Ursodeoxycholic Acid Attenuates B Cell Susceptibility to SARS-CoV-2 Spike Protein by Interfering Its Binding to ACE2.

B cells are essential for the defense against various infectious agents including severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) causing coronavirus disease 2019 (COVID-19). COVID-19 is caused by interaction of the spike protein (SP) with the receptor-binding domain (RBD) and its receptor, angiotensin converting enzyme 2 (ACE2). Bisphenol A (BPA), a plasticizer and endocrine-disrupting chemical, can enter the human body through several exposure routes. Previously, we reported human B cell death by BPA treatment via autophagy induction. Here, we investigated whether the exposure to BPA affects B cell susceptibility to SP of COVID-19 and how to interfere the interaction of SP and ACE2. We observed an increase in ACE2 gene expression in human B cells by BPA treatment and more SP binding in BPA-treated B cells. Our data also showed more B cell death accompanying increased autophagic puncta count and lysosomal intracellular activity by co-treatment with BPA and SP compared to those in BPA treatment alone. Ursodeoxycholic acid (UDCA) reduced SP binding in B cells in BPA-exposed B cells. UDCA treatment also inhibited B cell death and lysosomal enzyme activity which were enhanced by co-treatment of BPA and SP. Taken together, results demonstrate that BPA-exposed B cells are more susceptible to COVID-19. It also suggests that UDCA could be protective to SP-responding B cells exposed to BPA.