Curbside particulate matter and susceptibility to SARS-CoV-2 infection

Lisa Miyashita; Gary Foley; Sean Semple; Joseph M Gibbons; Corinna Pade; Áine McKnight; Jonathan Grigg

doi:10.1016/j.jacig.2023.100141

Curbside particulate matter and susceptibility to SARS-CoV-2 infection

J Allergy Clin Immunol Glob. 2023 Jul 8;2(4):100141. doi: 10.1016/j.jacig.2023.100141. eCollection 2023 Nov.

Authors

Lisa Miyashita¹, Gary Foley¹, Sean Semple², Joseph M Gibbons¹, Corinna Pade¹, Áine McKnight¹, Jonathan Grigg¹

Affiliations

¹ Blizard Institute, Queen Mary University of London, London, United Kingdom.
² Institute for Social Marketing, University of Stirling, Stirling, United Kingdom.

Abstract

Background: Biologic plausibility for the association between exposure to particulate matter (PM) less than 10 μm in aerodynamic diameter (PM₁₀) and coronavirus disease 2019 (COVID-19) morbidity in epidemiologic studies has not been determined. The upregulation of angiotensin-converting enzyme 2 (ACE2), the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) entry receptor on host cells, by PM₁₀ is a putative mechanism.

Objective: We sought to assess the effect of PM₁₀ on SARS-CoV-2 infection of cells in vitro.

Methods: PM₁₀ from the curbside of London's Marylebone Road and from exhaust emissions was collected by cyclone. A549 cells, human primary nasal epithelial cells (HPNEpCs), SARS-CoV-2-susceptible Vero-E6 and Calu3 cells were cultured with PM₁₀. ACE2 expression (as determined by median fluorescent intensity) was assessed by flow cytometry, and ACE2 mRNA transcript level was assessed by PCR. The role of oxidative stress was determined by N-acetyl cysteine. The cytopathic effect of SARS-CoV-2 (percentage of infection enhancement) and expression of SARS-CoV-2 genes' open reading frame (ORF) 1ab, S protein, and N protein (focus-forming units/mL) were assessed in Vero-E6 cells. Data were analyzed by either the Mann-Whitney U test or Kruskal-Wallis test with the Dunn multiple comparisons test.

Results: Curbside PM₁₀ at concentrations of 10 μg/mL or more increased ACE2 expression in A549 cells (P = .0021). Both diesel PM₁₀ and curbside PM₁₀ in a concentration of 10 μg/mL increased ACE2 expression in HPNEpCs (P = .0022 and P = .0072, respectively). ACE2 expression simulated by curbside PM₁₀ was attenuated by N-acetyl cysteine in HPNEpCs (P = .0464). Curbside PM₁₀ increased ACE2 expression in Calu3 cells (P = .0256). In Vero-E6 cells, curbside PM₁₀ increased ACE2 expression (P = .0079), ACE2 transcript level (P = .0079), SARS-CoV-2 cytopathic effect (P = .0002), and expression of the SARS-CoV-2 genes' ORF1ab, S protein, and N protein (P = .0079).

Conclusions: Curbside PM₁₀ increases susceptibility to SARS-COV-2 infection in vitro.

Keywords: PM10; Particulate matter; SARS-CoV-2; airway epithelial cells.