Gene expression profiling of porcine mammary epithelial cells after challenge with Escherichia coli and Staphylococcus aureus in vitro.

Postpartum Dysgalactia Syndrome (PDS) represents a considerable health problem of postpartum sows, primarily indicated by mastitis and lactation failure. The poorly understood etiology of this multifactorial disease necessitates the use of the porcine mammary epithelial cell (PMEC) model to identify how and to what extent molecular pathogen defense mechanisms prevent bacterial infections at the first cellular barrier of the gland. PMEC were isolated from three lactating sows and challenged with heat-inactivated potential mastitis-causing pathogens Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) for 3 h and 24 h, in vitro. We focused on differential gene expression patterns of PMEC after pathogen challenge in comparison with the untreated control by performing microarray analysis. Our results show that a core innate immune response of PMEC is partly shared by E. coli and S. aureus. But E. coli infection induces much faster and stronger inflammatory response than S. aureus infection. An immediate and strong up-regulation of genes encoding cytokines (IL1A and IL8), chemokines (CCL2, CXCL1, CXCL2, CXCL3, and CXCL6) and cell adhesion molecules (VCAM1, ICAM1, and ITGB3) was explicitly obvious post-challenge with E. coli inducing a rapid recruitment and activation of cells of host defense mediated by IL1B and TNF signaling. In contrast, S. aureus infection rather induces the expression of genes encoding monooxygenases (CYP1A1, CYP3A4, and CYP1B1) initiating processes of detoxification and pathogen elimination. The results indicate that the course of PDS depends on the host recognition of different structural and pathogenic profiles first, which critically determines the extent and effectiveness of cellular immune defense after infection.

The role of bacterial pathogens in coliform mastitis in sows.

Even in modern piglet production, mastitis and lactation failure in sows represent a considerable health problem post partum, affecting in its consequences both the sow and her piglets. Known as a multifactorial syndrome, Mastitis-Metritis-Agalactia (MMA) has been topic of several studies investigating possible influencing factors at farm and sow level in the recent past. However, there is a lack of current investigations on the causative pathogens, especially with advanced laboratory methods and with an adequate control group of healthy animals. Therefore, 1026 milk samples from coliform mastitis (CM)-affected, and 972 samples from healthy sows on six farms were examined bacteriologically in this study. The spectrum of isolated bacteria did not differ significantly between diseased and healthy animals for most species, with Escherichia coli as predominant species with 70.4% positive samples from diseased, and 78.0% positive samples from healthy animals. Furthermore, other Enterobacteriaceae, Staphylococcaceae, Streptococcaceae and Enterococcaceae were isolated both from CM-affected and non-affected animals.The similar bacteria distribution underlines the multifactorial pathogenesis of CM: Only with further adverse--endogen or exogen--factors being present, ubiquitous bacteria from the sow's environment can contribute to the development of clinical signs of infection.