Abstract
Respiratory syncytial virus (RSV) is a leading cause of respiratory distress and hospitalization in the paediatric population. Low airway surface pH impairs antimicrobial host defence and worsens airway inflammation. Inhaled Optate safely raises airway surface pH in humans and raises intracellular pH in primary human airway epithelial cells (HAECs) in vitro. We aimed to determine if raising intracellular pH with Optate would decrease infection and replication of RSV in primary HAECs.
We cultured HAECs from healthy subjects in both air-liquid interface (ALI) and submerged conditions. We infected HAECs with green fluorescent protein-labelled RSV (GFP-RSV; MOI 1) and treated them with Optate or phosphate buffered saline control. We collected supernatant after a four-hour incubation and then every 24 h. We used fluorescence intensity, fluorescent particle counts, plaque assays, western blots, and enzyme-linked immunosorbent assays (ELISA) to quantitate infection.
In submerged culture, fluorescence intensity decreased in Optate-treated cells (48H p=0.0174, 72H p=<0.0001). Similarly, Optate treatment resulted in decreased fluorescent particle count (48H p=0.0178, 72H p=0.0019) and plaque forming units (PFUs) (48H p=0.0011, 72H p=0.0148) from cell culture supernatant. In differentiated HAECs cultured at ALI, Optate treatment decreased fluorescence intensity (p≤0.01), GFP via western blot and ELISA (p<0.0001), and RSV-fusion protein via ELISA (p=0.001). Additionally, RSV infection decreased as Optate concentration increased in a dose-dependent manner (p<0.001).
In conclusion, Optate inhibits RSV infection in primary HAECs in a dose-dependent manner. These findings suggest Optate may have potential as an inhaled therapeutic for patients with RSV.
Footnotes
This manuscript has recently been accepted for publication in the ERJ Open Research. It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJOR online. Please open or download the PDF to view this article.
Conflict of interest: Michael D. Davis reports support for the present manuscript received from NIH/NHLBI HL 158507, Indiana CTSI UL1 TR002529, and Riley Children's Foundation. Support for attending meetings and/or travel from Riley Hospital for Children Department of Pediatrics, outside the submitted work; Optate patent issues or pending, outside the submitted work; co-funder of Airbase Breathing Company, unrelated to the submitted work.
Conflict of interest: Benjamin Gaston reports support for the present manuscript from NIH. Grants or contracts received from NIH, outside the submitted work; support for attending meetings and/or travel from NIH, outside the submitted work; Patents planned, issued or pending: USPTO 7,888,385 - Provisional USPTO application for using inhaled buffer to treat viral respiratory diseases, disclosure made outside the submitted work. Stock or stock options: Airbase Breathing Company, 11,500 common units, disclosure made outside the submitted work.
Conflict of interest: Jessica Saunders reports support for the present manuscript from NIH NHLBI P01-Gaston, Morris Green Physician-Scientist Development Program, and Indiana Clinical and Translational Science Institute. Support for attending meetings and/or travel from Indiana University School of Medicine, outside the submitted work.
Conflict of interest: Laura Smith reports support for the present manuscript from NIH NHLBI P01-Gaston.
Conflict of interest: The remaining authors have nothing to disclose.
This is a PDF-only article. Please click on the PDF link above to read it.
- Received August 11, 2022.
- Accepted April 5, 2023.
- Copyright ©The authors 2023
This version is distributed under the terms of the Creative Commons Attribution Non-Commercial Licence 4.0. For commercial reproduction rights and permissions contact permissions{at}ersnet.org
