-Author name in bold denotes the presenting author
-Asterisk * with author name denotes a Non-ASH member
Clinically Relevant Abstract denotes an abstract that is clinically relevant.

PhD Trainee denotes that this is a recommended PHD Trainee Session.

Ticketed Session denotes that this is a ticketed session.

3938 Loss of Platelet 12-Lipoxygenase Aggravates the Severity of Sars-Cov-2 Infection

Program: Oral and Poster Abstracts
Session: 301. Vasculature, Endothelium, Thrombosis and Platelets: Basic and Translational: Poster III
Hematology Disease Topics & Pathways:
Fundamental Science, Research, Diseases, SARS-CoV-2/COVID-19, Infectious Diseases
Monday, December 11, 2023, 6:00 PM-8:00 PM

Ana Claudia Andrade, PhD1*, Emile Lacasse2*, Isabelle Dubuc3*, Leslie Gudimard1*, Florian Puhm2*, Celso Queiroz4*, Isabelle Allaeys, PhD1*, Julien Prunier5*, Élizabeth Dumais6*, Nicolas Flamand6*, Arnaud Droit1*, Eric Boilard, PhD1 and Louis Flamand, PhD7*

1Centre de recherche du CHU de Québec-Université Laval, Quebec, QC, Canada
2Centre de recherche du CHU de Québec-Université Laval, Quebec, Quebec, CAN
3Centre de recherche du CHU de Québec-Université Laval, Quebec, QC, CAN
4Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
5Centre de recherche du CHU de Quebec-Université Laval, Quebec, QC, Canada
6Université Laval, Quebec City, QC, CAN
7Centre recherche du CHU de Quebec- Universite Laval, Quebec City, QC, Canada

Uncontrolled inflammation and dysregulation of platelet activity, leading to venous thromboembolic events are hallmark pathological findings of severe COVID-19. Considering that 12-lipoxygenase (12-LOX) is a key enzyme regulating platelet activity, we investigated its contribution during SARS-CoV-2 infection.

To examine the role of platelet-type 12-LOX, we performed intranasal infections of angiotensin-converting enzyme 2 transgenic mice (K18-hACE2) and K18-hACE2 knockout mice for the Alox12 gene, which encodes the platelet 12-LOX enzyme, using 500 TCID50 of the SARS-CoV-2 Delta strain. Notably, Alox12 knockout mice exhibited more severe disease and higher lethality. To decipher the drivers of this increased severity, we evaluated pulmonary tissue inflammation in mice. The Alox12 knockout mice showed elevated levels of central inflammatory cytokines/chemokines such as IFN-α, IFN-γ, IL-6, CCL-3, CCL-2, CCL-4, CXCL-1, CXCL-9 measured by Luminex multiplex assays. These results were corroborated by histopathological analysis, indicating a higher inflammatory score on the third and fifth day post-infection. Despite 12-LOX's role in platelet activation, we found no signs of higher coagulation processes in the pulmonary tissues of knockout animals, as evidenced by histopathology and preliminary transcriptome analysis of lung tissue.

Furthermore, we investigated the effect of 12-LOX loss on whole blood leukocyte populations by flow cytometry throughout the infection. No significant differences in these populations were observed in the knockout animals relative to WT mice. To explore the impact of 12-LOX metabolites on pulmonary inflammation, we performed mass spectrometry analysis of the main biolipids. Our study unveiled a significant decrease in the levels of inflammatory mediators, namely 12-HETrE, PGE1, 12-HEPE, Maresin-2, 12-HETE, 15-HETE, 11-HETE, LTB4, and 12-KETE, in the lungs of Alox12 knockout mice.

Taken together, our results underscore the critical role of platelet 12-LOX in regulating pulmonary inflammation during SARS-CoV-2 infection. Loss of this enzyme disrupts even more the production of inflammatory mediators following infection, exacerbating disease severity. Our findings highlight the relevance of platelet 12-LOX activity in the regulation of pulmonary inflammation after SARS-CoV-2 infection, shedding light on potential therapeutic targets.

Disclosures: No relevant conflicts of interest to declare.

*signifies non-member of ASH