Lipopolysaccharide challenge of the mammary gland in cows induces nitrosative stress that impairs milk oxidative stability

Abstract

The aim of this work was to study the effects of mastitis induced by intramammary lipopolysaccharide (LPS) challenge on milk oxidative stability, as well as to understand the underlying biochemical processes that cause such changes. LPS challenge was associated with nitric oxide burst from the surrounding mammary epithelial cells and consequently induced nitrosative stress that was induced by the formation of NO 2 d from nitrite by lactoperoxidase. This response was associated with an , 3-fold increased formation of hazardous compounds: nitrotyrosines, carbonyls and lipid peroxides. We sustained the involvement of xanthine oxidase as a major source of hydrogen peroxide. In consistent with previous findings, catalase has been shown to play a major role in modulating the nitrosative stress by oxidizing nitrite to nitrate. The current hygienic quality criteria cannot detect mixing of low-quality milk, such as milk with high somatic cells, and nitrite with high-quality milk. Thus, development of an improved quality control methodology may be important for the production of high-quality milk.Keywords: milk, cow, mastitis, NO and NO 2 d, plasmin system Implication In this study, we show that intramammary treatment with lipopolysaccharide induced nitric oxide burst that was associated with nitrosative stress that reflected the formation of hazardous compounds in milk: nitrotyrosines, carbonyls and lipid peroxides. These changes were associated with impairment in milk quality. Currently, very little is known about the presence of oxidative substances in commercial milk and their industrial and health implications. As mastitis is a prevalent problem in the dairy industry, this study stresses the importance of gaining further information on the effect of different forms of mastitis on milk composition.

Early mammary gland metabolic and immune responses during natural-like and forceful drying-off in high-yielding dairy cows

“…Our results are consistent with previous studies noting that one of the roles of the PL system in milk is the formation of substances that prevent milk clotting during milk stasis or infection (Heegaard et al, 1994;Leitner et al, 2011;Silanikove et al, 2012). The involvement of the PA-PLG-PL system in regulating milk secretion (Silanikove et al, , 2009 and in the induction of mammary gland involution in rodents (Ossowski et al, 1979;Tonner et al, 2000) and ruminants (Shamay et al, 2002(Shamay et al, , 2003(Shamay et al, , 2005Silanikove et al, 2005Silanikove et al, , 2006 is well established.…”

“…Prevention of casein hydrolysis in milk stored within the mammary gland in ANI cows most likely has an important physiological role; namely, prevention of formation of clots during milk stasis, thus preventing uncontrolled (necrotic) inflammation (Heegaard et al, 1994;Leitner et al, 2011;Silanikove et al, 2012).…”

Milk metabolites as indicators of mammary gland functions and milk quality

“…Milk secretion is regulated by milk-borne negative feedback regulation system that responds to abiotic influences, such as milking frequency and heat stress (Silanikove et al 2006(Silanikove et al , 2009 and biotic effects, such as mammary gland infection (Leitner et al 2011a;Silanikove et al 2012). Casein derived peptides from plasmin activity activate the negative feed-back control on milk secretion and alter milk coagulation properties, which is mainly reflected in reduction of lactose concentration in the milk (Silanikove et al 2006;Leitner et al 2011a).…”

Human milk H2O2 content: does it benefit preterm infants?

“…It appears that the H 2 O 2 generation at the time that the milk is ejected has an antibacterial effect. Whether such effect is solely to protect the mother against mastitis, as suggested by some (26), or has an equally important antimicrobial protective role for the neonate is unclear. The data from our study suggest that it may have both effects.…”