Publications by authors named "N Lorent"

37 Publications

Monocyte-driven atypical cytokine storm and aberrant neutrophil activation as key mediators of COVID-19 disease severity.

Nat Commun 2021 07 5;12(1):4117. Epub 2021 Jul 5.

KU Leuven Flow & Mass Cytometry Facility, KU Leuven, Leuven, Belgium.

Epidemiological and clinical reports indicate that SARS-CoV-2 virulence hinges upon the triggering of an aberrant host immune response, more so than on direct virus-induced cellular damage. To elucidate the immunopathology underlying COVID-19 severity, we perform cytokine and multiplex immune profiling in COVID-19 patients. We show that hypercytokinemia in COVID-19 differs from the interferon-gamma-driven cytokine storm in macrophage activation syndrome, and is more pronounced in critical versus mild-moderate COVID-19. Systems modelling of cytokine levels paired with deep-immune profiling shows that classical monocytes drive this hyper-inflammatory phenotype and that a reduction in T-lymphocytes correlates with disease severity, with CD8+ cells being disproportionately affected. Antigen presenting machinery expression is also reduced in critical disease. Furthermore, we report that neutrophils contribute to disease severity and local tissue damage by amplification of hypercytokinemia and the formation of neutrophil extracellular traps. Together our findings suggest a myeloid-driven immunopathology, in which hyperactivated neutrophils and an ineffective adaptive immune system act as mediators of COVID-19 disease severity.
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http://dx.doi.org/10.1038/s41467-021-24360-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8257697PMC
July 2021

The Antimicrobial Activity of Peripheral Blood Neutrophils Is Altered in Patients with Primary Ciliary Dyskinesia.

Int J Mol Sci 2021 Jun 8;22(12). Epub 2021 Jun 8.

Laboratory of Molecular Immunology, Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, University of Leuven, 3000 Leuven, Belgium.

The airways of patients with primary ciliary dyskinesia (PCD) contain persistently elevated neutrophil numbers and CXCL8 levels. Despite their abundance, neutrophils fail to clear the airways from bacterial infections. We investigated whether neutrophil functions are altered in patients with PCD. Neutrophils from patients and healthy controls (HC) were isolated from peripheral blood and exposed to various bacterial stimuli or cytokines. Neutrophils from patients with PCD were less responsive to low levels of fMLF in three different chemotaxis assays ( < 0.05), but expression of the fMLF receptors was unaltered. PCD neutrophils showed normal phagocytic function and expression of adhesion molecules. However, PCD neutrophils produced less reactive oxygen species upon stimulation with bacterial products or cytokines compared to HC neutrophils ( < 0.05). Finally, the capacity to release DNA, as observed during neutrophil extracellular trap formation, seemed to be reduced in patients with PCD compared to HC ( = 0.066). These results suggest that peripheral blood neutrophils from patients with PCD, in contrast to those of patients with cystic fibrosis or COPD, do not show features of over-activation, neither on baseline nor after stimulation. If these findings extend to lung-resident neutrophils, the reduced neutrophil activity could possibly contribute to the recurrent respiratory infections in patients with PCD.
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http://dx.doi.org/10.3390/ijms22126172DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8230338PMC
June 2021

Early lung ultrasound assessment for the prognosis of patients hospitalized for COVID-19 pneumonia. A pilot study.

Respir Med Res 2021 Jun 4;80:100832. Epub 2021 Jun 4.

Department of Respiratory Diseases, University Hospitals KU Leuven, Herestraat 49, 3000 Leuven, Belgium.

Objective: SARS CoV-2 is an epidemic viral infection that can cause mild to severe lung involvement. Newly apprehended knowledge on thoracic imaging abnormalities and the growing clinical experience on the evolution of this disease make the radiographic follow-up of hospitalized patients relevant. The value of consecutive bedside lung ultrasonography in the follow-up of hospitalized patients with SARS CoV-2 pneumonia and its correlation with other clinical and laboratory markers needs to be evaluated.

Methods: We assessed 39 patients [age: 64 y(60.1-68.7)] with confirmed SARS CoV-2 pneumonia. A total of 24 patients were hospitalized until the follow-up test, 9 were discharged early and 6 required a transfer to critical care unit. Two ultrasound scans of the lung were performed on day 1 and 4 of patients' hospitalization. Primary endpoint was the magnitude of association between a global lung ultrasound score (LUS) and clinical and laboratory markers. Secondary endpoint was the association between the evolution of LUS with the corresponded changes in clinical and laboratory outcomes during hospitalization period.

Results: LUS score on admission was higher among the deteriorating patients and significantly (P=0.038-0.0001) correlated (Spearman's rho) with the levels of C-reactive protein (0.58), lymphocytes (-0.33), SpO (-0.48) and oxygen supplementation (0.48) upon admission. The increase in LUS score between the two scans was significantly correlated (0.544, P=0.006) with longer hospital stay.

Conclusion: Lung ultrasound assessment can be a useful as an imaging modality for SARS CoV-2 patients. Larger studies are needed to further investigate the predictive role of LUS in the duration and the outcome of the hospitalization of these patients.
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http://dx.doi.org/10.1016/j.resmer.2021.100832DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8177497PMC
June 2021

Venous Thromboembolism in Patients Discharged after COVID-19 Hospitalization.

Semin Thromb Hemost 2021 Jun 23;47(4):362-371. Epub 2021 Apr 23.

Department of Cardiovascular Diseases, University Hospitals Leuven, Leuven, Belgium.

Background:  Venous thromboembolism (VTE) is a frequent complication of COVID-19, so that the importance of adequate in-hospital thromboprophylaxis in patients hospitalized with COVID-19 is well established. However, the incidence of VTE after discharge and whether postdischarge thromboprophylaxis is beneficial and safe are unclear. In this prospective observational single-center study, we report the incidence of VTE 6 weeks after hospitalization and the use of postdischarge thromboprophylaxis.

Methods:  Patients hospitalized with confirmed COVID-19 were invited to a multidisciplinary follow-up clinic 6 weeks after discharge. D-dimer and C-reactive protein were measured, and all patients were screened for deep vein thrombosis with venous duplex-ultrasound. Additionally, selected high-risk patients received computed tomography pulmonary angiogram or ventilation-perfusion (V/Q) scan to screen for incidental pulmonary embolism.

Results:  Of 485 consecutive patients hospitalized from March through June 2020, 146 patients were analyzed, of which 39% had been admitted to the intensive care unit (ICU). Postdischarge thromboprophylaxis was prescribed in 28% of patients, but was used more frequently after ICU stay (61%) and in patients with higher maximal D-dimer and C-reactive protein levels during hospitalization. Six weeks after discharge, elevated D-dimer values were present in 32% of ward and 42% of ICU patients. Only one asymptomatic deep vein thrombosis (0.7%) and one symptomatic pulmonary embolism (0.7%) were diagnosed with systematic screening. No bleedings were reported.

Conclusion:  In patients who had been hospitalized with COVID-19, systematic screening for VTE 6 weeks after discharge revealed a low incidence of VTE. A strategy of selectively providing postdischarge thromboprophylaxis in high-risk patients seems safe and potentially effective.
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http://dx.doi.org/10.1055/s-0041-1727284DOI Listing
June 2021

Elevated serum calprotectin (S100A8/A9) in patients with severe asthma.

J Asthma 2021 Apr 19:1-6. Epub 2021 Apr 19.

Laboratory of Respiratory Diseases and Thoracic Surgery (BREATHE), Department of Chronic Diseases, Metabolism and Ageing (CHROMETA), KU Leuven, Leuven, Belgium.

Objective: Asthma is a heterogeneous disease consisting of several inflammatory phenotypes of which neutrophilic asthma is associated with poorer responses to classic therapies, namely (inhaled) corticosteroids. The development of targeted therapies requires the identification of biomarkers to distinguish these phenotypes. Currently, we lack validated biomarkers for non-eosinophilic asthma. The aim of this study is to examine serum calprotectin (SC) in asthmatics and its potential as biomarker for neutrophilic asthma.

Methods: Hundred-seventeen severe asthmatics were referred for sputum induction and data were obtained from their medical records. To evaluate the association between SC and asthma phenotypes, patients were divided into subgroups based on sputum cell count (3% eosinophils and 61% neutrophils). Additionally, SC levels of asthmatics were compared with these of patients with chronic obstructive pulmonary disease, non-cystic fibrosis bronchiectasis and healthy controls.

Results: Asthmatics ( = 45) had significantly higher levels of SC than healthy controls. No significant differences were found between the different asthma phenotypes and in comparison with COPD patients. SC was significantly higher in asthmatics with a lower FEV/FVC ratio (<70) and non-significantly elevated SC levels were seen in asthmatics with frequent exacerbations (>2 in the last year).

Conclusion: In conclusion, there was no difference in SC levels between the different inflammatory subtypes in asthmatics. Nevertheless, severe asthmatics seemed to have higher SC levels suggesting that SC may be a marker of disease severity rather than a marker for specific inflammatory subtypes in asthmatics. Further research in larger cohorts is necessary to validate SC as biomarker in severe asthmatics.
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http://dx.doi.org/10.1080/02770903.2021.1914649DOI Listing
April 2021
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