Determinants of a bronchoalveolar lavage of good quality for mineralogical analyses in adults: Experience from the Asbestos Fibers and Particles Laboratory of Paris City.

BACKGROUND: Mineralogical analyses of bronchoalveolar lavage (BAL) may help in assessing past exposure to mineral particles. However, their interpretation relies on their quality, meaning their representativeness of the alveolar compartment. The aim of this study was to find predictive factors of BAL samples quality allowing a reliable mineralogical analysis. METHODS: All BAL samples analyzed between 2018 and 2020 in the Asbestos Fibers and Particles Laboratory from Paris City were included. They were read by an experienced cyto-pathologist and validated according to their representativeness of the alveolar region compartment. Univariate and stratified analyses were conducted to identify factors associated with the samples' cytological quality. RESULTS: On the 780 samples included, 64.4% were deemed of good cytological quality and 17.9% were not interpretable. Injected volume and BAL yield (recovery volume on injected volume ratio) were associated with cytological quality. Injecting at least 100mL with a ≥60% yield or injecting at least 150mL with a ≥30% yield allowed having a good proportion of BAL with sufficient cytological quality. CONCLUSIONS: Injected volume greater than 100mL with sufficient BAL yield are essential factors to ensure a reliable mineralogical analysis of BAL samples.

Metallic oxide nanoparticle translocation across the human bronchial epithelial barrier.

Inhalation is the most frequent route of unintentional exposure to nanoparticles (NPs). Our aim was to quantify the translocation of different metallic NPs across human bronchial epithelial cells and to determine the factors influencing this translocation. Calu-3 cells forming a tight epithelial barrier when grown on a porous membrane in a two compartment chamber were exposed to fluorescently labelled NPs to quantify the NP translocation. NP translocation and uptake by cells were also studied by confocal and transmission electron microscopy. Translocation was characterized according to NP size (16, 50, or 100 nm), surface charge (negative or positive SiO2), composition (SiO2 or TiO2), presence of proteins or phospholipids and in an inflammatory context. Our results showed that NPs can translocate through the Calu-3 monolayer whatever their composition (SiO2 or TiO2), but this translocation was increased for the smallest and negatively charged NPs. Translocation was not associated with an alteration of the integrity of the epithelial monolayer, suggesting a transcytosis of the internalized NPs. By modifying the NP corona, the ability of NPs to cross the epithelial barrier differed depending on their intrinsic properties, making positively charged NPs more prone to translocate. NP translocation can be amplified by using agents known to open tight junctions and to allow paracellular passage. NP translocation was also modulated when mimicking an inflammatory context frequently found in the lungs, altering the epithelial integrity and inducing transient tight junction opening. This in vitro evaluation of NP translocation could be extended to other inhaled NPs to predict their biodistribution.