Abstract:
Bovine mastitis is the inflammatory reaction of the mammary gland and is commonly
caused by bacterial infections in high-yielding dairy cows. The detailed investigation of the
immunotranscriptomic response of bovine mammary epithelial (BME) cells to pattern recognition
receptors (PRRs) activation by microbial-associated molecular patterns (MAMPs) can be of great
importance for understanding the innate immune defense mechanisms, and for exploring the
immunomodulatory candidate genes. In this work, we investigated the transcriptome modifications
of BME cells after the in vitro stimulation with Escherichia coli derived lipopolysaccharide (LPS) and
heat-killed Staphylococcus aureus JE2 and S. aureus SA003. In addition, the effect of Pam3CSK4 (a
synthetic triacylated lipopeptide that activates Toll-like receptor 2 (TLR2)), and the intracellular
chemotactic protein cyclophilin A (CyPA), which is secreted by BME cells during mastitis, in the
expression changes of selected cytokines and chemokines were evaluated by qPCR. Microarray
analysis identified 447, 465 and 520 differentially expressed genes (DEGs) in the BME cells after LPS, S. aureus JE2 and S. aureus SA003 stimulation, respectively. A major differential response in
the inflammatory gene expression was noticed between the stimulation of LPS and S. aureus strains.
Unlike the S. aureus strains, LPS stimulation resulted in significant upregulation of CCL2, CXCL2,
CXCL3, CXCL8, IL1 and IL1 , which were confirmed by qPCR analysis. Pam3CSK4 was not able
to induce significant changes in the expression of cytokines and chemokines in challenged BME
cells. The exogenous CyPA administration was able to upregulate CXCL2, CXCL3, CXCL8, IL1
and IL1 expression in BME cells indicating its ability to promote inflammation. The identification
of transcriptional markers of mastitis specific for individual inflammatory factors such as LPS,
Pam3CSK4 or CyPA, which can be evaluated in vitro in BME cells, may enable the development
of novel diagnostics and/or immunomodulatory treatments, providing new tools for the effective
management of mastitis in dairy cows. The results of this work are an advance in this regard.
