Mechanisms of exacerbation of COVID-19 pathogenesis in mice expressing human ACE2 by polycyclic aromatic hydrocarbons (PAHs), and its protection by inhibition of soluble epoxide hydrolase (sEH)

Project Summary Severe coronavirus disease (COVID-19) is caused by a novel Beta-coronavirus, now named SARS-CoV-2. COVID-19 is characterized by unresolved systemic hyperinflammation associated with a life-threatening "cytokine storm syndrome", leading to multi-organ failure dysfunction in some patients. Recent studies have shown that cigarette smoking and other environmental pollutants exacerbate respiratory illness in COVID-19 infected individuals, but the mechanisms responsible for the potentiation of lung disease is not known. Models of lung damage due to environmental chemicals (e.g., cigarette smoking) include the use of polycyclic aromatic hydrocarbons (PAH), especially benzo[a]pyrene (BP), which are present in cigarette smoke, charbroiled steaks, diesel exhausts etc. In these models, additional hyperoxic exposure leads to exacerbation of ARDS-like symptoms. Current data suggests that using a soluble epoxide hydrolase inhibitor (sEHI) protects against lung injury related to ARDS, as they prevent hydration of anti-inflammatory eicosanoids [e.g., epoxy eicasotrienoic acids (EETs). The central hypothesis proposed in this application is that BP would exacerbate lung injury/inflammation during SARS-CoV-2 infection, and subsequent hyperoxia exposure, and that treatment of these mice with sEHI would confer protection against lung injury. Gene expression profiling using single cell RNA-Seq and FACS approaches will be done to determine the molecular pathways of lung injury and inflammation mediated by BP/SARS-CoV- 2/hyperoxia. We propose the following specific aims: 1. To test the hypothesis that transgenic K18-hACE2 mice that are treated with BP prior to infection with SARS-CoV-2 will be more susceptible to lung injury than those that are mock treated prior to infection. We will also test the hypothesis that treatment with the sEHI TPPU will confer protection against lung injury/ARDS in the BP/SARS-COV-2/-exposed mice. Gene expression profiling using single cell RNA-seq will be performed to determine the role of specific lung cells in lung injury mediated by BP/SARS-CoV-2 and its protection by sEHI. 2. To test the hypothesis that exposure of BP/SARS-CoV-2 treated mice to hyperoxia will lead to further exacerbation of lung injury compared to those maintained in room air, and that these mice will display lesser injury if they were exposed to sEHI treatment during the hyperoxia phase. The proposed studies will unravel molecular mechanisms of lung injury mediated by SARS-CoV-2/hyperoxia, and its potentiation by environmental PAHs. Furthermore, if our sEHI studies aimed to protect mice against COVID-19 pathogenesis, it will be a big step towards future clinical trials on the use of sEHs for treatment of COVID019 in humans.