerging toolset of three-dimensional pulmonary cell culture models for simulating lung pathophysiology towards mechanistic elucidation and therapeutic treatment of SARS-COV-2 infection

The ongoing COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) poses a never before seen challenge to human health and the world economy. However, it is difficult to widely use conventional animal and cell culture models in understanding the underlying pathological mechanisms of COVID-19, which in turn hinders the development of relevant therapeutic treatments, including drugs. To overcome this challenge, various three-dimensional (3D) pulmonary cell culture models such as organoids are emerging as an innovative toolset for simulating the pathophysiology occurring in the respiratory system, including bronchial airways, alveoli, capillary network, and pulmonary interstitium, which provide a robust and powerful platform for studying the process and underlying mechanisms of SARS-CoV-2 infection among the potential primary targets in the lung. This review introduces the key features of some of these recently developed tools, including organoid, lung-on-a-chip, and 3D bioprinting, which can recapitulate different structural compartments of the lung and lung function, in particular, accurately resembling the human-relevant pathophysiology of SARS-CoV-2 infection in vivo. In addition, the recent progress in developing organoids for alveolar and airway disease modeling and their applications for discovering drugs against SARS-CoV-2 infection are highlighted. These innovative 3D cell culture models together may hold the promise to fully understand the pathogenesis and eventually eradicate the pandemic of COVID-19.

Blood hyperviscosity in acute and recent COVID-19 infection

BACKGROUND

Elevated estimated blood viscosity (EBV), derived from hematocrit and globulins, is associated with thrombotic complications, organ failure, and higher mortality in COVID-19 patients. Although informative, EBV does not account for cellular interactions or fibrinogen.

OBJECTIVE

Investigate whether patients with acute and recent COVID-19 have altered whole blood viscosity (WBV) when measured at both high and low shear rates using in vitro blood samples from patients.

METHODS

Cross-sectional study of 58 patients: 15 in the intensive care unit with acute COVID-19, 32 convalescent (9 < 8weeks [W] from acute infection, 23 > 8 W), and 11 controls without COVID-19. WBV was measured at high (300 s-1) and low (5 s-1) shear rates (HSR, LSR) using a scanning capillary viscometer.RESULTSAcute and convalescent patients < 8 W had mean WBV at LSR (16.0 centipoise [cP] and 15.1 cP) and HSR (5.1 cP and 4.7 cP). Mean WBV of convalescent > 8 W and control patients were 12.3 cP and 13.0 cP at LSR, and 4.1 cP and 4.2 cP at HSR. Acute and < 8 W patients had significantly higher WBV at both HSR and LSR compared to patients > 8 W (all p≤0.01). No significant differences in WBV were observed between acute and < 8 W patients, or between patients > 8 W and controls.

CONCLUSIONS

Hyperviscosity provides a possible explanation for thrombotic risk in acute and convalescent (< 8 W) patients. These findings have important implications for thromboprophylaxis.

Vascular dysfunction in COVID-19 patients: update on SARS-CoV-2 infection of endothelial cells and the role of long non-coding RNAs

Although COVID-19 is primarily a respiratory disease, it may affect also the cardiovascular system. COVID-19 patients with cardiovascular disorder (CVD) develop a more severe disease course with a significantly higher mortality rate than non-CVD patients. A common denominator of CVD is the dysfunction of endothelial cells (ECs), increased vascular permeability, endothelial-to-mesenchymal transition, coagulation, and inflammation. It has been assumed that clinical complications in COVID-19 patients suffering from CVD are caused by SARS-CoV-2 infection of ECs through the angiotensin-converting enzyme 2 (ACE2) receptor and the cellular transmembrane protease serine 2 (TMPRSS2) and the consequent dysfunction of the infected vascular cells. Meanwhile, other factors associated with SARS-CoV-2 entry into the host cells have been described, including disintegrin and metalloproteinase domain-containing protein 17 (ADAM17), the C-type lectin CD209L or heparan sulfate proteoglycans (HSPG). Here, we discuss the current data about the putative entry of SARS-CoV-2 into endothelial and smooth muscle cells. Furthermore, we highlight the potential role of long non-coding RNAs (lncRNAs) affecting vascular permeability in CVD, a process that might exacerbate disease in COVID-19 patients.

Skin microcirculation reactivity to local thermal hyperaemia in patients with COVID-19 - A pilot observational study

BACKGROUND

Endothelial dysfunction and microvascular disturbances are suggested to play a key role in higher morbidity and worse prognosis in patients with COVID-19 and cardiometabolic diseases.

OBJECTIVE

Study was aimed to establish relationships between the skin microcirculation parameters and various clinical and laboratory indicators.

METHODS

The study included 18 patients with moderate disease according to WHO criteria. Skin microcirculation measurements were performed by laser Doppler flowmetry using a heating test on the hairy skin of the right forearm.

RESULTS

Baseline perfusion only correlated with C-reactive protein (Rs = 0.5, p = 0.034). Microcirculation indices characterising the development of hyperaemia during the first minute of heating (LTH1 and AUC60) showed significant correlations (Rs from 0.48 to 0.67, p < 0.05) with indices of general blood analysis and blood coagulation (fibrinogen, D-dimer, haemoglobin, erythrocyte count and haematocrit). Indexes characterising the dynamics of hyperaemia development over longer time intervals showed correlation with the glomerular filtration rate (Rs = 0.6, p = 0.009).

CONCLUSION

Known COVID-19 risk factors (haemorheological parameters, age) are correlated with the microvascular reactivity to heating in patients with COVID 19. We suggest that, prospectively, the method of laser Doppler flowmetry could be used for non-invasive instrumental assessment of microcirculatory disorders in patients with COVID-19.

Endothelial Poldip2 regulates sepsis-induced lung injury via Rho pathway activation

AIMS

Sepsis-induced lung injury is associated with significant morbidity and mortality. Previously, we showed that heterozygous deletion of polymerase δ-interacting protein 2 (Poldip2) was protective against sepsis-induced lung injury. Since endothelial barrier disruption is thought to be the main mechanism of sepsis-induced lung injury, we sought to determine if the observed protection was specifically due to the effect of reduced endothelial Poldip2.

METHODS AND RESULTS

Endothelial-specific Poldip2 knock-out mice (EC-/-) and their wild-type littermates (EC+/+) were injected with saline or lipopolysaccharide (18 mg/kg) to model sepsis-induced lung injury. At 18 h post-injection mice, were euthanized and bronchoalveolar lavage (BAL) fluid and lung tissue were collected to assess leucocyte infiltration. Poldip2 EC-/- mice showed reduced lung leucocyte infiltration in BAL (0.21 ± 0.9×106 vs. 1.29 ± 1.8×106 cells/mL) and lung tissue (12.7 ± 1.8 vs. 23 ± 3.7% neutrophils of total number of cells) compared to Poldip2 EC+/+ mice. qPCR analysis of the lung tissue revealed a significantly dampened induction of inflammatory gene expression (TNFα 2.23 ± 0.39 vs. 4.15 ± 0.5-fold, IκBα 4.32 ± 1.53 vs. 8.97 ± 1.59-fold), neutrophil chemoattractant gene expression (CXCL1 68.8 ± 29.6 vs. 147 ± 25.7-fold, CXCL2 65 ± 25.6 vs. 215 ± 27.3-fold) and a marker of endothelial activation (VCAM1 1.25 ± 0.25 vs. 3.8 ± 0.38-fold) in Poldip2 EC-/- compared to Poldip2 EC+/+ lungs. An in vitro model using human pulmonary microvascular endothelial cells was used to assess the effect of Poldip2 knock-down on endothelial activation and permeability. TNFα-induced endothelial permeability and VE-cadherin disruption were significantly reduced with siRNA-mediated knock-down of Poldip2 (5 ± 0.5 vs. 17.5 ± 3-fold for permeability, 1.5 ± 0.4 vs. 10.9 ± 1.3-fold for proportion of disrupted VE-cadherin). Poldip2 knock-down altered expression of Rho-GTPase-related genes, which correlated with reduced RhoA activation by TNFα (0.94 ± 0.05 vs. 1.29 ± 0.01 of relative RhoA activity) accompanied by redistribution of active-RhoA staining to the centre of the cell.

CONCLUSION

Poldip2 is a potent regulator of endothelial dysfunction during sepsis-induced lung injury, and its endothelium-specific inhibition may provide clinical benefit.

Central retinal vein occlusion and occlusive vasculopathy at macula in a patient with recent COVID-19 infection

We described a post-COVID-19 patient who presented with central retinal vein occlusion and macular ischemia. A 50-year-old male presented with decreased vision for a month in his right eye (RE). The patient had no systemic risk factors for vascular disease but recent COVID-19 infection. Fundus examination revealed dense intraretinal dot hemorrhages especially at macula and ischemia-related retinal whitening in the posterior pole in RE. Expanding of foveal avascular zone was also detected in optical coherence tomography angiography (OCTA) sections. After systemic steroid therapy, subretinal fluid resolved but visual acuity did not increase. Depending on the fundus fluorescein angiography and OCTA findings, clinical picture was compatible with previous central retinal vein occlusion with superimposed occlusive vasculopathy at macula. COVID-19 patients with visual problems must be considered with care in regard to thrombotic retinal diseases.

Cardiovascular/Stroke Risk Assessment in Patients with Erectile Dysfunction-A Role of Carotid Wall Arterial Imaging and Plaque Tissue Characterization Using Artificial Intelligence Paradigm: A Narrative Review

PURPOSE

The role of erectile dysfunction (ED) has recently shown an association with the risk of stroke and coronary heart disease (CHD) via the atherosclerotic pathway. Cardiovascular disease (CVD)/stroke risk has been widely understood with the help of carotid artery disease (CTAD), a surrogate biomarker for CHD. The proposed study emphasizes artificial intelligence-based frameworks such as machine learning (ML) and deep learning (DL) that can accurately predict the severity of CVD/stroke risk using carotid wall arterial imaging in ED patients.

METHODS

Using the PRISMA model, 231 of the best studies were selected. The proposed study mainly consists of two components: (i) the pathophysiology of ED and its link with coronary artery disease (COAD) and CHD in the ED framework and (ii) the ultrasonic-image morphological changes in the carotid arterial walls by quantifying the wall parameters and the characterization of the wall tissue by adapting the ML/DL-based methods, both for the prediction of the severity of CVD risk. The proposed study analyzes the hypothesis that ML/DL can lead to an accurate and early diagnosis of the CVD/stroke risk in ED patients. Our finding suggests that the routine ED patient practice can be amended for ML/DL-based CVD/stroke risk assessment using carotid wall arterial imaging leading to fast, reliable, and accurate CVD/stroke risk stratification.

SUMMARY

We conclude that ML and DL methods are very powerful tools for the characterization of CVD/stroke in patients with varying ED conditions. We anticipate a rapid growth of these tools for early and better CVD/stroke risk management in ED patients.

Endothelial glycocalyx damage in patients with severe COVID-19 on mechanical ventilation - a prospective observational pilot study

BACKGROUND

Coronavirus disease (COVID-19) associated endotheliopathy and microvascular dysfunction are of concern.

OBJECTIVE

The objective of the present single-center observational pilot study was to compare endothelial glycocalyx (EG) damage and endotheliopathy in patients with severe COVID-19 (COVID-19 group) with patients with bacterial pneumonia with septic shock (non-COVID group).

METHODS

Biomarkers of EG damage (syndecan-1), endothelial cells (EC) damage (thrombomodulin), and activation (P-selectin) were measured in blood on three consecutive days from admission to the intensive care unit (ICU). The sublingual microcirculation was studied by Side-stream Dark Field (SDF) imaging with automatic assessment.

RESULTS

We enrolled 13 patients in the non-COVID group (mean age 70 years, 6 women), and 15 in the COVID-19 group (64 years old, 3 women). The plasma concentrations of syndecan-1 were significantly higher in the COVID-19 group during all three days. Differences regarding other biomarkers were not statistically significant. The assessment of the sublingual microcirculation showed improvement on Day 2 in the COVID-19 group. Plasma levels of C-reactive protein (CRP) were significantly higher on the first two days in the COVID-19 group. Plasma syndecan-1 and CRP were higher in patients suffering from severe COVID-19 pneumonia compared to bacterial pneumonia patients.

CONCLUSIONS

These findings support the role of EG injury in the microvascular dysfunction in COVID-19 patients who require ICU.

MYTHS AND TRUTHS OF THE ASSOCIATION OF RETINAL VASCULAR OCCLUSION WITH COVID-19

PURPOSE

To critically review data published in the recent past to scrutinize a causal relationship between retinal vascular occlusion and COVID-19.

METHOD

A comprehensive literature search was performed on Pubmed with the key words retinal vascular occlusion, retinal vein occlusion, retinal artery occlusion, and COVID-19.

RESULTS

A total of 17 case reports were published during this period, and 10 were on retinal vein occlusion and 7 on retinal artery occlusion. Most of the published reports lacked convincing evidences in one or the other aspects, such as insufficient laboratory workup or presence of multiple confounding risk factors.

CONCLUSION

In this index article, strength of the data is insufficient to establish a definitive cause-and-effect relationship of retinal vascular occlusive disorders with COVID-19. Hence, clinicians can continue to manage these cases according to the standard guidelines until there are more robust evidences to support this association to alter the diagnostic and treatment modalities.

Contrast enhanced ultrasonography (CEUS) a novel tool to detect intestinal epithelial barrier dysfunction in severe COVID-19 disease

Ten patients with confirmed COVID-19 disease were studied. Nine patients required intensive care treatment, among them four needed extracorporeal membrane oxygenation (ECMO). Contrast enhanced ultrasonography (CEUS) was performed by one experienced investigator as a bolus injection of up to 2.4 ml of sulphur hexafluoride microbubbles via a central venous catheter. B-Mode evaluation and strain elastography showed mural edema of the small bowel with a thickness of up to 10 mm in all patients. We applied color coded Doppler sonography (CCDS) and power mode with flow-adapted parameters and early, dynamic capillary arterial contrast enhancement of bowel wall structures <10 s to assess perfusion of the small bowel. In all patients, reactive hyperemia was seen in the entire small bowel. In a subgroup of seven patients microbubbles translocated into the intestinal lumen. Thus, high-grade intestinal barrier disruption secondary to SARSCoV-2 infection can be postulated in these patients. This is the first description of perfusion changes and a disruption of the small bowel epithelial barrier in COVID-19 Patients using contrast ultrasonography and elastography.

A Deadly Embrace: Hemagglutination Mediated by SARS-CoV-2 Spike Protein at Its 22 N-Glycosylation Sites, Red Blood Cell Surface Sialoglycoproteins, and Antibody

Rouleaux (stacked clumps) of red blood cells (RBCs) observed in the blood of COVID-19 patients in three studies call attention to the properties of several enveloped virus strains dating back to seminal findings of the 1940s. For COVID-19, key such properties are: (1) SARS-CoV-2 binds to RBCs in vitro and also in the blood of COVID-19 patients; (2) although ACE2 is its target for viral fusion and replication, SARS-CoV-2 initially attaches to sialic acid (SA) terminal moieties on host cell membranes via glycans on its spike protein; (3) certain enveloped viruses express hemagglutinin esterase (HE), an enzyme that releases these glycan-mediated bindings to host cells, which is expressed among betacoronaviruses in the common cold strains but not the virulent strains, SARS-CoV, SARS-CoV-2 and MERS. The arrangement and chemical composition of the glycans at the 22 N-glycosylation sites of SARS-CoV-2 spike protein and those at the sialoglycoprotein coating of RBCs allow exploration of specifics as to how virally induced RBC clumping may form. The in vitro and clinical testing of these possibilities can be sharpened by the incorporation of an existing anti-COVID-19 therapeutic that has been found in silico to competitively bind to multiple glycans on SARS-CoV-2 spike protein.

Tip of the iceberg: erectile dysfunction and COVID-19

The novel severe acute respiratory syndrome coronavirus 2 caused the coronavirus 2019 (COVID-19) pandemic that resulted in more than 150 million infections and 3.5 million deaths globally. COVID-19 affected men more than women, emerging with more severe disease and higher mortality rates. Androgens may be responsible for the underlying reason of more severe disease, as androgen receptors have been implicated to mediate viral cell entry and infection. Besides, male reproductive organs have been reported to be affected by the especially severe disease, resulting in erectile dysfunction (ED). In this narrative review, we aimed to gather possible mechanisms of the development of ED led by COVID-19. Current evidence illuminates endothelial dysfunction, direct testicular damage, and the psychological burden of COVID-19 that are of the pathways of ED. Although the proposed underlying mechanisms partly fail to answer the questions by which COVID-19 leads to ED, it is important to monitor men who recovered from COVID-19 regarding the sexual dysfunction sequelae of infection and address the long‐term consequences.

Mechanisms contributing to adverse outcomes of COVID-19 in obesity

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

Endothelial cells and blood vessels are major targets for COVID-19-induced tissue injury and spreading to various organs

The coronavirus disease 2019 (COVID-19) infected so far over 250 million people and caused the death of over 5 million worldwide. Aging, diabetes, and cardiovascular diseases, conditions with preexisting impaired endothelial functions predispose to COVID-19. While respiratory epithelium is the main route of virus entry, the endothelial cells (ECs) lining pulmonary blood vessels are also an integral part of lung injury in COVID-19 patients. COVID-19 not only affects the lungs and respiratory system but also gastrointestinal (GI) tract, liver, pancreas, kidneys, heart, brain, and skin. Blood vessels are likely conduits for the virus dissemination to these distant organs. Importantly, ECs are also critical for vascular regeneration during injury/lesions healing and restoration of vascular network. The World Journal of Gastroenterology has published in last two years over 67 outstanding papers on COVID-19 infection with a focus on the GI tract, liver, pancreas, etc., however, the role of the endothelial and vascular components as major targets for COVID-19-induced tissue injury, spreading to various organs, and injury healing have not been sufficiently emphasized. In the present article, we focus on these subjects and on current treatments including the most recent oral drugs molnupiravir and paxlovid that show a dramatic, significant efficacy in controlling severe COVID-19 infection.

Ramatroban for chemoprophylaxis and treatment of COVID-19: David takes on Goliath

INTRODUCTION

In COVID-19 pneumonia, there is a massive increase in fatty acid levels and lipid mediators with a predominance of cyclooxygenase metabolites, notably TxB2 ≫ PGE2 > PGD2 in the lungs, and 11-dehydro-TxB2, a TxA2 metabolite, in the systemic circulation. While TxA2 stimulates thromboxane prostanoid (TP) receptors, 11-dehydro-TxB2 is a full agonist of DP2 (formerly known as the CRTh2) receptors for PGD2. Anecdotal experience of using ramatroban, a dual receptor antagonist of the TxA2/TP and PGD2/DP2 receptors, demonstrated rapid symptomatic relief from acute respiratory distress and hypoxemia while avoiding hospitalization.

AREAS COVERED

Evidence supporting the role of TxA2/TP receptors and PGD2/DP2 receptors in causing rapidly progressive lung injury associated with hypoxemia, a maladaptive immune response and thromboinflammation is discussed. An innovative perspective on the dual antagonism of TxA2/TP and PGD2/DP2 receptor signaling as a therapeutic approach in COVID-19 is presented. This paper examines ramatroban an anti-platelet, immunomodulator, and antifibrotic agent for acute and long-haul COVID-19.

EXPERT OPINION

Ramatroban, a dual blocker of TP and DP2 receptors, has demonstrated efficacy in animal models of respiratory dysfunction, atherosclerosis, thrombosis, and sepsis, as well as preliminary evidence for rapid relief from dyspnea and hypoxemia in COVID-19 pneumonia. Ramatroban merits investigation as a promising antithrombotic and immunomodulatory agent for chemoprophylaxis and treatment.

Kidney in the net of acute and long-haul coronavirus disease 2019: a potential role for lipid mediators in causing renal injury and fibrosis

PURPOSE OF REVIEW

Severe COVID-19 disease is often complicated by acute kidney injury (AKI), which may transition to chronic kidney disease (CKD). Better understanding of underlying mechanisms is important in advancing therapeutic approaches.

RECENT FINDINGS

SARS-CoV-2-induced endothelial injury initiates platelet activation, platelet-neutrophil partnership and release of neutrophil extracellular traps. The resulting thromboinflammation causes ischemia-reperfusion (I/R) injury to end organs. Severe COVID-19 induces a lipid-mediator storm with massive increases in thromboxane A2 (TxA2) and PGD2, which promote thromboinflammation and apoptosis of renal tubular cells, respectively, and thereby enhance renal fibrosis. COVID-19-associated AKI improves rapidly in the majority. However, 15-30% have protracted renal injury, raising the specter of transition from AKI to CKD.

SUMMARY

In COVID-19, the lipid-mediator storm promotes thromboinflammation, ischemia-reperfusion injury and cytotoxicity. The thromboxane A2 and PGD2 signaling presents a therapeutic target with potential to mitigate AKI and transition to CKD. Ramatroban, the only dual antagonist of the thromboxane A2/TPr and PGD2/DPr2 signaling could potentially mitigate renal injury in acute and long-haul COVID. Urgent studies targeting the lipid-mediator storm are needed to potentially reduce the heavy burden of kidney disease emerging in the wake of the current pandemic.

Metabolic Influences Modulating Erythrocyte Deformability and Eryptosis

Many factors in the surrounding environment have been reported to influence erythrocyte deformability. It is likely that some influences represent reversible changes in erythrocyte rigidity that may be involved in physiological regulation, while others represent the early stages of eryptosis, i.e., the red cell self-programmed death. For example, erythrocyte rigidification during exercise is probably a reversible physiological mechanism, while the alterations of red blood cells (RBCs) observed in pathological conditions (inflammation, type 2 diabetes, and sickle-cell disease) are more likely to lead to eryptosis. The splenic clearance of rigid erythrocytes is the major regulator of RBC deformability. The physicochemical characteristics of the surrounding environment (thermal injury, pH, osmolality, oxidative stress, and plasma protein profile) also play a major role. However, there are many other factors that influence RBC deformability and eryptosis. In this comprehensive review, we discuss the various elements and circulating molecules that might influence RBCs and modify their deformability: purinergic signaling, gasotransmitters such as nitric oxide (NO), divalent cations (magnesium, zinc, and Fe2+), lactate, ketone bodies, blood lipids, and several circulating hormones. Meal composition (caloric and carbohydrate intake) also modifies RBC deformability. Therefore, RBC deformability appears to be under the influence of many factors. This suggests that several homeostatic regulatory loops adapt the red cell rigidity to the physiological conditions in order to cope with the need for oxygen or fuel delivery to tissues. Furthermore, many conditions appear to irreversibly damage red cells, resulting in their destruction and removal from the blood. These two categories of modifications to erythrocyte deformability should thus be differentiated.

The Sexual Long COVID (SLC): Erectile Dysfunction as a Biomarker of Systemic Complications for COVID-19 Long Haulers

Introduction

Long term complications of COVID-19, the disease caused by the SARS-CoV-2, involve many organ systems, dramatically worsening the quality of life, and finally contributing to impaired physical functioning. Despite the presence of well-identified pathogenetic mechanisms, the effect of “Long COVID” on sexual health has been only marginally addressed.

Objectives

To provide coverage of the current literature on long COVID, its epidemiology, pathophysiology, and relevance for erectile function. Methods. Comprehensive review of literature pertaining to the epidemiology and pathophysiology of long COVID, and its relevance for erectile function.

Results

Symptoms of long COVID are highly prevalent and involve almost all systems of the human body, with a plethora of clinical manifestations which range from minor nuisances to life-threatening conditions. “Brain fog” and fatigue are the most common complaints, although other neuropsychiatric complications, including sensory dysfunctions, anxiety, depression, and cerebrovascular events have also been reported. The respiratory and cardiovascular systems are also affected, with dyspnea, pulmonary fibrosis, endothelial dysfunction, and myocarditis occurring in some COVID long haulers. A subset of patients might develop endocrine manifestations, including onset of diabetes, thyroid dysfunction, and hypogonadism. Overall, long COVID features many complications which can impair erectile function by multiple pathogenetic mechanisms, and which could require tailored treatment: (i) careful investigation and management from the sexual medicine expert are therefore much needed, (ii) and future research on this topic is warranted.

Conclusion

in COVID-19 long haulers, several complications can adversely affect erectile function which, upon future tailored studies, could be used as biomarker for the severity of the long COVID disease and for its follow-up.

Sansone A, Mollaioli D, Limoncin E et al. The Sexual Long COVID (SLC): Erectile Dysfunction as a Biomarker of Systemic Complications for COVID-19 Long Haulers. Sex Med Rev 2022;10:271–285.

Acute Invasive Fungal Rhinosinusitis and Coronavirus Disease 2019

ABSTRACT

Acute invasive fungal rhinosinusitis (mucormycosis) is a rare, highly fatal disease. This opportunistic fungal infection causes angioinvasion and ischemic tissue necrosis. It mainly affects immunocompromised patients. Since the coronavirus disease 2019 (COVID-19) outbreak, many case reports have described the rhino-orbital-cerebral mucormycosis associated with COVID-19. However, the underlying predisposing factors are unknown. Several factors, other than diabetes, which is the most well-known contributing factor, may be involved in causing this severe fungal infection in COVID-19 patients. These factors may include steroid therapy, which is being used in severely dyspneic patients, the use of broad-spectrum antibiotics that may cause fungal flare-ups, and hospitalization with possible nosocomial infections. In addition, increased serum ferritin levels, possible endothelial damage, and pancreatic islets affection among COVID-19 patients may be implicated. Head and neck surgeons should be aware of the increasing prevalence of craniofacial mucormycosis among COVID-19 patients, as early diagnosis and prompt treatment are essential to improve the outcomes.

Clinical correlation between coagulation disorders and sepsis in patients with liver failure

OBJECTIVE

This study aimed to explore the clinical detection and prognosis of coagulation function in patients with liver failure and sepsis.

METHODS

The plasma fibrinogen (FIB), factor II, factor VII, factor V, factor IV, antithrombin III (ATIII), platelet (PLT), mean PLT volume (MPV), D-dimer, prothrombin activity (PTA), and fibrin degradation product (FDP) levels and thromboelastogram values were detected in patients with liver failure complicated with sepsis and compared with those in the liver failure and liver cirrhosis groups. The patients with liver failure complicated with sepsis were analyzed by univariate and multivariate logistic regression, and the regression equation was established.

RESULTS

The levels of FIB, factor II, factor VII, factor V, ATIII, PLT, MPV, D-dimer, and FDP in the patients with liver failure complicated with sepsis were compared with those in the control group patients, and the differences were statistically significant (p <  0.05). Among the thromboelastography parameters in the patients with liver failure and sepsis, the differences in the K-value, R-value, angle, maximum amplitude, and coagulation index values compared with those of the control group were statistically significant (p <  0.05). The logistic regression model obtained was as follows: p = 1/(1 + e [-0.128×X1-0.058×X2 + 0.211×X3 + 0.2×X4 + 0.25]). The specificity, sensitivity, and accuracy values of the regression equation in determining the prognosis were 92%, 93.9%, and 92.8%, respectively. Among the 11 factors, factor VII, PLT, FDP, and D-dimer were included in the regression equation.

CONCLUSION

Coagulation disorder is exacerbated in patients with liver failure and sepsis. Among the 11 coagulation-related factors, factor VII, PLT, FDP, and D-dimer may be the independent factors influencing the prognosis of patients with acute liver failure and sepsis.

Effect of SARS-CoV-2 proteins on vascular permeability

Severe acute respiratory syndrome (SARS)-CoV-2 infection leads to severe disease associated with cytokine storm, vascular dysfunction, coagulation, and progressive lung damage. It affects several vital organs, seemingly through a pathological effect on endothelial cells. The SARS-CoV-2 genome encodes 29 proteins, whose contribution to the disease manifestations, and especially endothelial complications, is unknown. We cloned and expressed 26 of these proteins in human cells and characterized the endothelial response to overexpression of each, individually. Whereas most proteins induced significant changes in endothelial permeability, nsp2, nsp5_c145a (catalytic dead mutant of nsp5), and nsp7 also reduced CD31, and increased von Willebrand factor expression and IL-6, suggesting endothelial dysfunction. Using propagation-based analysis of a protein–protein interaction (PPI) network, we predicted the endothelial proteins affected by the viral proteins that potentially mediate these effects. We further applied our PPI model to identify the role of each SARS-CoV-2 protein in other tissues affected by coronavirus disease (COVID-19). While validating the PPI network model, we found that the tight junction (TJ) proteins cadherin-5, ZO-1, and β-catenin are affected by nsp2, nsp5_c145a, and nsp7 consistent with the model prediction. Overall, this work identifies the SARS-CoV-2 proteins that might be most detrimental in terms of endothelial dysfunction, thereby shedding light on vascular aspects of COVID-19.

A review of ischemic stroke in COVID-19: currently known pathophysiological mechanisms

Coronavirus disease 2019 (COVID-19), the third type of coronavirus pneumonia after severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), is spreading widely worldwide now. This pneumonia causes not only respiratory symptoms but also multiple organ dysfunction, including thrombotic diseases such as ischemic stroke. The purpose of this review is to explore whether COVID-19 is a risk factor for ischemic stroke and its related pathophysiological mechanisms. Based on the high thrombosis rate and frequent strokes of COVID-19 patients, combined with related laboratory indicators and pathological results, the discussion is mainly from two aspects: nerve invasion and endothelial dysfunction. SARS-CoV-2 can directly invade the CNS through blood-borne and neuronal retrograde pathways, causing cerebrovascular diseases. In addition, the endothelial dysfunction in COVID-19 is almost certain. Cytokine storm causes thromboinflammation, and downregulation of ACE2 leads to RAS imbalance, which eventually lead to ischemic stroke.

Is SARS-CoV-2 infection an emerging risk factor for splanchnic venous thrombosis?

OBJECTIVE

Thrombosis represents one of the most feared complications of the COronaVIrus Disease-2019 (COVID-19). Although pulmonary embolism and deep venous thrombosis are the most described complications, some investigations reported thrombotic localization also in the splanchnic venous district.

METHODS

We describe the case of a patient with SARS-CoV-2 infection presenting with abdominal pain and diagnosed with portal vein thrombosis. In addition, we shortly review available literature supporting the possible role of COVID-19 as leading cause of splanchnic venous thrombosis.

RESULTS

After in-depth diagnostic workup, we excluded the commonest causes of portal thrombosis and concluded that SARS-CoV-2 infection represented the main explanation of this finding.

CONCLUSIONS

Our study warns the clinicians to maintain a high index of suspicion for thrombosis in patients diagnosed with SARS-CoV-2 infection manifesting gastrointestinal symptoms. An appropriate diagnostic work-up could allow to obtain an early diagnosis and consequently improve the clinical outcome of patients.

Endothelial Cell Activation by SARS-CoV-2 Spike S1 Protein: A Crosstalk between Endothelium and Innate Immune Cells

Background. Emerging evidences suggest that in severe COVID-19, multi-organ failure is associated with a hyperinflammatory state (the so-called “cytokine storm”) in combination with the development of a prothrombotic state. The central role of endothelial dysfunction in the pathogenesis of the disease is to date accepted, but the precise mechanisms underlying the associated coagulopathy remain unclear. Whether the alterations in vascular homeostasis directly depend upon the SARS-CoV-2 infection of endothelial cells or, rather, occur secondarily to the activation of the inflammatory response is still a matter of debate. Here, we address the effect of the SARS-CoV-2 spike S1 protein on the activation of human lung microvascular endothelial cells (HLMVEC). In particular, the existence of an endothelium-macrophage crosstalk in the response to the spike protein has been explored. Methods and Results. The effect of the spike protein is addressed in human lung microvascular endothelial cells (HLMVEC), either directly or after incubation with a conditioned medium (CM) of human monocyte-derived macrophages (MDM) previously activated by the spike S1 protein (CM-MDM). Both MDM and HLMVEC are activated in response to the S1 protein, with an increased expression of pro-inflammatory mediators. However, when HLMVEC are exposed to CM-MDM, an enhanced cell activation occurs in terms of the expression of adhesion molecules, pro-coagulant markers, and chemokines. Under this experimental condition, ICAM-1 and VCAM-1, the chemokines CXCL8/IL-8, CCL2/MCP1, and CXCL10/IP-10 as well as the protein tissue factor (TF) are markedly induced. Instead, a decrease of thrombomodulin (THBD) is observed. Conclusion. Our data suggest that pro-inflammatory mediators released by spike-activated macrophages amplify the activation of endothelial cells, likely contributing to the impairment of vascular integrity and to the development of a pro-coagulative endothelium.

Early evaluation of organ failure using MELD-XI in critically ill elderly COVID-19 patients

PURPOSECritically ill elderly patients who suffer from Sars-CoV-2 disease are at high risk for organ failure. The modified MELD-XI score has not been evaluated for outcome prediction in these most vulnerable patients.METHODSThe Corona Virus disease (COVID19) in Very Elderly Intensive Care Patients study (COVIP, NCT04321265) prospectively recruited patients on intensive care units (ICU), who were = 70 years. Data were collected from March 2020 to February 2021. The MELD-XI score was calculated using the highest serum bilirubin and creatinine on ICU admission. Univariate and multivariable logistic regression analyses were performed to assess associations between the MELD-XI score and mortality. The primary outcome was 30-day-mortality, the secondary outcomes were ICU- and 3-month-mortality.RESULTSIn total, data from 2,993 patients were analyzed. Most patients had a MELD-XI <12 on admission (76%). The patients with MELD-XI = 12 had a significantly higher 30-day-, ICU- and 3-month-mortality (44%vs 64%, and 42%vs. 59%, and 57%vs. 76%, p < 0.001). After adjustment for multiple confounders, MELD-XI = 12 remained significantly associated with 30-day- (aOR 1.572, CI 1.268-1.949, p < 0.001), ICU-, and 3-month-mortality.CONCLUSIONIn critically ill elderly intensive care patients with COVID-19, the MELD-XI score constitutes a valuable tool for an early outcome prediction.

Endothelial Dysfunction, Inflammation, and Oxidative Stress in COVID-19-Mechanisms and Therapeutic Targets

The outbreak of the COVID-19 pandemic represents an ongoing healthcare emergency responsible for more than 3.4 million deaths worldwide. COVID-19 is the disease caused by SARS-CoV-2, a virus that targets not only the lungs but also the cardiovascular system. COVID-19 can manifest with a wide range of clinical manifestations, from mild symptoms to severe forms of the disease, characterized by respiratory failure due to severe alveolar damage. Several studies investigated the underlying mechanisms of the severe lung damage associated with SARS-CoV-2 infection and revealed that the respiratory failure associated with COVID-19 is the consequence not only of acute respiratory distress syndrome but also of macro- and microvascular involvement. New observations show that COVID-19 is an endothelial disease, and the consequent endotheliopathy is responsible for inflammation, cytokine storm, oxidative stress, and coagulopathy. In this review, we show the central role of endothelial dysfunction, inflammation, and oxidative stress in the COVID-19 pathogenesis and present the therapeutic targets deriving from this endotheliopathy.

In vitro effects of temperature on red blood cell deformability and membrane stability in human and various vertebrate species

BACKGROUND

The effects of temperature on micro-rheological variables have not been completely revealed yet.

OBJECTIVE

To investigate micro-rheological effects of heat treatment in human, rat, dog, and porcine blood samples.

METHODS

Red blood cell (RBC) - buffer suspensions were prepared and immersed in a 37, 40, and 43°C heat-controlled water bath for 10 minutes. Deformability, as well as mechanical stability of RBCs were measured in ektacytometer. These tests were also examined in whole blood samples at various temperatures, gradually between 37 and 45°C in the ektacytometer.

RESULTS

RBC deformability significantly worsened in the samples treated at 40 and 43°C, more expressed in human, porcine, rat, and in smaller degree in canine samples. The way of heating (incubation vs. ektacytometer temperation) and the composition of the sample (RBC-PBS suspension or whole blood) resulted in the different magnitude of RBC deformability deterioration. Heating affected RBC membrane (mechanical) stability, showing controversial alterations.

CONCLUSION

Significant changes occur in RBC deformability by increasing temperature, showing inter-species differences. The magnitude of alterations is depending on the way of heating and the composition of the sample. The results may contribute to better understanding the micro-rheological deterioration in hyperthermia or fever.

Application of extracorporeal carbon dioxide removal combined with continuous blood purification therapy in ARDS with hypercapnia in patients with critical COVID-19

INTRODUCTION

Coronavirus disease-19 (COVID-19) is a new type of epidemic pneumonia caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The population is generally susceptible to COVID-19, which mainly causes lung injury. Some cases may develop severe acute respiratory distress syndrome (ARDS). Currently, ARDS treatment is mainly mechanical ventilation, but mechanical ventilation often causes ventilator-induced lung injury (VILI) accompanied by hypercapnia in 14% of patients. Extracorporeal carbon dioxide removal (ECCO2R) can remove carbon dioxide from the blood of patients with ARDS, correct the respiratory acidosis, reduce the tidal volume and airway pressure, and reduce the incidence of VILI.

CASE REPORT

Two patients with critical COVID-19 combined with multiple organ failure undertook mechanical ventilation and suffered from hypercapnia. ECCO2R, combined with continuous renal replacement therapy (CRRT), was conducted concomitantly. In both cases (No. 1 and 2), the tidal volume and positive end-expiratory pressure (PEEP) were down-regulated before the treatment and at 1.5 hours, one day, three days, five days, eight days, and ten days after the treatment, together with a noticeable decrease in PCO2 and clear increase in PO2, while FiO2 decreased to approximately 40%. In case No 2, compared with the condition before treatment, the PCO2 decreased significantly with down-regulation in the tidal volume and PEEP and improvement in the pulmonary edema and ARDS after the treatment.

CONCLUSION

ECCO2R combined with continuous blood purification therapy in patients with COVID-19 who are criti-cally ill and have ARDS and hypercapnia might gain both time and opportunity in the treatment, down-regulate the ventilator parameters, reduce the incidence of VILI and achieve favorable therapeutic outcomes.

The Endothelial Glycocalyx as a Double-Edged Sword in Microvascular Homeostasis and Pathogenesis

Expressed on the endothelial cell (EC) surface of blood vessels, the glycocalyx (GCX), a mixture of carbohydrates attached to proteins, regulates the access of cells and molecules in the blood to the endothelium. Besides protecting endothelial barrier integrity, the dynamic microstructure of the GCX confers remarkable functions including mechanotransduction and control of vascular tone. Recently, a novel perspective has emerged supporting the pleiotropic roles of the endothelial GCX (eGCX) in cardiovascular health and disease. Because eGCX degradation occurs in certain pathological states, the circulating levels of eGCX degradation products have been recognized to have diagnostic or prognostic values. Beyond their biomarker roles, certain eGCX fragments serve as pathogenic factors in disease progression. Pharmacological interventions that attenuate eGCX degradation or restore its integrity have been sought. This review provides our current understanding of eGCX structure and function across the microvasculature in different organs. We also discuss disease or injury states, such as infection, sepsis and trauma, where eGCX dysfunction contributes to severe inflammatory vasculopathy.

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.

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.

COVID-19 and Delayed Cerebral Ischemia-More in Common Than First Meets the Eye

Since the arrival of the global COVID-19 pandemic scientists around the world have been working to understand the pathological mechanisms resulting from infection. There has gradually been an understanding that COVID-19 triggers a widespread endotheliopathy and that this can result in a widespread thrombosis and in particular a microthrombosis. The mechanisms involved in the microthrombosis are not confined to infection and there is evidence that patients with aneurysmal sub-arachnoid haemorrhage (SAH) also suffer from an endotheliopathy and microthrombosis. In this article we attempt to shed light on similarities in the underlying processes involved in both diseases and suggest potential treatment options.

Preventive effects of Pycnogenol® on cardiovascular risk factors (including endothelial function) and microcirculation in subjects recovering from coronavirus disease 2019 (COVID-19)

BACKGROUND

The aim of this open supplement study was to evaluate the effects of Pycnogenol® in comparison with controls on symptoms of post-COVID-19 syndrome and in improving endothelial function, microcirculation, inflammatory markers and oxidative stress over 3 months in symptomatic subjects recovering from COVID-19.

METHODS

Sixty subjects recovering from symptomatic COVID-19 were included. One group of 30 followed a standard recovery management while 30 comparable subjects received a supplement of 150 mg Pycnogenol® daily (in 3 doses of 50 mg) in addition to standard management.

RESULTS

Two groups of selected subjects were comparable at baseline. The groups progressively improved both with the SM (standard management) and with the SM in combination with the supplement. Patients, supplemented with Pycnogenol® showed significantly better improvement compared to the control group patients. No side effects from the supplementation were observed; tolerability was optimal. The progressive evolution over time was visible in all target measurements. Physiological tests. Endothelial function, low in all subjects at inclusion was assessed by flow mediated dilation (FMD) and finger reactive hyperemia in the microcirculation (laser Doppler measurements) after the release of an occluding suprasystolic cuff). It was significantly improved in the Pycnogenol® group after one month and after 3 months (p<0.05 vs controls). The rate of ankle swelling (RAS) by strain gauge decreased significantly in the supplemented group (p<0.05) in comparison with controls showing an improvement of the capillary filtration rate. At inclusion, the kidney cortical flow velocity indicated a decrease in perfusion (lower systolic and diastolic flow velocity) in all patients. Kidney cortical flow velocity increased significantly with the supplement (p<0.05) in comparison with controls with improvement in systolic velocity and in diastolic component. High sensitivity CRP (hs-CRP) and Il-6 plasma levels decreased progressively over 3 months with a significant more pronounced decrease in the supplement group (p<0.05). The number of patients with normal plasma IL-6 levels at the end of the study was higher (p<0,05) with the supplement. ESR followed the same pattern with a progressive and a more significant decrease in the supplemented subjects (p<0.02). Oxidative stress decreased significantly in the supplemented group (p<0.05) compared with the control group. Blood pressure and heart rate were normalized in all subjects in the supplement group; systolic pressure was significantly lower in the supplemented group (p<0,05) at the end of the study. Finally, the scores of Quality-of-life, mood and fatigue questionnaire and the Karnofsky scale performance index significantly improved in the supplement group (p<0.05) compared to controls after 1 and 3 months. All other blood parameters (including platelets and clotting factors) were within normal values at the end of the study.

CONCLUSIONS

In conclusion, Pycnogenol® may offer a significant option for managing some of the signs and symptoms associated with post-COVID-19 syndrome. This pilot evaluation offers some potential rationale for the use of Pycnogenol® in this condition that will have significant importance in the coming years.

A potential association between immunosenescence and high COVID-19 related mortality among elderly patients with cardiovascular diseases

Elderly patients with cardiovascular diseases account for a large proportion of Corona virus Disease 2019(COVID-19)related deaths. COVID-19, as a new coronavirus, mainly targets the patient's lung triggering a cascade of innate and adaptive immune responses in the host. The principal causes of death among COVID-19 patients, especially elderly subjects with cardiovascular diseases, are acute respiratory distress syndrome(ARDS), multiple organ dysfunction syndrome (MODS), and microvascular thrombosis. All prompted by an excessive uncontrolled systemic inflammatory response. Immunosenescence, characterized by systemic and chronic inflammation as well as innate/adaptive immune imbalance, presents both in the elderly and cardiovascular patients. COVID-19 infection further aggravates the existing inflammatory process and lymphocyte depletion leading to uncontrollable systemic inflammatory responses, which is the primary cause of death. Based on the higher mortality, this study attempts to elucidate the pathophysiological mechanisms of COVID-19 in elderly subjects with cardiovascular diseases as well as the cause of the high mortality result from COVID-19.

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.

Interstitial lung opacities in patients with severe COVID-19 pneumonia by bedside high-resolution ultrasound in association to CO2 retention

BACKGROUND

Coronavirus disease 2019 (COVID-19) can cause acute respiratory distress syndrome (ARDS).

OBJECTIVE

This single centre cross-section study aimed to grade the severity of pneumonia by bed-side lung ultrasound (LUS).

METHODS

A scoring system discriminates 5 levels of lung opacities: A-lines (0 points),≥3 B-line (1 point), coalescent B-lines (2 points), marked pleural disruptions (3 points), consolidations (4 points). LUS (convex 1-5 MHz probe) was performed at 6 defined regions for each hemithorax either in supine or prone position. A lung aeration score (LAS, maximum 4 points) was allocated for each patient by calculating the arithmetic mean of the examined lung areas. Score levels were correlated with ventilation parameters and laboratory markers.

RESULTS

LAS of 20 patients with ARDS reached from 2.58 to 3.83 and was highest in the lateral right lobe (Mean 3.67). Ferritin levels (Mean 1885μg/l; r = 0.467; p = 0.051) showed moderate correlation in spearman roh calculation. PaCO2 level (Mean 46.75 mmHg; r = 0.632; p = 0.005) correlated significantly with LAS, while duration of ventilation, Horovitz index, CRP, LDH and IL-6 did not.

CONCUSIONS

The proposed LAS describes severity of lung opacities in COVID-19 patients and correlates with CO2 retention in patients with ARDS.

Elevated fibrinogen and fibrin degradation product are associated with poor outcome in COVID-19 patients: A meta-analysis

INTRODUCTION

COVID-19 is a systemic infection with a significant impact on coagulation which manifests in thromboembolism. There is an unknown relationship of which coagulation profile parameter at presentation has an association with poor outcome in COVID-19.

OBJECTIVE

This meta-analysis aimed to determine the relationship between fibrinogen and FDP with poor outcome in COVID-19 patients.

METHODS

A systematic search of all observational studies or trials involving adult patients with COVID-19 that had any data fibrinogen or FDP on admission was carried out using the PubMed, Science Direct, Scopus, ProQuest, and MedRxiv databases. We assessed the methodological quality assessment using the NIH Quality Assessment Tool. We performed random-effects inverse-variance weighting analysis using mean difference (MD).

RESULTS

A total of 17 studies (1,654 patients) were included in this meta-analysis. It revealed a higher mean of fibrinogen levels on admission in patients with severe case compared to those with non-severe case (MD = 0.69, [95% CI: 0.44 to 0.94], p < 0.05; I2 = 72%, p < 0.05). Non-survivor group had a pooled higher mean difference of fibrinogen values on admission (MD = 0.48 [95% CI: 0.13 to 0.83], p < 0.05; I2 = 38%, p = 0.18). Higher FDP on admission was found in poor outcome (composite of severity, critically ill, and mortality) compared to good outcome (4 studies, MD = 4.84 [95% CI: 0.75 to 8.93], p < 0.05; I2 = 86%, p < 0.05).

CONCLUSION

Elevated fibrinogen and FDP level on admission were associated with an increase risk of poor outcome in COVID-19 patients.