People with metabolic diseases like Type-2 diabetes and cancer as well as those exposed to organophosphate pesticides can be at an increased risk of COVID-19 infection, finds a new study performed in human lung airway cells.

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The study, led by Saurabh Chatterjee and the team from the University of South Carolina in the US, identified a basic mechanism linked with inflammation that could increase susceptibility to Covid-19 infection among people exposed to organophosphates. The findings showed that people with Type-2 diabetes and cancer may also be at increased risk to Covid because they tend to exhibit the same type of inflammation. Exposure to organophosphate pesticides causes Gulf War Illness -- a cluster of medically unexplained chronic symptoms that can include fatigue, headaches, joint pain, indigestion, insomnia, dizziness, respiratory disorders and memory problems.

The team examined whether exposure to the organophosphate pesticide chlorpyriphos and increased levels of interleukin 6 (IL-6) could increase risk of SARS-CoV-2 infection. For six hours, they exposed human lung airway epithelial cells to either IL-6 or chlorpyriphos or to both in combination. Another group of cells received no exposure to serve as a control. The researchers then treated the cells with the spike proteins that cover the outside of SARS-CoV-2. During infection, spike proteins bind with angiotensin converting enzyme 2 (ACE2) receptors to our cells, starting a process that allows the virus to release its genetic material into the healthy cell.

They found that cells exposed to IL-6 and the pesticide exhibited increased apoptosis or controlled cell death when the SARS-CoV-2 spike protein was present. The cells exposed to both the pesticide and IL-6 also had significantly more ACE2 expression on the apical cell surface compared to cells that were unexposed or exposed to the pesticide alone. The apical membrane of airway cells faces the interior of the airway while the basolateral membrane touches the surrounding tissues. Increased ACE2 receptor expression on the apical surface means more viruses will attach to the cells, the researchers explained. "Since people with obesity, Type-2 diabetes or cancer also have high circulatory IL-6 levels, we think people with these conditions will also have increased susceptibility to SARS-CoV-2 infection because of increased translocation of ACE2 receptor to the apical cell surface", Chatterjee said.