Environmental organophosphate co‐exposure in pre‐existing systemic inflammation can Increase susceptibility to SARS‐COV‐2 infection in human lung epithelial cells

Mondal, Ayan; Bose, Dipro; Saha, Punnag; Seth, Ratanesh; Nagarkatti, Mitzi; Nagarkatti, Prakash; Chatterjee, Saurabh

Environmental exposures from pollutants in air, water and food cause systemic inflammatory events to persist. Studies have shown that environmental co exposures alter the microbiome profile and cause long lasting systemic inflammation. This is common in the general population as well as a certain subsection of veterans having Gulf War Illness who were co exposed to organophosphates decades ago. With COVID19 pandemic claiming more than 335,000 deaths in USA alone, we aimed to study the susceptibility of SARS‐COV‐2 virus entry and its potential inflammatory mechanisms in the lung epithelial cells following co‐exposure to IL6 and pesticide chlorpyrifos. Notably, a recent report confirms more than 160,000 positive SARS‐COV‐2 cases of veterans with mortality rate of more than 4%. Recent studies from our laboratory and others suggested that pesticide exposure during war theater and increased IL‐6 in blood serum played pivotal role in physiological complications which include neurological and gastrointestinal disturbances. In the present report, we aim to identify whether pesticides and IL‐6 co‐exposure increases the risk of SARS‐COV‐2 infection by invitro studies with human lung airway epithelial cells. Cells were exposed to organophosphate Chlorpyriphos (20 µg/ml) or human recombinant IL‐6 (20 pg/ml) or with both for 6 h and treated with recombinant SARS‐COV‐2 spike protein (50 ng/ml) and observed for Angiotensin Converting Enzyme 2 expression (ACE2) on the apical or basolateral surface of airway epithelial cells. ACE‐2 has been identified as putative receptor for SARS‐COV‐2 entry where it's spike protein pivotal to the entry of viral particle in cells. With reports showing abundant expression of ACE2 receptor protein to apical surface of polarized epithelial cells might support viral entry and replication in host cells, we performed Immunofluorescence microscopy to study ACE 2 protein expression in Apical cell surface (FoxJ1) or in basolateral cell surface (Sodium‐Potassium ATPase 2). Results showed organophosphate and IL 6 exposure significantly increased ACE2 protein expression on the apical cell surface compared to when cells were unexposed or exposed with organophosphate alone. Furthermore, results showed that co exposure of IL 6 and organophosphate were instrumental in increased apoptosis of lung airway epithelial cells in presence of SARS‐COV‐2 spike protein compared to untreated cells. The following results though preliminary may pave the way for more mechanistic studies in rodent models to identify mechanisms of susceptibility of severe COVID19 outcomes in the general population and veterans who were co exposed to environmental agents in early life.