Use of Human Lung Tissue Models for Screening of Drugs against SARS-CoV-2 Infection

Abstract

The repurposing of licenced drugs for use against COVID-19 is one of the most rapid ways to develop new and alternative therapeutic options to manage the ongoing pandemic. Given circa 7817 licenced compounds available from Compounds Australia that can be screened, this paper demonstrates the utility of commercially available ex vivo/3D airway and alveolar tissue models. These models are a closer representation of in vivo studies than in vitro models, but retain the benefits of rapid in vitro screening for drug efficacy. We demonstrate that several existing drugs appear to show anti-SARS-CoV-2 activity against both SARS-CoV-2 Delta and Omicron Variants of Concern in the airway model. In particular, fluvoxamine, as well as aprepitant, everolimus, and sirolimus, has virus reduction efficacy comparable to the current standard of care (remdesivir, molnupiravir, nirmatrelvir). Whilst these results are encouraging, further testing and efficacy studies are required before clinical use can be considered.

Keywords: 3D tissue models; COVID-19; CoviRx.org; drug repurposing; therapeutics.

Figure 1

Structure of MatTek EpiAirway and EpiAlveolar 3D Tissue Models. (A) EpiAirway tissue model is composed of mucocilliary epithelial cells derived from normal human tracheal/bronchial epithelial cells (NHBE) differentiated at the air-liquid interface. (B) EpiAlveolar tissue model is composed of alveolar cells, fibroblasts and pulmonary endothelial cells derived from normal human alveolar epithelial cells (NHAE), normal human pulmonary fibroblasts (NHPF), and normal human pulmonary endothelial cells (NHPE) differentiated at the air-liquid interface. Colours are associated with cell types as labelled.

Figure 2

Growth of SARS-CoV-2 Delta in MatTek EpiAirway and EpiAlveolar 3D Tissue Models. (A) Growth in the EpiAirway tissue model peaked on Day 3 post-infection with relative reproducibility. An amount of 5 mM remdesivir was effective at preventing detectable infection in all but one of the replicates on Day 3. (B) Growth in the EpiAlveolar tissue model also peaked on Day 3 post-infection, but with more variability between the replicates than EpiAirway. A total of 5 µM remdesivir was effective at preventing detectable infection in all the samples. Dots represent titres from biological quadruplicate samples coloured by tissue type. For horizontal lines, the large dark lines represent the mean titre of the replicates, while the smaller, lighter lines represent the standard error of the mean (SEM).

Figure 3

Primary Screening of Selected Drugs on the Growth of SARS-CoV-2 Delta in MatTek EpiAirway Tissue Model. Titres in the EpiAirway tissue model in the presence of 25, 10, 2, 0.4, 0.08, or 0.016 µM control (Remdesivir and Molnupiravir) or test (Fluvoxamine, L-Cycloserine, Probenecid, Pyrimethamine, Ondansetron, Cyclizine, Everolimus, Lapatinib, Cetrizine, and Rolapitant) drugs were determined by titrating the apical wash samples collected after 48 hr (black dots). The Red dashed line represents the average titre (±SD) from the biological triplicate Delta virus-only control samples.

Figure 4

Toxicity of Drugs at 10 μM Concentration. Apical wash samples were collected and analysed in triplicate for LDH release from cells. Absorbance was compared to positive toxicity control (100 μM rotenone) and plotted as percentage of positive toxicity control for DMSO (green) and test drugs (blue).

Figure 5

Secondary Screening of Selected Drugs on the Growth of SARS-CoV-2 Delta and Omicron in MatTek EpiAirway Tissue Model. Titres of SARS-CoV-2 Delta (A) and Omicron (B) in the EpiAirway tissue model in the presence of 10, 2, 0.4, or 0.08 µM remdesivir and nirmatrelvir or 25, 10, 4, 1, or 0.4 µM molnupiravir, fluvoxamine, everolimus, pyrimethamine, aprepitant, or sirolimus were determined by titrating the apical wash samples collected after 48 hr (black dots). The Red dashed line represents the average titre (±SD) from the biological triplicate Delta virus-only control samples, while the Blue dashed line represents the average titre (±SD) from the biological triplicate Omicron virus-only control samples.