Sand Particles Increase Pneumococcal Adhesion to Primary Airway Cells in vitro

<bold>Background:</bold> Studies have suggested there can be increases in respiratory disease in Europe associated with sandstorms originating from the Sahara, sometimes known as Calima sandstorm events (1,2). We previously showed that Calima sandstorm particles (CSP) increase pneumococcal adhesion to A549 lung epithelial cells (3). <bold>Aim:</bold> Assess dose dependent effects of Calima sandstorm particles on pneumococcal adhesion to human primary bronchial epithelial cells (HPBEpC) in vitro. <bold>Methods:</bold> Airborne mineral dust originating in Saharan Africa and deposited on Tenerife during a sandstorm (February 2020) were collected. Samples were filtered (10 mm mesh), suspended in DPBS and added in various concentrations to adherent HPBEpC lung epithelial cells (2x105 cells/well) in cell culture plates for 2h. After washing, D39 S. pneumoniae strain was incubated with cells for 2h. Cells were washed and lysed before adherent bacteria were enumerated on blood agar plates for colony forming units (CFU) counts. Data was analysed by Kruskal-Wallis, with post-hoc analysis. <bold>Results:</bold> Incubation with Calima particles (1µg/ml - 20µg/ml) increased pneumococcal adhesion to HPBEpC cells in a dose dependent manner (figure, n=6, 10µg/ml *P<0.05, 20 µg/ml ***P<0.001). Conclusion Calima sand particles increase pneumococcal adherence to lower primary airway cells in vitro. References (1) Karanasiou A et al., Oct 15;47:107-14. doi: 10.1016/j.envint.2012.06.012. (2) López-Villarrubia E, et al., 2021 Jul;57(7):464-470. doi: 10.1016/j.arbr.2020.03.032. (3) Miyashita L, et al., ERS Congress, DOI: 10.1183/13993003.congress-2023