AUTHOR=Fernández-Bravo Ana , Figueras Maria José 

TITLE=Immune Response of the Monocytic Cell Line THP-1 Against Six Aeromonas spp.

JOURNAL=Frontiers in Immunology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2022.875689

DOI=10.3389/fimmu.2022.875689

ISSN=1664-3224

ABSTRACT=<p><italic>Aeromonas</italic> are autochthonous bacteria of aquatic environments that are considered to be emerging pathogens to humans, producing diarrhea, bacteremia, and wound infections. Genetic identification shows that 95.4% of the strains associated with clinical cases correspond to the species <italic>Aeromonas caviae</italic> (37.26%), <italic>Aeromonas dhakensis</italic> (23.49%), <italic>Aeromonas veronii</italic> (21.54%), and <italic>Aeromonas hydrophila</italic> (13.07%). However, few studies have investigated the human immune response against some <italic>Aeromonas</italic> spp. such as <italic>A. hydrophila</italic>, <italic>Aeromonas salmonicida</italic>, and <italic>A. veronii</italic>. The present study aimed to increase the knowledge about the innate human immune response against six <italic>Aeromonas</italic> species, using, for the first time, an <italic>in vitro</italic> infection model with the monocytic human cell line THP-1, and to evaluate the intracellular survival, the cell damage, and the expression of 11 immune-related genes (<italic>TLR4</italic>, <italic>TNF-α</italic>, <italic>CCL2</italic>, <italic>CCL20</italic>, <italic>JUN</italic>, <italic>RELA</italic>, <italic>BAX</italic>, <italic>TP53</italic>, <italic>CASP3</italic>, <italic>NLRP3</italic>, and <italic>IL-1β</italic>). Transcriptional analysis showed an upregulated expression of a variety of the monocytic immune-related genes, with a variable response depending upon the <italic>Aeromonas</italic> species. The species that produced the highest cell damage, independently of the strain origin, coincidentally induced a higher expression of immune-related genes and corresponded to the more prevalent clinical species <italic>A. dhakensis</italic>, <italic>A. veronii</italic>, and <italic>A. caviae</italic>. Additionally, monocytic cells showed an overexpression of the apoptotic and pyroptotic genes involved in cell death after <italic>A. dhakensis</italic>, <italic>A. caviae</italic>, and <italic>Aeromonas media</italic> infection. However, the apoptosis route seemed to be the only way of producing cell damage and death in the case of the species <italic>Aeromonas piscicola</italic> and <italic>Aeromonas jandaei</italic>, while <italic>A. veronii</italic> apparently only used the pyroptosis route.</p>