Astodrimer sodium nasal spray forms a barrier to SARS-CoV-2 in vitro and preserves normal mucociliary function in human nasal epithelium

Abstract

COVID-19 remains a severe condition for many including immunocompromised individuals. There remains a need for effective measures against this and other respiratory infections, which transmit via virus-laden droplets that reach the nasal or oral mucosae. Nasal sprays offer potential protection against viruses. Such formulations should preserve normal nasal mucociliary function. The antiviral barrier efficacy and effects on mucociliary function of astodrimer sodium nasal spray (AS-NS) were evaluated and compared with other available nasal sprays-low pH hydroxypropyl methylcellulose (HPMC-NS), iota-carrageenan (Carr-NS), nitric oxide (NO-NS), and povidone iodine (PI-NS). Assays simulated clinical conditions. Antiviral barrier function and cell viability were assessed in airway cell monolayers, while a model of fully differentiated human nasal epithelium (MucilAir™) was utilized to evaluate tissue integrity, cytotoxicity, cilia beating frequency, and mucociliary clearance. AS-NS reduced infectious virus in cell monolayers and demonstrated a benign cytotoxicity profile. In human nasal epithelium ex vivo, AS-NS had no impact on mucociliary function (cilia beating nor mucociliary clearance). Carr-NS, HPMC-NS, NO-NS and PI-NS demonstrated limited antiviral effects, while HPMC-NS caused inhibition of mucociliary function. Astodrimer sodium nasal spray demonstrates an acceptable nonclinical efficacy and safety profile as a barrier nasal spray against respiratory viral infection in the nasal cavity.

Fig. 1

Concentration of infectious SARS-CoV-2 virus, expressed as log₁₀ PFU/mL, in supernatants from Calu-3 cell cultures following a 4 h incubation with 400 µL of PBS (negative control), AS-NS, NO-NS, Carr-NS, or HPMC-NS.

Fig. 2

Effects of nasal sprays on cell viability, as determined by ATP-related luminescence, following 24 h exposure of Vero E6 cell monolayers to serial dilutions of AS-NS, Carr-NS, NO-NS, HPMC-NS, and PI-NS (a); or to each nasal spray diluted to 10% (b). Values are expressed as a percentage of the luminescence observed in untreated controls, corresponding to 100% cell viability.

Fig. 3

Microphotographs (× 40 magnification) of Vero E6 cell monolayers: untreated (a), or after a 24 h exposure to 10% AS-NS (b), 10% Carr-NS (c), 10% NO-NS (d), 10% HPMC-NS (e), and 10% PI-NS (f). Untreated cells (control), and cells treated with AS-NS or Carr-NS display an intact cell monolayer and appear healthy with no apoptotic or necrotic bodies, while cells treated with NO-NS, HPMC-NS and PI-NS exhibit a rounded shape, reduced cell count, and a disrupted cell monolayer.

Fig. 4

Trans-epithelial electrical resistance (TEER) (indicative of tissue integrity) measured at the end of treatment (EoT) and end of recovery (EoR) in inserts exposed to test items for either 4 or 24 h. Triton X-100 is a positive control, known to induce cytotoxicity mediated epithelial disruption. The dashed line at [a] indicates the critical threshold (100 Ω cm²), below which the inserts are considered to display compromised epithelium.

Fig. 5

CBF at EoT and EoR in inserts exposed to test items for either 4 or 24 h. Isoproterenol serves as a positive control, inducing enhanced ciliary beating. The dashed lines at [a] (4 Hz) and [b] (8 Hz) indicate the standard range of CBF for the MucilAir™ system. Note [c]: Bars representing CBF for HPMC-NS at either 5 or 10 µL are not plotted due to the total loss of ciliary beating after exposure to this test item, reflecting a CBF value of 0 Hz. This difference was statistically significant (p < 0.0001) when compared with untreated controls/saline. *p < 0.05 relative to untreated inserts at the corresponding timepoint (EoT or EoR). §p < 0.05 relative to the same treatment at EoT.

Fig. 6

MCC at EoT and EoR in inserts exposed to test items for either 4 or 24 h. Isoproterenol is a positive control, known to enhance MCC through its stimulatory effect on ciliary beating. *p < 0.05 relative to untreated inserts at the corresponding timepoint (EoT or EoR). §p < 0.05 relative to the same treatment at EoT.