Dosing intact birch pollen grains at the air-liquid interface (ALI) to the immortalized human bronchial epithelial cell line BEAS-2B

Abstract

In real life, humans are exposed to whole pollen grains at the air epithelial barrier. We developed a system for in vitro dosing of whole pollen grains at the Air-Liquid Interface (ALI) and studied their effect on the immortalized human bronchial epithelial cell line BEAS-2B. Pollen are sticky and large particles. Dosing pollen needs resuspension of single particles rather than clusters, and subsequent transportation to the cells with little loss to the walls of the instrumentation i.e. in a straight line. To avoid high speed impacting insults to cells we chose sedimentation by gravity as a delivery step. Pollen was resuspended into single particles by pressured air. A pollen dispersion unit including PTFE coating of the walls and reduced air pressure limited impaction loss to the walls. The loss of pollen to the system was still about 40%. A linear dose effect curve resulted in 327-2834 pollen/cm2 (± 6.1%), the latter concentration being calculated as the amount deposited on epithelial cells on high pollen days. After whole pollen exposure, the largest differential gene expression at the transcriptomic level was late, about 7 hours after exposure. Inflammatory and response to stimulus related genes were up-regulated. We developed a whole pollen exposure air-liquid interface system (Pollen-ALI), in which cells can be gently and reliably dosed.

Biological impact of sequential exposures to allergens and ultrafine particle‐rich combustion aerosol on human bronchial epithelial BEAS‐2B cells at the air liquid interface

“…Intact birch pollen grains were freshly collected in Munich in 2018, as described in (Candeias et al, 2021). Aqueous pollen extract ( Betula pendula ) was prepared as previously described (Gilles et al, 2009).…”

TUBE Project: Transport-Derived Ultrafines and the Brain Effects

“…ALI methods can overcome the major weaknesses of submerged cell culture methods, e.g., selective exposure to insoluble and soluble components, coagulation of particles, and loss of semivolatile or volatile components and gases. They have proven to be highly usable for studying very different forms and sources of aerosols (e.g., [ 48 , 49 , 50 ]). The designs of different ALI systems are highly different and usually meant to meet specific study questions.…”