Neutrophil extracellular trap biomarkers in aneurysmal subarachnoid hemorrhage: early decline of DNase 1 activity associated with delayed cerebral ischemia

Introduction

High-mobility group box 1 (HMGB1) protein is a critical mediator of neutrophil extracellular trap (NET) formation (NETosis). Myeloperoxidase (MPO)-DNA complexes, a biomarker of NETs, and HMGB1 have been associated with delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). Additional mechanistic NET-related biomarkers and their role in the neuroinflammatory cascade surrounding DCI remain to be explored.

Methods

A post-hoc analysis of a prospective, blinded, single-center biomarker observational study was performed. De novo measurements of serum citrullinated histone H3-DNA complexes (H3Cit-DNA), peptidylarginine deiminase 4 (PAD4), cell-free DNA (cf-DNA), and DNase 1 activity were conducted on admission (D0) and day 4 (D4). Delayed cerebral infarction (DCI) was defined as new cerebral infarction on CT head not present on the post-treatment scan.

Results

H3Cit-DNA, PAD4, cf-DNA, and DNase 1 activity were within quantifiable ranges in all serum samples analyzed at D0 and D4. Admission biomarker levels were not associated with DCI development. From D0 to D4, in both the DCI and the non-DCI groups, H3Cit-DNA levels significantly decreased, cf-DNA levels significantly increased, and PAD4 levels remained stable. In contrast, DNase 1 activity significantly decreased from D0 to D4 in the DCI group (p < 0.001) but not in the non-DCI group.

Conclusion

This exploratory analysis demonstrated NET-related biomarkers such as H3Cit-DNA, PAD4, cf-DNA, and DNase 1 activity in all aSAH patients. A decline of systemic DNase 1 activity in the early phase might increase the risk of delayed cerebral ischemia.

Lower respiratory tract single-cell RNA sequencing and neutrophil extracellular trap profiling of COVID-19-associated pulmonary aspergillosis: a single centre, retrospective, observational study

BACKGROUND

COVID-19-associated pulmonary aspergillosis (CAPA) is a severe superinfection with the fungus Aspergillus affecting patients who are critically ill with COVID-19. The pathophysiology and the role of neutrophil extracellular traps (NETs) in this infection are largely unknown. We aimed to characterise the immune profile, with a focus on neutrophils and NET concentrations, of critically ill patients with COVID-19, with or without CAPA.

METHODS

We conducted a single-centre, retrospective, observational study in two patient cohorts, both recruited at University Hospitals Leuven, Belgium. We included adults aged 18 years or older who were admitted to the intensive care unit because of COVID-19 between March 31, 2020, and May 18, 2021, and who were included in the previous Contagious trial (NCT04327570). We investigated the immune cellular landscape of CAPA versus COVID-19 only by performing single-cell RNA sequencing (scRNA-seq) on bronchoalveolar lavage fluid. Bronchoalveolar lavage immune cell fractions were compared between patients with CAPA and patients with COVID-19 only. Additionally, we determined lower respiratory tract NET concentrations using biochemical assays in patients aged 18 years and older who were admitted to the intensive care unit because of severe COVID-19 between March 15, 2020, and Dec 31, 2021, for whom bronchoalveolar lavage was available in the hospital biobank. Bronchoalveolar lavage NET concentrations were compared between patients with CAPA and patients with COVID-19 only and integrated with existing data on immune mediators in bronchoalveolar lavage and 90-day mortality.

FINDINGS

We performed scRNA-seq of bronchoalveolar lavage on 43 samples from 39 patients, of whom 36 patients (30 male and six female; 14 with CAPA) were included in downstream analyses. We performed bronchoalveolar lavage NET analyses in 59 patients (46 male and 13 female), of whom 26 had CAPA. By scRNA-seq, patients with CAPA had significantly lower neutrophil fractions than patients with COVID-19 only (16% vs 33%; p=0·0020). The remaining neutrophils in patients with CAPA preferentially followed a hybrid maturation trajectory characterised by expression of genes linked to antigen presentation, with enhanced transcription of antifungal effector pathways. Patients with CAPA also showed depletion of mucosal-associated invariant T cells, reduced T helper 1 and T helper 17 differentiation, and transcriptional defects in specific aspects of antifungal immunity in macrophages and monocytes. We observed increased formation of NETs in patients with CAPA compared with patients with COVID-19 only (DNA complexed with citrullinated histone H3 median 15 898 ng/mL [IQR 4588-86 419] vs 7062 ng/mL [775-14 088]; p=0·042), thereby explaining decreased neutrophil fractions by scRNA-seq. Low bronchoalveolar lavage NET concentrations were associated with increased 90-day mortality in patients with CAPA.

INTERPRETATION

Qualitative and quantitative disturbances in monocyte, macrophage, B-cell, and T-cell populations could predispose patients with severe COVID-19 to develop CAPA. Hybrid neutrophils form a specialised response to CAPA, and an adequate neutrophil response to CAPA is a major determinant for survival in these patients. Therefore, measuring bronchoalveolar lavage NETs could have diagnostic and prognostic value in patients with CAPA. Clinicians should be wary of aspergillosis when using immunomodulatory therapy that might inhibit NETosis to treat patients with severe COVID-19.

FUNDING

Research Foundation Flanders, KU Leuven, UZ Leuven, VIB, the Fundação para a Ciência e a Tecnologia, the European Regional Development Fund, la Caixa Foundation, the Flemish Government, and Horizon 2020.

Modulation of thromboinflammation in hospitalized COVID-19 patients with aprotinin, low molecular weight heparin, and anakinra: The DAWn-Antico study

Background

Thromboinflammation plays a central role in severe COVID-19. The kallikrein pathway activates both inflammatory pathways and contact-mediated coagulation. We investigated if modulation of the thromboinflammatory response improves outcomes in hospitalized COVID-19 patients.

Methods

In this multicenter open-label randomized clinical trial (EudraCT 2020-001739-28), patients hospitalized with COVID-19 were 1:2 randomized to receive standard of care (SOC) or SOC plus study intervention. The intervention consisted of aprotinin (2,000,000 IE IV four times daily) combined with low molecular weight heparin (LMWH; SC 50 IU/kg twice daily on the ward, 75 IU/kg twice daily in intensive care). Additionally, patients with predefined hyperinflammation received the interleukin-1 receptor antagonist anakinra (100 mg IV four times daily). The primary outcome was time to a sustained 2-point improvement on the 7-point World Health Organization ordinal scale for clinical status, or discharge.

Findings

Between 24 June 2020 and 1 February 2021, 105 patients were randomized, and 102 patients were included in the full analysis set (intervention N = 67 vs. SOC N = 35). Twenty-five patients from the intervention group (37%) received anakinra. The intervention did not affect the primary outcome (HR 0.77 [CI 0.50-1.19], p = 0.24) or mortality (intervention n = 3 [4.6%] vs. SOC n = 2 [5.7%], HR 0.82 [CI 0.14-4.94], p = 0.83). There was one treatment-related adverse event in the intervention group (hematuria, 1.49%). There was one thrombotic event in the intervention group (1.49%) and one in the SOC group (2.86%), but no major bleeding.

Conclusions

In hospitalized COVID-19 patients, modulation of thromboinflammation with high-dose aprotinin and LMWH with or without anakinra did not improve outcome in patients with moderate to severe COVID-19.

Inflammation and echocardiographic ventricular function in patients with a systemic right ventricle and heart failure

Background

Clinical deterioration is fast once heart failure (HF) develops in patients with a systemic right ventricle (sRV) [1]. Despite its established role in HF patients with a normal heart anatomy [2,3], little is known about the contribution of inflammation in sRV-HF patients.

Aims

To assess inflammation and echocardiography in sRV patients with or without HF and to relate inflammation to echocardiographic ventricular function.

Methods

In this cross-sectional prospective study, patients with a sRV due to Senning/Mustard repair or due to congenitally corrected transposition of the great arteries (ccTGA) were consecutively enrolled at the outpatient clinic of a single, tertiary care center. Echocardiography and venipuncture were performed on the same day. C-reactive protein (CRP), red cell distribution width (RDW), neutrophil-lymphocyte ratio (NLR), myeloperoxidase (MPO), myeloperoxidase and citrullinated histone H3-DNA complexes (MPO-DNA and H3Cit-DNA) and interleukin 10 were measured. Patients were stratified based on the presence or absence of HF, with HF defined as having signs and/or symptoms of HF requiring medical therapy plus one of the following: impaired ventricular function with elevated intracardiac pressures, elevated N-terminal pro-brain natriuretic peptide, and/or peak oxygen consumption in lowest quartile (according to published norms for TGA patients). Comparative statistics and univariate correlations were performed.

Results

Eighty-seven patients were included (mean age 39 years; 69% male; 25% ccTGA, 68% NYHA class I) from which one third (29/87) had HF. Most inflammatory markers were significantly higher in the HF group compared to non-HF: CRP (4.3 vs 2.21 mg/dL; P=0.016), RDW (13.6 vs 12.7 fL; P&lt;0.001), NLR (3.6 vs 2.9; P=0.01), MPO (171 vs 139 ng/mL; P=0.03) and MPO-DNA (1.4 vs 1.2; P=0.04). When assessing systolic function, HF patients had: i) lower strain of the sRV free wall (10.9 vs 13.1%; P=0.008), ii) lower mitral annular plane systolic excursion (MAPSE) (1.7 vs 2.1 cm; P&lt;0.001) and iii) lower strain rate (SR) of the subpulmonary LV (spLV) (1.0 vs 1.3 S-1; P=0.03). The spLV was also more hypertrophied (end-diastolic LV posterior wall 0.99 vs 0.79 cm; P=0.007) and more dilated (end-diastolic LV internal diameter 4.1 vs 3.3 cm; P=0.006) in HF. CRP and RDW showed the strongest correlations (Spearman correlation coefficient r&gt;0.29) with LV and RV ventricular function. CRP correlated with lateral tricuspid annular systolic velocity (r=−0.313**), strain of the free wall (r=−0.317**) and global longitudinal strain (r=−0.292**) of the sRV. RDW correlated with MAPSE (r=−0.313**). **P&lt;0.01.

Conclusions

sRV patients in HF have more systemic inflammation and lower RV free wall strain. With more remodeling and a lower MAPSE and SR of the spLV, the LV cannot be ignored when evaluating HF in sRV patients. Correlation between inflammation and ventricular systolic function, however, is limited.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): ERA-CVD JTC2019 (Fonds Wetenschappelijk Onderzoek G0G1719N to K.M. and A.V.D.B); German Bundesministerium für Bildung und Forschung 01KL2001 to T.W.)

Neutrophil Extracellular Traps and Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage

IMPORTANCE

Myeloperoxidase (MPO)-DNA complexes, biomarkers of neutrophil extracellular traps (NETs), have been associated with arterial and venous thrombosis. Their role in aneurysmal subarachnoid hemorrhage (aSAH) is unknown.

OBJECTIVES

To assess whether serum MPO-DNA complexes are present in patients with aSAH and whether they are associated with delayed cerebral ischemia (DCI).

DESIGN SETTING AND PARTICIPANTS

Post-hoc analysis of a prospective, observational single-center study, with de novo serum biomarker measurements in consecutive patients with aSAH between July 2018 and September 2020, admitted to a tertiary care neuroscience ICU.

MAIN OUTCOMES AND MEASURES

We analyzed serum obtained at admission and hospital day 4 for concentrations of MPO-DNA complexes. The primary outcome was DCI, defined as new infarction on brain CT. The secondary outcome was clinical vasospasm, a composite of clinical and transcranial Doppler parameters. We used Wilcoxon signed-rank-test to assess for differences between paired measures.

RESULTS

Among 100 patients with spontaneous subarachnoid hemorrhage, mean age 59 years (sd ± 13 yr), 55% women, 78 had confirmed aSAH. Among these, 29 (37%) developed DCI. MPO-DNA complexes were detected in all samples. The median MPO-DNA level was 33 ng/mL (interquartile range [IQR], 18-43 ng/mL) at admission, and 22 ng/mL (IQR, 11-31 ng/mL) on day 4 (unpaired test; p = 0.015). We found a significant reduction in MPO-DNA levels from admission to day 4 in patients with DCI (paired test; p = 0.036) but not in those without DCI (p = 0.17). There was a similar reduction in MPO-DNA levels between admission and day 4 in patients with (p = 0.006) but not in those without clinical vasospasm (p = 0.47).

CONCLUSIONS AND RELEVANCE

This is the first study to detect the NET biomarkers MPO-DNA complexes in peripheral serum of patients with aSAH and to associate them with DCI. A pronounced reduction in MPO-DNA levels might serve as an early marker of DCI. This diagnostic potential of MPO-DNA complexes and their role as potential therapeutic targets in aSAH should be explored further.

Thromboprophylaxis in COVID‐19: Weight and severity adjusted intensified dosing

Background

Aims

Methods

Results

Conclusion