Scientific Abstract
SARS-CoV-2, the causative agent of the COVID-19 pandemic, has had a global impact, affecting millions over the last three years. The severity of COVID-19-associated symptoms can range from asymptomatic to death. The prognosis of hospitalized COVID-19 patients heavily depends on the presence of comorbidities such as pre-existing lung diseases. Agricultural workers inhale respiratory irritants regularly, substantially increasing their risk for developing chronic lung diseases with long-term
exposures. This inherent risk associated with agricultural work puts the workers in danger of severe COVID-19. In previous studies, we characterized the protein kinase C (PKC)-dependent airway inflammation mediated by organic dust extract (ODE) derived from dust collected from swine confinement facilities in in vitro and in vivo models. Here, we studied the effect of ODE on SARS-CoV-2 pseudoviral infection in mice and BEAS-2B cells. In wild-type (WT) and humanized ACE2 mice, ODE increased ACE2 shedding by ADAM-17 in the lungs. After repeated ODE treatments, the increased
soluble ACE2 correlated to higher pseudovirus titer in the mouse lungs. In the human bronchial epithelial cell line, BEAS-2B, ODE augmented PKCα activity in WT cells, and functional PKCα was needed for membrane ACE2 expression, as seen in PKCα-deficient cells. Unlike in the mice, increasing membrane ACE2 levels by treating with PKCα or ADAM-17 inhibitors and a low dose of ODE enhanced pseudoviral entry in vitro. Following viral entry, IL-8 secretion by the cells was diminished in a PKCαand ADAM-17-independent manner. Together, the complex mechanisms involved in the synergistic
effects of agricultural dust and SARS-CoV-2 highlight the importance of studying dust-mediated changes to immunity against circulating pathogens.
