A Treatment to Eliminate Respiratory Viral Infections Associated with Asthma Exacerbations

Abstract ID 93723 Poster Board 349 Background: Low airway pH is implicated in many airways diseases. Furthermore, low airway surface pH impairs antimicrobial host defense and worsens airway inflammation. Many respiratory viruses require low endosomal pH to enter airway epithelial cells, activate viral surface proteins, and to replicate. Respiratory syncytial virus (RSV) and human metapneumovirus (hMPV), both members of the Paramyxovirdae family, are leading causes of acute asthma exacerbations. Inhaled Optate, an alkaline buffer, safely raises airway surface pH in humans and raises intracellular and endosomal pH in primary human airway epithelial cells (HAECs). We have recently demonstrated that Optate inhibits SARS-CoV-2 infection in primary HAECs. Here, we hypothesized that Optate treatment would decrease viral infection and replication in RSV and hMPV in primary HAECs. Methods: We grew primary HAECs from healthy subjects, infected them with RSV or hMPV tagged with green fluorescent protein (RSV-GFP1 or MPV-GFP1, ViraTree), and used 120 mM Optate (concentrations used in humans in vivo) to determine whether Optate would prevent viral infection and replication. GFP-RSV or GFP-MPV (multiplicity of infection = 1) and Optate or PBS control were co-administered to HAECs. Supernatant from the infected cells was collected after a 4-hour incubation period and then every 24 hours for 3 days. Viral infection and replication were determined with fluorescence quantification, immunoblot assays, enzyme-linked immunosorbent assay (ELISA), and fluorescent particle counts via plaque assays. Results: RSV and hMPV infection was significantly lower in cells treated with Optate compared to control, demonstrated by a significant decrease in fluorescence intensity (Figure). Additionally, RSV plaque-forming units significantly decreased in Optate-treated cells (p=0.0011). Finally, GFP protein levels significantly decreased when measured by western blot analysis and ELISA after Optate treatment (p=.0014 and p=.0023, respectively). Conclusion: Optate inhibits RSV and hMPV infection in primary HAECs, similar to its inhibition of SARS-CoV-2. Our findings suggest that Optate may have potential as an inhaled therapeutic for patients with RSV or hMPV. Furthermore, these findings suggest that Optate may be suitable for a proof-of-concept clinical trial to evaluate airway pH modulation as a treatment for RSV or hMPV infections and their related asthma exacerbations. NHLBI: P01 HL158507 NASA- Indiana Space Grant Consortium Doctoral Fellow (2023-2024)