Gene expression adjustment of inflammatory mechanisms in dairy cow mammary gland parenchyma during host defense against staphylococci

The aim of the study was to identify differences in the expression of splice variants of the PRMT2, LTF and C4A genes in the mammary glands of healthy dairy cows and those infected with staphylococci. An expression study was conducted on 38 Polish Holstein-Friesian dairy cows who were removed from the herd owing to subclinical and chronic mastitic or reproductive issues. Two days before slaughter, milk samples were taken for microbiological analysis and examined for the presence of bacteria. The mammary gland parenchyma samples with a predominance of secretory tissue were taken; these were divided into three groups according to the health status of the mammary gland: H (without pathogenic bacteria in milk), CoNS (with coagulase-negative staphylococci in milk), and CoPS (with coagulase-positive staphylococci in milk). Two of the investigated genes, LTF and C4A, demonstrated variants unequivocally expressed in infected tissue. Two LTF gene variants were found to be associated with cow health status, and with the type of bacteria causing mastitis (CoPS or CoNS). In addition, the expression of C4A isoforms differed with regard to mastitis etiology groups. The comprehensive evaluation of PRMT2 transcript suggested that the gene may also be involved in course of mastitis: two of four PRMT2 transcripts showed increased expression in the mammary gland of the CoPS group compared to controls. The obtained results are important for the knowledge on the etiology of bovine mastitis. The effects of the identified mastitis-relevant splice variants need to be further explored on the protein level to verify the suitability of splice variants and recognize their contribution towards the disease phenotypes and course.