COVID-19 and platelet derived DNA in acute respiratory distress syndrome (ARDS) – PlatdeDNA
COVID-19 and Platelet derived DNA in acute respiratory syndrome (ARDS)
The recent and persistent COVID pandemic is adding to the high death toll rate largely due to virus infection induced severe acute respiratory distress syndrome (ARDS) with strong lung inflammation, disruption of the alveolar barrier, acute lung edema, sudden respiratory failure and pulmonary thrombosis. Platelets trigger the thrombotic process and amplify inflammation through interaction with granulocytes generating extracellular dsDNA release, neutrophil extracellular traps, the release of bioactive substances along with the generation of procoagulant platelets in addition to canonical aggregation.
General objective of the project and the main issues raised
It remains currently unknown precisely whether platelet activation contribute to the release of extracellular double-stranded DNA (dsDNA) during SARS-Cov-2 infection and severe acute lung inflammation. We hypothesized that platelet-derived cell-free DNA is recognized by the cGAS/STING pathway and may drive a type I IFN-response in immune cells. This may lead to neutrophilic respiratory inflammation with acute alveolitis known as ARDS. <br />To test this hypothesis, we investigated the following aspects of platelet-related acute lung inflammation in sterile inflammation and virus induced ARDS:<br />1. DNA release by activated platelets in vitro; and activation of platelet-derived DNA of cGAS/STING reporter and gene deficient mice;<br />2. Selective platelets depletion affecting sterile and SARS-CoV-2 induced ARDS;<br />3. Effect of pharmacological inhibition of cGAS/STING on experimental ARDS;
Our consortium of two French teams and two international collaborators, which are experts in lung inflammation, virus infection, innate immunity, molecular and cell biology, is addressing these issues using advanced models, clinical samples and pluridisciplinary and cutting-edge technologies.
We show increase in circulating dsDNA levels in COVID-19 patients (n=30) which is however not correlated with platelet counts. Co-culture of purified mouse platelets with macrophages in vitro highlighted their negative regulation of pro-inflammatory cytokine production. Platelets depletion in vivo using specific neutralizing antibody against CD42b (?CD42b) yielded disease worsening with increased clinical score, viral load in in oropharyngeal swabs and pro-inflammatory cytokines production.
Further analysis and investigations are needed to better understand and consolidate the results.
None
The COVID pandemic causes severe acute respiratory distress syndrome (ARDS) with severe respiratory barrier damage, inflammation, edema and often respiratory failure. Platelets are involved in thrombosis and contribute to innate immunity. Platelets expressing ACE2 are abundant in the lungs and upon activation release mitochondrial DNA. We hypothesize that platelets are an important source of extracellular DNA activating the cGAS and STING pathway triggering lung inflammation. Thus, reducing platelets, cell free DNA and/or targeting the cGAS/STING pathway may dampen ARDS.
Clinical samples from COVID-19 patients (n = 84) and non-COVID-19 patients (n=17) collected from endotracheal aspirates, plasma and PBMC will be analyzed for platelet counts and activation, self-DNA levels in the aspirates and in plasma and correlated with clinical parameters and survival.
Experimental studies of in vitro activated platelets and in vivo SARS-CoV-2 infection in a novel huACE2 KI mice will address the following aspects of platelet-related questions: i) DNA release by in vitro activated platelets; ii) activation of platelet-derived DNA on cGAS/STING reporter and gene deficient mice; iii) selective platelets depletion affecting sterile and SARS-CoV-2 infection induced ARDS; iv) effect of pharmacological inhibition of cGAS/STING in experimental ARDS.
Our consortium of two French teams and two international collaborators, which are experts in lung inflammation, virus infection, innate immunity, molecular and cell biology, will address these issues using advanced models, clinical samples and pluridisciplinary and cutting-edge technologies. The data may be exploited to develop innovative therapeutic options for severe COVID-19.
Project coordination
Dieudonnée TOGBE (Immunologie et neurogénétique expérimentales et moléculaires)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
Partner
INEM Immunologie et neurogénétique expérimentales et moléculaires
CEPR Centre d'Etude des Pathologies Respiratoires
Help of the ANR 79,990 euros
Beginning and duration of the scientific project:
May 2021
- 12 Months
