Abstract
BackgroundMastitis is the most common disease in dairy cattle and the costliest for the dairy farming industry, as it lowers milk yield and quality. Mastitis occurs as a result of interactions between microorganisms and the individual genetic predispositions of each animal. Thus, it is important to fully understand the mechanisms underlying these interactions. Elucidating the immune response mechanisms can determine which genetic background makes an animal highly resistant to mastitis. We analyzed the innate immune responses of dairy cows naturally infected with coagulase-positive staphylococci (CoPS; N = 8) or coagulase-negative staphylococci (CoNS; N = 7), causing persistent mastitis (after several failed treatments) vs. infection-free (i.e., healthy [H]; N = 8) dairy cows. The expressions of the acute phase protein genes serum amyloid A3 (SAA3), haptoglobin (HP), ceruloplasmin (CP) genes in the tissues most exposed to pathogens— mammary gland cistern lining epithelial cells (CLECs) and mammary epithelial cells (MECs)—were analyzed.ResultsWe found constitutive and extrahepatic expressions of the studied genes in both tissue types. HP expression in the MECs of the CoPS-infected group was higher than in the H group (p ≤ 0.05). Moreover, higher SAA3 expression in the CoPS and CoNS groups than in the H group (p = 0.06 and 0.08, respectively) was found. No differences between SAA3 and HP in CLECs were revealed, regardless of the pathogen type. However, higher expression of CP (p ≤ 0.05) in the CoPS group than in the H group was noted.ConclusionsThe expressions of selected acute phase proteins were similar between CLECs and MECs, which means that CLECs are not only a mechanical barrier but are also responsible for the biological immune response. Our findings agree with the results of other authors describing the immunological response of MECs during chronic mastitis, but the results for CLECs are novel.
Highlights
Mastitis is the most common disease in dairy cattle and the costliest for the dairy farming industry, as it lowers milk yield and quality
The aim of the study was to determine the expressions of serum amyloid A3 (SAA3), HP, and CP genes in Mammary epithelial cell (MEC) and Cistern lining epithelial cell (CLEC) during chronic subclinical mastitis caused by coagulase-positive staphylococci (CoPS) and coagulase-negative staphylococci (CoNS) vs. bacteria-free udder samples to compare the immune response of both tissues to staphylococcal infection
HP expression in the MEC samples infected with CoPS was approximately four times higher than that of the H
Summary
Mastitis is the most common disease in dairy cattle and the costliest for the dairy farming industry, as it lowers milk yield and quality. Elucidating the immune response mechanisms can determine which genetic background makes an animal highly resistant to mastitis. Over the course of many years, breeding programs in the dairy industry have selected mainly for the traits of high milk yield and quality. This selection has resulted in highly productive dairy cattle; these animals are prone to many infections, especially those related to the mammary gland. Toxins released by some bacteria damage the milk-secreting tissue and milk ducts, resulting in reduced milk yield and quality [3]. This damage can even lead to animals becoming unable to produce milk, which in turn results in animal culling [4]
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