Differential response of bovine mammary epithelial cells to Staphylococcus aureus or Escherichia coli agonists of the innate immune system

Abstract

Mastitis caused by Escherichia coli and Staphylococcus aureus is a major pathology of dairy cows. To better understand the differential response of the mammary gland to these two pathogens, we stimulated bovine mammary epithelial cells (bMEC) with either E. coli crude lipopolysaccharide (LPS) or with S. aureus culture supernatant (SaS) to compare the transcriptomic profiles of the initial bMEC response. By using HEK 293 reporter cells for pattern recognition receptors, the LPS preparation was found to stimulate TLR2 and TLR4 but not TLR5, Nod1 or Nod2, whereas SaS stimulated TLR2. Biochemical analysis revealed that lipoteichoic acid, protein A and α-hemolysin were all present in SaS, and bMEC were found to be responsive to each of these molecules. Transcriptome profiling revealed a core innate immune response partly shared by LPS and SaS. However, LPS induced expression of a significant higher number of genes and the fold changes were of greater magnitude than those induced by SaS. Microarray data analysis suggests that the activation pathways and the early chemokine and cytokine production preceded the defense and stress responses. A major differential response was the activation of the type I IFN pathway by LPS but not by SaS. The higher upregulation of chemokines (Cxcl10, Ccl2, Ccl5 and Ccl20) that target mononuclear leucocytes by LPS than by SaS is likely to be related to the differential activation of the type I IFN pathway, and could induce a different profile of the initial recruitment of leucocytes. The MEC responses to the two stimuli were different, as LPS was associated with NF-κB and Fas signaling pathways, whereas SaS was associated with AP-1 and IL-17A signaling pathways. It is noteworthy that at the protein level secretion of TNF-α and IL-1β was not induced by either stimulus. These results suggest that the response of MEC to diffusible stimuli from E. coli and S. aureus contributes to the onset of the response with differential leucocyte recruitment and distinct inflammatory and innate immune reactions of the mammary gland to infection.

Staphylococcus aureus Phenol-Soluble Modulins Impair Interleukin Expression in Bovine Mammary Epithelial Cells

“…They produce various antimicrobial substances and inflammatory mediators that enhance effector functions of innate immunity and stimulate adaptive immunity, playing a pivotal role in the resolution of infection (27). A great number of studies dedicated to the analysis of the defensive response of MEC used killed bacteria or bacterial supernatants; however, those models have a significant limitation, since there is a great difference in the immune responses initiated by live bacteria, killed bacteria, bacterial supernatants, and purified bacterial components (26,31,32). Using live E. coli and S. aureus bacteria, we set up in vitro infection models that assessed the effects of these Gram-negative and Gram-positive bacteria on expression of IL-32, IL-6, and IL-8.…”

Intramammary infusion of Panax ginseng extract in bovine mammary gland at cessation of milking induces changes in the expression of toll-like receptors, MyD88 and NF-kB during early involution

“…Among these receptors, expression of TLR2 and 4 substantially increased in quarters suffering from subclinical, moderate or severe infections, which correlated with severity of infection (Goldammer et al, 2004). TLR2 and TLR4 gene expression by mammary epithelial cells, monocytes-macrophages and neutrophyls has been reported (Gilbert et al, 2013;Strandberg et al, 2005;Wright et al, 1990); however, expression at the protein level remains to be documented. We performed IHC studies with antibodies to TLR2 and TLR4 to gain information on the localization of these receptors in bovine mammary tissue.…”

Cyanidin-3-O-β-glucoside inhibits lipopolysaccharide-induced inflammatory response in mouse mastitis model

“…The results showed that C3G could decrease the levels of cholesterol in lipid rafts. Meanwhile, our cholesterol replenishment Mammary epithelial cells directly contact with the invading pathogens and play an important role in upper immunity ( 25 ). They recognize the pathogen-associated molecular patterns of invading pathogens via pattern recognition receptors such as TLRs, and induce the production of cytokines.…”