Increased Angiotensin-Converting Enzyme 2 and Loss of Alveolar Type II Cells in COVID-19-related Acute Respiratory Distress Syndrome.

Rationale: ACE2 (angiotensin-converting enzyme 2), the entry receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is expressed in type 2 alveolar epithelial cells (AT2) that may play key roles in postinjury repair. An imbalance between ACE2 and ACE has also been hypothesized to contribute to lung injury. Objectives: To characterize the expression and distribution of ACE2 and ACE and to compare AT2 with endothelial cell expression in coronavirus disease (COVID-19)-related or -unrelated acute respiratory distress syndrome (ARDS) and controls. Methods: Lung tissue stainings (using multiplex immunofluorescence) and serum concentrations of ACEs were determined retrospectively in two different cohorts of patients. AT2 and endothelial cells were stained in lung tissue for ProSPC (pro-surfactant protein C) and CD31, respectively. Measurements and Main Results: Pulmonary ACE2 expression was increased in patients with COVID-19-related and -unrelated ARDS (0.06% of tissue area and 0.12% vs. 0.006% for control subjects; P = 0.013 and P < 0.0001, respectively). ACE2 was upregulated in endothelial cells (0.32% and 0.53% vs. 0.01%; P = 0.009 and P < 0.0001) but not in AT2 cells (0.13% and 0.08% vs. 0.03%; P = 0.94 and P = 0.44). Pulmonary expression of ACE was decreased in both COVID-19-related and -unrelated ARDS (P = 0.057 and P = 0.032). Similar increases in ACE2 and decreases in ACE were observed in sera of COVID-19 (P = 0.0054 and P < 0.0001) and non-COVID-19 ARDS (P < 0.0001 and P = 0.016). In addition, AT2 cells were decreased in patients with COVID-19-related ARDS compared with COVID-19-unrelated ARDS (1.395% vs. 2.94%, P = 0.0033). Conclusions: ACE2 is upregulated in lung tissue and serum of both COVID-19-related and -unrelated ARDS, whereas a loss of AT2 cells is selectively observed in COVID-19-related ARDS.

Biological Assessment of the NO-Dependent Endothelial Function.

Nitric oxide (NO) is implicated in numerous physiological processes, including vascular homeostasis. Reduced NO bioavailability is a hallmark of endothelial dysfunction, a prequel to many cardiovascular diseases. Biomarkers of an early NO-dependent endothelial dysfunction obtained from routine venous blood sampling would be of great interest but are currently lacking. The direct measurement of circulating NO remains a challenge due by its high reactivity and short half-life. The current techniques measure stable products from the NO signaling pathway or metabolic end products of NO that do not accurately represent its bioavailability and, therefore, endothelial function per se. In this review, we will concentrate on an original technique of low temperature electron paramagnetic resonance spectroscopy capable to directly measure the 5-α-coordinated heme nitrosyl-hemoglobin in the T (tense) state (5-α-nitrosyl-hemoglobin or HbNO) obtained from fresh venous human erythrocytes. In humans, HbNO reflects the bioavailability of NO formed in the vasculature from vascular endothelial NOS or exogenous NO donors with minor contribution from erythrocyte NOS. The HbNO signal is directly correlated with the vascular endothelial function and inversely correlated with vascular oxidative stress. Pilot studies support the validity of HbNO measurements both for the detection of endothelial dysfunction in asymptomatic subjects and for the monitoring of such dysfunction in patients with known cardiovascular disease. The impact of therapies or the severity of diseases such as COVID-19 infection involving the endothelium could also be monitored and their incumbent risk of complications better predicted through serial measurements of HbNO.

Is there a role for immune-enhancing therapies for acutely ill patients with coronavirus disease 2019?

PURPOSE OF REVIEW: Although the so-called cytokine storm has been early described and related to a dramatic evolution in severe COVID-19 patients, it soon became clear that those patients display clinical and biological evidence of an immunosuppressive state characterized, among other, by a profound lymphopenia. The negative role of this immune suppression on the outcome raises the question on immune therapies that might improve patient's condition. RECENT FINDINGS: Important positive effects of active immune therapies, such as IL-7 or thymosin-α are already described and warrant confirmation in larger prospective trials. For other therapies, such as interferons, firm conclusions for critically ill COVID-19 patients are lacking as those patients were often excluded from the published trials. Treatment with immunoglobulins or convalescent plasma is a passive strategy to provide specific immunity. Unfortunately, results from large RCTs do not support their use presently. SUMMARY: In this article, we provide a review on active and passive immune boosting strategies that might help treating the most severe COVID-19 patients. We mainly focus on active strategies that include IL-7, thymosin-α, interferons, and vitamin D. Although some positive effects are described, they certainly warrant confirmation in large randomized controlled trials.

IRF4 impedes human CD8 T cell function and promotes cell proliferation and PD-1 expression.

Human CD8 tumor-infiltrating lymphocytes (TILs) with impaired effector functions and PD-1 expression are categorized as exhausted. However, the exhaustion-like features reported in TILs might stem from their activation rather than the consequence of T cell exhaustion itself. Using CRISPR-Cas9 and lentiviral overexpression in CD8 T cells from non-cancerous donors, we show that the T cell receptor (TCR)-induced transcription factor interferon regulatory factor 4 (IRF4) promotes cell proliferation and PD-1 expression and hampers effector functions and expression of nuclear factor κB (NF-κB)-regulated genes. While CD8 TILs with impaired interferon γ (IFNγ) production exhibit activation markers IRF4 and CD137 and exhaustion markers thymocyte selection associated high mobility group box (TOX) and PD-1, activated T cells in patients with COVID-19 do not demonstrate elevated levels of TOX and PD-1. These results confirm that IRF4+ TILs are exhausted rather than solely activated. Our study indicates, however, that PD-1 expression, low IFNγ production, and active cycling in TILs are all influenced by IRF4 upregulation after T cell activation.

HELIOS-expressing human CD8 T cells exhibit limited effector functions.

Introduction: The transcription factor HELIOS is primarily known for its expression in CD4 regulatory T cells, both in humans and mice. In mice, HELIOS is found in exhausted CD8 T cells. However, information on human HELIOS+ CD8 T cells is limited and conflicting. Methods: In this study, we characterized by flow cytometry and transcriptomic analyses human HELIOS+ CD8 T cells. Results: These T cells primarily consist of memory cells and constitute approximately 21% of blood CD8 T cells. In comparison with memory HELIOS- T-BEThigh CD8 T cells that displayed robust effector functions, the memory HELIOS+ T-BEThigh CD8 T cells produce lower amounts of IFN-γ and TNF-α and have a lower cytotoxic potential. We wondered if these cells participate in the immune response against viral antigens, but did not find HELIOS+ cells among CD8 T cells recognizing CMV peptides presented by HLA-A2 and HLA-B7. However, we found HELIOS+ CD8 T cells that recognize a CMV peptide presented by MHC class Ib molecule HLA-E. Additionally, a portion of HELIOS+ CD8 T cells is characterized by the expression of CD161, often used as a surface marker for identifying TC17 cells. These CD8 T cells express TH17/TC17-related genes encoding RORgt, RORa, PLZF, and CCL20. Discussion: Our findings emphasize that HELIOS is expressed across various CD8 T cell populations, highlighting its significance beyond its role as a transcription factor for Treg or exhausted murine CD8 T cells. The significance of the connection between HELIOS and HLA-E restriction is yet to be understood.

Development of SARS-CoV2 humoral response including neutralizing antibodies is not sufficient to protect patients against fatal infection.

More than a year after the start of the pandemic, COVID-19 remains a global health emergency. Although the immune response against SARS-CoV-2 has been extensively studied, some points remain controversial. One is the role of antibodies in viral clearance and modulation of disease severity. While passive transfer of neutralizing antibodies protects against SARS-CoV-2 infection in animal models, titers of anti-SARS-CoV-2 antibodies have been reported to be higher in patients suffering from more severe forms of the disease. A second key question for pandemic management and vaccine design is the persistence of the humoral response. Here, we characterized the antibody response in 187 COVID-19 patients, ranging from asymptomatic individuals to patients who died from COVID-19, and including patients who recovered. We developed in-house ELISAs to measure titers of IgG, IgM and IgA directed against the RBD or N regions in patient serum or plasma, and a spike-pseudotyped neutralization assay to analyse seroneutralization. Higher titers of virus-specific antibodies were detected in patients with severe COVID-19, including deceased patients, compared to asymptomatic patients. This demonstrates that fatal infection is not associated with defective humoral response. Finally, most of recovered patients still had anti-SARS-CoV-2 IgG more than 3 months after infection.

Oxidative stress-induced endothelial dysfunction and decreased vascular nitric oxide in COVID-19 patients.

BACKGROUND: SARS-CoV-2 targets endothelial cells through the angiotensin-converting enzyme 2 receptor. The resulting endothelial injury induces widespread thrombosis and microangiopathy. Nevertheless, early specific markers of endothelial dysfunction and vascular redox status in COVID-19 patients are currently missing. METHODS: Observational study including ICU and non-ICU adult COVID-19 patients admitted in hospital for acute respiratory failure, compared with control subjects matched for cardiovascular risk factors similar to ICU COVID-19 patients, and ICU septic shock patients unrelated to COVID-19. FINDINGS: Early SARS-CoV-2 infection was associated with an imbalance between an exacerbated oxidative stress (plasma peroxides levels in ICU patients vs. controls: 1456.0 ± 400.2 vs 436 ± 272.1 mmol/L; P < 0.05) and a reduced nitric oxide bioavailability proportional to disease severity (5-α-nitrosyl-hemoglobin, HbNO in ICU patients vs. controls: 116.1 ± 62.1 vs. 163.3 ± 46.7 nmol/L; P < 0.05). HbNO levels correlated with oxygenation parameters (PaO2/FiO2 ratio) in COVID-19 patients (R2 = 0.13; P < 0.05). Plasma levels of angiotensin II, aldosterone, renin or serum level of TREM-1 ruled out any hyper-activation of the renin-angiotensin-aldosterone system or leucocyte respiratory burst in ICU COVID-19 patients, contrary to septic patients. INTERPRETATION: Endothelial oxidative stress with ensuing decreased NO bioavailability appears as a likely pathogenic factor of endothelial dysfunction in ICU COVID-19 patients. A correlation between NO bioavailability and oxygenation parameters is observed in hospitalized COVID-19 patients. These results highlight an urgent need for oriented research leading to a better understanding of the specific endothelial oxidative stress that occurs during SARS-CoV-2. FUNDING: Stated in the acknowledgments section.

Inflammation-Induced Coagulopathy Substantially Differs Between COVID-19 and Septic Shock: A Prospective Observational Study.

Critical COVID-19, like septic shock, is related to a dysregulated systemic inflammatory reaction and is associated with a high incidence of thrombosis and microthrombosis. Improving the understanding of the underlying pathophysiology of critical COVID-19 could help in finding new therapeutic targets already explored in the treatment of septic shock. The current study prospectively compared 48 patients with septic shock and 22 patients with critical COVID-19 regarding their clinical characteristics and outcomes, as well as key plasmatic soluble biomarkers of inflammation, coagulation, endothelial activation, platelet activation, and NETosis. Forty-eight patients with matched age, gender, and co-morbidities were used as controls. Critical COVID-19 patients exhibited less organ failure but a prolonged ICU length-of-stay due to a prolonged respiratory failure. Inflammatory reaction of critical COVID-19 was distinguished by very high levels of interleukin (IL)-1ß and T lymphocyte activation (including IL-7 and CD40L), whereas septic shock displays higher levels of IL-6, IL-8, and a more significant elevation of myeloid response biomarkers, including Triggering Receptor Expressed on Myeloid cells-1 (TREM-1) and IL-1ra. Subsequent inflammation-induced coagulopathy of COVID-19 also differed from sepsis-induced coagulopathy (SIC) and was characterized by a marked increase in soluble tissue factor (TF) but less platelets, antithrombin, and fibrinogen consumption, and less fibrinolysis alteration. In conclusion, COVID-19 inflammation-induced coagulopathy substantially differs from SIC. Modulating TF release and activity should be evaluated in critical COVID-19 patients.

Impaired immune response mediated by prostaglandin E2 promotes severe COVID-19 disease.

The SARS-CoV-2 coronavirus has led to a pandemic with millions of people affected. The present study finds that risk-factors for severe COVID-19 disease courses, i.e. male sex, older age and sedentary life style are associated with higher prostaglandin E2 (PGE2) serum levels in blood samples from unaffected subjects. In COVID-19 patients, PGE2 blood levels are markedly elevated and correlate positively with disease severity. SARS-CoV-2 induces PGE2 generation and secretion in infected lung epithelial cells by upregulating cyclo-oxygenase (COX)-2 and reducing the PG-degrading enzyme 15-hydroxyprostaglandin-dehydrogenase. Also living human precision cut lung slices (PCLS) infected with SARS-CoV-2 display upregulated COX-2. Regular exercise in aged individuals lowers PGE2 serum levels, which leads to increased Paired-Box-Protein-Pax-5 (PAX5) expression, a master regulator of B-cell survival, proliferation and differentiation also towards long lived memory B-cells, in human pre-B-cell lines. Moreover, PGE2 levels in serum of COVID-19 patients lowers the expression of PAX5 in human pre-B-cell lines. The PGE2 inhibitor Taxifolin reduces SARS-CoV-2-induced PGE2 production. In conclusion, SARS-CoV-2, male sex, old age, and sedentary life style increase PGE2 levels, which may reduce the early anti-viral defense as well as the development of immunity promoting severe disease courses and multiple infections. Regular exercise and Taxifolin treatment may reduce these risks and prevent severe disease courses.

Surgical mask on top of high-flow nasal cannula improves oxygenation in critically ill COVID-19 patients with hypoxemic respiratory failure.

OBJECTIVE: Critically ill patients admitted in ICU because of COVID-19 infection display severe hypoxemic respiratory failure. The Surviving Sepsis Campaign recommends oxygenation through high-flow nasal cannula over non-invasive ventilation. The primary outcome of our study was to evaluate the effect of the addition of a surgical mask on a high-flow nasal cannula system on oxygenation parameters in hypoxemic COVID-19 patients admitted in ICU who do not require urgent intubation. The secondary outcomes were relevant changes in PaCO2 associated with clinical modifications and patient's feelings. DESIGN: We prospectively assessed 21 patients admitted in our mixed Intensive Care Unit of the Cliniques Universitaires Saint Luc. MAIN RESULTS: While FiO2 was unchanged, we demonstrate a significant increase of PaO2 (from 59 (± 6), to 79 mmHg (± 16), p < 0.001), PaO2/FiO2 from 83 (± 22), to 111 (± 38), p < 0.001) and SaO2 (from 91% (± 1.5), to 94% (± 1.6), p < 0.001), while the patients were under the surgical mask. The SpO2 returned to pre-treatment values when the surgical mask was removed confirming the effect of the device rather than a spontaneous positive evolution. CONCLUSION: A surgical mask placed on patient's face already treated by a High-flow nasal cannula device improves COVID-19 patient's oxygenation admitted in Intensive Care Unit for severe hypoxemic respiratory failure without any clinically relevant side.

Inhibition of aquaporin-1 prevents myocardial remodeling by blocking the transmembrane transport of hydrogen peroxide.

Pathological remodeling of the myocardium has long been known to involve oxidant signaling, but strategies using systemic antioxidants have generally failed to prevent it. We sought to identify key regulators of oxidant-mediated cardiac hypertrophy amenable to targeted pharmacological therapy. Specific isoforms of the aquaporin water channels have been implicated in oxidant sensing, but their role in heart muscle is unknown. RNA sequencing from human cardiac myocytes revealed that the archetypal AQP1 is a major isoform. AQP1 expression correlates with the severity of hypertrophic remodeling in patients with aortic stenosis. The AQP1 channel was detected at the plasma membrane of human and mouse cardiac myocytes from hypertrophic hearts, where it colocalized with NADPH oxidase-2 and caveolin-3. We show that hydrogen peroxide (H2O2), produced extracellularly, is necessary for the hypertrophic response of isolated cardiac myocytes and that AQP1 facilitates the transmembrane transport of H2O2 through its water pore, resulting in activation of oxidant-sensitive kinases in cardiac myocytes. Structural analysis of the amino acid residues lining the water pore of AQP1 supports its permeation by H2O2 Deletion of Aqp1 or selective blockade of the AQP1 intrasubunit pore inhibited H2O2 transport in mouse and human cells and rescued the myocyte hypertrophy in human induced pluripotent stem cell-derived engineered heart muscle. Treatment of mice with a clinically approved AQP1 inhibitor, Bacopaside, attenuated cardiac hypertrophy. We conclude that cardiac hypertrophy is mediated by the transmembrane transport of H2O2 by the water channel AQP1 and that inhibitors of AQP1 represent new possibilities for treating hypertrophic cardiomyopathies.

Primary cardiac lymphoma and complete atrio-ventricular block: case report and review of the literature.

Primary cardiac lymphoma (PCL) is a rare and extremely aggressive malignancy, which can express itself by damaging the cardiac conduction system (complete atrio-ventricular block), the myocardium and the pericardium. Histology confirms the diagnosis. Chances of survival depend on early diagnosis and treatment. We present the case of a female patient admitted for severe deterioration of her general state of health who had a complete atrio-ventricular block caused by a tumour of the atrial septum, a B-cell lymphoma stage I. The diagnosis was suggested by combined PET/CT imaging and confirmed by histology of a cardiac biopsy. Her general clinical condition, including the cardiac parameters, significantly improved following chemotherapy induction.

Nitric oxide synthase in post-ischaemic remodelling: new pathways and mechanisms.

The three isoforms of nitric oxide synthase (NOS), spatially confined in specific intracellular compartments in cardiac cells, have distinct roles in the regulation of contractility in pathophysiological situations. Recently, evidence has emerged that implicates NOS in modulating myocardial remodelling during cardiac stress, including after ischaemic insults. As long as they remain in a coupled state the NOS mostly attenuate hypertrophic remodelling through both cGMP-dependent and independent mechanisms. We review the evidence provided from the phenotype of genetic mouse models as well as from in vitro cell experiments dissecting the signalling effectors involved in the NOS-mediated regulation that justify new therapeutic interventions on the NOS-cGMP axis to attenuate the development of heart failure.

Diltiazem poisoning treated with hyperinsulinemic euglycemia therapy and intravenous lipid emulsion.

Intravenous lipid emulsion (ILE) has been proposed as a rescue therapy for severe local anesthetic drugs toxicity, but experience is limited with other lipophilic drugs. An 18-year-old healthy woman was admitted 8 h after the voluntary ingestion of sustained-release diltiazem (3600 mg), with severe hypotension refractory to fluid therapy, calcium salts, and high-dose norepinephrine (6.66 µg/kg/min). Hyperinsulinemic euglycemia therapy was initiated and shortly after was followed by a protocol of ILE (intralipid 20%, 1.5 ml/kg as bolus, followed by 0.25 ml/kg over 1h). The main finding attributed to ILE was an apparent rapid decrease in insulin resistance, despite a prolonged serum diltiazem elimination half-life. Diltiazem is a lipophilic cardiotoxic drug, which could be sequestered in an expanded plasma lipid phase. The mechanism of action of ILE is not known, including its role in insulin resistance and myocardial metabolism in calcium-channel blocker poisoning.

Multiple organ failure after an overdose of less than 0.4 mg/kg of colchicine: role of coingestants and drugs during intensive care management.

INTRODUCTION: Although the ingestion of a dose of colchicine lower than 0.5 mg/kg is usually complicated by a mortality rate less than 5%, severe complications may be associated with drug-drug interactions in case of overdose combining other drugs. CASE REPORT: A 33-year-old previously healthy woman was admitted after a drug overdose combining colchicine, atorvastatin, ibuprofen, diclofenac, and furosemide. The amount of colchicine ingested was exactly 20 mg, corresponding to 0.33 mg/kg. Despite this relatively low dose, she presented the clinical course that is usually seen with much larger colchicine ingestions. She developed acute renal and liver failure, acute lung injury, pancytopenia with sepsis, rhabdomyolysis, hypertriglyceridemia, and ultimately died on Day 14 from hyperammonemic encephalopathy, refractory hypoxemia, and cardiac arrhythmias. DISCUSSION: Serious drug-drug interactions may have complicated colchicine poisoning. In particular, atorvastatin, an inhibitor of P-glycoprotein and cytochrome P450 3A4, was likely responsible for an increased severity of rhabdomyolysis. In addition, propofol used for sedation during mechanical ventilation may have induced symptoms consistent with "propofol infusion syndrome," with further muscular injury and hypertriglyceridemia. The mechanism of death was unusual and similar to Reye's syndrome.

Refractory High Intracranial Pressure following Intraventricular Hemorrhage due to Moyamoya Disease in a Pregnant Caucasian Woman.

Intraventricular hemorrhage during pregnancy is usually followed by a poor recovery. When caused by moyamoya disease, ischemic or hemorrhagic episodes may complicate the management of high intracranial pressure. A 26-year-old Caucasian woman presented with generalized seizures and a Glasgow Coma Score (GCS) of 3 during the 36th week of pregnancy. The fetus was delivered by caesarean section. The brain CT in the mother revealed bilateral intraventricular hemorrhage, a callosal hematoma, hydrocephalus and right frontal ischemia. Refractory high intracranial pressure developed and required bilateral ventricular drainage and intensive care treatment with barbiturates and hypothermia. Magnetic resonance imaging and cerebral angiography revealed a moyamoya syndrome with rupture of the abnormal collateral vascular network as the cause of the hemorrhage. Intracranial pressure could only be controlled after the surgical removal of the clots after a large opening of the right ventricle. Despite an initially low GCS, this patient made a good functional recovery at one year follow-up. Management of refractory high intracranial pressure following moyamoya related intraventricular bleeding should require optimal removal of ventricular clots and appropriate control of cerebral hemodynamics to avoid ischemic or hemorrhagic complications.