Lipopolysaccharide challenge of the mammary gland in bovine induced a transient glandular shift to anaerobic metabolism

Abstract

Support of milk production in modern dairy cows demands a large proportion of its own metabolic resources, such as glucose, which might be required under stressful situations. The aim of the experiment was to test the hypothesis that acute immune stress shifts oxidative metabolism to glycolysis. Two mammary quarters in 6 Holstein cows were infused with lipopolysaccharide (LPS), whereas the 2 counter quarters served as controls to the treatment. An additional 6 cows were infused with saline and served as running controls. The LPS challenge induced dramatic transient increases in milk lactate (75-fold) and malate (11-fold) concentrations (both markers of glycolysis) at 24h posttreatment. No significant changes in lactate and malate concentrations were recorded in control quarters and control animals, indicating that the effect of LPS was restricted to the treated gland. The LPS challenge induced a dramatic transient decrease in milk yield, and lactose and citrate (a marker of mitochondrial metabolism) secretion at 24h posttreatment. The kinetics were inversely proportional to those of lactate and malate concentrations. Thus, our data suggest that LPS challenge induces acute conversion of epithelial cell metabolism from principally mitochondrial-oxidative to principally cytosolic (glycolytic), which allows the diversion of metabolic resources normally used to synthesize milk to support the immune system. An in vitro bacterial growth test showed that concentrations of lactate, malate, and lactose equivalent to those found in the in vivo experiment delayed and reduced the growth of a pathogenic Escherichia coli strain, suggesting that they play a role in diminution of bacterial multiplication in the mammary gland.

Changes in protein expression profiles in bovine endometrial epithelial cells exposed to E. coli LPS challenge

“…The interactomic analysis ( Figure 6) shows clearly that energy metabolism occupies a very central place in this system. This is consistent with the fact that LPS induced glycolysis which has been constantly reported in literature from other tissues and other species [52][53][54] determines other cell responses thus contributing in many ways to the development of pathological processes.…”

Concomitant lipopolysaccharide-induced transfer of blood-derived components including immunoglobulins into milk

“…This is in contrast to the concentrations of BHBA and LDH, which were always higher in blood than in milk. This observation may be explained by additional lactate production and release during anaerobic metabolism by milk and epithelial cells in the gland (Mayer et al, 1988;Silanikove et al, 2011), whereas the results of experiment 2 show that the lactate produced by cells in the milk appeared to be released from these cells directly after synthesis. In addition, the small size of the lactate molecule (90 Da) as compared with the other investigated constituents may allow for increased transfer from blood into milk.…”

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

“…The layout details of the study are described in Silanikove et al (2011). Briefly, 12 Israeli Holstein heifers with low SCC (27 000 6 5000 cells/ml) and no bacterial detection that produced 33.2 6 3.1 milk/day were divided into two groups of six cows each.…”