205 Evaluation of SARS-CoV-2 spike protein response on PI3K agonist-mediated IL-8 release

Borchers, C. E.; Thyagarajan, A.; Rapp, C.; Travers, J. B.; Sahu, R.

A novel coronavirus related to a condition known as a severe acute respiratory syndrome (SARS) was termed as SARS Coronavirus-19 (SARS-CoV-2 or COVID-19), which has caused an unprecedented global pandemic. While the mode of COVID-19 infection, its structural configuration, and multiple mechanisms of action including the critical roles of spike proteins have been substantially explored, elucidation of signaling pathways regulating its cellular responses is yet to be fully determined. Among major signaling cascades, phosphoinositide 3-kinases (PI3K) and its downstream pathways have been exploited as the potential therapeutic targets for COVID-19, and its activation induces the release of cytokines such as interleukin-8 (IL-8). To that end, the current studies were sought to determine SARS-CoV-2 spike S1 subunit protein (referred to as COVID-19) on PI3K agonist, phorbol myristate acetate (PMA)-mediated IL-8 release. Given that multiple cell types including epithelial lining of the nasal, bronchial and alveolar cells have been found to be primarily affected by COVID-19, we used nasopharyngeal carcinoma, KBP and non-small cell lung cancer, A549 cell lines for our studies. We observed that treatments with only PMA but not COVID-19 were able to induce dose-dependent IL-8 release from both KBP and A549 cell lines. Our next studies determined the effects of COVID-19 pretreatment with PMA and vice versa to evaluate if any of this combination would exert synergistic effect on IL-8 release. We observed no significant differences in IL-8 release with either of these combinations when compared with PMA-alone group. However, significantly increased IL-8 release was noticed by PMA + COVID-19 combination when compared with COVID-19-alone group. Overall, these studies indicate that PI3K signaling does not directly mediate COVID-19-induced IL-8 release in these cellular models.Copyright © 2021