Arterial priapism in dengue: A case report and literature review.

Arterial priapism, rare and often traumatic, is generally associated with cavernous arterial lesions. We report an unprecedented case in a 17-year-old adolescent, occurring spontaneously after severe dengue, expanding the understanding of this pathology. No similar association has been previously documented in the literature. The patient was successfully treated with conservative measures, and erections returned to normal. Dengue, by causing vascular leaks, could be a rare trigger for arterial priapism. Further studies are needed to elucidate these mechanisms and potential clinical implications.

Vascular senescence and leak are features of the early breakdown of the blood-brain barrier in Alzheimer's disease models.

Alzheimer's disease (AD) is an age-related disease, with loss of integrity of the blood-brain barrier (BBB) being an early feature. Cellular senescence is one of the reported nine hallmarks of aging. Here, we show for the first time the presence of senescent cells in the vasculature in AD patients and mouse models of AD. Senescent endothelial cells and pericytes are present in APP/PS1 transgenic mice but not in wild-type littermates at the time of amyloid deposition. In vitro, senescent endothelial cells display altered VE-cadherin expression and loss of cell junction formation and increased permeability. Consistent with this, senescent endothelial cells in APP/PS1 mice are present at areas of vascular leak that have decreased claudin-5 and VE-cadherin expression confirming BBB breakdown. Furthermore, single cell sequencing of endothelial cells from APP/PS1 transgenic mice confirms that adhesion molecule pathways are among the most highly altered pathways in these cells. At the pre-plaque stage, the vasculature shows significant signs of breakdown, with a general loss of VE-cadherin, leakage within the microcirculation, and obvious pericyte perturbation. Although senescent vascular cells were not directly observed at sites of vascular leak, senescent cells were close to the leak area. Thus, we would suggest in AD that there is a progressive induction of senescence in constituents of the neurovascular unit contributing to an increasing loss of vascular integrity. Targeting the vasculature early in AD, either with senolytics or with drugs that improve the integrity of the BBB may be valid therapeutic strategies.

Pericyte Loss in Diseases.

Pericytes are specialized cells located in close proximity to endothelial cells within the microvasculature. They play a crucial role in regulating blood flow, stabilizing vessel walls, and maintaining the integrity of the blood-brain barrier. The loss of pericytes has been associated with the development and progression of various diseases, such as diabetes, Alzheimer's disease, sepsis, stroke, and traumatic brain injury. This review examines the detection of pericyte loss in different diseases, explores the methods employed to assess pericyte coverage, and elucidates the potential mechanisms contributing to pericyte loss in these pathological conditions. Additionally, current therapeutic strategies targeting pericytes are discussed, along with potential future interventions aimed at preserving pericyte function and promoting disease mitigation.

Spleen Tyrosine Kinase phosphorylates VE-cadherin to cause endothelial barrier disruption in acute lung injury.

Increased endothelial cell (EC) permeability is a cardinal feature of acute lung injury/acute respiratory distress syndrome (ALI/ARDS). Tyrosine phosphorylation of VE-cadherin is a key determinant of EC barrier disruption. However, the identity and role of tyrosine kinases in this context are incompletely understood. Here we report that Spleen Tyrosine Kinase (Syk) is a key mediator of EC barrier disruption and lung vascular leak in sepsis. Inhibition of Syk by pharmacological or genetic approaches, each reduced thrombin-induced EC permeability. Mechanistically, Syk associates with and phosphorylates VE-cadherin to cause EC permeability. To study the causal role of endothelial Syk in sepsis-induced ALI, we used a remarkably efficient and cost-effective approach based on gene transfer to generate EC-ablated Syk mice. These mice were protected against sepsis-induced loss of VE-cadherin and inflammatory lung injury. Notably, the administration of Syk inhibitor R788 (fostamatinib); currently in phase II clinical trial for the treatment of COVID-19, mitigated lung injury and mortality in mice with sepsis. These data identify Syk as a novel kinase for VE-cadherin and a druggable target against ALI in sepsis.

Molecular Determinants of Tissue Specificity of Flavivirus Nonstructural Protein 1 Interaction with Endothelial Cells.

Members of the mosquito-borne flavivirus genus such as dengue (DENV), West Nile (WNV), and Zika (ZIKV) viruses cause distinct diseases and affect different tissues. We previously found that the secreted flaviviral nonstructural protein 1 (NS1) interacts with endothelial cells and disrupts endothelial barrier function in a tissue-specific manner consistent with the disease tropism of the respective viruses. However, the underlying molecular mechanism of this tissue-specific NS1-endothelial cell interaction is not well understood. To elucidate the distinct role(s) that the wing and ß-ladder domains of NS1 play in NS1 interactions with endothelial cells, we constructed flavivirus NS1 chimeras that exchanged the wing and ß-ladder domains in a pairwise manner between DENV, WNV, and ZIKV NS1. We found that both the NS1 wing and ß-ladder domains conferred NS1 tissue-specific endothelial dysfunction, with the wing conferring cell binding and the ß-ladder involved in inducing endothelial hyperpermeability as measured by transendothelial electrical resistance. To narrow down the amino acids dictating cell binding specificity, we utilized the DENV-WNV NS1 chimera and identified residues 91 to 93 (GDI) of DENV NS1 as a molecular motif determining binding specificity. Further, using an in vivo mouse model of localized leak, we found that the GDI motif of the wing domain was essential for triggering DENV NS1-induced vascular leak in mouse dermis. Taken together, we identify molecular determinants of flavivirus NS1 that confer NS1 binding and vascular leak and highlight the importance of the NS1 wing domain for flavivirus pathogenesis. IMPORTANCE Flavivirus NS1 is secreted into the bloodstream from infected cells during a viral infection. Dengue virus NS1 contributes to severe dengue pathology such as endothelial dysfunction and vascular leak independently of the virus. We have shown that multiple flavivirus NS1 proteins result in endothelial dysfunction in a tissue-specific manner consistent with their respective viral tropism. Here, we aimed to identify the molecular determinants that make some, but not other, flavivirus NS1 proteins bind to select endothelial cells in vitro and cause vascular leak in a mouse model. We identified the wing domain of NS1 as a primary determinant conferring differential endothelial dysfunction and vascular leak and narrowed the contributing amino acid residues to a three-residue motif within the wing domain. The insights from this study pave the way for future studies on the effects of flavivirus NS1 on viral dissemination and pathogenesis and offer potential new avenues for antiviral therapies.

Sulfated ß-glucan from Agaricus subrufescens inhibits flavivirus infection and nonstructural protein 1-mediated pathogenesis.

Despite substantial morbidity and mortality, no therapeutic agents exist for treatment of dengue or Zika, and the currently available dengue vaccine is only recommended for dengue virus (DENV)-immune individuals. Thus, development of therapeutic and/or preventive drugs is urgently needed. DENV and Zika virus (ZIKV) nonstructural protein 1 (NS1) can directly trigger endothelial barrier dysfunction and induce inflammatory responses, contributing to vascular leak in vivo. Here we evaluated the efficacy of the (1-6,1-3)-ß-D-glucan isolated from Agaricus subrufescens fruiting bodies (FR) and its sulfated derivative (FR-S) against DENV-2 and ZIKV infection and NS1-mediated pathogenesis. FR-S, but not FR, significantly inhibited DENV-2 and ZIKV replication in human monocytic cells (EC50 = 36.5 and 188.7 µg/mL, respectively) when added simultaneously with viral infection. No inhibitory effect was observed when FR or FR-S were added post-infection, suggesting inhibition of viral entry as a mechanism of action. In an in vitro model of endothelial permeability using human pulmonary microvascular endothelial cells (HPMECs), FR and FR-S (0.12 µg/mL) inhibited DENV-2 NS1- and ZIKV NS1-induced hyperpermeability by 50% and 100%, respectively, as measured by Trans-Endothelial Electrical Resistance. Treatment with 0.25 µg/mL of FR and FR-S inhibited DENV-2 NS1 binding to HPMECs. Further, FR-S significantly reduced intradermal hyperpermeability induced by DENV-2 NS1 in C57BL/6 mice and protected against DENV-induced morbidity and mortality in a murine model of dengue vascular leak syndrome. Thus, we demonstrate efficacy of FR-S against DENV and ZIKV infection and NS1-induced endothelial permeability in vitro and in vivo. These findings encourage further exploration of FR-S and other glycan candidates for flavivirus treatment alone or in combination with compounds with different mechanisms of action.

Dengue NS1 induces phospholipase A2 enzyme activity, prostaglandins, and inflammatory cytokines in monocytes.

INTRODUCTION: Dengue virus (DENV) NS1 is a non-structural secretory protein associated with severe disease and known to cause vascular leak leading to dengue haemorrhagic fever (DHF). As phospholipases A2 (PLA2) enzymes, platelet activating factor, and leukotrienes are elevated in dengue, we sought to investigate whether NS1 potentially contributes to disease pathogenesis by inducing PLA2s. METHODS: THP-1 cells and primary human monocytes of healthy adults (n = 6) were co-cultured with DENV1 NS1, LPS and media alone. The latter two were used as positive and negative controls. The cell culture supernatants and lysates were harvested at 12 and 24 h and the activity of secretory and cytoplasmic PLA2, prostaglandins (PGE2 and PGD2) were measured by ELISA and cytokines levels were measured using a magnetic Luminex assay. Expression of PLA2G4A, PLA2G2A, PLA2G5, PLA2G10, PLA2G7, GAPDH, NLRP3 and DDX58 genes were assessed using quantitative RT-PCR. RESULTS: cPLA2 (p = 0.005), sPLA2 (p = 0.04), PGE2 metabolite (p = 0.02) and PGD2 metabolite (p = 0.04) levels were significantly higher at 12 h in monocytes co-cultured with NS1. Levels of IP-10 (p = 0.005) and IL-10 (p = 0.009) was significantly higher at 24 h, whereas IFNα level was significantly higher (p = 0.013) only at 12 h. IL-1ß (p = 0.028 and p = 0.031) and TNFα (p = 0.007 and p = 0.011) showed significantly higher levels at both time points. At 12 h significant upregulation of PLA2G4A (p < 0.0001) was seen, whereas PLA2G7 (p = <0.0001), NLRP3 (p = 0.0009) and DDX58 (p = 0.0056) were significantly downregulated. This pattern changed at 24 h with PLA2G4A (p = 0.0069) showing a marked downregulation and PLA2G7, DDX58 and NLRP3 showing an upregulation, although not significant. CONCLUSION: Dengue NS1 induces the production of PLA2 enzymes, prostaglandins and inflammatory cytokines from primary human monocytes, which could play a role in vascular leak in dengue.

A novel Vascular Leak Index identifies sepsis patients with a higher risk for in-hospital death and fluid accumulation.

PURPOSE: Sepsis is a leading cause of morbidity and mortality worldwide and is characterized by vascular leak. Treatment for sepsis, specifically intravenous fluids, may worsen deterioration in the context of vascular leak. We therefore sought to quantify vascular leak in sepsis patients to guide fluid resuscitation. METHODS: We performed a retrospective cohort study of sepsis patients in four ICU databases in North America, Europe, and Asia. We developed an intuitive vascular leak index (VLI) and explored the relationship between VLI and in-hospital death and fluid balance using generalized additive models (GAM). RESULTS: Using a GAM, we found that increased VLI is associated with an increased risk of in-hospital death. Patients with a VLI in the highest quartile (Q4), across the four datasets, had a 1.61-2.31 times increased odds of dying in the hospital compared to patients with a VLI in the lowest quartile (Q1). VLI Q2 and Q3 were also associated with increased odds of dying. The relationship between VLI, treated as a continuous variable, and in-hospital death and fluid balance was statistically significant in the three datasets with large sample sizes. Specifically, we observed that as VLI increased, there was increase in the risk for in-hospital death and 36-84 h fluid balance. CONCLUSIONS: Our VLI identifies groups of patients who may be at higher risk for in-hospital death or for fluid accumulation. This relationship persisted in models developed to control for severity of illness and chronic comorbidities.

Kinase signaling as a drug target modality for regulation of vascular hyperpermeability: A case for ARDS therapy development.

The endothelial vascular permeability barrier has an important role throughout the body's extensive vasculature, and its disruption leads to vascular hyperpermeability (leakage), which is associated with numerous medical conditions. In the lung, vascular hyperpermeability can lead to pulmonary edema and acute respiratory distress syndrome (ARDS), the most severe and deadly complication of viral and bacterial infections, trauma and radiation exposure. There is currently no pharmacological treatment for ARDS with the only approved options being focused on supportive care. The development of effective treatments for ARDS has a potential to turn infectious diseases such as bacterial and viral pneumonia (including COVID-19) into manageable conditions, saving lives and providing a new tool to combat future epidemics. Strategies that aim to protect and augment the vascular endothelial barrier are important avenues to consider as potential treatments for ARDS and other conditions underlined by vascular hyperpermeability. We propose the activation of the MAPKAPK2 (MK2) kinase pathway as a new approach to augment the endothelial barrier and prevent or reverse ARDS and other conditions characterized by vascular barrier dysfunction.

The impact of chronic mild hypoxia on cerebrovascular remodelling; uncoupling of angiogenesis and vascular breakdown.

BACKGROUND: Chronic mild hypoxia (CMH, 8% O2) stimulates robust vascular remodelling in the brain, but it also triggers transient vascular disruption. This raises the fundamental question: is the vascular leak an unwanted side-effect of angiogenic remodelling or is it a pathological response, unrelated to endothelial proliferation, in which declining oxygen levels trigger endothelial dysfunction? METHODS: To answer this question, mice were exposed to CMH (8% O2) for periods up to 14 days, after which, brain tissue was examined by immunofluorescence (IF) to determine which type of blood vessel (arteriole, capillary or venule) was most commonly associated with endothelial proliferation and vascular leak and how this correlated with tight junction protein expression. Vascular perfusion was examined using DiI. Data were analysed using one-way analysis of variance (ANOVA) followed by Tukey's multiple comparison post-hoc test. RESULTS: The following was observed: (1) most endothelial proliferation and extravascular fibrinogen leak occurred in capillaries and to a lesser degree in venules, (2) much to our surprise, endothelial proliferation and extravascular fibrinogen leak never colocalized, (3) interestingly however, endothelial proliferation was strongly associated with an intravascular fibrinogen staining pattern not seen in stable blood vessels, (4) DiI perfusion studies revealed that angiogenic vessels were adequately perfused, suggesting that fibrinogen retention in angiogenic vessels is not due to temporary closure of the vessel, but more likely because fibrinogen is retained within the vessel wall, (5) bromodeoxyuridine (BrdU) labelling as a means to more permanently label proliferating endothelial cells, confirmed lack of any connection between endothelial proliferation and extravascular fibrinogen leak, while (6) in contrast, proliferating microglia were detected within extravascular leaks. CONCLUSIONS: Taken together, our findings support the concept that in the short-term, hypoxia-induced endothelial proliferation triggers transient fibrinogen deposition within the walls of angiogenic blood vessels, but no overt vascular leak occurs in these vessels. Importantly, endothelial proliferation and extravascular fibrinogen leaks never co-localize, demonstrating that extravascular leak is not an unwanted side-effect of angiogenic endothelial proliferation, but rather a dysfunctional vascular response to hypoxia that occurs in a distinct group of non-angiogenic blood vessels.

Ultrasound and Microbubbles for Targeted Drug Delivery to the Lung Endothelium in ARDS: Cellular Mechanisms and Therapeutic Opportunities.

Acute respiratory distress syndrome (ARDS) is characterized by increased permeability of the alveolar-capillary membrane, a thin barrier composed of adjacent monolayers of alveolar epithelial and lung microvascular endothelial cells. This results in pulmonary edema and severe hypoxemia and is a common cause of death after both viral (e.g., SARS-CoV-2) and bacterial pneumonia. The involvement of the lung in ARDS is notoriously heterogeneous, with consolidated and edematous lung abutting aerated, less injured regions. This makes treatment difficult, as most therapeutic approaches preferentially affect the normal lung regions or are distributed indiscriminately to other organs. In this review, we describe the use of thoracic ultrasound and microbubbles (USMB) to deliver therapeutic cargo (drugs, genes) preferentially to severely injured areas of the lung and in particular to the lung endothelium. While USMB has been explored in other organs, it has been under-appreciated in the treatment of lung injury since ultrasound energy is scattered by air. However, this limitation can be harnessed to direct therapy specifically to severely injured lungs. We explore the cellular mechanisms governing USMB and describe various permutations of cargo administration. Lastly, we discuss both the challenges and potential opportunities presented by USMB in the lung as a tool for both therapy and research.

Capillary leak syndrome: State of the art in 2021.

Capillary leak syndrome (CLS) is an increasingly acknowledged multifaceted and potentially lethal disease. Initial nonspecific symptoms are followed by the intriguing CLS hallmark: the double paradox associating diffuse severe edema and hypovolemia, along with hemoconcentration and hypoalbuminemia. Spontaneous resolutive phase is often associated with poor outcome due to iatrogenic fluid overload during leak phase. CLS is mainly triggered by drugs (anti-tumoral therapies), malignancy, infections (mostly viruses) and inflammatory diseases. Its idiopathic form is named after its eponymous finder: Clarkson's disease. CLS pathophysiology involves a severe, transient and multifactorial endothelial disruption which mechanisms are still unclear. Empirical and based-on-experience treatment implies symptomatic care during the acute phase (with the eventual addition of drugs amplifying cAMP levels in the severest cases), and the prophylactic use of monthly polyvalent immunoglobulins to prevent relapses. As CLS literature is scattered, we aimed to collect and summarize the current knowledge on CLS to facilitate its diagnosis, understanding and management.

Anti-inflammatory Effects of Statins in Lung Vascular Pathology: From Basic Science to Clinical Trials.

HMG-CoA reductase inhibitors (or statins) are cholesterol-lowering drugs and are among the most widely prescribed medications in the United States. Statins exhibit pleiotropic effects that extend beyond cholesterol reduction including anti-atherosclerotic, antiproliferative, anti-inflammatory, and antithrombotic effects. Over the last 20 years, statins have been studied and examined in pulmonary vascular disorders, including both chronic pulmonary vascular disease such as pulmonary hypertension, and acute pulmonary vascular endothelial injury such as acute lung injury. In both research and clinical settings, statins have demonstrated promising vascular protection through modulation of the endothelium, attenuation of vascular leak, and promotion of endothelial repair following lung inflammation. This chapter provides a summary of the rapidly changing literature, summarizes the anti-inflammatory mechanism of statins on pulmonary vascular disorders, and explores clinical evidence for statins as a potential therapeutic approach to modulation of the endothelium as well as a means to broaden our understanding of pulmonary vasculopathy pathophysiology.

Depletion of Arg/Abl2 improves endothelial cell adhesion and prevents vascular leak during inflammation.

Endothelial barrier disruption and vascular leak importantly contribute to organ dysfunction and mortality during inflammatory conditions like sepsis and acute respiratory distress syndrome. We identified the kinase Arg/Abl2 as a mediator of endothelial barrier disruption, but the role of Arg in endothelial monolayer regulation and its relevance in vivo remain poorly understood. Here we show that depletion of Arg in endothelial cells results in the activation of both RhoA and Rac1, increased cell spreading and elongation, redistribution of integrin-dependent cell-matrix adhesions to the cell periphery, and improved adhesion to the extracellular matrix. We further show that Arg is activated in the endothelium during inflammation, both in murine lungs exposed to barrier-disruptive agents, and in pulmonary microvessels of septic patients. Importantly, Arg-depleted endothelial cells were less sensitive to barrier-disruptive agents. Despite the formation of F-actin stress fibers and myosin light chain phosphorylation, Arg depletion diminished adherens junction disruption and intercellular gap formation, by reducing the disassembly of cell-matrix adhesions and cell retraction. In vivo, genetic deletion of Arg diminished vascular leak in the skin and lungs, in the presence of a normal immune response. Together, our data indicate that Arg is a central and non-redundant regulator of endothelial barrier integrity, which contributes to cell retraction and gap formation by increasing the dynamics of adherens junctions and cell-matrix adhesions in a Rho GTPase-dependent fashion. Therapeutic inhibition of Arg may provide a suitable strategy for the treatment of a variety of clinical conditions characterized by vascular leak.

Safety and Efficacy of Imatinib for Hospitalized Adults with COVID-19: A structured summary of a study protocol for a randomised controlled trial.

OBJECTIVES: Primary Objective: To evaluate the efficacy and safety of oral administration of imatinib combined with the Best Conventional Care (BCC) versus placebo plus BCC in hospitalized patients with COVID-19. HYPOTHESIS: Addition of imatinib to the BCC will provide a superior clinical outcome for patients with COVID-19 compared with BCC plus placebo. This hypothesis is on the basis of 1) intralysosomal entrapment of imatinib will increase endosomal pH and effectively decrease SARS-CoV-2/cell fusion, 2) kinase inhibitory activity of imatinib will interfere with budding/release or replication of SARS-CoV-2, and 3) because of the critical role of mechanical ventilation in the care of patients with ARDS, imatinib will have a significant clinical impact for patients with critical COVID-19 infection in Intensive Care Unit (ICU). TRIAL DESIGN: This is an individual patient-level randomized, double-blind, placebo-controlled, two-parallel arm phase 3 study to evaluate the safety and efficacy of imatinib for the treatment of hospitalized adults with COVID-19. Participants will be followed for up to 60 days from the start of study drug administration. This trial will be conducted in accordance with the principles of the Declaration of Helsinki and the Good Clinical Practice guidelines of the International Conference on Harmonization. PARTICIPANTS: Inclusion Criteria: Patients may be included in the study only if they meet all of the following criteria: 1) Ability to understand and willingness to sign a written informed consent document. Informed consent must be obtained prior to participation in the study. For patients who are too unwell to provide consent such as patients on invasive ventilator or extracorporeal membrane oxygenation (ECMO), their Legally Authorized Representative (LAR) can sign the informed consent, 2) Hospitalized patients ≥18 years of age, 3) Positive reverse transcriptase-polymerase chain reaction (RT-PCR) assay for SARS-CoV-2 in the respiratory tract sample (oropharyngeal, nasopharyngeal or bronchoalveolar lavage (BAL)) by Center for Disease Control or local laboratory within 7 days of randomization, 4) Women of childbearing potential must agree to use at least one primary form of contraception for the duration of the study. EXCLUSION CRITERIA: Patients meeting any of the following criteria are not eligible for the study: 1) Patients receiving any other investigational agents in a clinical trial. Off-label use of agents such as hydroxychloroquine is not an exclusion criterion, 2) Pregnant or breastfeeding women, 3) Patients with significant liver or renal dysfunction at the time of screening as defined as: 3.1) Direct bilirubin >2.5 mg/dL, 3.2) AST, ALT, or alkaline phosphatase >5x upper limit of normal, 3.3) eGFR ≤30 mL/min or requiring renal replacement therapy, 4) Patients with significant hematologic disorder at screen as defined as: 4.1) Absolute neutrophil count (ANC) <500/µL, 4.2) Platelet <20,000/µL, 4.3) Hemoglobin <7 g/dL, 5) Uncontrolled underlying illness including, but not limited to, symptomatic congestive heart failure, unstable angina pectoris, uncontrolled active seizure disorder, or psychiatric illness/social situations that per site Principal Investigator's judgment would limit compliance with study requirements, 6) Known allergy to imatinib or its component products, 7) Any other clinical conditions that in the opinion of the investigator would make the subject unsuitable for the study. Both men and women of all races and ethnic groups are eligible for this trial. University of Maryland Medical Center, Baltimore, MD is the initiating site. The study may be opened in other centers on the basis of the accrual rate or the magnitude of the COVID-19 pandemic. INTERVENTION AND COMPARATOR: Imatinib: All doses of imatinib should be administered with a meal and a large glass of water. Imatinib can be dissolved in water or apple juice for patients having difficulty swallowing. In this study, patients with confirmed positive COVID-19 tests receive imatinib for a total of 14 days; 400 mg orally daily Days 1-14. Imatinib 400 mg tablets will be encapsulated using size 000 capsules and cellulose microcrystalline filler. For patients on ventilator or ECMO, imatinib will be given as oral suspension (40 mg/mL). To make the oral suspension, imatinib tablets will be crushed and mixed in Ora-sweet solution to yield a concentration of 40 mg/mL suspension by pharmacy. Additionally, in the absence of supportive microbiological testing results, we confirm that the in-use stability period for the prepared imatinib suspensions will be 24 hours at room temperature or 7 days at refrigerated conditions. The pharmacy staff will follow the American Society Health-System Pharmacists (ASHP) guidelines for handling hazardous drugs. Placebo: The matching placebo will be packaged by Investigational Drug Service Pharmacy at University of Maryland Medical Center. The placebos will be prepared using size 000 capsules and cellulose microcrystalline filler. Imatinib 400 mg capsules and placebo capsules will be identical form and color. For patients on ventilator or ECMO, placebo will be given as oral suspension with similar process for making imatinib suspension. Concomitant Medications/supportive care: In both arms, patients can receive concomitant available local standard of care antipyretics, antibacterials, antivirals, antifungals and anti-inflammatory including hydroxychloroquine at the discretion of the treating physician as necessary. For other drug-drug interactions particularly with CYP P450, the treating physician should consider the risk and benefit of drug administration based on available information. Co-administration of off-label immunomodulatory treatments for COVID-19 including but not limited to corticosteroids, sarilumab, clazakizumab, tocilizumab, and anakinra will be allowed but may affect interpretability of study outcomes. The timing, dosing, and duration of these treatments will be meticulously collected, including any of these treatments that may be used for participants who experience progression of COVID-19 disease after study enrollment. Two analyses will be performed, the primary analysis will compare the primary endpoint in the two trial arms irrespective of any other treatment; the second analysis will be stratified for co-administration of immunomodulatory drugs. MAIN OUTCOMES: The primary endpoint is the proportion of patients with a two-point improvement at Day 14 from baseline using the 8-category ordinal scale. The ordinal scale is an evaluation of the clinical status at the first assessment of a given study day. The scale is as follows: 1) Not hospitalized, no limitations on activities; 2) Not hospitalized, limitation on activities and/or requiring home oxygen; 3) Hospitalized, not requiring supplemental oxygen - no longer requires ongoing medical care; 4) Hospitalized, not requiring supplemental oxygen - requiring ongoing medical care (COVID-19 related or otherwise); 5) Hospitalized, requiring supplemental oxygen; 6) Hospitalized, on non-invasive ventilation or high flow oxygen devices; 7) Hospitalized, on invasive mechanical ventilation or ECMO; 8) Death. The secondary endpoints include: All-cause mortality at Day 28, All-cause mortality at Day 60, Time to a 2-point clinical improvement difference over baseline, Duration of hospitalization, Duration of ECMO or invasive mechanical ventilation (for subjects who are on ECMO or mechanical ventilation at Day 1), Duration of ICU stay (for subjects who are in ICU at Day 1), Time to SARS-CoV-2 negative by RT-PCR, Proportion of patients with negative oropharyngeal or nasopharyngeal swab for SARS-CoV-2 by RT-PCR on days 5, 10, 14, 21, and 28 after starting treatment, Proportion of subjects with serious adverse events, Proportion of subjects who discontinue study drug due to adverse events. The exploratory endpoints include: Determine the impact of treatment arms on IL-6 levels, Obtain blood/peripheral blood mononuclear cells (PBMCs) for storage to look at transcriptomics in severe disease, Association of major histocompatibility complex (MHC) with severity of illness, Mean change in the ordinal scale from baseline, Time to an improvement of one category from admission using an ordinal scale, Duration of hospitalization, Duration of new oxygen use, Number of oxygenation free days, Duration of new mechanical ventilation, Number of ventilator free days. RANDOMIZATION: Eligible patients will be uniformly randomized in 1:1 ratio to receive either imatinib or placebo for 14 days. Both groups will receive the BCC. The randomized treatment allocations use stratified, permuted block randomization with a variable block size; blocks are generated using a validated random number generator. In order to balance the severity of the respiratory illness between the two arms, randomization will be stratified based on radiographic findings and oxygen requirements: 1) Severe disease: evidence of pneumonia on chest X-ray or CT scan OR chest auscultation (rales, crackles), and SpO2 ≤92% on ambient air or PaO2/FiO2 <300 mmHg, and requires supplemental oxygen administration by nasal cannula, simple face mask, or other similar oxygen delivery device; 2) Critical disease: requires supplemental oxygen delivered by non-rebreather mask or high flow cannula OR use of invasive or non-invasive ventilation OR requiring treatment in an intensive care unit, use of vasopressors, extracorporeal life support, or renal replacement therapy. BLINDING (MASKING): The participants, caregivers, and the statistician are blinded to group assignment. The only people who are not blinded are Site Pharmacists. Blinding will be performed via a specific randomization process. Centralized, concealed randomization will be executed by the Primary Site's Pharmacist. Data on eligible consented cases will be submitted electronically on the appropriate on-study form to the pharmacy, where the patient is randomized to imatinib or placebo. Imatinib 400 mg capsules and placebo capsules will be identical form and color. For patients on ventilator or ECMO, placebo will be given as oral suspension with similar process for making imatinib suspension. NUMBERS TO BE RANDOMIZED (SAMPLE SIZE): The trial is designed as a double-blind, two-parallel arm, randomized controlled trial with a uniform (1:1) allocation ratio to: Arm A) Imatinib or Arm B) Placebo. Patients in both arms will receive the BCC per local institutional standards at the discretion of the treating physician. Group sample sizes of 102 in Arm A and 102 in Arm B achieve 80.6% power to detect a difference between the group proportions of 0.20. The proportion in Arm A (imatinib treatment arm) is assumed to be 0.30 under the null hypothesis and 0.50 under the alternative hypothesis. The proportion in Arm B (placebo control arm) is 0.30. The test statistic used is the two-sided Fisher's Exact Test. The significance level of the test is targeted at 0.05. The significance level actually achieved by this design is α=0.0385. The power of the test is calculated using binomial enumeration of all possible outcomes. The primary analysis will be conducted using an intention to treat principle (ITT) for participants who at least receive one dose of study drug or placebo. The sample size is not inflated for dropouts. All patients will be evaluable irrespective of the clinical course of their disease. TRIAL STATUS: Current protocol version is 1.2 from May 8, 2020. The recruitment started on June 15, 2020 and is ongoing. We originally anticipated that the trial would finish recruitment by mid 2021. We are aware of the enrollment requirement of approximately 200 patients, which is required to provide scientific integrity of the results. We are also aware of the fact that enrolling this number of patients in a single-site at University of Maryland Medical Center (UMMC) may take longer than expected, particularly taken into account other competing studies. For this reason, we are actively considering opening the protocol in other sites. After identification of other sites, we will fulfill all regulatory requirements before opening the protocol in other sites. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04394416 . First Posted: May 19, 2020; Last Update Posted: June 4, 2020. FDA has issued the "Study May Proceed" Letter for this clinical trial under the Investigational New Drug (IND) number 149239. FULL PROTOCOL: The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol.

A Novel Strategy to Mitigate the Hyperinflammatory Response to COVID-19 by Targeting Leukotrienes.

SARS-CoV-2 causing coronavirus disease 2019 (COVID-19) has wreaked havoc during the global pandemic of 2020 infecting millions and leaving over a half million dead. As a new virus, not previously in the human population, but with similarities to other coronaviruses causing severe acute respiratory distress syndrome (SARS/ARDS), and no known treatments, the race to re-purpose existing drugs and to enlist novel therapeutics is underway. In the half-year since the first cases, we have acquired substantial knowledge of this virus and the clinical course of COVID-19 progression. Results from early clinical trials have revealed two treatments (remdesivir, dexamethasone) that mitigate disease progression but clearly, there is much room for improvement. Initial case reports indicated many succumb to COVID-19 of hypoxic respiratory failure due to ARDS. However, ensuing studies revealed an atypical, immune cell-sequestered, vasculature-inflamed state leading to multiorgan thrombotic complications and end organ failure likely due to hyperinflammatory host responses. This Perspective focuses on a potential mechanism for a key COVID-19 disease progression turning point related to vascular and airway inflammation. The leukotriene lipid mediators have been overlooked with discussion centering on cytokine storms unleashing the deadly form of COVID-19. Leukotrienes possess some of the most potent known activities on immune cell trafficking and vascular leakage. We offer a simple treatment paradigm using two generic drugs targeting the hyperinflammatory response that characterizes the turning point from mild to severe/critical COVID-19 by targeting leukotriene biosynthesis with zileuton (Zyflo® controlled release formulation) and antagonism of the cysteinyl leukotriene 1 receptor with montelukast (Singulair®).

The endothelial glycocalyx: Structure and function in health and critical illness.

OBJECTIVE: To conduct a narrative review of the current literature in reference to the structure and function of the endothelial glycocalyx (EG) and its contribution to the pathophysiology of conditions relevant to the veterinary emergency and critical care clinician. Novel therapies for restoring or preserving the EG will also be discussed. DATA SOURCES: Online databases (PubMed, CAB abstracts, Scopus) were searched between January 1st 2017 and May 1st 2017 for English language articles without publication date restriction. Keywords included EG, endothelial surface layer, degradation, syndecan-1, heparan sulfate, critical illness, sepsis, trauma, and therapeutics. DATA SYNTHESIS: The EG is a complex and important structure located on the luminal surface of all blood vessels throughout the body. It plays an important role in normal vascular homeostasis including control of fluid exchange across the vascular barrier. Loss or degradation of the EG has an impact on inflammation, coagulation, and vascular permeability and tone. These changes are essential components in the pathophysiology of many conditions including sepsis and trauma. A substantial body of experimental animal and human clinical research over the last decade has demonstrated increased circulating concentrations of EG degradation products in these conditions. However, veterinary-specific research into the EG and critical illness is currently lacking. The utility of EG degradation products as diagnostic and prognostic tools continues to be investigated and new therapies to preserve or improve EG structure and function are under development. CONCLUSIONS: The recognition of the presence of the EG has changed our understanding of transvascular fluid flux and the pathophysiology of many conditions of critical illness. The EG is an exciting target for novel therapeutics to improve morbidity and mortality in conditions such as sepsis and trauma.

Imaging Biomarkers in Animal Models of Drug-Induced Lung Injury: A Systematic Review.

For drug-induced interstitial lung disease (DIILD) translational imaging biomarkers are needed to improve detection and management of lung injury and drug-toxicity. Literature was reviewed on animal models in which in vivo imaging was used to detect and assess lung lesions that resembled pathological changes found in DIILD, such as inflammation and fibrosis. A systematic search was carried out using three databases with key words "Animal models", "Imaging", "Lung disease", and "Drugs". A total of 5749 articles were found, and, based on inclusion criteria, 284 papers were selected for final data extraction, resulting in 182 out of the 284 papers, based on eligibility. Twelve different animal species occurred and nine various imaging modalities were used, with two-thirds of the studies being longitudinal. The inducing agents and exposure (dose and duration) differed from non-physiological to clinically relevant doses. The majority of studies reported other biomarkers and/or histological confirmation of the imaging results. Summary of radiotracers and examples of imaging biomarkers were summarized, and the types of animal models and the most used imaging modalities and applications are discussed in this review. Pathologies resembling DIILD, such as inflammation and fibrosis, were described in many papers, but only a few explicitly addressed drug-induced toxicity experiments.

Vascular Leak and Hypercytokinemia Associated with Severe Fever with Thrombocytopenia Syndrome Virus Infection in Mice.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging viral hemorrhagic fever (VHF) endemic to China, South Korea, Japan, and Vietnam. Here we characterize the pathogenesis and natural history of disease in IFNAR-/- mice challenged with the HB29 strain of SFTS virus (SFTSV) and demonstrate hallmark features of VHF such as vascular leak and high concentrations of proinflammatory cytokines in blood and tissues. Treatment with FX06, a natural plasmin digest product of fibrin in clinical development as a treatment for vascular leak, reduced vascular permeability associated with SFTSV infection but did not significantly improve survival outcome. Further studies are needed to assess the role of vascular compromise in the SFTS disease process modeled in IFNAR-/- mice.

Neutrophil activation in systemic capillary leak syndrome (Clarkson disease).

Systemic capillary leak syndrome (SCLS; Clarkson disease) is a rare orphan disorder characterized by transient yet recurrent episodes of hypotension and peripheral oedema due to diffuse vascular leakage of fluids and proteins into soft tissues. Humoral mediators, cellular responses and genetic features accounting for the clinical phenotype of SCLS are virtually unknown. Here, we searched for factors altered in acute SCLS plasma relative to matched convalescent samples using multiplexed aptamer-based proteomic screening. Relative amounts of 612 proteins were changed greater than twofold and 81 proteins were changed at least threefold. Among the most enriched proteins in acute SCLS plasma were neutrophil granule components including bactericidal permeability inducing protein, myeloperoxidase and matrix metalloproteinase 8. Neutrophils isolated from blood of subjects with SCLS or healthy controls responded similarly to routine pro-inflammatory mediators. However, acute SCLS sera activated neutrophils relative to remission sera. Activated neutrophil supernatants increased permeability of endothelial cells from both controls and SCLS subjects equivalently. Our results suggest systemic neutrophil degranulation during SCLS acute flares, which may contribute to the clinical manifestations of acute vascular leak.