Abstract:
Keratinocytes (KC) are the main cellular components of the stratum corneum that constitutes a solid physical
skin barrier representing the first line of defense against pathogens. Moreover, KC are potent producers of
inflammatory mediators and antimicrobial peptides (AMP) when activated through their pattern recognition
receptors. In atopic dermatitis (AD) the protective skin barrier may be compromised due to barrier disruption,
secondary infection and accelerated secretion of inflammatory cytokines which may also affect AMP expression
in the skin. In the present study, we addressed the responses of a canine KC cell line upon exposure to
Staphylococcus pseudintermedius, typically found on canine atopic skin during secondary infections, and stimulation
by individual AD-associated ligands and cytokines. All stimuli induced a significant increase in expression
of the pro-inflammatory cytokine genes tumor necrosis factor (TNF)-α and interleukin (IL)-8, but with different
kinetics. Limited effects were observed on AMP gene expression except for K9CATH which was significantly
upregulated upon bacterial infection but with none of the individual AD-associated ligands. Interestingly,
K9CATH possessed antimicrobial activity towards Staphylococcus pseudintermedius, indicating that K9CATH expression
is a specific defense reaction towards bacterial infection and not part of a general pro-inflammatory
profile of KC.
