Characterization of virulence mechanisms of Bordetella Pertussis using 2D and 3D in vitro airway test systems

The agent of whooping cough, B. pertussis, upon inhalation
binds to the ciliated epithelial cells of the airway tract and produces
several virulence factors to initiate pathogenicity. One of
the most important virulence factors is adenylate cyclase toxin
(CyaA). Previous studies have assessed the impact of CyaA on
cell lines, however, the effects of CyaA on primary human airway
epithelial cells (hAEC) are still unknown. In our investigation,
we characterized the response of primary hAEC extracted
from two different anatomic sites (nose and tracheo-bronchial
region) upon intoxication with CyaA and its toxoid CyaA-AC-.
To this end, cells were cultured either on monolayers or on
3D AEC-based tissue models with high in vitro/in vivo correlation,
and comparative analyses were performed. In addition,
we added to our investigation immortalized human bronchial
epithelial cells (HBEC3-KT) to directly evaluate the differences
in the response of primary human cells and a cell line, which
has not been used before for such investigations. Furthermore,
in the need of having in vitro test systems that +mimic with
more precision the in vivo immune response of the human
respiratory tract, we improved the primary airway tissue model
by introducing monocyte-derived dendritic cells (MDDCs) into
the system to evaluate its potential to allow MDDCs migration
upon CyaA and CyaA-AC- intoxication. We were able to show
that, compared to HBEC3-KT, primary hAEC were more sensitive
to CyaA action. Moreover, in hAEC CyaA did affect cell
viability, intracellular cAMP levels, dendritic cell migration,
and compromises the innate immune functions, however,
these effects were cell-type specific different Our findings reveal
first insights into toxin-cell interaction using primary hAEC
of different origins and confirm that the choice of respiratory
epithelial cell type can significantly influence the outcome of
research studies.

Author(s): Maria Bianchi

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