Mobilization of neutrophils and defense of the bovine mammary gland

Abstract

-The leucocytes present in normal milk are not very efficient in preventing infection, because very small numbers of bacteria are able to induce infection experimentally. The mobilization of phagocytes from the blood to milk appears crucial in coping with the expansion of the bacterial population in the mammary gland. Important parameters for the outcome of mammary infections are the bactericidal efficiency of neutrophils and the antiphagocytic and cytotoxic properties of the invading bacteria, but several studies have shown that the promptness and the magnitude of the initial recruitment of neutrophils by the infected mammary gland have a profound influence on the severity and the outcome of mastitis. This is an incentive for studying the mechanisms behind the mobilization of neutrophils to the mammary gland. Although milk macrophages may play a role in the triggering of the inflammatory response, studies on several responses to infections at various epithelium sites strongly suggest that epithelial cells are capable of responding to bacterial intrusion and play a major part in the initiation of inflammation. A better knowledge of the effector cells and of the mediators involved in the mobilization of neutrophils could help in devising strategies to modulate this important determinant of milk quality and udder defense. PMN / mastitis / dairy cattle / inflammation

Mathematical Model of the Acute Inflammatory Response to Escherichia coli in Intramammary Challenge

“…The rate of leukocyte mobilization in response to infection (ν) was very low in cows from groups A and C compared with cows from groups B and D. This may be related to the observation by Rainard and Riollet (2003) and Vangroenweghe et al (2004b) that increasing the inoculum of E. coli shortens the lag period before the inflammatory response manifests itself. Indeed, ν corresponds to exponentially distributed waiting times in the blood and is inversely related to the lag period (Hethcote, 2000): If the duration of the migration for each new bacteria is denoted D, then ν ∼ 1/D, since a blood cell migrates into the milk once in D units of time.…”

Innate immunity of the bovine mammary gland

“…The ability of neutrophils to ingest and kill bacteria is pivotal for the control of infection. Many studies have shown both the importance and the limitations of neutrophilmediated defense of the mammary gland, and have explored the possibilities of modulation of the phagocytic defense of the udder [26,123,127,146,177]. Much less is known about the roles of MEC in sensing the pathogens and alerting the immune system, or in direct control of the multiplication of the pathogens through production of antibacterial components (host defense peptides, proteins, lipids or oxygen radicals).…”

Genetic parameters of somatic cell score and lactose content in goat’s milk

“…The results of our earlier study (Bagnicka et al, 2011) showed, that after removing the cytoplasmic particles together with fat, the exfoliated epithelial cells reached up to 67% of total somatic cell count (SCC) in healthy mammary gland. It is strongly evidenced that not only leukocytes but also epithelial cells play a crucial role in the initiation of inflammatory process (Rainard and Riollet, 2003); thus, the high SCC in goat's milk, including exfoliated epithelial cells, might be the reason for the low frequency of clinical mastitis in dairy goats.…”