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The inflammatory response of primary bovine mammary epithelial cells to Staphylococcus aureus strains is linked to the bacterial phenotype.

ABSTRACT: Staphylococcus aureus is a major mastitis-causing pathogen in dairy cows. The latex agglutination-based Staphaurex test allows bovine S. aureus strains to be grouped into Staphaurex latex agglutination test (SLAT)-negative [SLAT(-)] and SLAT-positive [SLAT(+)] isolates. Virulence and resistance gene profiles within SLAT(-) isolates are highly similar, but differ largely from those of SLAT(+) isolates. Notably, specific genetic changes in important virulence factors were detected in SLAT(-) isolates. Based on the molecular data, it is assumed that SLAT(+) strains are more virulent than SLAT(-) strains. The objective of this study was to investigate if SLAT(-) and SLAT(+) strains can differentially induce an immune response with regard to their adhesive capacity to epithelial cells in the mammary gland and in turn, could play a role in the course of mastitis. Primary bovine mammary epithelial cells (bMEC) were challenged with suspensions of heat inactivated SLAT(+) (n?=?3) and SLAT(-) (n?=?3) strains isolated from clinical bovine mastitis cases. After 1, 6, and 24 h, cells were harvested and mRNA expression of inflammatory mediators (TNF-?, IL-1?, IL-8, RANTES, SAA, lactoferrin, GM-CSF, COX-2, and TLR-2) was evaluated by reverse transcription and quantitative PCR. Transcription (??CT) of most measured factors was induced in challenged bMEC for 6 and 24 h. Interestingly, relative mRNA levels were higher (P<0.05) in response to SLAT(+) compared to SLAT(-) strains. In addition, adhesion assays on bMEC also showed significant differences between SLAT(+) and SLAT(-) strains. The present study clearly shows that these two S. aureus strain types cause a differential immune response of bMEC and exhibit differences in their adhesion capacity in vitro. This could reflect differences in the severity of mastitis that the different strain types may induce.

SUBMITTER: Zbinden C

PROVIDER: S-EPMC3907564 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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The inflammatory response of primary bovine mammary epithelial cells to Staphylococcus aureus strains is linked to the bacterial phenotype.

Zbinden Christina C Stephan Roger R Johler Sophia S Borel Nicole N Bünter Julia J Bruckmaier Rupert M RM Wellnitz Olga O

PloS one 20140130 1

Staphylococcus aureus is a major mastitis-causing pathogen in dairy cows. The latex agglutination-based Staphaurex test allows bovine S. aureus strains to be grouped into Staphaurex latex agglutination test (SLAT)-negative [SLAT(-)] and SLAT-positive [SLAT(+)] isolates. Virulence and resistance gene profiles within SLAT(-) isolates are highly similar, but differ largely from those of SLAT(+) isolates. Notably, specific genetic changes in important virulence factors were detected in SLAT(-) isola ...[more]

PMID: 24498088

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Project description:Bovine mastitis, an inflammatory reaction of the mammary gland, is commonly caused by Staphylococcus aureus or Escherichia coli infections in high-yielding dairy cows. Immunotranscriptomic responses of bovine mammary epithelial cell (bMEC) are pivotal for the understanding of the defense against invading pathogens, and for the fate of udder inflammation. The intracellular chemotaxic protein Cyclophilin A (CyPA), secreted by bMEC during inflammatory reaction is being considered as a marker for the early diagnosis of mastitis. Taken together, the present study aimed to investigate the microarray-based transcriptome alterations in bMEC after in vitro infection with two S. aureus strains (S. aureus JE2 and S. aureus SA003) or E. coli crude lipopolysaccharide (LPS). In addition, the CyPA-induced expression changes of selected cytokine and chemokines were evaluated by qRT-PCR. Differential expression analysis identified 447, 465 and 520 differentially expressed genes (DEGs) in bMEC after LPS, S. aureus JE2 and S. aureus SA003 stimulation, respectively. LPS-induced DEGs are involved in the activation of cytokine-cytokine receptors interaction, NOD-like receptor signaling, chemokine signaling, interleukin-1 signaling and Toll-like receptor signaling pathway; while S. aureus induced DEGs were involved in the enrichment of neuroactive ligand-receptor interaction, GPCR signaling, cytokine-cytokine receptor interaction, and JAK-STAT pathway. A major differential inflammatory response to LPS and S. aureus treatments was the activation of the chemokine signaling pathway by LPS but not either by S. aureus JE2 or SA003. Unlike the S. aureus strains, LPS stimulation resulted significant upregulation of CCL2, CXCL2, CXCL3, CXCL5, CXCL8, CXCL9, IL1A and IL1B that are known to target mononuclear leukocytes, and could induce systemic inflammation. CyPA stimulation was able to upregulate chemokines (CXCL2, CXCL3, CXCL8, IL1A and IL1B) expression in bMEC indicating its ability to promote inflammation. Several of the LPS-induced DEGs were found to have transcription factor binding sites, and their expressions were also predicted to be regulated by sets of microRNAs. The transcriptional alterations associated with inflammatory response in this study may reflect immunomodulatory mechanisms underlying the interaction of bMEC with E. coli and S. aureus during mastitis.

Project description:Probiotics have been considered as a promising strategy to prevent various diseases in both humans and animals. This approach has gained interest in recent years as a potential means to control bovine mastitis. In a previous study, we found that several L. casei strains, including BL23, were able to inhibit the internalization of S. aureus, a major etiologic agent of mastitis, into bovine mammary epithelial cells (bMEC). This antagonism required a direct contact between L. casei and bMEC or S. aureus, suggesting the inhibition relied on interactions between L. casei cell surface components and bMEC. In this study, we have investigated the impact of some candidates which likely influence bacteria host cell interactions. We have shown that L. casei BL23 fbpA retained its inhibitory potential, indicating that L. casei BL23 antagonism did not rely (solely) on competition between S. aureus and L. casei fibronectin-binding proteins for adhesion to bMEC. We have then investigated the impact of four sortase mutants, srtA1, srtA2, srtC1 and srtC2, and a double mutant (srtA1-srtA2) on L. casei BL23 inhibitory potential. Sortases are responsible for the anchoring on the bacterial cell wall of LPXTG-proteins, which reportedly play an important role in bacteria-host cell interaction. All the srt mutants tested presented a reduced inhibition capacity, the most pronounced effect being observed with the srtA2 mutant. A lower internalization capacity of L. casei srtA2 into bMEC was also observed. This was associated with several changes at the surface of L. casei BL23 srtA2 compared to the wild type (wt) strain, including altered abundance of some LPXTG- and moonlighting proteins, and modifications of cell wall structure. These results strongly support the role of sortase A2 in L. casei BL23 inhibition against S. aureus internalization. Deciphering the contribution of the cell surface components altered in srtA2 strain in the inhibition will require further investigation.

Dataset Information

The inflammatory response of primary bovine mammary epithelial cells to Staphylococcus aureus strains is linked to the bacterial phenotype.

Publications

The inflammatory response of primary bovine mammary epithelial cells to Staphylococcus aureus strains is linked to the bacterial phenotype.

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